Stability of secure routing protocol in ad hoc wireless network.

The contributions of this research are threefold. First, it offers a new routing approach to ad hoc wireless network protocols: the Enhanced Heading-direction Angle Routing Protocol (EHARP), which is an enhancement of HARP based on an on-demand routing scheme. We have added important features to overcome its disadvantages and improve its performance, providing the stability and availability required to guarantee the selection of the best path. Each node in the network is able to classify its neighbouring nodes according to their heading directions into four different zone-direction group. The second contribution is to present a new Secure Enhanced Heading-direction Angle Routing Protocol (SEHARP) for ad hoc networks based on the integration of security mechanisms that could be applied to the EHARP routing protocol. Thirdly, we present a new approach to security of access in hostile environments based on the history and relationships among the nodes and on digital operation certificates. We also propose an access activity diagram which explains the steps taken by a node. Security depends on access to the history of each unit, which is used to calculate the cooperative values of each node in the environment

Sentiment analysis in the Arabic language using machine learning

Includes bibliographical references.2015 Summer.Sentiment analysis has recently become one of the growing areas of research related to natural language processing and machine learning. Much opinion and sentiment about specific topics are available online, which allows several parties such as customers, companies and even governments, to explore these opinions. The first task is to classify the text in terms of whether or not it expresses opinion or factual information. Polarity classification is the second task, which distinguishes between polarities (positive, negative or neutral) that sentences may carry. The analysis of natural language text for the identification of subjectivity and sentiment has been well studied in terms of the English language. Conversely, the work that has been carried out in terms of Arabic remains in its infancy; thus, more cooperation is required between research communities in order for them to offer a mature sentiment analysis system for Arabic. There are recognized challenges in this field; some of which are inherited from the nature of the Arabic language itself, while others are derived from the scarcity of tools and sources. This dissertation provides the rationale behind the current work and proposed methods to enhance the performance of sentiment analysis in the Arabic language. The first step is to increase the resources that help in the analysis process; the most important part of this task is to have annotated sentiment corpora. Several free corpora are available for the English language, but these resources are still limited in other languages, such as Arabic. This dissertation describes the work undertaken by the author to enrich sentiment analysis in Arabic by building a new Arabic Sentiment Corpus. The data is labeled not only with two polarities (positive and negative), but the neutral sentiment is also used during the annotation process. The second step includes the proposal of features that may capture sentiment orientation in the Arabic language, as well as using different machine learning classifiers that may be able to work better and capture the non-linearity with a richly morphological and highly inflectional language, such as Arabic. Different types of features are proposed. These proposed features try to capture different aspects and characteristics of Arabic. Morphological, Semantic, Stylistic features are proposed and investigated. In regard with the classifier, the performance of using linear and nonlinear machine learning approaches was compared. The results are promising for the continued use of nonlinear ML classifiers for this task. Learning knowledge from a particular dataset domain and applying it to a different domain is one useful method in the case of limited resources, such as with the Arabic language. This dissertation shows and discussed the possibility of applying cross-domain in the field of Arabic sentiment analysis. It also indicates the feasibility of using different mechanisms of the cross-domain method. Other work in this dissertation includes the exploration of the effect of negation in Arabic subjectivity and polarity classification. The negation word lists were devised to help in this and other natural language processing tasks. These words include both types of Arabic, Modern Standard and some of Dialects. Two methods of dealing with the negation in sentiment analysis in Arabic were proposed. The first method is based on a static approach that assumes that each sentence containing negation words is considered a negated sentence. When determining the effect of negation, different techniques were proposed, using different word window sizes, or using base phrase chunk. The second approach depends on a dynamic method that needs an annotated negation dataset in order to build a model that can determine whether or not the sentence is negated by the negation words and to establish the effect of the negation on the sentence. The results achieved by adding negation to Arabic sentiment analysis were promising and indicate that the negation has an effect on this task. Finally, the experiments and evaluations that were conducted in this dissertation encourage the researchers to continue in this direction of research

The international contractor's decision to invest : a strategic risk management decision model for public private partnership projects in Saudi Arabia

One of the main sources of risks that influence potential project success is the project selection decision, especially for international contractor organisations looking for an opportunity to invest in public private partnership projects in foreign countries. Project selection decision, which involves the bid/no bid decision, is a critical investment decision needs to be made based on concrete project evaluation and risks identifications; where negative-risk is in place if there is an absence of a rational basis at the time of making such a decision. Thus, negative consequences of such a decision might occur. The bid/no bid decision necessitates an effective project evaluation and risk identification from various aspects with consideration of several internal and external factors in order to achieve project success. Bidding for PPP projects overseas without efficiently applying risk management tools and techniques to evaluate both the project and the organisation’s current situation and capability might result either in large losses or consumption of time and resources that could have been avoided. The prime aim of this research is to develop a strategic investment decision model from the perspective of risk management, in order to facilitate the decisions of international contractors who intend to invest in public private partnership projects in the Saudi Arabian construction industry. This aim requires establishing a link between the risk management process and the organisation's strategy and its current situation, and identifying risks involved in the bid/no bid decision, PPP projects, and international investment in order to provide an effective computer-based model that is capable of organising the bid/no bid decision in a rational, logical, flexible, and user-friendly manner. The pragmatic triangulation philosophy approach is adopted as the best research methodology that allows two types of research strategy to be combined in order to accomplish the research aim and objectives. Thus, the methods used are qualitative interviews and a quantitative questionnaire-based survey. The findings of this research identified critical success factors of international contractors’ bidding decisions for PPP projects in the Saudi Arabian construction industry. In particular, seventy-seven factors affecting the bid/no bid decision were used as a foundation for development of a Strategic Risk Management Decision Model (SRMDM), available at www.srmdm.com

A Current-Source Modular Converter for Large-Scale Photovoltaic Systems

The world is shifting toward renewable energy sources (RESs) to generate clean energy and mitigate the stress of global warming caused by CO2 emissions in recent decades. Among several RES types, large-scale photovoltaic (LSPV) plants are a promising source for meeting ambitious clean energy targets and being part of power generation. With the progress of high-power modular inverters, new opportunities have arisen to integrate them into LSPV systems connected to medium-voltage (MV) grids to obtain high efficiency and reliability, better system flexibility, and improved electrical safety compared with string or central inverters. This thesis presents and implements a new current source three-phase modular inverter (TPMI) based on a novel dual-isolated SEPIC/CUK (DISC) converter. The TPMI is designed with a single power processing stage comprised of seriesconnected DISC submodules (SMs) to deliver MV into the utility grid. It outperforms conventional high-power inverters in terms of modularity, scalability, galvanic isolation compliance, and distributed maximum power point tracking (MPPT) capabilities. The DISC converter employed as an SM in the proposed TPMI generates bipolar output (i.e., both positive and negative voltages). In addition to having step-up and step-down capabilities with a continuous input current, this converter shares an input side inductor, thereby reducing the number of components. The DISC structure, modulation method, operation, novel state-space model, and parameter design procedure are analysed in details. Then, simulation results are presented to validate the theoretical and analytical analyses of the DISC converter. The proposed TPMI inverter is subsequently integrated into the LSPV grid connection to prove its suitability for such applications. In the theoretical analysis, the advantages of TPMI structure over conventional topologies are discussed. Then, the modulation technique, and operational concept are presented, followed by a dedicated control strategy is implemented by adding a system and SM-level controllers. The system controller is required for the generation of uniform duty ratios for all SMs in order to regulate the power transfer. The SM level controller is introduced to ensure equal current and voltage distribution between SMs and to compensate for minor discrepancies between the various parameters. The entire TPMI system is demonstrated through MATLAB and Simulink simulations, with the objective being to deliver the rated (1 MW) power from the PV modules under normal operation, uniform shading, and partial shading conditions and to match PV generation with the grid’s power demands. A downscaled 3-kW TPMI inverter was developed in the laboratory to validate its feasibility experimentally with its control strategy in different operating conditions. Finally, the TPMI performance is compared with selected current source inverter topologies, which shows that TPMI obtains good efficiency within the context of existing state-of-the-art current source converters. Then, the TPMI structure is modified by redesigning its DISC SMs, which provides several benefits, including a reduction in the number of switch devices operating at high frequency, thus decreasing switching losses, and an increase in efficiency. In this study, a half-cycle modulation (HCM) scheme is developed for the switches, and the operation of a modified DISC SM is analysed. Simulation and experimental results validate the performance of the modified TPMI topology and demonstrate its suitability for LSPV applications. According to the results of the comparison, the maximum power efficiency of the modified TPMI structure is 95.5%, which represents an improvement over the original TPMI structure

The Influence of Oil Prices Fluctuations on The Stock Prices: Evidence from Upstream Country (Saudi Arabia) and Downstream Country (United State)

GRACH (1,1) model was employed in this study to examine the volatility effect of crude oil prices on the Saudi (TASI) and U.S (S&P 500) stock markets during the time of period 2003-2016. In order to capture the accurate oil prices effect on those stock markets, the sample period was divided into four sub-periods. The results were that oil prices fluctuations had a significantly positive influence on the stock markets in Saudi Arabia and United States

Sentiment Analysis in Arabic: An Overview

The analysis of natural language text for identification of sentiment has been well-studied for the English language. In contrast, the work that has been done in Arabic remains in its infancy; thus, requiring more cooperation between research communities to offer a mature sentiment analysis system for Arabic. There are recognized challenges that face linguists in this field; some of them inherited from the nature of the Arabic language itself, and others derived from the scarcity of tools and sources. This article provides an overview of sentiment analysis in the Arabic language, by detailing what has been done in English as a model example of such an analysis, and what have been covered to date in Arabic, as well as some of the limitations and existing potential research avenues in this field

Current-source single-phase module integrated inverters for PV grid-connected applications

This paper presents a modular grid-connected single-phase system based on series-connected current-source module integrated converters (MICs). The modular configuration improves the reliability, redundancy and scalability of photovoltaic (PV) distributed generators. In this system, each PV panel is connected to a dc/ac inverter to permit individual Maximum Power Point Tracking (MPPT) operation for each panel. Thus, the harvested power from the PV system will increase significantly. There are four different inverter topologies suitable to be used as MICs with different performances in terms of filtering elements size, power losses, efficiency, output voltage range, and high frequency transformers’ size. For the MPPT control, the oscillating even order harmonic components should be eliminated from the inverter’s input side otherwise the maximum power cannot be extracted. The proposed modulation scheme in this paper will ease the control of inverter’s input and output sides. Therefore, the 2nd order harmonic in the input current can be eliminated without adding new active semiconductor switches. A repetitive controller coupled with proportional-resonant controllers are employed to achieve accurate tracking for grid side as well as input side currents. Comparisons and performance evaluations for the proposed MICs are presented and validated with 1 kVA prototype controlled by TMS320F29335 DSP

The development of an arbitration system attractive to international commerce: analysing the new Saudi law of arbitration 1433H (2012)

The practice of International Commercial Arbitration (ICA) has undergone several developments in the legislative history of the Kingdom of Saudi Arabia (KSA) largely influenced by the surrounding political, economic and legal circumstance. This was evident in the welcoming approach to ICA at the time of its establishment, which later changed to a hostile approach following the Aramco case. This hostile attitude hindered the development of the KSA arbitration framework up until the 1970s when it realised the importance of ICA in creating a reliable formwork for international commerce. Since then, the KSA has gradually developed a cautious and welcoming approaching to ICA, while at the same time reserving its sovereign rights over local disputes. This thesis critically assesses the development of the KSA arbitration regulation and the influence of both Sharia and the KSA culture in its development. In this regard, this thesis discusses the influence of the various Sharia sources on the KSA legal system and how such sources could be reconciled with current Islamic law theories. Such reconciliation will help remove issues evident in the KSA’s interpretation and application of Sharia principles. This is particularly necessary when ascertaining the limits of KSA public policy, which is primarily based on Sharia rules. The Islamic natural law theory and Maqasid Al Sharia theory provide an effective rationale for resolving issues arising under Islamic law. If such theories are well utilised by the KSA lawmakers, the issue of public policy and any other upcoming issues will be effectively resolved within the boundary of Sharia. This thesis additionally discusses the 2012 Saudi Arbitration Regulation SAR and how it develops the earlier practice of ICA in the KSA. It draws comparisons, where relevant, with the UNICTRAL Model Law and other institutional and developed states’ rules in order to compare the new regulation’s provisions with those of internationally recognised standards. This is particularly important in light of the KSA’s aims in attracting international commerce, which requires a system of developed and reliable legal regulations capable of governing disputes. In this regard, this thesis examines the influence of the 2012 SAR on the KSA practice of ICA through the researcher’s collected interviews and enforcement cases. It also examines the influence of the 2013 Saudi Enforcement Regulation (SER) on the enforcement of both local and international awards. This regulation, alongside the 2012 SAR, governs the process of ICA from its start until its enforcement, requiring such processes to be of international standard in order to achieve the KSA goal of attracting foreign commerce. This thesis concludes by acknowledging the development introduced by the 2012 SAR into the KSA arbitration framework. It also acknowledges the 2012 SAR’s failures to address some of the important issues inherited from the predecessor regulation. The author additionally recommends certain steps that should be taken by the KSA in order to develop the 2012 SAR and the 2013 SER. The contentious issues in the KSA’s interpretation of Sharia rules are also addressed and specific recommendations are put forward to help clarify these issues. Finally, the author believes that the KSA arbitration framework, as it currently stands, is much more attractive than any predecessor regulation, but it is nevertheless not attractive enough to draw foreign commerce. Therefore, this thesis puts forward several recommendations aimed at making the KSA’s arbitration framework more attractive to both local and foreign commerce. These recommendations include: embracing a hybrid view of ICA, clarifying the ambiguities present in the 2012 SAR, developing the consultative council’s role, codifying the general provisions of Sharia, refining the scope of the KSA’s public policy and reconsidering the scope of interest in the KSA’s legal practice. The implementation of these recommendations will create an appropriately attractive and reliable arbitration framework