121 resultados para distributed denial-of-service attack


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In most agent-based systems, different middle agents are employed to increase their flexibility. However, there are still three issues remain unsolved. In centralized architecture with single middle agent, the middle agent itself is a bottleneck and suffers from single point failure; middle agents in distributed architecture lack capability of dynamic organization of agents; The reliability is not strong because of the single point failure and lack of effective architecture. We introduce a platform with ring architectural model to solve all above problems. In the platform, multiple middle agents are dynamically supported for solving the first problem. For solving the second problem, middle agents dynamically manage the registration and cancellation of service provider agents and application teams, each of which includes a set of closely interacting requester agents to complete an independent task. Redundancy middle agent technique is proposed for solving the third problem. All middle agents are of the feature of proliferation and self-cancellation according to the sensory inputs from their environment. For organizing the middle agents effectively, a ring architectural model is proposed. We demonstrate the applicability of the platform by its application and present experimental evidence that the platform is flexible and robust.

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Studies of the construct of service quality have traditionally been undertaken from the perspective of the service receiver. More recently, research has focused on both the service provider's perspective and the service receiver's perspective. In addition, there have also been some triadic network approaches to the study of service quality. However, there has been very little research into sequential service quality in service-encounter chains (that is, consecutive service performances in a series of service encounters). The incorporation of connected service encounters in services management can improve understanding of sequential service quality in service-encounter chains. This paper provides a customized construct of sequential service quality and  highlights the importance of time, context, and performance threshold in service-encounter chains. Furthermore, the paper presents a customized six-dimensional construct of sequential service quality.

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Background: The prevalence of heart failure in Australia is similar to that of Europe. In Australia, chronic heart failure management programs (CHF-MPs) have become part of standard care for patients with Chronic Heart Failure (CHF). However, heterogeneity among programs is common which can result in variable patient outcomes.

Method: A national survey was undertaken of 59 post-discharge CHF-MPs identified from within the Australian health care system. Two had ceased operating and one centre declined to participate in the study. A 33-item investigator-developed questionnaire, examining the characteristics and interventions used within each CHF-MP, was sent to the remaining 56 CHF-MPs. A response rate of 100% was achieved.

Results: Our survey revealed a disproportional distribution of CHF-MPs across the Australian continent: the State of Victoria had 3.6 CHF-MPs/million population, New South Wales had 3.7 CHF-MPs/million population, Queensland had 1 program/million population, South Australia had 0.3 CHF-MPs/million population and Western Australia had 1 program/million population.Overall, 8000 postdischarge CHF pts (median: 126; IQR: 26-260) were managed via CHF-MPs. Approximately 40,000 CHF pts are discharged from metropolitan institutions nationally, this represents only 22% of the potential caseload for these cost-effective CHF-MPs. Only 8% of these programs were located within rural regions. The majority of CHF-MPs were located within an acute metropolitan hospital (52%) and 36% were community based (all associated with a hospital). Heterogeneity of CHF-MPs in applied models of care was evident with 75% of CHF-MPs offering CHF outpatient clinics and 77% conducting home visits. Of the programs offering home visits 78% were funded by regional government (p<0.048). There were no nurse-led CHF outpatient clinics. A hybrid approach to CHF-MPs was common with many CHF-MPs comprising an outpatient clinic, home visits and inpatient visits. Various medications were titrated by nurses in 43% of CHF-MPs. In the programs that allowed nurses to titrate medications 79% were located in an acute hospital (p<0.011).

Conclusion: Variability of service availability is of concern within the context of universal coverage. In addition, heterogeneity between programs and the diversity in models of care delivery highlights the inconsistency and questions the quality of health related outcomes. We are currently analysing health outcome data from the 1015 patients managed in these CHF-MPs to describe the relationship between quality of care and health outcomes.

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The study examines how organizational activities of compensation and empowerment impact on consumers switching intentions and also whether these differ based on the speed of service recovery. Data is collected using hypothetical scenarios in a situation of process failure. It is found that there is no direct effect of either compensation or empowerment on switching intent, although the interaction effect is significant when recovery occurs quickly.

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This chapter explores the provision of after-sales information technology (IT) support services using Web-based self-service systems (WSSs) in a business-to-business (B2B) context. A recent study conducted at six large multi-national IT support organisations revealed a number of critical success factors (CSFs) and stakeholder-based issues. To better identify and understand these important enablers and barriers, we explain how WSSs should be considered within a complex network of service providers, business partners and customer firms. The CSFs and stakeholder-based issues are discussed. The chapter highlights that for more successful service provision using WSSs, IT service providers should collaborate more effectively with enterprise customers and business partners and should better integrate their WSSs.

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Dynamic deployment of Web services is a term used frequently when describing the selection and deployment of a service to a grid host. Although current grid systems (such as Globus) provide dynamic deployment, the requirements of the service being deployed are not considered. Therefore truly dynamic deployment cannot be achieved as the services deployed are restricted to the grid system used. We present a dynamic deployment mechanism as part of self configuration in a service oriented grid environment. The dynamic deployment mechanism takes the requirements of the service into consideration, including parameters such as the operating system required to execute the service, the required software libraries, any additional required software packages, price and Quality of Service (QoS) parameters.

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Self-service technologies (SSTs), such as machine assisted and electronic services are prevalent. Many established brands in industries such as banking, retailing, and hospitality have adopted SSTs to complement or replace existing channels of service delivery, e.g., face-to-face service. However, the influence of SSTs on established brands has not been examined previously. In the light of this, a conceptual model is proposed that incorporates SST-related variables and their influence on brand satisfaction, brand associations, brand attitudes, and brand loyalty, along with customers' future likelihood to reuse the SST. Arguably, these outcomes affect brand equity and the long-term survival of SSTs.

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This study employed a 3 x 2 full-factorial, between-subjects design experiment examining the influence of service guarantee compensation and fix on hotel guests’ satisfaction following invocation of a service guarantee. The study involved a sample of 390 online panel members. As expected, satisfaction is enhanced when the problem is corrected, however overcompensating guests beyond what was initially promised does not enhance satisfaction evaluations. Increasing compensation from the low to the medium (promised) level results in stronger satisfaction ratings when the problem is fixed versus when it is not.

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A common characteristic among parallel/distributed programming languages is that the one language is used to specify not only the overall organisation of the distributed application, but also the functionality of the application. That is, the connectivity and functionality of processes are specified within a single program. Connectivity and functionality are independent aspects of a distributed application. This thesis shows that these two aspects can be specified separately, therefore allowing application designers to freely concentrate on either aspect in a modular fashion. Two new programming languages have been developed for specifying each aspect. These languages are for loosely coupled distributed applications based on message passing, and have been designed to simplify distributed programming by completely removing all low level interprocess communication. A suite of languages and tools has been designed and developed. It includes the two new languages, parsers, a compilation system to generate intermediate C code that is compiled to binary object modules, a run-time system to create, manage and terminate several distributed applications, and a shell to communicate with the run-tune system. DAL (Distributed Application Language) and DAPL (Distributed Application Process Language) are the new programming languages for the specification and development of process oriented, asynchronous message passing, distributed applications. These two languages have been designed and developed as part of this doctorate in order to specify such distributed applications that execute on a cluster of computers. Both languages are used to specify orthogonal components of an application, on the one hand the organisation of processes that constitute an application, and on the other the interface and functionality of each process. Consequently, these components can be created in a modular fashion, individually and concurrently. The DAL language is used to specify not only the connectivity of all processes within an application, but also a cluster of computers for which the application executes. Furthermore, sub-clusters can be specified for individual processes of an application to constrain a process to a particular group of computers. The second language, DAPL, is used to specify the interface, functionality and data structures of application processes. In addition to these languages, a DAL parser, a DAPL parser, and a compilation system have been designed and developed (in this project). This compilation system takes DAL and DAPL programs to generate object modules based on machine code, one module for each application process. These object modules are used by the Distributed Application System (DAS) to instantiate and manage distributed applications. The DAS system is another new component of this project. The purpose of the DAS system is to create, manage, and terminate many distributed applications of similar and different configurations. The creation procedure incorporates the automatic allocation of processes to remote machines. Application management includes several operations such as deletion, addition, replacement, and movement of processes, and also detection and reaction to faults such as a processor crash. A DAS operator communicates with the DAS system via a textual shell called DASH (Distributed Application SHell). This suite of languages and tools allowed distributed applications of varying connectivity and functionality to be specified quickly and simply at a high level of abstraction. DAL and DAPL programs of several processes may require a few dozen lines to specify as compared to several hundred lines of equivalent C code that is generated by the compilation system. Furthermore, the DAL and DAPL compilation system is successful at generating binary object modules, and the DAS system succeeds in instantiating and managing several distributed applications on a cluster.

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This article focuses on Atom Egoyan's Ararat and explores how, through a convoluted narrative structure, Egoyan grapples with denial of the Armenian Genocide and the consequences of those denials for present generations—both Turkish and Armenian—illuminated in the film as an extension of the genocide. Egoyan uses a film-within-a-film to move beyond a popular definition of genocide as mass killing alone and links the understanding of stories, truths, and perspectives in everyday life to the dehumanizing acts of genocide. Employing the philosopher Emmanuel Levinas’ ethical theory of the Other (the ethical) and philosophical understandings of ontology (dehumanization) to illuminate the genocide and its ongoing denial, this article contends that Egoyan's focus on the generations of genocide survivors points to the ethical responsibility to one another that underlies everyday lives and sits at the heart of what is absent in the acts of genocide.

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Service innovation is of increasing importance in the Australian economy, yet it remains a largely neglected area of study. Recent studies overseas have shown that services are becoming more engaged with innovation, and that service innovation is complex and multi-dimensional. Official R&D and business innovation statistics in Australia are examined, and they reveal that service providers across all service industries in Australia are performing R&D and are actively innovating, a finding that is consonant with the overseas studies. However, innovation performance varies across and within service industries, reflecting differences in the nature and structure of those industries. A clear need for further research is identified, both to provide a clearer understanding of the nature of service innovation and to provide a basis for practical recommendations.

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Objective. To outline the major findings of a qualitative evaluation of an Early Psychosis Service 3 years after its establishment.

Design. Data to evaluate the service were collected from team meetings, focus groups, individual interviews and questionnaires administered to clinicians, school staff, patients, carers and families.

Setting. Barwon Health; Mental Health, Drug and Alcohol Services provide public mental health care to the Geelong, Victoria, region (population 270 000), which is a mixed urban and rural setting. The Early Psychosis Service model implemented involved the placement of two early psychosis workers into each offive adult geographically based Area Mental Health Teams rather than the establishment of a single Early Psychosis Team.

Results. The service was found not to adhere to its original design in several key respects. Caseloads and periods of case management were found to be lower and shorter respectively than was originally planned for, caseworkers often experienced isolation and resentment from their adult service coworkers, the service was perceived to be difficult to access and premises not to be youth friendly and communication and engagement with external agencies and service providers was perceived to be poor.

Conclusions. The choice of service model, inadequate consultation with stakeholders and inadequate promotion of the service contributed to its failure to reach early expectations. Because of these and other issues, including difficulties distinguishing between early psychosis and non-psychosis, a decision was made to restructure youth services and

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Libraries are dynamic organization providing dynamic services to their patrons. However, advances in IT and networking have created a serious competition to libraries from many information service provisioning agents. The purpose of this study is to understand the issue relevant to service quality assessment in libraries and subsequently develop a conceptual model of aligning library quality of service assessment for effective reporting of library value and performance to stakeholders. In this paper, we will focus on the provision of library services and the nature of the relationship and interactions between various components of library services.

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A wireless sensor network (WSN) is a group of sensors that are geographically distributed and interconnected by wireless networks. Sensors gather information about the state of physical world. Then, after processing forward them to the main destination. To be able to provide this service, there are many aspects of communication techniques that need to be explored. Supporting quality of service (QoS) will be of critical importance for pervasive WSNs that serve as the network infrastructure of diverse applications. To illustrate new research and development interests in this field, this paper examines and discusses the requirements, critical challenges, and open research issues on QoS management in WSNs. A brief overview of recent progress is given.

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Addressing core issues in mobile surveillance, we present an architecture for querying and retrieving distributed, semi-permanent multi-modal data through challenged networks with limited connectivity. The system provides a rich set of queries for spatio-temporal querying in a surveillance context, and uses the network availability to provide best quality of service. It incrementally and adaptively refines the query, using data already retrieved that exists on static platforms and on-demand data that it requests from mobile platforms. We demonstrate the system using a real surveillance system on a mobile 20 bus transport network coupled with static bus depot infrastructure. In addition, we show the robustness of the system in handling different conditions in the underlying infrastructure by running simulations on a real, but historic dataset collected in an offline manner.