Minimum Time Cost Research Articles

A tool to minimize the time costs of parallel computations through optimal processing power allocation

AbstractIn this paper, we present a software system, OPAS (Optimal Allocation System), that incorporates the optimal allocation policy in the analysis of the time‐cost behaviour of parallel computations. OPAS assumes that the underlying system which supports the executions of parallel computations has a finite number of processors, that all the processors have the same speed and that the communication is achieved through a shared memory. OPAS defines the time cost as a function of the input, the algorithm, the data structure, the processor speed, the number of processors and the processing power allocation. In analysing the time cost of a computation, OPAS first uses the optimal allocation policy that we developed previously to determine the amount of processing power each node receives and then derives the computation's time cost. OPAS can evaluate different time‐cost behaviours, such as the minimum time cost, the maximum time cost, the average time cost and the time‐cost variance. It can also determine the speed‐up and efficiency, and plot the time‐cost curve and time‐cost distribution.

New lattice gas method for semiconductor transport simulations

We present a new lattice gas simulation technique for semiclassical semiconductor transport which is comparable in accuracy to Monte Carlo simulations, but is capable of dealing with arbitrarily complex spatial inhomogeneities, nonlinear dynamical effects and carrier instabilities with only a minimal additional cost in computer time, and runs orders of magnitude faster on parallel hardware.

The application of spreadsheets to data analysis in biology

Rapid analysis of data is useful in the laboratory or tutorial situation. A discussion of a graph or parameters derived from a line of best fit may help to identify and clarify experimental or procedural difficulties. Microcomputers in the classroom or laboratory can be excellent tools in such situations but the time needed to produce appropriate software can be a major disincentive to such work. This paper describes, with examples, the relevance of spreadsheets (purpose-built applications packages for data manipulation and presentation) to this problem. It is shown that, with few computing or programming skills, it is possible to use a single, powerful software package for many purposes. With minimal cost in time or money, a range of purpose-designed spreadsheet templates can be produced, applicable to many data analysis problems.

The value of obtaining renal images following brain scintigraphy with technetium-99m glucoheptonate.

The value of adding an extra view of the kidneys immediately following brain imaging with Tc-99m glucoheptonate was investigated in a two-year retrospective study at our institution. Between October 1982 and October 1984, 561 individuals underwent Tc-99m glucoheptonate brain imaging with the added renal view. Twenty-nine of these individuals (5.2%) demonstrated renal abnormalities. The abnormal renal findings were clinically correlated in 24 of these persons. Sixteen (67%) of these 24 individuals were unaware of any renal abnormality. Useful information can be obtained from renal images incidental to brain imaging at no added expense or radiation exposure to the patient, and at a minimal cost in time to the imaging clinic.

Heuristical job allocation in a flexible manufacturing system

Two heuristic algorithms are presented for solving the scheduling problem in a statically loaded Flexible Manufacturing System (FMS). The heuristics goal is to minimise the total cost resulting from the tardiness of jobs. Using the same heuristics, an iterative method is proposed to find an optimal makespan and the average lead time. Modifications required to handle the case of a dynamically loaded FMS are then presented. Simulation results show that the developed heuristics appear to out perform the other published techniques used in obtaining the schedules associated with minimum makespan, minimum average lead time and minimum cost of tardiness. Finally, the simulation of the dynamic case shows that the algorithms could be implemented locally on each station for the scheduling calculation.

Data structures for finite element modelling

The graphical representation of a finite element model (undirected graphs) imposes some constraints on the choice of storage techniques and data structures; first, the storage structure must deal efficiently with sparse matrices; second, the retrieval method of an edge, of a finite element model, around selected nodes must minimize the multiple occurrences of the same edge if plotting efficiency is to be achieved; and third, the insertion and extraction of edges in a data structure must be independent of the selected nodes identification scheme. This paper evaluates the relative merit of elementary storage methods and data structures in terms of the time and space costs required to satisfy the above constraints. The theoretical costs are derived and the experimental costs are evaluated and compared. Depending on the homogeneity of the degree of the nodes, a static data structure or a linked list data structure using listed or sectioned hashing techniques are shown to yield the minimum time and space costs.

Fuel-optimal aircraft trajectories with fixed arrival times

A maximum principle application shows that a fuel-optimal aircraft trajectory which arrives at an assigned time is also a direct operating cost-optimal trajectory for certain time cost. The time cost is minimum for maximum endurance cruise. Only for minimum time cost can an optimal trajectory contain a hold or path stretching segment. These concepts are illustrated for three aircraft: the Boeing 737, 747, and 767. Complete optimal trajectories are shown for the 747. Cruise control implications are investigated using the 767 model. Finally, optimal descents are compared to Mach/CAS descents for the 737.

Predicting rock pressure manifestations in seam development workings

1. By means of investigations on models made from equivalent materials, for the first time the authors have experimentally established the complex influence of the principal geological and technical factors, varying over a wide range of values, on the rock pressure parameters in a seam development working lying in the zone of influence of extraction operations. 2. It is found that the rheological properties of the surrounding rocks play a decisive role in the process of deformation of the seam development workings. In field and laboratory investigations, with the aim of obtaining trustworthy results it is therefore necessary to make combined investigations of the properties of the solid rock, including determinations of its rheological characteristics. 3. The above investigations show that it is necessary to make a more thorough study of the combined effects of the main geological and technical factors on the geomechanical process, and that experimental investigations made by up-to-date methods of scientific planning should be more widely taken into practice. These methods permit the data necessary for planning the support of development workings to be most completely studied with minimum cost of time and resources, and adopted in production most effectively. 4. A nomogram, based on the authors' investigations, permits more correct and more soundly based prediction of the expected displacements and the pressure on the supports in seam development workings driven and supported in a wide range of geological conditions.

Trade-offs in fixed-point multiplication algorithms for microprocesors

Multiplication algorithms which are appropriate for 8-bit microprocessors are discussed, particularly within the context of signal-processing needs, where minimisation of execution time is important. The trade-offs which exist between minimum memory, minimum execution time and minimum cost are discussed in detail, and specific examples based on the Z80 processor are included to provide a quantitative comparison of the alternatives.

Multicystic dysplastic kidney: diagnostic considerations and management.

A protocolled diagnostic approach for assessing various cystic and solid masses occurring in the neonate and infant, with particular emphasis on renal masses, is described. This protocol uses diagnostic examinations in such a sequence as to establish the diagnosis with acceptable confidence by the least invasive procedure and, therefore, at minimal cost in time, money, and risk to the patient. Early definitive diagnosis permits triage of patients into a group benefiting from immediate surgical intervention versus those with entities that can safely be followed up expectantly. Moreover, certain diagnostic procedures such as antegrade pyelography can be expanded to serve therapeutic purposes as a temporizing percutaneous nephrostomy, thus preserving renal parenchyma and hopefully improving the general condition of the neonate until a definitive surgical procedure can be safely undertaken to correct the underlying deficit.

Optimal conversion of extended-entry decision tables with general cost criteria

A general dynamic programming algorithm for converting limited, extended, or mixed entry decision tables to optimal decision trees is presented which can take into account rule frequencies or probabilities, minimum time and/or space cost criteria, common action sets, compressed rules and ELSE rules, sequencing constraints on condition tests, excludable combinations of conditions, certain ambiguities, and interrupted rule masking.

Costs of Shell Analysis

AbstractExcavation of a coastal site often involves the temptation to perform a quantitative analysis for mollusc shell present in the midden. A major factor in such an analysis is the time expense involved. This paper presents the minimal time costs for the sub-processes of standard shell analysis. Time costs for an actual shell analysis are reconstructed to illustrate the use of sub-process rates and as an independent check on the rates as reported. An adequate standard shell analysis is an expensive undertaking. The time and/or money involved might well be applied to more productive research.

Automatic analysis of amino-acid sequences in proteins and peptides.

AbstractThe development of the widely used automatic method from Edman's manual sequence analysis of proteins and peptides has resulted from modification of the procedure and from the use of a physically novel principle. All reaction, centrifugation, extraction, and drying operations are carried out in a rotating vessel. At a minimal cost in time and material, for example, sixty amino acids have been split off consecutively from a single sample of myoglobin.