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941.
DEWIP is a manufacturing control system for job shop environments aiming at achieving short and reliable lead times by establishing WIP control loops between the manufacturing work centres. The paper describes the mode of function, the setting of parameters and simulation results of the new manufacturing control system. The setting of parameters is done with the aid of the funnel model and the theory of logistic operating curves, both developed at the Institute of Production Systems at the University of Hanover. The simulation is conducted using industrial data and makes it possible to assess DEWIP with regard to lead times, WIP level, performance and schedule reliability. DEWIP is compared both with an uncontrolled process and with the manufacturing control systems Load oriented order release (LOOR), Conwip and Polca. The results suggest that DEWIP and the models employed for the setting of parameters are suitable for job shop production and therefore offer a valuable alternative to prevailing centralized manufacturing control systems. 相似文献
942.
The stage gate model has been proposed for application to uncertain technology development. Reports on industrial experience from such implementations are quite limited, however. This led us to explore in six companies what adaptations have been made to facilitate the model's usefulness for technology development and the companies’ experiences from their practical application of the model. Our results indicate that aspects proven important for the operational success, or failure, of the model include the level of adaptation to the characteristics of technology development and a more flexible use than that normally found in product development. 相似文献
943.
In this paper the robustness of Brass's child-survivorship indirect mortality estimation technique is investigated. An analytical method is developed for studying the error or bias caused in indirect mortality estimates by poor data, badly chosen model functions, and specific demographic assumptions that are often violated in practice. The resulting analytical expressions give insight into the rationale of indirect methods, the conditions under which they are robust, and the magnitude of errors that occur when specific assumptions are violated. 相似文献
944.
What is the relationship between well-being and satisfaction of basic psychological needs overtime? The basic psychological needs theory is a subtheory of the self-determination theory that elaborates the concept of psychological needs and its relations to psychological health and well-being. The goals of this research was to establish the causal ordering between basic psychological needs and three psychological well-being indicators (subjective well-being, self-esteem and satisfaction with life), in a longitudinal study. We used a cross-lagged two-wave design. A total of 272 university students completed the questionnaire at the beginning and at the end of the semester. Relatedness at time 1 (T1) had a positive and significant effect on all well-being indicators at time 2 (T2); competence (T1) had a positive and significant effect on all indicators except for self-esteem (T2); finally, autonomy (T1) did not have a significant effect on any of the well-being indicators (T2). In conclusion, we confirm the causal ordering of competence and relatedness on well-being, according to the basic psychological needs subtheory. Universities, in general, and teachers, in particular, should promote relations between students and support the need of competence. 相似文献
945.
Abstract In 1980, thirty‐five years after the end of World War II, the long‐term impact of war‐trauma on individuals’ lives led to concern about Post‐Traumatic Stress Disorder. While the focus here is not on “disorders,” it is on interactive patterns of “defensive” caretaking behaviors which contribute to intergenerational transmission of anxiety, silence and losses related to the Holocaust. In this long‐term group, defensive caretaking patterns are conceptualized as second‐generation behaviors which focus on parental needs thereby avoiding addressing second‐generation vulnerabilities. Relevant concepts of Sullivan, Winnicott, Bion and Fairbairn are applied. In an innovative trauma group design, defensive caretaking patterns are illustrated through clinical examples and interventions by the therapist as a “validating object” work to mitigate transmission to still the next generation. 相似文献
946.
This paper examines the impact of immigrant status on home ownership in Australia. It shows that the rate of home ownership for most groups of immigrants is comparable to that of the Australian born. As expected, recently arrived immigrants have relatively low probabilities of owning their own home. These results hold for both analyses pooled across movers and non‐movers, and for analyses restricted to those, both immigrants and the native born, who moved residence in the previous five years. A decomposition of the estimated coefficients of the model of tenure choice is developed. This is shown to enhance understanding of variations in rates of home ownership across birthplace groups. 相似文献
947.
948.
We propose a hidden Markov model for longitudinal count data where sources of unobserved heterogeneity arise, making data
overdispersed. The observed process, conditionally on the hidden states, is assumed to follow an inhomogeneous Poisson kernel,
where the unobserved heterogeneity is modeled in a generalized linear model (GLM) framework by adding individual-specific
random effects in the link function.
Due to the complexity of the likelihood within the GLM framework, model parameters may be estimated by numerical maximization
of the log-likelihood function or by simulation methods; we propose a more flexible approach based on the Expectation Maximization
(EM) algorithm. Parameter estimation is carried out using a non-parametric maximum likelihood (NPML) approach in a finite
mixture context. Simulation results and two empirical examples are provided. 相似文献
949.
W. B. Morley 《Long Range Planning》1986,19(6):124-129
This article describes the series of changes which British Telecom has gone through over the last 10 years or so— changes which have often been dramatic and highly publicized. Faced with the challenges of the fast-changing business environment of the past decade—the most obvious of which was the technological revolution—British Telecom was perceived to be safe and reliable, but slow to change and expensive. Its strengths were the widespread understanding and acceptance of the need for change, its reservoir of the necessary skills and talent, a sound commercial infrastructure and a corporate culture. The author describes the organizational changes which have taken place and looks to a future where change is endemic if a business is to survive. 相似文献
950.
R W Hart S C Freni D W Gaylor J R Gillette L K Lowry J M Ward E K Weisburger P Lepore A Turturro 《Risk analysis》1986,6(2):117-154
The Color Additives Scientific Review Panel considered whether there was information sufficient to perform a carcinogenic risk assessment on the colors D&C Red No. 19 (R-19), D&C Red No. 37 (R-37), D&C Orange No. 17 (O-17), D&C Red No. 9 (R-9), D&C Red No. 8 (R-8) and FD&C Red No. 3 (R-3) and to evaluate the assessments sent to FDA as part of the petitions for use of the colors for drug and external uses by the Cosmetic, Toiletry and Fragrance Association (CTFA). There is a lack of human data concerning the colors for making a human health assessment, so the assessments are based upon the extrapolation of animal data. The risk assessments are determined for exposure to single chemicals. Excluded from consideration are possible effects from exposure to multiple chemicals, such as co-carcinogenesis, promotion, synergism, antagonism, etc. In the light of recent efforts in establishing a consensus in risk assessment, the Panel has determined that the CTFA assessments for R-10, O-17, and R-9 are consistent with present acceptable usages, although it questions some of the assumptions used in the assessments. The Panel identified a number of general assumptions made, and discusses their validity, their impact on total uncertainty, and the potential options to address the gaps in understanding that necessitate the assumption. The Panel also derived revised risk estimates using more "reasonable" assumptions than "worst-case" situations, for 90th percentile and average exposure. For those assumptions that are easily quantifiable, the Panel's estimates are less than an order of magnitude lower than the CTFA risk estimates, indicating that the underestimates and overestimates of the CTFA risk estimates tend to balance each other. The impact of most of the assumptions is not quantifiable. The assessment for R-3 is complicated by the fact that there is no good skin penetrance study for this color. It was assumed that the penetrance is similar to that of another water-soluble xanthene color, R-19. It is expected that the absorption of the color is not likely to exceed that of the smaller molecule, R-19. Therefore, the risk estimates are similar to the CTFA estimates, but with different reasoning. The estimates for R-8 and R-37 are different from the others in that there is a lack of any exposure or toxicological information on these colors.(ABSTRACT TRUNCATED AT 400 WORDS) 相似文献