*2.1. Manual Installation and Maintenance Maneuvers for First Generation TECs*

We define the term *manual* for installation and maintenance maneuvers for TECs in an open loop. These sorts of maneuvers are currently used in the first generation tidal technologies which are, at present, in a pre-commercial stage [38]. An example of the gravity-based TEC described in this section and designed by the GIT-ERM research group is illustrated in Figure 3. The manual installation of the TECs can be divided into the installation sequence for the support structure of the TECs and the installation sequence for the gondolas. The following steps have, therefore, been defined in order to perform the installation tasks:

**Figure 3.** Example of TEC used for manual installation and maintenance maneuvers. Additional details about this TEC design can be found in [38].

	- **–** The special vessel transports the complete TEC and the equipment required (support structure, ballasts, gondola, etc.) simultaneously (see Figure 4a), and moves from the base

port towards the TEF. When it is at the TEF, it uses its dynamic positioning system to place all the necessary items in the exact position in which the TEC will be installed.

**Figure 4.** Installation of the structure of the TECs: (**a**) position required to install the base; (**b**) connection of the umbilical cables to the TEC structure; (**c**) controlled descent of the TEC structure; (**d**) fixing the TEC structure to the seabed; (**e**) placement of the concrete ballasts; and (**f**) installation of the TEC structure once the process has been completed.

	- **–** Once the support structure has been completely installed, the special vessel is placed on the TEC structure and the guide cables of the gondola are recovered by means of an acoustic signal (see Figure 5a).
	- **–** In order to work with the gondolas, a specific tool equipped with a hydraulic system will be used, whose objective is to wrap itself around the gondola that is to be installed or recovered. Its operation is similar to that of a clamp (see Figure 6).
	- **–** The guide cables are connected to the tool used to lower the gondola (see Figure 5b). These cables facilitate the descent of the gondola and the insertion of the gondola into the structure.
	- **–** The gondola initiates its descent with the guide cables thanks to its own weight and without oscillations until the gondola has been inserted into the structure. Figure 5c illustrates the descent process of the gondola and Figure 5d depicts the gondola-structure insertion process.
	- **–** The final step is that of removing the tool used to install the gondola and the retrieval of the guide cables. Figure 5e illustrates the removal process. When the tool is on the deck of the vessel, the guide cables are removed from the tool and are submerged in a safe location by means of a ballast and a buoy in order to recover them during the next intervention. Figure 5f shows the installation of the whole TEC once the process has been completed.

**Figure 5.** Installation of the gondola of the TECs: (**a**) cable-recovery process; (**b**) connection of the cables to the tool in charge of lowering the gondola; (**c**) controlled descent of the gondola; (**d**) process of inserting the gondola into the TEC structure; (**e**) tool and cable removal process; and (**f**) end of gondola-installation process.

**Figure 6.** Tool used for manual installation and maintenance maneuvers (installation and recovery of the gondola).

The maneuvers that are necessary to perform the maintenance tasks (recovery of a submerged gondola) follow the inverse order of that described for the installation of the gondola. The procedure for maintenance maneuvers, therefore, shares a lot of similarities with the procedure of installing the gondolas, and the steps required to perform maintenance maneuvers are the following:

	- **–** The starting point is that of locating the special vessel above the gondola to be recovered. The first step is the recovery of the cables from the seabed. The ends of the cables are released from the seabed by means of an acoustic signal (see Figure 7a) and these cables are connected to the tool used to recover the gondola.
	- **–** The tool starts its descent, following a trajectory with an inclination angle that permits the tool to wrap itself around the back of the gondola (see Figure 7b).
	- **–** When the tool is ready to perform the grip, the cables are tightened and placed completely vertically (see Figure 7c). The hydraulic system of the tool is activated in order to close it and fix it to the gondola (see Figure 7d).
	- **–** The process of raising the gondola begins. As the cables are tightened, the displacements are very small and the operation is carried out under safe conditions (see Figure 7e).
	- **–** When the whole system (gondola + tool) is outside the water, the cables are removed from the tool and are submerged again by means of a ballast and a buoy in order to recover them in the future (see Figure 7f).

**Figure 7.** Maintenance operations of the gondola: (**a**) positioning the special vessel above the gondola; (**b**) descent process of the tool; (**c**) coupling process between the tool and the gondola and cable tensioning process; (**d**) activation of the hydraulic system of the tool to fix it to the gondola; (**e**) gondola lifting process; and (**f**) gondola recovered.


*7.2. Estimations of Perceived Gust for Fixed-Wing*

Now we consider the flight path of a fixed-wing UAV above the building roof as indicated in Figure 12 at representative speeds of 5 m/s and 15 m/s. Consider how the combined effects of flow angle and magnitude are perceived along one flight path by superimposing the vehicle flight speed *VV* onto the vertical speed *Vvert* and horizontal speed *Vhoriz* of the wind, *Vvert* and *Vhoriz* being the Cartesian analog of the "polar" results given in Figure 13. The superposition of the flight velocity and wind speed enables the relative velocity and angle of attack to be computed. The effective angle of attack, α(t), is calculated using

$$\alpha(t) = \alpha\_o + \operatorname{atan}\left(\frac{V\_{\text{vert}}}{V\_V + V\_{\text{horiz}}}\right) \tag{7}$$

The results for two nominal cruise speeds (5 m/s and 15 m/s), converted back into velocity magnitude and angle of attack, are given in Figure 15. The immediately obvious feature of Figure 15 occurs near the building leading edge, "0" of the abscissa. As expected from Figure 13, the shear layer atop the building results in the worst-case perceived gust encounter: at the lower flight velocity (5 ms−1) a ≈20◦ change in aircraft relative angle of attack is accompanied by an approximately 50% increase in velocity magnitude, all over a time increment of 0.25 s. At a higher flight velocity of 15 ms−1, the perceived angle of attack is lower (≈10◦), accompanied by a 25% increase in velocity over a time increment of 0.11 s. Using a simple linear relationship between the incident flow changes (angle of attack and relative velocity magnitude) and lift coefficient, and assuming a 2π lift curve slope and an unperturbed flight path (i.e., steady level flight), this gust represents changes in *CL* of 8.5 and 2 for a flight velocity of 5 ms−1 and 15 ms−1, respectively. For flight paths at 45◦ (where one wing is immersed into the gust before the other) the roll moment coefficient *CLp* presented in Figure 15 is calculated from the lift imbalance between the aircraft's wings:

$$\mathbf{C}\_{L\_p} = \frac{b}{2} \ast \Delta \mathbf{C}\_L \tag{8}$$

$$\mathbb{C}\_{L\_p} = M / qSb \tag{9}$$

Taking time lags into consideration, conventional attitude sensing and control systems of a fixed wing UAV travelling at 10 ms−1 will typically take 0.52 s to react (from sensing to actuation) [7,66] which can be insufficient to mitigate this gust. The combination of phase-advanced sensors, where flow, forward of the UAV, is measured and used as a control input [67], and novel control techniques may be needed [68] to achieve flight control in this type of environment. Examples of the latter include rotations of the entire wing, leadingedge control surfaces [68], or "fast flaps" at the trailing edge [69], which are intended to deflect faster than one convective time, producing lift transients well beyond what would be considered quasi-steady.

**Figure 15.** Gust shape as perceived by a moving aircraft. And the resultant *CL* in the vicinity of the rooftop (from a simple strip theory model, utilizing transient flow data). Note that position 0 denotes the physical edge of the building.


**4. General discussion**

146 Social Welfare

always something that stops you when you go out… Because when you can't do anything, you have no freedom…'. *d)* They are monitored by prison warders: 'Prison warder, that's me that is'. *e)* Prison life is passive: 'So it turns out that you don't do much on the inside either, because you're not motivated and… and don't like doing much anyway'. *f)* But there's prison leave: 'True, I'm off on leave from time to time, but as a rule I suffer for it afterwards'. *g)* Plans for making an escape: 'No, that's why I think it's unfair and really… because if I'd been a man then: Right I'm off, then, bugger everything, I can't put up with this any more']. *h)* Will to live: 'You really lose the will to… live'. *i)* Lengthy sentence: 'It's like I've been here for ever…'. *j)* Apprehensive about the future in prison: 'But I get dreadfully anxious about the future, because I know that living like this for just a few more years… I start doubting myself, how strong I've actually been, that it's not enough, because there's too much trouble'. *k)* Fearful of release: 'If you're up for release… there's often so much trouble, you have to make calls, ask others, to get it over with… and degrading yourself and spilling the beans, sorry I was born, that's how I feel it… It really kills any pleasure you're feeling when you leave here, like'. *1)* Fair sentence? 'No, it wasn't fair… those things have left their mark in a way… Just starting to brood over things: why this and why that? I never deserved it, and… I've got myself to blame partly because I never got an education… married young' [*Laura* (44), Kjell Underlid, 11

A man used a *mountaineering metaphor* to describe his feelings of loss of control over his life: 'You start off on a plotted route. A route that's your life. But then you find out that for you there's not enough to hold onto on the mountain side to get further. It's so hard that route. You fight and fight, but you don't get anywhere.  Some (grips) are fragile, and some are missing, and… And they're terrible' [*Steinar (*30), Kjell

*Metaphor* means that a literal meaning is given a non-literal meaning. Although metaphors can oversimplify, mask, deceive and lead astray, they can often serve as a springboard for the creation of meaning and communication of understanding. They can structure experiences and understanding, act as reference points around which to organise data and build bridges between things we comprehend and things we are trying to comprehend (Ely,

Although poor people as individuals share characteristics with the rest of humanity and other disadvantaged groups, as individuals they are nonetheless unique, and their subjectivity belongs to them as unique individuals. Their metaphors and expressions may create empathy with and insight into their life-worlds, because they are based on

The *prison metaphor* highlights the almost claustrophobic sense of oppression, of being tied hand and foot, accommodating to the greyness of everyday poverty, resigned hopelessness in relation to the future, and self-reproach. The *mountaineering metaphor* illustrates the sense of powerlessness, of a sense of the ground giving way, accompanied by a fear of losing one's

February, 2000].

Underlid, 11 February, 2000].

Vinz, Downing & Anzul, 2001).

footing and falling.

**3.6 Further explication/interpretative reflection**

particularistic and ideosyncratic experiences.

I shall now discuss the findings in light of *a*) theories of needs and emotions, *b*) contextual factors, and *c*) methodology.

The inhibition or loss of autonomy experienced by the respondents in the sample can be understood on the basis of a concept of *subjective needs*. They have a subjective need for autonomy but experience that it is either blocked or frustrated by poverty. The typical affective reaction to this blocking or frustration is usually expressed in *anger- or sadnessrelated states*, although many also react with other feelings, e.g., fear and anxiety.

Affective reactions associated with inhibition or loss of autonomy varied in intensity from moderate unease to very strong feelings. There were instances of short-lived emotions linked to actual events, focused and permanent sentiments and diffuse, negative moods linked to existential questions of a poverty-related nature. Feelings associated with inhibited or lost autonomy in situations of poverty affected all respondents in the sample, penetrated different life domains and role arenas, and had shaped the lives of several of the respondents over a period of years and even decades. There was nonetheless wide variation in the sample with respect to type and intensity of feelings.

These variations in the experience of inhibition or loss of autonomy may have something to do with differences in the objective poverty situation. Poverty can be deep and wide, deep and narrow, shallow and wide, shallow and narrow and permanent/chronic or shortlived/acute. On the other hand there is no strict correlation between objective inhibition or loss of autonomy and subjective feelings. Poor people's objective situation will manifest itself in their *horizon* – as the concept is employed in phenomenology and hermeneutics – to different degrees and in different ways (Husserl, 1970; Gadamer, 1989). The poor do not necessarily reflect over the likely consequences of inhibition or loss of autonomy. It is not certain that the entire range of such inhibition or loss of autonomy is intentional (in the philosophical sense, i.e., consciousness as directed at something) and aspects of inhibited or lost autonomy are not necessarily objectivised (made into an object of consciousness). In general, experienced inhibition or loss of autonomy is multifaceted, multidetermined and expressive of an interplay between subjective and objective factors.

From an emotion theory perspective (Ben-Ze'ev, 2000), the negative feelings associated with inhibited or lost autonomy felt by the respondents originate in a negative evaluation of the desirability of their perceived situation, or of the situation of people close to them (especially their children). In other words, there exists a threat to key values and aspirations. The intensity of the feelings is determined by the level of desirability and importance of these aspirations as perceived by each individual and how potent, real and relevant they perceive the threats to be. Other factors of significance in this connection are what/who is held to be responsible for the threats, how controllable/uncontrollable they are felt to be, whether the respondent is prepared or unprepared to meet the threat, and how certain/uncertain it is that it will actually materialise, and when and how. The extent to which the situation is considered deserved or undeserved will also have an impact as will the person's general circumstances, formal and informal safety networks, personality factors, use of defence mechanisms (A. Freud, 2000/1936) and emotion- and problem-focused coping strategies

Autonomy and Poverty – An Empirical Study of Long-Term Recipients of Social Assistance 149

beyond. It is a small, biased and judicious sample of long-standing recipients of social security in a city in one of the wealthiest countries in the world on the cusp of a new millennium. On the other hand, the study may also have touched on experiences of poverty that are almost universal and invariant. That said, conventional criteria relating to representativeness are not equally relevant in qualitative research where one is more interested in the uniqueness of different experiences and in contextual, interactional and

The purpose of this summary is to conclude the study as a whole, to see it, as it were, from a bird's eye view. It offers in addition a synthesis of transformed meaning units into a

The 'psychology of poverty' has preoccupied me for a considerable time. I have studied experiences of inhibited or lost autonomy among the poor and attempted to understand what it means. During this process I have sometimes been physically distant from the phenomena under investigation (while reviewing the literature and analysing the data for example) and sometimes closer (I spent more than six months with the respondents, generally in their own homes). I was granted access to the subjectivity and life-worlds of the poor in the shape of lived everyday experiences (the 'taste and smell' of poverty), verbalised and reflected upon within a framework of a trustful dialogue. These experiences were fixed in the form of a transcribed text, selected excerpts from which I have attempted to explicate and interpret. The interviews were encounters between people whose lives, circumstances and horizons differed – between poor and non-poor, between the horizon of the lay person and that of the professional psychologist and researcher. Both of us existed, however, in the same society and historical period. The findings and interpretations are the product of the fusion of horizons made possible by

Inhibition or loss of autonomy is a key meaning of relative poverty in affluent welfare states, generally accompanied by a sense of anger or sadness. This is a subjective reality for the poor. The sense of inhibited or lost autonomy is an existential verity for the poor in affluent welfare states. It is a psychological *essence* of this type of poverty. This does not mean that experienced inhibition or loss of autonomy is the only or most significant nucleus of the 'psychology of poverty'. Experiences of insecurity (Underlid, 2007), social devaluation (Underlid, 2005) and a besieged self-image or sense of worth (Underlid, 2004) are examples

Whether the data from this in-depth study of a small number of respondents corroborate the claim that experienced inhibition or loss of autonomy is a psychological essence of relative poverty in affluent welfare states may of course be questioned. Nevertheless the study provides a platform on which to base further studies in the 'psychology of poverty' – either with the same methodology and theoretical perspectives or others. It is my hope that these tentative steps into largely virgin territory – for recent contributions, see for example Mullainathan´s (2011) excellent article - will inspire others to embark on similar research and that future studies will succeed in fitting the various pieces of the 'psychology of

interpretative concerns (Van Manen, 1992).

**5. Synthesis and concluding remarks**

consistent statement (Giorgi, 1985).

these encounters.

of other potential essences.

(Lazarus & Folkman, 1984). Other relevant factors are salience (stimulus properties in a particular context), perception (which is selective), social comparison along different dimensions, interpretation of the situation (attribution), needs (general autonomy orientation) and general attitude to life (ideology). Negative feelings associated with inhibition or loss of autonomy can also be interpreted as the activation of deeper and more generalised *anxiety* related to personality and background, current circumstances (for instance too little/too much external structure), belonging, social exclusion, identity and fundamental existential issues. Such experiences can therefore also be elucidated from the perspective of anxiety theories (Roth, Noyes & Burrows, 1988–1992). Need and emotion theories are, however, as an interpretative basis, far too narrow.

The experiences of the respondents may be understood more broadly in relation to the structure and culture of the society in which they live, i.e. *contextually*. It is a society for which commercialism (a system dominated by economic interests), materialism (Fournier & Richins, 1991) and consumerism (Bauman, 1998) are key characteristics (Hellevik, 1996). Money in this type of society exerts a wide-ranging and decisive influence on feelings of autonomy, and lack of money is in many ways an autonomy killer. This is the context in which relative poverty in affluent welfare states should be understood in relation to experienced autonomy.

Other groups may also experience inhibition or loss of autonomy due to such contextual factors, but the type of inhibited or lost autonomy reported by the respondents in this study is *poverty-related*, and in this sense their experiences are relatively exclusive. Since the questions put to them in the interviews concerned their experiences of their poverty-related situation, a control group of non-poor would have been irrelevant and meaningless. However, many of the same attributes exist among other socio-economically deprived groups.

The findings also need to be seen in connection with the study's *methodological* approach. In the interviews information was generated by both parties in conversation or dialogue. Now, there is good reason to ask if my own understanding and values, i.e. preconceptions, may have influenced the information that was created. I tried to act as an interested, concerned and empathic researcher, but also emphasised a professional and neutral approach and the use of open, non-leading questions. Whatever may have been non-verbally communicated is not easy to say.

It is also difficult to estimate the impact of the 1000 kroner promised for taking the trouble to take part. It may well be that it was perceived by respondents as such a large amount that they felt compelled to take part in the study. The rate of participation in this study was higher than usual in poverty research, despite this study's increased number of questions and time to complete it. The themes for inquiry were also both more personal and more intimate. The fact that none of the participants pulled out, and that after the interviews many said unprompted they were pleased with their own participation, may be taken to indicate that factors other than money contributed to them remaining in the study or even to them becoming respondents in the first place

The study's external validity is low, and findings should not be generalised without great care to other people suffering from poverty either within the same socio-cultural bracket or beyond. It is a small, biased and judicious sample of long-standing recipients of social security in a city in one of the wealthiest countries in the world on the cusp of a new millennium. On the other hand, the study may also have touched on experiences of poverty that are almost universal and invariant. That said, conventional criteria relating to representativeness are not equally relevant in qualitative research where one is more interested in the uniqueness of different experiences and in contextual, interactional and interpretative concerns (Van Manen, 1992).


**2.5. Genome editing**

Genetics relies on the analysis of mutations and the phenotypic variation they cause to correlate precise sequence changes to particular genes of interest. With the help of genetic engineering techniques, desired traits can also be introduced into plants not expressing them naturally. However, the use of genetically modified crops is hindered by health, environmental, and ethical concerns. Genome editing with site-specific nucleases is the most advanced technology for precise and effective genome engineering, which promises to revolutionize applied research for crop improvement [70,71]. It involves the insertion, elimination, or replacement of a fragment of DNA at desired locations in the genome, by using engineered nucleases that create specific double-strand breaks (DSBs) and stimulate cellular DNA repair mechanisms. There are currently four classes of targetable nucleases discovered and bioengineered that are used to create site-specific DSB: zinc finger nucleases (ZFNs), transcription activator–like effector nucleases (TALENs), clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR-associated (Cas) RNA-guided nucleases (RGNs), and engineered meganu‐ clease, also known as homing endonucleases [72–75].

tive splice variants; mapping on the reference genome to elaborate the expression level of known, annotated genes; and the differential expression of selected genes between different genotypes. Such studies will become increasingly important for modern breeding programs since especially biotic and abiotic stresses are clearly regulated by different mechanisms other

First experiments were conducted to study the DNA methylation profile on the model plant *Arabidopsis* to study epigenetic changes upon biotic stresses. A whole set of tools were installed and in-house scripts developed to analyze data derived from whole-genome bisulfide (BS) transformation [67]. The BS transformation converts non-methylated cysteine into a uracil and later, after polymerase chain reaction (PCR) amplification, into a thymine, whereas the methylated cysteine remains a cysteine. Since this technique is looking for single-nucleotide events and since the genomic code is "falsified," there is the need for a high-quality reference and specialized mapping strategies and statistics for the methylation calling [68]. The availa‐ bility of a good-quality reference genome sequence of cassava and whole-genome re-sequenc‐ ing of several clones of interest prompted DNA methylation profiling for some relevant cassava varieties. In this pilot study at IITA, currently in progress, the aim is to reveal dynamic methylation events under biotic and abiotic stresses to gain information on possible epigenetic

With the development of NGS noncoding RNA (ncRNA), especially the smaller species became very easy to detect, and many studies demonstrated that these ncRNAs are important players in gene regulation, regulation of DNA and histone methylation, and defense mecha‐ nisms in plants. ncRNA profiles are also important for diagnosing and characterizing virus infections in plants [69]. The virus infection triggers a defense reaction where a cascade of host ncRNA are involved, but also small interfering RNAs (siRNAs) corresponding to the viral genome are found in the plant extract. These endogenous ncRNA and the viral small RNA fragments can easily be detected by NGS. At IITA, we have the expertise and software suite of tools to search and analyze any plant ncRNAs or virus siRNAs. Again biotic and abiotic stresses in plants have a specific profile of expression of different species of ncRNA, and at IITA, we study this phenomenon to create information and tools to improve the breeding

Genetics relies on the analysis of mutations and the phenotypic variation they cause to correlate precise sequence changes to particular genes of interest. With the help of genetic engineering techniques, desired traits can also be introduced into plants not expressing them naturally. However, the use of genetically modified crops is hindered by health, environmental, and ethical concerns. Genome editing with site-specific nucleases is the most advanced technology for precise and effective genome engineering, which promises to revolutionize applied research for crop improvement [70,71]. It involves the insertion, elimination, or replacement of a fragment of DNA at desired locations in the genome, by using engineered nucleases that create specific double-strand breaks (DSBs) and stimulate cellular DNA repair mechanisms. There are currently four classes of targetable nucleases discovered and bioengineered that are

than purely genetic variations.

294 Next Generation Sequencing - Advances, Applications and Challenges

programs.

**2.5. Genome editing**

markers for the next-generation breeding programs.

Over the past few years, all of the above nucleases have been used to create targetspecific mutations in model and crop plants, albeit with some limitations. In all cases, a continuing issue is the delivery of all the reagents efficiently and functionally to the cells or organisms under study. The CRISPR/CRISPR-associated protein 9 (Cas9) tool seems to overcome some of the shortcomings of the other methods [76,77]. Successful examples of targetable nucleases application are reported for *Arabidopsis*, tobacco, rice, maize, soy‐ bean, barley, cabbage, and bunchgrass by using different delivery technologies, including T-DNA plasmid from Agrobacterium, protoplasts and embryonic callus manipulation, and subsequent plant regeneration [70,78–82].

Targetable nucleases are attractive alternative biotechnological tools for trait manipulation and breeding in crop plants. By means of targetable nucleases, mutations can be produced in a very specific manner, and known mutations can be transferred between cultivars or breeding lines without disrupting a favorable genetic background. Although genome editing approaches are relatively new and not yet widely applied, their advantage in terms of safety, robustness, speed, and precision over the classical mutagenesis and breeding is undisputable [75]. Targeted genome editing using artificial nucleases, combined with accurate gene expression analyses, has the potential to accelerate plant breeding by providing the means to modify genomes rapidly in a precise and predictable manner [71] and to restore lost traits through reverse breeding [83]. Although genome editing has not yet been applied to African staple crop species, there is no doubt that this technology will assume a great importance particularly for genetic improvement of asexually propagated crops with limited flowering ability [71].

Furthermore, technologies based on targetable nucleases offer the opportunity to overcome the major concerns of the general public about transgenic crops since the organism with the edited gene do not contain the foreign DNA. In particular, the absence of extra copies of DNAs upon nonhomologous end joining (NHEJ)-mediated gene knockout makes the final plant comparable with those arising from natural mutations. However, the development of dedi‐ cated international legislations is required to effectively promote a wide application of genome editing technologies for crop improvement [70,84]. As knowledge is gained about plant genome organization and gene functions are revealed, the potential of genome editing could be mainstreamed to broaden the genetic base of crops.


Contents

**Preface XI**

#### **Section 3 III-V Epitaxy 153**

Preface

This book consists of nine chapters.

This edited volume is a collection of reviewed and relevant research chapters with a focus on the epitaxy field of study. This book includes scholarly contributions by accomplished authors and is edited by various experts in the field of materials science. Each contribution is available

**InTechOpen**

as a stand-alone chapter but is also directly related to the book's topics and objectives.

The target audience comprises scholars and specialists in the field.

Chapter 9 **Epitaxy and Device Properties of InGaAs Photodetectors with Relatively High Lattice Mismatch 203** Xing-you Chen, Yi Gu and Yong-gang Zhang

## Preface

**Section 3 III-V Epitaxy 153**

**VI** Contents

Chapter 7 **GaN and InN Hexagonal Microdisks 155**

**Electronic Applications 171**

Baba Krupanidhi

Chen-Chi Yang, Ikai Lo, Yu-Chi Hsu and Hong-Yi Yang

Chapter 8 **Heterostructures of III-Nitride Semiconductors for Optical and**

Chapter 9 **Epitaxy and Device Properties of InGaAs Photodetectors with**

**Relatively High Lattice Mismatch 203** Xing-you Chen, Yi Gu and Yong-gang Zhang

Basanta Roul, Greeshma Chandan, Shruti Mukundan and Saluru

This edited volume is a collection of reviewed and relevant research chapters with a focus on the epitaxy field of study. This book includes scholarly contributions by accomplished authors and is edited by various experts in the field of materials science. Each contribution is available as a stand-alone chapter but is also directly related to the book's topics and objectives.

This book consists of nine chapters.

The target audience comprises scholars and specialists in the field.

**InTechOpen**

**Section 1**

**High-Quality Epitaxy of Functional**

**Heterostructures with Strain Engineering**


**7. Morbidity and mortality**

In general, inner city asthma has a higher index of severity, is associated with increased morbidity, and has a higher mortality rate than asthma outside the inner city milieu [29]. Several criteria may be used to evaluate the level of acuity. These include, among others, emergency room visits, hospitalizations, office visits, time lost from work, and absenteeism from school. Research shows that inner city asthma is associated with increased morbidity in each of these criteria. The national database report of 2006 indicated that around 3.5 million visits to physician offices, half a million visits to hospital outpatient departments, an equivalent number of visits to an emergency department, and over 150,000 hospitalizations were related to asthma in this population [55].

Inner city asthma is associated with increased mortality when adjusted for the level of acuity. As far as mortality is concerned, there were 167 deaths from asthma in 2005 among children and adolescents [29, 55]. Interestingly, African-Americans demonstrate a sevenfold increase in mortality, around threefold increase in emergency department visits, threefold increase in hospitalization, but 20% lower nonemergency ambulatory visits than white children. Data on Hispanic children show emergency department visits to be twice that of whites [55].


**1. Introduction**

Oxides are among the most stable inorganic materials since no further oxidative processes (e.g., corrosion, ion release) can take place. This is a major reason for the use of oxides as ideal bioceramic materials since the 1960s because their chemical inertness was considered as the basis for biocompatibility. The first ceramic oxide used in orthopedics was alumina (Al2O3), while ceramic composite oxides, prevalently made of alumina-zirconia (Al2O3-ZrO2) were subsequently developed, seeking improved mechanical performance [1].

The first use of alumina as a biomaterial is due to Dr. Sami Sandhaus, a Swiss dentist, who in 1962 developed a screw-shaped dental implant named Crystalline Bone Screw— CBS® and used it in a significant number of cases [2]. In 1963, L.W. Smith and J.F. Estes (Haeger Potteries, Dundee, IL, USA) developed CerosiumTM as a bone substitute in case of large bone defects, i.e., a silica aluminate matrix where pores (about 50% in volume) were filled with epoxy resin [3].

At that time, hip arthroplasty was taking its first steps. Although keenly interested by the potential of such a procedure, orthopedic surgeons were very concerned about the failures of implants due to the wear of bearings. The cooperation between Dr. Boutin—an orthopedic surgeon working in Pau, a town in Southern France—and one of his patients, the manager of a factory sited nearby manufacturing high alumina electric insulator, led to the first total hip replacement (THR) with an alumina-on-bearing in 1970 [4]. Such an implant had a stainless-steel stem and a Ultra-High Molecular Weight Polyethylene (UHMWPE) socket—soon replaced by a socket made of alumina—both cemented into bone.

In the same years, several scientists in Germany (i.e., G. Langer in Keramed, G. Heimke in Friedrichfeld, H. Dörre in Feldmüle, M. Saltzer in Rosenthal) gave a decisive contribution to the development of alumina for orthopedic components and overall for alumina as a

**Citation:** Piconi, C.; Sprio, S. Oxide Bioceramic Composites in Orthopedics and Dentistry. *J. Compos. Sci.* **2021**, *5*, 206. https://doi.org/ 10.3390/jcs5080206

Academic Editor: Francesco Tornabene

Received: 6 July 2021 Accepted: 30 July 2021 Published: 3 August 2021

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

**Copyright:** © 2021 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/).

biomaterial. This resulted in the development of a number of ceramic orthopedic devices, among which it is worthwhile to mention the BIOLOX® alumina developed by H. Dörre in Feldmüle (now CeramTec GmbH), which became "*the ceramic*" in orthopedics until this attribute was overtaken by the higher-performing BIOLOX® delta alumina–zirconia ceramic composite [5].

Indeed, alumina showed critical issues particularly related to failure of THR implants [6], leading some manufacturers to withdraw from the market of implantable ceramics. Alumina exhibits low fracture strength and toughness and is very sensitive to microstructural flaws that lead to a poor resistance to stress concentration or mechanical impact. As the presence of intergranular pores and large grain size are the main microstructural features that affect the mechanical strength of alumina, the efforts of ceramists were focused on decreasing the porosity and the grain size in alumina ceramics. This was obtained by the selection of proper precursors (e.g., alkoxide-derived powders) and by the optimization of the overall manufacturing process, from batch preparation to final densification by hot isostatic pressing (HIP). Such improvements resulted in the so-called "third generation alumina" based on high-purity precursors and characterized by finer grain size and density near the theoretical one, as illustrated in Table 1.

**Table 1.** Selected properties of alumina, evidencing the development of the material [5].

Nevertheless, the feasibility to obtain alumina components with specific design was limited by its typical brittle fracture behavior [7]. In response to these issues, the company Desmarquest (now Saint Gobain Céramiques Avancées Desmarquest—SGCAD, Evreux, France) followed a different approach: they focused their attention on a different, intrinsically tough ceramic, Yttria-stabilized Zirconia Polycrystal (Y-TZP). Zirconia (zirconium dioxide, ZrO2) is characterized by the polymorphism of its crystal lattice; therefore, it exists in three thermodynamically stable crystalline phases: monoclinic (up to 1170 ◦C), tetragonal (1170–2370 ◦C), and cubic (2370–2680 ◦C). Effective applications of zirconia ceramics in medicine were made possible since the discovery of the stabilization of the tetragonal phase at room temperature based on the introduction of small amounts of oxide phases as stabilizers. Such a discovery led to the development of Partially Stabilized Zirconia (PSZ) [8] because the low concentration of the stabilizing oxide did not allow the full stabilization of the cubic phase. PSZ was firstly obtained by using calcium oxide as stabilizer, but successively either magnesium oxide (magnesia, MgO) or yttrium oxide (yttria, Y2O3) were used for this purpose. The real breakthrough in the development of zirconia ceramics occurred in 1975 with the publication of the research paper "Ceramic Steel?" by Garvie, Hannink, and Pascoe [9]. They reported the increase in toughness in MgO-stabilized PSZ (Mg-PSZ) due to the transformation of the tetragonal phase into monoclinic. Such a transformation, taking place in a "martensitic" way as in some steels, results in an effective dissipative mechanism for fracture energy and, finally, in a self-toughening effect.

More recently, Gupta et al. [10] reported that a tetragonal zirconia ceramic showing grain size ≈0.3 to 0.5 μm could be obtained by using 2–3 mol% of Yttrium Oxide (Yttria— Y2O3) as a stabilizer, thus resulting in minimal residual cubic and monoclinic zirconia. Since then, although many studies had been dedicated to materials stabilized by CaO, MgO,

and CeO, the main zirconia ceramic that was developed industrially for the production of medical devices was the one stabilized by Y2O3. The tetragonal grains in Y-TZP being metastable—can shift to the monoclinic natural form at the expense of an external source of energy, i.e., the elastic stress field that yields an advancing crack. Thus, phase transformation results as an efficient dissipative mechanism for the energy that otherwise would lead to fracture. Indeed, it was evaluated that the tetragonal–monoclinic phase transformation implies (for a free grain) a volume expansion 4–5 vol %. As each grain is constrained by its neighbors (the matrix), the constrained phase transformation generates a compressive stress field that increases the energy threshold that a crack has to overcome to develop further. These concurrent, energy-dissipative, microscopic-scale phenomena above outlined result, at a macroscopic level, in the remarkable bending strength and toughness of Y-TZP (see Table 2).

**Table 2.** Selected properties of Y-TZP. Alumina data reported for comparison.

Several manufacturers worldwide started the production of Y-TZP ball heads. Among them, SGCAD—the main manufacturer of zirconia (Y-TZP) ball heads worldwide—and Kyocera (Kyoto, Japan) developed also zirconia knee condylar components for total knee replacements (TKR).

The metastability of Y-TZP is the key for its outstanding mechanical performances. However, the metastability of Y-TZP was a cause of concern since the beginning of the clinical use of Y-TZP components. In the biologic environment, Y-TZP may spontaneously transform from tetragonal to monoclinic, drastically decreasing its mechanical properties [11]. Such an undesired phenomenon is named aging or low-temperature degradation (LTD). In THR bearings, the onset of LTD at the surface of the component is related to an increase of the surface roughness, in turn leading to the wear increase of UHMWPE acetabular cups that are usually coupled to Y-TZP heads [3]. The studies on the physicochemical mechanisms giving rise to LTD are still running: several models have been proposed to explain such a behavior, but none have been fully satisfactory to date [12], although it is acknowledged that LTD kinetics is promoted by temperature (especially for T > 100–150 ◦C), by the presence of water in the environment, and by applied stresses. In addition, different LTD kinetics were observed in Y-TZP ball heads obtained from different manufacturers or from different batches produced by the same manufacturer, thus leaving open the main questions about the possible influence of the production process on LTD [13]. Finally, the unexpected high rates of failure in some batches of Y-TZP since 2000 [14] led to the abandon of its use in orthopedics.

#### **2. Biocompatibility of Alumina and Zirconia Composites**

The biological safety of alumina and zirconia and of alumina–zirconia composites has been established for a long time and was recently confirmed [15–18]. Tests on alumina, zirconia, and alumina–zirconia composites were performed using materials in the form of powders or dense ceramics, particularly addressing physicochemical features such as surface reactivity, chemical composition, impurity content, and type of stabilizer. The in vitro assays were performed using extracts in various media, in either direct or indirect contact, by using various cell lines such as macrophages, lymphocytes, fibroblasts, and osteoblasts. Similar considerations can be made on the in vivo tests, which had been performed in several implantation sites in different animal models, to analyze either adverse reactions in soft tissue and/or bone, as well as systemic toxicity. An absence of adverse reactions in cell culture either in tissues or organs after in vivo implants was observed whatever the culture conditions or the implants site.


*Article* **Mini-Map Design Features as a Navigation Aid in the Virtual Geographical Space Based on Video Games**

**Krzysztof Zagata \* and Beata Medy ´nska-Gulij**

Adam Mickiewicz University, Pozna ´n, Poland; Department of Cartography and Geomatics, 61-712 Pozna ´n, Poland

**\*** Correspondence<EMAIL_ADDRESS>Tel.: +48-61-829-6242

**Abstract:** The main objective of this study is to identify features of mini-map design as a navigational aid in the virtual geographical space in 100 popular video games for a computer platform. The following research methods were used: visual comparative analysis, classification and selection of cartographic material, comparison of specific parameters for selected features of design elements, and application of cartographic design rules and popularity of design solutions in video games. The study revealed eight features of mini-map design and their popular parameters and attributes in video games, with only one game meeting all conditions of popularity: projection: orthographic; centring: player-centred; base layers: artificial; shape: circle; orientation: camera view; position: bottom left; proportions: 2.1–3%; additional navigational element: north arrow. The key attributes of the mini-map's features were captured, which, when considered separately, complementarily and potentially holistically, confirm the possibility of designing the mini-map according to traditional cartographic design principles. The identified parameters of the mini-map can be useful not only in the design of the game cartography interface, but also for other geomedia products.

**Keywords:** mini-map; map design; virtual geographical space; navigation aid; video games; game cartography interface; graphical features

### **1. Introduction**

A video game is a complex technological system that combines many programming, geographical, cartographic, psychological and cognitive aspects [1,2]. Many video games are based on real-world concepts to represent virtual geographical space and present a series of phenomena linked by spatial information [3]. Year by year, game developers are building increasingly complex geographical spaces with the help of growing computer game engines (e.g., Unity, Unreal Engine, CryEngine, Frostbite) [4]. The subject of "cartography and games" is taken up in research in the context of designing cartographic products, game production, as well as aspects of gamification [5,6].

Maps are an integral part of cartographic research in the broad field of geomedia [7]. Maps are very often used in video games as a representation of a fictional geographical space [8]. Thanks to the basic content and the cartographic elements used, players can obtain spatial information about current events in the virtual world [9]. The design of a map under traditional conditions must be based on conscious rules and decisions due to the large variety of available methods and visual variables [10–12]. Therefore, in contrast to video game developers who do not rely on cartographic principles to design a virtual world, the authors believe it is worthwhile to investigate the relationship between the user and cartographic products in games [13,14]. Maps play an important role in common navigation both in video games and in real life by helping the user find their way and get directly from A to B [15,16].

Game cartography interfaces are practically ubiquitous in games that involve exploration and navigation of virtual geographical space [17]. As video games evolve, game

**Citation:** Zagata, K.; Medy ´nska-Gulij, B. Mini-Map Design Features as a Navigation Aid in the Virtual Geographical Space Based on Video Games. *ISPRS Int. J. Geo-Inf.* **2023**, *12*, 58. https://doi.org/10.3390/ ijgi12020058

Academic Editors: Florian Hruby and Wolfgang Kainz

Received: 12 December 2022 Revised: 24 January 2023 Accepted: 6 February 2023 Published: 8 February 2023

**Copyright:** © 2023 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/).

developers are implementing newer and newer cartographic elements such as mini-maps, compasses, arrows, cartographic symbols and others to better understand space [18]. Toups et al. [19] investigated how the player interacts with the maps during the game. Based on the analysis, they referred to the design of the cartographic interface, but also to its functionality in terms of manipulating the map and its navigational elements.

A very important element of the user interface in topographic orientation (comparison of space with a map) in the virtual geographical space is the mini-map. The mini-map, sometimes called a 'radar screen' or 'corner map', shows a miniature version of the game world, or part of it, from the perspective of the top view [20]. The mini-map usually represents a larger space than the area visible from the player's main camera [21]. The element in the game cartography interface is a kind of navigational aid that provides detailed information about the position, orientation, objects nearby or terrain around the player. The mini-map, usually created as one of the non-diegetic parts of the HUD (headsup display), provides important information to make the right decisions during the game and plays an important role in navigation in different game genres (e.g., role-playing games, multiplayer online role-playing games, racing games, shooter games, battle royale games, survival games and strategy games), and especially in open-world games [22,23].

Indeed, geographical space is closely linked to different societies of people who relate to each other through the natural environment that surrounds them [24]. On the other hand, virtual geographical space is an environment that, through rules derived from real geographical space, allows the reflection and shaping of existing geographical space or the creation of fictitious spaces based on real-world rules [25]. The basic activity in video games is to navigate through three-dimensional and two-dimensional virtual geographical spaces in order to find a way to new destinations or to freely explore the game in conjunction with the game's open world [26]. One of the tasks of cartography that has found its place in video game research over the years is to understand the definition and role of "space" [27–30]. Almost all video games with programmed gameplay mechanics allow players to memorise and assimilate new spatial knowledge, which they use to transparently employ interactive navigational elements as they move through the game world [31,32]. In the article by Si et al. [33], the term 'spatial exploration' is mentioned as a fundamental element of the game, where players increase their knowledge of geographical space and improve navigation between important topographical objects.

The main problem addressed in the research concerns the development and the selection of basic features of mini-maps design for a navigation aid in the virtual geographical space. The main objective of the study is to identify mini-map design features for a navigation aid in the virtual geographical space in video games. To achieve the main objective of the research, the specific aims are: to identify and arrange features of mini-maps according to their individual parameters and to capture key attributes for mini-map features that are considered separately, complementarily and as holistically as possible.

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

The fundamental methods of the research were: visual comparative analysis, classification and selection of cartographic material, comparison and classification of specific parameters for selected features of design elements and the application of cartographic design rules, and popularity of design solutions in video games [34–38].

To meet the research objectives, the stages of research were:

• Graphical representation of mini-map design features (Section 3.9).

### *2.1. Selection of Mini-Map Features*

The study proposes the following eight features of the mini-map: shape, position, orientation, centring, projection, base layers, proportions and additional navigation elements. After a careful analysis of the scientific literature, the authors noticed the lack of other scientific studies on the research topic under consideration. In selecting mini-map features, we were guided by the principles of the traditional cartographic map design and its components, as well as the design solution in video games [39,40]. Traditional cartographic map design principles helped enforce mini-map features such as shape, position, orientation, proportions and projection. The design of user interface elements in video games, on the other hand, helped organise features such as centring, base layers and additional navigational elements. Many of these mini-map features overlap between these two design worlds, and the combination of interdisciplinary principles allows for an objective evaluation of the design of the mini-map.

The first feature that can be used to classify the parameters of mini-maps used in video games is their shape. When creating interface elements, game developers adapt them to the commonly understood style of the game, especially its graphic design [41]. The second premise that determines the choice of the optimal shape of the mini-map is the willingness to adapt it to other elements of the user interface, which is the most important part of the navigation system due to its practical aspect [42]. The choice of the appropriate shape allows proper use of space on the user's screen (e.g., no unused spaces). The last factor considered when designing a user interface is the experience of video game developers, who sometimes choose to duplicate patterns that have worked well in other projects [43].

Another feature that characterizes the mini-map is the position of the interface elements on the screen. According to current trends in Western culture, interface elements should be located in the upper or left part of the screen, which is due to the user's reflex regarding the reading direction [44]. In the habits of Eastern cultures, on the other hand, user interface segments tend to be located at the top or right edge of the screen [45]. The relationship described above is used especially in games that require players to react quickly during the game. Placing important navigational elements in an intuitive position allows the user to significantly reduce reaction time and also avoid unnecessary clicks and deceptions [46]. In cartography, the creators of cartographic visualisations face a similar problem concerning the position of inset maps and in the map layout [47].

An important feature in the design of a mini-map is an orientation and, thus, the question in which direction the mini-map rotates in interaction with the camera of the player looking at virtual space. Considering this feature of mini-maps, it should be pointed out that it fulfils the role of a traditional compass, confirming that the mini-map should be perceived as a navigational element [48]. The choice of an appropriate orientation by video game developers facilitates the user's topographical orientation in the virtual geographical space, which affects the comfort of the game [49].

Video game developers have a choice between two types of mini-maps, depending largely on the level of detail of the world created. The mini-map can represent the entire game world, but it is possible, if not necessary, to represent many elements on the mini-map that make up the synthetic appearance of the virtual space [50]. However, some games require the representation of numerous elements that have a significant impact on the gameplay, which can affect the readability of the mini-map [51]. Here, a larger scale of the map is recommended and, thus, a stronger focus on the player's current position in the virtual world [52]. The above considerations show the importance of choosing the appropriate scale of the mini-map for the needs of a particular video game, which also argues for recognising the mini-map as a cartographic element in the user interface.

Another cartographic feature that video game developers must consider when designing a mini-map is how it is projected onto the plane. The vast majority of virtual visualisations use orthographic projection, which is perpendicular to the displayed space [53,54].

This allows the player to have a "bird's eye view" of the virtual space surrounding them, which allows them to estimate the distance more accurately between important points in the game. Perspective projection is the second type of projection, which is much less common in mini-maps. In this case, it is more difficult for the user to estimate the actual distances, as the virtual world is displayed from a certain angle and is, thus, distorted. However, this projection enables the representation of a larger field of view during the game, which allows the player to quickly develop initial ideas about the next fragments of the virtual geographical space.

An essential feature of the mini-map is the issue of the graphic design of the virtual geographical space. This aspect concerns the features of the mini-map, which, on the one hand, should fit the overall aesthetics of the interface and the game world and, on the other hand, should aim to increase navigational efficiency during the game. Choosing the right gameplay background and basic texture layers makes it easier to find one's way around the virtual space [55]. Game developers undertake to create a kind of graphic-aesthetic scheme that allows defining a closed set of markers always associated with the same topographic objects represented on the map and the mini-map (artificial layers), or on the use of unique analogies consisting in the reflection of the mini-map textures used in the game (in-game layers) [56,57]. In this way, the player has the possibility of constantly analysing the totality of the space surrounding him. Video game developers can also choose transparent layers, which allows the mini-map to focus only on the representation of cartographic symbols that are central to topographical orientation in an unfamiliar space.

The proportions of the individual interface elements on the displayed screen is another important design feature of the UI (user interface), which directly affects the appearance and readability of the game during play. The proportions of the individual elements are understood as the percentage of the area they occupy in relation to the total available screen [58]. The appropriate size of the cartographic element of the mini-map is extremely important, as too small an element size may result in insufficient visibility of the elements displayed on it, making it only a decorative element of the user interface. On the other hand, a mini-map that is too large may obscure other important elements of the video game's graphic design that may prove important during gameplay. As suggested by game designers, mini-maps should generally not exceed 10% of the available viewing area [50].

The final optional element of graphical user interface design in video games can be all kinds of navigational components designed to increase navigational efficiency when navigating virtual geographical space. A significant distinguishing feature of the criterion discussed here is the fact that it is not necessary to commit to a single additional navigational element [59]. However, when deciding on additional elements, video game designers should think about the functionality of the chosen solutions, because too much complexity in the number of elements may not make it easier or even more difficult for the user to find his way around the virtual space during the game [60,61].

### *2.2. Selection of Video Games*

The number of professional video games released grows every year, and it is impossible to describe all available games in one article. Modern technologies of computer game engines offer increasingly better ways to create a graphic design and integrate a programming environment to develop a video game. The research focuses on games published for a computer platform (PC). Another criterion for selecting a game for analysis was whether the game had a navigation element in the user interface, i.e., a mini-map.

From the large number of online portals that provide video game ratings and publish lists of popular video games in history, 14 online portals were selected. The websites were selected by the Google search engine and ranked based on the phrases "top 100 video games" and "best 100 PC video games" (17 January 2022) in order of their display on the first and second page of popularity. According to Su et al. [62], a higher position in the internet search engine enables more frequent visits by internet users.

The 100 most popular and highest rated video games on video game websites were selected and categorised. The video games were rated by website users (gamers) and video game critics based on their subjective opinion of the game. The selection of games did not take into account that the same video games were duplicated from different websites. For each criterion of the mini-map features, a game was analysed only once. games" and "best 100 PC video games" (17 January 2022) in order of their display on the first and second page of popularity. According to Su et al. [62], a higher position in the internet search engine enables more frequent visits by internet users. The 100 most popular and highest rated video games on video game websites were selected and categorised. The video games were rated by website users (gamers) and

The list of web portals analysed includes portals related to: video game critics based on their subjective opinion of the game. The selection of games

• Information services such as IGN [63–71]; did not take into account that the same video games were duplicated from different web-

*ISPRS Int. J. Geo-Inf.* **2023**, *12*, x FOR PEER REVIEW 5 of 17

On the other hand, the list of 100 games collected includes such titles as: The Witcher 3: Wild Hunt, Dead Rising 4, Grand Theft Auto V, Assassin's Creed IV: Black Flag, Forza Horizon 5, Red Dead Redemption 2, Guild Wars 2, World of Warcraft, Counter- Strike: Global Offensive, Warcraft III, Call of Duty: Warzone, Cyberpunk 2077, World of Tanks or League of Legends (Figure 1). All 100 games were installed on a computer and tested during a gameplay [Appendix A]. • gaming magazines, such as, e.g., PC Gamer [75,76]; • websites that collect surveys on different fields, such as, e.g., Ranker [77]. On the other hand, the list of 100 games collected includes such titles as: The Witcher 3: Wild Hunt, Dead Rising 4, Grand Theft Auto V, Assassin's Creed IV: Black Flag, Forza Horizon 5, Red Dead Redemption 2, Guild Wars 2, World of Warcraft, Counter- Strike: Global Offensive, Warcraft III, Call of Duty: Warzone, Cyberpunk 2077, World of Tanks or League of Legends (Figure 1). All 100 games were installed on a computer and tested during a gameplay [Appendix A].

**Figure 1.** Examples of video games with a mini-map in the game cartography interface (**A**) Red Dead Redemption 2; (**B**) Guild Wars 2; (**C**) Cyberpunk 2077. **Figure 1.** Examples of video games with a mini-map in the game cartography interface (**A**) Red Dead Redemption 2; (**B**) Guild Wars 2; (**C**) Cyberpunk 2077.

*2.3. Parameters and Attributes for Classifying Mini-Map Features*

Based on the visual analysis of the chosen 100 video game interfaces, the following parameters and attributes were classified for the selected 8 features of the mini-map (Figure 2):

*ISPRS Int. J. Geo-Inf.* **2023**, *12*, x FOR PEER REVIEW 7 of 17

**Figure 2.** Parameters and attributes for 8 mini-map features according to the chosen 100 video games ((**A**) shape, (**B**) position, (**C**) orientation, (**D**) centring, (**E**) projection, (**F**) base layers, (**G**) proportions, (**H**) additional navigational elements). **3. Results Figure 2.** Parameters and attributes for 8 mini-map features according to the chosen 100 video games ((**A**) shape, (**B**) position, (**C**) orientation, (**D**) centring, (**E**) projection, (**F**) base layers, (**G**) proportions, (**H**) additional navigational elements).

#### The analysis result in the juxtaposition form of mini-map features expressed as a per-**3. Results**

centage for each specific parameter or attribute is presented in Figure 3. The design features are listed in order from the first with the clearest indication of the preferred The analysis result in the juxtaposition form of mini-map features expressed as a percentage for each specific parameter or attribute is presented in Figure 3. The design features are listed in order from the first with the clearest indication of the preferred parameter (projection: orthographic 97%) to the last features with an unclear indication of the popularity of the parameters in the selected 100 video games.

parameter (projection: orthographic 97%) to the last features with an unclear indication of

the popularity of the parameters in the selected 100 video games.

**Figure 3.** The percentage of use of a specific parameter of the mini-map with examples of video games according to their majority unambiguity. Bold red stands for the highest percentage, solid red for a value close to the highest, blue colour for values far from the highest. \* One video game can use many additional navigational elements. **Figure 3.** The percentage of use of a specific parameter of the mini-map with examples of video games according to their majority unambiguity. Bold red stands for the highest percentage, solid red for a value close to the highest, blue colour for values far from the highest. \* One video game can use many additional navigational elements.

### *3.1. Projection*

Almost all video games used the mechanism of orthogonal projection in the mini-map to visualise the virtual world of the game (97%). Only 3% of the mini-maps used perspective projection to visualise the game space (Grand Theft Auto V, Forza Horizon 5, Watch Dogs).

### *3.2. Centring*

The vast majority of mini-maps use the mechanism of a limited field of view covering the immediate surroundings of the player (80%). The predominant option is used especially in the genres RPG (role-playing game), MMORPG (massively multiplayer online roleplaying game) and FPS (first-person shooter). Only 20% of the games choose the variant of a miniature map of the virtual world. This type of mini-map was mainly found in the game genres MOBA (multiplayer online battle arena) and RTS (real-time strategy).

### *3.3. Base Layers*

This feature is dominated by mini-maps in which artificial layered textures were used (58%). Secondly, video game developers opted for a transparent mini-map that only highlights the key elements of the game (26%). Most rarely, game developers used in-game textures of the virtual geographical space that reflected the actual view of the player's camera (16%).

### *3.4. Shape*

Most of the mini-maps (45%) are in the shape of a circle. They are followed by a rectangle (17%) and a square (16%). The least popular are unusual geometric shapes such as: irregular (11%), ellipse (6%), parallelogram (3%) and diamond (2%).

### *3.5. Orientation*

In the case of the analysed video games, more than half chose to orient themselves to the player's camera (53%). Static orientation is second (40%) and orientation to the north of the virtual geographical space is the least common (7%).

### *3.6. Position*

Holzinger et al. [78] noted that user interface elements embedded on the left side of the screen performed better than those on the right side. On the other hand, Edler et al. [79] showed in their study that the legend of the thematic map placed on the right side is read and decoded much faster than the legend on the left side. The analysis shows that the most frequently chosen position for a mini-map in the user interface is "bottom left" (36%). The next choice of developers was "top right" (31%), while the option "bottom centre" was only used in one game (1%). It can be seen that the split between the left side of the mini-map (50%) and the right side (49%) is insignificant.

### *3.7. Proportions*

For the criterion of the size of the mini-map, the range of 2.1–3% (36%) in relation to the entire screen displayed was chosen most frequently. The size options 1.1–2% (35%) and 3.1–4% (18%) were also frequently chosen. The smallest size range 0–1% (2%) and mini-maps covering a larger area of the screen: 4.1–5% (4%), 5.1–6% (1%), 6.1–10% (4%) were used least frequently.

### *3.8. Additional Navigational Elements*

Each game can have more than one additional navigational element on the user interface (mini-map is the main navigational element). Four-fifths of the video games have additional navigational elements besides the mini-maps to help the player find his way around the virtual geographical space (80%). The most popular navigational element is the north arrow, which points north in space (37%). Slightly less often, developers used peripheral arrows to indicate the destination (28%). The implementation of directional cues in the game was seen comparatively often (24%). The use of text elements was seen in 18% of games to increase the accuracy of navigation, while a compass element was introduced in 16% of games. Occasionally, a chessboard mechanism was added to the mini-map to better distinguish individual areas of the virtual world (4%).

#### *3.9. Mini-Map Composition* mini-map to better distinguish individual areas of the virtual world (4%).

*ISPRS Int. J. Geo-Inf.* **2023**, *12*, x FOR PEER REVIEW 10 of 17

Figure 4 shows a graphical representation of the most popular attributes from eight mini-map design features. The composition is the result of the percentage rating of the parameters calculated separately for each feature from Figure 3. Therefore, it can be assumed that the features should meet the following popular parameters: projection: orthographic; centring: player-centred; base layers: artificial; shape: circle; orientation: camera view; position: bottom left; proportions: 2.1–3%; additional navigational element: north arrow. It is particularly noteworthy that only one mini-map from Assassin's Creed IV: Black Flag meets the above-mentioned parameters of all eight mini-map features (Figure 4). *3.9. Mini-Map Composition* Figure 4 shows a graphical representation of the most popular attributes from eight mini-map design features. The composition is the result of the percentage rating of the parameters calculated separately for each feature from Figure 3. Therefore, it can be assumed that the features should meet the following popular parameters: projection: orthographic; centring: player-centred; base layers: artificial; shape: circle; orientation: camera view; position: bottom left; proportions: 2.1–3%; additional navigational element: north arrow. It is particularly noteworthy that only one mini-map from Assassin's Creed IV: Black Flag meets the above-mentioned parameters of all eight mini-map features (Figure 4).

around the virtual geographical space (80%). The most popular navigational element is the north arrow, which points north in space (37%). Slightly less often, developers used peripheral arrows to indicate the destination (28%). The implementation of directional cues in the game was seen comparatively often (24%). The use of text elements was seen in 18% of games to increase the accuracy of navigation, while a compass element was introduced in 16% of games. Occasionally, a chessboard mechanism was added to the

**Figure 4.** Mini-map composition on the display view (16:9) with the most popular parameters of 8 design features—by separate analysis for each parameter. **Figure 4.** Mini-map composition on the display view (16:9) with the most popular parameters of 8 design features—by separate analysis for each parameter.

#### **4. Discussion 4. Discussion**

Basic geometric shapes, such as a rectangle and a square, are usually used in designing shapes for traditional maps for navigation. The mini-map as a cartographic interface element in video games breaks with the basic principles of cartographic design by preferred use of the circle shape. Such a design of the mini-map by the game developers could be due to the fact that the shape of the circle often fits better with the graphic aesthetics of the game. The authors note an additional functionality of the shape described, as it allows symmetrical distance to be shown in any direction of the displayed space. With regard to the position feature, the lower left corner of the screen proved to be Basic geometric shapes, such as a rectangle and a square, are usually used in designing shapes for traditional maps for navigation. The mini-map as a cartographic interface element in video games breaks with the basic principles of cartographic design by preferred use of the circle shape. Such a design of the mini-map by the game developers could be due to the fact that the shape of the circle often fits better with the graphic aesthetics of the game. The authors note an additional functionality of the shape described, as it allows symmetrical distance to be shown in any direction of the displayed space.

the most frequent choice of the developers in designing the position of the mini-map. As a result of the analysis, a slight tendency to place the mini-map element at the bottom of the screen can be identified. Traditional cartographic design principles also suggest placing location maps below the main cartographic content. With regard to the position feature, the lower left corner of the screen proved to be the most frequent choice of the developers in designing the position of the mini-map. As a result of the analysis, a slight tendency to place the mini-map element at the bottom of the screen can be identified. Traditional cartographic design principles also suggest placing location maps below the main cartographic content.

The orientation, centring and projection features support the interaction between the player and the user interface. The continuous rotation of the mini-map in relation to the movement of the virtual character's camera, the display of the player's current position together with the immediate surroundings and the orthogonal projection onto the plane of the geographical space support the player in permanent topographical orientation.

As with the design of traditional topographic maps, game developers usually opt for an artificial texture layer that is distinct from the referenced geographical space. The graphic process aims to develop a pattern of navigational behaviour that enhances the interpretation of topographic objects in virtual geographic space.

The vast majority of video games favour smaller mini-maps with an aspect ratio of 1.1% to 3% of the total game screen. It can be assumed that the creators of these games intended the mini-map to play the role of an additional navigation option that enables orientation in virtual space. Even in traditional cartography, the location map is relatively small compared to the frame of the main content of the cartography.

When designing a complex navigation system, game developers do not limit themselves to individual interface elements. As the results of the analysis show, in addition to the mini-map, the developers often use other additional elements that are familiar to users from everyday life (north arrow or compass). It is worth mentioning that the above-mentioned elements are always a fixed part of the interface during the game. However, many games also use dynamic navigational elements that depend on current events or phenomena in the virtual geographical space (different types of lines or highlighted symbols).

The unexpected fact of the research that all eight parameters are fulfilled with the highest percentages by only one game gives rise to a discussion about the complementarity and holistic nature of the design process in the context of the analysis of mini-map features [80]. Therefore, the authors draw attention to the possibility of grouping several selected features instead of treating all eight features of the mini-map together. Based on the comparison in Figure 3, four design features can be identified that have clearly defined priority parameters. Figure 5 shows the four most preferred parameters, which 22 out of 100 games fulfil: projection (orthographic), centring (player-centred), base layers (artificial) and shape (circle). The four features with the addition of camera view orientation implement mini-maps from 16 games, while the addition of the north arrow implements 15 selected video games. For the position feature, an unchanged trend of slightly more mini-maps in the lower left corner of the screen was noted (10 games). However, when identifying the four priority features, the proportion of smaller mini-maps is surprisingly much larger (13 games 1.1–2%). *ISPRS Int. J. Geo-Inf.* **2023**, *12*, x FOR PEER REVIEW 12 of 17

**Figure 5.** Grouping of the most popular and preferred parameters of the mini-map features: projection, centring, base layers and shape with separate addition of other popular attributes or parameters from four other features (see Figure 3). **5. Conclusions Figure 5.** Grouping of the most popular and preferred parameters of the mini-map features: projection, centring, base layers and shape with separate addition of other popular attributes or parameters from four other features (see Figure 3).

#### In summary, the identification of mini-map design features in video games is very **5. Conclusions**

valuable for a navigational aid in the virtual geographical space. The authors focused on the selection and classification of the cartographic features of the mini-map element in the graphical user interface of video games in terms of the proposed parameters and attributes. The proposed research approach resulted in revealing eight features of mini-map In summary, the identification of mini-map design features in video games is very valuable for a navigational aid in the virtual geographical space. The authors focused on the selection and classification of the cartographic features of the mini-map element in the

design in video games, according to their most popular parameters and attributes: projection: orthographic; centring: player-centred; base layers: artificial; shape: circle; orientation: camera view; position: bottom left; proportions: 2.1–3%; additional navigational ele-

to the popular parameters and attributes, we find that only one game fulfils all conditions (Figure 4). Based on the identification and arrangement of the eight mini-map features according to their individual parameters and attributes, we can conclude that the four most commonly used attributes are: orthographic projection, player-centred view, artificial base layer, circle shape (Figure 5). The feature of mini-map position on the screen is the most difficult to define, as the bottom left and bottom right corners are similarly pre-

In response to the additional research objectives of the article, it can be stated that the fundamental elements of the mini-map most commonly found among video game designers were indicated (Figure 5). They form the core of the cartographic design of the mini-

The authors captured key attributes for mini-map features that are considered separately, complementarily and as holistically as possible, confirming the nature of mini-map design as part of an individual creative process that can be supported by traditional

map, on which further research on other evaluation criteria can be based.

ferred and the other two corners also have high usability.

graphical user interface of video games in terms of the proposed parameters and attributes. The proposed research approach resulted in revealing eight features of mini-map design in video games, according to their most popular parameters and attributes: projection: orthographic; centring: player-centred; base layers: artificial; shape: circle; orientation: camera view; position: bottom left; proportions: 2.1–3%; additional navigational element: north arrow (Figure 3). If we interpret the mini-map features individually according to the popular parameters and attributes, we find that only one game fulfils all conditions (Figure 4). Based on the identification and arrangement of the eight mini-map features according to their individual parameters and attributes, we can conclude that the four most commonly used attributes are: orthographic projection, player-centred view, artificial base layer, circle shape (Figure 5). The feature of mini-map position on the screen is the most difficult to define, as the bottom left and bottom right corners are similarly preferred and the other two corners also have high usability.

In response to the additional research objectives of the article, it can be stated that the fundamental elements of the mini-map most commonly found among video game designers were indicated (Figure 5). They form the core of the cartographic design of the mini-map, on which further research on other evaluation criteria can be based.

The authors captured key attributes for mini-map features that are considered separately, complementarily and as holistically as possible, confirming the nature of mini-map design as part of an individual creative process that can be supported by traditional cartographic design principles [81,82]. These studies also confirm the importance of map design in the context of usability, which goes hand in hand with the popularity of cartographic products in new geomedia, such as mini-maps in video games [83].

The features analysed make the mini-map an important cartographic element in the visualisation of geographical space, providing detailed spatial information in a useful form. In general, the mini-map as the main element of the game cartography interface, is designed in accordance with the principles of cartographic design. The only significant divergency from the rules of map design is the use of a circle shape instead of a traditional rectangle. However, such a divergency is related to the specificity of navigation in virtual geographic space, which is the result of the necessary adaptation of cartographic design to new geomedia.

A navigation in spaces is not limited to virtual worlds, but takes place in all activities that have to do with moving around in our world. Cartographic elements in games, such as a mini-map, fulfil many conditions that can be compared to satellite applications on mobile phones [84]. The design of these elements usually varies according to the needs of presenting and exploring the geographical space. Fundamentally, they have a common task, which is to help people navigate through real or virtual spaces. Further research should include the possibility of comparing the individual design processes to identify differences in functions and tasks.

The authors hope that the identified most popular parameters of the eight features can be useful not only in the design of video games, but also in other cartographic products dealing with virtual and augmented reality. User-centred design focuses on the needs of the player [85] and the needs of the map users [57,86]. Future projects will also need an evaluation of popular solutions by gamers and map users to determine which solutions actually work best and are not just the most popular. Given the growing interest in the video game industry worldwide, more research is needed on the optimisation and effectiveness of the user interface and cartographic products.

**Author Contributions:** Conceptualization, Krzysztof Zagata and Beata Medy´nska-Gulij; methodology, Krzysztof Zagata; formal analysis, Krzysztof Zagata; resources, Krzysztof Zagata; writing original draft preparation, Krzysztof Zagata and Beata Medy ´nska-Gulij; writing—review and editing, Krzysztof Zagata and Beata Medy´nska-Gulij. 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:** This paper is the result of research on the mini-map in the interface based on the analysis of video games carried out within statutory research on the doctorate at the Department of Cartography and Geomatics, Faculty of Geographical and Geological Sciences, Doctoral School, Adam Mickiewicz University Pozna ´n, Poland.

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

### **Appendix A**

Alphabetical list of the 100 games with a mini-map by *Name*-**Year**-Genre:

*Age of Empires II: HD Edition*-**2013**-Strategy; *Albion Online*-**2017**-MMORPG; *Anno 1404*- **2009**-Strategy; *Apex Legends*-**2019**-Action; *Assassin's Creed IV: Black Flag*-**2013**-Action; *Battlefield 1942*-**2002**-Action; *Battlefield 2*-**2005**-Action; *Battlefield 2042*-**2021**-Action; *Black Desert Online*-**2014**-MMORPG; *Borderlands 2-***2012**-Action; *Call of Duty 4: Modern Warfare*-**2007**- Action; *Call of Duty: Black Ops*-**2010**-Action; *Call of Duty: Warzone*-**2020**-Action; *Company of Heroes*-**2006**-Strategy; *Company of Heroes 2*-**2013**-Strategy; *Cossacks 3*-**2016**-Strategy; *Counter-Strike: Global Offensive*-**2012**-Action; *Counter-Strike: Source*-**2005**-Action; *Crackdown 3*-**2019**- Action; *Crysis*-**2007**-Action; *Cyberpunk 2077*-**2020**-Action; *Darksiders 2*-**2012**-Action; *Days Gone*-**2021**-Action; *Dead Cells*-**2018**-Platform; *Dead Island*-**2011**-Action; *Dead Rising 4*-**2016**- Action; *Dekaron*-**2007**-MMORPG; *Destiny 2*-**2017**-Action; *Deus EX: Human Revolution*-**2011**- RPG; *Divinity: Original Sin II*-**2017**-RPG; *Dota 2*-**2013**-MOBA; *Dragon Age: Origins*-**2009**- RPG; *DRAGON QUEST XI S: Echoes of an Elusive Age—Definitive Edition*-**2018**-RPG; *Dying Light*-**2015**-Action; *Elex*-**2017**-RPG; *Factorio*-**2020**-Strategy; *Far Cry 3*-**2012**-Action; *Far Cry 4*-**2014**-Action; *Fifa 22*-**2021**-Sports; *Final Fantasy XII: The Zodiac Age*-**2018**-RPG; *Final Fantasy XIV*-**2013**-MMORPG; *For Honor*-**2017**-Action; *Fortnite*-**2017**-Action; *Forza Horizon* 5-**2021**- Racing; *Genshin Impact*-**2020**-RPG; *Grand Theft Auto III-***2002**-Action; *Grand Theft Auto V*-**2015**- Action; *Grand Theft Auto: San Andreas*-**2005**-Action; *Grand Theft Auto: Vice City*-**2003**-Action; *Grim Dawn*-**2016**-RPG; *Guild Wars*-**2005**-MMORPG; *Guild Wars 2*-**2012**-MMORPG; *Heroes of Might and Magic III*-**2004**-Strategy; *Hitman 3*-**2021**-Action; *L.A. Noire*-**2011**-Adventure; *League of Legends*-**2009**-MOBA; *Lost Ark*-**2022**-MMORPG; *Mad Max*-**2015**-Action; *Medal of Honor*-**2010**-Action; *Medieval II: Total War*-**2006**-Strategy; *Middle-earth: Shadow of War*-**2017**- Action; *Monster Hunter World*-**2018**-RPG; *Need for Speed Payback*-**2017**-Racing; *Nioh*-**2017**- RPG; *Northgard*-**2018**-Strategy; *Orcs Must Die! 2*-**2012**-Action; *Path of Exile*-**2013**-MMORPG; *PlayerUnknown's Battlegrounds*-**2017**-Action; *Red Dead Redemption 2*-**2019**-Action; *Rome: Total War*-**2004**-Strategy; *RuneScape*-**2003**-MMORPG; *S.T.A.L.K.E.R.: Call of Pripyat*-**2009**-Action; *Saints Row 4*-**2013**-Action; *Sleeping Dogs*-**2012**-Action; *Sniper Elite 4*-**2017**-Action; *Sniper: Ghost Warrior 3*-**2017**-Action; *Spellforce 3*-**2017**-Strategy; *Star Wars: Knights of the Old Republic*-**2003**-RPG; *Star Wars: The Old Republic*-**2011**-MMORPG; *Starcraft II: Wings of Liberty*-**2010**-Strategy; *The Ascent*-**2021**-RPG; *The Binding of Isaac: Afterbirth*-2015-Action; *The Crew 2*-**2018**-Racing; *The Riftbreaker*-**2021**-Action; *The Witcher 2: Assassins of Kings*-**2011**-RPG; *The Witcher 3: Wild Hunt*-**2015**-RPG; *Titanfall 2*-**2016**-Action; *Tom Clancy's Ghost Recon: Wildlands*-**2017**-Action; *Torchlight 2*-**2012**-RPG; *Total War: Shogun 2*-**2011**-Strategy; *Valheim*-**2021**-Action; *Valorant*-**2020**-Action; *Vanquish*-**2017**-Action; *Warcraft III: The Frozen Throne*-**2003**-Strategy; *Warframe*-**2013**-Action; *Warhammer 40,000: Dawn of War—Dark Crusade*-**2006**-Strategy; *Watch Dogs*-**2014**-Action; *World of Tanks*-**2010**-Action; *World of Warcraft*-**2004**-MMORPG; *Yakuza 5 Remastered*-**2021**-Action.

### **References**

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**1. Introduction**

The needs of modern aviation for a safe and reliable source of fuel are without question. Safe fuels must among other things, be able to be stored for periods of time and be compatible with similar fuels from other sources. For commercial uses, long-term storage is not normally required, since most fuel is used within a few months of refining although longer periods may be required at smaller airports. The military, however maintains much larger stockpiles of fuel in reserve for use in case of emergencies.

The composition of jet fuel can vary significantly depending on the refining process and the source of crude oil. Compatibility can be an issue, since storage tanks are normally refilled when they reach a certain level, and fuels from different suppliers are mixed, even though

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compatibility issues are possible. Other aspects of storage standards require that the fuel remain free of contaminants, including surfactants, other petroleum products, microorganisms and dyes. All of these types of contaminants can arise from many sources, but careful storage can minimize the hazards associated with some.

The storage and delivery of aviation fuels is carefully regulated and must meet certain standards Including maintaining the purity of the fuel and safety of the aircraft and ground crew [1]. In this chapter, the contamination of fuel from only a few sources will be considered; in particular water contamination, contamination with solids formed by reaction to the fuel with oxygen and contamination due to microorganisms. Finally, some of the challenges associated with the transition to alternate fuels will be discussed.