Search results

IN order to obtain machines of large carrying capacity, there is a tendency to increase the number of power units, and it is of great interest to consider the effect of this policy upon safety in flight. It is obvious that, if all the power units are of the same construction, the possibility of failure of one engine in a machine fitted with two engines is twice that in a machine fitted with one engine, so that in general the probability of one unit going out of action in a multi‐engined machine is proportional to the number of power units employed. In the case of a single‐engined machine horizontal flight cannot be maintained after the engine fails, and unless the failure occurs in the vicinity of a safe landing ground disaster may result. In the case of a multi‐engined machine, however, if level flight can be maintained on the power obtainable from the remaining units, it may bo possible to arrive at a safe landing ground without further trouble. The question, therefore, arises as to which factor is the more important, the increase in the probability of failure, or the ability to fly level with an engine out of action.

The purpose of this study is to propose and model an integrated production‐maintenance strategy for a failure‐prone machine in a just‐in‐time context.

The proposed integrated policy is defined and a simulation model is developed to investigate it.

The paper focuses on finding simultaneously two decision variables: the period (T) at which preventive maintenance actions have to be performed; and the sequence of jobs (S). These values minimize the maintenance costs (M_C) and the expected total earliness and tardiness costs (ET_C) away from a common due‐date D.

The paper attempts to integrate in a single model the two main aspects of any manufacturing and production systems: production and maintenance. It focuses on a stochastic scheduling problem in which n immediately available jobs are to be scheduled jointly with the preventive maintenance. The effect of the period (T) and the sequence of job (S) on the expected total cost are shown through a numerical example.

The paper proposes an integrated model that links production, preventive maintenance and corrective maintenance. It is simultaneously focusing on the period (T) at which preventive maintenance actions have to be performed and the sequence of jobs (S) to reduce production and maintenance‐related costs.

The purpose of this paper is to consider various possible constraints of the problem of production and maintenance planning control for a multi-machine under subcontracting constraint, in order to bring the manufacturer industry closer to real mode. In this paper, we present an efficient and feasible optimal solution, by comparing optimization procedures.

Our manufacturing system is composed of parallel machines producing a single product, to satisfy a random demand under a given service level. In fact, the demand is greater than the total capacity of the set of machines; hence there rises a necessity of subcontracting to complete the missing demand. In addition, we consider that the unit cost of subcontracting is a variable depending on the quantity subcontracted. As a result, we have developed a stochastic optimal control model. Then, to solve the problem we compared three optimization methods: (exact/approximate), the genetic algorithm (GA), the Pattern Search (PS) and finally fmincon. Thus, we validate our approach via a numerical example and a sensitivity analysis.

This paper defines an internal production plan, a subcontracting plan and an optimal maintenance strategy. The optimal solution presented in this paper significantly improves the ability of the decision maker to consider larger instances of the integrated model. In addition, the decision maker can answer the following question: Which is the most optimal subcontractor to choose?

The approach developed deals with the case of the real-mode manufacturing industry, taking into consideration different constraints and determining decision variables which allow it to expand the profits of the manufacturing industry in different domains such as automotive, aeronautics, textile and pharmacies.

This paper is one of the few documents dealing with the integrated maintenance in subcontracting constraint production which considers the complex aspect of the multi-machine manufacturing industry. We also dealt with the stochastic aspect of demand and failures. Then, we covered the impact of the unit cost variation of subcontracting on the total cost. Finally, we shed light on a comparison between three optimization methods in order to arrive at the most optimal solution.

This paper provides an overview of five types of assembly equipment and indicates where each type is typically suited to small parts assembly operations

Scheduling is defined by Baker as, “the allocation of resources over time to perform a collection of tasks”. The term facilities is often used instead of resources and the tasks to be performed may involve a variety of different operations.

Force output is extremely important for electromagnetic linear machines. The purpose of this study is to explore new permanent magnet (PM) array and winding patterns to increase the magnetic flux density and thus to improve the force output of electromagnetic tubular linear machines.

Based on investigations on various PM patterns, a novel dual Halbach PM array is proposed in this paper to increase the radial component of flux density in three-dimensional machine space, which in turn can increase the force output of tubular linear machine significantly. The force outputs and force ripples for different winding patterns are formulated and analyzed, to select optimized structure parameters.

The proposed dual Halbach array can increase the radial component of flux density and force output of tubular linear machines effectively. It also helps to decrease the axial component of flux density and thus to reduce the deformation and vibration of machines. By using analytical force models, the influence of winding patterns and structure parameters on the machine force output and force ripples can be analyzed. As a result, one set of optimized structure parameters are selected for the design of electromagnetic tubular linear machines.

The proposed dual Halbach array and winding patterns are effective ways to improve the linear machine performance. It can also be implemented into rotary machines. The analyzing and design methods could be extended into the development of other electromagnetic machines.

DRAUGHTSMEN can make a major contribution to productivity provided they are trained in work study. This fact emerged from a paper presented by Mr. B. A. Dyson, General Manager (Overseas Production) of Hoover Ltd., to a joint work study conference organised by the British Institute of Management.

The progress of parallel computing in Information Retrieval (IR) is reviewed. In particular we stress the importance of the motivation in using parallel computing for text retrieval. We analyse parallel IR systems using a classification defined by Rasmussen and describe some parallel IR systems. We give a description of the retrieval models used in parallel information processing. We describe areas of research which we believe are needed.

HELD as usual in the unique atmosphere of the Grand Palais building, the fourteenth “Salon de l'Aviation,” from November 16th to December 2nd, presented a most international character, the number of machines exhibited by foreign manufacturers being appreciably increased over all previous shows. Products of seven countries were displayed in the vast hall, the aeroplanes occupying the ground floor, with the engines round them, while the balcony and other rooms were devoted to accessories and the official exhibition of the Ministère de l'Air. The fourth international Exhibition of Photogrammetry formed part of the show, and not the least instructive. The success of the Salon is a just reward for its sponsors, the Chambre Syndicate des Industries Aéronautiques, of which M. Henry Potez, the well‐known aeroplane and engine manufacturer, is the present President, M. André Granet being Commissaire‐Général.

The research aims to develop a practicable method to solve relatively large job‐shop scheduling problems (JSSP) for production planning in real‐time.

This paper analyses some search strategies based on machine‐order space, and proposes a filter search algorithm (FSA) to reduce computing time by improving the speed of finding a proper machine order. Numerical experiments are conducted to verify the FSA.

The experiments confirmed the superior performance of the FSA, making it possible to solve relatively large JSSPs in real‐time. The results showed that the leaf‐node number affects the solution quality. The performance can be improved by increasing the leaf‐node number. There is a significant decrease in the average quality deviation when the leaf‐node number increases; but the decreasing rate becomes minor when the leaf‐node number is relatively large. While triple filters may provide more leaf‐node numbers for the FSA, dual filters are considered enough for most practical scheduling problems. A method is proposed to determine appropriate leaf‐node numbers for practical production environments.

A limitation is that the FSA's performance is affected by the choice of leaf‐node number. Although the relationships between the solution quality and the leaf‐node number for some problems have been worked out, it will be useful future research to deduce the relationships for other job‐shop instances of different sizes.

The FSA is a new approach, which is particularly useful for planning production schedules needed for efficient and responsive management of manufacturing systems to cope with increasing global competition and market changes.