23 resultados para Mean-value solution
em Aston University Research Archive
Resumo:
In many Environmental Information Systems the actual observations arise from a discrete monitoring network which might be rather heterogeneous in both location and types of measurements made. In this paper we describe the architecture and infrastructure for a system, developed as part of the EU FP6 funded INTAMAP project, to provide a service oriented solution that allows the construction of an interoperable, automatic, interpolation system. This system will be based on the Open Geospatial Consortium’s Web Feature Service (WFS) standard. The essence of our approach is to extend the GML3.1 observation feature to include information about the sensor using SensorML, and to further extend this to incorporate observation error characteristics. Our extended WFS will accept observations, and will store them in a database. The observations will be passed to our R-based interpolation server, which will use a range of methods, including a novel sparse, sequential kriging method (only briefly described here) to produce an internal representation of the interpolated field resulting from the observations currently uploaded to the system. The extended WFS will then accept queries, such as ‘What is the probability distribution of the desired variable at a given point’, ‘What is the mean value over a given region’, or ‘What is the probability of exceeding a certain threshold at a given location’. To support information-rich transfer of complex and uncertain predictions we are developing schema to represent probabilistic results in a GML3.1 (object-property) style. The system will also offer more easily accessible Web Map Service and Web Coverage Service interfaces to allow users to access the system at the level of complexity they require for their specific application. Such a system will offer a very valuable contribution to the next generation of Environmental Information Systems in the context of real time mapping for monitoring and security, particularly for systems that employ a service oriented architecture.
Resumo:
Flow control in Computer Communication systems is generally a multi-layered structure, consisting of several mechanisms operating independently at different levels. Evaluation of the performance of networks in which different flow control mechanisms act simultaneously is an important area of research, and is examined in depth in this thesis. This thesis presents the modelling of a finite resource computer communication network equipped with three levels of flow control, based on closed queueing network theory. The flow control mechanisms considered are: end-to-end control of virtual circuits, network access control of external messages at the entry nodes and the hop level control between nodes. The model is solved by a heuristic technique, based on an equivalent reduced network and the heuristic extensions to the mean value analysis algorithm. The method has significant computational advantages, and overcomes the limitations of the exact methods. It can be used to solve large network models with finite buffers and many virtual circuits. The model and its heuristic solution are validated by simulation. The interaction between the three levels of flow control are investigated. A queueing model is developed for the admission delay on virtual circuits with end-to-end control, in which messages arrive from independent Poisson sources. The selection of optimum window limit is considered. Several advanced network access schemes are postulated to improve the network performance as well as that of selected traffic streams, and numerical results are presented. A model for the dynamic control of input traffic is developed. Based on Markov decision theory, an optimal control policy is formulated. Numerical results are given and throughput-delay performance is shown to be better with dynamic control than with static control.
Resumo:
A formalism for describing the dynamics of Genetic Algorithms (GAs) using method s from statistical mechanics is applied to the problem of generalization in a perceptron with binary weights. The dynamics are solved for the case where a new batch of training patterns is presented to each population member each generation, which considerably simplifies the calculation. The theory is shown to agree closely to simulations of a real GA averaged over many runs, accurately predicting the mean best solution found. For weak selection and large problem size the difference equations describing the dynamics can be expressed analytically and we find that the effects of noise due to the finite size of each training batch can be removed by increasing the population size appropriately. If this population resizing is used, one can deduce the most computationally efficient size of training batch each generation. For independent patterns this choice also gives the minimum total number of training patterns used. Although using independent patterns is a very inefficient use of training patterns in general, this work may also prove useful for determining the optimum batch size in the case where patterns are recycled.
Resumo:
The Government has established essential principles in order to make significant improvements in the health of the people and has placed an emphasis on shifting care to the primary sening. This research has explored the potential role of the community pharmacist in health promotion in the pharmacy, and at general medical practices. The feasibility of monitoring patients' health status in the community was evaluated by intervention to assess and alter cardiovascular risk factors.68, hypertensive patients, monitored at one surgery, had a change in mean systolic blood pressure from 158.28 to 146.55 mmHg, a reduction of 7.4%, and a change in mean diastolic bood pressure from 90.91 to 84.85 mmHg, a reduction of 6.7%.120 patients, from a cohort of 449 at the major practice, with an initial serum total cholesterol of 6.0+mmol/L, experienced a change in mean value from 6.79 to 6.05 mmol/L, equivalent to a reduction of 10.9%. 86% of this patient cohort showed a decrease in cholesterol concentration. Patients, placed in a high risk category according to their coronary rank score, assessed at the first health screening, showed a consistent and significant improvement in coronary score throughout the study period of two years. High risk and intermediate risk patients showed improvements in coronary score of 52% and 14% respectively. Patients in the low risk group maintained their good coronary score. In some cases, a patient's improvement was effected in liaison with the GP, after a change or addition of medication and/or dosage.Pharmacist intervention consisted of advice on diet and lifestyle and adherence to medication regimes. It was concluded that a pharmacist can facilitate a health screening programme in the primary care setting, and provide enhanced continuity of care for the patient.
Resumo:
The size frequency distributions of discrete β-amyloid (Aβ) deposits were studied in single sections of the temporal lobe from patients with Alzheimer's disease. The size distributions were unimodal and positively skewed. In 18/25 (72%) tissues examined, a log normal distribution was a good fit to the data. This suggests that the abundances of deposit sizes are distributed randomly on a log scale about a mean value. Three hypotheses were proposed to account for the data: (1) sectioning in a single plane, (2) growth and disappearance of Aβ deposits, and (3) the origin of Aβ deposits from clusters of neuronal cell bodies. Size distributions obtained by serial reconstruction through the tissue were similar to those observed in single sections, which would not support the first hypothesis. The log normal distribution of Aβ deposit size suggests a model in which the rate of growth of a deposit is proportional to its volume. However, mean deposit size and the ratio of large to small deposits were not positively correlated with patient age or disease duration. The frequency distribution of Aβ deposits which were closely associated with 0, 1, 2, 3, or more neuronal cell bodies deviated significantly from a log normal distribution, which would not support the neuronal origin hypothesis. On the basis of the present data, growth and resolution of Aβ deposits would appear to be the most likely explanation for the log normal size distributions.
Resumo:
Purpose: To describe and validate bespoke software designed to extract morphometric data from ciliary muscle Visante Anterior Segment Optical Coherence Tomography (AS-OCT) images. Method: Initially, to ensure the software was capable of appropriately applying tiered refractive index corrections and accurately measuring orthogonal and oblique parameters, 5 sets of custom-made rigid gas-permeable lenses aligned to simulate the sclera and ciliary muscle were imaged by the Visante AS-OCT and were analysed by the software. Human temporal ciliary muscle data from 50 participants extracted via the internal Visante AS-OCT caliper method and the software were compared. The repeatability of the software was also investigated by imaging the temporal ciliary muscle of 10 participants on 2 occasions. Results: The mean difference between the software and the absolute thickness measurements of the rigid gas-permeable lenses were not statistically significantly different from 0 (t = -1.458, p = 0.151). Good correspondence was observed between human ciliary muscle measurements obtained by the software and the internal Visante AS-OCT calipers (maximum thickness t = -0.864, p = 0.392, total length t = 0.860, p = 0.394). The software extracted highly repeatable ciliary muscle measurements (variability ≤6% of mean value). Conclusion: The bespoke software is capable of extracting accurate and repeatable ciliary muscle measurements and is suitable for analysing large data sets.
Resumo:
Efficient numerical modelling of the power, spectral and statistical properties of partially coherent quasi-CW Raman fiber laser radiation is presented. XPM between pump wave and generated Stokes wave is not important in the generation spectrum broadening and XPM term can be omitted in propagation equation what sufficiently speeds-up simulations. The time dynamics of Raman fiber laser (RFL) is stochastic exhibiting events several times more intense that the mean value on the ps timescale. However, the RFL has different statistical properties on different time scales. The probability density function of spectral power density is exponential for the generation modes located either in the spectrum centre or spectral wings while the phases are distributed uniformly. The pump wave preserves the initial Gaussian statistics during propagation in the laser cavity. Intense pulses in the pump wave are evolved under the SPM influence and are not disturbed by the dispersion. Contrarily, in the generated wave the dispersion plays a significant role that results in stochastic behavior. © 2012 Elsevier B.V. All rights reserved.
Resumo:
We measure the radial profile of the photoelastic coefficient C(r) in single-mode polymer optical fibers (POFs), and we determine the evolution of C(r) after annealing the fibers at temperatures from 40°C to 80°C. We demonstrate that C(r) in the fibers drawn from a preform without specific thermal pre-treatment changes and converges to values between 1.2 and 1.6×10-12 Pa-1 following annealing at 80°C. The annealed fibers display a smoothened radial profile of C(r) and a lowered residual birefringence. In contrast, the mean value of C(r) of the fiber drawn from a preform that has been pre-annealed remains constant after our annealing process and is significantly higher, i.e., 4×10-12 Pa-1. The annealing process decreases the residual birefringence to a lower extent as well. These measurements indicate the impact of annealing on the thermal stability of the photoelastic coefficient of POFs, which is an essential characteristic in view of developing POF-based thermomechanical sensors.
Resumo:
A numerical method for the Dirichlet initial boundary value problem for the heat equation in the exterior and unbounded region of a smooth closed simply connected 3-dimensional domain is proposed and investigated. This method is based on a combination of a Laguerre transformation with respect to the time variable and an integral equation approach in the spatial variables. Using the Laguerre transformation in time reduces the parabolic problem to a sequence of stationary elliptic problems which are solved by a boundary layer approach giving a sequence of boundary integral equations of the first kind to solve. Under the assumption that the boundary surface of the solution domain has a one-to-one mapping onto the unit sphere, these integral equations are transformed and rewritten over this sphere. The numerical discretisation and solution are obtained by a discrete projection method involving spherical harmonic functions. Numerical results are included.
Resumo:
Purpose - Managers at the company attempt to implement a knowledge management information system in an attempt to avoid loss of expertise while improving control and efficiency. The paper seeks to explore the implications of the technological solution to employees within the company. Design/methodology/approach - The paper reports qualitative research conducted in a single organization. Evidence is presented in the form of interview extracts. Findings - The case section of the paper presents the accounts of organizational participants. The accounts reveal the workers' reactions to the technology-based system and something of their strategies of resistance to the system. These accounts also provide glimpses of the identity construction engaged in by these knowledge workers. The setting for the research is in a knowledge-intensive primary industry. Research was conducted through observation and interviews. Research limitations/implications - The issues identified are explored in a single case-study setting. Future research could look at the relevance of the findings to other settings. Practical implications - The case evidence presented indicates some of the complexity of implementation of information systems in organizations. This could certainly be seen as more evidence of the uncertainty associated with organizational change and of the need for managers not to expect an easy adoption of intrusive IT solutions. Originality/value - This paper adds empirical insight to a largely conceptual literature. © Emerald Group Publishing Limited.
Resumo:
Purpose – The purpose of this paper is to demonstrate the need for an improved understanding of consumer value for online grocery purchases and to propose the notion of “integrated service solution” packages as a strategy for growing and successfully sustaining the channel to guide both marketing strategy and policy. Design/methodology/approach – This paper integrates and synthesises research from retailing, consumer behaviour and service quality literatures in order to develop a conceptual framework for understanding the value of e-grocery shopping to aid practitioners to address the critical needs, expectations and concerns of consumers for the development of grocery shopping within the online environment. Findings – This paper offers an alternative approach to allow e-grocery to become a mainstream retail channel in its own right and not to compete with the in-store offerings. The research demonstrates the need for a progressive approach that follows contemporary consumer needs and habits at the household level. The conjecture is that shopping for fast-moving consumer goods follows a learning path that needs to be replicated in the online context. Moreover, it is suggested that consumer resistance to the adoption of the new channel should be addressed not only from a technological perspective but also from the social aspects of online shopping. Originality/value – The research provides a practical framework for both retailers and policy makers on how the “next generation” of online services can be developed using a “bottom up” consumer perspective. This paper also advocates a non-technological bias to e-grocery retailing strategy.
Resumo:
The International Cooperation Agency (identified in this article as IDEA) working in Colombia is one of the most important in Colombian society with programs that support gender rights, human rights, justice and peace, scholarships, aboriginal population, youth, afro descendants population, economic development in communities, and environmental development. The identified problem is based on the diversified offer of services, collaboration and social intervention which requires diverse groups of people with multiple agendas, ways to support their mandates, disciplines, and professional competences. Knowledge creation and the growth and sustainability of the organization can be in danger because of a silo culture and the resulting reduced leverage of the separate group capabilities. Organizational memory is generally formed by the tacit knowledge of the organization members, given the value of accumulated experience that this kind of social work implies. Its loss is therefore a strategic and operational risk when most problem interventions rely on direct work in the socio-economic field and living real experiences with communities. The knowledge management solution presented in this article starts first, with the identification of the people and groups concerned and the creation of a knowledge map as a means to strengthen the ties between organizational members; second, by introducing a content management system designed to support the documentation process and knowledge sharing process; and third, introducing a methodology for the adaptation of a Balanced Scorecard based on the knowledge management processes. These three main steps lead to a knowledge management “solution” that has been implemented in the organization, comprising three components: a knowledge management system, training support and promotion of cultural change.
Resumo:
In this work the solution of a class of capital investment problems is considered within the framework of mathematical programming. Upon the basis of the net present value criterion, the problems in question are mainly characterized by the fact that the cost of capital is defined as a non-decreasing function of the investment requirements. Capital rationing and some cases of technological dependence are also included, this approach leading to zero-one non-linear programming problems, for which specifically designed solution procedures supported by a general branch and bound development are presented. In the context of both this development and the relevant mathematical properties of the previously mentioned zero-one programs, a generalized zero-one model is also discussed. Finally,a variant of the scheme, connected with the search sequencing of optimal solutions, is presented as an alternative in which reduced storage limitations are encountered.
Resumo:
Public values are moving from a research concern to policy discourse and management practice. There are, though, different readings of what public values actually mean. Reflection suggests two distinct strands of thinking: a generative strand that sees public value emerging from processes of public debate; and an institutional interpretation that views public values as the attributes of government producers. Neither perspective seems to offer a persuasive account of how the public gains from strengthened public values. Key propositions on values are generated from comparison of influential texts. A provisional framework is presented of the values base of public institutions and the loosely coupled public propositions flowing from these values. Value propositions issue from different governing contexts, which are grouped into policy frames that then compete with other problem frames for citizens’ cognitive resources. Vital democratic commitments to pluralism require public values to be distributed in competition with other, respected, frames.
Resumo:
Despite many interest in e-grocery, little has changed, over the years, in the offering that is often geared only towards low value staple products. Yet, from an e-supermarket perspective, the number of sourcing stores is increasing regularly providing an illusion of service improvement. This situation, we argue is leading e-grocery providers to forego profits as consumers need to look both at the competition online and offline to satisfy their overall regular grocery needs. Expansion of e-grocery operations could be better achieved, we argue, by serving diverse and premium priced products (e.g. organic, limited production, regional items; special occasions items and products related to health e.g. allergies, diabetes) and utilizing more efficiently modern logistic techniques. A framework is offered presenting a model including the delivery of premium products from various suppliers and providing an integrated service solution to e-grocery customers that complete traditional supermarket ranges, creating potential high value added products niches. In this context, the objective was to understand the consumer discrimination factors (ie: range of product, delivery timing, location, service quality) leading to intentions towards purchasing more items from e-grocery retailers. Data are derived from a survey of 356 respondents in Turkey’s three biggest metropolitan areas. The relationship between consumer attitudes and demographic characteristics are also analyzed. Factor and SEM analyses are used to discriminate within the sample (n=356, no of items=150). Results, future research and policy implications are discussed.