Adaptive resource allocation for multicast orthogonal frequency division multiple access systems with guaranteed BER and rate

In this paper, we propose a resource allocation scheme to minimize transmit power for multicast orthogonal frequency division multiple access systems. The proposed scheme allows users to have different symbol error rate (SER) across subcarriers and guarantees an average bit error rate and transmission rate for all users. We first provide an algorithm to determine the optimal bits and target SER on subcarriers. Because the worst-case complexity of the optimal algorithm is exponential, we further propose a suboptimal algorithm that separately assigns bit and adjusts SER with a lower complexity. Numerical results show that the proposed algorithm can effectively improve the performance of multicast orthogonal frequency division multiple access systems and that the performance of the suboptimal algorithm is close to that of the optimal one. Copyright © 2012 John Wiley & Sons, Ltd. This paper proposes optimal and suboptimal algorithms for minimizing transmitting power of multicast orthogonal frequency division multiple access systems with guaranteed average bit error rate and data rate requirement. The proposed scheme allows users to have different symbol error rate across subcarriers and guarantees an average bit error rate and transmission rate for all users. Copyright © 2012 John Wiley & Sons, Ltd.

On-line learning in radial basis functions networks

An analytic investigation of the average case learning and generalization properties of Radial Basis Function Networks (RBFs) is presented, utilising on-line gradient descent as the learning rule. The analytic method employed allows both the calculation of generalization error and the examination of the internal dynamics of the network. The generalization error and internal dynamics are then used to examine the role of the learning rate and the specialization of the hidden units, which gives insight into decreasing the time required for training. The realizable and over-realizable cases are studied in detail; the phase of learning in which the hidden units are unspecialized (symmetric phase) and the phase in which asymptotic convergence occurs are analyzed, and their typical properties found. Finally, simulations are performed which strongly confirm the analytic results.

Learning curves for Gaussian processes models: fluctuations and universality

Based on a statistical mechanics approach, we develop a method for approximately computing average case learning curves and their sample fluctuations for Gaussian process regression models. We give examples for the Wiener process and show that universal relations (that are independent of the input distribution) between error measures can be derived.

Measuring complexity through average symmetry

This work introduces a complexity measure which addresses some conflicting issues between existing ones by using a new principle - measuring the average amount of symmetry broken by an object. It attributes low (although different) complexity to either deterministic or random homogeneous densities and higher complexity to the intermediate cases. This new measure is easily computable, breaks the coarse graining paradigm and can be straightforwardly generalized, including to continuous cases and general networks. By applying this measure to a series of objects, it is shown that it can be consistently used for both small scale structures with exact symmetry breaking and large scale patterns, for which, differently from similar measures, it consistently discriminates between repetitive patterns, random configurations and self-similar structures

Measuring accounting disclosure in a period of complex changes : the case of Egypt

Significant changes in accounting disclosure are observed in periods of economic change such as those relating to emerging capital markets and programs of privatization. Measurement of the level of accounting disclosure should ideally be designed to capture the complexity of change in order to give insight and explanation to match the causes and consequences of change. This paper shows the added interpretive value in subdividing the disclosure checklist to reflect the requirements of national accounting regulations, the location of disclosure items in the annual report, and limitations on the availability of regulations in official translation to the local language. Defining targeted disclosure categories leads to significance testing of specific aspects of changes in accounting disclosure in the Egyptian capital market in the 1990s. Strong correlation of disclosure with the presence of majority government ownership of the company and the relative activity of share trading supports the applicability of political costs and capital need theories, respectively. The relation between International Accounting Standards (IASs) disclosure and the type of audit firm points to additional theoretical explanations, including relative familiarity with the legislation and compliance features identifiable with the emerging capital market. The approach described in this paper has the potential for enhancing understanding of the complexity of accounting change in other emerging capital markets and developing economies.

Transaction attributes and buyer-supplier relationships in AMT acquisition and implementation:the case of Malaysia

This paper explores how transaction attributes of technology affect differences in the relationship between technology buyers and suppliers. It also examines the impact on performance of different patterns of relationship between technology buyers and suppliers. Data obtained from 147 manufacturing firms in Malaysia are used to test several hypotheses, which were derived from a review of the literature on technology, transaction cost theory and buyer–supplier relationships (BSR). The research results indicate that the higher the level of technological complexity, specificity and uncertainty, the more firms are likely to engage in a closer relationship with technology suppliers. Even though the majority of firms reported improvements in their performance, results indicate that firms demonstrating a closer relationship with technology suppliers are more likely to achieve higher levels of performance than those that do not. It is also shown that with high levels of transaction attribute, implementation performance suffers more when firms have weak relationships with technology suppliers than with moderate and low levels of transaction attribute.

The propensity to hedge with futures contracts:the case of potato futures contracts

This paper studies why UK non-financial firms hedge with potato futures contracts. It is found that the financial characteristics of firms in the sample play an important role in influencing the propensity to hedge. For example, it is found that firms that hedge are on average larger than firms that do not hedge. Firms that hedge also have more volatile earnings. Furthermore, firms that do hedge appear to want to smooth earnings to reduce the costs of financial distress and avoid entering the highest tax threshold. © 2005 Taylor & Francis.

Managing risk in software development projects:a case study

Purpose - The main objective of the paper is to develop a risk management framework for software development projects from developers' perspective. Design/methodology/approach - This study uses a combined qualitative and quantitative technique with the active involvement of stakeholders in order to identify, analyze and respond to risks. The entire methodology has been explained using a case study on software development project in a public sector organization in Barbados. Findings - Analytical approach to managing risk in software development ensures effective delivery of projects to clients. Research limitations/implications - The proposed risk management framework has been applied to a single case. Practical implications - Software development projects are characterized by technical complexity, market and financial uncertainties and competent manpower availability. Therefore, successful project accomplishment depends on addressing those issues throughout the project phases. Effective risk management ensures the success of projects. Originality/value - There are several studies on managing risks in software development and information technology (IT) projects. Most of the studies identify and prioritize risks through empirical research in order to suggest mitigating measures. Although they are important to clients for future projects, these studies fail to provide any framework for risk management from software developers' perspective. Although a few studies introduced framework of risk management in software development, most of them are presented from clients' perspectives and very little effort has been made to integrate this with the software development cycle. As software developers absorb considerable amount of risks, an integrated framework for managing risks in software development from developers' perspective is needed. © Emerald Group Publishing Limited.

A performance assessment method for hospitals:the case of municipal hospitals in Angola

Over 60% of the recurrent budget of the Ministry of Health (MoH) in Angola is spent on the operations of the fixed health care facilities (health centres plus hospitals). However, to date, no study has been attempted to investigate how efficiently those resources are used to produce health services. Therefore the objectives of this study were to assess the technical efficiency of public municipal hospitals in Angola; assess changes in productivity over time with a view to analyzing changes in efficiency and technology; and demonstrate how the results can be used in the pursuit of the public health objective of promoting efficiency in the use of health resources. The analysis was based on a 3-year panel data from all the 28 public municipal hospitals in Angola. Data Envelopment Analysis (DEA), a non-parametric linear programming approach, was employed to assess the technical and scale efficiency and productivity change over time using Malmquist index.The results show that on average, productivity of municipal hospitals in Angola increased by 4.5% over the period 2000-2002; that growth was due to improvements in efficiency rather than innovation. © 2008 Springer Science+Business Media, LLC.

Strategy paradigms for the management of quality:dealing with complexity

Quality management is dominated by rational paradigms for the measurement and management of quality, but these paradigms start to “break down”, when faced with the inherent complexity of managing quality in intensely competitive changing environments. In this article, the various theoretical strategy paradigms employed to manage quality are reviewed and the advantages and limitations of these paradigms are highlighted. A major implication of this review is that when faced with complexity, an ideological stance to any single strategy paradigm for the management of quality is ineffective. A case study is used to demonstrate the need for an integrative multi-paradigm approach to the management of quality as complexity increases.

Exporting to Eastern Europe : principles and practice, including a case study of the market for fire fighting equipment

East-West trade has grown rapidly since the sixties, stimulating a parallel expansion in the literature on the subject. An extensive review of this literature shows how: (i) most of the issues involved have at their source the distinctions between East and West in political ideology and/or economic management, and (ii) there has been a tendency to keep theoretical and practical perspectives on the subject too separate. This thesis demonstrates the importance of understanding the fundamental principles implied in the first point, and represents an attempt to bridge the gap identified in the second. A detailed study of the market for fire fighting equipment in Eastern Europe is undertaken in collaboration with a medium-sized company, Angus Fire Armour Limited. Desk research methods are combined with visits to the market to assess the potential for the company's products, and recommendations for future strategy are made. The case demonstrates the scope and limitations of various research methods for the East European market, and a model for market research relevant to all companies is developed. Tne case study highlights three areas largely neglected in the literature: (i) the problems of internal company adaptation to East European conditions; (ii) the division of responsibility between foreign trade organisations; and (iii) bribery and corruption in East-West trade. Further research into the second topic - through a survey of 36 UK exporters - and the third - through analysis of publicised corruption cases - confirms the representativeness of the Angus experience, and reflects on the complexity of the Bast European import process, which does not always function as is commonly supposed. The very complexity of the problems confronting companies reaffirms the need to appreciate the principles underlying the subject, while the detailed analysis into questions of, originally, a marketing nature, reveals wider implications for East-West trade and East-West relations.

Feature analysis of spammers in social networks with active honeypots:a case study of Chinese microblogging networks

In this poster we presented our preliminary work on the study of spammer detection and analysis with 50 active honeypot profiles implemented on Weibo.com and QQ.com microblogging networks. We picked out spammers from legitimate users by manually checking every captured user's microblogs content. We built a spammer dataset for each social network community using these spammer accounts and a legitimate user dataset as well. We analyzed several features of the two user classes and made a comparison on these features, which were found to be useful to distinguish spammers from legitimate users. The followings are several initial observations from our analysis on the features of spammers captured on Weibo.com and QQ.com. ¦The following/follower ratio of spammers is usually higher than legitimate users. They tend to follow a large amount of users in order to gain popularity but always have relatively few followers. ¦There exists a big gap between the average numbers of microblogs posted per day from these two classes. On Weibo.com, spammers post quite a lot microblogs every day, which is much more than legitimate users do; while on QQ.com spammers post far less microblogs than legitimate users. This is mainly due to the different strategies taken by spammers on these two platforms. ¦More spammers choose a cautious spam posting pattern. They mix spam microblogs with ordinary ones so that they can avoid the anti-spam mechanisms taken by the service providers. ¦Aggressive spammers are more likely to be detected so they tend to have a shorter life while cautious spammers can live much longer and have a deeper influence on the network. The latter kind of spammers may become the trend of social network spammer. © 2012 IEEE.

Project risk management using multiple criteria decision-making technique and decision tree analysis:a case study of Indian oil refinery

This study proposes an integrated analytical framework for effective management of project risks using combined multiple criteria decision-making technique and decision tree analysis. First, a conceptual risk management model was developed through thorough literature review. The model was then applied through action research on a petroleum oil refinery construction project in the Central part of India in order to demonstrate its effectiveness. Oil refinery construction projects are risky because of technical complexity, resource unavailability, involvement of many stakeholders and strict environmental requirements. Although project risk management has been researched extensively, practical and easily adoptable framework is missing. In the proposed framework, risks are identified using cause and effect diagram, analysed using the analytic hierarchy process and responses are developed using the risk map. Additionally, decision tree analysis allows modelling various options for risk response development and optimises selection of risk mitigating strategy. The proposed risk management framework could be easily adopted and applied in any project and integrated with other project management knowledge areas.

An empirical investigation of audit pricing in the public sector:the case of Greek LGOs

This paper investigates the associations between audit pricing and multidimensional characteristics of local governments by using a sample of Greek municipalities. The Greek institutional setting is interesting because it is politically pluralistic. Moreover, independent auditors appointed through a bid process exclusively perform the audits. Our results suggest a considerable variation on audit fees which is mainly driven by politically related factors indicating the importance of relevant theoretical anticipations in audit pricing in the public sector. Agency costs appear strong enough to explain audit pricing. We also confirm prior findings on the significance of audit complexity and size. Results also suggest that audit fees are reduced when an internal team dedicated to accrual accounting is appointed. Therefore, our conclusions offer practical implications for policy setters and regulators in the public sector in relation to audit quality.

Measuring accounting disclosure in a period of complex changes:the case of Egypt

Significant changes in accounting disclosure are observed in periods of economic change such as those relating to emerging capital markets and programs of privatization. Measurement of the level of accounting disclosure should ideally be designed to capture the complexity of change in order to give insight and explanation to match the causes and consequences of change. This paper shows the added interpretive value in subdividing the disclosure checklist to reflect the requirements of national accounting regulations, the location of disclosure items in the annual report, and limitations on the availability of regulations in official translation to the local language. Defining targeted disclosure categories leads to significance testing of specific aspects of changes in accounting disclosure in the Egyptian capital market in the 1990s. Strong correlation of disclosure with the presence of majority government ownership of the company and the relative activity of share trading supports the applicability of political costs and capital need theories, respectively. The relation between International Accounting Standards (IASs) disclosure and the type of audit firm points to additional theoretical explanations, including relative familiarity with the legislation and compliance features identifiable with the emerging capital market. The approach described in this paper has the potential for enhancing understanding of the complexity of accounting change in other emerging capital markets and developing economies.