Search results

This paper aims to present a new multi-community meta-heuristic optimization algorithm, which is called shuffled shepherd optimization algorithm (SSOA). In this algorithm.

The agents are first separated into multi-communities and the optimization process is then performed mimicking the behavior of a shepherd in nature operating on each community.

A new multi-community meta-heuristic optimization algorithm called a shuffled shepherd optimization algorithm is developed in this paper and applied to some attractive examples.

A new metaheuristic is presented and tested with some classic benchmark problems and some attractive structures are optimized.

THE study of fatigue from a physiological aspect is a field which motion study technicians have made little or no attempt to explore. Shame on their heads. The physiological simplification of motions aimed at reducing fatigue could have completely offset the notion that motion study is aimed at converting the operator into an automaton. It may well be that an elaborate motion pattern set‐up designed to simplify the work merely succeeds in setting up stresses in the worker. The superimposing of a time‐studied standard for the job may not have taken into account the adaptation of the speed of motions to the physiological limitations of the operator working at a high level performance. Very few practitioners have attempted to study motions in the factory with a view to reducing fatigue and stress as a prerequisite to studying the set‐up for increased production. Still fewer have attempted to evaluate these factors. It is about time they did.

Nobody concerned with political economy can neglect the history of economic doctrines. Structural changes in the economy and society influence economic thinking and, conversely, innovative thought structures and attitudes have almost always forced economic institutions and modes of behaviour to adjust. We learn from the history of economic doctrines how a particular theory emerged and whether, and in which environment, it could take root. We can see how a school evolves out of a common methodological perception and similar techniques of analysis, and how it has to establish itself. The interaction between unresolved problems on the one hand, and the search for better solutions or explanations on the other, leads to a change in paradigma and to the formation of new lines of reasoning. As long as the real world is subject to progress and change scientific search for explanation must out of necessity continue.

A mathematical description of temperature-dependent boundary conditions is crucial in manifold model-based control or prototyping applications, where accurate thermal simulation results are required. Estimation of boundary condition coefficients for complex geometries in complicated or unknown environments is a challenging task and often does not fulfill given accuracy limits without multiple manual adaptions and experiments. This paper aims to describe an efficient method to identify thermal boundary conditions from measurement data using model order reduction.

An optimization problem is formulated to minimize temperature deviation over time between simulation data and available temperature sensors. Convection and radiation effects are expressed as a combined heat flux per surface, resulting in multiple temperature-dependent film coefficient functions. These functions are approximated by a polynomial function or splines, to generate identifiable parameters. A formulated reduced order system description preserves these parameters to perform an identification. Experiments are conducted with a test-bench to verify identification results with radiation, natural and forced convection.

The generated model can approximate a nonlinear transient finite element analysis (FEA) simulation with a maximum deviation of 0.3 K. For the simulation of a 500 min cyclic cooling and heating process, FEA takes a computation time of up to 13 h whereas the reduced model takes only 7-11 s, using time steps of 2 s. These low computation times allow for an identification, which is verified with an error below 3 K. When film coefficient estimation from literature is difficult due to complex geometries or turbulent air flows, identification is a promising approach to still achieve accurate results.

A well parametrized model can be further used for model-based control approaches or in observer structures. To the knowledge of the authors, no other methodology enables model-based identification of thermal parameters by physically preserving them through model order reduction and therefore derive it from a FEA description. This method can be applied to much more complex geometries and has been used in an industrial environment to increase product quality, due to accurate monitoring of cooling processes.

THE fashionable topic today is management. Critics lay at its door many of the troubles from which we suffer. On the other hand there are those who laud it as the key which will open the door to future prosperity for this country. Government, Press, commerce and industry are as one in assuring us that by making management efficient we can say goodbye to many of our difficulties. That is a rather facile assumption. Prosperity depends on productivity and management is only one of the factors involved.

IT must not be left exclusively to the United States, her native land, to pay tribute to Dr. Lillian M. Gilbreth on the occasion of her eightieth birthday. Her work in applying science to the problem of increasing productivity deserves the gratitude of us all, since it has affected the economy of all industrial countries and contributed substantially to the higher standard of life which is now enjoyed.

MANY indications of the growing importance of work study as an aid to increased productivity will be in evidence at the Third Annual Production Exhibition and Convention (Olympia, May 12–21) where many of the improved methods displayed by upwards of a hundred firms and organisations are the direct or indirect results of the application of work study techniques.

The purpose of this paper is to study the flow characteristics of damping control valve of shock absorber, and obtain the minimum driving current required under different working conditions.

Based on the simplified model of the internal structure of damping control valve and the theory of fluid mechanics, the mathematical model of the damping control valve driving current under rated load is established. The test bench was designed to study the relationship between flow characteristics and driving current of the damping control valve.

The results show that the minimum driving current of switching and flowrate show a linear relationship and the minimum current required for the 4-1 switching is the largest that means the minimum current as long as meets the 4-1 switching to meet the needs of all levels switching.

These results of the theoretical and experimental study provide a reliable guide and reference for the design and application of damping control valve.

In discussing the subject of bread, or indeed any subject, one is of course confronted by the initial difficulty of definition. Nothing is harder than to define any concrete thing, no matter how common and well‐known it may be. This is not surprising when we remember that no one has ever succeeded in defining a definition. Perhaps the best attempt to do so is Pascal's, in the “Port Royal Logic,” and it is easy to drive a coach and six through the rules which he lays down for definitions to conform to. The only things that can be strictly defined are mathematical abstractions, such as a circle, which are formed on natural objects by pruning away their multitudinous properties till only two or three which can be expressed by a short and indisputable definition are left.

MODERN work study technique demands that the methods engineer and the time study engineer work hand in hand for the benefit of productivity as a whole. And to state the obvious it is becoming clearer that time and motion are indivisible.