scholarly journals Mathematical model of steel consumption minimization considering the two-stage billets cutting

2021 ◽  
pp. 118-124
Author(s):  
V.V Hnatushenko ◽  
T.A Zheldak ◽  
L.S Koriashkina
Keyword(s):  
Mathematical Model ◽  
Mathematical Optimization ◽  
Optimal Size ◽  
Multi Stage ◽  
Distribution Process ◽  
Steel Consumption ◽  
Rolling Production ◽  
Mathematical Optimization Model ◽  
The Moment ◽  
Cutting Plan

Purpose. To achieve a decrease in energy and resource costs in the multi-stage production of rolled products within a given plan through the development of appropriate mathware. Methodology. The multi-stage problem mathware for producing rolling steel products is developed on the basis of system approach applying fundamental principles of the optimization and operation research theory. Realization of the developed mathematical model allows discovering such a strategy of using steel during the whole manufacturing process, which minimizes not only the steel waste at the moment of its casting in a mold, but also the offcuts in the process of cutting the obtained ingots into the billets. Findings. A mathematical task model is built to minimize the amount of steel for producing a certain order of size of one cast volume only. The developed model specifies the possibility to pre-evaluate the billet optimal size, based on the necessary cutting along the final product length, appropriate for the certain billet form of section, and ingot weight limits. Originality. A mathematical model is provided for the optimal metal distribution process when implementing the plan of manufacturing rolling products. The model, in contrast to the existing ones, shifts the emphasis on forming the optimal ingot weight, which has a pre-calculated optimal cutting plan. Practical value. The use of the developed mathematical optimization model (minimizing the amount of steel for producing a certain order) as part of an automated decision support system for management of rolling production will reduce the number of cutting machine changeover and minimize resources use and stock balance.

Initial Prestress Optimization of Tensegrity Structures Based on Fish-Swarm Algorithm

2012 ◽  
Vol 594-597 ◽  
pp. 2922-2926
Author(s):  
Cheng Qing Liu ◽  
Rui Liang ◽  
Wei Xing Shi
Keyword(s):  
Mathematical Model ◽  
Matrix Theory ◽  
Mathematical Optimization ◽  
Tensegrity Structures ◽  
Matlab Program ◽  
Force Finding ◽  
Equilibrium Matrix ◽  
Mathematical Optimization Model ◽  
Swarm Algorithm ◽  
Compression Condition

Several force finding methods for the tensegrity structures, coupled with their limitations, are simply reviewed. Based on the equilibrium matrix theory and the judgment of structure’s geometrical stability, a new mathematical model, which considering the uniformity as well as the tension-compression condition of elements prestress, is proposed in this paper. The author write a corresponding MATLAB program by using the Fish-swarm Algorithm, and an example of multi states of self-stress tensegrity structrue is presented. The results show that the proposed mathematical optimization model can solve the force-finding problem of any multi states of self-stress tensegrity structure accurately and efficiently.

scholarly journals Modelling the impact of delaying vaccination against SARS-CoV-2 assuming unlimited vaccine supply

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Marcos Amaku ◽  
Dimas Tadeu Covas ◽  
Francisco Antonio Bezerra Coutinho ◽  
Raymundo Soares Azevedo ◽  
Eduardo Massad
Keyword(s):  
Mathematical Model ◽  
Vaccination Campaign ◽  
Vaccination Rate ◽  
Sao Paulo ◽  
The State ◽  
São Paulo ◽  
Health Authorities ◽  
The World ◽  
The Moment ◽  
The Impact

Abstract Background At the moment we have more than 177 million cases and 3.8 million deaths (as of June 2021) around the world and vaccination represents the only hope to control the pandemic. Imperfections in planning vaccine acquisition and difficulties in implementing distribution among the population, however, have hampered the control of the virus so far. Methods We propose a new mathematical model to estimate the impact of vaccination delay against the 2019 coronavirus disease (COVID-19) on the number of cases and deaths due to the disease in Brazil. We apply the model to Brazil as a whole and to the State of Sao Paulo, the most affected by COVID-19 in Brazil. We simulated the model for the populations of the State of Sao Paulo and Brazil as a whole, varying the scenarios related to vaccine efficacy and compliance from the populations. Results The model projects that, in the absence of vaccination, almost 170 thousand deaths and more than 350 thousand deaths will occur by the end of 2021 for Sao Paulo and Brazil, respectively. If in contrast, Sao Paulo and Brazil had enough vaccine supply and so started a vaccination campaign in January with the maximum vaccination rate, compliance and efficacy, they could have averted more than 112 thousand deaths and 127 thousand deaths, respectively. In addition, for each month of delay the number of deaths increases monotonically in a logarithmic fashion, for both the State of Sao Paulo and Brazil as a whole. Conclusions Our model shows that the current delay in the vaccination schedules that is observed in many countries has serious consequences in terms of mortality by the disease and should serve as an alert to health authorities to speed the process up such that the highest number of people to be immunized is reached in the shortest period of time.

AUTOMATED OPERATIONAL SCHEDULING SYSTEM FOR MULTI-STAGE PRODUCTION: MATHEMATICAL MODEL AND SOFTWARE IMPLEMENTATION

2021 ◽  
Vol 3 (102) ◽  
pp. 18-37
Author(s):  
OXANA S. LOGUNOVA ◽  
MIKHAIL B. ARKULIS
Keyword(s):  
Mathematical Model ◽  
Raw Materials ◽  
Software Implementation ◽  
Scheduling System ◽  
Operation Conditions ◽  
Multi Stage ◽  
Complete Set ◽  
Wip Inventory ◽  
Production Areas ◽  
Strip Production

The purpose of the study is to improve the efficiency of production areas of multi-stage production with the possibility of rational use of equipment capacity and stocks of WIP inventory in the operation conditions of the automated operational scheduling system. Features of the considered problem regarding operative calendar planning are: necessity of processing raw materials at several stages according to the flow chart; an array of the equipment which demands division of work into three periods for each party; availability of planned and unscheduled equipment downtime; necessity to complete set of orders from several suborders; availability of incomplete production in a warehouse; restrictions in order and timing of orders. In the work, the authors construct a mathematical model with the use of multidimensional matroids with structured elements in the construction of free time scale for equipment loading. The research was carried out for a metallurgical plant at the cold strip production site...

DIFFERENTIAL EQUATIONS FOR TRAIN STARTING WITH ELASTIC CONNECTIONS

2021 ◽  
Vol 2 ◽  
pp. 18-26
Author(s):  
I.P. POPOV
Keyword(s):  
Mathematical Model ◽  
Differential Equations ◽  
Friction Force ◽  
Static Friction ◽  
Longitudinal Vibrations ◽  
Maximum Tension ◽  
Inert Mass ◽  
The Moment ◽  
Elastic Couplings ◽  
Selection Of

The starting mode for the train is the most difficult. An effective method of pulling is the selection of coupling clearances. In this case, the cars are set in motion sequentially and the inert mass, as well as the static friction force immediately at the moment of starting, are minimal. This method has two significant drawbacks - a small fixed value of the gaps in the couplings and the shock nature of the impulse transfer. These disadvantages can be avoided by using elastically deformable couplings. The aim of this work is to construct a mathematical model of "easy" starting of a train with elastic couplings. The softening of the train start-off mode is essentially due to the replacement of the simultaneous start-off of the sections with alternate ones. To exclude longitudinal vibrations of the composition, after reaching the maximum tension of the coupling, the possibility of its harmonic compression should be mechanically blocked.

scholarly journals A Mathematical Optimization Model for Locating Telecenters

2012 ◽  
Vol 03 (03) ◽  
pp. 251-263 ◽  
Author(s):  
Morteza Tabatabaie Shourijeh ◽  
Mohammad Kermanshah ◽  
Amir Reza Mamdoohi ◽  
Ardeshir Faghri ◽  
Khaled Hamad
Keyword(s):  
Optimization Model ◽  
Mathematical Optimization ◽  
Mathematical Optimization Model

scholarly journals Optimal Semi-Competitive Intermediation Networks

2020 ◽  
Vol 20 (5) ◽  
pp. 81-94
Author(s):  
Amelia Bădică ◽  
Costin Bădică ◽  
Maria Ganzha ◽  
Mirjana Ivanović ◽  
Marcin Paprzycki
Keyword(s):  
Optimization Model ◽  
Numerical Optimization ◽  
Autonomous Agents ◽  
Mathematical Optimization ◽  
Optimal Strategies ◽  
Directed Acyclic Graphs ◽  
Pricing Strategies ◽  
Computational Results ◽  
Acyclic Graphs ◽  
Mathematical Optimization Model

AbstractIn this work we address the problem of optimizing collective profitability in semi-competitive intermediation networks defined as augmented directed acyclic graphs. Network participants are modeled as autonomous agents endowed with private utility functions. We introduce a mathematical optimization model for defining pricing strategies of network participants. We employ welfare economics aiming to maximize the Nash social welfare of the intermediation network. The paper contains mathematical results that theoretically prove the existence of such optimal strategies. We also discuss computational results that we obtained using a nonlinear convex numerical optimization package.

Abstract 108: Optimal In-Hospital Defibrillator Placement

Circulation ◽  
2019 ◽  
Vol 140 (Suppl_2) ◽  
Author(s):  
Kwan Hon Benjamin Leung ◽  
Matthew Yang ◽  
Christopher Sun ◽  
Katherine S Allan ◽  
Natalie Wong ◽  
...  
Keyword(s):  
Average Distance ◽  
Mathematical Optimization ◽  
Rank Test ◽  
Relative Decrease ◽  
Signed Rank ◽  
Out Of Sample ◽  
Signed Rank Test ◽  
Academic Teaching Hospital ◽  
Mathematical Optimization Model ◽  
The Difference

Introduction: Delays in defibrillation of in-hospital cardiac arrests (IHCAs) can reduce the likelihood of survival. Mathematical optimization has been shown to improve public location defibrillator placement but has not been applied to in-hospital defibrillator placement. Objective: To determine if mathematical optimization of in-hospital defibrillator placements can reduce distances to IHCAs compared to current placements in a large academic teaching hospital. Methods: We identified all treated IHCAs and defibrillator placements in St. Michael’s Hospital in Toronto, Canada from Jan. 2007 to Jun. 2017 and mapped them to a 3-D representation of the hospital that we developed from blueprints. An equal number of optimal defibrillator locations was identified using a mathematical optimization model that minimizes the average distance between IHCAs and the closest defibrillator in a 10-fold cross-validation approach. The optimized and current defibrillator locations were compared in terms of average distance to the out-of-sample IHCAs in each fold. We repeated the analysis excluding IHCAs and defibrillators in intensive care units (ICUs), operating theaters (OTs), and the emergency department (ED). Significance in the difference of average distance was determined using a Wilcoxon signed-rank test. Results: We identified 537 treated IHCAs and 53 defibrillators within the hospital during the study period. Of these, 236 IHCAs and 38 defibrillators were outside of ICUs, OTs, and the ED. Optimal defibrillator placements reduced the average defibrillator-to-IHCA distance from 17.1 m to 3.8 m, a relative decrease of 77.8% (P<0.01) on all IHCAs compared to current defibrillator placements. For non-ICU/OT/ED IHCAs, the average distance was reduced from 18.3 m to 9.8 m, a relative decrease of 46.4% (P<0.01). Conclusion: Optimization-guided placement of in-hospital defibrillators can significantly reduce the distance from an IHCA to the closest defibrillator.

Approach for the Design of Specialized Ships: The Case of Cargo Transport to an Ocean Island

2021 ◽  
Vol 163 (A2) ◽  
Author(s):  
V M F S Santos ◽  
H O Duarte ◽  
S E G Melo ◽  
M N Peres ◽  
E C Domingues
Keyword(s):  
Protected Area ◽  
Marine Protected Area ◽  
Mathematical Optimization ◽  
Cost Savings ◽  
Economic Feasibility ◽  
Feasibility Analysis ◽  
Preliminary Design ◽  
Cargo Transport ◽  
Fernando De Noronha ◽  
Mathematical Optimization Model

The island of Fernando de Noronha (FN) is a marine protected area, located about 293 nautical miles from Recife, Brazil. Supplies are transported out by improvised boats and the main freight contractor, the Administration of FN (AFN) spends large sums with outsourced shipping services, some of which could be redirected to problems of major concern such as health, environment and education. Using a sequence of five steps, including the construction of a database, mathematical simulation and economic feasibility analysis, it was possible to develop a preliminary design for a specialized economically viable vessel, which meets the requirement, draught limitations and needs of the island of FN. It is shown that the approach is feasible through the construction of a mathematical optimization model and a design of a vessel of about 450 tons of displacement that allows cost savings to AFN of around US$ 1.76M per year.

Perishing Goods Transportation Problem

2019 ◽  
pp. 315-338
Author(s):  
Ocotlán Díaz-Parra ◽  
Jorge A. Ruiz-Vanoye ◽  
Alejandro Fuentes-Penna ◽  
Ricardo A. Barrera-Cámara ◽  
Miguel A. Ruiz-Jaimes ◽  
...  
Keyword(s):  
Transportation Problem ◽  
Mathematical Optimization ◽  
Economic Losses ◽  
Perishable Products ◽  
Extreme Conditions ◽  
Smart Transportation ◽  
Transportation Modes ◽  
Mathematical Optimization Model ◽  
Transportation Times ◽  
Fresh Products

The smart transportation of farming must carry food from agriculture, livestock, and fisheries from one location to another using diverse types of transportation modes to improve the wellbeing of citizens. The mathematical optimization model proposed in this chapter represents the problem of transportation of perishable products which aims to minimize costs and optimize transportation times and costs. Reduction of the time of transportation of perishable products increases the likelihood of delivering fresh products and minimizes economic losses. Transportation time and temperature suitable for the conservation of the product are priorities in this type of problem because the product is transported in time reduces the probability that the product will be exposed to extreme conditions that favor its decomposition. To check the feasibility of the model, this study proposes a set of instances subject to an application obtained a series of solutions that are analyzed to identify if there is a feasible solution.

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