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Socio-Technical Perspective For Electronic Tax Information System In Tanzania, Lucas Ngowi, Ellen Kalinga Jul 2021

Socio-Technical Perspective For Electronic Tax Information System In Tanzania, Lucas Ngowi, Ellen Kalinga

Tanzania Journal of Engineering and Technology (TJET)

Socio-technical systems theory has rarely been used by system architects in setting up computing systems. However, the role of socio-technical concepts in computing, which is becoming social in nature, has made the concepts more relevant and commercial. Tax information systems are examples of such systems because they are influenced by external variables such as the political environment, technological trends, and social environment, introducing complexity in their deployment and determining the type of e-services and their delivery to a diverse group of people. It was observed that in Tanzania there is resistance, reluctance and minimal use of electronic tax system because …

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Fully Coupled Internal Radiative Heat Transfer For The 3d Material Response Of Heat Shield, Raghava S. C. Davuluri, Rui Fu, Kaveh A. Tagavi, Alexandre Martin Jul 2021

Fully Coupled Internal Radiative Heat Transfer For The 3d Material Response Of Heat Shield, Raghava S. C. Davuluri, Rui Fu, Kaveh A. Tagavi, Alexandre Martin

Mechanical Engineering Faculty Publications

The radiative transfer equation (RTE) is strongly coupled to the material response code KATS. A P-1 approximation model of RTE is used to account for radiation heat transfer within the material. First, the verification of the RTE model is performed by comparing the numerical and analytical solutions. Next, the coupling scheme is validated by comparing the temperature profiles of pure conduction and conduction coupled with radiative emission. The validation study is conducted on Marschall et al. cases (radiant heating, arc-jet heating, and space shuttle entry), 3D Block, 2D IsoQ sample, and Stardust Return Capsule. The validation results agree well for …

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Interaction Of A Shock Wave With A Particle Curtain, Daniel M. Freelong Jul 2021

Interaction Of A Shock Wave With A Particle Curtain, Daniel M. Freelong

Mechanical Engineering ETDs

This thesis presents an experimental study of the interaction of a normal shock wave with a sparse curtain of particles. Soda lime particles with a nominal diameter of 40 micrometers are used to form the curtain. A high speed camera captured several segments of the particle curtain flow from the front view, including the early formation stages. The frames from the video segments were then extracted into individual sequential images. Properties were found using the images such as the velocity fields, time evolution of multiphase Atwood number, and perturbation growth. Volume fractions were derived from mass discharge measurements and particle …

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Main Factors That Influence The Thermal Stress State Of Piston Engine Parts, J F. Ismatov, A I. Yangibayev, N V. Vadulina, A A. Jalilov Jul 2021

Main Factors That Influence The Thermal Stress State Of Piston Engine Parts, J F. Ismatov, A I. Yangibayev, N V. Vadulina, A A. Jalilov

Technical science and innovation

The development of a holistic, effective, and scalable structure of economic management, as well as the introduction of a program to improve the technical level and efficiency of machinery, are two of the most important concepts for the deep reconstruction of the Republic of Uzbekistan's economic process. Vehicles with diesel engines are gradually being introduced to our country's car fleet. Modern diesel engines are being developed by boosting them: increasing the average effective pressure and speed. Therefore, high reliability and service life, fuel efficiency and environmental performance are the main criteria for their quality. Forcing diesels leads to an increase …

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Dynamic Aeroelastic Response Of Stall-Controlled Wind Turbine Rotors In Turbulent Wind Conditions, Sara Jalal, Fernando L. Ponta, Apurva Baruah, Anurag Rajan Jul 2021

Dynamic Aeroelastic Response Of Stall-Controlled Wind Turbine Rotors In Turbulent Wind Conditions, Sara Jalal, Fernando L. Ponta, Apurva Baruah, Anurag Rajan

Michigan Tech Publications, Part 1

With the current global trend of the wind turbines to be commissioned, the next generation of state-of-the-art turbines will have a generating capacity of 20 MW with rotor diameters of 250 m or larger. This systematic increase in rotor size is prompted by economies-of-scale factors, thereby resulting in a continuously decreasing cost per kWh generated. However, such large rotors have larger masses associated with them and necessitate studies in order to better understand their dynamics. The present work regarding the aeroelastic behavior of stall-controlled rotors involves the study of the frequency content and time evolution of their oscillatory behavior. A …

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Experimental Study Of Drying Yacon Tubers, U K. Khujakulov, Sh A. Sultanova, J E. Safarov Jul 2021

Experimental Study Of Drying Yacon Tubers, U K. Khujakulov, Sh A. Sultanova, J E. Safarov

Technical science and innovation

This study discusses the method and experimental drying unit for drying yacon tubers at different temperatures. And also the scheme of experimental drying unit is given, which controls temperature, speed of warm air and shows the mass of dried material. The cross-sectional area of the flow in the tunnel is 20×20 cm, the thermal air passed horizontally through a chute with holes and a surface area of 12×12 cm. The exhaust gas did not circulate in this experiment. The accuracy of the temperature control system was 0.1 °C, the weight control system 0.1 g. The variation of moisture ratio depending …

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Causes Of Rolling Stock Brake Equipment Failures, O T. Kasimov, Sh I. Mamaev, A V. Grishenko Jul 2021

Causes Of Rolling Stock Brake Equipment Failures, O T. Kasimov, Sh I. Mamaev, A V. Grishenko

Technical science and innovation

Reliable operation of the rolling stock and devices of railway transport is the basis for ensuring the throughput and transport capacity of railways, as well as safety.The article is dedicated to the current day of the topical topic: increasing the reliability and analyzing the causes of brake equipment failures in locomotives in the conditions of JSC "Uzbekistan Temir Yollari".On the rolling stock of railways of JSC "Uzbeksiton Temir Yullari" five types of brakes are used: parking (manual), pneumatic, electro-pneumatic, electric (dynamic and reversible), magnetic-rail and are used as additional to EPT.The article presents an analysis of the …

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Lagrangian And Eulerian Accelerations In Turbulent Stratified Shear Flows, Frank G. Jacobitz, Kai Schneider Jul 2021

Lagrangian And Eulerian Accelerations In Turbulent Stratified Shear Flows, Frank G. Jacobitz, Kai Schneider

School of Engineering: Faculty Scholarship

The Lagrangian and Eulerian acceleration properties of fluid particles in homogeneous turbulence with uniform shear and uniform stable stratification are studied using direct numerical simulations. The Richardson number is varied from Ri=0, corresponding to unstratified shear flow, to Ri=1, corresponding to strongly stratified shear flow. The probability density functions (pdfs) of both Lagrangian and Eulerian accelerations have a stretched-exponential shape and they show a strong and similar influence on the Richardson number. The extreme values of the Eulerian acceleration are stronger than those observed for the Lagrangian acceleration. Geometrical statistics explain that the magnitude of the Eulerian acceleration is larger …

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Reduced-Order Modeling Of Loosening In Bolted Joints And Dynamic Interactions Between Axially Aligned Threaded Joints, Sandro Aldana Jul 2021

Reduced-Order Modeling Of Loosening In Bolted Joints And Dynamic Interactions Between Axially Aligned Threaded Joints, Sandro Aldana

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

Maintaining effective preload in bolted joints is critical for ensuring long-term performance and safety throughout the operation of any assembled structure. The loosening of bolted joints has been studied since the Industrial Revolution, but modeling approaches have only emerged over the past three decades. Although existing approaches are capable of simulating or predicting loosening in a single joint consisting of a single bolt, they are too computationally expensive to be used to model loosening in large structures consisting of many bolts. The objective of this thesis is to construct and employ a reduced-order modeling (ROM) approach that treats the internal …

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Study Of Friction And Wear Effects In Aluminum Parts Manufactured Via Single Point Incremental Forming Process Using Petroleum And Vegetable Oil-Based Lubricants, Jose M. Diabb Zavala, Oscar Martinez-Romero, Alex Elias-Zuniga, Hector Manuel Leija Gutierrez, Alejandro Estrada-De La Vega, Jaime Taha-Tijerina Jul 2021

Study Of Friction And Wear Effects In Aluminum Parts Manufactured Via Single Point Incremental Forming Process Using Petroleum And Vegetable Oil-Based Lubricants, Jose M. Diabb Zavala, Oscar Martinez-Romero, Alex Elias-Zuniga, Hector Manuel Leija Gutierrez, Alejandro Estrada-De La Vega, Jaime Taha-Tijerina

Manufacturing & Industrial Engineering Faculty Publications

This paper focuses on studying how mineral oil, sunflower, soybean, and corn lubricants influence friction and wear effects during the manufacturing of aluminum parts via the single point incremental forming (SPIF) process. To identify how friction, surface roughness, and wear change during the SPIF of aluminum parts, Stribeck curves were plotted as a function of the SPIF process parameters such as vertical step size, wall angle, and tool tip semi-spherical diameter. Furthermore, lubricant effects on the surface of the formed parts are examined by energy dispersive spectroscopy (EDS) and scanning electron microscope (SEM) images, the Alicona optical 3D measurement system, …

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An Economical Method For Securely Disintegrating Solid-State Drives Using Blenders, Brandon J. Hopkins Phd, Kevin A. Riggle Jul 2021

An Economical Method For Securely Disintegrating Solid-State Drives Using Blenders, Brandon J. Hopkins Phd, Kevin A. Riggle

Journal of Digital Forensics, Security and Law

Pulverizing solid-state drives (SSDs) down to particles no larger than 2 mm is required by the United States National Security Agency (NSA) to ensure the highest level of data security, but commercial disintegrators that achieve this standard are large, heavy, costly, and often difficult to access globally. Here, we present a portable, inexpensive, and accessible method of pulverizing SSDs using a household blender and other readily available materials. We verify this approach by pulverizing SSDs with a variety of household blenders for fixed periods of time and sieve the resulting powder to ensure appropriate particle size. Among the 6 household …

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Early-Stage Gas Identification Using Convolutional Long Short-Term Neural Network With Sensor Array Time Series Data, Kai Zhou, Yixin Liu Jul 2021

Early-Stage Gas Identification Using Convolutional Long Short-Term Neural Network With Sensor Array Time Series Data, Kai Zhou, Yixin Liu

Michigan Tech Publications, Part 1

Gas identification/classification through pattern recognition techniques based on gas sensor arrays often requires the equilibrium responses or the full traces of time-series data of the sensor array. Leveraging upon the diverse gas sensing kinetics behaviors measured via the sensor array, a computational intelligence-based meta-model is proposed to automatically conduct the feature extraction and subsequent gas identification using time-series data during the transitional phase before reaching equilibrium. The time-series data contains implicit temporal dependency/correlation that is worth being characterized to enhance the gas identification performance and reliability. In this context, a tailored approach so-called convolutional long short-term memory (CLSTM) neural network …

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In-Vitro And In-Silico Investigations Of Alternative Surgical Techniques For Single Ventricular Disease, Arka Das Jul 2021

In-Vitro And In-Silico Investigations Of Alternative Surgical Techniques For Single Ventricular Disease, Arka Das

Doctoral Dissertations and Master's Theses

Single ventricle (SV) anomalies account for one-fourth of all cases of congenital Heart disease. The conventional second and third stage i.e. Comprehensive stage II and Fontan procedure of the existing three-staged surgical approach serving as a palliative treatment for this anomaly, entails multiple complications and achieves a survival rate of 50%. Hence, to reduce the morbidity and mortality rate associated with the second and third stages of the existing palliative procedure, the novel alternative techniques called “Hybrid Comprehensive Stage II” (HCSII), and a “Self-powered Fontan circulation” have been proposed. The goal of this research is to conduct in-vitro investigations to …

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Liner Sailing Speed Optimization Considering Wind And Waves, Zhaokun Wei, Xinlian Xie, Tiantian Bao Jul 2021

Liner Sailing Speed Optimization Considering Wind And Waves, Zhaokun Wei, Xinlian Xie, Tiantian Bao

Journal of Marine Science and Technology–Taiwan

This paper proposes a new sailing speed optimization problem considering sea conditions such as wind and waves for a container shipping company. Since wind and waves, as exterior factors, can reduce speed, more power is employed as compensation to maintain regular service frequency and avoid delay, resulting in additional bunker consumption and higher cost. Hence, it is necessary to optimize the sailing speed according to the wind and waves. A power model was built to determine the reduced speed caused by the wind and waves for quantifying the speed reduction. On the basis of the proposed model, we developed a …

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A Bilevel Mathematical Approach For The Empty Container Repositioning Proble With A Sharing And Exchanging Strategy In Liner Shipping, Dung-Ying Lin, Chieh-Ju Juan Jul 2021

A Bilevel Mathematical Approach For The Empty Container Repositioning Proble With A Sharing And Exchanging Strategy In Liner Shipping, Dung-Ying Lin, Chieh-Ju Juan

Journal of Marine Science and Technology–Taiwan

In the maritime industry, the management of empty containers is a significant issue whose costs account for a large proportion of the total world fleet running costs. To reduce repositioning activities and increase cost effectiveness, this paper proposes a solution framework considering empty container sharing and exchanging strategies to coordinate the shipping lines in a maritime transportation network. The proposed solution framework considers an empty container matching platform company and a group of shipping lines in a given shipping network. Because of the interactive relationship between the two parties, the proposed problem is formulated as a bilevel programming problem, and …

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Investigating Model Solution Correctness For Parameter Uncertainty In Both Objective Function And Constraints, Shangyao Yan, Sin-Siang Wang, Chun-Yi Wang Jul 2021

Investigating Model Solution Correctness For Parameter Uncertainty In Both Objective Function And Constraints, Shangyao Yan, Sin-Siang Wang, Chun-Yi Wang

Journal of Marine Science and Technology–Taiwan

To resolve engineering management problems encountered in the real world, optimization models are usually formulated with some parameter assumptions. Parameter uncertainty, which may arise due to changes in the environment or human error, may thus be incorporated into the objective function and the constraints. However, to simplify the modeling, the values of these parameters are usually set or projected as deterministic values. It is no wonder that the modelling results based on these inaccurate parameters are neither correct nor reliable. Thus, it is important to examine the correctness of the model results in relation to parameter uncertainty. This study aims …

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Modular Design And Implementation Of An Automatic Power Factor Regulator For Energy Savings On Fishing Vessels, Chien-Hsing Lee, Shih-Hsien Hsu, Joe-Air Jiang Jul 2021

Modular Design And Implementation Of An Automatic Power Factor Regulator For Energy Savings On Fishing Vessels, Chien-Hsing Lee, Shih-Hsien Hsu, Joe-Air Jiang

Journal of Marine Science and Technology–Taiwan

This study describes the experiences of modular design and implementation of an automatic power factor regulator for improving energy efficiency on Taiwanese longline fishing vessels. The load capacities of such vessels are typically divided into three categories, depending on the gross tonnage or fish carrying capacity: less than 100 kW, from 100 kW to less than 250 kW, and larger than 250 kW. For attaining proper power factor improvement, a compensation unit with a total of 30 kVar, 60 kVar and 90 kVar was sized and assembled with capacitors of 10, 15 and 20 kVar to enable control within 12 …

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Key Risk Factors Influencing Harbor Tugboat Operations For Kaohsiung Port, Wen-Jui Tseng, Ji-Feng Ding, Chia-Ming Liu, Liou-Yuan Li Jul 2021

Key Risk Factors Influencing Harbor Tugboat Operations For Kaohsiung Port, Wen-Jui Tseng, Ji-Feng Ding, Chia-Ming Liu, Liou-Yuan Li

Journal of Marine Science and Technology–Taiwan

The harbor tugboat operation is a very important business and process of Kaohsiung port. To ensure the safety of harbor tugboat operations and to reduce the occurrence of accidents, it is an important issue to conduct a risk assessment of tugboat operations for Kaohsiung port. Hence, the main purpose of this paper is employ the analytic hierarchy process (AHP) method to evaluate key risk factors influencing the harbor tugboat operations for Kaohsiung port. At first, a total of three evalu-ation dimensions with 14 preliminary risk factors are gener-ated from literature and interviews of tugboat captains. We then applied the steps …

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Free Vibration Analysis Of A Free-Free Single-Tapered Beam Carrying Arbitrary Concentrated Elements Using Modified Mode-Superposition Method (Mmsm), Chia-Chin Wu Jul 2021

Free Vibration Analysis Of A Free-Free Single-Tapered Beam Carrying Arbitrary Concentrated Elements Using Modified Mode-Superposition Method (Mmsm), Chia-Chin Wu

Journal of Marine Science and Technology–Taiwan

The literature contains scant information on the free vibration analyses of the loaded single-tapered beams (STBs) (i.e., STBs carrying concentrated elements (CEs)) Furthermore, even when such studies have been performed, they generally only consider the case of constrained (e.g., free-clamped (F-C)) beams. In other words, the problem of unconstrained (e.g., free-free (F-F)) loaded STBs has not yet to be addressed. Thus, the present study employs the modified mode-superposition method (MMSM) to investigate the free vibration characteristics of the F-F loaded STB carrying arbitrary various CEs. The investigation focuses particularly on the natural frequencies and mode shapes of the rigid-body motions …

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Optimum Design Of The Underwater Discharge System Based On Surrogate Modeling, Jisang Ha, Myung-Il Roh, Seung-Ho Ham, Sung-Jun Lee Jul 2021

Optimum Design Of The Underwater Discharge System Based On Surrogate Modeling, Jisang Ha, Myung-Il Roh, Seung-Ho Ham, Sung-Jun Lee

Journal of Marine Science and Technology–Taiwan

Underwater vehicles are equipped with a device for discharging projectiles, called the underwater discharge system. Because these vehicles have limited space, many studies have attempted to reduce the volume of the underwater discharge system while improving its performance. However, owing to the characteristics of the system, the occupied volume and performance conflict with each other. Therefore, minimizing the occupied volume while satisfying the required performance criteria is the most significant requirement in the design stage. To address this, an optimization problem for the underwater discharge system was mathematically formulated and solved using multi-objective genetic algorithms. Additionally, we proposed a method …

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An Analysis Of Key Influencing Factors On Island Tourism Revisit Intentions – Evidence From The Matsu Islands, Chun-Chieh Wang, Hsiao-Chuan Liu, Hsuan-Shih Lee, Cheng-Chi Chung Jul 2021

An Analysis Of Key Influencing Factors On Island Tourism Revisit Intentions – Evidence From The Matsu Islands, Chun-Chieh Wang, Hsiao-Chuan Liu, Hsuan-Shih Lee, Cheng-Chi Chung

Journal of Marine Science and Technology–Taiwan

Sightseeing and tourism not only brings economic benefits to the local community but also drive the development of related industries. In 1992, when the Matsu’s battlefield mission was dissolved, tourism became one of the key development strategies to boom the region. Although the number of visitors to Matsu Islands has risen significantly in recent years, how to increase the island’s willingness to revisit the island has been an important issue. Since local tourism has its own characteristics, island tourism marketing strategies should be different. Many previous studies have quantified the relationship between tourism area satisfaction and willingness to revisit, but …

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3d Numerical Simulation Of Kuroshio-Induced Wake Near Green Island, Taiwan, Tien-Hung Hou, Jen-Yi Chang, Chia-Cheng Tsai, Tai-Wen Hsu Jul 2021

3d Numerical Simulation Of Kuroshio-Induced Wake Near Green Island, Taiwan, Tien-Hung Hou, Jen-Yi Chang, Chia-Cheng Tsai, Tai-Wen Hsu

Journal of Marine Science and Technology–Taiwan

In this research, Kuroshio-induced vortex shedding in the lee of Green Island was numerically studied using the three-dimensional Princeton Ocean Model. The temporal and spatial characteristics of the vortex street were analyzed at different tidal levels, wind fields and water depths. The nu-merical results were validated by comparing with in-situ measurements from the Green Island tidal station, shipboard acoustic doppler current profiler (ADCP), conductivi-ty-temperature-depth (CTD) profiler, and moderate resolution imaging spectroradiometer (MODIS) satellite image datasets. Also, the three-dimensional results of velocity, temperature, and salinity fields were compared well with observational data. Furthermore, the influence depths of the wind effect and …

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Intelligent Fuzzy Control With State-Derivative Feedback For Takagi-Sugeno Fuzzy Stochastic Singular Systems, Wen-Jer Chang, Kuang-Yow Lian, Cheung-Chieh Ku, Che-Lun Su Jul 2021

Intelligent Fuzzy Control With State-Derivative Feedback For Takagi-Sugeno Fuzzy Stochastic Singular Systems, Wen-Jer Chang, Kuang-Yow Lian, Cheung-Chieh Ku, Che-Lun Su

Journal of Marine Science and Technology–Taiwan

This document deals with the problem of passive fuzzy controller design with the state-derivative feedback approach for the nonlinear stochastic singular systems. Recently, the singular systems have a greater focus on literature because they can keep more physical system characteristics than conventional systems. At first, the Takagi-Sugeno fuzzy stochastic singular models are used to represent the nonlinear stochastic singular systems. Then, the state-derivative feedback approach and parallel distributed compensation method are employed to design the passive fuzzy controllers. In the design process, the Lyapunov stability conditions are developed subject to multiple performance constraints, including the passivity constraint and decay rate …

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Sea Ice Warning Visualization And Path Planning For Ice Navigation Based On Radar Image Recognition, Tsung-Hsuan Hsieh, Shengzheng Wang, Huijia Gong, Wei Liu, Ning Xu Jul 2021

Sea Ice Warning Visualization And Path Planning For Ice Navigation Based On Radar Image Recognition, Tsung-Hsuan Hsieh, Shengzheng Wang, Huijia Gong, Wei Liu, Ning Xu

Journal of Marine Science and Technology–Taiwan

Ice navigation is currently one of the important issues in path planning studies. Most studies are using sea ice models or ice charts for large-scale path planning, but the weather and ice conditions in the polar waters usually change quickly and are not easy to predict. Under these conditions, small-scale path planning that can be adjusted in time for sea ice collision avoidance is needed. This study uses marine radar imaging to reconstruct the ice navigation scene, and establishes a visual-ization function of sea ice warning on the radar image. We combine the bidirectional rapidly-exploring random tree (B-RRT) algorithm and …

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Enhancing Marine Administrative Management Based On Human Factor Through Safety Criteria, Wen-Cheng Lin, Hsin-Hung Cheng Jul 2021

Enhancing Marine Administrative Management Based On Human Factor Through Safety Criteria, Wen-Cheng Lin, Hsin-Hung Cheng

Journal of Marine Science and Technology–Taiwan

This study aims to improve maritime safety by enhancing administrative management based on human factors. This study used Fuzzy analytic hierarchy process to analyze the risks and threats regarding safety maritime criteria. Establishing administrative reform is given the highest priority. First, the current model for crew training system is explored. Second, the marine surveyor is examined to determine if it is professional enough for inspection work. Third, the investigation system used by maritime safety investigators should be inspected. The suggestions mentioned expect to establish a maritime administrative reform that could pave the way for the application of maritime safety around …

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Experimental Study On Treatment Of Ballast Water By Inert Flue Gas Deoxidation, Guozhi Bao, Peng Yang, Rui Da, Junxia Li, Guanghui Zhao, Ning Chen Jul 2021

Experimental Study On Treatment Of Ballast Water By Inert Flue Gas Deoxidation, Guozhi Bao, Peng Yang, Rui Da, Junxia Li, Guanghui Zhao, Ning Chen

Journal of Marine Science and Technology–Taiwan

In this paper, the antimicrobial effect of inert flue gas on indicator microorganisms in ballast water was investigated based on a 265h test. The inert flue gas consists of nitrogen (N2) and carbon dioxide (CO2) the microorganisms include Chlorella and Escherichia coli. Within the scope of the test, the killing effect of the microbes treated by combining N2 and CO2 was higher than that of using only either N2 or CO2. When the dissolved oxygen concentration in the ballast water was 0.5 mg/L and the pH value was 6, the killing effect was the highest. At this time, the mortality …

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Performance Evaluation Of Gas Lift Valves Using Numerical Simulation, Felipe Simoes Maciel Jul 2021

Performance Evaluation Of Gas Lift Valves Using Numerical Simulation, Felipe Simoes Maciel

LSU Master's Theses

This work aimed to assess the performance of two numerical simulation methods to replicate flow capacity test (FCT) results and predict the flow coefficient (Cv) and critical pressure ratio (Rcp) of gas lift valves (GLVs). FCT's use a modified GLV with an adjustable stem positioning system to obtain pressure as a function of flow rate for different stem positions to calculate Cv and Rcp. Therefore, this study used both a one-dimensional (1D) mechanistic model and computational fluid dynamics (CFD) to predict the same variable from the FCT without tests using modified GLVs. This methodology demonstrates accurate results, which were compared …

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Mathematical Model Of Power Flow In A Single-Phase Network Using Facts Devices Containing Static Power Flow Compensator Svc, Sh V. Khamidov, Bahrom Normuratov Jul 2021

Mathematical Model Of Power Flow In A Single-Phase Network Using Facts Devices Containing Static Power Flow Compensator Svc, Sh V. Khamidov, Bahrom Normuratov

Scientific-technical journal

The use of FACTS technology makes it possible to reduce the gap between controlled and uncontrolled modes of EPS operation, providing dispatching personnel with additional degrees of freedom in controlling power flows and voltages in excess and deficient areas of the electrical network. The unified approach used as an alternative combines the state variables of the EPS without controlled power equipment and the state variables describing the given controlled power equipment - the FACTS device - into a single set of states. In this case, the electrical network is described in a single coordinate system for the combined iterative solutions …

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Optimization Of Load-Bearing And Impact Energy Absorption Capacities Of Honeycomb Structures By Density Gradation, Oyindamola Khadijat Rahman Jul 2021

Optimization Of Load-Bearing And Impact Energy Absorption Capacities Of Honeycomb Structures By Density Gradation, Oyindamola Khadijat Rahman

Theses and Dissertations

Density gradation has been analytically and experimentally proven to enhance the load-bearing and energy absorption efficiency of cellular solids. This research focuses on the analytical optimization (by virtual experiments) of polymeric honeycomb structures made from flexible thermoplastics to achieve density-graded structures with desired mechanical properties. The global stress-strain curves of single-density honeycomb structures are used as input to an analytical model that enables the characterization of the constitutive response of density-graded hexagonal honeycombs with discrete and continuous gradations and for various gradients. The stress-strain outputs are used to calculate the specific energy absorption, efficiency, and ideality metrics for all density-graded …

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High-Throughput Computation Of New Carbon Allotropes With Diverse Hybridization And Ultrahigh Hardness, Mohammed Al-Fahdi, Alejandro Rodriguez, Tao Ouyang, Ming Hu Jul 2021

High-Throughput Computation Of New Carbon Allotropes With Diverse Hybridization And Ultrahigh Hardness, Mohammed Al-Fahdi, Alejandro Rodriguez, Tao Ouyang, Ming Hu

Faculty Publications

The discovery of new carbon allotropes with different building blocks and crystal symmetries has long been of great interest to broad materials science fields. Herein, we report several hundred new carbon allotropes predicted by the state-of-the-art RG2 code and first-principles calculations. The types of new carbon allotropes that were identified in this work span pure sp2 , hybrid sp2/sp3 , and pure sp3 C–C bonding. All structures were globally optimized at the first-principles level. The thermodynamic stability of some selected carbon allotropes was further validated by computing their phonon dispersions. The predicted carbon allotropes …

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