从原初性的外在符合到模拟性的主体反思——现代性文本学与后现代性文本学的差异

对于现代性文本学而言,文本虽然获得了一定的独立性和开放性,但仍然处于一种既定的现成状态。文本背后始终假定原初意义的确定存在,思想的生产机制仍旧局限在非生产性的封闭结构中,以再现对某种原初性目的论的符合。在后现代性文本学的视域中,文本的既成性与意义的原初性,经由复合性和生产性的发生逻辑,被动态化为一种能指意指的生产过程。思想构境论充分结合了主体的生产性反思与特定历史情境的多元编织。它在去中心的、开放的思想生产过程中,颠覆和超越了真理原像的恒久秩序,并把思想的生成当作主体当下所建构的对文本＂原初语境＂的拟现,从而指向一种后文本学的主体反思。     

The Impact of Forecast Errors on Early Order Commitment in a Supply Chain*

Supply chain partnership involves mutual commitments among participating firms. One example is early order commitment, wherein a retailer commits to purchase a fixed‐order quantity and delivery time from a supplier before the real need takes place. This paper explores the value of practicing early order commitment in the supply chain. We investigate the complex interactions between early order commitment and forecast errors by simulating a supply chain with one capacitated supplier and multiple retailers under demand uncertainty. We found that practicing early order commitment can generate significant savings in the supply chain, but the benefits are only valid within a range of order commitment periods. Different components of forecast errors have different cost implications to the supplier and the retailers. The presence of trend in the demand increases the total supply chain cost, but makes early order commitment more appealing. The more retailers sharing the same supplier, the more valuable for the supply chain to practice early order commitment. Except in cases where little capacity cushion is available, our findings are relatively consistent in the environments where cost structure, number of retailers, capacity utilization, and capacity policy are varied.     

Replanning the Master Production Schedule for a Capacity-Constrained Job Shop

This research examines the use of both frozen and replanning intervals for planning the master production schedule (MPS) for a capacity-constrained job shop. The results show that forecast error, demand lumpiness, setup time, planned lead time, and order size have a greater impact on the mean total backlog, total inventory, and number of setups than the frozen and replanning intervals. The study also shows that a repetitive lot dispatching rule reduces the importance of lot sizing, and a combination of repetitive lot dispatching rule and single-period order size consistently produces the lowest mean total backlog and total inventory. The results also indicate that rescheduling the open orders every period produces a lower mean total backlog and total inventory when the forecast errors are large relative to the order sizes. This result suggests that the due date of an open order should be updated only when a significant portion of the order is actually needed on the new due date.     

Decision Making with Uncertain Judgments: A Stochastic Formulation of the Analytic Hierarchy Process*

In the analytic hierarchy process (AHP), priorities are derived via a deterministic method, the eigenvalue decomposition. However, judgments may be subject to error. A stochastic characterization of the pairwise comparison judgment task is provided and statistical models are introduced for deriving the underlying priorities. Specifically, a weighted hierarchical multinomial logit model is used to obtain the priorities. Inference is then conducted from the Bayesian viewpoint using Markov chain Monte Carlo methods. The stochastic methods are found to give results that are congruent with those of the eigenvector method in matrices of different sizes and different levels of inconsistency. Moreover, inferential statements can be made about the priorities when the stochastic approach is adopted, and these statements may be of considerable value to a decision maker. The methods described are fully compatible with judgments from the standard version of AHP and can be used to construct a stochastic formulation of it.     

论理论与实在的关系

以牛顿力学为核心的近代自然科学研究的哲学基础预设了经典理论与实在之间的镜像关系.这种关系蕴含了两个基本假设:其一,科学理论的可靠性与实在性假设;其二,科学方法与科学仪器的有效性与客观性假设.这种观点曾受到马赫、彭加勒和迪昂等人的质疑,却得到了罗素和维特根斯坦的逻辑原子主义的支持.相对论力学进一步强化了这种关系.量子力学的产生对此提出的挑战是颠覆性的和空前的.量子理论是依赖于测量条件的理论,它与实在之间的关系是一种整体性的模拟关系.模拟的过程是主客观统一的不断相互作用的过程.在这个过程中,理论不再是对实在的直接描述,而是在特定的模型框架内谈论实在或理解实在.谈论实在是在特定条件下对实在的认知内容的表达,对实在机理的间接模拟,不是对实在本身的直接断言,也不是对实在行为变化的镜像表达.这种观点不需要我们放弃长期以来形成的科学有可能使我们认识实在的直觉与追求,而是承认,科学认知过程中存在的辩护等修辞因素也是对科学真理的探索、辩明与阐释.这是一种介于僵化的经典实在论与多元的相对主义视野之间的一种中间领域的语境认识论.     

随机效应空间滞后单指数面板模型

对随机效应空间滞后单指数面板模型,本文构建了该模型的截面极大似然估计方法,从理论证明和数值模拟两方面分别考察了其估计量的大样本性质和小样本表现。研究结果表明:(1)在大样本条件下,估计量均具有一致性,并且参数估计量具有渐近正态性。(2)在小样本条件下,各估计量依然具有良好的表现,其精度随着样本容量的增加而提高;空间权重矩阵结构的复杂性对空间相关系数的估计量影响较大,但对其他估计量的影响较小。     

LSTAR-GARCH模型的单位根检验

LSTAR模型的单位根检验往往易忽视其条件方差的时变性,实际上,对许多经济变量尤其是金融变量建立LSTAR模型后,经常发现其条件方差存在GARCH效应。针对LSTAR-GARCH模型的平稳性检验,本文构建了检验统计量tNG,之后在极大似然估计的基础上,推导出tNG的渐近分布,通过蒙特卡洛模拟方法得到该统计量的渐近临界值,并在此基础上研究了tNG检验的检验功效。在与刘雪燕和张晓峒(2009)提出的tNL检验、Ling等(2003)提出的tLG检验以及DF单位根检验进行比较后,发现tNG检验具备明显优势。     

Forecasting with serially correlated regression models

In this article we investigate the asymptotic and finite-sample properties of predictors of regression models with autocorrelated errors. We prove new theorems associated with the predictive efficiency of generalized least squares (GLS) and incorrectly structured GLS predictors. We also establish the form associated with their predictive mean squared errors as well as the magnitude of these errors relative to each other and to those generated from the ordinary least squares (OLS) predictor. A large simulation study is used to evaluate the finite-sample performance of forecasts generated from models using different corrections for the serial correlation.     

Variance reduction through negative correlation,a simulation study

A new method for reducing the variance in simalation experiments is presented and evaluated. The method can be regarded as an extension of the antithetic variates principle. We create negative correlation within all pairs of random number while the original mcihod creates correlation only within some pairs. Our method is compared to ihe antithetic variates and crude Monte-Carlo techniques by repeated simulations. The results obtained are ail in favour of our method.