Minimum Cost Globally Rigid Subgraphs

Author(s):  
Tibor Jordán ◽  
András Mihálykó
Keyword(s):  
2020 ◽  
Vol 54 (6) ◽  
pp. 1775-1791
Author(s):  
Nazila Aghayi ◽  
Samira Salehpour

The concept of cost efficiency has become tremendously popular in data envelopment analysis (DEA) as it serves to assess a decision-making unit (DMU) in terms of producing minimum-cost outputs. A large variety of precise and imprecise models have been put forward to measure cost efficiency for the DMUs which have a role in constructing the production possibility set; yet, there’s not an extensive literature on the cost efficiency (CE) measurement for sample DMUs (SDMUs). In an effort to remedy the shortcomings of current models, herein is introduced a generalized cost efficiency model that is capable of operating in a fuzzy environment-involving different types of fuzzy numbers-while preserving the Farrell’s decomposition of cost efficiency. Moreover, to the best of our knowledge, the present paper is the first to measure cost efficiency by using vectors. Ultimately, a useful example is provided to confirm the applicability of the proposed methods.


2020 ◽  
Vol 26 (3) ◽  
pp. 685-697
Author(s):  
O.V. Shimko

Subject. The study analyzes generally accepted approaches to assessing the value of companies on the basis of financial statement data of ExxonMobil, Chevron, ConocoPhillips, Occidental Petroleum, Devon Energy, Anadarko Petroleum, EOG Resources, Apache, Marathon Oil, Imperial Oil, Suncor Energy, Husky Energy, Canadian Natural Resources, Royal Dutch Shell, Gazprom, Rosneft, LUKOIL, and others, for 1999—2018. Objectives. The aim is to determine the specifics of using the methods of cost, DFC, and comparative approaches to assessing the value of share capital of oil and gas companies. Methods. The study employs methods of statistical analysis and generalization of materials of scientific articles and official annual reports on the results of financial and economic activities of the largest public oil and gas corporations. Results. Based on the results of a comprehensive analysis, I identified advantages and disadvantages of standard approaches to assessing the value of oil and gas producers. Conclusions. The paper describes pros and cons of the said approaches. For instance, the cost approach is acceptable for assessing the minimum cost of small companies in the industry. The DFC-based approach complicates the reliability of medium-term forecasts for oil prices due to fluctuations in oil prices inherent in the industry, on which the net profit and free cash flow of companies depend to a large extent. The comparative approach enables to quickly determine the range of possible value of the corporation based on transactions data and current market situation.


Author(s):  
Ki-Sang Song ◽  
Arun K. Somani

From the 1994 CAIS Conference: The Information Industry in Transition McGill University, Montreal, Quebec. May 25 - 27, 1994.Broadband integrated services digital network (B-ISDN) based on the asynchronous transmission mode (ATM) is becoming reality to provide high speed, multi bit rate multimedia communications. Multimedia communication network has to support voice, video and data traffics that have different traffic characteristics, delay sensitive or loss sensitive features have to be accounted for designing high speed multimedia information networks. In this paper, we formulate the network design problem by considering the multimedia communication requirements. A high speed multimedia information network design alogrithm is developed using a stochastic optimization method to find good solutions which meet the Quality of Service (QoS) requirement of each traffic class with minimum cost.


1982 ◽  
Vol 21 (3) ◽  
pp. 231-244
Author(s):  
Mia A M. De Kuijper

In Pakistan the prices of petroleum products are set by the government, to raise revenues, stabilize prices, and achieve redistribution and social objectives. But in addition to these benefits, government31 taxes and subsidies for petroleum pro• ducts result in losses in economic efficiency through the misallocation of resources. How do the benefits compare with these losses? Are revenues raised in a manner that minimizes economic waste? Do the subsidies achieve equity or other social benefits at minimum cost?


Author(s):  
T. Movchan ◽  
V. Artеmov ◽  
D. Bulysheva

It is recommended to implement forecasting management models in the area of land use and protection by applying linear programming methods to optimize the size of farms, which land is located in different natural and economic zones. Analysis and assessment of land use in natural-economic zones is a type of management activity for deep understanding of the dialectic of a managed object development and true assessment of its moving forces. This enables to simulate the situation of land use, to identify a specific goal, to choose the means to achieve it and to obtain the optimum result. The implementation of the proposed forecast models of the optimal farm size is carried out by linear programming in three ways (northwest corner method, minimum cost method and What-If analysis method, that uses Solver, a Microsoft Excel add-in program). The implementation of the above approaches is based on the example of four farms and five natural-economic zones. The obtained solutions show that the best result is attained by using Solver for What-If analysis method, a Microsoft Excel add-in program. The northwest corner method gives the worst result, but this is the simplest solution. The minimum cost method depends on the researcher qualification and produces the result that is most often found between the results obtained by the northwest corner method and the "Solver" procedure. When using the method of the northwest corner a program of consideration of different options for the distribution of land resources and the choice of the optimal solution was developed. This allows to find an optimal result of land allocation according to the result, which is similar to the result of the procedure "Solver", but it is more adapted for the direct participation of the researcher in the process of solving problems. There is an opportunity to improve the result by changing the original data, which simulates the forecast of the distribution of farm land in natural-economic zones, while minimizing production costs. In the absence of access to computers, the solutions obtained by the northwest corner and the minimum cost methods can be improved by the potential method.


1974 ◽  
Vol 9 (1) ◽  
pp. 25-29
Author(s):  
M. B. Bayer

Abstract This paper describes a method of applying probabilistic DO (dissolved oxygen) and BOD (biochemical oxygen demand) standards in river basin water quality models. Maximum likelihood estimators for the DO and BOD concentrations variances for each reach are used to obtain a lower bound for BOD so that the probability of violating specified DO and BOD standards is less than Θ per cent in any reach. These boundary values for DO and BOD concentrations are incorporated into a nonlinear water quality optimization model for finding the minimum cost set of wastewater treatment plant efficiencies required to meet DO and BOD standards. The method also provides the minimum DO concentration and the maximum BOD concentration which may be expected to occur 1-Θ of the time for any reach.


2020 ◽  
Vol 14 ◽  
Author(s):  
Osama Bedair

Background: Modular steel buildings (MSB) are extensively used in petrochemical plants and refineries. Limited guidelines are available in the industry for analysis and design of (MSB) subject to accidental vapor cloud explosions (VCEs). Objectives: The paper presents simplified engineering model for modular steel buildings (MSB) subject to accidental vapor cloud explosions (VCEs) that are extensively used in petrochemical plants and refineries. Method: A Single degree of freedom (SDOF) dynamic model is utilized to simulate the dynamic response of primary building components. Analytical expressions are then provided to compute the dynamic load factors (DLF) for critical building elements. Recommended foundation systems are also proposed to install the modular building with minimum cost. Results: Numerical results are presented to illustrate the dynamic response of (MSB) subject to blast loading. It is shown that (DLF)=1.6 is attained at (td/t)=0.4 for front wall (W1) with (td/T)=1.25. For side walls (DLF)=1.41 and is attained at (td/t)=0.6. Conclusions: The paper presented simplified tools for analysis and design of (MSB) subject accidental vapor cloud blast explosions (VCEs). The analytical expressions can be utilized by practitioners to compute the (MSB) response and identify the design parameters. They are simple to use compared to Finite Element Analysis.


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