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171.
一种新型近共沸混合工质的循环性能实验研究 总被引:1,自引:0,他引:1
文中开展了对一种新型近共沸混合物的整机性能实验研究,该混合物具有零ODP值和低GWP值,可作为传统工质R502甚至是R404A的长期替代物。根据国标GB/T 5773-2004搭建了第二制冷剂量热器的整机性能测试实验台。试验在蒸发温度为-40℃的商用制冷温区进行,系统研究了在不同蒸发温度、冷凝温度、过冷度、过热度等工况下的性能。实验结果与R404A进行了比较,包括压比、压缩机功耗、制冷量、COP、吸气温度。实验结果表明,该新工质COP比R404A高9.2%至14.2%。 相似文献
172.
Ruoyan Sun 《Physics letters. A》2017,381(1):19-23
We combined an epidemic model with an objective function to minimize the weighted sum of people with excess weight and the cost of a medication and surgical intervention in the population. The epidemic model is consisted of ordinary differential equations to describe three subpopulation groups based on weight. We introduced an intervention using medication and surgery to deal with excess weight. An objective function is constructed taking into consideration the cost of the intervention as well as the weight distribution of the population. Using empirical data, we show that fixed participation rate reduces the size of obese population but increases the size for overweight. An optimal participation rate exists and decreases with respect to time. Both theoretical analysis and empirical example confirm the existence of an optimal participation rate, . Under , the weighted sum of overweight (S) and obese (O) population as well as the cost of the program is minimized. This article highlights the existence of an optimal participation rate that minimizes the number of people with excess weight and the cost of the intervention. The time-varying optimal participation rate could contribute to designing future public health interventions of excess weight. 相似文献
173.
The “relative entropy” has been used as a minimization function to predict the tertiary structure of a protein backbone, and
good results have been obtained. However, in our previous work, the ensemble average of the contact potential was estimated
by an approximate calculation. In order to improve the theoretical integrity of the relative-entropy-based method, a new theoretical
calculation method of the ensemble average of the contact potential was presented in this work, which is based on the thermodynamic
perturbation theory. Tests of the improved algorithm were performed on twelve small proteins. The root mean square deviations
of the predicted versus the native structures from Protein Data Bank range from 0.40 to 0.60 nm. Compared with the previous
approximate values, the average prediction accuracy is improved by 0.04 nm.
Contributed equally to this work
Supported by the National Natural Science Foundation of China (Grant No. 30670497), the Beijing Natural Science Foundation
(Grant No. 5072002), and the Specialized Research Foundation for the Doctoral Program of Higher Education (Grant No. 200800050003) 相似文献
174.
Effendi Widjaja Hui Heng Chong Martin Tjahjono 《Journal of Raman spectroscopy : JRS》2010,41(2):181-186
In situ thermo‐Raman spectroscopy (TRS) measurements were performed in order to investigate solid‐phase transformation of the copper sulfate pentahydrate from room temperature up to 300 °C. Band‐target entropy minimization (BTEM), a blind‐source separation algorithm, was employed in order to identify and reconstruct the pure component spectra of the species involved in the dehydration process. In spite of low signal‐to‐noise ratio and elevated baseline spectral data, BTEM was successfully utilized to identify and reconstruct four pure component spectra of copper sulfate pentahydrate, trihydrate, monohydrate, and anhydrate, which were formed during this thermally induced process. Subsequent mapping of these four pure component spectral estimates back onto the preprocessed spectra yielded the relative concentrations of each individual species. Finally, the transition temperatures of each dehydration step could be unambiguously deduced from the obtained concentration profile. The current study shows that combined thermo‐Raman spectroscopy and chemometric analysis provides an effective tool to determine the dehydration temperatures as well as to identify the structures of each individual species involved in a solid‐phase dehydration process. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
175.
Two-phase image segmentation is a fundamental task to partition an image into foreground and background. In this paper, two types of nonconvex and nonsmooth regularization models are proposed for basic two-phase segmentation. They extend the convex regularization on the characteristic function on the image domain to the nonconvex case, which are able to better obtain piecewise constant regions with neat boundaries. By analyzing the proposed non-Lipschitz model, we combine the proximal alternating minimization framework with support shrinkage and linearization strategies to design our algorithm. This leads to two alternating strongly convex subproblems which can be easily solved. Similarly, we present an algorithm without support shrinkage operation for the nonconvex Lipschitz case. Using the Kurdyka-Łojasiewicz property of the objective function, we prove that the limit point of the generated sequence is a critical point of the original nonconvex nonsmooth problem. Numerical experiments and comparisons illustrate the effectiveness of our method in two-phase image segmentation. 相似文献
176.
177.
A Practical Algorithm for Determining the Optimal Pseudo-Boundary in the Method of Fundamental Solutions 下载免费PDF全文
A. Karageorghis 《advances in applied mathematics and mechanics.》2009,1(4):510-528
One of the main difficulties in the application of the method of
fundamental solutions (MFS) is the determination of the position of
the pseudo-boundary on which are placed the singularities in terms
of which the approximation is expressed. In this work, we propose a
simple practical algorithm for determining an estimate of the
pseudo-boundary which yields the most accurate MFS approximation
when the method is applied to certain boundary value problems.
Several numerical examples are provided. 相似文献
178.
最小风险证券组合的结构分析和迭代算法 总被引:1,自引:0,他引:1
本文分析了最小风险组合证券投资的结构特征,并提出了一种组合证券风险最小化的迭代算法,证明了其收敛性.该算法操作简单,且易于处理不允许卖空情况下的证券组合问题. 相似文献
179.
Nonlinear complementarity as unconstrained optimization 总被引:8,自引:0,他引:8
C. Kanzow 《Journal of Optimization Theory and Applications》1996,88(1):139-155
Several methods for solving the nonlinear complementarity problem (NCP) are developed. These methods are generalizations of the recently proposed algorithms of Mangasarian and Solodov (Ref. 1) and are based on an unconstrianed minimization formulation of the nonlinear complementarity problem. It is shown that, under certain assumptions, any stationary point of the unconstrained objective function is already a solution of NCP. In particulr, these assumptions are satisfied by the mangasarian and Soolodov implicit Lagranian functioin. Furthermore, a special Newton-type method is suggested, and conditions for its local quadratic convergence are given. Finally, some preliminary numerical results are presented.The author would like to thank Dr. Oswald Knoth (Leipzig) for pointing out that the equivalence of Lemma 2.2. is not true for complementarity problems which have no solutions. He is also grateful to the anonymous referencees for their helpful comments. 相似文献
180.
系统地研究Nb2TiO7与Nb1.33Ti0.67O4材料相互转变的氧化还原循环可逆性能,同时研究Nb2TiO7和Nb1.33Ti0.67O4样品随温度和氧分压变化的电导率,并与复合电极对称电池和电解池的电化学性能相关联. 在830 oC下,对Nb1.33Ti0.67O4复合电极电解池进行水蒸气的电解研究测试. 电流电压曲线和电解池短期性能测试表明在低电压下主要为电极的还原和活化过程;而在高电压下主要为水蒸气的电解. 当3%H2O/Ar/4%H2气体通入阴极时电解池水蒸气电解的法拉第效率为98.9%;而当通入气体转换为3%H2O/Ar时效率为89%. 相似文献