1,542 research outputs found

    Shortest Paths Routing Problem in MANETs

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    The need for communication services is rapidly increasing, because the mobile communication service is synonymous with an ideal communication style realizing communication anytime, anywhere and with anyone. The availability of a path depends on the number of links and the reliability of each link forming the path. Many routing metrics in terms of number of links have been proposed, such as the shortest path routing. Shortest path routing selects a path having minimum cost to forward the data to the destination node. Shortest path routing algorithm selection depends on direct traffic form source to destination, maximizing the network performance and minimizing the cost. Performance of the network can be enhanced through shortest path routing but it also depends upon the functionality of the routing protocol and the parameters that are selected for the shortest path routing. The primary goal of such an adhoc network routing protocol is correct and efficient route establishment between a pair of nodes so that messages may be delivered in a timely manner. Route construction should be done with a minimum of cost, overhead and bandwidth consumption. Some of researchers explored the concept of shortest path routing over ad hoc network. Each one uses his own parameters with different topology. No one uses all parameters. In this paper, we will discuss the solutions ideas that have been proposed by them

    FDI versus local industrial investment: a human capital perspective of development

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    This research looks at three automotive components\u27 factories in Egypt, equally benchmarked in all aspects, except for the nationality and nature of their ownership structure and their unique management arrangements and styles. One is totally foreign owned, but co-managed, the second is partly foreign owned, and managed, and the third is totally Egyptian-owned and managed. The study eventually, seeks to uncover the inner workings of the role of FDI vis-Ã -vis that of local industrial intellectual elite (progressive entrepreneurs), in conjunction with the pattern of intermittent reliance on foreign technical assistance. It probes the different ways these three different arrangement settings differ or converge in their agency for human capital accumulation, in the form of technical cultural and social expertise, while levering aspects of leadership and empowerment. â Way- backâ appointed employee samples, in each factory, are tested against their most recently appointed counterparts, for their level of accumulated technical, social and cultural expertise. The research incorporates a varied mix of tools of statistical analysis, where â a single case study with multiple embedded units study\u27 approach, including , theoretical and political-economic contextualization, all combine, in order to give a clearer picture of the situation of industrial modernity versus overall modernity against a contemporary discourse of global modernity

    Motor Neuron Disease

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    Compact modeling of multiple gate mos devices.

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    Aquesta tesi doctoral presenta models analítics electrostàtics i de transport de diferents tipus de transistors MOSFET de porta múltiple: Double-Gate (DG) MOSFET, Gate-All-Around MOSFETs i FinFETs.Les estructures de porta múltiple són les més adequades per aconseguir la miniaturització dels circuits CMOS per sota dels 50 nm de longitud de canal. La reducció del tamany implica més velocitat i més densitat de circuits a un xip, però també dóna lloc a problemes (efectes de canal curt) que empitjoren les prestacions dels transistors; aquests problemes es deuen a un control més deficient del canal per la porta, que causa un augment del corrent de fuites (degradant la relació on/off del corrent) i disminució de la resistència de sortida (degradant el guany). Amb les estructures de porta múltiple el control electrostàtic del canal per la porta augmenta considerablement i els efectes de canal curt es redueixen dràsticament.El disseny de circuits nanomètrics necessita models acurats dels dispositius MOS de porta múltiple. A més, els models han d'ésser analítics, de manera que els puguin utilitzar els simuladors de circuits, amb temps de simulació petits i sense problemes de convergencia.Aquesta tesi presenta models analítics dels transistors multi-gate MOSFETs, tant per al comportament electrostàtic com pels mecanismes de transport. L'electrostàtica ha estat modelada a partir de l'equació de Poisson en 2 o 3 dimensions. S'han desenvolupat tècniques per resoldre analíticament l'equació de Poisson. El fet de què els models es derivin d'una anàlisi bidimensional o tridimensional fa que els efectes de canal curt s'incloguin de manera física, sense paràmetres empírics. Els models analítics resultants s'han comparat amb simulacions numèriques bidimensionals i tridimensionals, i s'ha observat una concordància quasi perfecta fins als 20 nm de longitud de canal. En el cas del FinFET, a més, s'ha pogut realitzar una comparació amb mesures experimentals, que ha resultat bastant exitosa.Aquesta tesi està recolzada per un total 7 articles publicats o acceptats a revistes internacionals, i dos més d'enviats.En esta tesis hemos estudiado las características de los dispositivos MOSFET nodopados de puerta múltiple (multiple-gate MOSFETs), con dimensiones nanométricas.Hemos introducido modelos compactos de los efectos de canal corto (SCEs) para trestipos de dispositivos MOS de puerta múltiple (surrounding-gate MOSFET, double-gateMOSFET, y FinFET). Se han conseguido modelar los principales parámetros afectadospor los efectos de canal corto. Este trabajo supone un avance muy importante en el modelado de los nuevosdispositivos nanométricos MOS de puerta múltiple. Una buena prueba de ello es que lamayor parte de los resultados presentados en esta tesis se han publicado (o estánaceptados para publicación) en prestigiosas revistas internacionales y en actas decongresos internacionales de reconocido prestigio

    Encryption Efficiency Analysis and Security Evaluation of RC6 Block Cipher for Digital Images

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    This paper investigates the encryption efficiency of RC6 block cipher application to digital images, providing a new mathematical measure for encryption efficiency, which we will call the encryption quality instead of visual inspection, The encryption quality of RC6 block cipher is investigated among its several design parameters such as word size, number of rounds, and secret key length and the optimal choices for the best values of such design parameters are given. Also, the security analysis of RC6 block cipher for digital images is investigated from strict cryptographic viewpoint. The security estimations of RC6 block cipher for digital images against brute-force, statistical, and differential attacks are explored. Experiments are made to test the security of RC6 block cipher for digital images against all aforementioned types of attacks. Experiments and results verify and prove that RC6 block cipher is highly secure for real-time image encryption from cryptographic viewpoint. Thorough experimental tests are carried out with detailed analysis, demonstrating the high security of RC6 block cipher algorithm. So, RC6 block cipher can be considered to be a real-time secure symmetric encryption for digital images

    The Development of a Predictive Theory of Science Education Based Upon Information Processing Theory

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    This thesis describes the establishment of a new predictive theory for science education which can give direction to the improvement and transformation of science teaching at all levels. It is based upon Information Processing Theory. It has the ability to predict performance in science on the basis of independent psychological tests and to provide a framework for understanding how scientific learning takes place. The development of the theory has resulted from empirical work on 529 school pupils at "0" Grade (age 16) and on 440 Glasgow University students, through two series of experiments in addition to two confirmatory studies in the U.S.A. and Egypt. The first series related to students performance in individual questions, and the second related to students over-all performance in conventional examinations. Throughout this empirical work, a constant pattern has emerged showing that the students' holding-thinking space limited their ability to solve problems of different complexity. As soon as there was an overload on students' holding-thinking space, their performance fell away. In addition, the students' holding-thinking space is considered to be a good predictor for success in the conventional "0" Grade examinations, as well as the university examinations not only in chemistry, but also in physics, biology and mathematics. Where the theory and the empirical measurements have not agreed exactly, further investigation has been done to examine the disparities. In some cases new understanding has occurred which has allowed the theory to be modified. This thesis illustrates the importance of the teaching of learning strategies. In fact, it raises the teaching of strategies on to a par with the teaching of content. Three ways of successfully reducing the load on the students' holding-thinking space have been described and tested. The effect of the limitation of students' perceptual fields and of holding-thinking space on learning and problem solving tasks is also explored. The theory, which has been established in this thesis, answered some of the questions that educators have concerning students' limitations in learning and in problem solving. The outworking of this theory in terms of instructional methods, design of computer programs, books and laboratory experiences, is forming the basis of several follow-up studies

    Taxonomic revision of the cultivated species of Mimusops (Sapotaceae) in Egypt, with new records

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    During the process of updating horticultural records of this genus in Egypt, five problems were identified: lack of publications, lack of clarity between species, numerous errors of identifications, loss of earlier documented records of identity, as well as, the introduction and cultivation of new plants during the 19th Century added to the complexity of the problem. In this study, the taxonomic aspects of genus Mimusops, were thoroughly studied to identify the most reliable characters for taxon delimitation. Our assessment was based on morphological characters representing habit, leaves, petioles, flowering pedicels, buds, floral parts, fruit and seed. Fieldwork have revealed the presence of four species, of which Mimusops kummel and M. zeyheri are new records. The latter species is represented in Egypt by M. zeyheri var. laurifolia. This variety has been neglected by many authors. Additionally, Mimusops elengi L. was believed to be cultivated in Egypt, but no materials have been encountered that could confirm it. The specimens earlier identified as M. elengi actually belong either to M. kummel or to M. laurifolia. A detailed description of the genus and species with photographs, an identification key, and synonymy for each taxon are provided

    Metal sources for the Katanga Copperbelt deposits (DRC) insights from Sr and Nd isotope ratios

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    The ore deposits of the Central African Copperbelt formed during a multiphase mineralisation process. The basement underlying the Neoproterozoic Katanga Supergroup that hosts the ore, demonstrates the largest potential as metal source. Various ore deposits that formed during different mineralisation phases are taken as case studies, i.e. Kamoto, Luiswishi, Kambove West, Dikulushi and Kipushi (Democratic Republic of Congo, DRC). The Sr and Nd isotopic compositions of gangue carbonates associated with these deposits is determined and compared with those of rocks from several basement units, bordering or underlying the Copperbelt, to infer the metal sources. The mineralising fluid of diagenetic stratiform Cu-Co mineralisation interacted with felsic basement rocks underlying the region. The Co from these deposits is most likely derived from mafic rocks, but this is not observed in the isotopic signatures. Syn-orogenic, stratabound Cu-Co mineralisation resulted mainly from remobilisation of diagenetic sulphides. A limited, renewed contribution of metals from felsic basement rocks might be indicated by the isotope ratios in the western part of the Copperbelt, where the metamorphic grade is the lowest. The mineralising fluid of syn- and post-orogenic, vein-type mineralisations interacted with local mafic rocks, and with felsic basement or siliciclastic host rocks
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