PHYSICAL LAYER SECURITY USING MASSIVE MIMO AND RIS TECHNOLOGY

Massive Multiple-Input-Multiple-Output (MIMO) systems and Reconfigurable Intellegent Surfaces (RIS) are considered to be the key technologies for next generations wireless communication, which are aimed to achieve higher data rates, massive connectivity and more secure data transmission. Combined use of these technologies together with artificial noise (AN) gives high hopes for strengthening Physical Layer Security (PLS) in wireless networks. This capstone work considers configuring phase shifts of RIS such that the impact of AN is maximized for illegitimate user, while its impact on legitimate user is not significant compared to the actual signal received from base station. In the proposed system model, some antennas is dedicated for AN and the rest are transmitting the actual data. The main objective of this model is to maximize Secrecy Capacity (SC) of the communication link, while satisfying the users’ quality of service (QoS). To achieve that, we optimize the phase shifts of RIS and find the optimal number of base station antennas transmitting AN. Obtained results validate theoretical concepts and show that proposed RIS-assisted Massive MIMO incorporated with AN transmission can be an effecting tool for establishing and improving PLS in wireless communication

NUMERICAL STUDY ON PUNCHING SHEAR RESPONSES OF FLAT PLATE STRUCTURES STRENGTHENED WITH ENGINEERED CEMENTITIOUS COMPOSITES

Flat plates are one of the conventional structural systems found in the construction sector due to their several advantages including simplicity, lowered expenses, and architectural mobility. However, the flat plate systems are vulnerable to punching shear failures which happen suddenly and catastrophically. Thus, it is crucial to develop strengthening techniques to augment the punching shear resistance of such structures. The strengthening techniques include shear reinforcement, drop panels, and column capital. One of the modern techniques for retrofitting flat plates is the use of engineered cementitious composites (ECC), applied as thin layers on both sides of slab surfaces. There are only limited studies that examined the response of flat plates with ECC retrofitting that improved the punching shear resistance. Most previous research has employed experimental methods to assess the impact of ECC on the punching shear capacity of the slab considering limited design parameters due to economic constraints. Furthermore, some inconsistent results were reported from two separate studies. In one study, the tension side retrofitting with ECC showed a noticeable contribution to punching shear resistance but in another, it was insignificant. Therefore, it is necessary to investigate the behavior of flat plates subjected to concentric vertical loading and examine if the ECC is valid as a retrofitting technique through numerical simulations considering various design parameters. This thesis evaluates the impact of the ECC strengthening technique on the punching shear response of flat plate structures. For that purpose, analytical models of the interior slab-column assemblage were developed in finite element software ABAQUS. First, the model was calibrated from test results in the literature. The numerical simulations were carried out on flat plate models subjected to gravity loading to investigate the global response of the flat plate and its failure mechanism. The contributions of concrete and ECC were determined to examine the effectiveness of ECC strengthening. Moreover, the cracking pattern was visualized by presenting the contour plots that displayed the flat plate model’s maximum principal equivalent plastic strain. In this thesis, the main study parameter was the placement of the retrofitting: on the tension, compression, and both slab surfaces. The other study parameters include compressive strength, thickness, and width of the ECC. The numerical study results showed that the punching shear behavior of flat plates was improved with the application of the ECC retrofitting technique. The addition of a thin layer of ECC on the compression side of the slab provided a direct shear strength contribution near the column face, therefore no improvement was observed as the width of the ECC increased. Moreover, the deformation capacity of the slab improved with low-strength ECC retrofitting of the slab on the compression side, whereas normal-strength ECC showed a more brittle response. The addition of a thin layer of ECC on the tension side of the slab has no direct shear force resistance contribution. However, it can lower the neutral axis and enlarge the concrete compression zone, increasing the concrete contribution to the punching shear strength. This increase is only effective if the ECC width is large enough to cover the punching cracking region. The double-sided retrofitting can significantly increase the strength and deformation capacity of the flat plate, resulting in a better performance under punching load. However, it must be noted that the strength does not result from the superposition of strengths of one-sided retrofitting since peak strengths occur at different displacements for ECC retrofitting on the tension and compression sides. Overall, the parametric results revealed that the higher the compressive strength and thickness of the ECC, the greater the punching shear response of the slab. Accordingly, the compressive strength of 20 MPa, thickness of 30 mm, and width of full slab length applied on both sides of the slab were determined to be optimal parameters for improving both strength and deformation capacity

STUDYING EFFECTS OF ZEB1 KO IN TRIPLE-NEGATIVE BREAST CANCER CELLS MDA-MB-231

One of the main problems in cancer therapy is the resistance of cancer cells to various anticancer drugs. Targeted anticancer drugs categorized on their effect to cancer hallmarks. According to the principles of functioning, anticancer drugs are divided into: growth factor inhibitors, pro-apoptotic drugs, immune checkpoint inhibitors, telomerase inhibitors, inhibitors of VEGF signaling, PARP inhibitors, metastasis suppressors, inhibitors of glycolysis and aerobic metabolism, inactivators of drug efflux and detoxication machinery etc (Dembic, 2020). The main mechanisms of resistance to them are: increased DNA repair, increased efflux of drugs, enhanced metabolism of drugs, growth factor compensation, genetic and epigenetic factors modification (Holohan et al., 2013; Kachalaki et al., 2016; Mansoori et al., 2017). One of these mechanisms which helps to avoid drugs effect is epithelial-mesenchymal transition (EMT) (Hashemi et al., 2022). EMT can give resistance to such drugs as doxorubicin via AMPK overexpression (Andugulapati et al., 2022), cisplatin via 14,15-epoxyeicosatrienoic acid (Luo et al., 2018), tamoxifen via Cx43 loss (Wu et al., 2021) etc. Also EMT is activated for metastasis of cancer cells and as a result, unfavorable prognosis in treatment. That’s why EMT has particular importance in treating of triple-negative breast cancer (TNBC) (Grasset et al., 2022) the most aggressive type of breast cancer. TNBC is characterized by high heterogeneity and the absence of major target receptors: estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2). Many research groups reported about mesenchymal gene expression in TNBC, suggesting EMT (Jang et al., 2015). One of the regulators of EMT are Zinc finger E-Box binding homeobox 1 (ZEB1), proteins that encoded by ZEB1 gene, located on chromosome 10p11.2 (Williams et al., 1992). Main function of this transcription factor is linked to the promotor region of the epithelial cell marker protein E-cadherin, causing the cells to lose their epithelial properties (Larsen et al., 2016). The importance of ZEB1 in TNBC therapy is due to its ability to promote chemoresistance through various mechanisms such as activated ataxia-telangiectasia mutated (ATM) kinase expression by forming a ZEB1/p300/PCAF complex (X. Zhang et al., 2018) or by repression of E-cadherin in AR-negative docetaxel-resistant sublines (Hanrahan et al., 2017). This work shows the effect of a knockout of the gene responsible for the synthesis of ZEB1 using the CRISPR-CAS-9 technology

PERFORMANCE COMPARISON OF ENSEMBLE ALGORITHMS WITH NEURAL NETWORKS BASED METHODS FOR SMALL-SIGNAL MODELING OF GaN HEMTs

This thesis investigates and compares the ensemble modeling methods and neural networks approaches for small-signal modeling of Gallium Nitride High Electron Mobility Transistors (GaN HEMTs). Specifically, ensemble methods are represented by Random Forests and eXtreme Gradient Boosting (XGBoost) algorithms, while neural networks techniques consist of Adaptive Neuro-Fuzzy Inference Systems (ANFIS) and Feed-forward Artificial Neural Networks (FFANN). To carry out the research to a higher standard, this work utilizes two distinct GaN HEMT devices. The first, a GaN HEMT grown on Diamond, is characterized by a smaller dataset and fewer modeling parameters. Conversely, the second device, a GaN HEMT on Silicon, possesses a larger dataset and a greater number of training parameters. Furthermore, the model performance is meticulously evaluated using Mean Square Error (MSE), Mean Absolute Error (MAE), and the coefficient of determination (R2). Findings suggest that ensemble models exhibit enhanced stability and greater robustness against overfitting. While the neural networks-based models demonstrate superior accuracy and a more streamlined development process. This research provides critical guidance for researchers and engineers in selecting the most suitable modeling approach for certain GaN HEMT devices. The choice hinges on a careful balance between prioritizing accuracy, mitigating overfitting, and managing the complexities inherent in model development

Performance Evaluation for Reconfigurable Intelligent Surfaces-enabled Terahertz Communications

The terahertz (THz) frequency band is attractive for the development of high data rate, large capacity, and low latency sixth generation (6G) wireless communications. A possible solution to the issues of excessive propagation losses in the THz band is the incorporation of reconfigurable intelligent surfaces (RISs), which are able to sensibly adjust the reflecting elements and improve the received power strength in the network. Moreover, different multiple access techniques can be considered to effectively allocate the power and spectrum resources among the users. Therefore, this work evaluates the performance of a RIS-aided Non Orthogonal Multiple Access (NOMA) THz system model with multiple users. The network resource allocation schemes are compared in terms of the Sum Rate maximization and different RIS deployment scenarios are discussed. The simulation results confirm the analytical derivations and present the RIS-THz link performance in various conditions

POLYCAPROLACTONE AND POLYETHYLENE TEREPHTHALATE NANOFIBER GRAFTS FOR ANTERIOR CRUCIATE LIGAMENT TISSUE APPLICATIONS

The present study hypothesizes that the produced graft from two different polymers (PCL&PET) with aligned-bimodal and unaligned-unimodal fibers can mimic the properties of healthy and injured ACL rabbit tissue, respectively. To observe if the created graft is useful to replicate the conditions for ACL restoration, primary fibroblasts taken from rabbit’s ACL tissue were seeded on two different types of scaffolds: aligned fibers, which represent healthy ACL tissue, and unaligned, which represent injured ACL tissue. After cell seeding, the evaluation of cell proliferation and DNA were evaluated in 3-time points from day 0 to day 7

FINAL PROJECT REPORT DOCUMENT– SPRING 2024

The NU Life Hub project aims to address the fragmentation of information and resources for Nazarbayev University (NU) students by offering a centralized platform designed specifically for their needs. The project addresses students' challenges in finding and participating in campus activities, accessing a convenient marketplace to fulfill their needs, and staying informed about various campus events. The NU Life Hub solution will be a comprehensive platform that combines event management, marketplace, and community engagement functions to improve the overall university experience. During the project, extensive research was conducted to understand existing solutions and approaches to address similar challenges university communities face. This analysis informed the design and development of the NU Life Hub, ensuring that best practices were embedded into the platform and critical challenges were effectively addressed

NEURAL NETWORK BASED FILTER MODELING AND OPTIMIZATION FOR 5G AND BEYOND APPLICATIONS

Designing high-performance microwave and millimeter-wave filters is difficult because small changes in geometric dimensions and electrical sizes can significantly affect the filter’s characteristic. Typically, in filter design, the initial values of design variables are optimized to achieve the desired performance. In the field of high-frequency RF device modeling, the use of machine learning (ML) through artificial neural networks (ANN) has gained popularity in recent years. Unlike other RF modeling techniques, ANN-based models require training with sufficient datasets to achieve the desired accuracy level. The input data could be the device’s dimensions, while the output could be the S-parameters. Once trained, the ANN-based model can provide EM-level accuracy and equivalent-circuit-level speed. Additionally, it is highly scalable, allowing for the introduction of more input parameters to make the model more versatile and complex. Therefore, the ANN-based model is an excellent option for high-frequency RF modeling compared to other techniques. The main objective of this research project is to develop an AAN that can be used in design of RF Filters

MOTIVATION AND REMOTE WORKING: CASE STUDY OF ONE NATIONAL HIGHER EDUCATION INSTITUTION IN KAZAKHSTAN

The COVID19 pandemic has upended our life in many aspects. When the virus raged in 2020, many countries announced a state of emergency and launched a complete lockdown. In the conditions of the severe lockdown, social isolation and remote working came to the fore and were applied by all organizations, including higher education institutions. Kazakhstani institutions also pursued this route by launching remote work options for all university staff. This single descriptive qualitative case study explores motivation of university staff who worked remotely during the period of pandemic. Overall, 15 university staff members were interviewed. Data analysis revealed some fluctuations in motivation of university staff when they worked remotely during the pandemic. Along with this, it was clear that working remotely affected the perception of work and work setting by revealing both advantages and disadvantages. Thus, this research fills in the gap in the previous literature on motivation, focusing particularly on the period of the pandemic and remote working by bringing in the perspective of university staff

WOMEN’S LEADERSHIP AND MOTHERHOOD IN HIGHER EDUCATION: A CASE STUDY OF WOMEN ADMINISTRATORS IN A REGIONAL UNIVERSITY IN EAST KAZAKHSTAN

This research explores the experiences of mothers who hold administrative positions in a regional university in East Kazakhstan. The study examines the challenges and benefits of balancing motherhood and administrative duties in higher education, aiming to inform the development of supportive structures for these women. This study used a qualitative method with semi-structured interviews as the data collection instrument. It delves into the challenges these mother administrators face, including work-life conflicts, workplace dynamics, and access to institutional support. The study also identifies positive aspects of having the dual role, including personal fulfillment, career advancement, and contributions to diversity within the institution. The findings highlight the significance of implementing flexible work schedules, providing leadership training and coping strategies to support female administrators. These measures can contribute to increasing job satisfaction, improving retention rates, and fostering a more inclusive and supportive work environment. This study adds to the existing body of knowledge on female leadership in higher education by providing practical insights for educational institutions to enhance their support systems for female administrators