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Estimating isotherm parameters of drying clay for the ceramic industry of Sergipe, Brazil

APPLIED CLAY SCIENCE 2018年 161卷 211-214页

作者： Oliveira, H. A. Silva, D. C. Oliveira, R. M. P. B. Santos, C. P. de Jesus, E. Macedo, Z. S. Univ Fed Sergipe Mat Sci & Engn Grad Program P2CEM Av Marechal Rondon S-N BR-49100000 Sao Cristovao SE Brazil Univ Fed Sergipe Chem Engn Dept Av Marechal Rondon S-N BR-49100000 Sao Cristovao SE Brazil Univ Fed Sergipe Phys Dept Av Marechal Rondon S-N BR-49100000 Sao Cristovao SE Brazil

The drying process is one of the main stages of production phase of ceramics. Drying without (previous) knowledge of the technological characteristics of clay and the drying parameters may create cracks and deformations in the products. In this study, the models of Page, Henderson & Pabis, Lewis and Midilli were used to evaluate the drying process conditions of five clays used in the ceramic industry in the state of Sergipe, Brazil. The samples in this study were identified as: 1-PIN, 2-IN, 3-PIR, 4-MA and 5-VER, which come from four different deposits in Sergipe and from a deposit in Alagoas. The clays were first characterized through particle size analysis, chemical composition, organic matter content, plasticity index and X-ray diffractometry. Specimens were prepared by axial pressure with 8% moisture and subjected to drying where moisture loss over time was evaluated. The drying parameters were estimated using non-linear adjustments with the GAMS (General Algebraic Modeling System) application. The sum of squared errors (SSE) was used as the objective function and the root mean square error (RMSE) was used as the models performance function. According to the results found, we observed that the Midilli model best described the drying of the five clays, with 5-VER clay presenting drying coefficient of k = 1.442 h(-1) and clay 3-PIR presenting k = -0.125 h(-1). Thus, 5-VER and 3-PIR clays showed high and low rates of water loss, respectively. These results are consistent with the data obtained through the physical, chemical and structural characterization of clays.

关键词： Clay Ceramics Drying parameters non-linear programming

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COMPUTABLE NUMERICAL BOUNDS FOR LAGRANGE MULTIPLIERS OF STATIONARY-POINTS OF non-CONVEX DIFFERENTIABLE non-linear PROGRAMS

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OPERATIONS RESEARCH LETTERS 1985年第2期4卷 47-48页

作者： MANGASARIAN, OL Computer Sciences Department University of Wisconsin Madison WI 53706 USA

It is shown that the satisfaction of a standard constraint qualification of mathematical programming [5] at a stationary point of a non-convex differentiable non-linear program provides explicit numerical bounds for the set of all Lagrange multipliers associated with the stationary point. Solution of a single linear program gives a sharper bound together with an achievable bound on the 1-norm of the multipliers associated with the inequality constraints. The simplicity of obtaining these bounds contrasts sharply with the intractable NP-complete problem of computing an achievable upper bound on the p-norm of the multipliers associated with the equality constraints for integer p ≧ 1 .

关键词： non-linear programming Lagrange multipliers

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Allocating tolerances to minimize cost of nonconforming assembly

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ASSEMBLY AUTOMATION 1997年第4期17卷 303-+页

作者： Wei, CC Chung Hua Polytech Inst Dept Ind Engn & Management Hsinchu Taiwan

Tolerance assignment plays a vital role in reducing the manufacturing cost, and most optimization models for assigning the tolerances lend to ignore the process capability of the machine. Therefore, the quality loss due to nonconforming parts can be unacceptably high. Proposes a non-linear mathematical programming model for determining the component tolerances by simultaneously formulating the component's manufacturing cost, the machine's process capability and scrap rate. Includes a comparison between the results obtained by the proposed model and the traditional method.

关键词： mathematical programming model non-linear programming production costs scrap rates

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Process synthesis for particle separations using centrifuges

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COMPUTERS & CHEMICAL ENGINEERING 1998年第3期22卷 351-356页

作者： Agena, SM Bogle, IDL Cornish, ARH Univ London Univ Coll Dept Chem & Biochem Engn London WC1E 7JE England

Particle separations with centrifuges, i.e. non-sharp separations, are investigated. A methodology is studied which will lead to the creation of a cost optimal particle separation process. The particle separation task examined is specified by fixing the feed flowrate and particle composition of feed and products. According to separation breakpoints for adjacent particle size channels, a superstructure is built which contains all possible processing solutions. The optimal particle separation process is obtained using a non-linear optimisation technique (MINOS, GAMS). This technique is used to minimise an objective function in terms of centrifugation costs, subject to the formulations of the superstucture. It is demonstrated that the methodology of the superstructure can be successfully applied for particle separation processes. Cost optimal operating and design conditions are deduced for three particle separation tasks. (C) 1998 Elsevier Science Ltd. All rights reserved.

关键词： sloppy separation non-sharp separation superstructure non-linear programming optimisation GAMS MINOS

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Sourcing with random yields and stochastic demand: A newsvendor approach

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COMPUTERS & OPERATIONS RESEARCH 2007年第12期34卷 3682-3690页

作者： Yang, Shitao Yang, Jian Abdel-Malek, Layek New Jersey Inst Technol Dept Ind & Mfg Engn Newark NJ 07102 USA Seton Hall Univ Stillman Sch Business S Orange NJ 07079 USA

We studied a supplier selection problem, where a buyer, while facing random demand, is to decide ordering quantities from a set of suppliers with different yields and prices. We provided the mathematical formulation for the buyer's profit maximization problem and proposed a solution method based on a combination of the active set method and the Newton search procedure. Our computational study shows that the proposed method can solve the problem efficiently, and is able to generate interesting and insightful results that lead us to various managerial implications.

关键词： supply chain supplier selection newsvendor non-linear programming

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Design and optimization of a novel system for trigeneration

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ENERGY 2019年 168卷 247-260页

作者： Arabkoohsar, A. Andresen, G. B. Aalborg Univ Dept Energy Technol Aalborg Denmark Aarhus Univ Dept Engn Aarhus Denmark

Subcooled compressed air energy storage (SCAES) is a system cogenerating heat, cooling, and power at a high coefficient of performance. In this study, hybridization of a SCAES system with a large-scale solar powered absorption chiller (SPAC) is proposed. The hybrid system sustainably provides cooling and power at high efficiency. The combined SPAC-SCAES system is appropriate for locations with large cooling demand and grid-connected renewable power plants. Employing this system, the renewable power plant may efficiently operate in the power market, maximizing the financial benefits by storing its surplus power and reclaiming the stored energy for balancing the demand and the production. In addition, a large amount of cold is produced, increasing the profitability of the system. This combined system is designed and simulated for a typical wind farm plus an absorption chiller of a hospital. nonlinear programming (NLP) is used to optimize the operation strategy of the SCAES and based on the given results;the components of the system are sized. The results show that by the combined system a massive amount of balancing power can be produced for the grid, a reliable integration between the cold and electricity sectors is made, and the levelized cost of energy (LCOE) decreases remarkably. (C) 2018 Elsevier Ltd. All rights reserved.

关键词： Subcooled CAES Solar-powered absorption chiller Wind farm Trigeneration non-linear programming

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Vendor performance with supply risk: A chance-constrained DEA approach

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INTERNATIONAL JOURNAL OF PRODUCTION ECONOMICS 2006年第2期100卷 212-222页

作者： Talluri, S Narasimhan, R Nair, A Michigan State Univ Dept Marketing & Supply Chain Management Eli Braod Coll Business E Lansing MI 48824 USA Business Complex E Lansing MI 48824 USA Auburn Univ Coll Business Auburn AL 36849 USA

The strategic importance of vendor evaluation is well established in the purchasing literature. Several evaluation methodologies that consider multiple performance attributes have been proposed for vendor evaluation purposes. While these techniques range from scoring models that utilize prior articulation of weights to derive composite scores for vendors to advanced mathematical models, methods that incorporate the inherent variability in vendor's performance attributes have been limited. The primary reason for the lack of development of such models is due to the complexities associated with stochastic approaches. In order to more accurately evaluate the performance of vendors, it is critical to consider variability in vendor attributes. This paper is an attempt to fill this void in vendor evaluation models by presenting a chance-constrained data envelopment analysis (CCDEA) approach in the presence of multiple performance measures that are uncertain. Our paper effectively demonstrates the first application of CCDEA in the area of purchasing, in general, and vendor evaluation, in particular. The model is demonstrated by applying it to a previously reported dataset from a pharmaceutical company. (c) 2004 Elsevier B.V. All rights reserved.

关键词： chance-constrained programming non-linear programming purchasing stochastic data envelopment analysis

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An SLA and power-saving scheduling consolidation strategy for shared and heterogeneous clouds

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JOURNAL OF SUPERCOMPUTING 2015年第5期71卷 1817-1832页

作者： Vilaplana, Jordi Mateo, Jordi Teixido, Ivan Solsona, Francesc Gine, Francesc Roig, Concepcio Univ Lleida Dept Comp Sci Lleida 25001 Spain Univ Lleida INSPIRES Lleida 25001 Spain

This paper presents a power-aware scheduling policy algorithm of Virtual Machines into nodes called Green Cloud (GreenC) for Heterogeneous cloud systems. GreenC takes into account optimal assignments according to physical and virtual machine heterogeneity, the current host workload and communication between the different virtual machines. An initial test case has been performed by modelling the policies to be executed by a solver that demonstrates the applicability of our proposal for saving energy and also guaranteeing the QoS. The proposed policy has been implemented using the OpenStack software and the obtained results showed that energy consumption can be significantly lowered by applying GreenC to allocate virtual machines to physical hosts.

关键词： Green cloud computing SLA Power-aware scheduling non-linear programming

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Real-time optimization flow control

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COMPUTER NETWORKS 2010年第5期54卷 797-810页

作者： Dalalah, Doraid Jordan Univ Sci & Technol Fac Engn Dept Ind Engn Irbid 22110 Jordan

In this paper, we propose a dynamic optimization approach to end-to-end flow control in data networks. The objective is to maximize the aggregate utilities of the data sources over soft transmission rate bounds and delay constraints. The network links and data sources are considered as processors of a distributed computational system that has a global objective function. The presented model works with different shapes of utility curves under the proposition of elastic data traffic. The approach relies on real-time observations of the delay as a measure of the data network congestion at the routers (network nodes). A primal-dual algorithm carried out by the data sources is used to solve the optimization problem in a decentralized manner. The calculated transmission rates are bounded and the sources are subjected to a maximum number of data packets that can be queued downstream of each transmission session. The algorithm solves for the rates without the access to any network global information while each source calculates its transmission rate that should maximize the global objective function. The calculated optimal rates conform to rate-to-queue proportionality. Finally, we present an extensive simulation results to demonstrate the reliability of the algorithm. (C) 2009 Elsevier B.V. All rights reserved.

关键词： Data networks Flow control Optimization non-linear programming Duality

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Energy management system for enhanced resiliency of microgrids during islanded operation

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ELECTRIC POWER SYSTEMS RESEARCH 2016年 137卷 133-141页

作者： Balasubramaniam, Karthikeyan Saraf, Parimal Hadidi, Ramtin Makram, Elham B. Clemson Univ Holcombe Dept Elect & Comp Engn Clemson SC USA Clemson Univ Restorat Inst Charleston SC USA

This paper proposes a method to enhance resiliency of microgrids through survivability. Survivability in this context is to minimize load shed for the duration the microgrid is in islanded mode following a disturbance event. During islanded operation, microgrid loads are prioritized as critical and non-critical loads. The key decision is to ascertain whether to provide energy to non-critical loads after supplying the critical loads or to store excess energy for future dispatches. This task is formulated as a non-linear programming problem. The objective is to minimize the amount of critical load shed while maximizing the amount of non-critical load served for a projected restoration time while adhering to relevant operational and physical constraints. For this extended time-scale problem, uncertainty of renewable generation and load forecast is quantified with probability distribution and confidence levels are used to establish likelihood of forecast error. Distributed generation such as solar and wind farm along with battery energy storage system are modeled. Demand response is implemented through adjustable loads and a fleet of plug in hybrid electric vehicles that can be operated in both grid to vehicle and vehicle to grid mode. Test cases are studied on a modified CIGRE microgrid benchmark test system and results are compared with a temporal decomposition scheme based energy management system. (C) 2016 Elsevier B.V. All rights reserved.

关键词： Demand response Energy management system Load shedding Microgrid non-linear programming Resilience

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