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Articles 1741 - 1770 of 1876
Full-Text Articles in Physical Sciences and Mathematics
Extreme Anomalous Clustering Algorithm, Panuruk Lisuwan
Extreme Anomalous Clustering Algorithm, Panuruk Lisuwan
Chulalongkorn University Theses and Dissertations (Chula ETD)
A clustering algorithm is a process of dividing data points into disjoint clusters according to the similarity of the data points. Many researchers have presented and developed the clustering algorithms to be suitable for the different characteristics of the datasets. Therefore, the concept of the identifying anomaly data points in the dataset was adopted in this thesis to explain the similarity of the data points. The main idea is to calculate the minimum distance between data points to identify the extreme anomalous score of all data points. In this thesis, a novel clustering algorithm is proposed called the Extreme Anomalous …
Measurement For Disordered Proteins Affecting Scale-Free Network, Satanat Kitsiranuwat
Measurement For Disordered Proteins Affecting Scale-Free Network, Satanat Kitsiranuwat
Chulalongkorn University Theses and Dissertations (Chula ETD)
No abstract provided.
Clifford Algebra-Valued Segal-Bargmann Transform, Sorawit Eaknipitsari
Clifford Algebra-Valued Segal-Bargmann Transform, Sorawit Eaknipitsari
Chulalongkorn University Theses and Dissertations (Chula ETD)
A classical Segal-Bargmann transform maps square-integrable functions on R to holomorphic square-integrable functions on C with respect to some Gaussian measure. In this work, we extend the classical Segal-Bargmann transform to functions taking values in a Clifford algebra. We establish that in this setting, the generalized Segal-Bargmann transform is a unitary isomorphism mapping Clifford algebra-valued square-integrable functions on Rⁿ with respect to some Gaussian measure to monogenic square-integrable functions on Rⁿ⁺¹ with respect to another Gaussian measure. We also discuss about the differential and multiplication operators in the monogenic functions space as well as certain properties of their domains.
Complete Convergence For Sequences Of Coordinatewise Widely Orthant Dependent Random Vectors In Hilbert Spaces, Teerayut Phutthanukool
Complete Convergence For Sequences Of Coordinatewise Widely Orthant Dependent Random Vectors In Hilbert Spaces, Teerayut Phutthanukool
Chulalongkorn University Theses and Dissertations (Chula ETD)
In this thesis, we introduce a new dependence concept for a sequence of random vectors taking values in real separable Hilbert spaces called coordinate-wise widely orthant dependence and extend the Baum-Katz Theorem to obtain complete convergence and complete moment convergence for a sequence of co-ordinatewise widely orthant dependent random vectors taking values in Hilbert spaces.
Strategies For Playing Closing Octagons Game In Some Situations, Thitiphut Leelathanakit
Strategies For Playing Closing Octagons Game In Some Situations, Thitiphut Leelathanakit
Chulalongkorn University Theses and Dissertations (Chula ETD)
Closing Octagons game is a combinatorial game for two players that we modify from Dots and Boxes game and Dots and Hexagons game. The game starts with an m × n array of octagons such that every two adjacent octagons has one common side and 0 points for both players. Two players alternately turn by the following rules. (i) A player moves by coloring one side of an octagon. (ii) A player who colors the eighth side of k octagons earns k points and takes one more move. The game ends when every side of octagons has been colored and …
Patterns Of Lines Intersecting On Plane, Wongtawan Chamnan
Patterns Of Lines Intersecting On Plane, Wongtawan Chamnan
Chulalongkorn University Theses and Dissertations (Chula ETD)
In this work, we are interested in patterns of n lines on the plane such that lines produce M intersecting points. One famous related problem is called Fourier's 17 line problem. Although there are only a few known necessary conditions for realization, some arrangements may not even drawable. Consequently, we try to find more necessary conditions for this problem that can lead to possible arrangements and realize the arrangements. We provide a systematic algorithm to draw the possible arrangements. We establish lemmas for the direct drawing and find some certain cases of arrangements which are drawable. We also provide another …
Metal-Salen Derivatives For Electro-Reduction Of Carbon Dioxide, Kantima Chitchak
Metal-Salen Derivatives For Electro-Reduction Of Carbon Dioxide, Kantima Chitchak
Chulalongkorn University Theses and Dissertations (Chula ETD)
Copper(II) salen, salophen-based ligands, and their corresponding copper complexes were prepared and utilized for the electrocatalytic reduction of carbon dioxide. Controlled-potential electrolysis of copper(II) salen electrocatalyst with carbon dioxide in non-aqueous solution was investigated to obtain the optimized electrolysis condition including the applied potential and proton donor quantity. With the applied potential of –2.10 V, carbon monoxide (3.50-16.30%) was obtained as the only product in gas phase. Methane was additionally found with the addition of proton donor and its maximum percentage (0.39 ± 0.00%) were obtained from the electrolysis with 25.00 mM proton donor and 2.00 mM copper(II) salen. Moreover, …
Synthesis Of Ni-Tin Incorporated Porous Silica Catalysts For Dry Reforming Of Methane, Maslin Chotirach
Synthesis Of Ni-Tin Incorporated Porous Silica Catalysts For Dry Reforming Of Methane, Maslin Chotirach
Chulalongkorn University Theses and Dissertations (Chula ETD)
A new titanium nitride (TiN) promoted nickel catalyst was synthesized and tested as an alternative catalyst in the dry reforming of methane (DRM). The series of this catalyst with various Ni and TiN contents was prepared in two steps, direct synthesis of SBA-15 in the presence of TiN, followed by the impregnation of Ni. The influence of TiN promoted Ni-based catalyst on dry reforming reaction was investigated at the temperature of 700ºC and atmospheric pressure for a duration of 4 h, using feed ratio of CH4/CO2 = 1. The promising catalysts, that gave highest CO2 and CH4 conversions as well …
Electrochemical Properties Of Lnsr3-Xcaxfe3-Ybyo10 (Ln = La, Pr And Sm; X = 0-1.0; B = Co, Ni And Cu; Y = 0-1.5) For Intermediate Temperature Solid Oxide Fuel Cells, Nicharee Wongsawatgul
Electrochemical Properties Of Lnsr3-Xcaxfe3-Ybyo10 (Ln = La, Pr And Sm; X = 0-1.0; B = Co, Ni And Cu; Y = 0-1.5) For Intermediate Temperature Solid Oxide Fuel Cells, Nicharee Wongsawatgul
Chulalongkorn University Theses and Dissertations (Chula ETD)
To enhance the electrochemical performance of cathode material for intermediate temperature solid oxide fuel cell (IT-SOFC) the Ruddlesden-Popper (RP) phases of LnSr3-xCaxFe3-yByO10 (Ln = La, Pr and Sm; x = 0-1.0; B = Ni, Co, and Cu; y = 0-1.5) was investigated and prepared by citric nitrate combustion method. Firstly, various Ca concentrations were added to the LaSr3-xCaxFe3O10-δ structure and it was found that the materials contained low Ca concentration provided the lower area specific resistance (ASR) and better electrochemical cell performance due to the enhance in conductivity and reduction of TEC. Secondly, the effect of Pr and Sm replacement …
Electrochemical Sensors For Human Papillomavirus Dna, C-Reactive Protein And Food Colorants Detections, Sakda Jampasa
Electrochemical Sensors For Human Papillomavirus Dna, C-Reactive Protein And Food Colorants Detections, Sakda Jampasa
Chulalongkorn University Theses and Dissertations (Chula ETD)
In this dissertation, electrochemical sensors for determination of medical biomolecular markers and food colorants were developed. The research can be divided into two parts. In the first part, electrochemical sensors for determination of clinically important biomarkers were studied. There was two subprojects based on the target markers. The first subproject was the development of electrochemical sensor for the simultaneous detection of high-risk human papillomaviruses (HPV) DNA type 16 and 18 as biomarkers for cervical cancer. In this work, a highly specific pyrrolidinyl peptide nucleic acid was employed as DNA capture probe for both target DNAs. A second PNA probe labeled …
Fecu/Sio2 Catalysts Prepared By Autocombustion Method For Fischer-Tropsch Synthesis, Suthasinee Pengnarapat
Fecu/Sio2 Catalysts Prepared By Autocombustion Method For Fischer-Tropsch Synthesis, Suthasinee Pengnarapat
Chulalongkorn University Theses and Dissertations (Chula ETD)
The purpose of this study was to prepare iron-based catalysts supported on silica by autocombustion method for directly using for Fischer-Tropsch synthesis (FTS) without a reduction step. The effect of different citric acid (CA):iron nitrate (N) molar ratios (CA:N), acid types and SiO2 supports on the FTS performance of catalysts were investigated. The CA:N had an important influence on the formation of iron active phases (FexC) and FTS activity. Increasing the CA:N molar ratios up to 0.1 increased CO conversion of catalyst to 86.5%, which was then decreased markedly at higher CA:N molar ratios. An excess of CA resulted in …
Microencapsulation Of Eugenol In Polyelectrolyte Complexes Of Chitosan And Alginate, Chamaiporn Supachettapun
Microencapsulation Of Eugenol In Polyelectrolyte Complexes Of Chitosan And Alginate, Chamaiporn Supachettapun
Chulalongkorn University Theses and Dissertations (Chula ETD)
Eugenol is widely used in several applications such as food activity packaging to prolong shelf life of fruits and vegetables because of its antimicrobial activity. However, eugenol is easy to decompose, leading to reduce its activity. In this work, we prepared eugenol loaded alginate-chitosan microparticles in order to solve this problem and controlled release essential oil using ionic gelation technique. The effect of concentration of eugenol (0.1-0.5 g), calcium chloride (0.5 – 8 %W/V) and surfactant (2-10% W/V) was investigated. The results showed that the optimum condition was eugenol 0.1 g, calcium chloride 2% W/V and surfactant 4% W/V. The …
Functional Surfactants In Lubricant For Microelectronic Industry, Chuenkamol Khongphow
Functional Surfactants In Lubricant For Microelectronic Industry, Chuenkamol Khongphow
Chulalongkorn University Theses and Dissertations (Chula ETD)
The functional surfactants, as the additional additives in the standard glycol-based lubricant were studied and optimized to reduce and protect the surface of the magnetic read/write head from deposited contaminants during the lapping processes. The scanning electron microscopy (SEM) and energy-dispersive x-ray spectroscopy (EDS) results identified that the black contamination was bismuth (Bi) particles, came out from lapping plate during the lapping process due to wear. Selected surfactants exhibited the results in reduce and prevent the deposition of contaminants by forming the micelle beyond their critical micelle concentration (CMC) values. We found that both polyethoxylate alcohol (PEAL) and quaternary amines …
Mixed Metal Oxide Catalysts Derived From Natural Sources For Production Of Fatty Acid Methyl Esters, Wayu Jindapon
Mixed Metal Oxide Catalysts Derived From Natural Sources For Production Of Fatty Acid Methyl Esters, Wayu Jindapon
Chulalongkorn University Theses and Dissertations (Chula ETD)
The objectives of this research are to study active sites of Ca-based catalysts derived from calcite (CaCO3) and dolomite (CaMg(CO3)2), and to clarify catalytic effect of MgO in the calcined dolomite as catalyst in transesterification of palm oil with methanol. Firstly, the effects of calcination temperature on evolution of MgO in dolomite and its catalytic activity were studied. The MgO containing in the calcined dolomite was not active, while the main active site was CaO. However, Ca and Mg mixed oxides obtained from calcined dolomite had higher activity than that prepared by physical mixing in which calcite and magnesite (MgCO3) …
Synthesis Of Puerarin-Gold Nanoparticles For Transdermal Delivery, Kwanruen Chanpeng
Synthesis Of Puerarin-Gold Nanoparticles For Transdermal Delivery, Kwanruen Chanpeng
Chulalongkorn University Theses and Dissertations (Chula ETD)
Puerarin (Pur) is herbal medicine that its inflammatory response but low solubility to reduce activity. Thus, the aim of this study was to synthesize q188-kappa-carrageenan@Pur@gold nanoparticles (q188-κ-c@Pur@AuNPs) for enhancing solubility and transdermal delivery. The κ-c was synthesized by quaternization of κ-c with 25% (v/v) q188, and the q188-κ-c @AuNPs was prepared by reducing HAuCl4 into AuNPs by using 25% (v/v) q188-κ-c as reducing and stabilizing agents. The highest degree of quaternization (%DQ) at 21.12% was found q188 addition, which was calculated from 1H NMR. The solubility of the q188-κ-c derivatives was 43.7±0.01%, which higher than κ-c. The size of synthesized …
Effect Of Corrosion Inhibitors In Lubricant For Electronic Industry, Natclitta Maipul
Effect Of Corrosion Inhibitors In Lubricant For Electronic Industry, Natclitta Maipul
Chulalongkorn University Theses and Dissertations (Chula ETD)
The selected functional polymers and fatty esters of poly)1-butene pyrrolidone) (PP) and propylene glycol monostearate (PG) were investigated and applied to use as the corrosion inhibitors for protecting material removal during read/write head lapping processes in hard disk drive (HDD) production. Potentiodynamic polarization measurement was used to study their corrosion behaviors against antiferromagnetic materials (IrMn) which are the most sensitive materials in the head structure. Corrosion rate of PP- and PG-modified lubricants were 0.086 and 0.084 Å/min, respectively, while standard lubricant was 0.111 Å/min. Moreover, the leaching out of metallic atoms was investigated by using inductively couple plasma mass spectroscopy …
Hydrodeoxygenation Of Oleic Acid On Unsupported Co-Mo And Ni-Mo Sulfide Catalysts, Paphawee Sanggam
Hydrodeoxygenation Of Oleic Acid On Unsupported Co-Mo And Ni-Mo Sulfide Catalysts, Paphawee Sanggam
Chulalongkorn University Theses and Dissertations (Chula ETD)
In this research, hydrodeoxygenation (HDO) of oleic acid (model compound of palm oil) over unsupported Co-Mo and Ni-Mo sulfide catalysts was carried out in Parr reactor to produce bio-hydrogenated diesel (BHD). The effects of reaction parameters: temperature, hydrogen pressure and the mole ratio of catalysts (Ni/(Ni+Mo) or Co/(Co+Mo)) on the conversion and product yields (mainly n-C17 and n-C18 hydrocarbons) were investigated to find the optimal conditions. The results showed that high pressure favored a HDO pathway, while high temperature strongly affected to decarboxylation and decarbonylation pathways. At optimal condition as temperature of 280oC, reaction times of 6 h and hydrogen …
Photooxidation Of Organosulfur Compounds Catalyzed By Iodo-Bodipy Derivatives Under Visible Light Irradiation, Piyamaporn Tangkasemsamran
Photooxidation Of Organosulfur Compounds Catalyzed By Iodo-Bodipy Derivatives Under Visible Light Irradiation, Piyamaporn Tangkasemsamran
Chulalongkorn University Theses and Dissertations (Chula ETD)
In this work, iodo-BODIPY derivatives, I-GB, 3I-GB, I-RB, were synthesized and used as photocatalysts for oxidation of organosulfurs such as thiols and thioethers into the corresponding disulfides and sulfoxides, respectively, as well as compared with benchmark photocatalyst, rose bengal. All BODIPY derivatives were successfully synthesized in good yields (36-80%) via condensation reaction between 4-iodobenzaldehyde and corresponding pyrroles, followed by oxidation with DDQ and complexation with BF3.OEt2. Among all synthesized BODIPYs, 3I-GB and 3I-RB showed relatively low quantum yield (0.053-0.054) with high singlet oxygen generation efficiency under green LED suggesting that both of them could serve as good photocatalysts for sulfur …
Preparation Of Porous Carbon From Popped Rice Via Impregnated Water Coupled With Freeze-Drying Process, Purichaya Nisawa-Anutaraphan
Preparation Of Porous Carbon From Popped Rice Via Impregnated Water Coupled With Freeze-Drying Process, Purichaya Nisawa-Anutaraphan
Chulalongkorn University Theses and Dissertations (Chula ETD)
Activated carbon is an interesting material due to its high surface area derived from the highly porous structure. This material is suitable for using as a good adsorbent in various applications such as wastewater treatment, gas absorption and medicine. Production of activated carbon typically consists of two steps which are carbonization and activation. Agricultural wastes are used as carbon sources. This research focuses on the production of activated carbon from popped rice due to its appropriate chemical and structural characteristics, including highly starch content and connected-pore structure. Therefore, it should potentially be applied to produce activated carbon if the surface …
Development Of Hydrogen Embrittlement Resisted Pd-Cu Alloy Membrane, Ratchaneekorn Chukiatthai
Development Of Hydrogen Embrittlement Resisted Pd-Cu Alloy Membrane, Ratchaneekorn Chukiatthai
Chulalongkorn University Theses and Dissertations (Chula ETD)
The development of PdCu alloy membranes that can be used in hydrogen separation at low working temperature (<300°C) without hydrogen embrittlement problem is a very attractive topic for the petrochemical industry. Pd–Cu membranes have been prepared by electroless plating and electroplating method on stainless steel support. The compositions of the PdCu alloy membranes were related to both the metal deposition rates. The appropriate annealing temperature of Pd–Cu membranes was found at 500 °C in argon atmosphere for 24 hours to form a complete alloy material. After thermal annealing, the Cu atom was distributed in Pd alloy membrane. The surface morphology, compositions, and crystallinity of the PdCu alloy membranes were characterized using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). The best Pd contents in PdCu alloy membrane were about 84 and 75 %at. The hydrogen flux through the PdCu alloy membrane was measured at temperature 150 to 300 °C and differential pressure 0.5 to 2.5 bar for membrane stability. The hydrogen flux increased with increasing temperature and pressure. Adding Cu atoms in Pd can reduce strain in Pd lattice structure. Both PdCu alloy membrane can be operated at the lower temperature than a critical temperature of pure Pd membrane without hydrogen embrittlement.
Effect Of Metallocene Elastomers And Screw Speed On Polypropylene Compounds: Morphological And Physical Properties, Supot Ponhan
Effect Of Metallocene Elastomers And Screw Speed On Polypropylene Compounds: Morphological And Physical Properties, Supot Ponhan
Chulalongkorn University Theses and Dissertations (Chula ETD)
Polypropylene (PP) which is widely used in automotive industries can replace engineering plastics and metals due to its outstanding mechanical properties, moldability and reduced weight. Some automotive parts such as bumper require higher impact resistance, which is the limited property of PP. The aim of this work is to improve the impact properties with balancing the stiffness-impact properties and the physical properties by blending PP with metallocence elastomer (POE) using a twin screw extruder. The effects of PP and POE type and blending ratio on the PP/POE blends properties and morphology was studied. The results showed that the impact strength …
Water/Dust Repellent Coatings For Wood Surface From 3-Aminopropyltriethoxy Silane-Quat 188, Tanate Tubtimtong
Water/Dust Repellent Coatings For Wood Surface From 3-Aminopropyltriethoxy Silane-Quat 188, Tanate Tubtimtong
Chulalongkorn University Theses and Dissertations (Chula ETD)
Wetting and dust fouling on wood surface are big problems because of hydroxyl group and static charge on its surface. These problems could be minimized by surface modification which decreasing of hydroxyl groups and increasing of positive charges on wood surface. Many researches were reported about wetting issue but there were few studies directly involved to dust problem. In this research, 3-aminopropyltriethoxy silane (APTES) and 3-chloro-2-hydroxypropyltrimethyl ammonium chloride (Q188) were used to modify hydroxyl groups on wood surface to enhance wetting and dust repellency behavior of wood. The APTES-treated woods (AW) were prepared by immersion solution method and then were …
Molecular Dynamics Of Single-Wall Carbon Nanotube Wrapped With Polypropylene, Wanwisa Panman
Molecular Dynamics Of Single-Wall Carbon Nanotube Wrapped With Polypropylene, Wanwisa Panman
Chulalongkorn University Theses and Dissertations (Chula ETD)
Nowadays, the nanocomposite materials have been widely used in various applications due to their unique properties such as thermal and electrical properties. Polymer/carbon nanotube (CNT) nanocomposite is one the important nanocomposite materials that are manufactured for improving thermal conductivity and electrical properties of polymers. Unfortunately, polypropylene (PP)/CNT preparation is difficult because of CNT dispersion and aggregation. Accordingly, amylose (AMY) and chitosan (CS) are selected in the present study in order to demonstrate how AMY and CS could diminish such problems by non-covalent modification on outer surface of single-walled CNT using molecular dynamics (MD) simulations. The MD results reveal that AMY …
Gas Sensing Response Of Nickel Doped Calcium Copper Titanate Thin Films Synthesized By Sol-Gel Method, Arisara Boontum
Gas Sensing Response Of Nickel Doped Calcium Copper Titanate Thin Films Synthesized By Sol-Gel Method, Arisara Boontum
Chulalongkorn University Theses and Dissertations (Chula ETD)
Nickel-doped calcium copper titanate (Ni-doped CCTO) thin films prepared by nickel oxide (NiO) and nickel (II) acetate (C4H6NiO4) have been synthesized using sol-gel method. Four layers of Ni-doped CCTO films with various nickel dopant concentrations including undoped film were deposited by a spin coating technique on silicon and alumina substrates. Each film layer was annealed at a fixed annealing temperature of 800 °C. All samples were characterized by X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS) field emission scanning electron microscope (FESEM). Only the doped films prepared by NiO were analyzed by Raman spectroscopy. Moreover, the …
Plasma Characteristics And Ion Etching Performance In Hard Disk Drive Slider Fabrication Processes, Napakan Wongpanit
Plasma Characteristics And Ion Etching Performance In Hard Disk Drive Slider Fabrication Processes, Napakan Wongpanit
Chulalongkorn University Theses and Dissertations (Chula ETD)
A hard disk drive (HDD) is the permanent magnetic data storage and one of the most important components of computers, electronic devices and cloud data storage service facility. The data reading and writing are operated by the reader and writer parts of HDD head or slider. These reader and writer were made of multilayer thin ilms of different materials, forming a tunneling magnetoresistive (TMR) device. In HDD production, the ion beam etching (IBE) process was used in the preparation of surface patterns and cleaning in many fabrication steps. The Monte Carlo-based simulation package, SRIM was applied to calculate the etching …
Effects Of Gamma Ray Irradiation On Structural And Optical Properties Of Csi:Tl Crystals, Poramin Sintham
Effects Of Gamma Ray Irradiation On Structural And Optical Properties Of Csi:Tl Crystals, Poramin Sintham
Chulalongkorn University Theses and Dissertations (Chula ETD)
In this research work, effects of gamma ray irradiation on structural and optical properties of CsI doped with Tl (CsI:Tl), which is a scintillator material used for radiation detector applications, were investigated by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), UV-VIS spectroscopy and X-ray luminescence spectroscopy. The CsI:Tl crystals used in this study were grown by a modified homemade Bridgman-Stockbarger technique with CsI powder precursors purities of 99.999% and 99.9% and with the same amount of Tl in form powder of Tl. It is observed that CsI:Tl crystal grown with the 99.999% CsI powder precursor exhibited a colorless …
Effect Of Tio2 Morphology On Efficiency Of Ch3nh3pbi3 Perovskite Solar Cells, Ramon Songtanasit
Effect Of Tio2 Morphology On Efficiency Of Ch3nh3pbi3 Perovskite Solar Cells, Ramon Songtanasit
Chulalongkorn University Theses and Dissertations (Chula ETD)
A TiO2 compact (cp) layer or blocking layer (bl) plays a crucial role in a hybrid organic-inorganic lead halide perovskite solar cell (PSC) because it prevents the carrier recombination at the interface of fluorine-doped tin oxide (FTO) and perovskite layers. In this work, fabrication, characterizations of cp-TiO2 and their effects on the PSC were studied. The cp-TiO2 layers in this work were fabricated by radio frequency (RF)-magnetron sputtering method and spin coating method with various conditions. The cp-TiO2 layer was incorporated into the PSC device structure consisting of Au/spiro-OMeTAD/MAPbI3/mp-TiO2/cp-TiO2/FTO. For the sputtering method, cp-TiO2 could selectively block the transport of …
Tribological Characterization Of Lapping Lubricant In Hard Disk Drive Fabrication, Sawanee Jitphayomkun
Tribological Characterization Of Lapping Lubricant In Hard Disk Drive Fabrication, Sawanee Jitphayomkun
Chulalongkorn University Theses and Dissertations (Chula ETD)
One of the most important processes in hard disk drive fabrication is the lapping process. As two bodies are in contact, the friction occurs, and the softer material can be worn out by the harder. By using lubricant in the lapping process, it does not only reduce the friction, but it also transfers heat and captures debris away from the surface contacts. This thesis work focused on the effects of tribological parameters toward the characteristics of lubricants, using ball-on-disk tribometer. The tribological behaviors between using different base lubricants were investigated. At the same condition as final lapping process, EG-based and …
ไฮโดรดีออกซีจีเนชันของกวัยอะคอลและน้ำมันชีวภาพบนนิกเกิลโมลิบดินัม/เซอร์โคเนีย-อะลูมินา, ชนิสรา แผ่นผา
ไฮโดรดีออกซีจีเนชันของกวัยอะคอลและน้ำมันชีวภาพบนนิกเกิลโมลิบดินัม/เซอร์โคเนีย-อะลูมินา, ชนิสรา แผ่นผา
Chulalongkorn University Theses and Dissertations (Chula ETD)
งานวิจัยนี้ต้องการสังเคราะห์และศึกษาอิทธิพลของตัวรองรับ ZrO2-Al2O3 ต่อกัมมันตภาพของตัวเร่งปฏิกิริยานิกเกิลโมลิบดินัมบนตัวรองรับผสมเซอร์โคเนีย-อะลูมินา (NiMo/ZrO2-Al2O3) เพื่อใช้ในการเร่งปฏิกิริยาไฮโดรดีออกซีจีเนชันของกวัยอะคอลและน้ำมันชีวภาพ โดยทำการสังเคราะห์ตัวรองรับผสมเซอร์โคเนียและอะลูมินาที่อัตราส่วนโดยโมลเซอร์โคเนียต่ออะลูมินา (ZrO2/Al2O3) เท่ากับ 0/1 1/4 2/3 4/1 และ 1/0 ด้วยวิธีไฮโดรเทอร์มอล (hydrothermal method) จากนั้นสังเคราะห์ตัวเร่งปฏิกิริยา NiMo บนตัวรองรับผสมเซอร์โคเนีย-อะลูมินา ด้วยวิธีอิมเพรกเนชัน (impregnation method) โดยใช้นิกเกิล 3.3% และโมลิบดินัม 15% โดยน้ำหนักของตัวรองรับ ศึกษาภาวะในการไฮโดรดีออกซีจีเนชัน ได้แก่ ความดันแก๊สไฮโดรเจนเริ่มต้น (10-30 บาร์) และระยะเวลาในการทำปฏิกิริยา (2-6 ชม.) ก่อนทำปฏิกิริยาตัวเร่งปฏิกิริยาถูกรีดักชัน (reduction) แบบอิน-ซิทู (in-situ) ที่ความดันแก๊สไฮโดรเจนเริ่มต้น 10 บาร์ อุณหภูมิ 400 oซ เป็นเวลา 2 ชม. ทำไฮโดรดีออกซีจีเนชันที่อุณหภูมิ 300 oซ ควบคุมอัตราการกวนอยู่ที่ 400 รอบ/นาที จากการศึกษาพบว่า การใช้ตัวเร่งปฏิกิริยา NiMo/ZrO2-Al2O3 ทำให้ค่าการเปลี่ยนแปลงกวัยอะคอลและปริมาณฟีนอลมีแนวโน้มลดลงเมื่อปริมาณ ZrO2 เพิ่มขึ้น แต่สามารถยับยั้งการเกิดโค้กบนพื้นผิวตัวเร่งปฏิกิริยาได้เมื่อเทียบกับการใช้ตัวรองรับ Al2O3 ในส่วนของภาวะในการทำปฏิกิริยาพบว่า ความดันแก๊สไฮโดรเจนเริ่มต้นส่งผลต่อตัวเร่งปฏิกิริยา NiMo/ZrO2-Al2O3 2/3 โดยเมื่อความดันเพิ่มขึ้น ค่าการเปลี่ยนแปลงกวัยอะคอลและปริมาณฟีนอลมีแนวโน้มสูงขึ้น และสามารถยับยั้งเกิดการคาร์บอนบนพื้นผิวตัวเร่งปฏิกิริยาได้ สำหรับผลของระยะเวลาในการทำปฏิกิริยาพบว่า ตัวเร่งปฏิกิริยาทุกตัวมีค่าการเปลี่ยนแปลงกวัยอะคอล ปริมาณฟีนอล และการเกิดโค้กบนพื้นผิวตัวเร่งปฏิกิริยาเพิ่มขึ้นเมื่อระยะเวลาในการทำปฏิกิริยาเพิ่มขึ้น เมื่อศึกษากัมมันตภาพของตัวเร่งปฏิกิริยา NiMo/ZrO2-Al2O3 2/3 ต่อไฮโดรดีออกซีจีเนชันของน้ำมันชีวภาพที่ได้จากการไพโรไลซิสของขี้เลื้อยและปริมาณคาร์บอนบนพื้นผิวตัวเร่งปฏิกิริยาพบว่า ตัวเร่งปฏิกิริยา NiMo/ZrO2-Al2O3 2/3 สามารถลดปริมาณออกซิเจนในน้ำมันชีวภาพจาก 55.9 เป็น 35.3% โดยน้ำหนัก จึงทำให้ค่าความร้อนของน้ำมันชีวภาพมีค่าสูงขึ้นจาก 13.5 เป็น 22.8 เมกะจูล/กิโลกรัม
รีดิวซ์กราฟีนออกไซด์/เลเยอร์ดับเบิลไฮดรอกไซด์คอมพอสิตเป็นตัวเก็บประจุยวดยิ่งฐานเซลล์เคมีไฟฟ้าเชิงแสง, ณัฐภพ เกษรเทียน
รีดิวซ์กราฟีนออกไซด์/เลเยอร์ดับเบิลไฮดรอกไซด์คอมพอสิตเป็นตัวเก็บประจุยวดยิ่งฐานเซลล์เคมีไฟฟ้าเชิงแสง, ณัฐภพ เกษรเทียน
Chulalongkorn University Theses and Dissertations (Chula ETD)
ตัวเก็บประจุยวดยิ่งเป็นอุปกรณ์กักเก็บพลังงานที่ปัจจุบันได้รับความนิยมเนื่องด้วย มีคุณสมบัติโดดเด่นหลายประการ เช่น การอัดประจุและคายประจุรวดเร็ว มีค่าความหนาแน่นของกำลังงานสูง มีความเสถียร และมีราคาถูกเมื่อเทียบกับแบตเตอรี่ทั่วไป โดยในงานวิจัยนี้ต้องการปรับปรุงค่าความหนาแน่นพลังงานของตัวเก็บประจุยวดยิ่ง โดยใช้รีดิวซ์กราฟีนออกไซด์/ นิกเกิล โคบอลต์ อะลูมิเนียม เลเยอร์ดับเบิลไฮดรอกไซด์เป็นวัสดุคอมพอสิตซึ่งสังเคราะห์ผ่านกระบวนการไฮโดรเทอร์มอล โดยรีดิวซ์กราฟีนออกไซด์และนิกเกิล โคบอลต์ อะลูมิเนียม เลเยอร์ดับเบิลไฮดรอกไซด์แผ่นระดับนาโนถูกรวมกันซึ่งทั้งสองวัสดุนี้เกิดเป็นโครงสร้างระดับชั้นซึ่งสามารถป้องกันการรวมกลุ่มกันเองและยังสามารถปรับปรุงสมบัติการนำไฟฟ้าของเลเยอร์ดับเบิล ไฮดรอกไซด์ที่มีการเติมรีดิวซ์กราฟีนลงไปด้วยเพราะว่าอิเล็กตรอนสามารถถ่ายโอนผ่านวัสดุ คอมพอสิตได้ดีและส่งเสริมการเกิดปฏิกิริยารีดอกซ์ในโครงสร้างคอมพอสิต โดยผลการทดลองทางเคมีไฟฟ้าโดยพบว่าค่าความจุไฟฟ้าจำเพาะสูงสุดของรีดิวซ์กราฟีนออกไซด์/นิกเกิล โคบอลต์ อะลูมิเนียม เลเยอร์ดับเบิลไฮดรอกไซด์เท่ากับ 1,050.4 ฟารัดต่อกรัม จากนั้นนำรีดิวซ์กราฟีนออกไซด์/นิกเกิล โคบอลต์ อะลูมิเนียมเลเยอร์ดับเบิลไฮดรอกไซด์ที่สังเคราะห์ได้ใช้เป็นขั้วไฟฟ้าในตัวเก็บประจุยวดยิ่งต่อร่วมกับเซลล์แสงอาทิตย์เชิงเคมีไฟฟ้าเพื่อกักเก็บพลังงานในรูปของ ความจุไฟฟ้าไฟฟ้าชั่วขณะโดยผลการทดลองเบื้องต้นแสดงให้เห็นว่าตัวเก็บประจุยวดยิ่งต่อร่วมเซลล์แสงอาทิตย์ชนิดสีย้อมไวแสงนั้นสามารถจ่ายพลังงานไฟฟ้าจากการอัดประจุของเซลล์แสงอาทิตย์เป็นเวลา 60 วินาที สามารถเพิ่มความเสถียรของกำลังไฟฟ้าขาออกของเซลล์แสงอาทิตย์ได้ชั่วขณะเมื่อความเข้มแสงมีการเปลี่ยนแปลง