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Search Results: 1 - 10 of 55075 matches for " Wei Lai "
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Historical Materialism and Liu Dunzhen’s Ancient Chinese Architecture History  [PDF]
Wei Li, Lanlan Lai
Advances in Historical Studies (AHS) , 2017, DOI: 10.4236/ahs.2017.64011
Abstract: After the founding of new China, Marxist Historical Materialism has achieved dominant position in China. Although it had been the dogmatism tendency of “simplification”, “formulation” and “politicization”, Chinese Historical Materialism research reached a new height and state in the 1950-1960s. Liu Dun-zhen’s works—Ancient Chinese Architecture History, which has been inoculation, mature and birth of in a turbulent of historical background, inevitably, the historical materialism and its core ideology have had a complex and profound influence on it. From the angle of text study, this article tries to show how deep the academic penetrability in Ancient Chinese Architecture History on the specific historical environment of that time and the great contribution of narrative paradigm and academic discourse system.
Study on Comprehensive Evaluation Model of Commercial Housing Price-Rationalization  [PDF]
Yifei Lai, Yuanxin Wei, Haiyun Luo
Journal of Service Science and Management (JSSM) , 2010, DOI: 10.4236/jssm.2010.33043
Abstract: In recent years, the prices of city commercial housing are soaring, causing wide attention of public and fierce discussion about whether it is reasonable for the housing prices in China. This paper attempts to establish a method to measure housing price-rationalization. Firstly, the paper establishes rationalization evaluation system of housing price from commercial housing price formation, residents’ endurance and coordination parity system. Then it selects an appropriate standard ways to build affordable housing product evaluation criteria.
Test for Homogeneity of Odds Ratios Using U-Statistics  [PDF]
Qi Wei, Dejian Lai
Open Journal of Statistics (OJS) , 2019, DOI: 10.4236/ojs.2019.93024
Abstract: There are a few statistics testing the homogeneity of odds ratios across strata. Asymptotic statistics lose their power in the “sparse-data” setting. Both asymptotic statistics and exact tests have low power when the sample sizes are small. We created a set of U statistics and compared them with some existing statistics in testing homogeneity of OR at different data settings. We evaluated their performance in terms of the empirical size and power via Monto Carlo simulations. Our results showed that two of the U-statistics under our study had higher power for testing homogeneity of odds ratios for 2 by 2 contingency tables. The application of the tests was illustrated in two real examples.
Clustering Student Discussion Messages on Online Forumby Visualization and Non-Negative Matrix Factorization  [PDF]
Xiaodi Huang, Jianhua Zhao, Jeff Ash, Wei Lai
Journal of Software Engineering and Applications (JSEA) , 2013, DOI: 10.4236/jsea.2013.67B002
Abstract:

The use of online discussion forum can effectively engage students in their studies. As the number of messages posted on the forum is increasing, it is more difficult for instructors to read and respond to them in a prompt way. In this paper, we apply non-negative matrix factorization and visualization to clustering message data, in order to provide a summary view of messages that disclose their deep semantic relationships. In particular, the NMF is able to find the underlying issues hidden in the messages about which most of the students are concerned. Visualization is employed to estimate the initial number of clusters, showing the relation communities. The experiments and comparison on a real dataset have been reported to demonstrate the effectiveness of the approaches.

Oscillating Water Surface Measurement of Free Overfall with a Plunge Pool  [PDF]
Shun Chung Tsung, Jihn Sung Lai, Hau Wei Wang
Journal of Flow Control, Measurement & Visualization (JFCMV) , 2015, DOI: 10.4236/jfcmv.2015.33009
Abstract: This study presents a laser-sheet imaging technique to measure the water surface of free overfalls with plunge pool. Varying the plunge pool length of a constant approach discharge created skimming, periodic oscillatory, and nappe flows. This study analyzes the resulting oscillating water surfaces and temporal variations of water stages at particular positions in the periodic oscillatory flow condition. The oscillation period and amplitude of temporal water stage variation were determined by directly measuring the time interval and water stage differences in water stage variations, respectively. The plunge pool length and air pocket characteristics seriously affected the periodic oscillatory flow. The oscillation period increased as the plunge pool length increased. On the other hand, the water stage amplitude decreased sharply when the plunge pool exceeded a specific length. The absence of an air pocket beneath the falling nappe significantly increased the oscillation period and decreased the water stage amplitude. This study investigates water surface oscillation in the plunge pool and the upstream side of the drop. However, the mean end depth of a periodic oscillatory flow with an air pocket is also applicable to discharge estimation using the end depth method.
Analysis of Nitrogen Dioxide in Environment  [PDF]
Jun Wang, Wei Zhang, Rui Cao, Xiangyu You, Hong Lai
Advances in Bioscience and Biotechnology (ABB) , 2016, DOI: 10.4236/abb.2016.76026
Abstract: As a severe environmental pollutant, detection and quantitation of nitrogen dioxide (NO2) have been studied for centuries. In this review, recent progress of NO2 analysis in the atmosphere will be summarized. Four major types of detection technologies, including traditional chemical detection, optical detection, solid-state field effect transistor detection, and other detection technology are covered. The standard method employed by the US EPA, which is based on luminol, is the most reliable and robust method that is used for fully validated monitoring. In the past two decades, accompanying the fast development of electrical engineering and integrated circuit, micro to nanoscale gas sensors have been gaining more and more attention. Application of novel materials including nano wires and graphene also leads to a new era of research and development of sensors.
Effect of Applied Potential on the Formation of Self-Organized Nanotube Arrays and Its Photoelectrochemical Response
Chin Wei Lai,Srimala Sreekantan
Journal of Nanomaterials , 2011, DOI: 10.1155/2011/142463
Abstract: Self-organized TiO2 nanotube arrays have been fabricated by anodization of Ti foil in an electrochemical bath consisting of 1?M of glycerol with 0.5?wt% of NH4F. The effects of applied potential on the resulting nanotubes were illustrated. Among all of the applied potentials, 30?V resulted in the highest uniformity and aspect ratio TiO2 nanotube arrays with the tube's length approximately 1? m and pore's size of 85?nm. TiO2 nanotube arrays were amorphous in as-anodized condition. The anatase phase was observed after annealing at 400 in air atmosphere. The effect of crystallization and effective surface area of TiO2 nanotube arrays in connection with the photoelectrochemical response was reported. Photoelectrochemical response under illumination was enhanced by using the annealed TiO2 nanotube arrays which have larger effective surface area to promote more photoinduced electrons. 1. Introduction Since titanium oxide (TiO2) is a commercial product in the early twentieth century, it is believed to be the most promising photocatalyst, due to its great capacity for oxidation, wide band gap, nontoxicity, low-cost, widespread availability, and long term stability [1–5]. Due to its wide range of functions, TiO2 photocatalyst can be applied to the field of environmental cleanup including deodorization, antibacterial protection, antifouling protection, water treatment, emission gas treatment, dye-sensitized solar cells, hydrogen generation by water photoelectrolysis, gas sensors, and so on [4–8]. These applications can be roughly divided into “environmental” and “energy” categories. In this context, simple anodization method has caught the attention of the scientific community because vertically oriented and highly ordered TiO2 nanotube arrays can be produced via this method [2, 9–12]. Heterogeneous photocatalysis is a well-known process in which a combination of photochemistry and catalysis are operating together [5, 13]. It implies that both light and catalyst are necessary to bring out the chemical reaction. Upon absorption of photons with energy larger than the band gap of TiO2, electrons are excited from the valence band to the conduction band, creating electron-hole pairs [4, 13–15]. The valence band holes are powerful oxidants (+1 to +3.5?V versus NHE depending on the semiconductor and pH), while the conduction band electrons are good reductants (+0.5 to ?1.5?V versus NHE). During photocatalytic hydrogen production, an essential photogeneration of electron-hole pairs is required. When photocatalysis is applied to perform water splitting process for
Photoelectrochemical Performance of Smooth TiO2 Nanotube Arrays: Effect of Anodization Temperature and Cleaning Methods
Chin Wei Lai,Srimala Sreekantan
International Journal of Photoenergy , 2012, DOI: 10.1155/2012/356943
Abstract: The formation of self-organized titanium dioxide (TiO2) nanotube arrays without bundling or clustering is essential for their high efficiency in photoelectrochemical (PEC) application. The present paper reports on the use of different temperatures to control the specific architecture of nanotube arrays and effective cleaning techniques to ensure the formation of clean TiO2 nanotube surface. The wall thickness of nanotube arrays could be controlled from 12.5 nm to 37.5 nm through different anodization temperature ranging from 10°C to 80°C. Furthermore, ultrasonic cleaning combined with acetone showed the high-ordered TiO2 nanotube arrays without morphological disorder, bundling, and microcrack problems. Based on the results obtained, a higher PEC response of 1 mA/cm2 and a photoconversion efficiency of 1.3% could be achieved using a wall thickness of 12.5 nm and defect-free TiO2 nanotube arrays for low charge transfer resistance.
Single Step Formation of C-TiO2 Nanotubes: Influence of Applied Voltage and Their Photocatalytic Activity under Solar Illumination
Chin Wei Lai,Srimala Sreekantan
International Journal of Photoenergy , 2013, DOI: 10.1155/2013/276504
Abstract: Self-aligned and high-uniformity carbon (C)- titania (TiO2) nanotube arrays were successfully formed via single step anodization of titanium (Ti) foil at 30?V for 1?h in a bath composed of ethylene glycol (EG), ammonium fluoride (NH4F), and hydrogen peroxide (H2O2). It was well established that applied voltage played an important role in controlling field-assisted oxidation and field-assisted dissolution during electrochemical anodization process. Therefore, the influences of applied voltage on the formation of C-TiO2 nanotube arrays were discussed. It was found that a minimal applied voltage of 30?V was required to form the self-aligned and high-uniformity C-TiO2 nanotube arrays with diameter of ~75?nm and length of ~2?μm. The samples synthesized using different applied voltages were then subjected to heat treatment for the conversion of amorphous phase to crystalline phase. The photocatalytic activity evaluation of C-TiO2 samples was made under degradation of organic dye (methyl orange (MO) solution). The results revealed that controlled nanoarchitecture C-TiO2 photocatalyst led to a significant enhancement in photocatalytic activity due to the creation of more specific active surface areas for incident photons absorption from the solar illumination. 1. Introduction Nowadays, various kinds of environmental contaminants are around all of us, especially organic and inorganic pollutants from industrial wastewaters [1–3]. Thus, the treatments of such wastewater have become a major concern and it is urgent to develop a sustainable and cost-effective treatment technology to solve global environmental problems [3, 4]. In recent years, the photocatalyst system has attracted much attention from science community as one of the most promising ways to solve the environmental problems [4–6]. This system is considered to be an ideal and green environmental solution for our green economy future. In this case, TiO2 based nanomaterials have been broadly studied as the most promising photocatalyst for environmental remediation such as air purification, water purification, heavy metals degradation, and hazardous waste remediation [6–10]. The reasons are mainly attributed to the nontoxicity, cost-effectiveness, long-term stability, widespread availability, and high stability against photocorrosion with great capacity for oxidation and high photocatalytic property. To date, development of nanoarchitecture of TiO2 assemblies with precisely controllable nanoscale features has gained significant scientific interest [11, 12]. Among different nanoarchitectures of TiO2,
Research on User Permission Isolation for Multi-Users Service-Oriented Program  [PDF]
Li Yu, Jiang Wei, Lin Li, Zhan Jing, Liang Peng, Yingxu Lai, Shupo Bu
Int'l J. of Communications, Network and System Sciences (IJCNS) , 2012, DOI: 10.4236/ijcns.2012.52014
Abstract: For the super user privilege control problem in system services, a user permission isolation method is proposed. Based on virtualization technology, the permission limited environments are constructed for different users. According to privilege sets, the users, mapping relations are built among users, isolated domains and program modules. Besides, we give an algorithm for division of program permissions based on Concept Lattices. And the security strategies are designed for different isolated domains. Finally, we propose the implications of least privilege, and prove that the method eliminates the potential privileged users in system services.
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