Explicit Input Research Articles

Context-aware design and interaction in computer systems

As the human-computer interface becomes more pervasive and intimate, it will need to explicitly draw upon cognitive science as a basis for understanding what people are capable of doing. User experience and situation should be integrated into the computer system design process. Situational awareness can be used to reduce the amount of explicit input a person is required to give a computer. Contextual information of what and where the user task is, what the user knows, and what the system capabilities are, can greatly simplify the user scenario. Such use of contextual models in computers can also reduce the teaching needed for the user to accomplish tasks. An approach to a framework for design of contextual computing is illustrated through examples.

Metabolic engineering from a cybernetic perspective. 1. Theoretical preliminaries

The theoretical basis of a cybernetic metabolic network design and analysis framework, which has been subsequently successfully applied to predict system response to genetic alteration, is presented. This conceptual methodology consists of three main branches, namely, a model realization framework, a representation of genetic alteration, and lastly, a metabolic design component. These concepts are introduced as a series of postulates that describe the basic tenets of the approach. Each branch is discussed in turn, starting with the cybernetic representation of arbitrarily complex metabolic networks. A set of postulates is put forth that affords the modular construction of cybernetic models of metabolic networks using as a base a library of elementary pathways. This is followed by a discussion of the representation of genetic alterations within the cybernetic framework. It is postulated that the objective of the base network and the altered system are identical (at least on the time scale required for the organism to "learn" new objectives). This implies, with respect to resource allocation, that the base network and its genetically altered counterpart may still be treated as optimal systems; however, the set of competing physiological choices open to the altered network expands or contracts depending upon the nature of the genetic perturbation. Lastly, to add a predictive design aspect to the methodology, we present a set of postulates that outline the application of metabolic control analysis to cybernetic model systems. We postulate that sensitivity coefficients computed from a cybernetic model, although still local in scope, have the added benefit of a systematic representation of regulatory function as described by the cybernetic variables. Thus, information gained from sensitivity measurements stemming from a cybernetic model include the explicit input of metabolic regulation, a component that is lacking in a purely kinetic representation of metabolic function. The sensitivity results can then be employed to develop qualitative strategies for the rational alteration of metabolic function, which can be evaluated by simulation of an appropriately modified cybernetic model of the base network.

Data Pre-Processing/Model Initialisation in Neurofuzzy Modelling of Structure-Property Relationships in Al-Zn-Mg-Cu Alloys.

The paper deals with the application of multiple linear regression and neurofuzzy modelling approaches to 7xxx series based aluminium alloys. 36 compositional and ageing time variants and subsequent proof strength and electrical conductivity measurements have been studied. The input datasets have been transformed in two ways: to reveal more explicit microstructural information and to reflect some empirical findings in the literature. Neurofuzzy modelling exhibited improved performance in modelling proof strength and electrical conductivity c.f. the multiple linear regression approach. Electrical conductivity is best modelled using the explicit microstructural input dataset, whilst proof strength is best modelled by a further modification of this dataset, decided upon after inspection of the subnetwork structures produced by neurofuzzy modelling. Neurofuzzy modelling offers a transparent empirically based data-driven approach that can be combined with pre-processing of the data and initialising of the model structure based upon physical understanding. An iterative modelling approach is defined whereby data-driven empirical modelling approaches are first used to assess underlying data structures and are validated against physically based understanding, these then inform subsequent initialised neurofuzzy models and input data transformations to provide both optimal subset and feature representation.

Radial basis function networks for internal model control

In this paper radial basis function (RBF) networks are used in the framework of nonlinear internal model control (IMC). A nonlinear IMC strategy is proposed that includes explicit input weighting. This strategy yields a control law in form of an analytical expression if a control-linear RBF model is used. Important implementation issues such as disturbance modeling and state estimation are discussed and an extended Kalman filter approach is proposed for combined state and model parameter estimation. Simulation studies for a continuous stirred tank reactor with multiple steady states indicate that the proposed control strategy is well suited for the control of unstable nonlinear systems.

Production Efficiency Differences between Large and Small Banks

Management Involves the critical entrepreneurial function besides routine supervision. Since entrepreneurship is not an explicit input, its Impact on output gets refiected by the neutral efficiency parameter in a neoclassical production function framework. Employing the Cobb-Douglas production function, per (standard) branch Income differences between the 14 Large (LBG) and 13 Small (SBG) Bank Groups was accounted for in terms of differential neutral output efficiency, non-neutral resource efficiency use and resource input use per (standard) branch. During 1974-76, the LBG was found to have an edge over the SBC in neutral output efficiency which pattern reversed during 1984-86. The opposite was true with respect to the role of non-neutral resource efficiency use. The contribution of differential input use was in favour of the LBG though the size of the difference declined in convergence over the decade.

Grammatically biased learning: Learning logic programs using an explicit antecedent description language

Every concept learning system produces hypotheses that are written in some sort of constrained language called the concept description language, and for most learning systems, the concept description language is fixed. This paper describes a learning system that makes a large part of the concept description language an explicit input, and discusses some of the possible applications of providing this additional input. In particular, we discuss a technique for learning a logic program such that the antecedent of each clause in the program can be generated by a special antecedent description language; it is shown that this technique can be used to make use of many different types of background knowledge, including constraints on how predicates can be used, programming clichés, overgeneral theories, incomplete theories, and theories syntactically close to the target theory. The approach thus unifies many of the problems previously studied in the field of knowledge-based learning.

Designing Model and Climate Controls of the Greenhouse Cucumber by Means of Repetitive Nonlinear Optimization

Starting from a descriptive plant-physiological model of the growing cucumber, greenhouse climate strategies are developed by means of nonlinear optimization. For this, the descriptive model has been approximated by a simplified time-variant nonlinear dynamic input-output control model. Contrasted with a former version other model in-puts have been chosen. Especially, the global radiation is now an explicit input. A hierarchical control structure with strategic and operative layer allows to take into consideration Apriori-and actual information on the outer climate by means of repetitive optimizations with different repetition periods at the upper and lower layer. Results of simulation runs and greenhouse tests will be reported.

Noise in resonant optical amplifiers of general resonator configuration

The population-statistical description of a linear optical amplifier, extended to include both a resonant optical cavity and explicit input and output photon fluxes, is shown to yield three useful noise relationships. Despite the treatment's plainly particulate character, it provides an expression for the variance of the time-integrated output-photon-detection process in which terms associated with interferometrically generated beat noise are prominent. For systems whose photodetector electrical bandwidth B is much smaller than the amplifier's optical bandwidth Delta v, as is almost invariably the case for semiconductor amplifiers in lightwave-communication systems, the time-integrated photocurrent variance can be written in a simple, physically intuitive form. Two quotients are of central importance: ( Delta nu /B) and the ratio ( <n S="" sub="" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"/> / <n ASE="" sub="" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"/> ) of mean amplified-signal power to mean amplified-spontaneous-emission power. In the usual case of interest for optical amplifiers in communication systems where <n S="" sub="" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"/> >> <n ASE="" sub="" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"/> , the signal-to-noise ratio of the integrated photocurrent, on which the error probability in an on-off-keyed system depends, is approximately=1/2( Delta v/B) ((n/sub S/)/(n/sub ASE/)).< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Statistical analysis of an incoherently coupled, steady-state optical amplifier

The inverted population model of a linear optical amplifier is extended to incorporate explicit input and output photon fluxes. The input field is assumed to be incoherently coupled to the internal field of the amplifier, thus permitting a population statistical description of the complete system, including photon detection. Steady-state behavior and intensity amplification are simultaneously realizable. The integrated statistics of the photoelectron count at the detector are obtained and employed to evaluate a suitably defined signal-to-noise ratio for the system. The conditions under which signal enhancement can occur are derived and discussed for the case in which the input field photocount is Poisson distributed.

Cognitive strengths and weaknesses in language-impaired children: one more look.

The hypothesis-testing abilities of 15 language-impaired and 15 normally developing children matched for mental age were investigated using discrimination-learning tasks. The subjects in both groups were presented with two sets of discrimination-learning problems. One set of problems featured explicit input concerning the correct response choice. The other set of problems featured nonexplicit input. The results revealed both differences in the performance of the MA-matched and language-impaired children and differences in performance on the two types of problems. The children in both groups solved more of the explicit input problems than the nonexplicit input problems. In addition, the MA-matched children performed significantly better than the language-impaired children, particularly on the nonexplicit problems. The findings suggested that the language-impaired children exhibited deficits in solving discrimination-learning problems. The deficits exhibited by the language-impaired children seemed related to deficits in their ability to encode information.

A stochastic model of rainfall interception

A stochastic model of rainfall interception is proposed which relates, via the Poisson probability distribution, the mean number of raindrops retained on elemental surface areas to the mean number of raindrop strikes per element. The model provides a rational explanation of the observation that canopies wet up in a gradual, asymptotic manner. For the special case in which the maximum number of drops retained per surface element is less than or equal to unity, it is shown that the model takes an identical form to the exponential wetting relationship proposed by Aston. The model takes into account mean raindrop volume as an explicit input variable, and predicts that, for the same total amounts of rainfall, maximum canopy storage will be attained less rapidly for raindrops of larger volume.

Self-tuning regulators with explicit variance restrictions

Self-tuning regulators with on-line adaptation of the weights in a quadratic loss function are considered. The criterion for control is to minimize the variances of one or several process variables. Design constraints are taken into account by introducing explicit state and input variance restrictions. The algorithm solves the necessary optimality conditions of the variance-constrained optimal control problem using a stochastic approximation method. A particularly simple algorithm is obtained if the control is based on a single-step loss function. An example taken from multivariate cement kiln control shows, however, that there are practical situations when it is necessary to use a more complex algorithm, which requires the on-line solution of a Riccati equation.

THE USE OF SOCIAL SERVICES BY BLACK AND WHITE ELDERLY

Little is known about the roles of the family, kin, and non-kin support networks in determining the use of social services by the elderly. The purpose of this study was to examine the role of the formal and informal support systems in explaining social service utilization by Black and White elderly. Path analytic procedures are used to test an explanatory model of utilization by a national area probability sample of 3.996 non-institutionalized elderly. The findings indicate that informal family support was more important for Black elderly than White elderly. In addition, family aid was found to be supplementary rather than an alternative support system. In the planning, designing, and delivery of social services to the elderly, it is imperative that racial and cultural differences become explicit input factors. Additionally, future researchers have a responsibility to employ research procedures capable of simultaneously dealing with a comprehensive range of variables in investigating this rather complex p...

New Methods of Controlling Nonlinear System Represented by Discrete Volterra Functional Series

New methods of controlling nonlinear system represented by discrete Volterra functional series are proposed. These methods make it possible to eliminate the effect of disturbance on the desired output by using .explicit input terminals, whose values can be easily set. For this purpose, the system is first identified by a simpler practical recurrent identification method and its inverse system is synthesized to reproduce input functions. Then, the control systems with inverse system and dynamical compensator are built to eliminate the contribution of the disturbance to the output and realize the desired output.

Control aspects of human temperature regulation

Human body temperature control is characterized by a local dependence of system variables and parameters: receptors are thought to be distributed locally throughout the body. The integrative control centres appear to extend quasicontinuously from the spinal cord up to the hypothalamus. Finally, control actions obviously affect the passive system with distinct local dependence. The essential properties of non-linear distributed parameter control of human body temperature are demonstrated by way of experimental and mathematical results. With regard to the control strategy there are evidently five different concepts which claim to answer the question: ‘What is regulated and how?’ A control concept based on spatial integration of temperatures plus local effector actuation seems to be the one which is most adequately supported by system-theoretical as well as by experimental results. The discussion about ‘reference’ and ‘set-point’ of temperature regulation is still going on, and concentrates on four concepts. The concept of balance of passive and active processes, i.e. of controlling and of controlled subsystems, defines the steady-state as the only compatible operating point of the open loop functions in the closed control loop. It does not need an explicit neuronal reference input or difference of controller inputs and solves simultaneously the so-called problem of changing set-point due to fever or to circadian rhythm. This is explained as an adjustment of control parameters requiring another balance of controller and passive system.

Lethal genes and statistics

In some genetic crosses the individuals homozygous for a certain ‘lethal’ gene die, in some cases at an embryonic stage. Heterozygotes may appear perfectly normal. Consider a lethal gene that has no visible effect in heterozygotes and that kills homozygotes for that gene before they can be observed and counted, leading to an altered ratio between the surviving phenotypes. Will the observed ratio in our samples in itself make us suspect the presence of a lethal gene? Three statistical methods are tried. Two traditional methods, the chi‐square test and the binomial test, are shown to require large sample sizes to detect the lethality. The low power of the tests in this application is shown. A Bayesian approach, requiring explicit input from the experimenter, is introduced, and is shown to adapt well to a sequential plan. The lethal gene example illustrates limitations of quantitative (statistical) analyses; we require additional qualitative information to decide whether lethality is present.

Simultaneous Reduction and Expansion of Multidimensional Laplace Transform Kernels

Application of Laplace transforms in linear systems analysis has many well established merits. Analogously, multidimensional Laplace transforms can be employed in the analysis of nonlinear analytic systems to provide similar benefits, including explicit input–output relationships. At present, one of the most serious drawbacks to the use of multidimensional transforms lies with the difficulty in reducing multidimensional kernels during inverse transformation. Herein, simplified reduction and expansion techniques for multidimensional inverse transformation will be presented. The labor involved in their application is comparable to that of familiar inverse transformation through use of Heaviside’s expansions. Examples will help to clarify the techniques.