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Search Results: 1 - 10 of 9591 matches for " Xiangbin Zeng "
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Simulation and Optimization Characteristic of Novel MoS2/c-Si HIT Solar Cell  [PDF]
Sue Xu, Xiangbin Zeng, Wenzhao Wang, Guangtong Zhou, Yishuo Hu, Shaoxiong Wu, Yang Zeng
Journal of Minerals and Materials Characterization and Engineering (JMMCE) , 2017, DOI: 10.4236/jmmce.2017.55027
Abstract: Monolayer MoS2 has excellent optoelectronic properties, which is a potential material for solar cell. Though MoS2/c-Si heterojunction solar cell has been researched by many groups, little study of MoS2/c-Si solar cell physics is reported. In this paper, MoS2/c-Si heterojunction solar cells have been designed and optimized by AFORS-HET simulation program. The various factors affecting the performance of the cells were studied in details using TCO/n-type MoS2/i-layer/p-type c-Si/BSF/Al structure. Due to the important role of intrinsic layer in HIT solar cell, the effect of different intrinsic layers including a-Si:H, nc-Si:H, a-SiGe:H, on the performance of TCO/n-type MoS2/i-layer/p-type c-Si/Al cell, was studied in this paper. The results show that the TCO/n-type MoS2/i-layer/p-type c-Si/Al cell has the highest efficiency with a-SiGe:H as intrinsic layer, efficiency up to 21.85%. The back surface field effects on the properties of solar cells were studied with p + μc-Si and Al as BSF layers. And the effect of various factors such as thickness and band gap of intrinsic layer, thickness of MoS2, density of defect state and the energy band offset of MoS2/c-Si interface of TCO/n-type MoS2/i-layer nc-Si:H/p-type c-Si/Al cells, on the characteristics of solar cells, have been discussed for this kind of MoS2 heterojunction cells. The optimal solar cell with structure of TCO/n-type MoS2/i-type nc-Si:H/p-type c-Si/BSF/Al, has the best efficiency of 27.22%.
The High Surface Ratio Micro-MoS2 Grain Composed of MoS2 Nanosheet Prepared with One-Step Hydrothermal Synthesis  [PDF]
Guangtong Zhou, Xiangbin Zeng, Wenzhao Wang, Yishuo Hu, Sue Xu, Shaoxiong Wu, Yang Zeng, Wen Jing, Tingting Ren, Zhenyu Guo, Pengfei Xu, Haoran Li, Yushu Tang
Journal of Minerals and Materials Characterization and Engineering (JMMCE) , 2018, DOI: 10.4236/jmmce.2018.63026
Abstract: Micro molybdenum disulfide was prepared with one-step hydrothermal method; the influence of reactant concentration and temperature on the surface ratio of micro-MoS2 grain was investigated. Raman spectroscopy (Raman), X-ray diffraction (XRD), and Scanning electron microscopy (SEM) were used to characterize the structure, composition and morphology of MoS2. The results show that micro-MoS2 grains were synthesized with one-step hydrothermal synthesis, and the morphology of micro-MoS2 grains is like flower and sphere. The SEM figures indicate that the surface ratio of micro-MoS2 grains is different and also show that the surface ratio of micro-MoS2 grains can be improved by regulating reactant concentration and temperature. This research showed a method to improve the surface ratio of micro-MoS2 grains.
Reply to Cen LiXiang, Li XinQi, and Yan YiJing: No adiabatic conditional geometrical phase shift
Wang Xiangbin
Physics , 2002,
Abstract: Much long before the appearing time of the Comment by Cen, Li, and Yan,, the main issue addresed there by Cen et al had been resolved already. The information offered by the Comment is selective and misleading.
Environmental and Health Impact of Solid Waste Disposal in Developing Cities: A Case Study of Granville Brook Dumpsite, Freetown, Sierra Leone  [PDF]
Foday Pinka Sankoh, Xiangbin Yan, Quangyen Tran
Journal of Environmental Protection (JEP) , 2013, DOI: 10.4236/jep.2013.47076
Abstract:

Indiscriminate disposal of solid waste in dumpsites located within urban areas has proved to be a problem to nearby residents in most developing cities of the world, Freetown is no exception. Open dumps have environmental safeguards; they can pose major public health threats and environmental effects in urban cities. Therefore, this paper presents the findings of a research carried out in Freetown municipal area in Sierra Leone to determine the environmental and health impacts of solid waste disposal at Granville Brook dumpsite on the surrounding human settlements. Data were collected from three hundred and ninety eight nearby dumpsite household residents (less than fifty metres) and two hundred and thirty three far away household residents (more than fifty metres) through the use of structured self-administered questionnaires. Interviews and personal observations were also used to collect some of the data. Descriptive statistics involving tables, graphs and figures were used to present and analyze the data. Results show that both nearby residents and far away residents suffered from related diseases such as malaria, chest pains, diarrhea and cholera, due to the location of the dumpsite closer to their settlements. As a result, this study highlights the need for the Freetown City Council to properly manage and relocate the dumpsite to a safe distance from all human settlements, and provide resettlement and environmental education programmes for all persons living less than fifty metres away from the dumpsite as interim measures.

Evaluating the effect of price and non-price policy intervention on rice cultivation in Sierra Leone: A supply response model approach  [PDF]
Alhaji Mohamed Hamza Conteh, Xiangbin Yan
Agricultural Sciences (AS) , 2014, DOI: 10.4236/as.2014.51005
Abstract:

Rice is the main food for over 95 percent of the Sierra Leonean populace. It accounts for the largest portion of the agricultural GDP of the country. On the contrary, its cultivation has been shrinking over the past decades. Consequently, importation now becomes the main source of supplying the grain for local needs since its cultivation or production could no longer meet domestic request. The deterioration in the local cultivation of rice has had severe socio-economic implications such as higher consumer prices and balance of payment burden. Therefore, the main objective of this study is to evaluate the effect of price and other related nonprice policy intervention on rice cultivation in the country. The tools utilized for analyzing the problem comprise, a coefficient of protection analysis as well as a supply response analysis by means of a time series regression (for the period 1980-2011). Major limitations established negatively affecting rice output are price disincentives to cultivators, public expenditure and fertilizer consumption. From the above findings, rice cultivators should be accorded the necessary incentives to keep them more effective in the rice cultivation career. The food policy approach that had over the years depended on huge importation of rice should be reviewed in favor of domestic cultivation. Increasing local cultivation through a meaningful protection of cultivators can independently reduce the price of rice to the advantage of the final consumers. This study also recommends that public funds should be redirected away from rice import toward investments in its domestic cultivation.

Non-adiabatically detecting the geometric phase of the macroscopic quantum state with symmetric SQUID
Wang Xiangbin,Matsumoto Keiji
Physics , 2001, DOI: 10.1103/PhysRevB.65.172508
Abstract: We give a simple way to detect the geometric phase shift and the conditional geometric phase shift with Josephson junction system. Comparing with the previous work(Falcl G, Fazio R, Palma G.M., Siewert J and Verdal V, {\it Nature} {\bf 407}, 355(2000)), our scheme has two advantages. We use the non-adiabatic operation, thus the detection is less affected by the decoherence. Also, we take the time evolution on zero dynamic phase loop, we need not take any extra operation to cancel the dynamic phase.
The influence of price on rice production in Sierra Leone  [PDF]
Alhaji Mohamed Hamza Conteh, Xiangbin Yan, Foday Pinka Sankoh
Agricultural Sciences (AS) , 2012, DOI: 10.4236/as.2012.34054
Abstract: Rice is the main staple food of the vast majority of Sierra Leoneans, eaten on a daily basis by almost every household in the country. Rice is the most important food crop widely grown by farmers across the country. Although much attention is now focused on rice production through the small holder commercialization programme (SHCP), less attention has been given to investigating the constraints faced by rice producers in the country. Also, as food insecurity continues to be a major development problem across the country, thereby undermining people’s health, productivity, and often their very survival; this study contributes to efforts to overcome the development challenges posed by food insecurity necessarily begin with accurate assessment of influential factors that constrained the production of the staple food, rice. The main objective of this study is therefore to analysis the factors that influence rice production in the country, and specifically examine the relationship between rice production and the price of rice as sold in the domestic market. The study used a log linear model with the quantity of rice produced as the dependent variable and the price of domestic rice, quantity of rice imported and price of imported rice as explanatory. Findings indicated that, domestic rice is more expensive than imported rice per ton, and this underscores the argument that, rice importation is undermining domestic rice production as a viable income generating activity. Also, almost all the people in the capital city which hosts about 70% of the total population of country prefer eating imported rice, since it is free from stones and other impurities. However, In order to control price and still increase rice production, the government should be able to purchase the rice from the farmers and then sell this rice to private retailers.
A Situational Assessment of Socioeconomic Factors Affecting Solid Waste Generation and Composition in Freetown, Sierra Leone  [PDF]
Foday Pinka Sankoh, Xiangbin Yan, Alhaji Mohamed Hamza Conteh
Journal of Environmental Protection (JEP) , 2012, DOI: 10.4236/jep.2012.37067
Abstract: The generation of solid waste has become an increasing environmental and public health problem, especially in developing countries. These problems associated with the generation of solid waste are part of social changes where households play an important role. Invariably, these social changes influence the size, structure and characteristics of given households. This paper presents the findings of a study carried out in Freetown municipal area in Sierra Leone to assess socioeconomic factors affecting household solid waste generation and composition in Freetown, Sierra Leone. Structured questionnaires were administered with respect to these socioeconomic factors in four (4) selected constituencies of the city. These are the most populated constituencies that generated 70% of the total quantity of solid waste in the city. Therefore, they are suitable samples of the study area. The rate of waste generation was determined by using door- to-door approach in five (5) selected households from each constituency through sorting and weighing of solid wastes respectively. The dependent variables were solid waste generation and composition, and the independent variables were family size, education, income levels among others. The data obtained were subjected to statistical analysis to determine relationships between independent variables and dependent variables through correlation. The results showed that the solid waste generation and composition in Freetown was significantly affected by average family size, employment status, monthly income, and number of room(s) occupied by households. In general, the paper adequately suggests new insights concerning the role of socioeconomic factors in affecting the generation and composition of household solid waste.
Performance of Cross-Layer Design with Antenna Selection and Imperfect Feedback Information in MIMO Systems
Xiaoyu Dang,Xiangbin Yu,Xiaomin Chen
International Journal of Antennas and Propagation , 2012, DOI: 10.1155/2012/328457
Abstract: By combining adaptive modulation and automatic repeat request, a cross-layer design (CLD) scheme for MIMO system with antenna selection (AS) and imperfect feedback is presented, and the corresponding performance is studied. Subject to a target packet loss rate and fixed power constraint, the variable switching thresholds of fading gain are derived. According to these results, and using mathematical manipulation, the average spectrum efficiency (SE) and packet error rate (PER) of the system are further derived. As a result, closed-form expressions of the average SE and PER are obtained, respectively. These expressions include the expressions under perfect channel state information as special cases and provide good performance evaluation for the system. Numerical results show that the proposed CLD scheme with antenna selection has higher SE than the existing CLD scheme with space-time block coding, and the CLD scheme with variable switching thresholds outperforms that with conventional-fixed switching thresholds. 1. Introduction With the fast development of modern communication techniques, the demand for high data rate service is growing increasingly in the limited radio spectrum. For this reason, the future wireless communication systems will require spectrally efficient techniques to increase the system capacity. Cross-layer design (CLD), as a good work to improve the spectral efficiency (SE) and system throughput of future wireless systems while meeting the prescribed quality of service (QoS) requirements, has received much attention recently [1–3]. Especially, CLD combining adaptive modulation (AM) and automatic repeat request (ARQ) which is widely accepted as an efficient means to improve the overall performance of transmission in fading channels has been introduced in the improved 3G scheme, such as high-speed downlink packet access (HSDPA) [4–8]. Antenna selection (AS), which is a one promising approach to achieve the goal of providing performance benefits while significantly decreasing the hardware complexity and cost, has received considerable studies [9–11]. It can provide a good tradeoff between the performance, cost, and complexity and can be realized at both ends. Therefore, effective combination of cross-layer design and antenna selection techniques will receive much attention for practical purpose. The transmit antenna selection scheme with maximal ratio combining (MRC) is an effective diversity scheme [9, 10]. Based on this antenna selection scheme, the performance analysis of discrete-rate adaptive M-ray quadrature amplitude modulation
SVD-Aided Beamforming and Power Allocation Algorithm for Multiuser Turbo-BLAST System Uplink with Imperfect CSI
Xiaomin Chen,Xiangbin Yu,Dazhuan Xu
International Journal of Antennas and Propagation , 2012, DOI: 10.1155/2012/357381
Abstract: The SVD-aided joint transmitter and receiver design for the uplink of CDMA-based synchronous multiuser Turbo-BLAST systems is proposed in the presence of channel state information (CSI) imperfection. At the transmitter, the beamforming and power allocation schemes are developed to maximize the capacity of the desired user. At the receiver, a suboptimal decorrelating scheme is first proposed to mitigate the multiuser interference (MUI) and decouple the detection of different users with imperfect CSI, and then the iterative detecting algorithm that takes the channel estimation error into account is designed to cancel the coantenna interference (CAI) and enhance the bit error rate (BER) results further. Simulation results show that the proposed uplink CDMA-based multiuser Turbo-BLAST model is effective, the detection from every user is completely independent to each other after decorrelating, and the system performance can be enhanced by the proposed beamforming and power allocation schemes. Furthermore, BER performance can be enhanced by the modified iterative detection. The effect of CSI imperfection is evaluated, which is proved to be a useful tool to assess the system performance with imperfect CSI.
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