The authors propose a new model for dynamic traffic assignment, modeling the traffic system by a mixedintegerlinear program solvable in finite time. The model represents link travel times, which must be the same for...
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The authors propose a new model for dynamic traffic assignment, modeling the traffic system by a mixedintegerlinear program solvable in finite time. The model represents link travel times, which must be the same for all vehicles which enter a link together during a single time period by means of 0-1 integer variables. Given the values of these variables, the problem is to assign traffic, modeled as multiperiod multicommodity flow, subject to constraints on capacity implied by the link travel times. An optimal solution to the model gives the vehicle routings corresponding to minimum total travel time, achieving the most efficient use of road capacity. The solution gives unambiguous link travel times as a function of time of entry to the link, suitable for individual route optimization if all but a small priority class of traffic accepts the system-optimal routing.< >
This paper describes a two-step algorithm for solving the layout problem while assuming the departments can have varying areas. The first step solves a quadratic assignment problem formulation of the problem using a h...
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This paper describes a two-step algorithm for solving the layout problem while assuming the departments can have varying areas. The first step solves a quadratic assignment problem formulation of the problem using a heuristic cutting plane routine. The second step solves a mixed-integerlinearprogramming problem to find the desired block diagram layout. The algorithm incorporates two concepts to make the solutions more practical. First, rearrangement costs are simultaneously considered along with flow costs in solving a dynamic layout problem involving multiple time periods. It is the only algorithm to solve a general dynamic layout problem with varying department areas. Second, regular department shapes are maintained by requiring all departments to be rectangular. Its formulation for doing this is more efficient than previous algorithms.
With the goal of fiscal self-sufficiency, the United States Postal Service (USPS) has embarked upon a 10-year program to modernize, and in some cases radically alter, the way it manages and processes the mail. At the ...
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With the goal of fiscal self-sufficiency, the United States Postal Service (USPS) has embarked upon a 10-year program to modernize, and in some cases radically alter, the way it manages and processes the mail. At the heart of this effort is the goal of automating virtually all of the letter mail by 1995. This means reading, sorting, and then sequencing each mail piece to the order in which it will be delivered by the carrier with only a minimum of manual labor. In support of this goal, a series of long-term planning models has been developed to help select equipment and plan for its use at the more than 250 general mail facilities (GMF) throughout the nation. This paper reports on one of the central studies underlying this effort. Because of the size and complexity of the facility design problem, a hierarchical approach was followed. Three interrelated models were developed starting with a mixedintegerlinear program to derive equipment needs and initial machine schedules. The latter are post-processed in two stages to produce implementable schedules that reflect current practice. An auxiliary linear program and a heuristic were constructed for this purpose. The models and analysis conducted are demonstrated with data obtained from the Providence GMF. The results indicate that near optimal solutions can be found quite efficiently and are expected to lead to substantial savings over the 10-year planning horizon.
The background of this study is a rather classical but complex inventory control/production planning/line scheduling problem of a major soft-drink company in Hong Kong. The issue that stands out for this many-product ...
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Presents a mathematical programming model for finding the sub-optimal assignment of a given application task onto a heterogeneous suite of computers. The proposed model is based on the Cluster-M heterogeneous programm...
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Presents a mathematical programming model for finding the sub-optimal assignment of a given application task onto a heterogeneous suite of computers. The proposed model is based on the Cluster-M heterogeneous programming paradigm. Using Cluster-M, an application task is represented in form of a Cluster-M specification which indicates all the concurrent and communicating subtasks at every step of computation. These specifications are then to be mapped onto the underlying heterogeneous suite of computers represented in a Cluster-M representation format. To map every step of Cluster-M specification onto the Cluster-M representation of the heterogeneous suite, we propose to use an optimal synthesis technique called SOS (synthesis of systems). We formulate and solve each of the mapping steps in the form of a mixed integer linear programming model. This leads to a very fast sub-optimal selection and mapping solution.< >
Develops a mixed integer linear programming (MIP) model for determining the connectivities of a multi-beam satellite and for distributing the traffic among transponders. The optimization objectives include evenly dist...
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Develops a mixed integer linear programming (MIP) model for determining the connectivities of a multi-beam satellite and for distributing the traffic among transponders. The optimization objectives include evenly distributing traffic among transponders (satellite beams) and minimizing the number of active transponders. The model handles a variety of service classes each with different requirements simultaneously. The major inputs to the model are the heterogeneous traffic matrix, beam inter-connection capabilities of transponders and their capacities, and beam coverages. The outputs are the transponder switch settings and a traffic assignment plan. The traffic assignment plan indicates what portion of the traffic originating from one region and destined to another should be assigned to each transponder.< >
This paper discusses a mathematical optimization problem with a number of applications in the timing analysis of synchronous and asynchronous circuits. This problem, which we call min-max linearprogramming (mmLP), in...
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This paper discusses a mathematical optimization problem with a number of applications in the timing analysis of synchronous and asynchronous circuits. This problem, which we call min-max linearprogramming (mmLP), involves the solution of linear programs that have min and max functions added to their constraints. Instances of problem mmLP are described, and a simple proof of NP-completeness is given. Two alternate methods are presented for mmLP solution. The first uses a branch-and-bound algorithm which is optimized to specifically reduce the number of operations required by the simplex linearprogramming algorithm. The second uses a transformation to a standard mixed integer linear programming (MILP) formulation. We evaluate both approaches on a variety of problems, including several large previously unsolved optimal clocking problems.
An algorithm is presented for designing digital filters with coefficients expressible as sums of signed power-of-two (SPT) terms. For each filter gain, the time complexity of the algorithm is a second-order polynomial...
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ISBN:
(纸本)0780312813
An algorithm is presented for designing digital filters with coefficients expressible as sums of signed power-of-two (SPT) terms. For each filter gain, the time complexity of the algorithm is a second-order polynomial in the filter order and is a first-order polynomial in the filter wordlength. Unlike conventional methods where each coefficient is allocated a fixed number of SPT terms, the author's method allows the number of SPT terms for each coefficient to vary subject to the number of SPT terms for the entire filter. This provides the possibility of finding a better filter without increasing the number of adders, which determines the realization cost for a given filter length. Application of the algorithm to finite impulse response (FIR) filter designs shows that it achieves up to 8.9 dB improvement over simulated annealing and mixedintegerlinear programing on the normalized peak ripples of example filters.< >
Most high-level synthesis schedulers are capable only of mapping an operation to one specific module type. To ensure a full design space exploration, a synthesis system should however select freely from a library cont...
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Most high-level synthesis schedulers are capable only of mapping an operation to one specific module type. To ensure a full design space exploration, a synthesis system should however select freely from a library containing modules with a large variety in delay, area and so on. A module selection and scheduling approach which allows the full use of such unrestricted libraries is presented. Extensive benchmark results show very fast running times and optimal solutions. This approach clearly illustrates the advantages of synthesis tools which can fully cope with unrestricted libraries, as they lead to designs with less module area.< >
The United States Coast Guard is organized by Atlantic and Pacific areas, which are further subdivided into districts. Each district assigns cutters (ships) of length 180 feet or less into weekly statuses. The resulti...
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The United States Coast Guard is organized by Atlantic and Pacific areas, which are further subdivided into districts. Each district assigns cutters (ships) of length 180 feet or less into weekly statuses. The resulting cutter schedules reflect the district's level of readiness to respond to such emergencies as search and rescue, law enforcement, and pollution response. The First Coast Guard District has one of the largest scheduling problems, assigning each of 16 cutters to one of six weekly statuses. The First District's quarterly schedules must adhere to a number of guidelines which ensure patrol coverage, enforce equitable distribution of patrols, and restrict consecutive cutter statuses. This thesis formulates and solves the quarterly scheduling problem as an elastic mixedintegerlinear program. Face valid schedules, which are superior to actual schedules for all measures of effectiveness considered, are obtained within 15 minutes on a 486/33 Mhz personal computer using a commercially available integerprogramming solver.
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