• Parameters of managerial effectiveness and development of third sector managers. An empirical study of HIV NGO managers in India

      Analoui, Farhad; Kazi, Shehnaz (University of BradfordPeace Studies and International Development, 2017)
      This unique and first-time research explores the parameters of effectiveness among HIV/AIDS and development NGO managers in India. The aim of this research has been investigate and explore how these managers perceive and view their own effectiveness at work. This research contextualises Analoui's Model (1999, 2002) of eight parameters of managerial effectiveness and three contextual factors, which explores and identifies the inter-relationship between the factors and causal influences which form the basis for their increased effectiveness. The methodology employed include qualitative semi-structured individual interviews with 16 NGOs managers and 2 focus-group interviews with 16 non-managerial staff. The results revealed a myriad of factors and influences concerning the NGO managers’ perception, managerial skills and competencies, organizations criteria for effectiveness, opportunities, demands and constraints involved, as well as the inter-organisational relationship and the dominant managerial philosophy of effectiveness. All the parameters of effectiveness and contextual factors of the Model (1999, 2002) apply and are suitable for this context, however, based on the main findings and in-depth discussions, the model has been adapted and modified in order to fit this unique and complex, highly diverse, holistic, multi-faceted and culturally specific context. The findings also indicate to numerous inter-linked factors both internally and externally of the NGOs and, include various training and development (T&D) needs for managers, with implications for the formation of adequate policies and implementation of relevant development programmes to improve and increase NGO managers effectiveness in India.
    • Partial least squares structural equation modelling with incomplete data. An investigation of the impact of imputation methods.

      Wallace, James; Mohd Jamil, J.B. (University of BradfordSchool of Management, 2013-11-28)
      Despite considerable advances in missing data imputation methods over the last three decades, the problem of missing data remains largely unsolved. Many techniques have emerged in the literature as candidate solutions. These techniques can be categorised into two classes: statistical methods of data imputation and computational intelligence methods of data imputation. Due to the longstanding use of statistical methods in handling missing data problems, it takes quite some time for computational intelligence methods to gain profound attention even though these methods have analogous accuracy, in comparison to other approaches. The merits of both these classes have been discussed at length in the literature, but only limited studies make significant comparison to these classes. This thesis contributes to knowledge by firstly, conducting a comprehensive comparison of standard statistical methods of data imputation, namely, mean substitution (MS), regression imputation (RI), expectation maximization (EM), tree imputation (TI) and multiple imputation (MI) on missing completely at random (MCAR) data sets. Secondly, this study also compares the efficacy of these methods with a computational intelligence method of data imputation, ii namely, a neural network (NN) on missing not at random (MNAR) data sets. The significance difference in performance of the methods is presented. Thirdly, a novel procedure for handling missing data is presented. A hybrid combination of each of these statistical methods with a NN, known here as the post-processing procedure, was adopted to approximate MNAR data sets. Simulation studies for each of these imputation approaches have been conducted to assess the impact of missing values on partial least squares structural equation modelling (PLS-SEM) based on the estimated accuracy of both structural and measurement parameters. The best method to deal with particular missing data mechanisms is highly recognized. Several significant insights were deduced from the simulation results. It was figured that for the problem of MCAR by using statistical methods of data imputation, MI performs better than the other methods for all percentages of missing data. Another unique contribution is found when comparing the results before and after the NN post-processing procedure. This improvement in accuracy may be resulted from the neural network¿s ability to derive meaning from the imputed data set found by the statistical methods. Based on these results, the NN post-processing procedure is capable to assist MS in producing significant improvement in accuracy of the approximated values. This is a promising result, as MS is the weakest method in this study. This evidence is also informative as MS is often used as the default method available to users of PLS-SEM software.
    • Partial ordering of weak mutually unbiased bases in finite quantum systems

      Vourdas, Apostolos; Lei, Ci; Oladejo, Semiu Oladipupo (University of BradfordFaculty of Engineering and Informatics School of Electrical Engineering and Computer Science, 2015)
      There has being an enormous work on finite quantum systems with variables in Zd, especially on mutually unbiased bases. The reason for this is due to its wide areas of application. We focus on partial ordering of weak mutually un-biased bases. In it, we studied a partial ordered relation which exists between a subsystem ^(q) and a larger system ^(d) and also, between a subgeometry Gq and larger geometry Gd. Furthermore, we show an isomorphism between: (i) the set {Gd} of subgeometries of a finite geometry Gd and subsets of the set {D(d)} of divisors of d. (ii) the set {hd} of subspaces of a finite Hilbert space Hd and subsets of the set {D(d)} of divisors of d. (iii) the set {Y(d)} of subsystems of a finite quantum system ^(d) and subsets of the set {D(d)} of divisors of d. We conclude this work by showing a duality between lines in finite geometry Gd and weak mutually unbiased bases in finite dimensional Hilbert space Hd.
    • Pathological role of double-stranded DNA antibodies in multiple sclerosis.

      Nigel, Lindsey; Rowton, Sharon (University of BradfordDivision of Biomedical Sciences, 2010-05-10)
      Multiple sclerosis is a complex disease and one for which the aetiology remains largely unanswered. Anti-dsDNA antibodies have been found intrathecally and bordering lesions in multiple sclerosis patients and in view of their known pathogenity in lupus nephritis the aim of this project was to further investigate their role in multiple sclerosis. Using the acute experimental allergic encephalomyelitis (EAE) model in the Lewis rat, the inflammatory phase of disease was profiled using immunohistological and ELISA methods and was related to clinical sign severity. The parameters of interest were central nervous system deposits of IgM, IgG, B cells and C3 and anti-DNA antibodies in sera, cerebrospinal fluid and in situ. In situ evaluation of anti-dsDNA antibodies was also performed in tissue taken from Biozzi (AH) mice (relapsing/remitting EAE model) and from a multiple sclerosis patient. Inflammatory deposits specifically at sites of perivascular cuffing were found to increase with increasing clinical sign severity. At the time clinical signs had plateaued in the Lewis rat, intrathecal anti-dsDNA antibodies were at their highest level and anti-ssDNA antibodies at their lowest. The latter possibly due to their involvement in the `clearing-up¿ process following tissue damage. Using novel DNA probes fluorescence suggestive of the presence of anti-dsDNA iii antibodies was seen in both animal and human tissue. Within human tissue the antibodies appeared to accumulate around active lesions and within vessels, raising the question of these antibodies having differing location dependent functions. EAE models have the potential to investigate these findings further and to evaluate new therapies.
    • Patterns of influence in management decision making. Analysis of decision processes in four types of Brazilian organizations.

      Butler, Richard J.; Rodrigues, Indiana P. F. (University of BradfordPostgraduate School of Studies in Management and Administration., 2009-11-12)
      The distribution of influence in organizational decisions is analysed in relation to institutional frameworks and characteristics inherent to decision topics. Distribution of influence is defined as the concentration of participants in decision process and their specific capability to influence decision outcomes. This definition encompasses two dimensions which are: participation in the decision processes and effective influence upon the decision outcomes. Institutional frameworks are distinguished according to the loci of their genesis and existence, that are: the focal organization the task-environment and the larger social context. Six characteristics inherent to decision topics are identified as related to variables defined as properties of decision. The analysis is carried out at two distinct stages. At the first stage, it examines the relationships of the institutional frameworks - existing at the organization and the task environment level - and of the properties of decisions with the distribution of influence in decision processes. At the second stage, the patterns of influence that emerged out of the first stage of analysis are analysed in terms of cultural traits prevailing in Brazilian society. The results point to variation in the distribution of influence in decision processes associated with factors of the taskenvironment, of the context of the organizations and characteristics inherent to decision topics. But they do not provide a wholly satisfactory explanation of such variation. A more general pattern of influence in management decisionmahing, characterized by low level of participation and high centre of influence in decision processes, appears as the dominant profile of the distribution of influence in Brazilian organizations. Interpreted in the light of the Brazilian social context, this pattern of influence in management decision making shows pervasive cultural traits, identified in the macro social system. Comparing the patterns of influence in management decisionmaking in Brazil and Britain, similarities and differences come to light. The comparative analysis corroborates the argument that patterns of influence in management decision making are bound to contingent as much as to institutional factors.
    • PAX: The history of a Catholic peace society in Britain 1936-1971.

      Flessati, Valerie (University of BradfordDepartment of Peace Studies, 2009-10-30)
      In 1936 the founders of PAX aimed at 'resistance to modern warfare on grounds of traditional morality'. Believing that 'just war' criteria could no longer be met, they called themselves pacifists. Although most members were Roman Catholic Pax did not claim to be a 'Catholic society' because the RC Church at that time took an opposing view, particularly of conscientious objection. Church authorities attempted to censor Pax literature and instructed clergy to resign from the society. Pax supported conscientious objectors during the Second World War. When membership declined afterwards it continued to publish the Pax Bulletin and to provide a forum where Catholics could debate theological and practical questions of war and peace. By the 1960s Pax had gained some distinguished sponsors and a branch in the United States - support which enabled it to influence debate at the Second Vatican Council in 1965. The Council endorsed the right to conscientious objection. In 1971 Pax merged with Pax Christi, the international Catholic peace organisation which began in France in 1944/45. This is the first detailed historical study of the Roman Catholic element in the British peace movement. The story of Pax demonstrates the part that even a small pressure group can play in changing public opinion through patient work. Eventually, despite apathy and opposition, Pax helped bring the RC Church to a recognition of the right to conscientious objection and played a crucial role in the development of a more widespread peace movement within the Church
    • Peace and conflict resolution activities in support of strengthening civil society's democratic capacity in South Korea. Case studies on three civil society organisations working on peace and conflict resolution in South Korea.

      Gallagher, Tom G.P.; Chung, Da Woon (University of BradfordDepartment of Peace Studies, 2012-11-02)
      In the last fifteen years, conflict resolution, a collaborative, problem-solving approach to social conflicts, was introduced to new democracies in an attempt to develop civil society¿s capacity for conflict management (Mayer, 2000). Conflict resolution provides people with an opportunity to advocate effectively for their own interests in a non-violent, constructive manner through systematic educational efforts, skills trainings, dialogue initiatives, and mediation practices (Mayer, 2000). It empowers people to address, manage, and transform difficulties and antagonism into a source of positive social change and, thus, change people¿s negative psychological responses to conflicts (Bush & Folger, 1994). In this view, conflict resolution in new democracies¿ civil society provides citizens as well NGO practitioners with the skills and opportunities to practice how to express and resolve differences in a safe and constructive environment (Shonholtz, 1997). In an effort to provide additional information about civil society¿s conflict resolution practices and their affect in new democracies, this dissertation examines the existing efforts of South Korean civil society organisations to promote conflict resolution methodologies. Specifically, three organisations are examined to understand better South Korean civil society¿s response to PCR issues. Furthermore, by closely examining these three civil society organisations, this dissertation aims to explore what affect increased awareness and engagement in conflict resolution methodologies have on the democratic quality of civil society.
    • Peat exploitation on Thorne Moors. A case-study from the Yorkshire-Lincolnshire border 1626-1963, with integrated notes on Hatfield Moors

      Seaward, Mark R.D.; Limbert, Martin (University of BradfordDivision of Archaeological, Geographical and Environmental Sciences, 2012-07-02)
      In its industrial heyday, Thorne Moors was the most extensive commercial peat operation in Britain. It became closely tied to nearby Hatfield Moors, and at both the methods of exploitation were essentially the same. Although much of Thorne Moors is situated in Yorkshire, the eastern extent lies in Lincolnshire. Recognizable differences in scale and methodology existed between the Yorkshire and Lincolnshire parts. After regional drainage in the 1620-30s, there was increased trade in the peat of Thorne Moors along the River Don. A succession of uses included unrefined and refined fuel, products from carbonization and distillation, and moss litter for working horses. From the mid-19th century, companies were formed to exploit the new uses, especially moss litter, and export became increasingly focused on railways. In 1896, the British Moss Litter Co. Ltd was set up (restructured 1899) to assume the Thorne/Hatfield interests of several smaller companies, including the Anglo-Dutch Griendtsveen Moss Litter Co. Ltd. The British Moss Litter Co. was acquired by Fisons Ltd in 1963. Following a contextual history, descriptions are given of both muscle-powered peat winning and transportation methodologies. These comprise exploitation in the 17th and 18th centuries, an examination of the 19th century writings of William Casson, and written allusions spanning 1863-1963. Information is imparted on the Griendtsveen Moss Litter Co. In addition to creating a 'Dutch' peat canal system, this company introduced an immigrant Dutch workforce, proficient in their native methods and intended inter alia to retrain local workers looking for employment with Griendtsveen. Dutch methodology persisted alongside the local methods for c.60 years. Accounts are also presented of the evolutionary limit of indigenous peat winning, and the use of narrow gauge railways. Finally the transition to mechanisation of peat cutting and narrow gauge haulage is outlined.
    • The perceived timing of events across different sensory modalities. A psychophysical investigation of multisensory time perception in humans.

      Whitaker, David J.; Heron, James; Hanson, James Vincent Michael (University of BradfordSchool of Optometry and Vision Science, 2010-05-07)
      The experiments reported within this thesis use psychophysical techniques to examine the factors which determine perceived multisensory timing in humans. Chapters 1 and 2 describe anatomical and psychophysical features of temporal processing, respectively, whilst Chapter 3 introduces the reader to psychophysical methods. Chapter 4 examines the relationship between two measures of sensory latency, reaction time (RT) and crossmodal temporal order judgment (TOJ). Despite task and attentional manipulations the two measures do not correlate, suggesting that they measure some fundamentally different aspect(s) of temporal perception. Chapter 5 examines the effects of adaptation to asynchronous stimulus pairs on perceived audiovisual (AV), audiotactile (AT) and visuotactile (VT) temporal order. Significant temporal shifts are recorded in all three conditions. Evidence is also presented showing that crossmodal TOJs are intransitive. Chapter 6 shows that concurrent adaptation to two sets of asynchronous AV stimulus pairs causes perceived AV temporal order to recalibrate at two locations simultaneously, and that AV asynchrony adaptation effects are significantly affected by observers¿ attention during adaptation. Finally, Chapter 7 shows that when observers are accustomed to a physical delay between motor actions and sensory events, an event presented at a reduced delay appears to precede the causative motor action. The data are well-described by a simple model based on a strong prior assumption of physical synchrony between motor actions and their sensory consequences.
    • Perceptions of culturally competent practice behaviour by newly qualified nurses

      Archibong, Uduak E.; Walton, Sean; Wray, Jane (University of BradfordFaculty of Health Sciences, 2017)
      Background: The nursing workforce needs to be adequately prepared to deliver care to an increasingly diverse patient population in the United Kingdom (UK). The Nursing and Midwifery Council (NMC) expects newly qualified nurses (NQNs) to deliver culturally sensitive and respectful care. Aim: The study aimed to explore NQNs’ perceptions of culturally competent practice during the first 9 months post qualification. Methods: A qualitative longitudinal study was conducted with a volunteer sample of 14 NQNs recruited from 3 Higher Education Institutions in the north of England. Data was collected using directed reflections (at 2-3 and 5-6 months) and semi-structured interviews (at 8-9 months) and analysed using a phenomenological approach informed by symbolic interactionism. Results: Perceptions of culturally competent nursing practice were associated with core concepts such as individualised patient care, compassionate and respectful care, respecting individual differences, professionalism and patient trust. Specific behaviours were associated with verbal and non-verbal communication, care planning and diversity-specific adjustments. Discussion: Self-perceived competence and confidence in caring for, and interacting with, patients from diverse backgrounds developed and changed throughout the transition period with experience and interaction opportunities. An ability to reflect upon and learn from novel experiences, plus an enabling ward culture and environment which responded positively to nurses seeking advice and support was important. Conclusion: Educational preparation may have enabled NQNs’ opportunities to develop some but not necessarily all of the skills and behaviours required to demonstrate culturally competent practice. During transition, supported development and professional socialisation can assist in enhancing competence and confidence.
    • Performance Analysis and Enhancement of QoS Framework for Fixed WiMAX Networks. Design, analysis and evaluation of 802.16 Point-to-Multipoint (PMP) Quality of Service Framework based on uplink scheduler and call admission control analysis.

      Awan, Irfan U.; Laias, Elmabruk M. (University of BradfordSchool of Informatics, Department of Computing., 2010-05-28)
      Given the current developments and advances in the scientific and technological aspects of human knowledge and introducing new approaches in various fields of telecommunication technologies and industries, there has been an increasing growth in its players¿ plans and a positive change in their outlooks in order to achieve the target of "anywhere and anytime access". Recent developments of WiMAX (Worldwide interoperability for Microwave Access) networks, as a sign of increasing needs and demands for new telecommunication services and capabilities, have led to revolutions in global telecommunication which should be perceived properly in terms of the commercial and technical aspects in order to enjoy the new opportunities. Most experts believe that WiMAX technology is a preliminary step to develop Fourth Generation networks known as 4G technologies. It has not only succeeded in the utilization of several of the latest telecommunication techniques in the form of unique practical standards, but also paved the way for the quantitative and qualitative developments of high-speed broadband access. IEEE 802.16 Standard introduces several advantages, and one of them is the support for Quality of Services (QoS) at the Media Access Control (MAC) level. For these purposes, the standard defines several scheduling classes at MAC layer to treat service flow in a different way, depending on QoS requirements. In this thesis, we have proposed a new QoS framework for Point-to-Multi Point (PMP) 802.16 systems operating in Time Division Duplexing (TDD) mode over a WirelessMAN-OFDM physical layer. The proposed framework consists of a Call Admission Control (CAC) module and a scheduling scheme for the uplink traffic as well as a simple frame allocation scheme. The proposed CAC module interacts with the uplink scheduler status and it makes its decision based on the scheduler queue status; on the other hand, the proposed scheduling scheme for the uplink traffic aims to support realtime flows and adapts the frame-by-frame allocations to the current needs of the connections, with respect to the grants boundaries fixed by the CAC module. Extensive OPNET simulation demonstrates the effectiveness of the proposed architecture.
    • Performance analysis and improvement of InfiniBand networks. Modelling and effective Quality-of-Service mechanisms for interconnection networks in cluster computing systems.

      Min, Geyong; Awan, Irfan U.; Yan, Shihang (University of BradfordDepartment of Computing, School of Computing, Informatics and Media, 2013-11-22)
      The InfiniBand Architecture (IBA) network has been proposed as a new industrial standard with high-bandwidth and low-latency suitable for constructing high-performance interconnected cluster computing systems. This architecture replaces the traditional bus-based interconnection with a switch-based network for the server Input-Output (I/O) and inter-processor communications. The efficient Quality-of-Service (QoS) mechanism is fundamental to ensure the import at QoS metrics, such as maximum throughput and minimum latency, leaving aside other aspects like guarantee to reduce the delay, blocking probability, and mean queue length, etc. Performance modelling and analysis has been and continues to be of great theoretical and practical importance in the design and development of communication networks. This thesis aims to investigate efficient and cost-effective QoS mechanisms for performance analysis and improvement of InfiniBand networks in cluster-based computing systems. Firstly, a rate-based source-response link-by-link admission and congestion control function with improved Explicit Congestion Notification (ECN) packet marking scheme is developed. This function adopts the rate control to reduce congestion of multiple-class traffic. Secondly, a credit-based flow control scheme is presented to reduce the mean queue length, throughput and response time of the system. In order to evaluate the performance of this scheme, a new queueing network model is developed. Theoretical analysis and simulation experiments show that these two schemes are quite effective and suitable for InfiniBand networks. Finally, to obtain a thorough and deep understanding of the performance attributes of InfiniBand Architecture network, two efficient threshold function flow control mechanisms are proposed to enhance the QoS of InfiniBand networks; one is Entry Threshold that sets the threshold for each entry in the arbitration table, and other is Arrival Job Threshold that sets the threshold based on the number of jobs in each Virtual Lane. Furthermore, the principle of Maximum Entropy is adopted to analyse these two new mechanisms with the Generalized Exponential (GE)-Type distribution for modelling the inter-arrival times and service times of the input traffic. Extensive simulation experiments are conducted to validate the accuracy of the analytical models.
    • Performance Analysis and Modelling of Spectrum Handoff Schemes in Cognitive Radio Networks. Modelling and Analysis of Spectrum Handoff Decision Schemes in Cognitive Radio Networks using the Queuing Theory and Simulation for Licensed and Unlicensed Spectrum Bands.

      Awan, Irfan U.; Cullen, Andrea J.; Zahed, Salah M.B. (University of BradfordSchool of Electrical Engineering and Computer Science, 2015-07-15)
      Recently, wireless access has become an essential part of modern society. Consequently, the demand for new wireless applications and services, as well as the number of wireless users, are gradually increasing. Given that this amount of expansion is eventually controlled by the available radio frequency spectrum, government regulatory agencies have recently adopted a strict approach to the licensing of limited amounts of spectrum to different entities (e.g., public safety, military, service providers, unlicensed devices, and TV). All of them possess exclusive transmissions to their assigned frequency channels. A new study on spectrum efficiency revealed big geographic and temporal variations in spectrum utilisation, ranging from 15-85% in the bands below 3GHz. These variations were less at frequencies above this figure. Recently, the Cognitive Radio (CR) has risen as an encouraging piece of technology to improve spectrum efficiency and to solve the problem of spectrum scarcity. This is because CR allows the secondary (unlicensed) users to occupy unused licensed spectrum bands temporarily, given that the interference of the primary (licensed) users is prohibited or minimised. In this thesis, various spectrum handoff management schemes have been proposed in order to improve the performance evaluation for CR networks. The proposed spectrum handoff schemes use the Opportunistic Spectrum Access (OSA) concept to utilise available spectrum bands. The handoff Secondary Users (SUs) have a higher priority to occupy available spectrum channels in the licensed and unlicensed spectrum bands without interfering with the legacy spectrum owner, i.e. primary users (PUs). However, existing spectrum handoff management schemes in CR networks do not provide high transmission opportunities for handoff secondary users to utilise the available radio spectrum resources. The first part of this thesis addresses the issue of spectrum handoff management in a licensed spectrum band environment. In this case, both reactive and proactive spectrum handoff schemes are proposed. Queuing theory or/and simulation experiments have been used to evaluate the performance of the proposed schemes and compare them with other existing schemes. Handoff delay has mainly been used to investigate the impact of successive handoff operations on the performance of the proposed CR networks. Implemented models have shown an improvement in the adopted performance measures. According to the achieved results, the improvement of the proposed, prioritised handoff schemes in some cases is approximately 75% when compared with existing schemes. On the other hand, the second part of this research proposed a prioritised spectrum handoff scheme in a heterogeneous spectrum environment, which is composed of a pool of licensed and unlicensed spectrum channels. In general, the availability of substantial numbers of the licensed spectrum channels is the key benefit of using this type of radio spectrum channel. Whereas, accessing with equal rights for all types of users is the main advantage of using unlicensed spectrum channels. In this respect, no transmission interruptions occur once a user obtains a channel. In addition, the proposed schemes use only the unlicensed spectrum channels as their backup channels. This enables the user to resume interrupted transmission in the case of the spectrum handoff operation (mainly; due to the appearance of the primary users), and thus facilitates a SUs communication. The proposed principle is investigated using a retrial queuing theory as well as extensive simulation experiments, and is compared with another non-prioritised scheme which do not give any preference to handoff SUs over new SUs. The results indicate that the proposed model has improved on current average handoff delay. This thesis contributes to knowledge by further enhancing the efficient utilisation of available radio spectrum resources and therefore subsequently provides an improvement in the spectrum capacity for wireless cognitive radio networks.
    • Performance Analysis of Cluster Based Communication Protocols for Energy Efficient Wireless Sensor Networks. Design, Analysis and Performance Evaluation of Communication Protocols under Various Topologies to Enhance the Lifetime of Wireless Sensor Networks.

      Awan, Irfan U.; Bajaber, Fuad G. (University of BradfordSchool of Computing, Informatics and Media, 2011-05-11)
      Sensor nodes are deployed over sensing fields for the purpose of monitoring certain phenomena of interest. The sensor nodes perform specific measurements, process the sensed data, and send the data to a base station over a wireless channel. The base station collects data from the sensor nodes, analyses this data, and reports it to the users. Wireless sensor networks are different from traditional networks, because of the following constraints. Typically, a large number of sensor nodes need to be randomly deployed and, in most cases, they are deployed in unreachable environments; however, the sensor nodes may fail, and they are subject to power constraints. Energy is one of the most important design constraints of wireless sensor networks. Energy consumption, in a sensor node, occurs due to many factors, such as: sensing the environment, transmitting and receiving data, processing data, and communication overheads. Since the sensor nodes behave as router nodes for data propagation, of the other sensor nodes to the base station, network connectivity decreases gradually. This may result in disconnected sub networks of sensor nodes. In order to prolong the network¿s lifetime, energy efficient protocols should be designed for the characteristics of the wireless sensor network. Sensor nodes in different regions of the sensing field can collaborate to aggregate the data that they gathered. Data aggregation is defined as the process of aggregating the data from sensor nodes to reduce redundant transmissions. It reduces a large amount of the data traffic on the network, it requires less energy, and it avoids information overheads by not sending all of the unprocessed data throughout the sensor network. Grouping sensor nodes into clusters is useful because it reduces the energy consumption. The clustering technique can be used to perform data aggregation. The clustering procedure involves the selection of cluster heads in each of the cluster, in order to coordinate the member nodes. The cluster head is responsible for: gathering the sensed data from its cluster¿s nodes, aggregating the data, and then sending the aggregated data to the base station. An adaptive clustering protocol was introduced to select the heads in the wireless sensor network. The proposed clustering protocol will dynamically change the cluster heads to obtain the best possible performance, based on the remaining energy level of sensor nodes and the average energy of clusters. The OMNET simulator will be used to present the design and implementation of the adaptive clustering protocol and then to evaluate it. This research has conducted extensive simulation experiments, in order to fully study and analyse the proposed energy efficient clustering protocol. It is necessary for all of the sensor nodes to remain alive for as long as possible, since network quality decreases as soon as a set of sensor nodes die. The goal of the energy efficient clustering protocol is to increase the lifetime and stability period of the sensor network. This research also introduces a new bidirectional data gathering protocol. This protocol aims to form a bidirectional ring structure among the sensor nodes, within the cluster, in order to reduce the overall energy consumption and enhance the network¿s lifetime. A bidirectional data gathering protocol uses a source node to transmit data to the base station, via one or more multiple intermediate cluster heads. It sends data through energy efficient paths to ensure the total energy, needed to route the data, is kept to a minimum. Performance results reveal that the proposed protocol is better in terms of: its network lifetime, energy dissipation, and communication overheads.
    • Performance Analysis of New Algorithms for Routing in Mobile Ad-hoc Networks. The development and performance evaluation of some new routing algorithms for mobile ad-hoc networks based on the concepts of angle direction and node density.

      Woodward, Mike E.; Elazhari, Mohamed S. (University of BradfordSchool of Computing, Informatics and Media, 2011-06-22)
      Mobile Ad hoc Networks (MANETs) are of great interest to researchers and have become very popular in the last few years. One of the great challenges is to provide a routing protocol that is capable of offering the shortest and most reliable path in a MANET in which users are moving continuously and have no base station to be used as a reference for their position. This thesis proposes some new routing protocols based on the angles (directions) of the adjacent mobile nodes and also the node density. In choosing the next node in forming a route, the neighbour node with the closest heading angle to that of the node of interest is selected, so the connection between the source and the destination consists of a series of nodes that are moving in approximately the same direction. The rationale behind this concept is to maintain the connection between the nodes as long as possible. This is in contrast to the well known hop count method, which does not consider the connection lifetime. We propose three enhancements and modifications of the Ad-hoc on demand distance vector (AODV) protocol that can find a suitable path between source and destination using combinations and prioritization of angle direction and hop count. Firstly, we consider that if there are multiple routing paths available, the path with the minimum hop count is selected and when the hop counts are the same the path with the best angle direction is selected. Secondly, if multiple routing paths are available the paths with the best angle direction are chosen but if the angles are the same (fall within the same specified segment), the path with minimum hop count is chosen. Thirdly, if there is more than one path available, we calculate the average of all the heading angles in every path and find the best one (lowest average) from the source to the destination. In MANETs, flooding is a popular message broadcasting technique so we also propose a new scheme for MANETS where the value of the rebroadcast packets for every host node is dynamically adjusted according to the number of its neighbouring nodes. A fixed probabilistic scheme algorithm that can dynamically adjust the rebroadcasting probability at a given node according to its ID is also proposed; Fixed probabilistic schemes are one of the solutions to reduce rebroadcasts and so alleviate the broadcast storm problem. Performance evaluation of the proposed schemes is conducted using the Global Mobile Information System (GloMoSim) network simulator and varying a number of important MANET parameters, including node speed, node density, number of nodes and number of packets, all using a Random Waypoint (RWP) mobility model. Finally, we measure and compare the performance of all the proposed approaches by evaluating them against the standard AODV routing protocol. The simulation results reveal that the proposed approaches give relatively comparable overall performance but which is better than AODV for almost all performance measures and scenarios examined.
    • Performance and Security Trade-offs in High-Speed Networks. An investigation into the performance and security modelling and evaluation of high-speed networks based on the quantitative analysis and experimentation of queueing networks and generalised stochastic Petri nets.

      Kouvatsos, Demetres D.; Miskeen, Guzlan M.A. (University of BradfordDepartment of Computing, 2014-05-30)
      Most used security mechanisms in high-speed networks have been adopted without adequate quantification of their impact on performance degradation. Appropriate quantitative network models may be employed for the evaluation and prediction of ¿optimal¿ performance vs. security trade-offs. Several quantitative models introduced in the literature are based on queueing networks (QNs) and generalised stochastic Petri nets (GSPNs). However, these models do not take into consideration Performance Engineering Principles (PEPs) and the adverse impact of traffic burstiness and security protocols on performance. The contributions of this thesis are based on the development of an effective quantitative methodology for the analysis of arbitrary QN models and GSPNs through discrete-event simulation (DES) and extended applications into performance vs. security trade-offs involving infrastructure and infrastructure-less high-speed networks under bursty traffic conditions. Specifically, investigations are carried out focusing, for illustration purposes, on high-speed network routers subject to Access Control List (ACL) and also Robotic Ad Hoc Networks (RANETs) with Wired Equivalent Privacy (WEP) and Selective Security (SS) protocols, respectively. The Generalised Exponential (GE) distribution is used to model inter-arrival and service times at each node in order to capture the traffic burstiness of the network and predict pessimistic ¿upper bounds¿ of network performance. In the context of a router with ACL mechanism representing an infrastructure network node, performance degradation is caused due to high-speed incoming traffic in conjunction with ACL security computations making the router a bottleneck in the network. To quantify and predict the trade-off of this degradation, the proposed quantitative methodology employs a suitable QN model consisting of two queues connected in a tandem configuration. These queues have single or quad-core CPUs with multiple-classes and correspond to a security processing node and a transmission forwarding node. First-Come-First-Served (FCFS) and Head-of-the-Line (HoL) are the adopted service disciplines together with Complete Buffer Sharing (CBS) and Partial Buffer Sharing (PBS) buffer management schemes. The mean response time and packet loss probability at each queue are employed as typical performance metrics. Numerical experiments are carried out, based on DES, in order to establish a balanced trade-off between security and performance towards the design and development of efficient router architectures under bursty traffic conditions. The proposed methodology is also applied into the evaluation of performance vs. security trade-offs of robotic ad hoc networks (RANETs) with mobility subject to Wired Equivalent Privacy (WEP) and Selective Security (SS) protocols. WEP protocol is engaged to provide confidentiality and integrity to exchanged data amongst robotic nodes of a RANET and thus, to prevent data capturing by unauthorised users. WEP security mechanisms in RANETs, as infrastructure-less networks, are performed at each individual robotic node subject to traffic burstiness as well as nodal mobility. In this context, the proposed quantitative methodology is extended to incorporate an open QN model of a RANET with Gated queues (G-Queues), arbitrary topology and multiple classes of data packets with FCFS and HoL disciplines under bursty arrival traffic flows characterised by an Interrupted Compound Poisson Process (ICPP). SS is included in the Gated-QN (G-QN) model in order to establish an ¿optimal¿ performance vs. security trade-off. For this purpose, PEPs, such as the provision of multiple classes with HoL priorities and the availability of dual CPUs, are complemented by the inclusion of robot¿s mobility, enabling realistic decisions in mitigating the performance of mobile robotic nodes in the presence of security. The mean marginal end-to-end delay was adopted as the performance metric that gives indication on the security improvement. The proposed quantitative methodology is further enhanced by formulating an advanced hybrid framework for capturing ¿optimal¿ performance vs. security trade-offs for each node of a RANET by taking more explicitly into consideration security control and battery life. Specifically, each robotic node is represented by a hybrid Gated GSPN (G-GSPN) and a QN model. In this context, the G-GSPN incorporates bursty multiple class traffic flows, nodal mobility, security processing and control whilst the QN model has, generally, an arbitrary configuration with finite capacity channel queues reflecting ¿intra¿-robot (component-to-component) communication and ¿inter¿-robot transmissions. Two theoretical case studies from the literature are adapted to illustrate the utility of the QN towards modelling ¿intra¿ and ¿inter¿ robot communications. Extensions of the combined performance and security metrics (CPSMs) proposed in the literature are suggested to facilitate investigating and optimising RANET¿s performance vs. security trade-offs. This framework has a promising potential modelling more meaningfully and explicitly the behaviour of security processing and control mechanisms as well as capturing the robot¿s heterogeneity (in terms of the robot architecture and application/task context) in the near future (c.f. [1]. Moreover, this framework should enable testing robot¿s configurations during design and development stages of RANETs as well as modifying and tuning existing configurations of RANETs towards enhanced ¿optimal¿ performance and security trade-offs.
    • Performance Evaluation and Prediction of 2-D Markovian and Bursty Multi-Traffic Queues. Analytical Solution for 2-D Markovian and Bursty Multi-Traffic Non Priority, Priority and Hand Off Calling Schemes.

      Kouvatsos, Demetres D.; Karamat, Taimur (University of BradfordSchool of Informatics, Computing and Media, 2011-10-28)
      Queueing theory is the mathematical study of queues or waiting lines, which are formed whenever demand for service exceeds the capacity to provide service. A queueing system is composed of customers, packets or calls that need some kind of service. These entities arrive at queueing system, join a queue if service is not immediately available and leave system after receiving service. There are also cases when customers, packets or calls leave system without joining queue or drop out without receiving service even after waiting for some time. Queueing network models with finite capacity have facilitated the analysis of discrete flow systems, such as computer systems, transportation networks, manufacturing systems and telecommunication networks, by providing powerful and realistic tools for performance evaluation and prediction. In wireless cellular systems mobility is the most important feature and continuous service is achieved by supporting handoff from one cell to another. Hand off is the process of changing channel associated with the current connection while a call is in progress. A handoff is required when a mobile terminal moves from one cell to another or the signal quality deteriorates in current cell. Since neighbouring cells use disjoint subset of frequency bands therefore negotiation must take place between mobile terminal, the current base station and next potential base station. A poorly designed handoff scheme significantly decreases quality of service (QOS). Different schemes have been devised and in these schemes handoff calls are prioritize. Also most of the performance evaluation techniques consider the case where the arrival process is poisson and service is exponential i.e. there is single arrival and single departure. Whereas in practice there is burstiness in cellular traffic i.e. there can be bulk arrivals and bulk departures. Other issue is that, assumptions made by stochastic process models are not satisfied. Most of the effort is concentrated on providing different interpretations of M/M queues rather than attempting to provide a new methodology. In this thesis performance evaluation of multi traffic cellular models i.e. non priority, priority and hand off calling scheme for bursty traffic are devised. Moreover extensions are carried out towards the analysis of a multi-traffic M/M queueing system and state probabilities are calculated analytically.
    • Performance Management in a German Hidden Champion - an Action Research investigation

      Bright, David; Zueva-Owens, Anna; Schlüter, Thomas
      Purpose - This thesis addresses the lack of research on Performance Management (PM) in Hidden Champions (HCs) due to development and implementation of a HC tailored PM system (PMS) in Action Research Design (AR). A HC tailored strategy map and PMS framework were elaborated to improve the financial and non-financial performance of the HC. Design/methodology/approach - A longitudinal case study with two AR cycles were performed to develop the HC tailored strategy map and framework for the PMS including their implementation using mixed methods data collection. A validated HC tailored strategy map and framework for the PMS implementation are presented. Findings - Findings show significantly increased financial and non-financial performance of the HC. The revenue of the case company increased by 11.6%, the return on revenue increased 3% up to 17%, customer satisfaction grew, throughput times shortened and leadership competencies improved. Findings further show that AR is an effective procedure for HC tailored PMS design and implementation. Research limitations and practical implications - The findings are based on one case study and needs to be tested in other HCs. Findings should be of interest to scholars in the field of PM, as well as practitioners improving financial and non-financial performance. Originality/value -This thesis contributes to knowledge of PM in HCs, and AR, as it provides a validated HC strategy map and framework for HC tailored PMS implementation in a HC. It provides an approach for practitioners to improve financial and non-financial performance in HCs.
    • Performance measurement in African semi-autonomous revenue authorities : The case of Kenya, South Africa and Tanzania. How can performance measures in African semi-autonomous revenue authorities (ARAs) be strategic, efficient and effective?

      van Duivenboden, Hein; Kariuki, Elizabeth Judy Nyawira. (University of BradfordSchool of Management, 2013-12-06)
      Semi-autonomous revenue authorities (ARAs) have been established all over the world as a distinctive institutional model outside the traditional public service aimed at enhancing tax administration, and thereby raising tax revenues. In order to boost the robustness of their operations, substantial expenditures have gone towards modernising ARAs. Expenditures have been guided by medium-term corporate-wide plans, and the results monitored, assessed and reported using performance measures. Performance measurement has proved challenging for ARAs to implement and sustain in practice. Some of the challenges evolve around weak capacity, implementation costs, issues to do with quantification, competing demands from a wide range of constituents, the inappropriate selection of measures and a bias towards performance measures that focus on finances. As a means for enhancing performance measurement, there are practices, lessons and theoretical perspectives that can be discerned from the broadspectrum of literature on performance measurement in the public sector and ARAs from around the world. This thesis explores how performance measurement in African ARAs can be more strategic, efficient and effective by ascertaining which key factors shape its adoption. The research focuses on the in depth study of three ARAs in Sub Saharan Africa, involving a combination of structured interviews with internal and external stakeholders, the administration of a survey instrument and review of ARA documents. The final chapters of the thesis deploy fuzzy set logic techniques to identify and test the significance of various causal conditions in the adoption of performance measurement in ARAs, as a plausible answer to the research question.
    • Performance modeling of congestion control and resource allocation under heterogeneous network traffic. Modeling and analysis of active queue management mechanism in the presence of poisson and bursty traffic arrival processes.

      Awan, Irfan U.; Min, Geyong; Wang, Lan (University of BradfordDepartment of Computing, 2010-10-27)
      Along with playing an ever-increasing role in the integration of other communication networks and expanding in application diversities, the current Internet suffers from serious overuse and congestion bottlenecks. Efficient congestion control is fundamental to ensure the Internet reliability, satisfy the specified Quality-of-Service (QoS) constraints and achieve desirable performance in response to varying application scenarios. Active Queue Management (AQM) is a promising scheme to support end-to-end Transmission Control Protocol (TCP) congestion control because it enables the sender to react appropriately to the real network situation. Analytical performance models are powerful tools which can be adopted to investigate optimal setting of AQM parameters. Among the existing research efforts in this field, however, there is a current lack of analytical models that can be viewed as a cost-effective performance evaluation tool for AQM in the presence of heterogeneous traffic, generated by various network applications. This thesis aims to provide a generic and extensible analytical framework for analyzing AQM congestion control for various traffic types, such as non-bursty Poisson and bursty Markov-Modulated Poisson Process (MMPP) traffic. Specifically, the Markov analytical models are developed for AQM congestion control scheme coupled with queue thresholds and then are adopted to derive expressions for important QoS metrics. The main contributions of this thesis are listed as follows: iii ¿ Study the queueing systems for modeling AQM scheme subject to single-class and multiple-classes Poisson traffic, respectively. Analyze the effects of the varying threshold, mean traffic arrival rate, service rate and buffer capacity on the key performance metrics. ¿ Propose an analytical model for AQM scheme with single class bursty traffic and investigate how burstiness and correlations affect the performance metrics. The analytical results reveal that high burstiness and correlation can result in significant degradation of AQM performance, such as increased queueing delay and packet loss probability, and reduced throughput and utlization. ¿ Develop an analytical model for a single server queueing system with AQM in the presence of heterogeneous traffic and evaluate the aggregate and marginal performance subject to different threshold values, burstiness degree and correlation. ¿ Conduct stochastic analysis of a single-server system with single-queue and multiple-queues, respectively, for AQM scheme in the presence of multiple priority traffic classes scheduled by the Priority Resume (PR) policy. ¿ Carry out the performance comparison of AQM with PR and First-In First-Out (FIFO) scheme and compare the performance of AQM with single PR priority queue and multiple priority queues, respectively.