Parallel simulated annealing for power system decomposition

This paper proposes a parallel optimization approach to power system decomposition for voltage control. In this paper, a parallel simulated annealing (PSA) technique is developed to decompose power systems so that subsystems are equally separated in terms of the number of nodes and control variables. System decomposition is one of difficult discrete number combinatorial problems. The PSA technique provides better solutions than the conventional SA because of searching a solution near a global minimum over a wide range. The proposed method is tested in IEEE 30, 57, and 118 node systems     

Air vent in water chamber and surface coating on liner slides concerning auxiliary cooling system for the high temperature engineering test reactor

Experimental study was made to confirm the validity of new designs of the auxiliary cooling system for the high temperature engineering test reactor (HTTR). First, it is necessary to vent residence air in outlet side of water chamber of the auxiliary heat exchanger for the HTTR. Accordingly, we have proposed to mount a proper bend duct in the outlet side of the water chamber. Air vent is done by difference between pressures at both ends of the bend duct caused by the forced water circulation using the water pumps. From flow tests, it was confirmed that it is capable of venting the air through the bend duct by circulating the water in maximum capacity of the water pumps. Second, it is essential to prevent seizure and excessive wear of the liner slides of the auxiliary concentric hot gas duct for the HTTR at a service temperature of 950°C. Therefore, we have put forward to coat titanium nitride (TiN) on the surface of the liner slides made of nickel-based superalloy Hastelloy XR using the thermochemical vapor deposition method. As a result of seizure and wear tests, it was confirmed that the TiN coating film of 3 μm on the surface of Hastelloy XR is sufficient.     

Effects of crystallographic misorientation on power loss in

The effects of the inclination angle β of the [001] axis out of the sheet plane on the thickness dependence of the power losses in     

Three-dimensional pin power reconstruction for the axially heterogeneous region in BWR

A three-dimensional pin power reconstruction method was proposed and verified by applying to the axially heterogeneous region problem of the BWR core calculation. Because the production assembly calculation has been carried out by two-dimensional deterministic calculation methods like current coupling collision probability or the method of characteristics, it has been difficult to predict the detailed three-dimensional heterogeneous pin power distribution of the axially heterogeneous region. Consequently, only radial intranodal homogeneous power distributions have been considered, and axial intranodal homogeneous power distributions have not been considered in the estimation of linear-heat-generation-ratio at common BWR core calculations.     

A combination of differential equations and convolution in understanding the spread of an epidemic

Nonlinear dynamical method of projecting the transmission of an epidemic is accurate if the input parameters and initial value variables are reliable. Here, such a model is proposed for predicting an epidemic. A method to supplement two variables and two parameters for this proposed model is demonstrated through a robust statistical approach. The method described here worked well in case of three continuous distributions. Model predictions could be lower estimates due to under-reporting of disease cases. Anad hoc procedure with a technical note is provided in the appendix An earlier version of this paper was presented at the annual conference of the Indian Society for Mathematical Modelling & Computer Simulation, Bangalore, November 14–15, 2002     

Survey of switching techniques in high-speed networks and their performance

One of the most promising approaches for high speed networks for integrated service applications is fast packet switching, or ATM (asynchronous transfer mode). ATM can be characterized by very high speed transmission links and simple, hard-wired protocols within a network. To match the transmission speed of the network links, and to minimize the overhead due to the processing of network protocols, the switching of cells is done in hardware switching fabrics in ATM networks. A number of designs have been proposed for implementing ATM switches. Although many differences exist among the proposals, the vast majority of them are based on self-routeing multistage interconnection networks. This is because of the desirable features of multi-stage interconnection networks such as self-routeing capability and suitability for VLSI implementation. Existing ATM switch architectures can be classified into two major classes: blocking switches, where blockings of cells may occur within a switch when more than one cell contends for the same internal link, and non-blocking switches, where no internal blocking occurs. A large number of techniques have also been proposed to improve the performance of blocking and non-blocking switches. In this paper, we present an extensive survey of the existing proposals for ATM switch architectures, focusing on their performance issues.     

New protection method for HVDC lines including cables

For the third project of the Hokkaido-Honshu HVDC Link in Japan, called the HVDC Link III project (rated at 250 kVDC-1200 A-300 MW), we developed an HVDC transmission line protection method based on a new working principle that allows high-speed and highly sensitive detection of faults, enhancing reliability in the supply of electric power. In general, increasing the sensitivity of relays will lead to an increased likelihood of undesired operation whereas lowering the sensitivity will impair the responsiveness of the relays. Our proposed method meets these apparently incompatible requirements very well. Basically classified as a differential scheme, the HVDC transmission line protection method compensates for a charging and discharging current that flows through the line-to-ground capacitance at times of voltage variations caused by a line fault or by the operation of DC power systems. The developed protection method is also characterized in that it uses current changes induced by voltage variations to restrain the operation of a relay. This configuration has made the proposed method far superior in responsiveness and sensitivity to the conventional protection method. A simulation using an EMTP (Electro-Magnetic Transients Program) was conducted on this method. Developed relay equipment embodying the new protection method was subjected to various verification tests, where this equipment was connected to a power system simulator, before being delivered to the HVDC Link III facility