The extended duration of recent major power system disturbances have indicated the need for development of system restoration plans (SRP), which would minimize the time required for restoration of service. This paper ...
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The extended duration of recent major power system disturbances have indicated the need for development of system restoration plans (SRP), which would minimize the time required for restoration of service. This paper presents an efficient approach to SRP, from a complete collapse under peak-and light-load conditions, developed at Potomac Electric Power Company (PEPCo). The method is based on: (a) the combined effort of operating personnel and system analysts, (b) the access to data available from the on-line computer facilities, and (c) the use of an interactive load flow program. The SRP development procedure and the results described in this paper are of general interest in that they can be adopted and applied to the other electric systems.
The problem of optimum flow control of a class of queueing systems which appears as a model of datagram and virtual circuit computer communication networks is investigated. This class "intuitively" has the p...
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The problem of optimum flow control of a class of queueing systems which appears as a model of datagram and virtual circuit computer communication networks is investigated. This class "intuitively" has the property that by increasing the load on the network, both the average throughput and the average time delay also increase. It is shown that the control that achieves the maximum throughput under a bounded average time delay criterion can be specified by a "window" flow control mechanism (bang-bang control). The window size L , the maximum number of unacknowledged packets in the system, can be easily derived from the preassigned upper bound on the time delay T , the Norton equivalent of the queueing system μ, and the maximum admissible total load on the network c .
This paper studies the security of multi-threaded programs. We combine two methods, i.e., qualitative and quantitative security analysis, to check whether a multi-threaded program is secure or not. In this paper, besi...
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This paper studies the security of multi-threaded programs. We combine two methods, i.e., qualitative and quantitative security analysis, to check whether a multi-threaded program is secure or not. In this paper, besides reviewing classical analysis models, we present a novel model of quantitative analysis where the attacker is able to select the scheduling policy. This model does not follow the traditional information-theoretic channel setting. Our analysis first studies what extra information an attacker can get if he knows the scheduler's choices, and then integrates this information into the transition system modeling the program execution. Via a case study, we compare this approach with the traditional information-theoretic models, and show that this approach gives more intuitive-matching results.
The load flow study has been at the center of studies made for designing and operating power systems for many years. It is well known that forecasted data used in load flow studies contain errors that affect the solut...
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The load flow study has been at the center of studies made for designing and operating power systems for many years. It is well known that forecasted data used in load flow studies contain errors that affect the solution, as can be evidenced by running many cases perturbing the input data. This paper presents a method for calculating the effect of the propagation of data inaccuracies through the load flow calculations, thus obtaining a range of values for each output quantity that, to a high degree of probability, encloses the operating conditions of the system. The method is efficient and can be added to any existing load flow program. Results of cases run on the AEP system are included.
The initial personalization of multilayer ceramic substrates begins with the formation of vias in the individual green ceramic sheets. A fully automatic computer-controlled tool to perform this function has been devel...
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The initial personalization of multilayer ceramic substrates begins with the formation of vias in the individual green ceramic sheets. A fully automatic computer-controlled tool to perform this function has been developed by IBM and is in operation on its manufacturing lines. The auto punch tool creates more than 40 000 vias of two different sizes (0.14 mm and 0.15 mm) in green ceramic sheets of two differenct thicknesses (0.20 mm and 0.28 mm). The positional distribution of the vias is on a 0.3 mm grid. Other than the grid the vias may be randomly distributed. Their positional accuracy is within 0.03 mm at 3 v. The vias are created at a rate of 1440 vias per second. All data needed to operate the tool and to create the vias flow automatically from a factory host computer (IBM System 370/168) through an area controller (IBM Series I) to the tool controller (IBM Series I). Manufacturing data concerning each individual green ceramic sheet are returned to the factory host computer.
A cost-effective coordinate rotation digital computer (CORDIC) architecture is described for the computation of inverse kinematic position solution based on a functional decomposition of the closed-form joint equation...
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A cost-effective coordinate rotation digital computer (CORDIC) architecture is described for the computation of inverse kinematic position solution based on a functional decomposition of the closed-form joint equations. The functional decomposition shows a limited amount of parallelism with a large amount of sequentialism in the flow of computation and data dependencies and reveals the requirement for computing a large set of elementary operations: multiplications, additions, divisions, square roots, trigonometric functions and their inverse. However, these elementary operations, in general, cannot be efficiently computed in general-purpose uniprocessor computers. The CORDIC algorithms are the natural candidates for efficiently computing these elementary operations and the interconnection of these CORDIC processors to exploit the great potential of pipelining provides a better solution for computing the inverse kinematic position solution. The functional decomposition of the inverse kinematic position solution into a set of computational tasks can be represented as a directed task graph. The inclusion of input data modifies the task graph to an acyclic data dependency graph (ADDG). The nodes of the ADDG correspond to the computational modules, each of which can be realized by a CORDIC processor. The operands or data move along the edges, each of which connects a pair of nodes. Due to different paths and computation time for each CORDIC processor, operands may arrive at multi-input modules at different arrival time, causing a longer pipelined time. Delay buffers may be inserted at various paths to achieve a balanced ADDG. The optimal buffer assignment problem is reduced to an integer linear optimization problem which can be solved easily by computers. The realization of the balanced ADDG results in a maximum pipelined CORDIC architecture with a minimum number of delay buffer stages for the computation of inverse kinematic position solution.
Earlier reported tests have demonstrated that sufficient ultrasonic scattering can be obtained from particulate matter in urine during voiding to be of value as a transcutaneous diagnostic technique for the lower urin...
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Earlier reported tests have demonstrated that sufficient ultrasonic scattering can be obtained from particulate matter in urine during voiding to be of value as a transcutaneous diagnostic technique for the lower urinary tract. In this paper, we compare theoretical scattering computations for urethral flow models with data obtained from scattering measurements on the urethra and on physical models. The results indicate that urethral parameters such as the average urine velocity, extent of turbulence, and urethral diameter as a function of position along the tract, including the location of any strictures, can be determined remotely by ultrasonic means.
Techniques and methods are presented for conducting simplified power-flow calculations in power pools by employing the simultaneous computing capability of the computers in the separate areas of the pool.
Techniques and methods are presented for conducting simplified power-flow calculations in power pools by employing the simultaneous computing capability of the computers in the separate areas of the pool.
Spreadsheet programs are deceptively simple tools that are widely used by end-user developers in organizations. However, recent studies have shown that spreadsheets often contain significant, decision-affecting errors...
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Spreadsheet programs are deceptively simple tools that are widely used by end-user developers in organizations. However, recent studies have shown that spreadsheets often contain significant, decision-affecting errors. One study that addressed "linking errors," i.e., incorrect references to spreadsheet cell values on separate work areas, found these errors to be a major error source in complex spreadsheets that use distinct work areas spread across multiple worksheets. This paper describes a code inspection approach that visually represents the structure of a linked spreadsheet and graphically identifies linked cells and their sources. We tested this approach in an experimental study where subjects created a complex spreadsheet. Results indicate that subjects who used the approach made significantly fewer errors and experienced no decrease in speed of spreadsheet production or satisfaction with the production process.
Complex BIFORE transform (CBT) is extended to multiple dimensions. Basic properties of multidimensional CBT are developed and a fast algorithm for its computation is applied.
Complex BIFORE transform (CBT) is extended to multiple dimensions. Basic properties of multidimensional CBT are developed and a fast algorithm for its computation is applied.
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