Дисертації з теми "Passive protection systems"

Requirements determination is a critical driver in a successful software development process. Despite decades of research prescribing various software development methodologies, intended to aid in achieving an eventual convergence between the user’s mental models and an informationally equivalent representation that is codified within an information system, we can still attribute many of the deficiencies in software development projects to the improper or ineffective execution of the requirements determination process. This study draws on the user resistance, software development, and psychology literature to discuss how perceived threats by potential users and key respondents can result in sub-optimization of a proposed information system via reduction in the quality of their responses during the requirements gathering phase. A laboratory experiment was carried out to explore the sources and effects of various threat perceptions and the effectiveness of techniques intended to detect and mitigate such perceptions of threat. The results confirm that perception of threat does lead to a degradation in response quality, with perceived adaptability fully mediating the relationship. The findings on whether interviewer reassurance has a moderating effect on the relationship between threat and perceived adaptability had interesting results, which are discussed.

The ever increasing demands of Internet users caused by the introduction of new high bandwidth applications and online services as well as the growing number of users and devices connected to the Internet, bring many challenges for the operators, especially in the last mile section of the network. Next generation access architectures are expected to offer high sustainable bandwidth per user. They also need to support a much larger service areas to decrease number of current central offices and hence potentially save the network expenditures in the future. Obviously, it requires high capacity and low loss transmission and optical fiber technology is the only future proof candidates for broadband access. Although this technology has already been widely deployed in the core networks, it is hard to use the same expensive devices made for core segment to solve the last mile bottlenecks, due to the low number of users sharing the network resources (and deployment cost). Therefore, the next generation optical access (NGOA) networks need to be designed with consideration of cost efficiency in the first place.   Network reliability is also turning to be an important aspect for the NGOA networks as a consequence of long reach, high client count and new services requiring uninterrupted access. Consequently, new architectures not only need to be cost efficient but also they should fulfill the increasing reliability requirements.   Although several NGOA alternatives have been proposed in the literatures, there is not yet an agreement on a single architecture. As described earlier, network expenditure and reliability performance are the two main factors to be considered. Therefore, this thesis concentrates on finding a suitable alternative for future broadband access by evaluating the reliability performance and total cost of ownership for several NGOA candidates. In particular, in this thesis we analyze the tradeoff between the cost needed to deploy backup resources and the reliability performance improvement obtained by the provided survivability mechanism.   First, we identified the suitable NGOA candidates by comparing two main groups of optical access networks, namely passive optical networks (PONs) and active optical networks (AONs), in terms of cost, reliability performance and power consumption. The initial results have shown that wavelength division multiplexing PON (WDM PON) is the most promising alternative for the NGOA networks because of its high potential capacity, low cost and power consumption. So we continued our studies by investigating two WDM-based PON architectures regarding their cost and reliability performance. The study has also included a proposed fiber layout compatible with these two candidates aiming to minimize the required investment needed to offer protection. Our primary results confirmed that hybrid PON (HPON) is the best alternative for the NGOA networks. Therefore we further analyzed this candidate considering several variants of HPON. The most important components and sections of the HPON, which need to be protected to decrease the impact of each failure in the network have been identified. Based on these outcomes, two resilience architectures protecting the shared part of the HPON were proposed and their reliability performance parameters as well as cost of protection were evaluated. According to the results, using our proposed protection schemes a considerable improvement in reliability performance of the HPON variants can be provided at minor extra investment. We also introduced a cost efficient HPON architecture with different levels of protection for users with various reliability requirements, i.e. the protection of shared parts of the access network for all the connected users and end-to-end resilience scheme for some selected ones (e.g., business users). To gain an overall view on the cost efficiency of the proposed architecture, we evaluated the investment required for deploying these schemes considering several network upgrading paths towards a protected network. Moreover, a sensitivity analysis investigating the influence of network deployments time and the density of the users with higher availability requirements was presented.   In summary, we have shown that HPON is able to fulfill the main NGOA requirements such as high bandwidth per-user, large coverage and client count. The work carried out in the thesis has proved that HPON can also offer high reliability performance while keeping the network expenditures at an acceptable level. Moreover, low power consumption and high flexibility in resource allocation of this architecture, makes it a winning candidate for the NGOA networks. Therefore, HPON is a promising architecture to be deployed as NGOA network in the near future considering the fact that components are soon to be available in the market.

QC 20130530

FP7 EU project, Optical Access Seamless Evolution(OASE)

There is a relationship between inelastic deformation and energy dissipation in structures that are subjected to earthquake ground motions. Thus, if seismic energy dissipation can be achieved by means of a separate non-load bearing supplementary damping system, the load bearing structure can remain elastic with continuing serviceability following the design level earthquake. This research was carried out to investigate the advantages of using added damping in structures. The control system consists of passive friction dampers called ring spring dampers installed in the ground floor of the structure using a tendon to transmit the forces to the other parts of the structure. The ring springs dampers are friction devices consisting of inner and outer ring elements assembled to form a spring stack. External load applied to the spring produces sliding action across mating ring interfaces. The damping forces generated by the dampers and transferred in the supplemental system to the structure by the tendon and horizontal links oppose the internal loads. A four storey-two bay steel frame structure was used in the study. Experimental and analytical studies to investigate the effectiveness of a supplemental control system are presented. The model was subjected to a series of earthquake simulations on the shaking table in the Structural Laboratory of the Civil Engineering Department, at the University of Canterbury. The earthquake simulation tests have been performed on the structure both with and without the supplemental control system. The earthquake simulations were a series of gradually increasing intensity replications of two commonly used earthquake records. This thesis includes detailed description of the structural model, the supplemental control system, the ring springs dampers and the data obtained during the testing. Analyses were then carried out on a twelve storey framed structure to investigate the possible tendon arrangements and the size and type of dampers required to control the response of a real building. Guidelines for determining the appropriateness of including a supplemental damping system have been investigated. The main features of the supplemental control system adopted in this research are: • It is a passive control system with extreme reliability and having no dependence on external power sources to effect the control action. These power sources may not be available during a major earthquake. • Ring springs are steel friction devices capable of absorbing large amounts of input energy. No liquid leakage can occur and minimal maintenance is required for the ring spring dampers. • With a damper-tendon system, the distribution of the dampers throughout the structure is not so critical. Only one or two dampers are used to produce the damping forces needed, and forces are then transferred to the rest of the building by the tendon system. • It is a relatively inexpensive control system with a long useful life.

Un ilot non-intentionnel peut se former lorsque d’une petite partie du réseau est déconnectée du reste du système électrique, et continue pourtant de fonctionner à l’insu du gestionnaire de réseau en raison de la présence de générateurs locaux. Cet événement n’est pas voulu : le comportement des ilots n’est pas maitrisé, ce qui entraîne des risques potentiels pour les personnes et équipements électriques. L’ilotage non-intentionnel est un phénomène complexe et mal connu, aujourd’hui considéré comme rare, mais dont la probabilité d’apparition tend actuellement, a priori, à s’accroître progressivement. Cet accroissement est dû à l’effet conjugué de plusieurs phénomènes : premièrement, le développement des installations de production de petite et moyenne puissance, raccordées directement au réseau de distribution ; deuxièmement, l’élargissement des seuils de détection qui sont utilisés dans leurs protections de découplage ; et troisièmement, l’implémentation dans ces installations d’automatismes de régulation de puissance active et réactive. Dans ce contexte, la chaire industrielle Smartgrid d’Enedis a financé ces travaux de thèse afin de mieux caractériser ces phénomènes d’ilotage et d’améliorer leur détection.Afin d’atteindre ces objectifs, une première priorité de la thèse a été d’améliorer la compréhension des ilots non-intentionnels au travers d’une approche analytique. Celle-ci a notamment permis la résolution formelle d’un modèle simple capable d’expliquer le comportement en fréquence d’un îlot. Ces résolutions ont été enrichies par de nombreuses expérimentations en laboratoire et par des simulations numériques. Les modèles ont fait l’objet d’une étude bibliographique approfondie, notamment pour le choix des modèles de charge.Une seconde priorité de la thèse a été d’estimer l’efficacité des méthodes passives de détection d’ilotage au travers du calcul de la zone de non-détection (ZND). L'influence de plusieurs charges sur la ZND a été analysé, ce qui a permis d’améliorer la compréhension du phénomène complexe que sont les ilots non-intentionnels. L’efficacité des nouvelles protections anti-ilotage utilisant des seuils sur la dérivée en fréquence (ROCOF) a aussi fait l’objet d’évaluations approfondies. Enfin, les méthodes de calcul de ZND ont été améliorés par rapport aux méthodes préexistantes, ce qui a permis de radicalement améliorer l’estimation faite de l'impact des nouvelles régulations de puissance P(f) et Q(U)
Unintentional islands might appear when a subpart of the grid is disconnected from the power system and keeps working because of local generation. These events are unwanted: their behavior is not controlled and leads to potential risks for people and for electric equipment. Unintentional islanding is a complex phenomenon and badly understood. Nowadays it is considered to be rare, but a priori its occurrence probability is currently steadily increasing. This rising is the consequence of several phenomena: firstly, the development of distributed generation of small and average size directly connected to the distribution grid; secondly, the enlargement of frequency thresholds used by isolating protections; and thirdly, the implementation of power regulations of active and reactive power in the generation unit. Within this context, the Smart Grid chair of Enedis financed this PhD thesis in order to better characterize these islanding phenomena and to improve their detection.To achieve these targets, a first priority of the PhD was to improve the comprehension of unintentional islanding through symbolic calculation. This approach makes it possible to solve a simple model and to explain the evolution of the frequency during an island. These results are completed with several laboratory experiments and by numeric simulations. Models are designed based on a thorough bibliography, in particular for load modeling.A second priority of the PhD was to estimate the efficiency of anti-islanding protections through the computation of non-detection zone (NDZ). The impact of several loads on the NDZ is analyzed to improve the understanding of unintentional islanding, which is a complex phenomenon. The efficiency of new anti-islanding protections using thresholds on the rate of change of frequency (ROCOF) is also thoroughly evaluated. It is shown that the computation method used by the protection plays a key role. At last, the calculation methods of the NDZ is improved regarding previous methods. Among other things, it allows to radically change the estimations of the impact of new power regulations P(f) and Q(U)

L'objectif principal de la thèse est de proposer une méthode de recommandation prenant en compte la vie privée des utilisateurs ainsi que l'évolutivité du système. Pour atteindre cet objectif, une technique hybride basée sur le filtrage par contenu et le filtrage collaboratif est utilisée pour atteindre un modèle précis de recommandation, sous la pression des mécanismes visant à maintenir la vie privée des utilisateurs. Les contributions de la thèse sont trois : Tout d'abord, un modèle de filtrage collaboratif est défini en utilisant agent côté client qui interagit avec l'information sur les éléments, cette information est stockée du côté du système de recommandation. Ce modèle est augmenté d’un modèle hybride qui comprend une stratégie basée sur le filtrage par contenu. En utilisant un modèle de la connaissance basée sur des mots clés qui décrivent le domaine de l'article filtré, l'approche hybride augmente la performance de prédiction des modèles sans élever l’effort de calcul, dans un scenario du réglage de démarrage à froid. Finalement, certaines stratégies pour améliorer la protection de la vie privée du système de recommandation sont introduites : la génération de bruit aléatoire est utilisée pour limiter les conséquences éventuelles d'une attaque lorsque l'on observe en permanence l'interaction entre l'agent côté client et le serveur, et une stratégie basée sur la liste noire est utilisée pour s’abstenir de révéler au serveur des interactions avec des articles que l'utilisateur considère comme pouvant transgresser sa vie privée. L'utilisation du modèle hybride atténue l'impact négatif que ces stratégies provoquent sur la performance prédictive des recommandations
The main objective of this thesis is to propose a recommendation method that keeps in mind the privacy of users as well as the scalability of the system. To achieve this goal, an hybrid technique using content-based and collaborative filtering paradigms is used in order to attain an accurate model for recommendation, under the strain of mechanisms designed to keep user privacy, particularly designed to reduce the user exposure risk. The thesis contributions are threefold : First, a Collaborative Filtering model is defined by using client-side agent that interacts with public information about items kept on the recommender system side. Later, this model is extended into an hybrid approach for recommendation that includes a content-based strategy for content recommendation. Using a knowledge model based on keywords that describe the item domain, the hybrid approach increases the predictive performance of the models without much computational effort on the cold-start setting. Finally, some strategies to improve the recommender system's provided privacy are introduced: Random noise generation is used to limit the possible inferences an attacker can make when continually observing the interaction between the client-side agent and the server, and a blacklisted strategy is used to refrain the server from learning interactions that the user considers violate her privacy. The use of the hybrid model mitigates the negative impact these strategies cause on the predictive performance of the recommendations

Cette thèse analyse les tensions vécues et les négociations menées, au quotidien, par des jeunes diplômés, en prenant en compte leurs parcours de formation et le recours au RSA. Partant d’entretiens et de récits, la recherche porte sur les processus socio-biographiques, avec leurs nombreuses transformations identitaires et relationnelles. Une typologie des modes de vie a d’abord été construite pour décrire les multiples usages du RSA pratiqués au quotidien. Une analyse des parcours dans le dispositif a permis ensuite de saisir les manières dont ces jeunes renégociaient les usages du RSA avec leur entourage proche et avec les professionnels chargés de l'accompagnement des allocataires. Enfin cette thèse montre que le recours au RSA représente une expérience sociale marquante pour des jeunes diplômés, sortis de l'enseignement supérieur et confrontés à la précarité professionnelle, notamment dans la manière dont ils vivent leurs transitions sociales vers la vie adulte
This thesis analyzes the lived tensions and negotiations conducted on a daily basis by young graduates, taking into account their training program and the use of RSA. Starting with interviews and stories, research focuses on socio-biographical process, with their many identities and relational transformations. A typology of lifestyles was first constructed to describe the multiple uses of RSA practiced daily. An analysis of the course in the device was then used to grasp the ways in which these young renegotiating uses RSA with their entourage and the professionals responsible for the accompaniment of the beneficiaries. Finally, this thesis shows that the use of RSA represents a significant social experience for young graduates, out of higher education and faced with job insecurity, particularly in the way they live their social transitions to adulthood

Landfill leachate production is an unavoidable by-product of landfilling solid waste. Mitigation of the adverse environmental impacts of landfill leachate is required at all active and closed landfill sites. Since leachate production continues long after the landfill is closed and no longer generating revenue, management strategies including low-cost passive and naturalized landfill leachate treatment systems are ideal. The past practice of dumping solid waste into unused tracts of land has created many brownfield sites with uncontrolled discharges of leachate to the receiving environment. Belle Park in Kingston, Ontario is an example of such a site that has been reclaimed for recreational use. A seep management strategy, which included the installation of leachate extraction wells, has been implemented at the site. Passive treatment systems, a coastal fringe wetland and a phreatophyte plots, were installed to evaluate their effectiveness in conjunction with the leachate seep management. Modelling estimated that originally, the pumping wells decreased leachate discharge by 60%, and with the newer wells in 2007 the discharge was decreased by 75- 85%. In situ pilot-scale evaluations of treatments systems are required to ensure adequate treatment of the leachate. The Merrick Landfill in North Bay, Ontario currently captures leachate produced on site and is assessing the potential of a hybrid-passive landfill leachate treatment system. This design process started with bench-scale design and assessment of active pretreatment options, followed by an evaluation of passive and semi-passive treatment systems at the bench-scale (treating 2-3 L/day) at both room (24oC) and cold (2oC) ambient temperatures. The design process culminated with a pilot-scale assessment of hybrid-passive treatment systems (treating 2000 L/d). Assessment of flow in passive treatment system is usually conducted with tracer evaluations. Vertical-flow passive treatment systems with intermittent dosing of leachate for passive aeration have both saturated and unsaturated flow regions. This research shows that tracer evaluation of these types of system was insufficient to measure the clogging within the pore spaces. Therefore a time-lagged flux method was created, based on the pilot-scale hybrid passive treatment system at the Merrick Landfill. This analytical solution quantified the changes in saturated hydraulic conductivity in the treatment system cells.
Thesis (Ph.D, Civil Engineering) -- Queen's University, 2011-09-30 15:55:45.73

Yes
The performance of buried rigid pipes underneath geogrid-reinforced soil while applying incrementally increased cyclic loading was assessed using a fully instrumented laboratory rig. The influence of varying two parameters of practical importance was investigated; the pipe burial depth and the number of geogrid-layers. Measurements were taken for pipe deformation, footing settlement, strain in pipe and reinforcing layers, and pressure/soil stress on the pipe crown during various stages of cyclic loading. The research outcomes demonstrated a rapid increase in the rate of deformation of the pipe and the footing, and the rate of generated strain in the pipe and the geogrid-layers during the first 300 cycles. While applying further cycles, those rates were significantly decreased. Increasing the pipe burial depth and number of geogrid-layers resulted in reductions in the footing and the pipe deformations, the pressure on pipe crown, and the pipe strains. Redistribution of stresses, due to the inclusion of reinforcing layers, formed a confined zone surrounding the pipe providing it with additional lateral support. The pipe invert experienced a rebound, which was found to be dependent on pressure around the pipe and the degree of densification of the bedding layer. Data for strains measured in the geogrid-layers showed that despite the applied loading value and the pipe burial depth, the tensile strain in the lower geogrid-layer was usually higher than that measured in the upper layer.
The full-text of this article will be released for public view at the end of the publisher embargo on 5 Jun 2021.

碩士
東南科技大學
營建科技與防災研究所在職專班
102
Abstract Recently, economy and technology evolution continue booming all over the world. Modern intelligent buildings, shopping malls, power stations, Hi-Tech fabrication plants, and hospitals are designed and constructed one by one. All of them need a Data Center to support their daily operation for all the central/distributed control and/or intelligent automation works; it plays a role like the brain of each organization. one second of accidental shut down is not allowable because it may cause huge business loss or even human life impact. Thus, fire protection for the Data Center become one of the most important topics in the modern constructional engineering area. In the computer room, the computer/network is the major systems which have many supporting facilities such as power supply, air condition, and fire protection systems…etc are built to keep and to perform the major system work well and protection at all the time. But the fire/smoke attack which issues from the pipeline that travelling through rooms and buildings is still hard to be warranted and sometimes ignored, these finally become a leak in the fire protecting efforts. In general, Active Fire Protection facilities such as Fire Extinguisher、Sprinkler Systems are all carefully inspected item by item and are relative complete because they are requested by the rule of government fire protection agency, but for the Passive Fire Protection System related to partition plan, door material and pipeline draws relative less attention and is even ignored. The importance of the Data Center is doubtless, we also know its computer room is definitely the most critical area. For the Computer Room fire protection topic, this study explores Fire Compartment Strategy, Partition Wall Design, Fire-Proof door material, through Hole sealing、Fire Retarding and Smoke Blocking considerations, try to give a proposal which promotes the Passive Fire Protection level higher to get a long term stable fire protection environment for the computer room and the intelligent organizations.

This thesis is concerned with passive control systems for seismic protection of building structures, with special emphasis on elastomeric bearings, viscous dampers and tuned mass dampers. Both mathematical modeling and earthquake response analysis techniques are presented for this class of problems. Earthquake response simulations are carried out for a six-story L-shaped building equipped with these protective systems and subjected to three real earthquake ground excitations, namely the El Centro 1940, Orion Blvd 1971 and Capitola 1989 earthquake records. Both deterministic and stochastic earthquake ground excitations are considered. The performance and effectiveness of these passive protective systems are studied mainly in the time domain with some considerations of the frequency domain. Based on all analyses performed and for the particular building structure considered, it is found that base isolation is very effective in reducing the seismic structural response, especially if it exhibits a nonlinear hysteretic behavior, since in addition to decoupling the frame structure from the ground motion, it dissipates the earthquake input energy through hysteretic action. Tuned-mass damping is less effective than viscous damping in reducing the structural response to earthquake excitations. The results also show that the characteristics of the earthquake ground excitation represent a very important factor which influences the performance of the three passive earthquake protective systems studied herein, especially of the tuned-mass damper system.

Current seismic design practice promotes inelastic response in order to reduce the design forces. By allowing the structure to yield while increasing the ductility of the structure, the global forces can be kept within the limited bounds dictated by the yield strength. However, during severe earthquakes, the structures undergo significant inelastic deformations leading to stiffness and strength degradation, increased interstory drifts, and damage with residual drift. The research presented in this thesis has three components that seek to address these challenges. To prevent the inelastic effects observed in yielding systems, a new concept “apparent weakening” is proposed and verified through shake table studies in this thesis. “Apparent weakening” is introduced in the structural system using a complementary “adaptive negative stiffness device” (NSD) that mimics "yielding” of the global system thus attracting it away from the main structural system. Unlike the concept of weakening and damping, where the main structural system strength is reduced, the new system does not alter the original structural system, but produces effects compatible with an early yielding. Response reduction using NSD is achieved in a two step sequence. First the NSD, which is capable of exhibiting nonlinear elastic stiffness, is developed based on the properties of the structure. This NSD is added to the structure resulting in reduction of the stiffness of the structure and NSD assembly or “apparent weakening”-thereby resulting in the reduction of the base shear of the assembly. Then a passive damper, designed for the assembly to reduce the displacements that are caused due to the “apparent weakening”, is added to the structure-thereby reducing the base shear, acceleration and displacement in a two step process. The primary focus of this thesis is to analyze and experimentally verify the response reduction attributes of NSD in (a) elastic structural systems (b) yielding systems and (3) multistory structures. Experimental studies on 1:3 scale three-story frame structure have confirmed that consistent reductions in displacements, accelerations and base shear can be achieved in an elastic structure and bilinear inelastic structure by adding the NSD and viscous fluid damper. It has also been demonstrated that the stiffening in NSD will prevent the structure from collapsing. Analogous to the inelastic design, the acceleration and base shear and deformation of the structure and NSD assembly can be reduced by more than 20% for moderate ground motions and the collapse of structure can be prevented for severe ground motions. Simulation studies have been carried on an inelastic multistoried shear building to demonstrate the effectiveness of placing NSDs and dampers at multiple locations along the height of the building; referred to as “distributed isolation”. The results reported in this study have demonstrated that by placing a NSD in a particular story the superstructure above that story can be isolated from the effects of ground motion. Since the NSDs in the bottom floors will undergo large deformations, a generalized scheme to incorporate NSDs with different force deformation behavior in each storey is proposed. The properties of NSD are varied to minimize the localized inter-story deformation and distribute it evenly along the height of the building. Additionally, two semi-active approaches have also been proposed to improve the performance of NSD in yielding structures and also adapt to varying structure properties in real time. The second component of this thesis deals with development of a novel device to control the response of structural system using adaptive length pendulum smart tuned mass damper (ALP-STMD). A mechanism to achieve the variable pendulum length is developed using shape memory alloy wire actuator. ALP-STMD acts as a vibration absorber and since the length is tuned to match the instantaneous frequency, using a STFT algorithm, all the vibrations pertaining to the dominant frequency are absorbed. ALP-STMD is capable of absorbing all the energy pertaining to the tuned-frequency of the system; the performance is experimentally verified for forced vibration (stationary and non-stationary) and free vibration. The third component of this thesis covers the development of an adaptive control algorithm to compensate hysteresis in hysteretic systems. Hysteretic system with variable stiffness hysteresis is represented as a quasi-linear parameter varying (LPV) system and a gain scheduled controller is designed for the quasi-LPV system using linear matrix inequalities approach. Designed controller is scheduled based on two parameters: linear time-varying stiffness (slow varying parameter) and the stiffness of friction hysteresis (fast varying parameter). The effectiveness of the proposed controller is demonstrated through numerical studies by comparing the proposed controller with fixed robust H∞ controller. Superior tracking performance of the LPV-GS over the robust H∞ controller in different displacement ranges and various stiffness switching cases is clearly evident from the results presented in this thesis. The LPV-GS controller is capable of adapting to the parameter changes and is effective over the entire range of parameter variations.