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Item Metadata only 13 Smart polymers for bioseparation and other biotechnological applications(Smart Polymers and their Applications, 2014-01-01) Savina, I.N.; Galaev, I. Yu.; Mikhalovsky, S.V.; I.N., SavinaAbstract: The progress in development of a number of novel products using recombinant DNA technology and cell culturing, plus the demands for high product yield whilst preserving biological activity, require novel approaches for fast and cost-effective isolation and/or purification processes. Smart polymers (SPs) with their ability to undergo considerable changes in response to external stimuli make possible the development of novel technologies for isolation and purification. In this chapter the main applications of SPs in biotechnology and, in particular, in bioseparation, are discussed. Affinity precipitation, two-phase polymer separation, using SP membranes and SP chromatographic carriers are overviewed with a presentation of recent developments and discussion of future perspectives in these areas. Application of SP as catalysts is also discussed.Item Open Access 19th International Conference on Turkish Linguistics(Nazarbayev University School of Sciences and Humanities, 2018-08-17)The Organizing Committee would like to thank… At Nazarbayev University Assel Sadykova (executive director, School of Humanities and Social Sciences), Aigerim Nurgaliyeva, Lazzat Sundetova, Ainur Yerezhepekova, Meruyert Mukanova, and Anel Kaddesova, colleagues, and student volunteers. At the International Turkic Academy President Darkhan Kydyrali, colleagues, and staff. At L.N. Gumilyov Eurasian National University Rector Erlan Syzdykov and colleagues, staff, and student volunteers. The members of the ICTL 19 Program Committee and anonymous reviewers. The participants in the cultural program from Nazarbayev University and L.N. Gumilyov Eurasian National University. Lars Johanson, Éva Á. Csató, and A. Sumru Özsoy for their encouragement to host ICTL 19 in Astana, as well as Mehmet-Ali Akinci for his kind support during the organization of the conference.Item Open Access 1D states of the beryllium atom: Quantum mechanical nonrelativistic calculations employing explicitly correlated Gaussian functions(2011) Sharkey, Keeper L.; Bubin, Sergiy; Adamowicz, LudwikVery accurate finite-nuclear-mass variational nonrelativistic calculations are performed for the lowest five 1D states (1s2 2p2, 1s2 2s1 3d1, 1s2 2s1 4d1, 1s2 2s1 5d1, and 1s2 2s1 6d1) of the beryllium atom (9Be). The wave functions of the states are expanded in terms of all-electron explicitly correlated Gaussian functions. The exponential parameters of the Gaussians are optimized using the variational method with the aid of the analytical energy gradient determined with respect to those parameters. The calculations exemplify the level of accuracy that is now possible with Gaussians in describing bound states of a four-electron system where some of the electrons are excited into higher angular statesItem Open Access 2D BI2SE3 VAN DER WAALS EPITAXY ON MICA FOR OPTOELECTRONICS APPLICATIONS(MDPI, 2020-08-22) Wang, Shifeng; Li, Yong; Ng, Annie; Hu, Qing; Zhou, Qianyu; Li, Xin; Liu, HaoBi2Se3 possesses a two-dimensional layered rhombohedral crystal structure, where the quintuple layers (QLs) are covalently bonded within the layers but weakly held together by van der Waals forces between the adjacent QLs. It is also pointed out that Bi2Se3 is a topological insulator, making it a promising candidate for a wide range of electronic and optoelectronic applications. In this study, we investigate the growth of high-quality Bi2Se3 thin films on mica by the molecular beam epitaxy technique. The films exhibited a layered structure and highly c-axis-preferred growth orientation with an XRD rocking curve full-width at half-maximum (FWHM) of 0.088◦ , clearly demonstrating excellent crystallinity for the Bi2Se3 deposited on the mica substrate. The growth mechanism was studied by using an interface model associated with the coincidence site lattice unit (CSLU) developed for van der Waals epitaxies. This high (001) texture favors electron transport in the material. Hall measurements revealed a mobility of 726 cm2 /(Vs) at room temperature and up to 1469 cm2 /(Vs) at 12 K. The results illustrate excellent electron mobility arising from the superior crystallinity of the films with significant implications for applications in conducting electrodes in optoelectronic devices on flexible substrates.Item Open Access 2D SKELETON-BASED HUMAN ACTION RECOGNITION USING ACTION-SNIPPET REPRESENTATION AND DEEP SEQUENTIAL NEURAL NETWORK(Nazarbayev University School of Engineering and Digital Sciences, 2022-05) Askar, AizadaHuman action recognition is one of the crucial and important tasks in data science. It aims to understand human behavior and assign a label on performed action and has diverse applications. Domains, where this application is used, includes visual surveillance, human–computer interaction and video retrieval. Hence, discriminating human actions is a challenging problem with a lot of issues like motion performance, occlusions and dynamic background, and different data representations. There are many researches that explore various types of approaches for human action recognition. In this work we propose advanced geometric features and adequate deep sequential neural networks (DSNN) for 2D skeleton-based HAR. The 2D skeleton data used in this project are extracted from RGB video sequences, allowing the use of the proposed model to enrich contextual information. The 2D skeleton joint coordinates of the human are used to capture the spatial and temporal relationship between poses. We employ BiLSTM and Transformer models to classify human actions as they are capable of concurrently modeling spatial relationships between geometric characteristics of different body parts.Item Restricted 2D/3D NOVEL MATERIALS FOR HIGH PERFORMANCE PEROVSKITE SOLAR CELLS(Nazarbayev University School of Engineering and Digital Sciences, 2022-04) Aidarkhanov, DamirThe continuous increase of energy demand and emission of greenhouse gases from the conventional fossil fuels signifies the importance of renewable energy. The solar radiation is a readily available renewable energy source. If the amount of solar energy irradiated on the earth can be converted into electrical energy very efficiently, the energy demand of our daily life can be satisfied. The photovoltaics (i.e. solar cells) are the devices directly converting the solar irradiation into the electrical energy. Among the existing photovoltaic technologies, the metal halide perovskite solar cells (PSCs) demonstrate a huge potential of realizing cost-effective and high-performance devices for future practical applications. The theoretical calculations demonstrate that a single junction PSC can reach a power conversion efficiency (PCE) above 30%. However, there are still a number of challenges hindering the commercialization of PSCs for the practical use. This work focuses on enhancing the performance of PSCs via application of novel 2D/3D materials and engineering of device architectures. A multilayer structure for electron-transporting layer (ETL) has been developed for high performance PSCs. It is shown that a triple-layer ETL consisted of SnO2 quantum dots, SnO2 nanoparticles, and fullerene-derivative based passivation layer can facilitate the carrier transports due to optimization of surface morphology of ETL which yields a better interface quality for subsequently deposited perovskite absorber layer. The defect states residing the interface between the ETL and perovskite are also reduced by optimizing the architecture of ETL in PSCs. Further, a two-dimensional material, black phosphorus (BP) in form of nanoflakes was used to modify the interface between the ETL and the perovskite layer. The application of BP in PSCs demonstrates an increase of the device efficiency and stability. The positive effect introduced by BP is attributed to the improved perovskite crystallization on BP modified ETL and passivation of interfacial defects by lone-pair electrons of BP. Meanwhile, the photovoltaic properties of multiple cations mixed-halide perovskite layer can be improved by incorporation of a cross-linking material, 2,2′-(Ethylenedioxy) bis(ethylammonium iodide). The PSCs incorporated with an optimized concentration of cross-linking material demonstrate an enhancement of PCE and improvement in stability, which are attributed to the passivation of the defect states located at the surface and grain boundaries of perovskite by the cross-linking molecules. The cross linker assisted crystallization also leads to the formation of compact perovskite thin films, which could suppress the penetration of various species such as moisture, oxygen etc. from the atmosphereItem Open Access 30 Gb/s integrated receiver array for parallel optical interconnects(IET, 2019-08) Nguyen, Nga T. H.; Ukaegbu, Ikechi; Park, Hyo-HoonA 30 Gb/s integrated receiver array for parallel optical interconnects with four channels have been designed and implemented in a 0.13 mu m CMOS technology. To achieve small area and low power consumption while maintaining large bandwidth and high gain, the integrated receiver has been implemented with a regulated cascode (RGC) transimpedance amplifier (TIA), resistive and capacitive degeneration and inductorless limiting amplifier (LA), which employs active feedback and negative capacitance. From the measurement results of the optical module using 850 nm photodiode (PD), the receiver showed a constant single-ended output swing of 320 mV up to 7.5 Gb/s/ch with clear eye diagrams and BER of <10(-12). With a voltage supply of 1.2 V, a figure of merit (FOM) of 8 mW/Gb/s was obtained with a small chip area per channel of 0.28 mm(2)/ch.Item Open Access 3D CFD Modeling Investigation of Potential Vortex Formation at the Intakes of Caruachi Powerhouse(INTERNATIONAL CONFERENCE ONHYDRAULICS OF DAMS AND RIVER STRUCTURES, TEHRAN, IRAN; 04/2004, 2004-04) Marcano, A.; Rojas-Solorzano, L.; Reyes, M.In this paper, the 3-D CFD simulation of the free-surface flow approaching the intakes of Caruachi Powerhouse is presented. The aim of the investigation is to determine whether or not vortex structures are likely to appear from the water surface through the intakes, as the result of the presence of cofferdams placed few meters upstream of the intakes. The presence of cofferdams was a note of concern with regard to the effects they might have on the turbine intakes once the hydroelectric central starts operating. In all the considered conditions, results did not show neither strong surface vortices in the proximities of the Power House intakes, nor air entrainment-entrapment towards the intakes, which reflects the safe operation of the turbines in the presence of the cofferdams. The latter added in decision taking on leaving the cofferdams submerged instead of removing them, which resulted in cost savings for the projectItem Open Access 3D CFD-DEM-IBM SIMULATIONS OF SAND PRODUCTION IN OIL WELLS(Nazarbayev University School of Engineering and Digital Sciences, 2021-09-16) Rakhimzhanova, AigerimSand production is particularily prominent in sandstone reservoirs, which are common to observe in the majority of oil and gas fields. When sand particles start to erode from weak sandstone formations for different reasons, their impact could lead to the decline of the production flow rate and equipment degradation, which will results in a huge economical loss. In some cases, it results in the end of production life of a well and reservoir. The key to overcome this problem and achieve accurate prediction of sand production may lie in the understanding of the cause of sanding mechanism. The current numerical approaches to predict the sanding mechanism are based on continuum and non-continuum models. The majority of developed models are based on the continuum approach, while a few discontinuum-based (DEM – Discrete Element Method) have been developed in the last two decades. Sand production is a dynamic and continuous process, which starts from microscopic scales where the rock is discontinuous in nature. It is impossible to capture local discontinuous phenomena using continuum-based models. The DEM models can capture the interaction and motion of each sand grain, the failure micro mechanism in a dynamic process at micro and macro scales, which makes it possible to simulate the sanding phenomena. In this research the DEM is firstly used for the rock characterization, where a simple 3D bond contact model for cemented sandstone material is developed by modifying the previous existing JKR (Johnson-Kendall-Roberts) model for auto-adhesive silt size sand particles, and the model parameter is the bond strength in terms of the interface energy. The material properties of the synthetic sandstone specimens equivalent to the Ustyurt-Buzachi Sedimentary Basin core samples were reproduced for the numerical specimens and the triaxial compression test results show that the numerically simulated macroscopic response is in good agreement with the experimental results of the cemented sandstone. The main aim of this research is to develop the sample preparation procedure/method with physical perforation penetration and sand production modelling in a periodic cell and by developing and using the combined 3D CFD-DEM-IBM modelling techniques (CFD – Computational Fluid Dynamics; IBM – Immersed Boundary Method). The application of the IBM is proposed to simulate the complex interaction between the geometry of the cased horizontal well completion opening and the weakly cemented sandstone under the overburden pressure and drawdown. The capability of developed methods to capture sand arching, damage zone (due to the perforation penetration) and sanding mechanism (erosion near the perforation hole) due to the pressure drawdown are presented. This study shows the mechanism of sand production in a bottom-up approach in the first 0.1 sec of sanding initiation immediately after the perforation penetration in oil wells, which will help engineers to better understand the sanding mechanism at the micro levels and how the problem of sanding can eventually be overcome though better insight into the phenomenon.Item Open Access 3D HIERARCHICAL NANOCRYSTALLINE CUS CATHODE FOR LITHIUM BATTERIES(Materials, 2021-03-26) Kalimuldina, Gulnur; Nurpeissova, Arailym; Adylkhanova, Assyl; Issatayev, Nurbolat; Adair, Desmond; Bakenov, ZhumabayConductive and flexible CuS films with unique hierarchical nanocrystalline branches directly grown on three-dimensional (3D) porous Cu foam were fabricated using an easy and facile solution processing method without a binder and conductive agent for the first time. The synthesis procedure is quick and does not require complex routes. The structure and morphology of the as-deposited CuS/Cu films were characterized by X-ray diffraction and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy and transmission electron spectroscopy, respectively. Pure crystalline hexagonal structured CuS without impurities were obtained for the most saturated S solution. Electrochemical testing of CuS/Cu foam electrodes showed a reasonable capacity of 450 mAh·g−1 at 0.1 C and excellent cyclability, which might be attributed to the unique 3D structure of the current collector and hierarchical nanocrystalline branches that provide fast diffusion and a large surface area.Item Metadata only 3D intermetallic anodes for Lithium-ion batteries(2018-12-31) Murat, E.; Adi, A.; Bakenov, Z.; Nurpeissova A.; Nurpeissova, A.Abstract Recently various three-dimensional (3D) battery architectures have emerged as a new direction for powering microelectromechanical systems and other small autonomous devices. The ultimate goal of such unique battery architecture is to obtain a high surface area substrate coated with thin layers of anode, electrolyte and cathode materials to enhance the energy density per foot print area, while maintaining a large power density. In view of this, attempts on formulating 3D structured anode utilizing widely available three dimensional mesoporous nickel foam and tin alloy matrix are reportedItem Open Access 3D MULTIDISCIPLINARY AUTOMATED DESIGN OPTIMIZATION TOOLBOX FOR WIND TURBINE BLADES(Processes, 2021-04) Sagimbayev, Sagi; Kylyshbek, Yestay; Batay, Sagidolla; Zhao, Yong; Fok, Sai; Lee, Teh SooThis paper presents two novel automated optimization approaches. The first one proposes a framework to optimize wind turbine blades by integrating multidisciplinary 3D parametric modeling, a physics-based optimization scheme, the Inverse Blade Element Momentum (IBEM) method, and 3D Reynolds-averaged Navier–Stokes (RANS) simulation; the second method introduces a framework combining 3D parametric modeling and an integrated goal-driven optimization together with a 4D Unsteady Reynolds-averaged Navier–Stokes (URANS) solver. In the first approach, the optimization toolbox operates concurrently with the other software packages through scripts. The automated optimization process modifies the parametric model of the blade by decreasing the twist angle and increasing the local angle of attack (AoA) across the blade at locations with lower than maximum 3D lift/drag ratio until a maximum mean lift/drag ratio for the whole blade is found. This process exploits the 3D stall delay, which is often ignored in the regular 2D BEM approach. The second approach focuses on the shape optimization of individual cross-sections where the shape near the trailing edge is adjusted to achieve high power output, using a goal-driven optimization toolbox verified by 4D URANS Computational Fluid Dynamics (CFD) simulation for the whole rotor. The results obtained from the case study indicate that (1) the 4D URANS whole rotor simulation in the second approach generates more accurate results than the 3D RANS single blade simulation with periodic boundary conditions; (2) the second approach of the framework can automatically produce the blade geometry that satisfies the optimization objective, while the first approach is less desirable as the 3D stall delay is not prominent enough to be fruitfully exploited for this particular case studyItem Open Access 3D MULTIDISCIPLINARY AUTOMATED DESIGN OPTIMIZATION TOOLBOX FOR WIND TURBINE BLADES(MDPI AG, 2021-03-26) Sagimbayev, Sagi; Kylyshbek, Yestay; Batay, Sagidolla; Zhao, Yong; Fok, Sai; Soo Lee, TehThis paper presents two novel automated optimization approaches. The first one proposes a framework to optimize wind turbine blades by integrating multidisciplinary 3D parametric modeling, a physics-based optimization scheme, the Inverse Blade Element Momentum (IBEM) method, and 3D Reynolds-averaged Navier-Stokes (RANS) simulation; the second method introduces a framework combining 3D parametric modeling and an integrated goal-driven optimization together with a 4D Unsteady Reynolds-averaged Navier-Stokes (URANS) solver. In the first approach, the optimization toolbox operates concurrently with the other software packages through scripts. The automated optimization process modifies the parametric model of the blade by decreasing the twist angle and increasing the local angle of attack (AoA) across the blade at locations with lower than maximum 3D lift/drag ratio until a maximum mean lift/drag ratio for the whole blade is found. This process exploits the 3D stall delay, which is often ignored in the regular 2D BEM approach. The second approach focuses on the shape optimization of individual cross-sections where the shape near the trailing edge is adjusted to achieve high power output, using a goal-driven optimization toolbox verified by 4D URANS Computational Fluid Dynamics (CFD) simulation for the whole rotor. The results obtained from the case study indicate that (1) the 4D URANS whole rotor simulation in the second approach generates more accurate results than the 3D RANS single blade simulation with periodic boundary conditions; (2) the second approach of the framework can automatically produce the blade geometry that satisfies the optimization objective, while the first approach is less desirable as the 3D stall delay is not prominent enough to be fruitfully exploited for this particular case study.Item Open Access A 3d multidisciplinary automated design optimization toolbox for wind turbine blades based on ns solver and experimental data(Nazarbayev University School of Engineering and Digital Sciences, 2018) Sagimbayev, SagiThis thesis attempts to develop a framework to optimize wind turbine blades automatically by a multidisciplinary 3D modeling and simulation methods. The original NREL Phase VI wind turbine blade and its experimental measurements are used to validate the Computational Fluid Dynamics (CFD) model developed in ANSYS Fluent and based on the 3D Navier-Stokes (NS) solver with a realizable k-epsilon turbulence model, which is later used in the automation process. The automated design optimization process involves multiple modeling and simulation methods using Solidworks and ANSYS Mesher and ANSYS Fluent NS solver, which are integrated and controlled through Matlab by implementing the scripting capabilities of each software package. Then all scripts are integrated into one optimization cycle, with its optimization objective being the highest mean value of 3D Lift/Drag ratio (3DLDR) across the blade. A 3DLDR distribution across the blade can be calculated by the Inverse Blade Element Momentum (IBEM) Method based on experimental measurements. The optimization process is performed to find optimized twist angles across the blade using the Angle of Attack (AOA) with the highest 3DLDR as a reference, in order to 3 achieve the optimization objective. Therefore, the automatic optimization framework is based on 3D solid modeling and 3D aerodynamic simulation and guided by IBEM and experimental data. Thus the design tool is capable of exploiting the 3D stall delay of blades designed by the traditional 2D BEM method to enhance their performances. It is found that this automated framework can result in optimized blade geometries with the improvement of performance parameters compared to the original ones.Item Metadata only 3D particle size distribution of inter-ground Portland limestone/slag cement from 2D observations: Characterization and distribution evaluation(Construction and Building Materials, 2017-08-30) Sun, Hongfang; Fan, Bing; Memon, Shazim Ali; Cen, Zhuo; Gao, Xiaobin; Lin, Bin; Liu, Bing; Li, Dawang; Xing, Feng; Zhang, Xiaogang; Hongfang, SunAbstract In this research, the particle size distribution (PSD) of different components in inter-ground Portland limestone cement (PLC) and limestone-slag cement (PLC-S) was characterization by using an electron microscopy approach. Firstly, the 2D PSD of limestone, slag, and Portland cement (OPC) was determined by means of image analysis. Based on the 2D data and using a discrete stereology, the 3D size distribution was reconstructed. Finally, the PSD of inter-ground mixtures was assessed by using a compressible packing model. The results showed that the addition of limestone in cement makes the OPC component coarser and distribution broader; meanwhile, the limestone particles were found to be finer than the OPC particles. The addition of both limestone and slag (PLC-S) were found to further broaden the PSD of OPC component and limestone component with the mean size of particles increased in the following order (limestoneItem Open Access 3D PRINTING OF BIOCOMPATIBLE CRYOGELS FOR BONE TISSUE ENGINEERING(School of Engineering and Digital Sciences, 2023) Moazzam, MuhammadNatural biopolymers are highly valued and commonly utilized in tissue engineering to create scaffolds that support living cells. This is due to their exceptional biocompatibility and the fact that their degradation rate can be controlled. However, the shape and average pore size are crucial in biological processes that influence the kinetics of cell proliferation and tissue regeneration processes linked to the production of extracellular matrix. For the construction of high-accuracy hydrogel scaffolds via 3D printing, the shear thinning characteristics of the bioinks used frequently result in morphological compromises like smaller pore diameters. Here, we introduced a new mixture of gelatin and oxidized alginate (Gel/OxAlg) that has been optimized for use in 3D printing and cryogelation techniques. This composite formulation allows for the creation of highly porous and biocompatible hydrogel scaffolds with extra-large pore sizes (d > 100 μm) using a combination of 3D printing and cryogelation techniques. These scaffolds have the potential to serve as a platform for various tissue engineering applications, and their morphological properties and cell viability data can be tailored accordingly. Overall, our approach offers a simple and cost-effective method for constructing hydrogel scaffolds with high accuracy.Item Restricted 3D PRINTING OF GELATIN/OXIDIZED CARBOXYMETHYL CELLULOSE SCAFFOLDS WITH GRADIENT POROSITY FOR BONE TISSUE REGENERATION APPLICATIONS(Nazarbayev University School of Engineering and Digital Sciences, 2024-04-23) Dyussenbinov, AibekThis master thesis investigates the development and evaluation of 3D-printed gelatin/oxidized carboxymethyl cellulose (OxCMC) scaffolds with gradient porosity for applications in bone tissue regeneration. Recognizing the limitations of current bone repair methodologies, this research aims to mimic the natural extracellular matrix of bone through advanced scaffold engineering techniques. The thesis explores the synthesis and optimization of bioinks from gelatin and OxCMC, chosen for their biocompatibility, biodegradability, and mechanical properties conducive to 3D printing. Through extensive experimentation, including rheological tests, Fourier-transform infrared spectroscopy (FTIR) analysis, and scanning electron microscopy (SEM) imaging, scaffold formulations were tailored to achieve desired porosity gradients and mechanical strength. The novel approach of utilizing a complex 3D printing model with different pinheads for varying ink compositions is highlighted as a key innovation. This method allowed for the creation of scaffolds that not only support cell adhesion and proliferation but also replicate the porosity gradient inherent to natural bone, thereby addressing a critical aspect of scaffold design in bone tissue engineering. Results indicated a direct correlation between the polymer content in the scaffolds and their swelling ability, degradation rates, and mechanical properties. Scaffolds with higher polymer content showed less swelling but greater mechanical strength, aligning with the requirements for supporting bone tissue regeneration. The gradient scaffold, in particular, demonstrated a balance between swelling behavior and mechanical integrity, suggesting its suitability for bone tissue engineering applications. This research contributes to the field of regenerative medicine by offering a promising scaffold design strategy for bone tissue regeneration. By closely mimicking the structural and mechanical properties of natural bone, the developed scaffolds hold potential for improving the outcomes of bone repair and regeneration procedures, paving the way for future clinical applications.Item Embargo 3D-PRINTED OSTEOCHONDRAL GRAFTS AND THEIR CHARACTERIZATION(Nazarbayev University School of Engineering and Digital Sciences, 2024-04-25) Effanga, Victoria EffiongThe osteochondral (OC) interface is a complex tissue with a hierarchical structure found at the ends of the bones of the knee joint consisting of a layer of soft tissue (cartilage) overlaying hard tissue in the subchondral bone. It exhibits a gradient of its constituents, especially in terms of mineral concentration, cell phenotype, collagens, and glycosaminoglycans, with a thickness of around 0.5 mm. The tidemark, a critical yet often overlooked component of OC interface tissue, plays a pivotal role in maintaining tissue function by acting as a barrier against vascular invasion of the cartilage. Fabricating scaffolds that mimic the complex physiology and functionalities of the OC tissue within the physiological thickness remains a challenge. This study aimed at fabricating a unitary composite scaffold that is similar of the OC interface in terms of distribution of its mineral content. It was hypothesized that the interface formed between the layers of the multilayer graft will possess a thickness of hydroxyapatite (HAP) gradient similar to that seen at the native rabbit OC tissue. To test the hypothesis, a multilayer composite OC graft was fabricated using gelatin and oxidized alginate (OXA) compositions with and without HAP for the bone and cartilage regions, respectively, and a gradient of HAP was formed in between. The two layers were formed using a 3D bioprinting method, while a porous electrospun mesh of polycaprolactone was placed in the graded region between cartilage and bone to represent the tidemark. The change in mineral content across the rabbit OC interface tissue and the OC graft interface was investigated using energy dispersive X-ray (EDX) and micro computed tomography (CT) characterization. The printability of the bioinks was verified by a strain sweep test, and volumetric expansion of both inks, with and without HAP, was examined using a swelling test. Findings revealed that both bioinks exhibited a shear thinning behavior. In addition, swelling test showed that both inks possessed similar volumetric expansion when immersed in water, demonstrating its feasibility to be used as a defect filler. EDX scan for calcium (Ca) and phosphorus (P) verified the gradient of mineral in both OC grafts and native rabbit OC tissue. The CT characterization verified a HAP gradient created in the OC graft within 168m thickness similar to the mineral gradient thickness determined for rabbit OC interface. Furthermore, the electrospun membrane was found to have pore diameters less than 1m that is sufficient to prevent vascular invasion of the articular cartilage tissue. Overall, the OC graft fabricated using combined bioprinting and electrospinning techniques demonstrated a potential to serve as a biomimetic hydrogel filler for regenerating OC defects to restore the function of the knee joint. It is expected that the proposed OC graft will be effectively used to address a significant clinical problem that affects millions of people, with significant societal and economic impacts.Item Restricted 60 GHZ PHASED ARRAY PHASE SHIFTER DESIGN FOR 5G APPLICATION(Nazarbayev University School of Engineering and Digital Sciences, 2024-04-24) Shaimerden, YernurThe purpose of this research work is to design a phase shifter and antenna for integration into a 60 GHz phased array transceiver designed specifically for 5G applications. A phased array transceiver consists of an active device (e.g. amplifier), phased array matrix, and antenna. This thesis focuses on the design of a 60 GHz phased antenna array with no active device. A butler matrix is implemented for the phased array matrix. In the methodology part, the development process of the butler matrix and patch antenna is presented. In this study, various types of beamforming networks are examined and written in the literature review section. The fundamental components of the Butler matrix are systematically designed, showing each step of the process. At the implementation step, CST software was used. Design is implemented on a substrate material known as Rogers RT/duroid 5880, with a 0.127 mm thickness. The results indicate the good reflection coefficient at the operating frequency of 60 GHz. Proposed design with patch antenna results in four orthogonal beams, each directed at +5°, +37°, -37°, and −5°.Item Open Access A BEM-ISOGEOMETRIC method for the ship wave-resistance problem(Ocean Engineering, 2012) Belibassakis, K.A.; Gerostathis, Th.P.; Kostas, Konstantinos; Politis, C.G.; Kaklis, P.D.; Ginnis, A.I.; Feurer, C.In the present work IsoGeometric Analysis is applied to the solution of the Boundary Integral Equation associated with the Neumann-Kelvin problem and the calculation of the wave resistance of ships. As opposed to low-order panel methods, where the body is represented by a large number of quadrilateral panels and the velocity potential is assumed to be piecewise constant (or approximated by low degree polynomials) on each panel, the isogeometric concept is based on exploiting the same NURBS basis, used for representing exactly the body geometry, for approximating the singularity distribution (and, in general, the dependent physical quantities). In order to examine the accuracy of the present method, numerical results obtained in the case of submerged and surface piercing bodies are * Corresponding author. Tel: (+30) 2107721138, Fax: (+30) 2107721397, e-mail: kbel@fluid.mech.ntua.gr 2 compared against analytical solutions, experimental data and predictions provided by the low-order panel or other similar methods appeared in the pertinent literature, illustrating the superior efficiency of the isogeometric approach. The present approach by applying Isogeometric Analysis and Boundary Element Method to the linear NK problem has the novelty of combining modern CAD systems for ship-hull design with computational hydrodynamics tools.