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Articles 4321 - 4350 of 4606

Full-Text Articles in Engineering

Observation And Investigation Of The Ferrielectric Subphase With Qt>1/2, Yuri Panarin, O. Kalinovskaya, J. K. Vij Jan 1997

Observation And Investigation Of The Ferrielectric Subphase With Qt>1/2, Yuri Panarin, O. Kalinovskaya, J. K. Vij

Articles

The high-temperature femelectric phase with qT > 1/2 has been found to exist in a antiferroelectric liquid crystal. This phase has been identified using dielectric spectroscopy and conoscopy.


Closed Loop Time Domain Gradient Methods For Parameter And Time Delay Estimation, M, Behan, M Cahill, M. Carry, G Clausen, V. Dooley, N. English, W. Grainger, D. O'Connor, Aidan O'Dwyer, John Ringwood Jan 1997

Closed Loop Time Domain Gradient Methods For Parameter And Time Delay Estimation, M, Behan, M Cahill, M. Carry, G Clausen, V. Dooley, N. English, W. Grainger, D. O'Connor, Aidan O'Dwyer, John Ringwood

Conference papers

This paper discusses the estimation of process parameters and time delay, in a Smith predictor structure, using gradient algorithms in the time domain. A number of estimation algorithms are outlined and applied in simulation to the estimation of the parameters of an appropriate process model. An analytical exploration of the technique is also provided.


Bs News Jan 1997

Bs News

Building Services Engineering

No abstract provided.


Investigation Of The Ferrielectric Subphase With Qt>1/2 Under Bias Voltage, Yuri Panarin, O.E. Kalinovskaya, J.K. Vij Jan 1997

Investigation Of The Ferrielectric Subphase With Qt>1/2 Under Bias Voltage, Yuri Panarin, O.E. Kalinovskaya, J.K. Vij

Articles

The properties of Femelectric phase with qT > 112 have been investigated using broadband dielectric spectroscopy and polarization measurements under the bias voltage. The field -induced sequence of phase transitions is found to be different fiom those of the conventional femelectric phases with qTS 112


A Study Of Antiferroelectric Liquid Crystals Using The Pyroelectric Technique, J.W. O'Sullivan, Yuri Panarin, J.K. Vij, A.J. Seed, M. Hird, J.W. Goodby Jan 1997

A Study Of Antiferroelectric Liquid Crystals Using The Pyroelectric Technique, J.W. O'Sullivan, Yuri Panarin, J.K. Vij, A.J. Seed, M. Hird, J.W. Goodby

Articles

Antiferroelectric liquid crystals are studied using the pyroelecmc technique. The effects of temperature and applied voltage on the pyroelectric signal are examined. The pyroelecmc signal can detect phase changes that occur due to temperature and bias voltage. A high temperature femelecmc phase FiLC is found and the stability of this phase under different bias voltages is examined


Bs News Oct 1996

Bs News

Building Services Engineering

No abstract provided.


Bs News Sep 1996

Bs News

Building Services Engineering

No abstract provided.


Bs News Jul 1996

Bs News

Building Services Engineering

No abstract provided.


Bs News Jun 1996

Bs News

Building Services Engineering

No abstract provided.


Bs News May 1996

Bs News

Building Services Engineering

No abstract provided.


Bs News Apr 1996

Bs News

Building Services Engineering

No abstract provided.


Bs News Mar 1996

Bs News

Building Services Engineering

No abstract provided.


Bs News Feb 1996

Bs News

Building Services Engineering

No abstract provided.


Termes De Signes Positif Et Négatif En Analyses Exergétiques Des Flux De Chaleur, Jim Mcgovern, Pierre Le Goff Jan 1996

Termes De Signes Positif Et Négatif En Analyses Exergétiques Des Flux De Chaleur, Jim Mcgovern, Pierre Le Goff

Articles

In various technical plants there are heat transfer rates at temperatures above that of the environment and other simultaneous heat transfer rates at temperatures below the temperature of the environment. This is the case in cryogenic industrial processes where a cooling effect is produced from a heat source. This is also the case for all absorption refrigeration plants or absorption plants that provide refrigeration and heat pumping, notably for air-conditioning of buildings. In these cases exergetic analysis leads to equations in which some terms are positive and others are negative. This can pose problems in the definition of exergetic, or …


Knowledge-Based System For Casting Process Selection, Ahmet Er, Edward Sweeney, Voya Kondic Jan 1996

Knowledge-Based System For Casting Process Selection, Ahmet Er, Edward Sweeney, Voya Kondic

Articles

Design of casting entails the knowledge of various interacting factors that are unique to casting process, and, quite often, product designers do not have the required foundry-specific knowledge. Casting designers normally have to liaise with casting experts in order to ensure the product designed is castable and the optimum casting method is selected. This two-way communication results in long design lead times, and lack of it can easily lead to incorrect casting design. A computer-based system at the discretion of a design engineer can, however, alleviate this problem and enhance the prospect of casting design for manufacture. This paper proposes …


The Control Of A Process With Time Delay By Using A Modified Smith Predictor Compensator, Aidan O'Dwyer, John Ringwood Jan 1996

The Control Of A Process With Time Delay By Using A Modified Smith Predictor Compensator, Aidan O'Dwyer, John Ringwood

Conference papers

A modification is proposed to the Smith predictor compensator structure for the control of a process with time delay. The modification facilitates the achievement of an improved closed loop system regulator response, with little degradation in the corresponding servo response. The compensator design procedure is discussed, and simulation results are provided to demonstrate the applicability of the method.


Software Quality: Definitions And Strategic Issues, Ronan Fitzpatrick Jan 1996

Software Quality: Definitions And Strategic Issues, Ronan Fitzpatrick

Reports

This paper contains two sections relating to software quality issues. First, the various definitions of software quality are examined and an alternative suggested. It continues with a review of the quality model as defined by McCall, Richards and Walters in 1977 and mentions the later model of Boëhm published in 1978. Each of McCall's quality factors is reviewed and the extent to which they still apply in the late 1990s is commented on. The factors include, integrity, reliability, usability, accuracy, efficiency, maintainability, testability, flexibility,interface facility (interoperability), re-usability and transferability (portability). They are subdivided into external and internal quality factors. Interrelationships …


Theoretical Investigations Of Electro-Optical Synchonisation Of Self-Pulsating Laser Diodes, A. Egan, P. Rees, J. O'Gorman, M. Harley-Stead, Gerald Farrell, Joe Hegarty, P. Phelan Jan 1996

Theoretical Investigations Of Electro-Optical Synchonisation Of Self-Pulsating Laser Diodes, A. Egan, P. Rees, J. O'Gorman, M. Harley-Stead, Gerald Farrell, Joe Hegarty, P. Phelan

Articles

The synchronisation mechanism of selfpulsating laser diodes is determined and it is shown how this results in a frequency-dependent phase difference between the electrical input and optical output. The time-to-lock of the electrical input to the optical output is examined, particularly with regard to the importance of the initial phase difference between the signals. The effect of synchronisation on timing jitter in self pulsating lasers is also investigated.


Bs News Jan 1996

Bs News

Building Services Engineering

No abstract provided.


Bs News Oct 1995

Bs News

Building Services Engineering

No abstract provided.


Bs News Sep 1995

Bs News

Building Services Engineering

No abstract provided.


Chp And Energy Conservation, Jim Mcgovern Sep 1995

Chp And Energy Conservation, Jim Mcgovern

Articles

The principles of the use of 'combined heat and power' (CHP) for the achievement of fuel energy conservation, minimisation of environmental impact and economic advantage are explained. A distinction is made between the two types of outputs: heat and work. It is argued that an efficiency value that is defined as the sum of the heat and work outputs divided by the energy of the fuel used is not very meaningful. An alternative, rational, efficiency is explained. It is concluded that CHP is an option to be considered where both heating and power are required, but is not a general …


Bs News Jun 1995

Bs News

Building Services Engineering

No abstract provided.


Bs News Jun 1995

Bs News

Building Services Engineering

No abstract provided.


Bs News Jun 1995

Bs News

Building Services Engineering

No abstract provided.


Bs News May 1995

Bs News

Building Services Engineering

No abstract provided.


Bs News Apr 1995

Bs News

Building Services Engineering

No abstract provided.


Bs News Mar 1995

Bs News

Building Services Engineering

No abstract provided.


Bs News Feb 1995

Bs News

Building Services Engineering

No abstract provided.


Model Parameter And Time Delay Estimation In The Frequency Domain, Aidan O'Dwyer, John Ringwood Jan 1995

Model Parameter And Time Delay Estimation In The Frequency Domain, Aidan O'Dwyer, John Ringwood

Conference papers

This paper discusses the estimation of the parameters (including the time delay) of single input, single output (SISO) process models from an appropriate number of arbitrarily specified points on the process frequency response. The method involves combining an analytical approach with a least squares approach using a gradient algorithm, to provide accurate and robust estimates of the parameters.