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Ag-alloyed Cu2ZnSn(S,Se)4 kesterite semiconductors have been attracting considerable attention recently because doping with Ag can suppress the CuZn related anti-site defects, which is the main factor that limits the efficiency of kesterite solar cells. Although the performance of the thin film and the device is enhanced (for example, better crystallinity, fewer deep level defects and longer lifetime of the minority carrier) by doping a small amount of Ag in the CZTS thin film, the density of the defects remains high, and the band alignment of CdS/CZTS is not fully optimized, and the interface carrier concentration is greatly decreased. These phenomena will limit any further improvement in efficiency. In this work, to further increase the performance of the device, the interface of CdS/CZTS for an Ag-alloyed CZTS thin film solar cell was doped with In or Al. Then the properties of the thin film, interface band structure and device performance were investigated. After doping the interface with In or Al, the concentrations of the n-type and p-type carriers at the CdS/CAZTS heterojunction were boosted, and the interface band alignment was optimized, resulting in over 11% efficiency for an Ag-alloyed CZTS (with Al interface doping) thin film solar cell. Moreover, low-cost Al-doped ZnO (AZO) was used to replace indium tin oxide (ITO) as the front electrode after optimization, and more than 10% efficiency of CAZTS device without In was obtained. This study demonstrates the feasibility of controlling the doping of the interface to improve the interface performance of a heterojunction by using a simple spin coating process, and also provided a suitable experimental basis for future low-cost thin film solar cells.

The optimal planning of grid-connected microgrids (MGs) has been extensively studied in recent years. While most of the previous studies have used fixed or time-of-use (TOU) prices for the optimal sizing of MGs, this work introduces real-time pricing (RTP) for implementing a demand response (DR) program according to the national grid prices of Iran. In addition to the long-term planning of MG, the day-ahead operation of MG is also analyzed to get a better understanding of the DR program for daily electricity dispatch. For this purpose, four different days corresponding to the four seasons are selected for further analysis. In addition, various impacts of the proposed DR program on the MG planning results, including sizing and best configuration, net present cost (NPC) and cost of energy (COE), and emission generation by the utility grid, are investigated. The optimization results show that the implementation of the DR program has a positive impact on the technical, economic, and environmental aspects of MG. The NPC and COE are reduced by about USD 3700 and USD 0.0025/kWh, respectively. The component size is also reduced, resulting in a reduction in the initial cost. Carbon emissions are also reduced by 185 kg/year.

The composting experiments on three manures (cattle, pig and chicken manures) were carried out to study the maturity indexes by monitoring their physical and chemical properties, seed germination index (GI), and characterizing chemical structures using Fourier transform infrared (FTIR) spectroscopy. Results showed that temperature changed during composting, and the numbers of peak temperatures for cattle, chicken, and pig manures were 1, 2 and 2, respectively. The duration with temperature higher than 50 ℃ was longer than 10 days for all the three manures. This indicated that temperature was the most intuitive maturity index. The pH of pig and chicken manures increased from 6.63 to 7.74 and from 7.73 to 8.66, respectively, while that of cattle manure first increased from 7.86 to 8.36 and then decreased to 7.52. The organic carbon content decreased by23.3%, 28.2%, and 31.7%, respectively, for cattle, pig and chicken manures. In addition, the NH选择新鲜的牛粪、猪粪和鸡粪为堆肥原料,通过室内模拟直接堆肥试验,研究堆肥过程理化参数变化、种子发芽指数以及腐熟物红外光谱特征.结果表明: 堆肥过程温度变化明显,牛粪出现一次堆肥高温阶段,鸡粪和猪粪各两次,堆肥温度超过50 ℃以上时间均大于10 d,温度可以最直观地表征堆肥的腐熟程度.堆肥过程中pH值变化幅度较大,其中猪粪的pH值从6.63上升至7.74,鸡粪从7.73上升至8.66,牛粪则先从7.86上升至8.36再下降至7.52;有机碳含量逐渐降低,牛粪、猪粪和鸡粪分别下降23.3%、28.2%和31.7%;堆肥过程中,牛粪、猪粪和鸡粪的铵态氮含量分别下降87.8%、73.6%和79.7%,硝态氮含量分别增加至堆肥前的56.81、6.49和4.85倍,铵态氮/硝态氮均下降至2以下.温度、pH值、有机碳含量和铵态氮/硝态氮能较好地反映3种粪便高温堆肥的腐熟程度,且与种子发芽率相关性较高(

To improve the Analog to Digital Converter's (ADC's) effective quantizer bits of wideband signals as linear frequency modulation (LFM) signal, a method based on the fractional Fourier transform (FRFT) is proposed. The expression of the signal-to-quantization-noise ratio (SQNR) in the FRFT domain is obtained. In comparison to the traditional methods in the Fourier domain, about 1.5 bits of improvement in effective quantizer bits are obtained. Simulation results validate the correctness of the theory and show the effectiveness of the proposed method in the fractional Fourier domain.

Signal sampling is an important part of digital signal processing system. In the conventional sampling processing, the sampled signal is always analyzed in the Fourier transform (FT) domain. In this paper, we apply the fractional Fourier transform (FRFT) analysis into sampling processing. This study presents a quantitative signal-to-noise ratio (SNR) analysis of sampled data in the FRFT domain and introduces a new sampling method under sub-Nyquist rate based on FRFT. In contrast to the FT-based analysis method, we can achieve greater SNR and reduce the sampling rate of an Analog to Digital converter (ADC) in the FRFT domain.

Laminated bamboo composite (LBC) has received a great attention due to its environmental friendly characteristics and excellent physical and mechanical properties, therefore it is necessary to investigate the durability of the LBC material in ambient environment (temperature and relative humidity). In this paper, firstly, LBC materials were manufactured in laboratory. Moisture absorption and thickness swelling kinetics of the materials at different temperatures and relative humidity were investigated. Then effects of ambient environment on mechanical properties were evaluated at three different ambient temperatures (21 °C, 36 °C, and 60 °C) and different moisture contents. It is found that the moisture absorption and the thickness swelling increase with temperature, relative humidity and ageing time before an equilibrium condition is satisfied. Parameters of the diffusion coefficient and the swelling rate increase with the temperature. In addition, there is a significant decrease in mechanical properties of the moisture-saturated specimens compared to the dry ones. And the degradation of the bending property and the compressive strength is found to be a function of the moisture absorption during the initial period and becomes stable as the absorption process approaches equilibrium. Finally, surface erosions are shown by scanning electron microscopy (SEM) after the hydrothermal aging at 60 °C.

The objective of this work was to use a novel 3-D test analysis system for evaluating the mechanical properties of the natural fiber fabric composites under biaxial loads. Composites with three resin matrices (water-based epoxy resin, isocyanate resin, phenolic resin) were investigated, and strain filed were characterized by using the digital speckle correlation. The water-based epoxy resin plate and isocyanate resin plate demonstrated a characteristic of orthotropy and elastoplasticity, while the phenolic resin board revealed linear elastic and brittle-fracture simultaneously at X,Y-axial. Dissimilarities of biaxial load value were related to the orthotropy of composite structure, and load changes in fracture direction had a negative effect on the other directions at breaking moment. The degrees of dropping presented a positive correlation with the load values at rift direction. Under the linear elastic stage, the value of load and average strain at Y-direction were larger than that under X-direction within the same testing area. The strain-filed at X/Y-direction provided by isocyanate and phenolic resin plates illustrated a more smooth change than that of the water-based epoxy resin plate.

To evaluate the mechanical properties of natural fiber fabrics with the characteristic of interweaving between warp and weft direction as well as textile structural composites under complex stress state, it is essential to develop experimental techniques to realize multi-axial testing for large deformation. This work proposes a novel testing device for investigating fiber fabrics and textile composites under multidimensional loads. Accuracy of the system is comparable to the testing diagnostics of the Instron 5808 previously. The homogeneity for different types of cruciforms and different biaxial tensile speeds were investigated. The effects of different loading methods, biaxial (X and Y), and 3-D loading (X, Y, and Z) on the breaking strength of the woven ramie fabric were presented. The displacement-field and shear field for composites with hole were characterized by the digital speckle correlation method.

The structures and qualities of main chemical compositions in cell wall of bamboo treated with gamma rays were tested by nuclear magnetic resonance spectrometer (NMR) and X-ray Diffraction (XRD). The result indicated that the bamboo crystallinity increased at the beginning of irradiation process, while the crystallinity reduced when the irradiation dose was raised to about 100 kGy. During the whole irradiation process, hemicellulose degraded, and with the irradiation doses increased the non-phenolic lignin changed to the phenolic.