4,425 research outputs found
Remote Sensing Information Sciences Research Group, Santa Barbara Information Sciences Research Group, year 3
Research continues to focus on improving the type, quantity, and quality of information which can be derived from remotely sensed data. The focus is on remote sensing and application for the Earth Observing System (Eos) and Space Station, including associated polar and co-orbiting platforms. The remote sensing research activities are being expanded, integrated, and extended into the areas of global science, georeferenced information systems, machine assissted information extraction from image data, and artificial intelligence. The accomplishments in these areas are examined
Heuristics and Metaheuristics Approaches for Facility Layout Problems: A Survey
Facility Layout Problem (FLP) is a NP-hard problem concerned with the arrangement of facilities as to minimize the distance travelled between all pairs of facilities. Many exact and approximate approaches have been proposed with an extensive applicability to deal with this problem. This paper studies the fundamentals of some well-known heuristics and metaheuristics used in solving the FLPs. It is hoped that this paper will trigger researchers for in-depth studies in FLPs looking into more specific interest such as equal or unequal FLPs
An Integrated Model for Optimization of Production-Distribution inventory Levels and Routing Structure for a Multi-Period, Multi-Product, Bi-Echelon Supply Chain
In many multi-stage manufacturing supply chains, transportation related costs are a significant portion of final product costs. It is often crucial for successful decision making approaches in multi-stage manufacturing supply chains to explicitly account for non-linear transportation costs. In this paper, we have explored this problem by considering a Two-Stage Production-Transportation (TSPT). A two- stage supply chain that faces a deterministic stream of external demands for a single product is considered. A finite supply of raw materials, and finite production at stage one has been assumed. Items are manufactured at stage one and transported to stage two, where the storage capacity of the warehouses is limited. Packaging is completed at stage two (that is, value is added to each item, but no new items are created), and the finished goods inventories are stored which is used to meet the final demand of customers. During each period, the optimized production levels in stage one, as well as transportation levels between stage one and stage two and routing structure from the production plant to warehouses and then to customers, must be determined. We consider “different cost structures,” for both manufacturing and transportation. This TSPT model with capacity constraint at both stages is optimized using Genetic Algorithms (GA) and the results obtained are compared with the results of other optimization techniques of complete enumeration, LINDO, and C-plex
Aspects of computerised timetabling
This research considers the problem of constructing high school timetables using a
computer. In the majority of high schools, termly or yearly timetables are still
being produced manually. Constructing a timetable is a hard and time consuming
task which is carried out repeatedly thus a computer program for assisting with this
problem would be of great value. This study is in three parts. First. an overall
analysis of the problem is undertaken to provide background knowledge and to
identify basic principles in the construction of a school timetable. The
characteristics of timetabling problems are identified and the necessary data for the
construction of a timetable is identified. The first part ends with the production of
a heuristic model for generating an initial solution that satisfies all the hard
constraints embodied in the curriculum requirements.
The second stage of the research is devoted to designing a heuristic model for
solving a timetable problem with hard and medium constraints. These include
constraints like the various numbers of common periods, double periods and
reducing the repeated allocation of a subject within any day. The approaches taken
are based on two recently developed techniques, namely tabu search and simulated
annealing. Both of these are used and comparisons of their efficiency are
provided. The comparison is based on the percentage fulfilment of the hard and
medium requirements.
The third part is devoted to one of the most difficult areas in timetable
construction, that is the softer requirements which are specific to particular schools
and whose satisfaction is not seen as essential. This section describes the
development of an expert system based on heuristic production rules to satisfy a
range of soft requirements. The soft requirements are studied and recorded as
rules and a heuristic solution is produced for each of the general requirements.
Different levels of rule are developed, from which the best possible solution to a
particular timetable problem is expertly produced.
Finally, possible extensions of the proposed method and its application to other
types of the timetabling problem are discussed
Recommended from our members
Tabu search for ship routing and scheduling
This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University, 20/12/2006.This thesis examines exact and heuristic approaches to solve the Ship Routing and Scheduling Problem (SRSP). The method was developed to address the problem of loading cargos for many customers using heterogeneous vessels. Constraints relate to delivery time windows imposed by customers, the time horizon by which all deliveries must be made and vessel capacities. The objective is to minimise the overall operation cost, where all customers are satisfied. Two types of routing and scheduling are considered, one called single-cargo problem, where only one cargo can be loaded into a ship, and the second type called multi-cargo problem, where multiple products can be carried on a ship to be delivered to different customers. The exact approach comprises two stages. In the first stage, a number of candidate feasible schedules is generated for each ship in the fleet. The second stage is to model the problem as a set partitioning problem (SPP) where the columns are the candidate feasible schedules obtained in the first stage. The heuristic approach uses Tabu Search (TS). Most of the TS operations, such as insert and swap moves, tenure, tabu list, intensification, and diversification are used. The results of a computational investigation are presented. Solution quality and execution time are explored with respect to problem size and parameters controlling the tabu search such as tenure and neighbourhood size. The results showed that the average of the solution gap between TS solution and SPP solution is up to 28% (for small problems) and up to 18% for large problems. However, obtaining an optimal solution requires a large amount of computer time to produce the solution compared to obtaining approximate solutions using the TS approach. The use of Tabu Search for SRSP is novel and the results indicate that it is viable approach for large problems
Methodological review of multicriteria optimization techniques: aplications in water resources
Multi-criteria decision analysis (MCDA) is an umbrella approach that has been applied to a wide range of natural resource management situations. This report has two purposes. First, it aims to provide an overview of advancedmulticriteriaapproaches, methods and tools. The review seeks to layout the nature of the models, their inherent strengths and limitations. Analysis of their applicability in supporting real-life decision-making processes is provided with relation to requirements imposed by organizationally decentralized and economically specific spatial and temporal frameworks. Models are categorized based on different classification schemes and are reviewed by describing their general characteristics, approaches, and fundamental properties. A necessity of careful structuring of decision problems is discussed regarding planning, staging and control aspects within broader agricultural context, and in water management in particular. A special emphasis is given to the importance of manipulating decision elements by means ofhierarchingand clustering. The review goes beyond traditionalMCDAtechniques; it describes new modelling approaches. The second purpose is to describe newMCDAparadigms aimed at addressing the inherent complexity of managing water ecosystems, particularly with respect to multiple criteria integrated with biophysical models,multistakeholders, and lack of information. Comments about, and critical analysis of, the limitations of traditional models are made to point out the need for, and propose a call to, a new way of thinking aboutMCDAas they are applied to water and natural resources management planning. These new perspectives do not undermine the value of traditional methods; rather they point to a shift in emphasis from methods for problem solving to methods for problem structuring. Literature review show successfully integrations of watershed management optimization models to efficiently screen a broad range of technical, economic, and policy management options within a watershed system framework and select the optimal combination of management strategies and associated water allocations for designing a sustainable watershed management plan at least cost. Papers show applications in watershed management model that integrates both natural and human elements of a watershed system including the management of ground and surface water sources, water treatment and distribution systems, human demands,wastewatertreatment and collection systems, water reuse facilities,nonpotablewater distribution infrastructure, aquifer storage and recharge facilities, storm water, and land use
An Expert System for Unit Commitment
Methods used to solve the unit commitment problem of power generating systems should give a solution which is both feasible and optimal, and should be flexible enough to be rapidly and easily reimplemented in response to a changing and unpredictable environment. An expert system is proposed which incorporates both heuristic and numerical optimization methods to achieve such a solution. The expert system acts like a preprocessor for data which is to be used by a Dynamic Programming routine to determine the most economical schedule of generating units. After the schedule has been generated, the expert system acts like a postprocessor to check the feasibility of the schedule and make recommendations for changes to achieve a better schedule
Bilinear and parallel prediction methods
To make accurate predictions about a system one must develop a model for that system. Bilinear models are often attractive options because they allow the user to model nonlinear interactions between variables in complicated systems with (potentially) millions of variables. In this work we apply bilinear models to two separate domains and present novel models for improved prediction accuracy and novel heuristics for solving the optimization problems that arise from the use of bilinear models.
In the first system we use a bilinear model to predict the remaining useful life (RUL) of a rechargeable lithium-ion (Li-ion) battery. The approach used to solve the bilinear model leverages bilinear kernel regression to build a nonlinear mapping between the capacity feature space and the RUL state space. Specific innovations of the approach include: a general framework for robust sparse prognostics that effectively incorporates sparsity into kernel regression and implicitly compensates for errors in capacity features; and two numerical procedures for error estimation that efficiently derives optimal values of the regression model parameters.
Second, we apply a bilinear model to the matrix completion problem, where one seeks to recover a data matrix from a small sample of observed entries. We assume the matrix we wish to recover is low-rank (the rank of the matrix is much less than either dimension) and model it as the product of two low-rank matrices. We then adapt existing parallel solutions to this bilinear model for use on a graphics processing unit (GPU). Additionally, we introduce a novel method for inductive matrix completion on a GPU
GAM: a web-service for integrated transcriptional and metabolic network analysis
Novel techniques for high-throughput steady-state metabolomic profiling yield information about changes of nearly thousands of metabolites. Such metabolomic profiles, when analyzed together with transcriptional profiles, can reveal novel insights about underlying biological processes. While a number of conceptual approaches have been developed for data integration, easily accessible tools for integrated analysis of mammalian steady-state metabolomic and transcriptional data are lacking. Here we present GAM (‘genes and metabolites’): a web-service for integrated network analysis of transcriptional and steady-state metabolomic data focused on identification of the most changing metabolic subnetworks between two conditions of interest. In the web-service, we have pre-assembled metabolic networks for humans, mice, Arabidopsis and yeast and adapted exact solvers for an optimal subgraph search to work in the context of these metabolic networks. The output is the most regulated metabolic subnetwork of size controlled by false discovery rate parameters. The subnetworks are then visualized online and also can be downloaded in Cytoscape format for subsequent processing. The web-service is available at: https://artyomovlab.wustl.edu/shiny/gam
Management: A continuing bibliography with indexes
This bibliography lists 344 reports, articles, and other documents introduced into the NASA scientific and technical information system in 1978
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