A CAD approach for suppression of power supply noise and performance analysis of some multi-core processors in pre-layout stage

In modern system-on-chip, the number of transistors has grown exponentially. This requires an efficient electrical power distribution network for proper functioning of the chip. Voltages at different nodes with respect to the desired level may vary which correspond to generation of supply noise. This paper deals with the estimation and allocation of decoupling capacitance for reduction of supply noise at the pre-layout level. Usually, decoupling capacitors are placed near the noisy functional modules, which acts as local charge storing devices and effectively reduce the transients. In this work, analysis of various sources of supply noises has been performed. Depending on the amount of supply noise, the decoupling capacitance has been estimated and allocated with minimum increment in power consumption and propagation delay. We have considered 512-points, 1-k point, 2-k point and 4-k point Fast Fourier Transform processors and International Test Conference 1999 (b14 and b17) benchmark circuits as our test circuits. This work reports up to 51.9% reduction of peak supply noise at the cost of 0.48 and 1.44% increase in power consumption and delay respectively. This estimation and subsequent allocation of decoupling capacitances will help for more accurate design and implementation at the layout stage.

     

Efficient E-beam excitation of XeCl

Efficient laser output at 308 nm has been obtained from XeCl in an Ne/Xe/HCl mixture at a pressure of 4 atm bye-beam excitation and bye-beam controlled discharge pumping. Maximum energy extraction is 7 J/1 fore-beam excitation and 9 J/1 for thee-beam controlled discharge. Efficiencies based on total energy deposited in the gas are approximately 4 percent. Similar results were obtained with KrF in the same device, indicating that undere-beam ore-beam controlled discharge excitation, XeCl may be as efficient as KrF.     

Theoretical investigations on some rigid-rod polymers used as high-performance materials

This review focuses on a new type of para-catenated aromatic polymer being used in the preparation of high-performance films and fibers of exceptional strength, thermal stability, and environmental resistance, including inertness to essentially all common solvents. Polymers of this type include cis and transpoly(p-phenylene benzobisoxazole) (PBO), and the cis and trans forms of the corresponding poly(p-phenylene benzobis-thiazole)(PBT). The purpose of this paper is to summarize the authors' theoretical work on the structures, conformational energies, intermolecular interactions, and electronic properties of PBO and PBT chains, including the protonated forms known to exist in strong acids. The emphasis is on how such studies provide a molecular understanding of the unusual properties and processing characteristics of this new class of materials.     

Sn-ZSM-12, a new,large pore MTW type tin-silicate molecular sieve: synthesis,characterization and catalytic properties in oxidation reactions

A new large pore tin-silicate analogue of zeolite ZSM-12 (MTW topology) with Si/Sn molar ratio >70 has been synthesized hydrothermally using a new template, hexamethylene bis(benzyl dimethyl ammonium hydroxide). This material exhibits an expansion in unit cell volume (XRD), an IR band at 970 cm^–1 and a charge transfer band at 205 nm in the UV-Vis region indicating the presence of Si-O-Sn units with Sn⁴⁺ centers in T_d configuration. Sn-ZSM-12 catalyzes the oxidation of phenol,m-cresol andm-xylene using dilute H₂O₂ as an oxidizing agent.     

Copper Carbenoid,Reactant and Catalyst for One‐Pot Diazo Ester Coupling Cascade Rearrangement of Enediynes: Formation of Two Contiguous Tetrasubstituted Stereocenters

The copper‐catalyzed reaction of enediynes with diazo esters leads to cyclic amino esters bearing two contiguous tetrasubstituted stereogenic centers through a one‐pot, five‐step cascade. Copper iodide catalyzes the formation of an intermediate 3‐alkynoate and copper carbenoid promotes its reversible isomerization to the corresponding allenoate. The alkynoate‐allenoate equilibrium is completely shifted to the right by the rapid consumption of the allenoate by Myers–Saito cyclization. This is followed by 1,5‐H atom transfer and recombination of the resulting biradical. Memory of chirality phenomenon explains the high enantioselectivity.     

Fibers spun from blends of different molecular weights of polypropylene

Fibers spun from blends of small percentage of plastic grade polypropylene (HMPP) with fiber grade polypropylene (PP) are studied for drawing behavior. A factorial design of experiment is used for a two-stage drawing process with variables, such as percent of HMPP component, first stage draw ratio and temperature, and second stage temperature. Optimization is carried out for breaking stress and modulus of drawn filaments. Breaking stress of up to 0.74 GPa and initial modulus of 7.34 GPa is possible by such an optimization process. These properties are observed for 6% HMPP blend composition. Heat setting of drawn filaments show little changes up to 140°C heat-setting temperature. Large scale structural changes with rapid drop in mechanical properties is observed for 150-160°C heat-set samples.