Worcester Polytechnic Institute

About: Worcester Polytechnic Institute is a education organization based out in Worcester, Massachusetts, United States. It is known for research contribution in the topics: Computer science & Population. The organization has 6270 authors who have published 12704 publications receiving 332081 citations. The organization is also known as: WPI.

Spray casting of steel strip: Process analysis

Abstract: Near-net shape manufacturing (NNSM) of thin steel sections by spray casting eliminates casting as a separate step with attendant improved microstructures and properties and significant energy savings. The process involves atomization of a stream of liquid metal and deposition of droplets in the generated spray on a moving substrate at mass flow rates of 0.25 to 2.5 kg/s. In this paper, NNSM of steel strip by the Osprey spray casting process is investigated by combining numerical simulation and experiments. Critical input parameters for the computation are quantified utilizing existing state-of-the-art mathematical models and specific experiments. Numerical computation of the consolidation of the spray at the substrate during manufacture of thin sections is conducted using bothcontinuum anddiscrete event (“splat solidification”) approaches to predict: (1) variation of strip thickness in the transverse dimension and (2) isotherms and cooling rates across the strip thickness. Predicted geometries of the strip simulated by the continuum model are in good agreement with measurements. Predicted isotherms in narrow strip by the continuum approach are in reasonable agreement with thermocouple measurements for intermediate thicknesses (2 to 5 mm), and the observed microstructure is consistent with predicted cooling rates. The discrete event model predicts significantly higher cooling rates than the continuum model in the basal portion of the strip. This is consistent with the observed grain size in thin strip (

NTRU in Constrained Devices

Abstract: The growing connectivity offered by constrained computing devices signals a critical need for public-key cryptography in such environments. By their nature, however, public-key systems have been difficult to implement in systems with limited computational power. The NTRU public-key cryptosystem addresses this problem by offeringb etter computational performance than previous practical systems. The efficiency of NTRU is applied to a wide variety of constrained devices in this paper, includingthe Palm ComputingPlatform, Advanced RISC Machines ARM7TDMI, the Research in Motion pager, and finally, the Xilinx Virtex 1000 family of FPGAs. On each of these platforms, NTRU offers exceptional performance, enablinga new range of applications to make use of the power of public-key cryptography.

Preparation of nanophase solid state materials.

Abstract: A process for the preparation of nanophase solid state materials having crystallite morphology and particle sizes in the range of from about 1 nm to 30 nm is disclosed. Novel nanophase solid state materials are also disclosed.

Computational fluid dynamics studies of fixed bed heat transfer

Abstract: Fluid flow and heat transfer in a fixed bed of tube to particle ratio 2.86 were studied by solving the 3D Navier–Stokes and energy equations using a commercial finite element code, ANSYS/FLOTRAN. The geometry model consisted of an arrangement of eight spheres. Boundary conditions were given at the wall and the inlet, similar to an experimental setup, to determine the velocity and temperature at various locations. The main objective of this study was to use computational fluid dynamics (CFD) to obtain values for the dimensionless wall heat transfer coefficient, Nuw and the radial effective thermal conductivity ratio, kr/kf, using air as the fluid. Nuw and kr/kf were evaluated from the calculated temperatures at different locations in the bed by fitting these with the analytical solution of the usual two-dimensional pseudo-homogeneous model, using a non-linear least squares analysis. Results were obtained for Reynolds numbers in the range 9–1450. The Nuw and kr/kf values showed reasonable qualitative agreement with both experimental values and values predicted by a model-matching theory based on experimental measurements. Studies were also carried out to verify the depth, pressure and wall temperature dependence of the effective heat parameters. The effect of the temperature profile measurement position above the bed on the estimated parameters, was investigated.