344 research outputs found

    Organization of Multi-Agent Systems: An Overview

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    In complex, open, and heterogeneous environments, agents must be able to reorganize towards the most appropriate organizations to adapt unpredictable environment changes within Multi-Agent Systems (MAS). Types of reorganization can be seen from two different levels. The individual agents level (micro-level) in which an agent changes its behaviors and interactions with other agents to adapt its local environment. And the organizational level (macro-level) in which the whole system changes it structure by adding or removing agents. This chapter is dedicated to overview different aspects of what is called MAS Organization including its motivations, paradigms, models, and techniques adopted for statically or dynamically organizing agents in MAS.Comment: 12 page

    Spatial modulation schemes and modem architectures for millimeter wave radio systems

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    The rapid growth of wireless industry opens the door to several use cases such as internet of things and device-to-device communications, which require boosting the reliability and the spectral efficiency of the wireless access network, while reducing the energy consumption at the terminals. The vast spectrum available in millimeter-wave (mmWave) frequency band is one of the most promising candidates to achieve high-speed communications. However, the propagation of the radio signals at high carrier frequencies suffers from severe path-loss which reduces the coverage area. Fortunately, the small wavelengths of the mmWave signals allow packing a large number of antennas not only at the base station (BS) but also at the user terminal (UT). These massive antenna arrays can be exploited to attain high beamforming and combining gains and overcome the path-loss associated with the mmWave propagation. In conventional (fully digital) multiple-input-multiple-output (MIMO) transceivers, each antenna is connected to a specific radio-frequency (RF) chain and high resolution analog-to-digital-converter. Unfortunately, these devices are expensive and power hungry especially at mmWave frequency band and when operating in large bandwidths. Having this in mind, several MIMO transceiver architectures have been proposed with the purpose of reducing the hardware cost and the energy consumption. Fully connected hybrid analog and digital precoding schemes were proposed in with the aim of replacing some of the conventional RF chains by energy efficient analog devices. These fully connected mapping requires many analog devices that leads to non-negligible energy consumption. Partially connected hybrid architectures have been proposed to improve the energy efficiency of the fully connected transceivers by reducing the number of analog devices. Simplifying the transceiver’s architecture to reduce the power consumption results in a degradation of the attained spectral efficiency. In this PhD dissertation, we propose novel modulation schemes and massive MIMO transceiver design to combat the challenges at the mmWave cellular systems. The structure of the doctoral manuscript can be expressed as In Chapter 1, we introduce the transceiver design challenges at mmWave cellular communications. Then, we illustrate several state of the art architectures and highlight their limitations. After that, we propose scheme that attains high-energy efficiency and spectrum efficiency. In chapter 2, first, we mathematically describe the state of the art of the SM and highlight the main challenges with these schemes when applied at mmWave frequency band. In order to combat these challenges (for example, high cost and high power consumption), we propose novel SM schemes specifically designed for mmWave massive MIMO systems. After that, we explain how these schemes can be exploited in attaining energy efficient UT architecture. Finally, we present the channel model, systems assumptions and the transceiver devices power consumption models. In chapter 3, we consider single user SM system. First, we propose downlink (DL) receive SM (RSM) scheme where the UT can be implemented with single or multiple radio-frequency chains and the BS can be fully digital or hybrid architecture. Moreover, we consider different precoders at the BS and propose low complexity and efficient antenna selection schemes for narrowband and wideband transmissions. After that, we propose joint uplink-downlink SM scheme where we consider RSM in the DL and transmit SM (TSM) in the UL based on energy efficient hybrid UT architecture. In chapter 4, we extend the SM system to the multi-user case. Specifically, we develop joint multi-user power allocation, user selection and antenna selection algorithms for the broadcast and the multiple access channels. Chapter 5 is presented for concluding the thesis and proposing future research directions.Considerando los altos requerimientos de los servicios de nueva generación, las infraestructuras de red actual se han visto obligadas a evolucionar en la forma de manejar los diferentes recursos de red y computación. Con este fin, nuevas tecnologías han surgido para soportar las funcionalidades necesarias para esta evolución, significando también un gran cambio de paradigma en el diseño de arquitecturas para la futura implementación de redes.En este sentido, este documento de tesis doctoral presenta un análisis sobre estas tecnologías, enfocado en el caso de redes inter/intra Data Centre. Por consiguiente, la introducción de tecnologías basadas en redes ópticas ha sido estudiada, con el fin de identificar problemas actuales que puedan llegar a ser solucionados mediante el diseño y aplicación de nuevas técnicas, asimismo como a través del desarrollo o la extensión de los componentes de arquitectura de red.Con este propósito, se han definido una serie de propuestas relacionadas con aspectos cruciales, así como el control de dispositivos ópticos por SDN para habilitar el manejo de redes híbridas, la necesidad de definir un mecanismo de descubrimiento de topologías ópticas capaz de exponer información precisa, y el analizar las brechas existentes para la definición de una arquitectura común en fin de soportar las comunicaciones 5G.Para validar estas propuestas, se han presentado una serie de validaciones experimentales por medio de escenarios de prueba específicos, demostrando los avances en control, orquestación, virtualización y manejo de recursos con el fin de optimizar su utilización. Los resultados expuestos, además de corroborar la correcta operación de los métodos y componentes propuestos, abre el camino hacia nuevas formas de adaptar los actuales despliegues de red respecto a los desafíos definidos en el inicio de una nueva era de las telecomunicaciones.Postprint (published version

    On BCL-Algebra

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    It has been found that the BCL-algebra is more extensive class than BCK/BCI/BCH algebra. In this paper we study some properties of BCL-algebra of type (2,0) We also find deformation of such algebra and illustrate the connection between divisible algebra and deformation function

    Ketorolac Tromethamine In-situ Ocular Hydro Gel; Preparation, Characterization, and In-vivo Evaluation

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    The aim of this work is to formulate Ketorolac tromethamine in a new ocular in situ hydro gel delivery system. Two polymers; Chitosan and Carbopol 940 were used in different concentrations for the preparation of the in situ hydro gels, all formulations exposed to visual examination, pH measurement, in-vitro release, rheological study, stability study, and in-vivo anti-inflammatory effect study on the inflamed eye of rabbits. Results showed that all formulations were clear and showed pH within the acceptable range, Chitosan 0.5%w/v gives the highest release rate, all formulae exhibited pseudoplastic flow with a thixotropic behavior, stability study showed that rate of drug degradation followed first order kinetics and 0.5% Chitosan based formula showed longer shelf life (2.532 year), the percent of unhealed ulcers of the inflamed eye of rabbits was 17.5% for 0.5% Chitosan in situ hydro gel compared to 55% for Acular eye drop (positive control). Statistical analysis of the data revealed significance difference between the tested formula and control solution at p <0.05. So this system that combines the advantages of both solutions and gels, such as accuracy and facility of administration of the former and prolonged residence time of the latter, also enhances the healing rate of Ketorolac tromethamine in ulcerative rabbit's eye compared to ocular eye drops

    Achieving competitive advantage through the integration of disabled architects in architectural design firms in Egypt

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    The 2030 strategy of sustainable development in Egypt is based on integrated goals, including Human Resource Development. Egypt has ~9,540 disabled architects, who can play an important role in achieving competitive advantage through their integration in Architectural Design Firms (ADFs). By neglecting the benefits of integrating disabled architects, ADFs encounter the risk of losing unique skills and competent personnel. This article investigates the integration of disabled architects in ADFs as an approach for achieving competitive advantage. To achieve this aim, a research methodology consisting of literature review, case studies, and survey questionnaire has been adopted, and it is designed to achieve five objectives. First, literature review is used to investigate the concepts of disabilities and competitive advantage, as well as the relation between integrating disabled architects and the achievement of competitiveness in ADFs. Second, six case studies are presented and analyzed to investigate the role and process of achieving competitive advantage in ADFs through employing disabled architects. Third, the results of a survey questionnaire are analyzed to examine the perception regarding and application of employing disabled architects as an approach for achieving competitive advantage in ADFs in Egypt. Fourth, a framework is developed to facilitate the integration of disabled architects in ADFs with the goal of achieving competitive advantage. Finally, the research findings are summarized and recommendations are put forth. The value of this research stems from the need to address the issue of lack of employment of disabled architects in ADFs and the benefits of making better use of their unique capabilities and skills toward achieving competitiveness. In addition, this research covers a controversial topic that receives scant attention in construction literature, especially in Egypt

    Forecasting project schedule performance using probabilistic and deterministic models

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    AbstractEarned value management (EVM) was originally developed for cost management and has not widely been used for forecasting project duration. In addition, EVM based formulas for cost or schedule forecasting are still deterministic and do not provide any information about the range of possible outcomes and the probability of meeting the project objectives. The objective of this paper is to develop three models to forecast the estimated duration at completion. Two of these models are deterministic; earned value (EV) and earned schedule (ES) models. The third model is a probabilistic model and developed based on Kalman filter algorithm and earned schedule management. Hence, the accuracies of the EV, ES and Kalman Filter Forecasting Model (KFFM) through the different project periods will be assessed and compared with the other forecasting methods such as the Critical Path Method (CPM), which makes the time forecast at activity level by revising the actual reporting data for each activity at a certain data date. A case study project is used to validate the results of the three models. Hence, the best model is selected based on the lowest average percentage of error. The results showed that the KFFM developed in this study provides probabilistic prediction bounds of project duration at completion and can be applied through the different project periods with smaller errors than those observed in EV and ES forecasting models

    Formulation and Evaluation of Taste-Masked Orally Disintegrating Tablets of Nicergoline based on β-cyclodextrin Inclusion Complexation

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    Complexation of nicergoline with β-cyclodextrin (β-CD) into an inclusion complex has been used successfully to improve the drug’s solubility, dissolution rate and hence per oral absorption. In addition, masking of the bitter taste was also achieved. The preparation of inclusion complexes was performed using two different techniques, namely; physical mixing and kneading. The apparent stability constant (Kc) of the complex was calculated from the phase solubility analysis. Compatibility of nicergoline and β-CD complex with disintegrants and superdisintegrants were evaluated using powder x-ray diffractometry (PXRD), differential scanning calorimetry (DSC), and fourier transform infrared spectroscopy (FTIR). The morphology of complex particles was studied using scanning electron microscopy. Pharmaceutical characterization confirmed that all additives were compatible with the drug and no signs of physical or chemical interaction were detected. Orodispersible tablets (ODTs) of nicergoline complexed with β-CD and containing 7-9 % camphor had rapid disintegration time (7-12 seconds) and fast drug release profiles (90-100 % in 10 minutes). Therefore, nicergoline ODTs are considered a valuable choice dosage form with improved per oral absorption and taste acceptability
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