5. Conclusions

Acoustic noise measurement in the vicinity of the investigated open-air MRI device yielded the maximum sound pressure level of about 82 dB(C) at the distance of 45 cm from the central point of the MRI scanning area for the GE scan sequence with short TE and TR times and the sagittal orientation of scan slices. For examination of other parts of the human body (leg, arm, etc.), the head is not inserted directly between the upper and the lower gradient coils, so the noise level is much lower as documented for different distances in Figure 10. Finally, the scanning times for the mostly used 3D or Hi-Res sequences are in general less than 15 minutes (typically about 3–5 minutes depending on the chosen number and thickness of the slices)—exposition of the examined person and his/her hearing system to the noise and vibration is not significant.

If there is need for more detailed MR images with higher quality factor QF (e.g., in scanning of particular parts of the human brain, the eye, the middle and inner ear, etc.), the time duration TDUR can be much longer (more than half an hour). In such a case, the long exposition to the vibration and acoustic noise may impose great physiological and psychological stress on the patient. Therefore, these scan parameters should be chosen only in the urgent cases.

The results of the performed measurements are useful for precise description of the process of the mechanical vibration excitation and the acoustic noise radiation in the scanning area and in the vicinity of the MRI device. The measurement results and comparisons with a similar low-field MRI tomograph can be used in optimization of the acoustic noise suppression in the speech recorded parallel with application of MRI scanning for 3D modeling of the human vocal tract [19].

Author details

\*, Anna Přibilová2 and Ivan Frollo1

Information Technology, SUT, Bratislava, Slovak Republic

\*Address all correspondence to<EMAIL_ADDRESS>
provided the original work is properly cited.

1 Institute of Measurement Science, SAS, Bratislava, Slovak Republic

2 Institute of Electronics and Photonics, Faculty of Electrical Engineering and

Analysis of Energy Relations between Noise and Vibration Produced by a Low-Field MRI Device

DOI: http://dx.doi.org/10.5772/intechopen.85275

© 2019 The Author(s). Licensee IntechOpen. 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,

Jiří Přibil1

115

#### Acknowledgements

This work was funded by the Slovak Scientific Grant Agency project VEGA 2/ 0001/17 and the Ministry of Education, Science, Research, and Sports of the Slovak Republic VEGA 1/0905/17, and the Slovak Research and Development Agency, project no. APVV-15-0029.

### Conflict of interest

The authors declare no conflict of interest.

Analysis of Energy Relations between Noise and Vibration Produced by a Low-Field MRI Device DOI: http://dx.doi.org/10.5772/intechopen.85275


**3. Optimization of graphene electrode-electrolyte for supercapacitors**

Carbon materials with large surface areas for charge storage are now the most researched materials. Despite these huge precise surface areas, the charges substantially deposited on the carbon electrodes. The deposition is somehow restricted by many factors, such as volume expansion, layer formation on the surface, surfaceto-volume ratio, etc. [72]. Therefore, an alternate electrode material is needed to enhance the performance of supercapacitor electrodes. Metal oxides and graphene is considered to be the exceptional electrode ingredients to enhance the performance of supercapacitors.

Electrolyte parameters, particularly specific capacitance and energy density are critical in determining the capacitive efficiency of electric double-layer capacitors (EDLCs). In particular, electrolytes with such a large electrochemical stability window (ESW) can provide superior specific capacitance as well as density, and that is why ionic liquid-based electrolytes have received a lot of attention. The quantity of ionic liquid (IL) is a significant parameter for controlling its viscosity, potential window, and ionic conductivity, which is represented in the EDLC working voltage and has yet to be well investigated [73]. A pseudocapacitor achieves charge aggregation by faradic reactions (redox reactions) of redox-active materials deposited on the electrodes or immersed in fluids. Because of their excellent redox characteristics, metal oxides have frequently been employed as cathodes for those deposited on the electrodes [74].

Graphene-based micro-supercapacitors on standard Xerox paper substrates were created in response to future demands for flexible, simple, and moderate energy storage devices. To enhance the overall performance of the device, the usage of redox-active species (iodine redox couple) was investigated. At 6.5 mA cm−3, the

*Perspective Chapter: Graphene Based Nanocomposites for Supercapacitor Electrodes DOI: http://dx.doi.org/10.5772/intechopen.106050*

smart printed device based on graphene composite had an amazing high volumetric capacitance of 29.6 mF cm−3 (volume of entire device). These electrodes contain redox-active potassium iodide. Surprisingly, the device demonstrated enhanced volumetric capacitance of 130 mF cm−3. In an H2 SO4 solution, the maximal density for a graphene +K device was determined to be 0.026 mWh cm−3 [75].

Surjit Sahoo et al. [76] described a unique supercapacitor device that uses 2D graphene sheets as electrode material. The markedly high energy storage and a porosity PVDF electrolyte incorporating TEABF4 as a solid-like piezo-polymer separator were used. When placed under stress, stresses ranging from 5 to 20 N, the porous PVDF film produced a voltage ranging from 4 to 11 V. The graphene polymer composite device had the highest particular device capacitance of 28.46 F g−1 (31.63 mF cm−2) as well a specific energy of 35.58 Wh kg−1, as well as a great power density of 7500 W kg−1. The above discussion shows that the optimum composition of electrolyte, as well as electrode configuration, is very important to obtain high capacity as well as cyclability.


count\_Km[m,1] counts the number of transitions m -> 0 in the 22 years for fixed i # count\_Km[m,2] counts the number of transitions m -> 1 in the 22 years for fixed i # n\_m0[dias,m] counts the number of transitions m -> 0 in the 22 years for each i # n\_m1[dias,m] counts the number of transitions m -> 1 in the 22 years for each i


*Article* **Research on the Spatial–Temporal Distribution and Morphological Characteristics of Ancient Settlements in the Luzhong Region of China**

**Mengfei Tong 1, Baihao Li 1,\* and Zhao Li 2**

**Abstract:** This paper focuses on ancient settlements in the Luzhong region (the centre of Shandong Province) of China and analyses the spatial–temporal distribution and morphological characteristics of ancient settlements with the help of GIS technology and the perspectives of archaeology and cultural geography. Specifically, the 1972 settlements collected were used to establish a database of settlement site attributes. Then, the DEM data were superimposed with the settlement sites, and calculations of the kernel density, elevation, slope, aspect, and buffer zone were further carried out. The distribution and characteristics were refined based on quantitative and qualitative analyses. The study found that the Neolithic period, the Shang–Zhou period, and the Qin–Northern and Southern Dynasties were the three high points of settlement development. In these three periods, the centres of the largescale distribution of settlements experienced changes from a "single centre" to a "continuous belt" to a "double centre'. In general, the spatial and temporal characteristics of the settlement distribution were continuously developed through time, while the spatial characteristics show that the main body continued to change locally. In different periods, settlements tended to be in the alluvial plains located between 20 and 60 m and with a slope of less than 6◦. At the same time, they showed the obvious characteristic of living close to water. The past, present, and future are in the same chain of time; meanwhile, these settlements are the predecessors of today's cities, towns, and villages. So, this study provides a basis for protecting their heritage value and provides a reference for the coordination of human–land relations, which can help achieve global sustainable development.

**Keywords:** ancient settlements; urban heritage; spatial–temporal distribution; morphological characteristics