Evaluation of stamping lubricants at various temperature levels using the ironing test

Lubricants are employed in stamping operations in order to (a) improve the material flow into the die cavity, (b) reduce wear and galling in the die and (c) obtain good surface finish of the part. Process conditions such as high temperatures and pressures could cause the lubricant to fail, thus resulting in galling or tearing of the part, damage to the tooling, and lost production. Therefore, selection of an appropriate lubricant based on the process conditions is important in the stamping industry. Several benchmark tests emulating stamping operations have been developed and are used to evaluate the performance of candidate lubricants. The major drawback of most of these tests is their inability to emulate high contact pressures and sliding velocities, which are crucial parameters for lubricity, especially in the case of high-speed progressive or transfer die operations involving ironing. Moreover, most of these tests are conducted at room temperature, while in reality; the process temperature can reach as high as 200 °C. The ironing tribotest developed at the Engineering Research Center for Net Shape Manufacturing (ERC/NSM) induces high contact pressures and temperatures, thus emulating the conditions in a production environment. Application of the test to screen candidate lubricants for stamping operations involving the ironing process is discussed in this paper.     

An implementation of distributed shared memory

Shared memory is a simple yet powerful paradigm for structuring systems. Recently, there has been an interest in extending this paradigm to non-shared memory architectures as well. For example, the virtual address spaces for all objects in a distributed object-based system could be viewed as constituting a global distributed shared memory. We propose a set of primitives for managing distributed shared memory. We present an implementation of these primitives in the context of an object-based operating system as well as on top of Unix.     

An Efficient Parallel Algorithm for the Layered Planar Monotone Circuit Value Problem

A planar monotone circuit (PMC) is a Boolean circuit that can be embedded in the plane and that contains only AND and OR gates. A layered PMC is a PMC in which all input nodes are in the external face, and the gates can be assigned to layers in such a way that every wire goes between gates in successive layers. Goldschlager, Cook and Dymond, and others have developed NC ² algorithms to evaluate a layered PMC when the output node is in the same face as the input nodes. These algorithms require a large number of processors (Ω(n ⁶ ), where n is the size of the input circuit). In this paper we give an efficient parallel algorithm that evaluates a layered PMC of size n in time using only a linear number of processors on an EREW PRAM. Our parallel algorithm is the best possible to within a polylog factor, and is a substantial improvement over the earlier algorithms for the problem. Received April 18, 1994; revised April 7, 1995.     

Electrolytic recovery of zinc from zinc ash using a catalytic anode

The process of galvanisation of steel generates zinc ash as the waste product, thus creating pollution problems. The recovery of zinc metal from zinc ash, with a zinc content of about 76% by leaching and electrowinning has been studied. The presence of chloride has been identified as the major problem area. A catalytic anode based on iridium dioxide (IrO₂) was used as the anode material to overcome this problem. Catalyst loading was kept at an economically acceptable level. The catalyst's stability, energy consumption and efficiency of zinc recovery are discussed. The service life of the IrO₂ active coating has been established by an accelerated polarisation test. The zinc deposit recovered from the zinc ash has been examined by X‐ray diffraction (XRD) and scanning electron microscopy (SEM). Copyright © 2004 Society of Chemical Industry     

A 3.3-V CMOS adaptive analog video line driver with low distortion performance

An analog line driver for video applications is presented. Utilizing a class-AB error amplifier structure, the design achieved 1.2-V peak-to-peak output swing with better than 42-dB linearity for frequencies up to 5 MHz. An adaptive tuning scheme for output impedance matching using peak detection is used to provide uniform performance across line impedance variations. The circuit is designed in AMI 0.5-/spl mu/m CMOS technology and has a tuning range of 70-180 /spl Omega/ with a power consumption of about 26.4 mW at 75-/spl Omega/ load.     

Development of indigenous technology for production of titanium sponge by the Kroll process

Titanium has emerged as a major structural metal for a wide range of industrial applications due to its attractive engineering properties. India has a large and rich reserve base for this metal in the beach sands of the eastern and southern regions with well established production facilities for their separation into individual minerals. Research and Development activities for establishing the metal production technology have been underway in the country for over two decades. The Defence Metallurgical Research Laboratory, Hyderabad, has already demonstrated the metal production technology by the conventional Kroll process on 2000 kg/batch scale and is now all set for demonstrating the same by the more advanced, energy efficient combined process route on 4000 kg/batch scale. The paper reviews the R & D efforts undertaken so far in the field of metal extraction with emphasis on the current status of this developmental activity at DMRL.     

Hydration and strength characteristics of synthetic Al-, Mg- and Fe alites

Alites containing different amounts of Al, Mg or Fe were hydrated up to 30 days and their kinetics of hydration and compressive strengths were determined. At the same degree of hydration Fe-alites showed greatest strength. There was evidence that the nature of C?S?H formed in different alites is not the same.     

Multiple control input design for identification of light aircraft

This paper establishes a design technique for control input histories resulting in higher confidence levels in the estimate of lateral stability and control derivatives of light aircraft, and which cause dynamic motion favorable to reductions in numerical divergence tendencies in the identification algorithms. A combined aileron and rudder input design is demonstrated for the Cessna 172 aircraft.