Artykuły (CN-dmms)

Permanent URI for this collectionhttps://repo.agh.edu.pl/handle/AGH/102785

Artykuły czasopisma Decision Making in Manufacturing and Services

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Access status: Open Access ,
Resource management in machine scheduling problems a survey
(2007) Janiak, Adam; Janiak, Władysław; Lichtenstein, Maciej
The paper is a survey devoted to job scheduling problems with resource allocation. We present the results available in the scientific literature for commonly used models of job processing times and job release dates, i.e., the models in which the job processing time or the job release date is given as a linear or convex function dependent on the amount of the additional resource allotted to the job. The scheduling models with resource dependent processing times or resource dependent release dates extend the classical scheduling models to reflect more precisely scheduling problems that appear in real life. Thus, in this paper we present the computational complexity results and solution algorithms that have been developed for this kind of problems.
Access status: Open Access ,
A Distributed Decision-Support System for Virtual Prototyping
(2007) Tirpak, Thomas M.; Lach, Lawrence E.; Xiao, Weimin; Lopez, Juan M.
Virtual Prototyping (VP) is a data-driven design process that promotes both knowledge reuse and innovation. High-profile applications in the automotive and aerospace industries have demonstrated its potential to significantly reduce prototype cycles, time to market, and total product cost. This paper addresses VP as a specialized application of Decision-Support Systems, and discusses common requirements for engineering design tools, as well as requirements specific to the design of electronic products, such as mobile phones. Motorola Labs' test bed for VP is introduced in terms of its open, agent-based architecture utilizing Java CORBA. One of the key principles of the VP System is the reuse of expert knowledge across multiple engineering domains. This is highlighted via several use cases, showing that the system can function not only as an Intranet-accessible repository of model services but also as an integral part of decision-making within the native CAD environment.
Access status: Open Access ,
Scheduling with high variety of customized compound products
(2007) Smutnicki, Czesław
Domestic appliance is an instance of manufacturing various products on clients demand with frequent changes of production. Although the technological process for each individual product is relatively simply, the variety of products, mixed orders, frequent machines changeovers, machines with unusual service policy, lack or limited storage, etc., generates quite nontrivial planning, batching and scheduling problems and furthermore of a huge size. In this paper, we present specific real process of production of refrigerators, mathematical and graph models of the problem and an outline of solution algorithm, based the on local search approach.
Access status: Open Access ,
The art and science of modeling decision-making under severe uncertainty
(2007) Sniedovich, Moshe
For obvious reasons, models for decision-making under severe uncertainty are austere. Simply put, there is precious little to work with under these conditions. This fact highlights the great importance of utilizing in such cases the ingredients of the mathematical model to the fullest extent, which in turn brings under the spotlight the art of mathematical modeling. In this discussion we examine some of the subtle considerations that are called for in the mathematical modeling of decision-making under severe uncertainty in general, and worst-case analysis in particular. As a case study we discuss the lessons learnt on this front from the Info-Gap experience.
Access status: Open Access ,
The errors-in-variable model in the optimal portfolio construction
(2007) Czapkiewicz, Anna; Machowska, Małgorzata
In the paper we consider a modification of Sharpe's method used in classical portfolio analysis for optimal portfolio building. The conventional theory assumes there is a linear relationship between asset's return and market portfolio return, while the influence of all the other factors is not included. We propose not to neglect them any more, but include them into a model. Since the factors in question are often hard to measure or even characterize, we treat them as a disturbances on random variables used by classical Sharpe's method. The key idea of the paper is the modification of the classical approach by application of the errors-in-variable model. We assume that both independent (market portfolio return) as well as dependent (given asset's return) variables are randomly distributed values related with each other by linear relationship and we build the model used for parameters' estimation. To verify the model, we performed an analysis based on archival data from Warsaw Stock Exchange. The results are also included.
Access status: Open Access ,
Optimizing modular machining line design problem with mixed activation mode of machining units
(2007) Belmokhtar, Sana; Dolgui, Alexandre; Delorme, Xavier; Ignatenko, Ivan
A modular transfer line designing problem is investigated. The problem is to find the best subset of modules (machining units) from a given set and to assign them to different stations so that technological constraints and cycle upper limit are respected and the line cost is minimal. The investigated lines have a mixed activation mode for the machining units of each station, i. e. the units of each station are arranged into a series of stages such that each stage is composed of several units activated in parallel. A mixed integer program approach is proposed to model and solve the corresponding design problem. Improvements are suggested in order to reduce the model size and speed up the computations.
Access status: Open Access ,
Batch scheduling of deteriorating products
(2007) Barketau, Maksim S.; Cheng, T. C. Edwin; Kovalëv, Mihail Y.; Ng, C. T. Daniel
In this paper we consider the problem of scheduling $N$ jobs on a single machine, where the jobs are processed in batches and the processing time of each job is a simple linear increasing function depending on job's waiting time, which is the time between the start of the processing of the batch to which the job belongs and the start of the processing of the job. Each batch starts from the setup time $S$. Jobs which are assigned to the batch are being prepared for the processing during time $S_{0} < S$. After this preparation they are ready to be processed one by one. The non-negative number $b_i$ is associated with job $i$. The processing time of the $i$-th job is equal to $b_{i}(s_{i} - (s_{i}^{b} + S0))$, where $s_{i}^{b}$ and $s_i$ are the starting time of the $b$-th batch to which the $i$-th job belongs and the starting time of this job, respectively. The objective is to minimize the completion time of the last job. We show that the problem is NP-hard. After that we present an $O(N)$ time algorithm solving the problem optimally for the case $b_{i} = b$. We further present an $O(N^{2})$ time approximation algorithm with a performance guarantee 2.
Access status: Open Access ,
Elevator trip distribution for inconsistent passenger input-output data
(2007) Yoneda, Kiyoshi
Accurate traffic data are the basis for group control of elevators and its performance evaluation by trace driven simulation. The present practice estimates a time series of inter-floor passenger traffic based on commonly available elevator sensor data. The method demands that the sensor data be transformed into sets of passenger input-output data which are consistent in the sense that the transportation preserves the number of passengers. Since observation involves various behavioral assumptions, which may actually be violated, as well as measurement errors, it has been necessary to apply data adjustment procedures to secure the consistency. This paper proposes an alternative algorithm which reconstructs elevator passenger origin-destination tables from inconsistent passenger input-output data sets, thus eliminating the ad hoc data adjustment.
Access status: Open Access ,
Three-machine flowshop scheduling problem to minimize total completion time with bounded setup and processing times
(2007) Allahverdi, Ali
The three-machine flowshop scheduling problem to minimize total completion time is studied where setup times are treated as separate from processing times. Setup and processing times of all jobs on all machines are unknown variables before the actual occurrence of these times. The lower and upper bounds for setup and processing times of each job on each machine is the only information that is available. In such a scheduling environment, there may not exist a unique schedule that remains optimal for all possible realizations of setup and processing times. Therefore, it is desired to obtain a set of dominating schedules (which dominate all other schedules) if possible. The objective for such a scheduling environment is to reduce the size of dominating schedule set. We obtain global and local dominance relations for a three-machine flowshop scheduling problem. Furthermore, we illustrate the use of dominance relations by numerical examples and conduct computational experiments on randomly generated problems to measure the effectiveness of the developed dominance relations. The computational experiments show that the developed dominance relations are quite helpful in reducing the size of dominating schedules.
Access status: Open Access ,
Advances in cone-based preference modeling for decision making with multiple criteria
(2007) Wiecek, Margaret M.
Decision making with multiple criteria requires preferences elicited from the decision maker to determine a solution set. Models of preferences, that follow upon the concept of nondominated solutions introduced by Yu (1974), are presented and compared within a unified framework of cones. Polyhedral and nonpolyhedral, convex and nonconvex, translated, and variable cones are used to model different types of preferences. Common mathematical properties of the preferences are discussed. The impact of using these preferences in decision making is emphasized.
Access status: Open Access ,
A transfer line balancing problem by heuristic methods: industrial case studies
(2008) Guschinskaya, Olga; Dolgui, Alexandre
The paper deals with the problem of optimal configuration of a type of transfer lines which are equipped with transfer machines. Such machines perform operations with standard modular spindle heads which are activated sequentially. All operations assigned to the same spindle head (block of operations) are executed simultaneously by a set of tools fixed at the spindle head. The quantity of machines and spindle heads used to produce a part with the given productivity rate defines the final cost of the transfer line which must be minimized. To minimize this cost, a combinatorial problem of operations assignment to blocks and machines must be solved. The solution must provide a desired productivity (cycle time), it must also satisfy precedence and compatibility constraints. In this paper, we suggest improved versions of FSIC heuristic algorithm in order to help line designers to solve real-scale industrial problems. Results of computational experiments obtained for industrial cases are presented.
Access status: Open Access ,
Partial coordination may increase overall costs in supply chains
(2008) Kaczmarczyk, Waldemar
This paper presents a computational study to evaluate the impact of coordinating production and distribution planning in a two-level industrial supply chain. Three planning methods are compared. The first emulates the traditional way of planning. The two other coordinate plans of the supplier and of all the buyers according to the Vendor Managed Inventory (VMI) approach. The monolithic method solves a single model describing the entire optimization problem. The sequential method copies the imperfect VMI practice. All three methods are implemented by means of Mixed Integer Programming models. The results presented prove that the right choice of planning method is very important for overall cost of the supply chain. In contrast to the previous research, it turned out that information sharing without full coordination may even lead to increase in the overall cost. For some companies applying the VMI approach, developing exact models and solving them almost optimally may therefore be very important.
Access status: Open Access ,
A loss function for box-constrained inverses problems
(2008) Yoneda, Kiyoshi
A loss function is proposed for solving box-constrained inverse problems. Given causality mechanisms between inputs and outputs as smooth functions, an inverse problem demands to adjust the input levels to make the output levels as close as possible to the target values; box-constrained refers to the requirement that all outcome levels remain within their respective permissible intervals. A feasible solution is assumed known, which is often the status quo. We propose a loss function which avoids activation of the constraints. A practical advantage of this approach over the usual weighted least squares is that permissible outcome intervals are required in place of target importance weights, facilitating data acquisition. The proposed loss function is smooth and strictly convex with closed-form gradient and Hessian, permitting Newton family algorithms. The author has not been able to locate in the literature the Gibbs distribution corresponding to the loss function. The loss function is closely related to the generalized matching law in psychology.
Access status: Open Access ,
Developing and deploying electronics assembly line optimization tools: a Motorola case study
(2008) Tirpak, Thomas M.
The assignment of workloads to production equipment is one category of planning decision for an electronics assembly factory. In practice, line balancing requires not only selecting machines with sufficient placement accuracy and feeder capacity, but also addressing a host of other operational objectives and constraints. Motorola Labs led a multi-year effort to apply mathematical programming to balance a variety of production mix and volume scenarios. By representing the optimization problem as a specially structured, mixed linear-integer program, we were able to incorporate a high degree of reality in the model, simultaneously optimizing fixed setups, handling custom parts, maximizing machine uptime, and mitigating secondary bottlenecks. This paper presents the story of how we developed and deployed a software solution that significantly improved assembly cycle times, setup changeovers, and overall factory productivity, saving the company tens of millions of dollars.
Access status: Open Access ,
CP-driven production process planning in multiproject environment
(2008) Banaszak, Zbigniew; Bocewicz, Grzegorz; Bach, Irena
The way enterprise capabilities are used decides about its competitiveness among other ones. In that context modeling aimed at production tasks allocation planning plays a crucial role especially at concurrently executed production orders. The introduced reference model employing constraint programming (CP) paradigm describes both an enterprise and a set of project-like production orders. Moreover, encompassing consumer orders requirements and available production capabilities, the model provides the formal framework allowing one to develop a class of decision support systems aimed at interactive production process planning subject to multiproject environment constraints. In that context our contribution is a knowledge-based and CP-driven approach to resource allocation assuming precise character of decision variables. The conditions sufficient for deadlock avoidance are the main goal. The conditions delivered provide formal framework for developing a task oriented Decision Support Tool for Project Portfolio Prototyping (DST4P, Banaszak 2006). The tool provides a prompt and interactive service to a set of routine queries formulated either in straight or reverse way.
Access status: Open Access ,
A reference point approach to bi-objective dynamic portfolio optimization
(Wydawnictwa AGH, 2009) Sawik, Bartosz
The portfolio selection problem presented in this paper is formulated as a bi-objective mixed integer program. The portfolio selection problem considered is based on a dynamic model of investment, in which the investor buys and sells securities in successive investment periods. The problem objective is to dynamically allocate the wealth on different securities to optimize by reference point method the portfolio expected return and the probability that the return is not less than a required level. In computational experiments the dataset of daily quotations from the Warsaw Stock Exchange were used.
Access status: Open Access ,
Modelling multi-period set-up times in the proportional lot-sizing problem
(Wydawnictwa AGH, 2009) Kaczmarczyk, Waldemar
This paper presents new mixed integer programming models for the Proportional Lot-Sizing Problem (PLSP) with set-up times longer than a period. Proposed models explicitly calculate the distribution of times amongst products in periods with a changeover and determine a final period for every set-up operation. Presented results prove that the proposed models are easier to solve using standard MIP methods than already known models.
Access status: Open Access ,
Practical tips for modelling lot-sizing and scheduling problems
(Wydawnictwa AGH, 2009) Kaczmarczyk, Waldemar
This paper presents some important alternatives for modelling Lot-Sizing and Scheduling Problems. First, the accuracy of models can improved by using short time buckets, which allow more detailed planning but lead to higher computational effort. Next, valid inequalities make the models tighter but increase their size. Sometimes it is possible to find a good balance between the size and tightness of a model by limiting a priori the number of valid inequalities. Finally, a special normalization of the variables simplifies the presentation of results and validation of models.
Access status: Open Access ,
Sequential simulated annealing for the vehicle routing problem with time windows
(Wydawnictwa AGH, 2009) Woch, Marcin; Łebkowski, Piotr
This article presents a new simulated annealing algorithm that provides very high quality solutions to the vehicle routing problem. The aim of described algorithm is to solve the vehicle routing problem with time windows. The tests were carried out with use of some well known instances of the problem defined by M. Solomon. The empirical evidence indicates that simulated annealing can be successfully applied to bi-criterion optimization problems.
Access status: Open Access ,
On efficient coloring of chordless graphs
(Wydawnictwa AGH, 2009) Janczewski, Robert; Małafiejski, Michał
We are given a simple graph $G=(V,E)$. Any edge $e \in E$ is a chord in a path $P \subseteq G$ (cycle $C \subseteq G$) iff a graph obtained by joining $e$ to path $P$ (cycle $C$) has exactly two vertices of degree 3. A class of graphs without any chord in paths (cycles) we call pathchordless (cycle-chordless). We will prove that recognizing and coloring of these graphs can be done in $O(n^{2})$ and $O(n)$ time, respectively. Our study was motivated by a wide range of applications of the graph coloring problem in coding theory, time tabling and scheduling, frequency assignment, register allocation and many other areas.