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ZnO薄膜气敏元件的反应温变和表面反应速率方程
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作者 李长庆 邢建平 +2 位作者 黄少艳 徐勇 裘南畹 《传感技术学报》 CAS CSCD 北大核心 2007年第8期1723-1726,共4页
提出了一种研究气敏元件和材料反应温变的方法和实验装置;给出了反应温变Δtrea随气体浓度C变化的规律;给出了反应放热率Prea与反应温变Δtrea的关系式;得到了表面反应的速率方程一般形式,它包括了目前常用的两种经验公式:双曲线型和幂... 提出了一种研究气敏元件和材料反应温变的方法和实验装置;给出了反应温变Δtrea随气体浓度C变化的规律;给出了反应放热率Prea与反应温变Δtrea的关系式;得到了表面反应的速率方程一般形式,它包括了目前常用的两种经验公式:双曲线型和幂函数型. 展开更多
关键词 ZNO 薄膜 反应温变 表面 速率方程
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SnO_2/CeO_2表面反应速率方程和分子反应几率 被引量:1
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作者 于萍 宋远锋 +3 位作者 袁庆华 王蕾蕾 李建明 裘南畹 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 北大核心 2005年第4期573-576,共4页
介绍了反应温变测试装置原理及其实验规律,利用粉末溅射平面薄膜型SnO2/CeO2酒敏传感器测试了反应温变;并用内插法给出了反应温变随酒气气体浓度变化的规律.对表面反应速率方程进行了推导,并对分子表面反应的几率进行了计算.给出了普遍... 介绍了反应温变测试装置原理及其实验规律,利用粉末溅射平面薄膜型SnO2/CeO2酒敏传感器测试了反应温变;并用内插法给出了反应温变随酒气气体浓度变化的规律.对表面反应速率方程进行了推导,并对分子表面反应的几率进行了计算.给出了普遍的反应速率方程,它包括了两种常用的经验公式:双曲线型和幂函数型公式;同时得到了分子反应几率是小的概念,其值一般为10-3~10-5. 展开更多
关键词 反应温变 反应速率 反应几率
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气敏闭室测量相关实验现象与理论分析
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作者 李娟 邢建平 矫亦林 《传感技术学报》 CAS CSCD 北大核心 2006年第4期976-980,共5页
采用闭式实验测量方法测试了微型平面薄膜元件,对出现的过冲弛豫现象产生机理采用扩散模型进行了物理过程分析,并进行了仿真。给出了气敏元件反应放热率Prea与Δttea反应温变的关系式,据此对还原气体分子表面反应几率进行了研究,并对闭... 采用闭式实验测量方法测试了微型平面薄膜元件,对出现的过冲弛豫现象产生机理采用扩散模型进行了物理过程分析,并进行了仿真。给出了气敏元件反应放热率Prea与Δttea反应温变的关系式,据此对还原气体分子表面反应几率进行了研究,并对闭室测试中浓度的衰减进行了分析,浓度衰减慢过程的结果验证了闭式测量与流通测量的一致性结论。 展开更多
关键词 气敏传感器 反应温变 闭室测试
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Coupled effect of cement hydration and temperature on rheological properties of fresh cemented tailings backfill slurry 被引量:6
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作者 吴迪 蔡嗣经 黄刚 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2014年第9期2954-2963,共10页
The fluidity of fresh cemented tailings backfill(CTB) slurry depends on its rheological properties. Hence, it is crucial to understand the rheology of fresh CTB slurry, which is related to the cement hydration progr... The fluidity of fresh cemented tailings backfill(CTB) slurry depends on its rheological properties. Hence, it is crucial to understand the rheology of fresh CTB slurry, which is related to the cement hydration progress and temperature evolution within CTB mixtures. For this reason, a numerical model was developed to predict the evolution of the rheological properties of fresh CTB slurry under the coupled effect of cement hydration and temperature. Experiments were conducted to investigate the rheological behaviours of the fresh CTB slurry. By comparing the simulated results with the experimental ones, the availability of this developed model was validated. Thereafter, the model was used to demonstrate the coupled effect of cement hydration and temperature on the evolution of fresh CTB slurry's rheological properties, under various conditions(initial CTB temperature, cement to tailings ratio, and water to cement ratio). The obtained results are helpful to better understanding the rheology of CTB slurry. 展开更多
关键词 cemented tailings backfill(CTB) HYDRATION temperature rheology coupled model
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A tetragonal tungsten bronze-type photocatalyst:Ferro-paraelectric phase transition and photocatalysis
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作者 范大勇 种瑞峰 +3 位作者 范峰滔 王秀丽 李灿 冯兆池 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 北大核心 2016年第8期1257-1262,共6页
Although ferroelectrics have potential applications in photocatalysis due to their highly efficient charge separation, their mechanism of charge separation is still unknown. A ferroelectric Sr0.7Ba0.3Nb2O6 (SBN‐70)... Although ferroelectrics have potential applications in photocatalysis due to their highly efficient charge separation, their mechanism of charge separation is still unknown. A ferroelectric Sr0.7Ba0.3Nb2O6 (SBN‐70) semiconductor with a low ferro‐paraelectric phase transition (65℃) was studied. The photocatalytic activity for H2 production by ferroelectric and paraelectric SBN‐70 was examined. The spontaneous polarization in the ferroelectric phase strongly affected the photocata‐lytic performance and parallel ferroelectric domains significantly promoted photogenerated charge separation to result in better photocatalytic H2 production. This knowledge provides an important basis for the fabrication of ferroelectric photocatalysts with improved charge separation ability. 展开更多
关键词 PHOTOCATALYSIS Ferro-paraelectric phase transition Sr0.7Ba0.3Nb2O6 Anomalous photovoltaic effect Temperature-dependent photolumi-nescence excitation spectrum
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Effect of Air Velocity on Thermal Comfort under Thermal Environment Ramp Changing 被引量:1
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作者 嵇赟喆 涂光备 孙琳 《Transactions of Tianjin University》 EI CAS 2004年第4期291-296,共6页
Set points of the indoor air temperature and relative humidity in short-term staying location were studied. In this condition, the thermal reaction of human body varied with the ramp changes of the environmental therm... Set points of the indoor air temperature and relative humidity in short-term staying location were studied. In this condition, the thermal reaction of human body varied with the ramp changes of the environmental thermal parameters.The change rules of about 60 subjects′ thermal reaction to the ramp change of environment were surveyed, and the effect of air movement on the thermal reaction during transient condition was considered by using a questionnaire. With the experimental results and research findings under stable condition, a way to set environmental parameters of short-time staying location was recommended. 展开更多
关键词 transient environment ramp change thermal comfort air velocity
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Application of waterborne acrylic emulsions in coated controlled release fertilizer using reacted layer technology 被引量:4
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作者 申亚珍 赵聪 +1 位作者 周健民 杜昌文 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2015年第1期309-314,共6页
Waterborne acrylic emulsions modified with organic siloxanes and aziridine crosslinker were synthesized and applied as coating of controlled release fertilizer. The free films were characterized and the nutrient relea... Waterborne acrylic emulsions modified with organic siloxanes and aziridine crosslinker were synthesized and applied as coating of controlled release fertilizer. The free films were characterized and the nutrient release profiles of the coated fertilizers were determined. The results show that methyl silicone oil and methylsilanolate sodium could not improve water resistance performance and glass transition temperature Tgof coatings, while the firmness is enhanced. Aziridine crosslinker improves the water resistance performance, firmness and Tg. Incorporation of methyl silicone oil and aziridine crosslinker gives an excellent aqueous acrylic emulsion for coated controlled release fertilizer, with the 30-day cumulative nutrient release reduced to 16% and an estimated nutrient release duration over 190 days. Therefore, this waterborne coating is promising to meet the requirements for controlled release of nutrient and environmental protection. 展开更多
关键词 Controlled release fertilizer Acrylic emulsion SILOXANE CROSSLINKER Reacted layer technology
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Response of North Pacific and North Atlantic decadal variability to weak global warming 被引量:5
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作者 WU Sheng LIU Zheng-Yu +1 位作者 CHENG Jun LI Chun 《Advances in Climate Change Research》 SCIE CSCD 2018年第2期95-101,共7页
The Pacific Decadal Oscillation (PDO) and the Atlantic Multidecadal Variability (AMV) are the two dominant low-frequency modes in the climate system. This research focused on the response of these two modes under ... The Pacific Decadal Oscillation (PDO) and the Atlantic Multidecadal Variability (AMV) are the two dominant low-frequency modes in the climate system. This research focused on the response of these two modes under weak global warming. Observational data were derived from the Hadley Center Sea Ice and Sea Surface Temperature dataset (HadISST) and coupled model outputs from the Coupled Model Intercomparison Project Phase 5 (CMIP5). Changes in PDO and AMV were examined using four models (bcc-csml-1, CCSM4, IPSL-CM5A-LR, and MPI- ESM-LR) with long weak global warming scenarios (RCP2.6). These models captured the two low-frequency modes in both pre-industrial run and RCP2.6 run. Under weak global warming, the time scales of PDO and AMV significantly decreased while the amplitude only slightly decreased. Interestingly, the standard deviation of the North Pacific sea surface temperature anomaly (SSTA) decreased only in decadal time scale, and that of the North Atlantic SSTA decreased both in interannual and decadal time scales. The coupled system consists of a slow ocean component, which has a decadal time scale, and a fast atmospheric component, which is calculated by subtracting the decadal from the total. Results suggest that under global warming, PDO change is dominated by ocean dynamics, and AMV change is dominated by ocean dynamics and stochastic atmosphere forcing. 展开更多
关键词 Pacific decadal oscillation Atlantic multidecadal variability RCP2.6
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Comparison of steam-gasification characteristics of coal char and petroleum coke char in drop tube furnace 被引量:4
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作者 丁路 周志杰 +1 位作者 霍威 于广锁 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2015年第7期1214-1224,共11页
The steam-gasification reaction characteristics of coal and petroleum coke (PC) were studied in the drop tube furnace (DTF). The effects of various factors such as types of carbonaceous material, gasification temp... The steam-gasification reaction characteristics of coal and petroleum coke (PC) were studied in the drop tube furnace (DTF). The effects of various factors such as types of carbonaceous material, gasification temperature (1100- 1400 ℃) and mass ratio of steam to char (0.4:1, 0.6:1 and 1:1 separately) on gasification gas or solid products were investigated. The results showed that for all carbonaceous materials studied, H2 content exhibited the largest part of gasification gaseous products and CH4 had the smallest part. For the two petroleum cokes, CO2 content was higher than CO, which was similar to Zun-yi char. When the steam/char ratio was constant, the carbon con- version of both Shen-fu and PC chars increased with increasing temperature. When the gasification temperature was constant, the carbon conversions of all char samples increased with increasing steam/char ratio. For all the steam/char ratios, compared to water gas shift reaction, char-H2O and char-CO2 reaction were further from the thermodynamic equilibrium due to a much lower char gasification rate than that of water gas shift reaction rate. Therefore, kinetic effects may play a more important role in a char gasification step than thermodynamic effects when the gasification reaction of char was held in DTF, The calculating method for the equilibrium shift in this study will be a worth reference for analysis of the gaseous components in industrial gasifier. The reactivity of residual cokes decreased and the crystal layer (L002/d002) numbers of residual cokes increased with increasing gasification temperature. Therefore, L002/d002, the carbon crystallite structure parameter, can be used to evaluate the reactivity of residual cokes. 展开更多
关键词 Drop tube furnaceSteam/char ratioThermodynamic equilibriumReactivity
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Transesterification Reaction of Waste Cooking Oil and Chicken Fat by Homogeneous Catalysis
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作者 Ignacio Contreras Andrade Jonathan Parra Santiago +2 位作者 Jose Ricardo Sodre Joseph Sebastian Pathiyamattom Carlos Alberto Guerrero-Fajardo 《Journal of Chemistry and Chemical Engineering》 2014年第7期736-743,共8页
In the last years, biodiesel production has been on a steady increase due to it is renewable and biodegradable fuel. The process to obtain biodiesel can be carried out using different raw materials. It is conlmonly pe... In the last years, biodiesel production has been on a steady increase due to it is renewable and biodegradable fuel. The process to obtain biodiesel can be carried out using different raw materials. It is conlmonly performed by transesterification reaction of vegetable oils with methanol and using a homogeneous or heterogeneous catalyst. This work seeks to compare the results produced in transesterification of wasted cooking oil and chicken fat by homogeneous catalysis with NaOH. Due to in each case triglyceride comes from different raw materials, operation conditions differ slightly, which is more evident in the values used for the temperature. For chicken fat was used temperature variations between 35 ℃ and 55 ℃, varying catalyst in percentages between 0.3% and 0.7% with a molar ratio 6:1 in all cases and a reaction time of I h. Likewise, the conditions used in the tmnsesterification process of waste cooking oil were temperature between 50 ℃ and 60 ℃ with a molar ratio 6/1 and 9/1 for alcohol and oil, and catalyst percentage between 0.5% and 0.7% by weight. The yields obtained were between 78% and 94%, or 83% and 95%, for chicken fat and wasted cooking oil, respectively. 展开更多
关键词 BIODIESEL TRANSESTERIFICATION homogeneous catalysis cooking oil chicken fat.
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Design and control of a p-xylene oxidation process
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作者 陶莉莉 胡志华 钱锋 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2015年第12期1935-1944,共10页
The p-xylene(PX) oxidation process is of great industrial importance because of the strong demand of the global polyester fiber.A steady-state model of the PX oxidation has been studied by many researchers.In our prev... The p-xylene(PX) oxidation process is of great industrial importance because of the strong demand of the global polyester fiber.A steady-state model of the PX oxidation has been studied by many researchers.In our previous work,a novel industrial p-xylene oxidation reactor model using the free radical mechanism based kinetics has been developed.However,the disturbances such as production rate change,feed composition variability and reactor temperature changes widely exist in the industry process.In this paper,dynamic simulation of the PX oxidation reactor was designed by Aspen Dynamics and used to develop an effective plantwide control structure,which was capable of effectively handling the disturbances in the load and the temperature of the reactor.Step responses of the control structure to the disturbances were shown and served as the foundation of the smooth operation and advanced control strategy of this process in our future work. 展开更多
关键词 p-Xylene oxidation Dynamic simulation Aspen Dynamics Process design and control
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Interaction between N and C in Soil Has Consequences for Global Carbon Cycling 被引量:2
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作者 Siegfried FLEISCHER 《Journal of Resources and Ecology》 CSCD 2012年第1期16-19,共4页
Energy-yielding processes in the N-cycle form important links with the global C-cycle. One example is demonstrated with the supply of nitrogen to soils, initially resulting in lowered CO2 emissions. This well known ef... Energy-yielding processes in the N-cycle form important links with the global C-cycle. One example is demonstrated with the supply of nitrogen to soils, initially resulting in lowered CO2 emissions. This well known effect has mostly been interpreted as hampered or delayed soil respiration. When added in surplus, however, nitrogen supply does not stabilize the minimum emissions initially obtained, but gradually results in increased CO2 emissions. Specific inhibition of the CO2 consuming process nitrification in soils, with surplus ammonium supply or with acetylene, mostly results in additional CO2 emissions. The difference between this disclosed gross heterotrophic respiration (GHR) and the net CO2 emission (NHR) is the result of a within-soil CO2-sink. Soil respiration solely determined as CO2 emitted as NHR (the common situation) therefore may lead to misinterpretations of the function of the soil system, especially in areas with high N-deposition. As a consequence, the interpreted ’acclimation’ of the soil respiration response in a warmer world should be reconsidered. The concept of respiration inhibition by nitrogen supply may also be questioned. Disregard of these processes, including the indicated N-driven within-soil CO2-sink, may prevent adequate measures counteracting climate change. 展开更多
关键词 soil respiration carbon sink CO2 emissions temperature response climate change N-supply
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A facile hydrothermal preparation and photoluminescence study of ZnO micro/nanostructures on Zn foils 被引量:1
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作者 WU MingZai LU XiangHua +4 位作者 LIU YanMei MA YongQing SUN ZhaoQi LIU XianSong ZHANG LiDe 《Science China Chemistry》 SCIE EI CAS 2011年第10期1547-1551,共5页
ZnO micro/nanostructures with various morphologies were grown via hydrothermal etching of Zn foil.Controlling the reaction temperature and time,rod-like,pencil-like,tube-like and flowerlike ZnO micro/nanostructures co... ZnO micro/nanostructures with various morphologies were grown via hydrothermal etching of Zn foil.Controlling the reaction temperature and time,rod-like,pencil-like,tube-like and flowerlike ZnO micro/nanostructures could be prepared directly on the Zn foil surface at temperatures 100-180℃ with excellent reproducibility.X-ray diffraction patterns indicated that these ZnO micro/nanostructures were hexagonal.Possible mechanisms for the variation of morphology are discussed.Moreover,photoluminescence spectra of the as-grown samples revealed that all of them consist of UV emission band at around 392 nm. 展开更多
关键词 crystal morphology HYDROTHERMAL PHOTOLUMINESCENCE
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Approaching strain limit of two-dimensional MoS_(2) via chalcogenide substitution 被引量:1
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作者 Kailang Liu Xiang Chen +11 位作者 Penglai Gong Ruohan Yu Jinsong Wu Liang Li Wei Han Sanjun Yang Chendong Zhang Jinghao Deng Aoju Li Qingfu Zhang Fuwei Zhuge Tianyou Zhai 《Science Bulletin》 SCIE EI CSCD 2022年第1期45-53,M0004,共10页
Strain engineering is a promising method for tuning the electronic properties of two-dimensional(2 D)materials,which are capable of sustaining enormous strain thanks to their atomic thinness.However,applying a large a... Strain engineering is a promising method for tuning the electronic properties of two-dimensional(2 D)materials,which are capable of sustaining enormous strain thanks to their atomic thinness.However,applying a large and homogeneous strain on these 2D materials,including the typical semiconductor MoS_(2),remains cumbersome.Here we report a facile strategy for the fabrication of highly strained MoS_(2) via chalcogenide substitution reaction(CSR)of MoTe_(2) with lattice inheritance.The MoS_(2)resulting from the sulfurized MoTe_(2) sustains ultra large in-plane strain(approaching its strength limit~10%)with great homogeneity.Furthermore,the strain can be deterministically and continuously tuned to~1.5%by simply varying the processing temperature.Thanks to the fine control of our CSR process,we demonstrate a heterostructure of strained MoS_(2)/MoTe_(2)with abrupt interface.Finally,we verify that such a large strain potentially allows the modulation of MoS_(2) bandgap over an ultra-broad range(~1 e V).Our controllable CSR strategy paves the way for the fabrication of highly strained 2D materials for applications in devices. 展开更多
关键词 Strain engineering 2D materials Chalcogenide substitution Controllable strain Lattice inheritance
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Discovery of a novel 112-type iron-pnictide and La-doping induced superconductivity in Eu_(1-x)La_xFeAs_2(x=0–0.15) 被引量:3
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作者 Jia Yu Tong Liu +6 位作者 Bo-Jin Pan Bin-Bin Ruan Xiao-Chuan Wang Qing-Ge Mu Kang Zhao Gen-Fu Chen Zhi-An Ren 《Science Bulletin》 SCIE EI CAS CSCD 2017年第3期218-221,共4页
We report the discovery and characterization of a novel 112-type iron pnictide EuFeAs2, with La-doping induced superconductivity in a series of Eu1- xLaxFeAs2. The polycrystalline samples were synthesized through soli... We report the discovery and characterization of a novel 112-type iron pnictide EuFeAs2, with La-doping induced superconductivity in a series of Eu1- xLaxFeAs2. The polycrystalline samples were synthesized through solid state reaction method only within a very narrow temperature window around 1073 K. Small single crystals were also grown from a flux method with the size about 100μm. The crystal structure was identified by single crystal X-ray diffraction analysis as a monoclinic structure with space group of P2 1/m. From resistivity and magnetic susceptibility measurements, we found that the parent compound EuFeAs2 shows distinct anomalies probably due to the Fe2+ related antiferromagnetic/structural phase transition near 110K and the Eu2+ related antiferromagnetic phase transition near 40K. La-doping suppressed both phase transitions to lower temperatures and induced superconducting transitions with a Tc - 11 K for Eu0.85La0.15FeAs2. 展开更多
关键词 EuFeAs2 Superconductivity La-doping Antiferromagnetic transition
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Implementation of Interrogation Systems for Fiber Bragg Grating Sensors 被引量:1
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作者 Benjamin VARGHESE P. Dinesh KUMAR R. Mittu RAJU K. N. MADHUSOODANAN 《Photonic Sensors》 SCIE EI CAS 2013年第3期283-288,共6页
The development of two simple methods for wavelength-optical intensity modulation techniques for fiber Bragg grating (FBG) sensors is presented. The performance is evaluated by measuring the strain and temperature. ... The development of two simple methods for wavelength-optical intensity modulation techniques for fiber Bragg grating (FBG) sensors is presented. The performance is evaluated by measuring the strain and temperature. The first method consists of a narrow band source, an optical circulator, an FBG; and a power meter. The source and Bragg reflected signal from the FBG need to be matched to get linear results with good power levels. The source spectral power levels are very critical in this study. The power reflected from a matched reference FBG is fed into the measuring FBG in the second method. Since the FBGs are matched, the entire power is reflected back initially. During the measurement, the change in the measurand causes the reflected power from the sensing FBG to vary. A costly high resolution spectrum analyzer is required only during the characterization of the FBG and source. The performances of two interrogators are compared by measuring the strain and temperature. In the second method, the strain measurements can be made insensitive to the temperature variation by selecting a source with a flat spectrum at the measurement range. Highlights of these methods are the portability, cost effectiveness and better resolution. 展开更多
关键词 Fiber Bragg grating INTERROGATOR reflected power strain and temperature measurement
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