Nazarbayev University

Nazarbayev University Repository
Not a member yet
    6788 research outputs found

    PROPERTIES OF HYBRID FIBERS REINFORCED ENGINEERED GEOPOLYMER COMPOSITE CONTAINING GGBFS AND NON-CONVENTIONAL FLY ASH

    No full text
    A multifunctional seismic retrofitting technology is being developed for unreinforced masonry structures. This technology proposes to use lightweight engineered cementitious composites (ECC) trowelling on the surface of the masonry wall to improve its strength, ductility, and thermal performance. As part of research efforts, this thesis is to develop lightweight engineered geopolymer composites (EGC) using locally available industrial by-products and hybrid fibers. A possible alternate for typical engineered cementitious composite (ECC) is the recently developed engineered geopolymer composite (EGC). It is being investigated as a green building material with significant potential to lower CO2 emissions, primarily by the incorporation of industrial by-products into its matrix. As binder materials in EGC, ASTM-classified fly ash and GGBFS are used. In Kazakhstan, tons of waste materials from natural resources are produced including coal fly ash. However, due to the absence of quality control, locally available fly ash has a coarser particle size distribution which resulting in a low strength activity index than the ASTM specification, categorizing it as non-conventional fly ash. It is unclear if such non-conventional fly ash can achieve similar required mechanical properties as the classified one. Thus, it is worthwhile to investigate the suitability of the local fly ash as a binder material in the EGC. Additionally, the high cost of mostly used oil-coated polyvinyl alcohol (PVA) fiber as reinforcement in the ECC and EGC, limits their application in the industry, particularly in developing countries. To investigate the possibility of replacing the PVA fibers with other economically beneficial fibers such as Polypropylene (PP) fibers and steel (S), the EGC with different fiber combinations is considered in this thesis. Moreover, as part of requirement for multifunctional retrofitting, this thesis investigates the possibility for replacing the fine sand with lightweight aggregates (e.g. hollow micro glass bubbles (HMGB)) in the EGC in order to improve its thermal performance. This thesis investigates the workability, dry shrinkage, compressive strength, tensile strength, stain hardening capacity and thermal conductivity for the proposed EGC through extensive experimental studies. The investigation was conducted in two studies. In study I, the EGC containing non-conventional fly ash, GGBFS, and different fibers combinations was studied. The mixture proportion between fly ash and GGBFS was selected from a previous study. The main study parameter is the fiber combination among PVA, PP, and steel with a fixed total fiber content of 2%. Eight different fiber combinations were studied. In study II, the lightweight EGC by replacing the fine sand with the HMGB was studied for selected four mixtures in study I. The results from Phase I indicates that the EGC with the non-conventional fly ash can achieve required mechanical properties in terms of strength and strain hardening capacity. The EGC with PVA and PP combined fiber can achieve similar mechanical properties as the one with PVA only, while the PVA and steel combination does not perform well. A suitable combination can be 1.5% PVA and 0.5% PP. The highest compressive strength of EGC reaches with this combination and is 25 MPa. However, both tensile strength and strain slightly decrease to 2.04 MPa and 2.03%, respectively. It is also observed that by adding the fiber, the dry shrinkage and long-term strength loss occurred in the matrix have been significantly reduced. The EGC also exhibits lightweight and superior thermal performance as compared to the ECC without introducing lightweight aggregates. The results from Phase II show that replacing the fine sand with HMGB slightly lower the mechanical performance of the EGC. At the same time, it does not significantly reduce the weight and improve the thermal performance. Therefore, it is not necessary to replace the fine sand with the HMGB

    INVESTIGATION OF A MULTIFUNCTIONAL GRID-TIED PHOTOVOLTAIC INVERTER SYSTEM FOR POWER QUALITY IMPROVEMENT

    No full text
    This M.Sc thesis present the high gain DC-DC converter (HGDDC) for solar photovoltaic system (SPVs) with a multi-functional grid-tied inverter (MFGTI). The HGDDC step up the low SPVs voltage to a constant high gain DC voltage then to be easily integrated with utility grid voltage, at meantime to minimize the voltage ripple and reduce the stress of switches at output bus bar. In addition MFGTI convert the stepped up high gain voltage into demanded three phase utility grid voltage. While integrating the high gain voltage with utility grid voltage there are challenges like: grid voltage synchronization and power quality problems that are happened to the system due to non-linear loads, and SPVs irradiation changes. Therefore, to overcome of the grid synchronization and power quality issues, such as total current harmonic distortion, reactive power and to enhance the power factor, the author proposed a developed SRF control topology based on artificial neural network (ANN) techniques. This topology enable the MFGTI to inject the active power of SPVs to the utility gird Simulteniously to compensate the reactive power, reduce the total current harmonic, to enhance the power factor of the system and at main time to maintain the dc link voltage with very less voltage fluctuation. Eventually, the simulated results validate the satisfactory working of the proposed control topology under various solar irradiation, and nonlinear load conditions, it’s worthy to mention by implementing the mention topology the total current harmonics of the system reduced within IEEE-519 standards. To the end, a comparison study between ANN controller and dynamic PI of the synchronize reference frame (SRF) control theory are tested. Several simulations and prototype results are depicted to verify and validate the influenced of ANN based control. The proposed model is performed by MATLAB®/Simulink software, and the prototype work is done through Arduino Atmega 2560 controller

    IMPACT ASSESSMENT OF REAL-WORLD LARGE-SCALE OIL AND GAS PROJECTS WITH FUZZY DATA

    No full text
    The proposed capstone project aims to address the limitations of current MCDA methods and develop a more effective tool for decision-making in the oil and gas industry, particularly oilfield selection. The project will focus on the application of three MCDA methods: SPOTIS, COMET, and MCDA Index Tool. These methods will be evaluated based on their ability to address the challenges specific to the oil and gas industry, including various factors. The study will also explore the feasibility of developed comprehensive tool that can effectively address all the criteria required for generating valid results. This tool will be tailored to the unique characteristics of the oil and gas industry, and it will incorporate the various objectives and criteria that are essential for making informed decisions in this sector. The project will utilize a combination of literature review and case studies to investigate the effectiveness of the three MCDA methods and their applicability for the oil and gas industry. The study will also explore the factors that need to be considered in the development of the decision-making tool in this industry, including the availability and quality of data, the level of uncertainty and risk, and the stakeholder preferences. The expected outcomes of this project include a deeper understanding of the challenges and limitations of current MCDA methods in the oil and gas industry, as well as insights into the potential for developing a more effective and comprehensive tool for decision-making in this sector. The results of this study could have significant implications for the oil and gas industry, as well as for other industries that require a systematic approach to decision-making

    TRIAXIAL SHEAR BEHAVIOR OF CEMENTED-TREATED SAND UNDER HIGH CONFINING PRESSURES

    Get PDF
    Over the years, stabilizing materials like biopolymer, fly ash, bitumen, lime, and Portland cement have stabilized and improved the engineering soil's properties. However, because of the environmental problems associated with OPC use, substituting it with calcium sulfoaluminate (CSA) cement offers excellent promise for ground improvement because it is less harmful to the environment. Nevertheless, previous studies have examined the effects of CSA cement on the mechanical behavior of cemented sand; researchers have yet to make an effort to study the behavior of CSA cement-treated sand under high confining pressure. To this end, a consolidated-drained (CD) triaxial test was conducted at high confining pressure to examine CSA treated sand's shear strength and mechanical characteristics. In addition, SEM analysis was performed to learn more about the substructure of the tested samples. Experimental conditions, including effective stresses of 500, 1000, and 1500 kPa, and 3, 5, and 7% CSA cement content were employed in this research. In conclusion, the test results revealed that the effective stresses and the percentage of CSA cement present in the samples significantly impact the mechanical behavior of CSA-treated sand under high confining pressures

    DEVELOPMENT OF FAILURE PREDICTION MODEL FOR THE OIL AND GAS INDUSTRY

    No full text
    The oil and gas is a crucial sector in the global economy, and the Republic of Kazakhstan has established itself as a significant player in this field. As the industry continues to evolve, companies are actively seeking ways to leverage advanced digital technologies to optimize their operations, enhance safety, and increase profitability. This capstone project represents a cutting-edge effort to develop a framework for failure prediction in the oil and gas sector. Through close collaboration with Caspi Neft, which is a leading digitalization pioneer in the Kazakhstani market, this study has produced a range of innovative deliverables. These include the failure prediction model for the oil and gas equipment, an example of a well. In addition, the project has developed a comprehensive framework for the implementation of the model, which enables it to be readily integrated into the enterprise resource planning (ERP) system of the company. To achieve these outcomes, the project team employed a range of advanced machine learning algorithms, leveraging a rich dataset provided by Caspi Neft. This dataset included detailed information on operational conditions, downtime history, and other critical variables, allowing the team to generate a highly accurate failure prediction model with a validation accuracy of over 90%. The model was further validated through expert review, demonstrating its robustness and applicability to real-world conditions. The oil and gas industry is characterized by a dynamic and evolving dataset, which presents challenges for long-term prediction and modeling. In addition, the industry is subject to strict confidentiality requirements, which can limit the availability of data for research purposes. Nonetheless, the present project represents a significant step forward in the establishment of advanced digital technologies for the oil and gas industry, with the potential to drive cost reductions, enhance safety, and increase efficiency in this vital sector

    ELECTROACTIVITY OF YARROWIA LIPOLYTICA AND BIOPROCESS IMPROVEMENT

    Get PDF
    Electrofermentation is known to mitigate redox imbalance in anaerobic growth, thus increasing growth and key metabolite production in yeast. In the first part of this work, I investigated growth, biofilm formation, and oil degradation under electrofermentation conditions of Yarrowia lipolytica through laboratory-scale bioelectrochemical cells. Two commonly used redox mediators, 2-hydroxy-1,4-naphthoquinone (2-HNQ) and potassium ferricyanide (K3[Fe(CN)6]) were tested to enhance the bio-electrochemical process. Results show that K3[Fe(CN)6] leads to better planktonic growth and biofilm formation compared to 2-HNQ. In the second part of the thesis, I investigated the possibility of using sunflower oil as an additional carbon source in a laboratory-scale electrofermentation process, to stimulate lipase production, a key group of enzymes used in the biofuel production and upcycling of waste oil. While I could not directly measure lipase expression, the electrofermentation experiments resulted in approximately 47 % higher cumulative charge output in presence of 5% of sunflower oil, suggesting that electrofermentation increases lipase production and oil metabolism. This work lay the basis for the development of an efficient waste oil degradation process under electrofermentation conditions

    ELECTROANALYTIC EVALUATION OF PHYSIOLOGICAL INTERACTIONS BETWEEN LACTOBACILLI AND STAPHYLOCOCCUS AUREUS

    Get PDF
    Studying individual bacterial species in co-culture is crucial for understanding the specific properties and behaviours that emerge from the interactions between microorganisms in the natural environment. The present study aimed to evaluate the physiological and electrochemical properties of a co-culture of Lactobacilli and Staphylococcus aureus. To facilitate equal growth of the two antagonistic species, Compound Media was developed. The results showed that Lactobacilli species inhibited the planktonic growth and biofilm formation of S. aureus in co-culture under both aerobic and anaerobic conditions in CM media. Among the three tested Lactobacilli species, Lactobacillus plantarum was found to exhibit significant antimicrobial activity against S. aureus, indicating that the metabolites secreted by Lactobacilli could be used as a natural antimicrobial agent. To enhance the electroactivity of bacterial cells, a redox mediator known as 2-hydroxy-1,4-naphthoquinone (HNQ) was introduced into the culture media. The inclusion of HNQ at a concentration of 20 μM increased the current and total charge of both individual and co-cultured cells. The current and total charge of S. aureus were higher than those of L. plantarum, indicating a greater proliferation rate of S. aureus. The data suggested that HNQ at 20 μM concentration had a minimal impact on the growth and biofilm formation of both individual and co-cultured cells. These findings provide insights into the physiological interactions between Lactobacilli and S. aureus, which can aid in the development of new tools and approaches for combating bacterial infections. The electrochemical approach used in this study can also be applied to investigate interactions between different microorganisms and understand their physiological and electrochemical properties

    ID LOGIC IS MORE THAN RFID

    No full text

    DETERMINANTS OF INNOVATION: AN EVIDENCE-BASED PERSPECTIVE IN THE DIGITAL TRANSFORMATION ERA

    Get PDF
    Innovation, the process of finding and using new ideas, creating new products or services, and introducing them to the market, is widely celebrated as the driving force of economic growth, sustainable development, and social change. Yet, innovation activity around the world is mostly concentrated in a few leading countries that possess the human and financial capital to create new knowledge and the market acumen to capitalize on it. For instance, three quarters of the patent filings from global innovation hotspots are emerging from just four countries – USA, Japan, China, and Germany. This uneven concentration of inventive activity, aptly named the global innovation divide, increases the gap between developed and developing economies. The situation has exacerbated over the last decade with the fourth industrial revolution and the emergence of the digital economy that has brought to the forefront knowledge generation and utilization. To close the innovation gap, regional, national, and international governments and authorities constantly encourage innovation through an array of fiscal subsidies and regulatory interventions with admittedly mixed results. Innovation of course starts at the firm level, with innovative firms developing competitive advantages for themselves and for their regions through knowledge exploration and exploitation and the creation of new technologies. Even in innovation leaders such as Germany, roughly one in two enterprises do not engage in innovation. Obstacles to innovation reflect the realization that innovation is a difficult, financially risky, and mostly liable to fail process. A multitude of business surveys and research studies have been dedicated to identifying and assessing the importance of the obstacles that deter firms from innovating and contrasting them with the obstacles slowing down, but not stopping, firms already engaged in innovation. While there is a broad consensus on what constitutes an obstacle to innovation, the term is open to a wide range of interpretations that are largely contingent upon the context within which innovation occurs. This handicaps the effectiveness of innovation policies that are based upon a generic understanding of the innovation process and are not sufficiently nuanced for the digital era. Past research on innovation has sought to identify major correlates of innovation by assessing only one dimension of innovative behavior at each time. Treating the phenomenon of innovation as unidimensional does not sufficiently capture the richness of the construct of organizational innovation. This dissertation demonstrates instead that the process of innovation is decidedly multi-dimensional and explores the multi-faceted nature of the impact of innovation on firms, regions, and countries. Based on an extensive range of iv publicly available datasets and using a multi-dimensional analytical approach, this dissertation dissects the phenomenon of innovation at several layers of abstraction: the firm layer, the operational layer, the process layer and the policy layer. The contributions of this dissertation at each layer are addressed in turn. • At the firm layer, the key characteristics of the profile of an organization that impact its involvement in innovation activities are identified as firm size, sector, and prior engagement in innovation activities. • At the operational layer, the effect of factors present in the operational environment within which innovation occurs is measured with emphasis on economic, market, cultural and gender diversity issues. • At the process layer, issues related to knowledge acquisition, elicitation, and management in innovative firms are introduced and examined in the context of tangible innovation outputs such as intellectual property rights. • At the policy layer, the effect of innovation policies and interventions over the last decade is assessed with a special focus on the promotion of clustering activities and innovation hotspots. The results of this evidence-based dissertation presented herein are instrumental in defining the specific facets of an effective, modern innovation policy, producing the desired performance outcomes in a context of limited resources for innovation

    3,400

    full texts

    4,758

    metadata records
    Updated in last 30 days.
    Nazarbayev University Repository is based in Kazakhstan
    Access Repository Dashboard
    Do you manage Open Research Online? Become a CORE Member to access insider analytics, issue reports and manage access to outputs from your repository in the CORE Repository Dashboard! 👇