**4.4 Stellate cells**

Hepatic Stellate cells (HSCs) are another subset with immune function. This relatively small population (5–10% of liver parenchymal cells) resides in the space of Disse and is primarily involved in the storage of retinoid droplets and vitamin A and regulation of blood flow in the sinusoids [32, 46, 47]. In the intact liver, they are quiescent cells. Once activated, they differentiate to myofibroblast and participate in hepatic fibrosis pathogenesis [48]. The second direction of their function is the immunosuppression. Study in animals and humans show that they are effective antigen presenting cells with tolerogenic capacity because of the expression of PD-L1, B7-H7 and Fas/Fas-L pathways [49–51]. When activated, HSCs induce myeloid derived suppressor cells and Foxp3+ regulatory T cells by production of retinoic acid [52] In addition, they produce a broad range of cytokines, like TGF-b, IL-6 etc., and are able to respond to them, thus actively participate in the immunemediated network in the liver [48].


*Article* **Palynological Study of Weed Flora from Potohar Plateau**

**Anwer Usma 1 , Mushtaq Ahmad 1,\*, Muhammad Zafar 1 , Shazia Sultana 1 , Fazal Ullah 2 , Saddam Saqib 3,4 , Asma Ayaz 5 and Wajid Zaman 6,\***

**Abstract:** The pollen morphology of weeds was investigated by scanning electron microscopy (SEM). A morpho-palynological investigation of 18 species of weeds that belongs to 16 angiosperms families was performed using SEM to document distinguishable microscopic features. The main objective of the present study was to provide basic knowledge about morpho-palynological features of weed species that helps delimit the weed flora of the Potohar Plateau. The results show diversity among the qualitative and quantitative characteristics of pollen shape, equatorial and polar axis diameter, the exine's thickness, and the exine's surface ornamentation. The pollen grains were spherical, prolate-spheroidal, oblate-spheroidal, and sub-oblate. The exine ornamentation in most species was reticulate, scarbate, aerolate, faveolate, reticulate-perforate, and reticulate-scabrate. All the species described possessed tricolpate pollen. The variations found in the thickness of the exine and other characters were helpful at the genus and species-specific levels. In accordance with these variations, a taxonomic key was prepared using these characteristics to identify and differentiate weed plant species. SEM images of pollen grains can help delimit the taxa to the species level. This study provides baseline information to distinguish the species of weeds.

**Keywords:** exine sculpturing; palynomorph; pollen grains; scanning electron microscopy; Pakistan

### **1. Introduction**

Weeds are considered undesirable plants competing with crops' growth and development. The growth of weeds in agricultural fields can limit the production of staple crops and causes severe damage to their production [1]. According to Khan et al. [2] weeds grow in cultivated and wild habitats and damage the growing crop plants [3]. Weedy plants threaten human health, welfare, biodiversity, ecosystem services, and food security. Here, weeds are defined as any plants that have detrimental socioeconomic and environmental effects, endanger human health, and jeopardize global food security, biodiversity, and ecosystem services [4]. Weeds play an important role in achieving an ecological balance in a cropping system by supporting different life forms. Throughout the world, major vegetation of weeds belongs to families such as Asteraceae, Poaceae, Amaranthaceae, and Fabaceae. The growth of weeds depends mostly on climatic conditions [5]. In some previously reported studies, the most commonly grown weeds of cotton crops are *Cynodon dactylon*, *Amaranthus viridis*, *Phyla nodiflora*, and *Phragmites australis* [6]. Common weeds of wheat crops are *Phragmites* sp., *Cynodon* sp., *Ranunculus* spp., and *Polypogon* sp. [6]. Similarly, *Achyranthes aspera* is a common weed in sugarcane crops and *Plantago lanceolata* is an important weed in chickpea fields [7]. Weeds belonging to the family Fabaceae can

**Citation:** Usma, A.; Ahmad, M.; Zafar, M.; Sultana, S.; Ullah, F.; Saqib, S.; Ayaz, A.; Zaman, W. Palynological Study of Weed Flora from Potohar Plateau. *Agronomy* **2022**, *12*, 2500. https://doi.org/10.3390/ agronomy12102500

Academic Editor: Rodolfo Gentili

Received: 5 September 2022 Accepted: 11 October 2022 Published: 13 October 2022

**Publisher's Note:** MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.

**Copyright:** © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

obtain essential nutrients from the soil and compete with crops because they gain nutrition faster than other plants [8]. These plants obtain nitrogen from their surroundings and convert it to nitrogen-rich compounds to enhance the growth of essential microorganisms, thereby increasing soil fertility [9]. Many researchers work on the world's weed flora and documented 50 parasitic weeds from Pakistan [10].

In Pakistan, the region of Potohar is located on the northeast side, with an area of approximately 25,000 km2 . Topographically, hilly and plain areas are found in this region [11]. This area also comprises of river Indus and the Jhelum, stretching from the salt range to the foothills of the Himalayas. The Potohar region is between latitude 32◦5 03400 N and longitude 71◦30073" E. The Jhelum plains lie at the lowest altitude, i.e., 825 ft (250 m). Non-native plant species have been introduced into the study area for greenery, which competes with native plant species. The natural vegetation of the Potohar region includes dry deciduous scrubby forests and few species of trees. This area's agriculture purely depends on the monsoon rainfall [12]. The construction of roads, houses, and industries has affected the natural vegetation, resulting in a change in soil composition.

The study of pollen grains plays a vital role in studying plant taxonomy and biodiversity because it helps identify plant species in a particular area [13]. Many taxonomists use different disciplines of plant systematics to identify plant species, such as morphology, anatomical studies, and palynological studies, to find the precise position of plants within taxa [14–19]. On the other hand, the studies of pollen characters are considered the most important tools for classifying and identifying morphologically similar plants. Considerable research has been done on pollen grains in Pakistan and worldwide. Meo and Khan [19] conducted Morpho-palynological studies on weeds for the first time in Rawalpindi, Pakistan. Meo et al. [20] reported the diverse features of weeds and pollen grains belonging to the family Asteraceae. On the other hand, there is not a single document on the morpho-palynology of weeds from the Potohar region of Pakistan. Current research aims to provide detailed information about weeds in the Potohar region of Pakistan, the diversity of their pollen grains, and their exine structure based on qualitative and quantitative characters using SEM as a basis for future studies. A taxonomic key is made based on microscopic characteristics, which helps to distinguish the micro-morphological characteristics to strengthen the identification of complicated weed species. The purpose of the present study was twofold: (1) to determine the pollen fertility of economically important weed species, which will help identify the freely reproducing species for conservation purposes; (2) to the taxonomic identification of the weed species through pollen morphological characteristics.

### **2. Materials and Methods**

### *2.1. Specimen Collection and Plant Identification*

From different sites in the Potohar region of Pakistan (Figure 1), 18 weeds were collected in a single season between August 2021 and November 2021. Approximately three to five samples were collected from each collection site randomly. Table 1 lists the collection site and voucher numbers. After collection, plants were identified either by comparing their morphological characteristics with the flora of Pakistan or by matching their morphology with specimens placed in the Herbarium of Pakistan (ISL). After mounting, the botanical names and author citations were validated using the International Plant Name Index (IPNI) (www.ipni.org (accessed on 7 July 2022)) and accessioned into the Herbarium of Pakistan (ISL) at Quaid-i-Azam University Islamabad, Pakistan.

**Figure 1.** Map of the collection sites of the study area. (Source: Google).

### *2.2. Study of Pollen under an Optical Microscope*

Either dry or fresh plant material extracts pollen grains from anthers. With the help of sharp needles, the anthers were separated from the flowers and placed on glass slides with a single drop of acetic acid, which helps appropriately crush anthers. A slight modification of the method reported by Butt et al. [21] was used to prepare the pollen grains slides. One drop of glycerin jelly was added to the pollen grains, and the extra debris was removed from the glass slide with the help of needles. Glycerin jelly will help stain the pollen grains [21,22]. A cover slip was placed on the pollen grains, and the pollen characteristics were observed by optical microscopy (OM, Leica Dialux 20).

### *2.3. Study of Pollen under a Scanning Electron Microscope*

The pollen grains were prepared for SEM using a slight modification of the methodology reported by Erdtmann [23]. In this method, pollen grains were crushed with 45% acetic acid and were placed on double-sided tape fixed to aluminum stubs using a fine pipette and sputter coated with gold to 150Å. Subsequently, these slides were examined by scanning electron microscopy (Model JEOL JSM- 5910) installed in the Central Resource Library (CRL), Department of Physics, University of Peshawar, Pakistan.

### *2.4. Data Analysis*

The minimum represented the quantitative features (mean ± standard error) and maximum (e.g., 27.7 (85.2 ± 10.8) 105). Five readings of each character were noted for each pollen grain. The quantitative data were noted and processed using SPSS software (version 16) to determine the minimum, maximum, mean, and standard error. These data are very helpful in identifying species and the nature of the different pollen grains. These indices provide information on pollen diameter, colpi and pore size, exine thickness, and polar-to-equatorial ratio.

### *2.5. Percentages of Sterility and Fertility among Pollen*

The pollen fertility was determined using the techniques reported by Khan and Stace [24]. The sterility and fertility percentages were determined using the formula [5,25].

The formula for fertility is given as:

$$\text{Ferribility} = (\text{F}/\text{F} + \text{S}) \times 100\%$$

The formula of sterility is expressed as:

$$\text{Sterality} = (\text{S} / \text{F} + \text{S}) \times 100$$

In the formula, F denotes the number of fertile pollen on a single ocular, while S denotes the number of sterile pollen on one ocular.

### *2.6. Taxonomic Key*

After examining the pollen grains under OM and SEM, different microscopic characteristics were observed, such as pollen, exine ornamentations, and colpi. The taxonomic keys have been developed based on these distinguishing characteristics.

### **3. Results**

A palynological study of 18 weed species from the Potohar Plateau of Pakistan belonging to 12 families was analyzed by OM and SEM. The examined species were explained quantitatively and qualitatively in Tables 2–4. The palynological study showed that weedy species of the study area were quite diverse, and their pollen structure helped identify them. Using these qualitative characters, a taxonomic key was prepared to identify and differentiate the weed plant species (Table 5).

*Agronomy* **2022**, *12*, 2500

**Table 2.** Qualitative data of the pollen of weeds members from the Potohar region of Pakistan.

**Table 4.** Pollen Fertility and Sterility percentages of examined taxa.

**Table 5.** Dichotomous key for identifying the Pothor (Pakistan) weed species based on the pollen morphological characteristics.

### *3.1. Pollen Size, Shape, and P/E Ratio*

Variations in grain shape were observed in equatorial and polar views, size, and pollen shapes. The P/E ratio helps determine the shapes of pollen. Pollen grains of the analyzed species have spherical, prolate-spheroidal, oblate-spheroidal, oblate, and suboblate shapes (Figure 2). The maximum polar diameter was 40.40 µm for *Cissampelos parira* and the minimum was 13.95 µm for *Atriplex stoeksii*. *Cissampelos parira* have a maximum equatorial diameter of 47.20 µm, whereas *Cucumis melo* subsp. *Agrestis* have a minimum of 13.45 µm (Figure 3). Similarly, *Euphorbia grandulata* have a maximum P/E ratio of 1.08, and *Cissampelos parira* have a minimum of 0.85 (Figure 4).

**Figure 2.** SEM images of pollen grains (Equatorial and Polar axis) and pollen surface ornamentation (**A**–**C**), The scale bar represents 5 µm for *Achyranthus aspera* (**D**–**F**), 5 µm for *Aerva javanica* (**G**–**I**), 10 µm for *Amaranthus graecizans* (**J**–**L**), and 5 µm for *Asphodelus tenuifolius*.

**Figure 3.** Comparison of the polar and equatorial diameter (µm) of the pollen of selected plant species.

**Figure 4.** P/E ratio of different species of weeds collected from the Potohar region of Pakistan.

*3.2. Quantitative and Qualitative Characters of Colpi*

All the documented species contain colpi (Figure 5) in their pollen except for *Euphorbia grandulata. Atriplex stoeksii* had a maximum colpi length of 12.30 µm, and *Citharexylum spinosum* had a minimum of 2.25 µm. *Atriplex stoeksii* had a maximum colpi width of 7.20 µm, and *Cissampelos parira* had a minimum of 1.23 µm. All species examined had tricolporate pollen (Figure 6).

**Figure 5.** SEM images of pollen grains (Equatorial and Polar axis) and pollen surface ornamentation (**A**–**C**). The scale bar represents 5 µm for *Atriplex stoeksii* (**D**–**F**), 5 µm for *Boerhivia procumbense* (**G**–**I**), 10 µm for *Brassica furatii* (**J**–**L**), and 10 µm for *Capparis decidua*.

**Figure 6.** Comparison of the Colpi length and width (µm) of selected plant species.

### *3.3. Exine Thickness*

The quantitative pollen characters were observed by SEM and OM (Figure 7). The maximum exine thickness was 2.95 µm for *Chorchorus depressus*, and the minimum was 0.60 µm for *Boerhivia procumbense* (Figure 8).

**Figure 7.** SEM images of pollen grains (Equatorial and Polar axis) and pollen surface ornamentation (**A**–**C**). The scale bar represents 5 µm for *Celosia aegentae* (**D**–**F**), 10 µm for *Cenchrus ciliaris* (**G**–**I**), 5 µm for *Chenopodium murale* (**J**–**L**), and 5 µm for *Chorchorus depressus*.

**Figure 8.** Graph representing the exine thickness of the selected plant species.

### *3.4. Exine Sculpturing*

The exine is the most distinguishing characteristic of the species (Figures 9 and 10). All the pollen grains included in this study had different exine sculpturing. Exine ornamentations are essential features for identifying closely related species and genera with each other. The present study recorded the following ornamentations: reticulate, carbonate, aerolate, faveolate, reticulate-perforate, and reticulate-scabrate. *Achyranthus aspera*, *Celosia aegentae*, and *Citharexylum spinosum* have scarbate exine ornamentations. *Aerva javanica*, *Cleome*

*brachycarpa*, and *Cenchrus ciliaris* have reticulate *ornamentations. Amaranthus gracigiense* and *Cleome viscosa* have scarbate-reticulate. *Asphodelus tenuifolius*, *Euphorbia grandulata*, and *Chenopodium murale* have aerolate, while *Cissampelos parira* and *Cucumis melo* subsp. *agrestis* have perforated exine sculpturing.

**Figure 9.** SEM images of pollen grains (Equatorial and Polar axis) and pollen surface ornamentation (**A**–**C**). The scale bar represents 10 µm for *Cissampelos parira* (**D**–**F**), 5 µm for *Citharexylum spinosum* (**G**–**I**), 5 µm for *Cleome brachycarpa* (**J**–**L**), and 5 µm for *Cleome viscosa*.

**Figure 10.** SEM images of pollen grains (Equatorial and Polar axis) and pollen surface ornamentation (**A**–**C**). The scale bar represents 10 µm for *Cucumis melo* subsp. *agrestis* (**D**–**F**) and 5 µm for *Euphorbia grandulata*.

### *3.5. Fertility and Sterility Percentages*

Table 4 lists the pollen fertility and sterility results. The highest fertility percentage was observed in *Brassica furatii* (97%) and *Cissampelos pareira* (95%), whereas the lowest percentage of fertility was observed in *Aerva javanica* (69%). In the case of sterility, the highest sterile pollen was observed in *Aerva javanica* (30%), while the lowest sterile pollen grains were found in *Brassica furatii* (2%).

### **4. Discussion**

This study examined the role of palynological studies for species identification from the Potohar regions of Pakistan using microscopic techniques. The pollen grains of the weeds varied in shape, aperture, mesocolpium, colpi orientation, and exine ornamentations. Pollen shape, exine sculpturing, spines, number of colpi, and exine thickness of weeds from district Bannu were described by Ahmad et al. [26]. A wide variation in pollen parameters helps differentiate closely related species and genera. The morphological characteristics of pollen provide additional knowledge in plant taxonomy and systematics. The pollen investigated through LM showed great variability in equatorial diameter, polar axis diameter, width and length of colpi, and exine thickness. An extensive range of variations was observed in the pollen morphology of selected species of weeds from the study area showing that the field of palynology plays a vital role in the evolutionary studies of plant species. Variations in exine sculpturing are the diagnostic characteristic in plant systematic studies.

The current study showed that pollen morphological features, particularly the shape of pollen grains, are the major distinguishing feature for identifying weeds species. The present study varies from the previous studies conducted on weeds in terms of the qualitative and quantitative microscopic characteristics. Amaranthaceae were considered the dominant family of weeds in the present research family, followed by Capparaceae. In contrast, the remainder of each family, i.e., Euphorbiaceae, Cucurbitaceae, Verbenaceae, Menispermaceae, Teliaceae, Chenopodiaceae, Poaceae, Asphodelaceae, Brassicaceae, and Nyctaginaceae, contain single species. Pollen grains were in the form of monad, with most species having scabrate exine ornamentation. Similar findings have been reported [27]. Nazish et al. [28] examined the apolar, spheroidal, and scabrate. Micro Echinate pollen ornamentations and sunken pore ornamentations have several pores, ranging from 11 to 23.

Various researchers working on the palynological study of weeds believed that exine ornamentation is the key feature for differentiating taxonomic characteristics [25–30]. Significant differences were observed in the following: the exine thickness, the diameter of the equatorial and polar axis, the size of the colpus, and the number of pores. Palynological studies are used for species identification in plant taxonomy and systematics. The study is linked directly to environmental sciences, molecular biology, plant ecology, pharmaceutical studies, genetics, and aerobiology [13]. In the present study, some pollen has the same aperture conditions, i.e., tricolporate. Khan et al. [31] worked on the pollen morphological features of 16 plants using scanning electron microscopy, which is somewhat similar to our results [32]. They used OM and SEM and described the pollen micro-morphology of 24 wetland weeds. Bolick et al. [33] recorded the exine sculpturing patterns of the pollen of Asteraceae with particular emphasis on evolution. The morphological pollen characteristics can be valuable in solving complications linked with the systematic study of grass. The study of the pollen provides the base for more structures to properly identify the plant species [34]. A palynological study of Asteraceous taxa from the Potohar region helps differentiate species taxonomically [35]. Research work has been done on many aspects of flora. The study area has diverse species, but no work has been performed on the pollen morphological study of weedy species.

Oblate-spheroidal observations were observed abundantly in this study. Most of the colpi orientations noted were sunken and angular. In addition, many prominent, waxy, long, slit-like, and tapering ends of colpi were observed in the pollen. The pollen examined in this study was reticulate in sculpturing, while some contained faveoelate. *Cenhrus*

*ciliaris* contained a single pore in the center of the pollen. Fertility and sterility percentages were determined for the stability of pollen in the study area. The fertility and sterility percentages in pollen grains indicated the relationship among the species' ancestors. The fertility of pollen grains helps identify the genetic variations in flora [36]. Meo et al. [37] reported different shapes of pollen grains of the genus *Cenchrus*. They observed spherical to perbolate shape in *C. pennisetiformis* and spheroidal to subulate in *C. setigerus*. The pollen of this genus is monoporate with psilate exine ornamentation. The position of pores was ectoporous, but endoporus pores were also observed in some cases. Three species, i.e., *C. ciliaris*, *C. biflorus*, and *C. pennisetiformis* are endoporus, whereas *C. setigerus* is ectoporus. The size and shape of pollen grains of the genus *Cenchrus* are used to distinguish the species. It is a valuable tool for calculating the strength of species in a specific region. The pollen examined in this study were oblate, suboblate, oblate-spheroidal, and prolate-spheroidal in shape with the aperture conditions of tricolporate, mesocolpium scarbate, aerolate, reticulate, and perforated exine ornamentations. By contrast, the colpi orientations were long, slit-like, sunken, angular, margins distinct, waxy, rounded, and tapering ends.

Perveen et al. [38] reported the morphological characteristics of pollen of the family Brassicaceae, which have reticulate exine ornamentation compared to the current study results *Brassica furatii* exhibit echinate type of exine surface. Appel and Al-Shehbaz [39] reported that all pollen grains observed in their research exhibit tricolpate with the reticulate type of exine, similar to the present study results in that *Brassica furatii* has tricolpate pollen grains. Moore et al. [40] reported tricolpate pollen with reticulate sculpturing of the exine. Considerable work has been done on weeds of the family Brassicaceae by [41,42], and it was concluded that the shape of the lumen is the most significant characteristic in the delimitation of different species in the family Brassicaceae.

Weed flora has been documented previously by many researchers. Reference [43] reported 73 weed species that are medicinally important and utilized for treating different diseases of both human beings and animals. These weed species help manufacture different plant yields and the indigenous sellers of crude drugs of plants. The pattern of distribution, richness, and abundance of weed species (e.g., *A. viridis*, *P. lanceolata*, *D. annulatum*, *V. thapsus*, and *C. dactylon*) depend on the different environmental conditions, such as CaCO3, pH, organic matter, soil texture, phosphorous, electrical conductivity, and concentration of nitrogen. Rafay et al. (2014) reported that weeds play a significant role in the agroecosystem by increasing the cropping system's environmental heterogeneity and floral diversity. Williams and Kremen [44] reported that non-crop plants support different types of invertebrates because many insects depend upon specific weeds for survival.

On the other hand, weeds play a serious role in crop production and threaten cultivated lands because they use soil nutrients. Weeds adversely affect the yield and growth of crop plants because of the nutrient demand. Weed vegetation is eliminated using different control measures, e.g., chemical approaches, cultural procedures, and biological mechanisms. In cultural operations, weeds are thrown away from the rice field [43]. Identification of different weed species and farming practices plan with revised management has been suggested [45].

The results of the present study of this family were compared with previously published data showing that these species are quite similar to the previously reported species, with few variations. Butt et al. [32] described the palynological study of weeds for pollen features, i.e., pore number, the diameter of the equatorial and polar axis, length, width of colpi, and its outline, which are very helpful for classifying species in plant taxonomy. According to the results, these characteristics are insufficient for species identifications; sometimes, many species hold similar features. The most vital characteristics are exine thickness, mesocolpium, and aperture conditions. The study also provides information on the delimitation of species from the genus to the family level. Nevertheless, further research will be needed to achieve more conclusive results using more cosmopolitan species.

### **5. Conclusions**

A microscopic study of weeds and pollen grains collected from the Potohar region of Pakistan has been documented. The studied pollen helps identify the weed plant species, genus, and family. Eighteen plant species belonging to 16 families were investigated in the present research; the morpho-palynological characters were investigated quantitatively and qualitatively. In the case of palynomorph, major variations were observed in size, appearance, and diameter of the equatorial and polar axis, the wideness of the exine, and its ornamentation. The pollen traits were proven to have taxonomic potential to support and strengthen the systematics of this subfamily. The dominant family of weeds in the present study is Capparaceae followed by Amaranthaceae, and the oblate shape of pollen is commonly observed in weeds. All the pollen grains were tricolpate with scabrate exine sculpturing. The current study was compared with previous studies, confirming that the pollen morphology under OM and SEM provides important information for identifying weeds species. The microscopic features provide considerable knowledge and have important information for correctly identifying flora. This study also contributed to collecting the data on weeds plants, i.e., preventive, therapeutic, and diagnostic potential. Further phylogenetic, pharmacognosy, and molecular studies are recommended for weed plants in the future to support and strengthen the systematics of weed flora.

**Author Contributions:** A.U., M.A., M.Z. and S.S. (Shazia Sultana) designed the research, performed the experiments, and analyzed the data., W.Z., F.U., A.A. and S.S. (Saddam Saqib) visualization, methodology, writing—review and editing, investigation, re-sources, data curation. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Data Availability Statement:** Not applicable.

**Acknowledgments:** All the authors are thankful to (CRL) Central resource library, Department of the Physics University of Peshawar, for providing the facility of Scanning Electron microscopy.

**Conflicts of Interest:** The authors declare no conflict of interest.

### **References**


**Application of Fractal Analysis While Designing of Family of Spacecraft for Needs of Space Industry**

Andrew V. Sedelnikov and Ksenia I. Potienko

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/67922

#### Abstract

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This paper deals with methods of fractal analysis, which allow creation of a line of spacecraft from different classes as addition to classical methods for needs of space industry. It is shown that the fractal analysis that widens opportunities of classical methods can become a base for solution of the modern problems of space technologies. Besides, the results of fractal analysis in this chapter are practically valued recommendations for designing of the line, algorithms of control over equipment to measure microaccelerations and of majority control over measuring data. It clearly demonstrates potential and applicability of methods of fractal analysis in practice.

Keywords: fractal analysis, fractal property, spacecraft, microaccelerations, majority control

## 1. Introduction

Space technologies have given a lot of new materials and medicines with unique features. For instance, semiconducting germanium for purposes of radio industry was firstly gotten under space conditions. Its purity achieved 99.9999%. Ultrastrong and thermostable monocrystals for development of blades of a turbine for aviation and rocket engines were also firstly grown in space laboratories. The metal foam is of great interest for engineering industry. It has a weak structure and combines high durability with lightness.

Such unique features can be achieved for materials, which are developed out of the field of terrestrial gravity. The absence of the field allows thorough mixing of melted metal with air for creation of foam metal with weak structure or exclusion of admixtures from the melt to significant reduction of crystallization centers to get large monocrystals, etc. Such technological processes, which require almost absolute absence of force action for their successful realization, are called as gravity-sensitive processes.

© 2017 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

The best resources and significant funds were wasted for realization of ambitious space projects. For instance, in USA, it was developed and realized grand project of space laboratory "Skylab." The laboratory was placed into near-earth orbit by legendary carrier rocket "Saturn-5" on 14 May 1973 for realization of more than 300 series of different experiments connected with cross-cutting technologies [1]. There were realized growth of monocrystals, experiments on directed crystallization and others among gravity-sensitive processes. The project "Skylab" was unprecedented in the scales of funds—its budget is considered to be 2.5 bn of dollars.

The large numbers of gravity-sensitive processes in Russia were conducted during realization of large-scale project of orbital complex "MIR." This platform was prepared better for technological and biomedicine experiments than space laboratory "Skylab." "Skylab" was the one big laboratory but "MIR" represented the complex of separated orbital modules with detail specialization of experiments conducted in each module. During realization of the project "MIR," the experience of "Skylab" was taken into account as well as finished by that moment Russian projects of manned orbital stations of the "Salut" series. For providing the research part of the project, the unique equipment was created such as the ovens "Krater-VM" and "Gallar," the complex to control conducting of experiments "Onyx," glass oven "Optyzon" experimental devices "Katalyzator" and "Titus," gauges "Alice" and others.

Evidently that high pace of development of scientific-technical progress today and also significant changing of earth technologies are the results of large-scale space projects. It seemed like space technologies would make a real revolution, but revolution was postponed due to small knowledge of the new conditions which determined realization of technological processes.

Investigations showed that it is wrong to believe that there is absolute weightless into inner environment of space laboratory. An influence of outer (gravitational field, aerodynamic drag, light pressure, etc.) and inner (running of operating elements, proper oscillations of big elastic elements, running of system of orientation, and control of spacecraft's movement) disturbing factors causes a microacceleration field in inner environment.

It influences the results of gravity-sensitive processes negatively. Today, the row of such processes, which demand microacceleration level no higher than 10.7 g for their successful realization, has been already developed. However, modern developmental stage of space technic has not yet allowed realization of the processes on a board of space laboratory. It is necessary to investigate the structure and nature of microaccelerations, to find out their new features to provide the necessary level for successful realization of gravity-sensitive processes. It is necessary to understand that requirements for microacceleration level will become tougher to the extent of development of space technologies.

Investigations show that microacceleration field as the test subject has several features, which significantly complicate its investigation. One of the features consists in overloads of microaccelerometers during launching of spacecraft/these overloads can achieve 10 g. It is approximately in 7–8 orders bigger than microacceleration values [2]. Such situation significantly complicates getting the reliable experimental data using onboard gauges. The following situation [3] was registered when testing of Canadian vibration isolator MGIM (microgravity isolation mount) during 2 years in orbital complex "MIR" and also during the flight of space shuttle STS-85 by gauges. In one series of experiments which were considered to be successfully realized, the oscillation amplitude inside was protected by the MGIM area that was significantly lower than the outside area. However, in another series of experiments which were marked as unsuccessful, the oscillation amplitude inside the protected area was higher than the outside area. The values of amplitudes (in successful and unsuccessful series) differed more than in 20 times. Later, during measurements of microaccelerations on the board of specialized technological spacecraft "FOTON-11" by French equipment BETA, the situation was similar [4]. Microaccelerometers, installed at different axes of bound coordinate system, showed data that differed more than 20 times. Nevertheless, there were not any obvious causes for it. Sazonov et al. [4] suppose that the software of BETA equipment was applied incorrectly. However, failure of some microaccelerometers is quite possible too. It is also remarkable that the equipment was not applied more on the spacecraft from "FOTON" series. Thus, the reliable way to control adequacy of microaccelerometers on the operational stage of spacecraft, after launching overloads, is required.

The second important feature of microacceleration field is impossibility to measure microaccelerations directly like temperature or angular velocity. That is why the measuring results are indirect estimations based on different methods. The gauges created according to the methods dive only qualitative-similar data. It significantly complicates the investigation of microacceleration field too. For instance, tested on orbital complex "MIR," complex of gauges which included "Alice-2" (MEMS-technologies) and "DACON" (convection sensor) showed that "DACON" is insensitive to high-frequency microaccelerations. Although, "Alice-2" managed to register it [5]. The changing of working body of modification of convection sensor "DACON-M" allowed changing of characteristics of the device [6]. The equipment "GRAVI-TON" based on measurement of magnetic field of the Earth and also row of other gauges were developed [7]. All mentioned facts show that experimental data are the results of mathematical modeling but not of the pure experiment. Thus, the role of mathematical modeling for investigation of microaccelerations is very important and stimulates application of new mathematical methods, particularly, of fractal analysis for investigation of microacceleration field.

## 2. Main part

The best resources and significant funds were wasted for realization of ambitious space projects. For instance, in USA, it was developed and realized grand project of space laboratory "Skylab." The laboratory was placed into near-earth orbit by legendary carrier rocket "Saturn-5" on 14 May 1973 for realization of more than 300 series of different experiments connected with cross-cutting technologies [1]. There were realized growth of monocrystals, experiments on directed crystallization and others among gravity-sensitive processes. The project "Skylab" was unprecedented in the scales of funds—its budget is considered to be

The large numbers of gravity-sensitive processes in Russia were conducted during realization of large-scale project of orbital complex "MIR." This platform was prepared better for technological and biomedicine experiments than space laboratory "Skylab." "Skylab" was the one big laboratory but "MIR" represented the complex of separated orbital modules with detail specialization of experiments conducted in each module. During realization of the project "MIR," the experience of "Skylab" was taken into account as well as finished by that moment Russian projects of manned orbital stations of the "Salut" series. For providing the research part of the project, the unique equipment was created such as the ovens "Krater-VM" and "Gallar," the complex to control conducting of experiments "Onyx," glass oven "Optyzon" experimental devices "Katalyzator" and

Evidently that high pace of development of scientific-technical progress today and also significant changing of earth technologies are the results of large-scale space projects. It seemed like space technologies would make a real revolution, but revolution was postponed due to small knowledge of the new conditions which determined realization of technological processes.

Investigations showed that it is wrong to believe that there is absolute weightless into inner environment of space laboratory. An influence of outer (gravitational field, aerodynamic drag, light pressure, etc.) and inner (running of operating elements, proper oscillations of big elastic elements, running of system of orientation, and control of spacecraft's movement) disturbing

It influences the results of gravity-sensitive processes negatively. Today, the row of such processes, which demand microacceleration level no higher than 10.7 g for their successful realization, has been already developed. However, modern developmental stage of space technic has not yet allowed realization of the processes on a board of space laboratory. It is necessary to investigate the structure and nature of microaccelerations, to find out their new features to provide the necessary level for successful realization of gravity-sensitive processes. It is necessary to understand that requirements for microacceleration level will become

Investigations show that microacceleration field as the test subject has several features, which significantly complicate its investigation. One of the features consists in overloads of microaccelerometers during launching of spacecraft/these overloads can achieve 10 g. It is approximately in 7–8 orders bigger than microacceleration values [2]. Such situation significantly complicates getting the reliable experimental data using onboard gauges. The following situation [3] was registered when testing of Canadian vibration isolator MGIM (microgravity

factors causes a microacceleration field in inner environment.

tougher to the extent of development of space technologies.

2.5 bn of dollars.

"Titus," gauges "Alice" and others.

98 Fractal Analysis - Applications in Physics, Engineering and Technology

There are a lot of different classifications of microaccelerations. For instance, microaccelerations are divided into quasi-static (low-frequency) and vibrational (high-frequency) according to its frequency. According to the nature of the source, they are divided into inner and outer. There is offered the classification according to the method of their control [8] because it is important to provide and control designed microacceleration level while creating new space technic.

Microaccelerations can be divided into three groups in accordance with the classification feature:

The constructive component is of the greatest interest among the three components because it is connected with construction of the spacecraft and the way of orbital control from the early stages of designing and development.

In a way, the constructive component of microacceleration field of the inner environment of spacecraft is formed while creating the constructional layout of space laboratory and developing the system of its orbital orientation in the early stages of designing.

Constructive component, which often mainly contribute to microacceleration field of inner environment, should be controlled for achieving of favorable microacceleration level.

Investigations of constructive component of microacceleration field show [9] that it has the feature which can be compared with fractal quality of scaling. For instance, the scaling of cosine part of Weierstrass-Mandelbrot function (WMF):

$$\text{Re}W(t) = \mathcal{C}(t) = \sum\_{n = -\infty}^{\infty} \frac{1 - \cos b^n t}{b^{(2-D)n}} \tag{1}$$

where D is fractal dimension and b is scaling parameter of WMF by the replacement of t to b4 t, and C(t) to b4(2-D)C(t) does not change the form of function (Figure 1).

According to the scale invariance of differential equations which describe oscillations of big elastic elements of spacecraft time-dependence of microaccelerations has the similar feature. However, not graph of function but the spacecraft itself is scaled: its sizes and inertia-mass parameters (Figure 2).

The results are described in detail below. For investigation of the fractal quality of constructive component, the simple scheme of spacecraft was chosen with the purpose of qualitative demonstration of the quality. The spacecraft represents the central absolutely rigid body that is rigidly attached to its elastic elements (Figure 3).

The elastic elements are considered to be the Euler-Bernoulli beams to simplify the investigation process. The estimation of microaccelerations using such models gives a bit overevaluated results [10].

The vibrations of elastic element are caused by inner and outer disturbing factors on spacecraft (Figure 3). Just the vibrations make the most important contribution to constructive component of microacceleration field. The impulse firing of engines of orientation and control of orbital motion of spacecraft [11], permanent running of operational equipment [2, 12] or the other factors, including the outer, can be considered to be the sources of vibrations.

Application of Fractal Analysis While Designing of Family of Spacecraft for Needs of Space Industry http://dx.doi.org/10.5772/67922 101

Figure 1. The self-affine property of the cosine part of Weierstrass-Mandelbrot function.

The constructive component is of the greatest interest among the three components because it is connected with construction of the spacecraft and the way of orbital control from the early

In a way, the constructive component of microacceleration field of the inner environment of spacecraft is formed while creating the constructional layout of space laboratory and develop-

Constructive component, which often mainly contribute to microacceleration field of inner

Investigations of constructive component of microacceleration field show [9] that it has the feature which can be compared with fractal quality of scaling. For instance, the scaling of

where D is fractal dimension and b is scaling parameter of WMF by the replacement of t to b4

According to the scale invariance of differential equations which describe oscillations of big elastic elements of spacecraft time-dependence of microaccelerations has the similar feature. However, not graph of function but the spacecraft itself is scaled: its sizes and inertia-mass

The results are described in detail below. For investigation of the fractal quality of constructive component, the simple scheme of spacecraft was chosen with the purpose of qualitative demonstration of the quality. The spacecraft represents the central absolutely rigid body that

The elastic elements are considered to be the Euler-Bernoulli beams to simplify the investigation process. The estimation of microaccelerations using such models gives a bit overevaluated

The vibrations of elastic element are caused by inner and outer disturbing factors on spacecraft (Figure 3). Just the vibrations make the most important contribution to constructive component of microacceleration field. The impulse firing of engines of orientation and control of orbital motion of spacecraft [11], permanent running of operational equipment [2, 12] or the other

factors, including the outer, can be considered to be the sources of vibrations.

X∞

1 � cosbnt

bð2�DÞn ð1Þ

t,

n¼�∞

environment, should be controlled for achieving of favorable microacceleration level.

ReWðtÞ ¼ CðtÞ ¼

and C(t) to b4(2-D)C(t) does not change the form of function (Figure 1).

Extraordinary situations, connected with failure of equipment, are also in the list.

equipment for passive and active orientation, vital activity of crew, etc.

ing the system of its orbital orientation in the early stages of designing.

cosine part of Weierstrass-Mandelbrot function (WMF):

is rigidly attached to its elastic elements (Figure 3).

stages of designing and development.

100 Fractal Analysis - Applications in Physics, Engineering and Technology

parameters (Figure 2).

results [10].

Proper frequency when cantilever attaching is performed by the following formula:

$$
\omega\_i = \frac{\eta\_i^2}{l^2} \sqrt{\frac{\text{EI}}{\mu'}} \tag{2}
$$

where ηi is i-equation root, cosηi chηi þ 1 ¼ 0; i is number of oscillation mode; l is length; EI is flexural rigidity; and µ is linear mass of elastic element.

Linear mass and rigidity are constant for the designed material. Roots ηi are also constant. Thus, frequency is the function of beam's length. So, double decrease of the length will lead to fourfold increase of frequency or fourfold decrease of period of vibrations. At that, microacceleration's amplitude will change. Beam with less length and mass will create less microaccelerations when central body of space laboratory will be permanent. Tangential inertia force influences each point of a beam:

Figure 2. The feature of constructive component of microacceleration field when scaling of inertia-mass parameters and sizes of spacecraft.

$$d\Phi\_t = \mu \frac{M}{I} (\mathbf{x} + \mathbf{s}) d\mathbf{x},\tag{3}$$

where M is moment of orientation engine, s is projection of radius vector of fixing point of elastic element relatively to center of mass of space laboratory on x-axes (Figure 3) and I ¼ I0 þ 1 3 μι3 þ μιs2 —inertia moment of space laboratory. At that, beam is considered to be homogeneous. I0 is inertia moment of central body. Then, the general inertia force of elastic element is:

Application of Fractal Analysis While Designing of Family of Spacecraft for Needs of Space Industry http://dx.doi.org/10.5772/67922 103

$$\Phi\_{\mathbf{r}}(l) = \mu \frac{M}{2I} (\mathbf{x} + \mathbf{s})^2 = \frac{\mu}{2} \frac{M(l+s)^2}{I\_0 + \left(\frac{1}{3}\mu s^3 + \mu s^2\right)}.\tag{4}$$

When length of elastic element decreases in two times, this formula has the following appearance:

$$\mathfrak{Op}\_{\pi}\left(\frac{l}{2}\right) = \frac{\mu}{2} \frac{M\left(\frac{l}{2} + s\right)^2}{I\_0 + \left(\frac{1}{24}\mu s^3 + \mu \frac{t}{2}s^2\right)}.\tag{5}$$

Equations (4) and (5) give more than double decrease of the real tangential inertia force of spacecraft "NIKA-T" [13] after substitution of basic parameters of the spacecraft. At that, energy losses are not taken into account there. It means the reduction of amplitude of reaction force of embedding. The reaction force to the spacecraft's body and causes microaccelerations by its moment around the spacecraft's center of mass.

Losses of energy in the attaching lug of elastic element are not taken into account. It means reduction of the amplitude of reaction force of embedding. The reaction force transmits to the body pf spacecraft and causes microaccelerations, because it creates momentum around center of mass of spacecraft. Mass and size of spacecraft should be reduced so as angular accelerations from tangential inertia forces are similar to get initial amplitude of microaccelerations. It is considered to be a condition of constancy of the form of constructive component caused by vibrations of elastic element (Figure 2). Thus:

$$\varepsilon(l) = \frac{M[\Phi\_{\tau}(l)]}{I} = \frac{\Phi\_{\tau}(l)s}{I} = \frac{\mu}{2} \frac{M(l+s)^2 s}{\left(l\_0 + \frac{1}{3}\mu l^3 + \mu s^2\right)^2} \tag{6}$$

$$\varepsilon\left(\frac{l}{2}\right) = \frac{M[\varPhi\_{\tau}\left(\frac{l}{2}\right)]}{I\_{1}} = \frac{\varPhi\_{\tau}(l)s\_{1}}{I\_{1}} = \frac{\mu}{2} \frac{M\left(\frac{l}{2} + s\_{1}\right)^{2}s\_{1}}{\left(I\_{10} + \frac{1}{24}\mu\mu^{3} + \mu\frac{t}{2}s\_{1}^{2}\right)^{2}}.\tag{7}$$

Figure 3. Circuit of space laboratory.

dФτ ¼ μ

and I ¼ I0 þ 1

sizes of spacecraft.

force of elastic element is:

102 Fractal Analysis - Applications in Physics, Engineering and Technology

M

Figure 2. The feature of constructive component of microacceleration field when scaling of inertia-mass parameters and

where M is moment of orientation engine, s is projection of radius vector of fixing point of elastic element relatively to center of mass of space laboratory on x-axes (Figure 3)

ered to be homogeneous. I0 is inertia moment of central body. Then, the general inertia

3 μι3 þ μιs2 —inertia moment of space laboratory. At that, beam is consid-

I ðx þ sÞdx, ð3Þ

Inertia moment of central body is e according to the formula: Ii0 ¼ miR2 i 4 , where mi and Ri—mass and radius of central body for i-iteration accordingly.

The initial spacecraft determined by scheme on Figure 3 is considered to be the zero iteration (i ¼ 0). The spacecraft with elastic element length of which is less than two times the initial length l1 ¼ ð0:5Þ 1 l0 � � and inertia-mass parameters and sizes are matched so as angular accelerations in Eqs. (6) and (7) are equal (εðlÞ ¼ ε l 2 � �) is considered to be the first iteration. The spacecraft with length of elastic element which is more than two times the initial length (l�1 ¼ ð0:5Þ �1 l0) and inertia-mass parameters and sizes are matched so as angular accelerations in Eqs. (6) and (7) are equal εðlÞ ¼ ε l 2 � � � � is considered to be the minus first iteration. Thus, there is view that the following change is lower than the elastic element while iterations:

$$l\_i = \left(\frac{1}{2}\right)^i l\_0. \tag{8}$$

Besides, the values of i can be positive (reduction of spacecraft's sizes relatively to initial) as well as negative (increase of spacecraft's sizes relatively to initial).

It is necessary to question: Would inertia-mass parameters of spacecraft change as synchronously so length of elastic element does? Is formulation of changing low of these parameters in the form similar to Eq. (8) possible? If the answers to the questions are positive, there are quality which is similar to the self-affine property of the cosine part Weierstrass-Mandelbrot function Eq. (1). Oppositely, if parameters will change disproportionally and angular accelerations would not be equal after each iteration, the analogy with fractal properties would be inapplicable. So, it is impossible to apply fractal functions for study and modeling of microacceleration field.

To search answers for these questions, the generalized parameter that characterizes inertiamass features of spacecraft was formed [14]:

$$z = \frac{\sum\_{i=1}^{N} m\_i}{m\_0 + \sum\_{i=1}^{N} m\_i} \,\prime \tag{9}$$

where m0 is mass of central body; mi is mass of i-elastic element and N, is number of elastic elements of spacecraft.

The generalized parameter in Eq. (9) has the following form for investigated situation:

$$z = \frac{m\_1}{m\_0 + m\_1}.\tag{10}$$

In fact, generalized parameter z characterizes mass percent of elastic elements to the total mass of spacecraft. The equality of angular accelerations is the condition of constancy of appearance of time-dependence of microaccelerations which correspond to Figure 2:

$$
\varepsilon(l\_{-1}) = \varepsilon(l\_0) = \dots = \varepsilon(l\_l). \tag{11}
$$

The value l obeys the law in Eq. (8). It is necessary to provide equality of Eq. (11) without changing of geometrical parameters of central body of spacecraft (radius and coordinates of fixing points of elastic element). In fact, it means multiple changing of elastic element's length and mass of central body to provide in Eq. (11) independently from sizes of spacecraft's body. Results of these actions for basic parameters of spacecraft "NIKA-T" (l0 ¼ 2 m, µ ¼ 10 kg/m, М ¼ 1 Н m, m0 ¼ 6000 kg) are shown in Figure 4. The following equation plays the role of coefficient, which determines multiplicity of changing of generalized parameter z:

$$kz\_i = \frac{z\_{i-1}}{z\_i}.\tag{12}$$

According to Figure 4, kzi coefficients significantly differ for different iterations. However, it is absolutely predictable, because changing of mass was conducted while permanent size of spacecraft's central body. Only length of elastic element was changed accordingly to the law in Eq. (8). It is hard to imagine significant changing of mass of spacecraft without changing of radius of central body. Thus, search of answers to be mentioned above questions after conducted in which the analysis will be leaded to the following. Is it possible to realize such changing law of central body's radius to achieve the following:

Inertia moment of central body is e according to the formula: Ii0 ¼ miR2

The initial spacecraft determined by scheme on Figure 3 is considered to be the zero iteration (i ¼ 0). The spacecraft with elastic element length of which is less than two times the initial

2

l0) and inertia-mass parameters and sizes are matched so as angular accelerations

spacecraft with length of elastic element which is more than two times the initial length

there is view that the following change is lower than the elastic element while iterations:

li ¼ 1 2 � �i

Besides, the values of i can be positive (reduction of spacecraft's sizes relatively to initial) as

It is necessary to question: Would inertia-mass parameters of spacecraft change as synchronously so length of elastic element does? Is formulation of changing low of these parameters in the form similar to Eq. (8) possible? If the answers to the questions are positive, there are quality which is similar to the self-affine property of the cosine part Weierstrass-Mandelbrot function Eq. (1). Oppositely, if parameters will change disproportionally and angular accelerations would not be equal after each iteration, the analogy with fractal properties would be inapplicable. So, it is impossible to apply fractal functions for study and modeling of microacce-

To search answers for these questions, the generalized parameter that characterizes inertia-

XN i¼1 mi

m0 þXN

where m0 is mass of central body; mi is mass of i-elastic element and N, is number of elastic

The generalized parameter in Eq. (9) has the following form for investigated situation:

z ¼ m1 m0 þ m1

In fact, generalized parameter z characterizes mass percent of elastic elements to the total mass of spacecraft. The equality of angular accelerations is the condition of constancy of appearance

i¼1 mi

z ¼

of time-dependence of microaccelerations which correspond to Figure 2:

2

well as negative (increase of spacecraft's sizes relatively to initial).

and inertia-mass parameters and sizes are matched so as angular accel-

� � � � is considered to be the minus first iteration. Thus,

and radius of central body for i-iteration accordingly.

104 Fractal Analysis - Applications in Physics, Engineering and Technology

erations in Eqs. (6) and (7) are equal (εðlÞ ¼ ε l

length l1 ¼ ð0:5Þ

(l�1 ¼ ð0:5Þ

leration field.

elements of spacecraft.

1 l0

in Eqs. (6) and (7) are equal εðlÞ ¼ ε l

mass features of spacecraft was formed [14]:

� �

�1

i

� �) is considered to be the first iteration. The

l0: ð8Þ

, ð9Þ

: ð10Þ

εðl�1Þ ¼ εðl0Þ ¼ … ¼ εðliÞ: ð11Þ

4 , where mi and Ri—mass

According to the investigations, conducted for spacecraft, shown in Figure 3, such law exists. The sample dispersion of values kzi was analyzed for different values kRi ¼ Const, using the

Figure 4. Changing dynamic of spacecraft's mass and generalized parameter if Eq. (11) is prominent for iterations �2 ≤ i ≤ 4.

same quantitative data, which correspond to basic parameters of spacecraft "NIKA-T." The results of quantitative analysis are shown in Figure 5.

Minimum of the dispersion is achieved closely to the value kR ¼ 0:4. Thus, changing law of radius of spacecraft's central body, which is analogical to Eq. (8), has the following form:

$$R\_i = (0.4)^i R\_0. \tag{13}$$

At that, generalized parameter z changes accordingly to approximated law:

$$z\_i = (1.873)^i z\_0. \tag{14}$$

Then, changing dynamic of the parameters with taking into account radius's changing, which is analogical to Figure 4, has the form shown in Figure 6.

Figure 5. Sample dispersion of values kzi in dependence on kR.

Figure 6. Changing dynamic of spacecraft's mass and generalized parameter when Eq. (11) is right taking into account changing of spacecraft's radius for iterations �2 ≤ i ≤ 4.

Consequently, we can confirm that constant scaling coefficients of central body's radius and generalized parameter z are found for viewed example of spacecraft. These coefficients provide invariance of appearance of dependence of constructive component of microaccelerations on time (Figure 2). The laws in Eqs. (8), (13) and (14) are realized simultaneously.

same quantitative data, which correspond to basic parameters of spacecraft "NIKA-T." The

Minimum of the dispersion is achieved closely to the value kR ¼ 0:4. Thus, changing law of radius of spacecraft's central body, which is analogical to Eq. (8), has the following form:

i

i

R0: ð13Þ

z0: ð14Þ

Ri ¼ ð0:4Þ

zi ¼ ð1:873Þ

Then, changing dynamic of the parameters with taking into account radius's changing, which

Figure 6. Changing dynamic of spacecraft's mass and generalized parameter when Eq. (11) is right taking into account

At that, generalized parameter z changes accordingly to approximated law:

results of quantitative analysis are shown in Figure 5.

106 Fractal Analysis - Applications in Physics, Engineering and Technology

is analogical to Figure 4, has the form shown in Figure 6.

Figure 5. Sample dispersion of values kzi in dependence on kR.

changing of spacecraft's radius for iterations �2 ≤ i ≤ 4.

In this case, the fractal quality of constructive component of microaccelerations can be determined as invariance of the form of time-dependence of microaccelerations' module whole scaling of spacecraft on generalized parameter z.

Scaling coefficients among axes of graph of time-dependence of microaccelerations are equal to 0.25 among time-axis and one among microacceleration-axis. Thus, the graph does not change its appearance as well as values of microaccelerations. It is very important for providing of required microacceleration level in the area with technological equipment. Graph compression among time-axis is explained by fourfold increase of frequency of proper oscillations of a beam while double reduction of its length.

There is used the simple scheme of spacecraft to show scaling property without hard computing in mentioned case. The same situation would be for more complicated scheme which is close to real spacecraft.

Scaling coefficients of mass km and radius kR are determined accordingly to the chosen scaling coefficient of length kl ¼ 0.5 in such a way as generalized parameter z was changed according to the law:

$$
\mathbf{z}\_i = \mathbf{k} \mathbf{z}\_i \mathbf{z}\_{0\prime} \tag{15}
$$

where z0 is value of spacecraft's generalized parameter while i ¼ 0, i.e., for basic spacecraft, which is the base for the future different types of spacecraft.

Application of another changing law of the length in place of Eq. (8) also does not change anything fundamentally. In this case, scaling coefficient of time-dependence of microaccelerations among time-axis will differ from 0.25.

It is worth to mention that only constructive component of microacceleration field has this property. Neither metastable even more nor random components according to classification [8] meets the fractal property. Metastable component is determined by the sphere of cosmic space where spacecraft operates. The component forms the part of microacceleration field, which is caused by outer disturbing factors. This disturbance, such as aerodynamic drag and light pressure, can change when spacecraft is scaled and can remain unchanged, such as magnetic disturbance. That is why metastable component has no scaling property.

The same thing is for random component. Appearance of emergency situations, failure of different equipment or random oscillations of basic parameters of outer disturbing impact on spacecraft is not connected with its scaling. On the other hand, probability of hitting of micrometeorite to spacecraft is connected with square of its outer surface and will change with scaling. Thus, we can claim that random component has no scaling property.

However, the remarks relatively to metastable and random components do not reduce the value of the found property of constructive component of microacceleration field. Actually, just constructive component is determined already in early developmental stages of spacecraft. This component characterizes dynamical features of spacecraft's constructional layout and takes into account the algorithms and ways to orient its orbital motion. Only constructive component can be influenced by using of the total power of different methods to provide and control microacceleration level in the area with technological equipment. This power can be significantly strengthened by application of fractal analysis as well as classical.

Scaling property of constructive component of microacceleration field allows application of methods of fractal analysis for designing of technological spacecraft as well as for correct data processing of microacceleration measurements, finding of failures of gauges and recovery of lost measuring data. It is very hard to do all of these only on the base of classical methods of analysis. The perspectives of addition of classical methods described by fractal property of constructive component of microaccelerations are mentioned below.

The launchings of spacecraft with specialized technological purposes happen with big intervals on the modern stage of space technologies' development. For instance, spacecraft "FOTON – M" No 3 was launched in 14 September 2007 and the following spacecraft "FOTON – M" No 4—only after almost 7 years in 19 July 2014. Thus, it is evident that it is impossible to arrange space experimental batch manufacturing only on the base of specialized space technic. One of the perspective ways to solute the problem is the wide application of small spacecraft. One start of carrier rocket of middle class is able to provide launching of tens small spacecraft to their orbits. Series-produced homotypic spacecraft can provide meeting of similar conditions for realization of concrete gravity-sensitive process. Continuous production can be organized using project launchings with small spacecraft as additional load. However, only application of small spacecraft would significantly limit production value. Limits on mass would not allow placement on spacecraft's board more than 100 kg of technological equipment and materials for production.

The approach, which includes advantages of spacecraft with specialized technological purposes and small spacecraft, is necessary to meet requirements of experimental batch production in space. This approach should integrate opportunities of these ways of space technic's development: regularity of launchings and significant scales of production while maintenance of equal favorable conditions for realization of gravity-sensitive processes. It is evident that such task statement leads to necessity to create line of spacecraft from different classes which meet these equal conditions. The scaling property of constructive component of microaccelerations should be applied to solute this task. For this purpose, the mathematical model of microaccelerations should be built using fractal function. Fractal model of microaccelerations worked out in the articles [15, 16] on the basis of cosine part of Weierstrass-Mandelbrot function in Eq. (1) can be example of such model. Behavior of an average value of microaccelerations as a random process was compared with behavior of cosine part of Weierstrass-Mandelbrot function with usage of statistical analysis. At that parameters of the function were identified with spacecraft's characteristics. So, functional fractal dimension D is identified with moment from orientation engine of spacecraft and scaling parameter b—with generalized parameter z.

Such line approximately can be presented in the form of scheme shown in Figure 7 [13], where "NIKA-T" is the base spacecraft and actually created space objects are used.

Application of Fractal Analysis While Designing of Family of Spacecraft for Needs of Space Industry http://dx.doi.org/10.5772/67922 109

Figure 7. Line of spacecraft from different classes, which realize equal microacceleration level in the area with technological equipment.

The line developed using fractal property would guarantee a correspondence of microacceleration levels on the spacecraft from different classes. It would allow conducting of the same process on the spacecraft and taking a step toward full-scale experimental batch production in space.

Described property also can be effectively applied for study of microacceleration field of inner environment of spacecraft. Correctness of the gauges' run after launching overloads can be estimated by comparison of experimental data with results of on-board measurements. There is worked out an algorithm of measuring equipment efficiency check on the basis of fractal property of constructive component of microaccelerations in Ref. [13]. The algorithm is effective when constructive component dominates in microacceleration field of inner environment. Significant differences between the fractal model and measuring data can be explained by following factors:

constructive component is determined already in early developmental stages of spacecraft. This component characterizes dynamical features of spacecraft's constructional layout and takes into account the algorithms and ways to orient its orbital motion. Only constructive component can be influenced by using of the total power of different methods to provide and control microacceleration level in the area with technological equipment. This power can be

Scaling property of constructive component of microacceleration field allows application of methods of fractal analysis for designing of technological spacecraft as well as for correct data processing of microacceleration measurements, finding of failures of gauges and recovery of lost measuring data. It is very hard to do all of these only on the base of classical methods of analysis. The perspectives of addition of classical methods described by fractal property of

The launchings of spacecraft with specialized technological purposes happen with big intervals on the modern stage of space technologies' development. For instance, spacecraft "FOTON – M" No 3 was launched in 14 September 2007 and the following spacecraft "FOTON – M" No 4—only after almost 7 years in 19 July 2014. Thus, it is evident that it is impossible to arrange space experimental batch manufacturing only on the base of specialized space technic. One of the perspective ways to solute the problem is the wide application of small spacecraft. One start of carrier rocket of middle class is able to provide launching of tens small spacecraft to their orbits. Series-produced homotypic spacecraft can provide meeting of similar conditions for realization of concrete gravity-sensitive process. Continuous production can be organized using project launchings with small spacecraft as additional load. However, only application of small spacecraft would significantly limit production value. Limits on mass would not allow placement on spacecraft's board more than 100 kg of technological equipment

The approach, which includes advantages of spacecraft with specialized technological purposes and small spacecraft, is necessary to meet requirements of experimental batch production in space. This approach should integrate opportunities of these ways of space technic's development: regularity of launchings and significant scales of production while maintenance of equal favorable conditions for realization of gravity-sensitive processes. It is evident that such task statement leads to necessity to create line of spacecraft from different classes which meet these equal conditions. The scaling property of constructive component of microaccelerations should be applied to solute this task. For this purpose, the mathematical model of microaccelerations should be built using fractal function. Fractal model of microaccelerations worked out in the articles [15, 16] on the basis of cosine part of Weierstrass-Mandelbrot function in Eq. (1) can be example of such model. Behavior of an average value of microaccelerations as a random process was compared with behavior of cosine part of Weierstrass-Mandelbrot function with usage of statistical analysis. At that parameters of the function were identified with spacecraft's characteristics. So, functional fractal dimension D is identified with moment from

orientation engine of spacecraft and scaling parameter b—with generalized parameter z.

"NIKA-T" is the base spacecraft and actually created space objects are used.

Such line approximately can be presented in the form of scheme shown in Figure 7 [13], where

significantly strengthened by application of fractal analysis as well as classical.

constructive component of microaccelerations are mentioned below.

108 Fractal Analysis - Applications in Physics, Engineering and Technology

and materials for production.

Thus, checking of efficiency of all gauges after launching overloads is possible. It is unachievable by classical methods of analysis.

For instance, failed gauge was found in the result of such checking. It is possible to avoid significant mistakes while forming of model of microacceleration field of inner environment of spacecraft by neglect of measuring data from the gauge. However, accuracy would be reduced along with loss of measurement channel from failed gauge. In this case accuracy can be raised using fractal analysis. Well-known method of majority control [13] can be applied for replacement of the measurement channel by fractal mathematical model of microaccelerations, which was used for measuring equipment efficiency check. Undoubtedly, accuracy of such estimation would be lower in comparison with valid effective measurement channel. On the other hand, it would be higher than without application of majority control.

One of the possible algorithms of majority control with the aim to find out failed gauge and to smooth results of measuring data processing is shown in Figure 8 [2].

At that, fractal mathematical model plays the role of additional measurement channel. The presence of significant statistical differences between measurements with additional channel and without ones can be evidence of failed gauge. If the differences will be considered to be random, we can claim that all gauges run correctly. It increases the reliability of measuring data which leave much to be desired on the present developmental stage.

Thus, invention of scaling property of constructive component of microacceleration field which is similar to self-affine property of fractal functions allows application of methods of fractal analysis for creation of a line of spacecraft from different classes. At that, these spacecraft should realize the equal microacceleration level in the area with technological equipment.

The application of the scaling property of constructive component of microaccelerations gives the ability to select the row of values of generalized parameter z, which provides invariance of the form of time dependence of microaccelerations. The generalized parameter will allow a choice of corresponding inertia-mass characteristics of spacecraft and creation of the family of spacecraft (from orbital space stations to small spacecraft) which realize the identical microacceleration level.

Such result could not be achieved by classical methods because the fractal property is the base of supposed approach to creation of line of spacecraft from different classes. At that, it is worth to note that application of fractal analysis gives a significant practical result. Actually, creation of spacecraft line which realizes equal microacceleration level will have to be allowed in the beginning of pilot batch production in space already on the present developmental stage of space-rocket technic. The potential and advantages of spacecraft from all classes included in the line created on the base of scaling property of microaccelerations will be applied in the production. It is a large step forward in comparison with separated irregular experimental investigations with technological purposes, which are conducted in separated spacecraft today. On the other hand, creation of line of spacecraft on the basis of scaling property of microaccelerations is one of a few ways which lead to pilot batch-space-production on the present stage.

In spite of the main aim of designing of the spacecraft line, fractal model of microaccelerations, built, for example, on the basis of Weierstrass-Mandelbrot function, combined with classical methods of analysis allows solution of other tasks. These tasks include increasing of reliability Application of Fractal Analysis While Designing of Family of Spacecraft for Needs of Space Industry http://dx.doi.org/10.5772/67922 111

Figure 8. Algorithm to realize majority control over gauges during exploitation stage.

For instance, failed gauge was found in the result of such checking. It is possible to avoid significant mistakes while forming of model of microacceleration field of inner environment of spacecraft by neglect of measuring data from the gauge. However, accuracy would be reduced along with loss of measurement channel from failed gauge. In this case accuracy can be raised using fractal analysis. Well-known method of majority control [13] can be applied for replacement of the measurement channel by fractal mathematical model of microaccelerations, which was used for measuring equipment efficiency check. Undoubtedly, accuracy of such estimation would be lower in comparison with valid effective measurement channel. On the other hand, it

One of the possible algorithms of majority control with the aim to find out failed gauge and to

At that, fractal mathematical model plays the role of additional measurement channel. The presence of significant statistical differences between measurements with additional channel and without ones can be evidence of failed gauge. If the differences will be considered to be random, we can claim that all gauges run correctly. It increases the reliability of measuring

Thus, invention of scaling property of constructive component of microacceleration field which is similar to self-affine property of fractal functions allows application of methods of fractal analysis for creation of a line of spacecraft from different classes. At that, these spacecraft should

The application of the scaling property of constructive component of microaccelerations gives the ability to select the row of values of generalized parameter z, which provides invariance of the form of time dependence of microaccelerations. The generalized parameter will allow a choice of corresponding inertia-mass characteristics of spacecraft and creation of the family of spacecraft (from orbital space stations to small spacecraft) which realize the identical microacce-

Such result could not be achieved by classical methods because the fractal property is the base of supposed approach to creation of line of spacecraft from different classes. At that, it is worth to note that application of fractal analysis gives a significant practical result. Actually, creation of spacecraft line which realizes equal microacceleration level will have to be allowed in the beginning of pilot batch production in space already on the present developmental stage of space-rocket technic. The potential and advantages of spacecraft from all classes included in the line created on the base of scaling property of microaccelerations will be applied in the production. It is a large step forward in comparison with separated irregular experimental investigations with technological purposes, which are conducted in separated spacecraft today. On the other hand, creation of line of spacecraft on the basis of scaling property of microaccelerations is one of a few ways which lead to pilot batch-space-production on the

In spite of the main aim of designing of the spacecraft line, fractal model of microaccelerations, built, for example, on the basis of Weierstrass-Mandelbrot function, combined with classical methods of analysis allows solution of other tasks. These tasks include increasing of reliability

would be higher than without application of majority control.

110 Fractal Analysis - Applications in Physics, Engineering and Technology

leration level.

present stage.

smooth results of measuring data processing is shown in Figure 8 [2].

data which leave much to be desired on the present developmental stage.

realize the equal microacceleration level in the area with technological equipment.

of data from on-board measuring equipment for microaccelerations; increasing of efficiency of control over microaccelerations during conducting of gravity-sensitive technological processes and also taking the decisions about possibility and advisability to realize some or another gravity-sensitive process on the board of concrete spacecraft.

We can claim that fractal analysis significantly widens opportunities of classical methods for conducting of majority control of microaccelerations, for recovering of lost measuring data and also for taking the decisions about realization of active control over microaccelerations on the exploitation stage of spacecraft.

Evidently, significant complications of spacecraft's model are necessary for effective application of fractal analysis and achieving required accuracy of estimations. The model described in the chapter was chosen only for approval of existence of scaling property of constructive component of microacceleration field and its illustration.

## Author details

Andrew V. Sedelnikov and Ksenia I. Potienko\*

\*Address all correspondence to<EMAIL_ADDRESS>
Samara University, Samara, Russia

## References

[10] A.V. Sedelnikov, D.P. Molyavko, K.I. Potienko, Study of over-assessment of microaccelerations when using a beam-model of elastic elements, International Review of Aerospace Engineering 9 (1) (2016) 9–12.

Evidently, significant complications of spacecraft's model are necessary for effective application of fractal analysis and achieving required accuracy of estimations. The model described in the chapter was chosen only for approval of existence of scaling property of constructive

[1] A.V. Sedelnikov, The problem of microaccelerations: from comprehension up to fractal model, (Moscow, Russian Academy of Sciences: The Elected Works of the Russian school,

[2] A.V. Sedelnikov, K.I. Potienko, How to estimate microaccelerations for spacecraft with

[3] R.G. Owen, D.I. Jones, A.R. Owens, A.A. Robinson, Integration of a microgravity isolation mount within a Columbus single rack, Acta Astronautica, 22 (1990) 127–135.

[4] V.V. Sazonov, S.Yu. Chebukov, V.I. Abrashkin, A.E. Kazakova, A.S. Zaitsev, Analysis of low-frequence microaccelerations onboard the foton-11 satellite, Space Research, 39 (4)

[5] I.A. Babushkin, A.F. Glukhov, V.A. Demin, E.A. Zilberman, G.F. Putin, Measurement of inertial microaccelerations with the use of convection sensors, Journal of Surface Investi-

[6] G.F. Putin, A.F. Gluchov, I.A. Babushkin, D.A. Zavalishin, M.Yu. Belyaev, A.I. Ivanov, V.V. Sazonov, Study of microaccelerations onboard the international space station with the

[7] K.I. Potienko, Basic development stages of the algorithms applied to recover lost microacceleration data and check efficiency of measuring equipment on the board of

[8] A.V. Sedelnikov, Classification of microaccelerations according to methods of their con-

[9] A.V. Sedelnikov, On the fractal properties microaccelerations, Microgravity Sciences and

space laboratory, American Journal of Aerospace Engineering, 3 (1) (2015) 10–16.

elliptical orbit, Microgravity Sciences and Technology, 28 (1) (2016) 41–48.

gation: X-Ray, Synchrotron and Neutron Techniques 3 (1) (2009) 142–147.

DAKON-M convection sensor, Space Research 50 (5) (2012) 346–342.

trol, Microgravity Sciences and Technology 27 (3) (2015) 245–251.

Technology 24 (5) (2012) 345–350.

component of microacceleration field and its illustration.

112 Fractal Analysis - Applications in Physics, Engineering and Technology

Andrew V. Sedelnikov and Ksenia I. Potienko\*

Samara University, Samara, Russia

\*Address all correspondence to<EMAIL_ADDRESS>
Author details

References

2012), p. 277.

(2001) 419–435.


**CURRENT PERSPECTIVES IN CONTAMINANT HYDROLOGY AND WATER RESOURCES SUSTAINABILITY**

Edited by **Paul M. Bradley**

#### **Current Perspectives in Contaminant Hydrology and Water Resources Sustainability**

http://dx.doi.org/10.5772/47884 Edited by Paul M. Bradley

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**Design and Experimental Validation of a LoRaWAN Fog Computing Based Architecture for IoT Enabled Smart Campus Applications †**

**Paula Fraga-Lamas 1,\*, Mikel Celaya-Echarri 2, Peio Lopez-Iturri 3,4, Luis Castedo 1, Leyre Azpilicueta 2, Erik Aguirre 3, Manuel Suárez-Albela 1, Francisco Falcone 3,4 and Tiago M. Fernández-Caramés 1,\***

Received: 28 June 2019; Accepted: 23 July 2019; Published: 26 July 2019

**Abstract:** A smart campus is an intelligent infrastructure where smart sensors and actuators collaborate to collect information and interact with the machines, tools, and users of a university campus. As in a smart city, a smart campus represents a challenging scenario for Internet of Things (IoT) networks, especially in terms of cost, coverage, availability, latency, power consumption, and scalability. The technologies employed so far to cope with such a scenario are not yet able to manage simultaneously all the previously mentioned demanding requirements. Nevertheless, recent paradigms such as fog computing, which extends cloud computing to the edge of a network, make possible low-latency and location-aware IoT applications. Moreover, technologies such as Low-Power Wide-Area Networks (LPWANs) have emerged as a promising solution to provide low-cost and low-power consumption connectivity to nodes spread throughout a wide area. Specifically, the Long-Range Wide-Area Network (LoRaWAN) standard is one of the most recent developments, receiving attention both from industry and academia. In this article, the use of a LoRaWAN fog computing-based architecture is proposed for providing connectivity to IoT nodes deployed in a campus of the University of A Coruña (UDC), Spain. To validate the proposed system, the smart campus has been recreated realistically through an in-house developed 3D Ray-Launching radio-planning simulator that is able to take into consideration even small details, such as traffic lights, vehicles, people, buildings, urban furniture, or vegetation. The developed tool can provide accurate radio propagation estimations within the smart campus scenario in terms of coverage, capacity, and energy efficiency of the network. The results obtained with the planning simulator can then be compared with empirical measurements to assess the operating conditions and the system accuracy. Specifically, this article presents experiments that show the accurate results obtained by the planning simulator in the largest scenario ever built for it (a campus that covers an area of 26,000 m2), which are corroborated with empirical measurements. Then, how the tool can be used to design the deployment of LoRaWAN infrastructure for three smart campus outdoor applications is explained: a mobility pattern detection system, a smart irrigation solution, and a smart traffic-monitoring deployment. Consequently, the presented results provide guidelines to smart campus designers and developers,

and for easing LoRaWAN network deployment and research in other smart campuses and large environments such as smart cities.

**Keywords:** IoT; smart campus; sustainability; fog computing; outdoor applications; LPWAN; LoRaWAN; 3D Ray-Launching; smart cities; Wireless Sensor Networks (WSN)

### **1. Introduction**

A smart campus is an infrastructure similar to a smart city that makes use of Internet of Things (IoT) solutions [1–6] to connect, monitor, control, optimize, and automate the systems of a university. Today, a smart campus represents a challenging scenario for IoT networks, especially in terms cost, coverage, availability, latency, security, power consumption, and scalability.

The area covered by a campus varies substantially depending on the university, its location, the financial endowment, and the year of founding. For example, Berry College (Floyd County, Georgia, United States), is often considered the largest contiguous rural campus in the world: it covers 27,000 acres (109.26 km2) [7] of land. Other examples are the suburban/urban campuses of Duke University (Durham, NC, USA), which are deployed on 9350 acres (37.83 km2) [8], and the campus of Stanford University (Stanford, CA, USA), which covers 8180 acres (33 km2) [9]. Regardless of their initial surface area, it is common that campuses grow considerably as time goes by [10], hence institutions usually devise long-term sustainability plans to envision their growth in the future [11–13].

When a campus provides smart IoT services, it is necessary to provide communications connectivity to IoT nodes and gateways. Such a connectivity can be provided in a quite straightforward way indoors thanks to the use of popular technologies such as Wi-Fi, but, outdoors, technology selection becomes more complex, since it is not only necessary to provide good coverage and a cost-effective deployment, but also to decrease the communications energy consumption to maximize IoT node battery life.

To tackle such an issue in wide areas, a set of technologies grouped under the term Low-Power Wide Area Network (LPWAN) seem to be a good selection, since, in comparison to other previous technologies, they provide a wider area communications range and reduced energy consumption. In fact, LPWAN technologies have emerged as an enabling technology for IoT and Machine-to-Machine (M2M) communications [14] mainly due to their capabilities related to range, cost, power consumption, and capacity. Examples of such technologies are NB-IoT [15], SigFox [16], Ingenu [17], Weightless [18] or LoRaWAN [19] (a detailed comparison of these and other LPWAN technologies is given later in Section 2.2).

In the case of LoRaWAN, it is gaining momentum from both industry and academia [20–22]. LoRaWAN defines a communications protocol and a system architecture for the network. In addition, it uses LoRa for its physical layer [23], which is able to create long-range communications links and makes use of a Chirp Spread Spectrum (CSS) modulation that conserves the power features of Frequency Shifting Keying (FSK) while increasing its communications range. All these features make LoRaWAN a good candidate for providing wireless communications to outdoor IoT nodes in a smart campus.

Traditionally, gateways connect the IoT nodes with the cloud and among them. The cloud is basically one or more servers with large computational power, communication, and storing capabilities that receives, processes, and analyzes the data collected from the IoT nodes by performing computational-intensive tasks. Although cloud-based solutions are appropriate at a small scale, when the number of IoT nodes grows significantly and, consequently, the network traffic they generate, congestion may lead to increasing latency responses and slower data processing. Among the different alternatives to confront this challenge and to guarantee a flexible, scalable, robust, secure, and energy-efficient deployment of IoT networks, the design and implementation of a fog computing

architecture was chosen. Fog computing supports physically distributed, low-latency (e.g., real-time or quasi real-time responses) and location-aware applications that decrease the network traffic and the computational load of traditional cloud computing systems by processing in the IoT nodes most of the data generated by their sensors and actuators and unburdening the higher layers from data processing [24].

Furthermore, when designing a smart campus, it is necessary to plan how LoRaWAN gateways and nodes are deployed to guarantee good IoT node coverage while minimizing the number of gateways (i.e., minimizing the smart campus communications infrastructure cost). The problem is that there are only a few examples of academic and commercial tools that create such a planning [25,26], so developers have to adapt tools previously optimized for other technologies (e.g., Wi-Fi [27]) or have to carry out tedious empirical measurements throughout the campus [28,29].

This article confronts the mentioned challenges by designing and implementing a cost-efficient, scalable, and low-power consumption LoRaWAN fog computing-based architecture for wide areas. Specifically, the system was designed with the aim of developing novel latency-sensitive IoT outdoor applications that create more sustainable and intelligent campuses. The following are the main contributions of the article, which as of writing, have not been found together in the literature:

The rest of this article is structured as follows. Section 2 reviews the state of the art on smart campuses: their characteristics, technologies, architectures, previous relevant deployments, potential applications, and the previous work on modeling and planning a smart campus. Section 3 details the architecture of the proposed system and the characteristics of the LoRaWAN testbed implementation. Section 4 describes the proposed planning simulator and the analyzed scenario. Section 5 is dedicated to the experiments. Finally, Section 6 presents the main discussion on the lessons learned from these experiences, while Section 7 is devoted to the conclusions.


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Green chemistry is defined as the use of a dozen principles that reduce or eliminate hazardous materials in the design, manufacture, and use of chemical products. Today, it is understood that focusing on precautions to reduce or eliminate existing pollution sources is more effective than looking for a cleaning path after exiting. This book presents the principles of green chemistry for clean production in light of the latest technological developments and increasing environmental awareness. Chapters cover such topics as synthesis and applications of nanomaterials for energy and environmental applications, climate process, alternative green energy sources, and removal of emerging pollutants from water.

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