Agent—oriented Virtual Environment Modeling

Virtual environment has been widely applied in scientific research and considered as an important tool of exploring science.But constructing a real virtual environment is rather difficult.The difficulty cannot be compared with developing general software,It has a high demand for sofware technology,Obviously traditional methods are not competent for the job.Fortunately with the development of agent-oriented technologies ,all problems seem to be solved.By classifying a virtual environment into four layers corresponding with real world and considering it as a collection of agents,the virtual objects can be mapped into agents and an agent model can be designed.Based on the idea that the state change of a system is caused by that of in dividuals and the mutual effect among them,a theory of agent behavior driven by event and belief is put for ward.Such agent-oriented modeling method can cope with the demand for handling multi-dimension information.It is an effective technique for constructing a large and complex virtual environment.     

Modeling teachers’ reactions to unexpectedness

BackgroundEven experienced teachers make inconsistent classroom decisions in unexpected situations. From the cognitive load theory perspective, the effective handling of the novel, unexpected events by teachers depends on the cognitive load of the task, the teaching context in which the unexpectedness appears, and the available cognitive capacity.AimsTeachers’ reactions to unexpected mathematical events, in particular the unexpectedness of the arithmetic calculation, was modeled, investigated experimentally, and explained within the theoretical framework of cognitive load theory.Sample64 mathematics teacher trainees took part in the experiment.MethodsIn a dual-task arrangement, participants verified alternative answers to simple mathematical questions while memorizing task-irrelevant information. The answers represented low (schematic good responses), and high (unexpected good responses) processing load conditions, and control condition (incorrect responses). The memory load was low or high representing levels of extraneous load. The participants’ cognitive capacity was estimated by a complex working memory span task.ResultsThe verification of unexpected but correct answers was slow and more error-prone as compared with the processing speed and accuracy of schematic answers, presumably due to elevated processing (intrinsic) load. The increase in memory load resulted in slower and more inaccurate verifications. However, working memory capacity was found to mediate the extraneous load effect.ConclusionsThe results stress the importance of well-organized schemas for effective reactions to unexpected classroom events. Furthermore, it highlights the importance of accurately understanding and being aware of the impact of cognitive load on teachers to improve teaching practice.     

Modeling TCP performance with proxy and ARQ

INTRODUCTION The convenience of wireless communications has led to increasing use of wireless networks for civilian and critical applications. With the advent of Internet technology and the increasing popularity of wireless data devices, the wireless industry is evolv- ing its core networks toward IP-based networks. It will be necessary to integrate the wireless networks and the existing wired networks into the Internet. TCP has been the predominant transport protocol used in the wired …     

Modeling and Simulation of Photoelectronic Lambda Bipolar Transistor

Based on the region model of lambda bipolar transistor （ LBT）, a dividing region theory model of PLBT is set up.simulated and verified. Firstly, the principal operations of different kinds of photoelectronic lambda bipolar transistor ,（ PLBT） are characterized by a simple circuit model. Through mathematical analysis of the equivalent circuit, the typical characteristics curve is divided into positive resistance, peak, negative resistance and cutoff regions. Secondly. by analyzing and simulating this model, the ratio of MOSFET width to channel length, threshold voltage and common emitter gain are discovered as the main structure parameters that determine the characteristic curves of PLBT. And peak region width, peak current value, negative resistance value and valley voltage value of PLBT can be changed conveniently according to the actual demands by modifying these parameters. Finally comparisons of the characteristics of the fabricated devices and the simulation results are made, which show that the analytical results are in agreement with the observed devices characteristics.     

Students’ Understanding Is Enhanced Through Molecular Modeling

Integration of molecular modeling into General Chemistry lab encourages students to dually process molecular concepts both verbally and pictorially. When students are tested utilizing questions not previously encountered the dual processing of information can contribute to a transfer to knowledge. General Chemistry students utilized molecular modeling in lab and a comparison of a treatment and nontreatment group during two semesters is presented for a pretest, posttest, and on semester exam questions. The treatment group tested significantly higher than the nontreatment group on both the posttest and semester exam questions related to molecular concepts illustrating that there was a transfer of knowledge.     

Digital Modeling and Visualization of Hydroelectric Engineering Geoinformation

To describe the spatial tendency and complex relationship of geological structures, a digital modeling based on geographic information system and the visualization of hydroelectric engineering geology information are presented. The functions of information visual query, spatial cutting, section drawing, and coupled analysis with hydraulic structures are realized. The geologic model can match the attribute data with the shape data of geological structures, and organize the information for spatial query and analysis of the 3D model. With an application in Laxiwa hydroelectric project on the upriver of Huanghe River, the method provides a 3D parallel section view and query results of geoinformation, and 3D section views of geoinformation along axis of spillway tunnel,and along the 5th axis with underground structures, respectively.     

Modeling Strain Rate Effect for Heterogeneous Brittle Materials

Rocks are heterogeneous from the point of microstructure which is of significance to their dynamic failure behavior. Both the compressive and tensile strength of rock-like materials is regarded different from the static strength. The present study adopts smoothed particle hydrodynamics (SPH) which is a virtual particle based meshfree method to investigate strain rate effect for heterogeneous brittle materials. The SPH method is capable of simulating rock fracture, free of the mesh constraint of the traditional FEM and FDM models. A pressure dependent J-H constitutive model involving heterogeneity is employed in the numerical modeling. The results show the compressive strength increases with the increase of strain rate as well as the tensile strength, which is important to the engineering design.     

Modeling of D-STATCOM in distribution systems load flow

This paper presents modeling of Distribution STATCOM (D-STATCOM) in load flow calculations for the steady- state voltage compensation. An accurate model for D-STATCOM is derived to use in load flow calculations. The rating of this device as well as the direction of required reactive power injection for voltage compensation in the desired value (1 p.u.) is de- rived and discussed analytically and mathematically by the phasor diagram method. Furthermore, an efficient method for node and line identification used in load flow calculations is presented. The validity of the proposed model is examined by using two standard distribution systems consisting of 33 and 69 nodes, respectively. The best location of D-STATCOM for under voltage problem mitigation approach in the distribution networks is determined. The results validate the proposed model for D- STATCOM in large distribution systems.     

Modeling and Adaptive Control of a Planar Parallel Mechanism

Dynamic model and control strategy of parallel mechanism have always been a problem in robotics research. In this paper,different dynamics formulation methods are discussed first, A model of redundant driven parallel mechanism with a planar parallel manipulator is then constructed as an example. A nonlinear adaptive control method is introduced. Matrix pseudo-inversion is used to get a desired actuator torque from a desired end-effector coordinate while the feedback torque is directly calculated in the actuator space. This treatment avoids forward kinematics computation that is very difficult in a parallel mechanism. Experiments with PID together with the descibed adaptive control strategy were carried out for a planar parallel mechanism. The results show that the proposed adaptive controller outperforms conventional PID methods in tracking desired input at a high speed,     

Product Modeling Based on Knowledge Fusion in Virtual Environment

Following researches on the knowledge-based product design, product modeling based on knowledge fusion is studied in a virtual environment. Knowledge fusion is the energy sources of product innovation designs. Because a knowledge representation method is the main content of knowledge fusion, production rule way, semantic network, predicate, object-oriented and case-based representations are discussed. Using agents with object-oriented method, the knowledge can be represented as a set. The product knowledge set is divided into two subset: text knowledge and knowledge of engineering graphics that is a different form. Manipulation of the subset knowledge and fusion method is described. The paper also describes a six-tuple function in an agent data structure. A virtual environment computation model is proposed, and a practical example given.     

Modeling attention in associative learning: Two processes or one?

Certain studies of associative learning show that attention is more substantial to cues that have a history of being predictive of an outcome than to cues that are irrelevant. At the same time, other studies show that attention is more substantial to cues whose outcomes are uncertain than to cues whose outcomes are predictable. This has led to the suggestion of there being two kinds of attention in associative learning: one based upon a mechanism that allocates attention to a cue on the basis of its predictiveness, the other based upon a mechanism that allocates attention to a cue on the basis of its prediction error (e.g., Le Pelley, Quarterly Journal of Experimental Psychology, 57B, 193-243, 2004). As an alternative, it has been demonstrated that the effects of both predictiveness and uncertainty can be accounted for with only one kind of attention: one that emphasizes the role of prediction (Esber & Haselgrove, Proceedings of the Royal Society B, 278, 2553-2561, 2011). Here, we consider the alternative: whether the effects of predictiveness and uncertainty can be reconciled with a model of learning that emphasizes the role of prediction error (Pearce, Kaye, & Hall, 1982). Simulations of this model reveal that, in many cases, it too is able to account for the influence of predictiveness and uncertainty in associative learning.     

Development of Shallow Footing Anti-Ram Bollard System Through Modeling and Testing

In past terrorist attacks, vehicle borne improvised explosive devices （VBIED） have been the primary manner of attacking buildings and infrastructures. Preventing unauthorized vehicles from approaching a protected area with anti-ram systems would maintain an established standoff distance against moving and stationary vehicles and consequently reduce blast and debris threats. This strategy has been considered the first line of defence against terrorists, Several types of anti-ram devices have been developed in accordance with U.S. Department of State K-rating criteria, for example, wedge barriers, rising beams, sliding/swing gates, and drop arms. However, these devices typically need a deep foundation for installation and can＇t be implemented into many locations where a depth of excavation is limited in order to protect utility lines of buildings and infrastructures. This paper presents a recent development of a series of shallow footing anti-ram bollard systems （SFABS） that can satisfy K-12 rating with only five-inch thick footing. A high-fidelity physics based finite element technique with a vehicle crash model is used for predicting anti-ram capacity and determining design parameters of the SFABS. Full-scale vehicle crash tests of the developed SFABS systems have been carried out to validate the design and analysis.     

Development of Shallow Footing Anti-Ram Bollard System Through Modeling and Testing

In past terrorist attacks, vehicle borne improvised explosive devices (VBIED) have been the primary manner of attacking buildings and infrastructures. Preventing unauthorized vehicles from approaching a protected area with anti-ram systems would maintain an established standoff distance against moving and stationary vehicles and consequently reduce blast and debris threats. This strategy has been considered the first line of defence against terrorists. Several types of anti-ram devices have been developed in accordance with U. S. Department of State K-rating criteria, for example, wedge barriers, rising beams, sliding/swing gates, and drop arms. However, these devices typically need a deep foundation for installation and can't be implemented into many locations where a depth of excavation is limited in order to protect utility lines of buildings and infrastructures. This paper presents a recent development of a series of shallow footing anti-ram bollard systems (SFABS) that can satisfy K-12 rating with only five-inch thick footing. A high-fidelity physics based finite element technique with a vehicle crash model is used for predicting anti-ram capacity and determining design parameters of the SFABS. Full-scale vehicle crash tests of the developed SFABS systems have been carried out to validate the design and analysis.     

Analysis of Characteristic Techniques in CAD Modeling ofRapid Prototyping with SLS

Production models and parts can be obtained with a CAD model of rapid prototyping technology. Because of the characteristics of rapid prototyping with SLS (selective laser sintering), hardness and strength of the forming parts are not very high. Usually these forming parts are used for testing new products, casting complicated shape, and making various inexpensive molds and dies. In a rapid prototyping process, building a CAD model is required.     

Modeling the relationship between pre-service teachers’ TPACK and digital nativity

The purpose of this study is to build a structural equation model that predicts the relationship between Technological Pedagogical Content Knowledge (TPACK) competencies and digital nativity. The data was collected from 1493 Turkish pre-service teachers. Two instruments were used in the data collection; a TPACK-deep scale and a Turkish adaptation of the Digital Native Assessment Scale (DNAS). Structural equation modeling (SEM) was conducted to investigate the assumption that digital nativity was a predictor of TPACK competency. It was found that pre-service teachers considered themselves to have high-level ability in both digital nativity and TPACK competency. The most prominent finding of the study was that digital nativity is a significant predictor of TPACK competency. Based on the research findings, implications for practice and suggestions for future studies are also provided.     

Numerical Modeling of Response and Damage of Masonry Walls to Blast Loading

To model the damage process of masonry walls under blast loading, a dynamic continuum damage material model is constructed for brick and mortar separately. The degradation of both the stiffness and strength are governed by a damage variable. By using the proposed material model, damage and fragmentation of a typical masonry wall under blast loading at different scaled distances is calculated. The hazard level of the masonry wall to blast loading is evaluated by analyzing the numerical results.     

Modeling of mass transfer characteristics of bubble column reactor with surfactant present

INTRODUCTION mass transfer coefficient, kLa, which depends fun- damentally on the superficial gas velocity and on Bubble columns are widely used in the the physical properties of the absorption phase.chemical industry where heterogeneous gas-liquid Numerous correlations have been proposed for theor gas-solid reacti…     

Modeling of Normal Perforation of Reinforced Concrete Slabs by a Rigid Projectile

An analytical model on the normal perforation of reinforced concrete slabs is constructed. The effect of reinforcing bars is further hybridized in a general three-stage model consisting of initial cratering, tunnelling and shear plugging. Besides three dimensionless numbers, i. e., the impact function I, the geometry function of projectile N and the dimensionless thickness of concrete target X, which are employed to predict the ballistic performance of perforation of concrete slabs, the reinforcement ratio Ps of concrete and the tensile strength fs of reinforcing bars are considered as the other main factors influencing the perforation process. Simpler solutions of ballistic performances of normal perforation of reinforced concrete slabs are formulated. Theoretical predictions agree well with individual published experimental data.     

Modeling and Measuring High School Students’ Computational Thinking Practices in Science

Journal of Science Education and Technology - Despite STEM education communities recognizing the importance of integrating computational thinking (CT) into high school curricula, computation still...     

Application of BP NN and RBF NN in Modeling Activated Sludge System

Based on the operation data from a certain wastewater treatment plant(WWTP) in northeast China,the models of back propagation neural network ( BP NN ) and radial basis function neural network ( RBF NN ) have been designed respectively and the ability of convergence and generalization has been analyzed separately.As for BP NN, the effects of numbers of layers and nodes have been studied ; as for RBF NN, the influences of the number of nodes and the RBF‘s width have been studied. It is concluded that BP NN has converged much slowly in comparison with RBF NN. The conclusion that the RBF NN is suitable for modeling activated sludge system has been drawn. An automatically optimum design program for RBF NN has been developed, through which the RBF NN model of traditional activated sludge system has been established.