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Under a Just-In-Time (JIT) pull system the sequencing of products requires the satisfaction of two main goals: (1) keeping a constant rate of usage of parts, and (2) smoothing the workload at work stations to avoid line stoppages. By using a practical observation related to JIT delivery systems we propose a two-step approach, where in the first step we consider only goal (1) by applying a benchmark heuristic. In the second step we focus on goal (2), by investigating the effectiveness of a spacing-constraint based approach, commonly used in the automotive industry, in comparison with a more general time-based one. We designed and conducted a simulation experiment based on the practical situation of final assembly lines and we found that the benchmark heuristic represents an appropriate choice for step one (based on a new performance measure that represents a lower bound on variation in parts utilization). For the second step, related to workload smoothing, the spacing-constraint based method presents bette...

The sequencing of products for final assembly in JIT mixed-model manufacturing systems is sometimes based on multiple criteria. The two main criteria that have been discussed in the literature are: the smoothing of parts utilization and the smoothing of the product load. Product rate variation smoothing and sub-assembly load variation smoothing may also be considered. One procedure for treating these multiple criteria is by the use of a weighted multi-attribute cost function, which is an aggregation of the respective objective functions. However, one difficulty which may be associated with this approach is in obtaining proper estimates for the weights. In this paper, we propose an alternative approach (a parametric procedure), which utilizes only the relative preference information for the criteria. A numerical example is presented to illustrate the procedure.

Toyota's goal-chasing method has proved effective for dealing with practical-sized sequencing problems for mixed-model assembly lines in just-in-time (JIT) production systems. Miltenburg introduced the multi-level concept to JIT assembly line sequencing, and his remark about Toyota's neglect of product ‘usage’ smoothing (PUS) when determining the assembly-line product sequence, primarily gave impetus to this study. We note that for most JIT systems, PUS would only be of practical significance, if it helps to achieve sub-assemblies and parts usage smoothing (SUS). In this paper, we conduct a simulation experiment for two-level sequence scheduling for JIT assembly lines. Using the SUS objective value as the metric, the results show that in a comparatively higher percentage of cases (relative to single-level SUS objective scheduling), which can be reasonably considered as statistically significant, better sequences are produced, This phenomenon is found to apply to Toyota's SUS objective as well as Miltenburg's.

In Brown Norway to Lewis rat lung transplantation, short-term administration of cyclosporine produces permanent adoption of allografts; however, the adopted grafts show symptoms of chronic rejection. To clarify the difference in cytokine production in acute an chronic rejection of the allografts, an immunohistochemical study was performed. In acute rejection, positive cells for respective cytokines were observed in infiltrating cells, increasing in number as the days after transplantation passed, and reaching a maximum on the fifth day. The strongest reactivity was observed perivenously. In chronic rejection, TNF-alpha positive cells were observed in the perivascular and peribronchial regions, especially around class II positive epithelia. The number of positive cells was, however, less than that in the vascular phase of acute rejection. Few cells were positive for IL-1 beta, IFN-gamma and, unexpectedly, for IL-4. These facts indicate the functional difference of infiltrating cells between acute and chronic rejection.

This paper proposes the matrix extension of Rouche's theorem to investigate the location of zeros of polynomial matrices. The theorem is then applied to the Levinson-Wiggins-Robinson (LWR) algorithm in order to enumerate the zeros of a polynomial matrix at each step of the recursion and test the stability of fitted multivariate autoregressions. Extensive use is made of some important algebraic relations in the LWR algorithm, which are derived from the properties of symmetrizable matrices. In this paper, only a finite sequence of sample correlation matrices computed from obsereed data over a finite time interval is assumed to be given and, therefore, the spectral density matrix defined by its Fourier transform is not necessarily nonnegative definite.

In this paper, we present a fast algorithm for fitting ARX models and determining their orders from the covariance and cross-covariance information of input and output processes. Ascending and descending order-update recurrences will be presented first for fitting an ARX model. These recurrences will be applied to the order determination of ARX models based on Akaike's information criterion. This algorithm reduces the computation required for fitting an ARX model (m, n) and its associated order determination to a number of operations proportional to 0[ (m + n)2], compared to the usual Cholesky decomposition method which requires a number of operations proportional to 0[(m + n)4]. Some numerical examples, as well as the Pascal source programs, are presented to illustrate the efficiency of this algorithm.

The most important problem during FBS examination in infants is respiratory care. A new ventilation method using the channel of the FBS is proposed for respiratory care during FBS examination in infants. An FBS with a channel of more than 1.2 mm in diameter was directly inserted into the trachea under general anaesthesia without an orotracheal tube. The first step of this ventilation is the flushing of pure O2 into the lung as inspiration through the channel of the FBS. The second step is the aspiration of expiratory gas through the channel by a vacuum pump. Ventilation during the FBS examination is maintained by the repetition of these two steps by the operation of a stop-cock. Experiments in dogs, and clinical use showed that this method of respiratory care is effective and safe with certain limitations. Clinically, inspection with the FBS could be performed continuously for five minutes in most cases.