Search results for: circular restricted three-body problem (CRTBP)

Authors: Çağrı Özgün Kibiroğlu, Zeynep Turgut

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This paper considers a hub location problem where the network service area partitioned into predetermined zones (represented by node clusters is given) and potential hub nodes capacity levels are determined a priori as a selection criteria of hub to investigate congestion effect on network. The objective is to design hub network by determining all required hub locations in the node clusters and also allocate non-hub nodes to hubs such that the total cost including transportation cost, opening cost of hubs and penalty cost for exceed of capacity level at hubs is minimized. A mixed integer linear programming model is developed introducing additional constraints to the traditional model of capacitated multiple allocation hub location problem and empirically tested.

Keywords: hub location problem, p-hub median problem, clustering, congestion

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Authors: Masoud Mahdavi

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The use of sloping lands is increasing due to the reduction of suitable lands for the construction of buildings. In the design and construction of buildings on sloping lands, the foundation has special loading conditions that require the designer and executor to use the slopped foundation. The creation of underground cavities, including urban and subway tunnels, sewers, urban facilities, etc., inside the ground, causes the behavior of the foundation to be unknown. In the present study, using Abacus software, a 45-degree stepped foundation on the ground is designed. The foundations are placed on the ground in a cohesive (no-hole) manner with circular cavities that show the effect of increasing the cross-sectional area of ​​the underground cavities on the foundation's performance. The Kobe earthquake struck the foundation and ground for two seconds. The underground cavities have a circular cross-sectional area with a radius of 5 m, which is located at a depth of 22.54 m above the ground. The results showed that as the number of underground cavities increased, von Mises stress (in the vertical direction) increased. With the increase in the number of underground cavities, the plastic strain on the ground has increased. Also, with the increase in the number of underground cavities, the change in location and speed in the foundation has increased.

Keywords: stepped foundation, sloping ground, Kobe earthquake, Abaqus software, underground excavations

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Authors: Geetha Baskaran, Andrzej Barjiela, Rong Qu

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Motivation: Nurse scheduling is a complex combinatorial optimization problem. It is also known as NP-hard. It needs an efficient re-scheduling to minimize some trade-off of the measures of violation by reducing selected constraints to soft constraints with measurements of their violations. Problem Statement: In this paper, we extend our novel approach to solve the nurse scheduling problem by transforming it through Information Granulation. Approach: This approach satisfies the rules of a typical hospital environment based on a standard benchmark problem. Generating good work schedules has a great influence on nurses' working conditions which are strongly related to the level of a quality health care. Domain transformation that combines the strengths of operation research and artificial intelligence was proposed for the solution of the problem. Compared to conventional methods, our approach involves judicious grouping (information granulation) of shifts types’ that transforms the original problem into a smaller solution domain. Later these schedules from the smaller problem domain are converted back into the original problem domain by taking into account the constraints that could not be represented in the smaller domain. An Integer Programming (IP) package is used to solve the transformed scheduling problem by expending the branch and bound algorithm. We have used the GNU Octave for Windows to solve this problem. Results: The scheduling problem has been solved in the proposed formalism resulting in a high quality schedule. Conclusion: Domain transformation represents departure from a conventional one-shift-at-a-time scheduling approach. It offers an advantage of efficient and easily understandable solutions as well as offering deterministic reproducibility of the results. We note, however, that it does not guarantee the global optimum.

Keywords: domain transformation, nurse scheduling, information granulation, artificial intelligence, simulation

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Authors: Mohammadali Abedini Sanigy, Jiangang Fei

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In this paper, a mathematical optimization model was developed to maximize the profit in a vegetable production planning problem. It serves as a decision support system that assists farmers in land allocation to crops and harvest scheduling decisions. The developed model can handle different rotation rules in two consecutive cycles of production, which is a common practice in organic production system. Moreover, different production methods of the same crop were considered in the model formulation. The main strength of the model is that it is not restricted to predetermined production periods, which makes the planning more flexible. The model is classified as a mixed integer programming (MIP) model and formulated in PYOMO -a Python package to formulate optimization models- and solved via Gurobi and CPLEX optimizer packages. The model was tested with secondary data from 'Australian vegetable growing farms', and the results were obtained and discussed with the computational test runs. The results show that the model can successfully provide reliable solutions for real size problems.

Keywords: crop rotation, harvesting, mathematical model formulation, vegetable production

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Authors: Susanna Vanhamäki, Gabor Schneider, Kati Manskinen

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‘Bioeconomy’ is a complex concept that cuts across many sectors and covers several policy areas. To achieve an overall understanding and support a successful bioeconomy, a cross-sectorial approach is necessary. In practice, due to the concept’s wide scope and varying international approaches, fully understanding bioeconomy is challenging on policy level. This paper provides a background of the topic through an analysis of bioeconomy strategies in the Baltic Sea region. Expert interviews and a small survey were conducted to discover the current and intended focuses of these countries’ bioeconomy sectors. The research shows that supporting sustainability is one of the keys in developing the future bioeconomy. The results highlighted that the bioeconomy has to be sustainable and based on circular economy principles. Currently, traditional bioeconomy sectors like food, wood, fish & waters as well as fuel & energy, which are in the core of national bioeconomy strategies, are best known and are considered more relevant than other bioeconomy industries. However, there is increasing potential for novel sectors, such as textiles and pharmaceuticals. The present research indicates that the opportunities presented by these bioeconomy sectors should be recognised and promoted. Education, research and innovation can play key roles in developing transformative and sustainable improvements in primary production and renewable resources. Furthermore, cooperation between businesses and educators is important.

Keywords: bioeconomy, circular economy, policy, strategy

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Authors: Sanam Haseen, Abdul Bari

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In this paper a three stage multivariate programming problem with random survey cost and variances as random variables has been formulated as a non-linear stochastic programming problem. The problem has been converted into an equivalent deterministic form using chance constraint programming and modified E-modeling. An empirical study of the problem has been done at the end of the paper using R-simulation.

Keywords: chance constraint programming, modified E-model, stochastic programming, stratified sample surveys, three stage sample surveys

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Authors: Iveta Nováková, Martin-Andrè S. Husby, Boy-Arne Buyle

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The building industry has one of the most significant contributions to global warming due to the production of building materials, transportation, building activities, and demolition of structures when they reach the end of their life. Implementation of circular material flow and circular economy can significantly reduce greenhouse gasses and simultaneously reduce the need for natural resources. The use of recycled concrete aggregates (RCA) is one of the possibilities for reducing the depletion of raw materials for concrete production. Concrete is the most used building material worldwide, and aggregates constitute 70% of its volume. RCA can replace a certain amount of natural aggregates (NA), and concrete will still perform as required. The aim of this scientific paper is to evaluate RCA properties with and without mechanical treatment. Analysis of RCA itself will be followed by compressive strength of concrete containing various amounts of treated and non-treated RCA. Results showed improvement in compressive strength of the mix with mechanically treated RCA compared to standard RCA, and even the strength of concrete with mechanically treated RCA in dose 50% of coarse aggregates was higher than the reference mix by 4%. Based on obtained results, it can be concluded that integration of RCA in industrial concrete production is feasible, at a replacement ratio of 50% for mechanically treated RCA and 30% if untreated RCA is used, without affecting the compressive strength negatively.

Keywords: recycled concrete aggregates, mechanical treatment, aggregate properties, compression strength

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Authors: Abu Hashan Md Mashud, M. Sharif Uddin, Aminur Rahman Khan

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In this paper, we formulate a new problem as a linear programming and Integer Programming problem and maximize profit within the limited budget and limited resources based on the construction of a tea garden problem. It describes a new idea about how to optimize profit and focuses on the practical aspects of modeling and the challenges of providing a solution to a complex real life problem. Finally, a comparative study is carried out among Graphical method, Simplex method and Branch and bound method.

Keywords: integer programming, tea garden, graphical method, simplex method, branch and bound method

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Authors: Mohamed Rajab Peer Mohamed, Thiruvenkatasamy Kannabiran

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In the present investigation, the scour around a circular pier subjected to a steady current were studied numerically using two-dimensional MIKE21 Flow Model (FM) and Sand Transport (ST)Modulewhich is developed by Danish Hydraulic Institute (DHI), Denmark. The unstructured flexible mesh generated with rectangular flume dimension of 10 m wide, 1 m deep, and 30 m long. The grain size of the sand was d50 = 0.16 mm, sediment size, sediment gradation=1.16, pier diameter D= 30 mm and depth-averaged current velocity, U = 0.449 m/s are considered in the model. The estimated scour depth obtained from this model is validated and it is observed that the results of the model have good agreement with flume experimental results.In order to estimate the scour depth, several simulations were made for three cases viz., Case I:change in sediment transport model description in the numerical model viz, i) Engelund-Hansen model, ii) Engelund-Fredsøe model, and iii) Van Rijn model, Case II: change in current velocity for keeping constant pile diameter D=0.03 m and Case III:change in pier diameter for constant depth averaged current speed U=0.449 m/s.In case I simulations, the results indicate that the scour depth S/D is the order of 1.73 for Engelund-Hansen model, 0.64 for Engelund-Fredsøe model and 0.46 for VanRijn model. The scour depth estimates using Engelund-Hansen method compares well the experimental results.In case II, simulations show that the scour depth increases with increasing current component of the flow.In case III simulations, the results indicate that the scour depth increases with increase in pier diameter and it stabilize attains steady value when the Froude number> 2.71.All the results of the numerical simulations are clearly matches with reported values of the experimental results. Hence, this MIKE21 FM –Sand Transport model can be used as a suitable tool to estimate the scour depth for field applications. Moreover, to provide suitable scour protection methods, the maximum scour depth is to be predicted, Engelund-Hansen method can be adopted to estimate the scour depth in the steady current region.

Keywords: circular pier, MIKE21, numerical model, scour, sediment transport

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Authors: Choi Duckkyu, Choi Yong, Kang Taegyoung, Jun Hyeonjong, Choi Ilsu, Hyun Changsik

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This study was carried out to develop a soybean combine thresher that enables to reduce the damage rate of soybean threshing and the rate of unthreshing. The combine threshing cylinder was developed with 6 circular axis at each end and fixed with disc plates. It was attached to the prototype combine thresher. A combine thresher that has a cylinder with circular rod type threshing pegs was used for a comparative test. A series of comparative tests were conducted using dae-won soybean. The test of the soybean thresher was performed at the cylinder speeds of 210, 240, 270 and 300 rpm, and with the concave clearance of 10, 13 and 16 mm. The separating positions of soybean after threshing were researched on a separate box with 4 sections. The soybean positions of front, center, rear and rear outside, of 59.5%, 30.6%, 7.8% and 2.2% respectively, were obtained. At the cylinder speeds from 210 rpm to 300 rpm, the damage rate of soybean was increased from 0.1% to 4.2% correspondingly to speeds. The unthreshed rate of soybean under the same condition was increased from 0.9% to 4.1% correspondingly to speeds. 0.7% of the damage rate and 1.5% of the unthreshed rate was achieved at the cylinder speed of 240 rpm and with the concave clearance of 10 mm. For Daewon soybean, an optimum cylinder speed of 240 rpm and the concave clearance of 10 mm were identified. These results will be useful for the design, construction, and operation of soybean threshing harvesters.

Keywords: soybean harvest, combine threshing, threshing cylinder, optimum design

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Authors: Abdolsalam Ghaderi

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In this paper, the single-depot capacitated location-routing problem under uncertainty is presented. The problem aims to find the optimal location of a single depot and the routing of vehicles to serve the customers when the parameters may change under different circumstances. This problem has many applications, especially in the area of supply chain management and distribution systems. To get closer to real-world situations, travel time of vehicles, the fixed cost of vehicles usage and customers’ demand are considered as a source of uncertainty. A combined approach including robust optimization and stochastic programming was presented to deal with the uncertainty in the problem at hand. For this purpose, a mixed integer programming model is developed and a heuristic algorithm based on Variable Neighborhood Search(VNS) is presented to solve the model. Finally, the computational results are presented and future research directions are discussed.

Keywords: location-routing problem, robust optimization, stochastic programming, variable neighborhood search

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Authors: Liudmila A.Guzikova

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Being federative state Russia includes more than 80 subjects which are widely diverse by climatic conditions, demographic characteristics, cultural traditions, intensity of migration, economic development and investment attraction and other parameters. Now, in the regions of the country all forms of housing problem are present - housing mismatch to sanitary and hygienic standards, overcrowding, forced residence in financially burdensome housing, homelessness, -although the extent of these symptoms varies widely. Heterogeneity of regional conditions in combination with specifics of regional housing situation requires to concentrate the study of housing problem on the regional level. Traditionally housing market and mortgage are considered as the instruments of housing problem solving. The question arises how the housing market and mortgage market contribute to solving the housing problem in the regions of Russia. Though the purchase of dwelling in ownership should not be regarded as a universal method of the housing problem solving, the purchase of dwelling both by own funds or by use of mortgage can reduce the problem and enhance public satisfaction of living conditions. The aim of the study is to identify differences and similarities in the development of regional housing markets and mortgage lending in the regions of Russia and to evaluate their impact on the status of the housing problem. To achieve the aim of the study the methods of correlation and regression analysis are used. The data of federal statistics constitutes the information base of research. The results of the study contribute to better understanding of the interrelations in housing sphere and can be used to work out social and economic development programs in the regions.

Keywords: housing market, housing problem, mortgage, regional economy

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Authors: Panatda Intanin, Sangutid Thongsawad, Chirapha Tannanonta, Todsaporn Fuangrod

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Stereotactic radiosurgery (SRS) is a highly precision delivery technique that requires comprehensive quality assurance (QA) tests prior to treatment delivery. An isocenter of delivery beam plays a critical role that affect the treatment accuracy. The uncertainty of isocenter is traditionally accessed using circular cone equipment, Winston-Lutz (WL) phantom and film. This technique is considered time consuming and highly dependent on the observer. In this work, the development of multileaf collimator (MLC)-based isocenter verification tool using electronic portal imaging device (EPID) was proposed and evaluated. A mechanical isocenter alignment with ball bearing diameter 5 mm and circular cone diameter 10 mm fixed to gantry head defines the radiation field was set as the conventional WL test method. The conventional setup was to compare to the proposed setup; using MLC (10 x 10 mm) to define the radiation filed instead of cone. This represents more realistic delivery field than using circular cone equipment. The acquisition from electronic portal imaging device (EPID) and radiographic film were performed in both experiments. The gantry angles were set as following: 0°, 90°, 180° and 270°. A software tool was in-house developed using MATLAB/SIMULINK programming to determine the centroid of radiation field and shadow of WL phantom automatically. This presents higher accuracy than manual measurement. The deviation between centroid of both cone-based and MLC-based WL tests were quantified. To compare between film and EPID image, the deviation for all gantry angle was 0.26±0.19mm and 0.43±0.30 for cone-based and MLC-based WL tests. For the absolute deviation calculation on EPID images between cone and MLC-based WL test was 0.59±0.28 mm and the absolute deviation on film images was 0.14±0.13 mm. Therefore, the MLC-based isocenter verification using EPID present high sensitivity tool for SRS QA.

Keywords: isocenter verification, quality assurance, EPID, SRS

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Authors: Taehan Lee

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We consider a network design problem which has shortest routing restriction based on the values determined by the installed facilities on each arc. In conventional multicommodity network design problem, a commodity can be routed through any possible path when the capacity is available. But, we consider a problem in which the commodity between two nodes must be routed on a path which has shortest metric value and the link metric value is determined by the installed facilities on the link. By this routing restriction, the problem has a distinct characteristic. We present an integer programming formulation containing the primal-dual optimality conditions to the shortest path routing. We give some computational results for the model.

Keywords: integer programming, multicommodity network design, routing, shortest path

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Authors: Ward Brullot, Thierry Verbiest

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Nonreciprocal optical effects, such as Faraday rotation or magnetic circular dichroism, are very useful both for fundamental studies as for applications such as magnetic field sensors or optical isolators. In this study, we developed layer-by-layer deposited 20nm thick plasmonic nanoparticle aggregates consisting of gold, silver and magnetite nanoparticles that show broadband nonreciprocal asymmetric transmission. As such, the optical transmittance, or absorbance, depends on the direction of light propagation in the material, which means that looking from one direction or the other, more or less light passes through the sample. Theoretical analysis showed that strong electric quadrupole fields, which are electric field gradients, occur in the aggregates and that these quadrupole fields are responsible for the observed asymmetric transmission and the nonreciprocity of the effect. Apart from nonreciprocal asymmetric transmission, also other effects such as, but not limited to, optical rotation, circular dichroism or nonlinear optical responses were measured in the plasmonic nanoparticle aggregates and the influences of the intense electric quadrupole fields determined. In conclusion, the presence of strong electric quadrupole fields make the developed plasmonic nanoparticle aggregates ideal candidates for the study and application of various nonreciprocal optical effects.

Keywords: asymmetric transmission, electric quadrupoles, nanoparticle aggregates, nonreciprocity

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Authors: Busaba Phurksaphanrat

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This research proposes a pre-emptive fuzzy goal programming model for multi-objective multi-mode resource constrained project scheduling problem. The objectives of the problem are minimization of the total time and the total cost of the project. Objective in a multi-mode resource-constrained project scheduling problem is often a minimization of make-span. However, both time and cost should be considered at the same time with different level of important priorities. Moreover, all elements of cost functions in a project are not included in the conventional cost objective function. Incomplete total project cost causes an error in finding the project scheduling time. In this research, pre-emptive fuzzy goal programming is presented to solve the multi-objective multi-mode resource constrained project scheduling problem. It can find the compromise solution of the problem. Moreover, it is also flexible in adjusting to find a variety of alternative solutions.

Keywords: multi-mode resource constrained project scheduling problem, fuzzy set, goal programming, pre-emptive fuzzy goal programming

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Authors: Sharon-Yasotha Veerayah-Mcgregor, Valipuram Manoranjan

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A backward or inverse problem is known to be an ill-posed problem due to its instability that easily emerges with any slight change within the conditions of the problem. Therefore, only a limited number of numerical approaches are available to solve a backward problem. This paper considers the Nagumo equation, an equation that describes impulse propagation in nerve axons, which also models population growth with the Allee effect. A creative operator splitting numerical scheme is constructed to solve the inverse Nagumo equation. Computational simulations are used to verify that this scheme is stable, accurate, and efficient.

Keywords: inverse/backward equation, operator-splitting, Nagumo equation, ill-posed, finite-difference

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Authors: Mazharuddin Syed Ahmed

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This research presents a framework used to develop The Ara Polytechnic College of Architecture Studies building “Kahukura” which is Green Building certified. This framework integrates the development of a smart building digital twin by utilizing Building Information Modelling (BIM) and its BIM maturity levels, including Levels of Development (LOD), eight dimensions of BIM, Heritage-BIM (H-BIM) and Facility Management BIM (FM BIM). The research also outlines a structured approach to building performance analysis and integration with the circular economy, encapsulated within a five-level digital twin framework. Starting with Level 1, the Descriptive Twin provides a live, editable visual replica of the built asset, allowing for specific data inclusion and extraction. Advancing to Level 2, the Informative Twin integrates operational and sensory data, enhancing data verification and system integration. At Level 3, the Predictive Twin utilizes operational data to generate insights and proactive management suggestions. Progressing to Level 4, the Comprehensive Twin simulates future scenarios, enabling robust “what-if” analyses. Finally, Level 5, the Autonomous Twin, represents the pinnacle of digital twin evolution, capable of learning and autonomously acting on behalf of users.

Keywords: building information modelling, circular economy integration, digital twin, predictive analytics

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Authors: Bastian Vollrath, Hartwig Hubel

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In case of over-elastic and cyclic loading, strain may accumulate due to a ratcheting mechanism until the state of shakedown is possibly achieved. Load history dependent numerical investigations by a step-by-step analysis are rather costly in terms of engineering time and numerical effort. In the case of multi-parameter loading, where various independent loadings affect the final state of shakedown, the computational effort becomes an additional challenge. Therefore, direct methods like the Simplified Theory of Plastic Zones (STPZ) are developed to solve the problem with a few linear elastic analyses. Post-shakedown quantities such as strain ranges and cyclic accumulated strains are calculated approximately by disregarding the load history. The STPZ is based on estimates of a transformed internal variable, which can be used to perform modified elastic analyses, where the elastic material parameters are modified, and initial strains are applied as modified loading, resulting in residual stresses and strains. The STPZ already turned out to work well with respect to cyclic loading between two states of loading. Usually, few linear elastic analyses are sufficient to obtain a good approximation to the post-shakedown quantities. In a multi-dimensional load domain, the approximation of the transformed internal variable transforms from a plane problem into a hyperspace problem, where time-consuming approximation methods need to be applied. Therefore, a solution restricted to structures with four stress components was developed to estimate the transformed internal variable by means of three-dimensional vector algebra. This paper presents the extension to cyclic multi-parameter loading so that an unlimited number of load cases can be taken into account. The theoretical basis and basic presumptions of the Simplified Theory of Plastic Zones are outlined for the case of elastic shakedown. The extension of the method to many load cases is explained, and a workflow of the procedure is illustrated. An example, adopting the FE-implementation of the method into ANSYS and considering multilinear hardening is given which highlights the advantages of the method compared to incremental, step-by-step analysis.

Keywords: cyclic loading, direct method, elastic shakedown, multi-parameter loading, STPZ

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Authors: Judit Manuel-i-Martin, Mechthild Donner, Ivana Radic, Yamna Erraach, Fatima Elhadad, Taoufik Yatribi, Feliu Lopez-i-Gelats

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This paper investigates how small olive farmers and olive oil producers implement circular economy practices to manage olive related waste and how such strategies are perceived by the farmers themselves. While there is a lot of data and research about possible uses of olive oil by-products, the perceptions and related practices of olive oil farmers is a much less investigated domain. A total of 60 semi-structured interviews were conducted in one of the most relevant olive oil producing regions in the Iberian Peninsula -the region of Terres de Ponent (Catalonia – Spain) - to examine the different by-product valorization strategies the olive oil farms develop. We test the hypothesis that the strategies conducted depend on the nature and amount of resources available by the farm. The results obtained point that access to milling infrastructure is a determining factor. We also found that olive tree pruning biomass and olive pomace are the most common by-products valorized by farmers, the first one on-farm and the latter in mills. Results indicate that high value uses for olive oil by-products are rarely implemented by farmers. We conclude that olive farmers tend to perceive by-product valorization strategies as waste management practices rather than as additional sources of value for their farm.

Keywords: circular economy, discourses, Mediterranean region, olive oil by-products, farmers’ strategies, olive pomace

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Authors: Mauricio Becerra Fernández, Olga Rosana Romero Quiroga, Elsa Cristina González La Rotta

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The logistics facilities design and construction is one of the strategic decisions that critically affects the performance of the company, from the economic perspective and relationship with customers. The case study company is the Colombian logistic sector leader, with over 60 years of experience, with sales of about one hundred twenty million dollars at the end of 2014. The preliminary design for the warehouse layout and operation includes a customer that provides approximately 17% of the profits of the company, considering the possibility of moving two forklifts in the warehouse halls. Some changes were not consider in previous stages of design, operations required forklift with different characteristics, whose size, do not allow the circulation of more than a forklift at a time. Therefore, it is necessary to assess the impact of this restriction on the warehouse operation, so decision makers implement actions to achieve efficient operation. The problem is addressed by recognizing logistics processes, which develop in a warehouse, collection of processes information behavior, the simulation of the current situation using ProModel software, model validation, making adjustments required, experiments design, conclusions and recommendations for the company.

Keywords: design, discrete events simulation, forklift allocation, logistics facilities, warehouse

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Authors: Mourad Hrizi

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In this paper, we study the inverse problem of reconstructing an interior interface D appearing in the elliptic partial differential equation: Δu+χ(D)u=0 from the knowledge of the boundary measurements. This problem arises from a semiconductor transistor model. We propose a new shape reconstruction procedure that is based on the Kohn-Vogelius formulation and the topological sensitivity method. The inverse problem is formulated as a topology optimization one. A topological sensitivity analysis is derived from a function. The unknown subdomain D is reconstructed using a level-set curve of the topological gradient. Finally, we give several examples to show the viability of our proposed method.

Keywords: inverse problem, topological optimization, topological gradient, Kohn-Vogelius formulation

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Authors: Sie Long Kek, Wah June Leong, Kok Lay Teo

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Linear quadratic Gaussian model is a standard mathematical model for the stochastic optimal control problem. The combination of the linear quadratic estimation and the linear quadratic regulator allows the state estimation and the optimal control policy to be designed separately. This is known as the separation principle. In this paper, an efficient computational method is proposed to solve the linear quadratic Gaussian problem. In our approach, the Hamiltonian function is defined, and the necessary conditions are derived. In addition to this, the output error is defined and the least-square optimization problem is introduced. By determining the first-order necessary condition, the gradient of the sum squares of output error is established. On this point of view, the stochastic approximation approach is employed such that the optimal control policy is updated. Within a given tolerance, the iteration procedure would be stopped and the optimal solution of the linear-quadratic Gaussian problem is obtained. For illustration, an example of the linear-quadratic Gaussian problem is studied. The result shows the efficiency of the approach proposed. In conclusion, the applicability of the approach proposed for solving the linear quadratic Gaussian problem is highly demonstrated.

Keywords: iteration procedure, least squares solution, linear quadratic Gaussian, output error, stochastic approximation

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Authors: Atefeh Salehipoor

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Textiles play a vital role in human life, particularly in the form of clothing. However, the alarming rate at which textiles end up in landfills presents a significant environmental risk. With approximately one garbage truck per second being filled with discarded textiles, urgent measures are required to mitigate this trend. Governments and responsible organizations are calling upon various stakeholders to shift from a linear economy to a circular economy model in the textile industry. This article highlights several key approaches that can be undertaken to address this pressing issue. These approaches include the creation of renewable raw material sources, rethinking production processes, maximizing the use and reuse of textile products, implementing reproduction and recycling strategies, exploring redistribution to new markets, and finding innovative means to extend the lifespan of textiles. However, the rapid accumulation of textiles in landfills poses a significant threat to the environment. This article explores the urgent need for the textile industry to transition from a linear economy model to a circular economy model. The linear model, characterized by the creation, use, and disposal of textiles, is unsustainable in the long term. By adopting a circular economy approach, the industry can minimize waste, reduce environmental impact, and promote sustainable practices. This article outlines key approaches that can be undertaken to drive this transition. Approaches to Address Environmental Challenges: 1. Creation of Renewable Raw Materials Sources: Exploring and promoting the use of renewable and sustainable raw materials, such as organic cotton, hemp, and recycled fibers, can significantly reduce the environmental footprint of textile production. 2. Rethinking Production Processes: Implementing cleaner production techniques, optimizing resource utilization, and minimizing waste generation are crucial steps in reducing the environmental impact of textile manufacturing. 3. Maximizing Use and Reuse of Textile Products: Encouraging consumers to prolong the lifespan of textile products through proper care, maintenance, and repair services can reduce the frequency of disposal and promote a culture of sustainability. 4. Reproduction and Recycling Strategies: Investing in innovative technologies and infrastructure to enable efficient reproduction and recycling of textiles can close the loop and minimize waste generation. 5. Redistribution of Textiles to New Markets: Exploring opportunities to redistribute textiles to new and parallel markets, such as resale platforms, can extend their lifecycle and prevent premature disposal. 6. Improvising Means to Extend Textile Lifespan: Encouraging design practices that prioritize durability, versatility, and timeless aesthetics can contribute to prolonging the lifespan of textiles. Conclusion The textile industry must urgently transition from a linear economy to a circular economy model to mitigate the adverse environmental impact caused by textile waste. By implementing the outlined approaches, such as sourcing renewable raw materials, rethinking production processes, promoting reuse and recycling, exploring new markets, and extending the lifespan of textiles, stakeholders can work together to create a more sustainable and environmentally friendly textile industry. These measures require collective action and collaboration between governments, organizations, manufacturers, and consumers to drive positive change and safeguard the planet for future generations.

Keywords: textiles, circular economy, environmental challenges, renewable raw materials, production processes, reuse, recycling, redistribution, textile lifespan extension

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Authors: Wuthichai Wongthatsanekorn, Nuntana Matheekrieangkrai

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This research proposes Bee Algorithm (BA) to optimize Ready Mixed Concrete (RMC) truck scheduling problem from single batch plant to multiple construction sites. This problem is considered as an NP-hard constrained combinatorial optimization problem. This paper provides the details of the RMC dispatching process and its related constraints. BA was then developed to minimize total waiting time of RMC trucks while satisfying all constraints. The performance of BA is then evaluated on two benchmark problems (3 and 5construction sites) according to previous researchers. The simulation results of BA are compared in term of efficiency and accuracy with Genetic Algorithm (GA) and all problems show that BA approach outperforms GA in term of efficiency and accuracy to obtain optimal solution. Hence, BA approach could be practically implemented to obtain the best schedule.

Keywords: bee colony optimization, ready mixed concrete problem, ruck scheduling, multiple construction sites

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Authors: Alaka Padhye, S. P. Kane

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The following study considers some variations made to the secretary problem (SP). In a multiple criteria secretary problem (MCSP), the selection of a unit is based on two independent characteristics. The units that appear before an observer are known say N, the best rank of a unit being N. A unit is selected, if it is better with respect to either first or second or both the characteristics. When the number of units is large and due to constraints like time and cost, the observer might want to stop earlier instead of inspecting all the available units. Let the process terminate at r2th unit where r1Keywords: joint distribution, marginal distribution, real ranks, secretary problem, selection criterion, two tailed secretary problem

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Authors: Mette Dalgaard Nielsen

Abstract:

The paper serves the purpose of providing an eco-systemic typology of fashion resale business models in Denmark while pointing to possibilities to learn from its wisdom during a time when a fundamental break with the dominant linear fashion paradigm has become inevitable. As we transgress planetary boundaries and can no longer continue the unsustainable path of over-exploiting the Earth’s resources, the global fashion industry faces a tremendous need for change. One of the preferred answers to the fashion industry’s sustainability crises lies in the circular economy, which aims to maximize the utilization of resources by keeping garments in use for longer. Thus, in the context of fashion, resale business models that allow pre-owned garments to change hands with the purpose of being reused in continuous cycles are considered to be among the most efficient forms of circularity. Methodologies: The paper is based on empirical data from an ongoing project and a series of qualitative pilot studies that have been conducted on the Danish resale market over a 2-year time period from Fall 2021 to Fall 2023. The methodological framework is comprised of (n) ethnography and fieldwork in selected resale environments, as well as semi-structured interviews and a workshop with eight business partners from the Danish fashion and textiles industry. By focusing on the real-world circulation of pre-owned garments, which is enabled by the identified resale business models, the research lets go of simplistic hypotheses to the benefit of dynamic, vibrant and non-linear processes. As such, the paper contributes to the emerging research field of circular economy and fashion, which finds itself in a critical need to move from non-verified concepts and theories to empirical evidence. Findings: Based on the empirical data and anchored in the business partners, the paper analyses and presents five distinct resale business models with different product, service and design characteristics. These are 1) branded resale, 2) trade-in resale, 3) peer-2-peer resale, 4) resale boutiques and consignment shops and 5) resale shelf/square meter stores and flea markets. Together, the five business models represent a plurality of resale-promoting business model design elements that have been found to contribute to the circulation of pre-owned garments in various ways for different garments, users and businesses in Denmark. Hence, the provided typology points to the necessity of prioritizing several rather than single resale business model designs, services and initiatives for the resale market to help reconfigure the linear fashion model and create a circular-ish future. Conclusions: The article represents a twofold research ambition by 1) presenting an original, up-to-date eco-systemic typology of resale business models in Denmark and 2) using the typology and its eco-systemic traits as a tool to understand different business model design elements and possibilities to help fashion grow out of its linear growth model. By basing the typology on eco-systemic mechanisms and actual exemplars of resale business models, it becomes possible to envision the contours of a genuine alternative to business as usual that ultimately helps bend the linear fashion model towards circularity.

Keywords: circular business models, circular economy, fashion, resale, strategic design, sustainability

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Authors: Thorsten Herrmann, Alexander Laukemann, Hansgeorg Binz, Daniel Roth

Abstract:

For the analysis of already identified and existing problems, the pertinent literature provides a comprehensive collection of approaches as well as methods in order to analyze the problems in detail. But coming up with problems, which are assets worth pursuing further, is often challenging. However, the importance of well-formulated problem ideas and their influence of subsequent creative processes are incontestable and proven. In order to meet the covered challenges, the Institute for Engineering Design and Industrial Design (IKTD) developed the Emoji Method. This paper presents the Emoji Method, which support designers to generate problem ideas in a structured way. Considering research findings from knowledge management and innovation management, research into emojis and emoticons reveal insights by means of identifying and formulating problem ideas within the early design phase. The simple application and the huge supporting potential of the Emoji Method within the early design phase are only few of the many successful results of the conducted evaluation. The Emoji Method encourages designers to identify problem ideas and describe them in a structured way in order to start focused with generating solution ideas for the revealed problem ideas.

Keywords: emojis, problem ideas, innovation management, knowledge management

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Authors: J. Kaabi, Y. Harrath

Abstract:

This paper studied the flow shop scheduling problem under machine availability constraints. The machines are subject to flexible preventive maintenance activities. The nonresumable scenario for the jobs was considered. That is, when a job is interrupted by an unavailability period of a machine it should be restarted from the beginning. The objective is to minimize the total tardiness time for the jobs and the advance/tardiness for the maintenance activities. To solve the problem, a genetic algorithm was developed and successfully tested and validated on many problem instances. The computational results showed that the new genetic algorithm outperforms another earlier proposed algorithm.

Keywords: flow shop scheduling, genetic algorithm, maintenance, priority rules

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Authors: Agni Stylianou-Georgiou, Eliza Pitri

Abstract:

This study is a design narrative that discusses researchers’ new learning based on changes made in pedagogies and learning opportunities in the context of a Cognitive Psychology and an Art History undergraduate course. The purpose of this study was to investigate how to encourage creative problem-based play in tertiary education engaging instructors and student-teachers in designing educational games. Course instructors modified content to encourage flexible thinking during game design problem-solving. Qualitative analyses of data sources indicated that Thinking Birds’ questions could encourage flexible thinking as instructors engaged in creative problem-based play. However, student-teachers demonstrated weakness in adopting flexible thinking during game design problem solving. Further studies of student-teachers’ shifting perspectives during different instructional design tasks would provide insights for developing the Thinking Birds’ questions as tools for creative problem solving.

Keywords: creative problem-based play, educational games, flexible thinking, tertiary education

Procedia PDF Downloads 266