931 resultados para change-point detection


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Intrusion detection is a critical component of security information systems. The intrusion detection process attempts to detect malicious attacks by examining various data collected during processes on the protected system. This paper examines the anomaly-based intrusion detection based on sequences of system calls. The point is to construct a model that describes normal or acceptable system activity using the classification trees approach. The created database is utilized as a basis for distinguishing the intrusive activity from the legal one using string metric algorithms. The major results of the implemented simulation experiments are presented and discussed as well.

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2000 Mathematics Subject Classification: Primary 60G70, 62F03.

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The purpose of this article is to investigate in which ways multi-level actor cooperation advances national and local implementation processes of human rights norms in weak-state contexts. Examining the cases of women’s rights in Bosnia and Herzegovina and children’s rights in Bangladesh, we comparatively point to some advantages and disadvantages cooperative relations between international organisations, national governments and local NGOs can entail. Whereas these multi-level actor constellations (MACs) usually initiate norm implementation processes reliably and compensate governmental deficits, they are not always sustainable in the long run. If international organisations withdraw support from temporary missions or policy projects, local NGOs are not able to perpetuate implementation activities if state capacities have not been strengthened by MACs. Our aim is to highlight functions of local agency within multi-level cooperation and to critically raise sustainability issues in human rights implementation to supplement norm research in International Relations.

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We propose that key concepts from clinical psychotherapy can inform science-based initiatives aimed at building tolerance and community cohesion. Commonalities in social and clinical psychology are identified regarding (1) distorted thinking (intergroup bias and cognitive bias), (2) stress and coping (at intergroup level and intrapersonal level), and (3) anxiety (intergroup anxiety and pathological anxiety). On this basis we introduce a new cognitive-behavioral model of social change. Mental imagery is the conceptual point of synthesis, and anxiety is at the core, through which new treatment-based approaches to reducing prejudice can be developed. More generally, we argue that this integration is illustrative of broader potential for cross-disciplinary integration in the social and clinical sciences, and has the potential to open up new possibilities and opportunities for both disciplines.

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Even simple hybrid automata like the classic bouncing ball can exhibit Zeno behavior. The existence of this type of behavior has so far forced a large class of simulators to either ignore some events or risk looping indefinitely. This in turn forces modelers to either insert ad-hoc restrictions to circumvent Zeno behavior or to abandon hybrid automata. To address this problem, we take a fresh look at event detection and localization. A key insight that emerges from this investigation is that an enclosure for a given time interval can be valid independent of the occurrence of a given event. Such an event can then even occur an unbounded number of times. This insight makes it possible to handle some types of Zeno behavior. If the post-Zeno state is defined explicitly in the given model of the hybrid automaton, the computed enclosure covers the corresponding trajectory that starts from the Zeno point through a restarted evolution.

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The spectral properties of long-period gratings (LPGs) fabricated in photonic crystal fibers using femtosecond laser pulses by the point-by-point technique, without oil-immersion of the fiber, are investigated in detail. Postfabrication spectral monitoring at room temperature showed significant long-term instability of the gratings and stable spectra only after 600 h. The stabilized spectral properties of the gratings improved with increasing annealing temperature. The observed changes in resonant wavelength, optical strength, and grating birefringence were correlated to the laser inscription energy and were further used to study the mechanism of femtosecond inscription. Furthermore, the femtosecond-laser inscribed LPGs were compared to electric-arc fabricated LPGs. Comparison of experimental results with theoretical models of LPGs and laser propagation during inscription indicate that the major processes responsible for the index change are permanent compaction and thermally induced strain, the latter can be significantly changed through annealing. © 2011 Optical Society of America.

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Engineering education in the United Kingdom is at the point of embarking upon an interesting journey into uncharted waters. At no point in the past have there been so many drivers for change and so many opportunities for the development of engineering pedagogy. This paper will look at how Engineering Education Research (EER) has developed within the UK and what differentiates it from the many small scale practitioner interventions, perhaps without a clear research question or with little evaluation, which are presented at numerous staff development sessions, workshops and conferences. From this position some examples of current projects will be described, outcomes of funding opportunities will be summarised and the benefits of collaboration with other disciplines illustrated. In this study, I will account for how the design of task structure according to variation theory, as well as the probe-ware technology, make the laws of force and motion visible and learnable and, especially, in the lab studied make Newton's third law visible and learnable. I will also, as a comparison, include data from a mechanics lab that use the same probe-ware technology and deal with the same topics in mechanics, but uses a differently designed task structure. I will argue that the lower achievements on the FMCE-test in this latter case can be attributed to these differences in task structure in the lab instructions. According to my analysis, the necessary pattern of variation is not included in the design. I will also present a microanalysis of 15 hours collected from engineering students' activities in a lab about impulse and collisions based on video recordings of student's activities in a lab about impulse and collisions. The important object of learning in this lab is the development of an understanding of Newton's third law. The approach analysing students interaction using video data is inspired by ethnomethodology and conversation analysis, i.e. I will focus on students practical, contingent and embodied inquiry in the setting of the lab. I argue that my result corroborates variation theory and show this theory can be used as a 'tool' for designing labs as well as for analysing labs and lab instructions. Thus my results have implications outside the domain of this study and have implications for understanding critical features for student learning in labs. Engineering higher education is well used to change. As technology develops the abilities expected by employers of graduates expand, yet our understanding of how to make informed decisions about learning and teaching strategies does not without a conscious effort to do so. With the numerous demands of academic life, we often fail to acknowledge our incomplete understanding of how our students learn within our discipline. The journey facing engineering education in the UK is being driven by two classes of driver. Firstly there are those which we have been working to expand our understanding of, such as retention and employability, and secondly the new challenges such as substantial changes to funding systems allied with an increase in student expectations. Only through continued research can priorities be identified, addressed and a coherent and strong voice for informed change be heard within the wider engineering education community. This new position makes it even more important that through EER we acquire the knowledge and understanding needed to make informed decisions regarding approaches to teaching, curriculum design and measures to promote effective student learning. This then raises the question 'how does EER function within a diverse academic community?' Within an existing community of academics interested in taking meaningful steps towards understanding the ongoing challenges of engineering education a Special Interest Group (SIG) has formed in the UK. The formation of this group has itself been part of the rapidly changing environment through its facilitation by the Higher Education Academy's Engineering Subject Centre, an entity which through the Academy's current restructuring will no longer exist as a discrete Centre dedicated to supporting engineering academics. The aims of this group, the activities it is currently undertaking and how it expects to network and collaborate with the global EER community will be reported in this paper. This will include explanation of how the group has identified barriers to the progress of EER and how it is seeking, through a series of activities, to facilitate recognition and growth of EER both within the UK and with our valued international colleagues.

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2004-ben Magyarország kilenc közép-kelet-európai országgal együtt csatlakozott az Európai Unióhoz, ami számos változást idézett elő az agrárkereskedelem terén. A cikk célja, hogy a legfrissebb adatok és a szakirodalmi fejlemények tükrében bemutassa, hogyan alakult Magyarországon a mezőgazdasági alapanyagok és a feldolgozott termékek kereskedelme az Európai Unióval. A megnyilvánuló komparatív előnyök módszerét alkalmazva a cikk számos következtetésre jutott. Először is világossá vált, hogy a csatlakozás növelte az agrárkereskedelem intenzitását, ám negatív hatással volt a kereskedelem egyenlegére. Kimutatható továbbá, hogy Magyarország az alacsony hozzáadott értékű alapanyagexportra és a magas hozzáadott értékű feldolgozott termékek importjára koncentrált a csatlakozás után, noha ezek komparatív előnyei nagymértékben megváltoztak egy hatékony alkalmazkodási folyamat következtében. A változások tényét támasztják alá a különböző rövid és hosszú távú stabilitásvizsgálatok is, amelyek az agrártermékek megnövekedett versenyére utalnak az EU-15 piacán. Agrárpolitikai szempontból az elemzések alátámasztják a strukturális reformok szükségességét. / === / Numerous changes in agricultural trading from the EU accession of Hungary and nine other Central-East European countries in 2004. The article sets out to present, in the light of the latest figures and written contributions, how Hungary’s EU trade in agricultural raw and semi-processed products developed thereafter. It uses the method of manifest comparative advantages to reach its conclusions. First, it became clear that accession increased the intensity of agricultural trading, although it had a detrimental effect on the trade balance. It also appeared that post-accession Hungary was concentrating on exports of basic materials of low added value and imports of processed articles with high added value, although these comparative advantages were much altered by an effective process of adaptation. The fact of the changes is supported by various short and long-term stability examinations, which point to increased competition for agricultural products on EU15 markets. From the policy point of view, the analyses support the need for structural reforms.

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A lean termelési rendszer munkásokra gyakorolt hatásaival foglalkozó irodalomban nincsen egyetértés annak megítélésében, hogy a hatásokban a negatív vagy pozitív hatások dominálnak-e. A szerző tanulmánya ehhez a vitához a pszichológiai, egészségügyi, munkahelyi jellemzőkre és a dolgozói elégedettségre vonatkozó eredmények áttekintésével kapcsolódik. A munkások elégedettségének vizsgálata arra utal, hogy a lean termelési rendszer egyszerre növeli és csökkenti is az elégedettséget, így az összességében nem változik más termelési rendszerekhez képest. A lean termelés kritikusai azt hangsúlyozzák, hogy a többi tényező negatívan hat a munkásokra. Megállapításaik megalapozottsága a nagyon kevés empirikus munka miatt megkérdőjelezhető. Ugyanakkor a tevékenységmenedzsment kutatói érdemben nem tudják cáfolni a stressz, a sérülések és betegségek kockázatának növekedését és a munka intenzívebbé válását. A negatív hatások és a várt pozitív hatások hiányának kiemelése felveti, hogy a munkavállalók bevonásán alapuló lean termelési rendszer nehezen ültethető át a gyakorlatba, illetve hogy a lean termelés intenzifikáción alapuló modellje is elterjedt. _____________ This literature review contributes to the debate related to the effects of lean production on workers. The study reviews different dimensions of the debate and focuses on issues like worker’s satisfaction, psychological effects, health and safety aspects, and workplace characteristics. Findings of researches reviewed in this paper cannot confirm that from workers’ point of view lean production is better than other production initiatives. Lean production enhances and decreases worker’s satisfaction at the same time, altogether, the satisfaction of workers does not change significantly compared to other systems. The negative impact of the other factors (psychological etc.) on workers is usually emphasized in the critique of lean production. Although, the limited number of (empirical) studies doubts these critical voices. However, Operations Management can not reject negative effects like increasing level of stress, increased risks of health and safety problems or intensification of work. The emphasis of the negative effects and the lack of positive effects can refer to the difficult employment of lean involvement system, or simply reflect that the model of lean intensification system is widely spread.

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A dolgozatban a hitelderivatívák intenzitásalapú modellezésének néhány kérdését vizsgáljuk meg. Megmutatjuk, hogy alkalmas mértékcserével nemcsak a duplán sztochasztikus folyamatok, hanem tetszőleges intenzitással rendelkező pontfolyamat esetén is kiszámolható az összetett kár- és csődfolyamat eloszlásának Laplace-transzformáltja. _____ The paper addresses questions concerning the use of intensity based modeling in the pricing of credit derivatives. As the specification of the distribution of the lossprocess is a non-trivial exercise, the well-know technique for this task utilizes the inversion of the Laplace-transform. A popular choice for the model is the class of doubly stochastic processes given that their Laplace-transforms can be determined easily. Unfortunately these processes lack several key features supported by the empirical observations, e.g. they cannot replicate the self-exciting nature of defaults. The aim of the paper is to show that by using an appropriate change of measure the Laplace-transform can be calculated not only for a doubly stochastic process, but for an arbitrary point process with intensity as well. To support the application of the technique, we investigate the e®ect of the change of measure on the stochastic nature of the underlying process.

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Az elmúlt két évtized folyamán a menedzserek megtanultak a megújult szabályok szerint játszani. Tudatosították, hogy a vállalatuk eredményes navigálásához folyamatosan figyelniük és adaptálniuk kell a legújabb módszereket, elméleteket. Jelen tanulmányával a szerző ezt a folyamatot kívánja segíteni, valamint arra az alapvető kérdésre keresi a választ, hogy érdemes-e a rendkívül gyorsan változó világban hosszabb távú célok meghatározásával foglalkozni, és ha igen, akkor mire összpontosítsák a vállalatok erőfeszítéseiket. Milyen részletezettséggel, milyen módon határozzák meg az elképzeléseiket úgy, hogy közben megőrizzék a vállalat flexibilitását, a változások idején nélkülözhetetlen agilitást. A szerző arra vállalkozik, hogy feltárja a stratégiai paradigmaváltás fejlődését, a termelési stratégia, az operations management központi meghatározó szereppé válását, valamint áttekintse a termelési és szolgáltatási rendszervezetés (OM) elveinek, eszközeinek, módszereinek fejlődését, kölcsönhatását, összefüggéseit. _______ Change of paradigm has taken place in strategic planning. Fight for position turned into a fight of movement. Companies strive to achieve individual, not copyable organizational performance, as well as to realize their business strategies by means of value generating, proactive approach. Operative management now placed in the focus of production strategy is becoming the compass, the driving force of leadership. The management of production and service systems has grown into independent scientific disciplines. It yielded such principles, tools and methods which are present as world-renowned blueprints (scientific tools) in the field of maintaining and developing corporate performance. In the present study the author specifies and discusses the tools of operative management as criteria of value generation aiming at quality and cost efficiency. He analyses the backto- back character, interrelationship of quality, TQM (Total Quality Management), TPS (Toyota Production System) and JIT (Just in Time). He examines the effects thereof on corporate performance where significant and strong relationship can be demonstrated in case there is an ability to plan and develop new products. The current new OM (Operations Management) techniques increasingly rely upon the quality of human resources, the permanent improvement of procedures as well as focusing on tight cooperation with suppliers/customers. Supply chain management, core competence management, service management now represent a “new generation” of the OM methods, processes, serving at the same time as basis and starting point for expectable future techniques as well.

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Hurricanes, earthquakes, floods, and other serious natural hazards have been attributed with causing changes in regional economic growth, income, employment, and wealth. Natural disasters are said to cause; (1) an acceleration of existing economic trends; (2) an expansion of employment and income, due to recovery operations (the so-called silver lining); and (3) an alteration in the structure of regional economic activity due to changes in "intra" and "inter" regional trading patterns, and technological change.^ Theoretical and stylized disaster simulations (Cochrane 1975; Haas, Cochrane, and Kates 1977; Petak et al. 1982; Ellson et al. 1983, 1984; Boisvert 1992; Brookshire and McKee 1992) point towards a wide scope of possible negative and long lasting impacts upon economic activity and structure. This work examines the consequences of Hurricane Andrew on Dade County's economy. Following the work of Ellson et al. (1984), Guimaraes et al. (1993), and West and Lenze (1993; 1994), a regional econometric forecasting model (DCEFM) using a framework of "with" and "without" the hurricane is constructed and utilized to assess Hurricane Andrew's impact on the structure and level of economic activity in Dade County, Florida.^ The results of the simulation exercises show that the direct economic impact associated with Hurricane Andrew on Dade County is of short duration, and of isolated sectoral impact, with impact generally limited to construction, TCP (transportation, communications, and public utilities), and agricultural sectors. Regional growth, and changes in income and employment reacted directly to, and within the range and direction set by national economic activity. The simulations also lead to the conclusion that areal extent, infrastructure, and sector specific damages or impacts, as opposed to monetary losses, are the primary determinants of a disaster's effects upon employment, income, growth, and economic structure. ^

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Before dawn on August 24, 1992, Hurricane Andrew smashed into south Florida, particularly southern Dade County, and soon become the costliest natural disaster in U.S. history. Andrew's impacts quickly overwhelmed local and state emergency response capabilities and eventually required major federal assistance, including regular military units. While the social and economic impacts of Hurricane Andrew are relatively well researched, much less attention has been given to its possible political effects. ^ Focusing on incumbent officeholders at three levels (municipal, state legislative, and statewide) who stood for reelection after Hurricane Andrew, this study seeks to determine whether they experienced any political effects from Andrew. That is, this study explores the possible interaction between the famous “incumbency advantage” and an “extreme event,” in this case a natural disaster. The specific foci were (1) campaigns and campaigning (a research process that included 43 personal interviews), and (2) election results before and after the event. ^ Given well-documented response problems, the working hypothesis was that incumbents experienced largely negative political fallout from the disaster. The null hypothesis was that incumbents saw no net political effects, but the reverse hypothesis was also considered: incumbents benefited politically from the event. ^ In the end, this study found that although the election process was physically disrupted, especially in south Dade County, the disaster largely reinforced the incumbency advantage. More specifically, the aftermath of Hurricane Andrew allowed most incumbent officeholders to (1) enhance constituency service, (2) associate themselves with the flow of external assistance, (3) achieve major personal visibility and media coverage, and yet (4) appear non-political or at least above normal politics. Overall, this combination allowed incumbents to very effectively “campaign without campaigning,” a point borne out by post-Andrew election results. ^

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Recent advances in airborne Light Detection and Ranging (LIDAR) technology allow rapid and inexpensive measurements of topography over large areas. Airborne LIDAR systems usually return a 3-dimensional cloud of point measurements from reflective objects scanned by the laser beneath the flight path. This technology is becoming a primary method for extracting information of different kinds of geometrical objects, such as high-resolution digital terrain models (DTMs), buildings and trees, etc. In the past decade, LIDAR gets more and more interest from researchers in the field of remote sensing and GIS. Compared to the traditional data sources, such as aerial photography and satellite images, LIDAR measurements are not influenced by sun shadow and relief displacement. However, voluminous data pose a new challenge for automated extraction the geometrical information from LIDAR measurements because many raster image processing techniques cannot be directly applied to irregularly spaced LIDAR points. ^ In this dissertation, a framework is proposed to filter out information about different kinds of geometrical objects, such as terrain and buildings from LIDAR automatically. They are essential to numerous applications such as flood modeling, landslide prediction and hurricane animation. The framework consists of several intuitive algorithms. Firstly, a progressive morphological filter was developed to detect non-ground LIDAR measurements. By gradually increasing the window size and elevation difference threshold of the filter, the measurements of vehicles, vegetation, and buildings are removed, while ground data are preserved. Then, building measurements are identified from no-ground measurements using a region growing algorithm based on the plane-fitting technique. Raw footprints for segmented building measurements are derived by connecting boundary points and are further simplified and adjusted by several proposed operations to remove noise, which is caused by irregularly spaced LIDAR measurements. To reconstruct 3D building models, the raw 2D topology of each building is first extracted and then further adjusted. Since the adjusting operations for simple building models do not work well on 2D topology, 2D snake algorithm is proposed to adjust 2D topology. The 2D snake algorithm consists of newly defined energy functions for topology adjusting and a linear algorithm to find the minimal energy value of 2D snake problems. Data sets from urbanized areas including large institutional, commercial, and small residential buildings were employed to test the proposed framework. The results demonstrated that the proposed framework achieves a very good performance. ^

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The purpose of this research is design considerations for environmental monitoring platforms for the detection of hazardous materials using System-on-a-Chip (SoC) design. Design considerations focus on improving key areas such as: (1) sampling methodology; (2) context awareness; and (3) sensor placement. These design considerations for environmental monitoring platforms using wireless sensor networks (WSN) is applied to the detection of methylmercury (MeHg) and environmental parameters affecting its formation (methylation) and deformation (demethylation). ^ The sampling methodology investigates a proof-of-concept for the monitoring of MeHg using three primary components: (1) chemical derivatization; (2) preconcentration using the purge-and-trap (P&T) method; and (3) sensing using Quartz Crystal Microbalance (QCM) sensors. This study focuses on the measurement of inorganic mercury (Hg) (e.g., Hg2+) and applies lessons learned to organic Hg (e.g., MeHg) detection. ^ Context awareness of a WSN and sampling strategies is enhanced by using spatial analysis techniques, namely geostatistical analysis (i.e., classical variography and ordinary point kriging), to help predict the phenomena of interest in unmonitored locations (i.e., locations without sensors). This aids in making more informed decisions on control of the WSN (e.g., communications strategy, power management, resource allocation, sampling rate and strategy, etc.). This methodology improves the precision of controllability by adding potentially significant information of unmonitored locations.^ There are two types of sensors that are investigated in this study for near-optimal placement in a WSN: (1) environmental (e.g., humidity, moisture, temperature, etc.) and (2) visual (e.g., camera) sensors. The near-optimal placement of environmental sensors is found utilizing a strategy which minimizes the variance of spatial analysis based on randomly chosen points representing the sensor locations. Spatial analysis is employed using geostatistical analysis and optimization occurs with Monte Carlo analysis. Visual sensor placement is accomplished for omnidirectional cameras operating in a WSN using an optimal placement metric (OPM) which is calculated for each grid point based on line-of-site (LOS) in a defined number of directions where known obstacles are taken into consideration. Optimal areas of camera placement are determined based on areas generating the largest OPMs. Statistical analysis is examined by using Monte Carlo analysis with varying number of obstacles and cameras in a defined space. ^