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排序方式: 共有314条查询结果,搜索用时 15 毫秒
21.
Asif Iqbal Naeem U. Dar Ning He Muhammad M. I. Hammouda Liang Li 《Journal of Intelligent Manufacturing》2010,21(6):761-776
The foremost challenge faced by expert systems, for their applicability to real world problems, is their inherent deficiency
of dynamism. For an expert system to be more pragmatic and applicable, the whole structure of an expert system—including rule-base,
fuzzy sets, and even user-interface—needs to be upgraded continuously. This continuous up gradation demands full-time, repetitive,
and cumbersome involvement of knowledge engineers. Machine learning is an answer to this problem, but unfortunately, the solutions
that have been provided are limited in scope. For example, most of the researchers put forward techniques of either generating
just rules from data, or self-expanding and self-correcting knowledge-base only. The innovative approach presented in this
paper is broader in scope. It enhances the efficacy and viability of expert systems to be more capable of coping with dynamic
and ever-changing industrial environments. The objective is facilitated by rendering, concurrently, the self-learning, self-correcting,
and self-expanding abilities to the expert system, without requiring knowledge engineering skills of the developers. This
means that the user needs just to feed data in form of the values of input/output variables and the complete development of
expert system is done automatically. The superiority of the proposed expert system, regarding its continuous self-development,
has been explained with the help of three examples related to prediction and optimization of milling and welding processes. 相似文献
22.
Siddiqui Pirzada Jamal Ahmed Khan Adnan Uddin Nizam Khaliq Saima Rasheed Munawwer Nawaz Shazia Dar Ahsana Hanif Muhammad 《Food science and biotechnology》2017,26(4):1055-1062
Food Science and Biotechnology - Recently, considerable attention has been paid to drug exploration from natural sources for treating memory loss, a major manifestation of various neurodegenerative... 相似文献
23.
J. Darío Aristizábal-Ochoa 《Canadian Metallurgical Quarterly》2004,130(3):274-282
The large-deflection elastic analysis of slender beam-columns of symmetrical cross sections with semirigid connections under end loads (forces and moments) including the effects of out-of-plumbness is developed in a classical manner. The classical theory of the “Elastica” and the corresponding elliptical functions are utilized in the proposed method which can be used in the large-deflection stability analysis of slender beam-columns with rigid, semirigid, and simple connections under any combination of end loads (conservative and nonconservative). The proposed method consisting of a closed-form solution of the Elastica can also be utilized in the large deflection analysis of beam-columns whose connections suffer from flexural degradation or, on the contrary, flexural stiffening. The main limitation of the Elastica is that only flexural strains are considered (the effects of axial and shear strains are neglected). Therefore results from the proposed method are theoretically exact from small to very large curvatures and transverse and longitudinal displacements for plane beam-columns under bending actions. The large-deflection analysis of a beam-column with flexible connections at both ends becomes a complex problem requiring the simultaneous solution of at least two highly nonlinear equations with elliptical integrals. The solution of this problem becomes even more complex when the end connections are nonlinear or the direction of the applied end load changes (like “follower” loads). The validity and effectiveness of the proposed method and equations are verified against available solutions of very large deflection elastic analysis of beam-columns. Four comprehensive examples are included for verification and easy reference. 相似文献
24.
Silicon - Silicon (Si) is very effective in the amelioration of heavy metal (HM) stress in different crop plants. This investigation was conducted to assess the protective role of Si in modulating... 相似文献
25.
We have been studying free-radical polymerization that is accompanied by phase separation above the lower critical solution temperature. In the past, we have experimentally shown evidence of hot regions in the reactive system. We have also shown in the past that eventually the system exerts control over the rate of propagation as well as termination. In this work, we invoke a concept in polymer physics (the coil-to-globule transition) to help explain the mechanism of thermal trapping within the polymerization zones. The diffusivities of polymer chains at different stages in the reaction are calculated using appropriate methods. From the diffusivities, the propagation and termination rate coefficients are calculated using the Achilias-Kiparissides gel effect model. With experimental kinetic data, we then estimate rates of monomer consumption within polymer-rich particles. Using a pseudo-steady-state heat transfer model, we are able to show that interior temperatures of polymer-rich particle domains greater than about 1 mm can reach spinodal temperature values at the early stage of polymerization. Polymer-rich particle sizes are obtained from the same reactor system whereby a small amount of crosslinker is added to preserve particle morphology. This experiment indicates that even under turbulent flow conditions, relatively large particles can exist in the reactor fluid. This agrees with the physical implications of the coil-to-globule transition. However, since these particles were obtained during the period of slow conversion rate, our heat transfer calculations indicate that interior particle temperatures would be almost the same as surface temperatures. This points to an unknown radical-trapping mechanism at this stage of the polymerization process. 相似文献
26.
Dar Reuven; Stronguin Florencia; Etter Jean-Francois 《Canadian Metallurgical Quarterly》2005,73(2):350
In this report, the authors explore the relationships of perceived treatment to outcome in a large, placebo-controlled trial of nicotine replacement treatment for smoking reduction. In the original study (J. F. Etter, E. Laszlo, J. P. Zellweger, C. Perrot, & T. V. Perneger, 2002), which was conducted in French-speaking Switzerland, smokers were randomly assigned to receive nicotine, matching placebo products, or no intervention. At the end of the 6-month study, participants were asked to guess whether they had received nicotine or placebo. In the present analysis, the authors examined the difference in smoking reduction between those who believed they had received nicotine and those who believed they had received placebo. Regardless of actual treatment, smokers who believed they had received nicotine had significantly better outcome than those who believed they had received placebo. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
27.
Uzair Ahmed Dar Wei Hong Zhang Ying Jie Xu 《International Journal of Mechanics and Materials in Design》2014,10(1):93-107
In this work, a nonlinear viscoelastic constitutive relation was implemented to describe the mechanical behavior of a transparent thermoplastic polymer polymethyl methacrylate (PMMA). The quasi-static and dynamic response of the polymer was studied under different temperatures and strain rates. The effect of temperature was incorporated in elastic and relaxation constants of the constitutive equation. The incremental form of constitutive model was developed by using Poila–Kirchhoff stress and Green strain tensors theory. The model was implemented numerically by establishing a user defined material subroutine in explicit finite element (FE) solver LS-DYNA. Finite element models for uniaxial quasi-static compressive test and high strain rate split Hopkinson pressure bar compression test were built to verify the accuracy of material subroutine. Numerical results were validated with experimental stress strain curves and the results showed that the model successfully predicted the mechanical behavior of PMMA at different temperatures for low and high strain rates. The material model was further engaged to ascertain the dynamic behavior of PMMA based aircraft windshield structure against bird impact. A good agreement between experimental and FE results showed that the suggested model can successfully be employed to assess the mechanical response of polymeric structures at different temperature and loading rates. 相似文献
28.
由深度数据重建三维物体的一种方法 总被引:1,自引:0,他引:1
讨论由深度数据重建三维物体的一种新方法.其基本思想是根据由基于物体旋转的主动式三角法三维信息获取系统所获取的物体深度数据作为该物体的型值点.再根据型值点进行网格划分,以便形成满足一定约束条件的空间拓扑网格.最后使用有理Bezier三角曲面片与矩形曲面片相结合的方法进行曲面拟合与逼近. 相似文献
29.
Multiclass determination of sunscreen chemicals in water samples by liquid chromatography-tandem mass spectrometry 总被引:1,自引:0,他引:1
Rodil R Quintana JB López-Mahía P Muniategui-Lorenzo S Prada-Rodríguez D 《Analytical chemistry》2008,80(4):1307-1315
A novel analytical method based on solid-phase extraction (SPE) and liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) for the determination of UV sunscreen agents in the water environment is presented. After a thorough investigation of SPE and LC-MS/MS conditions, it permits the enrichment and determination of nine of these compounds in a single methodology, including three very polar sulfonates (e.g., 2-phenylbenzimidazole-5-sulfonic acid, PBSA) and six other less polar compounds (e.g., benzophenone-3, BP-3; octocrylene, OC,...). Other important matters of concern in the determination of UV filters at trace levels in water, i.e., adsorption on glassware and blank contamination problems, have also been discussed and minimized. This methodology affords detection limits between 7 and 46 ng L-1 and SPE recoveries in the range 63-102% from different real water matrixes, except for butylmethoxydibenzoylmethane (BM-DBM), which was not determinable in wastewater samples due to adsorption problems. The application of the method allowed reporting the levels of benzophenone-4 (BP-4) in environmental water samples for the first time, where it was identified as one of the most important in concentration among the UV filters studied, particularly in wastewater (237-1481 ng L-1). 相似文献
30.
DP Fyhrie C Milgrom SJ Hoshaw A Simkin S Dar D Drumb DB Burr 《Canadian Metallurgical Quarterly》1998,26(4):660-665
BACKGROUND: It has already been shown that the production of fucosylceramide, an aberrant glycolipid, is associated with neoplastic changes in human tissues. The authors of this study designed a sandwich radioimmunoassay (RIA) using a mouse monoclonal anti-fucosylceramide antibody, PC47H, designated as PC/PC RIA, and measured the level of u-FCC, an antigen of PC47H, in the urine of cancer patients. METHODS: The cohort comprised 41 patients with gastric carcinoma, 35 with colorectal carcinoma, 34 with other malignancies, 14 with cholelithiasis, 18 with gastric ulcer, and 110 healthy individuals. The u-FCC was quantified by PC/PC RIA. The cutoff value of u-FCC was obtained from the 110 healthy individuals, and the rates of positivity for gastric and colorectal carcinoma patients were evaluated. RESULTS: The rates of u-FCC positivity were 63% for patients with gastric carcinoma and 69% for colorectal carcinoma patients. The rate was only 1% (1/110) for the healthy individuals. The u-FCC value did not correlate with the values of either CA 19-9 or carcinoembryonic antigen (CEA). In a combination assay of u-FCC with CA 19-9 and CEA, the positivity rates were 84% for gastric carcinoma patients and 85% for colorectal carcinoma patients. CONCLUSIONS: Gastric and colorectal carcinoma patients have significantly high levels of u-FCC in their urine compared with normal individuals. 相似文献