Proactive software rejuvenation solution for web enviroments on virtualized platforms

The availability of the Information Technologies for everything, from everywhere, at all times is a growing requirement. We use information Technologies from common and social tasks to critical tasks like managing nuclear power plants or even the International Space Station (ISS). However, the availability of IT infrastructures is still a huge challenge nowadays. In a quick look around news, we can find reports of corporate outage, affecting millions of users and impacting on the revenue and image of the companies. It is well known that, currently, computer system outages are more often due to software faults, than hardware faults. Several studies have reported that one of the causes of unplanned software outages is the software aging phenomenon. This term refers to the accumulation of errors, usually causing resource contention, during long running application executions, like web applications, which normally cause applications/systems to hang or crash. Gradual performance degradation could also accompany software aging phenomena. The software aging phenomena are often related to memory bloating/ leaks, unterminated threads, data corruption, unreleased file-locks or overruns. We can find several examples of software aging in the industry. The work presented in this thesis aims to offer a proactive and predictive software rejuvenation solution for Internet Services against software aging caused by resource exhaustion. To this end, we first present a threshold based proactive rejuvenation to avoid the consequences of software aging. This first approach has some limitations, but the most important of them it is the need to know a priori the resource or resources involved in the crash and the critical condition values. Moreover, we need some expertise to fix the threshold value to trigger the rejuvenation action. Due to these limitations, we have evaluated the use of Machine Learning to overcome the weaknesses of our first approach to obtain a proactive and predictive solution. Finally, the current and increasing tendency to use virtualization technologies to improve the resource utilization has made traditional data centers turn into virtualized data centers or platforms. We have used a Mathematical Programming approach to virtual machine allocation and migration to optimize the resources, accepting as many services as possible on the platform while at the same time, guaranteeing the availability (via our software rejuvenation proposal) of the services deployed against the software aging phenomena. The thesis is supported by an exhaustive experimental evaluation that proves the effectiveness and feasibility of our proposals for current systems

Targeting complexity of geriatric emergency department visitors: Comprehensiveness in a high-paced and efficiency-focused medical setting

The emergency department (ED) is one of the most important access points to medical care worldwide and a central link between out- and inpatient care. The demographic development is predicted to change the age distribution of patients in the German health system over the next few decades which could strongly affect the ED as a multidisciplinary centre of the health system. Many EDs in Germany have already observed an increase in the number of older and clinically complex patients that bind more resources and personnel capacities. Geriatric patients in the ED are a particularly vulnerable group with an increased risk of clinical complications compared to younger age groups. The higher prevalence of frailty, atypical symptoms, multimorbidity, polypharmacy, neuropsychiatric and cognitive impairments impede fast diagnosis and therapy. The integration of an elaborate and time-consuming assessment of older patients in an otherwise fast-paced and efficiency-driven environment is a major challenge of present-day and future EDs. Therefore, an effective screening for older patients who would benefit from further evaluation will be paramount. Common standardized triage systems of EDs or existing screening instruments like the Identification of Seniors at Risk (ISAR) score show major difficulties in effectively identifying vulnerable older patients. The Multidimensional Prognostic Index (MPI), which is based on a comprehensive geriatric assessment (CGA), has already been tested in numerous settings and might be an alternative to grasp the complexity of older ED patients. An important but rarely evaluated clinical outcome parameter is health-related quality of life (HRQOL). It is a central component of patient-related treatment concepts and plays a crucial role in the care for geriatric patients. Existing literature shows a strong influence of the health status on HRQOL of older people. The results of the study by Rarek et al., on which this thesis is based upon, were able to show that the HRQOL of geriatric ED patients is significantly associated with clinical prognosis at ED admission and up to 6 months after. Attention to the association between patient-related outcome factors such as HRQOL and objective clinical prognosis can improve a holistic approach for allocation decisions in future concepts of geriatric ED care. Various innovative concepts for the improvement of detection and management of geriatric and patients in the ED have been tested and evaluated in the USA in recent years. The initial experience about advantages and disadvantages of approaches that were tested can help to create adapted concepts for the German health care system. First responses to the increasing number of geriatric patients already exist in Germany and range from new screening tools to specialized ED units and an improved linking of different health care providers. Adapting EDs to the complexities and needs of geriatric patients will be a major challenge in an aging society. The global outbreak of the Coronavirus Disease 2019 (COVID-19) pandemic has threatened the health systems of numerous nations and at the time of this publication, the end is still unforeseeable. Many aspects and challenges of the complexity in geriatric patients in clinical practice have been illustrated by the impact of the pandemic on geriatric care. Older, multimorbid and frail patients are particularly affected by this disease due to an increased risk of a severe course of disease and higher mortality. The need to effectively identify vulnerable patients in the ED with a poor clinical prognosis has become more important due to the pandemic-related scarcity of resources. In addition, it has been observed that the COVID-19 pandemic had a negative impact on HRQOL of older people and the treatment of chronic illnesses. Given that geriatric patients have a higher risk for the development of chronic remnants of COVID-19, the pandemic could have unforeseeable influence on future health of the aging society. In the face of demographic changes, present and future challenges for health systems, effective identification and management of frail and vulnerable patients in the ED and structural changes to obtain geriatric-friendly EDs are important steps to guarantee adequate geriatric care and improve the clinical outcome as well as HRQOL

Modelling and Quantitative Analysis of Performance vs Security Trade-offs in Computer Networks: An investigation into the modelling and discrete-event simulation analysis of performance vs security trade-offs in computer networks, based on combined metrics and stochastic activity networks (SANs)

Performance modelling and evaluation has long been considered of paramount importance to computer networks from design through development, tuning and upgrading. These networks, however, have evolved significantly since their first introduction a few decades ago. The Ubiquitous Web in particular with fast-emerging unprecedented services has become an integral part of everyday life. However, this all is coming at the cost of substantially increased security risks. Hence cybercrime is now a pervasive threat for today’s internet-dependent societies. Given the frequency and variety of attacks as well as the threat of new, more sophisticated and destructive future attacks, security has become more prevalent and mounting concern in the design and management of computer networks. Therefore equally important if not more so is security. Unfortunately, there is no one-size-fits-all solution to security challenges. One security defence system can only help to battle against a certain class of security threats. For overall security, a holistic approach including both reactive and proactive security measures is commonly suggested. As such, network security may have to combine multiple layers of defence at the edge and in the network and in its constituent individual nodes. Performance and security, however, are inextricably intertwined as security measures require considerable amounts of computational resources to execute. Moreover, in the absence of appropriate security measures, frequent security failures are likely to occur, which may catastrophically affect network performance, not to mention serious data breaches among many other security related risks. In this thesis, we study optimisation problems for the trade-offs between performance and security as they exist between performance and dependability. While performance metrics are widely studied and well-established, those of security are rarely defined in a strict mathematical sense. We therefore aim to conceptualise and formulate security by analogy with dependability so that, like performance, it can be modelled and quantified. Having employed a stochastic modelling formalism, we propose a new model for a single node of a generic computer network that is subject to various security threats. We believe this nodal model captures both performance and security aspects of a computer node more realistically, in particular the intertwinements between them. We adopt a simulation-based modelling approach in order to identify, on the basis of combined metrics, optimal trade-offs between performance and security and facilitate more sophisticated trade-off optimisation studies in the field. We realise that system parameters can be found that optimise these abstract combined metrics, while they are optimal neither for performance nor for security individually. Based on the proposed simulation modelling framework, credible numerical experiments are carried out, indicating the scope for further work extensions for a systematic performance vs security tuning of computer networks

Website Performance Evaluation and Estimation in an E-business Environment

This thesis introduces a new Predictus-model for performance evaluation and estimation in a multi-layer website environment. The model is based on soft computing ideas, i.e. simulation and statistical analysis. The aim is to improve energy consumption of the website's hardware and investment efficiency and to avoid loss of availability. The aim of optimised exploitation is reduced energy and maintenance costs on the one hand and increased end-user satisfaction due to robust and stable web services on the other. A method based on simulation of user requests is described. Instead of ordinary static parameter set, the dynamic extraction from previous log files is used. The distribution of existing requests is exploited to generate the actual based natural load. By loading the server system with valid and well-known requests, the behaviour of the server system is natural. The control back loop on the generation of work load assures the validity of the work load in the long-term. A method for identifying the actual performance of the website is described. Using the well-known load in simulation of usage by a large number of virtual users and observing the utilisation rate of server resources ensure the best information for the internal state of the system. The disturbance of the service website usage can be avoided using the mathematical extrapolation method to reach the saturation point on the single server resource

Advanced extravehicular activity systems requirements definition study. Phase 2: Extravehicular activity at a lunar base

The focus is on Extravehicular Activity (EVA) systems requirements definition for an advanced space mission: remote-from-main base EVA on the Moon. The lunar environment, biomedical considerations, appropriate hardware design criteria, hardware and interface requirements, and key technical issues for advanced lunar EVA were examined. Six remote EVA scenarios (three nominal operations and three contingency situations) were developed in considerable detail

Between the red tent and the red haze : Representations of perimenopause

Perimenopause is a relatively new word in our language. It is found in a variety of texts, from medical literature to popular literature and the Internet. In this thesis, I explore some current representations of perimenopause. To do so, I utilise feminist analyses of representations of premenstrual syndrome and menopause. A feminist theoretical framework guides my methodology and organisation and interpretation of data. My methodology includes an extensive literature review of feminist theorising around premenstrual syndrome and menopause, as well as discourse analysis of textual representations of perimenopause and the use of a reflexive journal as a \u27perimenopausal\u27 woman. My analysis reveals four main themes; first, perimenopause is a medically defined condition that needs management; second, perimenopause is confusing and contradictory; third, perimenopause is to be feared; and fourth, perimenopause is a time of rejuvenation. I show that three of these themes are similar to themes found in the discourses of premenstrual syndrome and menopause. The implications of these themes are discussed. I conclude by arguing that perimenopause is a distinct discourse that merits further feminist attention

Healthy You

https://scholarlyworks.lvhn.org/healthy-you/1037/thumbnail.jp

Cybernationalism and cyberactivism in China

El nacionalismo en la era de Internet se está convirtiendo cada vez más en un factor esencial que influye en la agenda-setting de la sociedad china, así como en las relaciones de China con los países extranjeros, especialmente con Occidente. Para China, una mejor comprensión de la estructura teórica universal y de los patrones de comportamiento del nacionalismo facilitaría la articulación social general de esta tendencia y potenciaría su papel positivo en la agenda-setting social. Por otra parte, un estudio del cibernacionalismo chino basado en una perspectiva china en el mundo académico occidental es un intento de transculturación. Desde el punto de vista de las relaciones internacionales y la geopolítica actuales, que son bastante urgentes, este intento ayudaría a mejorar la compatibilidad de China con el actual orden mundial dominado por Occidente, a reducir la desinformación entre China y otros países y a sentar las bases culturales e ideológicas para otras colaboraciones internacionales. Teniendo en cuenta el estado actual de la investigación sobre el nacionalismo chino y la naturaleza participativa de las masas del cibernacionalismo, esta disertación se centra en el cibernacionalismo en las tres partes siguientes. El primero es un estudio de los orígenes históricos del cibernacionalismo chino. Esta sección incluye tanto una exploración del consenso social en la antigua China como un estudio de la influencia del nacionalismo en la historia china moderna. El estudio de los orígenes históricos no sólo nos muestra la secuencia cronológica de la experiencia del desarrollo y la evolución tanto del proto-nacionalismo como del nacionalismo en China, sino que también revela un impulso decisivo para las reivindicaciones y comportamientos actuales del cibernacionalismo. La segunda parte trata del proceso de formación y ascenso del cibernacionalismo desde el siglo XXI. El importante antecedente del paso del nacionalismo al cibernacionalismo es el proceso de informatización de la sociedad china. Una vez completado el estudio de la situación básica de la sociedad china de Internet, especialmente el estudio de los medios sociales como espacio público, podemos vincular Internet con el nacionalismo y examinar el nuevo desarrollo del nacionalismo en la era de la participación de masas. El objetivo final es conectar el proto-nacionalismo, el nacionalismo y el cibernacionalismo, y seguir construyendo una comprensión del cibernacionalismo que sea coherente tanto con los principios universales del nacionalismo como con el contexto chino. Por último, validamos los resultados derivados del estudio anterior a través de la realidad social, es decir, estudiando las prácticas de ciberactivismo del cibernacionalismo para juzgar su suficiencia general así como su validez. Llevaremos a cabo varios estudios de caso de natural language processing basados en big data para reproducir la lógica de comportamiento y el impacto real del ciberactivismo de la manera más cercana posible a la realidad de Internet, evitando al mismo tiempo los defectos de argumentación unilateral y de infrarrepresentación de los estudios de caso tradicionales.Nationalism in the Internet age is increasingly becoming an essential factor influencing agendasetting within Chinese society, as well as China’s relations with foreign countries, especially the West. For China, a better understanding of the universal theoretical structure and behavioral patterns of nationalism would facilitate the overall social articulation of this trend and enhance its positive role in social agenda setting. On the other hand, a study of Chinese cybernationalism based on a Chinese perspective in western academia is an attempt at transculturation. From the viewpoint of the current rather urgent international relations and geopolitics, such an attempt would help to enhance China’s compatibility with the current western-dominated world order, reduce misinformation between China and other countries, and lay the cultural and ideological groundwork for various other international collaborations. Considering the current state of Chinese nationalism research and the mass participatory nature of cybernationalism, this dissertation focuses on cybernationalism in the following three parts. The first is a study of the historical origins of Chinese cybernationalism. This section includes both an exploration of the social consensus in ancient China and a survey of the influence of nationalism in modern Chinese history. The historical origins study not only shows us the chronological sequence of experiencing the development and evolution of both proto-nationalism and nationalism in China, but also reveals a decisive impetus for the current claims and behaviors of cybernationalism. The second part deals with the process of formation and rise of cybernationalism since the 21st century. The important background for the move from nationalism to cybernationalism is the informatization process of Chinese society. After we have completed the study of the basic situation of Chinese Internet society, especially the study of social media as a public space, we can link the Internet with nationalism and examine the new development of nationalism in the era of mass participation. The ultimate goal is to connect the proto-nationalism, nationalism, cybernationalism, and furtherly construct an understanding of cybernationalism that is consistent with both the universal principles of nationalism and the Chinese context. Finally, we validate the results derived from the previous study through social reality, i.e., by studying the cyberactivism practices of cybernationalism to judge its general sufficiency as well as validity. We will conduct several natural language processing case studies based on big data to reproduce the behavioral logic and actual impact of cyberactivism in the closest possible way to the Internet reality while avoiding the unilateral argumentation and under-representation flaws of traditional case studies

Online failure prediction in air traffic control systems

This thesis introduces a novel approach to online failure prediction for mission critical distributed systems that has the distinctive features to be black-box, non-intrusive and online. The approach combines Complex Event Processing (CEP) and Hidden Markov Models (HMM) so as to analyze symptoms of failures that might occur in the form of anomalous conditions of performance metrics identified for such purpose. The thesis presents an architecture named CASPER, based on CEP and HMM, that relies on sniffed information from the communication network of a mission critical system, only, for predicting anomalies that can lead to software failures. An instance of Casper has been implemented, trained and tuned to monitor a real Air Traffic Control (ATC) system developed by Selex ES, a Finmeccanica Company. An extensive experimental evaluation of CASPER is presented. The obtained results show (i) a very low percentage of false positives over both normal and under stress conditions, and (ii) a sufficiently high failure prediction time that allows the system to apply appropriate recovery procedures

Online failure prediction in air traffic control systems

This thesis introduces a novel approach to online failure prediction for mission critical distributed systems that has the distinctive features to be black-box, non-intrusive and online. The approach combines Complex Event Processing (CEP) and Hidden Markov Models (HMM) so as to analyze symptoms of failures that might occur in the form of anomalous conditions of performance metrics identified for such purpose. The thesis presents an architecture named CASPER, based on CEP and HMM, that relies on sniffed information from the communication network of a mission critical system, only, for predicting anomalies that can lead to software failures. An instance of Casper has been implemented, trained and tuned to monitor a real Air Traffic Control (ATC) system developed by Selex ES, a Finmeccanica Company. An extensive experimental evaluation of CASPER is presented. The obtained results show (i) a very low percentage of false positives over both normal and under stress conditions, and (ii) a sufficiently high failure prediction time that allows the system to apply appropriate recovery procedures