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oe1(光电查) - 科学论文

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出版时间
  • 2018
研究主题
  • interdigital resonator
  • microwave gas sensor
  • PSE-coated
应用领域
  • Optoelectronic Information Science and Engineering
机构单位
  • King Mongkut’s University of Technology North Bangkok
  • Rajamangala University of Technology Suvarnabhumi
571 条数据
?? 中文（中国） ▾

  • [IEEE 2018 IEEE Conference on Antenna Measurements & Applications (CAMA) - V?ster?s, Sweden (2018.9.3-2018.9.6)] 2018 IEEE Conference on Antenna Measurements & Applications (CAMA) - A PSE-Coated Interdigital Resonator Gas Sensor for Agricultural Applications

    摘要： This paper presents a microwave gas sensor based on interdigital resonator structure coating with gas sensing material of poly (styrene-co-maleic acid) partial isobutyl/methyl mixed ester (PSE). This sensor was designed on the center of coplanar waveguide (CPW) to operate at 4 GHz with rejection characteristic. The measured results for five samples of ammonia hydroxide concentration (50, 200, 500, 1000, and 2000 ppm) under a static system in the closed chamber at room temperature were obtained. The levels of gas concentration can be impressively detected by measuring the transmission coefficient changes. The proposed sensor can be employed for several applications such as sensing the gas generating from agricultural products.

    关键词： interdigital resonator,microwave gas sensor,PSE-coated

    更新于2025-09-04 15:30:14

  • Synthesis and Characterization of Organo-Soluble Polyimides Derived from Alicyclic Dianhydrides and a Dihydroxyl-Functionalized Spirobisindane Diamine

    摘要： Two organo-soluble polyimides were synthesized by reaction of alicyclic bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride (BC) or 1,4,7,8-tetrabromobicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic anhydride (BCBr4) with 3,3,3’,3’-tetramethyl-1,1’-spirobisindane-5,5’-diamino-6,6’-diol (SBIDA). BC-SBIDA and BCBr4-SBIDA showed thermal stability of up to ~420 and 352 °C and displayed microporosity as indicated by Brunauer-Emmett-Teller (BET) surface areas of 191 and 243 m2 g-1, respectively. The polyimides were solution processible in polar organic solvents and exhibited strong mechanical properties with tensile modulus of 1.15-1.4 GPa, tensile strength of 27-28 MPa, and elongation at break of 2-4%. Introducing alicyclic moieties disturbs the delocalization of π-electrons across the polyimide backbone that reduces formation of charge transfer complexes (CTCs) leading to formation of colorless and transparent polyimide films. A fresh film sample of the bromine substituted BCBr4-SBIDA showed oxygen permeability of 31 barrer and oxygen/nitrogen selectivity of 5.9. Long-term physical aging of BCBr4-SBIDA over 365 days resulted in decrease of O2 permeability to 17 barrer with a simultaneous boost in O2/N2 selectivity to 6.6, which demonstrated highly competitive performance compared to commercially available polymers for air separation.

    关键词： alicyclic dianhydrides,membrane,polyimides,gas separation,optical properties,intrinsic microporosity

    更新于2025-09-04 15:30:14

  • Effects of gas residence time of CH <sub/>4</sub> /H <sub/>2</sub> on sp <sup>2</sup> fraction of amorphous carbon films and dissociated methyl density during radical-injection plasma-enhanced chemical vapor deposition

    摘要： Quadruple mass spectrometric measurements of CH3 density during radical-injection plasma-enhanced chemical vapor deposition to consider the sp2 fraction of amorphous carbon (a-C) films were performed. The sp2 fraction of the a-C films reached a minimum of 46%, where the CH3 density was maximum for a residence time of 6 ms. The sp2 fraction of the a-C films was tailored with the gaseous phase CH3 density during the deposition. This knowledge is useful for understanding the formation mechanism of bonding structures in the a-C films, which enables the precise control of their electronic properties.

    关键词： CH3 density,sp2 fraction,radical-injection plasma-enhanced chemical vapor deposition,amorphous carbon films,gas residence time

    更新于2025-09-04 15:30:14

  • All Printed Low-Power Metal Oxide Gas Sensors on Polymeric Substrates

    摘要： This paper presents a novel approach for fabrication of miniaturized and fully printed metal oxide (MOX) gas sensors on polyimide substrate by using digital manufacturing of the functional layers, namely aerosol jet and inkjet printing technologies. We are reporting for the first time a stacking approach for all-printed metal-oxide sensors. High resolution (~20 μm) printing of metallic patterns is enabled by aerosol jet of gold (Au) nanoparticles in solution, which leads to printed resistive thermal transducers with a reduced size of 500×500 μm2. Wide area printing feature of the aerosol jet is also applied for printing thin (~2 μm) inter-dielectric polyimide layer in between the heater and gold electrodes. The gas sensing layer, i.e. Pd-doped Tin Oxide (SnO2) nanoparticles, is deposited through drop on demand inkjet printing. Proper operation of the printed sensors is evaluated in both dry and humid conditions under reducing and oxidizing gases i.e. CO and NO2, respectively. All the tests are performed at 250 oC, produced by the integrated micro-hotplate at a low power consumption of ~78mW. The chemo-resistive responses of the sensors towards both the gases are found to be in the acceptable range as compared to conventional metal-oxide gas sensor responses. These results are very promising for future integration of metal-oxide gas sensors notably in smart printed electronics, disposable systems and wearables.

    关键词： Aerosol Jet,Metal Oxide,Printing,Gas Sensors,Micro-hotplates,Inkjet

    更新于2025-09-04 15:30:14

  • Synthesis and Characterization of Carbon Nanotubes by Modified Flame Fragments Deposition Method

    摘要： This study focuses on the synthesis of carbon nanotubes from Iraqi natural gas via a modified flame fragments deposition method in presence and absence of the catalyst. Four types of catalysts were used for the growth of carbon nanotubes. These types are iron doped on magnesium oxide (Fe/MgO), iron-cobalt doped on calcium carbonate (Fe-Co/CaCO3) and iron(III) oxide. All these four types were prepared in one batch by a home made instrument.The implemented technique ensures the same experimental conditions such as type of carbon source, type of carrier gas, flow rate of gases, growth temperature and synthesis time of growth for all synthesized samples. Various experimental techniques viz., X-ray diffraction, Raman spectroscopy, scanning electron microscopy and thermogravimetric analysis were used for characterization of the synthesized carbon nanotubes.

    关键词： Flame fragments deposition,Natural gas,Carbon nanotubes

    更新于2025-09-04 15:30:14

  • Hybrid PV and wind grid-connected renewable energy system to reduce the gas emission and operation cost

    摘要： This paper presents the methodology and results of the simulation and optimization of a hybrid renewable energy system for supply to a workstation reducing the gas emissions and the operation costs, so that to determinate the optimal system. The fundamentals equations used to estimate the operational costs are presented. The software used to simulate and optimize the purposed system is HOMER Pro?, this software can simulate energy systems with renewable fractions and optimize those systems to obtain the best system to use. In addition, the hybrid PV/Wind system replace 23.01 % of the grid purchases when they are working in parallel, the hybrid PV/Wind system take a reduction of the 12.46 % annual operation cost over the 100% of grid purchased and 9.3 % of the total operation cost over the 100% of the grid purchased. Finally, it can be concluded that the use of renewable energy systems takes greatest reductions on the supply systems if it takes the optimal design to develop the supply system.

    关键词： Renewable energy systems,Hybrid PV & Wind system,Energy management system,Gas emissions

    更新于2025-09-04 15:30:14

  • High‐Performance, Transparent Thin Film Hydrogen Gas Sensor Using 2D Electron Gas at Interface of Oxide Thin Film Heterostructure Grown by Atomic Layer Deposition

    摘要： A high-performance, transparent, and extremely thin (<15 nm) hydrogen (H2) gas sensor is developed using 2D electron gas (2DEG) at the interface of an Al2O3/TiO2 thin film heterostructure grown by atomic layer deposition (ALD), without using an epitaxial layer or a single crystalline substrate. Palladium nanoparticles (≈2 nm in thickness) are used on the surface of the Al2O3/TiO2 thin film heterostructure to detect H2. This extremely thin gas sensor can be fabricated on general substrates such as a quartz, enabling its practical application. Interestingly, the electron density of the Al2O3/TiO2 thin film heterostructure can be tailored using ALD process temperature in contrast to 2DEG at the epitaxial interfaces of the oxide heterostructures such as LaAlO3/SrTiO3. This tunability provides the optimal electron density for H2 detection. The Pd/Al2O3/TiO2 sensor detects H2 gas quickly with a short response time of <30 s at 300 K which outperforms conventional H2 gas sensors, indicating that heating modules are not required for the rapid detection of H2. A wide bandgap (>3.2 eV) with the extremely thin film thickness allows for a transparent sensor (transmittance of 83% in the visible spectrum) and this fabrication scheme enables the development of flexible gas sensors.

    关键词： gas sensor,oxide heterostructure,thin film,atomic layer deposition,hydrogen

    更新于2025-09-04 15:30:14

  • Investigation of the Combined Efficiency of a Solar/Gas Hybrid Water Heating System

    摘要： In climate regions with large seasonal variations in solar radiation, such as the Pacific Northwest of the United States, a solar thermal energy collector might not economically satisfy year-round domestic water heating demands, requiring an auxiliary unit, such as a natural gas-fired water heater. Previous studies have shown that the burner efficiency of a gas-fired water heater varies depending on the log-mean temperature difference between the cold fluid (water) and the hot fluid (combustion gases). In a solar/gas hybrid water heating system where solar collectors are used in conjunction with a gas-fired heater, the partial heating of water provided by solar input reduces the log-mean temperature difference value for the gas heater, reducing the efficiency of the gas burner. Since this efficiency reduction varies depending on the amount of pre-heating provided by solar energy input, it is difficult to accurately predict the actual cost and energy savings offered by solar/gas hybrid water heaters in different climate scenarios. Hence, to predict the actual energy and cost savings under various design conditions, the performance of solar/gas hybrid systems must be better understood. The purpose of this work is to experimentally determine the thermal performance of a solar/gas water hybrid water heating system with a 6.44 m2 flat plate solar collector array and a 22.3 kW natural gas burner in Corvallis, Oregon. Under different temperature lifts and solar insolation values, the system was operated at three different modes of heating: solar, gas, and combined solar/gas mode. The overall system thermal efficiency value for each mode is calculated. The efficiency of the solar collector heating system was found to be 41.97%, 39.82%, and 35.05% at initial water temperature of 20, 30, and 51.5 °C, respectively. For initial water temperatures of 20, 30, and 51.5 °C, the efficiency of the gas burner was found to be 69.2%, 66.4%, and 65.5% at the HHV, and 76.7%, 73.6%, and 72.6% at the LHV of natural gas, respectively. In the combined solar/gas heating mode, the efficiency of the gas burner decreased with increasing solar fraction. For solar fractions of 4.93%, 9.40%, 11.39%, and 14.27%, the efficiency of the gas burner in terms of the HHV of natural gas was found to be of 69.08%, 66.80%, 66.17%, and 65.18%, respectively. Based on the experimental results, a configuration that would provide higher overall system efficiency for combined solar/gas heating is suggested.

    关键词： water heating,Solar thermal,natural gas

    更新于2025-09-04 15:30:14

  • Simulation models for supporting the solar thermal power plant operator

    摘要： The benefits that may accrue for the operators of Solar Thermal Power Plants by integrating simulators to everyday operation and maintenance management is demonstrated by using a simulation environment allowing steady state and transient modelling. Two representative STPPs are used as test cases, namely a hybrid solar gas turbine plant and a solar steam turbine plant. The plants operation is simulated for different operating modes utilizing annual meteorological data. Component faults that may occur during operation, such as mirror soiling and misalignment are studied. The effects of different operating modes on performance and operability are established and evaluated. The effect of components degradation on performance is assessed, the overall plant performance deterioration is quantified, and the possibility for selecting optimal maintenance planning is discussed.

    关键词： Gas turbine,CSP,Fault,Steam turbine,Solar thermal

    更新于2025-09-04 15:30:14

  • Prediction of Adsorption Probability of Oxidizing and Reducing Species on 2D Hybrid Junction of rGO-ZnO from First Principle Analysis

    摘要： The target of this paper is to theoretically investigate the probability of gas (both oxidizing and reducing) adsorption on the van der Waals (vdW) heterojunction formed between p-type rGO and n-type 2D-ZnO, using density functional theory (DFT) based first principle calculation employing Virtual Nanolab (VNL) Atomistix Toolkit (ATK) (v2016.4). Two types of heterostructures are considered viz. heterostructure type-1 where hydroxyl group (sp2) is at the edge of the reduced graphene oxide (rGO) and heterostructure type-2 where hydroxyl group (sp3) is perpendicular to the plane of rGO. Adsorption energy, charge transfer and the distance of the nearest atom from the adsorbent are calculated for oxidizing (NO2 as the test case) and reducing (NH3 as the test case) species and compared with that of Oxygen on rGO/2D-ZnO heterostructures as well as on its individual constituent (rGO nanoflakes and 2D-ZnO, separately). Like 2D-ZnO, heterostructure type-1 was also found to be selective towards NO2 with almost three times and five times higher adsorption energy than that of 2D-ZnO and rGO, respectively. On the other hand, it was found that charge distribution in the underlying 2D-ZnO of heterostructure type-2 remained almost unaltered even after gas adsorption and therefore lead to insignificant improvement compared to its 2D-ZnO counterpart.

    关键词： gas adsorption probability,charge transfer,van der Waals heterostructure,Density functional theory,rGO-ZnO hybrid system

    更新于2025-09-04 15:30:14