摘要:

The paper is concerned with the measurement of the 2nd-order kernel in a Volterra-series representation of a nonlinear system by continuous or discrete crosscorrelation using an antisymmetric pseudorandom input signal derived from an m sequence. It is shown that the crosscorrelation measurements are related to the corresponding kernel values by a set of equations which may be structured into a number of independent subsets. The m-sequence properties determine how the maximum order of the subsets for off-diagonal values is related to the upper bound of the arguments for nonzero kernel values, which is used as an index of performance. The performance of signals derived from binary, ternary and quinary m sequences is investigated, and the characteristic polynomials and performance indexes of signals with superior performance are tabulated. Comparison of the results obtained demonstrates the advantages of ternary signals in this application, and an example is used to illustrate the solution of a typical problem.

DOI:10.1049/piee.1972.0081

出版商:IEE    

年代:1972

数据来源: IET

摘要:

The problem of minimum mean-square state estimation for linear stationary systems is considered. State-vector partitioning is employed to arrive at a computationally efficient estimate, and a quantitative measure for the degree of optimality for this estimate is derived. This quantitative measure can then be used to relate the degree of optimality to the particular state-vector partition employed, thus providing an ordering over all admissible partitions of the system. A method of selecting the best partition (i.e. the one that maximises the degree of optimality) is outlined.

DOI:10.1049/piee.1972.0082

出版商:IEE    

年代:1972

数据来源: IET

摘要:

This paper describes the background to the development of corporate financial models with reference to the need for analytical methods in the financial area and the contribution which control and systems engineers could make to satisfy part of this need. Modelling work in the financial planning area is discussed in the context of overall corporate planning of resource allocation to different elements of company activity. The concept of model building in economics is discussed and a number of different types of economic model are described, together with examples. The literature on computerised financial models is reviewed, mainly from the user's point of view. Thereview includes discussions of commercially available models, models applied to specific companies, acquisitionanalysis models and comparisons of different growth models as aids in corporate planning. Mention is also made of work concerning the application of computers to accounting in general and of the use of input-output models for cost accounting problems.

DOI:10.1049/piee.1972.0083

出版商:IEE    

年代:1972

数据来源: IET

摘要:

Measurements of prebreakdown currents have been made for highly polished plane parallel aluminium electrodes in an ultrahigh vacuum (10−9torr), as a function of electrode separation, in the range 0.076–2.8 mm. The prebreakdown currents are found to be consistent with the Fowler-Nordheim field-emission theory. The field-in tensification factor is calculated at each gap separation. For gap separations larger than 0.89 mm, a large increase in the prebreakdown current, at a particular applied voltage (ignition), is observed. The ratio of the current increase, depending on electrode separation, is observed to be in the range 10–160. The ignition voltage is determined as a function of gap separation and found to increase with increasing gap separation. It is suggested that the ignition can only occur at a given gap separation, when the prerequisite values of a prebreakdown current, combined with an applied voltage, are simultaneously present. At short gap separations (≪0.76 mm), the ignition phenomenon is absent. It is shown that this is because the condition for the required current value cannot be satisfied at the required ignition voltage.

DOI:10.1049/piee.1972.0084

出版商:IEE    

年代:1972

数据来源: IET

DOI:10.1049/piee.1972.0085

出版商:IEE    

年代:1972

数据来源: IET

摘要:

A system of resistance thermometry is described which uses thermometer elements of the order of a fraction of an ohm. The advantages obtained include a reduction in the size of the thermometer and the ability to expose it directly to a fluid. The measurement method uses a transformer-coupled potentiometer circuit with a very large ratio between the standard resistor and the thermometer resistance. The measurement method may be applied to other resistive transducers for which a low resistance is advantageous. Substantial lengths of twisted-pair cable may be used. An analysis of the effects of transformer and cable loss is presented, and the question of optimum transformer design is considered in detail. It is shown that, for deflection output, the deviation of the performance of the overall circuit from ideal performance can be kept within 1% this deviation can be taken up in calibration. For null-balance output, the deviation is much smaller.

DOI:10.1049/piee.1972.0086

出版商:IEE    

年代:1972

数据来源: IET

摘要:

A recent development in the construction of electrostatic generators has been to inject charge carriers into a moving liquid stream. A simplified analysis is presented in the paper which gives the distribution of the electrical parameters in the generator duct. Short-circuit calculations are compared with Stuetzer's experimental results using kerosene as the working fluid. The comparison demonstrates the significance of the space-charge effect. The analytical model is then used to predict the load characteristics of Stuetzer's geometrical configuration for realistic values of leakage resistance and breakdown strength. The optimum performance of this geometry is also discussed.

DOI:10.1049/piee.1972.0087

出版商:IEE    

年代:1972

数据来源: IET