High-speed InGaP/GaAs HBTs with a strained InxGa1-xAs base

A self-aligned InGaP/GaAs heterojunction bipolar transistor with a compositionally graded In_xGa_1-xAs base has been demonstrated with f_T=83 GHz and f_max=197 GHz. To our knowledge, these results are the highest reported for both parameters in InGaP/GaAs HBT's. The graded base, which improves electron transport through the base, results in a DC current gain and a cutoff frequency which are 100% and 20% higher, respectively, than that achieved by an identical device with a nongraded base. The high f_max results from a heavily doped base, self-aligned base contacts, and a self-aligned collector etch. These results demonstrate the applicability of InGaP/GaAs HBT's in high-speed microwave applications     

Performance analysis of concurrency control using locking withdeferred blocking

The concurrency control (CC) method employed can be critical to the performance of transaction processing systems. Conventional locking suffers from the blocking phenomenon, where waiting transactions continue to hold locks and block other transactions from progressing. In a high data contention environment, as an increasing number of transactions wait, a larger number of lock requests get blocked and fewer lock requests can get through. The proposed scheme reduces the blocking probability by deferring the blocking behavior of transactions to the later stages of their execution. By properly balancing the blocking and abort effects, the proposed scheme can lead to better performance than either the conventional locking or the optimistic concurrency control (OCC) schemes at all data and resource contention levels. We consider both static and dynamic approaches to determine when to switch from the nonblocking phase to the blocking phase. An analytical model is developed to estimate the performance of this scheme and determine the optimal operating or switching point. The accuracy of the analytic model is validated through a detailed simulation     

Dynamic thermal methods and microprocessing units for measuring the rates and properties of material flows

A multifunctional measurement system utilizing a noncontacting, thermal-tracer primary detector is described. It provides for the automatic acquisition of information on volumetric and mass flow rates and the properties of fluid flows.Translated from Izmeritel'naya Tekhnika, No. 8, pp. 10–11, August, 1994.     

Calculation method for percolation thresholds in modeling porous and composite materials

A method is suggested for calculating percolation thresholds in two- and three-dimensional materials allowing for remote interaction and elongation of particles forming these materials. Calculated results are compared with known data. It is shown that it is possible to use the method when simulating elastic and plastic properties of porous materials.     

Nanoparticles and Their Effective Use in the Technology of Highly Concentrated Binding Suspensions (HCBS) and Refractory Castables. Part 1

General aspects (including terminology) related to the use of ultradisperse particulates (nanosystems) are discussed. The important role of nanoparticles in the technology of highly concentrated binding suspensions (HCBS) and refractory castables is emphasized. Using nanoparticles provides a route toward improving the rheotechnologic properties of HCBS and HCBS-based molding mixtures as well as the structure and service properties of the end product.     

On studying methods for cleaning dielectric oil for impregnation of high-voltage pulse capacitors with film dielectric

Methods for cleaning commercial T-1500 dielectric oil with different adsorbents are studied. The oil is intended for impregnation of high-voltage pulse capacitors with film dielectric.