共查询到20条相似文献,搜索用时 12 毫秒
1.
Anjali SharmaAuthor VitaeMonika TomarAuthor Vitae Vinay GuptaAuthor Vitae 《Sensors and actuators. B, Chemical》2011,156(2):743-752
Semiconducting SnO2 thin films having higher value of electrical conductivity have been deposited using RF sputtering technique in the reactive gas environment (30% O2 + 70% Ar) using a metallic tin (Sn) target for detection of oxidizing NO2 gas. The effect of growth pressure (12-18 mTorr) on the surface morphology and structural property of SnO2 film was studied using Atomic force microscopy (AFM), Scanning electron microscopy (SEM) and X-ray Diffraction (XRD) respectively. Film deposited at 16 mTorr sputtering pressure was porous with rough microstructure and exhibits high sensor response (∼2.9 × 104) towards 50 ppm NO2 gas at a comparatively low operating temperature (∼100 °C). The sensor response was found to increase linearly from 1.31 × 102 to 2.9 × 104 while the response time decrease from 12.4 to 1.6 min with increase in the concentration of NO2 gas from 1 to 50 ppm. The reaction kinetics of target NO2 gas on the surface of SnO2 thin film at the Sn sites play important role in enhancing the response characteristics at lower operating temperature (∼100 °C). The results obtained in the present study are encouraging for realization of SnO2 thin film based sensor for efficient detection of NO2 gas with low power consumption. 相似文献
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S. I. Kasatkin D. V. Vagin P. A. Polyakov O. P. Polyakov 《Automation and Remote Control》2008,69(10):1801-1807
The high-frequency characteristics of the one-layer anisotropic magnetoresistive strip—the magnetosensitive nanoelement of the magnetic field sensor—were analyzed on the basis of the Landau-Livshits-Hilbert equation. The results of this study were shown to coincide completely with the linear microwave theory. The strip frequency characteristics were analyzed for low-anisotropy and high-anisotropy FeNiCo ferromagnetic films of various thickness, strip width, easy magnetization direction, and fixed external magnetic field. 相似文献
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S. G. Krutchinskii 《Automation and Remote Control》2006,67(5):824-834
A principle of designing realizable precision interfaces between sensors and digital ports of microcontrollers and microconverters which enable one not only to measure a physical variable but also to estimate its derivative was proposed. These analog-to-digital interfaces were shown to feature higher precision of conversion without additional precision reference power supplies. The basic requirements on the active analog elements are in good agreement with the “system on chip” VLSI circuit technology. 相似文献
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P. ManjulaAuthor VitaeS. ArunkumarAuthor Vitae Sunkara V. ManoramaAuthor Vitae 《Sensors and actuators. B, Chemical》2011,152(2):168-175
Tin dioxide synthesized by the hydrothermal method, impregnated with Au has been used for the room temperature carbon monoxide sensing in air. Incorporation of poly ethylene glycol (PEG-6000) as a modifier during the synthesis procedure results in well dispersed nanosized particles of SnO2 which influence the sensing capability dramatically. This tailored morphology leads to development of a material with improved sensor response. Incorporation of gold resulted in a composition that was capable of selectively sensing low concentrations (upto 10 ppm CO in air) at temperatures below 50 °C. The mechanism of improved sensing has been explained based on the gas sensing characteristics with support from TEM, UV-DRS, XPS and FTIR. 相似文献
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Chen HuanAuthor Vitae Liu ZhiyuAuthor VitaeFu GangAuthor Vitae 《Sensors and actuators. B, Chemical》2011,156(2):912-917
Two types of tin oxide (SnO2) gas sensors were synthesized, which consist of spherical SnO2 nanoparticles and SnO2 nanorods mixed at different ratio, and their aging processes were studied. Using the Complex Impedance Spectroscopy method the electrical properties that are related to the microscopic structure of the samples were investigated. The evolution of absorption current was measured to analyze the ionic conductance that reflects the charging states of the samples. The results indicate that devices of optimal long-term stability can be obtained by sintering the mixture of SnO2 nanorods and spherical nanoparticles (1:1 weight ratio) at 850 °C. In the samples’ impedance data considerable fluctuation could be seen during the early stage of the aging process, which gradually disappeared after several days. The aging process, which is revealed by the changes in both grain-boundary resistance and capacitance, indicates the corresponding changes in the grain-boundary barrier height and the width of depletion layer. We suggest the DC-field-induced migration of ions within the grain boundaries as the probable cause of the phenomenon. 相似文献
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MEMS-based gas flow sensors 总被引:1,自引:0,他引:1
Yu-Hsiang Wang Chang-Pen Chen Chih-Ming Chang Chia-Pin Lin Che-Hsin Lin Lung-Ming Fu Chia-Yen Lee 《Microfluidics and nanofluidics》2009,6(3):333-346
Micro-electro-mechanical system (MEMS) devices integrate various mechanical elements, sensors, actuators, and electronics
on a single silicon substrate in order to accomplish a multitude of different tasks in a diverse range of fields. The potential
for device miniaturization made possible by MEMS micro-fabrication techniques has facilitated the development of many new
applications, such as highly compact, non-invasive pressure sensors, accelerometers, gas sensors, etc. Besides their small
physical footprint, such devices possess many other advantages compared to their macro-scale counterparts, including greater
precision, lower power consumption, more rapid response, and the potential for low-cost batch production. One area in which
MEMS technology has attracted particular attention is that of flow measurement. Broadly speaking, existing micro-flow sensors
can be categorized as either thermal or non-thermal, depending upon their mode of operation. This paper commences by providing
a high level overview of the MEMS field and then describes some of the fundamental thermal and non-thermal micro-flow sensors
presented in the literature over the past 30 years or so. 相似文献
10.
Sergei Manzhos 《Computer Physics Communications》2009,180(10):2002-17955
An algorithm that fits a continuous function to sparse multidimensional data is presented. The algorithm uses a representation in terms of lower-dimensional component functions of coordinates defined in an automated way and also permits dimensionality reduction. Neural networks are used to construct the component functions.
Program summary
Program title: RS_HDMR_NNCatalogue identifier: AEEI_v1_0Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEEI_v1_0.htmlProgram obtainable from: CPC Program Library, Queen's University, Belfast, N. IrelandLicensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.htmlNo. of lines in distributed program, including test data, etc.: 19 566No. of bytes in distributed program, including test data, etc.: 327 856Distribution format: tar.gzProgramming language: MatLab R2007bComputer: any computer running MatLabOperating system: Windows XP, Windows Vista, UNIX, LinuxClassification: 4.9External routines: Neural Network Toolbox Version 5.1 (R2007b)Nature of problem: Fitting a smooth, easily integratable and differentiatable, function to a very sparse (∼2-3 points per dimension) multidimensional (D?6) large (∼104-105 data) dataset.Solution method: A multivariate function is represented as a sum of a small number of terms each of which is a low-dimensional function of optimised coordinates. The optimal coordinates reduce both the dimensionality and the number of the terms. Neural networks (including exponential neurons) are used to obtain a general and robust method and a functional form which is easily differentiated and integrated (in the case of exponential neurons).Running time: Depends strongly on the dataset to be modelled and the chosen structure of the approximating function, ranges from about a minute for ∼103 data in 3-D to about a day for ∼105 data in 15-D. 相似文献11.
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A study on smell sensing and classification has been developed for a long time by many ways. Most of these have been focused on bad smells, when factors of bad smells were known chemically. Many gas sensors have been developed to detect specific chemicals. Our purpose is to make a new measurement system of smell gases and to apply it to classification of many gases. The proposed system has many sensors in a chamber and detects some chemicals at the same time. Smells data are transmitted to an A/D converter in a host PC which can be used to analyze data to classify the smells. The system must classify not only kinds of smells but also densities of them. In this paper, we develop the measurement system for multi-channel sensors made of metal-oxide semiconductors with power supply circuits. 相似文献
13.
G. Faglia E. Comini M. Pardo A. Taroni G. Cardinali S. Nicoletti G. Sberveglieri 《Microsystem Technologies》1999,6(2):54-59
An Au doped tin oxide thin film was deposited as base material for carbon monoxide detection over a micromachined substrate.
The performances of a recent technique to heat the device, named fast pulsed temperature supply, are presented. This technique
exploits the property that, due to the very low thermal mass of the membrane, the term required to reach steady state conditions
is very short (about 40 ms). The sensor heater is periodically supplied for very short terms, hundred of milliseconds, and
kept off for long ones, seconds or more. Besides a strong reduction of power consumption compared with isothermal characterization,
an increase of sensitivity is observed. Different shapes of the heating wave were examined and results are summarized and
compared.
Received: 1 June 1999 / Accepted: 2 June 1999 相似文献
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In the present work, a conducting polymer, doped polypyrrole, was used to develop a gas sensor by dip-pen nanolithography (DPN). The response time of the sensor to 18 ppm CO2 was 9 s. The sensor response increased linearly as the CO2 concentration increased. A possible mechanism for the CO2 sensing was discussed. 相似文献
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探讨了使用反对数放大器,并与查表法相结合的半导体式气体传感器信号的非线性修正方法,实验表明:这种方法能够满足高体积分数甲烷检测的需要。基于这种方法非线性修正的仪器,甲烷检测体积分数范围为0%~1.0%,检测精度可以达到±5.0%。 相似文献
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Rajan K. Chakrabarty Mark A. Garro Shammah Chancellor Hans Moosmüller 《Computer Physics Communications》2009,180(8):1376-1381
Computer simulation techniques have found extensive use in establishing empirical relationships between three-dimensional (3d) and two-dimensional (2d) projected properties of particles produced by the process of growth through the agglomeration of smaller particles (monomers). In this paper, we describe a package, FracMAP, that has been written to simulate 3d quasi-fractal agglomerates and create their 2d pixelated projection images by restricting them to stable orientations as commonly encountered for quasi-fractal agglomerates collected on filter media for electron microscopy. Resulting 2d images are analyzed for their projected morphological properties.
Program summary
Program title: FracMAPCatalogue identifier: AEDD_v1_0Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEDD_v1_0.htmlProgram obtainable from: CPC Program Library, Queen's University, Belfast, N. IrelandLicensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.htmlNo. of lines in distributed program, including test data, etc.: 4722No. of bytes in distributed program, including test data, etc.: 27 229Distribution format: tar.gzProgramming language: C++Computer: PCOperating system: Windows, LinuxRAM: 2.0 MegabytesClassification: 7.7Nature of problem: Solving for a suitable fractal agglomerate construction under constraints of typical morphological parameters.Solution method: Monte Carlo approximation.Restrictions: Problem complexity is not representative of run-time, since Monte Carlo iterations are of a constant complexity.Additional comments: The distribution file contains two versions of the FracMAP code, one for Windows and one for Linux.Running time: 1 hour for a fractal agglomerate of size 25 on a single processor. 相似文献17.
Recently, space-borne radar systems have been used to collect data for many different remote sensing applications. Some of the applications demand very high accuracy in the measured backscattering cross-sections. Microwave signals passing through the ionosphere may be, at times, affected by the scintillation effect, thus the backscattering cross-section. It is the purpose of this paper to discuss the gigahertz scintillation phenomenon and to assess the potential impact on active microwave observations. 相似文献
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