Greedy Algorithm for Minimizing the Cost of Routing Power on a Digital Microgrid

In this paper, we propose the greedy smallest-cost-rate path first (GRASP) algorithm to route power from sources to loads in a digital microgrid (DMG). Routing of power from distributed energy resources (DERs) to loads of a DMG comprises matching loads to DERs and the selection of the smallest-cost-rate path from a load to its supplying DERs. In such a microgrid, one DER may supply power to one or many loads, and one or many DERs may supply the power requested by a load. Because the optimal method is NP-hard, GRASP addresses this high complexity by using heuristics to match sources and loads and to select the smallest-cost-rate paths in the DMG. We compare the cost achieved by GRASP and an optimal method based on integer linear programming on different IEEE test feeders and other test networks. The comparison shows the trade-offs between lowering complexity and achieving optimal-cost paths. The results show that the cost incurred by GRASP approaches that of the optimal solution by small margins. In the adopted networks, GRASP trades its lower complexity for up to 18% higher costs than those achieved by the optimal solution.

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ANALYSIS OF EXTERNAL ENGINEERING NETWORK METHODS

Municipal economy of cities ◽

10.33042/2522-1809-2020-4-157-7-11 ◽

2020 ◽

Vol 4 (157) ◽

pp. 7-11

Author(s):

V. Zhvan ◽

V. Donenko ◽

S. Kulish ◽

A. Taran

Keyword(s):

Physical And Mechanical Properties ◽

Directional Drilling ◽

Horizontal Directional Drilling ◽

Technological Parameters ◽

Optimal Method ◽

Advantages And Disadvantages ◽

Analytical Review ◽

Conducting Research ◽

The Cost ◽

Selection Of

The article is devoted to the effective analysis of trench and trenchless pipeline laying technologies. In the course of the work, an analytical review of pipeline assembly was performed, the main technological parameters, the scope of each method, and their advantages and disadvantages were determined. List of considered pipeline laying methods: trenching, horizontal directional drilling, mechanical puncture, hydraulic puncture, microtunneling and punching. The article analyzes the classical trench method and the most widely used trenchless ones: horizontal directional drilling; mechanical puncture; hydraulic puncture; microtunneling; punching. Each of these methods has several advantages and disadvantages. The choice of the optimal method of laying the pipeline depends on many factors: the physical and mechanical properties of soils and hydrogeological conditions, the length and diameter of the pipeline, the presence of other communications, buildings and structures, as well as the budget that customers have. Work time is the last deciding factor. Based on the results of the analysis of pipeline laying technologies and expert survey of construction industry experts, the cost table of each method was compiled, outlining the main characteristics of the technology: length of pipeline, speed of work, scope, cost, and the advantages and disadvantages of each of the considered methods. The conclusions about the use of each of the pipeline laying methods were made. Each of the methods has its advantages and disadvantages, so to choose the method of work it is necessary to conduct a comprehensive assessment of technological parameters, cost, scope and timing of work. The cost of lay-ing the pipeline consists of the following factors: conducting research; selection of diameter and determination of pipeline length; choice of laying method and equipment necessary for the works; selection of equipment, shut-off and control equipment and other materials arranged on the pipeline; terms of performance of works. Taking into account these factors, an estimate is made, which determines the cost of installation of a particular pipeline. After the analysis, we can conclude that among the methods of trenchless laying of pipelines can be identi-fied horizontally directional drilling, it is this method of laying the pipeline will be appropriate to use for our region. The drilling technique allows to carry out pipelines under obstacles, to pull long segments of networks, to repair site damage. This method is universal and can be used in almost any environment. Keywords: trenches, horizontal directional drilling, mechanical puncture, hydraulic piercing, microtunnelling, punching, pipeline.

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Forward Link Optimization for the Design of VHTS Satellite Networks

Electronics ◽

10.3390/electronics9030473 ◽

2020 ◽

Vol 9 (3) ◽

pp. 473 ◽

Cited By ~ 3

Author(s):

Flor G. Ortiz-Gomez ◽

Ramón Martínez ◽

Miguel A. Salas-Natera ◽

Andrés Cornejo ◽

Salvador Landeros-Ayala

Keyword(s):

Cost Model ◽

High Capacity ◽

Optimal Solution ◽

Satellite Networks ◽

Forward Link ◽

User Terminal ◽

Trade Offs ◽

Service Areas ◽

Optimum Solution ◽

The Cost

The concept of geostationary VHTS (Very High Throughput Satellites) is based on multibeam coverage with intensive frequency and polarization reuse, in addition to the use of larger bandwidths in the feeder links, in order to provide high capacity satellite links at a reduced cost per Gbps in orbit. The dimensioning and design of satellite networks based on VHTS imposes the analysis of multiple trade-offs to achieve an optimal solution in terms of cost, capacity, and the figure of merit of the user terminal. In this paper, we propose a new method for sizing VHTS satellite networks based on an analytical expression of the forward link CINR (Carrier-to-Interference-plus-Noise Ratio) that is used to evaluate the trade-off of different combinations of system parameters. The proposed method considers both technical and commercial requirements as inputs, including the constraints to achieve the optimum solution in terms of the user G/T, the number of beams, and the system cost. The cost model includes both satellite and ground segments. Exemplary results are presented with feeder links using Q/V bands, DVB-S2X and transmission methods based on CCM and VCM (Constant and Variable Coding and Modulation, respectively) in two scenarios with different service areas.

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Selection model of work technology based on multi–criteria evaluations

E3S Web of Conferences ◽

10.1051/e3sconf/202016408030 ◽

2020 ◽

Vol 164 ◽

pp. 08030

Author(s):

Sergey Barkalov ◽

Pavel Kurochka ◽

Anton Khodunov ◽

Natalia Kalinina

Keyword(s):

Cost Function ◽

Optimal Solution ◽

Budget Constraint ◽

Pareto Optimal Solution ◽

Pareto Optimal ◽

Customer Preferences ◽

Optimal Solution Set ◽

The Cost ◽

Comprehensive Indicator ◽

Selection Of

A model for the selection of options for the production of work in a construction project is considered, when each option is characterized by a set of criteria. The number of analyzed options is being reduced based on the construction of the Pareto-optimal solution set. The remaining options are used to solve the problem based on the network model,\ in which the solution will be a subcritical path that meets budgetary constraints. At the same time, the proposed comprehensive indicator characterizing the preferences of the customer makes it possible to determine alternative options for performing work in the energy project in such a way that the amount of costs allocated to implement the set of work under consideration is minimal. Another statement of the problem is also considered when it is necessary to determine a strategy for the implementation of an energy project that, given a planned budget constraint, maximizes the growth of a comprehensive indicator that characterizes customer preferences in this project. The solution of the tasks is given under the assumption of the convexity of the cost function.

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OIL AND THE ENVIRONMENT - CALIFORNIA CASE STUDY

The APPEA Journal ◽

10.1071/aj75015 ◽

1976 ◽

Vol 16 (1) ◽

pp. 137

Author(s):

D. W. Barnett

Keyword(s):

Energy Production ◽

Social Cost ◽

Shadow Price ◽

Optimal Solution ◽

Minimum Cost ◽

Gulf Of Alaska ◽

Outer Continental Shelf ◽

Trade Offs ◽

The Cost ◽

Prudhoe Bay

USA environmentalists have tended to oppose all new energy developments. Their efforts may be counterproductive because opposition to, say, offshore oil directly leads to the continued use of other energy sources that may have a higher social cost. Rather than attempting to eliminate all pollution from energy production, which would be prohibitively expensive, one should minimize the social cost of energy production for the given demand.Linear programming is used to rank various oils (California State and Outer Continental Shelf (OCS), Gulf of Alaska, Prudhoe Bay, Athabasca tar sands, oil shale and certain foreign crudes) in terms of their social desirability. The objective is to minimize the cost of supplying the California market, subject to resource, sulphur and oil spill constraints.Social desirability is indicated by the inclusion of the oil in the optimal solution and the size of the associated shadow price. The larger the shadow price, the greater the benefits of increased production. The more negative, the greater the cost associated with forcing consumption of that fuel. The environmental shadow prices indicate the size of the trade-off between a particular environmental standard and minimum cost. The trade-offs can be surprisingly large. Any reasonable spill standard can be achieved by changing the development pattern. Generally, the further offshore, the smaller is the environmental degradation, but the more expensive is the oil. Foreign oils can be economically and environmentally inferior to domestic oils. Crude from the California OCS, San Joaquin Valley and Prudhoe Bay appears a valuable resource, while the Gulf of Alaska, synthetic and foreign crudes appear marginal to submarginal.The methodology could be readily adapted to the Australian scene.

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Forward Link Optimization for the Design of VHTS Satellite Networks

10.20944/preprints202002.0262.v1 ◽

2020 ◽

Author(s):

Flor G. Ortiz-Gomez ◽

Ramón Martínez ◽

Miguel A. Salas-Natera ◽

Andrés Cornejo ◽

Salvador Landeros-Ayala

Keyword(s):

Cost Model ◽

High Capacity ◽

Optimal Solution ◽

Satellite Networks ◽

Forward Link ◽

User Terminal ◽

Trade Offs ◽

Service Areas ◽

Optimum Solution ◽

The Cost

The concept of geostationary VHTS (Very High Throughput Satellites) is based on multibeam coverage with intensive frequency and polarization reuse in addition to the use of larger bandwidths in the feeder links, in order to provide high capacity satellite links at a reduced cost per Gbps in orbit. The dimensioning and design of satellite networks based on VHTS imposes the analysis of multiple trade-offs to achieve an optimal solution in terms of cost, capacity and figure of merit of the user terminal. In this paper, we propose a new method for sizing VHTS satellite networks based on an analytical expression of the forward link CINR (Carrier-to-Interference-plus-Noise Ratio) that is used to evaluate the trade-off of different combinations of system parameters. The proposed method considers both technical and commercial requirements as inputs including the constraints to achieve the optimum solution in terms of the user G/T, the number of beams and the system cost. The cost model includes both satellite and ground segments. Exemplary results are presented with feeder links using Q/V bands, DVB-S2X and transmission methods based on CCM and VCM (Constant and Variable Coding and Modulation, respectively) in two scenarios with different service areas.

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SEARCH FOR THE OPTIMAL SOLUTION FOR ASSIGNING SUBURBAN-URBAN TRAINS ON BRANCHED LINES ON EACH OF THE POSSIBLE ROUTES

T-Comm ◽

10.36724/2072-8735-2020-14-11-39-45 ◽

2020 ◽

Vol 14 (11) ◽

pp. 39-45

Author(s):

Vadim N. Shmal ◽

◽

Liliya R. Aysina ◽

Keyword(s):

Genetic Algorithm ◽

Mathematical Model ◽

Optimal Solution ◽

Directed Search ◽

Optimal Method ◽

Source Data ◽

On Line ◽

The Difference ◽

Traffic Organization ◽

Selection Of

The article describes the problem of organizing train traffic on line with branches, analyzes possible separate routes on the "trunk" and "branch" sections, and brunched routes. The development of a mathematical model which consider the interests of passengers in a service provided and economic interest of passenger companies are elements of scientific novelty of presented researching. The insufficient disclosure in the existing theoretical base of the issues of train traffic organization on lines with branches confirms the relevance of the research. The deficit of clear requirements for the organization of such lines leads to empirical decisions when operating such facilities. Adhering to the goal of providing a comfortable service for passengers and taking into account economic aspects in the interests of suburban companies, the objective function is minimize the difference between the mileage of available seats (as a condition that reflects the interests of a commuter company) and the overcrowding of the train (as a criterion that ensures a comfortable ride for the passenger). The authors suggest using a genetic algorithm for solve this problem. Genetic algorithm is a tool that allows you to perform a directed search of competitive options. The article describes the method of applying the genetic algorithm, the formation of "parent" variants and "offspring" variants, compliance with a number of restrictions and ranking of offspring variants for the selection of the best "individuals". Before testing the proposed method on a real example, the authors make a preliminary analysis to identify possible shortcomings that require improvement. The possibility of using a mathematical model and a genetic algorithm to find the optimal (or close to optimal) option for organizing traffic on a line with branches is considered on an arbitrary example. The presented calculations can be performed in any analytical software package. In this research, the search for the optimal method to organize traffic on a line with branches was performed in the MS Excel product. Successful calculations on an arbitrary option using the proposed mathematical model and genetic algorithms (as a tool to determine the optimal option of movement), allows us to assume that calculations can be made based on real source data for suburban directions of railway junctions that have lines with branches.

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Product range optimization – case study

STUDIES AND SCIENTIFIC RESEARCHES ECONOMICS EDITION ◽

10.29358/sceco.v0i15.134 ◽

2010 ◽

Author(s):

Simona Barsan ◽

Mihaela Sima

Keyword(s):

Production Capacity ◽

Optimal Solution ◽

Optimization Procedure ◽

Product Range ◽

Market Requirements ◽

Products Analysis ◽

The Cost ◽

A Company ◽

Selection Of

The paper presents the optimizing procedure of the product range manufactured by a company which operates in the area of production and sales of the milling and bakery products. The paper authors have taken this company as an example since the products it manufactures and commercializes address to population and are required to meet both qualitative and quantitative market requirements. After a brief overview of the company, one analyses its production capacity, staff structure and distribution as well as the concern of the company for the employees’ training in its activity field, so as to fulfill all the necessary and required conditions for developing a qualitative activity. The analysis continues with: the cost of the product before optimization, software presentation and computerized optimization procedure, the selection of the products to be optimized, data collection, the optimization procedure, results obtaining and analysis, choosing the optimal solution for the analyzed products analysis and for the future competitiveness of the company.

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Application of a New Nonlinear Programming Code with Decomposition to the Regional Wastewater-Collection and Treatment-Location Problem

Environment and Planning A Economy and Space ◽

10.1068/a080563 ◽

1976 ◽

Vol 8 (5) ◽

pp. 563-571

Author(s):

L R Padgett ◽

A H Montgomery ◽

L Romino

Keyword(s):

Nonlinear Programming ◽

Economies Of Scale ◽

Location Problem ◽

Sewage Treatment ◽

Optimal Solution ◽

Cost Savings ◽

Regional Model ◽

Programming Algorithm ◽

Trade Offs ◽

The Cost

A new, highly reliable nonlinear programming algorithm is coupled with decomposition to find the optimal solution to a regional sewage-treatment system for an area in Monongalia County surrounding Morgantown, West Virginia. A regional model with trade-offs between the cost of transporting wastewater to centrally located plants for treatment and the economies of scale accruing to large centralized treatment plants is developed. Possible cost savings of an optimal system are demonstrated.

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Motivation Improves Working Memory by Two Processes: Prioritisation and Retrieval Thresholds

10.31234/osf.io/qkycj ◽

2021 ◽

Author(s):

John P Grogan ◽

Govind Randhawa ◽

Minho Kim ◽

Sanjay G Manohar

Keyword(s):

Working Memory ◽

Memory Capacity ◽

Memory Recall ◽

Improve Performance ◽

Trade Offs ◽

The Cost ◽

Memory Precision ◽

Speed Accuracy ◽

Selection Of ◽

Attention Shifts

Motivation can improve performance when the potential rewards outweigh the cost of effort expended. In working memory (WM), people can prioritise rewarded items at the expense of unrewarded items, suggesting a fixed memory capacity. But can capacity itself increase with motivation? Across four experiments (N = 30-34) we demonstrate motivational improvements in WM even when all items were rewarded. However, this was not due to better memory precision, but rather better selection of the probed item within memory. Motivational improvements operated independently of encoding, maintenance, or attention shifts between items in memory. Moreover, motivation slowed responses. This contrasted with the benefits of rewarding items unequally, which allowed prioritisation of one item over another. We conclude that motivation can improve memory recall, not via precision or capacity, but via speed-accuracy trade-offs when selecting the item to retrieve.

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Identifying Measurement Invariant Item Sets in Cross-Cultural Settings Using an Automated Item Selection Procedure

Methodology ◽

10.1027/1614-2241/a000155 ◽

2018 ◽

Vol 14 (4) ◽

pp. 177-188 ◽

Cited By ~ 2

Author(s):

Martin Schultze ◽

Michael Eid

Keyword(s):

Measurement Invariance ◽

Optimal Solution ◽

Selection Procedure ◽

Cross Cultural ◽

Item Selection ◽

Ant System ◽

Item Quality ◽

Ant System Algorithm ◽

Selection For ◽

Selection Of

Abstract. In the construction of scales intended for the use in cross-cultural studies, the selection of items needs to be guided not only by traditional criteria of item quality, but has to take information about the measurement invariance of the scale into account. We present an approach to automated item selection which depicts the process as a combinatorial optimization problem and aims at finding a scale which fulfils predefined target criteria – such as measurement invariance across cultures. The search for an optimal solution is performed using an adaptation of the [Formula: see text] Ant System algorithm. The approach is illustrated using an application to item selection for a personality scale assuming measurement invariance across multiple countries.

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