考虑估值不确定和搜索成本的预售决策研究

研究了预售环境下,存在消费者估值不确定和消费者搜索成本时,销售商的最优定价和配给决策.建立一个两阶段模型,考虑一个销售商出售单一新产品给若干具有战略行为的消费者,消费者根据自身效用最大化原则选择最佳购买时机,销售商则考虑消费者的战略行为,决策最优的两期价格和预售期配给量.研究结果表明,预售期的配给量取决于单位产品的采购成本.当且仅当单位产品的采购成本介于特定范围内时,销售商应采用预售策略,此时折扣预售策略总是销售商的最佳选择.否则销售商应采用正常销售策略.研究还表明,当消费者的风险成本系数较低时,消费者的搜索成本越高,销售商的预售价格和总利润越低.否则,消费者的搜索成本越高,销售商的预售价格和总利润越高.     

Coordinating pricing and inventory decisions in a bounded production system with uncertain yield

Most inventory researches assume that production level can fluctuate arbitrarily. However, large fluctuation of the production level in many firms may be much costly. This paper addresses the coordinating pricing and inventory control problem in a bounded production system with uncertain yield, in which the production level is constrained between a maximum and minimum level in each period and the price can be adjusted dynamically. We show that the optimal policy is the interval base-stock-list-price policy. Also, we study the impact of the production bounds and uncertainty of the yield on the production system. Numerical experiments are also performed to study the impact of parameters on the system.     

管材相贯接头焊材用量的参数化计算

针对导管架建造过程中存在大量管件相贯的焊接作业,对管件相贯焊材用量的计算进行了研究.在建立两管相贯线焊接坡口数学模型的基础上,用积分法在被切管的轴剖面上计算焊缝的截面在其相邻小角度内的焊缝体积,再在整个支管圆周内根据两面角选择不同的两面角模型分段积分求解总的焊材填充体积.对多管搭接类型先应用相贯线方程求出支管与各管相贯的角度区间,再按两管相贯方法进行计算.在此基础上结合其他一些常用的焊接接头类型开发了焊材计算软件,说明了软件使用方法,并对软件进行了测试计算.结果表明,该方法能够显著提高焊材用量计算的效率和精度,计算误差控制在3%以内.     

AN SQP METHOD BASED ON SMOOTHING PENALTY FUNCTION FOR NONLINEAR OPTIMIZATION WITH INEQUALITY CONSTRAINT

1 IntroductionIn tabs paper, we consider the following nonlinear optbostion problem:where j: Re - R, g: Re - Re are continuously ~ntiable functinns. SoP method forproblem (1) generates a sequence of points which converges to a K--T point of problem (1)through the following iterate formulaxk 1 = x* adds (2)adhere da is the solution of the following quadratic Prograrxuning problemin which Bh is a sylnlnetric positive deflate lllatris and A* is a stepsise obtained by some lineseaxch to redu…     

An Approximation of the Customer Waiting Time for Online Restaurants Owning Delivery System

Online restaurants, which receive online orders and deliver food directly to the customer's residence, are becoming increasingly popular. To be successful, online restaurants need to provide reliable and prompt deliveries. Careful design of the meal preparation and order delivery systems is needed to avoid excessive customer waiting time between ordering and delivery. This paper considers the meal preparation and delivery processes simultaneously to approximate average customer waiting time for deliveries. The authors first discuss the system performance with one cook and unit-capacity delivery vehicles, using an M/G/1 queue and a GI/G/1 queue. Numerical experiments show that our approximation can adequately describe real waiting times. Then, series queues with multiple cooks and multi-capacity delivery vehicles, e.g., an M/G/n queue and a GI/G~n/1 queue, are examined.Results show that except for situations with a large meal preparation time and a small vehicle capacity,compared with the result of simulation, the approximation in this paper is acceptable with a deviation of less than 20%. The marginal decrease in waiting time associated with hiring more vehicles is estimated under different meal preparation speeds, sizes of service area and vehicle capacities.     

基因算法的应用及改进

基因算法是基于自然选择和自然基因机制的模型参数优化估计的通用数值方法,具有许多优点。它的主要缺点是,模型参数初始变化区间的大小对寻优效果有显著影响。文中改进了基因算法,并对具有寻优特性及其在水文建模中的应用进行了初步研究。     

A ROBUST SQP METHOD BASED ON A SMOOTHING APPROXIMATE PENALTY FUNCTION FOR INEQUALITY CONSTRAINED OPTIMIZATION

1 IntroductionConsider the following inequality constrained optiInization problem:Inin f(x)xeRn(1)s.t. g(x) 5 0where f: R1'-R, g: R"-Rm are cofltinuousIy differentiable functions.SQP method for soIving problem(1) is to gellerate a sequence {xk} converging…     

A multi-period pricing and inventory control model

<正> The authors analyze a finite horizon,single product,period review model in which pricingand inventory decisions are made simultaneously.Demands in different periods are random variablesthat are independent of each other and their distributions depend on the product price.Pricing andordering decisions are made at the beginning of each period and all shortage are backlogged.Orderingcost is a convex function of the amount ordered.The objective is to find an inventory and pricing policymaximizing expected discounted profit over the finite horizon.The authors characterize the structure ofthe optimal combined pricing and inventory strategy for this model.Moreover,the authors demonstratehow the profit-to-go function,order up to level,reorder point and optimal price change with respectto state and time.     

间歇注气抽采煤层气井注气量与采收率分析研究

水力压裂煤层、注气提高煤层气采收率等生产工艺过程中,煤层中流体的运动是多相多组分流体的扩散渗流。假定煤层为孔隙裂隙二重介质,孔隙中只存在吸附状态气相,裂隙是气、水共存空间,孔隙与裂隙之间气体的交换量是渗流场中的质量源。试验研究了质量源与时间和煤层结构的关系,测定了吸附置换速率的衰减系数。应用多孔介质中扩散渗流理论,再运用质量连续方程,导出了多相多组分流体的扩散渗流微分方程。忽略占煤层中气体总量百分比很小的游离状态气体在微分方程中随时间变化,从而求出了单井间歇注气抽采煤层气井在注气过程注气量的近似表达式。分析解表明注入气体流量与注入气体压力和煤层气初始压力之差、竞争吸附置换速率成正比;煤层渗透率越大、煤层气和注入气体的混合粘性越小,吸附竞争置换速率越小和注气抽采煤层气效果越差;注气抽采煤层气工艺适合低透气性煤层。     

Which Inspection Approach Is Better to Prevent Drug Fraud: Announced or Unannounced?

In recent years, there are many crimes related drug fraud occuring in China and many experts think that the main cause is that China Food and Drug Administration (CFDA) adopts announced inspection (AI). In order to circumvent this difficulty, CFDA has exploited unannounced inspection (UI) since 2014. In this paper, the authors study the problem of which one performs better, AI or UI. Specifically, the authors consider a supervisor, which decides the inspection approach, inspection strength and punishment to force the firm to put self-inspection effort to meet the requirements of Good Manufacturing Practice, and a firm, which produces a drug and decides its self-inspection effort. The authors use game theory to model this problem, characterize the equilibrium policies under AI, and compare the effects of the two approaches on preventing drug fraud under complete and incomplete information. The results show that under the complete information, UI performs better if the firm’s technical level and the inspection cost are low and AI performs better otherwise. When the supervisor doesn’t know the firm’s technical level, if the low technical level is high, AI performs better. Otherwise, UI performs better if the inspection cost is low and AI performs better if the inspection cost is high.