The demand for wireless networks continues to grow as the need for portable, low-cost telecommunications systems increases around the world. Wireless networks are particularly complex because their topologies can chan...
详细信息
The demand for wireless networks continues to grow as the need for portable, low-cost telecommunications systems increases around the world. Wireless networks are particularly complex because their topologies can change in response to operational requirements or environmental conditions and also because wireless networks are susceptible to electromagnetic interference. In this thesis, we consider the challenges associated with the operation and jamming of so-called "wireless mesh networks." In a wireless mesh network, the communication devices (denoted here as a nodes) are uniform in their ability to send and receive transmissions. We formulate and solve two related optimization problems for wireless mesh networks. First, we solve the problem of the network operator, namely: In order to maximize the utility of delivered network traffic, how should one set the power transmission levels for each node, and along what sequence of transmission links should the traffic flow? The second problem we consider involves an intelligent adversary, the attacker, who wants to place jamming devices among a finite number of locations to disrupt the operator's traffic in the worst possible way. We formulate and solve mathematical programs to obtain the optimal operation and jamming of these networks. We develop a computational decision-support tool that affords the rapid reconfiguration and analysis of various deployment scenarios.
Technology scaling has not only magnified the effects of device process variations, but it has also precipitated the need for simultaneous optimization of several performance metrics. In this paper, we propose a novel...
详细信息
ISBN:
(纸本)9781595939999
Technology scaling has not only magnified the effects of device process variations, but it has also precipitated the need for simultaneous optimization of several performance metrics. In this paper, we propose a novel gate sizing approach for multi-metric optimization of delay, power, and crosstalk noise. The algorithm is based on the concepts of mathematical programming, and models the process variation uncertainty considering spatial correlations. The approach identifies leakage power, dynamic power, and crosstalk noise as the objectives, and the optimized gate delays are kept as constraints. Initially, the deterministic upper and lower bounds of the objectives are identified, and during the final step, a crisp non-linear programming problem is formulated using these boundary values. The problem is solved using KNITRO, an interior-point based optimization solver. The proposed model maximizes the variation resistance, thus providing higher yield. ITC'99 benchmarks were used to test the proposed approach, and the results indicate that our algorithm identifies the solution points that are closest to the nominal bounds, while maintaining high timing yield. Copyright 2008 ACM.
In this paper we describe a trajectory optimization algorithm that generates a second order control update. This algorithm differs from previous trajectory optimization al-gorithms in that the control update is nonlin...
详细信息
ISBN:
(纸本)9780877035442
In this paper we describe a trajectory optimization algorithm that generates a second order control update. This algorithm differs from previous trajectory optimization al-gorithms in that the control update is nonlinear and that each constraint is modeled and met to the second order. The algorithm was designed around the idea of main-taining candidate solutions within the feasible defined problem set. We describe and test various implementations and also describe the limitations of the algorithm.
In this paper we present a strategy for tuning the crystal morphology of pharmaceutical compounds by the appropriate choice of solvent via an optimization model. A three-stage approach involving a pre-design stage, a ...
详细信息
In this paper we present a strategy for tuning the crystal morphology of pharmaceutical compounds by the appropriate choice of solvent via an optimization model. A three-stage approach involving a pre-design stage, a product design stage and a post-design experimental verification stage is presented. The pre-design stage addresses the tormulation of the property constraint tor crystal morphology. This involves crystallization experiments aria development of property models and constraints for morphology. In the design stage various property requirements for the solvent along with crystal morphology are considered and the product design problem is formulated as a mixed integer nonlinear programming *** design stage provides an optimal solvent/list of candidate solvents. Similar to the pre-design stage, in the post design experimental verification stage, the morphology of the crystals （precipitated from the designed solvent） is verified through crystallization experiments followed by product characterization via scanni＇ng electron microscopy, powder X-ray diffraction imaging and Fourier transform spectra analysis.
A one-dimensional pseudo-homogeneous model is used for simulation and subsequent optimization of a MPBR. The reactive system chosen for the present study is Finlayson extended o-xylene oxidation to phthalic anhydride ...
详细信息
ISBN:
(纸本)9780816910502
A one-dimensional pseudo-homogeneous model is used for simulation and subsequent optimization of a MPBR. The reactive system chosen for the present study is Finlayson extended o-xylene oxidation to phthalic anhydride production in the presence of undesired side reactions. The case study is actually taken from Froment and Bischoff and in the present article the optimal design and operation of the reactor is searched upon. All programmed simulations and optimizations were achieved by means of Wolfram Mathematica 6.0®. As is usual for the present case, sensitivity analyses are done for o-xylene inlet concentration (molar fraction) and reactor inlet temperature. The problem for optimization with differential equation constraints is also discussed and several objective functions, technical and economical ones, are maximized.
This paper presents the cost optimization of an urban drainage and wastewater treatment system. The mixed sewer urban drainage (including combined sewer overflows and retention basins), the activated sludge wastewater...
详细信息
This paper presents the cost optimization of an urban drainage and wastewater treatment system. The mixed sewer urban drainage (including combined sewer overflows and retention basins), the activated sludge wastewater treatment plant (WWTP), and the permissible loading of the receiving water were optimized simultaneously by the nonlinear programming approach. For this purpose, the integrated optimization model OPTIMALWWT was developed. The economic objective function of the defined investment and operational costs is subjected to rigorous design and ecological constraints. A practical example of the cost optimization of an existing urban drainage and WWTP, located in Slovenia, is presented to demonstrate the efficiency of the proposed method. For each of the two different design approaches, three different optimization cases were carried out for three different technological alternatives. As a result, the optimal technological process was finally selected for the reconstruction of the system, as a result of its suitable costs and operational safety. Water Environ. Res., 80, 581 (2008).
In our previous works, deterministic release policies were considered for the development of approximations of the two lower moments of the storage volume defined by the dynamic equation of the reservoir in discrete t...
详细信息
In our previous works, deterministic release policies were considered for the development of approximations of the two lower moments of the storage volume defined by the dynamic equation of the reservoir in discrete time but in continuous state space. Important innovation in that work was the incorporation of the lower and upper bounds of reservoir systems into the dynamic equation for the storage volume using indicator functions. The current work, which also does not use discretization, looks at an extension of previous developments that incorporates standard operating policies, and also a new randomized release policy, both of which make the moments calculations exact under the assumptions that (1) the sum of current random inflow and the previous storage volume can be described by just the two lower moments and (2) only the means and variances of the inflows are known. First- and second-moment expressions are derived for the stochastic storage state variable and include terms for the failure probabilities (probabilities of spills or deficits). Expected values of the storage state, variances of storage, release policies, and failure probabilities are obtained by solving the optimal reservoir operations problem using nonlinear programming. The various statistics thus obtained from this optimization compare extremely well with those obtained from simulation for the single-reservoir monthly operations problem studied. The exact characterization of the mean and variance of the storage state variable is derived, which is a difficulty in existing formulations based on linear quadratic Gaussian methods. For example, the latter methods have been unable to estimate these moments reasonably accurately, especially for long-term operations, whereas the traditional storage theory based on discretization brings on the "curse of dimensionality.'' The presentation herein is directed to both traditional reservoir storage theorists who are interested in the design of a reservoir wh
We present an accelerator scheme for use with existing packages that solve nonlinear programming problems with a large number of inequality constraints that arise in the process of discretizing continuous-time optimal...
详细信息
We present an accelerator scheme for use with existing packages that solve nonlinear programming problems with a large number of inequality constraints that arise in the process of discretizing continuous-time optimal control problems with state-space constraints. This scheme is based on the concept of outer approximations used in semi-infinite programming and acts as an external , active constraints set strategy. Our scheme constructs a finite sequence of inequality constrained nonlinear programming problems, containing a progressively larger subset of the constraints in the original problem, and submits these problems to a nonlinear programming solver for a fixed number of iterations. We prove that this scheme computes a solution of the original problem and show, by means of numerical experiments, that it results in reductions in computing time ranging from a factor of 6 to a factor of over 400.
The capacity and value-based pricing (CVBP) model for professional services was derived out of a need for a new way to think about how professional service 'products' should be priced in a competitive market-p...
详细信息
The capacity and value-based pricing (CVBP) model for professional services was derived out of a need for a new way to think about how professional service 'products' should be priced in a competitive market-place. Moving away from 'cost-plus' pricing, the CVBP model attempts to incorporate the 'stand-alone' value of a service, along with other variables, to arrive, systematically, at a set of improving prices. A multinomial logit model is used to model the discrete choice decision making. The model and its output can be used in negotiating services contracts, increasing profits, and smoothing demand.
This work constructs the membership functions of the system characteristics of a batch queuing system with server setup, in which the batch arrival rate, customer service rate, and server setup rate are all fuzzy numb...
详细信息
This work constructs the membership functions of the system characteristics of a batch queuing system with server setup, in which the batch arrival rate, customer service rate, and server setup rate are all fuzzy numbers. The -cut approach is used to transform a fuzzy queue into a family of conventional crisp queues in this context. By means of the membership functions of the system characteristics, a set of parametric nonlinear programs is developed to describe the family of crisp queues with server setup. Two numerical examples are solved suc- cessfully to illustrate the validity of the proposed approach. Because the system characteristics are expressed and governed by the membership functions, the fuzzy queues with server setup are represented more accurately and the analytic results are more useful for system designers and practitioners.
暂无评论