The impact of random machine unavailability on inventory policies in a continuous improvement environment

There are production situations where a production facility (e.g. a machine) is used intermittently to produce lot sizes of certain products. Upon completion of production run, the facility may not be available for a random amount of time due to several reasons, such as: the facility needs to be maintained and the maintenance time is random due to unforeseen circumstances; or that the facility is leased by different manufacturers and the demand for the facility is random. As a result of machine unavailability, stock-out situations might arise. This paper extends the work of Abboud et al . (2000, Computers and Operations Research , 27 , 335-351) by assuming learning and forgetting in production. A new mathematical model is developed with numerical examples and sensitivity analysis provided. Furthermore, this paper determines how the overall inventory cost is influenced by the nature of the random variable that represents the unavailability time of the production facility.     

The effects of learning and forgetting on the optimal lot size quantity of intermittent production runs

This paper studies the effects of learning and forgetting on the production lot size problem with infinite and finite planning horizons. It is assumed that the determination of the economic manufactured quantity (EMQ) in the succeeding production run is dependent on: (1) the maximum inventory accumulated prior to interruption; (2) the length of the interruption period which incurs total forgetting; and (3) the level of experience in equivalent units remembered at the start-up of the next production run. The optimum operating inventory doctrines is obtained by trading off procurement cost per unit time and the inventory carrying cost per unit time, so that their sum will be a minimum. A numerical example is presented to demonstrate the application of learning and forgetting to the determination of the EMQ.     

重视再现规律 提高教学质量

识记、遗忘、再现三个基本环节中,再现是记忆过程中最积极、最有决定意义的。再现具有规律性。优化课堂教学是形成再现的基础,科学组织复习是加速再现的前提,巧妙运用联想是激发再现的媒介。     

《长恨歌》文体异说

几十年前,陈寅恪先生以他文史大家的卓识,提出“唐代贞元元和间之小说,乃一种新文体……元稹李绅撰莺莺传及歌于贞元时,白居易与陈鸿撰长恨歌及传于元和时……实为贞元元和间新兴之文体”的新说,并准确地指出《长恨歌》为“言情小说文体”的诗歌部分。其实就《长恨歌》与《长恨歌传》这两部具体作品而言,两者都是小说,一用诗体,一用传体,《长恨歌》就是诗体小说。     

Discrete time-varying demand lot-sizing models with learning and forgetting effects

This paper deals with the problem of incorporating both learning and forgetting effects into discrete timevarying demand lot-sizing models to determine lot sizes. Forgetting is retrogression in learning which causes a loss of labour productivity due to breaks between intermittent production runs. Formulae are derived for calculating the production cost required to produce the first unit of each successive lot over a finite planning horizon. An optimal lotsizing model and three heuristic models are developed by extending the existing models without learning and forgetting considerations. Numerical examples and computational experience indicate that larger lot sizes are needed when the phenomenon of learning and forgetting exists. Several important conclusions are drawn from a comparison of the three heuristic solutions with the optimal solution, and suggestions for future research and for lot-size users to choose an appropriate lot-sizing technique are made.     

Partner Naming and Forgetting: Recall of Network Members

Network researchers must contend with recall, forgetting, alters whose names are not known, and other potential biases in estimating the size of personal (ego) networks. We use data from a longitudinal study of sexual and drug use ego networks. Results show 6% forgetting for 30-day sex partners, 18% for drug use partners, and 26% for close friends. Forgetting is decreased by behavioral specificity and salience. Forgetting increases with network size and time frame. In the domain of sex relationships, global estimates of network size, at least over a period of 30 days, are equivalent to estimates from partner naming 92% of the time if anonymous partners are accounted for.     

情景猜测与词表背诵词汇学习方法效果之对比研究

通过词汇测试练习,运用定量分析的方法,对比研究了情景猜测法与词表背诵法这两种词汇学习方法在词汇的认知和产出两个方面的相对效果,并且探讨了被试者的遗忘模式.T检验结果表明,词表背诵法在词汇认知方面效果比情景猜测法好,而在词汇的产出方面情景猜测法效果更好.同时,两组被试者遗忘的比例在第一次测试后最大,之后趋缓.     

困苦与解脱：《庄子》语言的言说方式

在语言的言说方式上,庄子可以算得上是第一次进行了全方位的关照。他不但对语障言筌进行了集中论述,而且探索了语言言说的最佳方式——“三言”,并对其理想的终极目标——“忘言”也进行了详细阐述。庄子的语言,摆脱了言说的障碍,真正实现了言说的绝对自由。     

集体遗忘：满语衰微原因探析

有清一代,满语在清朝历代统治者不断发出“国语骑射”的强调信号中,却经历了由盛至衰的转变,这是一个值得深思的问题。而细究其中的原因,笔者以为正是清朝当政者为巩固和加强其统治而施行的一系列政策措施。导致了满族由上至下的对满语的渐变式的全民集体遗忘,而这恰恰是满语衰微的主要原因之一。     

重道轻文观念之变与文的自觉

孔子在探讨具体事实和道理时要求言意协调,对于本体道———"天道"则流露出"言不尽意"的倾向。老子以本体道———根本道理来反思各种具体道,要求超越具体的"言"。韩非、墨子重视具体道而轻视言和文,庄子领悟老子的本体道而提倡忘言。汉代学者将孔老之道作了认识论和实践论方面的具体解释,重道轻文,重意轻言。何晏以"无"消解了政治伦理之道,强调"道"的不可言说;王弼以无为用,既用本体道来反思具体道,又由具体道去领悟本体道,形成道文同一、言意兼重的观念,消除了圣人和一般人、经典和一般著述之间的界限,不仅促进了文的自觉,也促进了人的自觉。