共查询到19条相似文献，搜索用时 305 毫秒
1.
A liquefied petroleum gas （LPG） sensor with high selectivity, sensitivity and low power consumption has been developed based on indium oxide with very low resistance. Nanocrystalline In203 gas sensing materials were directly synthesized through a one-step controllable solvothermal process at 210 ℃ for 24 h, using InCI3.4H2O as the starting material, cetyltrimethyl ammonium bromide （CTAB） as additive and ethanol as the solvent. The obtained samples were characterized by X-ray diffraction （XRD）, and transmission electron microscopy （TEM）. The results showed that indium oxide takes on uniform cubic shape with range size of 10~30 nm and fine dispersivity. Gas sensitivity was measured in a mixing static gas. The results indicated that 3.0 V is the best working voltage of the sensor to LPG. Sensitivity is 12.6. The response-time and recovery-time are 3 s and 10 s respectively. Power consumption is only around 200 mW. 相似文献
2.
Amorphous InGaZnO (a-IGZO) film is deposited on the glass substrate by radio-frequency sputtering and the influence of annealing on wet etch of a-IGZO films were investigated.The results show that etch rate of IGZO films decrease with the increase of annealing temperature.Etching taper angle is less than 60 and critical dimension (CD) loss is less than 1 μm in over-etching time of 30 s.The fact implies that IGZO films etching with oxalic acid may be a good wet etching way for the thin-film transistor (TFT) ... 相似文献
3.
A displacement sensor based on the fiber Fabry-Perot （F-P） cavity was proposed in this paper. Theoretical and experimental analyses were presented. Displacement resolution was demonstrated by spectrum-domain experiments to obtain the dynamic range of the F-P sensor, and a piezoelectric crystal unit （PZT） was used as the driver. The output signal was modulated by a piezoelectric ceramic ring and demodulated by a phase-locked oscillator. The experimental results show that the displacement resolution of the F-P sensor is less than 5 nm and the dynamic range is more than 100 μm. As acceleration is the second-order differential of displacement, an accelerometer model was proposed using the finite element method （FEM） nd ANSYS software. 相似文献
4.
Mesoporous SnO2 was synthesized using cetyltrimethyl ammonium bromide （CTAB） as supermolecule-template by hydrothermal method followed by calcining under different temperature in air. X-ray diffraction analysis （XRD） and transmission electron microscopy （TEM） techniques were used to characterize the structure of mesoporous SnO2. The results indicated that the gas sensors prepared by using mesoporous SnO2 after calcination at 400 ℃ showed quick response and recovery to ethanol at 200 ℃. It was also found that the mesostructure SnO2 with small particle size had higher sensitivity and selectivity to C2HhOH than the SnO2 nanoparticles the particle size of which is 20 nm synthesized by sol-gel method. 相似文献
5.
This paper presents a bi-directional permanent-magnet linear actuator for directly driving electrohydraulic valves with low power consumption. Its static and dynamic performances were analyzed using the 2D finite element method, taking into account the nonlinear characterization and the eddy current loss of the magnetic material. The experiment and simulation results agree well and show that the prototype actuator can produce a force of±100 N with the maximum power being 7 W and has linear characteristics with a positive magnetic stiffness within a stroke of ±1 mm. Its non-linearity is less than 1.5% and the hysteresis less than 1.5%. The actuator＇s frequency response （-3 dB） of the displacement reaches about 15 Hz, and the most significant factor affecting the dynamic performance is identified as the eddy current loss of the magnetic material. 相似文献
6.
Zhi Huang Zhao-bo Chen Nan-qi Ren Dong-xue Hu Dong-huan Zheng Zhen-peng Zhang 《浙江大学学报(A卷英文版)》2009,10(11):1642-1650
To improve the working and living environment of submarine crews, an integrated system of CO2 removal and O2 regeneration was designed to work under experimental conditions for 50 people in a submarine cabin during prolonged voyages. The integrated system comprises a solid amine water desorption （SAWD） unit for CO2 collection and concentration, a Sabatier reactor for CO2 reduction and a solid polymer electrolyte （SPE） unit for O2 regeneration by electrolysis. The performances of the SAWD-Sabatier-SPE integrated system were investigated. The experimental results from the SAWD unit showed that the average CO2 concentration in the CO2 storage tank was more than 96% and the outlet CO2 concentration was nearly zero in the first 45 min, and less than 1/10 of inlet CO2 after 60 min when input CO2 was 0.5% （1000 L）. About 950 L of CO2 was recovered with a recovery rate of 92%-97%. The output CO2 concentration was less than 0.2%, which showed that the adsorption-desorption performance of this unit was excellent. In the CO2 reduction unit we investigated mainly the start-up and reaction performance of the Sabatier reactor. The start-up time of the Sabatier reactor was 6, 8 and 10 rain when the start-up temperature was 187.3, 179.5 and 168 ℃, respectively. The product water was colorless, transparent, and had a pH of 6.9-7.5, and an electrical conductivity of 80μs/cm. The sum of the concentration of metal ions （Ru^3＋, Al^3＋, Pb^2＋） was 0.028% and that of nonmetal ions （Cl^-, SO4^2-） was 0.05%. In the O2 regeneration unit, the O2 generation rate was 0.48 m^3/d and the quantity was 2400 L, sufficient to meet the submariners＇ basic oxygen demands. These results may be useful as a basis for establishing CO2-1evel limits and O2 regeneration systems in submarines or similar enclosed compartments during prolonged voyages. 相似文献
7.
Wan Azlinda Wan-Mohamed Mohamed Hafts Yunus 《美中教育评论》2009,6(4):56-61
Generic skills are skills which contribute towards individual＇s effective and successful participation in the workplace. For juveniles, Technical and Vocational Education （TVE） is one of the platforms that provide them generic skills which enable them to compete for job market. The purpose of this study is to investigate the level of generic skills that has been inculcated through TVE on juveniles in one of the juvenile schools in Malaysia, the time the teachers spent on inculcating the skills, and the challenges the instructors face in the process. There are four focuses of the generic skills that are of interest in this study： communication, teamwork, problem solving and technology. Eight teachers and 119 juveniles were chosen as the respondents from the Juvenile School （JS）. The data collected was through a set of questionnaires from the respondents, and these were analyzed by using frequency, percentage and mean score. The findings from this research show that the level of generic skills inculcated as perceived by the juveniles is at a moderate level. The perceived moderate level of skill acquire of the juveniles is justified by the moderate amount of time that the teachers believed they spend in instilling the generic skills. The teachers also suggested that the lack of understanding on what generic skills are is the main reason for not inculcating generic skills at its highest level. In conclusion, generic skills inculcation on juveniles through TVE in Juvenile School is at an average level. Measures have to be taken so that inculcation of generic skills can be increase to a higher level, as these generic skills will benefit juveniles in the labor force market. 相似文献
8.
The stabilizing conditions of W/O microemulsion of Tx-6-C4H9OH/c-C6h12/H2O system were studied by visual observation.The result shows that when the weight ratio of Tx-6 to C4H9OH is 4:1 ,the W/O microemulsion system has stabilizing and extensive regions,and the system is insensitive to the values of pH and in the range of room temperature.In accordance with the theoretical value of HLB,the suitable value of HLB for Tx-6 and C4H9OH to compose microemulsion is greater than 9,less than or equal to 10 value of HLB.the suitable value of HLB for Tx-6 and C4H9OH to compose microemulsion is greater than 9,less than or equal to 10. 相似文献
9.
The mechanism and criterion of crack initiation and propagation of rocks were investigated by many researchers,And the creep behaviour of rocks was also theoretically and experimentally studied by some scientists and engineers.The characteristics of crack initation and propagation of rocks under creep condition.however,are very improtant for rock engineering and still not paid enough attention by researchers,In this paper,the criterion and mechanism of crack initiation and propagation under creep condition were investigated using specimens collected from sandstone rock formations outcropping in the Emei Mountain,the Sichuan Province of China.Cuboid specimens under three point bending were used in this investigation.All specimens were classified into four sorts and used for Mode-I fracutre of creep frcture tests.The experimental result shows that due to creep deformation.rock crack will inevitably initialt and propagate under a load of KI,which is less than fracture toughness KIC but not less than a constant(marked as KIC2),KIC2 indicates the ability of rock to resist crack initiation and propagation under creep conditions and is less than fracture tough ness KIC.defined as creep fracture toughness in this paper,KIC2 should be considered as an importnat parameter on design and computation of rock engineering.The microstructureal mechanism for crack initiation and propagation of rock materials under creep condition was introduced based on competitive model between softening effect and hardening effect,and the validity of test result was explained.The test result was also verified in rheological theory.When KI is more than KIC2 but less than KIC,rock crack will initiate and propagate after a time interval of sustained loading under creep condition.In order to find the relation between duration of sustained lading.which can lead to crack initiation and propagation,and the initial stress intensity factor KI,an unequal0interval time sequence forecasting and predicting model was introduced,and the relation was obtained for homogeneous and isotropic fine-grained red sandstone.Finally a modified fracture toughness formula was given,in which the influence of fracture process zone(FPZ) was fully considered. 相似文献
10.
The cumulative sum （CUSUM） algorithm is proposed to detect the selfish behavior of a node in a wireless ad hoc network. By tracing the statistics characteristic of the backoff time between successful transmissions, a wireless node can distinguish if there is a selfish behavior in the wireless network. The detection efficiency is validated using a Qualnet simulator. An IEEE 802.11 wireless ad hoc network with 20 senders and 20 receivers spreading out randomly in a given area is evaluated. The well-behaved senders use minimum contention window size of 32 and maximum con- tention window size of I 024, and the selfish nodes are assumed not to use the binary exponential strategy for which the contention window sizes are both fixed as 16. The transmission radius of all nodes is 250 m. Two scenarios are investigated： a single-hop network with nodes spreading out in 100 m~100 m, and all the nodes are in the range of each other; and a multi-hop network with nodes spreading out in 1 000 m~ 1 000 m. The node can monitor the backoff time from all the other nodes and run the detection algorithms over those samples. It is noted that the threshold can significantly affect the detection time and the detection accuracy. For a given threshold of 0.3 s, the false alarm rates and the missed alarm rates are less than 5%. The detection delay is less than 1.0 s. The simulation results show that the algorithm has short detection time and high detection accuracy. 相似文献
11.
1IntroductionSemiconductor metal oxides as chemical sensingmaterials have been extensively studied for a longti medue to their advantageous features,such as good sen-sitivity to the ambient conditions and si mplicity infabrication[1].Among them,it has bee… 相似文献
12.
以In2O3-SnO2石英光透电极为研究电极，采用薄层光谱电化学方法，测定了铁氰化钾体系在不同电位下的光谱电化学行为． 相似文献
13.
Mo_2N与CoMo/(TiO_2—Al_2O_3)催化剂加氢脱硫与加氢脱氮催化性能比较 总被引：1，自引：0，他引：1
本文在同一条件下分别测试了硫化态的催化剂CoMo/(TiO2—Al_2O_3)及氮化态的Mo_2N催化剂的加氢脱硫和加氢脱氮性能,结果表明,对于噻吩的加氢脱硫反应,硫化态催化剂CoMo/(TiO_2—Al_2O_3)在催化活性及稳定性方面都优于Mo_2N,而Mo_2N在毗啶的加氢脱氮反应中显示了较大优势。 相似文献
14.
Facile Fabrication of Fe_3O_4@TiO_2@C Yolk–Shell Spheres as Anode Material for Lithium Ion Batteries
Transition metal oxides have been actively exploited for application in lithium ion batteries due to their facile synthesis,high specific capacity,and environmental-friendly.In this paper,Fe_3O_4@TiO_2@C yolk-shell(Y-S) spheres,used as anode material for lithium ion batteries,were successfully fabricated by Stober method.XRD patterns reveal that Fe_3O_4@TiO_2@C Y-S spheres possess a good crystallinity.But the diffraction peaks' intensity of Fe_3O_4 crystals in the composites is much weaker than that of bare Fe_3O_4 spheres,indicating that the outer anatase TiO_2@C layer can cover up the diffraction peaks of inner Fe_3O_4 spheres.The yolk-shell structure of Fe_3O_4@TiO_2@C spheres is further characterized by TEM,HAADFSTEM,and EDS mapping.The yolk-shell structure is good for improving the cycling stability of the inner Fe_3O_4 spheres during lithium ions insertion-extraction processes.When tested at 200 mA/g,the Fe_3O_4@TiO_2@C Y-S spheres can provide a stable discharge capacity of 450 mAh/g over 100 cycles,which is much better than that of bare Fe_3O_4 spheres and TiO_2@C spheres.Furthermore,cyclic voltammetry curves show that the composites have a good cycling stability compared to bare Fe_3O_4 spheres. 相似文献
15.
以钼磷杂多酸作为光催化还原剂制备了表面负载钼磷杂多酸的纳米金溶胶（PMo12-NGs）,并将此PMo12-NGs修饰到具PVP膜的玻碳电极表面,考察该修饰电极的电化学行为．实验结果表明,用光催化还原法可直接制备得到杂多酸负载量大且均匀性好的纳米金,由此制备的纳米金修饰电极具有PMo12的良好的电化学行为,且电化学响应和电极稳定性优于单独PMo12修饰电极,该修饰电极对IO3^-等有明显的电催化还原作用,其催化速率常数k可达1．34×10^5mol^-1·L·s^-1． 相似文献
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17.
A series of Li_(1-x)Na_xV_3O_8 materials was prepared by solution reaction followed by calcination method and their electrochemical performances in 2 M Li_2SO_4-water-ethanol solution as negative electrodes for aqueous electrolyte lithium ion battery were studied and compared each other.X-ray diffraction analysis revealed that partially substituting sodium for lithium in LiV_3O_8 could increase the interlayer distances of (100) plane.Cyclic voltammetric experiments have demonstrated that the Li~ insertion and extraction kinetics of Li_(0.7)Na_(0.3)V_3O_8 is superior to that of LiV_3O_8.Charge/discharge results showed that the discharge specific capacity of Li_(0.7)Na_(0.3)V_3O_8 electrode is higher than that of LiV_3O_8 electrode. 相似文献
18.
The TiO2thin films have attracted attention be-cause of their remarkable optical and electronic prop-erties[1,2]. They are used in a wide variety of applica-tions such as photocatalysts[3,4], gas sensors[5,6]andsolar cells. Titania exists mainly in three … 相似文献
19.
以Ti(OC4H9)4为原料,采用溶胶-凝胶法制备出光催化剂纳米TiO2和TiO2-Fe2O3复合粉体,并用制得的样品在紫外光催化条件下对刚果红、碱性品红、酸性蓝等三种水溶性染料溶液进行降解实验,讨论了两种催化剂对染料的光催化降解脱色效果。结果表明TiO2-Fe2O3复合粉体对酸性蓝和刚果红的降解效果好于纳米TiO2,两者对碱性品红的降解效果相当。 相似文献