Engineering Science and Materials Commons^™

Special Issue “Cfd Modeling Of Complex Chemical Processes: Multiscale And Multiphysics Challenges”, Li Xi, De-Wei Yin, Jae Sung Park

Department of Mechanical and Materials Engineering: Faculty Publications

No abstract provided.

Application Of Atomically Precise Metal Nanoclusters In Electrocatalysis, Zhi-Hua Zhuang, Wei Chen

Journal of Electrochemistry

Metal nanoclusters (M NCs) consist of only several to a few hundred of metal atoms and possess core sizes less than 2 nm. Owing to the quantum size effect, the electronic states of M NCs evolve to discrete levels similar to the molecule energy gaps, other than a continuous density of states to produce plasmon characteristic of bulk metal nanoparticles (M NPs). In comparison with the conventional M NPs, M NCs exhibit dramatically unique electronic and optical properties, such as molecule-like energy gaps, strong photoluminescence and high catalytic properties, which make them promising for potential application in numerous fields, such …

Electrochemiluminescence Imaging Hydrogen Evolution Reaction On Single Platinum Nanoparticles Using A Bipolar Nanoelectrode Array, Xiang Qin, Zhong-Qiu Li, Jian-Bin Pan, Jian Li, Kang Wang, Xing-Hua Xia

Journal of Electrochemistry

A high-density (5.7 × 10⁸ cm^-2) nanoelectrode array with the electrode diameter of 200 nm and the interelectrode distance of 450 nm were fabricated. The nanoelectrode array consisted of gold nanowires embedded in a porous anodic aluminum oxide (AAO) matrix, having regular nanoelectrode distribution and highly uniform nanoelectrode size. The gold nanoelectrode array was used as a closed bipolar nanoelectrode array combined with electrochemiluminescence (ECL) method to map the electrocatalytic activity of platinum nanoparticles toward hydrogen evolution reaction (HER) by modifying the catalysts on single nanoelectrodes. Results show that HER on single bipolar nanoelectrodes could be imaged …

Oxygen-Exposure Induced Rapid Oxidation Of Spiro-Ometad In Cspbibr2 Perovskite Solar Cells, Wei-Guo Wang, Tian Bai, Gao-Fei Xue, Mei-Dan Ye

Journal of Electrochemistry

2,2′,7,7′-tetrakis(N,N-di-p-methoxyphenyl-amine)-9,9′-spirobifluorene (Spiro-OMeTAD) is the most widely used hole transport material in perovskite solar cells (PSCs). However, its oxidation in the air takes a long time and results in the attack of perovskite by water. In this regard, we performed the oxidation process of Spiro-OMeTAD in oxygen, where perovskite can be protected from water, guaranteeing the integrity of perovskite. It was demonstrated that the champion Spiro-OMeTAD based CsPbIBr₂ PSCs after oxygen oxidation achieved a 7.19% power conversion efficiency (PCE), showing a higher PCE than 6.29% of the champion device oxidized in air. A series of electrochemical characterization methods were applied …

Theoretical Studies Of Metal-N-C For Oxygen Reduction And Hydrogen Evolution Reactions In Acid And Alkaline Solutions, Xue-Ping Qin, Shang-Qian Zhu, Lu-Lu Zhang, Shu-Hui Sun, Min-Hua Shao

Journal of Electrochemistry

Single atom catalysts (SAC) have been regarded as the promising alternatives to platinum group metals due to their low costs and potentially high catalytic activities in various electrocatalytic reactions. The atomic mechanism understanding of activity discrepancy among different metal and nitrogen co-doped carbon-based catalysts is still lacking. Here, non-precious metal and nitrogen co-doped carbons (Me-N-C, Me = Fe and Co) as the model catalysts are investigated by combining experimental and theoretical studies to explore the catalytic activities and corresponding reaction mechanisms toward oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER) at universal pHs. Atomic theoretical simulations suggest that Fe-N-C …

Lithium Storage Performance Of Hard Carbons Anode Materials Prepared By Different Precursors, Zhen-Lang Liang, Yao Yang, Hao Li, Li-Ying Liu, Zhi-Cong Shi

Journal of Electrochemistry

Hard carbon is one of the most promising anode material for lithium ion batteries (LIBs) owing to its high stability, widespread availability, low-cost, and excellent performance. The electrochemical properties of hard carbon materials depend strongly on the type of precursors. It is, therefore, very important to choose an excellent hard carbon precursor. Polyacrylonitrile, petroleum pitch and peanut shells were used as raw materials to prepare different hard carbon anode materials for LIBs. These hard carbon anode materials were successfully synthesized in two steps. The selected precursor was firstly carbonized at 600℃ for 1 h in argon atmosphere using heating rate …

Pd-Based Electrocatalysts For Oxygen Reduction And Ethanol Oxidation Reactions: Some Recent Insights Into Structures And Mechanisms, Zhi-Peng Wu, Chuan-Jian Zhong

Journal of Electrochemistry

The development of efficient electrocatalysts for applications in fuel cells, including proton-exchange membrane fuel cell (PEMFC) and direct ethanol fuel cell (DEFC), has attracted extensive research attention in recent years. Oxygen reduction reaction and ethanol oxidation reaction are two of the key reactions where the design of active, stable and low-cost electrocatalysts is critical for the mass commercializations of PEMFCs and DEFCs. This challenge stems largely from the limited understanding of the catalyst structures and reaction mechanisms. Progress has been made in investigations of electrocatalysts derived from Pd-based alloy nanomaterials both experimentally and computationally. We highlight herein some of the …

Preparation And Characterization Of "Water-In-Salt" Polymer Electrolyte For Lithium-Ion Batteries, Xu Hou, Xin He, Jie Li

Journal of Electrochemistry

Since the development of wearable and flexible electronic products, the demand of flexible energy storage devices such as batteries and super capacitors is in urgent. To enhance the safety and cycling stability for flexible lithium-ion batteries, “water-in-salt” polymer electrolyte was prepared by introducing 21 mol·kg^-1 LiTFSI electrolyte into cross-linked polyacrylamide (PAM) after freeze-drying. A great amount of holes with the size range of 10 ~ 20 μm can be found on the surface and in the bulk of polyacrylamide, which is benefited from the freeze-drying process and acts as a great support for the electrolyte uptake. The “water-in-salt” polymer …

Electrochemical Surface-Enhanced Raman Spectroscopic Studies On Nickel Ultramicroelectrode, Li-Wen Wu, Wei Wang, Yi-Fan Huang

Journal of Electrochemistry

Nickel (Ni) electrodes are widely used in electrochemical researches. Understanding electrochemical processes on Ni electrodes through in-situ characterization of adsorbed species on their surfaces is helpful for rational optimization and application of Ni electrochemistry. Microelectrochemical surface-enhanced Raman spectroscopy (μEC-SERS) combines the mass transfer feature of ultramicroelectrode with high-sensitivity characterizations of molecular structures, which is a powerful method for studying Ni electrochemistry on polarization and non-equilibrium conditions. The key point of performing μEC-SERS is to make a SERS-active Ni ultramicroelectrode.
Here, we demonstrate a method of preparing a SERS-active Ni ultramicroelectrode through electrochemical deposition of several atomic layers of …

Sorption Of Ions Of Some Metals On Synthesized Weakly Basic Ion Exchangers, Dilmurod Azimov, S. Turabjanov, Farrukh Igitov, Rano Nazirova, Tulkin Tursunov

CHEMISTRY AND CHEMICAL ENGINEERING

The purpose of the study is to test a weakly basic anion exchanger of the polycondensation type in the processes of sorption of ions of copper, nickel, cobalt, zinc, cadmium. Among the indicated metal ions, the maximum sorption was established for copper ions.

To study the process of sorption of copper ions by the tested anion exchanger, the method of potentiometric titration was used. It was found that copper ions are sorbed by the anion exchanger in the form of a complex in the range of pH = 3,4-4,2. The formation of the copper ions complexes decreases with an increase …

Fabrication And Characterization Of Highly Ordered Aao Nanotubes, Anvar Khamidov, Farhod Hoshimov, Suvonkul Erkhanovich Nurmonov, Olim Ruzimuradov, Shavkat Mamatkulov

CHEMISTRY AND CHEMICAL ENGINEERING

Investigated the electrochemical synthesis and characterized of a nanometer scale porous anodic aluminum oxide (AAO) membranes with a mean pore diameter about of 80-100 nm. The anodizing process done by varying the anodizing temperature from 20 °C to 25 °C. The membranes exhibit interesting properties such as controllable pore diameters, periodicity and density distribution. These properties can preselected by adjusting the controlling parameters of a temperature controlled two-step anodization process. The surface features of the nanometer scale membrane such as pore density, pore diameter and interpore distance were quantified using scanning electron microscopy (SEM) and atomic force microscopy (AFM). SEM …

Improving Accuracy Of Unmanned Aerial System Thermal Infrared Remote Sensing For Use In Energy Balance Models In Agriculture Applications, Mitchell S. Maguire, C.M.U. Neale, Wayne E. Woldt

Department of Mechanical and Materials Engineering: Faculty Publications

Unmanned aerial system (UAS) remote sensing has rapidly expanded in recent years, leading to the development of several multispectral and thermal infrared sensors suitable for UAS integration. Remotely sensed thermal infrared imagery has been used to detect crop water stress and manage irrigation by leveraging the increased thermal signatures of water stressed plants. Thermal infrared cameras suitable for UAS remote sensing are often uncooled microbolometers. This type of thermal camera is subject to inaccuracies not typically present in cooled thermal cameras. In addition, atmospheric interference also may present inaccuracies in measuring surface temperature. In this study, a UAS with integrated …

Durability Of Concrete Using Foundry Waste Sand, Meshari Alrajab

Morehead State Theses and Dissertations

A thesis presented to the faculty of the College of Business and Technology Morehead State University in partial fulfillment of the requirements for the Degree Master of Science by Meshari Alrajab on April 20, 2021.

Quantifying Surface Morphology Of Manufactured Activated Carbon And The Waste Coffee Grounds Using The Getis-Ord-Gi* Statistic And Ripley’S K Function, Sanghoon Lee, Sukjoon Na, Olivia G. Rogers, Sungmin Youn

All Engineering Faculty Research

Activated carbon can be manufactured from waste coffee grounds via physical and/or chemical activation processes. However, challenges remain to quantify the differences in surface morphology between manufactured activated carbon granules and the waste coffee grounds. This paper presents a novel quantitative method to determine the quality of the physical and chemical activation processes performed in the presence of intensity inhomogeneity and identify surface characteristics of manufactured activated carbon granules and the waste coffee grounds. The spatial density was calculated by the Getis-Ord-Gi* statistic in scanning electron microscopy images. The spatial characteristics were determined by analyzing Ripley’s K function and complete …

Lecture 00: Opening Remarks: 46th Spring Lecture Series, Tulin Kaman

Mathematical Sciences Spring Lecture Series

Opening remarks for the 46th Annual Mathematical Sciences Spring Lecture Series at the University of Arkansas, Fayetteville.

Securing Pint Glasses On Serving Trays With Magnetic Attachments, Jayden Commendatore

Senior Theses

It is extremely common for servers in the restaurant industry to have pint glasses slip off their serving tray, wasting both time and money for the restaurant. I have designed a sleeve attachment that will clip on to the bottom of a pint glass. The metal sleeve attachment will be attracted to a magnet placed into the serving tray. This increases the normal force of the pint glass, resulting in an increase in the friction force between the tray and sleeve attachment, and helping secure the glass to the tray. In order to optimize the design, the value of the …

Six-Sigma Quality Management Of Additive Manufacturing, Hui Yang, Prahalad Rao, Timothy Simpson, Yan Lu, Paul Witherell, Abdalla R. Nassar, Edward Reutzel, Soundar Kumara

Department of Mechanical and Materials Engineering: Faculty Publications

Quality is a key determinant in deploying new processes, products, or services and influences the adoption of emerging manufacturing technologies. The advent of additive manufacturing (AM) as a manufacturing process has the potential to revolutionize a host of enterprise-related functions from production to the supply chain. The unprecedented level of design flexibility and expanded functionality offered by AM, coupled with greatly reduced lead times, can potentially pave the way for mass customization. However, widespread application of AM is currently hampered by technical challenges in process repeatability and quality management. The breakthrough effect of six sigma (6S) has been demonstrated in …

Anisotropic Scaffolds For Peripheral Nerve And Spinal Cord Regeneration, Wen Xue, Wen Shi, Yunfan Kong, Mitchell Kuss, Bin Duan

Department of Mechanical and Materials Engineering: Faculty Publications

The treatment of long-gap (>10 mm) peripheral nerve injury (PNI) and spinal cord injury (SCI) remains a continuous challenge due to limited native tissue regeneration capabilities. The current clinical strategy of using autografts for PNI suffers from a source shortage, while the pharmacological treatment for SCI presents dissatisfactory results. Tissue engineering, as an alternative, is a promising approach for regenerating peripheral nerves and spinal cords. Through providing a beneficial environment, a scaffold is the primary element in tissue engineering. In particular, scaffolds with anisotropic structures resembling the native extracellular matrix (ECM) can effectively guide neural outgrowth and reconnection. In …

Assessing Change In Runoff Water Parameters Through Road Shoulder Vegetated Filter Strips: Experimental Comparison Of Soils And Engineered Infiltration Media, Andrew Corrado, Mohammad Shokri

The Pegasus Review: UCF Undergraduate Research Journal

Placement of Vegetated Filter Strips (VFS) along roadways may facilitate removal of nutrients from stormwater runoff. The objective of this research is to compare water quality performance of a VFS containing engineered media to that of typical Florida sandy soil. Storms of variable intensity were simulated over two 1:1 scale physical models of typical one- and two-lane roadway shoulders, one with engineered media (treatment), and one without (control). Simulated roadway runoff was introduced as sheet flow from the roadway and precipitation was applied with a rainfall simulator. Samples of runoff and infiltrate were tested for Dissolved Oxygen (DO) concentration and …

Dynamics Of Running Processes In The Area Of Underless Water Intake, D.R. Bazarov, M.P. Tashkhanova, A. Gayur, M. Sapaeva

Irrigation and Melioration

The paper analyzes the dynamics of channel processes based on the results of field studies of the Amudarya River at the site of the damless water intake to the Karshi Magistralny Canal (KMK) and developed recommendations for improving the water intake conditions. Based on the results of field studies of the head section of the inlet channel, an assessment of the state of the Amudarya river bed in the water intake zone was made. The results of studies of the hydraulic and alluvial regimes of the Amu Darya River in the area of the damless water intake are generalized The …

Determination Of The Optimal Hydromodule Of Irrigation Network For Drip Irrigation, R.Zh. Karshiev, A. Urazkeldiev, A.H. Radjabov, A.I. Ernazarov

Irrigation and Melioration

Most of the irrigation canals operating in the country were built in the 60s and 80s of the XX century, their hydraulic parameters were designed and adapted to the irrigation regimes of agricultural crops, mainly for surface irrigation, and the average hydromodule values were 0,8-1,0 l / s. , the hydraulic parameters of the channel are designed to carry large volumes of water in a short period of time. Over the next 3-4 years, the introduction of water-saving technologies in the irrigation of agricultural crops by farms and "Clusters" requires the improvement of hydraulic methods of irrigation management, the use …

Assessment Of The Impact Of Climate Change On Hydrological Processes In The Chirchik River Basin, Kh.Sh. Gafforov, Sh.D. Sh.D.Tursunboev

Irrigation and Melioration

The importance of assessing past and future climate differences plays an important role in future planning in relation to climate change. This situation requires urgent and concerted action in several areas: technology, infrastructure, politics, economics, and the environment. The article evaluates the impact of changes in precipitation intensity on the water level in the global circulation model (GCM) RCP 4.5 and 8.5 scenarios in the 2030s, 2050s, and 2070s. This study is a useful reference for improving water resource management and ensuring the sustainability of agricultural products in the future, as well as for improving operational water management and agricultural …

Assessment Of The Impact Of Climate Change On Hydrological Processes In The Chirchik River Basin, В.K. Saliev

Irrigation and Melioration

The article examines the assessment of the state and problems of irrigation water use in the republic in the past and in the near future. A comparative analysis of the state of water resources use for the period of the last 30 years from 1989 to 2019 was carried out.According to the estimates, own water withdrawal for 5 years (2014/15-2018/19) shows that an average of 53.2 m3, including 50.5 billion m3 from rivers At present (2018-2019), an average of 57.06 billion m3 of water is taken for irrigation of 4.289 million hectares of land, against 63.02 billion m3 approved in …

Environmental Damage Caused By Transport Equipment Waste, M. Radkevich, K. Shipilova, M. Abdukodirova, O. Pochugevski

Irrigation and Melioration

The article suggests a new approach to the monetary assessment of the damage caused to the environment by the processed waste of the transport sector. The proposed assessment method is based on the waste collection factor, all types of irretrievable losses and the volume of necessary compensatory release of materials. Based on a survey among vehicle owners, it was found that the solid waste collection rate is about 50 %, while the waste collection rate for operating fluids does not exceed 32 %. In this regard, the bulk of the damage to the environment is caused by liquid waste. Calculations …

Research Of Stress-Deformed State Of Multi-Connected Complex Shell Structures, Т.М. Маvlanov, Sh.O. Khudainazarov, B. Yalgashev, O.S. Nurova

Irrigation and Melioration

Conducting numerical experiments for complex structurally inhomogeneous structures allows us to understand the qualitative picture of the effect of various parameters in a wide range of studies and to give sound recommendations at the design stage for conducting laboratory model and field experiments. In this paper, on the basis of the classical theory of elasticity, the basic equations characterizing the stress-strain state of complex multiply connected shell structures are given and a specific problem is solved. At the same time, some of the structural elements have viscoelastic properties. When solving the problem, the behavior of the structure for the n-th …

To The Determination Of The Critical Circuit Speed Of The Sharing Drum, Kh. Kh. Igamberdiev, A.B. Mukhitdinov

Irrigation and Melioration

The article is devoted to the theoretical definition of the critical circumferential speed of the stripping drum of a kena harvester, which depends on the drum diameter, diameter and weight of the stems. It was determined from the equality of the change in the momentum of the stem during impact, i.e. from a shock impulse acting on the stem. The shock impulse is determined when the drum blade touches the stem in the process of stripping, which acts on the mass of the entire stem. The duration of the impact of the drum stripping on the stem was determined from …

An Innovative Seeder For Sowing Non-Loose Seeds Of Saxaul And Cherkez, E.T. Farmonov

Irrigation and Melioration

The main reasons for the absence of a seeder for mechanized sowing of non-loose seeds of fodder plants in deserts are analyzed in the article. The author has developed a technology for sowing non-loose seeds (saxaul and cherkez), which prevents clogging, crushing and breakage in the seeder hopper, and provides for uniform and stable sowing at a set rate and shallow depth over the entire field area without reducing the biological germination. An innovative seeder with a universal sowing unit is recommended. Field tests of the innovative seeder with the proposed universal sowing unit were conducted in February 2020, as …

Recommendations For The Analysis And Safety Assessment Of Turbid Sediments In Flood Reservoirs, А. Yangiev, Sh. Panjiev, D. Adjimuradov

Irrigation and Melioration

The article presents the results of field research conducted in Langar, Dehkanabad, Shurabsoy flood reservoirs in the Kashkadarya region.There are many problems as a result of floods in the reservoirs, there are disturbances in the discharge and drainage facilities during the passage of accidental floods.At the same time, there was a large accumulation of turbid-sediments in flood reservoirs.In the article, the results of the calculations using empirical formulas for predicting the amount of turbid sediments in Langar, Dehkanabad, Shurabsoy flood reservoirs up to 2025-2030 years are also presented, and it is noted that at present their useless volumes are full …

Justification Of Parameters Of Replaceable Working Parts Of A Combined Machine, А.A. Akhmetov, L.B. Muratov

Irrigation and Melioration

In article are described the design and options for completing the replaceable working parts of the combined machine for continuous tillage which of the formation of ridges and ridges for sowing re-crops. The parameters of the ridge former and apron-leveler of this machine have been substantiated. The rational values of the parameters of the comb-former are: length 600 mm, width of the entrance edge 680 mm, height of the blade 160 mm, length of the side edge of the blade 178 mm. The rational values of the working length and height of the leveling apron are 220 mm and 200 …

Development Of An Algorithm For Optimization Of Continuous Technological Process Of Cultivation Of Microorganisms, Sh.R. Rakhmanov

Irrigation and Melioration

In article the analysis of possible modes of microalgae cultivation has been carried out. Two optimization algorithms are substantiated. The first one is based on the method of random search with an absolute bias, an algorithm for optimizing the process of cultivating microorganisms with continuous regeneration of the flow in one cultivator. The second is an algorithm for determining the optimal residence time of chlorella particles in multistage cultivators, focused on the method of dynamic programming, implemented in Wellman's recurrence relation. The developed algorithm for operational forecasting and automatic control of the chlorella cultivation process allows, under given production conditions …