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Search Results: 1 - 10 of 25662 matches for " Zhenmin Cheng "
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Carboxylation of Aromatics by CO2 under “Si/Al Based Frustrated Lewis Pairs” Catalytic System  [PDF]
Miaofei Gu, Zhenmin Cheng
Journal of Materials Science and Chemical Engineering (MSCE) , 2015, DOI: 10.4236/msce.2015.31015
Abstract:

Carboxylation of aromatics by CO2 to generate corresponding carboxylic acids is recently providing a novel approach to utilize the green gas CO2, in which the activation of CO2 is the key procedure. Among the many catalytic systems employed in the carboxylation, the concept of “Frustrated Lewis Pairs” (FLPs) was scarcely mentioned, which perform excellently in activating small molecules like CO2. The FLPs are combinations of Lewis acids and Lewis bases which failed to form adducts due to their bulky steric congestion. In this paper, we first attempted various Si/Al Based FLPs to catalyze the carboxylation of aromatics through the activation of CO2, and a good yield of 62% - 97% was obtained. The reaction mechanism was proposed, involving the activation of CO2 mainly contributed by AlCl3 in cooperation with organosilane, forming an intermediate consisting of CO2, AlCl3, and R4Si, as well as the subsequent electrophilic attack to aromatics, thus to promote the carboxylation reaction.

Absorption Enhanced Methanol Synthesis in a Trickle Bed Reactor over Cu/Zn/Al2O3 Catalyst  [PDF]
Peng Liu, Zhenmin Cheng
Journal of Materials Science and Chemical Engineering (MSCE) , 2015, DOI: 10.4236/msce.2015.36005
Abstract:

Methanol synthesis in a trickle bed reactor with tetraethylene glycol dimethyl ether (TEGDME) as the liquid phase over a Cu/Zn/Al2O3 catalyst was investigated. The pressure was kept constant at 5.0 MPa, while the temperature ranged from 230℃?to 260℃?and the mass space velocity varied between 294 L·Kg-1·h-1 and 1655 L·Kg-1·h-1. The effects of temperature and space velocity on CO conversion and methanol productivity were studied. Methanol synthesis processes in trickle bed with the TEGDME and paraffin oil as liquid phase were compared with the fixed bed process. The results indicated that the optimal temperature was approximately 240. When the space velocity was increased, the CO conversion decreased while the methanol productivity increased. The liquid introduced can help to keep the reactor nearly isothermal. For methanol synthesis in trickle-bed reactor, TEGDME was better than paraffin oil. Effect of TEGDME on the reaction was twofold. On one hand, it absorbs the methanol and speeds up the reaction. On the other hand, it also increases the mass transfer resistance and hinders the reaction.

Mapping Toll-Like Receptor Signaling Pathway Genes of Zhikong Scallop(Chlamys farreri) with FISH Mapping Toll-Like Receptor Signaling Pathway Genes of Zhikong Scallop(Chlamys farreri) with FISH
ZHAO Bosong,ZHAO Liang,LIAO Huan,CHENG Jie,LIAN Shanshan,LI Xuan,HUANG Xiaoting,BAO Zhenmin
- , 2015,
Abstract: Toll-like receptor(TLR) signaling pathway plays a pivotal role in the innate immune system. Studies on TLR signaling pathway genes in Zhikong scallop(Chlamys farreri) have mainly focused on sequence analysis and expression profiling, no research has been carried out on their localization. The chromosomal position of TLR signaling pathway genes can be valuable for assemblying scallop genome and analysizing gene regulatory networks. In the present study, five key TLR signaling pathway genes(Cf TLR, Cf Myd88, Cf TRAF6, Cf NFκB, and Cf IκB) containing bacterial artificial chromosomes(BACs) were isolated and physically mapped through fluorescence in situ hybridization on five non-homologous chromosome pairs, showing a similar distribution to another five model species. The isolation and mapping of these key immune genes of C. farreri will aid to the research on innate immunity, assignment of interested genes to chromosomes, and integration of physical, linkage and cytogenetic maps of this species
A Modified Resource Distribution Fairness Measure
Zhenmin Chen
Journal of Mathematics , 2013, DOI: 10.1155/2013/956039
Abstract: An important issue of resource distribution is the fairness of the distribution. For example, computer network management wishes to distribute network resource fairly to its users. To describe the fairness of the resource distribution, a quantitative fairness score function was proposed in 1984 by Jain et al. The purpose of this paper is to propose a modified network sharing fairness function so that the users can be treated differently according to their priority levels. The mathematical properties are discussed. The proposed fairness score function keeps all the nice properties of and provides better performance when the network users have different priority levels. 1. Introduction When a fixed number of users or receivers share limited amount of resource, the fairness of the distribution is always an important issue. The resource distribution can be of any kind such as social benefit resource distribution, manpower distribution, and computer network resource distribution. Suppose users share a certain amount of resource. Let be the amounts of resource the users receive, respectively. Suppose all users have the same right to share the entire resource. Then the difference among the values should not be too large. If the difference among values is too large, then it can be claimed that the distribution of the entire resource is unfair. Here certain rules have to be made to determine if the resource distribution is fair or unfair. To solve such a problem, there are two important steps. The first step is to find an appropriate quantitative measure, which is a function of , such that the quantitative measure can be used to describe the fairness of the resource distribution. The quantitative measure should increase when the resource distribution becomes fairer. On the other hand, it should decrease when the resource distribution becomes more and more unfair. The second step is to determine when one can conclude that the resource distribution is significantly unfair. The concept of statistical test can be adopted for this purpose. For a certain level of significance, one may conclude that the resource distribution is significantly unfair when the quantitative measure falls below some value. Such a value is called a critical value in statistical analysis. This paper focuses on modifying a commonly used fairness measure so that the modified fairness measure can better fit the real world applications. In the past several decades, many research papers have been published in this area in the literature. Jain et al. [1] proposed a quantitative measure to assess
Interval and Point Estimators for the Location Parameter of the Three-Parameter Lognormal Distribution
Zhenmin Chen,Feng Miao
International Journal of Quality, Statistics, and Reliability , 2012, DOI: 10.1155/2012/897106
Abstract: The three-parameter lognormal distribution is the extension of the two-parameter lognormal distribution to meet the need of the biological, sociological, and other fields. Numerous research papers have been published for the parameter estimation problems for the lognormal distributions. The inclusion of the location parameter brings in some technical difficulties for the parameter estimation problems, especially for the interval estimation. This paper proposes a method for constructing exact confidence intervals and exact upper confidence limits for the location parameter of the three-parameter lognormal distribution. The point estimation problem is discussed as well. The performance of the point estimator is compared with the maximum likelihood estimator, which is widely used in practice. Simulation result shows that the proposed method is less biased in estimating the location parameter. The large sample size case is discussed in the paper.
A Visibility-based Algorithm for Multi-robot Boundary Coverage
Linan Jiao,Zhenmin Tang
International Journal of Advanced Robotic Systems , 2008,
Abstract: Cell decomposition is often used in autonomous area coverage. We propose a visibility-based decomposition algorithm for single robot boundary coverage and a corresponding multi-robot algorithm in unknown environment. A graph data structure is exploited for completeness of coverage and incremental description of partially observed world. Visibility-based decomposition facilitates the construction of graph and algorithms operated on it. In the context of multi-robot, a dynamically selected highest priority robot is in charge of information share and synchrony through communication, polygon set operations provide tools for environmental information mergence, a distributed algorithm for multi-robot boundary coverage is proposed based on those technologies. Finally the experimental results show the relationships between robot number and traversable gate number, some future subjects of researches are introduced.
Interval and Point Estimators for the Location Parameter of the Three-Parameter Lognormal Distribution
Zhenmin Chen,Feng Miao
Journal of Quality and Reliability Engineering , 2012, DOI: 10.1155/2012/897106
Abstract: The three-parameter lognormal distribution is the extension of the two-parameter lognormal distribution to meet the need of the biological, sociological, and other fields. Numerous research papers have been published for the parameter estimation problems for the lognormal distributions. The inclusion of the location parameter brings in some technical difficulties for the parameter estimation problems, especially for the interval estimation. This paper proposes a method for constructing exact confidence intervals and exact upper confidence limits for the location parameter of the three-parameter lognormal distribution. The point estimation problem is discussed as well. The performance of the point estimator is compared with the maximum likelihood estimator, which is widely used in practice. Simulation result shows that the proposed method is less biased in estimating the location parameter. The large sample size case is discussed in the paper. 1. Introduction The two-parameter lognormal distribution and the three-parameter lognormal distribution have been used in many areas such as reliability, economics, ecology, biology, and atmospheric sciences. In the past twenty years, many research papers have been published on the parameter estimation problems for the lognormal distributions. See, for example, Kanefuji and Iwase [1], Sweet [2], and Crow and Shimizu [3]. The three-parameter lognormal distribution is the extension of the two-parameter lognormal distribution to meet the need of the biological and sociological science, and other fields. Some papers can be found in the literature for the parameter estimation problems for this distribution. See, for example, Komori and Hirose [4], Singh et al. [5], Eastham et al. [6], Cohen et al. [7], Chieppa and Amato [8], Griffiths [9], and Cohen and Whitten [10]. Chen [11] analyzed an application data set containing 49 plastic laminate strength measurements using the locally maximum likelihood estimation method. When the locally maximum likelihood estimation method is used, people are not using the criterion of searching the value of the parameter, which is being estimated, such that the likelihood function is maximized. This is particularly true when the location parameter of the three-parameter lognormal distribution is estimated. This is because the likelihood function goes to infinity when the value of the location parameter approaches to the smallest order statistic. The point estimation will be discussed in Section 3. The same data set is analyzed using the method presented in this paper. It should be noted
Statistical Test for Bivariate Uniformity
Zhenmin Chen,Tieyong Hu
Advances in Statistics , 2014, DOI: 10.1155/2014/740831
Abstract: The purpose of the multidimension uniformity test is to check whether the underlying probability distribution of a multidimensional population differs from the multidimensional uniform distribution. The multidimensional uniformity test has applications in various fields such as biology, astronomy, and computer science. Such a test, however, has received less attention in the literature compared with the univariate case. A new test statistic for checking multidimensional uniformity is proposed in this paper. Some important properties of the proposed test statistic are discussed. As a special case, the bivariate statistic test is discussed in detail in this paper. The Monte Carlo simulation is used to compare the power of the newly proposed test with the distance-to-boundary test, which is a recently published statistical test for multidimensional uniformity. It has been shown that the test proposed in this paper is more powerful than the distance-to-boundary test in some cases. 1. Introduction Testing uniformity in the univariate case has been studied by many researchers, whereas the multidimensional uniformity test seems to have received less attention in the literature. Testing whether a pattern of points in the multidimensional space is distributed uniformly has applications in many fields such as biology, astronomy, and computer science. A commonly used goodness-of-fit test for uniformity is the chi-square test [1]. Theoretically, the chi-square test can be applied for any multivariate distribution test. However, the problem for the chi-square test is the arbitrariness of cell limits determination. Another problem for the chi-square test is that the power of the chi-square test is usually low. Some other well-known methods for univariate goodness-of-fit tests are the Kolmogorov-Smirnov test [2, 3], Anderson-Darling test [4], and the Cramer-von Mises test [5]. Justel et al. [6] proposed a multivariate goodness-of-fit test based on the idea of the Kolmogorov-Smirnov test. By using the Rosenblatt’s transformation, they reduced the multivariate case to univariate case. The test statistic they used has distribution free property and can be applied to any dimensional case. The problem for that method is that the computation of test statistic is complicated especially for over two dimensions. Liang et al. [7] proposed several statistical tests for testing uniformity in multivariate case. Those tests used the number-theoretic and quasi-Monte Carlo method for measuring the discrepancy of the points in multidimensional unit. Berrendero et al. [8] proposed a
Zircon U-Pb ages, geochemistry and its petrogenesis of Jurassic granites in northeastern part of the Da Hinggan Mts.
大兴安岭东北部侏罗纪花岗质岩石的锆石U-Pb年龄、地球化学特征及成因

SUI ZhenMin,GE WenChun,WU FuYuan,ZHANG JiHeng,XU XueChun,CHENG RuiYu,
隋振民
,葛文春,吴福元,张吉衡,徐学纯,程瑞玉

岩石学报 , 2007,
Abstract: Abstract The U-Pb dating results determined by LA-ICPMS show that quite a large of Jurassic granites were still distributed inside the Proterozoic , Early and Late Paleozoic granite, which were recognized and categorized by predecessors. The intrusion sequence of Jurassic granite in the studied area could be classified into two stages, i.e. early and late stages on the basis of event occurring time, whose U-Pb dating in zircon are 188 ~ 190Ma and 171~181Ma, respectively. The dating data of Jurassic granite are fully comparable to those of Jurassic granite existing in the other part of Northeast China. Geochemically, these granitics could be distinguished by two types-low-Sr and high-Yb granitics and high-Sr and low-Yb granitics, they possess the same or similar source rock compositions but originated at different depth. The early intruded granitics, characterized by the low-Sr and high Yb, originated at the low pressure in the mid crust, however, the late intruded ones, characterized by high Sr and Law Yb, similarly to C-type adakites and it originated at the relatively high pressure in lower part of the crust. Characteristics of zircon Hf isotope indicated that the source materials of Jurassic granitics came from newly accreted crustal materials and their mixture in the Neoproterozoic and phanerozoic. The Jurassic granitics in the studied area are dominantly composed of granodiorite and adamellite, which belong to aluminum saturated or oversaturated, high potassium calc-alkaline series-the granite in type I, with similar feature of the granite associations at the active continental margin. It is a part of stripped or belted Jurassic granitics in Northeast China distributed alone NNE direction, its origin might be related to the subduction of paleo-Pacific tectonic plate.
Zircon U-Pb ages, Hf isotopic characteristics and their implications of the Early Paleozoic granites in the northeastern Da Hinggan Mts. , northeastern China
大兴安岭东北部早古生代花岗岩锆石U-Pb年龄、Hf同位素特征及地质意义

GE WenChun,SUI ZhenMin,WU FuYuan,ZHANG JiHeng,XU XueChun,CHENG RuiYu,
葛文春
,隋振民,吴福元,张吉衡,徐学纯,程瑞玉

岩石学报 , 2007,
Abstract: 大兴安岭东北部早古生代花岗岩属于Ⅰ型花岗岩。锆石的LA-ICPMS U-Pb年代学研究表明,十八站岩体、内河岩体、白银纳岩体的形成年龄分别为499±1、500±1和460±1Ma,而查拉班河岩体为一多次侵入的杂岩体,其形成年龄在465~481Ma。结合本区和邻区其它早古生代花岗岩体的锆石U-Pb年龄,限定了大兴安岭东北部地区早古生代花岗岩浆活动的时限为460~500Ma。锆石的LA-MC-ICPMS Hf同位素研究显示,本区早古生代花岗岩的锆石ε_(Hf)(t)多数介于 1.5~ 3.8之间,二阶段模式年龄介于1.1~1.4Ga,表明其主要起源于中-新元古代增生的地壳物质。结合兴安地块其它花岗岩的锆石Hf同位素资料,认为额尔古纳地块在中-新元古代时期曾发生一次重要的地壳增生事件,与兴安地块主要为显生宙地壳的特点明显不同。
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