Thesis (Sc.D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1981. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Includes bibliographical references. / by Edward Yik Chow. / Sc.D.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1979. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Bibliography: leaf 73. / by Oliver Chukwudi Ibe. / M.S.

Depuis le développement du capitalisme, la nécessité de créer un droit des groupes est apparue. Cette nécessité est corroborée par le fait qu’aujourd’hui, un salarié sur deux appartient à un groupe de sociétés. De plus, à l’aune de la mondialisation du contexte économique, le nombre de licenciements ne cesse d’augmenter. Certains groupes ont besoin de licencier pour sauvegarder leur santé économique, tandis que d’autres souhaitent prospérer. Ces derniers vont même jusqu’à l’abandon de leur filiale pour augmenter leur profit. Le législateur a institué une procédure de licenciement économique, applicable au groupe de sociétés, qui participe à une prévention des licenciements. Parallèlement, il a construit peu à peu un droit applicable à ce dernier dans le cadre d’une procédure individuelle et collective. Il a institué d’une part, l’obligation de rapatriement des salariés mis à disposition d’une filiale étrangère et, d’autre part, l’obligation de constituer un comité de groupe. Enfin, le groupe est tenu de contribuer à l’élaboration du plan de sauvegarde de l’emploi de ses filiales en fonction de ses moyens. Par ailleurs, l’existence d’un véritable droit des groupes dans le cadre d’une procédure de licenciement économique est confirmée par la position de la jurisprudence. En effet, le juge social est intervenu activement pour construire ce droit des groupes de sociétés. Tout d’abord, il a dégagé une obligation de reclassement élargie au groupe participant à l’édification de ce droit spécifique. Puis, la Chambre sociale a souhaité imputer une responsabilité au groupe en qualifiant la société donneuse d’ordre de coemployeur, ce qui permet de sanctionner le groupe de manière adaptée. Il existe donc un droit des groupes dans le cadre de la procédure des licenciements économiques participant à leur prévention, et intervenant lors dans leur mise en œuvre. / Since the development of capitalism, the need for a right groups appeared. This need is reinforced by the fact that today one in two employees belongs to a group of companies. Furthermore, in the globalization of the economy’s process, the number of redundancies is increasing ceaselessly. Some groups have to fire to save their economic health, while others wish to prosper. These ones will even give up their subsidiary to increase their profits.The legislator introduced a redundancy procedure applicable to the group of companies which one participating in a prevention of layoffs. Meanwhile, he gradually legislate a law applicable in case of an individual and collective process. He established, the one hand, the obligation to repatriate the employees provide to a foreign subsidiary and, secondly, the requirement to establish a group committee. Finally, the Group is required to elaborate a conservation plan for the use of its subsidiaries within its meansMoreover, the existence of a real law for the groups as part of a redundancy procedure is confirmed by the position of jurisprudence and legal precedents. Indeed, the social judge intervened actively to create a legal framework for this corporate group. First, he cleared an enlarged reclassification obligation to the group participating in the building of this specific duty. Then, the Social court wished to impute responsibility to the group by calling the donor company coemployeur order, allowing the group to be punish suitably.There is therefore a right for the groups within the framework of the procedure involved in redundancies prevention and intervening in their implementation.

abstract: Advances in semiconductor technology have brought computer-based systems intovirtually all aspects of human life. This unprecedented integration of semiconductor based systems in our lives has significantly increased the domain and the number of safety-critical applications – application with unacceptable consequences of failure. Software-level error resilience schemes are attractive because they can provide commercial-off-the-shelf microprocessors with adaptive and scalable reliability. Among all software-level error resilience solutions, in-application instruction replication based approaches have been widely used and are deemed to be the most effective. However, existing instruction-based replication schemes only protect some part of computations i.e. arithmetic and logical instructions and leave the rest as unprotected. To improve the efficacy of instruction-level redundancy-based approaches, we developed several error detection and error correction schemes. nZDC (near Zero silent Data Corruption) is an instruction duplication scheme which protects the execution of whole application. Rather than detecting errors on register operands of memory and control flow operations, nZDC checks the results of such operations. nZDC en sures the correct execution of memory write instruction by reloading stored value and checking it against redundantly computed value. nZDC also introduces a novel control flow checking mechanism which replicates compare and branch instructions and detects both wrong direction branches as well as unwanted jumps. Fault injection experiments show that nZDC can improve the error coverage of the state-of-the-art schemes by more than 10x, without incurring any more performance penalty. Further more, we introduced two error recovery solutions. InCheck is our backward recovery solution which makes light-weighted error-free checkpoints at the basic block granularity. In the case of error, InCheck reverts the program execution to the beginning of last executed basic block and resumes the execution by the aid of preserved in formation. NEMESIS is our forward recovery scheme which runs three versions of computation and detects errors by checking the results of all memory write and branch operations. In the case of a mismatch, NEMESIS diagnosis routine decides if the error is recoverable. If yes, NEMESIS recovery routine reverts the effect of error from the program state and resumes program normal execution from the error detection point. / Dissertation/Thesis / Doctoral Dissertation Computer Engineering 2018

Com a grande demanda por derivados da cana-de-açúcar no Brasil a expansão de área para produção, assim como o aumento da produtividade tem sido foco para áreas agrícolas na região centro-sul. Portanto áreas que anteriormente eram dedicadas a pastagem estão tornando-se cultivo de cana-de-açúcar. Essa mudança está ocorrendo com uma grande rapidez e por esse motivo preocupações com a sustentabilidade do solo estão sendo levantadas. O objetivo deste trabalho foi verificar como a atual mudança de uso da terra de pastagem para cultivo de canade- açúcar impacta atributos microbiológicos quantitativos e funcionais do solo em um transecto edafoclimático na região centro-sul do Brasil tendo a vegetação nativa como referência. Para isso foram feitas análises do carbono e nitrogênio da biomassa microbiana do solo segundo Vance, Brookes e Jenkinson (1987) e análises da atividade enzimática da β-glicosidase, fosfatase ácida e alcalina segundo Tabatabai (1994). Verifica-se a tendência de reduzir a fertilidade na pastagem em relação a mata nativa e posteriormente aumentar com o uso de fertilizantes na cana-de-açúcar. O estoque de C tem um menor valor na pastagem quando não manejada em Lat S 17º, diminui na sequencia de mudança dos sistemas de uso da terra em Lat S 21º, porém uma recuperação na mudança para cultivo de cana-de-açúcar e é maior em Lat S 23º quando a textura do solo é mais argilosa. Existe uma diminuição do estoque de CBM das matas nativas para as pastagens e um aumento nos cultivos de cana-de-açúcar em Lat S 17º e Lat S 21º. Em Lat S 23º a pastagem apresenta maior CBM do que os outros sistemas de uso da terra. Nos locais de estudo a menor relação CBM/C Total foi de 2,54% na mata nativa em Lat S 17º e a maior de 5,74% na pastagem de Lat S 23º. O N é um elemento muito sensível, em todos os atributos analisados a mudança de uso da terra causou uma grande diminuição, e a degradação do solo é o fator que causa o grande impacto nesses atributos. A textura argilosa do solo garante maior atividade enzimática, porém em cultivos de cana-de-açúcar a atividade diminui independente da classe textural. Os mesmos usos da terra em diferentes locais não podem ser analisados como repetições. Sendo assim pode-se concluir que nos casos analisados o impacto da mudança de uso da terra de pastagem para cultivo de cana-de-açúcar se manifestou de forma diferente em cada local, não permitindo uma generalização. / The great demand for derivatives of sugarcane in Brazil is the motive for the area expansion for production as well as the increase of productivity have been the focus of agricultural areas in the center-south region. So areas that were previously pastures have been changing for sugarcane cultivation. This change has occured with great speed and therefore concerns about the sustainability of soil have been raised. The aim of this study was to determine how the current change from pasture to sugarcane cultivation impacts quantitative and functional microbiological attributes of soil in a soil climatic zone in the central-south region of Brazil considering the native vegetation as reference. For it were made analysis of soil microbial biomass carbon and nitrogen according to Vance, Brookes and Jenkinson (1987) and analysis of enzymatic activity of β-glucosidase, acid and alkaline phosphatase according to Tabatabai (1994). There is a tendency to reduce fertility in pasture compared to native vegetation and then increase with the use of fertilizers in sugarcane cultivation. The stock of C has a lower value in the pasture when there is no fertilizers in Lat S 17º, decreases in the land use change in Lat S 21º, but there is a recovery in the switch over to sugarcane cultivation and it is the biggest in Lat S 23º when the soil texture is clayey. There is a decrease in the stock of CBM from native forests to pastures and an increase in sugarcane cultivation in Lat S 17º and Lat S 21º. In Lat S 23º the pasture has higher CBM stock than other land use systems. In the study sites the reason between CBM and C Total was 2.54% in the native vegetation in Lat S 17º and the highest 5.74% in the pasture of Lat S 23º. The N is a very sensitive element, in all attributes analyzed, the land use change caused a large decrease, and soil degradation is the factor that causes serious impact on those attributes. The clayey soil ensures greater enzymatic activity, but in sugarcane cultivation decreases the activity independent of the texture. The same land uses in different locations can\'t be analyzed as repetitions. Therefore in the cases analyzed the impact of the change from pasture to sugarcane cultivation was differently in each place, not allowing a generalization.

Physical and cognitive disabilities make it difficult or impossible to perform simple personal or job-related tasks. The primary objective of this research and development effort is to assist persons with physical disabilities to perform activities of daily living (ADL) using a smart 9-degrees-of-freedom (DOF) modular wheelchair-mounted robotic arm system (WMRA). The combination of the wheelchair's 2-DoF mobility control and the robotic arm's 7-DoF manipulation control in a single control mechanism allows people with disabilities to do many activities of daily living (ADL) tasks that are otherwise hard or impossible to accomplish. Different optimization methods for redundancy resolution are explored and modified to fit the new system with combined mobility and manipulation control and to accomplish singularity and obstacle avoidance as well as other optimization criteria to be implemented on the new system. The resulting control algorithm of the system is tested in simulation using C++ and Matlab codes to resolve any issues that might occur during the testing on the physical system. Implementation of the combined control is done on the newly designed robotic arm mounted on a modified power wheelchair and with a custom designed gripper. The user interface is designed to be modular to accommodate any user preference, including a haptic device with force sensing capability, a spaceball, a joystick, a keypad, a touch screen, head/foot switches, sip and puff devices, and the BCI 2000 that reads the electromagnetic pulses coming out of certain areas of the brain and converting them to control signals after conditioning. Different sensors (such as a camera, proximity sensors, a laser range finder, a force/torque sensor) can be mounted on the WMRA system for feedback and intelligent control. The user should be able to control the WMRA system autonomously or using teleoperation. Wireless Bluetooth technology is used for remote teleoperation in case the user is not on the wheelchair. Pre-set activities of daily living tasks are programmed for easy and semi-autonomous execution.

The rapid developments in the sensor and its related technology have made automation possible in many processes in diverse fields. Also sensor-based fault diagnosis and quality improvements have been made possible. These tasks depend highly on the sensor network for the accurate measurements. The two major problems that affect the reliability of the sensor system/network are sensor failures and sensor anomalies. The usage of redundant sensors offers some tolerance against these two problems. Hence the redundancy analysis of the sensor system is essential in order to clearly know the robustness of the system against these two problems. The degree of sensor redundancy defined in this thesis is closely tied with the fault-tolerance of the sensor network and can be viewed as a parameter related to the effectiveness of the sensor system design. In this thesis, an efficient algorithm to determine the degree of sensor redundancy for linear sensor systems is developed. First the redundancy structure is linked with the matroid structure, developed from the design matrix, using the matroid theory. The matroid problem equivalent to the degree of sensor redundancy is developed and the mathematical formulation for it is established. The solution is obtained by solving a series of l1-norm minimization problems. For many problems tested, the proposed algorithm is more efficient than other known alternatives such as basic exhaustive search and bound and decomposition method. The proposed algorithm is tested on problem instances from the literature and wide range of simulated problems. The results show that the algorithm determines the degree of redundancy more accurately when the design matrix is dense than when it is sparse. The algorithm provided accurate results for most problems in relatively short computation times.

Recent advances in Micro-Electro-Mechanical Systems (MEMS) and low-power short-range radios have enabled rapid development of wireless sensor networks. Future sensor networks are anticipated to include hundreds or thousands of these devices in many applications, such as capturing multimedia content for surveillance, structural health monitoring, tracking of accidental chemical leaks, machine failures, earthquakes and intrusion detection. With the increase of sensor applications, a number of challenging problems related to the network protocol design has emerged - the most important ones relating to energy efficiency and lifetime maximisation. Techniques devised for sensor networks should deal with a large number of sensors distributed in the field. Wireless sensor nodes are deployed with limited energy reserves, so the networks should operate with minimum energy overhead. In fact, the network should take into account not only individual node's energy efficiency but also consider the global picture, because surviving nodes' energy reserves in a failed network are wasted energy. This thesis examines a node organisation technique to deal with the above challenges. The focus is on improving network lifetime via organising the nodes in a distributed and energy efficient manner. The main goal is lowering wasted energy via energy balancing and exploiting node redundancy in case of node failure. In particular, this thesis proposes Energy Balanced Clustering (EBC) method for node self-organisation where network tasks (such as data aggregation and data forwarding) are shifted to high-energy neighbours to reduce the energy consumption of low energy nodes. After showing how to extend network lifetime by energy balanced node organisation, the effect of redundant node deployments on network lifetime is addressed. Redundant nodes consume energy by performing unnecessary tasks so a method called Self-Calculated Redundancy Check (SCRC) is proposed to deactivate redundant nodes. A deactivated redundant node can be used as a replacement for a failed node. The Asynchronous Failed Sensor node Detection (AFSD) proposed in this thesis uses the data packets exchanged between neighbours to identify failed neighbours. To restore coverage for network holes caused by failed nodes, policies are given for re-activating redundant nodes. Detailed analytical analysis and simulation of the proposed methods demonstrate that by taking into account energy balancing, eliminating redundant tasks and replacing failed nodes sensor network lifetime can significantly be improved.

<p>This master thesis has been done at Enea Epact AB. The purpose of this thesis is to develop and implement a Link Quality Control algorithm for GPRS/EPGRS in the current testing tool. A Link Quality Control (LQC) shall take quality values from mobile stations and base stations and decide a codingsscheme that opimizes the throughput of data. </p><p>The Advantage with LQC is that it adapts the used coding scheme to the channel quality. If the channel quality is too bad for the used coding scheme, a slower coding scheme with more redundancy should be selected. On the other hand, if the channel quality is too good for the used coding scheme, LQC should recommend a faster coding scheme with less redundancy. </p><p>The testing tool is now using a static coding schme that doesn’t change during a data session. An LQC is therefore necessary for better simulation of the traffic and to make the tests more real.</p>

<p>Many of the earth’s ecosystems are experiencing large species losses due to human impacts such as habitat destruction and fragmentation, climate change, species invasions, pollution, and overfishing. Due to the complex interactions between species in food webs the extinction of one species could lead to a cascade of further extinctions and hence cause dramatic changes in species composition and ecosystem processes. The complexity of ecological systems makes it difficult to study them empirically. The systems often consist of large species numbers with lots of interactions between species. Investigating ecological communities within a theoretical approach, using mathematical models and computer simulations, is an alternative or a complement to experimental studies. This thesis is a collection of theoretical studies. We use model food webs in order to explore how biodiversity (species number) affects the response of communities to species loss (Paper I-III) and to environmental variability (Paper IV).</p><p>In paper I and II we investigate the risk of secondary extinctions following deletion of one species. It is shown that resistance against additional species extinctions increases with redundancy (number of species per functional group) (Paper I) in the absence of competition between basal species but decreases with redundancy in the presence of competition between basal species (Paper II). It is further shown that food webs with low redundancy run the risk of losing a greater proportion of species following a species deletion in a deterministic environment but when demographic stochasticity is included the benefits of redundancy are largely lost (Paper II). This finding implies that in the construction of nature reserves the advantages of redundancy for conservation of communities may be lost if the reserves are small in size. Additionally, food webs show higher risks of further extinctions after the loss of basal species and herbivores than after the loss of top predators (Paper I and II).</p><p>Secondary extinctions caused by a primary extinction and mediated through direct and indirect effects, are likely to occur with a time delay since the manifestation of indirect effects can take long time to appear. In paper III we show that the loss of a top predator leads to a significantly earlier onset of secondary extinctions in model communities than does the loss of a species from other trophic levels. If local secondary extinctions occur early they are less likely to be balanced by immigration of species from local communities nearby implying that secondary extinctions caused by the loss of top predators are less likely to be balanced by dispersal than secondary extinctions caused by the loss of other species. As top predators are vulnerable to human-induced disturbances on ecosystems in the first place, our results suggest that conservation of top predators should be a priority. Moreover, in most cases time to secondary extinction is shown to increase with species richness indicating the decay of ecological communities to be slower in species-rich than in species-poor communities.</p><p>Apart from the human-induced disturbances that often force species towards extinction the environment is also, to a smaller or larger extent, varying over time in a natural way. Such environmental stochasticity influences the dynamics of populations. In paper IV we compare the responses of food webs of different sizes to environmental stochasticity. Species-rich webs are found to be more sensitive to environmental stochasticity. Particularly, species-rich webs lose a greater proportion of species than species-poor webs and they also begin losing species faster than species-poor webs. However, once one species is lost time to final extinction is longer in species-rich webs than in species-poor webs. We also find that the results differ depending on whether species respond similarly to environmental fluctuations or whether they are totally uncorrelated in their response. For a given species richness, communities with uncorrelated species responses run a considerable higher risk of losing a fixed proportion of species compared with communities with correlated species responses.</p>