760 research outputs found

    Sustainable Management of Calcareous Saline-Sodic Soil in Arid Environments: The Leaching Process in the Jordan Valley

    Get PDF
    A leaching experiment of calcareous saline-sodic soil was conducted in Jordan Valley and aimed to reduce the soil salinity ≤ 4.0 dS m−1. The quantification of salt removal from the effective root zone was done using three treatment scenarios. Treatment A contained soil amended with gypsum leaching with fresh water (EC = 1.1 dS m−1). Treatments B and C contained nonamended soil, but B was leached with fresh water only while treatment C’s soil was washed with saline agricultural drainage water (EC = 8 dS m−1) at the start of the experiment and continued with fresh water to reach the desired soil salinity. All treatments were able to reduce the soil salinity to the desired level at the end of the experiment; however, there were clear differences in the salt removal efficiencies among the treatments which were attributed to the presence of direct source of calcium ion. The soil amended with gypsum caused a substantial decline in soil salinity and drainage water’s electrical conductivity and drained the water twice as fast as the nonamended soil. It was found that utilizing agricultural drainage water and gypsum as a soil amendment for calcareous saline-sodic soil reclamation can beneficially contribute to sustainable agricultural management in the Jordan Valley

    Incremental Lifecycle Validation Of Knowledge-based Systems Through Commonkads

    Get PDF
    This dissertation introduces a novel validation method for knowledge-based systems (KBS). Validation is an essential phase in the development lifecycle of knowledge-based systems. Validation ensures that the system is valid, reliable and that it reflects the knowledge of the expert and meets the specifications. Although many validation methods have been introduced for knowledge-based systems, there is still a need for an incremental validation method based on a lifecycle model. Lifecycle models provide a general framework for the developer and a mapping technique from the system into the validation process. They support reusability, modularity and offer guidelines for knowledge engineers to achieve high quality systems. CommonKADS is a set of models that helps to represent and analyze knowledge-based systems. It offers a de facto standard for building knowledge-based systems. Additionally, CommonKADS is a knowledge representation-independent model. It has powerful models that can represent many domains. Defining an incremental validation method based on a conceptual lifecycle model (such as CommonKADS) has a number of advantages such as reducing time and effort, ease of implementation when having a template to follow, well-structured design, and better tracking of errors when they occur. Moreover, the validation method introduced in this dissertation is based on case testing and selecting an appropriate set of test cases to validate the system. The validation method defined makes use of results of prior test cases in an incremental validation procedure. This facilitates defining a minimal set of test cases that provides complete and effective system coverage. CommonKADS doesn’t define validation, verification or testing in any of its models. This research seeks to establish a direct relation between validation and lifecycle models, and introduces a validation method for KBS embedded into CommonKAD

    Digital Pulse Width Modulator Techniques For Dc - Dc Converters

    Get PDF
    Recent research activities focused on improving the steady-state as well as the dynamic behavior of DC-DC converters for proper system performance, by proposing different design methods and control approaches with growing tendency to using digital implementation over analog practices. Because of the rapid advancement in semiconductors and microprocessor industry, digital control grew in popularity among PWM converters and is taking over analog techniques due to availability of fast speed microprocessors, flexibility and immunity to noise and environmental variations. Furthermore, increased interest in Field Programmable Gate Arrays (FPGA) makes it a convenient design platform for digitally controlled converters. The objective of this research is to propose new digital control schemes, aiming to improve the steady-state and transient responses of a high switching frequency FPGA-based digitally controlled DC-DC converters. The target is to achieve enhanced performance in terms of tight regulation with minimum power consumption and high efficiency at steady-state, as well as shorter settling time with optimal over- and undershoots during transients. The main task is to develop new and innovative digital PWM techniques in order to achieve: 1. Tight regulation at steady-state: by proposing high resolution DPWM architecture, based on Digital Clock Management (DCM) resources available on FPGA boards. The proposed architecture Window-Masked Segmented Digital Clock Manager-FPGA based Digital Pulse Width Modulator Technique, is designed to achieve high resolution operating at high switching frequencies with minimum power consumption. 2. Enhanced dynamic response: by applying a shift to the basic saw-tooth DPWM signal, in order to benefit from the best linearity and simplest architecture offered by the conventional counter-comparator DPWM. This proposed control scheme will help the compensator reach the steady-state value faster. Dynamically Shifted Ramp Digital Control Technique for Improved Transient Response in DC-DC Converters, is projected to enhance the transient response by dynamically controlling the ramp signal of the DPWM unit

    Chemical And Biological Treatment Of Mature Landfill Leachate

    Get PDF
    The challenges imposed on Voltage Regulator Modules (VRM) become difficult to be achieved with the conventional multiphase buck converter commonly used on PC motherboards. For faster data transfer, a decrease in the output voltage is needed. This decrease causes small duty cycle that is accompanied by critical problems which impairs the efficiency. Therefore, these problems need to be addressed. Transformer-based non-isolated topologies are not new approaches to extend the duty cycle and avoid the associated drawbacks. High leakage, several added components and complicated driving and control schemes are some of the trade-offs to expand the duty cycle. The objective of this work is to present a new dc-dc buck-based topology, which extends the duty cycle with minimum drawbacks by adding two transformers that can be integrated to decrease the size and two switches with zero voltage switching (ZVS). Another issue addressed in this thesis is deriving a small signal model for a two-input two-phase buck converter as an introduction to a new evolving field of multi-input converters

    Sports Injury and Recovery Analyzed Using Blum\u27s Model of Health Determinants

    Get PDF
    This study explores the effects of various health determinants on the ability of a college athlete to recover from a sport’s injury. Blum\u27s Model of Health Determinants explains that there are four factors that contribute to the overall health of an individual: lifestyle, environment, medical services and heredity. Blum argued that each factor affects health to a different degree. To understand how each of these determinants affects an athlete’s recovery, different people involved in this process were interviewed, including coaches, trainers, athletes and sports psychologists. These interviews illustrated the need for an expansion within this model of health. While all four of these determinants are critical for the athlete to recover, one aspect that is not discussed in this model is mental health. The mental aspects discussed by every individual interviewed emphasized how significant this mental health role is within the recovery of an athlete. Implications of this research include the movement towards a more holistic understanding of health. By highlighting the mental aspects of recovery, the field of orthopedics has pioneered the need for a restructure of how health care views mental health, fielding the need for changes within various organizations such as the government, medical schools, and the American Medical Association. Currently, society and practitioners within fields of medicine beyond orthopedics are grappling with the link between mind and body. The results of this study indicate the need for this recognition within the orthopedic field as well as throughout other fields of medicine

    Why an open mind on open science could reshape human knowledge

    Get PDF
    In the year 1610, Galileo observed a ring-like shape around a distant planet (Saturn). After realising the significance of his discovery, Galileo wanted to record it to be able to claim it as his own contribution once it was announced. To do that, he wrote a letter to a colleague stating the following: "smaismrmilmepoetaleumibunenugttauiras"

    Thoughts on the future of human knowledge and machine intelligence

    Get PDF
    Throughout history, nations and armies have brawled for knowledge. The burning of the Library of Alexandria, the destruction of Xianyang Palace’s archives, the secret investigations of the Dead Sea Scrolls, the destruction of the Mayan Codex, and many other examples illustrate the continuous human quest for owning knowledge or eliminating it from an enemy

    The unspoken global race for artificial intelligence

    Get PDF
    Two men walk into a bar, the first one says: “robots will conquer our civilisation and make us their servants within ten years”, the second one responds: “No, the principle of artificial intelligence (AI) is a far-fetched goal that will never see light”. The bartender smiles, analyses their facial expressions, assigns a sentiment score to their sentences, evaluates their historical drinking trends, and decides to pour the first one a glass of gin and tonic, and the second one a glass of Scotch. Here is the spoiler: both men are lying; and the bartender is a robot. Not a funny joke, but a reality that is shadowing all conventional discussions about the future prospects of AI. In order to avoid such binary discussions about the goodness and possibilities of machine intelligence, and to eliminate the ‘hype’ surrounding the topic, this article aims to unveil the slowly cooking, quietly simmering, unspoken truths of the inevitable global arms race of AI

    An Empirical Model of Collaboration Capability and Absorptive Capacity in Virtual Teams: a Multi-Dimensional Investigation using Confirmatory Factor Analysis

    Get PDF
    Virtual teams are being increasingly utilized in industry given their ability to bring together diverse knowledge and experience from individuals who are not geographically proximal. Having a diversity of knowledge within virtual teams is noted to benefit innovation outcomes; however, leveraging the benefits of diversity (both deep-level and functional level) is likely to require a capability to facilitate collaboration among team members. This dissertation examines collaboration capability and absorptive capacity at the virtual team level by evaluating the inter-relationships among the dimensions and their influence on team innovation. This research also tests the impact of team diversity on team innovation with an additional focus on understanding the moderating impact of collaboration capability and the mediating impact of absorptive capacity. Two dimensions of team diversity are examined. The first dimension, deep-level diversity, involves the individual characteristics, values, attitudes and preferences. The second dimension, functional-level diversity, which entails the diversity in functional and expertise backgrounds. Survey data was collected from 166 virtual team members and the validation process revealed satisfactory psychometric properties at the items and the constructs level. A confirmatory factor analysis (CFA) was carried out to determine the factor structure of the hypothesized models, as well as its reliability and validity
    corecore