Partitioning strategy for efficient nonlinear finite element dynamic analysis on multiprocessor computers

A computational procedure is presented for the nonlinear dynamic analysis of unsymmetric structures on vector multiprocessor systems. The procedure is based on a novel hierarchical partitioning strategy in which the response of the unsymmetric and antisymmetric response vectors (modes), each obtained by using only a fraction of the degrees of freedom of the original finite element model. The three key elements of the procedure which result in high degree of concurrency throughout the solution process are: (1) mixed (or primitive variable) formulation with independent shape functions for the different fields; (2) operator splitting or restructuring of the discrete equations at each time step to delineate the symmetric and antisymmetric vectors constituting the response; and (3) two level iterative process for generating the response of the structure. An assessment is made of the effectiveness of the procedure on the CRAY X-MP/4 computers

FIFTY YEARS OF MICROPROCESSOR EVOLUTION: FROM SINGLE CPU TO MULTICORE AND MANYCORE SYSTEMS

Nowadays microprocessors are among the most complex electronic systems that man has ever designed. One small silicon chip can contain the complete processor, large memory and logic needed to connect it to the input-output devices. The performance of today's processors implemented on a single chip surpasses the performance of a room-sized supercomputer from just 50 years ago, which cost over $ 10 million [1]. Even the embedded processors found in everyday devices such as mobile phones are far more powerful than computer developers once imagined. The main components of a modern microprocessor are a number of general-purpose cores, a graphics processing unit, a shared cache, memory and input-output interface and a network on a chip to interconnect all these components [2]. The speed of the microprocessor is determined by its clock frequency and cannot exceed a certain limit. Namely, as the frequency increases, the power dissipation increases too, and consequently the amount of heating becomes critical. So, silicon manufacturers decided to design new processor architecture, called multicore processors [3]. With aim to increase performance and efficiency these multiple cores execute multiple instructions simultaneously. In this way, the amount of parallel computing or parallelism is increased [4]. In spite of mentioned advantages, numerous challenges must be addressed carefully when more cores and parallelism are used.This paper presents a review of microprocessor microarchitectures, discussing their generations over the past 50 years. Then, it describes the currently used implementations of the microarchitecture of modern microprocessors, pointing out the specifics of parallel computing in heterogeneous microprocessor systems. To use efficiently the possibility of multi-core technology, software applications must be multithreaded. The program execution must be distributed among the multi-core processors so they can operate simultaneously. To use multi-threading, it is imperative for programmer to understand the basic principles of parallel computing and parallel hardware. Finally, the paper provides details how to implement hardware parallelism in multicore systems

Framework for universal NMR quantum computing using Heisenberg spin interaction

Quantum computing using the control techniques of nuclear magnetic resonance (NMR) has been one of the first experimental implementations of quantum informa- tion processing. By rotating nuclear spins inside molecules with magnetic fields, it is possible to implement any unitary operation on a set of spin-1/2-qubits. Since published work has so far been limited to the Ising spin interaction, this thesis extends the framework of NMR quantum computing to the Heisenberg interaction. In order to find NMR pulse sequences that represent quantum gates in the machine language of NMR quantum computing, magnetic and radio-frequency fields, an algorithm was implemented to examine billions of possible sequences for a universal set of quantum gates. The Python program was optimized to avoid the numerically most expensive calculations so that sequences up to nine pulses could be investigated. The search yielded an NMR pulse sequence for the anisotropic Heisenberg interaction that im- plements the CNOT quantum gate on an arbitrary input state. However, no such sequence was found for the isotropic Heisenberg interaction for a sequence of up to nine pulses in length and while restricting the single-qubit rotations to a finite set of rotation angles. The framework of NMR quantum computing can thus be extended to the Heisenberg interaction although it is not clear if universal quantum computing is possible using only the isotropic Heisenberg interaction to entangle two qubits