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The steady behavior of a rarefied gas in a circular pipe with a saw-like temperature distribution increasing and decreasing periodically in the direction of the pipe axis is investigated numerically by means of the direct simulation Monte Carlo method. It is shown that a steady one-way flow is induced in the pipe without the help of a pressure gradient for a wide range of the Knudsen number when a series of ditches is dug periodically in the part of the pipe wall with decreasing (or increasing) temperature. The features of the flow are clarified in detail. It is also shown that the flow has a pumping effect. In particular, some data that give the estimate of the maximum compression ratio attained by a pipe consisting of a large number of periods are presented. The present study is the continuation of the previous study in the case of a two-dimensional channel [Y. Sone et al., Phys. Fluids 8, 2227 (1996)]. It is found that although the induced one-way flow is stronger for the two-dimensional channel, the pumping effect is stronger for the circular pipe. [ABSTRACT FROM AUTHOR]

It is demonstrated experimentally that a one-way flow of a slightly rarefied gas is induced in a circular straight pipe of a uniform diameter with its two ends being kept at an equal temperature and pressure by heating the middle part along the pipe and by putting up a shelf or shelves inside of a half part of the pipe on one side of the heater. The experiment is done in a small vacuum chamber of a glass bell jar, and the flow is detected by a small windmill. A one-way flow is induced from the part of the pipe with a shelf or shelves to that without it or them. The mechanism of the flow is explained by the difference of dependence on the cross sectional area between the thermal transpiration and Poiseuille flow. [ABSTRACT FROM AUTHOR]

A two-stage method is proposed for generating dense MOS modules. The first stage is generation of dense placements of FETs (field-effect transistors) from the gate-matrix layouts, using a gate matrix deformation method. The deformation of gate-matrix layouts is guided by the design rules, using FETs with meander channel structures if needed. The second stage is routing of metal wires to connect FETs in modules. The authors have developed a three-dimensional maze router by extending the method to cope with arbitrary multilayer connections with user-defined costs for the connections in each layer. The costs can be used to assign desired priorities for each metal layer in the routing. This method results in about 65% reduction in chip area compared with the gate matrix method for typical examples using three- or four-layer connections [ABSTRACT FROM PUBLISHER]