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Articles 3151 - 3180 of 16772

Full-Text Articles in Materials Science and Engineering

Study On Health State Evaluation Method Of Highway Tunnel Based On Neutrosophic Theory, Deng Fayou, Xia Caichu, Xu Chongbang May 2023

Study On Health State Evaluation Method Of Highway Tunnel Based On Neutrosophic Theory, Deng Fayou, Xia Caichu, Xu Chongbang

Journal of China & Foreign Highway

The structural complexity and inherent uncertainties of highway tunnels necessitate comprehensive consideration of various uncertain factors to reasonably evaluate their health state. By introducing neutrosophic theory, which accounts for structural uncertainties, this paper proposes a health state evaluation method for highway tunnels based on neutrosophic cosine and tangent similarity measures. The proposed method was applied to evaluate the health state of 10 samples. A comparison between the actual evaluation grades and the results obtained using the proposed method shows that the evaluation results are consistent with the actual grades. This indicates that the proposed method effectively addresses uncertainties in the …

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Interlayer Bonding Performance Of Wtr/Apao Composite Modified Asphalt, Ji Hongyan, Yan Kezhen, Yuan Jian, Zhang Xuanyu May 2023

Interlayer Bonding Performance Of Wtr/Apao Composite Modified Asphalt, Ji Hongyan, Yan Kezhen, Yuan Jian, Zhang Xuanyu

Journal of China & Foreign Highway

To investigate the bonding performance of waste tire rubber (WTR)/ amorphous α-olefin copolymer (APAO) composite modified asphalt as a waterproof bonding layer in asphalt pavements on cement concrete bridges, shear and pull-off tests were conducted. The shear strength and pull-off strength of SBS-modified asphalt, WTR-modified asphalt, and WTR/APAO composite modified asphalt were compared under different application rates and temperatures. The results show that WTR/APAO composite modified asphalt exhibits the best bonding performance, followed by WTR-modified asphalt, with SBS-modified asphalt performing the worst. Based on the shear and pull-off strengths at different temperatures, the optimal application rates were determined as 1.7 …

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Study On Modification Of Phosphate Pretreated Aggregate Vegetation Porous Concrete, Li Zhengxing, Hou Zebiao May 2023

Study On Modification Of Phosphate Pretreated Aggregate Vegetation Porous Concrete, Li Zhengxing, Hou Zebiao

Journal of China & Foreign Highway

To enhance the interfacial structure between aggregates and cementitious materials in vegetation porous concrete and improve its compressive strength, this paper investigates the effects of phosphate pretreatment on aggregate properties and the corresponding compressive strength of vegetation porous concrete. The performance of untreated aggregates, water-washed aggregates, and acid-treated aggregates was evaluated, and the modification mechanism was explored from the perspective of the interfacial transition zone (ITZ) using scanning electron microscopy (SEM). The results show that phosphate effectively removes impurities from the aggregate surface and increases surface roughness, thus improving the compactness and stability of the ITZ. After soaking the aggregates …

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Optimization Study On Indoor Vibratory Compaction Curves Of Cement Stabilized Macadam, Qiu Youqiang, Zhang Liujun May 2023

Optimization Study On Indoor Vibratory Compaction Curves Of Cement Stabilized Macadam, Qiu Youqiang, Zhang Liujun

Journal of China & Foreign Highway

To obtain well-defined secondary convex vibratory compaction curves and reduce the need for supplemental compaction point tests, this paper uses vibratory compaction tests for cement stabilized macadam in laboratory settings. Tests were conducted for two pavement sections along National Highway 110 (Hohhot to Bikeqi), exploring the influence of predefined moisture content intervals on vibratory compaction curves under varying cement dosages. The vibratory compaction curves were also compared with heavy compaction curves for analysis. The results show that the vibratory compaction curve is significantly influenced by the predefined moisture content intervals and cement dosage. For a moisture content interval of 1%, …

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Selection Of Phase Change Materials For Asphalt Pavement Based On Molecular Dynamics Simulation, Liu Fujun, Tian Xin, Liang Meichen, Guo Meng May 2023

Selection Of Phase Change Materials For Asphalt Pavement Based On Molecular Dynamics Simulation, Liu Fujun, Tian Xin, Liang Meichen, Guo Meng

Journal of China & Foreign Highway

Phase change materials (PCMs) have significant application potential in temperature regulation for asphalt pavements. To select suitable PCMs for road applications, this paper utilizes molecular dynamics simulation to analyze the molecular behaviors of lauric acid and polyethylene glycol (PEG). Experimental studies were conducted to validate the simulation results. The results show that molecular dynamics simulation provides an efficient and convenient method for comparing the performance of PCMs. PEG outperforms lauric acid in terms of molecular density, cohesive energy density, solubility parameters, and thermal conductivity, making it more suitable as a phase change material for asphalt pavements.

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Experimental Study On Water Stability Of Sand Compound Modified Mud Road, Chai Ruixiang, Wu Kai, Ye Wei, Cui Jinmei, Wang Jicheng, Li Zhantao May 2023

Experimental Study On Water Stability Of Sand Compound Modified Mud Road, Chai Ruixiang, Wu Kai, Ye Wei, Cui Jinmei, Wang Jicheng, Li Zhantao

Journal of China & Foreign Highway

Sand compound modified mud, as a coupled medium of sand and soil, differs from traditional modified mud. To further investigate its water stability indicators, orthogonal design was employed to conduct indoor water stability simulation tests (surface infiltration test, underground capillary water test, and dry-wet cycle test) on sand compound modified mud. The water stability of the modified mud was characterized using the change rate of unconfined compressive strength (UCS). The results show that the unconfined compressive strength and water stability of the modified mud were significantly improved. Under different water disturbance conditions, the order of influence of factors such as …

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Experimental Study On Influence Of Phosphorus Slag Powder On Pervious Concrete, Lou Jianxin, Yang Jianyong, Zhang Yuxian, Li Jun, Wang Jie, Liu Jian May 2023

Experimental Study On Influence Of Phosphorus Slag Powder On Pervious Concrete, Lou Jianxin, Yang Jianyong, Zhang Yuxian, Li Jun, Wang Jie, Liu Jian

Journal of China & Foreign Highway

This paper investigates the effects of replacing cement with phosphorus slag powder on the mechanical properties, permeability, and pavement performance of pervious concrete. The results show that incorporating a certain amount of phosphorus slag powder as a partial replacement for cement in pervious concrete is feasible. When the replacement ratio of phosphorus slag powder is within 10%, it enhances the strength of pervious concrete. The optimal replacement ratio of phosphorus slag powder is 8%, achieving a compressive strength of 24.18 MPa, a void ratio of 15.37%, and a permeability coefficient of 2.45 mm/s, which meet the requirements for fully permeable …

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Study On Alkali Excitation Mechanism Of Large Dosage Slag Fine Powder, Mei Yang May 2023

Study On Alkali Excitation Mechanism Of Large Dosage Slag Fine Powder, Mei Yang

Journal of China & Foreign Highway

To reveal the alkali excitation mechanism of high-dosage slag, this paper combines a three-factor, three-level orthogonal design with macro- and micro-performance tests and microstructure analysis. The effects of different activators, including Ca(OH)2, Na2SiO3, Na2SO4, and CaSO4, in single and dual combinations on the initial and final setting times, pore solution pH, and strength of concrete were explored. The results show that the impact on the strength of hardened paste of composite cementitious materials is ranked as: activator type > dosage > dual-mix ratio. The optimal dual-mix dosage is 4%, with the best combination being Ca(OH)2 and Na2SiO3 at a ratio of 5:1. …

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Dynamic Load Response Analysis Of Rubber Powder Modified Asphalt Mixture, Yang Sanqiang, Sun Shuang, Li Qian, Liu Xinlei, Qin Lusheng May 2023

Dynamic Load Response Analysis Of Rubber Powder Modified Asphalt Mixture, Yang Sanqiang, Sun Shuang, Li Qian, Liu Xinlei, Qin Lusheng

Journal of China & Foreign Highway

To investigate the mechanical response of rubber powder modified asphalt pavement under dynamic loads, this paper, based on the “Full-Scale Accelerated Pavement Loading Testing” project, designed experimental schemes for asphalt mixtures with varying rubber powder contents. The paper employed accelerated loading test equipment to evaluate the stress and deformation of pavement structures, obtaining dynamic strain response data to analyze the strain response patterns of various structural layers. Combining finite element numerical simulations and a custom loading program, the paper examined the dynamic responses of rubber powder modified asphalt pavements under variable temperature conditions. The results show that through microscopic testing, …

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Aging Asphalt Concrete Cracking Performance Under Different Cyclic Loading Frequencies, Yan Jingchen, Ma Yanpei, Yan Junjie May 2023

Aging Asphalt Concrete Cracking Performance Under Different Cyclic Loading Frequencies, Yan Jingchen, Ma Yanpei, Yan Junjie

Journal of China & Foreign Highway

Using digital speckle technology, this paper examines the crack propagation behavior of asphalt concrete under repeated loading, analyzing the crack propagation mechanism from macro- and micro-perspectives under different aging conditions and loading frequencies for four types of asphalt concrete. The results show that the basalt fiber-reinforced asphalt concrete beam specimens delay the onset of the unstable crack propagation phase, thus extending the service life of the asphalt concrete. Aging accelerates the progression of asphalt concrete to the unstable crack propagation point, advancing this stage by 4%-5%. Under repeated loading frequencies of 5 Hz, 10 Hz, and 15 Hz, the damage …

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Study On Microstructure Of Asphalt Modified By Oil‐Coal Blend, Guo Pengfei, Zhou Xinfeng May 2023

Study On Microstructure Of Asphalt Modified By Oil‐Coal Blend, Guo Pengfei, Zhou Xinfeng

Journal of China & Foreign Highway

To investigate the microstructure and modification mechanism of asphalt modified with oil-coal blend, SK-90# asphalt was mixed with 5%, 10%, 15%, 20%, and 25% (external blending method) oil-coal blend to produce modified asphalt. The performance and microstructural changes of the modified asphalt were analyzed using contact angle testing, infrared spectroscopy, cross-sectional SEM, and X-ray photoelectron spectroscopy. The results show that the oil-coal blend exhibits good compatibility with asphalt. During the modification process, esterification reactions occurred, resulting in a decrease in hydroxyl-containing aromatic compounds and an increase in carbonyl-containing aromatic compounds. Macroscopically, the oil-coal blend-modified asphalt demonstrated excellent high-temperature performance.

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Design And Development Of Two And Three Dimensional Integration System For Highway Based On Webgis, Che Defu, Zhou Huajun May 2023

Design And Development Of Two And Three Dimensional Integration System For Highway Based On Webgis, Che Defu, Zhou Huajun

Journal of China & Foreign Highway

To address the inefficiencies, lengthy cycles, and high resource demands in the process of determining the annual project database for highway maintenance quotas in Liaoning Province, a 2D and 3D integration system for highways based on WebGIS was designed and developed. This system not only provides a macroscopic view of the geographic distribution and overall characteristics of highways but also offers a detailed and intuitive representation of the spatial relationships and conditions of roadbeds and pavement damage. The system meets the needs of modern highway management and can serve as a reference for other highway maintenance quota tasks.

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Research On Influence Factors And Efficiency Analysis Of Expressway Maintenance Marketization, Zhong Wen, He Shoukui, Wang Xiaodong May 2023

Research On Influence Factors And Efficiency Analysis Of Expressway Maintenance Marketization, Zhong Wen, He Shoukui, Wang Xiaodong

Journal of China & Foreign Highway

To promote market-oriented reform of highway maintenance, this paper investigates its influencing factors and outcomes and proposes an evaluation model for assessing its effects. A panoramic analysis method within a three-dimensional framework was employed to determine the evaluation content. Drawing on the balanced scorecard concept, the analysis incorporates four dimensions: business, user, internal management, and learning and growth, with the innovative addition of a social responsibility dimension to construct an evaluation indicator system. Subsequently, a cloud-based extension model was developed to evaluate the effectiveness of expressway maintenance marketization and calculate the evaluation grade. Empirical analysis was conducted using data from …

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Analysis Of Expressway Routine Maintenance Performance Management Based On Dea, Li Yuhuan, Shi Xiaoli, Gao Nan May 2023

Analysis Of Expressway Routine Maintenance Performance Management Based On Dea, Li Yuhuan, Shi Xiaoli, Gao Nan

Journal of China & Foreign Highway

To allocate maintenance resources efficiently and improve management levels, this paper examines the maintenance performance and improvement strategies of routine maintenance projects for 23 expressways in Shaanxi Province using 2018 operational maintenance data and data envelopment analysis. The results show that for some inefficient subsidiaries, traditional radial- and slack-based performance improvement methods are challenging and impractical in the short term. Therefore, a scenario-dependent model-based long-term incremental improvement strategy is proposed. By leveraging relative improvement values, this strategy enables phased improvements for inefficient subsidiaries. It provides a feasible approach for subsidiaries to set lower short-term performance improvement targets while achieving gradual …

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Study On The Minimum Radius Of Vertical Curve Of Highway Main Line Entrance Section Based On Merging Sight Distance, Li Yang, Zhao Yemei, Chen Tianxing May 2023

Study On The Minimum Radius Of Vertical Curve Of Highway Main Line Entrance Section Based On Merging Sight Distance, Li Yang, Zhao Yemei, Chen Tianxing

Journal of China & Foreign Highway

Given the limited research on the vertical curve radius of highway mainline entrance sections and the lack of differentiation between entrance and exit sections in existing studies, this paper identifies merging sight distance as the primary influencing factor for the vertical curve radius of entrance sections. Using merging sight distance as the control condition, the vertical curve radius of entrance sections was studied. A safety merging sight distance calculation model for highway mainline entrance sections was established by analyzing the traffic behavior characteristics of vehicles on the entrance mainline and considering drivers’ psychological and physiological characteristics. The sight distance model …

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Soil Respiration Measurements Reveal High Retention Of Organic Carbon From Corn Residue Derived High-Lignin Fermentation Byproduct Enabling Sustainable Lignocellulosic Biofuel Production, Michelle Sun Wang May 2023

Soil Respiration Measurements Reveal High Retention Of Organic Carbon From Corn Residue Derived High-Lignin Fermentation Byproduct Enabling Sustainable Lignocellulosic Biofuel Production, Michelle Sun Wang

Dartmouth College Master’s Theses

While 2G biofuel production can utilize non-edible, lignocellulosic feedstocks such as agricultural residues to produce liquid fuel, harvesting crop residues is unsustainable without careful management of the soil underneath. By harvesting a fraction of the crop residues left in the field after harvest, soil health can diminish and critically, the soil organic carbon (SOC) stored in agricultural fields can decrease. Currently, in the most popular 2G process models published, the issue of soil degradation remains unresolved with residue harvest strategies receiving considerable attention in the literature and other SOC management strategies receiving far less. Specifically, the strategy of returning the …

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Review: Inelastic Constitutive Modeling: Polycrystalline Materials, Mirza Baig, Josiah Owusu-Danquah, Anne A. Campbell, Stephen F. Duffy Phd, Pe May 2023

Review: Inelastic Constitutive Modeling: Polycrystalline Materials, Mirza Baig, Josiah Owusu-Danquah, Anne A. Campbell, Stephen F. Duffy Phd, Pe

Civil and Environmental Engineering Faculty Publications

This article provides a literature review that details the development of inelastic constitutive modeling as it relates to polycrystalline materials. This review distinguishes between inelastic constitutive models that account for nonlinear behavior at the microstructural level, time-independent classic plasticity models, and time-dependent unified models. Particular emphasis is placed on understanding the underlying theoretical framework for unified viscoplasticity models where creep and classical plasticity behavior are considered the result of applied boundary conditions instead of separable rates representing distinct physical mechanisms. This article establishes a clear understanding of the advantages of the unified approach to improve material modeling. This review also …

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Machinability Of High Mn Steel Using Tool Life Criteria, Dika Handayani, Victor F. Okhuysen, Nicole Wagner May 2023

Machinability Of High Mn Steel Using Tool Life Criteria, Dika Handayani, Victor F. Okhuysen, Nicole Wagner

Engineering Faculty Articles and Research

High Mn steel alloys have shown to provide both high strength and ductility. However, current literature offers limited guidance on the machinability of these steel alloys. Therefore, this work provides turning recommendations for high Mn steel that is based on tool life data. Several indexable carbide inserts with various rake angles were used to machine cast billets of high Mn steel. Turning characteristics from various feed rates, cutting speeds, and depths of cut were analyzed. Through a design of experiments, it was determined that the feed rate was the most significant factor affecting tool life and that a tool with …

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Exploring Methods For Recycling Filament Waste In 3d Printing, Max Rios Carballo May 2023

Exploring Methods For Recycling Filament Waste In 3d Printing, Max Rios Carballo

Publications and Research

The goal of the current study is to investigate cutting-edge techniques for recycling filament waste from 3D printing procedures. Appropriate waste management techniques are required to reduce this trash's harmful environmental consequences. The goal of the project is to look at new methods for recycling filament waste in order to minimize disposal and encourage reuse. To acquire data from pertinent papers and research, a thorough literature review methodology was used. The findings show that this issue may be resolved utilizing a variety of recycling techniques, including shredding, melting, and re-extrusion. The type of filament waste and the intended goal will …

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A Study Of Biochar Production Via Continuous Vacuum-Assisted Pyrolysis, Max Wohlgenant May 2023

A Study Of Biochar Production Via Continuous Vacuum-Assisted Pyrolysis, Max Wohlgenant

Graduate Theses & Non-Theses

The present study focuses upon the design, fabrication, and feasibility of the bulk production of scientific biochar for mobile delivery. In the 2022 annual report, the National Academies of Science, Engineering, and Medicine recommended the integration of mobile, decentralized reactors that employ flexible manufacturing and circular economic principles. Biochar production, involving the thermal degradation of biomass under an inert atmosphere to yield remediation media is an ideal material to satisfy this recommendation. Many potential application sites, such as abandoned mines, are remote and limit the construction of large infrastructure. The continuous vacuum-assisted pyrolysis (CVAP) reactor was designed to: increase biochar …

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Multi-Mode Total Focusing Method (Mtfm) To Detect High-Temperature Hydrogen Attack (Htha) – A Review, Anjar Oktikawati, Rini Riastuti, Nursidi Yuanto May 2023

Multi-Mode Total Focusing Method (Mtfm) To Detect High-Temperature Hydrogen Attack (Htha) – A Review, Anjar Oktikawati, Rini Riastuti, Nursidi Yuanto

Journal of Materials Exploration and Findings

High temperature hydrogen attack (HTHA) is a commonly observed harm component in carbon steels exposed to high temperature and pressure in a hydrogen-rich environment. Hydrogen together with carbon responds to produce methane. The formation of methane bubbles in steel can lead to loss of fracture toughness and lead to intergranular cracking. The main challenge of this problem lies in early warning systems that can detect these bubble clusters before they reach the advanced stage. Several advanced ultrasonic inspections have been developed over the years due to the challenges of inspecting materials for defects and discontinuities. These cover time-of-flight diffraction (ToFD), …

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Estimating Remaining Life And Fitness-For-Services Evaluation Of Fuel Piping Systems, Sekar Putri Purwidyasari, Ahmad Isni Kurniawan, Deni Ferdian May 2023

Estimating Remaining Life And Fitness-For-Services Evaluation Of Fuel Piping Systems, Sekar Putri Purwidyasari, Ahmad Isni Kurniawan, Deni Ferdian

Journal of Materials Exploration and Findings

Assets life extension are required to predict the design life expiry based on condition and effects of deterioration. The remaining life assessment will answer the questions about timing of the component or equipment will lead to failure and shall be evaluated by inspection and maintenance monitoring. This study elaborates process calculation and analysis by using remaining life assessment and fitness for services method according to API 579-1/ASME FFS-1 for process piping area. The result of remaining useful life estimation and estimated life has been proposed. There are 11 piping systems based on the condition monitoring with thickness measurements. The result …

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Development Of Dynamic Risk-Based Inspection Using Forward Difference Approach For Pipe Failure Due To Uniform Corrosion, Jaka Fajar Fatriansyah, Zahra Nadia Nurullia, Andreas Federico, Dedi Priadi May 2023

Development Of Dynamic Risk-Based Inspection Using Forward Difference Approach For Pipe Failure Due To Uniform Corrosion, Jaka Fajar Fatriansyah, Zahra Nadia Nurullia, Andreas Federico, Dedi Priadi

Journal of Materials Exploration and Findings

The oil and gas industry is one of the world's largest and most influential energy contributors. All aspects involved in the operation of this industry are fundamental to be reviewed and managed correctly, especially by preventing or minimizing the failures that could occur. Uniform corrosion is the most common component failure mechanism that can cause failure in the oil and gas industry. The company's actions in managing and preventing the risk of this type of failure have a major role in the sustainability of the company due to the possibility of more significant impacts if the risk cannot be handled …

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Utilization Of Machine Learning To Investigate Material State, Ana B. Abadie May 2023

Utilization Of Machine Learning To Investigate Material State, Ana B. Abadie

Honors College Theses

The ability to predict material behavior that undergoes various loading conditions is critical to the development of reliable and safe components. Thermal and mechanical fatigue loading can cause significant damage to materials, leading to failure and potential safety hazards. Machine learning algorithms have emerged as a promising tool for improving accuracy and efficiency of predicting material behavior under such loading conditions. This research provides a comprehensive overview of a machine learning algorithm that is able to analyze and predict material state independently of the loading sequence. Unidirectional carbon fiber reinforced polymer (UD CFRP) composite which has undergone two different loading …

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Utilization Of Cellulose Symbiotic Culture Of Bacteria And Yeast (Scoby) With Sweet Tea Media As Methylene Blue And Brilliant Green Biosorbent Material, Leonard Mateus Sigiro, Ahmad Maksum, Donanta Dhaneswara May 2023

Utilization Of Cellulose Symbiotic Culture Of Bacteria And Yeast (Scoby) With Sweet Tea Media As Methylene Blue And Brilliant Green Biosorbent Material, Leonard Mateus Sigiro, Ahmad Maksum, Donanta Dhaneswara

Journal of Materials Exploration and Findings

The cellulose from Symbiotic Culture of Bacteria and Yeast (SCOBY) can be used as a biosorbent for dye adsorption, such as Methylene Blue and Brilliant Green. This study used sweet tea with a 6% of sugar concentration and 14 days of fermentation time to synthesize biosorbent material from SCOBY. The results from this synthesis are then characterized using FTIR, SEM, and BET. From the result of characterization, it was found that SCOBY has pores formed from cellulose. The results of the average pore size are 1.5976nm with a pore volume of 0.229cc/g, while the specific surface area is 143.244m2/g. The …

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Enhancing Compatibility And Mechanical Properties Of Natural Rubber Composites, Krisma Yessi Sianturi, Adam Febriyanto Nugraha, Belle Kristaura, Mochamad Chalid May 2023

Enhancing Compatibility And Mechanical Properties Of Natural Rubber Composites, Krisma Yessi Sianturi, Adam Febriyanto Nugraha, Belle Kristaura, Mochamad Chalid

Journal of Materials Exploration and Findings

Pure natural rubber (NR) exhibits low mechanical properties, necessitating the incorporation of additives like vulcanizing agents and fillers. Carbon black and silica, conventional fillers, are relatively expensive and not environmentally friendly. This study explores using Oil Palm Empty Fruit Bunch (OPEFB) fiber as an affordable, abundant, and biodegradable alternative filler for NR. However, compatibility issues arise between the nonpolar NR and the polar OPEFB fiber. A latex-starch hybrid coupling agent (CA (NR-St)) was added to the composite formulation to address this. NR, OPEFB fiber, and the coupling agent were mixed using an open roll mill with a 10 phr OPEFB …

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Fabrication Of Black Phosphorus Terahertz Photoconductive Antennas, Nathan Tanner Sawyers May 2023

Fabrication Of Black Phosphorus Terahertz Photoconductive Antennas, Nathan Tanner Sawyers

Physics Undergraduate Honors Theses

Terahertz (THz) photoconductive antennas (PCAs) using 40nm thin-film flakes of black phosphorus (BP) and hexagonal boron nitride (hBN) have been shown computationally to be capable of THz emission comparable to those based on GaAs [2]. In this paper, I briefly describe the scientific and practical interest in THz emissions and explain what warrants research into black phosphorus as a photoconductive semiconductor in THz devices. Furthermore, I outline the basic principle of how these antennas work and mention alternative designs produced by other researchers in the past. Finally, I summarize the fabrication process of these antennas, as well as the measurements …

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Physics-Based Human-In-The-Loop Machine Learning Combined With Genetic Algorithm Search For Multi-Criteria Optimization: Electrochemical Co2 Reduction Reaction, Naohiro Fujinuma, Samuel Lofland May 2023

Physics-Based Human-In-The-Loop Machine Learning Combined With Genetic Algorithm Search For Multi-Criteria Optimization: Electrochemical Co2 Reduction Reaction, Naohiro Fujinuma, Samuel Lofland

College of Science & Mathematics Departmental Research

Machine learning (ML) can be a powerful tool to expedite materials research, but the deployment for experimental research is often hindered by data scarcity and model uncertainty. An human-in-the-loop procedure to tailor the implementation of ML for multicriteria optimization is described. The effectiveness of this procedure in the development of a nafion-based membrane electrode assembly for electrochemical CO2 reduction reaction (CO2RR) into CO for two targets is demonstrated: energy efficiency (EE) and partial current density for CO2RR (). Model-agnostic nonlinear correlation analyses identify the 11 features relevant to those targets. The three studied decision tree-based ML models yield similar cross-validation …

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Assessment Of Joule Heating Properties Of Various Solder Alloys In Bga Assembly, Jimmy-Bao D. Le May 2023

Assessment Of Joule Heating Properties Of Various Solder Alloys In Bga Assembly, Jimmy-Bao D. Le

Material Science and Engineering Theses - Archive

The continuing demands for smaller, yet higher performance devices have resulted in many revolutionary changes in device packaging in recent years, including the change in package form factors, structure, and the type of solder alloys used for the assembly. Because solder joints are exposed to various electrical and thermo-mechanical stresses, not only at use condition but also during their process into the assembly, they are prone to failure. Especially concerned in this respect is the current density that the solder joint is subjected to as it determines the level of Joule Heating (JH), thus the solder temperature, significantly affecting the …

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Study Of Alloy Effect On Electromigration In Sn Solder Alloys, Geng Ni May 2023

Study Of Alloy Effect On Electromigration In Sn Solder Alloys, Geng Ni

Material Science and Engineering Dissertations - Archive

This dissertation presents experimental results about the alloy effect on the Electromigration (EM) of Sn in Sn-based binary and ternary alloys. By using cross-stripe configuration, the alloy effect on EM of Sn can be characterized from marker polarity, and the migration of alloy element under EM can be measured from marker front motion. In the dissertation, the mechanism of alloy effect on EM of Sn, “Two-Phase equilibrium”, will be introduced. Electromigration is a phenomenon where metallic atoms are migrated at the direction of electron flow under high current density. In response to the demands for greater speed and smaller size, …

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