提高我国农产品流通效率的对策研究

我国是一个农业大国,农产品的生产已取得突飞猛进的发展,但目前尚未形成高效畅通的农产品流通体系。农产品流通效率的低下已成为制约农业与农村经济发展的一个重要因素。提高农产品的流通效率,增加农民收入,必须从完善农产品流通入手。要发展现代的农产品流通模式,发挥农民专业合作经济组织的服务功能,加强农产品流通信息体系建设,提高农民的营销意识,健全质量标准体系和认证体系。     

Upper bounds for port bond causal orientations of weighted junction structures

Three upper bounds are given for the number of distinct sets of port variables which can be used to specify weighted junction structure input-output relattions. Each successive bound is shown to be numerically smaller and computationally more expensive than its predecessor. Examples are given which use the established bounds.     

基于多个决策变量的供应链契约协调研究

当供应链上存在订货、促销努力多个决策变量时，为了协调面临不确定需求零售商的订货和促销努力决策活动．需要根据需求能否被观察或促销努力成本能否被确认，结合回购契约，分别设计销售折扣、促销努力成本共享等形式更为复杂的契约。     

Structural vibration control

Undesirable time-variable motions of dynamical structures (e.g. scales, balances, vibratory platforms, bridges and buildings) are mainly caused by unknown or uncertain excitations. In a variety of applications it is desirable or even necessary to attenuate these disturbances in an effective way and with moderate effort. Hence, several passive as well as active methods and techniques have been developed in order to treat these problems. However, employment of active techniques often fails because of their considerable financial costs. We propose an affordable control scheme which accounts for the above-mentioned deficiencies. In addition, we allow constraints on control actions. Furthermore, the number of control inputs (actuators) may be arbitrary, i.e., the system may be mismatched. The scheme is based on Lyapunov stability theory and, provided that the bounds of the uncertainties are a priori known, a stable attractor (ball of ultimate boundedness) of the structure can be computed. In case measurement errors or uncertainties, respectively, are significant, it is shown how the Lyapunov-based control scheme may be combined with a fuzzy control concept. The effectiveness and behavior of the control scheme is demonstrated on two simplified models of elastic structures such as a two story building and a bridge subjected to a moving truck.     

Stabilization irrespective of bounds of uncertain variations for linear uncertain systems with delays

In this study, the stabilizability irrespective of the bounds of uncertain parameters and time delays is investigated for linear uncertain delay systems. For uncertain systems without delays, a linear time-varying or time-invariant uncertain system has been shown to be stabilizable independent of the bounds of uncertain variations if and only if the system has a particular geometric configuration called an antisymmetric stepwise configuration (ASC) or a generalized antisymmetric stepwise configuration (GASC), respectively. In this study, fundamental approaches to investigating the stabilizability of delay systems with specific uncertainty structures such as ASCs or GASCs are presented. For a class of 3-dimensional systems, it is shown here that if a linear time-varying or time-invariant uncertain delay system has an ASC or a GASC, respectively, then the system can be stabilized, however large the given bounds of delays and uncertain parameters might be.     

Delay-dependent criteria for absolute stability of uncertain time-delayed Lur’e dynamical systems

This paper deals with the absolute stability analysis for uncertain time-delayed Lur systems with sector and slope restricted nonlinearities. New delay-dependent stability criteria are derived via linear matrix inequality (LMI) formulation that can be easily solved by various convex optimization techniques. Sector bounds and slope bounds are employed to a Lyapunov-Krasovskii functional through convex representation of the nonlinearities so that less conservative stability conditions are obtained. A numerical example shows effectiveness of the proposed stability condition over some existing ones.     

On piecewise linear approximation of attenuation function with specified slope and range

A method of approximating attenuation functions by straight line segments whose slope and range can be chosen independently within certain bounds is described. Realization of the approximant is straightforward, and results in a simple, easily adjustable network. The maximum approximation error is calculated and can be made as small as desired. The method can be applied to adaptive amplitude equalizers.     

Equilibrium and duality in electromagnetic field problems

Electromagnetic fields can be treated as systems in which the field equations are the equations of equilibrium. This formulation draws the subject into the unified approach of mechanics. Close analogies to potential and kinetic energy exist and these can be used to provide double bounds to the electromagnetic energy.     

渔捞业最佳经济捕捞努力量的一种确定方法

渔捞业中最佳经济产量是指能使持续的纯利润最大的产量，此时投入的捕捞努力量为最佳经济捕捞努力量，文中假定捕捞总成本与鱼类种群密度成反比而与捕捞努力量成正比，给出了最佳经济捕捞力量 的求解方法。保持这样的捕捞努力量，则可实现渔涝业的可持续发展。     

Approximate lower bound for the SNR of matched filters

For the simple binary detection problem of detecting a known signal in the presence of additive noise, the matched filter is well known to yield the highest output signal-to-noise ratio (SNR). When the detection is carried out in discrete time, selecting an optimal filter length for a specific detection problem is important. Bounds on the SNR of the matched filter can assist in this selection. Exact bounds on the SNR can be computed in terms of the eigenvalues of the noise covariance matrix, but these bounds can be difficult to compute. An approximate lower bound for the SNR has been suggested recently by Martinez and Thomas (see Ref. (2), Franklin Inst. Vol. 321, No. 5, pp. 251–260, 1986). A supplement to this bound which is more accurate for small values of filter length is discussed in this paper. Some examples which delineate a comparison between the two approximate bounds are presented.     

政府补贴下考虑销售努力的闭环供应链研究

在废旧资源回收再利用行业的发展进程中,再造品销售困难是当前行业所面临的主要问题。本文从改善再造品销售难的现状出发,将零售商针对再造品进行销售努力与政府补贴再造品销售两者综合考虑,构建政府补贴下考虑销售努力的闭环供应链决策模型,通过不同模型决策的对比分析及算例仿真分析,为改善再造品销售困难问题提出相关对策。研究表明,零售商进行再造品的销售努力行为能扩大再造品市场比例的同时增加市场总需求,政府补贴可以缓解零售商的努力成本压力、控制再造品销售价格在销售努力过程中上升等问题,因此,政府补贴与销售努力相结合的方式是可以改善再造品销售困难问题的经济可行性对策。     

考虑CSR与质量努力的闭环供应链决策研究

为减少消费者对再造品质量水平的质疑,促进再造品销售,本文构建了有无零售商企业社会责任与制造商质量努力的四个闭环供应链模型,运用stackelberg博弈与逆向归纳法求出均衡解,通过对比、算例仿真各均衡结果探讨其对闭环供应链利润、价格等因素的影响,并提出相应对策。研究表明：（1）制造商质量努力能够扩大再造品的市场份额及产品的市场规模。一定范围内的质量努力能够使闭环供应链各方均获益。（2）零售商履行企业社会责任能够提升企业品牌形象,扩大产品的市场规模,使制造商、闭环供应链系统及社会福利获益。（3）一定范围内的质量努力能够缓解零售商履行企业社会责任的利益损失,因此,制造商质量努力与零售商企业社会责任相结合是可以改善再造品销售难问题的有效对策。     

团购网站消费行为模式的信息经济分析

团购网站Groupon是在web2.0环境下产生出来的一种新兴电子商务模式,发展进程具有跳跃式增长的特点,其具有羊群效应、长尾理论、网络外部性等显著的信息经济学特性。从信息经济学的角度来分析,网络团购交易过程本身就是一种博弈,团购网站消费行为模式体现了重复博弈的特性,商家、网站、用户三方之间也存在着信息不对称的情况。通过网络团购的价格离散,可以实现市场的分离均衡,优化市场效率,提高市场容量。     

Probability of error in CPSK systems with intersymbol interference and additive noise

A simple lower bound, an upper bound and a simple approximation to the upper bound on the probability of error for coherent phase-shift-keyed (CPSK) systems operating in the presence of intersymbol interference and additive noise are obtained. The additive noises in the in-phase channel and the quadrature channel are assumed to be independent, and are independent of the signal, but not restricted to be Gaussian. The approximation to the upper bound is four times the lower bound, hence the tightness of these bounds is uniform for all cases. This fact and the simplicity of the bounds make these bounds a useful system design tool. Numerical examples for quaternary and octonary systems are presented and compared to known results.     

Matrix solution bounds of the continuous Lyapunov equation by using a bilinear transformation

By using a bilinear transformation and some linear algebraic techniques, new matrix bounds of the solution of the continuous algebraic Lyapunov equation (CALE) are derived in this paper. Comparing to existing works, these obtained matrix bounds are less restrictive and are easy to be calculated. A numerical example is also given to demonstrate the merits of the present results.     

Dual-hop relaying communications over generalized-K (KG) fading channels

In this paper, a study on the end-to-end performance of dual-hop non-regenerative relaying over independent generalized-K (KG) fading channels is presented. Using a suitable upper bound for the end-to-end signal-to-noise ratio (SNR), novel closed-form expressions for the cumulative distribution function (CDF), probability density function (PDF) and the moments of this bounded SNR are derived. These results can be afterwards used to obtain important performance metrics of the considered system such as the outage probability and the error performance of digital modulation schemes. In the case of independent but non-necessarily identical fading channels, lower bounds for the average bit error probability (ABEP) for different modulation schemes are determined by using the Padé approximants method. For the case of identical fading channels, closed-form lower bounds for the ABEP are derived. Various numerical and computer simulation results illustrate the proposed analysis.     

基于供应链保兑仓融资的企业风险收益合约研究

作为典型的供应链融资服务保兑仓融资业务,可以使参与企业获得很好的收益。企业努力水平的高低以及信用程度的大小决定保兑仓业务的收益状态,如果使合约企业在保兑仓业务中共赢,必须以参与企业一定的努力水平和信用程度作为先决条件。结果表明,企业努力水平和信用程度与企业收益幅度之间存在密切的关系,不同的努力水平和信用程度将会导致企业不同的收益落差,直接影响企业的收益水平。     

气候风险下考虑政府补贴的订单农业契约设计

针对单一农户和公司组成的"公司+农户"型订单农业供应链,构建不利气候和努力水平共同影响农产品产出的随机收益模型,并在此基础上引入政府补贴因子.对比分析集中和分散决策下农户和公司的最优决策行为,设计一种与气候指数、努力水平和收购价格相关的风险分担+转移支付的协调策略.仿真分析表明:不利气候降低农户的努力水平;合理的政府补贴因子能有效地提高农户努力水平和供应链成员收益;在公司所设计的风险分担机制与转移支付满足一定的条件下,可实现订单农业供应链协调.     

Examining the Influence of Emotional Expressions in Online Consumer Reviews on Perceived Helpfulness

Drawing on the cognitive appraisal theory of emotions and the attribution theory, this study extends existing research by examining how the emotional expressions influence perceived helpfulness of online consumer reviews (OCRs). We include two negative emotions (anger, fear) and two positive emotions (pride, surprise). Each of these four emotions can be described with respect to six emotional appraisal dimensions which containing certainty, pleasantness, attentional activity, anticipated effort, control and others’ responsibility. Hypotheses thus developed were empirically validated using the laboratory experiment in the context of restaurant services. Research results indicated that emotion expressions in OCRs have an indirect effect on perceived helpfulness through attribution about the reviewer's cognitive effort. We find that reviews with negative emotions are perceived to be more reviewer's cognitive efforts than positive emotions. More specifically, OCRs with negative emotions tend to comprise more diagnostic features related the product or service, and are more informative. We further examined whether the gender of reader moderates the relationship between different emotional expressions and perceived reviewer's cognitive effort. The results find that reviews conveying positive emotions tended to have a greater impact on male readers’ perception of reviewer's cognitive effort than those of female readers. Reviews conveying negative emotions were found to have a greater impact on female readers’ perception of reviewer's cognitive effort than that of male readers. The study results add to existing knowledge of the influence of emotional expression on perceived helpfulness, which will advance our understanding of information processing in the psychological mechanisms influencing the attitude. Applying the results from this study, restaurant service providers can make different coping strategy for discrete emotions and platform administrators can assistant reviewer express their emotions more precisely.     

Document ranking for variable bit-block compression signatures

Variable bit-block compression (VBC) signature is extended for document ranking. Two different extensions were experimented: the weighted VBC (WVBC) scheme and the aggregate VBC (AVBC) scheme. For both, analytical bounds of the additional storage for the term frequencies were derived. The upper and lower bounds of WVBC signatures were better than the corresponding bounds for AVBC signatures. In general, these bounds are functions of the word size (in bits) of the term frequencies. Therefore, term frequencies were scaled to reduce the word size. Experiments showed that the additional storage cost is closer to the lower than the upper bound for both WVBC and AVBC signatures. In addition, WVBC signatures were better than AVBC signatures in terms of storage and retrieval speed. Logarithmic scaling was found to be significantly better than linear scaling, in measuring the agreement of document ranking against the case without scaling, using the Kendall rank-order correlation. If a 75% ranking performance is acceptable, then the additional storage of the term frequencies is only 3.4% of all the indexed documents.