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1.
In this paper, we investigate the flow, heat and mass transfer of a viscous fluid flow over a stretching sheet by including the blowing effects of mass transfer under high flux conditions. Mass transfer in this work means species transfer and is different from mass transpiration for permeable walls. The new contribution from this work is, for the first time, to consider the coupled blowing effects from massive species transfer on flow, heat, and species transfer for a stretching plate. Based on the exact solutions of the momentum equations, which are valid for the whole Navier–Stokes equations, the energy and mass transfer equations are solved exactly and the effects of the blowing parameter, the Schmidt number, and the Prandtl number on the flow, heat and mass transfer are presented and discussed. The solution is given in terms of an incomplete Gamma function. It is found the coupled blowing effects due to mass transfer can have significant influences on velocity profiles, drag, heat flux, as well as temperature and concentration profiles. These solutions provide rare results with closed form analytical expressions and can be used as benchmark problem for numerical code validation.  相似文献   

2.
In this work, forced convective heat transfer of nanofluid in the developing laminar flow (entrance region) in a circular tube is considered. The nanofluid thermal conductivity, as an important parameter, is considered as two parts: static and dynamic part. Simulated results show that the dynamic part of nanofluid thermal conductivity due to the Brownian motion has a minor effect on the heat transfer coefficients, on the other hand, static part of thermal conductivity including nanolayer around nanoparticle has an important role in heat transfer.  相似文献   

3.
朱光  鲍曙光 《运筹与管理》2019,28(12):153-161
本文利用1994~2007年县级数据,以财政自给率作为门槛变量,基于双重面板门槛模型,分析了我国转移支付与地方公共支出的非线性关系。研究结果表明:转移支付对地方公共支出的影响存在显著的门槛效应;转移支付对基本建设支出和行政管理支出的促进作用都更为显著,在某种程度上强化了地方政府行为选择和公共支出结构的扭曲;我国转移支付对公共支出的影响存在地区差异,转移支付不能有效激励经济欠发达地区提供基本公共服务,因而转移支付制度在一定程度上与基本公共服务均等化目标激励不相容。  相似文献   

4.
In this paper, we propose a general framework for Extreme Learning Machine via free sparse transfer representation, which is referred to as transfer free sparse representation based on extreme learning machine (TFSR-ELM). This framework is suitable for different assumptions related to the divergence measures of the data distributions, such as a maximum mean discrepancy and K-L divergence. We propose an effective sparse regularization for the proposed free transfer representation learning framework, which can decrease the time and space cost. Different solutions to the problems based on the different distribution distance estimation criteria and convergence analysis are given. Comprehensive experiments show that TFSR-based algorithms outperform the existing transfer learning methods and are robust to different sizes of training data.  相似文献   

5.
虚拟科技创新团队作为一种优势资源的有效整合机制和从事创新性工作的知识密集型组织,知识的有效转移和持续流动是其成功的关键。本文运用演化博弈论的方法,将转移效应、制度因素、成本损失等影响知识转移的主要因素作为研究问题的关注角度,以知识转移效用函数为切入点,对虚拟科技创新团队知识转移的条件进行分析,系统研究了团队内部知识转移的稳定性、持续性以及演化趋势,并在此基础上提出了改善虚拟科技创新团队知识转移的对策建议。  相似文献   

6.
我国企业通过对外投资可以拥有在分处国内外的两个实体间开展转让定价的机会,以此来对抗跨国公司在华通过转让定价谋求战略竞争优势,获取公平竞争机会.以单市场双寡头古诺竞争下的转让定价决策模型为基础,构建了我国企业对外投资后在国内和国外两个市场与跨国公司进行战略性转让定价博弈模型,发现无论我国企业与跨国公司相比是否具有成本优势,都应该通过对外投资获取开展战略性转让定价机会,与跨国公司进行公平竞争.  相似文献   

7.
The present paper treats the identification of parametric nonminimum phase transfer function. We propose a method of identification based on the inner outer factorization of stable transfer function. It consists of identifying the outer and inner parts of a transfer function separately. The outer part is identified by the use of the second-order spectral estimate from the observed linear process, while the inner part is identified by the use of a higher-order cumulant spectral estimate from the observed process. Respective parameter estimators are determined in the light of asymptotic efficiency. In order to estimate the order of the inner part of a transfer function, a criterion is proposed. It is introduced based on the same principle as in the case of Akaike's AIC.  相似文献   

8.
An analysis is performed to study the unsteady mixed convection flow of a viscous incompressible micropolar fluid adjacent to a heated vertical surface in the presence of viscous dissipation when the buoyancy force assists or opposes the flow. The flow of the fluid and subsequent heat transfer from the stretching surface is investigated with the aid of appropriate transformation variables. The effect of the governing parameters on the flow and heat transfer characteristics as well as the local skin friction coefficient, wall couple stress and the heat transfer rate are thoroughly examined.  相似文献   

9.
For students to develop an understanding of functions, they must have opportunities to solve problems that require them to transfer between algebraic, numeric, and graphic representations (transfer problems). Research has confirmed student difficulties with certain types of transfer problems and has suggested instructional factors as a possible cause. Algebra teachers (n= 28) were surveyed to determine the amount of class time they devote to different types of transfer problems and how many times these problems appear on their teacher‐made assessments. Results suggest that teachers dedicate less class time to graphic to numeric transfer problems than to any other type of transfer problem and that these problems appear less frequently on assessments. These are exactly the types of transfer problems that pose the most difficulty for students. It is conjectured that teachers' familiarity with these problems, combined with assumed student mastery, contribute to this mismatch.  相似文献   

10.
Queueing network modeling of manufacturing systems has been addressed by a large number of researchers. The purpose of this paper is to provide a bibliography of material concerned with modeling of production and transfer lines using queueing networks. Both production and transfer lines have a product-flow layout and are used in mass manufacturing. We denote production lines as flow lines with asynchronous part transfer, while transfer lines have synchronous part transfer. As well as providing a bibliography of material, a contribution of this paper is also the systematic categorization of the queueing network models based on their assumptions. This, it is hoped, will be of use to researchers of queueing networks and also manufacturing system designers. A number of suggestions are also given for further research. The basic source for this work is the book by Papadopoulos, Heavey and Browne, with the addition of the newly published papers and books (from 1992 to early 1995).  相似文献   

11.
A common of finite-time heat transfer processes between high- and low-temperature sides with generalized radiative heat transfer law [q ∝ Δ(Tn)] is studied in this paper. In general, the minimization of entropy generation in heat transfer processes is taken as the optimization objective. A new physical quantity, entransy, has been identified as a basis for optimizing heat transfer processes in terms of the analogy between heat and electrical conduction recently. Heat transfer analyses show that the entransy of an object describes its heat transfer ability, as the electrical energy in a capacitor describes its charge transfer ability. Entransy dissipation occurs during heat transfer processes, as a measure of the heat transfer irreversibility with the dissipation related thermal resistance. Under the condition of fixed heat load, the optimal configurations of hot and cold fluid temperatures for minimizing entransy dissipation are derived by using optimal control theory. The condition corresponding to the minimum entransy dissipation strategy with Newtonian heat transfer law (n = 1) is that corresponding to a constant heat flux rate, while the condition corresponding to the minimum entransy dissipation strategy with the linear phenomenological heat transfer law (n = −1) is that corresponding to a constant ratio of hot to cold fluid temperatures. Numerical examples for special cases with Newtonian, linear phenomenological and radiative heat transfer law (n = 4) are provided, and the obtained results are also compared with the conventional strategies of constant heat flux rate and constant hot fluid (reservoir) temperature operations and optimal strategies for minimizing entropy generation. Moreover, the effects of heat load changes on the optimal hot and fluid temperature configurations are also analyzed.  相似文献   

12.
We study a lattice model that is closely related to the Ising model and can be regarded as describing diffusion of loops in two dimensions. The time development is given by a transfer matrix for a random surface model on a three-dimensional lattice. The transfer matrix is indexed by loops and is invariant under a group of motions in the loop space. The eigenvalues of the transfer matrix are calculated in terms of the partition function and the correlation functions of the Ising model.  相似文献   

13.
14.
在习近平新时代中国特色社会主义思想框架的指导下,军民融合已经上升为国家战略,技术转移作为军民两大板块多领域、全要素、深层次对接的重要载体,其转移效率直接影响到军民融合深度发展战略的实施。以2012~2016年间中国A股证券市场军民融合板块下45家企业的数据为基础,采用DEA的方法,通过测度不同区域技术转移效率,分析军民融合企业技术转移效率的区域差异并进行收敛性研究,进而通过面板 tobit模型分析以企业、政府、高校、环境四个方面产生的六个因素对军民融合企业技术转移效率的影响。研究结果表明:近五年军民融合企业技术转移效率波动较大,年际差异和省际差异都较为显著。军民融合企业自身规模、产品的差异化、政府的科技投入、技术市场成交额对技术转移效率有正向影响,高校数量、地区GDP对军民融合企业技术转移效率影响不显著。最后,提出相应的管理建议。  相似文献   

15.
本文给出了控制系统的广义传递函数和它的连续性的定义.利用广义传递函数作为工具,建立了一组判定运动稳定性的定理,从而把对一个控制动力学系统特性的了解建立在这个系统的被观测过程之中,简化了运动稳定性问题的判定方法.  相似文献   

16.
现有的动态群体决策实践经常存在决策速度慢、观点不收敛的问题。本研究融入知识共享/转移的因素,从决策动态交互的过程视角,探讨决策绩效(一致性及决策时间)的改善机理、影响因素,从而提高相应绩效指标。研究通过构建决策过程模型,证明了知识共享/转移考虑下一致性序列在交互过程中的收敛性。同时,通过定性模拟判断知识共享/转移对决策时间的影响,以最小化决策时间为优化目标,搜索知识共享/转移水平,给出了个体知识差异构成的多维空间下最优的行动方案。  相似文献   

17.
This paper presents the use of a transfer pricing system to coordinate business units in a Wagner–Whitin type model for a decentralized lot-sizing problem in a dynamic multistage, multiproduct environment. The paper includes two major proofs: (1) a transfer pricing system enabling optimal decentralized lot-sizing is characterized. The transfer pricing system can be interpreted as a generalization of the reciprocal method or step-down allocation method in cost location accounting; and (2) based on a Wagner–Whitin type theorem and the Kakutani fixed point theorem, it is shown that such a transfer pricing system exists.  相似文献   

18.
The transfer of programs from development systems to efficient run-time environments is generally considered as a compilation process possibly followed by an optimization phase. This order excludes most possibilities to make optimizations on the source language level. This paper describes an alternative transfer method where user interaction is done on a user oriented level in order to support the optimization process. Experiments show that the efficiency gain is considerable.  相似文献   

19.
基于BP神经网络的时间序列预测问题研究   总被引:3,自引:0,他引:3  
分析指出了基于标准BP神经网络的时间序列预测问题存在的不足.根据基于BP神经网络的时间序列预测问题的特点,研究给出了一种以y=x作为传递函数的时间序列预测方法,经实例验证表明,给出的以y=x作为传递函数的时间序列预测方法较基于标准BP神经网络的时间序列预测方法具有较好的结果.  相似文献   

20.
In this paper, we construct a special class of subshifts of finite type. By studying the spectral radius of the transfer matrix associated with the subshift of finite type, we obtain an estimation of its topological entropy. Interestingly, we find that the topological entropy of this class of subshifts of finite type converges monotonically to log(n + 1) (a constant only depends on the structure of the transfer matrices) as the increasing of the order of the transfer matrices.  相似文献   

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