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31.
A protocol for performance evaluation of line detection algorithms   总被引:4,自引:0,他引:4  
Accurate and efficient vectorization of line drawings is essential for any higher level processing in document analysis and recognition systems. In spite of the prevalence of vectorization and line detection methods, no standard for their performance evaluation protocol exists. We propose a protocol for evaluating both straight and circular line extraction to help compare, select, improve, and even design line detection algorithms to be incorporated into line drawing recognition and understanding systems. The protocol involves both positive and negative sets of indices, at pixel and vector levels. Time efficiency is also included in the protocol. The protocol may be extended to handle lines of any shape as well as other classes of graphic objects.  相似文献   
32.
In this paper, we propose a logic of argumentation for the specification and verification (LA4SV) of requirements on Dung??s abstract argumentation frameworks. We distinguish three kinds of decision problems for argumentation verification, called extension verification, framework verification, and specification verification respectively. For example, given a political requirement like ??if the argument to increase taxes is accepted, then the argument to increase services must be accepted too,?? we can either verify an extension of acceptable arguments, or all extensions of an argumentation framework, or all extensions of all argumentation frameworks satisfying a framework specification. We introduce the logic of argumentation verification to specify such requirements, and we represent the three verification problems of argumentation as model checking and theorem proving properties of the logic. Moreover, we recast the logic of argumentation verification in a modal framework, in order to express multiple extensions, and properties like transitivity and reflexivity of the attack relation. Finally, we introduce a logic of meta-argumentation where abstract argumentation is used to reason about abstract argumentation itself. We define the logic of meta-argumentation using the fibring methodology in such a way to represent attack relations not only among arguments but also among attacks. We show how to use this logic to verify the requirements of argumentation frameworks where higher-order attacks are allowed [A preliminary version of the logic of argumentation compliance was called the logic of abstract argumentation?(2005).]  相似文献   
33.
In this paper a new approach to the control of a nonlinear, time-varying process is proposed. It is based on a recursive version of the fuzzy identification method and predictive functional control. First, the recursive fuzzy identification method is derived, after which it is used in connection with fuzzy predictive functional control to construct an adaptive fuzzy predictive functional controller. The adaptive FPFC is then tested on a nonlinear, time-varying, semi-batch reactor process and compared with the standard FPFC, which uses non-adaptive fuzzy model. The simulation results are promising; they indicate that the control of time-varying, nonlinear processes with the FPFC can be improved with the use of an adaptive fuzzy model. An improvement in reference tracking and disturbance rejection can be observed, but the main advantage is the reduced number of switchings between hot and cold water. This is an important improvement in the case of real applications.  相似文献   
34.
High shoring towers, the common shoring solution for high clearance construction, cause the entire formwork system to account for a remarkably high percentage of the cost of the constructed concrete element. However, data on work inputs in assembly and disassembly of high towers are scarce, and the reason lies in the difficulty in conducting the numerous work studies that would be needed to cover the wide variety of tower types offered by the market and the extensive range of heights to which towers are erected. A model is presented, based on a limited number of work studies, for the prediction of work inputs in the assembly and disassembly of shoring towers of two configurations, rising to heights of up to 30 m. Results of actual measured work input data for three tower models representing three tower types widely used on construction sites are presented. An insight is provided into the anatomy of tower erection, which should make possible use of the proposed methodology for the development of similar models for additional tower types.  相似文献   
35.
Academic conferences are places of situated learning dedicated to the exchange of knowledge. Knowledge is exchanged between colleagues who are looking to enhance their future research by taking part in several formal and informal settings (lectures, discussions and social events). We studied the processes of knowledge sharing and the influence of the use of IT at the International Conference of Information Systems (ICIS2007) held in Montréal. We describe the categories of knowledge content shared at the conference. Two forms of knowledge sharing were analyzed: formal, guided, planned knowledge sharing in lectures or discussions, and informal knowledge exchange during social events. Data were collected from 274 participants at the conference. The intensity of knowledge sharing in the formal settings was higher compared to the informal settings and was perceived as contributing to future research and to the creation of social relationships. In contrast, informal knowledge sharing contributed mainly to job enhancement and to the initiation of meetings. The discussion centers on planning and evaluating conferences in terms of seeking, creating and sustaining knowledge sharing.  相似文献   
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37.
Synchronized external pulsation is proposed as a method to improve tolerance to acceleration stress. This technique uses a modified anti-G suit which is pressurized and depressurized synchronously with the heart cycle. The feasibility of the procedure has been studied using a computer model of the cardiovascular system which includes the effects of Gz stress, and contains simulations of baroreceptor control of heart rate and venous tone. Model predictions indicate that for unprotected subjects, carotid pressure at eye level (ophthalmic artery pressure) decreases to 20 mmHg (beginning of central light loss) at approximately +3.6 Gz. Applying standard anti-G suit pressure to the model increases this level to 5.3 Gz. When synchronized external pulsation of 2 psi is superimposed on the standard anti-G suit pressure, the tolerance to acceleration stress is further augmented by at least 0.9 G above the protection afforded by the standard anti-G suit alone. A set of preliminary experiments on human subjects to test the feasibility of using the technique in the high-G environment has also been carried out. The results under various protection modes compare favorably to the model predictions. Our results suggest that the computer model presented here is a useful tool for studying cardiovascular responses under +GZ stress. It also indicates that using synchronized external pulsation pressure superimposed on the standard anti-G suit pressure may offer extra protection to acceleration stress.  相似文献   
38.
The authors report 5 studies that demonstrate that manhood, in contrast to womanhood, is seen as a precarious state requiring continual social proof and validation. Because of this precariousness, they argue that men feel especially threatened by challenges to their masculinity. Certain male-typed behaviors, such as physical aggression, may result from this anxiety. Studies 1-3 document a robust belief in (a) the precarious nature of manhood relative to womanhood and (b) the idea that manhood is defined more by social proof than by biological markers. Study 4 demonstrates that when the precarious nature of manhood is made salient through feedback indicating gender-atypical performance, men experience heightened feelings of threat, whereas similar negative gender feedback has no effect on women. Study 5 suggests that threatening manhood (but not womanhood) activates physically aggressive thoughts. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
39.
The high frequency C-V characteristics of poly SiSiO2Si capacitors have been studied. It is shown that the poly SiSiO2Si capacitor C-V characteristics are significantly different from the corresponding metal-SiO2Si capacitor due to field penetration into the poly Si layer. A comparison of the theoretical and measured C-V characteristics gives an estimate of the surface state charge density at the poly SiSiO2 interface and indicates that the surface potential behavior of this interface is trap and surface state dominated up to poly silicon impurity concentrations of approximately 1017 cm?3.  相似文献   
40.
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