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INTRODUCTION Chaos is based on the principle that simpledeterministic laws can exhibit complex externalbehavior (Hegger and Kantz, 2000); although it isquite difficult to reveal such simple laws from thesystem’s external behavior only. This is mainly dueto the dissipation and sensitivity to initial condi-tions (SIC) properties of the chaotic systems (Weiet al., 2002). Linear system theory has developedfor many years, but has proved to be incapable ofsufficiently modeling the chaot… 相似文献
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INTRODUCTIONObject oriented (OO )frameworksbecamemoreandmorepopularinthesoftwareindustryduringthe1990s.Aframeworkisasetofcooper atingclassesthatmakeupareusabledesignforaspecificclassofsoftware (Deutsch ,1989;John sonandFoote,1988) .Applicationsbuiltontopofsuchaframeworkreusenotonlyitssourcecodebutalsomoreimportantitsarchitecturedesign(Pree,1994;1995;FayadandSchmidt,1997;MarkiewiczandLucena ,2 0 0 1) .Consequently,theuseofframeworksreducesthecostsandim provesthesoftwarequalitygreatly .… 相似文献
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INTRODUCTIONWithconstantchangingmarketsandenviron ments,itisanurgenttaskforenterprisestoen hanceitsagilityandflexibility (Zhang ,1 996) .Byoptimizinginternalbusinessprocessesandor ganizationstructure ,BPR (businessprocessreengineering)enablesenterprisesto… 相似文献
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ZHANG Feng LI Zhi-ping WANG He-lin WU Jian TAN Zhen-hua 《浙江大学学报(A卷英文版)》2007,8(11):1858-1863
In the phase of field evaluation, the changing of interwell reservoir may be out of control if the geological model was built only on well data due to few existing wells. The uncertainty of the interwell reservoir interpolation based only on well data can be decreased by comprehensive utilization of geological, logging and seismic data, especially by using highly relative seismic properties from 3D seismic data adjusted by well point data to restrict interpolation of geological properties. A 3D-geological model which takes the sand body as the direct modeling object was built through stacking the structure, reservoir and water/oil/gas properties together in 3D space. 相似文献
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LIU Shi-guang WANG Zhang-ye GONG Zheng CHEN Fei-fei PENG Qun-sheng 《浙江大学学报(A卷英文版)》2006,7(7):1099-1106
INTRODUCTIONTornado is one of the most terrible natural phe- nomena in the world. It causes incredible amounts of damage and destroys significant numbers of facilities every year. No wonder it receives great attention as a major research topic in many fields. Realistic simu- lation of tornado is also a great challenge for com- puter graphics researchers. It provides useful infor- mation for natural disaster prevention and can be integrated into entertainment, computer games, etc. Most to… 相似文献
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Dynamic architecture of multi-agent systems （MAS） is important for critical systems. As the existing formal specifications of MAS cannot describe its dynamic architecture, a formal approach using n-calculus is presented, which is suited for the describing and analyzing of concurrent MAS with dynamic topology, n-calculus describes the belief-desireintention （BDI） model that represents agent＇s mental states and provides many useful facilities to analyze MAS model such as deadlock, behavior equivalence, and model checking. To illustrate the favorable representation capability of n-calculus, an example of dynamic multi-agent systems in e-commerce is provided. Finally, by using an existing n-calculus supporting tool, MAS model and some key behaviors properties are analyzed and verified. 相似文献
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REN Xiang-yang MUELLER Heinrich KUHLENKOETTER Bernd 《浙江大学学报(A卷英文版)》2006,7(7):1215-1224
INTRODUCTION The simulation and verification technologies of numerical controlled (NC) manufacturing processes have been developed since the end of the 1970s, and a lot of significant accomplishments have been achieved. This kind of technology has important im- pact on product development and quality control. The designed CAD model can be produced to virtually reduce or even eliminate expensive experiments on testing material. If any potential problem, such as collision, improper parame… 相似文献
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Dynamic architecture of multi-agent systems(MAS)is important for critical systems.As the existing formal specifications of MAS cannot describe its dynamic architecture,a formal approach usingπ-calculus is presented,which is suited for the describing and analyzing of concurrent MAS with dynamic topology,π-calculus describes the belief-desire- intention(BDI)model that represents agent's mental states and provides many useful facilities to analyze MAS model such as deadlock,behavior equivalence,and model checking.To illustrate the favorable representation capability ofπ-calculus,an example of dynamic multi-agent systems in e-commerce is provided.Finally,by using an existingπ-calculus supporting tool, MAS model and some key behaviors properties are analyzed and verified. 相似文献
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SUNGWen-pei LINCheng-I SHIHMing-hsiang GOCheer-germ 《浙江大学学报(A卷英文版)》2005,6(2):132-140
In view of the recent technological development, the pursuit of safe high-precision structural designs has been the goal of most structural designers. To bridge the gap between the construction theories and the actual construction techniques, safety factors are adopted for designing the strength loading of structural members. If safety factors are too conservative, the extra building materials necessary will result in high construction cost. Thus, there has been a tendency in the construction field to derive a precise buckling load analysis model of member in order to establish accurate safety factors. A numerical analysis model, using modal analysis to acquire the dynamic function calculated by dynamic parameter to get the buckling load of member, is proposed in this paper. The fixed and simple supports around the circular plate are analyzed by this proposed method. And then, the Monte Carlo method and the normal distribution method are used for random sampling and measuring errors of numerical simulati 相似文献
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Cellular automata modeling techniques and the characteristics of mixed traffic flow were used to derive the 2-dimensional model presented here for simulation of pedestrian's crossing dynamics.A conception of "stop point" is introduced to deal with traffic obstacles and resolve conflicts among pedestrians or between pedestrians and the other vehicles on the crosswalk.The model can be easily extended,is very efficient for simulation of pedestrian's crossing dynamics,can be integrated into traffic simulation software,and has been proved feasible by simulation experiments. 相似文献
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INTRODUCTION With worldwide increase of air pollution and the environmental consciousness of governments, people have to look for new resources to mitigate the energy crisis and improve the present environmental status (Ferng et al., 2004; Rowe and Li, 2001). Fuel cells are highly efficient and environmentally clean electrical generators (Mann et al., 2000) that convert the chemical energy of a gaseous fuel directly into elec-tricity energy and play an important role in solving the prob… 相似文献
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张晋 王慧Institute of Systems Engineering Zhejiang University Hangzhou China 李平 《Journal of Zhejiang University. Science. B》2004,(7)
INTRODUCTION Computer simulation of traffic can give insightinto a wide variety of phenomena observed in realtraffic flow; lead to a greater understanding of itsbasic principles; and can also help researchers ex-plore the effects of implementing new traffic rulesand control systems without doing potentially ha-zardous experiments with real traffic. Approachesthat apply classic differential equation methods tomodel the nonlinear dynamics of this problem candescribe only part of the ph… 相似文献
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SUNG Wen-pei GO Cheer-germ SHIH Ming-hsiang 《浙江大学学报(A卷英文版)》2007,8(9):1373-1379
The characteristic properties of shell element with similar shapes are used to generate a so-called super element for the analysis of the crack problems for cylindrical pressure vessels. The formulation is processed by matrix condensation without the involvement of special treatment. This method can deal with various singularity problems and it also presents excellent results to crack problems for cylindrical shell. Especially,the knowledge of the kind of singular order is not necessary in super element generation; it is very economical in terms of computer memory and programming. This method also exhibits versatility to solve the problem of kinked crack at cylindrical shell. 相似文献
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Online learning from video modeling examples, in which a human model demonstrates and explains how to perform a learning task, is an effective instructional method that is increasingly used nowadays. However, model characteristics such as gender tend to differ across videos, and the model-observer similarity hypothesis suggests that such characteristics may affect learning. Therefore, this study investigated whether the effectiveness of learning how to solve a probability calculation problem from video modeling examples would vary as a function of the model’s and observer’s gender. In a 2 (Model: Female/Male) × 2 (Observer: Female/Male) between-subject design, 167 secondary education students learned how to solve probability calculation problems by observing video modeling examples. Results showed no effects of Model or Observer gender on learning and near transfer. Male students reported higher self-efficacy than female students. Compared to a female model, observing a male model enhanced perceived competence more from pretest to posttest, irrespective of observers’ gender. Furthermore, learning from a male model was less effortful and more enjoyable for male students than for female students. These results suggest that gender of both model and observer can matter in terms of affective variables experienced during learning, and that instructional designers may want to consider this when creating (online) learning environments with video modeling examples. 相似文献
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Jennifer A. Czocher 《Educational Studies in Mathematics》2018,99(2):137-159
Contemporary scholars describe mathematical modeling as a transformation of a real-world problem to a mathematical problem and back again. This paper treats a critical issue in the modeling process: how modelers determine if the transformation from the real world to mathematics was carried out well. I present an empirically derived typology of validating activities explaining how validating functions to ensure a mathematical model will yield a reasonably accurate prediction. The typology arose from analysis of four engineering undergraduates’ production of 276 instances of validating. The nuances of validating suggest that creating and maintaining relationships between reality and mathematics is more complex than a transformation and that we should afford a more prominent role to validation in the modeling process. 相似文献
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The salt-gradient operation mode used in ion-exchange simulated moving bed chromatography (SMBC) can improve the efficiency of protein separations. A detailed model that takes into account any kind of adsorption/ion-exchange equilibrium, salt gradient, size exclusion, mass transfer resistance, and port periodic switching mechanism, was developed to simulate the complex dynamics. The model predictions were verified by the experimental data on upward and downward gradients for protein separations reported in the literature. All design and operating parameters (number, configuration, length and diameter of columns, particle size, switching period, flow rates of feed, raffinate, desorbent and extract, protein concentrations in feed, different salt concentrations in desorbent and feed) can be chosen correctly by numerical simulation. This model can facilitate the design, operation, optimization, control and scale-up of salt-gradient ion-exchange SMBC for protein separations. 相似文献
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INTRODUCTION Land resources management and ecologicalenvironmental decision-making requires knowl-edge about the spatial distribution, and quantity andquality of soil resources. Soil maps have tradition-ally been made by interpretation of remotely sensedimagery supported by ground surveys. Thus, soilmapping becomes expensive, labor-intensive, andtime-consuming exercises. Moreover, it also issubjective, and may result in inconsistencies in theassignment of soil type boundaries or nam… 相似文献
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Preparing for an exam entails various exam-related emotions. To ensure psychologically healthy behavior and an effective learning process, emotion regulation is highly important. In the present study, we used a dynamic multilevel modeling approach to analyse the interplay of exam-related anxiety and hope, as well as four regulation strategies over time. This study provides valuable insights into students’ emotion regulation in academic settings. Specifically, we measured students’ emotions and regulation strategies (cognitive approach, cognitive avoidance, behavioral approach, behavioral avoidance) across two weeks of measurement. In total, 217 university students answered several questionnaires via an electronic device during two different measurement periods lasting 7 days each. These measurement periods were 5 weeks (day 35–29) and one week (day 7 to 1) prior to an important exam. During their everyday life, they answered these questionnaires six times a day. We applied dynamic multilevel modeling to analyse the data. Results revealed cross-lagged relationships of exam-related emotions on regulation strategies, with the strongest cross-lagged relationship being found for hope and the cognitive approach regulation strategy. Moreover, the temporal distance to the exam affected the strength and direction of these cross-lagged relationships. This study suggests the importance of considering the mechanisms of emotion regulation on the situation level, and that strategies should be tailored to the individual situation rather than employing universal strategies. Further, the extent to which we can interpret the lagged relationships as suggestive of causal mechanisms are discussed. 相似文献
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It is now required for teachers to incorporate computational thinking (CT) into their science classes. Our research modifies the existing structure of a science methods course for preservice teachers to include CT via modeling and simulations. In the first study, preservice teachers were introduced to the basics of coding through an Hour of Code tutorial, followed by an exercise where they programmed an animated model of the solar system using Scratch. In the second study, we created a web-based simulation to visualize Newton’s second law of motion (F?=?ma) with a dynamic graph feature. The simulation is a race between two cars with interactive settings that the user can change, such as changing the mass and force of each car. Results from both studies reveal that after completing the exercises, preservice teachers learned the material effectively, felt that CT exercises would be beneficial in K-8 education, and plan to incorporate CT into their future classrooms. 相似文献