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Articles 40741 - 40770 of 195926
Full-Text Articles in Engineering
Validation Of Athlet-Cd With Cora-28 Test, Murat Tuter
Validation Of Athlet-Cd With Cora-28 Test, Murat Tuter
Masters Theses
“Following the incidents at Chernobyl and Fukushima, severe accidents at nuclear power plants (NPP) have become a global concern. These accidents generally occur because of a failure in the reactor cooling system (RCS) and result in the melting of the reactor core and fission product release. This event is mostly caused by a LOCA, loss of flow accident, station blackout or loss of heat sink. During a severe accident, generation of hydrogen as a result of steam-zircaloy fuel cladding is a significant safety concern. To better understand and prevent the hydrogen generation issue, safety related experiments and safety related codes …
Pressure Relief Wells: Analysis Of Subsurface Heterogeneity To Evaluate Relief Well Locations For Mississippi River Levees, Emma Marie Young
Pressure Relief Wells: Analysis Of Subsurface Heterogeneity To Evaluate Relief Well Locations For Mississippi River Levees, Emma Marie Young
Masters Theses
“When designing pressure relief well systems, it is imperative to understand what major geomorphology and heterogenies features are present, such as buried oxbow lakes, especially when the feature is parallel to the source, such as the Mississippi River. When present, there is a notable greater increase in head pressures, especially on the landward tow of the levee. This can cause erosional features that originally thought of to have been protected from by installing pressure relief wells. When comparing the effective hydraulic conductivities of horizontal clay layers and vertical clay layers spanning the length of the model, little to no noticeable …
Controlling Microalloy Interactions On Precipitation, Hot Ductility, And Microstructure -- Mechanical Property Relationships, Madhuri Varadarajan
Controlling Microalloy Interactions On Precipitation, Hot Ductility, And Microstructure -- Mechanical Property Relationships, Madhuri Varadarajan
Masters Theses
“One of the main problems faced in the continuous casting of micro-alloy steels is the formation of transverse cracks. Transverse cracks are surface, or near-surface cracks formed perpendicular to the casting direction. The research focuses on using laboratory hot tensile tests methods to determine the low ductility ranges in high strength steel grades with different micro-alloy additions of titanium, niobium, and vanadium. The hot ductility of commercially produced as-cast slab and beam blank samples was evaluated using two experimental methods: tensile testing utilizing a servo-hydraulic load frame with a resistance furnace and thermomechanical testing using rapid Joule heating. The tests …
Array Signal Processing For Source Localization And Enhancement, Sohel J. Patel
Array Signal Processing For Source Localization And Enhancement, Sohel J. Patel
Doctoral Dissertations
“A common approach to the wide-band microphone array problem is to assume a certain array geometry and then design optimal weights (often in subbands) to meet a set of desired criteria. In addition to weights, we consider the geometry of the microphone arrangement to be part of the optimization problem. Our approach is to use particle swarm optimization (PSO) to search for the optimal geometry while using an optimal weight design to design the weights for each particle’s geometry. The resulting directivity indices (DI’s) and white noise SNR gains (WNG’s) form the basis of the PSO’s fitness function. Another important …
Evaluating Essential Processes And Forecast Requirements For Meteotsunami-Induced Coastal Flooding, Chenfu Huang, Eric Anderson, Yi Liu, Gangfeng Ma, Greg Mann, Pengfei Xue
Evaluating Essential Processes And Forecast Requirements For Meteotsunami-Induced Coastal Flooding, Chenfu Huang, Eric Anderson, Yi Liu, Gangfeng Ma, Greg Mann, Pengfei Xue
Civil & Environmental Engineering Faculty Publications
Meteotsunamis pose a unique threat to coastal communities and often lead to damage of coastal infrastructure, deluge of nearby property, and loss of life and injury. The Great Lakes are a known hot-spot of meteotsunami activity and serve as an important region for investigation of essential hydrodynamic processes and model forecast requirements in meteotsunami-induced coastal flooding. For this work, we developed an advanced hydrodynamic model and evaluate key model attributes and dynamic processes, including: (1) coastal model grid resolution and wetting and drying process in low-lying zones, (2) coastal infrastructure, including breakwaters and associated submerging and overtopping processes, (3) annual/seasonal …
Backlog Burner: An Adventure Into Automated Scheduling, Anjolaoluwa J. Olubusi
Backlog Burner: An Adventure Into Automated Scheduling, Anjolaoluwa J. Olubusi
Senior Independent Study Theses
The focus of this independent study is to explain the nurse scheduling problem (NSP) and use it as a basis to create an automated scheduling program. The nurse scheduling problem is an operational research problem that sets to find an optimal hospital schedule that fulfills the needs of the hospital and the personal requests of the nurses. The majority of solutions for the nurse scheduling problem are often designed within a hospital setting. The objective of this independent study is to use the solutions of the nurse scheduling problem to develop an automated scheduling program for the College of Wooster …
Investigation Of The Combustion Of Exhaust Gas Recirculation In Diesel Engines With A Particulate Filter And Selective Catalytic Reactor Technologies For Environmental Gas Reduction, Megavath Vijay Kumar, Alur Veeresh Babu, Ch. Rami Reddy, A. Pandian, Mohit Bajaj, Hossam Zawbaa, Salah Kamel
Investigation Of The Combustion Of Exhaust Gas Recirculation In Diesel Engines With A Particulate Filter And Selective Catalytic Reactor Technologies For Environmental Gas Reduction, Megavath Vijay Kumar, Alur Veeresh Babu, Ch. Rami Reddy, A. Pandian, Mohit Bajaj, Hossam Zawbaa, Salah Kamel
Articles
The Diesel Engine, invented by the German engineer Rudolf Diesel, was a marvelous creation that changed the way the automobile industry worked. It is an internal combustion engine that compresses air to elevate its pressure and temperature so high that the atomized diesel fuel undergoes combustion almost instantaneously when it is sprayed into the combustion chamber. The Major advantage of a Compression Ignition (CI) engine compared to a Spark Ignition (SI) engine is the higher compression ratio achieved in the former, making it more efficient. This makes diesel engines more suitable for heavy-duty vehicles, which require more torque to overcome …
Modeling Cognitive Load As A Self-Supervised Brain Rate With Electroencephalography And Deep Learning, Luca Longo
Modeling Cognitive Load As A Self-Supervised Brain Rate With Electroencephalography And Deep Learning, Luca Longo
Articles
The principal reason for measuring mental workload is to quantify the cognitive cost of performing tasks to predict human performance. Unfortunately, a method for assessing mental workload that has general applicability does not exist yet. This is due to the abundance of intuitions and several operational definitions from various fields that disagree about the sources or workload, its attributes, the mechanisms to aggregate these into a general model and their impact on human performance. This research built upon these issues and presents a novel method for mental workload modelling from EEG data employing deep learning. This method is self-supervised, employing …
Examining The Size Of The Latent Space Of Convolutional Variational Autoencoders Trained With Spectral Topographic Maps Of Eeg Frequency Bands, Taufique Ahmed, Luca Longo
Examining The Size Of The Latent Space Of Convolutional Variational Autoencoders Trained With Spectral Topographic Maps Of Eeg Frequency Bands, Taufique Ahmed, Luca Longo
Articles
Electroencephalography (EEG) is a technique of recording brain electrical potentials using electrodes placed on the scalp [1]. It is well known that EEG signals contain essential information in the frequency, temporal and spatial domains. For example, some studies have converted EEG signals into topographic power head maps to preserve spatial information [2]. Others have produced spectral topographic head maps of different EEG bands to both preserve information in The associate editor coordinating the review of this manuscript and approving it for publication was Ludovico Minati . the spatial domain and take advantage of the information in the frequency domain [3]. …
Introduction To The Special Issue On Gala Conf 2021, Francesca De Rosa, Jannicke Baalsrud Hauge, Pierpaolo Dondio, Isa Marfizi-Schottman, Margarida Romero, Francesco Bellotti
Introduction To The Special Issue On Gala Conf 2021, Francesca De Rosa, Jannicke Baalsrud Hauge, Pierpaolo Dondio, Isa Marfizi-Schottman, Margarida Romero, Francesco Bellotti
Articles
This special issue of the International Journal of Serious Games is dedicated to the selected best papers of the 2021 edition of the GALA conference. This edition was organized by Francesca De Rosa and her team at NATO Centre for Maritime Research and Experimen-tation (CMRE), La Spezia, Italy. Because of the Covid-19 pandemic, it was held online, for the second year. The three papers published in this special issue were first selected for a content exten-sion, so to make them suitable as journal papers, then underwent the regular IJSG peer-review process, which, on the other hand, discarded other three selected …
Power Management In Hybrid Anfis Pid Based Ac–Dc Microgrids With Eho Based Cost Optimized Droop Control Strategy, T. Narasimha Prasad, S. Devakirubakaran, S. Muthubalaji, S. Srinivasan, B. Karthikeyan, R. Palanisamy, Mohit Bajaj, Hossam Zawbaa, Salah Kamel
Power Management In Hybrid Anfis Pid Based Ac–Dc Microgrids With Eho Based Cost Optimized Droop Control Strategy, T. Narasimha Prasad, S. Devakirubakaran, S. Muthubalaji, S. Srinivasan, B. Karthikeyan, R. Palanisamy, Mohit Bajaj, Hossam Zawbaa, Salah Kamel
Articles
One of the most critical operations aspects is power management strategies for hybrid AC/DC microgrids. This work presented power management in hybrid AC–DC microgrids with a droop control strategy. At first, photovoltaic, Wind, and battery are used as the power sources, which supply the power with uncertainties. The AC and DC microgrids are controlled by an Adaptive neuro-fuzzy inference system (ANFIS) controller and Proportional Integral Derivative (PID) controller. Simultaneously we calculate the running cost for photovoltaic, Wind, and Battery. Moreover, an optimizer based on the elephant herding optimization algorithm is formulated to reduce the cost price. This method utilizes two …
The Association Between Ambient Uvb Dose And Anca‑Associated Vasculitis Relapse And Onset, Jennifer Scott, Enock Havyarimana, Albert Navarro-Gallinad, Arthur White, Jason Wyse, Jos Van Geffen, Michiel Van Weele, Antonia Buettner, Tamara Wanigasekera, Cathal Walsh, Louis Aslett, John Kelleher, Julie Power, James Ng, Declan O’Sullivan, Lucy Hederman, Neil Basu, Mark A. Little, Lina Zgaga
The Association Between Ambient Uvb Dose And Anca‑Associated Vasculitis Relapse And Onset, Jennifer Scott, Enock Havyarimana, Albert Navarro-Gallinad, Arthur White, Jason Wyse, Jos Van Geffen, Michiel Van Weele, Antonia Buettner, Tamara Wanigasekera, Cathal Walsh, Louis Aslett, John Kelleher, Julie Power, James Ng, Declan O’Sullivan, Lucy Hederman, Neil Basu, Mark A. Little, Lina Zgaga
Articles
The aetiology of ANCA-associated vasculitis (AAV) and triggers of relapse are poorly understood. Vitamin D (vitD) is an important immunomodulator, potentially responsible for the observed latitudinal differences between granulomatous and non-granulomatous AAV phenotypes. A narrow ultraviolet B spectrum induces vitD synthesis (vitD-UVB) via the skin. We hypothesised that prolonged periods of low ambient UVB (and by extension vitD deficiency) are associated with the granulomatous form of the disease and an increased risk of AAV relapse.
A Privacy Preserving Online Learning Framework For Medical Diagnosis Applications, Trang Pham Ngoc Nguyen
A Privacy Preserving Online Learning Framework For Medical Diagnosis Applications, Trang Pham Ngoc Nguyen
Theses: Doctorates and Masters
Electronic Health records are an important part of a digital healthcare system. Due to their significance, electronic health records have become a major target for hackers, and hospitals/clinics prefer to keep the records at local sites protected by adequate security measures. This introduces challenges in sharing health records. Sharing health records however, is critical in building an accurate online diagnosis framework. Most local sites have small data sets, and machine learning models developed locally based on small data sets, do not have knowledge about other data sets and learning models used at other sites.
The work in this thesis utilizes …
Development Of An Explainability Scale To Evaluate Explainable Artificial Intelligence (Xai) Methods, Stephen Mccarthy
Development Of An Explainability Scale To Evaluate Explainable Artificial Intelligence (Xai) Methods, Stephen Mccarthy
Dissertations
Explainable Artificial Intelligence (XAI) is an area of research that develops methods and techniques to make the results of artificial intelligence understood by humans. In recent years, there has been an increased demand for XAI methods to be developed due to model architectures getting more complicated and government regulations requiring transparency in machine learning models. With this increased demand has come an increased need for instruments to evaluate XAI methods. However, there are few, if none, valid and reliable instruments that take into account human opinion and cover all aspects of explainability. Therefore, this study developed an objective, human-centred questionnaire …
An Investigation Of The Relationship Between Subjective Mental Workload And Objective Indicators Of User Activity, Greg Byrne
Dissertations
Whilst the concept of physical workload is intuitively understood and readily applicable in system design, the same cannot be said of mental workload (MWL), despite its importance in our increasingly technological society. Despite its origin in the mid 20th century, the very concept of ”mental workload” is still a topic of debate in the literature, although it can be loosely defined as “the amount of mental work necessary for a person to complete a task” (Miller, 1956; Longo, 2014). Several methods have been utilized to measure of MWL, including physiological methods such as neuro-imagery, performance-based metrics, and subjective measures via …
Long-Term Durability Of Rooftop Grid-Connected Solar Photovoltaic Systems, Chibuisi Chinasaokwu Okorieimoh
Long-Term Durability Of Rooftop Grid-Connected Solar Photovoltaic Systems, Chibuisi Chinasaokwu Okorieimoh
Doctoral
Compared to their initial performance, solar photovoltaic (PV) arrays show long-term performance degradation, resulting in lower like-for-like efficiencies and performance ratios. The long-term durability of polycrystalline silicon (p-Si) solar PV modules in three roof-top grid-connected arrays has been examined. Electrical output, ambient temperature, cell temperature, solar irradiance, solar irradiation, and wind speed data were collected at hourly intervals from 2017 to 2021 from three 50 kWp PV installations in Northern Ireland. The results show the extent to which higher PV temperatures associated with more intense solar radiation decrease efficiency, fill factor and maximum power output for PV arrays in a …
Experimental Analysis And Computer Simulation Of A Laboratory-Scale Intermittent Water Supply System, Brian Rivers
Experimental Analysis And Computer Simulation Of A Laboratory-Scale Intermittent Water Supply System, Brian Rivers
Dissertations, Master's Theses and Master's Reports
Intermittent water systems (IWS) are prevalent throughout developing regions of the world. However, few tools exist to predict IWS performance because modeling transient flow is difficult: IWS networks can experience widely fluctuating conditions, ranging from completely empty to completely full (pressurized flow). An experimental IWS, consisting of a 50.75-gallon reservoir, an elevated distribution network, and four outlets was constructed to study the hydraulics of IWS. Three experiments were run on the system that represented two falling-head scenarios and a constant-head scenario. Computer simulation models of the experimental IWS were developed in EPANET 2.2.0 and EPA-SWMM 5.1, which are open-source modeling …
Per- And Polyfluoroalkyl Substances Mitigation From Contaminated Groundwater Using Halophyte And Cow Bone Biochars, Bailey Papes
Per- And Polyfluoroalkyl Substances Mitigation From Contaminated Groundwater Using Halophyte And Cow Bone Biochars, Bailey Papes
Dissertations, Master's Theses and Master's Reports
Per- and polyfluoroalkyl substances (PFAS) groundwater contamination is a growing concern for the Brackish Groundwater National Desalination Research Facility. Two of the four wells onsite are contaminated with perfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid (PFOS), and perfluorohexane sulfonic acid (PFHxS). The removal of PFAS by adsorption onto powder activated carbon (PAC) is promising, but the production of PAC is energy intensive and expensive. A potential cost-effective alternative to PAC is biochar. This study quantified the capacities of two halophyte biochars, cow bone biochar and PAC to adsorb PFOA, PFOS, and PFHxS from brackish groundwater. The three biochars were ineffective at …
Wireless Power Transfer In Autonomous Mobile Microgrids, Carl Greene
Wireless Power Transfer In Autonomous Mobile Microgrids, Carl Greene
Dissertations, Master's Theses and Master's Reports
The ability to autonomously dock unmanned ground vehicles plays a key role in mobile micro-grids, where efficient power transfer is paramount. The approach utilized in this work allows for near-field wireless power transfer in remote locations with minimal support. Establishing a micro-grid power system connection autonomously using wireless power eliminates the arduous task of designing a complex, multiple degrees of freedom (MDOF) robotic arm. The work presented in this thesis focuses on both the hardware and software within the micro-grid system. This particular near-field wireless system consists of a primary and secondary set of modules, comprised of Litz wire coils, …
Simulating Groundwater Pollutant Transport For Remediation Design, Antrim County, Michigan, Abilynn Raetz
Simulating Groundwater Pollutant Transport For Remediation Design, Antrim County, Michigan, Abilynn Raetz
Dissertations, Master's Theses and Master's Reports
Located in Antrim County, Michigan between the coasts of Torch Lake and Lake Michigan is a hydrocarbon plume that has impacted surrounding residential wells. The plume is comprised of benzene, toluene, ethylbenzene, and xylenes (BTEX) and primarily resides in the shallowest groundwater aquifer. The plume is suspected of having originated from an underground storage container that was removed in 1979. A conceptual model was developed for the site, comprising of a simplified hydrogeological model. Groundwater modeling was performed using Aquaveo's groundwater modeling software (GMS). PEST parameter calibration was performed on the hydraulic conductivity and recharge values using data from surrounding …
Eager Scheduling Of Dependent Instructions, Kurush Kasad
Eager Scheduling Of Dependent Instructions, Kurush Kasad
Dissertations, Master's Theses and Master's Reports
Modern superscalar processors are able to potentially issue and execute multiple instructions per cycle. Several techniques over the years have focused on increasing the Instruction Level Parallelism (ILP) that a processor can exploit. However, there are many limitations of ILP that hinder performance, chief of them being the chain of dependencies between instructions that stops instructions from being executed in parallel.
We propose a new micro-architecture design which extends the superscalar pipeline with a data-flow pipeline where the dataflow part identifies immediately dependent instructions and executes them early. The dataflow pipeline is able to identify redundant instructions, track changes in …
An Experimental Study Towards Underwater Propulsion System Using Structure Borne Traveling Waves, Shreyas Suhas Gadekar
An Experimental Study Towards Underwater Propulsion System Using Structure Borne Traveling Waves, Shreyas Suhas Gadekar
Dissertations, Master's Theses and Master's Reports
The method of generating steady-state structure-borne traveling waves underwater in an infinite media creates abundant opportunities in the field of propulsive applications, and they are gaining attention from several researchers. This experimental study provides a framework for harnessing traveling waves in a 1D beam immersed under quiescent water using two force input methods and providing a motion to an object floating on the surface of the water.
In this study, underwater traveling waves are tailored using structural vibrations at five different frequencies in the range of 10Hz to 300Hz. The resulting fluid motion provides a propulsive thrust that moves a …
Permeability, Structural Changes, Flow Regime Transitions In Fuel Cell Catalyst Layers And A Model For Predicting Trapped Saturation For Two-Phase Flow In Porous Media, Karrar Takleef Alofari
Permeability, Structural Changes, Flow Regime Transitions In Fuel Cell Catalyst Layers And A Model For Predicting Trapped Saturation For Two-Phase Flow In Porous Media, Karrar Takleef Alofari
Dissertations, Master's Theses and Master's Reports
Proper water management in Proton Exchange Membrane (PEM) fuel cell is important to achieve high performance. Understanding the percolation of the produced water at the cathode catalyst layer (CL) is critical for any robust water management technique. In this study, an ex-situ experimental setup is used to study percolation in the CL at different injection rates and relative humidity (RH) conditions. The results show that increasing the flow rate force the liquid to flow through the bulk of the pores due to the dominant viscous effect. On the other hand, at low injection rates, the capillary becomes dominant and liquid …
Length-Scale-Dependent Stress Relief Mechanisms In High Purity Indium, Fereshteh Mallakpour
Length-Scale-Dependent Stress Relief Mechanisms In High Purity Indium, Fereshteh Mallakpour
Dissertations, Master's Theses and Master's Reports
Lithium-ion batteries are widely used in portable electronics and electric vehicles. However, due to the presence of flammable liquid electrolytes, these devices fail catastrophically when the cell experiences a short circuit. One attractive solution to this problem is a solid-state battery. As the name implies, the flammable liquid electrolyte is replaced by a non-flammable solid-state electrolyte (SSE). The unexpected, yet frequently observed failure mechanism in these devices is the formation and growth of lithium dendrites originating at the interface between the lithium anode and the SSE. As the dendrites grow, device performance degrades. Once the dendrites completely penetrate the SSE, …
Understanding Strength Of Dried Iron Ore Pellets, Victor Claremboux
Understanding Strength Of Dried Iron Ore Pellets, Victor Claremboux
Dissertations, Master's Theses and Master's Reports
After an extensive literature review, it was found that there was no reliable way for predicting the impact of binders or mixtures of binders on iron ore pellets. This is a challenging problem because iron ore pellets are a complex product of an agglomeration process which is typically controlled only to the extent that is necessary to form a quality product for ironmaking. This work identifies the resistance of a dried pellet to abrasion as a prime variable to record and analyze to understand the influence of combined pellet binders. A consistent method of measuring abrasion resistance is identified and …
The Role Of Inclusion In Climate Vulnerability Assessment And Equitable Adaptation Goals In Small American Municipalities, Elena Lioubimtseva
The Role Of Inclusion In Climate Vulnerability Assessment And Equitable Adaptation Goals In Small American Municipalities, Elena Lioubimtseva
Open Access Publishing Support Funded Articles
Equity and inclusion considerations are important prerequisites of effective climate adaptation planning, especially at a local scale. This study examines how climate adaptation plans of small American cities and counties consider equity in their climate vulnerability assessments and adaptation planning goals and how consideration of equity in existing adaptation plans relates to the inclusion of diverse categories of stakeholders. Data analysis is based on the content of 23 local climate adaptation plans of small urban and rural municipalities across the United States with populations of less than 300 thousand people. Correlations between conceptualization of vulnerability dimensions, inclusion of 9 categories …
Effect Of Silica Size In Ticl4/Mgcl2-Sio2 Catalysts On Ethylene Polymerization Behaviors, Nattawat Manomaiwajee
Effect Of Silica Size In Ticl4/Mgcl2-Sio2 Catalysts On Ethylene Polymerization Behaviors, Nattawat Manomaiwajee
Chulalongkorn University Theses and Dissertations (Chula ETD)
At present, the production of polyethylene has a high production volume. The commonly used catalyst for the synthesis of polyethylene is Ziegler-Natta. The development of polymer morphology and efficiency of ethylene polymerization in the petrochemical industry was developed by the addition of silica supports. However, the specific properties of silica have not been widely researched with the Ziegler-Natta catalyst. Therefore, the effect of silica size on the Ziegler-Natta catalyst was studied in this thesis. The study focused on the polymerization of ethylene and the copolymerization of ethylene/1-hexene in slurry process. The silica sizes used as bisupport were varied including 8 …
ประสิทธิภาพตัวกลางดูดซับสำหรับกำจัดสารหนูจากน้ำบาดาลในพื้นที่จังหวัดระยอง, วรรณพศุกร์ สิทธิผล
ประสิทธิภาพตัวกลางดูดซับสำหรับกำจัดสารหนูจากน้ำบาดาลในพื้นที่จังหวัดระยอง, วรรณพศุกร์ สิทธิผล
Chulalongkorn University Theses and Dissertations (Chula ETD)
งานวิจัยนี้มีวัตถุประสงค์เพื่อศึกษาประสิทธิภาพตัวกลางดูดซับสำหรับกำจัดสารหนูจากน้ำบาดาล โดยศึกษาตัวกลางดูดซับ 3 กลุ่ม คือ วัสดุโครงข่ายโลหะอินทรีย์ วัสดุที่มีทางการค้า และวัสดุทางการเกษตร โดยถ่านกัมมันต์ทางการค้าชนิดเกล็ด (Granular activated carbon, GAC) ถูกนำมาปรับสภาพด้วยสารปรับสภาพ 2 ชนิด ได้แก่ การเคลือบด้วย Zeolitic idazolate framework และเหล็กไนเตรท ส่วนถ่านมันสำปะหลังถูกปรับสภาพพื้นผิวด้วยเหล็กไนเตรท จากการศึกษาประสิทธิภาพการดูดซับสารหนูเบื้องต้นเพื่อคัดเลือกวัสดุที่มีความเหมาะสมในการนำไปใช้งานในระบบคอลัมน์พบว่า ถ่านกัมมันต์ทางการค้าชนิดเกล็ดที่ปรับสภาพด้วยเหล็กไนเตรท (GAC-120-250Fe) มีความเหมาะสมในการนำไปใช้งานในระบบคอลัมน์เนื่องจากมีความสามารถในการดูดซับสารหนูได้เพียงพอ มีความแข็งแรงของโครงสร้างอนุภาค และมีการชะละลายเหล็กและสารอินทรีย์ละลายน้ำต่ำ ผลการศึกษาจลนพลศาสตร์และไอโซเทอร์มการดูดซับสารหนูของ GAC-120-250Fe พบว่า สอดคล้องกับสมการอันดับสองเทียมและสมการของฟรุนดลิช ตามลำดับ การวิเคราะห์การชะละลายของเหล็กและสารอินทรีย์ละลายน้ำพบว่าค่าทั้งสองมีค่าต่ำกว่ามาตรฐานน้ำบาดาลดื่มได้ ส่วนการศึกษาการดูดซับในระบบคอลัมน์พบว่า การเพิ่มความสูงของชั้นตัวกลางดูดซับส่งผลให้เวลาในการผลิตน้ำจนถึงความเข้มข้นเบรกทรู (Breakthrough) เพิ่มมากขึ้นและเป็นไปตามสมการของโบฮาร์ท-อดัมส์ โดยเส้นกราฟเบรกทรูที่ได้จากการทดลองสอดคล้องกับแบบจำลองของโทมัส ค่าอัตราการใช้ตัวกลางดูดซับ (Usage rate) และค่าเวลาสัมผัส (EBCT) ที่ให้ประสิทธิภาพการดูดซับสารหนูสูงสุดได้แก่ 286.2 มิลลิลิตรต่อกรัม และ 15.7 นาที ตามลำดับ ที่อัตราเร็วการไหลที่ 0.51 เซนติเมตรต่อนาที
Implementing Effective Learning With Ubiquitous Learning Technology During Coronavirus Pandemic, M. Samir Abou El-Seoud, Hosam F. El-Sofany
Implementing Effective Learning With Ubiquitous Learning Technology During Coronavirus Pandemic, M. Samir Abou El-Seoud, Hosam F. El-Sofany
Computer Science
Ubiquitous computing supports U-learning to develop and implement a new educational environment that provides effective and interactive learning to students wherever they are. This study aims to present a qualitative evaluation for using U-learning instead of traditional education to avoid the spread of the Coronavirus pandemic. The authors introduce a UTAUT (Unified Theory of Acceptance and Use of Technology) model to assess the capability of the given factors that are expected to affect the learners’ intention and behavior for accepting the U-learning technology for full E-learning. The research study shows a promising impact on the use of U-learning apps for …
การกำหนดนโยบายบริหารเพื่อเพิ่มประสิทธิภาพการเตรียมอะไหล่คงคลังกรณีศึกษาโรงงานผลิตกรดอะมิโน, พรพัชร จิระเดชะ
การกำหนดนโยบายบริหารเพื่อเพิ่มประสิทธิภาพการเตรียมอะไหล่คงคลังกรณีศึกษาโรงงานผลิตกรดอะมิโน, พรพัชร จิระเดชะ
Chulalongkorn University Theses and Dissertations (Chula ETD)
งานวิจัยนี้นำเสนอนโยบายการบริหารเพื่อเพิ่มประสิทธิภาพในการเตรียมอะไหล่คงคลังกรณีศึกษาโรงงานผลิตกรดอะมิโน ซึ่งมูลค่าอะไหล่คงคลังเฉลี่ยต่อปี มีแนวโน้มเพิ่มขึ้นจาก 8.3 ล้านบาท ปี พ.ศ. 2559 จนถึง 10.5 ล้านบาท ปี พ.ศ. 2564 ซึ่งสวนทางกับมูลค่าการเบิกใช้อะไหล่ที่มีมูลค่าน้อยลง จึงส่งผลให้อัตราหมุนเวียนอะไหล่มีค่าเฉลี่ยต่อปีอยู่ที่ 0.034 และ 0.102 ในปี พ.ศ. 2559 และปี พ.ศ. 2564 ตามลำดับ ซึ่งแสดงให้เห็นว่าอะไหล่ที่ถูกเก็บในคลังมากกว่าความต้องการ ส่งผลให้สูญเสียค่าใช้จ่ายในการเก็บสูง ดังนั้นการเพิ่มประสิทธิภาพในการเตรียมอะไหล่จะถูกพิจารณาการดำเนินงานผ่านนโยบายการตัดสินใจการเก็บอะไหล่ และปริมาณการเก็บคงคลัง โดยเริ่มต้นจากการนำเสนอเมทริกซ์การตัดสินใจการเก็บอะไหล่ ที่ต้องมีการประเมินความวิกฤติอะไหล่ผ่านเมทริกซ์ 1. Part/equipment critical 2. Supplier/lead-time 3. Failure modes and effects criticality analysis และ 4. Decision matrix จากนโยบายการตัดสินใจการเก็บอะไหล่สามารถช่วยตัดสินใจเก็บอะไหล่ที่มีความวิกฤตสูง ส่วนอะไหล่ที่มีความวิกฤตต่ำจะไม่ถูกตัดสินใจเก็บ จากผลการศึกษาพบว่าสามารถลดจำนวนรายการอะไหล่ที่ต้องจัดเก็บลงได้ 40% จากนั้นนำเสนอนโยบายการตัดสินใจปริมาณการเก็บอะไหล่ ด้วยนโยบาย Base stock ใหม่ โดยการพิจารณาโอกาสการเบิกใช้อะไหล่ผ่านการแจกแจงแบบปัวส์ซองแบบสะสม และผลการจำลองด้วยวิธีการมอนติคาร์โลทั้งหมด 30 ครั้ง พบว่ามูลค่าอะไหล่เฉลี่ยลดลง 68% และระดับอะไหล่ลดลง 60% ส่งผลให้มูลค่าคลังเฉลี่ยลดลงจาก 8.7 ล้านเหลือ 2.3 ล้านบาท และอัตราการหมุนเวียนอะไหล่เฉลี่ยเพิ่มขึ้นจาก 0.060 เป็น 0.220 โดยไม่มีอะไหล่ขาดมือ และผลการทดสอบนโยบายกับชุดข้อมูล ปี พ.ศ. 2563 – 2564 พบว่ามูลค่าอะไหล่เฉลี่ยลดลง 24 % และระดับอะไหล่ลดลง 19% โดยไม่มีอะไหล่ขาดมือ