Reliability analysis of a two-dependent-unit parallel system with a standby unit

A parallel system with two active components and a cold standby unit is studied in this paper. The two simultaneously working components are dependent and the copula function is used to model their dependence. An explicit expression is obtained for the mean time to failure of the system in terms of the copula function and marginal lifetime distributions in two different cases As an application, numerical calculations are presented corresponding to two different copula functions and marginal lifetime distributions.     

Automaticity Theory and Its Implications for ELT in China

The paper presents an overview of automaticity research,particularly the influential theories concerned.It highlights four automatic learning models:rule-based approach,item/instance-based approach,exemplar-based random walk model,and restructuring model.Model 1 underlines that automatic processing is proceduralization of declarative knowledge with repeated practice being the prerequisite;model 2 stresses that automaticity is the direct memory retrieval and instance amount together with quality affects retrieval speed;model 3 emphasizes that memory retrieval is similarity-based,and responses are determined by the relative similarity of exemplars;the last argues that it is restructuring other than simply practice that increases the possibility of automaticity.Finally,respective implications of the learning models for ELT(English language teaching) in China are discussed.     

Hands on group work paper model for teaching DNA structure,central dogma and recombinant DNA

Understanding life on a molecular level is greatly enhanced when students are given the opportunity to visualize the molecules. Especially understanding DNA structure and function is essential for understanding key concepts of molecular biology such as DNA, central dogma and the manipulation of DNA. Researches have shown that undergraduate students typically lack a coherent view of concepts and their relationships when studying molecular biology within instruction-based lecture with no other pedagogical applications. In this study, we have designed an experimental to investigate the effect of a hands on paper models exercise within group work （Jigsaw Cooperative learning） on student biology teachers＇ academic achievement and attitudes to biotechnologies. Our goal was to develop a manipulative activity using inexpensive but graphic materials. The sample for this study consisted of 42 student teachers in the department of Biology Education during the 2005-2006 academic year. We have divided the students in two different classes. One of the classes was randomly assigned as the non-paper model （control, n=21） and the other as the paper model group （n=21）. In experimental group cut and paste paper models exercise within cooperative groups, in control group traditional instructional design has been applied in teaching DNA structure, Central Dogma and Recombinant DNA. The posttests of the groups in achievement and attitudes to biotechnologies show significant differences. The results indicated that the paper model group was more successful than the non-paper group.     

A comparative analysis of multi-output frontier models

Recently, there have been more debates on the methods of measuring efficiency. The main objective of this paper is to make a sensitivity analysis for different frontier models and compare the results obtained from the different methods of estimating multi-output frontier for a specific application. The methods include stochastic distance function frontier, stochastic ray frontier, and data envelopment analysis. The stochastic frontier regressions with and without the inefficiency effects model are also compared and tested. The results indicate that there are significant correlations between the results obtained from the alternative estimation methods.     

A Lesson Plan of Writing an Argument for Applied Essay Writing in Vo cational Education

This paper sets forth a tentative model of lesson planning for the writing module at the vocational education level,with argumentative essay writing as an illustration.First,it presents a summary account of the context where the course structure and learner needs are addressed.It,then,provides an overview of the lesson plan in terms of classroom processes,strategies and purposes.Finally,the paper proceeds to the theoretical and empirical justification of the lesson plan through recourse to earlier research findings.The model is intended to be implicational for writing teachers to prepare each lesson as an indispensable pre-instructional process.     

Preliminary Study of Jerome Model and Horace Model

Translation always plays the crucial role in the cross-culture communication and the development of human being’s history of civilization. The author of this papertries to make an analysis and contrast of the two translation models: the Jerome model and the Horace model, pointing out that it is because of different circumstances that different translation models are used in the translation.     

Computer simulation of active suspension based on the full-vehicle model

The current method to solve the problem of active suspension control for a vehicle is often dealt with a quarter-car or half-car model.But it is not enough to use this kind of model for practical applications.In this paper,based on considering the influence of factors such as,seat and passengers a MDOF(multi-degree-of-freedom)model describing the vehicle motion is set up.The MODF model,which is 8DOF of four independent suspensions and four wheel tracks,is more applicable by comparison of its analysis result with some conventional vehicle models.Therefore,it is more suitable to use the 8DOF full-car model than a conventional 4DOF half-car model in the active control design for car vibration.Based on the derived 8DOF odel,a controller is designed by using LQ(linear quadratic)control theory,and the appropriate control scheme is selected by testing various performance indexes.Computer simulation 8is carried out for a passenger car running on a road with step disturbance and random road disturbance expressed by Power Spectral Density(PSD).Vibrations corresponding to ride comfort are derived under the foregoing road disturbances.The response results for uncontrolled and controlled system are compared.The response of vehicle vibration is greatly suppressed and quickly damped.which testifies the effect of the active suspenson.The results achieved for various controllers are compared to invesigate the influence of different control schemes on the control effect.     

Performance analysis of IEEE 802.11 DCF networks

This paper presents an analytical saturation throughput model of IEEE 802.11DCF （distributed coordination function） with basic access in ad hoc mode. The model takes into account freezing of the backofftimer when a station senses busy channel. It is shown that taking into account this feature of DCF is important in modeling saturation throughput by yielding more accurate and realistic results than models known from literature. The proposed analytical model also takes into account the effect of transmission errors. All essential features of the proposed analytical approach are illustrated with numerical results. The presen- tation of the model is proceeded by an overview of approaches to IEEE 802.11 network performance evaluation presented in the literature.     

Modular approach for ethics

It is hard to define a single set of ethics that will cover an entire computer users community. In this paper, the issue is addressed in reference to code of ethics implemented by various professionals, institutes and organizations. The paper presents a higher level model using hierarchical approach. The code developed using this approach could be adopted easily by the entire community of computer users working in different environments. The hierarchical approach allows refinement and customization of code at lower levels to address the needs of diverse sub groups of users. It also provides comfort of flexibility as well as the potential for evolution. The work reported here is in continuation of the research reported in an earlier paper （Wyne,2009）.     

Tracking multiple people under occlusion and across cameras using probabilistic models

Tracking multiple people under occlusion and across cameras is a challenging question for discussion. Furthermore, the cameras in this study are used to extend the field of view, which are distinguished from the same field of view. Such corre-spondence between multiple cameras is a burgeoning research subject in the area of computer vision. This paper effectively solves the problems of tracking multiple people who pass from one camera to another and segmenting people under occlusion using probabilistic models. The probabilistic models are composed ofblob model, motion model and color model, which make the most of the space, motion and color information. First, we present a color model that uses maximum likelihood estimation based on non-parametric kernel density estimation. Second, we introduce a blob model based on mean shift, which segments the body into many regions according to the color of each person in order to spatially localize the color features corresponding to the way people are dressed. Clothes can be any mixture of colors. Third, we bring forward a motion model based on statistical probability which indicates the movement position of the same person between two successive frames in a single camera. Finally, we effectively unify the three models into a general probabilistic model and attain a maximization likelihood probability image, which is used to segment the foreground region under occlusion and to match people across multiple cameras.     

A Generation Pricing Method with Capacity Bidding

Due to historic reasons China encounters some special difficulties in ESI(electricity system industry) restructureing,An easy and simple electricity value equivalent(es-EVE) method for day-ahead pool purchase pricing of China is therefore presented in this paper.The es-EVE method is different from two-part and one-part tariffs.It is more like the UK‘s method in form,but revised for China with some new concepts and procedure.The main contributions of it include:(1) Find two kinds of eigenvalue,namely EVEs,in an optimization model.(2) Define new concepts of virtual units units and feasible region,(3) Twice merit orderings are employed successively to find marginal price.They are simple maximum and minimum comparison procedures and so on.The special economic significance of the method for China is discussed.and some suggestion for ESI Restructuring based on es-EVE method are provided.A case study is offered at the end of the paper.     

Fuzzy finish time modeling for project scheduling

This research aims at developing a new fuzzy activity finish time estimation model for project scheduling management.With the application of the fuzzy quality function deployment （FQFD） and fuzzy analytic hierarchy process （FAHP） methods,the degree of fuzziness for every project activity is calculated in accordance with considerations of project uncertainties.These uncertainties are measured by the risk level of such project-related characteristics as time limit,activity start time,budget,manpower,technological difficulty,and facility requirements.In this paper,rather than applying the de-fuzzification technique to obtain the crisp activity duration for project scheduling,the fuzzy finish time estimation method for every activity is proposed based on the degree of fuzziness.The corresponding fuzzy activity duration time plot is also developed in a new fuzzy Gantt chart.The proposed model can provide a reasonable fuzzy finish time estimation for every activity,while most scheduling methods only provide the finish time of the entire project.Compared to existing models,this time estimation model and its corresponding Gantt chart are predicted to have higher reliability and practical application in project management and scheduling.     

Saturation throughput analysis of RTS/CTS scheme in an error-prone WLAN channel

In this paper, a new three-dimensional Markov model is proposed for the estimation of saturation throughput of RTS/CTS （request to send/clear to send） scheme in an error-prone wireless local area network （WLAN） channel. The model takes account of the effect of bit error on all the frames, and station short and long retry limits. Saturation throughput was re-analyzed using the new Markov model and numerical results closely matched those from simulation, confirming the accuracy of the new model. Evaluation of the influence of different parameters on throughput showed that the saturation throughput is sensitive to channel bit error rates and packet length, especially in high bit error conditions.     

Modeling and robustness of knowledge network in supply chain

The growth and evolution of the knowledge network in supply chain can be characterized by dynamic growth clustering and non-homogeneous degree distribution.The networks with the above characteristics are also known as scale-free networks.In this paper,the knowledge network model in supply chain is established,in which the preferential attachment mechanism based on the node strength is adopted to simulate the growth and evolution of the network.The nodes in the network have a certain preference in the choice of a knowledge partner.On the basis of the network model,the robustness of the three network models based on different preferential attachment strategies is investigated.The robustness is also referred to as tolerances when the nodes are subjected to random destruction and malicious damage.The simulation results of this study show that the improved network has higher connectivity and stability.     

Mathematically modeling fixed-bed adsorption in aqueous systems

Adsorption is one of the widely used processes in the chemical industry environmental application.As compared to mathematical models proposed to describe batch adsorption in terms of isotherm and kinetic behavior,insufficient models are available to describe and predict fixed-bed or column adsorption,though the latter one is the main option in practical application.The present review first provides a brief summary on basic concepts and mathematic models to describe the mass transfer and isotherm behavior of batch adsorption,which dominate the column adsorption behavior in nature.Afterwards,the widely used models developed to predict the breakthrough curve,i.e.,the general rate models,linear driving force(LDF) model,wave propagation theory model,constant pattern model,Clark model,Thomas model,Bohart-Adams model,Yoon-Nelson model,Wang model,Wolborska model,and modified dose-response model,are briefly introduced from the mechanism and mathematical viewpoint.Their basic characteristics,including the advantages and inherit shortcomings,are also discussed.This review could help those interested in column adsorption to reasonably choose or develop an accurate and convenient model for their study and practical application.     

A BOD-DO coupling model for water quality simulation by artificial neural network

A one-dimensional BOD-DO coupling model for water quality simulation is presented,which adopts Streeter-Phelps equations and the theory of back-propagation artificial neural network.The water quality data of Yangtze River in the Chongqing region in the year of 1989 are divided into 5 groups and used in the learning and testing courses of this model.The result shows that such model is feasible for water quality simulation and is more accurate than traditional models.     

Integrated statistical and engineering process control based on smooth transition autoregressive model

Traditional studies on integrated statistical process control and engineering process control (SPC-EPC) are based on linear autoregressive integrated moving average (ARIMA) time series models to describe the dynamic noise of the system.However,linear models sometimes are unable to model complex nonlinear autocorrelation.To solve this problem,this paper presents an integrated SPC-EPC method based on smooth transition autoregressive (STAR) time series model,and builds a minimum mean squared error (MMSE) controller as well as an integrated SPC-EPC control system.The performance of this method for checking the trend and sustained shift is analyzed.The simulation results indicate that this integrated SPC-EPC control method based on STAR model is effective in controlling complex nonlinear systems.     

Web应用系统的统一结构模型

With the increasing popularity,scale and complexity of web applications,design and development of web applications are becoming more and more difficult,However,the current state of their design and development is characterized by anarchy and ad hoc methodologies,One of the causes of this chaotic situation is that different researchers and designers have different understanding of web applications.In this paper,based on an explicit understanding of web applications,we present a unified architecture model of wed applications,the four-view model,which addresses the analysis and design issues of web applications from four perspectives,namely,logical view,data view,navigation view and presentation view,each addrssing a specific set of concerns of web applications,the purpose of the model is to provide a clear picture of web applications to alleviate the chaotic situation and facilitate its analysis,design and implementation.