Compute-and-Forward on a Multi-User Multi-Relay Channel

In this paper, we consider a system in which multiple users communicate with a destination with the help of multiple half-duplex relays. Based on the compute-and-forward scheme, each relay, instead of decoding the users' messages, decodes an integer-valued linear combination that relates the transmitted messages. Then, it forwards the linear combination towards the destination. Given these linear combinations, the destination may or may not recover the transmitted messages since the linear combinations are not always full rank. Therefore, we propose an algorithm where we optimize the precoding factor at the users such that the probability that the equations are full rank is increased and that the transmission rate is maximized. We show, through some numerical examples, the effectiveness of our algorithm and the advantage of performing precoding allocation at the users. Also, we show that this scheme can outperform standard relaying techniques in certain regimes

Evaluation, Modeling and Optimization of Coverage Enhancement Methods of NB-IoT

Narrowband Internet of Things (NB-IoT) is a new Low Power Wide Area Network (LPWAN) technology released by 3GPP. The primary goals of NB-IoT are improved coverage, massive capacity, low cost, and long battery life. In order to improve coverage, NB-IoT has promising solutions, such as increasing transmission repetitions, decreasing bandwidth, and adapting the Modulation and Coding Scheme (MCS). In this paper, we present an implementation of coverage enhancement features of NB-IoT in NS-3, an end-to-end network simulator. The resource allocation and link adaptation in NS-3 are modified to comply with the new features of NB-IoT. Using the developed simulation framework, the influence of the new features on network reliability and latency is evaluated. Furthermore, an optimal hybrid link adaptation strategy based on all three features is proposed. To achieve this, we formulate an optimization problem that has an objective function based on latency, and constraint based on the Signal to Noise Ratio (SNR). Then, we propose several algorithms to minimize latency and compare them with respect to accuracy and speed. The best hybrid solution is chosen and implemented in the NS-3 simulator by which the latency formulation is verified. The numerical results show that the proposed optimization algorithm for hybrid link adaptation is eight times faster than the exhaustive search approach and yields similar latency

The Ancient\u27s View of the Poet and Poetry

The poet’s position in society has always been much discussed throughout the ages and inall civilizations.Thus the poet is accepted and receives praise sometimes, but is rejected and banished from society at other times. The poet\u27s oscillation between these two extremes has always existed and will exist, it seems, as long as there is poetry. However, these two contradictory attitudes towards the Poet and Poetry have never received complete consensus from the different classes of society. The absence of this agreement, no doubt, denotes the necessity of the poet\u27s voice for some and its danger fo rothers

Stable recovery of a non-compactly supported coefficient of a Schr\"odinger equation on an infinite waveguide

We study the stability issue for the inverse problem of determining a coefficient appearing in a Schr\"odinger equation defined on an infinite cylindrical waveguide. More precisely, we prove the stable recovery of some general class of non-compactly and non periodic coefficients appearing in an unbounded cylindrical domain. We consider both results of stability from full and partial boundary measurements associated with the so called Dirichlet-to-Neumann map. To the best of our knowledge, our results are the first results of stable recovery of such class of coefficients for an elliptic equation in an unbounded domain

Optimization of Columnar NoSQL Data Warehouse Model with Clarans Clustering Algorithm

In order to perfectly meet the needs of business leaders, decision-makers have resorted to the integration of external sources (such as Linked Open Data) in the decision-making system in order to enrich their existing data warehouses with new concepts contributing to bring added value to their organizations, enhance its productivity and retain its customers. However, the traditional data warehouse environment is not suitable to support external Big Data. To deal with this new challenge, several researches are oriented towards the direct conversion of classical relational data warehouse to a columnar NoSQL data warehouse, whereas the existing advanced works based on clustering algorithms are very limited and have several shortcomings. In this context, our paper proposes a new solution that conceives an optimized columnar data warehouse based on CLARANS clustering algorithm that has proven its effectiveness in generating optimal column families. Experimental results improve the validity of our system by performing a detailed comparative study between the existing advanced approaches and our proposed optimized method

Analysis of the risks related to the logistics of the Hazardous Materials

Today, the number of industrial enterprises producing, using, storing and transporting hazardous materials is constantly increasing worldwide. This growth is linked to the progressive demand in various sectors, which makes our world riskier because of the nature and diversity of the dangerous events that may occur. The risks incurred by the hazardous materials transport activity, in case of the occurrence of an incident that may occur and have serious consequences for persons, the environment, property, a fire as an example accompanied by a release of toxic smoke, pollution of the soil and / or water, it can lead in case of non-control of the fire or the reactivity of the goods transported to an explosion. To this purpose, it is essential to protect the health and safety of personnel and to preserve the environment from any deterioration related to the risks incurred by the Transport of Dangerous Goods (TDG) business, which presents important issues for population, state and highly urbanized areas The aim of this thesis is to propose a systemic approach to risk assessment, taking into account in a global way the risks related to hazardous materials throughout the logistics chain (transport & storage). The approach consists of using the modeling and simulation techniques of an accident, to understand the consequences generated in the various scenarios in the event of the occurrence of a hazardous materials accident. This approach will allow the presentation of an industrial safety reasoning method based on actual case studies, rather than a detailed analysis of how to prevent and protect a given hazard. In the process of assessing the technological risks associated with the Transport of Dangerous Goods (TDG), the essential step is the evaluation of the risk intensity when an accidental event occurs, which is to quantify the risks involved. effects or impacts, in order to respond quickly and prioritize relief actions for the protection of the population and the environment. The assessment of the intensity of a technological risk can be carried out using an effects model, capable of estimating the effects induced by the hazardous phenomenon from a quantitative point of view, in order to determine the geographical area of the hazard where the intensity of the risk is deemed too high. In this context, the first issue addressed in this thesis is to assess the level of risk of hazardous goods transport areas for both road and marine modes of transportation, while the second issue of assessing risks in an industrial facility fixed

Travail et identités : la portée de l’impératif technologique. Une étude de cas

La dynamique de transformation de l’organisation du travail dans un contexte de changements technologiques et organisationnels dans une organisation industrielle de haute technologie a conduit à la fragmentation de la communauté technicienne et à la refonte de son identité professionnelle historique. Cette dynamique n’apparaît pas comme le résultat d’un quelconque déterminisme technologique. Les changements technologiques ont été, en dernière instance, un enjeu stratégique autour duquel se sont cristallisés les rapports de force dans l’organisation. Ils ont fait l’objet d’une instrumentalisation sur laquelle se sont appuyées les instances de l’entreprise pour légitimer leurs choix stratégiques en matière d’organisation du travail.The goal of this research is to study the impacts of technological changes on the professional identity of a specific category of workers: technicians. This research is based on a case study of a major high-tech organization working in the telecommunications sector. This group of “technical workers” establishes itself both as a key social actor and also as a professional category weakened by a deep identity malaise.This malaise itself can be attributed to its own specific social history and to the recent technological changes that have had a major impact on the production structures of its “natural” activity space. The study, carried out in a factory in a suburb west of Montreal, started just after the beginning of a complex process of technological and organizational change. The study has a dual goal. The first goal is to understand the dynamics of change brought about by these transformations, which have led to a new distribution of qualification spaces and a redefinition of negotiation powers for the members of the community. A second goal is to analyse the mechanisms which were in place for the remaking of the technician position and which make up the basis for the reconstruction of her social and professional identity. It is the deconstruction of this process which lies at the basis of this research which also set out to question the explanatory impact of the controversial notion of technological determinism as related to the recent transformations which have affected industrial work. The analysis model calls on three notions. The first notion is that the dynamics of the social work space within the enterprise set up a transformation process that leads to a structuring of new disqualification and requalification spaces. The second is that these dynamics are not the result of technological change alone; other factors much be taken into consideration in the redefinition of the technician’s identify and function. The third notion establishes a structural relation, of cause and effect, between the transformation process of the qualification spaces, their respective zones of uncertainty, and the technician identity through its technical, professional, and social components.The case study of this work sets up a constructivist and inductive approach, which takes the form of a long-term study, based on direct observation, personal conversations, and use of the organization’s documentary sources.The research results bring out two major phenomena. The first is the homogenization of the production space. The research is presented in two parts: first the bringing together of manufacturing operations into a single ad hoc space linked to the function rather than the product but in line with the same methods of task distribution; and thereafter, the definition of identical tasks, with the constraint of operation automation and equipment computerization. The second phenomenon is that of the fragmentation of the technician community. This is based on a transversal fracture of the technical population as a socioprofessional community and on the division of the technician’s function. The result of this phenomenon has been the disappearance of the largest of the sub-groups which previously made up the technician collective and which defined professional and collective identities; and the reconstitution of the community around two differentiated components: production technicians, and “specialized” technicians. The first group is by far the largest and includes, from this point in time on, operator technicians who have been greatly disqualified. Our results associate the second group with a redefined identify as a technician, a new collective group characterized by the appropriation of power spaces and technical means of authority, all of this to the detriment of both technical support (engineering) and hierarchical support (management).Each group draws its resources from the same formerly homogenous population for which the enterprise’s social space allowed a “long maturation period”—from the 1960’s—and an identity affirmation based on professional function and on a technical mastery which were institutionally recognized in the industrial space. This global transformation dynamic also led to the restructuration of the organization’s professional and social system.The results show that technological changes did not play an exclusive or overly developed role. The determinism attributed to the changes is, all things considered, relative when these are part of a complex dynamic with which other factors are associated, among which the enterprise’s strategy as an actor plays a decisive role. This is not because this role is more or less decisive than the dynamic stemming from technological changes, but rather because the former acts as a catalyst creating the conditions favourable to such an action. The technological changes appear, in the final analysis, as a strategic issue around which the power relations between different actors crystallized, particularly between technicians and leadership. Parallel to the irrefutable impacts of the “technical logic”, other strategic issues contributed to creating the social conditions for the institutional and collective action. The conduct and strategy of the leaders within the business are evident in a decisive manner at the very source of the main social transformations brought into focus by this study.This transformation dynamic cannot be seen as the sole result of some technological determinism, or of an unavoidable logic over which actors have no control. Research shows that technological changes are the focus of an instrumentalization as a contextual platform which leaders use as a basis to legitimize their strategic choices in the field of work organization.La dinámica de transformación de la organización del trabajo en un contexto de cambio tecnológico y organizacional, en una organización industrial de alta tecnología, ha conducido a la fragmentación de la comunidad de trabajadores tecnicos y a recomponer su identidad profesional histórica. Los cambios tecnológicos han sido, en última instancia, un desafío estratégico alrededor del cual se han cristalizado las correlaciones de fuerza en la organización. Esto ha sido objeto de una instrumentalización sobre la cual se apoyan las instancias empresariales para legitimar sus opciones estratégicas en materia de organización del trabajo