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Articles 2281 - 2310 of 3655
Full-Text Articles in Engineering
Improvement And Economic Analysis Of Bio-Hydrogenated Diesel Production For Producing Bio-Jet Fuel, Nattamon Munkong
Improvement And Economic Analysis Of Bio-Hydrogenated Diesel Production For Producing Bio-Jet Fuel, Nattamon Munkong
Chulalongkorn University Theses and Dissertations (Chula ETD)
In this study, process improvement of bio-hydrogenated diesel (BHD) production to produce jet fuel as an alternative product was carried out. The BHD was produced from palm oil with NiMo/Y-Al2O3 catalyst, while the bio-jet fuel was produced by catalytic cracking of the BHD product using NiAg/SAPO-11 catalyst, followed by appropriate separations. Process simulation by using Aspen Plus program was performed to evaluate the improved process. A comparison with a base case BHD production process was also demonstrated and discussed. It was found that a conventional existing BHD process can be improved by plugging in a hydrocracking/isomerization unit to process. The …
Study Of Co2 And Bi-Reforming Of Methane On Modified Nickel-Based Catalysts, Nichakorn Buasuk
Study Of Co2 And Bi-Reforming Of Methane On Modified Nickel-Based Catalysts, Nichakorn Buasuk
Chulalongkorn University Theses and Dissertations (Chula ETD)
Nowadays, several currently operated industrial factories significantly increase the rate of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) far higher than those that should be normally. Therefore, various mitigation ways to reduce carbon dioxide and methane are increasingly important. The prevailing methods are dry reforming of methane and bi-reforming of methane. Therefore, this research involves the study of the catalytic activity and coke resistance on the Ni-based catalysts with and without a promoter. The activity tests on the dry reforming of methane reaction and bi-reforming of methane reaction were performed in a fixed-bed reactor under atmospheric pressure at …
Development And Characterization Of Natural Rubber-Cellulose Sponge, Nuttapon Suppanucroa
Development And Characterization Of Natural Rubber-Cellulose Sponge, Nuttapon Suppanucroa
Chulalongkorn University Theses and Dissertations (Chula ETD)
Natural rubber (NR) sponges are a renewable biopolymer material derived from milky sap (latex) from rubber trees. In this study, composite sponges of natural rubber and cellulose (NR-C) with various compositions were synthesized. The Dunlop process was employed to prepare the NR-C sponges in various contents of cellulose fibers as reinforcing agent. The cellulose fibers were extracted from the pulp of eucalyptus trees and sodium alginate (SA) was used as dispersing agent. The aim of this work was to develop a green composite sponge with highly porous, flexible, and hydrophilic properties. The effects of cellulose loading on mechanical performance of …
Application Of Co-Solvent For Biodiesel Production In Ultrasound-Assisted Reactor, Panidaporn Ritprasert
Application Of Co-Solvent For Biodiesel Production In Ultrasound-Assisted Reactor, Panidaporn Ritprasert
Chulalongkorn University Theses and Dissertations (Chula ETD)
Biodiesel has been a promising alternative energy due to its renewability and lesser emissions of harmful gases such as carbon monoxide in comparison to traditional petroleum diesel fuel. Mostly, biodiesel production via transesterification requires catalyst to achieve faster reaction rate and complete the reaction. However, mass transfer between two immiscible reactants are obstacle to the biodiesel production. In this work, ultrasound-assisted (US) reactor and addition of co-solvent were used to overcome mass transfer limitation. The condition for biodiesel production from transesterification of palm oil using a circulated US reactor and addition of co-solvent was operated at 60°C, 1 atm, calcium …
Improvement Of Screen Printable Anisotropic Conductive Adhesive With Polyethylene Glycol As Diluent, Papitchaya Manduang
Improvement Of Screen Printable Anisotropic Conductive Adhesive With Polyethylene Glycol As Diluent, Papitchaya Manduang
Chulalongkorn University Theses and Dissertations (Chula ETD)
The primary aim of this research is to improve screen printable anisotropic conductive adhesive by reducing the viscosity of anisotropic conductive adhesive which is EPN/PPGDE/CTBN epoxy adhesive with polyethylene glycol 400. This research compared the conductivity of commercial and synthesized silver particles. As a result, the volume resistivity of commercial silver particles was lower than the synthesized silver particle due to silver oxide of silver particles. 1 phr of commercial silver particle was added in anisotropic conductive adhesive in which its volume resistivity was less than 1 Ω·cm. The effect of addition polyethylene glycol in the anisotropic conductive adhesive with …
Development And Characterization Of Solid Oxide Electrolysis Cells Based On Zirconia And Ceria Based Electrolyte For Hydrogen Production From Steam, Parintorn Temluxame
Development And Characterization Of Solid Oxide Electrolysis Cells Based On Zirconia And Ceria Based Electrolyte For Hydrogen Production From Steam, Parintorn Temluxame
Chulalongkorn University Theses and Dissertations (Chula ETD)
Steam electrolysis for hydrogen production is investigated in solid oxide electrolysis cell (SOEC). Sc3+, Ce4+, and Gd3+ are doped in zirconia (SCGZ) and compared with yttria stabilized zirconia (YSZ) and gadolinium doped ceria (GDC) electrolyte. Electrolyte-supported cells are fabricated. The SCGZ and YSZ electrolytes are dense with >95% relative density while GDC is less densified. The activation energy of conduction of the SCGZ electrolyte is the lowest at 65.58 kJ mol-1 although phase transformation is detected after electrolyte fabrication process. Cathode-supported cell having SCGZ electrolyte (Ni-SCGZ/SCGZ/BSCF) shows the highest electrochemical performance. Durability test of the cells in electrolysis mode is …
Biodiesel Production From Cooking Palm Oil In The Presence Of Cao/Γ-Al2o3 Catalyst Using Rotating Packed-Bed Reactor, Patcharaporn Sukjarern
Biodiesel Production From Cooking Palm Oil In The Presence Of Cao/Γ-Al2o3 Catalyst Using Rotating Packed-Bed Reactor, Patcharaporn Sukjarern
Chulalongkorn University Theses and Dissertations (Chula ETD)
This thesis proposed the biodiesel production from cooking palm oil by using rotating pack bed reactor (RPB). The experiments were divided into 3 parts i) preparation of CaO/γ-Al2O3 catalyst and catalytic activity for the transesterification in a conventional mechanical stirrer reactor (MS). ii) study of CaO/γ-Al2O3 heterogeneous catalysts using RPB iii) study of NaOH homogeneous catalysts using RPB by packing inert packing bed. The Response surface methodology (RSM) based on the Central composite design (CCD) was used to reduce the number of experiments. The optimum condition for CaO /γ-Al2O3 catalyst preparation was at calcination temperature of 500ºC and 24%CaO/γ- Al2O3. …
Preparation Of Ba0.5sr0.5(Co0.8fe0.2)1-Xtaxo3-Δ Perovskite Anode For Solid Oxide Electrolysis Cell And Comparison Of Electrochemical Performance And Durability With The Basic Anodes, Patthiya Prasopchokkul
Preparation Of Ba0.5sr0.5(Co0.8fe0.2)1-Xtaxo3-Δ Perovskite Anode For Solid Oxide Electrolysis Cell And Comparison Of Electrochemical Performance And Durability With The Basic Anodes, Patthiya Prasopchokkul
Chulalongkorn University Theses and Dissertations (Chula ETD)
Among perovskite anodes in solid oxide electrolysis cell (SOEC), Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF) has gained much attention due to its relatively high performance. However, the BSCF still suffers from chemical instability. In this study, partial substituting higher valance Ta5+ (5, 10, 15 and 20 mol%) at the B-site (Co2+/Fe3+) of BSCF was investigated to improve its structural stability. The Ba0.5Sr0.5(Co0.8Fe0.2)1-xTaxO3-δ (BSCFTax, 0 ≤ x ≤ 0.20) were synthesized by citrate-EDTA complexing method. The BSCF and BSCFTa0.05 exhibited the single phase perovskite while segregation of Ta2O5 and Ta3N5 were observed in other samples. The symmetrical half-cell having the yttria stabilized zirconia (YSZ) as …
Study Effect Of Catalyst Shape On The Ethylbenzene Dehydrogenation In Fixed Bed Reactor By Using Various Mathematical Models, Pawinee Maithong
Study Effect Of Catalyst Shape On The Ethylbenzene Dehydrogenation In Fixed Bed Reactor By Using Various Mathematical Models, Pawinee Maithong
Chulalongkorn University Theses and Dissertations (Chula ETD)
Nowadays, the chemicals are mostly manufactured by catalytic reactions in fixed bed reactor. Catalyst shape affects to reactor performance and the effect is studied by mathematic models which are varied forms to more realistic. Therefore, the objective of research is to study the effect of catalyst shape on the behavior of reactor for ethylbenzene dehydrogenation to styrene in gas phase by varied form. The simplest model, pseudohomogeneous model (model1), predicts 36.52% ethylbenzene conversion. The more complex model, heterogeneous model accounting for internal mass transfer (model2), predicts 34.49% conversion that equals to the model accounting for internal mass and heat transfer(model3). …
Effect Of Titania Phase Composition In Wo3/Tio2 Catalysts On Catalytic Properties In Dehydration Of Ethanol To Diethyl Ether, Phatthraporn Termvoratham
Effect Of Titania Phase Composition In Wo3/Tio2 Catalysts On Catalytic Properties In Dehydration Of Ethanol To Diethyl Ether, Phatthraporn Termvoratham
Chulalongkorn University Theses and Dissertations (Chula ETD)
At the present, several agricultural products can be used as raw materials for bio-ethanol production and consequently converted it into many valuable substances such as ethylene and diethyl ether. This can undergo via WO3/TiO2 catalyst in which the anatase phase of titania usually has a better activity on ethanol dehydration to diethyl ether and ethylene than rutile phase. However, pure anatase phase of titania perhaps does not give the best of catalytic properties. So, this study investigates on the effects of tungsten on titania-supported catalysts with different phase composition of titania consisting of anatase and rutile phase with various proportion …
Ni Catalyst Supported On Open-Cell Ceramic Foam For Glycerol Steam Reforming, Phichamon Sookjitsumran
Ni Catalyst Supported On Open-Cell Ceramic Foam For Glycerol Steam Reforming, Phichamon Sookjitsumran
Chulalongkorn University Theses and Dissertations (Chula ETD)
This work studied of nickel catalyst on open-cell ceramic foam for hydrogen production from glycerol steam reforming. Effect of different foam materials (alumina and zirconia), different pore density (PPI) at 10, 20 and 30 PPI and different feed flow rate (0.04, 0.2 and 0.4 ml/min) on physical and chemical properties and catalyst performance in fixed-bed reactor (16 mm diameter, 500 mm length and 20 mm catalyst bed) were investigated. Fresh and used catalysts were characterized by various techniques including XRD, SEM-EDX, H2-TPR, ICP, N2 adsorption-desorption, TPO and TGA. Catalyst performance was observed in glycerol steam reforming in condition as follows; …
Solid Acid Catalyst Prepared Via One Step Hydrothermal Carbonization For Production Of 5-Hydroxymethylfurfural In Biphasic System, Phornwimol Siabbamrung
Solid Acid Catalyst Prepared Via One Step Hydrothermal Carbonization For Production Of 5-Hydroxymethylfurfural In Biphasic System, Phornwimol Siabbamrung
Chulalongkorn University Theses and Dissertations (Chula ETD)
As one of the most important precursor for various high-value chemicals, 5-hydroxymethylfurfural (HMF) is a biomass-derived compound that has gained increasing chemical research and industrial interests in recent years. In this study, production of HMF from direct dehydration of glucose was investigated with various types of catalysts prepared by a modified one-step HTC method. Two type of acids were employed for the functionalization of the catalyst, namely, 2-Hydroxyethylsulfonic acid (C2H6O4S) and Hydrochloric acid (HCl), making C-SO3H and C-HCl catalysts. Moreover, both of them were synthesized by adding acrylic acid to the C-SO3H-A and C-HCl-A catalysts. Their physicochemical characteristics and catalytic …
Efficiency On Extending The Shelf-Life Of Ripened Mango (Cv. Golden Nam Dokmai) Using Bioplastic Bags From Laboratory Scale And Industrial Scale, Tanudkid Butweangphant
Efficiency On Extending The Shelf-Life Of Ripened Mango (Cv. Golden Nam Dokmai) Using Bioplastic Bags From Laboratory Scale And Industrial Scale, Tanudkid Butweangphant
Chulalongkorn University Theses and Dissertations (Chula ETD)
Efficiency in extending the shelf-life of ripened Golden Nam Dokmai by using bioplastic bags from laboratory scale and industrial scale production was tested. Polylactic acid (PLA) pellets and various fillers were mixed via twin screw extruder before being blown into film via extruder attached to blown film die in laboratory scale and industrial scale equipment. Oxygen and water vapor permeability of both kinds of bioplastic bags were evaluated for used as modified atmosphere packaging, for extend shelf-life of ripened mango. The oxygen permeability of films was 1,635.59±87.75 and 1,250.64±96.42 cc/m2-day and their water vapor permeability was 165.26±5.74 and 240.45±57.76 g/m2-day …
Modeling Production Of Aromatic From N-Paraffins With Chemical Equilibria, Thidarat Detsut
Modeling Production Of Aromatic From N-Paraffins With Chemical Equilibria, Thidarat Detsut
Chulalongkorn University Theses and Dissertations (Chula ETD)
Chemical Equilibrium models were constructed for modeling and developing the aromatic production model from the normal paraffin at the equilibrium of the reaction with catalysts, i.e. ZSM-5(80) and Mo2C. The models were verified under operating temperatures of 450-500 ° C under atmospheric pressure at 1 atm. By examining the accuracy by comparing the data calculated from each model with the value obtained from the corresponding experiments at the condition that the reaction is balanced. The suitable equilibrium model depends on the type of catalyst used in the system. The accuracy of all equilibrium models could be improved by specifying the …
The Synthesis Of Hyperbranched Epoxy Resin For Improvement Of Thermal, Mechanical, And Adhesion Properties Of Epoxy Adhesive, Tossapol Boonlert-Uthai
The Synthesis Of Hyperbranched Epoxy Resin For Improvement Of Thermal, Mechanical, And Adhesion Properties Of Epoxy Adhesive, Tossapol Boonlert-Uthai
Chulalongkorn University Theses and Dissertations (Chula ETD)
This research aimed to synthesize and characterize the hyperbranched epoxy resin synthesized by A2 + B4 polycondensation reaction consisting of bisphenol A (BPA) and polyethylene glycol (PEG) as A2 monomers, pentaerythritol as B4 branching monomer, and epoxide end group. There were varying PEG contents of 0, 5, 10, and 15 wt% of BPA. It was found that the synthesized resins could be confirmed by identifying the important chemical bond and possible structure by Fourier-transform infrared spectroscopy (FTIR) and H- and 13C-nuclear magnetic resonance (H-NMR and 13C-NMR) techniques. The 13C-NMR technique could identify the degree of branching (DB) of the synthesized …
Separation Of Trace Palladium Chloro Complexes From Wastewater Of Electroless Plating Process Via Hollow Fiber Supported Liquid Membrane, Vanee Mohdee
Chulalongkorn University Theses and Dissertations (Chula ETD)
The separation of palladium (Pd (II)) from wastewater containing copper (Cu (II)) and nickel (Ni (II)) is investigated via hollow fiber supported liquid membrane (HFSLM). The viability to separate Pd (II) was established by controlling the influence of operating conditions viz. aqueous feed acidity, carrier concentration, types of stripping solution as well as flows rate of feed and stripping solutions. A complete separation of Pd (II) acheiving >99% extraction and 87.09% recovery was demonstrated under optimum conditions of 6%(v/v) Aliquat 336, pH 2 as aqueous feed acidity, 0.5 M thiourea mixed with 0.1 M HCl as a strippant and 100 …
Non-Faradaic Electrochemical Modification Of Catalytic Activity (Nemca) Of Propane Oxidation On Pt/Ysz Thin Film Cell, Wanchana Lelalertsupakul
Non-Faradaic Electrochemical Modification Of Catalytic Activity (Nemca) Of Propane Oxidation On Pt/Ysz Thin Film Cell, Wanchana Lelalertsupakul
Chulalongkorn University Theses and Dissertations (Chula ETD)
In this work, non-Faradaic Electrochemical Modification of Catalytic Activity (NEMCA) of propane oxidation over Pt/yttria-stabilized zirconia (YSZ) thin films on alumina substrates has been studied. YSZ thin films were initially prepared by slurry dip coating and calcined at a relatively lower temperature of 800 oC. Propane oxidation at temperatures in a range of 300-500 oC clearly exhibited NEMCA. The maximum rate enhancement ratio was close to 3 at an applied potential of 1.0 V and a reaction temperature of 400 oC. The maximum faradaic efficiency was higher than 10,000 at an applied potential of 0.2 V and 300oC. However, NEMCA …
Synthesis Of Ziegler-Natta Catalysts Containing Sicl4/Teos/Ticl4/Mgcl2 For Ethylene/1-Hexene Copolymerization, Wasinee Ousirisombat
Synthesis Of Ziegler-Natta Catalysts Containing Sicl4/Teos/Ticl4/Mgcl2 For Ethylene/1-Hexene Copolymerization, Wasinee Ousirisombat
Chulalongkorn University Theses and Dissertations (Chula ETD)
Polyethylene (PE) is still worldwide manufacturing, and its most productivity is in Asia. The main categories of PE including high density polyethylene (HDPE), low density polyethylene (LDPE) and linear low density polyethylene (LLDPE). Ziegler-Natta catalyst is catalyst that used for α-olefins polymerization and it is widely used in industry because it has good activity with low operating cost. This research studies on synthesized SiCl4/TEOS/TiCl4/MgCl2 Ziegler-Natta catalyst in ethylene/1-hexene copolymerization with added silicon compounds,including tetraethylorthosilicate (TEOS) and SiCl4, used as additive in catalyst by varying 1-hexene comonomer at 0%, 3% and 5%. This research is separated into 2 parts, the first …
Performance Analysis Of The Proton-Conducting Solid Oxide Electrolysis Cell Coupling With Dry Methane Reforming, Wissawa Chalee
Performance Analysis Of The Proton-Conducting Solid Oxide Electrolysis Cell Coupling With Dry Methane Reforming, Wissawa Chalee
Chulalongkorn University Theses and Dissertations (Chula ETD)
The proton-conducting solid oxide electrolysis cell (H-SOEC) is a clean technology for syngas production from H2O and CO2 through electrochemical and chemical reactions. However, it gives low CO2 conversion and produces syngas product with high H2O content. Therefore, the H-SOEC coupling with a dry methane reforming process (H-SOEC/DMR) is proposed to improve its performance. The process flowsheet of the H-SOEC/DMR is developed by using Aspen Plus and used to evaluate the performance of H-SOEC/DMR. The performance analysis of the H-SOEC/DMR shows that under the temperature range of 1073-1273 K, the %CO2 and %CH4 conversions of higher than 90% and 80% …
Development Of Nickel Alloy Hydrogen Electrodes For Solid Oxide Electrolysis Cell, Aritat Wongmaek
Development Of Nickel Alloy Hydrogen Electrodes For Solid Oxide Electrolysis Cell, Aritat Wongmaek
Chulalongkorn University Theses and Dissertations (Chula ETD)
The conventional nickel-yttrium stabilized zirconia (Ni-YSZ) cathode in solid oxide electrolysis cell (SOEC) suffers from oxidation after exposed to steam during electrolysis for hydrogen production. The Ni-chromium (Cr)-iron (Fe) alloys with various compositions are introduced to improve cathode oxidation resistance. This study aims to study the effect of alloy contents and determine suitable fabrication method for SOEC cathode. The alloy containing cathode should satisfy both high electrochemical performance and low degradation rate. The content of Fe and Cr are varied in the range of 0-20%wt when the weight ratio of metal to YSZ is maintained constantly at 60:40. The SOEC …
Wind Load Analysis Of A High-Rise Building By Computational Fluid Dynamics, Canh Thiet Phung
Wind Load Analysis Of A High-Rise Building By Computational Fluid Dynamics, Canh Thiet Phung
Chulalongkorn University Theses and Dissertations (Chula ETD)
As new buildings become taller due to limited land area, often irregular in shapes for esthetics and some design constraints, wind load formula provided in design codes/standards cannot be applied because of the limitations. Wind tunnel test (WTT) is thus the suggested approach to obtain appropriate wind load for the design of such buildings. However, WTT is costly and time-consuming as it often requires much preparation of the small-scale model of the target building, instrumentation, and numerous realistic blocks of surrounding buildings (SBs). In this study, the CFD's accuracy will be evaluated by comparing its results to WTT by a …
Shear Wave Velocity Measurement Of Bangkok Clay Under Triaxial Testing With Various Stress Paths, Sirichai Pethrung
Shear Wave Velocity Measurement Of Bangkok Clay Under Triaxial Testing With Various Stress Paths, Sirichai Pethrung
Chulalongkorn University Theses and Dissertations (Chula ETD)
Orientation paths of shear wave velocity for clayey soil subjected to multiple triaxial loading tests are dependent on complicated factors direction of stresses, void ratio, coefficient of earth pressure at rest, etc. However, most suggested the mean effective stress could provide a suitable correlation as well. In the present study, an identify the shear wave velocity under triaxial undrained small loading-unloading test , monotonic triaxial drained compression test , triaxial drained loading-unloading test , triaxial stress control test , drained triaxial extension , and undrained triaxial extension measured using the bender elements was presented. These results are indicated that the …
Seismic Enhancement Of Reinforced Concrete Columns With Lap Splices Using External Steel Collars, Pochara Kruavit
Seismic Enhancement Of Reinforced Concrete Columns With Lap Splices Using External Steel Collars, Pochara Kruavit
Chulalongkorn University Theses and Dissertations (Chula ETD)
This research investigated the behavior of reinforced concrete (RC) columns with lap splices and mechanical splices. The study conducted the full-scale test and predicted a lateral load capacity using the proposed numerical model. The test configuration was a cantilever column subjected to a cyclic lateral loading and a constant gravity load. The tested specimens consisted of the RC column without lap splices, RC columns with spliced reinforcement including lap splices and mechanical splices, and RC column with lap splices strengthened by external steel collars. The experimental result indicated that the lateral load capacity of the RC column with mechanical splices …
Modified Response Spectrum Analysis For Computing Seismic Demands Of Multi-Tower Building Sharing A Common Podium, Tarek Youssef
Modified Response Spectrum Analysis For Computing Seismic Demands Of Multi-Tower Building Sharing A Common Podium, Tarek Youssef
Chulalongkorn University Theses and Dissertations (Chula ETD)
To design irregular tall buildings, performance-based design (PBD) approach, which requires nonlinear response history analysis (NLRHA), is the most accurate method. However, PBD approach is not always used in the current design practice because of its complexity, and as allowed in ASCE 7-16, design engineer can use code-based approach such as response spectrum analysis (RSA) procedure. This paper aims to investigate the accuracy of RSA procedure when applied to irregular tall buildings, and in particular for multi-tower buildings sharing a common podium. Also, a modified response spectrum analysis (MRSA) procedure previously proposed for computing shear demand in regular tall buildings, …
A Study On Intermediate Debonding For Steel Beams Strengthened With Fiber Reinforced Polymer Plates, Tosporn Prasertsri
A Study On Intermediate Debonding For Steel Beams Strengthened With Fiber Reinforced Polymer Plates, Tosporn Prasertsri
Chulalongkorn University Theses and Dissertations (Chula ETD)
There are limited previous works focusing on the occurrence of intermediate debonding in steel beams strengthened with fiber reinforced polymer (FRP) plates. Tested beams in the past experiments invoked an intermediate debonding by creating notch in steel beams. An anchorage system at FRP termination points was installed on some tested beams in literature. This research uses an initial bond defect to induce an intermediate debonding at the FRP-steel interface. The bond behavior of FRP-steel interface was investigated through the FRP-steel joints under the single lap shear testing. A four-point bending test was conducted to examine the flexural properties of FRP-strengthened …
An Application Of Line Of Balance And Building Information Modeling For Optimal Resource And Schedule: A Case Study Of An Elevated Highway Construction, Thanakon Uthai
Chulalongkorn University Theses and Dissertations (Chula ETD)
Project scheduling is an essential tool to support construction operations completing the project under limited time and cost. The linear infrastructure project such as elevated highway construction involves a large scale of working area and complexity of management. Recently, schedules are planned manually based on planners’ experience and intuition which may consume time and lead to human-errors. Moreover, the presentations of schedule by using the existing methods dose not cover the overview of projects in various aspects. The objective of this research is to establish an application of Line of Balance (LOB) and Building Information Modeling (BIM) for optimal resource …
Fundamental Solutions Of Multi-Layer Elastic Media With Couple Stress Theory, Wipavee Wongviboonsin
Fundamental Solutions Of Multi-Layer Elastic Media With Couple Stress Theory, Wipavee Wongviboonsin
Chulalongkorn University Theses and Dissertations (Chula ETD)
This thesis presents fundamental solutions of a two-dimensional, elastic, multi-layered medium under surface loadings by taking the influence of material micro-structure into account. An underlying mathematical model for simulating such small-scale influence is established within the continuum-based framework via the well-known couple stress theory. For each material layer, the generalized Navier’s equation governing the displacement field is established and the method of Fourier integral transform is applied to derive its general solution in a transformed space. A set of boundary conditions and the continuity of fields along the material interfaces are enforced to obtain a system of linear algebraic equations …
The Performance Of Automatic Adaptive Edge-Based Smoothed Finite Element Method In Engineering Mechanics Applications, Vu Hoang Le
The Performance Of Automatic Adaptive Edge-Based Smoothed Finite Element Method In Engineering Mechanics Applications, Vu Hoang Le
Chulalongkorn University Theses and Dissertations (Chula ETD)
The thesis investigates the performance of an edge-based smoothed finite element method (ES-FEM) combined with an automatic mesh refinement (AMR) algorithm to provide the solutions of in-plane elastic engineering mechanics applications. The ES-FEM adopts a strain smoothing technique over the edges adjoining the two adjacent triangular-shape meshes, whilst a layer of singular yet compatible five-node elements in addition to standard three-node ES-FEs can be employed to overcome the problems associated with stress singularity. The proposed framework enables the effective model construction of realistic engineering structures with complex geometry at modest computational resources. The AMR algorithm adopts the newest node bisection …
Strength Analysis Of Concrete-Encased Cellular Steel Columns, Worakarn Anuntasena
Strength Analysis Of Concrete-Encased Cellular Steel Columns, Worakarn Anuntasena
Chulalongkorn University Theses and Dissertations (Chula ETD)
This research investigates the compression behavior of bare cellular steel columns and concrete-encased cellular steel (CECS) columns subjected to concentric and eccentric loadings. First, the experimental study of the cellular steel and CECS columns was conducted in the laboratory. For the cellular steel columns subjected to concentric loading, the failure mode of the bare cellular steel columns was local buckling at both web and flanges at the hole section. All cellular steel columns exhibited yielding and hardening behavior. The cellular columns had the average yield loads less than the parent column by 15 %. For the CECS and CES columns …
Thai Spelling Correction And Word Normalization On Social Text Using A Two-Stage Pipeline With Neural Contextual Attention, Anuruth Lertpiya
Thai Spelling Correction And Word Normalization On Social Text Using A Two-Stage Pipeline With Neural Contextual Attention, Anuruth Lertpiya
Chulalongkorn University Theses and Dissertations (Chula ETD)
Text correction systems (e.g., spell checkers) have been used to improve the quality of computerized text by detecting and correcting errors. However, the task of performing spelling correction and word normalization (text correction) for Thai social media text has remained largely unexplored. In this thesis, we investigated how current text correction systems perform on correcting errors and word variances in Thai social texts and propose a method designed for this task. We have found that currently available Thai text correction systems are insufficiently robust for correcting spelling errors and word variances, while the text correctors designed for English grammatical error …