EXPERIMENTAL STUDY ON HIGH-SPEED CHARACTERISTICS OF AUTOMOTIVE ENGINE OIL-PUMP CHAIN

The high-speed multi-cycle impact and speed, load fluctuant characteristics of a kind of narrow-width automotive engine oil-pump chain 06BN-1 are studied through engine assembly and road-drive tests to satisfy the light-weight demand of engine. The worn surface morphologies of rubbing area between pin, bush and roller are also analyzed based on scanning electron microscope. The results show that the main wear mechanism of automotive engine oil-pump chain is fatigue wear, and it's failure mechanism is the forming, extending and flaking of cracks on top layer of pin and bush. Pin and bush both occurred cycle-soften phenomenon, and roller occurred cycle-harden. Fretting wear is one of the most important "fall to pieces" failure causes of automotive chain. Ensuring sufficient strength and plasticity of roller, as well as adopting suitable shaping technology are the effective methods to increase its resistance to multi-cycle impact.     

Cold model studies of mixing and mass transfer in steelmaking vessels

Abstract

Room temperature model studies using water to simulate 'metal' and paraffin oil (when required) as 'slag' were conducted to study the extent of mixing and the rate of mass transfer between metal and slag in the 130 t basic oxygen furnaces (BOFs) in operation in Tata Steel. Several systems of gas injection including top blowing, combined blowing and exclusive bottom purging were investigated. Similar work was undertaken in a room temperature model of an 80 t energy optimising furnace (EOF), in operation for a brief period earlier in Tata Steel. Details of the optimum blowing conditions, including the number/distribution of bottom tuyeres for the BOFs, are elaborated in the present paper. How mixing/mass transfer in an EOF compares with the BOF case(s) is also highlighted.     

EXPERIMENTAL STUDY ON SUPERFI- CIAL COAT OF GEARS OF NITRIDED 32Cr2MoV COATED WITH TiN FILM BY MULTI-ARC ION PLATING

After 32CrMoV is selected to manufacture nitrided gears coated with TiN by multi-arc ion plating,all of these uncoated gears and coated gears run in the gearbox under the same initial condi- tions so as to compare their difference concerning properties and microstructure.Experiment results indicate that tooth surface of the coated-TiN gears does not suffer surface abnormalities in meshed zone.Instead,the gears with nitrided case exhibit an abrasion mark on the meshed zone of tooth sur- face,which results in more weight loss of nitrided gears.The morphology of the surface suggests TiN film with more than 2000HV is so dense and smooth that coated-TiN gears have higher wear resis- tance compared with the uncoated gears.The microstructure of coated-TiN gears is finer,hardness is higher and its distribution of coated=TiN gears is more reliable than uncoated ones,which makes nitride layer combined with TiN film tightly.Consequently,the wear-resistance of gears has been dramatically promoted.     

Low Temperature Thermodynamic Study of the Stable and Metastable Phases of Silver

The low temperature thermodynamics of the stable phase of silver was assessed by the polynomial model and Debye model from the experimental data available in the literature. By means of the constrained non-linear least squares curve fitting arithmetic, two sets of parameter values were determined. The expression of the thermodynamic functions cp(T) and G(T)-H (298.15K) at 0-298.15K were presented. Only the low temperature thermodynamics of the metastable phase of silver can be extrapolated by the Debye model. The expression of the thermodynamic functions cp(T) at 0-298.15K was presented.     

NUMERICAL STUDY OF FLOW IN CONICAL DIFFUSER WITH VORTEX GENERATOR JETS

To develop vortex generator jet (VGJ) method for flow control, the turbulence flow in a 144°conical diffuser with and without vortex generator jets are simulated by solving Navier-Stokes equations with κ -ε turbulence model. The diffuser performance, based on different velocity ratio (ratio of the jet speed to the mainstream velocity), is investigated and compared with the experimental study. On the basis of the flow characteristics using computation fluid dynamics (CFD) method observed in the conical diffuser and the downstream development of the longitudinal vortices, attempt is made to correlate the pressure recovery coefficient with the behavior of vortices produced by vortex generator jets.     

Voice/Data Integrated Wireless Channel Access in Third Generation Digital Cellular Networks: The Performance of Bursty Data Generated by Interactive Applications

Mobile wireless communications, which includecellular telephones, land mobile radio, and personalcommunications systems, have experienced enormous growthover the last decade. Data services represent a critical component of future wirelesscommunications, but have received little attention sofar. While some attention has been given to specializedmobile data networks, less has been directed at the ongoing design of data services in evolvingthird generation digital cellular wireless networks. Inthis work we present the results of a simulation studythat explores the performance of a Reservation Random Access (RRA) scheme for transmittingdata packets over a common radio broadcast channel in acellular radio environment. In addition to voicetraffic, we consider data packet traffic generated by interactive applications. It is expected thatsuch applications will be very important in thirdgeneration wireless access mobile communication systems.Through an extensive simulation study of the data message delay distribution, we show that theproposed RRA scheme, originally designed under thePoisson data message arrival process assumption, canalso efficiently operate and be optimized under theextremely bursty data message arrival processcharacterized by independent, identically distributed,Pareto message interarrival times.