Applied Mechanics and Materials Vols. 479-480

Abstract: Formic acid has attracted much of interest due to potential using in Direct-formic acid fuel cells. Photosynthesized formic can be used as the hydrogen carrier because it is liquid at standard temperature and pressure. It is much safer and easier for handling and storing than hydrogen. It can be directly fed to the fuel cell and not need to be reformed. In this paper formic acid was artificially photosynthesized in photocatalytical reactor using Iron ion doped TiO₂. Water was used as a hydrogen source. CO₂ was introduced using continuous bubbling. Highest formic acid yield was obtained at 600W visible light irradiation using 3g/L photocatalyst load and 5L/min CO₂ gas flow rate at continuous stirring. Resulted acid was characterized using UV-visible absorbance spectrophotometer and gas chromatography (GC).

Abstract: Advances in nanofabrication have resulted in great potentials for improving in both device performance and the manufacturing process of various applications. One revolutionary example is silicon (Si) nanostructures, typically using Si nonopore arrays or Si nonowire arrays, to construct high efficient and low-cost solar cells. In this work, we develop the innovative combined nanostructure arrays with tailored structural profiles using inexpensive, simple and rapid etching processes, whose total reflection is suppressed to 1.6%, approximately 39% less than Si nonopore arrays, and 20% less than Si nanowire arrays. In addition, systematic investigations on wettability of textured Si surfaces reveal the inherent surface oxidation during etching process. These combined nanostructure arrays with tailored antireflection performances, along with the in-depth studies of underlying etching mechanisms, may benefit both the yield and cost efficiently in industrial standard of silicon solar cells.

Abstract: In this work, we report the preparation of transition metal deposited flexible multiwalled carbon nanotube buckypaper for thermoelectric applications. MWCNT buckypaper prepared by dispersion and filtration method was then deposited with the transition metals such as silver (Ag) and copper (Cu) by the electrodeposition method. We measured the voltage yield of Ag and Cu-doped buckypaper by making the temperature gradient along the sample. We established the temperature dependent Seebeck coefficient for Ag and Cu-doped buckypaper and found significant increase in the S(T). It is also revealed that remarkable rise in the value of S(T) and output voltage by connecting 3-sheets of BP in series. Here we determined the enhancement of Seebeck coefficient by increasing the number of BP sheets, thereby improving the thermoelectric efficiency. Furthermore, these paper-like CNT films show good flexibility, which makes them possible to be widely applied in various flexible energy conversion devices.

Abstract: In this work, we investigate the morphology and microstructure of the aggregates, and the gelation behaviour of Poly(3-hexylthiophene) (P3HT) conjugated polymer in xylene solution as functions of P3HT concentration and aging time by the means of ageing time test, wide angle X-ray diffraction (WAXD), scanning electron microscopy (SEM), UV-visible absorption (UV-vis) and photoluminescence (PL) spectra. The result reveals that the gelation time of P3HT/xylene solution decreases markedly with increasing P3HT concentration. The photophysical properties of the P3HT aggregates in P3HT/xylene solution increase as P3HT concentration and ageing time are raised. It indicates that the well soluble P3HT polymer chains in xylene solution present microphase separation and self-assemble into stiff sheetlike structure, which associates by rodlike nanowhiskers of P3HT polymers during aging. Upon prolonged aging, the sheetlike structure of P3HT aggregates to from the three-dimension network that improves the electronic particle mobility in the organic solar cell.

Abstract: This paper investigates the statistical dynamic behaviors of nonlinear vibration of the fluid-loaded double-walled carbon nanotubes (DWCNTs) by considering the effects of the geometric nonlinearity and the nonlinearity of van der Waals (vdW) force. Besides, the small scale effects of the nonlinear vibration of the DWCNTs are studied by using the theory of nonlocal elasticity. The nonlinear governing equations of the fluid-conveying DWCNTs are formulated based on the Hamilton's principle. The Young's modulus of elasticity of the DWCNTs is assumed as stochastic to actually describe the random material properties of the DWCNTs. By utilizing the perturbation technique, the nonlinear governing equations of the fluid-conveying can be decomposed into two sets of nonlinear differential equations involving the mean value of the displacement and the first variation of the displacement separately. Then we adopt the harmonic balance method in conjunction with Galerkin's method to solve the nonlinear differential equations successively. Some statistical dynamic response of the DWCNTs such as the mean values and standard deviations of the amplitude of the displacement are computed; meanwhile the effects of small scale coefficients on the statistical dynamic response of the DWCNTs are investigated.

Abstract: This paper proposed a gate location optimization scheme to minimize the maximum injection pressure in plastic injection molding. The method utilized a series of higher order response surface approximations (RSA) to model the maximum injection pressure distribution with respect to gate locations, and the global minimum of these response surface models were subsequently sought by a global optimization method based on a multi-start sequential quadratic programming technique. The design points for RSA were evaluated by the finite element method. After a sequence of repetitions of RSA and optimization, the converged minimizer would represent the optimal gate location. A rectangular plate with two segments of different thicknesses was selected to demonstrate the effectiveness of the procedure. The variation of the thicknesses causes the optimal gate location to deviate from the center and induce multiple valleys in the maximum injection pressure distribution, which is ideal for the application of the higher order RSA and a global searching technique.

Abstract: A novel design of photonic crystal waveguide crossing with taper structure is proposed. Simulations are performed by finite-difference time-domain method. The results show the proposed design has both high transmission and low cross talk characteristics. The transmission band and low cross talk band can be tuned to match each other by adjusting the taper structure..

Abstract: In this study, we proposed a method for measuring photoplethysmographic using a smartphone camera. A development algorithm is consists 6 procedures. The first is to convert RGB to Gray level from a camera image, the second is to detect ROI from image, the third is to extract photoplethysmography signal from a camera image, the fourth is to filter baseline, and the last is to oversample procedure using cubic spline interpolation. The proposed algorithm has been tested using several smartphone with a person and which can effectively acquire persons PPG signal at any situation. We supposed that the proposed algorithm can easily adapt for a smartphone m-health system.

Abstract: The purpose of this study was to analyze treatment effect for skin aging according to changes of fluence and pulse duration of 1064nm Nd:YAG laser. For this purpose, we designed skin model composed of epidermis, dermis, and fat, and each layer had similar thickness of facial skin. Environmental temperature was set to 26°C, and the initial temperature of each skin layer was designated as human body temperature (36.5°C). The fluence of the treatment laser was divided into 8, 9 and 10J/cm², and the pulse duration was classified to 0.35, 0.50, 0.70 and 1.00ms, respectively. Based on experimental results, we found that the skin temperature increased along with penetration depth as increase in fluence. In addition, the treatment condition with fluence of 8J/cm² and pulse duration of 0.7ms, as well as fluence of 9J/cm² and pulse duration of 0.5ms, transmitted the heat into the dermis most effectively without any skin damage.

Abstract: The main purpose of this research is to construct a laboratory for testing standard. It refers to the spirit of ISO/IEC 17025 Standard, and follows Guide to the Expression of Uncertainty in Measurement (ISO GUM) made by ISO organization. The content includes UV test system construction, UVB transmittance measurement uncertainty, and the plan of measurement quality assurance that assures the stable operation of the laboratory system. Construct the equations of measurement uncertainty by the system methods that apply to the UVB transmittance measurement of car insulation film, and evaluate the variance with transmittance measurement measured by UV spectroradiometer. As for the results of transmittance measurement, the transmittance is between 0.87214 and 1.02146(%) with single wavelength of 294.5nm. There is little difference between the manufacturer label value and the measured one. The verification proofs the effectiveness of the system, and allows the tests of commercial UV-cut products fit the international and world standards.