Effect of tempering under stress on the mechanical properties and relaxation resistance of austempered reinforcing wire

Conclusions To increase the relaxation resistance and retain high values of strength and ductility of austempered reinforcing wire it is necessary to conduct tempering under stress at stresses somewhat lower than _0.01 and temperatures of 350–380°.Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 8, pp. 32–33, August, 1979.     

Production of a dispersion-strengthened nickel-tungsten-aluminum alloy by mechanical alloying

Conclusions Metallographic and x-ray spectral studies of alloy powders subjected to mechanical alloying in a planetary centrifugal mill for various periods of time have shown that the high intensity of alloying in this type of mill enables the duration of the process to be reduced to between one-fifth and one-seventh that necessary with the attritors normally used for this purpose. A study was made of the structure and mechanical properties of rods of a dispersion-strengthened Ni-W-Al alloy produced by extrusion of a mechanically alloyed powder. The rods were found to be characterized by a high degree of structural homogeneity, an elongated grain shape resulting from active directional recrystallization during annealing, and a high level of strength at temperatures of up to 1200°C.Deceased.Translated from Poroshkovaya Metallurgiya, No. 7(235), pp. 44–47, July, 1982.     

Free access stack algorithms for microcellular radio systems

We evaluate the data traffic performance of a centralized packet access protocol for microcellular radio systems supporting both speech and data users. A time-slotted radio channel is assumed. Speech contention is decoupled from data contention to give speech priority over data. A free access stack algorithm is used for handling data contention. An out-slot access scheme is used in which the slots are divided into user-information transmission slots and contention slots for sending transmission requests. The contention slots are subdivided in minislots to improve the access capacity. The out-slot algorithm performances are compared with the performances of a previously proposed in-slot one in which all slots can be used for sending user information. A memoryless channel, with capture and errors, is considered. The effects of speech traffic on data performance are evaluated. Moreover, the paper presents a method for evaluating the packet error probability of a packet cellular system. This method is used for evaluating the proposed algorithm in a microcellular system. An access technique with coordinated operation among cochannel cells is studied. The effects of sectorization on data performances and protocol unfairness are investigated. Different frequency reuse factors are taken into consideration     

A context-tree based model for quantized fading

Fading is modeled by applying context tree pruning (CTP) to the sequence of fading states that results from quantizing a sequence of real-valued fading measurements. There results a family of finite state Markov chains of increasing order that represent the channel with increasing fidelity. A fading state may be the union of chain states. A particular model may be chosen from that family according to an application-specific criterion. The resulting models facilitate analysis and simulation of wireless systems that exploit channel memory. An example criterion compares each model's fading state sojourn time statistics with those of the original sequence     

Utilization of Coke Oven Gas and Converter Gas in the Direct Reduction of Lump Iron Ore

The application of off-gases from the integrated steel plant for the direct reduction of lump iron ore could decrease not only the total production cost but also the energy consumption and CO₂ emissions. The current study investigates the efficiency of reformed coke oven gas (RCOG), original coke oven gas (OCOG), and coke oven gas/basic oxygen furnace gas mixtures (RCOG/BOFG and OCOG/BOFG) in the direct reduction of lump iron ore. The results were compared to that of reformed natural gas (RNG), which is already applied in the commercial direct reduction processes. The reduction of lump ore was carried out at temperatures in the range of 1073 K to 1323 K (800 °C to 1050 °C) to simulate the reduction zone in direct reduction processes. Reflected light microscopy, scanning electron microscopy, and X-ray diffraction analysis were used to characterize the microstructure and the developed phases in the original and reduced lump iron ore. The rate-controlling mechanism of the reduced lump ore was predicted from the calculation of apparent activation energy and the examination of microstructure. At 1073 K to 1323 K (800 °C to 1050 °C), the reduction rate of lump ore was the highest in RCOG followed by OCOG. The reduction rate was found to decrease in the order RCOG > OCOG > RNG > OCOG-BOF > RCOG-BOFG at temperatures 1173 K to 1323 K (900 °C to 1050 °C). The developed fayalite (Fe₂SiO₄), which resulted from the reaction between wüstite and silica, had a significant effect on the reduction process. The reduction rate was increased as H₂ content in the applied gas mixtures increased. The rate-determining step was mainly interfacial chemical reaction with limitation by gaseous diffusion at both initial (20 pct reduction) and moderate (60 pct reduction) stages of reduction. The solid-state diffusion mechanism affected the reduction rate only at moderate stages of reduction.     

Estimation of the vacancy contribution to the work functions of electrons and positrons released from metals

The vacancy contribution to the work functions of electrons and positrons is demonstrated within our previously proposed models by the example of Al. Physical states of affairs in which the vacancy effect can manifest itself are considered.     

Weighted Parzen windows for pattern classification

This paper introduces the weighted-Parzen-window classifier. The proposed technique uses a clustering procedure to find a set of reference vectors and weights which are used to approximate the Parzen-window (kernel-estimator) classifier. The weighted-Parzen-window classifier requires less computation and storage than the full Parzen-window classifier. Experimental results showed that significant savings could be achieved with only minimal, if any, error rate degradation for synthetic and real data sets