Obtaining interaction diagram of concrete section exposed to fire by mathematical optimization

2021 ◽  
pp. 102993
Author(s):  
Han-Soo Kim
Keyword(s):  
Mathematical Optimization ◽  
Interaction Diagram ◽  
Concrete Section

Dimensioning a recovery boiler furnace using mathematical optimization

TAPPI Journal ◽  
2015 ◽  
Vol 14 (2) ◽  
pp. 119-129 ◽  
Author(s):  
VILJAMI MAAKALA ◽  
PASI MIIKKULAINEN
Keyword(s):  
Radial Basis Function Network ◽  
High Capacity ◽  
Mathematical Optimization ◽  
Optimization Procedure ◽  
Optimization Method ◽  
Performance Criteria ◽  
Boiler Furnace ◽  
Starting Point ◽  
Recovery Boiler ◽  
Base Design

Capacities of the largest new recovery boilers are steadily rising, and there is every reason to expect this trend to continue. However, the furnace designs for these large boilers have not been optimized and, in general, are based on semiheuristic rules and experience with smaller boilers. We present a multiobjective optimization code suitable for diverse optimization tasks and use it to dimension a high-capacity recovery boiler furnace. The objective was to find the furnace dimensions (width, depth, and height) that optimize eight performance criteria while satisfying additional inequality constraints. The optimization procedure was carried out in a fully automatic manner by means of the code, which is based on a genetic algorithm optimization method and a radial basis function network surrogate model. The code was coupled with a recovery boiler furnace computational fluid dynamics model that was used to obtain performance information on the individual furnace designs considered. The optimization code found numerous furnace geometries that deliver better performance than the base design, which was taken as a starting point. We propose one of these as a better design for the high-capacity recovery boiler. In particular, the proposed design reduces the number of liquor particles landing on the walls by 37%, the average carbon monoxide (CO) content at nose level by 81%, and the regions of high CO content at nose level by 78% from the values obtained with the base design. We show that optimizing the furnace design can significantly improve recovery boiler performance.

Generation of creep-fatigue interaction diagram for modified 9Cr–1Mo steel

2021 ◽  
Vol 191 ◽  
pp. 104376
Author(s):  
J. Veerababu ◽  
Sunil Goyal ◽  
J. Vanaja ◽  
A. Nagesha ◽  
M. Vasudevan
Keyword(s):  
Interaction Diagram ◽  
Creep Fatigue

scholarly journals Part-optimized forming by spatially distributed vaporizing foil actuators

2021 ◽  
Author(s):  
Marlon Hahn ◽  
A. Erman Tekkaya
Keyword(s):  
Process Design ◽  
High Speed ◽  
Specific Impulse ◽  
Design Procedure ◽  
Mathematical Optimization ◽  
Starting Point ◽  
Spatially Distributed ◽  
Lower Tool ◽  
A Minor ◽  
Charging Energy

AbstractElectrically vaporizing foil actuators are employed as an innovative high speed sheet metal forming technology, which has the potential to lower tool costs. To reduce experimental try-outs, a predictive physics-based process design procedure is developed for the first time. It consists of a mathematical optimization utilizing numerical forming simulations followed by analytical computations for the forming-impulse generation through the rapid Joule heating of the foils. The proposed method is demonstrated for an exemplary steel sheet part. The resulting process design provides a part-specific impulse distribution, corresponding parallel actuator geometries, and the pulse generator’s charging energy, so that all process parameters are available before the first experiment. The experimental validation is then performed for the example part. Formed parts indicate that the introduced method yields a good starting point for actual testing, as it only requires adjustments in the form of a minor charging energy augmentation. This was expectable due to the conservative nature of the underlying modeling. The part geometry obtained with the most suitable charging energy is finally compared to the target geometry.

scholarly journals Introducing fairness in Norwegian air ambulance base location planning

2021 ◽  
Vol 29 (1) ◽  
Author(s):  
Caroline J. Jagtenberg ◽  
Maaike A. J. Vollebergh ◽  
Oddvar Uleberg ◽  
Jo Røislien
Keyword(s):  
Social Welfare ◽  
Social Welfare Function ◽  
Mathematical Optimization ◽  
Population Coverage ◽  
Air Ambulance ◽  
Service Levels ◽  
Remote Areas ◽  
The North ◽  
Time Threshold ◽  
Essential Question

Abstract Background A primary task of the Norwegian helicopter emergency medical services (HEMS) is to provide advanced medical care to the critical ill and injured outside of hospitals. Where HEMS bases are located, directly influences who in the population can be reached within a given response time threshold and who cannot. When studying the locations of bases, the focus is often on efficiency, that is, maximizing the total number of people that can be reached within a given set time. This approach is known to benefit people living in densely populated areas, such as cities, over people living in remote areas. The most efficient solution is thus typically not necessarily a fair one. This study aims to incorporate fairness in finding optimal air ambulance base locations. Methods We solve multiple advanced mathematical optimization models to determine optimal helicopter base locations, with different optimization criteria related to the level of aversion to inequality, including the utilitarian, Bernoulli-Nash and iso-elastic social welfare functions. This is the first study to use the latter social welfare function for HEMS. Results Focusing on efficiency, a utilitarian objective function focuses on covering the larger cities in Norway, leaving parts of Norway largely uncovered. Including fairness by rather using an iso-elastic social welfare function in the optimization avoids leaving whole areas uncovered and in particular increases service levels in the north of Norway. Conclusions Including fairness in determining optimal HEMS base locations has great impact on population coverage, in particular when the number of base locations is not enough to give full coverage of the country. As results differ depending on the mathematical objective, the work shows the importance of not only looking for optimal solutions, but also raising the essential question of ‘optimal with respect to what’.

scholarly journals Intersection Sight Distance Characteristics of Turbo Roundabouts

Designs ◽  
2021 ◽  
Vol 5 (1) ◽  
pp. 16
Author(s):  
Akshay Salwan ◽  
Said M. Easa ◽  
Narayana Raju ◽  
Shriniwas Arkatkar
Keyword(s):  
North America ◽  
Mathematical Optimization ◽  
Critical Parameters ◽  
Practical Applications ◽  
Sight Distance ◽  
Large Numbers ◽  
Mathematical Formulas ◽  
Lateral Clearance ◽  
Intersection Geometry ◽  
Mathematical Characteristics

A turbo roundabout uses spiral circulatory roads for effectively counteracting the problems faced in modern multilane roundabouts. First developed in 1996, the turbo roundabout has an advantage over the conventional roundabout regarding capacity and safety. Turbo roundabouts are still in the developing phase in North America, but even in the European subcontinent where they exist in large numbers, reliable analytical studies on the critical parameters of roundabout visibility are lacking. Visibility (sight distance) helps to shape the geometry of the intersection and aids in safety. This paper presents the mathematical characteristics of the intersection geometry and intersection sight distance (ISD) of the turbo roundabout. Mathematical formulas are presented for the sight distance from the approaching vehicle to the conflicting-entering and circulating vehicles. The maximum lateral clearances to the conflicting vehicles are derived using mathematical optimization. The developed analytical method is verified graphically using AutoCAD. To assist in practical applications, design aids for the maximum lateral clearance are presented. The presented method and design aids should aid in promoting safety at turbo roundabouts.

scholarly journals Efficiency of integrated electrooxidation and anaerobic digestion of waste activated sludge

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
J. A. Barrios ◽  
A. Cano ◽  
F. F. Rivera ◽  
M. E. Cisneros ◽  
U. Durán
Keyword(s):  
Anaerobic Digestion ◽  
Current Density ◽  
Methane Production ◽  
Energy Recovery ◽  
Energy Analysis ◽  
Mathematical Optimization ◽  
Waste Activated Sludge ◽  
Bdd Electrode ◽  
Vs Removal ◽  
Pre Treatment

Abstract Background Most of the organic content of waste activated sludge (WAS) comprises microbial cells hard to degrade, which must be pre-treated for energy recovery by anaerobic digestion (AD). Electrooxidation pre-treatment (EOP) with boron-doped diamond (BDD) electrode have been considered a promising novel technology that increase hydrolysis rate, by the disintegrating cell walls from WAS. Although electrochemical oxidation could efficiently solubilize organic substances of macromolecules, limited reports are available on EOP of WAS for improving AD. In this endeavour, the mathematical optimization study and the energy analysis of the effects of initial total solids concentrations [TS] of WAS and current density (CD) during EOP on the methane production and removal of chemical oxygen demand (COD) and volatile solids (VS) were investigated. Because limited reports are available on EOP of WAS for improving biogas production, it is not well understood; however, it has started to attract interest of scientists and engineers. Results In the present work, the energy recovery as biogas and WAS conversion were comprehensively affected by CD and [TS], in an integrated EOP and AD system. When working with WAS at 3% of [TS] pre-treated at current density of 24.1 mA/cm2, the highest COD and VS removal were achieved, making it possible to obtain the maximum methane (CH4) production of 305 N-L/kg VS and a positive energy balance of 1.67 kWh/kg VS. Therefore, the current densities used in BDD electrode are adequate to produce the strong oxidant (hydroxyl radical, ·OH) on the electrode surface, allow the oxidation of organic compounds that favours the solubilization of particulate matter and VS from WAS. Conclusions The improvement of VS removal and COD solubilization were due to the effects of pre-treatments, which help to break down the microbial cells for faster subsequent degradation; this allows a decomposition reaction that leads to biodegrade more compounds during AD. The balance was positive, suggesting that even without any optimization the energy used as electricity could be recovered from the increased methane production. It is worth noting that this kind of analysis have not been sufficiently studied so far. It is therefore important to understand how operational parameters can influence the pre-treatment and AD performances. The current study highlights that the mathematical optimization and energy analysis can make the whole process more convenient and feasible.

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