Dispersive optical bistability in a ring cavity

Equations governing the behaviour of a single mode high-Q ring cavity are obtained for a coherent driving field (detuned to both cavity and atoms) and inhomogeneously broadened atomic transitions using a Hamiltonian approach. We find the region of bistability and critical points in the homogeneous broadening case. Numerical results including inhomogeneous broadening show that bistability is obtained more readily by detuning both the atomic transition and the cavity mode relative to the driving field.     

Modeling to support reliability enhancement during product development with applications in the U.K. Aerospace industry

Reliability improvement is the conceptual norm but has not been achieved by all sectors of industry. The U.K. aerospace industry is one that has aspired to make the transition from a culture of reliability demonstration to enhancement. This paper presents action research that examines the challenges facing this industry. A statistical model is developed to help measure the likely impact of failure modes on operational performance, hence providing a basis for managing the enhancement process. The model, which has general applicability to other product development processes, is stated and justified. The industrial interventions are described and an analysis of findings is presented. The proposed model is better than traditional approaches because it provides a systematic process to capture and integrate data from different sources to estimate reliability by directly measuring the engineering improvement achieved through product design and development. The estimates can be used to inform a traceable coherent argument about the level and growth in reliability to management and the customer as well as to provide insight into the impact of alternative engineering modifications to the design team. The modeling process has contributed to the partial transition to reliability enhancement of a consortium of companies who have changed their standard operating procedures to reflect the lessons learned from the research intervention. The insights gained contribute to an understanding of how the U.K. aerospace industry is changing its management of reliability enhancement in design.     

A coherent nonlinear mechanism for optical bistability from three level atoms

A novel scheme for optical bistability in a coherently driven three level atomic system is proposed. The scheme utilizes the non absorption resonance which occurs due to a population trapping in a coherent superposition of the ground state sublevels. The resulting optical bistability occurs for a lower threshold power than for a two level system and is insensitive to Doppler and laser bandwidth effects.     

Exact Fokker-Planck equations from stochastic master equations

A method for deriving exact Fokker-Planck equations from stochastic master equations by expanding the probability distribution in terms of Poisson distribution is given. It is applied to two non-linear chemical processes to obtain the steady state distributions.     

Interpretation and control of C-V measurementsusing pattern recognition and expert system techniques

The authors demonstrate how a pattern-recognition system can be applied to the interpretation of capacitance-voltage (C-V ) curves on an MOS test structure. By intelligently sequencing additional measurements it is possible to accurately extract the maximum amount of information available from C-V and conductance-voltage (G-V) measurements. The expert system described, (CV-EXPERT), is completely integrated with the measurement, instrumentation, and control software and is thus able to call up a sequence of individually tailored tests for the MOS test structure under investigation. The prototype system is able to correctly identify a number of process faults, including a leaky oxide, as shown. Improvements that could be gained from developing rules to coordinate G-V, capacitance-time, and doping profile measurements simply by recognizing the important factors in the initial C- V measurement are illustrated     

Groups with maximal subgroups of Sylow subgroups normal

This paper characterizes those finite groups with the property that maximal subgroups of Sylow subgroups are normal. They are all certain extensions of nilpotent groups by cyclic groups.     

Quantitative analysis of field-ion micrographs using moiré techniques

It has previously been demonstrated that the configuration of imaged atoms on the surface of a field-ion emitter may be interpreted as a moiré pattern. As a consequence it becomes possible to relate the structure of each plane in a field-ion image to that of a number of other planes, by means of ring counting procedures, and hence to obtain precise quantitative information concerning the emitter geometry. Here it is shown how the analysis may be applied to an understanding of how the various planar facets develop, to the determination of the relative field evaporation rates of different planes, and to the measurement of more accurate values of local radius.