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Sample records for humidity sensing characteristics

  1. Humidity sensing characteristics of hydrotungstite thin films

    Indian Academy of Sciences (India)

    G V Kunte; S A Shivashankar; A M Umarji

    2008-11-01

    Thin films of the hydrated phase of tungsten oxide, hydrotungstite (H2WO4.H2O), have been grown on glass substrates using a dip-coating technique. The -axis oriented films have been characterized by X-ray diffraction and scanning electron microscopy. The electrical conductivity of the films is observed to vary with humidity and selectively show high sensitivity to moisture at room temperature. In order to understand the mechanism of sensing, the films were examined by X-ray diffraction at elevated temperatures and in controlled atmospheres. Based on these observations and on conductivity measurements, a novel sensing mechanism based on protonic conduction within the surface layers adsorbed onto the hydrotungstite film is proposed.

  2. Role of Morphological Structure, Doping, and Coating of Different Materials in the Sensing Characteristics of Humidity Sensors

    Directory of Open Access Journals (Sweden)

    Ashis Tripathy

    2014-09-01

    Full Text Available The humidity sensing characteristics of different sensing materials are important properties in order to monitor different products or events in a wide range of industrial sectors, research and development laboratories as well as daily life. The primary aim of this study is to compare the sensing characteristics, including impedance or resistance, capacitance, hysteresis, recovery and response times, and stability with respect to relative humidity, frequency, and temperature, of different materials. Various materials, including ceramics, semiconductors, and polymers, used for sensing relative humidity have been reviewed. Correlations of the different electrical characteristics of different doped sensor materials as the most unique feature of a material have been noted. The electrical properties of different sensor materials are found to change significantly with the morphological changes, doping concentration of different materials and film thickness of the substrate. Various applications and scopes are pointed out in the review article. We extensively reviewed almost all main kinds of relative humidity sensors and how their electrical characteristics vary with different doping concentrations, film thickness and basic sensing materials. Based on statistical tests, the zinc oxide-based sensing material is best for humidity sensor design since it shows extremely low hysteresis loss, minimum response and recovery times and excellent stability.

  3. Gelatin as a new humidity sensing material: Characterization and limitations

    Energy Technology Data Exchange (ETDEWEB)

    Shapardanis, Steven [School of Engineering and Technology, Central Michigan University, Mt. Pleasant, Michigan, 48859 (United States); Hudpeth, Mathew [Department of Physics, Central Michigan University, Mt. Pleasant, Michigan, 48859 (United States); Kaya, Tolga, E-mail: kaya2t@cmich.edu [School of Engineering and Technology, Central Michigan University, Mt. Pleasant, Michigan, 48859 (United States); Science of Advanced Materials Program, Central Michigan University, Mt. Pleasant, Michigan, 48859 (United States)

    2014-12-15

    The goal of this work is to assert the utility of collagen and its denatured counterpart gelatin as cost-effective alternatives to existing sensing layers comprised of polymers. Rather than producing a material that will need to be discarded or recycled, collagen, as a by-product of the meat and leather industry, could be repurposed. This work examines the feasibility of using collagen as a sensing layer. Planar electrodes were patterned with lift-off process to work with the natural characteristics of gelatin by utilizing metal vapor deposition, spin coating, and photolithography. Characterization methods have also been optimized through the creation of specialized humidity chambers that isolate specific characteristics such as response time, accuracy, and hysteresis. Collagen-based sensors are found to have a sensitivity to moisture in the range of 0.065 pF/%RH. Diffusion characteristics were also analyzed with the diffusion coefficient found to be 2.5 × 10{sup −5} cm{sup 2}/s. Absorption and desorption times were found to be 20 seconds and 8 seconds, respectively. Hysteresis present in the data is attributed to temperature cross-sensitivity. Ultimately, the utility of collagen as a dielectric sensing material is, in part, due to its fibrous macrostructures as well its hydrophilic sites along the peptide chains. Gelatin was patterned between and below interdigitated copper electrodes and tested as a relative humidity sensor. This work shows that gelatin, which is inexpensive, widely available, and easy to process, can be an effective dielectric sensing polymer for capacitive-type relative humidity sensors.

  4. Gelatin as a new humidity sensing material: Characterization and limitations

    Directory of Open Access Journals (Sweden)

    Steven Shapardanis

    2014-12-01

    Full Text Available The goal of this work is to assert the utility of collagen and its denatured counterpart gelatin as cost-effective alternatives to existing sensing layers comprised of polymers. Rather than producing a material that will need to be discarded or recycled, collagen, as a by-product of the meat and leather industry, could be repurposed. This work examines the feasibility of using collagen as a sensing layer. Planar electrodes were patterned with lift-off process to work with the natural characteristics of gelatin by utilizing metal vapor deposition, spin coating, and photolithography. Characterization methods have also been optimized through the creation of specialized humidity chambers that isolate specific characteristics such as response time, accuracy, and hysteresis. Collagen-based sensors are found to have a sensitivity to moisture in the range of 0.065 pF/%RH. Diffusion characteristics were also analyzed with the diffusion coefficient found to be 2.5 × 10−5 cm2/s. Absorption and desorption times were found to be 20 seconds and 8 seconds, respectively. Hysteresis present in the data is attributed to temperature cross-sensitivity. Ultimately, the utility of collagen as a dielectric sensing material is, in part, due to its fibrous macrostructures as well its hydrophilic sites along the peptide chains. Gelatin was patterned between and below interdigitated copper electrodes and tested as a relative humidity sensor. This work shows that gelatin, which is inexpensive, widely available, and easy to process, can be an effective dielectric sensing polymer for capacitive-type relative humidity sensors.

  5. Gelatin as a new humidity sensing material: Characterization and limitations

    Science.gov (United States)

    Shapardanis, Steven; Hudpeth, Mathew; Kaya, Tolga

    2014-12-01

    The goal of this work is to assert the utility of collagen and its denatured counterpart gelatin as cost-effective alternatives to existing sensing layers comprised of polymers. Rather than producing a material that will need to be discarded or recycled, collagen, as a by-product of the meat and leather industry, could be repurposed. This work examines the feasibility of using collagen as a sensing layer. Planar electrodes were patterned with lift-off process to work with the natural characteristics of gelatin by utilizing metal vapor deposition, spin coating, and photolithography. Characterization methods have also been optimized through the creation of specialized humidity chambers that isolate specific characteristics such as response time, accuracy, and hysteresis. Collagen-based sensors are found to have a sensitivity to moisture in the range of 0.065 pF/%RH. Diffusion characteristics were also analyzed with the diffusion coefficient found to be 2.5 × 10-5 cm2/s. Absorption and desorption times were found to be 20 seconds and 8 seconds, respectively. Hysteresis present in the data is attributed to temperature cross-sensitivity. Ultimately, the utility of collagen as a dielectric sensing material is, in part, due to its fibrous macrostructures as well its hydrophilic sites along the peptide chains. Gelatin was patterned between and below interdigitated copper electrodes and tested as a relative humidity sensor. This work shows that gelatin, which is inexpensive, widely available, and easy to process, can be an effective dielectric sensing polymer for capacitive-type relative humidity sensors.

  6. Humidity Sensing Properties of Pre-irradiation Grafted HDPE Membranes

    Institute of Scientific and Technical Information of China (English)

    Zheng Jiao; Qun Fu; Xiang Geng; Zhen Li; Haijian Zhong

    2006-01-01

    Grafted high density polyethylene (HDPE) films have been prepared by grafting sodium styrene sulfonate (SSS) and acrylic acid (AA) onto HDPE using preirradiation method. The structure and surface morphology of both grafted and ungrafted HDPE films were observed by FTIR spectroscopy and scanning electron microscope (SEM), respectively. The humidity sensing properties of grafted HDPE films were investigated. The results show that the impedance of the film decreases with increasing of relative humidity (RH). The films display high sensitivity with nearly three orders of magnitude change in the resistance during the relative humidity variation from 5% to 98%. Grafted HDPE films exhibit excellent properties as humidity sensors.

  7. Fabrication of Porous Silicon Based Humidity Sensing Elements on Paper

    Directory of Open Access Journals (Sweden)

    Tero Jalkanen

    2015-01-01

    Full Text Available A roll-to-roll compatible fabrication process of porous silicon (pSi based sensing elements for a real-time humidity monitoring is described. The sensing elements, consisting of printed interdigitated silver electrodes and a spray-coated pSi layer, were fabricated on a coated paper substrate by a two-step process. Capacitive and resistive responses of the sensing elements were examined under different concentrations of humidity. More than a three orders of magnitude reproducible decrease in resistance was measured when the relative humidity (RH was increased from 0% to 90%. A relatively fast recovery without the need of any refreshing methods was observed with a change in RH. Humidity background signal and hysteresis arising from the paper substrate were dependent on the thickness of sensing pSi layer. Hysteresis in most optimal sensing element setup (a thick pSi layer was still noticeable but not detrimental for the sensing. In addition to electrical characterization of sensing elements, thermal degradation and moisture adsorption properties of the paper substrate were examined in connection to the fabrication process of the silver electrodes and the moisture sensitivity of the paper. The results pave the way towards the development of low-cost humidity sensors which could be utilized, for example, in smart packaging applications or in smart cities to monitor the environment.

  8. A Humidity Sensing Organic-Inorganic Composite for Environmental Monitoring

    Directory of Open Access Journals (Sweden)

    Khasan S. Karimov

    2013-03-01

    Full Text Available In this paper, we present the effect of varying humidity levels on the electrical parameters and the multi frequency response of the electrical parameters of an organic-inorganic composite (PEPC+NiPc+Cu2O-based humidity sensor. Silver thin films (thickness ~200 nm were primarily deposited on plasma cleaned glass substrates by the physical vapor deposition (PVD technique. A pair of rectangular silver electrodes was formed by patterning silver film through standard optical lithography technique. An active layer of organic-inorganic composite for humidity sensing was later spun coated to cover the separation between the silver electrodes. The electrical characterization of the sensor was performed as a function of relative humidity levels and frequency of the AC input signal. The sensor showed reversible changes in its capacitance with variations in humidity level. The maximum sensitivity ~31.6 pF/%RH at 100 Hz in capacitive mode of operation has been attained. The aim of this study was to increase the sensitivity of the previously reported humidity sensors using PEPC and NiPc, which has been successfully achieved.

  9. The humidity sensing properties and mechanism of strontium-hexaferrite

    CERN Document Server

    Zhang, Hui-Feng; Shao, Gang-Qin; Gao, Zhen-Sheng; Liu, Jin-Hua; Girish, H -N

    2016-01-01

    The humidity sensing properties of n-type strontium-hexaferrite semiconductors are investigated at room temperature. The involved materials include hexaferrites of pure Z-type (Sr3Co2Fe24O41) and X-type (Sr2Co2Fe28O46) / W-type (SrCo2Fe16O27) mixture, in which Fe3+ / Fe2+ ions have different lattice sites. The contact and reactions between water and material surface are demonstrated considering the formation of oxide ion vacancy, singly-ionized / fully-ionized oxide ion vacancy, and the chemisorbed / physisorbed / condensed water. An impedance spectra model is proposed considering the material-electrode interface, interior material, grain boundary, absorbed water and Warburg response. The mechanism of electronic coupled with protonic conduction and humidity sensing mechanism are explained.

  10. CMOS integration of inkjet-printed graphene for humidity sensing.

    Science.gov (United States)

    Santra, S; Hu, G; Howe, R C T; De Luca, A; Ali, S Z; Udrea, F; Gardner, J W; Ray, S K; Guha, P K; Hasan, T

    2015-11-30

    We report on the integration of inkjet-printed graphene with a CMOS micro-electro-mechanical-system (MEMS) microhotplate for humidity sensing. The graphene ink is produced via ultrasonic assisted liquid phase exfoliation in isopropyl alcohol (IPA) using polyvinyl pyrrolidone (PVP) polymer as the stabilizer. We formulate inks with different graphene concentrations, which are then deposited through inkjet printing over predefined interdigitated gold electrodes on a CMOS microhotplate. The graphene flakes form a percolating network to render the resultant graphene-PVP thin film conductive, which varies in presence of humidity due to swelling of the hygroscopic PVP host. When the sensors are exposed to relative humidity ranging from 10-80%, we observe significant changes in resistance with increasing sensitivity from the amount of graphene in the inks. Our sensors show excellent repeatability and stability, over a period of several weeks. The location specific deposition of functional graphene ink onto a low cost CMOS platform has the potential for high volume, economic manufacturing and application as a new generation of miniature, low power humidity sensors for the internet of things.

  11. CMOS integration of inkjet-printed graphene for humidity sensing

    Science.gov (United States)

    Santra, S.; Hu, G.; Howe, R. C. T.; de Luca, A.; Ali, S. Z.; Udrea, F.; Gardner, J. W.; Ray, S. K.; Guha, P. K.; Hasan, T.

    2015-11-01

    We report on the integration of inkjet-printed graphene with a CMOS micro-electro-mechanical-system (MEMS) microhotplate for humidity sensing. The graphene ink is produced via ultrasonic assisted liquid phase exfoliation in isopropyl alcohol (IPA) using polyvinyl pyrrolidone (PVP) polymer as the stabilizer. We formulate inks with different graphene concentrations, which are then deposited through inkjet printing over predefined interdigitated gold electrodes on a CMOS microhotplate. The graphene flakes form a percolating network to render the resultant graphene-PVP thin film conductive, which varies in presence of humidity due to swelling of the hygroscopic PVP host. When the sensors are exposed to relative humidity ranging from 10-80%, we observe significant changes in resistance with increasing sensitivity from the amount of graphene in the inks. Our sensors show excellent repeatability and stability, over a period of several weeks. The location specific deposition of functional graphene ink onto a low cost CMOS platform has the potential for high volume, economic manufacturing and application as a new generation of miniature, low power humidity sensors for the internet of things.

  12. Polyimide-coated fiber Bragg grating for relative humidity sensing

    Science.gov (United States)

    Lin, Yao; Gong, Yuan; Wu, Yu; Wu, Huijuan

    2015-03-01

    A fiber-optic humidity sensor has been fabricated by coating a moisture sensitive polymer film to the fiber Bragg grating (FBG). The Bragg wavelength of the polyimide-coated FBG changes while it is exposed to different humidity conditions due to the volume expansion of the polyimide coating. The characteristics of sensors, including sensitivity, temporal response, and hysteresis, were improved by controlling the coating thickness and the degree of imidization during the thermal curing process of the polyimide. In the relative humidity (RH) condition ranging from 11.3% RH to 97.3% RH, the sensitivity of the sensor was about 13.5 pm/% RH with measurement uncertainty of ±1.5% RH.

  13. Growth and humidity sensing properties of plate-like CuO nanostructures

    Science.gov (United States)

    Bayansal, F.; Çetinkara, H. A.; Çankaya, G.

    2014-03-01

    This paper describes a simple, low-temperature and cost-effective liquid-phase method to synthesize homogenous plate-like CuO nanostructures and their sensitivity to humidity. Scanning electron microscopy illustrated that the synthesized CuO nanoplates have thicknesses of ~100 nm. X-ray diffraction measurements showed that the CuO nanostructures have high crystallinity with monoclinic crystal structure preferentially in ? and ? directions. From the temperature-dependant dark electrical resistivity measurements, the ionization energies of the impurity levels and thermal band gap energies of the films are found as 0.30, 0.32 and 1.37, 1.39 for as-synthesized and annealed films, respectively. Gas sensing characteristics of the films were investigated for different concentrations of humidity, isopropyl alcohol, methanol, ethanol, chloroform and acetone vapours. It was found that the sensor is sensitive to humidity but not to the other volatile organic compounds.

  14. Silicon-Based Multiple Microsensors for Sensing Carbon Dioxide, Humidity and Temperature.

    Science.gov (United States)

    Chang, Hsing-Cheng

    A silicon based multiple microsensor for sensing carbon dioxide, humidity and temperature has been investigated. The carbon dioxide microsensor was designed based on gas permeable membrane and ion-sensing field effect transistor structures. The humidity microsensor was designed based on metal-oxide -semiconductor transistor with a polyimide sensing film. The temperature microsensor was also designed based on diode -sensing structure. The multiple microsensors were designed on the same chip and were fabricated by using standard VLSI processing techniques, micromachining processes and compatible polyimide processes. Small dimension, room temperature operation, fast response, and a relatively large chemical reservoir with an inner temperature controlled resistor are some of the special characteristics of this microsensor. Polyimides PMDA-ODA and 6FDA-ODA were chosen for humidity sensing, CO_2 gas selection and for wafer bonding. The polyimide and solid state compatible processes have been developed to reduce the sensor's dimension, simplify the fabrication process, and lower the production cost. A gaseous CO_2 measurement system was developed for measuring the device characteristics. The reaction parameters of the sensors have been analyzed and discussed to explain their sensing mechanisms. A novel polyimide assisted silicon wafer bonding method was investigated. The polyimide PI-2566 (6FDA-ODA) and the adhesion promoter VM-651 (aminopropyltriethoxysilane) were used as an intermediate material to bond two silicon wafers together. By sawing the bonded wafer and measuring the bond strength it was found that this method gave a uniform and strong bond. The bonding temperature was varied from 235^circC to 400 ^circC and the bond absorption characteristics were identified by analyzing the FTIR spectra. The bonding results are discussed and a bond model for the polyimide assisted silicon wafer bonding is suggested. This bonding process is simple and the yield rate is very

  15. Morphological and humidity sensing characteristics of SnO2–CuO, SnO2–Fe2O3 and SnO2–SbO2 nanocooxides

    Indian Academy of Sciences (India)

    B C Yadav; Preeti Sharma; P K Khanna

    2011-07-01

    This paper reports the synthesis of SnO2–CuO, SnO2–Fe2O3 and SnO2–SbO2 composites of nano oxides and comparative study of humidity sensing on their electrical resistances. CuO, Fe2O3 and SbO2 were added within base material SnO2 in the ratio 1 : 0.25, 1 : 0.50 and 1 : 1. Characterizations of materials were done using SEM and XRD. SEM images show the surface morphology and X-ray diffraction reveals the nanostructure of sensing materials. The pellets were annealed at 200, 400 and 600°C respectively for 3 h and after each step of annealing, observations were carried out. It was observed that as relative humidity (%RH) increases, there was decrease in the resistance of pellet for the entire range of RH. Results were found reproducible. SnO2–SbO2 shows maximum sensitivity for humidity (12 M/%RH) among other composites.

  16. Fast-response humidity-sensing films based on methylene blue aggregates formed on nanoporous semiconductor films

    Science.gov (United States)

    Ishizaki, Ryota; Katoh, Ryuzi

    2016-05-01

    We prepared fast-response colorimetric humidity-sensing (vapochromic) films based on methylene blue adsorption onto nanoporous semiconductor (TiO2, Al2O3) films. Color changes caused by changes of humidity could be easily identified visually. A characteristic feature of the vapochromic films was their fast response to changes of humidity. We found that the response began to occur within 10 ms. The response was rapid because all the methylene blue molecules attached to the nanoporous semiconductor surface were directly exposed to the environment. We also deduced that the color changes were caused by structural changes of the methylene blue aggregates on the surface.

  17. Facile Fabrication of MoS2-Modified SnO2 Hybrid Nanocomposite for Ultrasensitive Humidity Sensing.

    Science.gov (United States)

    Zhang, Dongzhi; Sun, Yan'e; Li, Peng; Zhang, Yong

    2016-06-01

    An ultrasensitive humidity sensor based on molybdenum-disulfide- (MoS2)-modified tin oxide (SnO2) nanocomposite has been demonstrated in this work. The nanostructural, morphological, and compositional properties of an as-prepared MoS2/SnO2 nanocomposite were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), energy dispersive spectrometry (EDS), nitrogen sorption analysis, and Raman spectroscopy, which confirmed its successful preparation and rationality. The sensing characteristics of the MoS2/SnO2 hybrid film device against relative humidity (RH) were investigated at room temperature. The RH sensing results revealed an unprecedented response, ultrafast response/recovery behaviors, and outstanding repeatability. To our knowledge, the sensor response yielded in this work was tens of times higher than that of the existing humidity sensors. Moreover, the MoS2/SnO2 hybrid nanocomposite film sensor exhibited great enhancement in humidity sensing performances as compared to the pure MoS2, SnO2, and graphene counterparts. Furthermore, complex impedance spectroscopy and bode plots were employed to understand the underlying sensing mechanisms of the MoS2/SnO2 nanocomposite toward humidity. The synthesized MoS2/SnO2 hybrid composite was proved to be an excellent candidate for constructing ultrahigh-performance humidity sensor toward various applications.

  18. Humidity Sensing Properties of Surface Modified Polyaniline Metal Oxide Composites

    Directory of Open Access Journals (Sweden)

    S. C. Nagaraju

    2014-01-01

    Full Text Available Polyaniline- (PANI praseodymium Oxide (Pr2O3 composites have been synthesized by in situ polymerization method with different weight percentages. The synthesized composites have been characterized by Fourier transform infrared spectroscopy, X-ray diffraction and scanning electron microscopy. The temperature dependent conductivity shows that the conductivity is due to the hopping of polarons and bipolarons. These composites show negative thermal coefficient (α behavior as a function of temperature, which is characteristic behavior of semiconducting materials. Sensor studies have been carried out by two-probe method and found that the sensitivity increases with increase in % RH. It is noticed that stability increase is due to the presence of Pr2O3 in polyaniline up to 30 wt%. A fast recovery and response time along with high sensitivity make these composites suitable for humidity sensors.

  19. An inductive telemetric measurement system for humidity sensing

    Science.gov (United States)

    Marioli, D.; Sardini, E.; Serpelloni, M.

    2008-11-01

    In some specific applications, the measuring environment can have unsuitable characteristics for a correct electronic functioning; it is not possible to connect a sensitive element to the conditioning electronics by standard cables or by a radiofrequency link. A possible solution could be a contactless link with a passive sensor inside the measuring environment and a readout outside. This paper discusses the telemetric system consisting of two contactless coupled planar inductors. The two inductors form a coupled transformer in air, with the primary one connected to the measurement electronics and the secondary one working as the sensitive element. A polymer deposited on the secondary one is sensible to the humidity, and changes its dielectric permittivity causing a variation of the inductor parasitic capacitance. A conditioning electronics measures frequency resonances, while the system extracts the corresponding capacitance values, compensating the distance variation as well. The whole system has been tested in the laboratory, and several results have been reported. These show about 200 fF variation over 1.7 pF for a change of the RH between 60% and 90% at a constant temperature of 22 °C. Moreover, the measured data are compensated on distance variation changing from 15 mm up to 30 mm. The complete explanation of the whole measurement system is described here. The low cost of the sensors and conditioning electronics implies a high diffusion in many application fields, from food packages to automotive.

  20. Humidity-Sensing Properties of One-Step Hydrothermally Synthesized Tin Dioxide-Decorated Graphene Nanocomposite on Polyimide Substrate

    Science.gov (United States)

    Zhang, Dongzhi; Chang, Hongyan; Liu, Runhua

    2016-08-01

    This paper demonstrates the one-step hydrothermal synthesis of a tin dioxide (SnO2)-decorated reduced graphene oxide (RGO) hybrid nanocomposite, which was drop-casted on a polyimide substrate as a humidity sensor. The as-synthesized hybrid was characterized in terms of its nanostructural, morphological and compositional features by SEM, XRD and nitrogen sorption. The humidity sensing properties of the presented RGO/SnO2 hybrid nanocomposite, such as repeatability, stability, response-recovery characteristics, were investigated by exposing it to a broad humidity range of 11-97% RH at room temperature. As a result, the sensor demonstrated a high sensitivity, a good repeatability, an acceptable linearity, a fast response/recovery characteristic and high long-term stability over a full humidity range measurement, indicating the unique advantages of one-step hydrothermal synthesis for sensor fabrication. The possible and proposed sensing mechanism for the sensor is mainly attributed to a humidity-induced transfer of charge carriers occuring at the interfaces and the swelling effect of RGO.

  1. Effect of Pore Size Distribution on Humidity Sensing Properties of MgO doped ZrO2-TiO2 Ceramic

    Science.gov (United States)

    Jain, M. K.; Bhatnagar, M. C.; Sharma, G. L.

    2000-01-01

    The MgO doped ZrO2-TiO2 composite is studied for its humidity sensing characteristics. Though dc electrical properties show very high sensitivity to humidity, it is not useful for practical applications because of the charging effect. The ac conductivity vs relative humidity characteristics of the pellet becomes linear with an increase in sintering temperature. The post treatment at high temperature and high humidity is found to accelerate initial ageing of the pellet and therefore, stabilizes the characteristics more quickly. A physical model has been proposed to correlate initial ageing, effect of sintering temperature and response time with pore size distribution. Pores below 300 Å radii are present in abundance near the ZrTiO4 phase formation temperature. These pores are responsible for higher sensitivity in low humidity region and linear characteristics.

  2. First-principle and experiment investigation of MoS2@SnO2 nano-heterogeneous structures with enhanced humidity sensing performance

    Science.gov (United States)

    Lei, Xiang; Yu, Ke; Li, Honglin; Tang, Zheng; Guo, Bangjun; Li, Jinzhu; Fu, Hao; Zhang, Qingfeng; Zhu, Ziqiang

    2016-04-01

    In this work, we report the First-principle investigation and synthesis of MoS2@SnO2 heterostructure as high-performance humidity sensor by a two-step hydrothermal method. The first-principles calculations were performed to explain water molecule adsorption mechanism by applying density of state model to simulate the interaction between water molecule and sensing base material. The higher specific surface and the lower adsorption energy theoretically predicted the improvement on humidity sensing performance, which was confirmed by experiments testing. The MoS2@SnO2 heterostructure exhibited promoted humidity sensing characteristics on response time of 53 s and recovery time of 21 s, while switching the humidity between 11% relative humidity (RH) and 95% RH. The corresponding humidity sensing mechanisms of MoS2@SnO2 were elaborately interpreted. This work could bring forward a new design method on practical humidity sensing devices with an excellent stability and fast response by using MoS2@SnO2 heterostructure.

  3. Evaluation of humidity sensing properties of TMBHPET thin film embedded with spinel cobalt ferrite nanoparticles

    Science.gov (United States)

    Zafar, Qayyum; Azmer, Mohamad Izzat; Al-Sehemi, Abdullah G.; Al-Assiri, Mohammad S.; Kalam, Abul; Sulaiman, Khaulah

    2016-07-01

    In this study, we report the enhanced sensing parameters of previously reported TMBHPET-based humidity sensor. Significant improved sensing performance has been demonstrated by coupling of TMBHPET moisture sensing thin film with cobalt ferrite nanoparticles (synthesized by eco-benign ultrasonic method). The mean size of CoFe2O4 nanoparticles has been estimated to be 6.5 nm. It is assumed that the thin film of organic-ceramic hybrid matrix (TMBHPET:CoFe2O4) is a potential candidate for humidity sensing utility by virtue of its high specific surface area and porous surface morphology (as evident from TEM, FESEM, and AFM images). The hybrid suspension has been drop-cast onto the glass substrate with preliminary deposited coplanar aluminum electrodes separated by 40 µm distance. The influence of humidity on the capacitance of the hybrid humidity sensor (Al/TMBHPET:CoFe2O4/Al) has been investigated at three different frequencies of the AC applied voltage ( V rms 1 V): 100 Hz, 1 kHz, and 10 kHz. It has been observed that at 100 Hz, under a humidity of 99 % RH, the capacitance of the sensor increased by 2.61 times, with respect to 30 % RH condition. The proposed sensor exhibits significantly improved sensitivity 560 fF/ % RH at 100 Hz, which is nearly 7.5 times as high as that of pristine TMBHPET-based humidity sensor. Further, the capacitive sensor exhibits improved dynamic range (30-99 % RH), small hysteresis ( 2.3 %), and relatively quicker response and recovery times ( 12 s, 14 s, respectively). It is assumed that the humidity response of the sensor is associated with the diffusion kinetics of water vapors and doping of the semiconductor nanocomposite by water molecules.

  4. High sensitivity flexible Lamb-wave humidity sensors with a graphene oxide sensing layer.

    Science.gov (United States)

    Xuan, Weipeng; He, Xingli; Chen, Jinkai; Wang, Wenbo; Wang, Xiaozhi; Xu, Yang; Xu, Zhen; Fu, Y Q; Luo, J K

    2015-04-28

    This paper reports high performance flexible Lamb wave humidity sensors with a graphene oxide sensing layer. The devices were fabricated on piezoelectric ZnO thin films deposited on flexible polyimide substrates. Two resonant peaks, namely the zero order antisymmetric (A0) and symmetric (S0) mode Lamb waves, were observed and fitted well with the theoretical analysis and modelling. With graphene oxide microflakes as the sensing layer, the sensing performance of both wave modes was investigated. The humidity sensitivity of the A0 mode is 145.83 ppm per %RH (at humidity 85%RH), higher than that of S0 mode of 89.35 ppm per %RH. For the first time, we have demonstrated that the flexible humidity sensors work as usual without noticeable deterioration in performance even under severe bending conditions up to 1500 με. Also the sensors showed an excellent stability upon repeated bending for thousand times. All the results demonstrated that the Lamb wave flexible humidity sensors have a great potential for application in flexible electronics.

  5. Designing and adjusting the thickness of polyvinylpyrrolidone waveguide layer on plasmonic nanofilm for humidity sensing

    Science.gov (United States)

    Feng, Zhiqing; Bai, Lan; Guo, Lijiao; Cao, Baosheng; Wu, Jinlei; He, Yangyang

    2017-01-01

    We developed a fast response and high-resolution plasmonic waveguide sensor for sensing environmental humidity by converting the optical signal in the visible light region. The sensor was designed as a layer-on-layer film structure in which the hydrophilic polymer of polyvinylpyrrolidone (PVP) film served as the waveguide layer and was dip-coated onto the plasmonic gold (Au) nanofilm for sensing the environmental humidity. The amount of the absorbed water molecules on the PVP layer could affect the refractive index and thickness of the PVP, leading to a shift of the surface plasmon resonance peak position of Au nanofilm at the different order modes of the waveguide. The theoretic calculations indicated that the optimal thickness of the waveguide layer on the Au nanofilm ranged from 550 to 650 nm. By adjusting the thickness of the PVP layer to 560 nm, the high-resolution optical signals were observed in the visible light region with the humidity shifts ranging from 11% to 85% relative humidity (RH). Our work details a successful attempt to design and prepare the plasmonic waveguide sensor with the lost-cost polymer as the sensing layer for real-time detection of environmental humidity.

  6. Fast Response and High Sensitivity ZnO/glass Surface Acoustic Wave Humidity Sensors Using Graphene Oxide Sensing Layer

    Science.gov (United States)

    Xuan, Weipeng; He, Mei; Meng, Nan; He, Xingli; Wang, Wenbo; Chen, Jinkai; Shi, Tianjin; Hasan, Tawfique; Xu, Zhen; Xu, Yang; Luo, J. K.

    2014-11-01

    We report ZnO/glass surface acoustic wave (SAW) humidity sensors with high sensitivity and fast response using graphene oxide sensing layer. The frequency shift of the sensors is exponentially correlated to the humidity change, induced mainly by mass loading effect rather than the complex impedance change of the sensing layer. The SAW sensors show high sensitivity at a broad humidity range from 0.5%RH to 85%RH with SAW humidity sensors, complemented with full humidity range measurement, highlights their potential in a wide range of applications.

  7. Humidity sensing properties of ZnO-based fibers by electrospinning.

    Science.gov (United States)

    Horzum, Nesrin; Taşçioglu, Didem; Okur, Salih; Demir, Mustafa M

    2011-08-15

    Zinc oxide (ZnO) based fibers with a diameter of 80-100 nm were prepared by electrospinning. Polyvinyl alcohol (PVA) and zinc acetate dihydrate were dissolved in water and the polymer/salt solution was electrospun at 2.5 kV cm(-1). The resulting electrospun fibers were subjected to calcination at 500°C for 2h to obtain ZnO-based fibers. Humidity sensing properties of the fiber mats were investigated by quartz crystal microbalance (QCM) method and electrical measurements. The adsorption kinetics under constant relative humidity (RH) between 10% and 90% were explained using Langmuir adsorption model. Results of the measurements showed that ZnO-based fibers were found to be promising candidate for humidity sensing applications at room temperature.

  8. Zeonex-PMMA microstructured polymer optical FBGs for simultaneous humidity and temperature sensing

    DEFF Research Database (Denmark)

    Woyessa, Getinet; Pedersen, Jens Kristian Mølgaard; Fasano, Andrea

    2017-01-01

    In this Letter, we report for the first time, to the best of our knowledge, the fabrication and characterization of a Zeonex/PMMA microstructured polymer optical fiber (mPOF) Bragg grating sensor for simultaneous monitoring of relative humidity (RH) and temperature. The sensing element (probe...

  9. Chemical bonding and humidity sensing properties of amorphous carbon nitride (a-CNx) by acetylene gas

    Science.gov (United States)

    Aziz, Siti Aisyah Abd; Purhanudin, Noorain; Awang, Rozidawati

    2017-05-01

    Amorphous carbon nitride (a-CNx) thin films were deposited by radio frequency plasma enhance chemical vapor deposition (RF-PECVD) using a fixed mixture of acetylene (C2H2) at 20 sccm and nitrogen (N2) gases at 50 sccm. The films were deposited at different RF power of 60, 70, 80, 90 and 100 W. The deposition pressure, deposition time and substrate temperature were kept constant at 0.8 mbar, 30 minutes and 100°C, respectively. The chemical bonding of the a-CNx thin films was characterized using Fourier transform infrared spectroscopy (FTIR) and its sensing properties was determined using a home built humidity sensor system. The increase of RF powers leads to an increment of formation of double (C=N) and triple (C≡N) bonds as compared to a-CNx deposited using methane (CH4) or ethane (C2H6) gas. This is due to a higher ratio of C to H atoms in C2H2. The humidity sensing performance show the sensitivity of the films is the highest at low deposition power in changes of relative humidity (%RH). The a-CNx thin film show good repeatability and high sensitivity as a humidity sensing materials which prepared at low RF power.

  10. Humidity Sensing Elements Based on Zn-doped TiO2 Films Prepared via a Sol-gel Method

    Directory of Open Access Journals (Sweden)

    Zvezditza Nenova

    2015-06-01

    Full Text Available Humidity sensing elements have been prepared via a sol-gel method on the basis of titanium n-butoxide, doped with ZnO. By this method Zn-modified titania films have been deposited on alumina substrates with interdigitated silver palladium electrodes and subsequent sintering at temperatures of 400°С and 800°С. Scanning electron microscopy has been employed to determine the surface morphology of the films obtained. Structural and compositional characterization has been done by X-ray diffraction analysis and energy dispersive X-ray spectroscopy. Electrical measurements of the characteristics and parameters of the obtained samples have been taken by an impedance analyzer within a frequency range from 100Hz to 1MHz. The impact of the Zn-dopant and sintering temperature on the samples electrical properties has been studied. The samples obtained by the sol-gel method described can be used as humidity sensing elements which change their resistance given changes in relative humidity at frequencies of up to about 1kHz.DOI: http://dx.doi.org/10.5755/j01.ms.21.2.6244

  11. Investigations on the Sensing Mechanism of Humidity Sensors Based on Poly(4-vinylpyridine)/carbon Black Composite by AC Impedance Spectra

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    1 Results Investigations on the sensing mechanism is important for understanding the electrical responses of humidity sensors to humidity change,and could provide guidelines for the design and synthesis of humidity sensitive materials with desirable properties.In this work,the sensing mechanism of humidity sensors based on quaternized poly(4-vinylpyridine) (PVP)/carbon black (CB) composite[1] was studied by measuring their AC impedance spectra at various humidities at room temperature.Under low humidity...

  12. CMOS Humidity Sensor System Using Carbon Nitride Film as Sensing Materials

    Directory of Open Access Journals (Sweden)

    Shaestagir Chowdhury

    2008-04-01

    Full Text Available An integrated humidity sensor system with nano-structured carbon nitride film as humidity sensing material is fabricated by a 0.8 μm analog mixed CMOS process. The integrated sensor system consists of differential humidity sensitive field effect transistors (HUSFET, temperature sensor, and operational amplifier. The process contains two poly, two metal and twin well technology. To form CNx film on Si3N4/Si substrate, plasma etching is performed to the gate area as well as trenches. CNx film is deposited by reactive RF magnetron sputtering method and patterned by the lift-off technique. The drain current is proportional to the dielectric constant, and the sensitivity is 2.8 ㎂/%RH.

  13. AC Humidity Sensing Properties of Mesoporous K2CO3-SiO2 Composite Materials

    Directory of Open Access Journals (Sweden)

    Liang Guo

    2016-01-01

    Full Text Available The mesoporous silica SBA-15 and mesoporous K2CO3-SiO2 composite material were synthesized. Characterization of microstructure and morphology of materials indicated that the composite material had saved the porous framework of mesoporous silica SBA-15. Humidity sensing properties of different inverse proportion K2CO3-SiO2 composite material were studied and we found that the sample with 0.16 g/g K2CO3 exhibited excellent linearity in the wide humidity range. The complex impedance changed five orders of magnitude from 11% RH to 95% RH. The rapid response and recovery time were 10 s and 38 s, respectively. Finally a feasible ion transfer mechanism was brought forward to explain the sensing mechanism.

  14. A New Strategy for Humidity Independent Oxide Chemiresistors: Dynamic Self-Refreshing of In2 O3 Sensing Surface Assisted by Layer-by-Layer Coated CeO2 Nanoclusters.

    Science.gov (United States)

    Yoon, Ji-Wook; Kim, Jun-Sik; Kim, Tae-Hyung; Hong, Young Jun; Kang, Yun Chan; Lee, Jong-Heun

    2016-08-01

    The humidity dependence of the gas sensing characteristics of metal oxide semiconductors has been one of the greatest obstacles for gas sensor applications during the last five decades because ambient humidity dynamically changes with the environmental conditions. Herein, a new and novel strategy is reported to eliminate the humidity dependence of the gas sensing characteristics of oxide chemiresistors via dynamic self-refreshing of the sensing surface affected by water vapor chemisorption. The sensor resistance and gas response of pure In2 O3 hollow spheres significantly change and deteriorate in humid atmospheres. In contrast, the humidity dependence becomes negligible when an optimal concentration of CeO2 nanoclusters is uniformly loaded onto In2 O3 hollow spheres via layer-by-layer (LBL) assembly. Moreover, In2 O3 sensors LBL-coated with CeO2 nanoclusters show fast response/recovery, low detection limit (500 ppb), and high selectivity to acetone even in highly humid conditions (relative humidity 80%). The mechanism underlying the dynamic refreshing of the In2 O3 sensing surfaces regardless of humidity variation is investigated in relation to the role of CeO2 and the chemical interaction among CeO2 , In2 O3 , and water vapor. This strategy can be widely used to design high performance gas sensors including disease diagnosis via breath analysis and pollutant monitoring.

  15. Humidity sensing behaviour of polyaniline/magnesium chromate (MgCrO4) composite

    Indian Academy of Sciences (India)

    T Machappa; M V N Ambika Prasad

    2012-02-01

    ‘in situ’ polymerization of polyaniline (PANI) was carried out in the presence of magnesium chromate (MgCrO4) to synthesize PANI/ceramic (MgCrO4) composite. These prepared composites were characterized by XRD, FTIR and SEM, which confirm the presence of MgCrO4 in polyaniline matrix. The temperature dependent conductivity measurement shows the thermally activated exponential behaviour of PANI /MgCrO4 composites. The decrease in electrical resistance was observed when the polymer composites were exposed to the broad range of relative humidity (ranging between 20 and 95% RH). This decrease is due to increase in surface electrical conductivity resulting from moisture absorption and due to capillary condensation of water causing change in conductivity within the sensing materials. PANI / MgCrO4 composites are found to be sensitive to low humidity ranging from 20 to 50% RH.

  16. Capacitive humidity sensing properties of carbon nanotubes grown on silicon nanoporous pillar array

    Institute of Scientific and Technical Information of China (English)

    JIANG WeiFen; XIAO ShunHua; ZHANG HuanYun; DONG YongFen; LI XinJian

    2007-01-01

    Multi-walled carbon nanotubes (CNTs) were grown on silicon nanoporous pillar array (Si-NPA) by thermal chemical vapor deposition method, and the structural and capacitive humidity sensing properties of CNT/Si-NPA were studied. It was found that with the relative humidity (RH) changing from 11% to 95%, a device response of ~480% was achieved at the frequency of 50000 Hz, and a linear device response curve could be obtained by adopting longitudinal logarithmic coordinate. The response/recovery times were measured to be ~20 s and ~10 s, respectively, which indicated a rather fast response/recovery rate. The adsorption-desorption dynamic cycle experiments demonstrated the high measurement reproducibility of CNT/Si-NPA sensors. These excellent performances were attributed to the unique surface structure, morphology and chemical inertness of CNT/Si-NPA.

  17. Capacitive humidity sensing properties of carbon nanotubes grown on silicon nanoporous pillar array

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Multi-walled carbon nanotubes (CNTs) were grown on silicon nanoporous pillar array (Si-NPA) by thermal chemical vapor deposition method, and the structural and capacitive humidity sensing properties of CNT/Si-NPA were studied. It was found that with the relative humidity (RH) changing from 11% to 95%, a device re-sponse of ~480% was achieved at the frequency of 50000 Hz, and a linear device response curve could be obtained by adopting longitudinal logarithmic coordinate. The response/recovery times were measured to be ~20 s and ~10 s, respectively, which indicated a rather fast response/recovery rate. The adsorption-desorption dynamic cycle experiments demonstrated the high measurement reproducibility of CNT/Si-NPA sensors. These excellent performances were attributed to the unique surface structure, morphology and chemical inertness of CNT/Si-NPA.

  18. Relative humidity sensing using dye-doped polymer thin-films on metal substrates

    Science.gov (United States)

    Kumari, Madhuri; Ding, Boyang; Blaikie, Richard

    2015-12-01

    We demonstrate humidity sensors based on optical resonances sustained in sub-wavelength thick dye-doped polymer coatings on reflecting surfaces. As a result of coupling between dye molecular absorption and Fabry-Perot resonances in the air-coating-surface cavity, the absorption spectra of such thin-film structures show a strong resonant peak under certain illumination conditions. These resonances are sensitive to the structural and material properties of the thin-film, metal underlayer and ambient conditions and hence can be used for gas and vapor sensing applications. Specifically, we present our proof of principle experimental results for humidity sensing using a thin-film structure comprising Rhodamine6G-doped polyvinyl alcohol (PVA) films on silver substrates. Depending on the PVA film thickness, dye-concertation and angle of incidence, the resonant absorption peak can undergo either red-shift or blue-shift as RH level increases in the range 20% to 60%. Also, the absorption magnitude at certain wavelengths near to resonance show almost linear reduction which can be used as the sensing signal. Our simulation studies show a very good agreement with the experimental data. The spectral and temporal sensitivity of this thin-film structure is attributed to the changes in the thickness of the PVA layer which swells by absorbing water molecules

  19. Synthesis and Characterization of Polymeric Graphene Quantum Dots Based Nanocomposites for Humidity Sensing

    Directory of Open Access Journals (Sweden)

    Lam Minh Long

    2016-01-01

    Full Text Available Graphene quantum dots (GQDs were synthesized and incorporated with polyethylenedioxythiophene:poly(4-styrenesulfonate (PEDOT:PSS and carbon nanotube (CNT to form a composite that can be used for humidity sensors. The 600 nm thick composite films contained bulk heterojunctions of CNT/GQD and CNT/PEDOT:PSS. The sensors made from the composites responded well to humidity in a range from 60 to 80% at room temperature and atmospheric pressure. With a CNT content of 0.4 wt.% (GPC-1 to 0.8 wt.% (GPC-2 and 1.2 wt.% (GPC-3, the sensitivity of the humidity sensing devices based on CNT-doped graphene quantum dot-PEDOT:PSS composites was increased from 4.5% (GPC-1 to 9.0% (GPC-1 and 11.0% (GPC-2, respectively. The fast response time of the GPC sensors was about 20 s and it was much improved due to CNTs doping in the composites. The best value of the recovery time was found to be of 40 s, for the GPC composite film doped with 1.2 wt.% CNT content.

  20. Characteristics of Arctic low-tropospheric humidity inversions based on radio soundings

    Directory of Open Access Journals (Sweden)

    T. Nygård

    2013-08-01

    Full Text Available Humidity inversions have a high potential importance in the Arctic climate system, especially for cloud formation and maintenance, in wide spatial and temporal scales. Here we investigate the climatology and characteristics of humidity inversions in the Arctic, including their spatial and temporal variability, sensitivity to the methodology applied and differences from the Antarctic humidity inversions. The study is based on data of the Integrated Global Radiosonde Archive (IGRA from 36 Arctic stations between the years 2000–2009. The results indicate that humidity inversions are nearly all the time present on multiple levels in the Arctic atmosphere. Almost half (48% of the humidity inversions were found at least partly within the same vertical layer with temperature inversions, whereas the existence of the other half may, at least partly, be linked to uneven vertical distribution of horizontal moisture transport. A high atmospheric surface pressure was found to increase the humidity inversion occurrence, whereas relationships between humidity inversion properties and cloud cover were generally relatively weak, although for some inversion properties systematic. The statistics of Arctic humidity inversion properties, especially inversion strength, depth and base height, proved to be very sensitive to the instruments and methodology applied. For example, the median strength of the strongest inversion in a profile was twice as large as the median of all Arctic inversions. The most striking difference between the Arctic and Antarctic humidity inversions was the much larger range of the seasonal cycle of inversion properties in the Arctic. Our results offer a baseline for validation of weather prediction and climate models and also encourage for further studies on humidity inversions due to the vital, but so far poorly understood, role of humidity inversions in Arctic cloud processes.

  1. One-pot synthesis of one-dimensional CdTe-cystine nanocomposite for humidity sensing

    Science.gov (United States)

    Lu, Zhisong; Wang, Jing; Xie, Jiale; Li, Chang Ming

    2014-03-01

    Quantum dot (QD)-incorporated one-dimensional (1D) nanocomposites offer great application potential. However, a facile one-step synthesis of the nanocomposites and fabrication of their free-standing film for sensing has not been accomplished. Herein a rod-shaped nanocomposite is one-pot synthesized via an L-cysteine-assisted hydrothermal approach, in which synthesis parameters including L-cysteine amount, temperature and reaction duration are tailored to control the composite nanostructures. CdTe nanocrystals are incorporated into the L-cystine matrices to form the nanorods, which tangle each other to network an intact film structure via a simple drying process. The free-standing CdTe-cystine nanorod film is directly utilized as a humidity sensor. This work provides a one-pot synthesis approach to grow 1D CdTe incorporated nanocomposites, demonstrating their great potential in film sensing applications.

  2. Zeonex-PMMA microstructured polymer optical FBGs for simultaneous humidity and temperature sensing.

    Science.gov (United States)

    Woyessa, Getinet; Pedersen, Jens K M; Fasano, Andrea; Nielsen, Kristian; Markos, Christos; Rasmussen, Henrik K; Bang, Ole

    2017-03-15

    In this Letter, we report for the first time, to the best of our knowledge, the fabrication and characterization of a Zeonex/PMMA microstructured polymer optical fiber (mPOF) Bragg grating sensor for simultaneous monitoring of relative humidity (RH) and temperature. The sensing element (probe) is based on two separate in-line fiber Bragg gratings (FBGs) inscribed in the fabricated mPOF. A root mean square deviation of 0.8% RH and 0.6°C in the range of 10%-90% RH and 20°C-80°C was found. The developed mPOFBG sensor constitutes an efficient route toward low-cost, easy-to-fabricate and compact multi-parameter sensing solutions.

  3. Taxonomy and remote sensing of leaf mass per area (LMA) in humid tropical forests.

    Science.gov (United States)

    Asner, Gregory P; Martin, Roberta E; Tupayachi, Raul; Emerson, Ruth; Martinez, Paola; Sinca, Felipe; Powell, George V N; Wright, S Joseph; Lugo, Ariel E

    2011-01-01

    Leaf mass per area (LMA) is a trait of central importance to plant physiology and ecosystem function, but LMA patterns in the upper canopies of humid tropical forests have proved elusive due to tall species and high diversity. We collected top-of-canopy leaf samples from 2873 individuals in 57 sites spread across the Neotropics, Australasia, and Caribbean and Pacific Islands to quantify environmental and taxonomic drivers of LMA variation, and to advance remote-sensing measures of LMA. We uncovered strong taxonomic organization of LMA, with species accounting for 70% of the global variance and up to 62% of the variation within a forest stand. Climate, growth habit, and site conditions are secondary contributors (1-23%) to the observed LMA patterns. Intraspecific variation in LMA averages 16%, which is a fraction of the variation observed between species. We then used spectroscopic remote sensing (400-2500 nm) to estimate LMA with an absolute uncertainty of 14-15 g/m2 (r2 = 0.85), or approximately 10% of the global mean. With radiative transfer modeling, we demonstrated the scalability of spectroscopic remote sensing of LMA to the canopy level. Our study indicates that remotely sensed patterns of LMA will be driven by taxonomic variation against a backdrop of environmental controls expressed at site and regional levels.

  4. Strontium-Doped Hematite as a Possible Humidity Sensing Material for Soil Water Content Determination

    Directory of Open Access Journals (Sweden)

    Carlo Grignani

    2013-09-01

    Full Text Available The aim of this work is to study the sensing behavior of Sr-doped hematite for soil water content measurement. The material was prepared by solid state reaction from commercial hematite and strontium carbonate heat treated at 900 °C. X-Ray diffraction, scanning electron microscopy and mercury intrusion porosimetry were used for microstructural characterization of the synthesized powder. Sensors were then prepared by uniaxially pressing and by screen-printing, on an alumina substrate, the prepared powder and subsequent firing in the 800–1,000 °C range. These sensors were first tested in a laboratory apparatus under humid air and then in an homogenized soil and finally in field. The results evidenced that the screen printed film was able to give a response for a soil matric potential from about 570 kPa, that is to say well below the wilting point in the used soil.

  5. Intensity-modulated relative humidity sensing with polyvinyl alcohol coating and optical fiber gratings.

    Science.gov (United States)

    Yang, Jingyi; Dong, Xinyong; Ni, Kai; Chan, Chi Chu; Shun, Perry Ping

    2015-04-01

    A relative humidity (RH) sensor in reflection mode is proposed and experimentally demonstrated by using a polyvinyl alcohol (PVA)-coated tilted-fiber Bragg grating (TFBG) cascaded by a reflection-band-matched chirped-fiber Bragg grating (CFBG). The sensing principle is based on the RH-dependent refractive index of the PVA coating, which modulates the transmission function of the TFBG. The CFBG is properly designed to reflect a broadband of light spectrally suited at the cladding mode resonance region of the TFBG, thus the reflected optical signal passes through and is modulated by the TFBG again. As a result, RH measurements with enhanced sensitivity of ∼1.80  μW/%RH are realized and demodulated in the range from 20% RH to 85% RH.

  6. Morphological and Humidity Sensing Studies of WO3 Mixed with ZnO and TiO2 Powders

    Directory of Open Access Journals (Sweden)

    N. K. Pandey

    2008-09-01

    Full Text Available This paper reports resistive type humidity sensing properties of composite powder of WO3, ZnO and TiO2 taken in the ratio of 8:2:1. Tungsten oxide powder has been obtained by oxidizing Tungsten powder (Lobachemie, 99 % pure at 600 0C. 250 mg of ZnO (qualigens, 99% pure and 125 mg of TiO2 (qualigens, 98% pure have been mixed with 1 gram of WO3. Pellet of this powder mixture has been made at pressure of 3 tones for half an hour. The pellet has been annealed at temperatures of 300 0C, 400 0C and 500 0C. Humidity sensing application of pellet has been studied in a specially designed chamber. Standard solution of potassium sulphate has been used as humidifier and potassium hydroxide as de-humidifier. Variation in resistances has been noted using Sinometre (MΩ range,VC 9808. Relative humidity is measured using standard hygrometer (Huger, Germany. It has been observed that as relative humidity increases, there is decrease in the resistance of the pellet. After annealing of sample at each temperature, it has been exposed to humidity in the chamber. The mean sensitivity of the pellet is calculated for each annealing temperature. It has been observed that as annealing temperature increases from 300 0C to 500 0C, mean sensitivity increases. This composite material carries a good scope for the development of resistive type humidity sensor.

  7. Experimental study on velocity characteristics of recirculation zone in humid air non-premixed flame

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    To examine the effect of the flow field within the recirculation zone on flame structure,the characteristic velocity fields of methane/humid air flame in nonpremixed combustion behind a disc bluff-body burner were experimentally studied by particle image velocimeter (PIV).The results show that two stagnation points exist on the centerline in the recirculation zone flame.However,the distance of the two stagnation points in humid air combustion shortens,and the minimal dimensionless velocity increases compared with the conventional nonhumid air combustion.In addition,the positional curves of the minimal velocities can be partitioned into three phases representing three different flame patterns.The analysis of axial minimal velocities on the centerline and their positions under different co-flow air velocity conditions reveals that fuel-to-air velocity ratio is the crucial parameter that governs humid air combustion flame characteristics.

  8. Fabrication and humidity sensing performance studies of a fluorescent film based on a cholesteryl derivative of perylene bisimide.

    Science.gov (United States)

    Zhang, Shujuan; Zhou, Feng; Peng, Haonan; Liu, Taihong; Ding, Liping; Fang, Yu

    2016-08-01

    A fluorescent film based on a cholesteryl derivative of perylene bisimide (PTCDI-co-CholDEA) was fabricated via utilization of an electrostatic spinning technique on a glass plate surface. SEM studies revealed that the film was characterized by fibrous network structure. It is the structure and the chemical composition that make the fluorescence emission of the film sensitive to the variation of local environmental humidity. The sensitivity of the sensing is 0.1497 (×10(4)a.u. of the intensity)/1% RH, of which RH is the abbreviation of relative humidity. The maximum quenching efficiency of the film is 55.4% when humidity reaches 97% RH. Furthermore, the sensing process is fully reversible, and presence of other commonly found liquids shows little effect to the monitoring process.

  9. The effect of Co-doping on the humidity sensing properties of ordered mesoporous TiO2

    Science.gov (United States)

    Li, Zhong; Haidry, Azhar Ali; Gao, Bin; Wang, Tao; Yao, ZhengJun

    2017-08-01

    Monitoring of humidity is of utmost importance as it is essential part of almost every process in our life. Many commercial humidity sensors based on metal oxide semiconductors are available in the market, but there is still need to synthesize low-cost, fast and highly sensitive humidity sensors with no interference from background environment. The aim of this work was to fabricate the ordered mesoporous un-doped and Co-doped TiO2 (0.1-5 mol% Co) and to analyze its humidity sensing properties at room temperatures. The ordered mesoporous powders with high specific surface area (SSA) were prepared by multicomponent self-assembly procedure and then spray-coated onto the sensor substrates with interdigitated gold electrodes. The sensors exhibited excellent stability and reproducible resistance change under various relative humidity percentages (9-90% RH) with negligible effect of background environment. For instance, the response to 90% RH at room temperature was about five orders of magnitude (∼1.39 × 105) and the response time (Tres) was ∼24 s. The reaction/recovery times of the sensors were compared with commercial humidity sensor to show that the reaction times in this work are not given by the surface reaction of water vapor on the sensor surfaces, rather these are mainly influenced by the experimental setup. The sensor response increased up to 3 mol% Co-contents and then decreased for 5 mol% Co-contents. Based on the experimental results, the surface reaction of humidity is discussed related to specific surface area, average grain size and cobalt contents to understand the humidity sensing mechanism.

  10. Humidity sensing properties of La~(3+)/Ce~(3+)-doped TiO_2-20 wt.% SnO_2 thin films derived from sol-gel method

    Institute of Scientific and Technical Information of China (English)

    李红霞; 史志铭; 刘红伟

    2010-01-01

    The humidity sensing properties of La3+/Ce3+-doped TiO2-20 wt.%SnO2 thin films were studied.Sol-gel method was employed to prepare the films on alumina substrates.By constructing a humidity-impedance measuring system,the sensing behaviors were inspected for the films sintered at different temperatures.Experimental results showed that,0.5 wt.% of La2O3 or Ce2O3 doped films sintered at 500 °C for 2 h had the best humidity sensing properties,the impedance decreasing from 109 ? to below 104 ? in the humidity ra...

  11. Synthesis, Humidity Sensing, Photocatalytic and Antimicrobial Properties of Thin Film Nanoporous PbWO4-WO3 Nanocomposites

    Directory of Open Access Journals (Sweden)

    Markasagayam Visagamani Arularasu

    2017-01-01

    Full Text Available A humidity sensor thin film based on nanoporous PbWO4-WO3 composites has been prepared by spin coating technique with different weight ratio of PbWO4 (Pb and WO3 (WO (PWWO-01, PWWO-82, PWWO-64, PWWO-46, PWWO-28, PWWO-01 and their humidity sensing properties have also been investigated at different relative humidity (RH in the range of 5% - 98% at room temperature with dc resistance. It is found that composite PWWO-28 show best humidity sensing properties with the sensitivity factor value of (Sf 3733. The response and recovery time of humidity sensor are about 50 s and 120 s, respectively. High sensitivity, narrow hysteresis loop, rapid response and recovery, prominent stability and good repeatability are obtained. Synthesized PbWO4-WO3 composites were characterized by power X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, BET and photoluminescence studies. The photocatalytic result demonstrated photocatalytic efficiency of nonporous PWWO-28 composite.  The antimicrobial activity of the composites was determined by disc diffusion method.

  12. Disposable, Paper-Based, Inkjet-Printed Humidity and H2S Gas Sensor for Passive Sensing Applications

    Directory of Open Access Journals (Sweden)

    Abdul Quddious

    2016-12-01

    Full Text Available An inkjet-printed, fully passive sensor capable of either humidity or gas sensing is presented herein. The sensor is composed of an interdigitated electrode, a customized printable gas sensitive ink and a specialized dipole antenna for wireless sensing. The interdigitated electrode printed on a paper substrate provides the base conductivity that varies during the sensing process. Aided by the porous nature of the substrate, a change in relative humidity from 18% to 88% decreases the electrode resistance from a few Mega-ohms to the kilo-ohm range. For gas sensing, an additional copper acetate-based customized ink is printed on top of the electrode, which, upon reaction with hydrogen sulphide gas (H2S changes, both the optical and the electrical properties of the electrode. A fast response time of 3 min is achieved at room temperature for a H2S concentration of 10 ppm at a relative humidity (RH of 45%. The passive wireless sensing is enabled through an antenna in which the inner loop takes care of conductivity changes in the 4–5 GHz band, whereas the outer-dipole arm is used for chipless identification in the 2–3 GHz band.

  13. Disposable, Paper-Based, Inkjet-Printed Humidity and H2S Gas Sensor for Passive Sensing Applications

    KAUST Repository

    Quddious, Abdul

    2016-12-06

    An inkjet-printed, fully passive sensor capable of either humidity or gas sensing is presented herein. The sensor is composed of an interdigitated electrode, a customized printable gas sensitive ink and a specialized dipole antenna for wireless sensing. The interdigitated electrode printed on a paper substrate provides the base conductivity that varies during the sensing process. Aided by the porous nature of the substrate, a change in relative humidity from 18% to 88% decreases the electrode resistance from a few Mega-ohms to the kilo-ohm range. For gas sensing, an additional copper acetate-based customized ink is printed on top of the electrode, which, upon reaction with hydrogen sulphide gas (HS) changes, both the optical and the electrical properties of the electrode. A fast response time of 3 min is achieved at room temperature for a HS concentration of 10 ppm at a relative humidity (RH) of 45%. The passive wireless sensing is enabled through an antenna in which the inner loop takes care of conductivity changes in the 4-5 GHz band, whereas the outer-dipole arm is used for chipless identification in the 2-3 GHz band.

  14. A rapid synthesis/growth process producing massive ZnO nanowires for humidity and gas sensing

    Science.gov (United States)

    Hsu, Nai-Feng; Chung, Tien-Kan

    2014-09-01

    We report a rapid and simple process to massively synthesize/grow ZnO nanowires capable of manufacturing massive humidity/gas sensors. The process utilizing a chemical solution deposition with an annealing process (heating in vacuum without gas) is capable of producing ZnO nanowires within an hour. Through depositing the ZnO nanowires on the top of a Pt-interdigitated-electrode/SiO2/Si-Wafer, a humidity/gas-hybrid sensor is fabricated. The humidity sensitivity (i.e., ratio of the electrical resistance of the sensor at 11-95 % relative humidity level) is approximately 104. The response and recovery time with the humidity changing from 11 to 95 % directly and reversely is 6 and 10 s, respectively. The gas sensitivity (i.e., ratio of electrical resistance of the sensor under the air to vaporized ethanol) is increased from 2 to 56 when the concentration of the ethanol is increased from 40 to 600 ppm. Both the response and recovery times are less than 15 s for the gas sensor. These results show the sensor utilizing the nanowires exhibits excellent humidity and gas sensing.

  15. Humidity sensing properties of Ce-doped nanoporous ZnO thin film prepared by sol-gel method

    Institute of Scientific and Technical Information of China (English)

    Mansoor Anbia; Seyyed Ebrahim Moosavi Fard

    2012-01-01

    The humidity sensitive characteristics of the sensor fabricated from Ce-doped nanoporous ZnO by screen-printing on the alumina substrate with Ag-Pd interdigital electrodes were investigated at different sintering temperatures.The nanoporous thin films were prepared by sol-gel technique.It was found that the impedance of the sensor sintered at 600 ℃ changed more than four order of magnitude in the relative humidity (RH) range of 11%-95% at 25 ℃.The response and recovery time of the sensor were about 13 and 17 s,respectively.The sensor showed high humidity sensitivity,rapid response and recovery,prominent stability,good repeatability and narrow hysteresis loop.These results indicated that Ce-doped nanoporous ZnO thin films can be used in fabricating high-performance humidity sensors.

  16. Humidity Sensing Using Gelatin and Cobalt Chloride Coating on Indium Tin Oxide-Coated Long-Period Grating

    Science.gov (United States)

    Nidhi; Kaler, R. S.; Kapur, Pawan

    2014-01-01

    In this article, humidity sensing using gelatin and cobalt chloride on indium tin oxide coated long-period gratings was proposed and demonstrated. First, a thin overlay of indium tin oxide was deposited on a long-period grating by using a simple dip coating methodology. Similarly, a combination of gelatin and cobalt chloride was deposited onto the indium tin oxide layer. A field emission scanning electron microscope provided detailed evidence of the attachment of amalgamation on long-period gratings. The designed sensor showed a significant shift in the resonance wavelength when the relative humidity varied from 40% to 95%, with a sensitivity of 0.12 nm/% relative humidity and an accuracy of 98.45%.

  17. Effect of thickness on surface morphology, optical and humidity sensing properties of RF magnetron sputtered CCTO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Ahmadipour, Mohsen [Structural Materials Niche Area, School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia, Engineering Campus, 14300 Nibong Tebal, Penang (Malaysia); Ain, Mohd Fadzil [School of Electrical and Electronic Engineering, Universiti Sains Malaysia, Engineering Campus, 14300 Nibong Tebal, Penang (Malaysia); Ahmad, Zainal Arifin, E-mail: srzainal@usm.my [Structural Materials Niche Area, School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia, Engineering Campus, 14300 Nibong Tebal, Penang (Malaysia)

    2016-11-01

    Highlights: • CCTO thin film was synthesized by RF magnetron sputtering successfully. • Increase in thickness lead to increase in grain size and decrease in band gap. • Short response times and recovery times of lead CCTO humidity sensor. • Sensor could detect humidity range (30–90%). - Abstract: In this study, calcium copper titanate (CCTO) thin films were deposited on ITO substrates successfully by radio frequency (RF) magnetron sputtering method in argon atmosphere. The CCTO thin films present a polycrystalline, uniform and porous structure. The surface morphology, optical and humidity sensing properties of the synthesized CCTO thin films have been studied by X-ray diffraction (XRD), atomic force microscopy (AFM), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX), UV–vis spectrophotometer and current-voltage (I–V) analysis. XRD and AFM confirmed that the intensity of peaks and pore size of CCTO thin films were enhanced by increasing the thin films. Tauc plot method was adopted to estimate the optical band gaps. The surface structure and energy band gaps of the deposited films were affected by film thickness. Energy band gap of the layers were 3.76 eV, 3.68 eV and 3.5 eV for 200 nm, 400 nm, and 600 nm CCTO thin films layer, respectively. The humidity sensing properties were measured by using direct current (DC) analysis method. The response times were 12 s, 22 s, and 35 s while the recovery times were 500 s, 600 s, and 650 s for 200 nm, 400 nm, and 600 nm CCTO thin films, respectively at humidity range of 30–90% relative humidity (RH).

  18. Humidity sensing properties of Ni(OH)2 nanoparticles synthesized via sonochemical method

    Science.gov (United States)

    Abbasian, Hamed; Ghanbari, Davood

    2015-01-01

    This work focuses on humidity sensor based Ni(OH)2 nanoparticles. The sonochemical method was employed to prepare nanoparticles and impedance analysis was used to characterize sensitivity, response, and recovery time of the prepared sensor. The Ni(OH)2 sensor was found to have high sensitivity and fast response/recovery time to humidity, and its impedance changed approximately two orders of magnitude from about 2.01 MΩ in dry air 20% RH (relative humidity) to 0.0258 MΩ in 90% RH air. Our results demonstrate the potential application of Ni(OH)2 nanoparticles for fabricating high performance humidity sensors.

  19. Effect of thickness on surface morphology, optical and humidity sensing properties of RF magnetron sputtered CCTO thin films

    Science.gov (United States)

    Ahmadipour, Mohsen; Ain, Mohd Fadzil; Ahmad, Zainal Arifin

    2016-11-01

    In this study, calcium copper titanate (CCTO) thin films were deposited on ITO substrates successfully by radio frequency (RF) magnetron sputtering method in argon atmosphere. The CCTO thin films present a polycrystalline, uniform and porous structure. The surface morphology, optical and humidity sensing properties of the synthesized CCTO thin films have been studied by X-ray diffraction (XRD), atomic force microscopy (AFM), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX), UV-vis spectrophotometer and current-voltage (I-V) analysis. XRD and AFM confirmed that the intensity of peaks and pore size of CCTO thin films were enhanced by increasing the thin films. Tauc plot method was adopted to estimate the optical band gaps. The surface structure and energy band gaps of the deposited films were affected by film thickness. Energy band gap of the layers were 3.76 eV, 3.68 eV and 3.5 eV for 200 nm, 400 nm, and 600 nm CCTO thin films layer, respectively. The humidity sensing properties were measured by using direct current (DC) analysis method. The response times were 12 s, 22 s, and 35 s while the recovery times were 500 s, 600 s, and 650 s for 200 nm, 400 nm, and 600 nm CCTO thin films, respectively at humidity range of 30-90% relative humidity (RH).

  20. Synthesis and Humidity Sensing Properties of Sn-Doped Nano-TiO2

    Directory of Open Access Journals (Sweden)

    P. Raji

    2011-01-01

    30%–97% in a self-designed humidity chamber, and the results revealed that the sensitivity factor increased with an increase in tin molar ratio. Among them, TiO2—20 wt% of SnO2 possessed the highest humidity sensitivity, while the pure TiO2 and SnO2 composite possessed a low sensitivity.

  1. Study of Optical Humidity Sensing Properties of Sol-Gel Processed TiO2 and MgO Films

    Directory of Open Access Journals (Sweden)

    B. C. Yadav

    2007-04-01

    Full Text Available Paper reports a comparative study of humidity sensing properties of TiO2 and MgO films fabricated by Sol-gel technique using optical method. One sensing element of the optical humidity sensor presented here consists of rutile structured two-layered TiO2 thin film deposited on the base of an isosceles glass prism. The other sensing element consists of a film of MgO deposited by same technique on base of the prism. Light from He-Ne laser enters prism from one of refracting faces of the prism and gets reflected from the glass-film interface, before emerging out from its other isosceles face. This emergent beam is allowed to pass through an optical fiber. Light coming out from the optical fiber is measured with an optical power meter. Variations in the intensity of light caused by changes in humidity lying in the range 5%RH to 95%RH have been recorded. MgO film shows better sensitivity than TiO2 film.

  2. The Electrical Characteristics of Aluminium Doped Zinc Oxide Thin Film for Humidity Sensor Applications

    Directory of Open Access Journals (Sweden)

    N. D. Md Sin

    2011-01-01

    Full Text Available The electrical characteristics of aluminum (Al doped zinc oxide (ZnO thin film for high sensitivity humidity sensors are presented. The effects of Al doping concentration at 0∼0.6 at % on the Al doped ZnO thin film properties were investigated using current-voltage measurement. The optical and structural properties were characterized using photoluminescence (PL, scanning emission microscope (SEM, and X-ray diffraction (XRD. Parameter 0.6 at % Aluminum doped show high sensitivity and suitable for humidity sensor. PL show an emissions band with two peaks centered at about 380 nm (ultra-violet (UV and 600 nm (green in a room temperature. The length of the nanorods increases as the doping concentration increases. XRD results show the intensity of the (002 peak decreased with the increasing of doping concentration.

  3. [Design of acupoint electric characteristic sensing needle].

    Science.gov (United States)

    Liu, Tang-yi; Yang, Hua-yuan; Kuai, Le; Gao, Ming

    2007-09-01

    The electric characteristics of acupoints have been confirmed by researchers at home and abroad. Because the traditional detection methods are various (mainly are different positions of the reference electrode), and they are influenced by many affective factors, with unstable results and bad repeatability, so the studies of the electric characteristics of acupoints are limited. The acupoint electric characteristic sensing needle is introduced in detail from its design, detection methods and so on, which can detects changes of the acupoint electric characteristics of channels and acupoints in different healthy states real-timely, dynamically and continuously. It not only can avoid those affective factors, and also the detective results are relatively stable and the repeatability is also better.

  4. Acoustic method of investigating the material properties and humidity sensing behavior of polymer coated piezoelectric substrates

    Science.gov (United States)

    Caliendo, Cinzia

    2006-09-01

    The relative humidity (RH) sensing behavior of a polymeric film was investigated by means of polymer coated surface acoustic wave (SAW) delay lines implemented on single crystal piezoelectric substrates, such as quartz and LiNbO3, and on thin piezoelectric polycrystalline films, such as ZnO and AlN, on Si and GaAs. The same SAW delay line configuration was implemented on each substrate and the obtained devices' operating frequency was in the range of 105-156MHz, depending on the type of the substrate, on its crystallographic orientation, and on the SAW propagation direction. The surface of each SAW device was covered by the same type RH sensitive film of the same thickness and the RH sensitivity of each polymer coated substrate, i.e., the SAW relative phase velocity shift per RH unit changes, was investigated in the 0%—80% RH range. The perturbational approach was used to relate the SAW sensor velocity response to the RH induced changes in the physical parameters of the sensitive polymer film: the incremental change in the mass density and shear modulus of the polymer film per unit RH change were estimated. The shift of the bare SAW delay lines operating frequency induced by the presence of the polymer film, at RH =0% and at T =-10°C, allowed the experimental estimation of the mass sensitivity values of each substrate. These values were in good accordance with those reported in the literature and with those theoretically evaluated by exact numerical calculation. The shift of the bare SAW delay lines propagation loss induced by the polymer coating of the device surface, at RH =0% and at ambient temperature, allowed the experimental estimation of the elastic sensitivity of each substrate. These values were found in good accordance with those available from the literature. The temperature coefficient of delay and the electromechanical coupling coefficient of the bare substrates were also estimated. The membrane sensitivity to ethanol, methanol and isopropylic

  5. Insights on Capacitive Interdigitated Electrodes Coated with MOF Thin Films: Humidity and VOCs Sensing as a Case Study

    KAUST Repository

    Sapsanis, Christos

    2015-07-24

    A prototypical metal-organic framework (MOF), a 2D periodic porous structure based on the assembly of copper ions and benzene dicarboxylate (bdc) ligands (Cu(bdc)·xH2O), was grown successfully as a thin film on interdigitated electrodes (IDEs). IDEs have been used for achieving planar CMOS-compatible low-cost capacitive sensing structures for the detection of humidity and volatile organic compounds (VOCs). Accordingly, the resultant IDEs coated with the Cu(bdc)·xH2O thin film was evaluated, for the first time, as a capacitive sensor for gas sensing applications. A fully automated setup, using LabVIEW interfaces to experiment conduction and data acquisition, was developed in order to measure the associated gas sensing performance.

  6. Insights on Capacitive Interdigitated Electrodes Coated with MOF Thin Films: Humidity and VOCs Sensing as a Case Study.

    Science.gov (United States)

    Sapsanis, Christos; Omran, Hesham; Chernikova, Valeriya; Shekhah, Osama; Belmabkhout, Youssef; Buttner, Ulrich; Eddaoudi, Mohamed; Salama, Khaled N

    2015-07-24

    A prototypical metal-organic framework (MOF), a 2D periodic porous structure based on the assembly of copper ions and benzene dicarboxylate (bdc) ligands (Cu(bdc)·xH2O), was grown successfully as a thin film on interdigitated electrodes (IDEs). IDEs have been used for achieving planar CMOS-compatible low-cost capacitive sensing structures for the detection of humidity and volatile organic compounds (VOCs). Accordingly, the resultant IDEs coated with the Cu(bdc)·xH2O thin film was evaluated, for the first time, as a capacitive sensor for gas sensing applications. A fully automated setup, using LabVIEW interfaces to experiment conduction and data acquisition, was developed in order to measure the associated gas sensing performance.

  7. Insights on Capacitive Interdigitated Electrodes Coated with MOF Thin Films: Humidity and VOCs Sensing as a Case Study

    Directory of Open Access Journals (Sweden)

    Christos Sapsanis

    2015-07-01

    Full Text Available A prototypical metal-organic framework (MOF, a 2D periodic porous structure based on the assembly of copper ions and benzene dicarboxylate (bdc ligands (Cu(bdc·xH2O, was grown successfully as a thin film on interdigitated electrodes (IDEs. IDEs have been used for achieving planar CMOS-compatible low-cost capacitive sensing structures for the detection of humidity and volatile organic compounds (VOCs. Accordingly, the resultant IDEs coated with the Cu(bdc·xH2O thin film was evaluated, for the first time, as a capacitive sensor for gas sensing applications. A fully automated setup, using LabVIEW interfaces to experiment conduction and data acquisition, was developed in order to measure the associated gas sensing performance.

  8. Heterogeneous nucleation for synthesis of sub-20nm ZnO nanopods and their application to optical humidity sensing.

    Science.gov (United States)

    Majithia, R; Ritter, S; Meissner, K E

    2014-02-17

    We present a novel method for colloidal synthesis of one-dimensional ZnO nanopods by heterogeneous nucleation on zero-dimensional ZnO nanoparticle 'seeds'. Ultra-small ZnO nanopods, multi-legged structures with sub-20 nm individual leg diameters, can be synthesized by hydrolysis of a Zn2+ precursor growth solution in presence of ∼4 nm ZnO seeds under hydrothermal conditions via microwave-assisted heating in as little as 20 min of reaction time. One-dimensional ZnO nanorods are initially generated in the reaction mixture by heterogeneous nucleation and growth along the [0001] direction of the ZnO crystal. Growth of one-dimensional nanorods subsequently yields to an 'attachment' and size-focusing phase where individual nanorods fuse together to form multi-legged nanopods having diameters ∼15 nm. ZnO nanopods exhibit broad orange-red defect-related photoluminescence in addition to a near-band edge emission at 373 nm when excited above the band-gap at 350 nm. The defect-related photoluminescence of the ZnO nanopods has been applied towards reversible optical humidity sensing at room temperature. The sensors demonstrated a linear response between 22% and 70% relative humidity with a 0.4% increase in optical intensity per % change in relative humidity. Due to their ultra-small dimensions, ZnO nanopods exhibit a large dynamic range and enhanced sensitivity to changes in ambient humidity, thus showcasing their ability as a platform for optical environmental sensing.

  9. Taxonomy and remote sensing of leaf mass per area (LMA) in humid tropical forests

    Science.gov (United States)

    Gregory P. Asner; Roberta E. Martin; Raul Tupayachi; Ruth Emerson; Paola Martinez; Felipe Sinca; George V.N. Powell; S. Joseph Wright; Ariel E. Lugo

    2011-01-01

    Leaf mass per area (LMA) is a trait of central importance to plant physiology and ecosystem function, but LMA patterns in the upper canopies of humid tropical forests have proved elusive due to tall species and high diversity. We collected top-of-canopy leaf samples from 2873 individuals in 57 sites spread across the Neotropics, Australasia, and Caribbean and Pacific...

  10. Humidity and temperature sensing properties of copper oxide-Si-adhesive nanocomposite.

    Science.gov (United States)

    Khan, Sher Bahadar; Chani, Muhammad Tariq Saeed; Karimov, Kh S; Asiri, Abdullah M; Bashir, Mehran; Tariq, Rana

    2014-03-01

    Smart and professional humidity and temperature sensors have been fabricated by utilizing copper oxide-Si-adhesive composite and pure copper oxide nanosheets. Copper oxide nanosheets are synthesized by low temperature stirring method and characterized by field emission scanning electron microscopy, which reveals that synthesized product is composed of randomly oriented nanosheets, which are grown in high density with an average thickness of~80±10 nm. X-ray diffraction confirms that the grown nanosheets consist of well crystalline monoclinic CuO. X-ray photoelectron spectroscopy and Fourier transform infrared (FTIR) spectroscopy also confirm that the synthesized nanomaterial is pure CuO without any impurity. The fabricated sensors exhibit good temperature sensitivity of -4.0%/°C and -5.2%/°C and humidity sensitivity of -2.9%/%RH and -4.88%/%RH, respectively for copper oxide-Si-adhesive composite and pure copper oxide nanosheets. The average initial resistance of the sensors is equal to 250 MΩ and 55 MΩ for the composite and pure copper oxide based sensors, respectively.

  11. Nano-Anatase TiO2 for High Performance Optical Humidity Sensing on Chip

    Directory of Open Access Journals (Sweden)

    Mahdiar Ghadiry

    2015-12-01

    Full Text Available An on-chip optical humidity sensor using Nano-anatase TiO2 coating is presented here. The coating material was prepared so that the result is in solution form, making the fabrication process quick and simple. Then, the solution was effortlessly spin-coated on an SU8 straight channel waveguide. Investigating the sensitivity and performance (response time of the device revealed a great linearity in the wide range (35% to 98% of relative humidity (RH. In addition, a variation of more than 14 dB in transmitted optical power was observed, with a response time of only ~0.7 s. The effect of coating concentration and UV treatment was examined on the performance and repeatability of the sensor. Interesting observations were found, and the attributed mechanisms were described. In addition, the proposed sensor was extensively compared with other state-of-the-art proposed counterparts from the literature and remarkable advantages were found. Since a high sensitivity of ~0.21 dB/%RH and high dynamic performances were demonstrated, this sensor is proposed for use in biomedical applications.

  12. Thin films of In2O3/SiO for Humidity Sensing Applications

    Directory of Open Access Journals (Sweden)

    K. Twomey

    2002-06-01

    Full Text Available This paper documents the manufacture and testing of a humidity sensor based on a combination of In2O3/SiO. A number of different sensor samples have been produced by thermal deposition and the effect of varying the vacuum pressure has also been investigated. The AC and DC conduction mechanisms have been investigated. From the AC conduction studies, the tunneling conduction mechanism has been observed at low frequencies and the hopping conduction mechanism, for the majority of sensor samples, has been observed at high frequencies. The DC conduction mechanisms have indicated the possibility of spacecharge-limited conduction. The sensor with the highest humidity sensitivity of 1.145%/RH% is 85%In2O3/15%SiO, which is produced at a vacuum pressure of 2×10-4 mbar.From the point of view of temperature stability, the 55%In2O3/45%SiO samples produced at a vacuum pressure of 2×10-4 mbar exhibit the lowest temperature sensitivity, 0.3%/oC.

  13. Towards retrieving critical relative humidity from ground-based remote sensing observations

    Energy Technology Data Exchange (ETDEWEB)

    Van Weverberg, Kwinten; Boutle, Ian; Morcrette, Cyril J.; Newsom, Rob K.

    2016-08-22

    Nearly all parameterisations of large-scale cloud require the specification of the critical relative humidity (RHcrit). This is the gridbox-mean relative humidity at which the subgrid fluctuations in temperature and water vapour become so large that part of a subsaturated gridbox becomes saturated and cloud starts to form. Until recently, the lack of high-resolution observations of temperature and moisture variability has hindered a reasonable estimate of the RHcrit from observations. However, with the advent of ground-based measurements from Raman lidar, it becomes possible to obtain long records of temperature and moisture (co-)variances with sub-minute sample rates. Lidar observations are inherently noisy and any analysis of higher-order moments will be very dependent on the ability to quantify and remove this noise. We present an exporatory study aimed at understanding whether current noise levels of lidar-retrieved temperature and water vapour are sufficient to obtain a reasonable estimate of the RHcrit. We show that vertical profiles of RHcrit can be derived for a gridbox length of up to about 30 km (120) with an uncertainty of about 4 % (2 %). RHcrit tends to be smallest near the scale height and seems to be fairly insensitive to the horizontal grid spacing at the scales investigated here (30 - 120 km). However, larger sensitivity was found to the vertical grid spacing. As the grid spacing decreases from 400 to 100 m, RHcrit is observed to increase by about 6 %, which is more than the uncertainty in the RHcrit retrievals.

  14. Humidity sensing properties of WO{sub 3} thick film resistor prepared by screen printing technique

    Energy Technology Data Exchange (ETDEWEB)

    Garde, Arun S, E-mail: arungarde@yahoo.co.in

    2014-12-25

    Highlights: • Polycrystalline WO{sub 3} Thick films are fabricated by screen printing technique. • Monoclinic phases were the majority in formation of films. • The peak at 1643 cm{sup −1} shows stretching vibrations attributed to W-OH of adsorbed H{sub 2}O. • Absorption peaks in the range 879–650 cm{sup −1} are attributed to the stretching W-O-W bonds. • Increase in resistance with decrease in RH when exposed to 20–100% RH. - Abstract: Thick films of tungsten oxide based were prepared using standard screen printing technique. To study the effect of temperature on the thick films were fired at different temperature for 30 min in air atmosphere. The WO{sub 3} thick films were characterized with X-ray diffraction, scanning electron microscopy and EDAX for elemental analysis. The formation of mixed phases of the film together with majority of monoclinic phase was observed. IR spectra confirm the peak at 1643 cm{sup −1} clearly shows stretching vibrations attributed to the W-OH bending vibration mode of the adsorbed water molecules. The absorption peaks in the range 879–650 cm{sup −1} are attributed to the stretching W-O-W bonds (i.e. ν [W-O{sub inter}-W]). The peak located at 983 cm{sup −1} belong to W=O terminal of cluster boundaries. A change in the resistance was observed with respect to the relative humidity when the WO{sub 3} thick films were exposed to a wide humidity range of 20–100%. An increasing firing temperature of WO{sub 3} film increases with the sensitivity. The parameters such as sensitivity and hysteresis of the WO{sub 3} film sensors have been evaluated.

  15. Combining interior and exterior characteristics for remote sensing image denoising

    Science.gov (United States)

    Peng, Ni; Sun, Shujin; Wang, Runsheng; Zhong, Ping

    2016-04-01

    Remote sensing image denoising faces many challenges since a remote sensing image usually covers a wide area and thus contains complex contents. Using the patch-based statistical characteristics is a flexible method to improve the denoising performance. There are usually two kinds of statistical characteristics available: interior and exterior characteristics. Different statistical characteristics have their own strengths to restore specific image contents. Combining different statistical characteristics to use their strengths together may have the potential to improve denoising results. This work proposes a method combining statistical characteristics to adaptively select statistical characteristics for different image contents. The proposed approach is implemented through a new characteristics selection criterion learned over training data. Moreover, with the proposed combination method, this work develops a denoising algorithm for remote sensing images. Experimental results show that our method can make full use of the advantages of interior and exterior characteristics for different image contents and thus improve the denoising performance.

  16. Polyimide Humidity Integrated Sensor Fabricated Using the MEMS Process

    Institute of Scientific and Technical Information of China (English)

    Dianzhong Wen

    2006-01-01

    This paper reports on the fabrication and sensing characteristics of Polyimide-based humidity sensor, based on that, a new integrated circuit of humidity measurement has been designed. It is a novel capacitive-type systems on a chip structure using the MEMS process. The results show that the new sensor presents sensing characteristics over a humidity range from 10%~70% RH at 20℃, and the sensor is able to fabricated together with Ics technology. The result shows that integration of humidity sensor with integrated circuit of humidity measurement is considerably easier when they are built in sensing groove. The appeal of a new structure like this brings the possibility of applications that would require the flexibility of simple screen printing.

  17. From the Solution Processing of Hydrophilic Molecules to Polymer-Phthalocyanine Hybrid Materials for Ammonia Sensing in High Humidity Atmospheres

    Science.gov (United States)

    Gaudillat, Pierre; Jurin, Florian; Lakard, Boris; Buron, Cédric; Suisse, Jean-Moïse; Bouvet, Marcel

    2014-01-01

    We have prepared different hybrid polymer-phthalocyanine materials by solution processing, starting from two sulfonated phthalocyanines, s-CoPc and CuTsPc, and polyvinylpyrrolidone (PVP), polyethylene glycol (PEG), poly(acrylic acid-co-acrylamide) (PAA-AM), poly(diallyldimethylammonium chloride) (PDDA) and polyaniline (PANI) as polymers. We also studied the response to ammonia (NH3) of resistors prepared from these sensing materials. The solvent casted films, prepared from s-CoPc and PVP, PEG and PAA-AM, were highly insulating and very sensitive to the relative humidity (RH) variation. The incorporation of s-CoPc in PDDA by means of layer-by-layer (LBL) technique allowed to stabilize the film, but was too insulating to be interesting. We also prepared PANI-CuTsPc hybrid films by LBL technique. It allowed a regular deposition as evidenced by the linear increase of the absorbance at 688 nm as a function of the number of bilayers. The sensitivity to ammonia (NH3) of PANi-CuTsPc resistors was very high compared to that of individual materials, giving up to 80% of current decrease when exposed to 30 ppm NH3. Contrarily to what happens with neutral polymers, in PANI, CuTsPc was stabilized by strong electrostatic interactions, leading to a stable response to NH3, whatever the relative humidity in the range 10%–70%. Thus, the synergy of PANI with ionic macrocycles used as counteranions combined with their simple aqueous solution processing opens the way to the development of new gas sensors capable of operating in real world conditions. PMID:25061841

  18. From the solution processing of hydrophilic molecules to polymer-phthalocyanine hybrid materials for ammonia sensing in high humidity atmospheres.

    Science.gov (United States)

    Gaudillat, Pierre; Jurin, Florian; Lakard, Boris; Buron, Cédric; Suisse, Jean-Moïse; Bouvet, Marcel

    2014-07-24

    We have prepared different hybrid polymer-phthalocyanine materials by solution processing, starting from two sulfonated phthalocyanines, s-CoPc and CuTsPc, and polyvinylpyrrolidone (PVP), polyethylene glycol (PEG), poly(acrylic acid-co-acrylamide) (PAA-AM), poly(diallyldimethylammonium chloride) (PDDA) and polyaniline (PANI) as polymers. We also studied the response to ammonia (NH3) of resistors prepared from these sensing materials. The solvent casted films, prepared from s-CoPc and PVP, PEG and PAA-AM, were highly insulating and very sensitive to the relative humidity (RH) variation. The incorporation of s-CoPc in PDDA by means of layer-by-layer (LBL) technique allowed to stabilize the film, but was too insulating to be interesting. We also prepared PANI-CuTsPc hybrid films by LBL technique. It allowed a regular deposition as evidenced by the linear increase of the absorbance at 688 nm as a function of the number of bilayers. The sensitivity to ammonia (NH3) of PANi-CuTsPc resistors was very high compared to that of individual materials, giving up to 80% of current decrease when exposed to 30 ppm NH3. Contrarily to what happens with neutral polymers, in PANI, CuTsPc was stabilized by strong electrostatic interactions, leading to a stable response to NH3, whatever the relative humidity in the range 10%-70%. Thus, the synergy of PANI with ionic macrocycles used as counteranions combined with their simple aqueous solution processing opens the way to the development of new gas sensors capable of operating in real world conditions.

  19. From the Solution Processing of Hydrophilic Molecules to Polymer-Phthalocyanine Hybrid Materials for Ammonia Sensing in High Humidity Atmospheres

    Directory of Open Access Journals (Sweden)

    Pierre Gaudillat

    2014-07-01

    Full Text Available We have prepared different hybrid polymer-phthalocyanine materials by solution processing, starting from two sulfonated phthalocyanines, s-CoPc and CuTsPc, and polyvinylpyrrolidone (PVP, polyethylene glycol (PEG, poly(acrylic acid-co-acrylamide (PAA-AM, poly(diallyldimethylammonium chloride (PDDA and polyaniline (PANI as polymers. We also studied the response to ammonia (NH3 of resistors prepared from these sensing materials. The solvent casted films, prepared from s-CoPc and PVP, PEG and PAA-AM, were highly insulating and very sensitive to the relative humidity (RH variation. The incorporation of s-CoPc in PDDA by means of layer-by-layer (LBL technique allowed to stabilize the film, but was too insulating to be interesting. We also prepared PANI-CuTsPc hybrid films by LBL technique. It allowed a regular deposition as evidenced by the linear increase of the absorbance at 688 nm as a function of the number of bilayers. The sensitivity to ammonia (NH3 of PANi-CuTsPc resistors was very high compared to that of individual materials, giving up to 80% of current decrease when exposed to 30 ppm NH3. Contrarily to what happens with neutral polymers, in PANI, CuTsPc was stabilized by strong electrostatic interactions, leading to a stable response to NH3, whatever the relative humidity in the range 10%–70%. Thus, the synergy of PANI with ionic macrocycles used as counteranions combined with their simple aqueous solution processing opens the way to the development of new gas sensors capable of operating in real world conditions.

  20. EDITORIAL: Humidity sensors Humidity sensors

    Science.gov (United States)

    Regtien, Paul P. L.

    2012-01-01

    All matter is more or less hygroscopic. The moisture content varies with vapour concentration of the surrounding air and, as a consequence, most material properties change with humidity. Mechanical and thermal properties of many materials, such as the tensile strength of adhesives, stiffness of plastics, stoutness of building and packaging materials or the thermal resistivity of isolation materials, all decrease with increasing environmental humidity or cyclic humidity changes. The presence of water vapour may have a detrimental influence on many electrical constructions and systems exposed to humid air, from high-power systems to microcircuits. Water vapour penetrates through coatings, cable insulations and integrated-circuit packages, exerting a fatal influence on the performance of the enclosed systems. For these and many other applications, knowledge of the relationship between moisture content or humidity and material properties or system behaviour is indispensable. This requires hygrometers for process control or test and calibration chambers with high accuracy in the appropriate temperature and humidity range. Humidity measurement methods can roughly be categorized into four groups: water vapour removal (the mass before and after removal is measured); saturation (the air is brought to saturation and the `effort' to reach that state is measured); humidity-dependent parameters (measurement of properties of humid air with a known relation between a specific property and the vapour content, for instance the refractive index, electromagnetic spectrum and acoustic velocity); and absorption (based on the known relation between characteristic properties of non-hydrophobic materials and the amount of absorbed water from the gas to which these materials are exposed). The many basic principles to measure air humidity are described in, for instance, the extensive compilations by Wexler [1] and Sonntag [2]. Absorption-type hygrometers have small dimensions and can be

  1. Humidity sensing properties of different single-walled carbon nanotube composite films fabricated by layer-by-layer self-assembly technique

    Science.gov (United States)

    Jing, Hongjun; Jiang, Yadong; Du, Xiaosong; Tai, Huiling; Xie, Guangzhong

    2012-10-01

    Poly(diallyldimethylammonium chloride)/single-walled carbon nanotube (PDDA/SWNT) multilayered thin films were prepared on quartz crystal microbalance by layer-by-layer self-assembly technique, and their sensing properties to humidity were studied. The SWNTs were characterized by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The composite films were observed by field-emission scanning electron microscope. Two types of SWNT humidity sensors were fabricated using SWNTs and carboxyl (COOH) modified SWNTs as sensitive material, respectively. The results showed that the sensitivity of the PDDA/SWNT-COOH humidity sensor was 20.23 % higher than that of the PDDA/SWNT sensor. In contrast, the latter had a much superior hysteresis property, and the reason to cause this phenomenon was discussed.

  2. Humidity Sensing Properties of Paper Substrates and Their Passivation with ZnO Nanoparticles for Sensor Applications

    Science.gov (United States)

    Niarchos, Georgios; Dubourg, Georges; Afroudakis, Georgios; Georgopoulos, Markos; Tsouti, Vasiliki; Makarona, Eleni; Crnojevic-Bengin, Vesna; Tsamis, Christos

    2017-01-01

    In this paper, we investigated the effect of humidity on paper substrates and propose a simple and low-cost method for their passivation using ZnO nanoparticles. To this end, we built paper-based microdevices based on an interdigitated electrode (IDE) configuration by means of a mask-less laser patterning method on simple commercial printing papers. Initial resistive measurements indicate that a paper substrate with a porous surface can be used as a cost-effective, sensitive and disposable humidity sensor in the 20% to 70% relative humidity (RH) range. Successive spin-coated layers of ZnO nanoparticles then, control the effect of humidity. Using this approach, the sensors become passive to relative humidity changes, paving the way to the development of ZnO-based gas sensors on paper substrates insensitive to humidity. PMID:28273847

  3. Cultivar Differences in the Stomatal Characteristics of Cut Roses Grown at High Relative Humidity

    NARCIS (Netherlands)

    Fanourakis, D.; Tapia, A.; Heuvelink, E.; Pinto De Carvalho, S.M.

    2009-01-01

    High relative air humidity (RH>85%) during cultivation is known to reduce the vase life of cut roses, but the magnitude of such effect is cultivar dependent. The reasons behind this genotypic variation are not yet known. In this study, the stomatal density and stomatal responses to two closing

  4. Stomatal response characteristics as affected by long-term elevated humidity levels

    NARCIS (Netherlands)

    Fanourakis, D.

    2011-01-01

    Restriction of leaf water loss, by stomatal closure, is decisive for plant survival, especially under conditions of water deficit. This sensitivity of stomata to low water potential is attenuated by high relative air humidity (RH ≥ 85%) during growth, which impedes the plant’s ability to

  5. Nanomechanical humidity detection through porous alumina cantilevers

    Directory of Open Access Journals (Sweden)

    Olga Boytsova

    2015-06-01

    Full Text Available We present here the behavior of the resonance frequency of porous anodic alumina cantilever arrays during water vapor adsorption and emphasize their possible use in the micromechanical sensing of humidity levels at least in the range of 10–22%. The sensitivity of porous anodic aluminium oxide cantilevers (Δf/Δm and the humidity sensitivity equal about 56 Hz/pg and about 100 Hz/%, respectively. The approach presented here for the design of anodic alumina cantilever arrays by the combination of anodic oxidation and photolithography enables easy control over porosity, surface area, geometric and mechanical characteristics of the cantilever arrays for micromechanical sensing.

  6. Analysis of the electrical characteristic of linseed oil films exposed to humidity

    Science.gov (United States)

    Palummo, Lucrezia; Bearzotti, Andrea

    2009-12-01

    Linseed oil is a material widely used in various applications as a protecting layer for surfaces in industry, in scientific research, for medical use, and finally for artistic purpose. This natural origins substance has a particular application as a protective and smoothing layer on phenolic-melaminic laminate electrodes on Resistive Plate Chamber (RPC) detectors used in various particle physic experiments. In such electronic applications where linseed oil could be exposed to water vapours, an electrical characterization should result useful for having an overall control of the process involving the oil. In this paper, we studied the electrical behaviour towards relative humidity variations of linseed oil films deposited on interdigitated metal electrodes. Moreover, I/V characterisation both in air and vacuum, current vs. temperature and relative humidity was performed.

  7. The Sensing of Humidity by Surface-Type Ag/FORMYL-TIPPCu(II)/Ag Sensor for Environmental Monitoring

    Science.gov (United States)

    Khan, Dil Nawaz; Sayyad, Muhammad Hassan; Tahir, Muhammad; Wahab, Fazal; Yaseen, Muhammad; Ali, Mukhtar; Munawar, Munawar Ali

    2014-06-01

    In this paper, we have studied the effects of changing relative humidity on the electrical parameters and their multi frequency response of the surface type Ag/formyl-TIPPCu(II)/Ag humidity sensors. The silver electrodes of thickness 100 nm were primarily deposited on cleaned glass substrates by thermal evaporator. A gap of 40 μm was created between the electrodes of each device by using mask during the evaporation process. Thin films of formyl-TIPPCu(II) of 140 nm thickness were grown on silver electrodes by thermal sublimation technique. The values of capacitance and resistance of the sensors were found at different humidity levels at frequency of 1, 10 and 100 kHz of AC input signal. A remarkable increase in capacitance and decrease in resistance were observed during the rise of relative humidity from 45% to 95% RH. The hysteresis response of these humidity sensors was also studied at 1 kHz AC signal.

  8. Characteristics of Temperature and Humidity Inversions and Low-Level Jets over Svalbard Fjords in Spring

    Directory of Open Access Journals (Sweden)

    Timo Vihma

    2011-01-01

    Full Text Available Air temperature and specific humidity inversions and low-level jets were studied over two Svalbard fjords, Isfjorden and Kongsfjorden, applying three tethersonde systems. Tethersonde operation practices notably affected observations on inversion and jet properties. The inversion strength and depth were strongly affected by weather conditions at the 850 hPa level. Strong inversions were deep with a highly elevated base, and the strongest ones occurred in warm air mass. Unexpectedly, downward longwave radiation measured at the sounding site did not correlate with the inversion properties. Temperature inversions had lower base and top heights than humidity inversions, the former due to surface cooling and the latter due to adiabatic cooling with height. Most low-level jets were related to katabatic winds. Over the ice-covered Kongsfjorden, jets were lifted above a cold-air pool on the fjord; the jet core was located highest when the snow surface was coldest. At the ice-free Isfjorden, jets were located lower.

  9. Sensing characteristics of birefringent microstructured polymer optical fiber

    DEFF Research Database (Denmark)

    Szczurowski, Marcin K.; Frazao, Orlando; Baptista, J. M.;

    2011-01-01

    We experimentally studied several sensing characteristics of a birefringent microstructured polymer optical fiber. The fiber exhibits a birefringence of the order 2×10-5 at 1.3 μm because of two small holes adjacent to the core. In this fiber, we measured spectral dependence of phase and group mo...

  10. Sensing characteristics of birefringent microstructured polymer optical fiber

    DEFF Research Database (Denmark)

    Szczurowski, Marcin K.; Frazao, Orlando; Baptista, J. M.

    2011-01-01

    We experimentally studied several sensing characteristics of a birefringent microstructured polymer optical fiber. The fiber exhibits a birefringence of the order 2×10-5 at 1.3 μm because of two small holes adjacent to the core. In this fiber, we measured spectral dependence of phase and group mo...

  11. Influence of Ce(III/Ce(IV - supplements on the Characteristics of Humidity Sensors with TiO2 Films Prepared via a Sol-gel Method

    Directory of Open Access Journals (Sweden)

    Kozhukharov, S.

    2013-04-01

    Full Text Available Humidity sensors have been prepared via a sol-gel method to deposit TiO2 films with additions of Ce-compounds on alumina substrates, with interdigitated silver palladium electrodes. Observations by scanning electron microscopy (SEM were performed in order to determine the surface morphology of the respective layers. Structural and compositional characterization was done by X-ray diffraction analysis (XRD, and energy dispersive X-ray spectroscopy (EDX for investigation of the relation between the film structures and the parameters of the respective sensors. The influence of Ce-compounds on the electrical characteristics of the samples as humidity sensing elements has been evaluated by an impedance analyzer.Los sensores de humedad han sido desarrollados mediante el método sol-gel para depositar películas superficiales basadas en TiO2 con adiciones de compuestos de cerio sobre sustratos de corindón y electrodos de aleación de plata y paladio. Se han realizado observaciones mediante el Microscopio Electrónico de Barrido (MEB para determinar la morfología superficial de las capas respectivas. Las caracterizaciones de la estructura y composición han sido realizadas mediante Difracción de Rayos X (DRX y espectroscopía de dispersión energética de rayos X (EDERX, con el fin de investigar la relación entre la estructura de las capas y los parámetros de los sensores respectivos. La influencia de los compuestos de cerio sobre las características eléctricas de los sensores de humedad obtenidos se ha evaluado mediante el análisis de impedancia eléctrica.

  12. 碳湿敏膜的非线性感湿特性和导电机理%The nonlinear sensing property and electric mechanism of carbon humidity-sensitive membranes

    Institute of Scientific and Technical Information of China (English)

    陈环; 彭振康; 傅刚

    2009-01-01

    采用羟乙基纤维素(HEC)和导电炭黑并添加山梨醇增湿剂制备碳湿敏膜,研究了膜在偏离结露区的非线性感湿特性和导电机理.扫描电镜脱测到,膜中炭黑粒子形成网链状的空问导电结构;2%炭黑含量使膜的导电通路处于渗流区,膜电阻在80%RH附近对湿度有较强的非线性特件.分析I-V曲线认为,是导电网链中炭黑粒子的间距使膜电阻对湿度变化和测量电压的变化都非常敏感,非线性感湿特性与导电机理密切相关.复阻抗谱表明,碳湿敏样品在33%RH时只出现与炭黑体电阻有关的半圆弧,在80%RH时出现与炭黑粒界电阻有关的第二个半圆弧,92%RH时的复阻抗谱是以上两个半圆弧外加接近45°角的拖尾,拖尾部分对应膜与电极之间水分子引起的极化作用.%The nonlinear sensing property and electric mechanism of carbon humidity-sensitive membranes under investigation were manufactured by using hydroxyethyl cellulose (HEC), carbon black (CB) and humidizer sorbitol. Microstructures examined by scanning electronic microscopy (SEM) show that, an effective carbon black electric network in humidity-sensing membrane would make the membrane' s resistance to have strong nonlinear property near 80% RH; so that the amount of 2wt% carbon black is in the proximity of the electric percolation threshold. The voltage-current characteristic suggested that the nonlinear sensing property and electric mechanism of the carbon humidity membranes are closely related. Particularly, impedance spectroscopy of sample at 92% RH was made up by two semi-circular arcs and a straight tail near 45° angle. The membrane's equivalent circuit was three RC circuits in series that corresponds to the contributions of the carbon bulk resistance, CB-grain-boundary resistance and electrode contact resistance, respectively.

  13. Investigating soil water retention characteristics at high suctions using relative humidity control

    Directory of Open Access Journals (Sweden)

    Mantikos Vasileios

    2016-01-01

    Full Text Available A technique for controlling relative humidity (RH is presented, which involves supplying a sealed chamber with a continuous flow of air at a computer-regulated RH. The desired value of RH is achieved by mixing dry and wet air at appropriate volumes and is measured for servo-control at three locations in the chamber with capacitive RH sensors and checked with a sensitive VAISALA sensor. The setup is capable of controlling RH steadily and continuously with a deviation of less than 0.2% RH. The technique was adopted to determine wetting soil-water retention curves (SWRC of statically compacted London Clay, under both free-swelling and constant volume conditions. The RH within the chamber was increased in a step-wise fashion, with each step maintained until vapour equilibrium between the chamber atmosphere and the soil samples was established. Independent filter paper measurements further validate the method, while the obtained retention curves complement those available in the literature for lower ranges of suction.

  14. Chemo-Mechanical Characteristics of Mud Formed from Environmental Dust Particles in Humid Ambient Air

    Science.gov (United States)

    Hassan, Ghassan; Yilbas, B. S.; Said, Syed A. M.; Al-Aqeeli, N.; Matin, Asif

    2016-07-01

    Mud formed from environmental dust particles in humid ambient air significantly influences the performance of solar harvesting devices. This study examines the characterization of environmental dust particles and the chemo-mechanics of dry mud formed from dust particles. Analytical tools, including scanning electron microscopy, atomic force microscopy, energy dispersive spectroscopy, particle sizing, and X-ray diffraction, are used to characterize dry mud and dust particles. A micro/nano tribometer is used to measure the tangential force and friction coefficient while tensile tests are carried out to assess the binding forces of dry mud pellets. After dry mud is removed, mud residuals on the glass surface are examined and the optical transmittance of the glass is measured. Dust particles include alkaline compounds, which dissolve in water condensate and form a mud solution with high pH (pH = 7.5). The mud solution forms a thin liquid film at the interface of dust particles and surface. Crystals form as the mud solution dries, thus, increasing the adhesion work required to remove dry mud from the surface. Optical transmittance of the glass is reduced after dry mud is removed due to the dry mud residue on the surface.

  15. Humid tropical forest clearing from 2000 to 2005 quantified by using multitemporal and multiresolution remotely sensed data

    Science.gov (United States)

    Hansen, M.C.; Stehman, S.V.; Potapov, P.V.; Loveland, T.R.; Townshend, J.R.G.; DeFries, R.S.; Pittman, K.W.; Arunarwati, B.; Stolle, F.; Steininger, M.K.; Carroll, M.; DiMiceli, C.

    2008-01-01

    Forest cover is an important input variable for assessing changes to carbon stocks, climate and hydrological systems, biodiversity richness, and other sustainability science disciplines. Despite incremental improvements in our ability to quantify rates of forest clearing, there is still no definitive understanding on global trends. Without timely and accurate forest monitoring methods, policy responses will be uninformed concerning the most basic facts of forest cover change. Results of a feasible and cost-effective monitoring strategy are presented that enable timely, precise, and internally consistent estimates of forest clearing within the humid tropics. A probability-based sampling approach that synergistically employs low and high spatial resolution satellite datasets was used to quantify humid tropical forest clearing from 2000 to 2005. Forest clearing is estimated to be 1.39% (SE 0.084%) of the total biome area. This translates to an estimated forest area cleared of 27.2 million hectares (SE 2.28 million hectares), and represents a 2.36% reduction in area of humid tropical forest. Fifty-five percent of total biome clearing occurs within only 6% of the biome area, emphasizing the presence of forest clearing 'hotspots.' Forest loss in Brazil accounts for 47.8% of total biome clearing, nearly four times that of the next highest country, Indonesia, which accounts for 12.8%. Over three-fifths of clearing occurs in Latin America and over one-third in Asia. Africa contributes 5.4% to the estimated loss of humid tropical forest cover, reflecting the absence of current agro-industrial scale clearing in humid tropical Africa. ?? 2008 by The National Academy of Sciences of the USA.

  16. Humid tropical forest clearing from 2000 to 2005 quantified by using multitemporal and multiresolution remotely sensed data.

    Science.gov (United States)

    Hansen, Matthew C; Stehman, Stephen V; Potapov, Peter V; Loveland, Thomas R; Townshend, John R G; DeFries, Ruth S; Pittman, Kyle W; Arunarwati, Belinda; Stolle, Fred; Steininger, Marc K; Carroll, Mark; Dimiceli, Charlene

    2008-07-08

    Forest cover is an important input variable for assessing changes to carbon stocks, climate and hydrological systems, biodiversity richness, and other sustainability science disciplines. Despite incremental improvements in our ability to quantify rates of forest clearing, there is still no definitive understanding on global trends. Without timely and accurate forest monitoring methods, policy responses will be uninformed concerning the most basic facts of forest cover change. Results of a feasible and cost-effective monitoring strategy are presented that enable timely, precise, and internally consistent estimates of forest clearing within the humid tropics. A probability-based sampling approach that synergistically employs low and high spatial resolution satellite datasets was used to quantify humid tropical forest clearing from 2000 to 2005. Forest clearing is estimated to be 1.39% (SE 0.084%) of the total biome area. This translates to an estimated forest area cleared of 27.2 million hectares (SE 2.28 million hectares), and represents a 2.36% reduction in area of humid tropical forest. Fifty-five percent of total biome clearing occurs within only 6% of the biome area, emphasizing the presence of forest clearing "hotspots." Forest loss in Brazil accounts for 47.8% of total biome clearing, nearly four times that of the next highest country, Indonesia, which accounts for 12.8%. Over three-fifths of clearing occurs in Latin America and over one-third in Asia. Africa contributes 5.4% to the estimated loss of humid tropical forest cover, reflecting the absence of current agro-industrial scale clearing in humid tropical Africa.

  17. Field Sensing Characteristic Research of Carbon Fiber Smart Material

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xiaoyu; Lü Yong; CHEN Jianzhong; LI Zhuoqiu

    2015-01-01

    In order to research the field sensing characteristic of the carbon fiber smart material, the Tikhonov regularization principle and the modiifed Newton-Raphson(MNR) algorithm were adopted to solve the inverse problem of the electrical resistance tomography (ERT). An ERT system of carbon fiber smart material was developed. Field sensing characteristic was researched with the experiment. The experimental results show that the speciifc resistance distribution of carbon ifber smart material is highly consistent with the distribution of structural strain. High resistance zone responds to high strain area, and the speciifc resistance distribution of carbon ifber smart material relfects the distribution of sample strain in covering area. Monitoring by carbon ifber smart material on complicated strain status in sample ifeld domain is realized through theoretical and experimental study.

  18. Synthesis of γ-WO{sub 3} thin films by hot wire-CVD and investigation of its humidity sensing properties

    Energy Technology Data Exchange (ETDEWEB)

    Jadkar, Vijaya; Waykar, Ravindra; Jadhavar, Ashok [School of Energy Studies, Savitribai Phule Pune University, Pune 411 007 (India); Pawbake, Amit [School of Energy Studies, Savitribai Phule Pune University, Pune 411 007 (India); Physical and Material Chemistry Division, National Chemical Laboratory, Pune 411 008 (India); Date, Abhijit [School of Aerospace, Mechanical and Manufacturing Engineering, RMIT University, Plenty Road, Bundoora, Melbourne VIC 3083 (Australia); Late, Dattatray [Physical and Material Chemistry Division, National Chemical Laboratory, Pune 411 008 (India); Pathan, Habib; Gosavi, Suresh; Jadkar, Sandesh [Department of Physics, Savitribai Phule Pune University, Pune 411 007 (India)

    2017-05-15

    In this study, monoclinic tungsten oxide (γ-WO{sub 3}) have been grown in a single step using HW-CVD method by resistively heating W filaments in a constant O{sub 2} pressure. The formation of γ-WO{sub 3} was confirmed using low angle-XRD and Raman spectroscopy analysis. Low angle-XRD analysis revealed that as-deposited WO{sub 3} film are highly crystalline and the crystallites have preferred orientation along the (002) direction. HRTEM analysis and SAED pattern also show the highly crystalline nature of WO{sub 3} with d spacing of ∝ 0.38 nm, having an orientation along the (002) direction. Surface topography investigated by SEM analysis shows the formation of a uniform and homogeneous cauliflower like morphology throughout the substrate surface without flaws and cracks. A humidity sensing device incorporating WO{sub 3} is also fabricated, which shows a maximum humidity sensitivity factor of ∝ 3954% along with a response time of ∝14 s and a recovery time of ∝25 s. The obtained results demonstrate that it is possible to synthesize WO{sub 3} in a single step by HW-CVD method and to fabricate a humidity sensor by using it. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  19. Temperature and relative humidity influence the microbial and physicochemical characteristics of Camembert-type cheese ripening.

    Science.gov (United States)

    Leclercq-Perlat, M-N; Sicard, M; Trelea, I C; Picque, D; Corrieu, G

    2012-08-01

    To evaluate the effects of temperature and relative humidity (RH) on microbial and biochemical ripening kinetics, Camembert-type cheeses were prepared from pasteurized milk seeded with Kluyveromyces marxianus, Geotrichum candidum, Penicillium camemberti, and Brevibacterium aurantiacum. Microorganism growth and biochemical changes were studied under different ripening temperatures (8, 12, and 16°C) and RH (88, 92, and 98%). The central point runs (12°C, 92% RH) were both reproducible and repeatable, and for each microbial and biochemical parameter, 2 kinetic descriptors were defined. Temperature had significant effects on the growth of both K. marxianus and G. candidum, whereas RH did not affect it. Regardless of the temperature, at 98% RH the specific growth rate of P. camemberti spores was significantly higher [between 2 (8°C) and 106 times (16°C) higher]. However, at 16°C, the appearance of the rind was no longer suitable because mycelia were damaged. Brevibacterium aurantiacum growth depended on both temperature and RH. At 8°C under 88% RH, its growth was restricted (1.3 × 10(7) cfu/g), whereas at 16°C and 98% RH, its growth was favored, reaching 7.9 × 10(9) cfu/g, but the rind had a dark brown color after d 20. Temperature had a significant effect on carbon substrate consumption rates in the core as well as in the rind. In the rind, when temperature was 16°C rather than 8°C, the lactate consumption rate was approximately 2.9 times higher under 88% RH. Whatever the RH, temperature significantly affected the increase in rind pH (from 4.6 to 7.7 ± 0.2). At 8°C, an increase in rind pH was observed between d 6 and 9, whereas at 16°C, it was between d 2 and 3. Temperature and RH affected the increasing rate of the underrind thickness: at 16°C, half of the cheese thickness appeared ripened on d 14 (wrapping day). However, at 98% RH, the underrind was runny. In conclusion, some descriptors, such as yeast growth and the pH in the rind, depended solely on

  20. Poly(vinyl alcohol) reinforced and toughened with poly(dopamine)-treated graphene oxide, and its use for humidity sensing.

    Science.gov (United States)

    Hwang, Sang-Ha; Kang, Dongwoo; Ruoff, Rodney S; Shin, Hyeon Suk; Park, Young-Bin

    2014-07-22

    Poly(dopamine)-treated graphene oxide/poly(vinyl alcohol) ("dG-O/PVA") composite films were made and characterized. G-O was modified with poly(dopamine) in aqueous solution and then chemically reduced to yield poly(dopamine)-treated reduced G-O. A combination of hydrogen bonding, strong adhesion of poly(dopamine) at the interface of PVA and G-O sheets, and reinforcement by G-O resulted in increases in tensile modulus, ultimate tensile strength, and strain-to-failure by 39, 100, and 89%, respectively, at 0.5 wt % dG-O loading of the PVA. The dG-O serves as a moisture barrier for water-soluble PVA, and the dG-O/PVA composite films were shown to be effective humidity sensors over the relative humidity range 40-100%.

  1. Humidity sensing using vertically oriented arrays of ReS2 nanosheets deposited on an interdigitated gold electrode

    Science.gov (United States)

    Yang, Aijun; Gao, Jian; Li, Baichang; Tan, Jiawei; Xiang, Yu; Gupta, Tushar; Li, Lu; Suresh, Shravan; Idrobo, Juan Carlos; Lu, Toh-Ming; Rong, Mingzhe; Koratkar, Nikhil

    2016-12-01

    We report a novel humidity sensor featuring vertically oriented arrays of ReS2 nanosheets grown on an interdigitated gold electrode by chemical vapor deposition. The vertical orientation of the nanosheets is important since it maximizes the exposed surface area for water adsorption/desorption. We find that the resistance of the ReS2 film decreases sensitively with increasing relative humidity, which we attribute to charge transfer from the absorbed H2O molecules to the n-doped ReS2 nanosheets. In addition to high sensitivity, the ReS2 sensors exhibit fast response/recovery time and excellent reversibility with minimal hysteresis. Moreover, our fabrication approach involving the direct (1-step) growth of the ReS2 films on an interdigitated electrode (without any transfer using wet chemistry or lithography) greatly simplifies the device architecture and has important practical benefits for the low-cost and scalable deployment of such sensor devices.

  2. Tropospheric profiles of wet refractivity and humidity from the combination of remote sensing data sets and measurements on the ground

    Directory of Open Access Journals (Sweden)

    F. Hurter

    2013-11-01

    Full Text Available We reconstruct atmospheric wet refractivity profiles for the western part of Switzerland with a least-squares collocation approach from data sets of (a zenith path delays that are a byproduct of the GPS (global positioning system processing, (b ground meteorological measurements, (c wet refractivity profiles from radio occultations whose tangent points lie within the study area, and (d radiosonde measurements. Wet refractivity is a parameter partly describing the propagation of electromagnetic waves and depends on the atmospheric parameters temperature and water vapour pressure. In addition, we have measurements of a lower V-band microwave radiometer at Payerne. It delivers temperature profiles at high temporal resolution, especially in the range from ground to 3000 m a.g.l., though vertical information content decreases with height. The temperature profiles together with the collocated wet refractivity profiles provide near-continuous dew point temperature or relative humidity profiles at Payerne for the study period from 2009 to 2011. In the validation of the humidity profiles, we adopt a two-step procedure. We first investigate the reconstruction quality of the wet refractivity profiles at the location of Payerne by comparing them to wet refractivity profiles computed from radiosonde profiles available for that location. We also assess the individual contributions of the data sets to the reconstruction quality and demonstrate a clear benefit from the data combination. Secondly, the accuracy of the conversion from wet refractivity to dew point temperature and relative humidity profiles with the radiometer temperature profiles is examined, comparing them also to radiosonde profiles. For the least-squares collocation solution combining GPS and ground meteorological measurements, we achieve the following error figures with respect to the radiosonde reference: maximum median offset of relative refractivity error is −16% and quartiles are 5% to

  3. Study on Porous Silicon with P-N Junction Sensor for Humidity Measurement

    Institute of Scientific and Technical Information of China (English)

    Chuzhe Tu; Zhenhong Jia

    2006-01-01

    Porous materials used for humidity sensing have been commercialized. In this paper, the preparation and humidity sensing characteristics of porous silicon with P-N junctions (PNJPS) are studied. PNJPS is made by electro-chemical anodic etched method from silicon wafers with P-N junctions. Its porous structure is verified by scanning electronic micrograph.Experiments also show that PNJPS has high sensitivity, short response time (less than 30 seconds), and long-term stability.

  4. Performance Characteristics of a PEM Fuel Cell with Parallel Flow Channels at Different Cathode Relative Humidity Levels

    OpenAIRE

    Sang Soon Hwang; Pil Hyong Lee

    2009-01-01

    In fuel cells flow configuration and operating conditions such as cell temperature, humidity at each electrode and stoichiometric number are very crucial for improving performance. Too many flow channels could enhance the performance but result in high parasite loss. Therefore a trade-off between pressure drop and efficiency of a fuel cell should be considered for optimum design. This work focused on numerical simulation of the effects of operating conditions, especially cathode humidity, wit...

  5. Advancing the quantification of humid tropical forest cover loss with multi-resolution optical remote sensing data: Sampling & wall-to-wall mapping

    Science.gov (United States)

    Broich, Mark

    Humid tropical forest cover loss is threatening the sustainability of ecosystem goods and services as vast forest areas are rapidly cleared for industrial scale agriculture and tree plantations. Despite the importance of humid tropical forest in the provision of ecosystem services and economic development opportunities, the spatial and temporal distribution of forest cover loss across large areas is not well quantified. Here I improve the quantification of humid tropical forest cover loss using two remote sensing-based methods: sampling and wall-to-wall mapping. In all of the presented studies, the integration of coarse spatial, high temporal resolution data with moderate spatial, low temporal resolution data enable advances in quantifying forest cover loss in the humid tropics. Imagery from the Moderate Resolution Imaging Spectroradiometer (MODIS) are used as the source of coarse spatial resolution, high temporal resolution data and imagery from the Landsat Enhanced Thematic Mapper Plus (ETM+) sensor are used as the source of moderate spatial, low temporal resolution data. In a first study, I compare the precision of different sampling designs for the Brazilian Amazon using the annual deforestation maps derived by the Brazilian Space Agency for reference. I show that sampling designs can provide reliable deforestation estimates; furthermore, sampling designs guided by MODIS data can provide more efficient estimates than the systematic design used for the United Nations Food and Agricultural Organization Forest Resource Assessment 2010. Sampling approaches, such as the one demonstrated, are viable in regions where data limitations, such as cloud contamination, limit exhaustive mapping methods. Cloud-contaminated regions experiencing high rates of change include Insular Southeast Asia, specifically Indonesia and Malaysia. Due to persistent cloud cover, forest cover loss in Indonesia has only been mapped at a 5-10 year interval using photo interpretation of single

  6. Approximating snow surface temperature from standard temperature and humidity data: new possibilities for snow model and remote sensing validation (Invited)

    Science.gov (United States)

    Raleigh, M. S.; Landry, C.; Hayashi, M.; Quinton, W. L.; Lundquist, J. D.

    2013-12-01

    The snow surface skin temperature (Ts) is important in the snowmelt energy balance, land-atmosphere interactions, weak layer formation (avalanche risk), and winter recreation, but is rarely measured at observational networks. Reliable Ts datasets are needed to validate remote sensing and distributed modeling, in order to represent land-atmosphere feedbacks. Previous research demonstrated that the dew point temperature (Td) close to the snow surface approximates Ts well because air is saturated immediately above snow. However, standard height (2 to 4 m) measurements of the saturation temperatures, Td and wet-bulb temperature (Tw), are much more readily available than measurements of Ts or near-surface Td. There is limited understanding of how these standard height variables approximate Ts, and how the approximations vary with climate, seasonality, time of day, and atmospheric conditions (stability and radiation). We used sub-daily measurements from seven sites in varying snow climates and environments to test Ts approximations with standard height temperature and moisture. Td produced the lowest bias (-2.2 °C to +2.6 °C) and root mean squared error (RMSE) when approximating mean daily Ts, but tended to underestimate daily extremes in Ts. For comparison, air temperature (Ta) was biased +3.2 °C to +6.8 °C. Ts biases increased with increasing frequency in nighttime stability and daytime clear sky conditions. We illustrate that mean daily Td can be used to detect systematic input data bias in physically-based snowmelt modeling, a useful tool when validating spatially distributed snow models in data sparse regions. Thus, improved understanding of Td variations can advance understanding of Ts in space and time, providing a simple yet robust measure of surface feedback to the atmospheric energy budget.

  7. Effect of impregnating agent and relative humidity on surface characteristics of sorbents determined by inverse gas chromatography.

    Science.gov (United States)

    Kasperkowiak, M; Kołodziejek, J; Strzemiecka, B; Voelkel, A

    2013-05-03

    Sorbents that potentially can be used for separation of the products of biotechnological conversion of glycerol were examined. Properties of Zeolite 5A, resins: Amberlite, Diaion and their samples impregnated with an aqueous solutions of 1,2,3-propanetriol, 1,3-propanediol, 2,3-butanediol, acetic acid, succinic acid and model fermentation broth were investigated. Because surface properties will probably depend on the ambient humidity the IGC experiments were carried out under different conditions of relative humidity RH=0, 40 and 80%. Activity of the sorbents surface was expressed by the value of the dispersive component of the free surface energy. Inverse gas chromatography was also used to express acid-base properties of materials described by KA and KD parameters. The changes in the activity of investigated sorbents significantly varied depending on the type of impregnating agent. Moreover, the obtained results demonstrate that humidity can strongly influence, in some cases, the dispersive component of the free surface energy and the ability to specific interactions (KA and KD).

  8. Enhanced piezo-humidity sensing of a Cd-ZnO nanowire nanogenerator as a self-powered/active gas sensor by coupling the piezoelectric screening effect and dopant displacement mechanism.

    Science.gov (United States)

    Yu, Binwei; Fu, Yongming; Wang, Penglei; Zhao, Yayu; Xing, Lili; Xue, Xinyu

    2015-04-28

    Highly sensitive humidity sensing has been realized from a Cd-doped ZnO nanowire (NW) nanogenerator (NG) as a self-powered/active gas sensor. The piezoelectric output of the device acts not only as a power source, but also as a response signal to the relative humidity (RH) in the environment. The response of Cd-ZnO (1 : 10) NWs reached up to 85.7 upon exposure to 70% relative humidity, much higher than that of undoped ZnO NWs. Cd dopant can increase the number of oxygen vacancies in the NWs, resulting in more adsorption sites on the surface of the NWs. Upon exposure to a humid environment, a large amount of water molecules can displace the adsorbed oxygen ions on the surface of Cd-ZnO NWs. This procedure can influence the carrier density in Cd-ZnO NWs and vary the screening effect on the piezoelectric output. Our study can stimulate a research trend on exploring composite materials for piezo-gas sensing.

  9. Intellective high-precision macromolecule resistance temperature/humidity instrument

    Science.gov (United States)

    Liu, Guixiong; Zhou, Qinhe; Kuang, Yongcong; Xu, Jing; Zeng, Zhixin

    2001-09-01

    Considering that the resistance of macromolecule resistor varies in a wide range and humidity sensor component is sensitive to temperature as well, a intelligent high- precision macromolecule resistance temperature/humidity instrument was proposed in this paper, the instrument is based on the integration of frequency-and-period-measuring method, and sensing characteristic calculation and compensation using interpolation. Practical applications show that the instrument has the advantages of high precision, simple peripheral circuit, low cost, suitability for remote measurement, strong ability of anti-interference and wide operation range.

  10. Enhanced Sensing Characteristics in MEMS-based Formaldehyde Gas Sensor

    CERN Document Server

    Wang, Yu-Hsiang; Lee, Chia-Yen; Ma, R -H; Chou, Po-Cheng

    2008-01-01

    This study has successfully demonstrated a novel self-heating formaldehyde gas sensor based on a thin film of NiO sensing layer. A new fabrication process has been developed in which the Pt micro heater and electrodes are deposited directly on the substrate and the NiO thin film is deposited above on the micro heater to serve as sensing layer. Pt electrodes are formed below the sensing layer to measure the electrical conductivity changes caused by formaldehyde oxidation at the oxide surface. Furthermore, the upper sensing layer and NiO/Al2O3 co-sputtering significantly increases the sensitivity of the gas sensor, improves its detection limit capability. The microfabricated formaldehyde gas sensor presented in this study is suitable not only for industrial process monitoring, but also for the detection of formaldehyde concentrations in buildings in order to safeguard human health.

  11. Effect of fuels on conductivity, dielectric and humidity sensing properties of ZrO2 nanocrystals prepared by low temperature solution combustion method

    Directory of Open Access Journals (Sweden)

    H.C. Madhusudhana

    2016-09-01

    Full Text Available ZrO2 nanopowders were synthesized by low temperature solution combustion method using two different fuels namely glycine and oxalyldihydrazide (ODH. The phase confirmation was done by powder X-ray diffraction (PXRD and Raman spectral analysis. Use of glycine resulted in ZrO2 with mixture of tetragonal and monoclinic phase with average crystallite size of ∼30 nm. However, ODH as fuel aids in the formation of ZrO2 with mixture of tetragonal and cubic phase with average crystallite size ∼20 nm. Further, in present work we present novel way to tune conductivity property of the nano ZrO2. We show that merely changing the fuel from glycine to ODH, we obtain better DC conductivity and dielectric constant. On the other hand use of glycine leads to the formation of ZrO2 with better AC conductivity and humidity sensing behavior. The dielectric constants calculated for samples prepared with glycine and ODH were found to be 45 and 26 respectively at 10 MHz. The AC and DC conductivity values of the samples prepared with glycine was found to be 9.5 × 10−4 S cm−1, 1.1 × 10−3 S cm−1 and that of ODH was 7.6 × 10−4 S cm−1, 3.6 × 10−3 S cm−1 respectively.

  12. Hydrogen sensing characteristics from carbon nanotube field emissions

    Science.gov (United States)

    Dong, Changkun; Luo, Haijun; Cai, Jianqiu; Wang, Fuquan; Zhao, Yangyang; Li, Detian

    2016-03-01

    An innovative hydrogen sensing concept is demonstrated based on the field emission from multi-walled carbon nanotubes, where the low emission currents rise in proportion to hydrogen partial pressures above 10-9 Torr. Experimental and first principles studies reveal that the sensing mechanism is attributed to the effective work function reduction from dissociative hydrogen chemisorption. The embedded Ni catalyst would assist both the hydrogen dissociation and work function reduction. This technique is promising to build miniature low cost hydrogen sensors for multiple applications. This work is valuable for studies of nanocarbon-gas reaction mechanisms and the work function properties in adsorption related applications, including field emission, hydrogen storage, energy cells, and gas sensing.

  13. Set-up and characterization of a humidity sensor realized in LTCC-technology

    CERN Document Server

    Smetana, W

    2008-01-01

    A new type of integrated temperature and humidity sensor applying LTCC-technology has been developed and characterized. In this approach, sensing elements are implemented using heated metal resistors (Pt-elements), where one is exposed to the humid environment that causes the sensor element to cool down with increased humidity, while the other one is sealed from the environment. Sensor design is based on FEA (Finite Element Analyses) where the critical design parameters have been analyzed with regard to the performance characteristic of the device. The set-up of sensor element will be shown and the functional capability will be demonstrated by experimental results.

  14. Using satellite data on meteorological and vegetation characteristics and soil surface humidity in the Land Surface Model for the vast territory of agricultural destination

    Science.gov (United States)

    Muzylev, Eugene; Startseva, Zoya; Uspensky, Alexander; Vasilenko, Eugene; Volkova, Elena; Kukharsky, Alexander

    2017-04-01

    The model of water and heat exchange between vegetation covered territory and atmosphere (LSM, Land Surface Model) for vegetation season has been developed to calculate soil water content, evapotranspiration, infiltration of water into the soil, vertical latent and sensible heat fluxes and other water and heat balances components as well as soil surface and vegetation cover temperatures and depth distributions of moisture and temperature. The LSM is suited for utilizing satellite-derived estimates of precipitation, land surface temperature and vegetation characteristics and soil surface humidity for each pixel. Vegetation and meteorological characteristics being the model parameters and input variables, correspondingly, have been estimated by ground observations and thematic processing measurement data of scanning radiometers AVHRR/NOAA, SEVIRI/Meteosat-9, -10 (MSG-2, -3) and MSU-MR/Meteor-M № 2. Values of soil surface humidity has been calculated from remote sensing data of scatterometers ASCAT/MetOp-A, -B. The case study has been carried out for the territory of part of the agricultural Central Black Earth Region of European Russia with area of 227300 km2 located in the forest-steppe zone for years 2012-2015 vegetation seasons. The main objectives of the study have been: - to built estimates of precipitation, land surface temperatures (LST) and vegetation characteristics from MSU-MR measurement data using the refined technologies (including algorithms and programs) of thematic processing satellite information matured on AVHRR and SEVIRI data. All technologies have been adapted to the area of interest; - to investigate the possibility of utilizing satellite-derived estimates of values above in the LSM including verification of obtained estimates and development of procedure of their inputting into the model. From the AVHRR data there have been built the estimates of precipitation, three types of LST: land skin temperature Tsg, air temperature at a level of

  15. Design and Development for Capacitive Humidity Sensor Applications of Lead-Free Ca,Mg,Fe,Ti-Oxides-Based Electro-Ceramics with Improved Sensing Properties via Physisorption

    Science.gov (United States)

    Tripathy, Ashis; Pramanik, Sumit; Manna, Ayan; Bhuyan, Satyanarayan; Azrin Shah, Nabila Farhana; Radzi, Zamri; Abu Osman, Noor Azuan

    2016-01-01

    Despite the many attractive potential uses of ceramic materials as humidity sensors, some unavoidable drawbacks, including toxicity, poor biocompatibility, long response and recovery times, low sensitivity and high hysteresis have stymied the use of these materials in advanced applications. Therefore, in present investigation, we developed a capacitive humidity sensor using lead-free Ca,Mg,Fe,Ti-Oxide (CMFTO)-based electro-ceramics with perovskite structures synthesized by solid-state step-sintering. This technique helps maintain the submicron size porous morphology of the developed lead-free CMFTO electro-ceramics while providing enhanced water physisorption behaviour. In comparison with conventional capacitive humidity sensors, the presented CMFTO-based humidity sensor shows a high sensitivity of up to 3000% compared to other materials, even at lower signal frequency. The best also shows a rapid response (14.5 s) and recovery (34.27 s), and very low hysteresis (3.2%) in a 33%–95% relative humidity range which are much lower values than those of existing conventional sensors. Therefore, CMFTO nano-electro-ceramics appear to be very promising materials for fabricating high-performance capacitive humidity sensors. PMID:27455263

  16. Design and Development for Capacitive Humidity Sensor Applications of Lead-Free Ca,Mg,Fe,Ti-Oxides-Based Electro-Ceramics with Improved Sensing Properties via Physisorption

    Directory of Open Access Journals (Sweden)

    Ashis Tripathy

    2016-07-01

    Full Text Available Despite the many attractive potential uses of ceramic materials as humidity sensors, some unavoidable drawbacks, including toxicity, poor biocompatibility, long response and recovery times, low sensitivity and high hysteresis have stymied the use of these materials in advanced applications. Therefore, in present investigation, we developed a capacitive humidity sensor using lead-free Ca,Mg,Fe,Ti-Oxide (CMFTO-based electro-ceramics with perovskite structures synthesized by solid-state step-sintering. This technique helps maintain the submicron size porous morphology of the developed lead-free CMFTO electro-ceramics while providing enhanced water physisorption behaviour. In comparison with conventional capacitive humidity sensors, the presented CMFTO-based humidity sensor shows a high sensitivity of up to 3000% compared to other materials, even at lower signal frequency. The best also shows a rapid response (14.5 s and recovery (34.27 s, and very low hysteresis (3.2% in a 33%–95% relative humidity range which are much lower values than those of existing conventional sensors. Therefore, CMFTO nano-electro-ceramics appear to be very promising materials for fabricating high-performance capacitive humidity sensors.

  17. Refractive index sensing characteristics of dual resonances in rectangular fractal nano-apertures

    Science.gov (United States)

    Aslan, Ekin; Turkmen, Mustafa

    2015-08-01

    Aperture based sensing platforms can be useful for both gas and bio-sensing applications. In this study, we investigate the refractive index sensing characteristics of dual resonances in rectangular fractal nanoapertures. By taking the advantages coming from its aperture based nature and dual band resonant behavior, one can use this platform to detect two different chemical/bio-molecules simultaneously. For the numerical analysis, we study the rectangular fractal nanoantenna array through the finite difference time domain (FDTD) method. We also introduce a fine tuning mechanism for adjusting the resonance frequencies which is important for the sensing applications. Then, we demonstrate the results of refractive index sensitivity tests in order to show the behavior of the structure against the refractive index changes. In these tests, we embed our sensing platform into different cladding media and obtain the refractive index sensing characteristics of dual resonances. Due to the dual-resonant behavior with easily accessible ultra-high-field localization characteristics, the proposed sensing platform can be a good candidate for ultra-sensitive chemical- and bio-sensing applications.

  18. Ethanol-Sensing Characteristics of Nanostructured ZnO: Nanorods, Nanowires, and Porous Nanoparticles

    Science.gov (United States)

    Quy, Chu Thi; Hung, Chu Manh; Van Duy, Nguyen; Hoa, Nguyen Duc; Jiao, Mingzhi; Nguyen, Hugo

    2017-06-01

    The morphology and crystalline size of metal oxide-sensing materials are believed to have a strong influence on the performance of gas sensors. In this paper, we report a comparative study on the ethanol-sensing characteristics of ZnO nanorods, nanowires, and porous nanoparticles. The porous ZnO nanoparticles were prepared using a simple thermal decomposition of a sheet-like hydrozincite, whereas the nanorods and nanowires were grown by hydrothermal and chemical vapor deposition methods, respectively. The morphology and crystal structure of the synthesized materials were characterized by field-emission scanning electron microscopy and x-ray diffraction. Ethanol gas-sensing characteristics were systematically studied at different temperatures. Our findings show that for ethanol gas-sensing applications, ZnO porous nanoparticles exhibited the best sensitivity, followed by the nanowires and nanorods. Gas-sensing properties were also examined with respect to the role of crystal growth orientation, crystal size, and porosity.

  19. Enhanced Acetone Sensing Characteristics of ZnO/Graphene Composites

    OpenAIRE

    Hao Zhang; Yuan Cen; Yu Du; Shuangchen Ruan

    2016-01-01

    ZnO/graphene (ZnO-G) hybrid composites are prepared via hydrothermal synthesis with graphite, N-methyl-pyrrolidone (NMP), and Zn(NO3)2·6H2O as the precursors. The characterizations, including X-ray diffraction (XRD), thermogravimetric analyses (TGA), Raman spectroscopy, and transmission electron microscopy (TEM) indicate the formation of ZnO-G. Gas sensors were fabricated with ZnO-G composites and ZnO as sensing material, indicating that the response of the ZnO towards acetone was significant...

  20. Model-based acoustic remote sensing of seafloor characteristics

    Digital Repository Service at National Institute of Oceanography (India)

    De, Ch.; Chakraborty, B.

    characterization using time- dependent acoustic backscatter: Study of Arabian Sea,” in Proc. IEEE Oceans, Kobe, Japan, 2008, pp. 1–4. 3876 IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING, VOL. 49, NO. 10, OCTOBER 2011 [6] C. De and B. Chakraborty, “Acoustic... characterization of seafloor sediment employing a hybrid method of neural network architecture and fuzzy algorithm,” IEEE Geosci. Remote Sens. Lett., vol. 6, no. 4, pp. 743–747, Oct. 2009. [7] C. De and B. Chakraborty, “Preference of echo features...

  1. Seasonal variation in coat characteristics, tick loads, cortisol levels, some physiological parameters and temperature humidity index on Nguni cows raised in low- and high-input farms

    Science.gov (United States)

    Katiyatiya, C. L. F.; Muchenje, V.; Mushunje, A.

    2015-06-01

    Seasonal variations in hair length, tick loads, cortisol levels, haematological parameters (HP) and temperature humidity index (THI) in Nguni cows of different colours raised in two low-input farms, and a commercial stud was determined. The sites were chosen based on their production systems, climatic characteristics and geographical locations. Zazulwana and Komga are low-input, humid-coastal areas, while Honeydale is a high-input, dry-inland Nguni stud farm. A total of 103 cows, grouped according to parity, location and coat colour, were used in the study. The effects of location, coat colour, hair length and season were used to determine tick loads on different body parts, cortisol levels and HP in blood from Nguni cows. Highest tick loads were recorded under the tail and the lowest on the head of each of the animals ( P Cortisol and THI were significantly lower ( P cortisol levels, THI, HP and tick loads on different body parts and heat stress in Nguni cows.

  2. Impact of temperature-humidity index on egg-laying characteristics and related stress and immunity parameters of Japanese quails

    Science.gov (United States)

    El-Tarabany, Mahmoud Salah

    2016-07-01

    The aim of this study was to investigate the effect of temperature-humidity index (THI) level on productive parameters, welfare, and immunity in Japanese quails. One hundred and eighty (180) birds of Japanese quail, 14 weeks old, were used. Birds were divided randomly into three equal groups, control (at low THI, less than 70), H1 (at moderate THI, 70-75), and H2 (at high THI, 76-80). Birds in the control group had higher body weight (281.2 g, p = 0.001), egg mass (745 g, p = 0.001), fertility (85.4 %, p = 0.039), hatchability (80.4 %, p = 0.001), and immune response titer to Newcastle disease virus ( p = 0.031), compared with H2 group. Furthermore, the thermoneutral group had higher internal egg quality score [albumen height (5.14 mm, p = 0.001), yolk height (10.88 mm, p = 0.015), yolk index (42.32 %, p = 0.039), and Haugh unit (92.67, p = 0.001)]. Nevertheless, there were no significant differences in fertility percentage, immune response, and corticosterone concentration between control and H1 group. Birds in the H2 group had the lowest total leucocytic count and lymphocyte percentage ( p = 0.001 and 0.020, respectively) but the highest H/L ratio (0.83, p = 0.001). Corticosterone concentration was lower in control and H1 groups (5.49 and 6.41 ng/mL, respectively, p = 0.024) than that in H2 group. Japanese quail exposed to heat stress revealed drop in production and immunological parameters, as well as a detrimental effects on welfare. Thus, practical approaches might be used to reduce the detrimental effects of greater THI level.

  3. Enhanced Acetone Sensing Characteristics of ZnO/Graphene Composites.

    Science.gov (United States)

    Zhang, Hao; Cen, Yuan; Du, Yu; Ruan, Shuangchen

    2016-11-09

    ZnO/graphene (ZnO-G) hybrid composites are prepared via hydrothermal synthesis with graphite, N-methyl-pyrrolidone (NMP), and Zn(NO₃)₂·6H₂O as the precursors. The characterizations, including X-ray diffraction (XRD), thermogravimetric analyses (TGA), Raman spectroscopy, and transmission electron microscopy (TEM) indicate the formation of ZnO-G. Gas sensors were fabricated with ZnO-G composites and ZnO as sensing material, indicating that the response of the ZnO towards acetone was significantly enhanced by graphene doping. It was found that the ZnO-G sensor exhibits remarkably enhanced response of 13.3 at the optimal operating temperature of 280 °C to 100 ppm acetone, an improvement from 7.7 with pure ZnO.

  4. Research on Properties optimization of humidity sensitive material ZnCr2O4-V2O5-Li2O-ZnO

    Institute of Scientific and Technical Information of China (English)

    FU Heng-lei; XU Tian-hua; SUN Bin

    2009-01-01

    Humidity-seining properties of humidity-sensitive material ZnCr2O4-V2O5-Li2O-ZnO made from crystal pbase ZnCr2O4.and glass phase LiZnVO4 of different mole ratios Were tested over a long time,synthetic characteristics of different mole ratios are compared,it shows that the best humidity-sensing properties were obtained when mole rataos are 94:6 and 96:4,the cause that mole ratio affects humadity-sensing properties parameters is analyzed.

  5. Can Remote Sensing Detect Aquifer Characteristics?: A Case Study in the Guarani Aquifer System

    Science.gov (United States)

    Richey, A. S.; Thomas, B.; Famiglietti, J. S.

    2013-12-01

    Global water supply resiliency depends on groundwater, especially regions threatened by population growth and climate change. Aquifer characteristics, even as basic as confined versus unconfined, are necessary to prescribe regulations to sustainably manage groundwater supplies. A significant barrier to sustainable groundwater management exists in the difficulties associated with mapping groundwater resources and characteristics at a large spatial scale. This study addresses this challenge by investigating if remote sensing, including with NASA's Gravity Recovery and Climate Experiment (GRACE), can detect and quantify key aquifer parameters and characteristics. We explore this through a case study in the Guarani Aquifer System (GAS) of South America, validating our remote sensing-based findings against the best available regional estimates. The use of remote sensing to advance the understanding of large aquifers is beneficial to sustainable groundwater management, especially in a trans-boundary system, where consistent information exchange can occur within hydrologic boundaries instead of political boundaries.

  6. Miniature Flexible Humidity Sensitive Patches for Space Suits Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Advanced space suit technologies demand improved, simplified, long-life regenerative sensing technologies, including humidity sensors, that exceed the performance of...

  7. Humidity Sensors Principle, Mechanism, and Fabrication Technologies: A Comprehensive Review

    Directory of Open Access Journals (Sweden)

    Hamid Farahani

    2014-04-01

    Full Text Available Humidity measurement is one of the most significant issues in various areas of applications such as instrumentation, automated systems, agriculture, climatology and GIS. Numerous sorts of humidity sensors fabricated and developed for industrial and laboratory applications are reviewed and presented in this article. The survey frequently concentrates on the RH sensors based upon their organic and inorganic functional materials, e.g., porous ceramics (semiconductors, polymers, ceramic/polymer and electrolytes, as well as conduction mechanism and fabrication technologies. A significant aim of this review is to provide a distinct categorization pursuant to state of the art humidity sensor types, principles of work, sensing substances, transduction mechanisms, and production technologies. Furthermore, performance characteristics of the different humidity sensors such as electrical and statistical data will be detailed and gives an added value to the report. By comparison of overall prospects of the sensors it was revealed that there are still drawbacks as to efficiency of sensing elements and conduction values. The flexibility offered by thick film and thin film processes either in the preparation of materials or in the choice of shape and size of the sensor structure provides advantages over other technologies. These ceramic sensors show faster response than other types.

  8. The Use of Compressive Sensing to Reconstruct Radiation Characteristics of Wide-Band Antennas from Sparse Measurements

    Science.gov (United States)

    2015-06-01

    ARL-TR-7328 ● JUN 2015 US Army Research Laboratory The Use of Compressive Sensing to Reconstruct Radiation Characteristics of...Army Research Laboratory The Use of Compressive Sensing to Reconstruct Radiation Characteristics of Wide- Band Antennas from Sparse Measurements... Compressive Sensing to Reconstruct Radiation Characteristics of Wide-Band Antennas from Sparse Measurements 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c

  9. Characteristics of the mechanical milling on the room temperature ferromagnetism and sensing properties of TiO{sub 2} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Bolokang, A.S., E-mail: Sylvester.Bolokang@transnet.net [Department of Physics, University of the Western Cape, Private Bag X 17, Bellville 7535 (South Africa); DST/CSIR National Centre for Nano-Structured Materials, Council for Scientific and Industrial Research, Pretoria 0001 (South Africa); Transnet Engineering, Product Development, Private Bag X 528, Silverton 0127 (South Africa); Cummings, F.R. [Department of Physics, University of the Western Cape, Private Bag X 17, Bellville 7535 (South Africa); Electron Microscope Unit, University of the Western Cape, Private Bag X 17, Bellville 7535 (South Africa); Dhonge, B.P. [DST/CSIR National Centre for Nano-Structured Materials, Council for Scientific and Industrial Research, Pretoria 0001 (South Africa); Abdallah, H.M.I.; Moyo, T. [School of Chemistry and Physics, Westville Campus, University of KwaZulu-Natal, Private Bag X54001, Durban 4000 (South Africa); Swart, H.C. [Department of Physics, University of the Free State, P.O. Box 339, Bloemfontein ZA9300 (South Africa); Arendse, C.J.; Muller, T.F.G. [Department of Physics, University of the Western Cape, Private Bag X 17, Bellville 7535 (South Africa); Motaung, D.E., E-mail: dmotaung@csir.co.za [DST/CSIR National Centre for Nano-Structured Materials, Council for Scientific and Industrial Research, Pretoria 0001 (South Africa)

    2015-03-15

    Highlights: • Anatase TiO{sub 2} NPs were milled at different times. • A correlation between defect, magnetization and gas sensing is demonstrated. • Magnetization improved with an increase of a defect-related originating from V{sub O}. • Surface area, pore size and volume improve with milling time. • Milled TiO{sub 2} exhibited enhanced gas-sensing properties to humidity. - Abstract: We report on the correlation between defect-related emissions, the magnetization and sensing of TiO{sub 2} nanoparticles (NPs) prepared by milling method. Surface morphology analyses showed that the size of the TiO{sub 2} NPs decreases with milling time. Raman and XRD studies demonstrated that the structural properties of the TiO{sub 2} transform to orthorhombic structure upon milling. Magnetization improved with an increase of a defect-related band originating from oxygen vacancies (V{sub O}), which can be ascribed to a decrease in the size of the NPs due to the milling time. Moreover, the longer-milled TiO{sub 2} exhibited enhanced gas-sensing properties to humidity in terms of sensor response, with about 12 s response time at room temperature. A combination of photoluminescence, X-ray photoelectron spectroscopy, vibrating sample magnetometer and sensing analyses demonstrated that a direct relation exists between the magnetization, sensing and the relative occupancy of the V{sub O} present on the surface of TiO{sub 2} NPs.

  10. On Bandwidth Characteristics of Tuning Fork Micro-Gyroscope with Mechanically Coupled Sense Mode

    Directory of Open Access Journals (Sweden)

    Yunfang Ni

    2014-07-01

    Full Text Available The bandwidth characteristics of a tuning fork micro-gyroscope with mechanically coupled sense mode were investigated in this paper to provide some references for mechanical bandwidth design. The concept of sense mode mechanical coupling is introduced first. Theoretical frequency response analyses were then carried out on the mechanical part of the gyroscope. Equations representing the relationships between the differential output signal and the frequency of the input angular rate were deduced in full frequency range and further simplified in low frequency range. Based on these equations, bandwidth characteristics under ideal and non-ideal conditions are discussed. Analytical results show that under ideal conditions, the bandwidth characteristics of a tuning fork micro-gyroscope are similar to those of a single mass micro-gyroscope, but under non-ideal conditions, especially when sense mass and/or stiffness are asymmetric, the bandwidth characteristics would be quite different because the in-phase mode would participate in the anti-phase vibration response. Experimental verifications were carried out on two micro-gyroscope prototypes designed in our laboratory. The deduced equations and analytical results can be used in guiding the mechanical bandwidth design of tuning fork micro-gyroscopes with mechanically coupled sense mode.

  11. On bandwidth characteristics of tuning fork micro-gyroscope with mechanically coupled sense mode.

    Science.gov (United States)

    Ni, Yunfang; Li, Hongsheng; Huang, Libin; Ding, Xukai; Wang, Haipeng

    2014-01-01

    The bandwidth characteristics of a tuning fork micro-gyroscope with mechanically coupled sense mode were investigated in this paper to provide some references for mechanical bandwidth design. The concept of sense mode mechanical coupling is introduced first. Theoretical frequency response analyses were then carried out on the mechanical part of the gyroscope. Equations representing the relationships between the differential output signal and the frequency of the input angular rate were deduced in full frequency range and further simplified in low frequency range. Based on these equations, bandwidth characteristics under ideal and non-ideal conditions are discussed. Analytical results show that under ideal conditions, the bandwidth characteristics of a tuning fork micro-gyroscope are similar to those of a single mass micro-gyroscope, but under non-ideal conditions, especially when sense mass and/or stiffness are asymmetric, the bandwidth characteristics would be quite different because the in-phase mode would participate in the anti-phase vibration response. Experimental verifications were carried out on two micro-gyroscope prototypes designed in our laboratory. The deduced equations and analytical results can be used in guiding the mechanical bandwidth design of tuning fork micro-gyroscopes with mechanically coupled sense mode.

  12. Effects of relative humidity on aerosol light scattering and its importance for the comparison of remote sensing with in-situ measurements

    Science.gov (United States)

    Zieger, Paul; Clemer, Katrijn; Yilmaz, Selami; Frieß, Udo; Irie, Hitoshi; Henzing, Bas; Fierz-Schmidhauser, Rahel; de Leeuw, Gerrit; Baltensperger, Urs; Weingartner, Ernest

    2010-05-01

    In the field, in-situ measurements of aerosol light scattering are often performed under dry conditions (relative humidity RH MAAP). This combination of measurements allows the determination of the aerosol extinction coefficient at ambient RH. Three MAX-DOAS (multi-axis differential optical absorption spectroscopy) instruments retrieved vertical profiles of the aerosol extinction coefficient during CINDI. The retrieved aerosol extinction corresponding to the lowest profile layer can now be directly compared to the in-situ value, which is now re-calculated to ambient RH.

  13. pH-Sensing Characteristics of Hydrothermal Al-Doped ZnO Nanostructures

    Directory of Open Access Journals (Sweden)

    Jyh-Liang Wang

    2013-01-01

    Full Text Available Highly sensitive and stable pH-sensing properties of an extended-gate field-effect transistor (EGFET based on the aluminum-doped ZnO (AZO nanostructures have been demonstrated. The AZO nanostructures with different Al concentrations were synthesized on AZO/glass substrate via a simple hydrothermal growth method at 85°C. The AZO sensing nanostructures were connected with the metal-oxide-semiconductor field-effect transistor (MOSFET. Afterwards, the current-voltage (I-V characteristics and the sensing properties of the pH-EGFET sensors were obtained in different buffer solutions, respectively. As a result, the pH-sensing characteristics of AZO nanostructured pH-EGFET sensors with Al dosage of 3 at.% can exhibit the higher sensitivity of 57.95 mV/pH, the larger linearity of 0.9998, the smaller deviation of 0.023 in linearity, the lower drift rate of 1.27 mV/hour, and the lower threshold voltage of 1.32 V with a wider sensing range (pH 1 ~ pH 13. Hence, the outstanding stability and durability of AZO nanostructured ionic EGFET sensors are attractive for the electrochemical application of flexible and disposable biosensor.

  14. Room Temperature Ammonia Gas Sensing Characteristics of Co3O4

    Directory of Open Access Journals (Sweden)

    P.N. Shelke

    2011-01-01

    Full Text Available Room temperature ammonia gas-sensing characteristics of Co3O4 pellet sensor are reported in this paper. For this purpose, Co3O4 powder is prepared by a route of simple precipitation + heating at 800 °C/2 hr. The as-prepared powder is characterized by using X-ray diffraction and scanning electron microscopy. The ammonia gas-sensing properties of Co3O4 pellets made at various loads of 3, 5, 7 & 9 ton and at constant time = 4 min. are measured using home-built static gas sensing system. The characterization studies revealed that the cobalt oxide particles formed are cubic spinel Co3O4, highly pure and spherical in shape. The particle size distribution is found to be nearly uniform with average particle size ~ 1 µm. The ammonia gas sensing properties of Co3O4 pellet sensor are found to be good. The highest sensitivities – S.F. = 175 and 358 are found at ~ 25 ppm and 250 ppm concentrations of ammonia gas respectively for the Co3O4 pellet sensor made at the load = 3 ton. Further, an admirable repeatability and reversibility in the ammonia gas sensing characteristics are observed for all the Co3O4 pellet sensors. The average response time of 4.0 min. and recovery time of 3.0 min. are obtained for all the Co3O4 pellet sensors.

  15. MoS2-modified ZnO quantum dots nanocomposite: Synthesis and ultrafast humidity response

    Science.gov (United States)

    Ze, Lu; Yueqiu, Gong; Xujun, Li; Yong, Zhang

    2017-03-01

    In this work, ZnO quantum dots (QDs), layered MoS2 and MoS2-modified ZnO QDs (MoS2@ZnO QDs) nanocomposite were synthesized and then applied as humidity sensor. The crystal structure, morphology and element distribution of ZnO QDs, MoS2 and MoS2@ZnO QDs were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and energy dispersive X-ray spectrometry, respectively. The humidity sensing characteristics of the MoS2 and MoS2@ZnO QDs against various relative humidity were measured at room temperature. The results show that the MoS2@ZnO QDs sensor exhibits high sensitivity with an impedance variation of three or four orders of magnitude to relative humidity range of 11-95% and it exhibits a short response-recovery time (1 s for adsorption and 20 s for desorption) and excellent repeatability. The mechanisms of the excellent performance for humidity sensing of MoS2@ZnO QDs sensor were discussed based on its impedance properties. Our work could offer guidelines to design higher performance especially ultrafast humidity response sensor utilizing the nanocomposite structure with two dimensional material and QDs.

  16. Characteristics of several NIR tuneable diode lasers for spectroscopic based gas sensing: A comparison

    Science.gov (United States)

    Weldon, Vincent; McInerney, David; Phelan, Richard; Lynch, Michael; Donegan, John

    2006-04-01

    Tuneable laser diodes were characterized and compared for use as tuneable sources in gas absorption spectroscopy. Specifically, the characteristics of monolithic widely tuneable single frequency lasers, such as sampled grating distributed Bragg reflector laser and modulated grating Y-branch laser diodes, recently developed for optical communications, with operating wavelengths in the 1520 nm ≤ λ ≤ 1570 nm are compared. The assessment also includes an external cavity laser and a distributed feedback laser for water vapour detection, both emitting at 935 nm. Characteristics investigated include side-mode suppression ratio, ease of tuning, tuning range, spectral emission linewidth, frequency stability and wavelength modulation. While some characteristics differ significantly across the range of lasers, each device has a number of useful intrinsic qualities for gas sensing. Specifically, the modulated grating Y laser and the sampled grating DBR laser have wide quasi-continuous tuneability (30-40 nm) and display relatively low residual amplitude noise when grating-modulated in a harmonic detection scheme. They are particularly suitable for multi-gas sensing. ECLs are also capable of wide quasi-continuous tuneability (100 nm) but their architecture renders them unsuitable for gas sensing application outside a controlled laboratory environment. DFB devices are by far the easiest with which to work but their modest tuneability (4 nm maximum by temperature) almost invariably limits their use to single gas sensing applications.

  17. pH-Sensing Characteristics of Hydrothermal Al-Doped ZnO Nanostructures

    OpenAIRE

    Jyh-Liang Wang; Po-Yu Yang; Tsang-Yen Hsieh; Chuan-Chou Hwang; Miin-Horng Juang

    2013-01-01

    Highly sensitive and stable pH-sensing properties of an extended-gate field-effect transistor (EGFET) based on the aluminum-doped ZnO (AZO) nanostructures have been demonstrated. The AZO nanostructures with different Al concentrations were synthesized on AZO/glass substrate via a simple hydrothermal growth method at 85°C. The AZO sensing nanostructures were connected with the metal-oxide-semiconductor field-effect transistor (MOSFET). Afterwards, the current-voltage (I-V) characteristics and ...

  18. Understanding the fundamental principles of metal oxide based gas sensors; the example of CO sensing with SnO sub 2 sensors in the presence of humidity

    CERN Document Server

    Barsan, N

    2003-01-01

    This paper investigates the effect of water vapour in CO sensing by using Pd doped SnO sub 2 sensors realized in thick film technology as an example of the basic understanding of sensing mechanisms applied to sensors. The results of phenomenological and spectroscopic measurement techniques, all of them obtained under working conditions for sensors, were combined with modelling in order to derive conclusions able to be generalized to the field of metal oxide based gas sensors. The techniques employed were: dc conductance, ac impedance spectroscopy, work function (by using the Kelvin probe method), catalytic conversion and diffuse reflectance infrared Fourier transform measurements. The most important conclusion is that the different parts of the sensor (sensing layer, electrodes, substrate) are all influencing the gas detection and their role has to be taken into consideration when one attempts to understand how a sensor works. (topical review)

  19. Characteristics on Humidity-controlled Composite Material in Greenhouse%温室用复合调湿材料特性的试验研究

    Institute of Scientific and Technical Information of China (English)

    陈伟; 魏凤兰; 刘锷; 李春龙; 张彩碚

    2011-01-01

    为探讨自制复合调湿材料替代温室后墙体内表面部分红砖的可行性,对密闭空间内的复合调湿材料进行了调湿能力研究,同时,在室温条件下对其进行了热工和力学性能的试验研究.结果表明:密闭空间的复合调湿材料其饱和吸湿率可达130%;在40min内,相对湿度降低了23%,即相对湿度由92.5%降低到了69.5%,在13h内相对湿度降低到了30.5%,即由92.5%降低到62%,在高湿情况下吸湿的性能要高于硅胶,吸湿性能比较显著;复合调湿砌块能够满足温室内墙体材料的热工性能和机械性能的要求.%In order to investigate the feasibility that self-made composite humidity-controlling materials replace the fraction red brick of the internal surface of back wall in greenhouse, a study on the humidity-controlling ability of composite humidity -controlling materials in confined space was conducted. At the same time, thermal and mechanical properties of composite humidity-controlled material were investigated in room temperature. The results showed that: saturated moisture absorption rate of composite humidity-controlled could be approximately 130%; in 40 minutes, the relative humidity decreased by 23%, which meant that the relative humidity decreased from 92.5% to 69.5%, the relative humidity decreased to 30.5% in 13 hours, which meant the relative humidity decreased from 92.5% to 62%.Under higher humidity conditions, the moisture-absorbing ability of the composite humidity -controlled materials was higher than that of silicone, having a more significant moisture absorption performance. The composite humidity-controlled building block could satisfy the thermal and mechanical property requirement of wall materials in greenhouse.

  20. 利用湿润指数分析开封市1981-2010年干旱湿润特征%Using Humidity Index to Analyze the Drought and Humid Characteristics of Kaifeng During 1981-2010

    Institute of Scientific and Technical Information of China (English)

    王二虎

    2012-01-01

    The 30 years consecutive climate datas of Kaifeng during 1981?010 were analyzed based on humidity index. It was found that Kaifeng is mainly with semiarid climate, and the humidity index was around 0.50. This indicator for dividing dry and wet showed obviously fluctuate trend. Only July and August of the year belong to wet period, while the period from October to June of the following year is basically dry climate. Kaifeng in winter, spring and autumn is mainly dry climate, the wet period only in summer. The moisture income of kaifeng mainly concentrates in the summer.%利用湿润指数对开封市1981-2010年连续30年的气候资料进行分析,开封市这30年的气候以半干旱为主,湿润指数围绕0.50这一干湿分界指标呈现明显上下波动的趋势.一年当中只有7月和8月两个月份属于湿润期,而从10月到次年6月基本为干旱期,冬、春、秋三季属于半干旱气候,只有夏季属于湿润期,水分收入主要集中在夏季.

  1. Inmate Violence and Correctional Staff Burnout: The Role of Sense of Security, Gender, and Job Characteristics.

    Science.gov (United States)

    Isenhardt, Anna; Hostettler, Ueli

    2016-12-05

    Violence in the workplace has serious consequences for employees and organizations. Based on a survey in early 2012 among employees from all work areas of 89 of the total 112 correctional facilities in Switzerland resulting in a sample of 2,045 employees (response rate 48.5%), this study (a) analyzed whether victimization has an impact on correctional staff burnout, (b) tested the hypothetical mediating role of sense of security in the relationship between victimization and burnout, and (c) included gender and job characteristics because work experiences and exposure to violence of staff differ strongly with gender and work tasks. Two different forms of violence were considered: (a) experienced violence (inmates-on-staff) and (b) observed violence (inmate-on-inmate). Analysis was carried out using structural equation modeling. Results show that victimization and witnessing violence between inmates negatively affect the personal sense of security and increase correctional staff burnout. In addition, the sense of security mediated the effect from experienced and observed violence on burnout. Gender and job characteristics also proved to be important. This is especially true for staff working as correctional officers and for employees working with young inmates and with inmates awaiting trial who reported a greater exposure to violence and a lower sense of security. The study adds to the knowledge on violence and its outcomes in corrections and contributes to the literature on the consequences of workplace violence in general and, specifically, in social service occupations. © The Author(s) 2016.

  2. Target-in-the-loop remote sensing of laser beam and atmospheric turbulence characteristics.

    Science.gov (United States)

    Vorontsov, Mikhail A; Lachinova, Svetlana L; Majumdar, Arun K

    2016-07-01

    A new target-in-the-loop (TIL) atmospheric sensing concept for in situ remote measurements of major laser beam characteristics and atmospheric turbulence parameters is proposed and analyzed numerically. The technique is based on utilization of an integral relationship between complex amplitudes of the counterpropagating optical waves known as overlapping integral or interference metric, whose value is preserved along the propagation path. It is shown that the interference metric can be directly measured using the proposed TIL sensing system composed of a single-mode fiber-based optical transceiver and a remotely located retro-target. The measured signal allows retrieval of key beam and atmospheric turbulence characteristics including scintillation index and the path-integrated refractive index structure parameter.

  3. Measuring Relative Humidity.

    Science.gov (United States)

    Pinkham, Chester A.; Barrett, Kristin Burrows

    1992-01-01

    Describes four experiments that enable students to explore the phenomena of evaporation and condensation and determine the relative humidity by measuring air temperature and dew point on warm September days. Provides tables to calculate saturation points and relative humidity. (MDH)

  4. Sense of coherence and job characteristics in predicting burnout in a South African sample

    Directory of Open Access Journals (Sweden)

    Claire S. Johnston

    2013-01-01

    Full Text Available Orientation: Research that considers the effects of individual characteristics and job characteristics jointly in burnout is necessary, especially when one considers the possibility of curvilinear relationships between job characteristics and burnout.Research purpose: This study examines the contribution of sense of coherence (SOC and job characteristics to predicting burnout by considering direct and moderating effects.Motivation for this study: Understanding the relationships of individual and job characteristics with burnout is necessary for preventing burnout. It also informs the design of interventions.Research design, approach and method: The participants were 632 working adults (57% female in South Africa. The measures included the Job Content Questionnaire, the Sense of Coherence Questionnaire and the Maslach Burnout Inventory. The authors analysed the data using hierarchical multiple regression with the enter method.Main findings: Job characteristics and SOC show the expected direct effects on burnout. SOC has a direct negative effect on burnout. Job demands and supervisor social support show nonlinear relationships with burnout. SOC moderates the effect of demands on burnout and has a protective function so that the demands-burnout relationship differs for those with high and low SOC.Practical/managerial implications: The types of effects, the shape of the stressor-strain relationship and the different contributions of individual and job characteristics have implications for designing interventions.Contribution/value add: SOC functions differently when combined with demands, control and support. These different effects suggest that it is not merely the presence or absence of a job characteristic that is important for well-being outcomes but how people respond to its presence or absence.

  5. Porous ZrO{sub 2}-TiO{sub 2} ceramics for applications as sensing elements in the air humidity monitoring; Ceramicas porosas de ZrO{sub 2}-TiO{sub 2} para aplicacao como elementos sensores no monitoramento de umidade do ar

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Rodrigo de Matos; Nono, Maria do Carmo de Andrade, E-mail: rodmatos@las.inpe.br [Instituto Nacional de Pesquisas Espaciais (SUCERA/INPE), Sao Jose dos Campos, SP (Brazil). Grupo de Pesquisa em Engenharia de Superficies de Solidos e de Ceramicas Micro e Nanoestruturadas

    2011-07-01

    The environmental monitoring requires versatile, reliable and lower cost instruments. The chemical superficial absorption/adsorption capability of water molecules by several ceramic oxides makes them excellent candidates for this application. In this way, many efforts have been made for the development of porous ceramics, manufactured from mechanical mixture of ZrO{sub 2} and TiO{sub 2} powders, for application as air humidity sensing elements. The sintered ceramics were characterized as for crystalline phases (X-ray diffraction) and pores structure (scanning electron microscopy and mercury porosimetry). The relative humidity curves for the ceramics were obtained from measurements with RLC bridge in climatic chamber. The behavior of these curves were comparatively analyzed with the aid of pores sizes distribution curves, obtained through mercury porosimetry. The results evidenced that the air humidity ceramic sensing elements are very promising ones. (author)

  6. Screening in humid air plasmas

    Science.gov (United States)

    Filippov, Anatoly; Derbenev, Ivan; Dyatko, Nikolay; Kurkin, Sergey

    2016-09-01

    Low temperature air plasmas containing H2O molecules are of high importance for atmospheric phenomena, climate control, biomedical applications, surface processing, and purification of air and water. Humid air plasma created by an external ionization source is a good model of the troposphere where ions are produced by the galactic cosmic rays and decay products of air and soil radioactive elements such as Rn222. The present paper is devoted to study the ionic composition and the screening in an ionized humid air at atmospheric pressure and room temperature. The ionization rate is varied in the range of 101 -1018 cm-3s-1. The humid air with 0 - 1 . 5 % water admixture that corresponds to the relative humidity of 0 - 67 % at the air temperature equal to 20°C is considered. The ionic composition is determined on the analysis of more than a hundred processes. The system of 41 non-steady state particle number balance equations is solved using the 4th order Runge-Kutta method. The screening of dust particle charge in the ionized humid air are studied within the diffusion-drift approach. The screening constants are well approximated by the inverse Debye length and characteristic lengths of recombination and attachment processes. This work was supported by the Russian Science Foundation, Project No. 16-12-10424.

  7. Self-Sensing Control of Nafion-Based Ionic Polymer-Metal Composite (IPMC Actuator in the Extremely Low Humidity Environment

    Directory of Open Access Journals (Sweden)

    Minoru Sasaki

    2013-10-01

    Full Text Available This paper presents feedforward, feedback and two-degree-of-freedom control applied to an Ionic Polymer-Metal Composite (IPMC actuator. It presents a high potential for development of miniature robots and biomedical devices and artificial muscles. We have reported in the last few years that dehydration treatment improves the electrical controllability of bending in Selemion CMV-based IPMCs. We tried to replicate this controllability in Nafion-based IPMC. We found that the displacement of a Nafion-based IPMC was proportional to the total charge imposed, just as in the Selemion-CMV case. This property is the basis of self-sensing controllers for Nafion-based IPMC bending behavior: we perform bending curvature experiments on Nafion-based IPMCs, obtaining the actuator's dynamics and transfer function. From these, we implemented self-sensing controllers using feedforward, feedback and two-degree-of-freedom techniques. All three controllers performed very well with the Nafion-based IPMC actuator.

  8. Optical Remote Sensing of Glacier Characteristics: A Review with Focus on the Himalaya

    Directory of Open Access Journals (Sweden)

    Roger G. Barry

    2008-05-01

    Full Text Available The increased availability of remote sensing platforms with appropriate spatial and temporal resolution, global coverage and low financial costs allows for fast, semi-automated, and cost-effective estimates of changes in glacier parameters over large areas. Remote sensing approaches allow for regular monitoring of the properties of alpine glaciers such as ice extent, terminus position, volume and surface elevation, from which glacier mass balance can be inferred. Such methods are particularly useful in remote areas with limited field-based glaciological measurements. This paper reviews advances in the use of visible and infrared remote sensing combined with field methods for estimating glacier parameters, with emphasis on volume/area changes and glacier mass balance. The focus is on the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER sensor and its applicability for monitoring Himalayan glaciers. The methods reviewed are: volumetric changes inferred from digital elevation models (DEMs, glacier delineation algorithms from multi-spectral analysis, changes in glacier area at decadal time scales, and AAR/ELA methods used to calculate yearly mass balances. The current limitations and on-going challenges in using remote sensing for mapping characteristics of mountain glaciers also discussed, specifically in the context of the Himalaya.

  9. FBG sensing temperature characteristic and application in oil/gas down-hole measurement

    Institute of Scientific and Technical Information of China (English)

    Shaomin LI; Xiaoying LIU; You LI; Shenlong YANG; Chong LIU

    2009-01-01

    Fiber Bragg gratings (FBGs) have been used to sense numerous parameters such as strain, temperature, and pressure. Cost-effective multipoint measurements have been achieved by connecting FBGs in parallel, serial, and other topologies as well as by using spatial, wavelength, and time-domain multiplexing techniques. This paper presents a method of measuring temperature of the oil/gas down-hole. Detailed contents include the basic theory and characteristics of fiber gratings, analysis of the sensing mechanism of fiber-optic gratings, and the cross-sensitivity effect between temperature and strain; the method of making the light-source of the fiber-optic gratings and the technology of measuring wavelength shift, building an experimental system of the temperature measurement, and dealing with the experimental data. The paper makes a comparison of several kinds of FBG sensing systems used in oil/gas down-hole to measure temperature and the analysis of the experimental results of building the temperature measurement experimental sys-tem. It demonstrates that the fiber-optic grating sensing method is the best choice in all methods of measuring temperature in oil/gas down-hole, which has a brilliant applied prospect.

  10. Parameterization of High Resolution Vegetation Characteristics using Remote Sensing Products for the Nakdong River Watershed, Korea

    Directory of Open Access Journals (Sweden)

    Hyun Il Choi

    2013-01-01

    Full Text Available Mesoscale regional climate models (RCMs, the primary tool for climate predictions, have recently increased in sophistication and are being run at increasingly higher resolutions to be also used in climate impact studies on ecosystems, particularly in agricultural crops. As satellite remote sensing observations of the earth terrestrial surface become available for assimilation in RCMs, it is possible to incorporate complex land surface processes, such as dynamics of state variables for hydrologic, agricultural and ecologic systems at the smaller scales. This study focuses on parameterization of vegetation characteristics specifically designed for high resolution RCM applications using various remote sensing products, such as Advanced Very High Resolution Radiometer (AVHRR, Système Pour l’Observation de la Terre-VEGETATION (SPOT-VGT and Moderate Resolution Imaging Spectroradiometer (MODIS. The primary vegetative parameters, such as land surface characteristics (LCC, fractional vegetation cover (FVC, leaf area index (LAI and surface albedo localization factors (SALF, are currently presented over the Nakdong River Watershed domain, Korea, based on 1-km remote sensing satellite data by using the Geographic Information System (GIS software application tools. For future high resolution RCM modeling efforts on climate-crop interactions, this study has constructed the deriving parameters, such as FVC and SALF, following the existing methods and proposed the new interpolation methods to fill missing data with combining the regression equation and the time series trend function for time-variant parameters, such as LAI and NDVI data at 1-km scale.

  11. Effects of metal coating on the fiber Bragg grating temperature sensing characteristics

    Science.gov (United States)

    Wen, Changjin; Li, Yulong

    2016-04-01

    Effects of the metal coatings on the fiber Bragg grating (FBG) temperature sensing characteristics were simulated and experimentally investigated. Temperature sensitivity of the coated FBG as a function of the coating material properties was simulated using MATLAB software based on the temperature sensing model. The simulation results show that the elastic modulus, Poisson's ratio, thermal expansion coefficient and coating thickness of the coatings have noticeable impacts on the sensing characteristics of the coated FBG. It is noted that (i) there is an extreme value for the influence of the elastic modulus on temperature sensitivity; (ii) temperature sensitivity increases with the increase of Poisson's ratio and thermal expansion coefficient; (iii) with the increase of the coating thickness, the temperature sensitivity increases first then reaches a plateau asymptotically. To validate the simulation results, several FBGs were coated with copper, nickel, cobalt, copper-zinc, and Ni-ZrO2, and subsequently the associated temperature sensitivities were measured using a network analyzer as well as a water bath. The results show that the simulation results agree well with that of the experiments, with the errors up to 5.49%.

  12. Phase evolution of vanadium oxides obtained through temperature programmed calcinations of ammonium vanadate in hydrogen atmosphere and their humidity sensing properties

    Energy Technology Data Exchange (ETDEWEB)

    Akande, A.A. [DST/CSIR National Centre for Nano-Structured Materials, P O Box 395, Pretoria, 0001 (South Africa); University of Limpopo, Department of Physics, P/Bag X1106, Sovenga, 0727 (South Africa); Linganiso, E.C.; Dhonge, B.P. [DST/CSIR National Centre for Nano-Structured Materials, P O Box 395, Pretoria, 0001 (South Africa); Rammutla, K.E. [University of Limpopo, Department of Physics, P/Bag X1106, Sovenga, 0727 (South Africa); Machatine, A.; Prinsloo, L.; Kunert, H. [School of Physics, University of Pretoria, Pretoria, 0002 (South Africa); Mwakikunga, B.W., E-mail: bmwakikunga@csir.co.za [DST/CSIR National Centre for Nano-Structured Materials, P O Box 395, Pretoria, 0001 (South Africa)

    2015-02-01

    The possibility of obtaining vanadium dioxide (VO{sub 2}) [wherein the vanadium ionic state is 4{sup +}] from a precursor of ammonium metavanadate (NH{sub 4}VO{sub 3}) bearing the ion V{sup 5+} is investigated. The reduction is carried out by calcining the NH{sub 4}VO{sub 3} powders in similar concentrations of H{sub 2} flow at varying temperatures. The resulting powders have been studied by several techniques including XRD, Raman spectroscopy, FTIR, TEM, BET and DSC. It is found that remnants of bright yellow V{sup 5+} still exist up to calcination temperatures of 100 °C after which the sky-blue VO{sub 2} dominates at calcination temperatures of 150 °C–250 °C. There is a population surge of metastable dark-blue V{sub 6}O{sub 13} (where V is in between V{sup 4+} and V{sup 5+} ionic states) between 250 °C and 300 °C. However above 350 °C the material reverts to the stable V{sup 5+} in the yellow–orange V{sub 2}O{sub 5}. XPS/EDS and VSM confirm the order of appearance to be VO{sub 2}(150 °C) → V{sub 6}O{sub 13}(200 °C) → V{sub 2}O{sub 5} (350 °C). - Highlights: • Validated the theoretical mass losses at each temperature of NH{sub 4}VO{sub 3} with TGA. • Confirmed mechanisms of formation of various stoichiometries of VO{sub x} from NH{sub 4}VO{sub 3}. • Determined the evolution of VO{sub 2}, V{sub 6}O{sub 13} and V{sub 2}O{sub 5} with temperature. • Phase diagram of VO{sub 2}, V{sub 6}O{sub 13} and V{sub 2}O{sub 5} by VSM, XPS/EDS, XRD and Raman spectra. • Comparative response of VO{sub 2}, V{sub 6}O{sub 13} and V{sub 2}O{sub 5} to humidity.

  13. A Self-Referencing Intensity-Based Fiber Optic Sensor with Multipoint Sensing Characteristics

    Directory of Open Access Journals (Sweden)

    Sang-Jin Choi

    2014-07-01

    Full Text Available A self-referencing, intensity-based fiber optic sensor (FOS is proposed and demonstrated. The theoretical analysis for the proposed design is given, and the validity of the theoretical analysis is confirmed via experiments. We define the measurement parameter, X, and the calibration factor, β, to find the transfer function, , of the intensity-based FOS head. The self-referencing and multipoint sensing characteristics of the proposed system are validated by showing the measured  and relative error versus the optical power attenuation of the sensor head for four cases: optical source fluctuation, various remote sensing point distances, fiber Bragg gratings (FBGs with different characteristics, and multiple sensor heads with cascade and/or parallel forms. The power-budget analysis and limitations of the measurement rates are discussed, and the measurement results of fiber-reinforced plastic (FRP coupon strain using the proposed FOS are given as an actual measurement. The proposed FOS has several benefits, including a self-referencing characteristic, the flexibility to determine FBGs, and a simple structure in terms of the number of devices and measuring procedure.

  14. Tapered Optical Fiber Humidity Sensor Coated with Nano-crystalline ZnO Doped with KCI

    Directory of Open Access Journals (Sweden)

    Sivacoumar Rajalingam

    2015-03-01

    Full Text Available In this research study we have targeted to fabricate a tapered optical fiber coated with zinc oxide doped with KCl to improve the humidity sensing capability of zinc oxide. The optical fiber was tapered through chemical etching method by HF acid (49.5%. The nano-crystalline Zinc Oxide (ZnO was synthesized using single molecular precursor method doped with KCl. The resulting material was characterized with Fourier Transform Infrared spectroscopy (FTIR, X-Ray Diffractometry (XRD and Scanning Electron Microscopy (SEM. The sensing mechanism of this sensor is based on the change of the optical properties of the coating when the relative humidity increases. The humidity sensing characteristic has been estimated by measuring the Optical Permeability (OP as a function of percentage of Relative Humidity (%RH in the ranging from 5 to 98% inside a closed chamber. The tapered optical fiber tested with an overlay coating at the optimal working point achieves better sensitivity. The experimental results show that the 5.7 wt% KCl doped ZnO nano-fibers hold super-rapid response and recovery than normal ZnO coating.

  15. Sensing Characteristics of A Precision Aligner Using Moire Gratings for Precision Alignment System

    Institute of Scientific and Technical Information of China (English)

    ZHOU Lizhong; Hideo Furuhashi; Yoshiyuki Uchida

    2001-01-01

    Sensing characteristics of a precision aligner using moire gratings for precision alignment sysem has been investigated. A differential moire alignment system and a modified alignment system were used. The influence of the setting accuracy of the gap length and inclination of gratings on the alignment accuracy has been studied experimentally and theoretically. Setting accuracy of the gap length less than 2.5μm is required in modified moire alignment. There is no influence of the gap length on the alignment accuracy in the differential alignment system. The inclination affects alignment accuracies in both differential and modified moire alignment systems.

  16. Single-Walled Carbon Nanotube Network Field Effect Transistor as a Humidity Sensor

    Directory of Open Access Journals (Sweden)

    Prasantha R. Mudimela

    2012-01-01

    Full Text Available Single-walled carbon nanotube network field effect transistors were fabricated and studied as humidity sensors. Sensing responses were altered by changing the gate voltage. At the open channel state (negative gate voltage, humidity pulse resulted in the decrease of the source-drain current, and, vice versa, the increase in the source-drain current was observed at the positive gate voltage. This effect was explained by the electron-donating nature of water molecules. The operation speed and signal intensity was found to be dependent on the gate voltage polarity. The positive or negative change in current with humidity pulse at zero-gate voltage was found to depend on the previous state of the gate electrode (positive or negative voltage, respectively. Those characteristics were explained by the charge traps in the gate dielectric altering the effective gate voltage, which influenced the operation of field effect transistor.

  17. A hybrid humidity sensor using optical waveguides on a quartz crystal microbalance

    Energy Technology Data Exchange (ETDEWEB)

    Shinbo, Kazunari, E-mail: kshinbo@eng.niigata-u.ac.j [Graduate School of Science and Technology, Niigata University, 2-8050 Ikarashi, Nishi-ku, Niigata City, Niigata 950-2181 (Japan); Center for Transdisciplinary Research, Niigata University, 2-8050 Ikarashi, Nishi-ku, Niigata City, Niigata 950-2181 (Japan); Otuki, Shunya; Kanbayashi, Yuichi [Graduate School of Science and Technology, Niigata University, 2-8050 Ikarashi, Nishi-ku, Niigata City, Niigata 950-2181 (Japan); Ohdaira, Yasuo [Graduate School of Science and Technology, Niigata University, 2-8050 Ikarashi, Nishi-ku, Niigata City, Niigata 950-2181 (Japan); Center for Transdisciplinary Research, Niigata University, 2-8050 Ikarashi, Nishi-ku, Niigata City, Niigata 950-2181 (Japan); Baba, Akira [Center for Transdisciplinary Research, Niigata University, 2-8050 Ikarashi, Nishi-ku, Niigata City, Niigata 950-2181 (Japan); Kato, Keizo; Kaneko, Futao [Graduate School of Science and Technology, Niigata University, 2-8050 Ikarashi, Nishi-ku, Niigata City, Niigata 950-2181 (Japan); Center for Transdisciplinary Research, Niigata University, 2-8050 Ikarashi, Nishi-ku, Niigata City, Niigata 950-2181 (Japan); Miyadera, Nobuo [Hitachi Chemical Co., Ltd., 48 Wadai, Tsukuba City, Ibaraki 300-4247 (Japan)

    2009-11-30

    In this study, slab and ridge optical waveguides (OWGs) made of fluorinated polyimides were deposited on a quartz crystal microbalance (QCM), and hybrid sensors using OWG spectroscopy and the QCM technique were prepared. Polyvinyl alcohol (PVA) film with CoCl{sub 2} was deposited on the OWGs, and the characteristics of humidity sensing were investigated. A prism coupler was used to enter a He-Ne laser beam ({lambda} = 632.8 nm) to the slab OWG. The output light intensity markedly changed due to chromism of the CoCl{sub 2} as a result of humidity sorption, and this change was dependent on the incident angle of the laser beam to the slab OWG. During the measurement of output light, the QCM frequency was simultaneously monitored. The humidity dependence of the sensor with the slab OWG was also investigated in the range from 15 to 85%. For the sensor with the ridge OWG, white light was entered by butt-coupling, and the characteristics of humidity sensing were investigated by observing the output light spectrum and the QCM frequency.

  18. [Studies on spectral characteristics of solid propellant by remote sensing FTIR].

    Science.gov (United States)

    Li, Yan; Huang, Zhong-hua; Zhou, Xue-tie; Wang, Jun-de

    2005-02-01

    The infrared spectral characteristics of high-intensity IR solid propellant were measured in this paper using a Bruker EQUINOX55 remote sensing FTIR spectrometer. The emission spectra of the combustion flame were recorded in the range of 4700-1800 cm(-1) with a spectral resolution of 4 cm(-1). The combustion temperatures of solid propellant at the burning time of 0, 9, 18, 27 and 36 s calculated from the molecular rotation-vibration spectra were 1992.5, 1610.9, 2294.4, 2361.1 and 1916.9 K, respectively. Moreover, the spectral radiance distributions of the high IR flare material at different times were given, and the combustion product concentrations of HCl, HF, CO2 and CO were determined quantitatively. Results showed that remote sensing FTIR is a potential technology that can be applied to the measurement of IR spectral characteristics, especially to the identification of the IR objects, guidance and anti-guidance in the military, and the modification of the make-up of solid propellant.

  19. Humidity Regulating Characteristics Analysis of Air-cooled Proton Exchange Membrane Fuel Cells%风冷式质子交换膜燃料电池湿度调节特性分析

    Institute of Scientific and Technical Information of China (English)

    可荣硕; 许世蒙

    2012-01-01

    质子交换膜燃料电池(Proton Exchange Membrane Fuel Cells,PEMFC)的内部环境是影响电堆性能及寿命的重要因素,针对风冷式燃料电池运行特点,在分析燃料电池温、湿度环境控制方式的基础上,研究了反应风速对系统湿度特性的影响,提出了反应风速与温度对湿度进行联合控制的方式,并通过3kW小型燃料电池样机实验,验证了该方法的可行性。%The inner environment of Proton Exchange Membrane Fuel Cells (PEMFC) has great influence on the property and service life of the pile. Aiming at the operation features of air-cooled PEMFC, on the basis of analyzing the control mode of fuel cells' temperature and humidity, the authors study the influence on humidity characteristics by reaction wind speed and propose a wind speed/temperature joint control of humidity. The feasibility of the method is validated through experiments on 3 kW small PEMFC prototype.

  20. Comparisons on temperature and hysteresis characteristics of three capacitive humidity sensors%3种型号湿敏电容传感器温度和迟滞特性的分析比较

    Institute of Scientific and Technical Information of China (English)

    杜智涛; 魏洪峰; 姜明波; 张志标

    2012-01-01

    In order to understand measuring characteristics of capacitive humidity sensor such as accuracy, hysteresis and temperature coefficient, this paper tests three different capacitive humidity sensors. The errors of measurement value and hysteresis are compared under different temperature conditions. The results indicate that there are quite differences on temperature and hysteresis among these three sensors, which is available for the choice and use of capacitive humidity sensors.%为掌握目前气象行业使用的湿敏电容湿度传感器的测量准确度、迟滞误差、温度系数等测量特性,文章对3种不同型号的湿度传感器进行了测试,对不同温度点下传感器的相对湿度测量示值误差和迟滞误差进行了分析和比较,测试和分析结果表明不同传感器的温度和迟滞特性有较大的差异。其分析比较的结果对湿度传感器的选择和使用具有参考价值。

  1. Coating based Fiber Bragg Grating humidity sensor array

    NARCIS (Netherlands)

    Cheng, L.K.; Boersma, A.; Jansen, T.H.

    2012-01-01

    A coating based FBG humidity sensor is developed for distributed humidity sensing. The sensitivity of the coated FBG is optimized by varying the chemical composition and the thickness of the coating. A sensitivity of ~2 pm/%RH and a rapid response are demonstrated. The composition of the coating can

  2. Clinker mineral hydration at reduced relative humidities

    DEFF Research Database (Denmark)

    Jensen, Ole Mejlhede; Hansen, Per Freiesleben; Lachowski, Eric E.;

    1999-01-01

    Vapour phase hydration of purl cement clinker minerals at reduced relative humidities is described. This is relevant to modern high performance concrete that may self-desiccate during hydration and is also relevant to the quality of the cement during storage. Both the oretical considerations...... and experimental data are presented showing that C(3)A can hydrate at lower humidities than either C3S or C2S. It is suggested that the initiation of hydration during exposure to water vapour is nucleation controlled. When C(3)A hydrates at low humidity, the characteristic hydration product is C(3)AH(6...

  3. Inhomogeneous Oxygen Vacancy Distribution in Semiconductor Gas Sensors: Formation, Migration and Determination on Gas Sensing Characteristics.

    Science.gov (United States)

    Liu, Jianqiao; Gao, Yinglin; Wu, Xu; Jin, Guohua; Zhai, Zhaoxia; Liu, Huan

    2017-08-10

    The density of oxygen vacancies in semiconductor gas sensors was often assumed to be identical throughout the grain in the numerical discussion of the gas-sensing mechanism of the devices. In contrast, the actual devices had grains with inhomogeneous distribution of oxygen vacancy under non-ideal conditions. This conflict between reality and discussion drove us to study the formation and migration of the oxygen defects in semiconductor grains. A model of the gradient-distributed oxygen vacancy was proposed based on the effects of cooling rate and re-annealing on semiconductive thin films. The model established the diffusion equations of oxygen vacancy according to the defect kinetics of diffusion and exclusion. We described that the steady-state and transient-state oxygen vacancy distributions, which were used to calculate the gas-sensing characteristics of the sensor resistance and response to reducing gases under two different conditions. The gradient-distributed oxygen vacancy model had the applications in simulating the sensor performances, such as the power law, the grain size effect and the effect of depletion layer width.

  4. Inhomogeneous Oxygen Vacancy Distribution in Semiconductor Gas Sensors: Formation, Migration and Determination on Gas Sensing Characteristics

    Directory of Open Access Journals (Sweden)

    Jianqiao Liu

    2017-08-01

    Full Text Available The density of oxygen vacancies in semiconductor gas sensors was often assumed to be identical throughout the grain in the numerical discussion of the gas-sensing mechanism of the devices. In contrast, the actual devices had grains with inhomogeneous distribution of oxygen vacancy under non-ideal conditions. This conflict between reality and discussion drove us to study the formation and migration of the oxygen defects in semiconductor grains. A model of the gradient-distributed oxygen vacancy was proposed based on the effects of cooling rate and re-annealing on semiconductive thin films. The model established the diffusion equations of oxygen vacancy according to the defect kinetics of diffusion and exclusion. We described that the steady-state and transient-state oxygen vacancy distributions, which were used to calculate the gas-sensing characteristics of the sensor resistance and response to reducing gases under two different conditions. The gradient-distributed oxygen vacancy model had the applications in simulating the sensor performances, such as the power law, the grain size effect and the effect of depletion layer width.

  5. Temporal-spatial characteristics of vegetation cover and desertification of China by using remote sensing data

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Based on the NOAA advanced very high resolution radiometer (NOAA-AVHRR) remote sensing data of 1982~1999, the normalized difference vegetation index (NDVI) reflecting the surface vegetation cover has been obtained. Using the empirical orthogonal function analysis, the temporal-spatial eigenvectors of NDVI are given, and the characteristics of the spatial distribution of vegetation cover and its temporal variation together with the desertification of China are analyzed. It is found that the surface vegetation cover has seriously deteriorated in most part of China since 1995, along with the intensified desertification. All these are mainly caused by human activities although the climate change is responsible for the damage of surface vegetation cover to some extent.

  6. Investigation of the Optical and Sensing Characteristics of Nanoparticle Arrays for High Temperature Applications

    Science.gov (United States)

    Dharmalingam, Gnanaprakash

    The monitoring of polluting gases such as CO and NOx emitted from gas turbines in power plants and aircraft is important in order to both reduce the effects of such gases on the environment as well as to optimize the performance of the respective power system. The need for emissions monitoring systems is further realized from increased regulatory requirements that are being instituted as a result of the environmental impact from increased air travel. Specifically, it is estimated that the contributions from aircraft emissions to total NOx emissions will increase from 4% to 17% between 2008 and 2020. Extensive fuel cost savings as well as a reduced environmental impact would therefore be realized if this increased air traffic utilized next generation jet turbines which used a emission/performance control sensing system. These future emissions monitoring systems must be sensitive and selective to the emission gases, reliable and stable under harsh environmental conditions where the operation temperatures are in excess of 500 °C within a highly reactive environment. Plasmonics based chemical sensors which use nanocomposites comprised of a combination of gold nano particles and Yttria Stabilized Zirconia (YSZ) has enabled the sensitive (PPM) and stable detection (100s of hrs) of H2, NO2 and CO at temperatures of 500 °C. The detection method involves measuring the change in the localized Surface Plasmon Resonance (LSPR) characteristics of the Au- YSZ nano composite and in particular, the plasmon peak position. Selectivity remains a challenging parameter to optimize and a layer by layer sputter deposition approach has been recently demonstrated to modify the resulting sensing properties through a change in the morphology of the deposited films. The material properties of the films have produced a unique sensing behavior in terms of a preferential response to H2 compared to CO. Although this is a very good benefit, it is expected that further enhancements would be

  7. Surface Properties and Characteristics of Mars Landing Sites from Remote Sensing Data and Ground Truth

    Science.gov (United States)

    Golombek, M. P.; Haldemann, A. F.; Simpson, R. A.; Furgason, R. L.; Putzig, N. E.; Huertas, A.; Arvidson, R. E.; Heet, T.; Bell, J. F.; Mellon, M. T.; McEwen, A. S.

    2008-12-01

    Surface characteristics at the six sites where spacecraft have successfully landed on Mars can be related favorably to their signatures in remotely sensed data from orbit and from the Earth. Comparisons of the rock abundance, types and coverage of soils (and their physical properties), thermal inertia, albedo, and topographic slope all agree with orbital remote sensing estimates and show that the materials at the landing sites can be used as ground truth for the materials that make up most of the equatorial and mid- to moderately high-latitude regions of Mars. The six landing sites sample two of the three dominant global thermal inertia and albedo units that cover ~80% of the surface of Mars. The Viking, Spirit, Mars Pathfinder, and Phoenix landing sites are representative of the moderate to high thermal inertia and intermediate to high albedo unit that is dominated by crusty, cloddy, blocky or frozen soils (duricrust that may be layered) with various abundances of rocks and bright dust. The Opportunity landing site is representative of the moderate to high thermal inertia and low albedo surface unit that is relatively dust free and composed of dark eolian sand and/or increased abundance of rocks. Rock abundance derived from orbital thermal differencing techniques in the equatorial regions agrees with that determined from rock counts at the surface and varies from ~3-20% at the landing sites. The size-frequency distributions of rocks >1.5 m diameter fully resolvable in HiRISE images of the landing sites follow exponential models developed from lander measurements of smaller rocks and are continuous with these rock distributions indicating both are part of the same population. Interpretation of radar data confirms the presence of load bearing, relatively dense surfaces controlled by the soil type at the landing sites, regional rock populations from diffuse scattering similar to those observed directly at the sites, and root-mean-squared slopes that compare favorably

  8. Academics explore humidity's benefits.

    Science.gov (United States)

    Mortimer, Dave

    2008-11-01

    The effects of humidification on hospital superbugs are being explored by some of the UK's top academics, in what Dave Mortimer, national sales manager for Vapac Humidity Control, explains are the UK's first such studies.

  9. Effects of palladium on the optical and hydrogen sensing characteristics of Pd-doped ZnO nanoparticles

    Directory of Open Access Journals (Sweden)

    Anh-Thu Thi Do

    2014-08-01

    Full Text Available The effect of palladium doping of zinc oxide nanoparticles on the photoluminescence (PL properties and hydrogen sensing characteristics of gas sensors is investigated. The PL intensity shows that the carrier dynamics coincides with the buildup of the Pd-related green emission. The comparison between the deep level emission and the gas sensing response characteristics allows us to suggest that the dissociation of hydrogen takes place at PdZn-vacancies ([Pd 2+(4d9]. The design of this sensor allows for a continuous monitoring in the range of 0–100% LEL H2 concentration with high sensitivity and selectivity.

  10. Dip-coated hydrotungstite thin films as humidity sensors

    Indian Academy of Sciences (India)

    G V Kunte; Ujwala Ail; S A Shivashankar; A M Umarji

    2005-06-01

    Thin films of a hydrated phase of tungsten oxide, viz. hydrotungstite, have been prepared on glass substrates by dip-coating method using ammonium tungstate precursor solution. X-ray diffraction shows the films to have a strong -axis orientation. The resistance of the films is observed to be sensitive to the humidity content of the ambient, indicating possible applications of these films for humidity sensing. A homemade apparatus designed to measure the d.c. electrical resistance in response to exposure to controlled pulses of a sensing gas has been employed to evaluate the sensitivity of the hydrotungstite films towards humidity.

  11. Genotype-environment interaction of maternal influence characteristics in Nellore cattle bred in the Brazilian humid tropical regions by reaction norm

    Directory of Open Access Journals (Sweden)

    Jorge Luís Ferreira

    2015-08-01

    Full Text Available Reaction Norm (RN is the study of genotype-environment interaction (GxE that complies with alternative ways of genotypes within different environments. This study was carried out to verify GxE by a reaction norm model of weights at 120 (W120 and 210 (W210 days of age in Nellore cattle raised in the Humid Tropical Regions of Brazil. Environmental gradients were obtained by solutions of contemporary groups which were fitted as co-variables in the random regression model via reaction norms. Mean weight at 120 days of age was 127.97 kg, and environmental gradients ranged between -27 and +26 kg. Average was 185.60 kg at 210 days of age and gradients ranged from -54 to +55 kg. Scale changes in the breeding values and heritability estimates occurred along the gradients for the two weights; the genetic correlations between breeding value breeding values were also similar for both weights. These correlations were high between the close gradients, and low to even negative between extreme environments. Slopes representing the environmental sensitivity were high, with changes of scale and changes in classification of ten bulls with a great numbers of calves for the two traits. When regression slopes of the ten bulls with the highest breeding value breeding values were evaluated, these values were different in W120 from those in W210, perhaps due to the greater influence of maternal effect on W120. These results characterize the influence of GxE on the pre-weaning weights of animals in the humid tropical regions of Brazil. Due to this, it is possible to get greater precision on the predictions of the animals breeding values breeding value. A less biased selection and a greater genetic progress occurred.

  12. Identifying Changing Snow Cover Characteristics in Central Asia between 1986 and 2014 from Remote Sensing Data

    Directory of Open Access Journals (Sweden)

    Andreas J. Dietz

    2014-12-01

    Full Text Available Central Asia consists of the five former Soviet States Kazakhstan, Kyrgyzstan, Tajikistan, Turkmenistan, and Uzbekistan, therefore comprising an area of ~4 Mio km2. The continental climate is characterized by hot and dry summer months and cold winter seasons with most precipitation occurring as snowfall. Accordingly, freshwater supply is strongly depending on the amount of accumulated snow as well as the moment of its release after snowmelt. The aim of the presented study is to identify possible changes in snow cover characteristics, consisting of snow cover duration, onset and offset of snow cover season within the last 28 years. Relying on remotely sensed data originating from medium resolution imagers, these snow cover characteristics are extracted on a daily basis. The resolution of 500–1000 m allows for a subsequent analysis of changes on the scale of hydrological sub-catchments. Long-term changes are identified from this unique dataset, revealing an ongoing shift towards earlier snowmelt within the Central Asian Mountains. This shift can be observed in most upstream hydro catchments within Pamir and Tian Shan Mountains and it leads to a potential change of freshwater availability in the downstream regions, exerting additional pressure on the already tensed situation.

  13. Analysis of Spectral Characteristics Based on Optical Remote Sensing and SAR Image Fusion

    Institute of Scientific and Technical Information of China (English)

    Weiguo LI; Nan JIANG; Guangxiu GE

    2014-01-01

    Because of cloudy and rainy weather in south China, optical remote sens-ing images often can't be obtained easily. With the regional trial results in Baoying, Jiangsu province, this paper explored the fusion model and effect of ENVISAT/SAR and HJ-1A satel ite multispectral remote sensing images. Based on the ARSIS strat-egy, using the wavelet transform and the Interaction between the Band Structure Model (IBSM), the research progressed the ENVISAT satel ite SAR and the HJ-1A satel ite CCD images wavelet decomposition, and low/high frequency coefficient re-construction, and obtained the fusion images through the inverse wavelet transform. In the light of low and high-frequency images have different characteristics in differ-ent areas, different fusion rules which can enhance the integration process of self-adaptive were taken, with comparisons with the PCA transformation, IHS transfor-mation and other traditional methods by subjective and the corresponding quantita-tive evaluation. Furthermore, the research extracted the bands and NDVI values around the fusion with GPS samples, analyzed and explained the fusion effect. The results showed that the spectral distortion of wavelet fusion, IHS transform, PCA transform images was 0.101 6, 0.326 1 and 1.277 2, respectively and entropy was 14.701 5, 11.899 3 and 13.229 3, respectively, the wavelet fusion is the highest. The method of wavelet maintained good spectral capability, and visual effects while improved the spatial resolution, the information interpretation effect was much better than other two methods.

  14. Research on remote sensing identification of rural abandoned homesteads using multiparameter characteristics method

    Science.gov (United States)

    Xu, Saiping; Zhao, Qianjun; Yin, Kai; Cui, Bei; Zhang, Xiupeng

    2016-10-01

    Hollow village is a special phenomenon in the process of urbanization in China, which causes the waste of land resources. Therefore, it's imminent to carry out the hollow village recognition and renovation. However, there are few researches on the remote sensing identification of hollow village. In this context, in order to recognize the abandoned homesteads by remote sensing technique, the experiment was carried out as follows. Firstly, Gram-Schmidt transform method was utilized to complete the image fusion between multi-spectral images and panchromatic image of WorldView-2. Then the fusion images were made edge enhanced by high pass filtering. The multi-resolution segmentation and spectral difference segmentation were carried out to obtain the image objects. Secondly, spectral characteristic parameters were calculated, such as the normalized difference vegetation index (NDVI), the normalized difference water index (NDWI), the normalized difference Soil index (NDSI) etc. The shape feature parameters were extracted, such as Area, Length/Width Ratio and Rectangular Fit etc.. Thirdly, the SEaTH algorithm was used to determine the thresholds and optimize the feature space. Furthermore, the threshold classification method and the random forest classifier were combined, and the appropriate amount of samples were selected to train the classifier in order to determine the important feature parameters and the best classifier parameters involved in classification. Finally, the classification results was verified by computing the confusion matrix. The classification results were continuous and the phenomenon of salt and pepper using pixel classification was avoided effectively. In addition, the results showed that the extracted Abandoned Homesteads were in complete shapes, which could be distinguished from those confusing classes such as Homestead in Use and Roads.

  15. Developing a thermal characteristic index for lithology identification using thermal infrared remote sensing data

    Science.gov (United States)

    Wei, Jiali; Liu, Xiangnan; Ding, Chao; Liu, Meiling; Jin, Ming; Li, Dongdong

    2017-01-01

    In remote sensing petrology fields, studies have mainly concentrated on spectroscopy remote sensing research, and methods to identify minerals and rocks are mainly based on the analysis and enhancement of spectral features. Few studies have reported the application of thermodynamics for lithology identification. This paper aims to establish a thermal characteristic index (TCI) to explore rock thermal behavior responding to defined environmental systems. The study area is located in the northern Qinghai Province, China, on the northern edge of the Qinghai-Tibet Plateau, where mafic-ultramafic rock, quartz-rich rock, alkali granite rock and carbonate rock are well exposed; the pixel samples of these rocks and vegetation were obtained based on relevant indices and geological maps. The scatter plots of TCI indicate that mafic-ultramafic rock and quartz-rich rock can be well extracted from other surface objects when interference from vegetation is lower. On account of the complexity of environmental systems, three periods of TCI were used to construct a three-dimensional scatter plot, named the multi-temporal thermal feature space (MTTFS) model. Then, the Bayes discriminant analysis algorithm was applied to the MTTFS model to extract rocks quantitatively. The classification accuracy of mafic-ultramafic rock is more than 75% in both training data and test data, which suggests TCI can act as a sensitive indicator to distinguish rocks and the MTTFS model can accurately extract mafic-ultramafic rock from other surface objects. We deduce that the use of thermodynamics is promising in lithology identification when an effective index is constructed and an appropriated model is selected.

  16. 圣女果分段式变温变湿热风干燥特性%Dried characteristics of cherry tomatoes using temperature and humidity by stages changed hot-air drying method

    Institute of Scientific and Technical Information of China (English)

    王庆惠; 李忠新; 杨劲松; 谢龙; 张世湘; 高振江

    2014-01-01

    Cherry tomato decays easily. Generally, it can be preserved only for 5-7days under normal pressure and temperature. The dehydration of cherry tomatoes into dried or preserved fruits can prolong their shelf life and enrich the market of the fruit. Currently, cherry tomatoes is dehydrated through natural drying. The advantage of this method is simple, and low cost. But the drying time is long and is affected by the climate and sanitary conditions. The product quality is difficult to control. In order to shorten the drying time and prevent mildew, cherry tomatoes are often soaked or sprayed with the alkaline solution. These chemicals are bad for our health. Multi-stage temperature-and-humidity drying is conducted through the material drying characteristics. This method can speed up the drying rate, improve drying quality, and reduce energy consumption. It has been successfully applied for apricot,lyceum barbarum, grapes and other materials. In this study, internal recycling hot-air drying technology was employed for the drying of cherry tomatoes. The effects of drying temperatures, humidity, drying stages and slicing forms on the drying characteristics and the appearance quality of the cherry tomatoes were investigated. Each experiment was composed of four drying stages. The drying temperatures were fixed, the humidity of the environment was changed in processⅠ,Ⅱ andⅢ. The drying temperature was low, the humidity was high at the beginning of processⅣ. Gradually, the temperature was raised, the humidity was reduced. At the end of the process, the drying temperature was higher, the humidity was lower compared with their values at the beginning. The experimental results indicated that pre-heated and falling rate periods exist during the drying of cherry tomato. Previous studies only shown falling rate period. The increase in temperature and humidity has bad effects on the nutrition, color and the appearance quality of cherry tomato. Even though cherry tomato can

  17. Investigating the Spatial Characteristics of Forest Fire in North Korea using Remote Sensing and GIS

    Science.gov (United States)

    RI, J.; Lee, K. S.

    2015-12-01

    Forest fires cause billions of dollar damage to property and the environment in the world every year. In North Korea (NK) forest fire occurred frequently in the entire region with the exception of the western plains and massive forest fires broke out throughout NK in May 2004. Furthermore, few researches focused on NK forest fire because of data unavailability and inaccessibility to the region. Operational fire monitoring over large areas can be approached through satellite remote sensing (RS). Thus, it is necessary to investigate the area damaged by forest fire and get information of damaged area for restoration of forest in NK after reunification. Therefore, the purpose of this study is to identify the location of forest fire and to estimate the damaged area by forest fire and finally to detect the landscape change after forest fire in Gangwon and South Hamgyong Province, NK using satellite RS data. In this study, we will investigate the area damaged by forest fire and investigate the spatial characteristics of forest fire in Gangwon and South Hamgyong Province using RS. Landsat data from USGS Were preprocessed (band composition), NBR and dNBR are calculated for figuring out the burned area and investigating the burn severity (BS) in burned area. NBR and dNBR (differenced NBR) are mostly useful to estimate BS by forest fires damage from RS data. The dNBR was then calculated by subtracting the post-fire NBR from the pre-fire NBR: The burned area from Landsat data processing were stored in GIS database to be retrieved and analyzed to figure out the chronological change pattern of forest fire damaged area. Finally, the spatiotemporal characteristics of forest fire in NK were analyzed and discussed to provide the information for restoring forest fire damaged area after reunification.

  18. Spatially Explicit Forest Characteristics of Europe Integrating NFI and Remote Sensing Data

    Science.gov (United States)

    Moreno, A. L. S.; Neumann, M.; Hasenauer, H.

    2015-12-01

    Seeing the forest through the trees in Europe is easier said than done. European forest data is nationally collected using different methodologies and sampling techniques. This data can be difficult to obtain, and if made available often lacks spatial information and might only be provided in the local language. This makes analyzing forests in Europe difficult. The reporting systems of Food and Agriculture Organization (FAO) and the European Forestry Institute (EFI) permit several acquisition and calculation methodologies which lead to difficulties in comparing country level data. We have collected spatially explicit national forest inventory (NFI) data from 13 countries in Europe and harmonized these datasets. Using this data along with remote sensing data products we have derived spatially explicit forest characteristics maps of Europe on a 0.017o resolution representing the time period 2000-2010. We have created maps for every NFI variable in our dataset including carbon stock, forest age, forest height, volume, basal area, etc. Cross-validating this data shows that this method produces accurate results for most variables while variables pertaining to forest cover type have lower accuracy. This data is in line with data from FAO and EFI in most cases. However, our dataset allows us to identify large incongruities quickly in FAO and EFI data. Our spatially explicit data is also accurate at predicting forest characteristics in areas where we have no NFI data. This data set provides a consistent harmonized view of the state of European forests in a way hitherto not possible, giving researchers the ability to analyze forests spatially across the entire continent. This method can also be useful for those researching areas that have little or no NFI data or areas where data acquisition is difficult or impossible. This data can also quickly give policy makers a greater view of how forest management practices have shaped our current European forests.

  19. Functional characteristics of a new electrolarynx "Evada" having a force sensing resistor sensor.

    Science.gov (United States)

    Choi, H S; Park, Y J; Lee, S M; Kim, K M

    2001-12-01

    Electrolarynxes have been used as one of the rehabilitation methods for laryngectomees. Earlier electrolarynxes could not alter frequency and intensity simultaneously during conversation. Recently, we developed an electrolarynx named "Evada" (prototype so far) using a force sensing resistor (FSR) sensor that can control both frequency and intensity simultaneously during conversation. Employing three types of electrolarynxes (Evada, Servox-inton, Nu-vois), this study was undertaken to examine the functional characteristics of Evada for the normal control group and for laryngectomess. Five laryngectomees and five normal adults were asked to express three sentences (declarative sentence, "You stay here.", interrogative sentence, "You stay here?", and imperative sentence, "You! Stay here.") using three types of electrolarynxes. Frequency and intensity changes between the first and last vowels in the three sentences were calculated and analyzed statistically by paired t test. The frequency changes in the interrogative and imperative sentences were more prominent in Evada than in Servox-inton and Nu-vois. The intensity changes in the interrogative and imperative sentences were also more prominent in Evada than in Servox-inton and Nu-vois. Evada controls frequency and/or intensity by having the subject press the control button(s). Therefore, Evada appears to be better at producing intonation and contrastive stress than Nu-vois and Servox-inton.

  20. Sensing Responses Based on Transfer Characteristics of InAs Nanowire Field-Effect Transistors.

    Science.gov (United States)

    Tseng, Alex C; Lynall, David; Savelyev, Igor; Blumin, Marina; Wang, Shiliang; Ruda, Harry E

    2017-07-16

    Nanowire-based field-effect transistors (FETs) have demonstrated considerable promise for a new generation of chemical and biological sensors. Indium arsenide (InAs), by virtue of its high electron mobility and intrinsic surface accumulation layer of electrons, holds properties beneficial for creating high performance sensors that can be used in applications such as point-of-care testing for patients diagnosed with chronic diseases. Here, we propose devices based on a parallel configuration of InAs nanowires and investigate sensor responses from measurements of conductance over time and FET characteristics. The devices were tested in controlled concentrations of vapour containing acetic acid, 2-butanone and methanol. After adsorption of analyte molecules, trends in the transient current and transfer curves are correlated with the nature of the surface interaction. Specifically, we observed proportionality between acetic acid concentration and relative conductance change, off current and surface charge density extracted from subthreshold behaviour. We suggest the origin of the sensing response to acetic acid as a two-part, reversible acid-base and redox reaction between acetic acid, InAs and its native oxide that forms slow, donor-like states at the nanowire surface. We further describe a simple model that is able to distinguish the occurrence of physical versus chemical adsorption by comparing the values of the extracted surface charge density. These studies demonstrate that InAs nanowires can produce a multitude of sensor responses for the purpose of developing next generation, multi-dimensional sensor applications.

  1. Growth characteristics of multipurpose tree species,crop productivity and soil properties in agroforestry systems under subtropical humid climate in India

    Institute of Scientific and Technical Information of China (English)

    M. Datta; N. P. Singh

    2007-01-01

    Multipurpose tree species (MPTs) were studied in an agroforestry arboretum under subtropical humid climate in Northeast India. Out of 12 MPTs planted under agroforestry systems, Acacia auriculiformis in spacing of 2 m × 2 m (2500 stems·hm-2) could have the potentiality to meet the timber/fuelwood requirement due to its high wood production of 635 m3·hm-2 with mean annual increment (MAI) of 2.54×10-2· m3·tree1·a-1 in a short rotation period of 10 years. Thus, A. Auriculiformis is a short rotation forest tree species suitable to grow in subtropical humid climate. On the other hand, at 16 years of age, Eucalyptus hybrid and Michelia champaca in spacing of 3 m × 3 m (1111 stems·hm-2) produced appreciably high timber volume of 315 m3·hm-2 and 165 m3·hm-2 with MAI of 1.77×10-2 m3·tree-1·a-1 and 0.92×10-2 m3·tree-1·a-1, respectively. At 16 years of age, Gmelina arborea produced a timber volume of 147 m3·hm-2 with MAI of 1.47×10-2 m3·tree-1·a-1 followed by Samania saman (140 m3·hm-2), Albizzia procera (113 m3·hm-2) and Tectona grandis (79 m3·hm-2) with MAI of 1.40, 1.13 and 0.78 × 10-2 m3 ·tree-1·a-1, respectively in 4 m × 4 m spacing (625 stems·hm-2). Gliricidia maculata and Leucaena leucocephala could be used as live fences around the farm boundary to supply their N-rich leaves for mulch as well as manure to crops. In agroforestry arboretum, direct seeded upland rice (Oryza sativa - variety, AR-11), groundnut (Arachis hypogaea - variety, JL-24) and sesamum (Sesamum indicum - variety, B-67) were grown during the initial period upto 8 years of tree establishment. Under other MPTs,there was a reduction in crop productivity as compared to open space. After 8 years of tree establishment, horti-silvi and silvi-pastoral systems were developed and pineapple (Ananas comosus - variety Queen), turmeric (Curcuma longa -variety RCT -1) and cowpea (Vigna sinensis - variety Pusa Barsati) as forage crop were raised. The productivity of pineapple, turmeric

  2. Modeling the sensing characteristics of chemi-resistive thin film semi-conducting gas sensors.

    Science.gov (United States)

    Ghosh, Abhishek; Majumder, S B

    2017-08-30

    For chemi-resistive thin film gas sensors a generic theoretical model is proposed to predict the variation of sensor response with the operating temperature and thickness of the sensing film. A diffusion equation is formulated assuming that inflammable target gases move through the sensing film by Knudsen diffusion and react with the adsorbed oxygen following first-order kinetics. We have assumed a realistic non-linear variation between the conductance and test gas concentration and derived a general expression relating the sensor response to the operating temperature and thickness of the film. Assuming Langmuir adsorption kinetics, we have theoretically predicted the response and recovery transients during gas sensing using thin film sensing elements. It is predicted that for irreversible type sensing, the response time is reduced with an increase in test gas concentration, whereas for reversible sensing, the response time is independent of test gas concentration. For zinc oxide thin film sensors, an excellent match is obtained between the model prediction and experimental data for their thickness (122 nm to 380 nm) and temperature variation (200 °C to 325 °C) in 500 ppm carbon monoxide (CO) sensing. The maximum CO response% (∼53%) was achieved in 320 nm thick ZnO films. The conductance transients for response and recovery for CO sensing closely follow Langmuir adsorption kinetics and as predicted theoretically, indeed for irreversible sensing, the response time reduces from 350 s to 220 s with an increase in test gas concentration from 20 to 550 ppm. In the case of reversible sensing we found that the response time is ∼55 s irrespective of the CO gas concentration in the range of 5-500 ppm. The models developed in the present work are quite generic in nature and we have discussed their applicability to a wide variety of sensing materials with various types of surface morphologies.

  3. EFECTO DEL CLIMA SOBRE LAS CARACTERÍSTICAS SEMINALES DE PORCINOS EN UNA ZONA DE BOSQUE HÚMEDO TROPICAL EFFECT OF CLIMATE ON THE SEMINAL CHARACTERISTICS OF BOARS IN A REGION OF HUMID TROPICAL FOREST

    Directory of Open Access Journals (Sweden)

    Guillermo Henao Restrepo

    2004-12-01

    from 12 to 24 months of age were selected to evaluate the effect of climatic variables measured on the day of semen collection and for each of preceding 45 days, on seminal characteristics. The variability of each characteristic was separated into a intraindividual component and an interindividual component, using maximum likelihood estimators (PROC VARCOMP of SAS®. In order to relate the seminal characteristics with the climatic variables, morphological abnormalities were grouped according to the affected spermatic region, into head, midsection and mainsection abnormalities; the other characteristics were evaluated without any modification. Possible correlations between seminal characteristics and climatic variables were evaluated. In a total of 298 ejaculates collected weekly during a period of 30 weeks, except for total volume and morphological abnormalities, the seminal characteristics presented low or moderate intra and interindividual variation and were similar to those found in other latitudes, with a tendency to present greater seminal volumes and concentrations. Maximum temperature, minimum temperature, range among temperatures, relative humidity and precipitation of the day of the semen collection and on each of the preceding 45 days had low effects on the seminal characteristics. It is possible that the boars in warm humid tropical areas develop a high level of adaptation that permits an adequate testicular thermoregulation that favors the spermatogenic function of the seminiferous tubules in a way that does not perceptibly affect production the seminal quality.

  4. Relating demographic characteristics of a small mammal to remotely sensed forest-stand condition.

    Directory of Open Access Journals (Sweden)

    Hania Lada

    Full Text Available Many ecological systems around the world are changing rapidly in response to direct (land-use change and indirect (climate change human actions. We need tools to assess dynamically, and over appropriate management scales, condition of ecosystems and their responses to potential mitigation of pressures. Using a validated model, we determined whether stand condition of floodplain forests is related to densities of a small mammal (a carnivorous marsupial, Antechinus flavipes in 60,000 ha of extant river red gum (Eucalyptus camaldulensis forests in south-eastern Australia in 2004, 2005 and 2011. Stand condition was assessed remotely using models built from ground assessments of stand condition and satellite-derived reflectance. Other covariates, such as volumes of fallen timber, distances to floods, rainfall and life stages were included in the model. Trapping of animals was conducted at 272 plots (0.25 ha across the region. Densities of second-year females (i.e. females that had survived to a second breeding year and of second-year females with suckled teats (i.e. inferred to have been successful mothers were higher in stands with the highest condition. There was no evidence of a relationship with stand condition for males or all females. These outcomes show that remotely-sensed estimates of stand condition (here floodplain forests are relatable to some demographic characteristics of a small mammal species, and may provide useful information about the capacity of ecosystems to support animal populations. Over-regulation of large, lowland rivers has led to declines in many facets of floodplain function. If management of water resources continues as it has in recent decades, then our results suggest that there will be further deterioration in stand condition and a decreased capacity for female yellow-footed antechinuses to breed multiple times.

  5. Relating demographic characteristics of a small mammal to remotely sensed forest-stand condition.

    Science.gov (United States)

    Lada, Hania; Thomson, James R; Cunningham, Shaun C; Mac Nally, Ralph

    2014-01-01

    Many ecological systems around the world are changing rapidly in response to direct (land-use change) and indirect (climate change) human actions. We need tools to assess dynamically, and over appropriate management scales, condition of ecosystems and their responses to potential mitigation of pressures. Using a validated model, we determined whether stand condition of floodplain forests is related to densities of a small mammal (a carnivorous marsupial, Antechinus flavipes) in 60,000 ha of extant river red gum (Eucalyptus camaldulensis) forests in south-eastern Australia in 2004, 2005 and 2011. Stand condition was assessed remotely using models built from ground assessments of stand condition and satellite-derived reflectance. Other covariates, such as volumes of fallen timber, distances to floods, rainfall and life stages were included in the model. Trapping of animals was conducted at 272 plots (0.25 ha) across the region. Densities of second-year females (i.e. females that had survived to a second breeding year) and of second-year females with suckled teats (i.e. inferred to have been successful mothers) were higher in stands with the highest condition. There was no evidence of a relationship with stand condition for males or all females. These outcomes show that remotely-sensed estimates of stand condition (here floodplain forests) are relatable to some demographic characteristics of a small mammal species, and may provide useful information about the capacity of ecosystems to support animal populations. Over-regulation of large, lowland rivers has led to declines in many facets of floodplain function. If management of water resources continues as it has in recent decades, then our results suggest that there will be further deterioration in stand condition and a decreased capacity for female yellow-footed antechinuses to breed multiple times.

  6. Heat or humidity, which triggers tree phenology?

    Science.gov (United States)

    Laube, Julia; Sparks, Tim H.; Estrella, Nicole; Menzel, Annette

    2014-05-01

    An overwhelming number of studies confirm that temperature is the main driver for phenological events such as leafing, flowering or fruit ripening, which was first discovered by Réaumur in 1735. Since then, several additional factors which influence onset dates have been identified, such as length of the chilling period, photoperiod, temperature of the previous autumn, nutrient availability, precipitation, sunshine and genetics (local adaptations). Those are supposed to capture some of the remaining, unexplained variance. But our ability to predict onset dates remains imprecise, and our understanding of how plants sense temperature is vague. From a climate chamber experiment on cuttings of 9 tree species we present evidence that air humidity is an important, but previously overlooked, factor influencing the spring phenology of trees. The date of median leaf unfolding was 7 days earlier at 90% relative humidity compared to 40% relative humidity. A second experiment with cuttings shows that water uptake by above-ground tissue might be involved in the phenological development of trees. A third climate chamber experiment suggests that winter dormancy and chilling might be linked to dehydration processes. Analysis of climate data from several meteorological stations across Germany proves that the increase in air humidity after winter is a reliable signal of spring, i.e. less variable or susceptible to reversal compared to temperature. Finally, an analysis of long-term phenology data reveals that absolute air humidity can even be used as a reliable predictor of leafing dates. Current experimental work tries to elucidate the involved foliar uptake processes by using deuterium oxide marked water and Raman spectroscopy. We propose a new framework, wherein plants' chilling requirements and frost tolerance might be attributed to desiccation processes, while spring development is linked to re-humidification of plant tissue. The influence of air humidity on the spring

  7. Radiation tolerant fiber optic humidity sensors for High Energy Physics applications

    CERN Document Server

    Berruti, Gaia Maria; Cusano, Andrea

    This work is devoted to the development of fiber optic humidity sensors to be applied in high-energy physics applications and in particular in experiments currently running at CERN. The high radiation level resulting from the operation of the accelerator at full luminosity can cause serious performance deterioration of the silicon sensors which are responsible for the particle tracking. To increase their lifetime, the sensors must be kept cold at temperatures below 0 C. At such low temperatures, any condensation risk has to be prevented and a precise thermal and hygrometric control of the air filling and surrounding the tracker detector cold volumes is mandatory. The technologies proposed at CERN for relative humidity monitoring are mainly based on capacitive sensing elements which are not designed with radiation resistance characteristic. In this scenario, fiber optic sensors seem to be perfectly suitable. Indeed, the fiber itself, if properly selected, can tolerate a very high level of radiation, optical fi...

  8. Optical humidity detection based on tunable diode laser absorption spectroscopy

    Science.gov (United States)

    Zhang, Keke; Liu, Shixuan; Chen, Shizhe; Zhao, Qiang; Zhang, Lijuan; Li, Xuanqun; Wang, Wenyan; Wu, Yushang

    2017-02-01

    Humidity is an important environmental parameter, which is difficult to be measured accurately and quickly using traditional measurement methods. Under the environment of low temperature or high humidity, traditional humidity and temperature sensor has shortages in humidity measurement accuracy, corresponding time and wet fade speed. To solve these problems, this paper proposes a method to measure the environmental humidity with wavelength modulation technology and harmonic detection technology based on tunable diode laser absorption spectroscopy. H2O molecular absorption line near 1392 nm is selected as the characteristic spectra. The effects of temperature, pressure and water concentration on the absorption spectrum width, the wavelength modulation coefficient and the amplitude of the harmonic signal are analyzed. Humidity and temperature sensor is modified using temperature and pressure compensation model, and the influence of the water concentration variation is eliminated by the iterative algorithm. The new humidity and temperature sensor prototype is developed, and the structure of the optical system is simple, which is easy to be adjusted. The response frequency of the humidity detection is 40 Hz. The experiment was carried out for 3 months at Qingdao national basic weather station. Experimental results show that the consistency of the humidity and temperature data is very good, which can proves the validity of the humidity measurement technology.

  9. All-Optical Graphene Oxide Humidity Sensors

    Directory of Open Access Journals (Sweden)

    Weng Hong Lim

    2014-12-01

    Full Text Available The optical characteristics of graphene oxide (GO were explored to design and fabricate a GO-based optical humidity sensor. GO film was coated onto a SU8 polymer channel waveguide using the drop-casting technique. The proposed sensor shows a high TE-mode absorption at 1550 nm. Due to the dependence of the dielectric properties of the GO film on water content, this high TE-mode absorption decreases when the ambient relative humidity increases. The proposed sensor shows a rapid response (<1 s to periodically interrupted humid air flow. The transmission of the proposed sensor shows a linear response of 0.553 dB/% RH in the range of 60% to 100% RH.

  10. LPG and NH3 sensing characteristics of DC electrochemically deposited Co3O4 films

    Science.gov (United States)

    Shelke, P. N.; Khollam, Y. B.; Gunjal, S. D.; Koinkar, P. M.; Jadkar, S. R.; Mohite, K. C.

    2015-03-01

    Present communication reports the LPG and NH3 sensing properties of Co3O4 films prepared on throughly cleaned stainless steel (SS) and copper (CU) substrates by using DC electrochemical deposition method followed by air annealing at 350°C/2 h. The resultant films are characterized by using X-ray diffraction (XRD), Raman spectroscopy and scanning electron microscopy (SEM). The LPG and NH3 gas sensing properties of these films are measured at room temperature (RT) by using static gas sensing system at different concentrations of test gas ranging from 25 ppm to 350 ppm. The XRD and Raman spectroscopy studies clearly indicated the formation of pure cubic spinel Co3O4 in all films. The LPG and NH3 gas sensing properties of films showed (i) the increase in sensitivity factor (S.F.) with gas concentrations and (ii) more sensibility to LPG as compared to NH3 gas. In case of NH3 gas (conc. 150 ppm) and LPG gas (conc. 60 ppm) sensing, the maximum S.F. = 270 and 258 are found for the films deposited on CU substrates, respectively. For all films, the response time (3-5 min.) is found to be much higher than the recovery time (30-50 sec). For all films, the response and recovery time are found to be higher for LPG as compared to NH3 gas. Further, repeatability-reproducibility in gas sensing properties is clearly noted by analysis of data for number of cycles recorded for all films from different set of depositions.

  11. Combining close-range and remote sensing for local assessment of biophysical characteristics of arable land

    NARCIS (Netherlands)

    Heijden, van der G.W.A.M.; Clevers, J.G.P.W.; Schut, A.G.T.

    2007-01-01

    For crop management, information on the actual status of the crop is important for taking decisions on nitrogen supply, water supply or harvesting. One would also like to take into account the local spatial variation of the crop. Remote sensing has proved to be a useful technique for estimating and

  12. Characteristics of cervical position sense in subjects with forward head posture.

    Science.gov (United States)

    Lee, Mi-Young; Lee, Hae-Yong; Yong, Min-Sik

    2014-11-01

    [Purpose] The purpose of this study was to investigate the effect of forward head posture (FHP) on proprioception by determining the cervical position-reposition error. [Subjects and Methods] A sample population was divided into two groups in accordance with the craniovertebral angle: the FHP group and the control group. We measured the craniovertebral angle, which is defined as the angle between a horizontal line passing through C7 and a line extending from the tragus of the ear to C7. The error value of the cervical position sense after cervical flexion, extension, and rotation was evaluated using the head repositioning accuracy test. [Results] There were significant differences in the error value of the joint position sense (cervical flexion, extension, and rotation) between the FHP and control groups. In addition, there was an inverse correlation between the craniovertebral angle and error value of the joint position sense. [Conclusion] FHP is associated with reduced proprioception. This result implies that the change in the muscle length caused by FHP decreases the joint position sense. Also, proprioception becomes worse as FHP becomes more severe.

  13. Characteristics of Cervical Position Sense in Subjects with Forward Head Posture

    Science.gov (United States)

    Lee, Mi-Young; Lee, Hae-Yong; Yong, Min-Sik

    2014-01-01

    [Purpose] The purpose of this study was to investigate the effect of forward head posture (FHP) on proprioception by determining the cervical position-reposition error. [Subjects and Methods] A sample population was divided into two groups in accordance with the craniovertebral angle: the FHP group and the control group. We measured the craniovertebral angle, which is defined as the angle between a horizontal line passing through C7 and a line extending from the tragus of the ear to C7. The error value of the cervical position sense after cervical flexion, extension, and rotation was evaluated using the head repositioning accuracy test. [Results] There were significant differences in the error value of the joint position sense (cervical flexion, extension, and rotation) between the FHP and control groups. In addition, there was an inverse correlation between the craniovertebral angle and error value of the joint position sense. [Conclusion] FHP is associated with reduced proprioception. This result implies that the change in the muscle length caused by FHP decreases the joint position sense. Also, proprioception becomes worse as FHP becomes more severe. PMID:25435690

  14. Assessment Of Morphometric Characteristics Of Karwadi-Nandapur Micro Watershed Using Remote Sensing And Geographical Information System

    Directory of Open Access Journals (Sweden)

    N.P. Patil

    2015-04-01

    Full Text Available Abstract The study area is Karwadi-Nandapur watershed is a micro watershed which falls in the Kayadhu river watershed in Marathwada region of Maharashtra. Using the remotely sensed images of the Indian Remote Sensing Satellite P6 IRS P6 Linear Imaging Self Scanner IIILISS III images captured in October 2010 and November 2011 having resolution of 23.5m X 23.5m and images from Google Earth Pro of study area were used and cartosat satellites. Map of India with scale 11500000 and soil maps of India were used for the experimental study. The thematic maps like drainage map land use and land cover map soil maps and contour map were prepared adopting the PCI Geomatica10.0 software. The geographical information systems GIS analysis was made for the said themes using the Arc GIS ArcMap10.0. The Karwadi- Nandapur watershed was found to be the third order basin. The present study aims to assess the morphometric characteristics of the watershed basin and it has been assessed by applying GIS techniques. Strahlers method has been employed to assess the fluvial characteristics of the study watershed. Each morphometric characteristic is considered as a single parameter and knowledge based weight age has been assigned by considering its role in soil erosion. The morphometric properties determined for this watershed as a whole and for each watershed will be useful for the efficient planning of water harvesting and groundwater projects on watershed basis.

  15. Thermal stability and energy harvesting characteristics of Au nanorods: harsh environment chemical sensing

    Science.gov (United States)

    Karker, Nicholas; Dharmalingam, Gnanaprakash; Carpenter, Michael A.

    2015-05-01

    Monitoring the levels of polluting gases such as CO and NOx from high temperature (500°C and higher) combustion environments requires materials with high thermal stability and resilience that can withstand harsh oxidizing and reducing environments. Au nanorods (AuNRs) have shown potential in plasmonic gas sensing due to their catalytic activity, high oxidation stability, and absorbance sensitivity to changes in the surrounding environment. By using electron beam lithography, AuNR geometries can be patterned with tight control of the rod dimensions and spacings, allowing tunability of their optical properties. Methods such as NR encapsulation within an yttria-stabilized zirconia overcoat layer with subsequent annealing procedures will be shown to improve temperature stability within a simulated harsh environment. Since light sources and spectrometers are typically required to obtain optical measurements, integration is a major barrier for harsh environment sensing. Plasmonic sensing results will be presented where thermal energy is harvested by the AuNRs, which replaces the need for an external incident light source. Results from gas sensing experiments that utilize thermal energy harvesting are in good agreement with experiments which use an external incident light source. Principal component analysis results demonstrate that by selecting the most "active" wavelengths in a plasmonic band, the wavelength space can be reduced from hundreds of monitored wavelengths to just four, without loss of information about selectivity of the AuNRs. By combining thermal stability, the thermal energy harvesting capability, and the selectivity in gas detection (achieved through multivariate analysis), integration of plasmonic sensors into combustion environments can be greatly simplified.

  16. Application of radar polarimetry techniques for retrieval snow and rain characteristics in remote sensing

    OpenAIRE

    2013-01-01

    The presence of snow cover has significant impacts on the both global and regional climate and water balance on earth. The accurate estimation of snow cover area can be used for forecasting runoff due to snow melt and output of hydroelectric power. With development of remote sensing techniques at different scopes in earth science, enormous algorithms for retrieval hydrometeor parameters have been developed. Some of these algorithms are used to provide snow cover map such as NLR with AVHRR/MOD...

  17. Characteristics analysis of SOI waveguide Michelson interferometers for developing biomedical fiber temperature-sensing head

    Science.gov (United States)

    Tsao, Shyh-Lin; Lee, Shin-Ge

    2000-07-01

    A new silicon-on-insulator (SOI) waveguide Michelson interferometer with Bragg reflective gratings as a biomedical temperature sensing array head is presented in this paper. The waveguide Bragg reflective gratings work as mirrors for adjusting the transfer function of the Michelson interferometer sensor. We will show the comparison of the temperature sensing accuracies of the fiber Bragg grating and SOI waveguide Michelson interferometers in biomedical applications. The grating length and perturbation period of waveguide Bragg grating in SOI waveguide Michelson interferometer will increase as temperature rises, that is, the thermal effects of the reflective Bragg gratings are considered in our analysis. According to the numerical analysis of power reflective spectra of waveguide Michelson interferometers, the temperature sensing waveguide of the Michelson interferometer can improve at least 20 times than the traditional fiber Bragg grating temperature sensor. Moreover, the SOI waveguide interferometer sensor we designed presents high sensitivity than pure single waveguide Bragg grating sensor and fiber Bragg grating sensor by adjusting the length of the two interferometric arms. The full width of half maximum (FWHM) of the frequency responses of passband of SOI waveguide Michelson interferometer can be designed smaller than fiber and waveguide Bragg grating sensors for sensitivity improvement.

  18. Hydrogen Gas Sensing Characteristics of Nanostructured NiO Thin Films Synthesized by SILAR Method

    Science.gov (United States)

    Karaduman, Irmak; Çorlu, Tugba; Yıldırım, M. Ali; Ateş, Aytunç; Acar, Selim

    2017-03-01

    Nanostructured NiO thin films have been synthesized by a facile, low-cost successive ionic layer adsorption and reaction (SILAR) method, and the effects of the film thickness on their hydrogen gas sensing properties investigated. The samples were characterized by scanning electron microscopy (SEM), x-ray diffraction (XRD) analysis, and energy-dispersive x-ray analysis. The XRD results revealed that the crystallinity improved with increasing thickness, exhibiting polycrystalline structure. SEM studies showed that all the films covered the glass substrate well. According to optical absorption measurements, the optical bandgap decreased with increasing film thickness. The gas sensing properties of the nanostructured NiO thin films were studied as a function of operating temperature and gas concentration. The samples showed good sensing performance of H2 gas with high response. The maximum response was 75% at operating temperature of 200°C for hydrogen gas concentration of 40 ppm. These results demonstrate that nanostructured NiO thin films synthesized by the SILAR method have potential for application in hydrogen detection.

  19. 云南高黎贡山中山湿性常绿阔叶林的群落特征%Community Characteristics of the Mid-Montane Humid Ever-Green Broad-Leaved Forest in Gaoligong Mountains, Yunnan

    Institute of Scientific and Technical Information of China (English)

    孟广涛; 柴勇; 袁春明; 艾怀森; 李贵祥; 王骞; 李品荣; 蔺汝涛

    2013-01-01

    The dynamic observation of the mid - montane humid evergreen broad-leaved forest and the community characteristics analysis were conducted in a 4 - hm2 permanent plot located in ecological corridor in southern region of Gaoligong Mountains National Nature Reserve during 2009-2010. The results showed that there were 10 546 freestanding individuals with DBH ≥1. 0 cm in the 4 hm plot, belonging to 95 species, 64 genera and 35 families. The species richness was higher and the proportion of rare species was lower in the plot, compared with other plots of the same kind forest. Lauraceae, Theaceae, Araliaceae, Fagaceae, and Symplocaceae were dominant families in the plot and they comprised 44. 21 % of all species and 56. 70% of all individuals. Symplocas ramosissima, Eurya pseudocerasifera , Gordonia longicarpa, Neolitsea lunglingensis, Lithocarpus hancei, and Cyclobalanopsis lamellosa had more importance value in the plot, but no one had obvious advantage, namely the plot did not contain an obviously dominant species. Floristic characteristics of the community indicated that the tropical elements were much more than temperate elements, implying that this area could be an origin of tropics. The minimal area of the community is 1. 32 hm , which could comprise more than 80% of all species. The structure of DBH size class of all species and some dominant species in the plot showed a typical pyramid structure with a wide bottom and a narrow top, implying a good regeneration in the community. The survival curve of most of dominant species tended to be of the Deevey-Ⅲ type, with a high mortality rate at small DHB size class and a low and stable mortality rate at large DBH size class.

  20. Using remote sensing and spatial analysis of trees characteristics for long-term monitoring in arid environments

    Science.gov (United States)

    Isaacson, Sivan; Blumberg, Dan G.; Rachmilevitch, Shimon; Ephrath, Jhonathan E.; Maman, Shimrit

    2016-04-01

    Trees play a significant role in the desert ecosystem by moderating the extreme environmental conditions including radiation, temperature, low humidity and small amount of precipitation. Trees In arid environments such an Acacia are considered to be `keystone species', because they have major influence over both plants and animal species. Long term monitoring of acacia tree population in those areas is thus essential tool to estimate the overall ecosystem condition. We suggest a new remote sensing data analysis technique that can be integrated with field long term monitoring of trees in arid environments and improve our understanding of the spatial and temporal changes of these populations. In this work we have studied the contribution of remote sensing methods to long term monitoring of acacia trees in hyper arid environments. In order to expand the time scope of the acacia population field survey, we implemented two different approaches: (1) Trees individual based change detection using Corona satellite images and (2) Spatial analysis of trees population, converting spatial data into temporal data. A map of individual acacia trees that was extracted from a color infra-red (CIR) aerial photographs taken at 2010 allowed us to examine the distribution pattern of the trees size and foliage health status (NDVI). Comparison of the tree sizes distribution and NDVI values distribution enabled us to differentiate between long-term (decades) and short-term (months to few years) processes that brought the population to its present state. The spatial analysis revealed that both tree size and NDVI distribution patterns were significantly clustered, suggesting that the processes responsible for tree size and tree health status (i.e., flash-floods spatial spreading) have a spatial expression. The distribution of the trees in the Wadi (ephemeral river) was divided into three distinct parts: large trees with high NDVI values, large trees with low NDVI values and small trees with

  1. High Temperature Sensing Systems--Characteristics of Rechargeable Batteries at High Temperature--

    OpenAIRE

    2001-01-01

     High temperature discharge characteristics were measured at 100℃ for commercial available Nickel Cadmium and Nickel Metal Hydride rechargeable batteries. A Nickel Cadmium battery has superior dis­charge characteristics than a Nickel Metal Hydride battery. A life cycle of rechargeable battery can be esti­mated by measuring an internal resistance of the battery during charge at room temperature.

  2. A Novel Passive Wireless Sensor for Concrete Humidity Monitoring

    Science.gov (United States)

    Zhou, Shuangxi; Deng, Fangming; Yu, Lehua; Li, Bing; Wu, Xiang; Yin, Baiqiang

    2016-01-01

    This paper presents a passive wireless humidity sensor for concrete monitoring. After discussing the transmission of electromagnetic wave in concrete, a novel architecture of wireless humidity sensor, based on Ultra-High Frequency (UHF) Radio Frequency Identification (RFID) technology, is proposed for low-power application. The humidity sensor utilizes the top metal layer to form the interdigitated electrodes, which were then filled with polyimide as the humidity sensing layer. The sensor interface converts the humidity capacitance into a digital signal in the frequency domain. A two-stage rectifier adopts a dynamic bias-voltage generator to boost the effective gate-source voltage of the switches in differential-drive architecture. The clock generator employs a novel structure to reduce the internal voltage swing. The measurement results show that our proposed wireless humidity can achieve a high linearity with a normalized sensitivity of 0.55% %RH at 20 °C. Despite the high losses of concrete, the proposed wireless humidity sensor achieves reliable communication performances in passive mode. The maximum operating distance is 0.52 m when the proposed wireless sensor is embedded into the concrete at the depth of 8 cm. The measured results are highly consistent with the results measured by traditional methods. PMID:27657070

  3. A Novel Passive Wireless Sensor for Concrete Humidity Monitoring

    Directory of Open Access Journals (Sweden)

    Shuangxi Zhou

    2016-09-01

    Full Text Available This paper presents a passive wireless humidity sensor for concrete monitoring. After discussing the transmission of electromagnetic wave in concrete, a novel architecture of wireless humidity sensor, based on Ultra-High Frequency (UHF Radio Frequency Identification (RFID technology, is proposed for low-power application. The humidity sensor utilizes the top metal layer to form the interdigitated electrodes, which were then filled with polyimide as the humidity sensing layer. The sensor interface converts the humidity capacitance into a digital signal in the frequency domain. A two-stage rectifier adopts a dynamic bias-voltage generator to boost the effective gate-source voltage of the switches in differential-drive architecture. The clock generator employs a novel structure to reduce the internal voltage swing. The measurement results show that our proposed wireless humidity can achieve a high linearity with a normalized sensitivity of 0.55% %RH at 20 °C. Despite the high losses of concrete, the proposed wireless humidity sensor achieves reliable communication performances in passive mode. The maximum operating distance is 0.52 m when the proposed wireless sensor is embedded into the concrete at the depth of 8 cm. The measured results are highly consistent with the results measured by traditional methods.

  4. A Novel Passive Wireless Sensor for Concrete Humidity Monitoring.

    Science.gov (United States)

    Zhou, Shuangxi; Deng, Fangming; Yu, Lehua; Li, Bing; Wu, Xiang; Yin, Baiqiang

    2016-09-20

    This paper presents a passive wireless humidity sensor for concrete monitoring. After discussing the transmission of electromagnetic wave in concrete, a novel architecture of wireless humidity sensor, based on Ultra-High Frequency (UHF) Radio Frequency Identification (RFID) technology, is proposed for low-power application. The humidity sensor utilizes the top metal layer to form the interdigitated electrodes, which were then filled with polyimide as the humidity sensing layer. The sensor interface converts the humidity capacitance into a digital signal in the frequency domain. A two-stage rectifier adopts a dynamic bias-voltage generator to boost the effective gate-source voltage of the switches in differential-drive architecture. The clock generator employs a novel structure to reduce the internal voltage swing. The measurement results show that our proposed wireless humidity can achieve a high linearity with a normalized sensitivity of 0.55% %RH at 20 °C. Despite the high losses of concrete, the proposed wireless humidity sensor achieves reliable communication performances in passive mode. The maximum operating distance is 0.52 m when the proposed wireless sensor is embedded into the concrete at the depth of 8 cm. The measured results are highly consistent with the results measured by traditional methods.

  5. A flexible humidity sensor based on KC-MWCNTs composites

    Science.gov (United States)

    Peng, Xiaoyan; Chu, Jin; Aldalbahi, Ali; Rivera, Manuel; Wang, Lidan; Duan, Shukai; Feng, Peter

    2016-11-01

    Multi-walled carbon nanotubes (MWCNTs) and single-walled carbon nanotubes (SWCNTs) were dispersed in the biopolymer kappa-carrageenan (KC) to form a flexible composite via evaporative casting method. The glycerin was used as plasticizer to increase the flexibility of the composite. The KC-CNTs was examined by using FESEM and Raman, and then the humidity sensing properties of the samples were characterized under alternating current (AC). The purpose for using AC power supply is to avoid the possible polarization effect during measurements of the humidity properties. The experimental data exhibit that the fabricated sensors have high response to relative humidity (RH) with good repeatability, stability, and low hysteresis. A phenomenon that the impedance of the sensor decreases with ascending RH was also found and the basic sensing mechanisms were discussed.

  6. Application of radar polarimetry techniques for retrieval snow and rain characteristics in remote sensing

    Science.gov (United States)

    Darvishi, M.; Ahmadi, Gh. R.

    2013-09-01

    The presence of snow cover has significant impacts on the both global and regional climate and water balance on earth. The accurate estimation of snow cover area can be used for forecasting runoff due to snow melt and output of hydroelectric power. With development of remote sensing techniques at different scopes in earth science, enormous algorithms for retrieval hydrometeor parameters have been developed. Some of these algorithms are used to provide snow cover map such as NLR with AVHRR/MODIS sensor for Norway, Finnish with AVHRR sensor for Finland and NASA with MODIS sensor for global maps. Monitoring snow cover at different parts of spectral electromagnetic is detectable (visible, near and thermal infrared, passive and active microwave). Recently, specific capabilities of active microwave remote sensing such as snow extent map, snow depth, snow water equivalent (SWE), snow state (wet/dry) and discrimination between rain and snow region were given a strong impetus for using this technology in snow monitoring, hydrology, climatology, avalanche research and etc. This paper evaluates the potentials and feasibility of polarimetric ground microwave measurements of snow in active remote sensing field. We will consider the behavior co- and cross-polarized backscattering coefficients of snowpack response with polarimetric scatterometer in Ku and L band at the different incident angles. Then we will show how to retrieve snow cover depth, snow permittivity and density parameters at the local scale with ground-based SAR (GB-SAR). Finally, for the sake of remarkable significant the transition region between rain and snow; the variables role of horizontal reflectivity (ZHH) and differential reflectivity (ZDR) in delineation boundary between snow and rain and some others important variables at polarimetric weather radar are presented.

  7. Application of radar polarimetry techniques for retrieval snow and rain characteristics in remote sensing

    Directory of Open Access Journals (Sweden)

    M. Darvishi

    2013-09-01

    Full Text Available The presence of snow cover has significant impacts on the both global and regional climate and water balance on earth. The accurate estimation of snow cover area can be used for forecasting runoff due to snow melt and output of hydroelectric power. With development of remote sensing techniques at different scopes in earth science, enormous algorithms for retrieval hydrometeor parameters have been developed. Some of these algorithms are used to provide snow cover map such as NLR with AVHRR/MODIS sensor for Norway, Finnish with AVHRR sensor for Finland and NASA with MODIS sensor for global maps. Monitoring snow cover at different parts of spectral electromagnetic is detectable (visible, near and thermal infrared, passive and active microwave. Recently, specific capabilities of active microwave remote sensing such as snow extent map, snow depth, snow water equivalent (SWE, snow state (wet/dry and discrimination between rain and snow region were given a strong impetus for using this technology in snow monitoring, hydrology, climatology, avalanche research and etc. This paper evaluates the potentials and feasibility of polarimetric ground microwave measurements of snow in active remote sensing field. We will consider the behavior co- and cross-polarized backscattering coefficients of snowpack response with polarimetric scatterometer in Ku and L band at the different incident angles. Then we will show how to retrieve snow cover depth, snow permittivity and density parameters at the local scale with ground-based SAR (GB-SAR. Finally, for the sake of remarkable significant the transition region between rain and snow; the variables role of horizontal reflectivity (ZHH and differential reflectivity (ZDR in delineation boundary between snow and rain and some others important variables at polarimetric weather radar are presented.

  8. A high sensitivity humidity sensor based on micro-ring resonator with three coupling points

    Science.gov (United States)

    Guo, Shi-liang; Wang, Wen-juan; Hu, Chun-hai

    2014-12-01

    A novel high sensitivity humidity sensor based on micro-ring resonator with three coupling points (MRRTCP) is reported. Since the dielectric constant of Polyimide is highly sensible to the relative humidity of the environment, we choose the Polyimide (PI) as the moisture material. The effective refractive index of the sensing part of the sensor changes as the relative humidity of the environment changes, this leading to an obvious shift of the output spectrum. The sensing range of the relative humidity sensor is 0~100%RH, and the sensitivity is 0.0017μm/%RH, and the structure is relatively simple and could be used in micro-scale humidity sensing.

  9. SOCIAL KNOWLEDGE IN THE CHARACTERISTICS OF COMMON SENSE AND EVERYDAY LIFE EXPERIENCE

    Directory of Open Access Journals (Sweden)

    Evgeniya Sergeevna Sagalaeva

    2015-01-01

    Full Text Available The article shows that changes in everyday life act as a cultural phenomenon, and the aim of social knowledge must be projection of total universal features to individual features. The author notes that among the components of everyday life and experience, as well as everyday ideology, there are social ideas as a kind of subjective constructs designed to rationalize and interpret the vital reality. The article defines the common sense as the totality of views on the world, skills, and forms of thinking, developed and used by the individual in daily practical life. Social knowledge in the coordinates of everyday life experience and common sense is determined by the fact that modern everyday life is a phenomenon devoid of statics. Daily life is a certain spiritual and social integrity of the mental and material, a constant attribute of social life, unfolding in a social and cultural space and time in such areas as the everyday life, work and leisure with the help of various types and forms of activityrelated manifestations.

  10. H2S Detection Sensing Characteristic of CuO/SnO2 Sensor

    Directory of Open Access Journals (Sweden)

    Zenglian Yu

    2003-05-01

    Full Text Available Among the various metal oxide additives tested, the complex of CuO is outstanding in promoting the sensing propoerties of an SnO2 sensor for H2S in air. The SnO2 sensors loaded with 5 wt. % CuO is extremely sensitive to H2S at 200 C° and below, while it is almost unsensitive to many other gases. The response to H2S is rather slow but the recovery is very rapid. Tha added CuO particles interact electronically with the surface of SnO2 (p-n junctions to make the sensor highly resistive, while the interaction is disconnected when CuO is sulfurized to CuS in the H2S containing atmosphere, leading to a drastic decrease in electrical resistance. The H2S sensing properties, particularly the rate of response of CuO/SnO2 sensors are influenced by the CuO loadings andoperating temperature as well as the thickness of Cuo loading film.

  11. Influence of Thickness on Ethanol Sensing Characteristics of Doctor-bladed Thick Film from Flame-made ZnO Nanoparticles

    Directory of Open Access Journals (Sweden)

    Sukon Phanichphant

    2007-02-01

    Full Text Available ZnO nanoparticles were produced by flame spray pyrolysis (FSP using zincnaphthenate as a precursor dissolved in toluene/acetonitrile (80/20 vol%. The particleproperties were analyzed by XRD, BET, and HR-TEM. The sensing films were produced bymixing the particles into an organic paste composed of terpineol and ethyl cellulose as avehicle binder and were fabricated by doctor-blade technique with various thicknesses (5,10, 15 μm. The morphology of the sensing films was analyzed by SEM and EDS analyses.The gas sensing characteristics to ethanol (25-250 ppm were evaluated as a function of filmthickness at 400°C in dry air. The relationship between thickness and ethanol sensingcharacteristics of ZnO thick film on Al2O3 substrate interdigitated with Au electrodes wereinvestigated. The effects of film thickness, as well as the cracking phenomenon, though,many cracks were observed for thicker sensing films. Crack widths increased withincreasing film thickness. The film thickness, cracking and ethanol concentration havesignificant effect on the sensing characteristics. The sensing characteristics with variousthicknesses were compared, showing the tendency of the sensitivity to ethanol decreasedwith increasing film thickness and response time. The relationship between gas sensingproperties and film thickness was discussed on the basis of diffusively and reactivity of thegases inside the oxide films. The thinnest sensing film (5 μm showed the highest sensitivityand the fastest response time (within seconds.

  12. Human-Finger Electronics Based on Opposing Humidity-Resistance Responses in Carbon Nanofilms

    KAUST Repository

    Tai, Yanlong

    2017-01-09

    Carbon nanomaterials have excellent humidity sensing properties. Here, it is demonstrated that multiwalled carbon-nanotube (MWCNT)- and reduced-graphene-oxide (rGO)-based conductive films have opposite humidity/electrical resistance responses: MWCNTs increase their electrical resistance (positive response) and rGOs decrease their electrical resistance (negative response). The authors propose a new phenomenology that describes a

  13. Spectral characteristics and feature selection of satellite remote sensing data for climate and anthropogenic changes assessment in Bucharest area

    Science.gov (United States)

    Zoran, Maria; Savastru, Roxana; Savastru, Dan; Tautan, Marina; Miclos, Sorin; Cristescu, Luminita; Carstea, Elfrida; Baschir, Laurentiu

    2010-05-01

    Urban systems play a vital role in social and economic development in all countries. Their environmental changes can be investigated on different spatial and temporal scales. Urban and peri-urban environment dynamics is of great interest for future planning and decision making as well as in frame of local and regional changes. Changes in urban land cover include changes in biotic diversity, actual and potential primary productivity, soil quality, runoff, and sedimentation rates, and cannot be well understood without the knowledge of land use change that drives them. The study focuses on the assessment of environmental features changes for Bucharest metropolitan area, Romania by satellite remote sensing and in-situ monitoring data. Rational feature selection from the varieties of spectral channels in the optical wavelengths of electromagnetic spectrum (VIS and NIR) is very important for effective analysis and information extraction of remote sensing data. Based on comprehensively analyses of the spectral characteristics of remote sensing data is possibly to derive environmental changes in urban areas. The information quantity contained in a band is an important parameter in evaluating the band. The deviation and entropy are often used to show information amount. Feature selection is one of the most important steps in recognition and classification of remote sensing images. Therefore, it is necessary to select features before classification. The optimal features are those that can be used to distinguish objects easily and correctly. Three factors—the information quantity of bands, the correlation between bands and the spectral characteristic (e.g. absorption specialty) of classified objects in test area Bucharest have been considered in our study. As, the spectral characteristic of an object is influenced by many factors, being difficult to define optimal feature parameters to distinguish all the objects in a whole area, a method of multi-level feature selection

  14. Investigation of the Carbon Monoxide Gas Sensing Characteristics of Tin Oxide Mixed Cerium Oxide Thin Films

    Directory of Open Access Journals (Sweden)

    Muhammad B. Haider

    2012-02-01

    Full Text Available Thin films of tin oxide mixed cerium oxide were grown on unheated substrates by physical vapor deposition. The films were annealed in air at 500 °C for two hours, and were characterized using X-ray photoelectron spectroscopy, atomic force microscopy and optical spectrophotometry. X-ray photoelectron spectroscopy and atomic force microscopy results reveal that the films were highly porous and porosity of our films was found to be in the range of 11.6–21.7%. The films were investigated for the detection of carbon monoxide, and were found to be highly sensitive. We found that 430 °C was the optimum operating temperature for sensing CO gas at concentrations as low as 5 ppm. Our sensors exhibited fast response and recovery times of 26 s and 30 s, respectively.

  15. TiO(2)/LiCl-based nanostructured thin film for humidity sensor applications.

    Science.gov (United States)

    Buvailo, Andrii I; Xing, Yangjun; Hines, Jacqueline; Dollahon, Norman; Borguet, Eric

    2011-02-01

    A simple and straightforward method of depositing nanostructured thin films, based on LiCl-doped TiO(2), on glass and LiNbO(3) sensor substrates is demonstrated. A spin-coating technique is employed to transfer a polymer-assisted precursor solution onto substrate surfaces, followed by annealing at 520°C to remove organic components and drive nanostructure formation. The sensor material obtained consists of coin-shaped nanoparticles several hundred nanometers in diameter and less than 50 nm thick. The average thickness of the film was estimated by atomic force microscopy (AFM) to be 140 nm. Humidity sensing properties of the nanostructured material and sensor response times were studied using conductometric and surface acoustic wave (SAW) sensor techniques, revealing reversible signals with good reproducibility and fast response times of about 0.75 s. The applicability of this nanostructured film for construction of rapid humidity sensors was demonstrated. Compared with known complex and expensive methods of synthesizing sophisticated nanostructures for sensor applications, such as physical vapor deposition (PVD) and chemical vapor deposition (CVD), this work presents a relatively simple and inexpensive technique to produce SAW humidity sensor devices with competitive performance characteristics.

  16. A Ceramic Thick Film Humidity Sensor Based on MnZn Ferrite

    Directory of Open Access Journals (Sweden)

    D. Egan

    2002-02-01

    Full Text Available A ceramic thick film humidity sensor, produced from MnZn ferrite, is presented. The proposed sensing mechanism is a combination of proton hopping, hydronium diffusion, and vacancy donor traps releasing electrons into the conduction band. The sensor structure comprises a two-layer device; the first layer is an interdigitated conductor and the second layer is a 30μm thick sensing layer. The effects of sintering the sensing pastes in air and vacuum have been reported. The air-fired sample exhibits the highest humidity sensitivity (1.54%/RH% and the lowest temperature sensitivity (0.37%/oC. The vacuum-fired sample has the lowest humidity sensitivity (0.043%/RH and the highest temperature sensitivity (0.77%/oC. The sensitivity results indicate that the air-fired sample has the best potential for use in humidity sensing applications.

  17. Nanosized thin SnO₂ layers doped with Te and TeO₂ as room temperature humidity sensors.

    Science.gov (United States)

    Georgieva, Biliana; Podolesheva, Irena; Spasov, Georgy; Pirov, Jordan

    2014-05-21

    In this paper the humidity sensing properties of layers prepared by a new method for obtaining doped tin oxide are studied. Different techniques-SEM, EDS in SEM, TEM, SAED, AES and electrical measurements-are used for detailed characterization of the thin layers. The as-deposited layers are amorphous with great specific area and low density. They are built up of a fine grained matrix, consisting of Sn- and Te-oxides, and a nanosized dispersed phase of Te, Sn and/or SnTe. The chemical composition of both the matrix and the nanosized particles depends on the ratio R(Sn/Te) and the evaporation conditions. It is shown that as-deposited layers with R(Sn/Te) ranging from 0.4 to 0.9 exhibit excellent characteristics as humidity sensors operating at room temperature-very high sensitivity, good selectivity, fast response and short recovery period. Ageing tests have shown that the layers possess good long-term stability. Results obtained regarding the type of the water adsorption on the layers' surface help better understand the relation between preparation conditions, structure, composition and humidity sensing properties.

  18. Nanosized Thin SnO2 Layers Doped with Te and TeO2 as Room Temperature Humidity Sensors

    Directory of Open Access Journals (Sweden)

    Biliana Georgieva

    2014-05-01

    Full Text Available In this paper the humidity sensing properties of layers prepared by a new method for obtaining doped tin oxide are studied. Different techniques—SEM, EDS in SEM, TEM, SAED, AES and electrical measurements—are used for detailed characterization of the thin layers. The as-deposited layers are amorphous with great specific area and low density. They are built up of a fine grained matrix, consisting of Sn- and Te-oxides, and a nanosized dispersed phase of Te, Sn and/or SnTe. The chemical composition of both the matrix and the nanosized particles depends on the ratio RSn/Te and the evaporation conditions. It is shown that as-deposited layers with RSn/Te ranging from 0.4 to 0.9 exhibit excellent characteristics as humidity sensors operating at room temperature—very high sensitivity, good selectivity, fast response and short recovery period. Ageing tests have shown that the layers possess good long-term stability. Results obtained regarding the type of the water adsorption on the layers’ surface help better understand the relation between preparation conditions, structure, composition and humidity sensing properties.

  19. Porous Cube-like In2O3 Nanoparticles and Their Sensing Characteristics toward Ethanol

    Institute of Scientific and Technical Information of China (English)

    Chih-Chia HUANG; Chen-Sheng YEH

    2008-01-01

    Porous cube-like crystalline In2O3 nanoparticles with an average diagonal length of 34.8 nm were fabricated by a laser ablation-reflux process to form In(OH)3, followed by a calcination treatment to yield porous In2O3. HRTEM (high-resolution transmission electronic microscopy), XRD (X-ray diffraction), BET (Brunauer-Emmett-Teller), and XPS (X-ray photoelectron spectroscopy) analysis were used to characterize their crystalline structures, grain sizes, surface areas, and surface compositions. The as-prepared porous indium oxides were tested for their sensing properties toward ethanol. Non-porous In2O3 nanopowder (about 40 nm) was also examined in order to compare the results with the as-prepared porous In2O3 nanomaterials. The porous In2O3 exhibited much better performance than that of non-porosus In2O3, and showed enhanced sensitivity with a lower detection limit than other reported In2O3-based materials when exposed to ethanol. Good gas sensitivity and linear behavior as a function of ethanol concentration were observed in the porous In2O3 nanoparticles.

  20. Sense of community in Hong Kong: relations with community-level characteristics and residents' well-being.

    Science.gov (United States)

    Mak, Winnie W S; Cheung, Rebecca Y M; Law, Lawrence S C

    2009-09-01

    Sense of community (SOC) has been one of the most studied topics in community psychology. However, no empirical study to date has investigated SOC in Hong Kong and its relations with community characteristics and residents' psychological well-being. A representative sample of 941 Hong Kong Chinese based on a randomized household survey was conducted in all 18 districts in Hong Kong. Results of hierarchical linear modeling indicated that SOC was not associated with sociodemographic indicators on both the individual-level (i.e., gender, age, family income, education level, type of residence, and area-to-capita ratio of residence) and the community-level (i.e., proportion of individuals with tertiary education, median family income, ownership of residence, population density, and resident stability). SOC was negatively related to daily hassles and positively with social support and quality of life. Conceptualization of SOC in Hong Kong was discussed.

  1. Comparative NH 3-sensing characteristic studies of PANI/TiO II nanocomposite thin films doped with different acids

    Science.gov (United States)

    Tai, Huiling; Jiang, Yadong; Xie, Guangzhong; Yu, Junsheng; Ying, Zhihua; Chen, Xuan

    2008-02-01

    Polyaniline/titanium dioxide (PANI/TiO II) nanocomposite thin films were synthesized by in-situ self-assembly method, which were doped with p-toluene sulphonic acid (p-TSA) and hydrochloric acid (HCl), respectively. The thin films were characterized by using UV-Vis absorption spectroscopy and scanning electron microscope (SEM), and the NH 3 gas sensitive properties of the thin films were investigated at room temperature. The results showed that the PANI/TiO II thin film doped with HCl was superior to that doped with p-TSA in terms of response-recovery characteristics. The surface morphology characterization of the thin films were performed to explain the different gas-sensing properties.

  2. ANALYZING THE SHAPE CHARACTERISTICS OF LAND USE CLASSES IN REMOTE SENSING IMAGERY

    Directory of Open Access Journals (Sweden)

    L. Jiao

    2012-07-01

    Full Text Available Shape is an important aspect of spatial attributes of land use segments in remotely sensed imagery, but it is still rarely used as a component in land use classification or image-based land use analysis. This study aims to quantitatively characterize land use classes using shape metrics. The study is conducted in a case area located in south China, covering twelve scenes of SPOT-5 images. There were total ten metrics selected for the analysis, namely, Convexity (CONV, Solidity (SOLI, Elongation (ELONG, Roundness (ROUND, Rectangular Fitting (RECT, Compact (COMP, Form Factor (FORM, Square pixel metric (SqP, Fractal Dimension (FD, and Shape Index (SI. The last five metrics were used to measure the complexity of shape. Eight land use classes were investigated in the case area, namely, roads, cultivated lands, settlement places, rivers, ponds, forest and grass lands, reservoirs, and dams. The results show that all typical shape properties of land use segments can be well measured by shape metrics. We identified the land use classes whose values are significantly differentiated from most classes for each metric. Two of the five complexity metrics, FORM and SqP, were identified to be more effective in characterizing the complexity of land use classes. We finally selected six shape metrics and deduced the "Shape Metric Signatures" (SMS of different land use classes. SMS can serve as accurate and predictive discriminators of land use classes within the study area. Our results show that SMS can clearly distinguish spectrally similar land use classes. The results will help to build a more accurate and intelligent object-oriented classification system for land use classes.

  3. Remote Sensing and Spectral Characteristics of Desert Sand from Qatar Peninsula, Arabian/Persian Gulf

    Directory of Open Access Journals (Sweden)

    Fares Howari

    2009-11-01

    Full Text Available Remote sensing data can provide valuable information about the surface expression of regional geomorphologic and geological features of arid regions. In the present study, several processing techniques were applied to reveal such in the Qatar Peninsula. Those included preprocessing for radiometric and geometric correction, various enhancement methods, classification, accuracy assessment, contrast stretching, color composition, and principal component analyses. Those were coupled with field groundtruthing and lab analyses. Field groundtruthing included one hundred and forty measurements of spectral reflectance for various sediment exposures representing main sand types in the four studied parts in Qatar. Lab investigations included grain size analysis, X-ray diffraction and laboratory measurements of spectral reflectance. During the course of this study three sand types have been identified: (i sabkha-derived salt-rich, quartz sand, and (ii beach-derived calcareous sand and (iii aeolian dune quartz. Those areas are spectrally distinct in the VNIR, suggesting that VNIR spectral data can be used to discriminate them. The study found that the main limitation of the ground spectral reflectance study is the difficulty of covering large areas. The study also found that ground and laboratory spectral radiance are generally higher in reflectance than those of Landsat TM. This is due to several factors such as atmospheric conditions, the low altitude or different scales. Whereas for areas with huge size of dune sand, the Landsat TM spectral has higher reflectance than those from field and laboratory. The study observed that there is a good correspondence or correlation of the wavelengths maximum sensitivity between the three spectral measurements i.e lab, field and space-borne measurements.

  4. Dip-coated hydrotungstite thin films as humidity sensors

    OpenAIRE

    2005-01-01

    Thin films of a hydrated phase of tungsten oxide, viz. hydrotungstite,have been prepared on glass substrates by dip-coating method using ammonium tungstate precursor solution. X-ray diffraction shows the films to have a strong b-axis orientation. The resistance of the films is observed to be sensitive to the humidity content of the ambient,indicating possible applications of these films for humidity sensing. Ahome made apparatus designed to measure the d.c. electrical resistance in response t...

  5. Temperature, Humidity, And Polymer Aging

    Science.gov (United States)

    Cuddihy, Edward F.

    1988-01-01

    Report presents analysis of experimental data on electrical resistivity of polymer (polyvinyl butyral) as function of temperature and relative humidity. Resulting theoretical expression for electrical resistivity resembles generally accepted empirical law for the corrosion rate.

  6. Spatially explicit forest characteristics of Europe through integrating Forest Inventory and Remotely sensed data

    Science.gov (United States)

    Moreno, Adam; Neumann, Mathias; Hasenauer, Hubert

    2015-04-01

    Carbon stock estimates are critical for any carbon trading scheme or climate change mitigation strategy. Understanding the carbon allocation and the structure of its ecosystem further help scientists and policy makers develop realistic plans for utilizing these systems. Forests play an important role in global carbon storage. Therefore it is imperative to include forests in any climate change mitigation and/or carbon trading scheme. Currently there is no estimate of forest carbon stocks and allocation nor forest structure maps throughout Europe. We compiled National Forest Inventory (NFI) data from 12 European countries. We integrated the NFI data with Net Primary Production data (NPP) from Moderate Resolution Imaging Spectroradiometer (MODIS), tree height data from Light Detection and Ranging (LIDAR) data from the Geosciences Laser Altimeter System (GLAS) instrument, and various other spatially explicit data sets. Through this process of integration of terrestrial and space based data we produced wall-to-wall forest characteristics maps of Europe. These maps include forest age, basal area, average diameter at breast height, total carbon, carbon allocation (stem, branches, leaves, roots), and other characteristics derived from forest inventory data. These maps cover Europe - including countries without terrestrial data - and give one coherent harmonized data set of current forest structure and carbon storage on a 16x16km resolution. The methodology presented here has the potential to be used world-wide in regions with data limitations or with limited access to data.

  7. A nafion coated capacitive humidity sensor on a flexible PET substrate

    KAUST Repository

    Sapsanis, Christos

    2017-03-07

    This paper reports a simple and low-cost technique for fabricating low-power capacitive humidity sensors without the use of a cleanroom environment. A maskless laser engraving system was utilized to fabricate two different gold electrode structures, interdigitated electrodes and Hilbert\\'s fifth-order fractal. The capacitive structures were implemented on a flexible PET substrate. The usage of Nafion, a well-known polymer for its hydrophilic properties as a sensing film, was attempted on the PET and outperformed the current efforts in flexible substrates. Its humidity sensing properties were evaluated in an automated gas setup with a relative humidity (RH %) ranging from 15% to 95 %.

  8. Investigations into sensing characteristics of circular thin-plate electrostatic sensors for gas path monitoring

    Institute of Scientific and Technical Information of China (English)

    Zhongsheng Chen; Xin Tang; Zheng Hu; Yongmin Yang

    2014-01-01

    Circular thin-plate electrostatic sensors are promising in gas path monitoring due to their advantages of non-intrusiveness and easy installation. The spatial sensitivity and filtering effect are two important performance parameters. In this paper, an analytically mathematical model of induced charge on a circular thin-plate electrode is first derived. Then the spatial sensitivity and fil-tering effect of the circular electrostatic sensor are investigated by numerical calculations. Finally, experimental studies are performed to testify the theoretical results. Both theoretical and experimen-tal results demonstrate that circular thin-plate electrostatic sensors act as a low-pass filter in the spa-tial frequency domain, and both the spatial filtering effect and the temporal frequency response characteristics depend strongly on the spatial position and velocity of the charged particle. These conclusions can provide guidelines for the optimal design of circular thin-plate electrostatic sensors.

  9. Torsion sensing characteristics of long period fiber gratings fabricated by femtosecond laser in optical fiber

    Science.gov (United States)

    Duan, Ji'an; Xie, Zheng; Wang, Cong; Zhou, Jianying; Li, Haitao; Luo, Zhi; Chu, Dongkai; Sun, Xiaoyan

    2016-09-01

    With the alignment of the fiber core systems containing dual-CCDs and high-precision electric displacement platform, twisted long period fiber gratings (T-LPFGs) were fabricated in two different twisted SMF-28 fibers by femtosecond laser. The torsion characteristics of the T-LPFGs were experimentally and theoretical investigated and demonstrated in this study. The achieved torsion sensitivity is 117.4 pm/(rad/m) in the torsion range -105-0 rad/m with a linearity of 0.9995. Experimental results show that compared with the ordinary long period fiber gratings, the resonance wavelength of the gratings presents an opposite symmetrical shift depending on the twisting direction after the applied torsion is removed. In addition, high sensitivity could be obtained, which is very suitable for the applications in the torsion sensor. These results are important for the design of new torsion sensors based on T-LPFGs fabricated by femtosecond laser.

  10. Refractive index sensing characteristics of D-shape double core photonic crystal fiber based on surface plasmon resonance

    Science.gov (United States)

    Liu, Feng; Li, Shi-tao; Guo, Xuan

    2016-10-01

    A refractive index (RI) sensor and its sensing characteristics based on surface plasmon resonance (SPR) of D-shape double core photonic crystal fiber (DC-PCF) are researched theoretically in this letter. The basic sensor principle is the SPR light intensity modulation of polished D-shape DC-PCF. The influence of the polished angle and depth on the DC-PCF SPR characteristics is discussed extensively by using the finite element method (FEM). The effects of the coated metal type and its layer thickness on the resonant intensity are also analyzed. The relationship between the analyte RI and resonant wavelength is numerically simulated. The theoretical results show that the sensor's RI sensitivity exhibits about 2000 nm/RIU with the structure parameters of 60° polished angle, 58.5μm polished depth and 70nm thickness of the silver layer. Furthermore, if the single wavelength laser is chosen, the detection of the two core light intensity difference will improve the ability of resistance to environmental interference. The simple sensor structure and high sensitivity can make this technology for online refractive index measurement in widespread areas.

  11. 光纤SPR湿敏传感器及其共振光谱特性研究%Research on Optical Fiber SPR Humidity Sensor and Resonance Spectrum Characteristic

    Institute of Scientific and Technical Information of China (English)

    张少华; 曾捷; 孙晓明; 穆昊; 梁大开

    2012-01-01

    A new type of humidity sensor based on optical fiber SPR sensor probe was introduced and manufactured. Firstly the sensitivity of optical fiber SPR sensor probe to environment humidity was studied. On this basis, coating with thin PVA film of different thickness and with capacity of adsorbing water molecule on the surface of optical fiber SPR sensor probe, for the purpose of monitoring relative humidity was proposed. The research shows that the SPR sensor probe coated with double layers of thin PVA film gets better detection result, and humidity measurement sensitivity is 1. 59%/%RH, being improved notably compared with SPR optical fiber probe. The SPR sensor coated with single layer of thin PVA film has relative humidity measuring sensitivity of 2. 411 nm/5/6RH related to resonance wavelength in high humidity area. In addition, the new type of optical fiber humidity-sensitive probe with PVA film losing efficiency can be reusable after special treatment%提出并研制了基于光纤SPR传感探针的新型湿敏传感器.首先研究了光纤SPR传感探针对环境湿度变化的敏感特性,在此基础上提出在光纤SPR传感探针表面增覆不同厚度且具有水分子吸附功能的PVA薄膜来实现环境相对湿度的监测.研究结果表明,增覆双层PVA薄膜的光纤SPR传感探针在高湿区具有较好监测效果,其共振强度对应的相对湿度测量灵敏度达到1.59%/%RH,较光纤SPR探针呈现显著提高.而增覆单层PVA薄膜的光纤SPR传感探针在高湿区共振波长对应的相对湿度监测灵敏度达到2.411nm/%RH.此外所提出的新型光纤SPR湿敏探针在PVA薄膜失效后经过特殊工艺处理仍可重复镀膜使用.

  12. Strain Sensing Characteristics of Rubbery Carbon Nanotube Composite for Flexible Sensors.

    Science.gov (United States)

    Choi, Gyong Rak; Park, Hyung-ki; Huh, Hoon; Kim, Young-Ju; Ham, Heon; Kim, Hyoun Woo; Lim, Kwon Taek; Kim, Sung Yong; Kang, Inpil

    2016-02-01

    In this study, the piezoresistive properties of CNT (Carbon Nanotube)/EPDM composite are characterized for the applications of a flexible sensor. The CNT/EPDM composites were prepared by using a Brabender mixer with MWCNT (Multi-walled Carbon Nanotube) and organoclay. The static and quasi-dynamic voltage output responses of the composite sensor were also experimentally studied and were compared with those of a conventional foil strain gage. The voltage output by using a signal processing system was fairly stable and it shows somehow linear responses at both of loading and unloading cases with hysteresis. The voltage output was distorted under a quasi-dynamic test due to its unsymmetrical piezoresistive characteristics. The CNT/EPDM sensor showed quite tardy response to its settling time test under static deflections and that would be a hurdle for its real time applications. Furthermore, since the CNT/EPDM sensor does not have directional voltage output to tension and compression, it only could be utilized as a mono-directional force sensor such as a compressive touch sensor.

  13. 干燥介质相对湿度对胡萝卜片热风干燥特性的影响%Effect of hot air relative humidity on drying characteristics of carrot slabs

    Institute of Scientific and Technical Information of China (English)

    巨浩羽; 肖红伟; 郑霞; 郭秀良; 刘嫣红; 张卫鹏; 袁婧; 高振江

    2015-01-01

    Drying is one of the most common processing methods for fruits and vegetables. Enhancing drying rate and dried products’ quality as well as energy efficiency is very tempting for drying industry. Recently, a lot of investigations have illustrated that drying temperature, air velocity and sample’s thickness have a significant influence on drying process. High drying temperature and velocity can extensively reduce drying time and enhance drying rate. However, few investigations take into account hot air relative humidity (RH) as important drying parameter in drying process. Some literatures showed that decreasing RH would lead to a steeper slope of moisture ratio decreasing. Whereas, some researches pointed out that there was no effect of RH on the drying rate in specified range of RH. In general, high RH can contribute to a rapid increase of product temperature. It is expected that with high RH pretreatment, the temperature and moisture tend to be equivalent and after that the RH can be reduced to enhance drying rate. In this circumstance, the temperature and moisture gradient between sample and drying air become consistent and the high efficient drying process could be achieved. Drying process refers to heat and mass transfer efficiency, energy consuming and products quality. Theoretical models, semi-theoretical and empirical models are widely used to describe drying process. However, those models neglect the fundamentals of the drying process and their parameters have no physical meaning and do not help in the optimization. Recently, Weibull model was used to describe drying process because of its applicability. Based on Weibull model, the relationship between scale parameters as well as shape parameters and drying process could be developed. So in current work, carrot slabs were used to explore the drying characteristics under the drying condition of constant RH and of decreasing RH step by step, together with constant drying temperature and constant air

  14. PSYCRODATA: a software which calculates the air humidity characteristics and relate its with the variations of the gamma environmental bottom; PSYCRODATA: software que calcula las caracteristicas de la humedad del aire y las relaciona con las variaciones del fondo gamma ambiental

    Energy Technology Data Exchange (ETDEWEB)

    Alonso A, D.; Dominguez L, O.; Ramos V, O.; Caveda R, C.A.; Capote F, E. [CPHR, Calle 20 No. 4113 e/41 y 47, Playa, C.P. 11300, A.P. 6195, C.P. 10600 La Habana (Cuba); Dominguez G, A.; Valdes S, E. [Instituto Superior de Ciencias y Tecnicas Aplicadas (INSTEC), La Habana (Cuba); Rodriguez V, E. [Instituto de Meteorologia (INSMET), La Habana (Cuba)]. e-mail: lola@cphr.edu.cu

    2006-07-01

    The computer tool 'Psycrodata', able to calculate the values of those characteristics of the humidity of the air starting from the measurements carried out of humidity and temperature in the post of occident of the National Net of Environmental Radiological Surveillance was obtained. Among the facilities that 'Psycrodata' toasts it is the keeping the obtained information in a database facilitating the making of reports. For another part the possibility of selection of different approaches for the calculation and the introduction of the psicrometric coefficient to use, its make that each station can have the suitable psicrometric chart keeping in mind the instrumentation and the characteristics of the area of location of the same one. Also, can have facilities to import text files for later on to be plotted, it allowed to correlate the absorbed dose rate in air due to the environmental gamma radiation, besides of the temperature and the humidity, with the tension of the water steam, the temperature of the dew point and the saturation deficit. (Author)

  15. 1960~2013年白龙江流域地表湿润指数演变特征%CHARACTERISTICS OF SURFACE HUMIDITY INDEX IN BAILONGJIANG RIVER BASIN DURING 1960~2013

    Institute of Scientific and Technical Information of China (English)

    张芳芳; 王强; 张喜风

    2015-01-01

    At present, climate warming as one of the main feature of the global climate change has become hot is-sue for scholars worldwide. Drought, as a potential natural phenomenon, is considered to be one of the most serious natural disasters in the world having great influence on economic damage. Therefore, an objective and reasonable drought assessment index becomes even more important. Based on the daily temperature, wind speed, total solar radiation, related humidity, sunshine hours, and precipitation data of Bailong River Basion from 1960 to 2013, hu-midity index was estimated and analyzed using the methods of Penman -Monteith model, linear trend, Mann -Kendall as well as Morlet wavelet under the background of climate change. The results showed that in recent 54 years, the surface humidity index in the Bailong River Basion displayed an increasing trend with fluctuation and the increasing rate was 0. 90/10a, indicating that climate the slightly trended to be wet in the study area. Additionally, the surface humidity index in the 1970s had the greatest increase among all the decades. However, the surface hu-midity index displayed a decreasing trend in the 1990s as well as the 2000s. It was found that the spatial distribu-tion pattern of surface humidity index in the Bailong River Basion presented variously. Namely, the rates of chan-ging trend in the upper, middle and lower reaches were -0. 02/10a, 0. 70/10a and 0. 86/10a, respectively. Ad-ditionally, the decadal average of the surface humidity index in lower reaches was generally higher than that of in middle and upper reaches, while the trend of the surface humidity index was lower than that of middle reaches. From average of the years, the surface humidity index of the middle and lower reaches of Bailong River Basin were significantly higher than that of the upstream region. The major cycle of upper middle, downstream of the Bailong River and Basin were changing respectively with 16a, 20a, 15a, 7a, and the abrupt

  16. Doing hydrology backwards in tropical humid catchments

    Science.gov (United States)

    Real Rangel, R.; Brena-Naranjo, J. A.; Pedrozo-Acuña, A.

    2015-12-01

    Top-down approaches in hydrology offer the possibility to predict water fluxes at the catchment scale based on the interpretation of the observed hydrological response at the catchment itself. Doing hydrology backwards (inferring precipitation and evapotranspiration rates at the catchment scale from streamflow measurements, see Kirchner (2009)) can be a useful methodology for estimating water fluxes at the catchment and regional scales. Previous studies using this inverse modeling approach have been performed in regions (UK, Switzerland, France, Eastern US) where energy-limited (in winter and early spring) and water-limited conditions (in summer) prevail during a large period of the year. However, such approach has not been tested in regions characterized by a quasi-constant supply of water and energy (e.g. humid tropics). The objective of this work is to infer annual rates of precipitation and evapotranspiration over the last decade in 10 catchments located in Mexico's tropical humid regions. Hourly discharge measurements during recession periods were analyzed and parameters for the nonlinear storage-discharge relationship of each catchment were derived. Results showed large variability in both catchment-scale precipitation and evapotranspiration rates among the selected study sites. Finally, a comparison was done between such estimates and those obtained from remotely-sensed data (TRMM for precipitation and MOD16 for evapotranspiration).

  17. Humid free efficient solar panel

    Science.gov (United States)

    Panjwani, Manoj Kumar; Panjwani, Suresh Kumar; Mangi, Fareed Hussain; Khan, Danish; Meicheng, Li

    2017-09-01

    The paper examines the impact of the humidity on the Solar panels which makes a space for the drastic variation in the power generated and makes the device less efficient. Humidity readily affects the efficiency of the solar cells and creates a minimal layer of water on its surface. It also decreases the efficiency by 10-20% of the total power output produced. Moreover, to handle this issue, all around characterized measures are required to be taken to guarantee the smooth working of the solar panels utilized in humid areas. In connection with this issue, Karachi, the biggest city of Pakistan which is located near the costal line touching Arabian Sea, was taken as a reference city to measure the humidity range. In Karachi, the average humidity lies between 25-70% (as per Pakistan Meteorological Department PMD), that indirectly leads in decreasing power acquired from a Solar Panel and develops various complexities for the solar system. The system on average experiences stability issues, such as those of power fluctuations etc., due to which, the whole solar system installed observes abnormal variations in acquired power. Silica Gel was used as a desiccant material in order to assure dryness over the solar panel. More than four experiments were conducted with the usage of water absorbent to improve the efficiency and to make system more power efficient.

  18. Air humidity requirements for human comfort

    DEFF Research Database (Denmark)

    Toftum, Jørn; Fanger, Povl Ole

    1999-01-01

    level near 100% rh. For respiratory comfort are the requirements much more stringent and results in lower permissible indoor air humidities. Compared with the upper humidity limit specified in existing thermal comfort standards, e.g. ASHRAE Addendum 55a, the humidity limit based on skin humidity...

  19. Photogated humidity-driven motility

    Science.gov (United States)

    Zhang, Lidong; Liang, Haoran; Jacob, Jolly; Naumov, Panče

    2015-06-01

    Hygroinduced motion is a fundamental process of energy conversion that is essential for applications that require contactless actuation in response to the day-night rhythm of atmospheric humidity. Here we demonstrate that mechanical bistability caused by rapid and anisotropic adsorption and desorption of water vapour by a flexible dynamic element that harnesses the chemical potential across very small humidity gradients for perpetual motion can be effectively modulated with light. A mechanically robust material capable of rapid exchange of water with the surroundings is prepared that undergoes swift locomotion in effect to periodic shape reconfiguration with turnover frequency of <150 min-1. The element can lift objects ~85 times heavier and can transport cargos ~20 times heavier than itself. Having an azobenzene-containing conjugate as a photoactive dopant, this entirely humidity-driven self-actuation can be controlled remotely with ultraviolet light, thus setting a platform for next-generation smart biomimetic hybrids.

  20. Surface characteristics of debris-covered glacier tongues in the Khumbu Himalaya derived from remote sensing texture analysis

    Science.gov (United States)

    Racoviteanu, Adina; Arnaud, Yves; Nicholson, Lindsay

    2013-04-01

    The delineation of debris-covered glaciers remains a challenge in optical remote sensing, due to the similarity of the spectral signature of debris-covered ice to surrounding lateral moraines, making it difficult to apply standard semi-automated algorithms commonly used for clean ice delineation. Furthermore, supraglacial debris exhibits considerable spatial variability in its characteristics such as debris cover thickness, particle size, thermal resistance and thermal conductivity. These properties are needed in order to map the extent of debris cover and to estimate ice melt under the debris cover or at the surface. In this study we evaluate the potential of texture analysis for detecting surface characteristics of debris-cover glacier tongues in the Khumbu Himalaya, using Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) and high-resolution Ikonos data. We focus on mapping supra-glacier lakes and exposed ice walls using texture analysis algorithms such as grey-level co-occurrence measures (GLCM), filtering, image segmentation, and particle boundaries. We compare the performance of various existing commercial software suitable for texture analysis such as ERDAS Objective, Aphelion, as well as public domain image display and analysis software used originally for medical analysis, notably Image SXM and ImageJ. Preliminary results based on geostatistics and GLCM measures show differences in surface roughness of debris cover when compared to surrounding ice-free moraines. We expand on these results and aim at developing a quasi-automated algorithm for extracting surface features, which will be used as input in an energy balance model for estimating melting under debris cover as well as surface ice melt.

  1. Landscape-Level Associations of Wintering Waterbird Diversity and Abundance from Remotely Sensed Wetland Characteristics of Poyang Lake

    Directory of Open Access Journals (Sweden)

    Iryna Dronova

    2016-05-01

    Full Text Available Poyang Lake, the largest freshwater wetland in China, provides critical habitat for wintering waterbirds from the East Asian Flyway; however, landscape drivers of non-uniform bird diversity and abundance are not yet well understood. Using a winter 2006 waterbird survey, we examined the relationships among metrics of bird community diversity and abundance and landscape characteristics of 51 wetland sub-lakes derived by an object-based classification of Landsat satellite data. Relative importance of predictors and their sets was assessed using information-theoretic model selection and the Akaike Information Criterion. Ordinary least squares regression models were diagnosed and corrected for spatial autocorrelation using spatial autoregressive lag and error models. The strongest and most consistent landscape predictors included Normalized Difference Vegetation Index for mudflat (negative effect and emergent grassland (positive effect, total sub-lake area (positive effect, and proportion of submerged vegetation (negative effect. Significant spatial autocorrelation in linear regression was associated with local clustering of response and predictor variables, and should be further explored for selection of wetland sampling units and management of protected areas. Overall, results corroborate the utility of remote sensing to elucidate potential indicators of waterbird diversity that complement logistically challenging ground observations and offer new hypotheses on factors underlying community distributions.

  2. Sensing characteristics of pure-shear film bulk acoustic resonator in viscous liquids

    Science.gov (United States)

    Chen, Da; Song, Shuren; Zhang, Dexue; Wang, Peng; Liu, Weihui

    2017-03-01

    We presented a pure-shear film bulk acoustic resonator (FBAR) and investigated its sensing characteristics in viscous liquids. In the resonator, the electrodes were located on the surface of c-axis-oriented AlN film to generate the lateral electric field and excite the shear acoustic resonance. Compared with the typical quasi-shear film bulk acoustic resonator based on inclined c-axis-oriented AlN or ZnO piezoelectric film, the proposed device exhibits significantly higher Q-factors and a notably improved detection limit, particularly in water and viscous liquids. The frequency shifts show a linear dependency on the square root of the product of the liquid viscosity and density of the glycerol solution in the viscosity range of 1-5 mPaṡs. Furthermore, we measured the mass sensitivity through real-time monitoring of the frequency change during the volatilization process of the loaded saline solutions. The proposed device shows the mass sensitivity of 465 Hzṡcm2/ng and the mass resolutions of 0.17 ng/cm2 in air, 0.25 ng/cm2 in water and 2.08 ng/cm2 in 50% glycerol solution, respectively. The obtained results clearly indicate that the proposed device is capable of using in liquid phase detection with high sensitivity requirements.

  3. CO2 sensing characteristics and mechanism for LaCoO3 predicted by density function theory

    Science.gov (United States)

    Shi, Changmin; Qin, Hongwei; Li, Ling; Chen, Yanping; Ju, Lin; Hu, Jifan

    2015-02-01

    The adsorption properties of CO2 molecule on the LaCoO3 (1 1 0) surface with one/two O2 pre-adsorption are studied by density functional theory method. Our calculated results show that the CO2 molecule acts as an acceptor when it is introduced into the LaCoO3 (1 1 0) surface with one O2 pre-adsorption. It is inconsistent with the experimental results. It cannot explain the reason why the resistance of p-type perovskite oxide material increase after CO2 molecule is introduced. For the LaCoO3 (1 1 0) surface with two O2 pre-adsorption, the role of CO2 molecule transforms to donor from acceptor. In this mode, the electrons of CO2 molecule transfer to the LaCoO3 (1 1 0) surface with two O2 pre-adsorption, resulting in a decrease of hole-carrier concentration and an increase of resistance. The interaction between CO2 and the LaCoO3 (1 1 0) surface with two O2 pre-adsorption is responsible for the CO2 sensing characteristics and mechanism of LaCoO3.

  4. Relative humidity multi-point optical sensors system based on fast Fourier multiplexing technique

    Science.gov (United States)

    Lopez-Aldaba, A.; Lopez-Torres, D.; Elosua, C.; Auguste, J.-L.; Jamier, R.; Roy, P.; Arregui, F. J.; Lopez-Amo, M.

    2017-04-01

    In this paper, a new multipoint optical fiber system for relative humidity measurements based on SnO2-FP (Fabry-Pérot) sensing heads and an optical interrogator as single active device is presented and characterized. The interrogation of the sensing heads is carried out by monitoring the Fast Fourier Transform phase variations of the FP (Fabry-Pérot) interference frequencies. This method allows to multiplex several sensors with different wavelength spacing interference pattern. The sensors operate within a wide humidity range (20%-90% relative humidity) with low crosstalk between them. Five sensing heads have been measured using two different channels of the optical interrogator. The availability of four channels in the interrogator allows to multiplex a higher number of sensors, reducing proportionally the cost of each sensing point.

  5. Development of La3+ Doped CeO2 Thick Film Humidity Sensors

    Directory of Open Access Journals (Sweden)

    Chunjie Wang

    2014-01-01

    Full Text Available The humidity sensitive characteristics of the sensor fabricated from 10 mol% La2O3 doped CeO2 nanopowders with particle size 17.26 nm synthesized via hydrothermal method were investigated at different frequencies. It was found that the sensor shows high humidity sensitivity, rapid response-recovery characteristics, and narrow hysteresis loop at 100 Hz in the relative humidity range from 11% to 95%. The impedance of the sensor decreases by about five orders of magnitude as relative humidity increases. The maximum humidity hysteresis is about 6% RH, and the response and recovery time is 12 and 13 s, respectively. These results indicate that the nanosized La2O3 doped CeO2 powder has potential application as high-performance humidity sensor.

  6. Combining Remotely Sensed Environmental Characteristics with Social and Behavioral Conditions that Affect Surface Water Use in Spatiotemporal Modelling of Schistosomiasis in Ghana

    Science.gov (United States)

    Kulinkina, A. V.; Walz, Y.; Liss, A.; Kosinski, K. C.; Biritwum, N. K.; Naumova, E. N.

    2016-06-01

    Schistosoma haematobium transmission is influenced by environmental conditions that determine the suitability of the parasite and intermediate host snail habitats, as well as by socioeconomic conditions, access to water and sanitation infrastructure, and human behaviors. Remote sensing is a demonstrated valuable tool to characterize environmental conditions that support schistosomiasis transmission. Socioeconomic and behavioral conditions that propagate repeated domestic and recreational surface water contact are more difficult to quantify at large spatial scales. We present a mixed-methods approach that builds on the remotely sensed ecological variables by exploring water and sanitation related community characteristics as independent risk factors of schistosomiasis transmission.

  7. SEMICONDUCTOR DEVICES: Humidity sensitive organic field effect transistor

    Science.gov (United States)

    Murtaza, I.; Karimov, Kh S.; Ahmad, Zubair; Qazi, I.; Mahroof-Tahir, M.; Khan, T. A.; Amin, T.

    2010-05-01

    This paper reports the experimental results for the humidity dependent properties of an organic field effect transistor. The organic field effect transistor was fabricated on thoroughly cleaned glass substrate, in which the junction between the metal gate and the organic channel plays the role of gate dielectric. Thin films of organic semiconductor copper phthalocynanine (CuPc) and semitransparent Al were deposited in sequence by vacuum thermal evaporation on the glass substrate with preliminarily deposited Ag source and drain electrodes. The output and transfer characteristics of the fabricated device were performed. The effect of humidity on the drain current, drain current-drain voltage relationship, and threshold voltage was investigated. It was observed that humidity has a strong effect on the characteristics of the organic field effect transistor.

  8. High-Performance Humidity Sensors Based on Double-Layer ZnO-TiO2 Nanofibers via Electrospinning

    Institute of Scientific and Technical Information of China (English)

    YUE Xue-Jun; HONG Tian-Sheng; XU Xing; LI Zhen

    2011-01-01

    ZnO and TiOi nanofibers are synthesized via electrospinning methods and characterized by x-ray diffraction, scanning electron microscopy, and transmission electron microscopy. Humidity sensors with double-layer sensing Sims are fabricated by spinning the ZnO and TiOz nanofibers on ceramic substrates sequentially. Compared with sensors loading only one type of nanoBber, the double-layer sensors exhibit much better sensing properties. The corresponding impedance changes more than four orders of magnitude within the whole humidity range from 11% to 95% relative humidity, and the response and recovery times are about 11 and 7s, respectively. Maximum hysteresis is around 1.5% RH, and excellent stability is also observed after 180 days. The humidity sensing mechanism is discussed in terms of the sensor structure. The experimental results provide a possible route for the design and fabrication of high performance humidity sensors based on one-dimensional nanomaterials.%@@ ZnO and TiO2 nanofibers are synthesized via electrospinning methods and characterized by x-ray diffraction,scanning electron microscopy,and transmission electron microscopy.Humidity sensors with double-layer sensing films are fabricated by spinning the ZnO and TiO2 nanofibers on ceramic substrates sequentially.Compared with sensors loading only one type of nanofiber,the double-layer sensors exhibit much better sensing properties.The corresponding impedance changes more than four orders of magnitude within the whole humidity range from 11%to 95%relative humidity,and the response and recovery times are about 11 and 7s,respectively.Maximum hysteresis is around 1.5%RH,and excellent stability is also observed after 180 days.The humidity sensing mechanism is discussed in terms of the sensor structure.The experimental results provide a possible route for the design and fabrication of high performance humidity sensors based on one-dimensional nanomaterials.

  9. Spatial Aggregation of Land Surface Characteristics: Impact of resolution of remote sensing data on land surface modelling

    NARCIS (Netherlands)

    Pelgrum, H.

    2000-01-01

    Land surface models describe the exchange of heat, moisture and momentum between the land surface and the atmosphere. These models can be solved regionally using remote sensing measurements as input. Input variables which can be derived from remote sensing measurements are surface albedo, surface te

  10. 含湿量对甲烷湿空气自热重整积碳特性的影响%NUMERICAL SIMULATION ON CARBON DEPOSITION CHARACTERISTICS OF HUMIDITY RATIO ON CH4/WET AIR AUTO-THERMAL REFORMING REACTION

    Institute of Scientific and Technical Information of China (English)

    冉景煜; 涂维峰

    2011-01-01

    Catalytic combustion of hydrocarbon fuels has been considered as an effective method in power MEMS. However, the ca talyst deactivation, mainly caused by carbon deposition, is occurred ubiquity in the catalytic reforming progress. In this paper, the effects of humidity ratio on the CH4/wet air auto-thermal reforming reaction with Ni catalyst on the micro-chamber's surface were simulated. The results show that increasing the humidity ratio will promote the methane reforming reaction. The heat dissipating capacity of auto-thermal reforming and the density of carbon deposition reduce with increasing the humidity ratio. The CH4 conversion rate, density of carbon deposition and mass fraction of H2 were changed very little, they reach 53.1%, 3.07% and 2.40x10-6 kmol/m2respectively while the humidity ratio exceeds 1.20 kg/kg and mixture flow rate is 36 g/h.%微动力装置中碳氢燃料催化燃烧被认为是有效的方法,但燃烧室内燃料催化重整普遍存在由积碳导致的催化剂失活等问题.本文采用数值方法研究了微细腔中甲烷湿空气在镍基催化剂上的自热重整反应,重点分析含湿量对甲烷自热重整反应及积碳特性的影响.结果表明:含湿量将增强甲烷重整反应;自热反应散热量和表面积碳浓度均随含湿量增加而降低.混合物质量流量为36 g/h时,当含湿量d>1.20 kg/kg后,甲烷转化率、氢气质量分数和积碳浓度变化幅度很小,分别接近 53.1%、3.07%和2.40x10-6 kmol/m2.

  11. Polypyrrole Porous Micro Humidity Sensor Integrated with a Ring Oscillator Circuit on Chip

    Science.gov (United States)

    Yang, Ming-Zhi; Dai, Ching-Liang; Lu, De-Hao

    2010-01-01

    This study presents the design and fabrication of a capacitive micro humidity sensor integrated with a five-stage ring oscillator circuit on chip using the complimentary metal oxide semiconductor (CMOS) process. The area of the humidity sensor chip is about 1 mm2. The humidity sensor consists of a sensing capacitor and a sensing film. The sensing capacitor is constructed from spiral interdigital electrodes that can enhance the sensitivity of the sensor. The sensing film of the sensor is polypyrrole, which is prepared by the chemical polymerization method, and the film has a porous structure. The sensor needs a post-CMOS process to coat the sensing film. The post-CMOS process uses a wet etching to etch the sacrificial layers, and then the polypyrrole is coated on the sensing capacitor. The sensor generates a change in capacitance when the sensing film absorbs or desorbs vapor. The ring oscillator circuit converts the capacitance variation of the sensor into the oscillation frequency output. Experimental results show that the sensitivity of the humidity sensor is about 99 kHz/%RH at 25 °C. PMID:22163459

  12. Polypyrrole Porous Micro Humidity Sensor Integrated with a Ring Oscillator Circuit on Chip

    Directory of Open Access Journals (Sweden)

    De-Hao Lu

    2010-11-01

    Full Text Available This study presents the design and fabrication of a capacitive micro humidity sensor integrated with a five-stage ring oscillator circuit on chip using the complimentary metal oxide semiconductor (CMOS process. The area of the humidity sensor chip is about 1 mm2. The humidity sensor consists of a sensing capacitor and a sensing film. The sensing capacitor is constructed from spiral interdigital electrodes that can enhance the sensitivity of the sensor. The sensing film of the sensor is polypyrrole, which is prepared by the chemical polymerization method, and the film has a porous structure. The sensor needs a post-CMOS process to coat the sensing film. The post-CMOS process uses a wet etching to etch the sacrificial layers, and then the polypyrrole is coated on the sensing capacitor. The sensor generates a change in capacitance when the sensing film absorbs or desorbs vapor. The ring oscillator circuit converts the capacitance variation of the sensor into the oscillation frequency output. Experimental results show that the sensitivity of the humidity sensor is about 99 kHz/%RH at 25 °C.

  13. A Low-Power Integrated Humidity CMOS Sensor by Printing-on-Chip Technology

    Directory of Open Access Journals (Sweden)

    Chang-Hung Lee

    2014-05-01

    Full Text Available A low-power, wide-dynamic-range integrated humidity sensing chip is implemented using a printable polymer sensing material with an on-chip pulse-width-modulation interface circuit. By using the inkjet printing technique, poly(3,4-ethylene-dioxythiophene/polystyrene sulfonate that has humidity sensing features can be printed onto the top metal layer of a 0.35 μm CMOS IC. The developed printing-on-chip humidity sensor achieves a heterogeneous three dimensional sensor system-on-chip architecture. The humidity sensing of the implemented printing-on-chip sensor system is experimentally tested. The sensor shows a sensitivity of 0.98% to humidity in the atmosphere. The maximum dynamic range of the readout circuit is 9.8 MΩ, which can be further tuned by the frequency of input signal to fit the requirement of the resistance of printed sensor. The power consumption keeps only 154 μW. This printing-on-chip sensor provides a practical solution to fulfill an ultra-small integrated sensor for the applications in miniaturized sensing systems.

  14. Relative humidity sensor based on SMS fiber structure using multimode coreless fiber

    Science.gov (United States)

    Syafrani, Sanif; Hatta, Agus M.; Kusumawardhani, Apriani

    2016-11-01

    Singlemode-Multimode-Singlemode (SMS) optical fiber structure using multimode coreless have been able to sense changes in relative humidity. In this experiment the measured humidity is 60 % -90 %, while the method is done by comparing the relative humidity changes with the change in output power in the optical fiber. Then the underlying phenomena is the change in the refractive index of air as the cladding MMF coreless due to changes in relative humidity. It has been done three length variations MMF coreless to add sensitivity sensor, and the obtained sensor by 22.30 mm MMF length have the greatest sensitivity, that is 0.0747 dBm / %. Obtained conclusions on length variation will cause any change in the sensitivity significantly in relative humidity between 75 % -80 %.

  15. Humidity sensor base on the ZnO nanorods and fiber modal interferometer

    Science.gov (United States)

    Wang, Jian; Zhang, Huan; Cao, Zhigang; Zhang, Xinyu; Yin, Chenchen; Li, Kang; Zhang, Guosheng; Yu, Benli

    2016-10-01

    A novel fiber relative humidity (RH) sensor is demonstrated in this paper. The sensor is composed of a fiber Michelson modal interferometer (MMI) and the ZnO nanorods which grown on the fiber to improve the sensitivity of the sensor. Two standard single mode fibers are spliced to form the MMI, misaligned splicing program is used at the spliced point. Relative humidity sensing experiment shows that the intensity of interference spectrum changes linearly with relative humidity. With the relative humidity increasing in the range from 30% to 85%, the intensity of the dip in the interference spectrum linearly increases higher than 50%. The relative humidity response of the sensor is induced by the interference between core mode and cladding mode. The ZnO nanorods with high surface to volume ratio grown outside of the fiber cladding enhance the sensitivity of the sensor.

  16. The effects of lithographic residues and humidity on graphene field effect devices

    Indian Academy of Sciences (India)

    BEHIYE BOYARBAY KANTAR; MUH˙ITT˙IN ÖZTÜRK; H˙IDAYET ÇET˙IN

    2017-02-01

    Recently, unknown-manner changes in charge neutrality point (CNP) positioning were ascribed to humidity at graphene field effect transistors (GFETs). While the exactmeans of humidity interacting with hydrophobicgraphene remains unknown, this work examines pristine and lithographic-process-applied graphene surfaces with surface enhanced Raman spectra (SERS). SERS analysis shows that the lithographic-process-applied graphenedoes not have the same properties as those of pristine graphene. Furthermore, this study has experimentally investigated the effect of humidity on the transfer characteristics of GFET and proposed a model to explain the formationof asymmetric $I_{\\rm DS}–V_{\\rm bg}$ branches in accordance with the SERS results and humidity responses.

  17. System-in Package of Integrated Humidity Sensor Using CMOS-MEMS Technology.

    Science.gov (United States)

    Lee, Sung Pil

    2015-10-01

    Temperature/humidity microchips with micropump were fabricated using a CMOS-MEMS process and combined with ZigBee modules to implement a sensor system in package (SIP) for a ubiquitous sensor network (USN) and/or a wireless communication system. The current of a diode temperature sensor to temperature and a normalized current of FET humidity sensor to relative humidity showed linear characteristics, respectively, and the use of the micropump has enabled a faster response. A wireless reception module using the same protocol as that in transmission systems processed the received data within 10 m and showed temperature and humidity values in the display.

  18. Integrated passive and wireless sensor for magnetic fields, temperature and humidity

    KAUST Repository

    Li, Bodong

    2013-11-01

    This paper presents a surface acoustic wave-based passive and wireless sensor that can measure magnetic field, temperature and humidity. A thin film giant magnetoimpedance sensor, a thermally sensitive LiNbO3 substrate and a humidity sensitive hydrogel are integrated together with a surface acoustic wave transducer to realize the multifunctional sensor. The device is characterized using a network analyzer under sequentially changing humidity, temperature and magnetic field conditions. The first hand results show the sensor response to all three sensing parameters with small temperature interference on the magnetic signals. © 2013 IEEE.

  19. Fabrication and Evaluation of a Graphene Oxide-Based Capacitive Humidity Sensor.

    Science.gov (United States)

    Feng, Jinfeng; Kang, Xiaoxu; Zuo, Qingyun; Yuan, Chao; Wang, Weijun; Zhao, Yuhang; Zhu, Limin; Lu, Hanwei; Chen, Juying

    2016-03-01

    In this study, a CMOS compatible capacitive humidity sensor structure was designed and fabricated on a 200 mm CMOS BEOL Line. A top Al interconnect layer was used as an electrode with a comb/serpent structure, and graphene oxide (GO) was used as sensing material. XRD analysis was done which shows that GO sensing material has a strong and sharp (002) peak at about 10.278°, whereas graphite has (002) peak at about 26°. Device level CV and IV curves were measured in mini-environments at different relative humidity (RH) level, and saturated salt solutions were used to build these mini-environments. To evaluate the potential value of GO material in humidity sensor applications, a prototype humidity sensor was designed and fabricated by integrating the sensor with a dedicated readout ASIC and display/calibration module. Measurements in different mini-environments show that the GO-based humidity sensor has higher sensitivity, faster recovery time and good linearity performance. Compared with a standard humidity sensor, the measured RH data of our prototype humidity sensor can match well that of the standard product.

  20. Fabrication and Evaluation of a Graphene Oxide-Based Capacitive Humidity Sensor

    Directory of Open Access Journals (Sweden)

    Jinfeng Feng

    2016-03-01

    Full Text Available In this study, a CMOS compatible capacitive humidity sensor structure was designed and fabricated on a 200 mm CMOS BEOL Line. A top Al interconnect layer was used as an electrode with a comb/serpent structure, and graphene oxide (GO was used as sensing material. XRD analysis was done which shows that GO sensing material has a strong and sharp (002 peak at about 10.278°, whereas graphite has (002 peak at about 26°. Device level CV and IV curves were measured in mini-environments at different relative humidity (RH level, and saturated salt solutions were used to build these mini-environments. To evaluate the potential value of GO material in humidity sensor applications, a prototype humidity sensor was designed and fabricated by integrating the sensor with a dedicated readout ASIC and display/calibration module. Measurements in different mini-environments show that the GO-based humidity sensor has higher sensitivity, faster recovery time and good linearity performance. Compared with a standard humidity sensor, the measured RH data of our prototype humidity sensor can match well that of the standard product.

  1. Intensity of African Humid Periods Estimated from Saharan Dust Fluxes

    Science.gov (United States)

    Ehrmann, Werner; Schmiedl, Gerhard; Beuscher, Sarah; Krüger, Stefan

    2017-01-01

    North Africa experienced dramatic changes in hydrology and vegetation during the late Quaternary driven by insolation-induced shifts of the tropical rain belt and further modulated by millennial-scale droughts and vegetation-climate feedbacks. While most past proxy and modelling studies concentrated on the temporal and spatial dynamics of the last African humid period, little is known about the intensities and characteristics of pre-Holocene humid periods. Here we present a high-resolution record of fine-grained eastern Saharan dust from the Eastern Mediterranean Sea spanning the last 180 kyr, which is based on the clay mineral composition of the marine sediments, especially the kaolinite/chlorite ratio. Minimum aeolian kaolinite transport occurred during the African Humid Periods because kaolinite deflation was hampered by increased humidity and vegetation cover. Instead, kaolinite weathering from kaolinite-bearing Cenozoic rocks was stored in lake basins, river beds and soils during these periods. During the subsequent dry phases, fine-grained dust was mobilised from the desiccated lakes, rivers and soils resulting in maximum aeolian uptake and transport of kaolinite. The kaolinite transport decreased again when these sediment sources exhausted. We conclude that the amount of clay-sized dust blown out of the Sahara into the Eastern Mediterranean Sea is proportional to the intensity of the kaolinite weathering and accumulation in soils and lake sediments, and thus to the strength of the preceding humid period. These humid periods provided the windows for the migration of modern humans out of Africa, as postulated previously. The strongest humid period occurred during the Eemian and was followed by two weaker phases centred at ca. 100 ka and ca. 80 ka. PMID:28129378

  2. Temperature dependence of thermally-carbonized porous silicon humidity sensor

    Science.gov (United States)

    Björkqvist, M.; Paski, J.; Salonen, J.; Lehto, V.-P.

    2005-06-01

    Thermal carbonization of porous silicon (PS) at 820 °C under acetylene atmosphere is an appropriate method for humidity sensing purposes. It produces stable and hydrophilic surface still maintaining originally large specific surface area of PS. We report the temperature dependence of various electrical param- eters measured for the thermally-carbonized PS humidity sensor. Capacitance of the sensor in dry air (6 RH%) is almost constant at various temperatures, whereas in higher relative humidity values, the temperature dependence becomes evident. The resistance variation of the sensor is less dependent on RH as the temperature increases. While the capacitance showed linear behavior as a function of temperature, the resistance had a clear non-linear temperature dependence. In order to get information about the effects of frequency on capacitance values, we measured a phase angle and admittance of the sensor as a function of frequency at three different temperatures in low and high humidity. According to these results, it is preferable to operate this sensor construction using low frequency (<1 kHz).

  3. Effect of humid air exposure on photoemissive and structural properties of KBr thin film photocathode

    CERN Document Server

    Rai, R; Ghosh, N; Singh, B K

    2014-01-01

    We have investigated the influence of water molecule absorption on photoemissive and structural properties of potassium bromide (KBr) thin film photocathode under humid air exposure at relative humidity (RH) 65%. It is evident from photoemission measurement that the photoelectron yield of KBr photocathode is degraded exponentially with humid air exposed time. Structural studies of the "as-deposited" and "humid air aged" films reveal that there is no effect of RH on film's crystalline face centered cubic (fcc) structure. However, the average crystallite size of "humid air exposed film" KBr film has been increased as compared to "as-deposited". In addition, topographical properties of KBr film are also examined by means of scanning electron microscope (SEM), transmission electron microscope (TEM) and atomic force microscope (AFM) and it is observed that granular characteristic of film has been altered, even for short exposure to humid air.

  4. Novel capacitance-type humidity sensor based on multi-wall carbon nanotube/SiO2 composite films

    Institute of Scientific and Technical Information of China (English)

    Liu Xiaowei; Zhao Zhengang; Li Tuo; Wang Xin

    2011-01-01

    A novel capacitance-type relative humidity (RH) sensor based on multi-wall carbon nanotubc/SiO2 (MWCNTs/SiO2) composite film is reported.Details of the fabrication process,possible sensing mechanism and sensing characteristics,such as linearity and sensitivity,are described.The capacitance of the MWCNTs/SiO2 composite film shows typical concentration percolation behavior with increasing MWCNT loading.At loadings below the percolation threshold (1.842wt%),the sensor capacitance increases obviously with increasing MWCNTs.The water condensed in the MWCNTs/SiO2 layer can lower the percolation threshold and increase the sensor capacitance.The sensor with MWCNT concentration of 1 wt% has the best properties.The sensor has a humidity sensitivity of about 673 pF/% RH and a linearity correlation of 0.98428.The response time of the sensor to RH is about 40 s and the recovery time is about 2 s.

  5. Thin films from hydrophilic poly(N,N-dimethyl acrylamide) copolymers as optical indicators for humidity

    Science.gov (United States)

    Lazarova, K.; Todorova, L.; Christova, D.; Vasileva, M.; Georgiev, R.; Madjarova, V.; Babeva, T.

    2017-01-01

    In the present paper we study thin films from poly(N,N-dimethyl acrylamide)-poly(ethylene oxide) (PDMAA/PEO) copolymers of different composition and structure in order to implement them as sensitive media for optical indicators for humidity. PDMAA/PEO di- and triblock copolymers were synthesized via redox polymerization in aqueous media. Thin films were deposited on silicon substrates by spin coating method using polymers solutions with appropriate concentrations. Refractive index, extinction coefficient and thickness of the films are calculated from reflectance spectra of the films deposited on silicon substrates using non-linear curve fitting method. Sensing properties of the films were tested by films exposure to different humidity levels followed by in-situ monitoring of the changes in the optical properties. The influence of the polymer structure and postdeposition annealing on the optical and sensing properties of the films was investigated. The potential application of selected polymers for optical sensing of humidity were demonstrated and discussed.

  6. Humidity Detection Using Metal Organic Framework Coated on QCM

    KAUST Repository

    Kosuru, Lakshmoji

    2016-06-28

    Quartz crystal microbalance (QCM) coated with poly-4-vinylpyridine (PVP) and metal organic framework HKUST-1 are investigated and compared for humidity sensing. Drop casting method is employed to coat the PVP and HKUST-1 solutions onto the surface of a quartz crystal microbalance. The resonance frequencies of these sensors with varying relative humidity (RH) from 22% RH to 69% RH are measured using impedance analysis method. The sensitivity, humidity hysteresis, response, and recovery times of these sensors are studied. The sensitivities of uncoated, PVP, and HKUST-1 coated QCM sensors are 7 Hz, 48 Hz, and 720 Hz, respectively, in the range of 22% RH–69% RH. The extraction of desorption rate and adsorption energy associated with the adsorption and desorption of water molecules on these surfaces reveals that HKUST-1 has better sensing properties than PVP and uncoated QCM sensors. In this work, the HKUST-1 coated QCM is shown to be a promising material for moisture detection.

  7. Surface Characterization of pNIPAM Under Varying Absolute Humidity

    Science.gov (United States)

    Chhabra, Arnav; Kanapuram, Ravitej; Leva, Harrison; Trejo, Juan; Kim, Tae Jin; Hidrovo, Carlos

    2012-11-01

    Poly(N-isopropylacrylamide) has become ubiquitously known as a ``smart'' polymer, showing many promising applications in tissue engineering and drug delivery systems. These applications are particularly reliant on its trenchant, thermally induced hydrophilic-hydrophobic transition that occurs at the lower critical solution temperature (LCST). This feature imparts the pNIPAM programmable adsorption and release capabilities, thus eliminating the need for additional enzymes when removing cells from pNIPAM coated surfaces and leaving the extracellular matrix proteins of the cells largely untouched. The dependence of the LCST on molecular weight, solvent systems, and various salts has been studied extensively. However, what has not been explored is the effect of humidity on the characteristic properties of the polymer, specifically the LCST and the magnitude of the hydrophilic-hydrophobic transition. We studied the surface energy variation of pNIPAM as a function of humidity by altering the absolute humidity and keeping the ambient temperature constant. Our experiments were conducted inside a cuboidal environmental chamber with control over the temperature and humidity inside the chamber. A controlled needle was employed to dispense size-regulated droplets. Throughout this process, a CCD camera was used to image the droplet and the static contact angle was determined using image processing techniques. The behavior of pNIPAM as a function of humidity is presented and discussed.

  8. Selective gas sensing for photonic crystal lasers

    DEFF Research Database (Denmark)

    Smith, Cameron; Christiansen, Mads Brøkner; Buss, Thomas

    2011-01-01

    We facilitate photonic crystal lasers to sense gases via an additional swelling polymer film. We describe the transduction transfer function and experimentally demonstrate an enhanced ethanol vapor sensitivity over 15 dB with low humidity crosstalk.......We facilitate photonic crystal lasers to sense gases via an additional swelling polymer film. We describe the transduction transfer function and experimentally demonstrate an enhanced ethanol vapor sensitivity over 15 dB with low humidity crosstalk....

  9. Utilization of remote sensing data on meteorological and vegetation characteristics for modeling water and heat regimes of large agricultural region

    Science.gov (United States)

    Muzylev, Eugene; Startseva, Zoya; Uspensky, Alexander; Volkova, Elena

    2016-04-01

    Presently, physical-mathematical models such as SVAT (Soil-Vegetation-Atmosphere-Transfer) developed with varying degrees of detail are one of the most effective tools to evaluate the characteristics of the water and heat regimes of vegetation covered territories. The produced SVAT model is designed to calculate the soil water content, evapotranspiration (evaporation from bare soil and transpiration), infiltration of water into the soil, vertical latent and sensible heat fluxes and other water and heat regime characteristics as well as vegetation and soil surface temperatures and the temperature and soil moisture distributions in depth. The model is adapted to satellite-derived estimates of precipitation, land surface temperatures and vegetation cover characteristics. The case study has been carried out for the located in the forest-steppe zone territory of part of the agricultural Central Black Earth Region of Russia with coordinates 49° 30'-54° N and 31° -43° E and area of 227 300 km2 for years 2011-2014 vegetation seasons. The soil and vegetation characteristics are used as the model parameters and the meteorological characteristics are considered to be input variables. These values have been obtained from ground-based observations and satellite-based measurements by radiometers AVHRR/NOAA, MODIS/EOS Terra and Aqua, SEVIRI/MSG-2,-3 (Meteosat-9, -10). To provide the retrieval of meteorological and vegetation cover characteristics the new and pre-existing methods and technologies of above radiometer thematic processing data have been developed or refined. From AVHRR data there have been derived estimates of precipitation P, efficient land surface temperature (LST) Ts.eff and emissivity E, surface-air temperature at a level of vegetation cover Ta, normalized difference vegetation index NDVI, leaf area index LAI and vegetation cover fraction B. The remote sensing products LST Tls, E, NDVI, LAI derived from MODIS data and covering the study area have been

  10. pH sensing characteristics and biosensing application of solution-gated reduced graphene oxide field-effect transistors.

    Science.gov (United States)

    Sohn, Il-Yung; Kim, Duck-Jin; Jung, Jin-Heak; Yoon, Ok Ja; Thanh, Tien Nguyen; Quang, Trung Tran; Lee, Nae-Eung

    2013-07-15

    Solution-gated reduced graphene oxide field-effect transistors (R-GO FETs) were investigated for pH sensing and biochemical sensing applications. A channel of a networked R-GO film formed by self-assembly was incorporated as a sensing layer into a solution-gated FET structure for pH sensing and the detection of acetylcholine (Ach), which is a neurotransmitter in the nerve system, through enzymatic reactions. The fabricated R-GO FET was sensitive to protons (H(+)) with a pH sensitivity of 29 mV/pH in terms of the shift of the charge neutrality point (CNP), which is attributed to changes in the surface potential caused by the interaction of protons with OH surface functional groups present on the R-GO surface. The R-GO FET immobilized with acetylcholinesterase (AchE) was used to detect Ach in the concentration range of 0.1-10mM by sensing protons generated during the enzymatic reactions. The results indicate that R-GO FETs provide the capability to detect protons, demonstrating their applicability as a biosensing device for enzymatic reactions.

  11. Effects of Niobium-Loading on Sulfur Dioxide Gas-Sensing Characteristics of Hydrothermally Prepared Tungsten Oxide Thick Film

    Directory of Open Access Journals (Sweden)

    Viruntachar Kruefu

    2015-01-01

    Full Text Available Nb-loaded hexagonal WO3 nanorods with 0–1.0 wt% loading levels were successfully synthesized by a simple hydrothermal and impregnation process and characterized for SO2 sensing. Nb-loaded WO3 sensing films were produced by spin coating on alumina substrate with interdigitated gold electrodes and annealed at 450°C for 3 h in air. Structural characterization by X-ray diffraction, high-resolution transmission electron microscopy, and Brunauer-Emmett-Teller analysis showed that spherical, oval, and rod-like Nb nanoparticles with 5–15 nm mean diameter were uniformly dispersed on hexagonal WO3 nanorods with 50–250 nm diameter and 100 nm–5 µm length. It was found that the optimal Nb loading level of 0.5 wt% provides substantial enhancement of SO2 response but the response became deteriorated at lower and higher loading levels. The 0.50 wt% Nb-loaded WO3 nanorod sensing film exhibits the best SO2 sensing performances with a high sensor response of ~10 and a short response time of ~6 seconds to 500 ppm of SO2 at a relatively low optimal operating temperature of 250°C. Therefore, Nb loading is an effective mean to improve the SO2 gas-sensing performances of hydrothermally prepared WO3 nanorods.

  12. Surface-type humidity sensor based on cellulose-PEPC for telemetry systems

    Institute of Scientific and Technical Information of China (English)

    Kh. S. Karimov; M.Saleem; T. A. Qasuria; M. Farooq

    2011-01-01

    Au/cellulose-PEPC/Au surface-type humidity sensors were fabricated by drop-casting cellulose and poly-N-epoxypropylcarbazole (PEPC) blend thin films. A blend of 2wt% of each cellulose and PEPC in benzol was used for the deposition of humidity sensing films. Blend films were deposited on glass substrates with preliminary deposited surface-type gold electrodes. Films of different thicknesses of cellulose and PEPC composite were deposited by drop-casting technique. A change in electrical resistance and capacitance of the fabricated devices was observed by increasing the relative humidity in the range of 0-95% RH. It was observed that the capacitances of the sensors increase, while their resistances decrease with increasing the relative humidity. The sensors were connected to op-amp square wave oscillators. It was observed that with increasing the relative humidity, the oscillator's frequencies were also increased in the range of 4.2-12.0 kHz for 65/μm thick film sample, 4.1-9.0 kHz for 88 μm thick film sample, and 4.2-9.0 kHz for 210 μm sample. Effects of film thickness on the oscillator's frequency with respect to humidity were also investigated. This polymer humidity sensor controlled oscillator can be used for short-range and long-range remote systems at environmental monitoring and assessment of the humidity level.

  13. Highly sensitive and ultrafast response surface acoustic wave humidity sensor based on electrospun polyaniline/poly(vinyl butyral) nanofibers

    Energy Technology Data Exchange (ETDEWEB)

    Lin Qianqian [Department of Polymer Science and Engineering, Cyrus Tang Center for Sensor Materials and Applications, Zhejiang University, MOE Key Laboratory of Macromolecule Synthesis and Functionalization, Hangzhou 310027 (China); Li Yang, E-mail: liyang@zju.edu.cn [Department of Polymer Science and Engineering, Cyrus Tang Center for Sensor Materials and Applications, Zhejiang University, MOE Key Laboratory of Macromolecule Synthesis and Functionalization, Hangzhou 310027 (China); Yang Mujie [Department of Polymer Science and Engineering, Cyrus Tang Center for Sensor Materials and Applications, Zhejiang University, MOE Key Laboratory of Macromolecule Synthesis and Functionalization, Hangzhou 310027 (China)

    2012-10-20

    Highlights: Black-Right-Pointing-Pointer Polyanline/poly(vinyl butyral) nanofibers are prepared by electrospinning. Black-Right-Pointing-Pointer Nanofiber-based SAW humidity sensor show high sensitivity and ultrafast response. Black-Right-Pointing-Pointer The SAW sensor can detect very low humidity. - Abstract: Polyaniline (PANi) composite nanofibers were deposited on surface acoustic wave (SAW) resonator with a central frequency of 433 MHz to construct humidity sensors. Electrospun nanofibers of poly(methyl methacrylate), poly(vinyl pyrrolidone), poly(ethylene oxide), poly(vinylidene fluoride), poly(vinyl butyral) (PVB) were characterized by scanning electron microscopy, and humidity response of corresponding SAW humidity sensors were investigated. The results indicated that PVB was suitable as a matrix to form nanofibers with PANi by electrospinning (ES). Electrospun PANi/PVB nanofibers exhibited a core-sheath structure as revealed by transmittance electron microscopy. Effects of ES collection time on humidity response of SAW sensor based on PANi/PVB nanofibers were examined at room temperature. The composite nanofiber sensor exhibited very high sensitivity of {approx}75 kHz/%RH from 20 to 90%RH, ultrafast response (1 s and 2 s for humidification and desiccation, respectively) and good sensing linearity. Furthermore, the sensor could detect humidity as low as 0.5%RH, suggesting its potentials for low humidity detection. Attempts were done to explain the attractive humidity sensing performance of the sensor by considering conductivity, hydrophilicity, viscoelasticity and morphology of the polymer composite nanofibers.

  14. Remote Sensing Monitoring of Tobacco Field Based on Phenological Characteristics and Time Series Image——A Case Study of Chengjiang County, Yunnan Province, China

    Institute of Scientific and Technical Information of China (English)

    PENG Guangxiong; DENG Lei; CUI Weihong; MING Tao; SHEN Wei

    2009-01-01

    Using three-phase remote sensing images of China-Brazil Earth Resources Satellite 02B (CBERS02B) and Landsat-5 TM, tobacco field was extracted by the analysis of time series image based on the different phenological characteristics between tobacco and other crops. The spectral characteristics of tobacco and corn in luxuriant growth stage are very similar, which makes them difficult to be distinguished using a single-phase remote sensing image. Field film after tobacco seedlings transplanting can be used as significant sign to identify tobacco. Remote sensing interpretation map based on the fusion image of TM and CBERS02B's High-Resolution (HR) camera image was used as standard reference material to evaluate the classification accuracy of Spectral Angle Mapper (SAM) and Maximum Likelihood Classifier (MLC) for time series image based on full samples test method. SAM has higher classification accuracy and stability than MLC in dealing with time series image. The accuracy and Kappa of tobacco coverage extracted by SAM are 83.4% and 0.692 respectively, which can achieve the accuracy required by tobacco coverage measurement in a large area.

  15. Effects of High-Humidity Aging on Platinum, Palladium, and Gold Loaded Tin Oxide—Volatile Organic Compound Sensors

    Directory of Open Access Journals (Sweden)

    Maiko Nishibori

    2010-07-01

    Full Text Available This study is an investigation of high-humidity aging effects on the total volatile organic compound (T–VOC gas-sensing properties of platinum, palladium, and gold-loaded tin oxide (Pt,Pd,Au/SnO2 thick films. The sensor responses of the high-humidity aged Pt,Pd,Au/SnO2, a non-aged Pt,Pd,Au/SnO2, and a high-humidity aged Pt/SnO2 to T–VOC test gas have been measured. The high-humidity aging is an effective treatment for resistance to humidity change for the Pt,Pd,Au/SnO2 but not effective for the Pt/SnO2. The mechanism of the high-humidity aging effects is discussed based on the change of surface state of the SnO2 particles.

  16. Thermal Conductivity of Humid Air

    Science.gov (United States)

    Beirão, S. G. S.; Ribeiro, A. P. C.; Lourenço, M. J. V.; Santos, F. J. V.; Nieto de Castro, C. A.

    2012-09-01

    In this article, measurements of the thermal conductivity of humid air as a function of pressure, temperature, and mole fraction of water, for pressures up to 5 MPa and temperatures up to 430 K, for different water contents (up to 10 % vapor mole fraction) are reported. Measurements were performed using a transient hot-wire apparatus capable of obtaining data with an uncertainty of 0.8 % for gases. However, as moist air becomes corrosive above 373 K and at pressures >5 MPa, the apparatus, namely, the pressure vessel and the cells had to be modified, by coating all stainless-steel parts with a titanium nitride thin film coating, about 4 μm thick, obtained by physical vapor deposition. The expanded uncertainty (coverage factor k = 2) of the present experimental thermal conductivity data is 1.7 %, while the uncertainty in the mole fraction is estimated to be better than 0.0006. Experimental details regarding the preparation of the samples, the precautions taken to avoid condensation in the tubes connected to the measuring cell, and the method developed for obtaining reliable values of the water content for the gas mixtures are discussed. A preliminary analysis of the application of the kinetic theory of transport properties in reacting mixtures to interpret the complex dependence of the thermal conductivity of humid air on water composition is addressed.

  17. Characteristics of the air temperature and humidity on the north slope of Mt Qomolangma%珠穆朗玛峰北坡地区气温和湿度变化特征

    Institute of Scientific and Technical Information of China (English)

    杨兴国; 秦大河; 张廷军; 康世昌; 秦翔

    2012-01-01

    珠穆朗玛峰地区由于其独特的自然地理条件、举世无双的高度、脆弱而敏感的环境使其成为气候变化和环境变迁的敏感区.根据2007年5月至2008年8月在珠穆朗玛峰北坡地区7个不同海拔高度观测的逐时气温和空气湿度资料分析了该地区气温和湿度的时空变化特征.结果表明,在海拔5207、5792和5955m高度处的年平均气温分别为0.2、-4.4和-5.4℃,最高气温分别为14.6、9.1和18,6℃,最低气温分别为-24.2、-28.8和- 29.3℃;除在冰川表面以外,空气相对湿度随海拔高度的升高没有明显变化.气温和相对湿度的年变化幅度随海拔高度的升高而减小.由于冰面近地层逆温层顶部暖空气与冷空气的混合作用造成其最高气温出现时间晚于其他下垫面.年平均温度递减率为(0.72±0.01)℃/100 m,并且呈现出明显的季节变化特征.同时结合定日气象站1959--2007年的气温和降水资料,探讨了对珠穆朗玛峰北坡绒布冰川变化的影响.%Weather and climatic conditions over the Himalaya regions are of great interest to the scientific community at large. The objective of this study is to present spatial and temporal variations of air temperatures and the relative humidity on the north slope of Mt Qomolangma. Both the hourly air temperature and relative humidity were measured at the seven automatic weather stations (AWS) from 5207 to 7028 m a. s. 1. from May 2007 through September 2008. The preliminary results show that the elevational variation of the mean annual air temperature is non-linear, which decreases from 0. 2℃ at elevations of 5207 m to - 4. 4℃ at 5792 m, and - 5. 4℃ at 5955 m. The maxima are 14. 6℃ , 9. 1℃ , and 18. 6℃ , and the minima are - 24. 2℃ , - 28. 8℃ , and - 29. 3℃ at the three elevations, respectively. The relative humidity does not change significantly with increasing elevation except over the glacier ice, but the mixing ratio decreases due to the

  18. Effect of different electrodes on the transport properties of ZnO nanofibers under humid environment

    Directory of Open Access Journals (Sweden)

    Z. Imran

    2015-11-01

    Full Text Available Relative humidity (RH sensing properties of zinc oxide nanofibers (ZNF, synthesized using electrospinning technique, were studied by impedance spectroscopy. RH sensors were fabricated with two different electrodes (Au and Ni using lithography on top of the nanofibers deposited on Si/SiO2 substrate. Compare with the Ni electrode sensor, Au electrode sensor exhibits larger sensitivity and quicker response/recovery. Capacitance, electrical conductivity and electrical modulus were studied at 40%-90% RH as a function of the frequency of the applied AC signal in the frequency range of 10−2-106 Hz. The corresponding response and recovery times are 3s and 5s for Au, and 6s and 10s for Ni electrode sensor, respectively. The sensors exhibited a reversible response with small hysteresis of less than 4% and 12% for Au and Ni electrodes respectively. Stability of the sensor device with Au electrode was confirmed by testing the device for 13 days. The excellent sensing characteristics and comparison of sensors with different electrode materials may offer an effective route for designing and optimizing RH sensors.

  19. Influence of particle size on H2 and H2S sensing characteristics of nanocrystalline zinc ferrite

    Science.gov (United States)

    Ghosh, P.; Das, M. R.; Mitra, P.

    2016-12-01

    Nanocrystalline zinc ferrite ZnFe2O4 was synthesized by sol-gel self-combustion technique. Ball milling at room temperature was carried out to control the particle size. Characterization of synthesized powders was made using X-ray diffraction and transmission electron microscopy analysis. Fine powders resulted from milling were used to prepare gas sensing elements in pellet form. The gas-sensing properties were studied in presence of hydrogen and hydrogen sulphide as test gases. The gas response behavior was found to be strongly influenced by the particle size. Significantly high sensitivity of 82 % was found for 7 nm zinc ferrite in presence of 200 ppm H2S at an operating temperature of 150 °C. Sensitivity was found to increase with temperature before being maximum at a particular operating temperature.

  20. One-pot synthesis of crystalline SnO2 nanoparticles and their low-temperature ethanol sensing characteristics

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Crystalline SnO2 nanoparticles(NPs) with a diameter less than 6 nm are synthesized using potassium stannate trihydrate as the precursor in a basic system.The synthesized NPs can detect ethanol at a ppm level even at 100℃.Furthermore,the NPs have good selectivity to ethanol.The excellent ethanol sensing performances are attributed to the small size effect according to the space-charge model.

  1. Characteristics of the nurse manager's recognition behavior and its relation to sense of coherence of staff nurses in Japan

    OpenAIRE

    Miyata, Chiharu; Arai, Hidenori; SUGA, Sawako

    2015-01-01

    The recognition behaviors strongly influence the job satisfaction of staff nurses and an extremely important factor for the prevention of burnout and the promotion of retention. Additionally, among internal factors that may affect worker's mental health, a sense of coherence (SOC) is an important concept from the view of the salutogenic theory and stress recognition style. Individual's SOC increases in relation to recognition behavior. However, in Japan, few studies have examined the effect o...

  2. Scaling behaviour in daily air humidity fluctuations

    CERN Document Server

    Vattay, G; Vattay, Gabor; Harnos, Andrea

    1994-01-01

    We show that the daily average air humidity fluctuations exhibit non-trivial $1/f^{\\alpha}$ behaviour which different from the spectral properties of other meteorological quantities. This feature and the fractal spatial strucure found in clouds make it plausible to regard air humidity fluctuations as a manifestation of self-organized criticality. We give arguments why the dynamics in air humidity can be similar to those in sandpile models of SOC.

  3. Sensing Characteristics of Flame-Spray-Made Pt/ZnO Thick Films as H2 Gas Sensor

    Directory of Open Access Journals (Sweden)

    Nittaya Tamaekong

    2009-08-01

    Full Text Available Hydrogen sensing of thick films of nanoparticles of pristine, 0.2, 1.0 and 2.0 atomic percentage of Pt concentration doped ZnO were investigated. ZnO nanoparticles doped with 0.2–2.0 at.% Pt were successfully produced in a single step by flame spray pyrolysis (FSP technique using zinc naphthenate and platinum(II acetylacetonate as precursors dissolved in xylene. The particle properties were analyzed by XRD, BET, SEM and TEM. Under the 5/5 (precursor/oxygen flame condition, ZnO nanoparticles and nanorods were observed. The crystallite sizes of ZnO spheroidal and hexagonal particles were found to be ranging from 5 to 20 nm while ZnO nanorods were seen to be 5–20 nm wide and 20–40 nm long. ZnO nanoparticles paste composed of ethyl cellulose and terpineol as binder and solvent respectively was coated on Al2O3 substrate interdigitated with gold electrodes to form thin films by spin coating technique. The thin film morphology was analyzed by SEM technique. The gas sensing properties toward hydrogen (H2 was found that the 0.2 at.% Pt/ZnO sensing film showed an optimum H2 sensitivity of ~164 at hydrogen concentration in air of 1 volume% at 300 °C and a low hydrogen detection limit of 50 ppm at 300 °C operating temperature.

  4. Passive Wireless SAW Humidity Sensors Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This proposal describes the preliminary development of passive wireless surface acoustic wave (SAW) based humidity sensors for NASA application to distributed...

  5. Morphology and gas sensing characteristics of density-controlled CuO nanostructures obtained by varying the oxygen partial pressure during growth

    Science.gov (United States)

    Lee, Dongjin; Jin, Changhyun; Noh, Youngwook; Park, Seokhyun; Choi, Sun-Woo

    2016-07-01

    By exerting different O2 partial pressures (0, 20, 40, and 60 sccm) onto copper substrates, we discovered that the growth parameter, namely, the O2 flow rate, affects the degree of nucleation, diameter, length, and crystalline quality of CuO nanowires (NWs). Scanning electron microscopy (SEM), X-ray diffraction (XRD), and transmission electron microscopy (TEM) were used to analyze the evolution of the morphological and the microstructural changes in the CuO nanostructures. The formation of a Cu2O interlayer between the Cu and the CuO layers could be adjusted by controlling more precisely the O2 flow rate. In addition, the reducing (H2S) and the oxidizing (O2, NO2, and SO2) gas sensing performances of these O2-assisted CuO NWs were compared with those of CuO NWs grown in static air. The response to the reducing H2S of the sensors based on CuO NWs grown using O2 at 40 sccm showed a higher electrical change and faster response and recovery times than the sensors based on CuO NWs grown using lower O2 flow rates, including the ones grown in static air and/or used for sensing oxidizing gases (O2, NO2, and SO2) did. On the basis of their growth and their gas-sensing applications, the possible mechanisms characteristic of the density-controlled CuO NWs grown using various O2 partial pressures are discussed.

  6. Characteristics of the Fiber Laser Sensor System Based on Etched-Bragg Grating Sensing Probe for Determination of the Low Nitrate Concentration in Water.

    Science.gov (United States)

    Pham, Thanh Binh; Bui, Huy; Le, Huu Thang; Pham, Van Hoi

    2016-12-22

    The necessity of environmental protection has stimulated the development of many kinds of methods allowing the determination of different pollutants in the natural environment, including methods for determining nitrate in source water. In this paper, the characteristics of an etched fiber Bragg grating (e-FBG) sensing probe-which integrated in fiber laser structure-are studied by numerical simulation and experiment. The proposed sensor is demonstrated for determination of the low nitrate concentration in a water environment. Experimental results show that this sensor could determine nitrate in water samples at a low concentration range of 0-80 ppm with good repeatability, rapid response, and average sensitivity of 3.5 × 10(-3) nm/ppm with the detection limit of 3 ppm. The e-FBG sensing probe integrated in fiber laser demonstrates many advantages, such as a high resolution for wavelength shift identification, high optical signal-to-noise ratio (OSNR of 40 dB), narrow bandwidth of 0.02 nm that enhanced accuracy and precision of wavelength peak measurement, and capability for optical remote sensing. The obtained results suggested that the proposed e-FBG sensor has a large potential for the determination of low nitrate concentrations in water in outdoor field work.

  7. Optical fiber waist-enlarged bitaper-based Michelson interferometric humidity sensor

    Science.gov (United States)

    Hu, Pengbing; Chen, Zhemin; Pan, Sunqiang; Li, Guoshui; Zhang, Jianfeng; Cheng, Jia

    2015-02-01

    An optical fiber waist-enlarged bitaper-based Michelson interferometric sensor is proposed and experimentally demonstrated for humidity measurement. The waist enlarged bitaper is created for light coupling between core mode and cladding modes propagating in the fiber interferometer. A chitason layer is plated onto the surface of the interferometer to act as a humidity-to-refractive index (RI) transducer and thus humidity measurement can be realized by monitoring the wavelength shifts of its interferogram induced by RI variations. The influence of the coating thickness and concentration of chitason on relative humidity (RH) measurement is experimentally studied. The coating sensor demonstrates an optimal humidity-sensing ability, with a humidity sensitivity and fast time-response of ~26 pm/%RH and ~5 s respectively, when it is 3-dip coated in chitason solutions of the concentration of 1 wt.%. The proposed humidity sensor is compact, cost-effective and of easy-operation, therefore it has potentials in many practical applications.

  8. Analysis of building envelope insulation performance utilizing integrated temperature and humidity sensors.

    Science.gov (United States)

    Hung, San-Shan; Chang, Chih-Yuan; Hsu, Cheng-Jui; Chen, Shih-Wei

    2012-01-01

    A major cause of high energy consumption for air conditioning in indoor spaces is the thermal storage characteristics of a building's envelope concrete material; therefore, the physiological signals (temperature and humidity) within concrete structures are an important reference for building energy management. The current approach to measuring temperature and humidity within concrete structures (i.e., thermocouples and fiber optics) is limited by problems of wiring requirements, discontinuous monitoring, and high costs. This study uses radio frequency integrated circuits (RFIC) combined with temperature and humidity sensors (T/H sensors) for the design of a smart temperature and humidity information material (STHIM) that automatically, regularly, and continuously converts temperature and humidity signals within concrete and transmits them by radio frequency (RF) to the Building Physiology Information System (BPIS). This provides a new approach to measurement that incorporates direct measurement, wireless communication, and real-time continuous monitoring to assist building designers and users in making energy management decisions and judgments.

  9. Fabrication of Cubic p-n Heterojunction-Like NiO/In2O3 Composite Microparticles and Their Enhanced Gas Sensing Characteristics

    Directory of Open Access Journals (Sweden)

    Hou Xuemei

    2016-01-01

    Full Text Available Oxide semiconductor In2O3 has been extensively used as a gas sensing material for the detection of various toxic gases. However, the pure In2O3 sensor is always suffering from its low sensitivity. In the present study, a dramatic enhancement of sensing characteristic of cubic In2O3 was achieved by deliberately fabricating p-n heterojunction-like NiO/In2O3 composite microparticles as sensor material. The NiO-decorated In2O3 p-n heterojunction-like sensors were prepared through the hydrothermal transformation method. The as-synthesized products were characterized using SEM-EDS, XRD, and FT-IR, and their gas sensing characteristics were investigated by detecting the gas response. The experimental results showed that the response of the NiO/In2O3 sensors to 600 ppm methanal was 85.5 at 260°C, revealing a dramatic enhancement over the pure In2O3 cubes (21.1 at 260°C. Further, a selective detection of methanol with inappreciable cross-response to other gases, like formaldehyde, benzene, methylbenzene, trichloromethane, ethanol, and ammonia, was achieved. The cause for the enhanced gas response was discussed in detailed. In view of the facile method of fabrication of such composite sensors and the superior gas response performance of samples, the cubic p-n heterojunction-like NiO/In2O3 sensors present to be a promising and viable strategy for the detection of indoor air pollution.

  10. Enhanced ethanol sensing characteristics of In2O3-decorated NiO hollow nanostructures via modulation of hole accumulation layers.

    Science.gov (United States)

    Kim, Hyo-Joong; Jeong, Hyun-Mook; Kim, Tae-Hyung; Chung, Jae-Ho; Kang, Yun Chan; Lee, Jong-Heun

    2014-10-22

    In this work, we report a dramatic enhancement in ethanol sensing characteristics of NiO hollow nanostructures via decoration with In2O3 nanoclusters. The pure NiO and 1.64-4.41 atom % In-doped NiO and In2O3-decorated NiO hollow spheres were prepared by ultrasonic spray pyrolysis, and their gas sensing characteristics were investigated. The response (the ratio between the resistance in gas and air) of the In2O3-decorated NiO hollow spheres to 5 ppm ethanol (C2H5OH) was 9.76 at 350 °C, which represents a significant improvement over the In-doped NiO and pure NiO hollow spheres (3.37 and 2.18, respectively). Furthermore, the 90% recovery time was drastically reduced from 1880 to 23 s, and a selective detection of ethanol with negligible cross-response to other gases was achieved. The enhanced gas response and fast recovery kinetics were explained in relation to the thinning of the near-surface hole accumulation layer of p-type NiO underneath n-type In2O3, the change of charge carrier concentration, and the variation of oxygen adsorption.

  11. Studies on electrical properties and CO-sensing characteristics of La0.9□0.1FeO3

    Institute of Scientific and Technical Information of China (English)

    MU Zonggang; ZHANG Ling; LI Xifeng; HU Jifan

    2011-01-01

    Semiconducting sensors offer an inexpensive and simple method for monitoring gases. Sensors based on the ABO3-type composite oxides materials have an advantage of high stability. The perovskite structures of these compounds are preserved, when an A-site deficiency of some perovskite structure compounds was formed. However, they exhibit particular physical properties. In this paper, La0.9□0.1FeO3 powder with an orthorhombic perovskite phase was prepared by sol-gel method. The electrical properties and CO-sensing characteristics of the La0.9□0.1FeO3 were also investigated. The results demonstrated that the La0.9□0.1FeO3 was a p-type semiconductor material. Compared with LaFeO3, the conductance of La0.9□0.1FeO3 was better than that of LaFeO3. The sensor based on La0.9□0. 1FeO3 showed excellent CO gas-sensing characteristics.

  12. Analysis and Mapping of the Spectral Characteristics of Fractional Green Cover in Saline Wetlands (NE Spain Using Field and Remote Sensing Data

    Directory of Open Access Journals (Sweden)

    Manuela Domínguez-Beisiegel

    2016-07-01

    Full Text Available Inland saline wetlands are complex systems undergoing continuous changes in moisture and salinity and are especially vulnerable to human pressures. Remote sensing is helpful to identify vegetation change in semi-arid wetlands and to assess wetland degradation. Remote sensing-based monitoring requires identification of the spectral characteristics of soils and vegetation and their correspondence with the vegetation cover and soil conditions. We studied the spectral characteristics of soils and vegetation of saline wetlands in Monegros, NE Spain, through field and satellite images. Radiometric and complementary field measurements in two field surveys in 2007 and 2008 were collected in selected sites deemed as representative of different soil moisture, soil color, type of vegetation, and density. Despite the high local variability, we identified good relationships between field spectral data and Quickbird images. A methodology was established for mapping the fraction of vegetation cover in Monegros and other semi-arid areas. Estimating vegetation cover in arid wetlands is conditioned by the soil background and by the occurrence of dry and senescent vegetation accompanying the green component of perennial salt-tolerant plants. Normalized Difference Vegetation Index (NDVI was appropriate to map the distribution of the vegetation cover if the green and yellow-green parts of the plants are considered.

  13. Experimental research on the indoor temperature and humidity fields in radiant ceiling air-conditioning system under natural ventilation

    Science.gov (United States)

    Huang, Tao; Xiang, Yutong; Wang, Yonghong

    2017-05-01

    In this paper, the indoor temperature and humidity fields of the air in a metal ceiling radiant panel air conditioning system with fresh air under natural ventilation were researched. The temperature and humidity distributions at different height and different position were compared. Through the computation analysis of partial pressure of water vapor, the self-recovery characteristics of humidity after the natural ventilation was discussed.

  14. Chelating-Template-Assisted in Situ Encapsulation of Zinc Ferrite Inside Silica Mesopores for Enhanced Gas-Sensing Characteristics.

    Science.gov (United States)

    Niu, Kui; Liang, Liman; Peng, Fei; Zhang, Fan; Gu, Yao; Tian, Hongyan

    2016-09-21

    A facile in situ approach has been designed to synthesize zinc ferrite/mesoporous silica guest-host composites. Chelating surfactant, N-hexadecyl ethylenediamine triacetic acid, was employed as structure-directing agent to fabricate mesoporous silica skeleton and simultaneously as complexing agent to incorporate stoichiometric amounts of zinc and iron ions into silica cavities. On this basis, spinel zinc ferrite nanoparticles with grain sizes less than 3 nm were encapsulated in mesoporous channels after calcination. The silica mesostructure, meanwhile, displayed a successive transformation from hexagonal p6mm through bicontinuous cubic Ia3̅d to lamellar phase with increasing the dopant concentration in the initial template solution. In comparison with zinc ferrite nanopowder prepared without silica host, the composite with bicontinuous architecture exhibited higher sensitivity, lower detection limit, lower optimum working temperature, quicker response, and shorter recovery time in sensing performance toward hydrogen sulfide. The significant improvements are from the high surface-to-volume ratio of the guest oxides and the three-dimensional porous structure of the composite. We believe the encapsulation route presented here may pave the way for directly introducing complex metal oxide into mesoporous silica matrix with tailorable mesophases for applications in sensing or other fields.

  15. Theoretical Investigation by Quantum Mechanics on the Tunnel Diode Effect of Electric Conductive Characteristics and Haptic Sensing in MCF Rubber

    Directory of Open Access Journals (Sweden)

    Kunio Shimada

    2010-01-01

    Full Text Available By applying our developed intelligent fluid, magnetic compound fluid (MCF, to silicon oil rubber, we have made the MCF rubber highly sensitive to temperature and electric conduction. MCF is useful as the element material in haptic robot sensors and other related devices. In the present paper, we clarified the relationship between the electric current and the voltage under a tensile strain by utilizing the quantum mechanics theory on the multibarrier potential problem. The experimental results could be qualitatively explained by our proposed theory. The electrons can be moved between the solid materials by the tunnel effect. The relation between voltage and electric current is affected by the formation of the clusters, and it is changed by the application of heat. We also clarified experimentally the present MCF rubber useful in haptic sensors. Because the motions of humans and robots are different, the sensing of the rubber is different, depending on the placement. However, as for both motions of human and robot, there is no quantitative difference in the electric resistance among kinetic energy, momentum, and force. The sensing is also different based on the stiffness of the surface to which the sensor is adhered.

  16. 环境温湿度对聚酰亚胺介电强度的影响机制%Influences of Elevated Temperature and Humidity on Breakdown Characteristics of Polyimide Film

    Institute of Scientific and Technical Information of China (English)

    罗杨; 吴广宁; 刘继午; 彭佳; 高国强; 孙继星; 朱光亚

    2014-01-01

    Polyimide (PI) film has been widely applied as electrical insulation for wires and cables due to its excellent electrical, mechanical and thermal properties. However, PI insulation could be degraded because of various environmental stresses, which can cause deterioration of their insulation properties. In this paper, the effects of thermal exposure on dielectric strength of nanocomposite PI film and pure PI film were investigated. The comparison of the breakdown field strength of single layer film, double layer films and three layer films were also studied. The influence mechanism of humidity on the breakdown strength was analyzed. The results show that the breakdown field strength of PI films, both nanocomposite PI film and pure PI film, is greatly decreased with the tested temperature increasing. And the decreasing rate of breakdown field strength increases more obviously when the tested temperature is more than 350℃. It is due to the motion and pyrolysis degradation of PI macromolecules caused by overheating. The single film possesses better heat dissipation potential and homogeneous micro-structure. Therefore the breakdown field strength of single layer film is higher than those of double layer films and three layer films. Higher thermal conductivity of nanocomposite PI film has the better breakdown stability in high temperature environment. Some hydrogen bonds exist between water molecule and carboxyl in the backbone chain of PI polymer. The hydrolysis reaction of PI macromolecule would make the dielectric strength of PI film decrease.%聚酰亚胺薄膜因其优良的电气、机械及热性能已在各种绝缘线缆中得到广泛应用。然而,环境应力可能会造成聚酰亚胺降解,从而降低其绝缘性能。以聚酰亚胺普通薄膜和聚酰亚胺纳米薄膜为测试对象,研究了单层膜、双层膜及三层膜在不同温度下的击穿特性,分析了水分对聚酰亚胺薄膜击穿场强的影响机制。结果表明:普

  17. Nanostructure characteristics of ferroics and bio-ferroics in relation to the design consideration of nano-sensing elements

    Science.gov (United States)

    Pal, Madhuparna

    The shift of the epicenter in the field of science and technology to the nano-world has become evident over the past couple of decades with the emergence of areas likes nanoscience, nanotechnology, nano-biotechnology, etc. Though the size of the devices has decreased, the capability of devices has increased rendering it as 'multifunctional/smart' devices. However the design of smart devices using a single phase material has reached to its limit, hence to make further progress "smart materials" are required. Sensors/actuators are mostly fabricated with popular ferroic materials (ferroelectric/ ferromagnetic/ ferroelastic) or multiferroics (having more than one ferroic property). Multifunctionality can be the outcome of heterogeneous systems with cross-coupled properties, intrinsic as well as extrinsic, and hence modeling of smart materials with high figure of merit is also needed. Most ideas in smart sensing and actuation have been borrowed from the biological systems thus a step further is indeed to combine the engineering with the fundamental biological activities. Not only can we use multiferroic materials in artificial transplants, but we should also investigate ferroic activities in the biological samples. These fundamental issues, their possible solutions and their wide impact underlie the motivation of the current work in this thesis report. To achieve the ultimate goal, the steps outlined were followed: i. understanding the properties of sensing elements of inorganic and biomaterials at nanoscale level, ii. investigation of the multiferroicity, iii. modeling engineered material with better sensing capabilities iv. Finally exploiting the new concepts for device and biomedical applications. The findings of this thesis reports multiferroic behavior in a selected class of single crystals, thin films and bulk materials. Human nails and hair samples have been investigated for ferroelectricity and a comprehensive study concludes the presence of bio

  18. Ethanol and LPG sensing characteristics of SnO2 activated Cr2O3 thick film sensor

    Indian Academy of Sciences (India)

    Ravi Chand Singh; Nipin Kohli; Manmeet Pal Singh; Onkar Singh

    2010-10-01

    The sensing response of pure and SnO2 activated Cr2O3 to ethanol vapours and liquefied petroleum gas (LPG) has been investigated. Fine particles of commercial chromium oxide powder were selected and deposited as thick film to act as a gas sensor. The sensor surface has been activated by tin dioxide, on surface oxidation of tin chloride. The concentration of tin chloride solution, used as activator, was varied from 0 to 5% and its effect on gas response, selectivity and operating temperature has been studied. It was found that response to ethanol vapours significantly improved, whereas response to LPG remained unaffected. Moreover, operating temperature remains unchanged both for LPG and ethanol vapours.

  19. On the Temperature and Humidity Dissimilarity in the Marine Surface Layer

    DEFF Research Database (Denmark)

    Larsén, Xiaoli Guo; Kelly, Mark C.; Sempreviva, Anna Maria

    2014-01-01

    The dissimilarity of temperature and humidity transfer in the marine surface layer (MSL) is investigated through the relative transport efficiency and correlation coefficient of these two scalars. We examine their variability and relationship with mean values, as well as spectral characteristics...... there is an efficient latent heat transfer but negligible sensible heat transfer. Our data suggest that parametrization of humidity fluxes via similarity theory could still be reliable when the correlation coefficient >0.5, and in near-neutral conditions the humidity flux can be estimated without use of the sensible...

  20. Comparison among the mineralogic characteristics of Corumbatai formation and a mass for via humidity ceramic coating; Comparacao das caracteristicas mineralogicas da formacao Corumbatai com uma massa para revestimentos ceramicos via umida

    Energy Technology Data Exchange (ETDEWEB)

    Rocha, R.R.; Zanardo, A.; Moreno, M.M.T., E-mail: azanardo@rc.unesp.b [Universidade Estadual Paulista Julio de Mesquita Filho (UNESP), SP (Brazil). Dept. de Petrologia e Metalogenia; Souza, E.M. [Colorminas Colorificio e Mineracao S.A., Icara, SC (Brazil)

    2009-07-01

    The mineralogy of the raw materials used in the production of ceramic tiles is a matter of great importance considering the constant necessity of finding alternatives to reduce costs and to improve the product quality. The ceramic industry of Santa Gertrudes could see a dramatic growth due to reasons that include the natural characteristics of the raw materials found in the region which are suitable for the production of ceramic tiles through the dry grinding process. In order to understand the ease of use of such clays which are sedimentary rocks of Corumbatai Formation, their plastic components made up primarily of clay minerals such as illite and smectite, and non-plastic components, including quartz (inert), feldspars (fluxe) and some contaminants, were identified with the use of X-ray diffraction. When comparing the properties of the formulation made with clays from Corumbatai Formation with that made with raw materials for the wet process, it was possible to note the ease of use and the relative characteristics of both processes. (author)

  1. Human-Finger Electronics Based on Opposing Humidity-Resistance Responses in Carbon Nanofilms.

    Science.gov (United States)

    Tai, Yanlong; Lubineau, Gilles

    2017-03-01

    Carbon nanomaterials have excellent humidity sensing properties. Here, it is demonstrated that multiwalled carbon-nanotube (MWCNT)- and reduced-graphene-oxide (rGO)-based conductive films have opposite humidity/electrical resistance responses: MWCNTs increase their electrical resistance (positive response) and rGOs decrease their electrical resistance (negative response). The authors propose a new phenomenology that describes a "net"-like model for MWCNT films and a "scale"-like model for rGO films to explain these behaviors based on contributions from junction resistances (at interparticle junctions) and intrinsic resistances (of the particles). This phenomenology is accordingly validated via a series of experiments, which complement more classical models based on proton conductivity. To explore the practical applications of the converse humidity/resistance responses, a humidity-insensitive MWCNT/rGO hybrid conductive films is developed, which has the potential to greatly improve the stability of carbon-based electrical device to humidity. The authors further investigate the application of such films to human-finger electronics by fabricating transparent flexible devices consisting of a polyethylene terephthalate substrate equipped with an MWCNT/rGO pattern for gesture recognition, and MWCNT/rGO/MWCNT or rGO/MWCNT/rGO patterns for 3D noncontact sensing, which will be complementary to existing 3D touch technology.

  2. Combining the Converse Humidity/Resistance Response Behaviors of RGO Films for Flexible Logic Devices

    KAUST Repository

    Tai, Yanlong

    2017-03-23

    Carbon nanomaterials have excellent humidity sensing performance. Here, we demonstrate that reduced-graphene-oxide- (rGO) based conductive films with different thermal reduction times have gradient and invertible humidity/electrical resistance responses: rGO films (< 11 h, negative response, regarded as a signal of “0”), rGO films (around 11-13 h, balance point) and rGO films (> 13 h, negative response, regarded as a signal of “1”). We propose a new mechanism that describes a “scale”-like model for rGO films to explain these behaviors based on contributions from Ohm-contact resistance and capacitive reactance at interplate junctions, and intrinsic resistances of the nanoplates, respectively. This mechanism is accordingly validated via a series of experiments and electrical impedance spectroscopies, which complement more classical models based on proton conductivity. To explore the practical applications of the converse humidity/resistance responses, three simple flexible logic devices were developed, i) a rGO pattern for humidity-insensitive conductive film, which has the potential to greatly improve the stability of carbon-based electrical device to humidity; ii) a Janus pattern of rGO films for gesture recognition, which is very useful to human/machine interactions; iii) a sandwich pattern of rGO films for 3-dimensional (3D) noncontact sensing, which will be complementary to existing 3D touch technique.

  3. Doping effect of In{sub 2}O{sub 3} on structural and ethanol-sensing characteristics of ZnO nanotubes fabricated by electrospinning

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Baoyu; Zhao, Changhui; Zhang, Mingxiang; Zhang, Zemin; Xie, Erqing, E-mail: xieeq@lzu.edu.cn; Zhou, Jinyuan, E-mail: zhoujy@lzu.edu.cn; Han, Weihua

    2015-09-15

    Highlights: • IZO nanotubes with various indium contents were synthesized by electrospinning. • A well-crystallized indium-zinc-oxide solid solution formed in IZO-0.01 nanotubes. • Amorphous In{sub 2}O{sub 3} segregated at ZnO grain boundaries at high indium doping levels. • IZO-0.01 nanotubes show a high response and good selectivity to ethanol at 275 °C. - Abstract: Indium-doped ZnO (IZO) nanotubes with various indium contents (0.01–0.20) were synthesized via a facile electrospinning method. Results of X-ray diffraction and transmission electron microscopy demonstrate that all samples are consisted of hexagonal wurtzite-typed ZnO, showing a well-crystallized indium-zinc-oxide solid solution when only a small amount of zinc ions substituted by indium ions (0.01). Once the amount of indium dopants ≥0.05, there will form some amorphous In{sub 2}O{sub 3}, leading to a pronounced decrease in grain sizes. Gas-sensing performances revealed that the IZO nanotube-based sensors have enhanced ethanol-sensing characteristics, especially, sensor based on IZO-0.01 nanotubes shows the highest response (R{sub a}/R{sub g} = 81.7), which is twice that of the undoped ZnO nanotubes (40.0) toward 100 ppm ethanol at an operating temperature of 275 °C. And IZO-0.20 nanotube-based sensor presents a relatively high response at high ethanol concentrations. Our research suggested that these remarkable enhanced ethanol-sensing properties can be closely related to the formation of indium-zinc-oxide solid solutions and/or heterostructures between ZnO and amorphous In{sub 2}O{sub 3}.

  4. Assessment of soil surface roughness characteristics at field-scale for soil erosion studies using microwave remote sensing data

    Science.gov (United States)

    Marzahn, Philip; Ludwig, Ralf

    2013-04-01

    Soil surface roughness (SSR) is a crucial parameter in the assessment and modelling of soil erosion in agricultural landscapes. Still, in recent modelling efforts, roughness is usually treated as a static parameter, leading to strong simplification and data uncertainty in the description of these physical processes and the derivation of hydrological quantities. However, this simplification is not only due to the lack of theoretical process knowledge, but rather refers to the lack of appropriate roughness input data, as it is very complex to measure roughness under natural conditions. To overcome the current limitations, the performance of microwave remote sensing acquisitions is investigated to derive SSR dynamics for a whole vegetation period over several agricultural fields. As the backscattered signal of an incident microwave shows an inherent dependency from the geometric properties, e.g. the roughness conditions, of an illuminated scene, microwave remote sensing imagery shows a good potential to derive SSR for soil erosion studies sufficiently. The proposed approach utilizes airborne PolSAR data, acquired at C- and L-Band (e.g. 5.6 GHz and 1.3 GHz) for the derivation of four potential roughness estimators. In addition an extensive ground truth database of photogrammetrically measured roughness samples is used to validate the results. To characterize the in-field measurements the RMS-height s - which is the standard deviation of the heights to a reference height - was chosen. Using the best fit approach, a highly accurate assessment of SSR at field-scale could be achieved by deriving s using a linear model from the real part of the circular coherence (Re[ρRRLL]). In this presentation, we show the database of the proposed approach acquired in the framework of the AgriSAR 2006 campaign funded by the European Space Agency, ESA, as well as methods and results of the proposed approach. In addition we will discuss the results in context of soil erosion research and

  5. Humidity Effects on Conductivity of DNA Molecules

    Institute of Scientific and Technical Information of China (English)

    YAN Xun-Ling; DONG Rui-Xin; LIN Qing-De

    2006-01-01

    We present a model related to the humidity to describe the conductivity of homogeneous DNA molecule,where the hydration of phosphate group and bases are taken into account. The calculated results show the oscillation feature of dⅠ/dⅤ-Ⅴ curves and the semiconductor behavior of DNA. With the relative humidity increasing, the voltage gap becomes narrow and the maximum of conductance increases nonlinearly. The conductivity of DNA approaches to stabilization when the relative humidity reaches a certain value. These results are in agreement with experimental measurements.

  6. Tropical Atmospheric Circulations with Humidity Effects

    CERN Document Server

    Hsia, Chun-Hsiung; Ma, Tian; Wang, Shouhong

    2011-01-01

    The main objective of this article is to study the effect of the moisture on the planetary scale atmospheric circulation over the tropics. The modeling we adopt is the Boussinesq equations coupled with a diffusive equation of humidity and the humidity dependent heat source is modeled by a linear approximation of the humidity. The rigorous mathematical analysis is carried out using the dynamic transition theory. In particular, we obtain the same types of transitions and hence the scenario of the El Ni\\~no mechanism as described in \\cite{MW2,MW3}. The effect of the moisture only lowers slightly the magnitude of the critical thermal Rayleigh number.

  7. A Triple-Probe Channel NO{sub 2}S{sub 2}-Macrocycle: Synthesis, Sensing Characteristics and Crystal Structure of Mercury(II) Nitrate Complex

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Ji Eun; Seo, Moo Lyong; Lee, Shim Sung [Gyeongsang National University, Jinju (Korea, Republic of); Choi, Kyu Seong [Kyungnam University, Masan (Korea, Republic of)

    2010-07-15

    A triple-probe channel type chemosensor based on an NO{sub 2}S{sub 2}-macrocycle functionalized with phenyltricyanovinyl group was synthesized and its sensing characteristics were examined. The pink-red solution of L changed selectively to pale yellow upon addition of Hg{sup 2+}. The selective fluorometric response of L to all the tested metal ions was studied. The results showed that a large enhancement of the fluorescence of L was observed only in the case of Hg{sup 2+}. In addition, L showed large anodic shift ({approx} 0.3 V) for the addition of excess Hg{sup 2+}. Through above three observed results by the different techniques, we confirmed that the proposed chemosensor acts as the multiple-probe channel sensing material. The crystal structure of mercury(II) nitrate complexes of L which shows a 1-D polymer network with a formula [Hg{sub 2}(L){sub 2}(NO{sub 3}){sub 2}({mu}-NO{sub 3}){sub 2}]{sub n} was also reported.

  8. Trace element geochemical characteristics of plants and their influence on the remote-sensing spectral properties in the North Jiangsu oil field

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    This paper presents the contents of 17 kinds of trace elements in plant leaf samples collected from 4 sections in the North Jiangsu oil field, and the dada on their visible-near infrared spectra. By comparing the results of the inner and outer oil-gas remote-sensing anomaly areas, the plant trace element composition, and the enrichment characteristics and their influence on the plant spectral properties are described. The results indicated that the plant leaves had very strong enrichment ability toward some elements such as Mg, Ca, K, Na, Fe, Al, Mn, V, Zn and Cr. The plant leaves from the oil-gas abnormal areas were enriched in trace elements of the Fe-series, but depleted in alkali and alkali-earth metal elements. The plant trace elements had a strong influence on the "blue-shift' strength and the reflectance of visible bands. And the ratios between Fe, Co and K, Na, Cd, Cu, Ba are the effective remote-sensing oil-indicating factors of plant trace elements.

  9. Highly sensitive and ultrafast response surface acoustic wave humidity sensor based on electrospun polyaniline/poly(vinyl butyral) nanofibers.

    Science.gov (United States)

    Lin, Qianqian; Li, Yang; Yang, Mujie

    2012-10-20

    Polyaniline (PANi) composite nanofibers were deposited on surface acoustic wave (SAW) resonator with a central frequency of 433 MHz to construct humidity sensors. Electrospun nanofibers of poly(methyl methacrylate), poly(vinyl pyrrolidone), poly(ethylene oxide), poly(vinylidene fluoride), poly(vinyl butyral) (PVB) were characterized by scanning electron microscopy, and humidity response of corresponding SAW humidity sensors were investigated. The results indicated that PVB was suitable as a matrix to form nanofibers with PANi by electrospinning (ES). Electrospun PANi/PVB nanofibers exhibited a core-sheath structure as revealed by transmittance electron microscopy. Effects of ES collection time on humidity response of SAW sensor based on PANi/PVB nanofibers were examined at room temperature. The composite nanofiber sensor exhibited very high sensitivity of ~75kHz/%RH from 20 to 90%RH, ultrafast response (1s and 2s for humidification and desiccation, respectively) and good sensing linearity. Furthermore, the sensor could detect humidity as low as 0.5%RH, suggesting its potentials for low humidity detection. Attempts were done to explain the attractive humidity sensing performance of the sensor by considering conductivity, hydrophilicity, viscoelasticity and morphology of the polymer composite nanofibers. Copyright © 2012 Elsevier B.V. All rights reserved.

  10. Central Asian Snow Cover Characteristics between 1986 and 2012 derived from Time Series of Medium Resolution Remote Sensing Data

    OpenAIRE

    2014-01-01

    The eminent importance of snow cover for climatic, hydrologic, anthropogenic, and economic reasons has been widely discussed in scientific literature. Up to 50% of the Northern Hemisphere is covered by snow at least temporarily, turning snow to the most prevalent land cover types at all. Depending on regular precipitation and temperatures below freezing point it is obvious that a changing climate effects snow cover characteristics fundamentally. Such changes can have severe impacts on local, ...

  11. Enhancement of Gas Sensing Characteristics of Multiwalled Carbon Nanotubes by CF4 Plasma Treatment for SF6 Decomposition Component Detection

    Directory of Open Access Journals (Sweden)

    Xiaoxing Zhang

    2015-01-01

    Full Text Available H2S and SO2 are important gas components of decomposed SF6 of partial discharge generated by insulation defects in gas-insulated switchgear (GIS. Therefore, H2S and SO2 detection is important in the state evaluation and fault diagnosis of GIS. In this study, dielectric barrier discharge was used to generate CF4 plasma and modify multiwalled carbon nanotubes (MWNTs. The nanotubes were plasma-treated at optimum discharge conditions under different treatment times (0.5, 1, 2, 5, 8, 10, and 12 min. Pristine and treated MWNTs were used as gas sensors to detect H2S and SO2. The effects of treatment time on gas sensitivity were analyzed. Results showed that the sensitivity, response, and recovery time of modified MWNTs to H2S were improved, but the recovery time of SO2 was almost unchanged. At 10 min treatment time, the MWNTs showed good stability and reproducibility with better gas sensing properties compared with the other nanotubes.

  12. Geomorphic and lithologic characteristics of Wadi Feiran basin, southern Sinai, Egypt, using remote sensing and field investigations

    Indian Academy of Sciences (India)

    Ayman A Ahmed; Mohamed Abdelkareem; Asran M Asran; Tawfig M Mahran

    2017-08-01

    Wadi Feiran is an important drainage basin in southern Sinai Peninsula covering an area of about 1785 km2, its streams drain into the Gulf of Suez crossing variety of rocks and sedimentary units varied in age from Precambrian to Quaternary. Field investigations, geographic information systems (GIS) and remote sensing studies including Landsat-7 ETM+, Radarsat-1, and SRTM DEM were integrated to reveal its lithologic, geologic and geomorphic features. Besides the field investigations, rock units including basement and pre- and syn-rift sedimentary units were discriminated using band ratios and principal component analysis techniques (PCA). Such techniques revealed that the crystalline rocks covering W. Feiran are unaltered rocks lacking OH-bearing minerals. Radar data successfully displayed the structures and geomorphic features related to topography. Moreover, the techniques allowed the extraction of the dyke-like structures along faults and shear zones. This also characterized the topographic variations through analysis of the shaded terrain and the altitudinal profiles. The results of data integration, lineament analysis and lineament density maps revealed that the structural grain in the present study has four different trends: N20–45E, N30–45W, N–S and E–W. Based on analysis of radar data and geomorphic indices, W. Feiran is an asymmetrical basin, its left side occupies ∼34% of the total area that leads to a supposedly massive tilt towards the south which caused the southwestward slope.

  13. Characteristics of the nurse manager's recognition behavior and its relation to sense of coherence of staff nurses in Japan.

    Science.gov (United States)

    Miyata, Chiharu; Arai, Hidenori; Suga, Sawako

    2015-01-01

    The recognition behaviors strongly influence the job satisfaction of staff nurses and an extremely important factor for the prevention of burnout and the promotion of retention. Additionally, among internal factors that may affect worker's mental health, a sense of coherence (SOC) is an important concept from the view of the salutogenic theory and stress recognition style. Individual's SOC increases in relation to recognition behavior. However, in Japan, few studies have examined the effect of recognition behaviors on the SOC of staff nurses. The purpose of this study was to investigate how staff nurses perceive recognition behaviors of the nurse manager and to determine the relationship between recognition behaviors and the staff nurses' SOC. This quantitative, cross-sectional study involved 10 hospitals in Japan. A total of 1425 nurses completed the questionnaire. As a result, the perceptions of nurse manager's recognition behaviors by staff nurses were evaluated by presentation and report, individual value and the transfer of responsibility, and professional development. The median score of staff nurse SOC-13 was 50 (IQR; 45-55). Significant differences in SOC scores were found in marital status, age, years of experience, and mental and physical health condition. In conclusion, recognition behaviors by the nurse manager can improve staff nurse's SOC and effectively support the mental health of the staff nurse.

  14. [Pharmacological characteristics of drugs targeted on calcium-sensing receptor.-properties of cinacalcet hydrochloride as allosteric modulator].

    Science.gov (United States)

    Nagano, Nobuo; Tsutsui, Takaaki

    2016-06-01

    Calcimimetics act as positive allosteric modulators of the calcium-sensing receptor (CaSR), thereby decreasing parathyroid hormone (PTH) secretion from the parathyroid glands. On the other hand, negative allosteric modulators of the CaSR with stimulatory effect on PTH secretion are termed calcilytics. The calcimimetic cinacalcet hydrochloride (cinacalcet) is the world's first allosteric modulator of G protein-coupled receptor to enter the clinical market. Cinacalcet just tunes the physiological effects of Ca(2+), an endogenous ligand, therefore, shows high selectivity and low side effects. Calcimimetics also increase cell surface CaSR expression by acting as pharmacological chaperones (pharmacoperones). It is considered that the cinacalcet-induced upper gastrointestinal problems are resulted from enhanced physiological responses to Ca(2+) and amino acids via increased sensitivity of digestive tract CaSR by cinacalcet. While clinical developments of calcilytics for osteoporosis were unfortunately halted or terminated due to paucity of efficacy, it is expected that calcilytics may be useful for the treatment of patients with activating CaSR mutations, asthma, and idiopathic pulmonary artery hypertension.

  15. Improved sensing characteristics of methane over ZnO nano sheets upon implanting defects and foreign atoms substitution

    Science.gov (United States)

    Hussain, Tanveer; Kaewmaraya, Thanayut; Khan, Mehwish; Chakraborty, Sudip; Shafiq Islam, Muhammad; Amornkitbamrung, Vittaya; Ahuja, Rajeev

    2017-10-01

    Thanks to the growing interests of metal oxide sensors in environmental and industrial uses, this study presents the sensing mechanism of methane gas (CH4) on recently synthesized two-dimensional form of ZnO, ZnO nano sheets (ZnO-NS). The adsorption energy of CH4 on pristine ZnO-NS, calculated by means of van der Waals corrected first-principles calculations, is found to be insufficient restricting its application as an efficient nano sensor. However, the creation of (O/Zn) vacancies and the substitution of foreign dopants into ZnO-NS considerably intensify the binding energy of CH4. Through a comprehensive energetic analysis, it is observed that among all the substituents, boron (B), sulphur (S) and gallium (Ga) improves the binding of CH4 to 2.75, 6.1 and 7.5 times respectively than its values on pristine ZnO-NS. In addition to the CH4 binding energies falling ideally between physisorption and chemisorption range, a prominent variation in the electronic properties before and after CH4 exposure indicates the promise of substituted Zn-NS as a useful nano sensors.

  16. Geomorphic and lithologic characteristics of Wadi Feiran basin, southern Sinai, Egypt, using remote sensing and field investigations

    Science.gov (United States)

    Ahmed, Ayman A.; Abdelkareem, Mohamed; Asran, Asran M.; Mahran, Tawfig M.

    2017-08-01

    Wadi Feiran is an important drainage basin in southern Sinai Peninsula covering an area of about 1785 km2, its streams drain into the Gulf of Suez crossing variety of rocks and sedimentary units varied in age from Precambrian to Quaternary. Field investigations, geographic information systems (GIS) and remote sensing studies including Landsat-7 ETM+, Radarsat-1, and SRTM DEM were integrated to reveal its lithologic, geologic and geomorphic features. Besides the field investigations, rock units including basement and pre- and syn-rift sedimentary units were discriminated using band ratios and principal component analysis techniques (PCA). Such techniques revealed that the crystalline rocks covering W. Feiran are unaltered rocks lacking OH-bearing minerals. Radar data successfully displayed the structures and geomorphic features related to topography. Moreover, the techniques allowed the extraction of the dyke-like structures along faults and shear zones. This also characterized the topographic variations through analysis of the shaded terrain and the altitudinal profiles. The results of data integration, lineament analysis and lineament density maps revealed that the structural grain in the present study has four different trends: N20-45E, N30-45W, N-S and E-W. Based on analysis of radar data and geomorphic indices, W. Feiran is an asymmetrical basin, its left side occupies ˜ 34% of the total area that leads to a supposedly massive tilt towards the south which caused the southwestward slope.

  17. Temporal dynamics of sand dune bidirectional reflectance characteristics for absolute radiometric calibration of optical remote sensing data

    Science.gov (United States)

    Coburn, Craig A.; Logie, Gordon; Beaver, Jason

    2016-09-01

    The use of Pseudo Invariant Calibration Sites (PICS) for establishing the radiometric trending of optical remote sensing systems has a long history of successful implementation. Past studies have shown that the PICS method is useful for evaluating the trend of sensors over time or cross-calibration of sensors but was not considered until recently for deriving absolute calibration. Current interest in using this approach to establish absolute radiometric calibration stems from recent research that indicates that with empirically derived models of the surface properties and careful atmospheric characterisation Top of Atmosphere (TOA) reflectance values can be predicted and used for absolute sensor radiometric calibration. Critical to the continued development of this approach is the accurate characterization of the Bidirectional Reflectance Distribution Function (BRDF) of PICS sites. This paper presents BRDF data collected by a high-performance portable goniometer system in order to develop a temporal BRDF model for the Algodones Dunes in California. The results demonstrated that the BRDF of a reasonably simple sand surface was complex with changes in anisotropy taking place in response to changing solar zenith angles. The nature of these complex interactions would present challenges to future model development.

  18. Research on high-temperature sensing characteristics based on modular interference of single-mode multimode single-mode fiber

    Science.gov (United States)

    Peng, Zhaozhuang; Wang, Li; Yan, Huanhuan

    2016-11-01

    Application of high temperature fiber sensing system is very extensive. It can be mainly used in high temperature test aerospace, such as, materials, chemicals, and energy. In recent years, various on-line optical fiber interferometric sensors based on modular interference of single-mode-multimode-single-mode(SMS) fiber have been largely explored in high temperature fiber sensor. In this paper we use the special fiber of a polyimide coating, its sensor head is composed of a section of multimode fiber spliced in the middle of Single-mode fiber. When the light is launched into the multimode fiber(MMF) through the lead-in single-mode fiber(SMF), the core mode and cladding modes are excited and propagate in the MMF respectively. Then, at the MMF-SMF spliced point, the excited cladding modes coupled back into the core of lead-out SMF interfere with SMF core mode. And the wavelength of the interference dip would shift differently with the variation of the temperature. By this mean, we can achieve the measurement of temperature. The experimental results also show that the fiber sensor based on SMS structure has a highly temperature sensitivity. From 30° to 300°, with the temperature increasing, the interference dip slightly shifts toward longer wavelength and the temperature sensitivity coefficient is 0.0115nm/°. With high sensitivity, simple structure, immunity to electromagnetic interferences and a good linearity of the experimental results, the structure has an excellent application prospect in engineering field.

  19. Temperature and Humidity Control in Livestock Stables

    DEFF Research Database (Denmark)

    Hansen, Michael; Andersen, Palle; Nielsen, Kirsten M.;

    2010-01-01

    The paper describes temperature and humidity control of a livestock stable. It is important to have a correct air flow pattern in the livestock stable in order to achieve proper temperature and humidity control as well as to avoid draught. In the investigated livestock stable the air flow...... is controlled using wall mounted ventilation flaps. In the paper an algorithm for air flow control is presented meeting the needs for temperature and humidity while taking the air flow pattern in consideration. To obtain simple and realisable controllers a model based control design method is applied....... In the design dynamic models for temperature and humidity are very important elements and effort is put into deriving and testing the models. It turns out that non-linearities are dominating in both models making feedback linearization the natural design method. The air controller as well as the temperature...

  20. Characteristics of the Remote Sensing Data Used in the Proposed Unfccc REDD+ Forest Reference Emission Levels (frels)

    Science.gov (United States)

    Johnson, B. A.; Scheyvens, H.; Samejima, H.; Onoda, M.

    2016-06-01

    Developing countries must submit forest reference emission levels (FRELs) to the UNFCCC to receive incentives for REDD+ activities (e.g. reducing emissions from deforestation/forest degradation, sustainable management of forests, forest carbon stock conservation/enhancement). These FRELs are generated based on historical CO2 emissions in the land use, land use change, and forestry sector, and are derived using remote sensing (RS) data and in-situ forest carbon measurements. Since the quality of the historical emissions estimates is affected by the quality and quantity of the RS data used, in this study we calculated five metrics (i-v below) to assess the quality and quantity of the data that has been used thus far. Countries could focus on improving on one or more of these metrics for the submission of future FRELs. Some of our main findings were: (i) the median percentage of each country mapped was 100%, (ii) the median historical timeframe for which RS data was used was 11.5 years, (iii) the median interval of forest map updates was 4.5 years, (iv) the median spatial resolution of the RS data was 30m, and (v) the median number of REDD+ activities that RS data was used for operational monitoring of was 1 (typically deforestation). Many new sources of RS data have become available in recent years, so complementary or alternative RS data sets for generating future FRELs can potentially be identified based on our findings; e.g. alternative RS data sets could be considered if they have similar or higher quality/quantity than the currently-used data sets.

  1. Dropwise condensation dynamics in humid air

    Science.gov (United States)

    Castillo Chacon, Julian Eduardo

    Dropwise condensation of atmospheric water vapor is important in multiple practical engineering applications. The roles of environmental factors and surface morphology/chemistry on the condensation dynamics need to be better understood to enable efficient water-harvesting, dehumidication, and other psychrometric processes. Systems and surfaces that promote faster condensation rates and self-shedding of condensate droplets could lead to improved mass transfer rates and higher water yields in harvesting applications. The thesis presents the design and construction of an experimental facility that allows visualization of the condensation process as a function of relative humidity. Dropwise condensation experiments are performed on a vertically oriented, hydrophobic surface at a controlled relative humidity and surface subcooling temperature. The distribution and growth of water droplets are monitored across the surface at different relative humidities (45%, 50%, 55%, and 70%) at a constant surface subcooling temperature of 15 °C below the ambient temperature. The droplet growth dynamics exhibits a strong dependency on relative humidity in the early stages during which there is a large population of small droplets on the surface and single droplet growth dominates over coalescence effects. At later stages, the dynamics of droplet growth is insensitive to relative humidity due to the dominance of coalescence effects. The overall volumetric rate of condensation on the surface is also assessed as a function of time and ambient relative humidity. Low relative humidity conditions not only slow the absolute rate of condensation, but also prolong an initial transient regime over which the condensation rate remains significantly below the steady-state value. The current state-of-the-art in dropwise condensation research indicates the need for systematic experimental investigations as a function of relative humidity. The improved understanding of the relative humidity

  2. Reversible Humidity Sensitive Clothing for Personal Thermoregulation

    Science.gov (United States)

    Zhong, Ying; Zhang, Fenghua; Wang, Meng; Gardner, Calvin J.; Kim, Gunwoo; Liu, Yanju; Leng, Jinsong; Jin, Sungho; Chen, Renkun

    2017-03-01

    Two kinds of humidity-induced, bendable smart clothing have been designed to reversibly adapt their thermal insulation functionality. The first design mimics the pores in human skin, in which pre-cut flaps open to produce pores in Nafion sheets when humidity increases, as might occur during human sweating thus permitting air flow and reducing both the humidity level and the apparent temperature. Like the smart human sweating pores, the flaps can close automatically after the perspiration to keep the wearer warm. The second design involves thickness adjustable clothes by inserting the bent polymer sheets between two fabrics. As the humidity increases, the sheets become thinner, thus reducing the gap between the two fabrics to reduce the thermal insulation. The insulation layer can recover its original thickness upon humidity reduction to restore its warmth-preservation function. Such humidity sensitive smart polymer materials can be utilized to adjust personal comfort, and be effective in reducing energy consumption for building heating or cooling with numerous smart design.

  3. Micro Humidity Sensor with High Sensitivity and Quick Response/Recovery Based on ZnO/TiO2 Composite Nanofibers

    Institute of Scientific and Technical Information of China (English)

    XU Lei; WANG Rui; XIAO Qi; ZHANG Dan; LIU Yong

    2011-01-01

    ZnO/Ti02 composite nanofibers are synthesized by an electrospinning method and characterized by x-ray diffraction,scanning electron microscopy,and transmission electron microscopy.A micro humidity sensor is fabricated by spinning the precursors of these nanofibers on a ceramic substrate with Ag-Pd interdigitated electrodes.Humidity sensing investigation reveals that this micro sensor offers high sensitivity and quick response/recovery at an operating frequency of 100 Hz.The corresponding impedance changes more than four orders of magnitude within the whole humidity range from 10% to 90% relative humidity (RH),and the response and recovery times are about 4 and 12s,respectively.The maximum hysteresis is around 2% RH.The humidity sensing mechanism is also discussed based on the nanofiber structure and morphology.

  4. River Temperature Dynamics and Habitat Characteristics as Predictors of Salmonid Abundance using Fiber-Optic Distributed Temperature Sensing

    Science.gov (United States)

    Gryczkowski, L.; Gallion, D.; Haeseker, S.; Bower, R.; Collier, M.; Selker, J. S.; Scherberg, J.; Henry, R.

    2011-12-01

    Salmonids require cool water for all life stages, including spawning and growth. Excessive water temperature causes reduced growth and increased disease and mortality. During the summer, salmonids seek local zones of cooler water as a refuge from elevated temperatures. They also prefer specific habitat features such as boulders and overhanging vegetation. The purpose of this study is to determine whether temperature dynamics or commonly measured fish habitat metrics best explain salmonid abundance. The study site was a 2-kilometer reach of the Walla Walla River near Milton-Freewater, OR, USA, which provides habitat for the salmonids chinook salmon (Oncorhynchus tshawytscha), steelhead/rainbow trout (Oncorhynchus mykiss), mountain whitefish (Prosopium williamsoni), and the endangered bull trout (Salvelinus confluentus). The Walla Walla River is listed as an impaired water body under section 303(d) of the Clean Water Act due to temperature. The associated total maximum daily load (TMDL) calls for temperatures to be below 18 °C at all times for salmonid rearing and migration; however, river temperatures surpassed 24 °C in parts of the study reach in 2009. The two largest factors contributing to the warmer water are reduced riparian vegetation, which decreases shading and increases direct solar radiation, and decreased summer flows caused by diversions and irrigation for agriculture. Fiber-optic distributed temperature sensing has emerged as a unique and powerful tool for ecological applications because of its high spatial and temporal resolution. In this study, meter-scale temperature measurements were obtained at 15-minute intervals along the length of the study reach, allowing for the detection and quantification of cold water inflows during the summer of 2009. The cold water inflows were classified as groundwater or hyporheic sources based on the diurnal temperature patterns. Snorkel surveys were conducted in mid-July and mid-August, 2009 to enumerate salmonid

  5. Measurement of NPK, Temperature, Moisture, Humidity using WSN

    Directory of Open Access Journals (Sweden)

    Mr. Gaikwad S.V,

    2015-08-01

    Full Text Available In India, where the economy is mainly base on agriculture and the climatic conditions are isotropic and are not able to make full use of agricultural resources. The main reason is the lack of rains and scarifies of land reservoir water and overused of fertilizers so we need to control these parameters. This system made wireless sensor network for monitoringagricultural environments for various factors such as NPK, temperature and humidity along with other factors can be of significance.By using pH sensors we get the information about the soil and analyze the acid level of the soil. By which we can apply fertilizer to the place where it needs, also we can avoid over fertilization of the crops. We used humidity sensor to sense the weather. By this the farmer can get idea about the climate. If there is any chance for rainfall; the farmer need not irrigate the crop field. This Seminar reports the design and development of a smart wireless sensor network (WSN for an agricultural environment. Monitoring agricultural environments for various factors such as Nitrates, Zink, Potassium, Phosphorus, Humidity and Temperature along with other factors can be of significance. The ability to document and detail changes in parameters of interest has become increasingly valuable. Investigations were performed for a remote monitoring system using WiFi, where the wireless sensor nodes are based on WSN802G modules. These nodes send data wirelessly to a central server, which collects the data, stores it and allows it to be analyzed and displayed as needed.

  6. Retrieval and Validation of Upper Tropospheric Humidity from SAPHIR aboard Megha-Tropics

    Science.gov (United States)

    Mathew, Nizy; Krishna Moorthy, K.; Raju C, Suresh; Pillai Renju, Ramachandran; Oommen John, Viju

    Upper tropospheric humidity (UTH) has been derived from brightness temperature of SAPHIR payload aboard Megha-Tropiques (MT) mission. The channels of SAPHIR are very close to the water vapor absorption peak at 183.31GHz. First three channels at 183.31±0.2 GHz, 183.31±1.1 GHz and 183.31±2.8 are used for upper tropospheric humidity (UTH) studies. The channel at 183.31±0.2 GHz enables retrieval of humidity up to the highest altitude possible with the present nadir looking microwave humidity sounders. Transformation coefficients for the first three channels for all the incidence angles have been derived using the simulated brightness temperatures and Jocobians with Chevellier data set as input to the radiative transfer model ARTS. These coefficients are used to convert brightness temperatures to upper tropospheric humidity from different channels. A stringent deep convective cloud screeing has been done using the brightness temperatures of SAPHIR itself. The retrieved UTH has been validated with the Jacobian weighted UTH derived from collocated radiosonde observations and also with the humidity profiles derived from ground based microwave radiometer data. UTH variation over the inter-tropical region on global basis has been studied for one year, taking the advantage of the first humidity product with high spatial and temporal resolution over the tropical belt, unbiased with specific local times of the satellite pass. These data set have been used to adress the seasonal and spatial variability of humidity in the tropical upper tropospheric region and humidity variability during Indian monsoon. The details of the MT-SAPHIR characteristics, methodology and results will be presented. begin{enumerate} begin{center}

  7. A Humidity Sensor Based on Silver Nanoparticles Thin Film Prepared by Electrostatic Spray Deposition Process

    Directory of Open Access Journals (Sweden)

    Thutiyaporn Thiwawong

    2013-01-01

    Full Text Available In this work, thin film of silver nanoparticles for humidity sensor application was deposited by electrostatic spray deposition technique. The influence of the deposition times on properties of films was studied. The crystal structures of sample films, their surface morphology, and optical properties have been investigated by X-ray diffraction (XRD, field emission scanning electron microscopy (FE-SEM, and UV-VIS spectrophotometer, respectively. The crystalline structure of silver nanoparticles thin film was found in the orientation of (100 and (200 planes of cubic structure at diffraction angles 2θ  =  38.2° and 44.3°, respectively. Moreover, the silver nanoparticles thin films humidity sensor was fabricated onto the interdigitated electrodes. The sensor exhibited the humidity adsorption and desorption properties. The sensing mechanisms of the device were also elucidated by complex impedance analysis.

  8. Analyses of hot and humid weather in Beijing city in summer and its dynamical identification

    Institute of Scientific and Technical Information of China (English)

    GAO; Shouting; ZHOU; Yushu; LEI; Ting; SUN; Jianhua

    2005-01-01

    The circulation, hygrothermal property and moisture transport character of typical hot and humid weather were analyzed in Beijing areas from July 30 to August 4, 2002. It was pointed out that, under the control of subtropical anticyclone which stretches to the west and north, downdraft suppresses the lifting of lower-troposphere moisture, which makes moisture keep in the lower troposphere. That is the direct reason causing hot and humid weather. Considering the non-uniformity saturated character in real atmosphere, generalized moist potential vorticity (GMPV) equation is derived by the introduction of generalized moist potential temperature concept. The analysis of GMPV shows that negative GMPV anomaly occurs in the lower troposphere. It has indicative sense to hot and humid weather. Thus, the GMPV anomaly can be utilized to identify this kind of weather and to make a short-term prediction.

  9. Correlating Humidity-Dependent Ionically Conductive Surface Area with Transport Phenomena in Proton-Exchange Membranes

    Energy Technology Data Exchange (ETDEWEB)

    He, Qinggang; Kusoglu, Ahmet; Lucas, Ivan T.; Clark, Kyle; Weber, Adam Z.; Kostecki, Robert

    2011-08-01

    The objective of this effort was to correlate the local surface ionic conductance of a Nafion? 212 proton-exchange membrane with its bulk and interfacial transport properties as a function of water content. Both macroscopic and microscopic proton conductivities were investigated at different relative humidity levels, using electrochemical impedance spectroscopy and current-sensing atomic force microscopy (CSAFM). We were able to identify small ion-conducting domains that grew with humidity at the surface of the membrane. Numerical analysis of the surface ionic conductance images recorded at various relative humidity levels helped determine the fractional area of ion-conducting active sites. A simple square-root relationship between the fractional conducting area and observed interfacial mass-transport resistance was established. Furthermore, the relationship between the bulk ionic conductivity and surface ionic conductance pattern of the Nafion? membrane was examined.

  10. A highly sensitive humidity sensor based on a nanofibrous membrane coated quartz crystal microbalance

    Energy Technology Data Exchange (ETDEWEB)

    Wang Xianfeng; Ding Bin [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Materials Science and Engineering, Donghua University, Shanghai 201620 (China); Yu Jianyong [Nanomaterials Research Center, Modern Textile Institute, Donghua University, Shanghai 200051 (China); Wang, Moran [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Pan Fukui, E-mail: binding@dhu.edu.cn [College of Textiles and Fashion, Qingdao University, Qingdao 266071 (China)

    2010-02-05

    A novel humidity sensor was fabricated by electrospinning deposition of nanofibrous polyelectrolyte membranes as sensitive coatings on a quartz crystal microbalance (QCM). The results of sensing experiments indicated that the response of the sensors increased by more than two orders of magnitude with increasing relative humidity (RH) from 6 to 95% at room temperature, exhibiting high sensitivity, and that, in the range of 20-95% RH, the Log({Delta}f) showed good linearity. The sensitivity of fibrous composite polyacrylic acid (PAA)/poly(vinyl alcohol) (PVA) membranes was two times higher than that of the corresponding flat films at 95% RH. Compared with fibrous PAA/PVA membranes, the nanofibrous PAA membranes exhibited remarkably enhanced humidity sensitivity due to their high PAA content and large specific surface area caused by the formation of ultrathin nanowebs among electrospun fibers. Additionally, the resultant sensors exhibited a good reversible behavior and good long term stability.

  11. A highly sensitive humidity sensor based on a nanofibrous membrane coated quartz crystal microbalance

    Science.gov (United States)

    Wang, Xianfeng; Ding, Bin; Yu, Jianyong; Wang, Moran; Pan, Fukui

    2010-02-01

    A novel humidity sensor was fabricated by electrospinning deposition of nanofibrous polyelectrolyte membranes as sensitive coatings on a quartz crystal microbalance (QCM). The results of sensing experiments indicated that the response of the sensors increased by more than two orders of magnitude with increasing relative humidity (RH) from 6 to 95% at room temperature, exhibiting high sensitivity, and that, in the range of 20-95% RH, the Log(Δf) showed good linearity. The sensitivity of fibrous composite polyacrylic acid (PAA)/poly(vinyl alcohol) (PVA) membranes was two times higher than that of the corresponding flat films at 95% RH. Compared with fibrous PAA/PVA membranes, the nanofibrous PAA membranes exhibited remarkably enhanced humidity sensitivity due to their high PAA content and large specific surface area caused by the formation of ultrathin nanowebs among electrospun fibers. Additionally, the resultant sensors exhibited a good reversible behavior and good long term stability.

  12. Influence of temperature and humidity on the detection of benzene vapor by piezoelectric crystal sensor

    CERN Document Server

    Han, Chan-Hyon; Yun, Jong-Ho; Sin, Kye-Ryong

    2016-01-01

    The effects of temperature and humidity on the estimation of air pollution by benzene by using the piezoelectric crystal gas sensor were studied. Polyvinylchloride films were used as substrate for the immobilization of polymethylphenylsiloxane onto the electrode surface of the piezoelectric crystal. The sensing layer consisting of polymethylphenylsiloxane and polyvinylchloride was used for real-time monitoring of benzene, one of the atmospheric pollutants. According to the humidity from 35% to 75%, the upper limit of detection by this sensor was decreased and the response time and frequency recovery time for detecting benzene were long. On the other hand, as increasing the temperature, the response time and the frequency recovery time of the sensor were short, but its sensitivity got worse. The models for the correlation between the benzene concentration and temperature (or humidity) were presented.

  13. Decrease of Building’s Humidity with Epiphyte and Xerophyte

    Directory of Open Access Journals (Sweden)

    Erlina Laksmiani Wahjutami

    2016-01-01

    Full Text Available This article is part of the research phase in Environmental Sciences Doctoral study program that is interdisciplinary research, ongoing. Architecture disciplines collaborate with the disciplines of biology to solve the problem of the microclimate in the built. Paradigm used as benchmarks is bioclimatic architecture in which there is a relationship between elements of the building, climate, and living organisms. Living organisms - in this case the plant - used as a tool to solve the problem of the microclimate in buildings. Plant is one of the living organisms that grow and thrive in their respective habitats and the climate of each character. Several studies have shown that plants are able to lower both ambient temperature and the temperature inside the building. In this study, the problem is the existence of a higher humidity levels in small type of dwelling (STD that has been totally renovated. Meanwhile Epiphytic and Xerophyte are plants that live by absorbing surrounding moisture. In the next stage of research, it is expected that the capability of Epiphyte and Xerophyte’s plants to reduce the building’s humidity proven. From the interpretation Q.S. 23: 17, implied that: Allah has bring down the water to the earth to grow a variety of plants [1]. The diversity of these plants would be useful for people who have sense. Building as the built environment will become sustainable environment when the human capable of utilizing plants as part of it.

  14. Humidity control tool for neonatal incubator.

    Science.gov (United States)

    Abdiche, M; Farges, G; Delanaud, S; Bach, V; Villon, P; Libert, J P

    1998-03-01

    In the first days of life, the daily evaporative loss from premature neonates can reach up to 20% of body mass. Such loss can be reduced by increasing the air humidity inside the incubator. Neither passive humidification nor open loop systems allow high humidity rates to be maintained or easily controlled: at 34 degrees C, the maximum levels vary with the system from 40% to 77% of relative humidity. The skin evaporative exchanges between the neonate and the environment are directly proportional to the water vapour partial pressure difference between the neonate's skin and the air. An active closed loop system has been designed, which permits reliable and accurate control of humidity according to the water vapour partial pressure set, between 1 and 6 kPa, in an air temperature range of 28-39 degrees C. It is characterised by variations of about 0.05 kPa around the set value and a maximum humidification speed of 0.25 kPa min-1. The algorithm is based on optimal control and the dynamic programming principles. Test results place this active system above usual systems for its power, precision and adaptability. It is an exploitable tool in fundamental and clinical research, to precisely study the humidity effects on neonatal comfort and thermo-regulation evolution.

  15. Humidity effects on wire insulation breakdown strength.

    Energy Technology Data Exchange (ETDEWEB)

    Appelhans, Leah

    2013-08-01

    Methods for the testing of the dielectric breakdown strength of insulation on metal wires under variable humidity conditions were developed. Two methods, an ASTM method and the twisted pair method, were compared to determine if the twisted pair method could be used for determination of breakdown strength under variable humidity conditions. It was concluded that, although there were small differences in outcomes between the two testing methods, the non-standard method (twisted pair) would be appropriate to use for further testing of the effects of humidity on breakdown performance. The dielectric breakdown strength of 34G copper wire insulated with double layer Poly-Thermaleze/Polyamide-imide insulation was measured using the twisted pair method under a variety of relative humidity (RH) conditions and exposure times. Humidity at 50% RH and below was not found to affect the dielectric breakdown strength. At 80% RH the dielectric breakdown strength was significantly diminished. No effect for exposure time up to 140 hours was observed at 50 or 80%RH.

  16. [Characteristics of terrestrial ecosystem primary productivity in East Asia based on remote sensing and process-based model].

    Science.gov (United States)

    Zhang, Fang-Min; Ju, Wei-Min; Chen, Jing-Ming; Wang, Shao-Qiang; Yu, Gui-Rui; Han, Shi-Jie

    2012-02-01

    Based on the bi-linearly interpolated meteorological reanalysis data from National Centers for Environmental Prediction, USA and by using the leaf area index data derived from the GIMMS NDVI to run the process-based Boreal Ecosystems Productivity Simulator (BEPS) model, this paper simulated and analyzed the spatiotemporal characteristics of the terrestrial ecosystem gross primary productivity (GPP) and net primary productivity (NPP) in East Asia in 2000-2005. Before regional simulating and calculating, the observation GPP data of different terrestrial ecosystem in 15 experimental stations of AsiaFlux network and the inventory measurements of NPP at 1300 sampling sites were applied to validate the BEPS GPP and NPP. The results showed that BEPS could well simulate the changes in GPP and NPP of different terrestrial ecosystems, with the R2 ranging from 0.86 to 0.99 and the root mean square error (RMSE) from 0.2 to 1.2 g C x m(-2) x d(-1). The simulated values by BEPS could explain 78% of the changes in annual NPP, and the RMSE was 118 g C x m(-2) x a(-1). In 2000-2005, the averaged total GPP and total NPP of the terrestrial ecosystems in East Asia were 21.7 and 10.5 Pg C x a(-1), respectively, and the GPP and NPP exhibited similar spatial and temporal variation patterns. During the six years, the total NPP of the terrestrial ecosystems varied from 10.2 to 10.7 Pg C x a(-1), with a coefficient of variation being 2. 2%. High NPP (above 1000 g C x m(-2) x a(-1)) occurred in the southeast island countries, while low NPP (below 30 g C x m(-2) x a(-1)) occurred in the desert area of Northwest China. The spatial patterns of NPP were mainly attributed to the differences in the climatic variables across East Asia. The NPP per capita also varied greatly among different countries, which was the highest (70217 kg C x a(-1)) in Mongolia, far higher than that (1921 kg C x a(-1)) in China, and the lowest (757 kg C x a(-1)) in India.

  17. DESIGN NOTE: A simple and inexpensive humidity control chamber

    Science.gov (United States)

    Harris, K. D.; Huizinga, A.; Brett, M. J.

    2002-01-01

    A low-cost humidity control chamber is described which is capable of varying the relative humidity of an enclosed volume between nominal values of 1 and 97%. The humidity is controlled by varying the duty cycle of two fans supplying respectively dry and humid air to the chamber.

  18. Effects of Humidity and Surface on Photoalignment of Brilliant Yellow

    Science.gov (United States)

    2016-10-14

    high humidity (a sealed box containing water, 80-90% RH) or low humidity (a closed box containing bentonite clay desiccant, ក% RH) for different...kept at high humidity (a sealed box containing water, 80- 90% RH) and one was kept at low humidity (a box containing bentonite clay desiccant, ក% RH

  19. Lanthanide-halide based humidity indicators

    Science.gov (United States)

    Beitz, James V.; Williams, Clayton W.

    2008-01-01

    The present invention discloses a lanthanide-halide based humidity indicator and method of producing such indicator. The color of the present invention indicates the humidity of an atmosphere to which it is exposed. For example, impregnating an adsorbent support such as silica gel with an aqueous solution of the europium-containing reagent solution described herein, and dehydrating the support to dryness forms a substance with a yellow color. When this substance is exposed to a humid atmosphere the water vapor from the air is adsorbed into the coating on the pore surface of the silica gel. As the water content of the coating increases, the visual color of the coated silica gel changes from yellow to white. The color change is due to the water combining with the lanthanide-halide complex on the pores of the gel.

  20. Optimal Design of a Polyaniline-Coated Surface Acoustic Wave Based Humidity Sensor

    Science.gov (United States)

    Wang, Wen; Xie, Xiao; He, Shitang

    2013-01-01

    This paper presents an optimal design for a new humidity sensor composed of a dual-resonator oscillator configuration with an operation frequency of 300 MHz, and a polyaniline (PANI) coating deposited along the resonation cavity of the sensing device. To improve the corrosion resistance of the sensor chip, Al/Au electrodes were used to form the SAW resonator. Prior to device fabrication, the coupling of modes (COM) model was used for the performance prediction and optimal design parameters determination. Two SAW resonators with Al/Au electrodes were fabricated on an ST-X quartz substrate, and used as the frequency control element in the feedback path of an oscillator circuit. A PANI thin coating was deposited onto the resonator cavity of the sensing device by a spinning approach as the sensor material for relative humidity (RH) detection. High detection sensitivity, quick response, good repeatability and stability were observed from the sensor experiments at room temperature.

  1. Optimal Design of a Polyaniline-Coated Surface Acoustic Wave Based Humidity Sensor

    Directory of Open Access Journals (Sweden)

    Wen Wang

    2013-12-01

    Full Text Available This paper presents an optimal design for a new humidity sensor composed of a dual-resonator oscillator configuration with an operation frequency of 300 MHz, and a polyaniline (PANI coating deposited along the resonation cavity of the sensing device. To improve the corrosion resistance of the sensor chip, Al/Au electrodes were used to form the SAW resonator. Prior to device fabrication, the coupling of modes (COM model was used for the performance prediction and optimal design parameters determination. Two SAW resonators with Al/Au electrodes were fabricated on an ST-X quartz substrate, and used as the frequency control element in the feedback path of an oscillator circuit. A PANI thin coating was deposited onto the resonator cavity of the sensing device by a spinning approach as the sensor material for relative humidity (RH detection. High detection sensitivity, quick response, good repeatability and stability were observed from the sensor experiments at room temperature.

  2. TiO2-TiO2 composite resistive humidity sensor: ethanol crosssensitivity

    Science.gov (United States)

    Ghalamboran, Milad; Saedi, Yasin

    2016-03-01

    The fabrication method and characterization results of a TiO2-TiO2 composite bead used for humidity sensing along with its negative cross-sensitivity to ethanol vapor are reported. The bead shaped resistive sample sensors are fabricated by the drop-casting of a TiO2 slurry on two Pt wire segments. The dried bead is pre-fired at 750°C and subsequently impregnated with a Ti-based sol. The sample is ready for characterization after a thermal annealing at 600°C in air. Structurally, the bead is a composite of the micron-sized TiO2 crystallites embedded in a matrix of nanometric TiO2 particle aggregates. The performance of the beads as resistive humidity sensors is recorded at room temperature in standard humidity level chambers. Results evince the wide dynamic range of the sensors fabricated in the low relative humidity range. While the sensor conductance is not sensitive to ethanol vapor in dry air, in humid air, sensor's responses are negatively affected by the contaminant.

  3. AC Response to Humidity and Propane of Sprayed Fe-Zn Oxide Films

    Directory of Open Access Journals (Sweden)

    Alejandro AVILA-GARCÍA

    2009-09-01

    Full Text Available Iron-zinc oxide films with different Zn contents were ultrasonically sprayed on glass substrates and inter-digital gold electrodes were evaporated upon them. Films were deposited from solutions containing 2, 10 and 30 at. % Zn. Hematite, amorphous and Franklinite structures turned out, respectively. They were assessed as humidity and propane detectors under alternating-current conditions for frequencies from 1 to 105 Hz and temperatures 30 and 250 oC. Their impedances in dry air, humid air and humid air plus propane were determined from voltage measurements with a Lock-In amplifier. Sensitivities to humidity (53 % RH. and 189, 500 and 786 ppm of propane from the response of the resistance, reactance and also the total impedance were determined as functions of frequency. The maximum sensitivity to humidity ranges from 24 % up to 308 %. For propane, the maximum sensitivity ranges from 45 % up to 711 %. The largest sensitivity values correspond in all cases to reactance. From the dynamical response, the response and recovery times are determined, along with the concentration-dependence of the sensitivity. The sensing mechanisms are commented.

  4. Fiber optic humidity sensor based on the graphene oxide/PVA composite film

    Science.gov (United States)

    Wang, Youqing; Shen, Changyu; Lou, Weimin; Shentu, Fengying

    2016-08-01

    Fiber optic humidity sensor based on an in-fiber Mach-Zehnder interferometer (MZI) coated with graphene oxide (GO)/PVA composite film was investigated. The MZI is constructed of two waist-enlarged tapers. The length between two waist-enlarged tapers is 20 mm. By comparing the experiment results of MZI coated with different GO/PVA composite films, composite film formed by the ratio of 0.3 g PVA mixed with 10 ml GO dispersion shows a better performance of relative humidity sensing. By using the molecular structure model of the composited GO/PVA, the operation mechanism between GO/PVA composite film and water molecules was illustrated. The sensitivity of 0.193 dB/%RH with a linear correlation coefficient of 99.1% and good stability under the relative humidity range of 25-80% was obtained. Temperature effect on the proposed fiber optic humidity sensor was also considered and analyzed. According to the repetitive experimental results, the proposed humidity sensor shows a good repeatability.

  5. Humidity Sensitivity of Multi-Walled Carbon Nanotube Networks Deposited by Dielectrophoresis

    Directory of Open Access Journals (Sweden)

    Tianhong Cui

    2009-03-01

    Full Text Available This paper presents an investigation on the humidity sensitivity of deposited multi-walled carbon nanotube (MWCNT networks using ac dielectrophoresis (DEP between interdigitated electrodes (IDEs. MWCNTs dispersed in ethanol were trapped and enriched between IDEs on a Si/SiO2 substrate under a positive DEP force. After the DEP process, the ethanol was evaporated and the MWCNT network on a substrate with IDEs was put into a furnace for repeated thermal annealing. It was found that the resistance stability of the network was effectively improved through thermal annealing. The humidity sensitivity was obtained by measuring the resistance of the MWCNT network with different relative humidity at room temperature. The experimental results show the resistance increases linearly with increasing the relative humidity from 25% to 95% RH with a sensitivity of 0.5%/%RH. The MWCNT networks have a reversible humidity sensing capacity with response time and recovery time of about 3 s and 25 s, respectively. The resistance is dependent on temperature with a negative coefficient of about -0.33%/K in a temperature range from 293 K to 393 K.

  6. Humidity fluctuations in the marine boundary layer measured at a coastal site with an infrared humidity sensor

    DEFF Research Database (Denmark)

    Sempreviva, A.M.; Gryning, Sven-Erik

    1996-01-01

    An extensive set of humidity turbulence data has been analyzed from 22-m height in the marine boundary layer. Fluctuations of humidity were measured by an ''OPHIR'', an infrared humidity sensor with a 10 Hz scanning frequency and humidity spectra were produced. The shapes of the normalized spectr...

  7. Mesoporous Silicate Materials in Sensing

    Directory of Open Access Journals (Sweden)

    Paul T. Charles

    2008-08-01

    Full Text Available Mesoporous silicas, especially those exhibiting ordered pore systems and uniform pore diameters, have shown great potential for sensing applications in recent years. Morphological control grants them versatility in the method of deployment whether as bulk powders, monoliths, thin films, or embedded in coatings. High surface areas and pore sizes greater than 2 nm make them effective as adsorbent coatings for humidity sensors. The pore networks also provide the potential for immobilization of enzymes within the materials. Functionalization of materials by silane grafting or through cocondensation of silicate precursors can be used to provide mesoporous materials with a variety of fluorescent probes as well as surface properties that aid in selective detection of specific analytes. This review will illustrate how mesoporous silicas have been applied to sensing changes in relative humidity, changes in pH, metal cations, toxic industrial compounds, volatile organic compounds, small molecules and ions, nitroenergetic compounds, and biologically relevant molecules.

  8. Study of dew water collection in humid tropical islands

    Science.gov (United States)

    Clus, O.; Ortega, P.; Muselli, M.; Milimouk, I.; Beysens, D.

    2008-10-01

    SummaryAn assessment of the potential for dew water to serve as a potable water source during a rainless season in a humid tropical climate was carried out in the Pacific islands of French Polynesia. The climate of these islands, in terms of diurnal and seasonal variations, wind and energy balance, is representative of the climate of the tropical Atlantic and Pacific oceans. Measurements were obtained at two characteristic sites of this region; a mountainous island (Punaauia, Tahiti Island) and an atoll (Tikehau, Tuamotu Archipelago). Dew was measured daily on a 30° tilted, 1 m 2 plane collector equipped with a thermally insulated radiative foil. In addition, an electronic balance placed at 1 m above the ground with a horizontal 0.16 m 2 condensing plate made of PolyTetraFluoroEthylene (Teflon) was used in Tahiti. Dew volume data, taken during the dry season from 16/5/2005 to 14/10/2005, were correlated with air temperature and relative humidity, wind speed, cloud cover and visible plus infrared radiometer measurements. The data were also fitted to a model. Dew formation in such a tropical climate is characterized by high absolute humidity, weak nocturnal temperature drop and strong Trade winds. These winds prevent dew from forming unless protected e.g. by natural vegetal windbreaks. In protected areas, dew can then form with winds as large as 7 m/s. Such strong winds also hamper at night the formation near the ground of a calm and cold air layer with high relative humidity. As the cooling power is lower than in the Mediterranean islands because of the high absolute humidity of the atmosphere, both effects combine to generate modest dew yields. However, dew events are frequent and provide accumulated amounts of water attractive for dew water harvesting. Slight modifications of existing rain collection devices on roofs can enhance dew formation and collection. Dew harvesting thus appears as an attractive possibility to provide the local population with a

  9. Humidity-independent conducting polyaniline films synthesized using advanced atmospheric pressure plasma polymerization with in-situ iodine doping

    Science.gov (United States)

    Park, Choon-Sang; Kim, Do Yeob; Kim, Dong Ha; Lee, Hyung-Kun; Shin, Bhum Jae; Tae, Heung-Sik

    2017-01-01

    This study reports on the synthesis and characterization of conducting polyaniline (PANI) thin films when using advanced atmospheric pressure plasma jets (APPJs). A simple method for synthesizing conducting polymers (CPs) with humidity-independent characteristics is introduced using advanced APPJs and an in-situ iodine doping method. In the case of ex-situ I2 doping, a humidity effect study showed that increasing the relative humidity produced significant changes in the electrical resistance (R) of the PANI, indicating strong humidity-dependent characteristics similar to conventional CPs. In contrast, in the case of in-situ I2 doping, the R and sensitivity of the PANI remained essentially unchanged when increasing the relative humidity, except for a very low sensitivity of 0.5% under 94% relative humidity. In addition, the R for the PANI with in-situ I2 doping showed no aging effect, while the R for the ex-situ-doped PANI increased dramatically over time. Thus, it is anticipated that the use of in-situ doping during plasma polymerization can be widely used to design stable and high-performance CPs with humidity-independent characteristics for a variety of applications.

  10. SnO2-MOF-Fabry-Perot humidity optical sensor system based on fast Fourier transform technique

    Science.gov (United States)

    Lopez-Aldaba, A.; Lopez-Torres, D.; Ascorbe, J.; Rota-Rodrigo, S.; Elosua, C.; Lopez-Amo, M.; Arregui, F. J.; Corres, J. M.; Auguste, J.-L.; Jamier, R.; Roy, P.

    2016-05-01

    In this paper, a new sensor system for relative humidity measurements based on a SnO2 sputtering deposition on a microstructured optical fiber (MOF) low-finesse Fabry-Perot (FP) sensing head is presented and characterized. The interrogation of the sensing head is carried out by monitoring the Fast Fourier Transform phase variations of the FP interference frequency. This method is low-sensitive to signal amplitude variations and also avoids the necessity of tracking the evolution of peaks and valleys in the spectrum. The sensor is operated within a wide humidity range (20%-90% relative humidity) with a maximum sensitivity achieved of 0.14rad/%. The measurement method uses a commercial optical interrogator as the only active element, this compact solution allows real time analysis of the data.

  11. Soil erosion in humid regions: a review

    Science.gov (United States)

    Daniel J. Holz; Karl W.J. Williard; Pamela J. Edwards; Jon E. Schoonover

    2015-01-01

    Soil erosion has significant implications for land productivity and surface water quality, as sediment is the leading water pollutant worldwide. Here, erosion processes are defined. The dominant factors influencing soil erosion in humid areas are reviewed, with an emphasis on the roles of precipitation, soil moisture, soil porosity, slope steepness and length,...

  12. Remote sensing of natural phenomena

    Directory of Open Access Journals (Sweden)

    Miodrag D. Regodić

    2014-06-01

    monitoring natural phenomena The images taken from Remote Sensing have helped men to use the environment and natural resources in a better way. It is expected that the developement of new technologies will spread the usage of satellite images for the welfare of mankind as well.  Besides monitoring the surface of the Earth, the satellite monitoring of  the processes inside the Earth itself is of great importance since these processes can  cause different catastrophes such as earthquakes, volcano eruptions, floods, etc. Usage of satellite images in monitoring atmospheric phenomena The launch of artificial earth satellites has opened new possibilities for monitoring and studying atmospheric phenomena. A large number of meteorological satellites have been launched by now (Nimbus, Meteor, SNS, ESSA, Meteosat, Terra, etc.. Since these images are primarily used for weather forecast, meteorologists use them to get information about the characteristics of clouds related to their temperature, the temperature of the cloud layer, the degree of cloudness, the profiles of humidity content, the wind parameters, etc. Meteosat satellites Meteosat is the first European geostationary satellite designed for meteorological research. The use of these satellites enabled the surveying in the visible and the near IR part of the spectrum as well as in the infrared thermal and water steam track. Based on these images, it was possible to obtain data such as:  height of clouds, cloud spreading and moving, sea surface temperature, speed of wind, distribution of the water steam, balance of radiation, etc. Usage of satellite images in monitoring floods Satellite images are an excellent background and an initial phase for preventing severe catastrophic events caused by floods. Due to satellite images, it is possible to manage overflown regions before, during and after floods. This enables prevention, forecasting, detection and elimination of consequences, i.e. demage. Satellite images are of great help

  13. A New Forecast Method of Forest Fire Risk Rating Based on Remote Sensing Data of Land Surface Temperature and Humidity%基于地表温度与湿度场遥感数据的火险等级预报新技术

    Institute of Scientific and Technical Information of China (English)

    王一凯; 黄诚; 段卫虎; 王艳霞; 周汝良

    2014-01-01

    在国家森林火险等级的定性化预报方法的基础上,利用云南省气象站点样本与空间位置及相关地形地貌因子数据,借助 GIS 空间建模功能,结合云南省特有的地理特点和气候特点,提出了一种基于地表温度场、湿度场遥感数据以及风速、蒸发量空间模拟数据的火险等级预报新方法。并以云南省4月的地表温度与湿度分析模型得到的测报数据,结果表明:该方法可较好地对森林火险天气等级进行化预报,数据与云南省4月多年预报的趋势相吻合。可较好地实现森林火险等级的定量化预报。%The paper analyzed national forest fire risk rating forecast method,and proposed a new forecast method combined with the typical geographical features and climatic characteristics of Yunnan Province, which also used samples with spacial location and related landform data from Meteorology Station of Yun-nan Province.The new method was based on the remote sensing data of land surface temperature,hu-midity and the spatial simulation data of wind speed,rainfall,evaporation capacity.By analyzing the for-est data,the result showed that this method better predicted the forest fire risk rating quantitatively. Tendency of the prediction was in agreement with the previous data of Yunnan Province in April.

  14. Application of the Development in Environment Measurement and Sensibility Nano-Sensing

    Science.gov (United States)

    Noda, Kazutoshi; Aizawa, Hidenobu

    Recently, environmental pollution is social problem with nano materials and food contamination is a new social problem. On the other hand, the complaint related to the offensive odor in Japan exceeded 20,000 affairs in 1998, and these problems are not solved. The odor sensing system for detecting and control an offensive odor at an early stage is required. The sensing system using the sense of odor known as one of the fifth senses of human is proposed to these demands. Especially as for e-NOSE system, application will be expected from now on in many fields, such as medical diagnosis, health monitoring, environment, food, robot and a car. The sensing technology in which an electrochemical sensor called quartz crystal microbalance (QCM) is mainly used is making detection mechanisms, such as an electrode and a detection thin film on the nano-level. Therefore, detection films of sensor depend on the characteristic of the sensing devices using on material and processing technology. That the new technology sensor is asked can detect extremely low concentration from ppm to ppb level, and it is the sensor with low influence of environment, such as a gas of the outside for detection, temperature and humidity.

  15. LIDAR and atmosphere remote sensing

    CSIR Research Space (South Africa)

    Venkataraman, S

    2008-05-01

    Full Text Available and to consist of theory and practical exercises • Theory: Remote sensing process, Photogrammetry, introduction to multispectral, remote sensing systems, Thermal infra-red remote sensing, Active and passive remote sensing, LIDAR, Application of remotely... Aerosol measurements and cloud characteristics head2right Water vapour measurements in the lower troposphere region up to 8 km head2right Ozone measurements in the troposphere regions up to 18 km Slide 22 © CSIR 2008 www...

  16. Anomalies in relative humidity profile in the boundary layer during convective rain

    Science.gov (United States)

    Chakraborty, Rohit; Talukdar, Shamitaksha; Saha, Upal; Jana, Soumyajyoti; Maitra, Animesh

    2017-07-01

    Radiometric observations of relative humidity profile at Kolkata show a significant fall at around 1 to 2 km height during convective rain events. An extensive investigation shows that the fall of relative humidity is not seen during calm conditions but is strongly related to the characteristics of temperature lapse rate profiles. Moreover, the phenomenon may have strong association with boundary layer structure. The reason for such anomalies in the planetary boundary layer humidity profile might be due to the release of latent heat at the mentioned altitude. The abundance of pollutant aerosols in urban regions has also been found to contribute to this relative humidity anomaly. It has also been reported that this boundary layer relative humidity is accompanied by high latent heat release and condensation of vapour to liquid which is not much prominent in other rain types as observed in stratiform rain. Hence, convective rain produces some unique boundary layer characteristics which have also been partially supported with allied satellite and multi-station observations.

  17. Raoult's law revisited: accurately predicting equilibrium relative humidity points for humidity control experiments

    CERN Document Server

    Bowler, Michael G; Bowler, Matthew W

    2016-01-01

    The equilibrium relative humidity values for a number of the most commonly used precipitants in biological macromolecule crystallisation have been measured using a new humidity control device. A simple argument in statistical mechanics demonstrates that the saturated vapour pressure of a solvent is proportional to its mole fraction in an ideal solution (Raoult's Law). The same argument can be extended to the case where solvent and solute molecules are of different size.

  18. Characteristics of the Transport of a Typical Pollution Event in the Chengdu Area Based on Remote Sensing Data and Numerical Simulations

    Directory of Open Access Journals (Sweden)

    Ying Zhang

    2016-10-01

    Full Text Available A heavy air pollution event occurred in Chengdu between 7 May 2014 and 8 May 2014. The present study established tracer sources based on HJ-1 satellite data, micropulse light detection and ranging (LiDAR remote sensing data, and backward trajectories simulated using the hybrid single-particle Lagrangian integrated trajectory (HYSPLIT model. Additionally, the present study analyzed the diffusion conditions for the sources and characteristics of the pollutant transport in this pollution event through simulation using a mesoscale atmospheric chemistry transport model—the weather research forecasting model with chemistry (WRF–CHEM. The results show that the change in the boundary-layer height over Chengdu had a relatively large effect on the vertical diffusion of pollutants. During the pollution event, Chengdu, Meishan, and Leshan were areas of significantly low mean ventilation coefficients ( V H . In Chengdu, the V H was extremely low at night, and there was a temperature inversion near the ground, resulting in the continuous accumulation of pollutants at night and a continuous worsening of the pollution. During the period of heavy pollution, there were straw-burning sites in Meishan, Ziyang, Neijiang, Zigong, and Deyang. On 7 May 2014, the pollutants in Chengdu mainly originated from Meishan. The accumulation in Chengdu of pollutants originating in Meishan and Deyang led to highly concentrated pollution on 8 May 2014, to which the pollutants originating in Deyang were the main contributor. The transport of pollutants resulting from straw burning in the study area and the relatively poor conditions for the pollutant diffusion in Chengdu collectively led to the heavy air pollution event investigated in the present study.

  19. Rugged Optical Atmospheric Humidity Sensor Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Trace species measurement on unmanned atmospheric research craft suitable for interplanetary travel is a demanding application for optical sensing techniques. Yet...

  20. Single-Antenna Temperature- and Humidity-Sounding Microwave Receiver

    Science.gov (United States)

    Hoppe, Daniel J.; Pukala, David M.; Lambrigtsen, Bjorn H.; Soria, Mary M.; Owen, Heather R.; Tanner, Alan B.; Bruneau, Peter J.; Johnson, Alan K.; Kagaslahti, Pekka P.; Gaier, Todd C.

    2011-01-01

    For humidity and temperature sounding of Earth s atmosphere, a single-antenna/LNA (low-noise amplifier) is needed in place of two separate antennas for the two frequency bands. This results in significant mass and power savings for GeoSTAR that is comprised of hundreds of antennas per frequency channel. Furthermore, spatial anti-aliasing would reduce the number of horns. An anti-aliasing horn antenna will enable focusing the instrument field of view to the hurricane corridor by reducing spatial aliasing, and thus reduce the number of required horns by up to 50 percent. The single antenna/receiver assembly was designed and fabricated by a commercial vendor. The 118 183-GHz horn is based upon a profiled, smooth-wall design, and the OMT (orthomode transducer) on a quad-ridge design. At the input end, the OMT presents four ver y closely spaced ridges [0.0007 in. (18 m)]. The fabricated assembly contains a single horn antenna and low-noise broadband receiver front-end assembly for passive remote sensing of both temperature and humidity profiles in the Earth s atmosphere at 118 and 183 GHz. The wideband feed with dual polarization capability is the first broadband low noise MMIC receiver with the 118 to 183 GHz bandwidth. This technology will significantly reduce PATH/GeoSTAR mass and power while maintaining 90 percent of the measurement capabilities. This is required for a Mission-of-Opportunity on NOAA s GOES-R satellite now being developed, which in turn will make it possible to implement a Decadal-Survey mission for a fraction of the cost and much sooner than would otherwise be possible.

  1. Clinker mineral hydration at reduced relative humidities

    DEFF Research Database (Denmark)

    Jensen, Ole Mejlhede

    1998-01-01

    This report deals with gas phase hydration of pure cement clinker minerals at reduced relative humidities. This is an important subject in relation to modern high performance concrete which may self-desiccate during hydration. In addition the subject has relevance to storage stability where...... prehydration may occur. In the report both theoretical considerations and experimental data are presented. It is suggested that the initiation of hydration during water vapour exposure is nucleation controlled....

  2. Fiberboard Humidity Data for 9975 Shipping Packages

    Energy Technology Data Exchange (ETDEWEB)

    Daugherty, W. [Savannah River Site (SRS), Aiken, SC (United States)

    2015-07-31

    The 9975 surveillance program is identifying a technical basis to support extending the storage period of 9975 packages in KAC beyond the currently approved 15 years. A key element of this effort is developing a better understanding of degradation of the fiberboard assembly under storage conditions. This degradation is influenced greatly by the moisture content of the fiberboard, which is not well characterized on an individual package basis. Two efforts have been undertaken to better understand the levels and behavior of moisture within the fiberboard assemblies of the 9975 shipping package. In the first effort, an initial survey of humidity and temperature in the upper air space of 26 packages stored in KAC was made. The data collected within this first effort help to illustrate how the upper air space humidity varies with the local ambient temperature and package heat load. In the second effort, direct measurements of two test packages are providing a correlation between humidity and fiberboard moisture levels within the package, and variations in moisture throughout the fiberboard assembly. This effort has examined packages with cane fiberboard and internal heat levels of 5 and 10W to date. Additional testing is expected to include 15 and 19W heat levels, and then repeat the same four heat levels with softwood fiberboard assemblies. This report documents the data collected to date within these two efforts

  3. Fiberboard humidity data for 9975 shipping packages

    Energy Technology Data Exchange (ETDEWEB)

    Daugherty, W. L. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2015-07-31

    The 9975 surveillance program is identifying a technical basis to support extending the storage period of 9975 packages in KAC beyond the currently approved 15 years. A key element of this effort is developing a better understanding of degradation of the fiberboard assembly under storage conditions. This degradation is influenced greatly by the moisture content of the fiberboard, which is not well characterized on an individual package basis.Two efforts have been undertaken to better understand the levels and behavior of moisture within the fiberboard assemblies of the 9975 shipping package. In the first effort, an initial survey of humidity and temperature in the upper air space of 26 packages stored in KAC was made. The data collected within this first effort help to illustrate how the upper air space humidity varies with the local ambient temperature and package heat load. In the second effort, direct measurements of two test packages are providing a correlation between humidity and fiberboard moisture levels within the package, and variations in moisture throughout the fiberboard assembly. This effort has examined packages with cane fiberboard and internal heat levels of 5 and 10W to date. Additional testing is expected to include 15 and 19W heat levels, and then repeat the same four heat levels with softwood fiberboard assemblies. This report documents the data collected to date within these two efforts.

  4. Fiberboard humidity data for 9975 shipping packages

    Energy Technology Data Exchange (ETDEWEB)

    Daugherty, W. L. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2015-07-31

    The 9975 surveillance program is identifying a technical basis to support extending the storage period of 9975 packages in KAC beyond the currently approved 15 years. A key element of this effort is developing a better understanding of degradation of the fiberboard assembly under storage conditions. This degradation is influenced greatly by the moisture content of the fiberboard, which is not well characterized on an individual package basis.Two efforts have been undertaken to better understand the levels and behavior of moisture within the fiberboard assemblies of the 9975 shipping package. In the first effort, an initial survey of humidity and temperature in the upper air space of 26 packages stored in KAC was made. The data collected within this first effort help to illustrate how the upper air space humidity varies with the local ambient temperature and package heat load. In the second effort, direct measurements of two test packages are providing a correlation between humidity and fiberboard moisture levels within the package, and variations in moisture throughout the fiberboard assembly. This effort has examined packages with cane fiberboard and internal heat levels of 5 and 10W to date. Additional testing is expected to include 15 and 19W heat levels, and then repeat the same four heat levels with softwood fiberboard assemblies. This report documents the data collected to date within these two efforts.

  5. The Effect of Humidity on the Knock Behavior in a Medium BMEP Lean-Burn High-Speed Gas Engine

    NARCIS (Netherlands)

    van Essen, Vincent Martijn; Gersen, Sander; van Dijk, Gerco; Mundt, Torsten; Levinsky, Howard

    2016-01-01

    The effects of air humidity on the knock characteristics of fuels are investigated in a lean-burn, high-speed medium BMEP engine fueled with a CH4 + 4.7 mole% C3H8 gas mixture. Experiments are carried out with humidity ratios ranging from 4.3 to 11 g H2O/kg dry air. The measured pressure profiles at

  6. Lower-tropospheric humidity: climatology, trends and the relation to the ITCZ

    Directory of Open Access Journals (Sweden)

    Alexander Läderach

    2013-07-01

    Full Text Available The tropical region is an area of maximum humidity and serves as the major humidity source of the globe. Among other phenomena, it is governed by the so-called Inter-Tropical Convergence Zone (ITCZ which is commonly defined by converging low-level winds or enhanced precipitation. Given its importance as a humidity source, we investigate the humidity fields in the tropics in different reanalysis data sets, deduce the climatology and variability and assess the relationship to the ITCZ. Therefore, a new analysis method of the specific humidity distribution is introduced which allows detecting the location of the humidity maximum, the strength and the meridional extent. The results show that the humidity maximum in boreal summer is strongly shifted northward over the warm pool/Asia Monsoon area and the Gulf of Mexico. These shifts go along with a peak in the strength in both areas; however, the extent shrinks over the warm pool/Asia Monsoon area, whereas it is wider over the Gulf of Mexico. In winter, such connections between location, strength and extent are not found. Still, a peak in strength is again identified over the Gulf of Mexico in boreal winter. The variability of the three characteristics is dominated by inter-annual signals in both seasons. The results using ERA-interim data suggest a positive trend in the Gulf of Mexico/Atlantic region from 1979 to 2010, showing an increased northward shift in the recent years. Although the trend is only weakly confirmed by the results using MERRA reanalysis data, it is in phase with a trend in hurricane activity – a possible hint of the importance of the new method on hurricanes. Furthermore, the position of the maximum humidity coincides with one of the ITCZ in most areas. One exception is the western and central Pacific, where the area is dominated by the double ITCZ in boreal winter. Nevertheless, the new method enables us to gain more insight into the humidity distribution, its variability and

  7. Upper limits for air humidity based on human comfort

    DEFF Research Database (Denmark)

    Toftum, Jørn; Fanger, Povl Ole; Jørgensen, Anette S.

    1998-01-01

    respiratory cooling. Human subjects perceived the condition of their skin to be less acceptable with increasing skin humidity. Inhaled air was rated warmer, more stuffy and less acceptable with increasing air humidity and temperature. Based on the subjects' comfort responses, new upper limits for air humidity...

  8. Humidity Sensitive Properties of a Silicone-containing Polyelectrolyte Material

    Institute of Scientific and Technical Information of China (English)

    Mu Jie YANG; Zong Wu YAO; You Si CHEN; Yang LI

    2006-01-01

    Resistive-type film humidity sensors were prepared with a silicone-containing polyelectrolyte (Si-PE) and their humidity sensitive properties have been investigated. The sensors so obtained show high sensitivity to humidity variation over a wide range of RH (20-96%).In addition, they exhibit high reversibility, quick response and well long-term stability.

  9. [Analysis of Lop Nur "Ear" features in remote sensing image and its environmental meaning].

    Science.gov (United States)

    Cai, Ai-Min; Shao, Yun; Gong, Hua-Ze; Wang, Guo-Jun; Xie, Chou

    2011-06-01

    There is a great significance of revealing the characteristics of regional environment evolution and global change to the research on arid Lop Nur areas. By the "Ear" features of Lop Nur in remote sensing image, the spectrum, soil and surface parameters were analyzed. The differences in total salt content in soil and the surface structure bring are cause directly for the "Ear" features in remote sensing image; The results of the analysis of spectrum, total salt content and particle size are in good agreement. "Ear" features recorded the process of environmental change. The process implys that Lop Nur dried up gradually under the impact of global change. The adjustment during the process of drying up let Lop Nur experience two relatively humid climates, with the previous a little longer, the later very short.

  10. Experimental Study on Brush-Painted Passive RFID-Based Humidity Sensors Embedded into Plywood Structures

    Directory of Open Access Journals (Sweden)

    Erja Sipilä

    2016-01-01

    Full Text Available The integration of electronics and wood is an interesting research area due to the increasing interest to add functionality into various wooden products. The passive RFID-based humidity sensor tag prototype, presented in this paper, is fabricated directly on plywood substrate to be embedded into wooden structures, by using brush-painting and photonic sintering of cost-effective silver ink. To the best of our knowledge, this is the first demonstration of brush-painted antennas as sensor elements. The developed sensor tag is fully passive and small in size, meaning it can be permanently enclosed into wooden structures. In addition, the sensor tag has all the functionalities of an ordinary passive UHF RFID tag, and a peak read range of about 10 meters. The sensor performance was evaluated in normal room conditions, after two 100% relative humidity tests, and after drying in normal room conditions for 9 days. According to the results, the fabricated UHF RFID-based humidity sensor tags have a great potential to be utilized in humidity sensing applications, and also in normal automatic identification and supply chain control of various wooden products. In addition, the first results of more cost-effective brush-painted copper UHF RFID tags on plywood substrate are presented.

  11. Liquid exfoliated pristine WS2 nanosheets for ultrasensitive and highly stable chemiresistive humidity sensors

    Science.gov (United States)

    Jha, Ravindra Kumar; Guha, Prasanta Kumar

    2016-11-01

    WS2 nanosheets have been synthesized by ultrasonication in a binary mixture of acetone and 2-propanol, with a volume ratio of 80:20. Hansen solubility parameters were taken into consideration as part of the process. These nanosheets have been characterized by electron microscopy, atomic force microscopy, and x-ray diffraction, along with spectroscopy such as ultraviolet-visible spectroscopy, Raman spectroscopy, and x-ray photoelectron spectroscopy. The nanosheets were further used as a sensing material to fabricate a humidity sensor on interdigitated aluminum electrodes, realized over Si/SiO2 substrate using a conventional photolithography technique. The response for our sensor varied from 11.9 for 40% RH to as high as 37.5 for 80% RH. Response and recovery time were found to be 13 ± 2 s and 17 ± 2 s respectively. The suspended nanosheets were also treated with UV light in a nitrogen environment. The response for UV treated nanosheets shows better linearity, however its response decreases in the presence of humidity. This is due to a decrease in oxygen content of the UV treated sample. Furthermore, the effect of sonication time has been investigated, and it was found that samples with 10 h sonication are better than others due to their high surface-to-volume ratio. The repeatability and stability of the sensor have been investigated and found to be excellent. The hysteresis in the sensors was also explored. The mechanism of humidity sensing has been discussed in detail.

  12. Determination of equilibrium humidities using temperature and humidity controlled X-ray diffraction (RH-XRD)

    Energy Technology Data Exchange (ETDEWEB)

    Linnow, Kirsten [University of Hamburg, Department of Chemistry - Inorganic and Applied Chemistry, Martin-Luther-King-Platz 6, 20146 Hamburg (Germany); Steiger, Michael [University of Hamburg, Department of Chemistry - Inorganic and Applied Chemistry, Martin-Luther-King-Platz 6, 20146 Hamburg (Germany)]. E-mail: michael.steiger@chemie.uni-hamburg.de

    2007-01-30

    Confined growth of crystals in porous building materials is generally considered to be a major cause of damage. We report on the use of X-ray diffraction under controlled conditions of temperature and relative humidity (RH-XRD) for the investigation of potentially deleterious phase transition reactions. An improved procedure based on rate measurements is used for the accurate and reproducible determination of equilibrium humidities of deliquescence and hydration reactions. The deliquescence humidities of NaCl (75.4 {+-} 0.5% RH) and Ca(NO{sub 3}){sub 2}.4H{sub 2}O (50.8 {+-} 0.7% RH) at 25 deg. C determined with this improved RH-XRD technique are in excellent agreement with available literature data. Measurement of the hydration of anhydrous Ca(NO{sub 3}){sub 2} to form Ca(NO{sub 3}){sub 2}.2H{sub 2}O revealed an equilibrium humidity of 10.2 {+-} 0.3%, which is also in reasonable agreement with available data. In conclusion, dynamic X-ray diffraction measurements are an appropriate method for the accurate and precise determination of equilibrium humidities with a number of interesting future applications.

  13. Modelling of the humidity effect on the barrier height in SnO{sub 2} varistors

    Energy Technology Data Exchange (ETDEWEB)

    Skuratovsky, I. [Department of Radioelectronics, Dniepropetrovsk National University, Dniepropetrovsk 49050 (Ukraine); Glot, A. [Division de Estudios de Posgrado, Universidad Tecnologica de la Mixteca, Huajuapan de Leon, Oaxaca 69000 (Mexico)]. E-mail: alexglot@mixteco.utm.mx; Traversa, E. [Dip. di Scienze e Tecnologie Chimiche, Universita di Roma ' Tor Vergata' , Via della Ricerca Scientifica, 00133 Rome (Italy)

    2006-03-15

    Tin dioxide based SnO{sub 2}-Bi{sub 2}O{sub 3}-Co{sub 3}O{sub 4}-Nb{sub 2}O{sub 5}-Cr{sub 2}O{sub 3} ceramic device with combined varistor and humidity-sensitive properties is studied. This varistor-sensor has high humidity sensitivity coefficient of about 420 at low electric field and high non-linearity coefficient of about 50 at electric field 3500 V cm{sup -1}. Current-voltage characteristics of the samples with separate electrodes for the central and the peripheral parts are studied in air with different relative humidity. It is shown that current through the peripheral part of a sample is increased much stronger than through the central part. The observed increase of low-field current on relative humidity is explained by the decrease of the barrier height. The estimations of the lowering of the barrier height in a humid air is performed using the suggested models.

  14. Analysis of Building Envelope Insulation Performance Utilizing Integrated Temperature and Humidity Sensors

    Directory of Open Access Journals (Sweden)

    Shih-Wei Chen

    2012-06-01

    Full Text Available A major cause of high energy consumption for air conditioning in indoor spaces is the thermal storage characteristics of a building’s envelope concrete material; therefore, the physiological signals (temperature and humidity within concrete structures are an important reference for building energy management. The current approach to measuring temperature and humidity within concrete structures (i.e., thermocouples and fiber optics is limited by problems of wiring requirements, discontinuous monitoring, and high costs. This study uses radio frequency integrated circuits (RFIC combined with temperature and humidity sensors (T/H sensors for the design of a smart temperature and humidity information material (STHIM that automatically, regularly, and continuously converts temperature and humidity signals within concrete and transmits them by radio frequency (RF to the Building Physiology Information System (BPIS. This provides a new approach to measurement that incorporates direct measurement, wireless communication, and real-time continuous monitoring to assist building designers and users in making energy management decisions and judgments.

  15. 提高多孔硅传感特性的一种新方法%A New Method For Improving Sensing Characteristics of Porous Silicon

    Institute of Scientific and Technical Information of China (English)

    李宏建; 崔昊杨; 黄伯云; 易丹青; 何英旋; 彭景翠

    2004-01-01

    The luminescence quenching effect of porous Si caused by adsorbing organic moleculars are investigated. It indicates that the solvent molecules of quenching luminescence are polarized molecules and the different polarity determines the different quenching, and the quenching caused by molecules absorbed of oxide porous Si has better reversibility and selectivity than that of porous Si. By using n-butylamine as carbon resource, carbon-nitrogen (c-n) film was deposited on the p-n junction(p- n) porous Si surface by means of a radio-frequency glow discharge plasma system. Electroluminescence (EL) intensity enhancement and EL peak blueshift of the passivated porous Si are observed experimentally. Further, the intensity decay and the peak blueshift of porous Si are not observed after storing 60 days in the atmosphere. The current-voltage characteristics show that the series resistance Rs and driven voltage in the ITO/cn/p-n porous Si diode is reduced greatly compared with the ITO/p-n porous Si diode. It provides a new method for improving sensing characteristics of porous Si.%研究了多孔硅(PS)吸附有机溶剂分子后对多孔硅荧光谱的淬灭效应.结果表明:淬灭多孔硅发光的有机溶剂分子是极性分子,有机溶剂分子的极性不同对多孔硅发光的淬灭程度也不同,且有些有机溶剂分子吸附氧化多孔硅比吸附多孔硅引起的发光淬灭具有更好的可逆性和选择性;用含有胺基的正丁胺(CH3CH2CH2CH2-NH2)作碳源,用射频辉光放电等离子系统在多孔硅表面沉积c-n膜对多孔硅进行钝化处理后发现:其电致发光强度明显增强,发光峰位兰移,且在大气中存放60天后,其电致发光谱强度基本不衰减,峰位不再移动.经钝化处理的器件较未经处理的器件具有小的串联电阻R和低的驱动电压.这为提高多孔硅的传感特性提供了一种新方法.

  16. Positive impedance humidity sensors via single-component materials.

    Science.gov (United States)

    Qian, Jingwen; Peng, Zhijian; Shen, Zhenguang; Zhao, Zengying; Zhang, Guoliang; Fu, Xiuli

    2016-05-06

    Resistivity-type humidity sensors have been investigated with great interest due to the increasing demands in industry, agriculture and daily life. To date, most of the available humidity sensors have been fabricated based on negative humidity impedance, in which the electrical resistance decreases as the humidity increases, and only several carbon composites have been reported to present positive humidity impedance. However, here we fabricate positive impedance humidity sensors only via single-component WO3-x crystals. The resistance of WO3-x crystal sensors in response to relative humidity could be tuned from a negative to positive one by increasing the compositional x. And it was revealed that the positive humidity impedance was driven by the defects of oxygen vacancy. This result will extend the application field of humidity sensors, because the positive humidity impedance sensors would be more energy-efficient, easier to be miniaturized and electrically safer than their negative counterparts for their lower operation voltages. And we believe that constructing vacancies in semiconducting materials is a universal way to fabricate positive impedance humidity sensors.

  17. Positive impedance humidity sensors via single-component materials

    Science.gov (United States)

    Qian, Jingwen; Peng, Zhijian; Shen, Zhenguang; Zhao, Zengying; Zhang, Guoliang; Fu, Xiuli

    2016-05-01

    Resistivity-type humidity sensors have been investigated with great interest due to the increasing demands in industry, agriculture and daily life. To date, most of the available humidity sensors have been fabricated based on negative humidity impedance, in which the electrical resistance decreases as the humidity increases, and only several carbon composites have been reported to present positive humidity impedance. However, here we fabricate positive impedance humidity sensors only via single-component WO3-x crystals. The resistance of WO3-x crystal sensors in response to relative humidity could be tuned from a negative to positive one by increasing the compositional x. And it was revealed that the positive humidity impedance was driven by the defects of oxygen vacancy. This result will extend the application field of humidity sensors, because the positive humidity impedance sensors would be more energy-efficient, easier to be miniaturized and electrically safer than their negative counterparts for their lower operation voltages. And we believe that constructing vacancies in semiconducting materials is a universal way to fabricate positive impedance humidity sensors.

  18. Effects of low humidity on the rat middle ear.

    Science.gov (United States)

    Lovejoy, H M; McGuirt, W F; Ayres, P H; Hayes, A W; Coggins, C R; Sagartz, J

    1994-09-01

    Secretory otitis media is common in the winter, and the possible risk factors are numerous. This study examines the effect of low humidity on the middle ear using a Sprague-Dawley rat model: 23 test rats housed for 5 days in a low-humidity environment (10% to 12% relative humidity) and 23 control rats housed at 50% to 55% relative humidity. Microscopic ear examinations were graded for otitis media with effusion (OME) before testing and on test days 3 and 5. The mucosa of the middle ears and eustachian tubes was examined histopathologically. Significantly more effusions were observed in the low-humidity group on test days 3 (P = .003) and 5 (P = .01), but no intergroup histopathologic differences were noted. We conclude that a low-humidity environment contributed to the development of OME in the test animals, and that low-humidity warrants further investigation as a contributing factor in childhood middle ear disease.

  19. Reduced graphene oxide decorated with Fe doped SnO2 nanoparticles for humidity sensor

    Science.gov (United States)

    Toloman, D.; Popa, A.; Stan, M.; Socaci, C.; Biris, A. R.; Katona, G.; Tudorache, F.; Petrila, I.; Iacomi, F.

    2017-04-01

    Reduced graphene oxide (rGO) decorated with Fe doped SnO2 nanoparticles were fabricated via the electrostatic interaction between positively charged modified Fe-doped SnO2 oxide and negatively charged graphene oxide (GO) in the presence of poly(allylamine) hydrochloride (PAH). The decoration of rGO layers with SnO2:Fe nanoparticles was highlited by TEM microsopy. For composite sample the diffraction patterns coincide well with those of SnO2:Fe nanoparticles. The reduction of graphene oxide was evidenced using XRD and FT-IR spectroscopy. The formation of SnO2:Fe-PAH-graphene composites was confirmed by FT-IR, Raman and EPR spectroscopy. Sensitivity tests for relative humidity (RH) measurements were carried out at five different concentrations of humid air at room temperature. The prepared composite sensor exhibited a higher sensing response as compared with Fe:SnO2 nanoparticles.

  20. Remote Sensing

    CERN Document Server

    Khorram, Siamak; Koch, Frank H; van der Wiele, Cynthia F

    2012-01-01

    Remote Sensing provides information on how remote sensing relates to the natural resources inventory, management, and monitoring, as well as environmental concerns. It explains the role of this new technology in current global challenges. "Remote Sensing" will discuss remotely sensed data application payloads and platforms, along with the methodologies involving image processing techniques as applied to remotely sensed data. This title provides information on image classification techniques and image registration, data integration, and data fusion techniques. How this technology applies to natural resources and environmental concerns will also be discussed.

  1. Cross-sensitivity of metal oxide gas sensor to ambient temperature and humidity: Effects on gas distribution mapping

    Science.gov (United States)

    Kamarudin, K.; Bennetts, V. H.; Mamduh, S. M.; Visvanathan, R.; Yeon, A. S. A.; Shakaff, A. Y. M.; Zakaria, A.; Abdullah, A. H.; Kamarudin, L. M.

    2017-03-01

    Metal oxide gas sensors have been widely used in robotics application to perform remote and mobile gas sensing. However, previous researches have indicated that this type of sensor technology is cross-sensitive to environmental temperature and humidity. This paper therefore investigates the effects of these two factors towards gas distribution mapping and gas source localization domains. A mobile robot equipped with TGS2600 gas sensor was deployed to build gas distribution maps of indoor environment, where the temperature and humidity varies. The results from the trials in environment with and without gas source indicated that there is a strong relation between the fluctuation of the mean and variance map with respect to the variations in the temperature and humidity maps.

  2. Relative humidity sensor based on surface plasmon resonance of D-shaped fiber with polyvinyl alcohol embedding Au grating

    Science.gov (United States)

    Yan, Haitao; Han, Daofu; Li, Ming; Lin, Bo

    2017-01-01

    This paper presents the design, fabrication, and characterization of a D-shaped fiber coated with polyvinyl alcohol (PVA) embedding an Au grating-based relative humidity (RH) sensor. The Au grating is fabricated on a D-shaped fiber to match the wave-vector and excite the surface plasmon, and the PVA is embedded in the Au grating as a sensitive cladding film. The refractive index of PVA changes with the ambient humidity. Measurements in a controlled environment show that the RH sensor can achieve a sensitivity of 5.4 nm per relative humidity unit in the RH range from 0% to 70% RH. Moreover, the surface plasmon resonance can be realized and used for RH sensing at the C band of optical fiber communication instead of the visible light band due to the metallic grating microstructure on the D-shaped fiber.

  3. Sensitivity of moist convection to environmental humidity

    Science.gov (United States)

    Derbyshire, S. H.; Beau, I.; Bechtold, P.; Grandpeix, J.-Y.; Piriou, J.-M.; Redelsperger, J. L.; Soares, P. M. M.

    2004-10-01

    As part of the EUROCS (EUROpean Cloud Systems study) project, cloud-resolving model (CRM) simulations and parallel single-column model (SCM) tests of the sensitivity of moist atmospheric convection to mid-tropospheric humidity are presented. This sensitivity is broadly supported by observations and some previous model studies, but is still poorly quantified. Mixing between clouds and environment is a key mechanism, central to many of the fundamental differences between convection schemes. Here, we define an idealized quasi-steady 'testbed', in which the large-scale environment is assumed to adjust the local mean profiles on a timescale of one hour. We then test sensitivity to the target profiles at heights above 2 km. Two independent CRMs agree reasonably well in their response to the different background profiles and both show strong deep precipitating convection in the more moist cases, but only shallow convection in the driest case. The CRM results also appear to be numerically robust. All the SCMs, most of which are one-dimensional versions of global climate models (GCMs), show sensitivity to humidity but differ in various ways from the CRMs. Some of the SCMs are improved in the light of these comparisons, with GCM improvements documented elsewhere.

  4. Energy from humid air. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Oliver, T.K.; Groves, W.N.; Gruber, C.L.; Cheung, A.

    1979-02-01

    Results to date are presented for a research project which is in progress at the South Dakota School of Mines and Technology. The goal of the research is to find a cost-effective process to convert the energy in humid air into mechanical work, which will be used to drive an electrical generator. The research is being carried out by computer modeling. Results for a natural draft tower show that it is not a cost-effective way to get energy from humid air. Parametric studies are presented for expansion-compression cycles. With suitable conditions, including large amounts of cooling during compression, this cycle has an attractive net work output. To avoid using all the output power to overcome machine losses, it appears necessary to use a one-machine mechanization. The most promising uses vortex flow to achieve the necessary expansion and subsequent compression with cooling. Power output and costs have been estimated for a vortex plant located in Puerto Rico.

  5. Ferroelectric KNbO3 nanofibers: synthesis, characterization and their application as a humidity nanosensor

    Science.gov (United States)

    Ganeshkumar, Rajasekaran; Sopiha, Kostiantyn V.; Wu, Ping; Cheah, Chin Wei; Zhao, Rong

    2016-09-01

    By virtue of its non-toxicity, high T c, and non-linear optical and ferroelectric properties, one-dimensional (1D) potassium niobate (KNbO3) may enable the development of numerous nanoscale devices. Despite the progress in 1D perovskite materials, preparing high aspect ratio KNbO3 nanostructures is still a concern. This report presents the successful synthesis of ultra-long KNbO3 nanofibers using a simple sol-gel assisted far-field electrospinning process. At optimized conditions, centimeters long, orthorhombic KNbO3 nanofibers with an average diameter of 100 nm have been obtained. The nanofibers are composed of uniform grains densely stacked along the direction of the nanofiber axis. Due to large surface-volume ratio, a high sensitive humidity nanosensor based on KNbO3 nanofibers displaying a logarithmic-linear dependence behavior of the conductance with the relative humidity (RH) was demonstrated. The conductance increases dramatically from 10-10 ℧ to 10-6 ℧ while RH varies from 15% to 95% at room temperature. In addition, the nanosensor exhibits excellent sensing performance, including ultrafast response (≤2 s) and recovery times (≤10 s), good linearity and reproducibility. Furthermore, the change in ferroelectric coercivity with respect to the RH and its effect in the sensing behavior were unveiled. This work could enable broad applications in the fields of environmental sensing and nano-electrical-mechanical systems.

  6. Study on Teaching Methodology for Remote Sensing based on Characteristic Key Subjects in Guizhou%贵州特色重点学科中的遥感课程教学改革研究

    Institute of Scientific and Technical Information of China (English)

    李松; 邓宝昆

    2014-01-01

    This paper discussed a teaching methodology for remote sensing to environmental specialty of Characteristic Key Subjects in Guizhou from both contents and methodology, aimed at those who are not major in remote sensing. Integrated subject orientation analysis of remote sensing and education of applied talents, this paper developed a 2+1 remote sensing teaching modes for aspects including technology and science views. Here 1 was the aim of education of applied talents, and 2 means that teaching of remote sensing which could be developed from views of technology and science views. Consequentially,integrated use of multi-approach based on multimedia and multi-method could improve teaching effect obviously. Finally, we gained experience in the practices of teaching.%基于贵州师范学院的贵州省环境特色重点学科平台,从教学内容和方法方面讨论非遥感专业的遥感课程教学方法。结合遥感学科定位和区域应用型人才培养目标,从理论和技术层面提出遥感课程“2+1”教学模式,“1”即围绕应用型人才培养目标,“2”是从理论和技术两方面进行教学设计。基于遥感的课程特点,以多媒体为核心的多手段教学,以及多教学方法的有效探索,有助于增强教学效果,也为遥感和GIS教学改革积累宝贵的经验。

  7. High Temperature Convective Drying of a Packed Bed with Humid Air at Different Humidities

    Directory of Open Access Journals (Sweden)

    J. Sghaier

    2009-01-01

    Full Text Available Problem statement: Drying a packed bed of porous particle at high temperature with varying humidity of hot air is an attractive process. Despite, many researches on experimental and simulation on a fixed bed drying at low and average temperature are proposed. Few studies showed drying at high temperature with humid air or using superheated steam. The latest is compared to dry air. Approach: In this study, we show an experimental and numerical study of humid air drying of a fixed bed of moist porous alumina particles. The air velocity, the air temperature and the vapor pressure were varied from 1.7-2.3 m.sec-1, 120-160°C and 0.1-0.65 bar, respectively and the experiments were performed at atmospheric pressure. Then a mathematical describing heat and mass transfer during drying is developed. This model is based on the averaging volume approach using two scale changes. Results: From the experimental works, the solid temperature and the bed moisture content have been presented at different drying conditions. The previous results show that an increase in humidity leads to an increase of the wet bulb temperature and a decrease in the drying time. At the same drying temperature, the variation in the gas velocity affects also the drying time. In addition, we note that the drying time increases if the bed depth increases. The predicted results deduced from the developed model were compared with the experiment. Conclusion: The experimental and predicted results obtained from this study describing drying of a packed bed illustrate clearly the effect of the air humidity on the drying kinetics.

  8. Humidity versus photo-stability of metal halide perovskite films in a polymer matrix.

    Science.gov (United States)

    Manshor, Nurul Ain; Wali, Qamar; Wong, Ka Kan; Muzakir, Saifful Kamaluddin; Fakharuddin, Azhar; Schmidt-Mende, Lukas; Jose, Rajan

    2016-08-21

    Despite the high efficiency of over 21% reported for emerging thin film perovskite solar cells, one of the key issues prior to their commercial deployment is to attain their long term stability under ambient and outdoor conditions. The instability in perovskite is widely conceived to be humidity induced due to the water solubility of its initial precursors, which leads to decomposition of the perovskite crystal structure; however, we note that humidity alone is not the major degradation factor and it is rather the photon dose in combination with humidity exposure that triggers the instability. In our experiment, which is designed to decouple the effect of humidity and light on perovskite degradation, we investigate the shelf-lifetime of CH3NH3PbI3 films in the dark and under illumination under high humidity conditions (Rel. H. > 70%). We note minor degradation in perovskite films stored in a humid dark environment whereas upon exposure to light, the films undergo drastic degradation, primarily owing to the reactive TiO2/perovskite interface and also the surface defects of TiO2. To enhance its air-stability, we incorporate CH3NH3PbI3 perovskite in a polymer (poly-vinylpyrrolidone, PVP) matrix which retained its optical and structural characteristics in the dark for ∼2000 h and ∼800 h in room light soaking, significantly higher than a pristine perovskite film, which degraded completely in 600 h in the dark and in less than 100 h when exposed to light. We attribute the superior stability of PVP incorporated perovskite films to the improved structural stability of CH3NH3PbI3 and also to the improved TiO2/perovskite interface upon incorporating a polymer matrix. Charge injection from the polymer embedded perovskite films has also been confirmed by fabricating solar cells using them, thereby providing a promising future research pathway for stable and efficient perovskite solar cells.

  9. Glucose Sensing

    CERN Document Server

    Geddes, Chris D

    2006-01-01

    Topics in Fluorescence Spectroscopy, Glucose Sensing is the eleventh volume in the popular series Topics in Fluorescence Spectroscopy, edited by Drs. Chris D. Geddes and Joseph R. Lakowicz. This volume incorporates authoritative analytical fluorescence-based glucose sensing reviews specialized enough to be attractive to professional researchers, yet also appealing to the wider audience of scientists in related disciplines of fluorescence. Glucose Sensing is an essential reference for any lab working in the analytical fluorescence glucose sensing field. All academics, bench scientists, and industry professionals wishing to take advantage of the latest and greatest in the continuously emerging field of glucose sensing, and diabetes care & management, will find this volume an invaluable resource. Topics in Fluorescence Spectroscopy Volume 11, Glucose Sensing Chapters include: Implantable Sensors for Interstitial Fluid Smart Tattoo Glucose Sensors Optical Enzyme-based Glucose Biosensors Plasmonic Glucose Sens...

  10. High-Sensitivity and Low-Hysteresis Porous MIM-Type Capacitive Humidity Sensor Using Functional Polymer Mixed with TiO2 Microparticles

    Science.gov (United States)

    Liu, Ming-Qing; Wang, Cong; Kim, Nam-Young

    2017-01-01

    In this study, a high-sensitivity and low-hysteresis porous metal–insulator–metal-type capacitive humidity sensor is investigated using a functional polymer mixed with TiO2 microparticles. The humidity sensor consists of an optimally designed porous top electrode, a functional polymer humidity sensitive layer, a bottom electrode, and a glass substrate. The porous top electrode is designed to increase the contact area between the sensing layer and water vapor, leading to high sensitivity and quick response time. The functional polymer mixed with TiO2 microparticles shows excellent hysteresis under a wide humidity-sensing range with good long-term stability. The results show that as the relative humidity ranges from 10% RH to 90% RH, the proposed humidity sensor achieves a high sensitivity of 0.85 pF/% RH and a fast response time of less than 35 s. Furthermore, the sensor shows an ultra-low hysteresis of 0.95% RH at 60% RH, a good temperature dependence, and a stable capacitance value with a maximum of 0.17% RH drift during 120 h of continuous test. PMID:28157167

  11. A novel humidity sensor based on NH2-MIL-125(Ti) metal organic framework with high responsiveness

    Science.gov (United States)

    Zhang, Ying; Chen, Yu; Zhang, Yupeng; Cong, Huahua; Fu, Bo; Wen, Shanpeng; Ruan, Shengping

    2013-10-01

    A novel porous nanosized humidity-sensing material of amine-functionalized titanium metal organic framework (MOF), NH2-MIL-125(Ti), was investigated. NH2-MIL-125(Ti) nanoparticles with high phase purity and good physicochemical property were synthesized by a simple hydrothermal method. The nanosized MOF was characterized by X-ray diffraction and scanning electron microscope. The average size of the MOF nanoparticles is around 300 nm. Then NH2-MIL-125(Ti) humidity sensor was fabricated by coating the nanosized materials on interdigitated electrodes. The humidity sensor based on NH2-MIL-125(Ti) shows good linearity of RH (11-95 % RH), as well as fast response and recovery time. The RH detecting range is from 11 to 95 % RH at 100 Hz. The response and recovery time are about 45 and 50 s, respectively. Moreover, the sensing mechanism was discussed by complex impedance analysis in detail. These results indicate the potential application of NH2-MIL-125(Ti) in humidity sensors.

  12. Trehalose in hair care: heat styling benefits at high humidity.

    Science.gov (United States)

    Pye, Susan; Paul, Prem K C

    2012-01-01

    Human hair switches that have been treated with trehalose solution and straightened using hot irons show longevity of the straight style even in high-humidity conditions. This anti-humidity benefit is especially noticeable if the straight style has been created at low relative humidity. It is proposed that hot-iron straightening of trehalose-treated switches produces in situ glassy forms of the sugar that act as water sinks at high humidity to provide anti-humidity benefits. Adsorption isotherms and powder x-ray studies of different forms of trehalose and moisture uptake of hair treated with the sugar suggest that the ability of a glassy form of trehalose to regulate moisture in the fiber and consequently affect its viscoelastic properties is a major factor in providing long-lasting straight style in humid conditions.

  13. The influence of humidity fluxes on offshore wind speed profiles

    Directory of Open Access Journals (Sweden)

    R. J. Barthelmie

    2010-05-01

    Full Text Available Wind energy developments offshore focus on larger turbines to keep the relative cost of the foundation per MW of installed capacity low. Hence typical wind turbine hub-heights are extending to 100 m and potentially beyond. However, measurements to these heights are not usually available, requiring extrapolation from lower measurements. With humid conditions and low mechanical turbulence offshore, deviations from the traditional logarithmic wind speed profile become significant and stability corrections are required. This research focuses on quantifying the effect of humidity fluxes on stability corrected wind speed profiles. The effect on wind speed profiles is found to be important in stable conditions where including humidity fluxes forces conditions towards neutral. Our results show that excluding humidity fluxes leads to average predicted wind speeds at 150 m from 10 m which are up to 4% higher than if humidity fluxes are included, and the results are not very sensitive to the method selected to estimate humidity fluxes.

  14. 负载敏感变量泵稳态特性研究%Steady State Characteristic Analysis of the Load-sensing Pump

    Institute of Scientific and Technical Information of China (English)

    来升; 穆希辉; 杜峰坡; 师永强; 赵亮亮

    2011-01-01

    The mathematical model of the load-sensing system was built. The operating point of the load-sensing system with a critical center spool of the load-sensing regulator was determined by three conditions. As condition I, the load-sensing regulator spool displacement XLsiS always at the null position for the load-sensing regulator with a critically lapped spool. Under condition Ⅱ, the control pressure Py and the pump pressure pp are the same. This would occur when the system pressure differential setting ΔPSET and the load pressure pLare small. Under condition III, The demand flow is larger than the supply flow by the load-sensing pump. Condition I is the “normal” operation condition. Conditions II and III should be avoided in practice.%建立负荷传感系统稳态时的数学模型,并通过研究得出负荷传感系统存在3种稳定状态:在状态I,敏感阀阀芯位移x=0,负荷传感系统工作正常;在状态Ⅱ,x=0,排量控制油缸腔体内的控制压力P,和泵出口的压力P相等,此时敏感阀的设定压差值△p盯和负载压力p均比较低,系统处于不稳定工作状态;在状态Ⅲ,x<0,负载所需流量大于泵提供的流量,泵满排量供油,此时系统虽处于稳定状态,但负载敏感阀控制不起作用.在设计和使用中,应避免负荷传感系统工作在状态Ⅱ和状态Ⅲ.

  15. Temperature compensated, humidity insensitive, high-Tg TOPAS FBGs for accelerometers and microphones

    DEFF Research Database (Denmark)

    Stefani, Alessio; Yuan, W.; Markos, C.;

    2012-01-01

    In this paper we present our latest work on Fiber Bragg Gratings (FBGs) in microstructured polymer optical fibers (mPOFs) and their application as strain sensing transducers in devices, such as accelerometers and microphones. We demonstrate how the cross-sensitivity of the FBG to temperature...... is eliminated by using dual-FBG technology and how mPOFs fabricated from different grades of TOPAS with glass transition temperatures around 135 degrees C potentially allow high-temperature humidity insensitive operation. The results bring the mPOF FBG closer to being a viable technology for commercial...

  16. Building Environment Analysis based on Temperature and Humidity for Smart Energy Systems

    Science.gov (United States)

    Yun, Jaeseok; Won, Kwang-Ho

    2012-01-01

    In this paper, we propose a new HVAC (heating, ventilation, and air conditioning) control strategy as part of the smart energy system that can balance occupant comfort against building energy consumption using ubiquitous sensing and machine learning technology. We have developed ZigBee-based wireless sensor nodes and collected realistic temperature and humidity data during one month from a laboratory environment. With the collected data, we have established a building environment model using machine learning algorithms, which can be used to assess occupant comfort level. We expect the proposed HVAC control strategy will be able to provide occupants with a consistently comfortable working or home environment. PMID:23202004

  17. Building Environment Analysis Based on Temperature and Humidity for Smart Energy Systems

    Directory of Open Access Journals (Sweden)

    Kwang-Ho Won

    2012-10-01

    Full Text Available In this paper, we propose a new HVAC (heating, ventilation, and air conditioning control strategy as part of the smart energy system that can balance occupant comfort against building energy consumption using ubiquitous sensing and machine learning technology. We have developed ZigBee-based wireless sensor nodes and collected realistic temperature and humidity data during one month from a laboratory environment. With the collected data, we have established a building environment model using machine learning algorithms, which can be used to assess occupant comfort level. We expect the proposed HVAC control strategy will be able to provide occupants with a consistently comfortable working or home environment.

  18. Effects of Absolute Humidity on Flashover Voltage of Insulators

    Science.gov (United States)

    Fujii, Osamu; Hidaka, Kazuhiro; Mizuno, Yukio; Naito, Katsuhiko; Irie, Takashi; Nishikawa, Morio

    Effect of humidity on flashover voltage of three kinds of insulators is experimentally studied for about three years under natural humidity condition. It is found that the existing IEC humidity correction seems to be proper for most insulators regardless of the kinds of applied voltage but that change may be necessary for a cap and pin insulator unit under the application of positive and negative lightning impulse voltages.

  19. Roles of humidity and temperature in shaping influenza seasonality.

    Science.gov (United States)

    Lowen, Anice C; Steel, John

    2014-07-01

    Experimental studies in guinea pigs demonstrated that influenza virus transmission is strongly modulated by temperature and humidity. A number of epidemiological studies have followed up on these findings and revealed robust associations between influenza incidence in temperate regions and local conditions of humidity and temperature, offering a long-awaited explanation for the wintertime seasonality of influenza in these locales. Despite recent progress, important questions remain as to the mechanism(s) by which humidity and/or temperature affects transmission.

  20. Thermal conductivity at different humidity conditions

    DEFF Research Database (Denmark)

    Kristiansen, Finn Harken; Rode, Carsten

    1999-01-01

    The thermal conductivity (the l-value) of several alternative insulation products and a traditional product is determined under different humidity conditions in a specially constructed hot plate apparatus.The hot plate apparatus is constructed with an air gap on each side of the test specimen where...... humidified air can pass. Thus, it is possible to build up different degrees of moisture on each side of the test specimen.The thermal conductivity is determined for the following types of alternative insulation: sheep's wool, flax, paper insulation, perlite and mineral wool. The insulation products were...... by an accumulation of moisture as condensation in the parts of the insulation that lie immediately close to the cold side of the apparatus. The high l-values found are therefore of no practical importance in structures where no condensation occurs. Disregarding these condensation situations, the maximum increase...

  1. Electric Field and Humidity Trigger Contact Electrification

    Directory of Open Access Journals (Sweden)

    Yanzhen Zhang

    2015-01-01

    Full Text Available Here, we study the old problem of why identical insulators can charge one another on contact. We perform several experiments showing that, if driven by a preexisting electric field, charge is transferred between contacting insulators. This transfer happens because the insulator surfaces adsorb small amounts of water from a humid atmosphere. We believe the electric field then separates positively from negatively charged ions prevailing within the water, which we believe to be hydronium and hydroxide ions, such that at the point of contact, positive ions of one insulator neutralize negative ions of the other one, charging both of them. This mechanism can explain for the first time the observation made four decades ago that wind-blown sand discharges in sparks if and only if a thunderstorm is nearby.

  2. Thermal conductivity at different humidity conditions

    DEFF Research Database (Denmark)

    Kristiansen, Finn Harken; Rode, Carsten

    1999-01-01

    humidified air can pass. Thus, it is possible to build up different degrees of moisture on each side of the test specimen.The thermal conductivity is determined for the following types of alternative insulation: sheep's wool, flax, paper insulation, perlite and mineral wool. The insulation products were......The thermal conductivity (the l-value) of several alternative insulation products and a traditional product is determined under different humidity conditions in a specially constructed hot plate apparatus.The hot plate apparatus is constructed with an air gap on each side of the test specimen where...... Ekofiber Vind, Herawool (without support fibres), Heraflax, Isodan with and without salts, Miljø Isolering with and without salts, Perlite (water-repellent), and Rockwool A-batts for comparison.All measurements of the materials started with no affection of moisture. Nevertheless, results were achieved...

  3. Thermal Comfort and Optimum Humidity Part 1

    Directory of Open Access Journals (Sweden)

    M. V. Jokl

    2002-01-01

    Full Text Available The hydrothermal microclimate is the main component in indoor comfort. The optimum hydrothermal level can be ensured by suitable changes in the sources of heat and water vapor within the building, changes in the environment (the interior of the building and in the people exposed to the conditions inside the building. A change in the heat source and the source of water vapor involves improving the heat - insulating properties and the air permeability of the peripheral walls and especially of the windows. The change in the environment will bring human bodies into balance with the environment. This can be expressed in terms of an optimum or at least an acceptable globe temperature, an adequate proportion of radiant heat within the total amount of heat from the environment (defined by the difference between air and wall temperature, uniform cooling of the human body by the environment, defined a by the acceptable temperature difference between head and ankles, b by acceptable temperature variations during a shift (location unchanged, or during movement from one location to another without a change of clothing. Finally, a moisture balance between man and the environment is necessary (defined by acceptable relative air humidity. A change for human beings means a change of clothes which, of course, is limited by social acceptance in summer and by inconvenient heaviness in winter. The principles of optimum heating and cooling, humidification and dehumidification are presented in this paper.Hydrothermal comfort in an environment depends on heat and humidity flows (heat and water vapors, occurring in a given space in a building interior and affecting the total state of the human organism.

  4. Thermal Comfort and Optimum Humidity Part 2

    Directory of Open Access Journals (Sweden)

    M. V. Jokl

    2002-01-01

    Full Text Available The hydrothermal microclimate is the main component in indoor comfort. The optimum hydrothermal level can be ensured by suitable changes in the sources of heat and water vapor within the building, changes in the environment (the interior of the building and in the people exposed to the conditions inside the building. A change in the heat source and the source of water vapor involves improving the heat - insulating properties and the air permeability of the peripheral walls and especially of the windows. The change in the environment will bring human bodies into balance with the environment. This can be expressed in terms of an optimum or at least an acceptable globe temperature, an adequate proportion of radiant heat within the total amount of heat from the environment (defined by the difference between air and wall temperature, uniform cooling of the human body by the environment, defined a by the acceptable temperature difference between head and ankles, b by acceptable temperature variations during a shift (location unchanged, or during movement from one location to another without a change of clothing. Finally, a moisture balance between man and the environment is necessary (defined by acceptable relative air humidity. A change for human beings means a change of clothes which, of course, is limited by social acceptance in summer and by inconvenient heaviness in winter. The principles of optimum heating and cooling, humidification and dehumidification are presented in this paper.Hydrothermal comfort in an environment depends on heat and humidity flows (heat and water vapors, occurring in a given space in a building interior and affecting the total state of the human organism.

  5. The Canopy Conductance of a Humid Grassland

    Science.gov (United States)

    Lu, C. T.; Hsieh, C. I.

    2015-12-01

    Penman-Monteith equation is widely used for estimating latent heat flux. The key parameter for implementing this equation is the canopy conductance (gc). Recent research (Blaken and Black, 2004) showed that gc could be well parameterized by a linear function of An/ (D0* X0c), where An represents net assimilation, D0 is leaf level saturation deficit, and X0c is CO2 mole fraction. In this study, we tried to use the same idea for estimating gcfor a humid grassland. The study site was located in County Cork, southwest Ireland (51o59''N 8o46''W), and perennial ryegrass (Lolium perenne L.) was the dominant grass species in this area. An eddy covariance system was used to measure the latent heat flux above this humid grassland. The measured gc was calculated by rearranging Penman-Monteith equation combined with the measured latent heat flux. Our data showed that the gc decreased as the vapor pressure deficit and temperature increased. And it increased as the net radiation increased. Therefore, we found out that the best parameterization of gc was a linear function of the product of the vapor deficit, temperature, and net radiation. Also, we used the gc which was estimated by this linear function to predict the latent heat flux by Penman-Monteith equation and compared the predictions with those where the gc was chosen to be a fixed value. Our analysis showed that this simple linear function for gc can improve the latent heat flux predictions (R square increased from 0.48 to 0.66).

  6. Homogenization of global radiosonde humidity data

    Science.gov (United States)

    Blaschek, Michael; Haimberger, Leopold

    2016-04-01

    The global radiosonde network is an important source of upper-air measurements and is strongly connected to reanalysis efforts of the 20th century. However, measurements are strongly affected by changes in the observing system and require a homogenization before they can be considered useful in climate studies. In particular humidity measurements are known to show spurious trends and biases induced by many sources, e.g. reporting practices or freezing of the sensor. We propose to detect and correct these biases in an automated way, as has been done with temperature and winds. We detect breakpoints in dew point depression (DPD) time series by employing a standard normal homogeneity test (SNHT) on DPD-departures from ERA-Interim. In a next step, we calculate quantile departures between the latter and the earlier part near the breakpoints of the time series, going back in time. These departures adjust the earlier distribution of DPD to the latter distribution, called quantile matching, thus removing for example a non climatic shift. We employ this approach to the existing radiosonde network. In a first step to verify our approach we compare our results with ERA-Interim data and brightness temperatures of humidity-sensitive channels of microwave measuring radiometers (SSMIS) onboard DMSP F16. The results show that some of the biases can be detected and corrected in an automated way, however large biases that impact the distribution of DPD values originating from known reporting practices (e.g. 30 DPD on US stations) remain. These biases can be removed but not corrected. The comparison of brightness temperatures from satellite and radiosondes proofs to be difficult as large differences result from for example representative errors.

  7. Attribution of observed surface humidity changes to human influence.

    Science.gov (United States)

    Willett, Katharine M; Gillett, Nathan P; Jones, Philip D; Thorne, Peter W

    2007-10-11

    Water vapour is the most important contributor to the natural greenhouse effect, and the amount of water vapour in the atmosphere is expected to increase under conditions of greenhouse-gas-induced warming, leading to a significant feedback on anthropogenic climate change. Theoretical and modelling studies predict that relative humidity will remain approximately constant at the global scale as the climate warms, leading to an increase in specific humidity. Although significant increases in surface specific humidity have been identified in several regions, and on the global scale in non-homogenized data, it has not been shown whether these changes are due to natural or human influences on climate. Here we use a new quality-controlled and homogenized gridded observational data set of surface humidity, with output from a coupled climate model, to identify and explore the causes of changes in surface specific humidity over the late twentieth century. We identify a significant global-scale increase in surface specific humidity that is attributable mainly to human influence. Specific humidity is found to have increased in response to rising temperatures, with relative humidity remaining approximately constant. These changes may have important implications, because atmospheric humidity is a key variable in determining the geographical distribution and maximum intensity of precipitation, the potential maximum intensity of tropical cyclones, and human heat stress, and has important effects on the biosphere and surface hydrology.

  8. Do honeybees, Apis mellifera scutellata, regulate humidity in their nest?

    Science.gov (United States)

    Human, Hannelie; Nicolson, Sue W.; Dietemann, Vincent

    2006-08-01

    Honeybees are highly efficient at regulating the biophysical parameters of their hive according to colony needs. Thermoregulation has been the most extensively studied aspect of nest homeostasis. In contrast, little is known about how humidity is regulated in beehives, if at all. Although high humidity is necessary for brood development, regulation of this parameter by honeybee workers has not yet been demonstrated. In the past, humidity was measured too crudely for a regulation mechanism to be identified. We reassess this issue, using miniaturised data loggers that allow humidity measurements in natural situations and at several places in the nest. We present evidence that workers influence humidity in the hive. However, there are constraints on potential regulation mechanisms because humidity optima may vary in different locations of the nest. Humidity could also depend on variable external factors, such as water availability, which further impair the regulation. Moreover, there are trade-offs with the regulation of temperature and respiratory gas exchanges that can disrupt the establishment of optimal humidity levels. As a result, we argue that workers can only adjust humidity within sub-optimal limits.

  9. Effects of temperature and humidity during irradiation on the response of a film dosimeter

    Science.gov (United States)

    Khan, Hasan M.; Wahid, Mian S.

    1995-09-01

    A commercially available leuco dye containing polyvinyl butyral based film (FWT-63-02) has been investigated ctrophotometrically for its dosimetric characteristic and for its use as routine dosimeter in radiation processing for the absorbed dose range 0.1 to 10 kGy. The present study was carried out to evaluate the performance of dosimeter under different environmental conditions (i.e. effects of temperature and relative humidity during irradiation). The response was measured at peak wavelength of 600 nm as well as at a number of other wavelengths (550, 625, 640 and 650 nm). The dosimeter was found to show quite stable response up to a radiation chamber temperature of 40°C. The dosimeter also showed stable behavior at low or moderate relative humidity conditions (<76%) in the radiation chamber. The characteristics of the dosimeter are suitable for its possible application in radiation processing, food irradiation and sterilization applications.

  10. Environmental dust effects on aluminum surfaces in humid air ambient

    Science.gov (United States)

    Yilbas, Bekir Sami; Hassan, Ghassan; Ali, Haider; Al-Aqeeli, Nasser

    2017-01-01

    Environmental dusts settle on surfaces and influence the performance of concentrated solar energy harvesting devices, such as aluminum troughs. The characteristics of environmental dust and the effects of mud formed from the dust particles as a result of water condensing in humid air conditions on an aluminum wafer surface are examined. The dissolution of alkaline and alkaline earth compounds in water condensate form a chemically active mud liquid with pH 8.2. Due to gravity, the mud liquid settles at the interface of the mud and the aluminum surface while forming locally scattered patches of liquid films. Once the mud liquid dries, adhesion work to remove the dry mud increases significantly. The mud liquid gives rise to the formation of pinholes and local pit sites on the aluminum surface. Morphological changes due to pit sites and residues of the dry mud on the aluminum surface lower the surface reflection after the removal of the dry mud from the surface. The characteristics of the aluminum surface can address the dust/mud-related limitations of reflective surfaces and may have implications for the reductions in the efficiencies of solar concentrated power systems. PMID:28378798

  11. Temperature-induced spectrum response of volume grating as an effective strategy for holographic sensing in acrylamide polymer part I: sensing.

    Science.gov (United States)

    Liu, Hongpeng; Yu, Dan; Zhou, Ke; Mao, Dongyao; Liu, Langbo; Wang, Hui; Wang, Weibo; Song, Qinggong

    2016-12-10

    Temperature-induced diffraction spectrum responses of holographic gratings are characterized for exploring the temperature-sensing capability of a holographic sensor. Linear blue shift of peak wavelength and linear diffraction reduction are observed. It provides quantitative expressions for sensing applications. Inorganic nanoparticles are dispersed into the binder to improve sensing properties. Obvious improvement of sensing parameters, including wavelength shift and diffraction change, is confirmed. The sensitivity, response rate, and linear response region of holographic sensors are determined to evaluate sensing capacity. Influence of relative humidity on holographic sensing response is discussed. Expansion of humidity range provides a probability for extending the range of wavelength shift. Finally, the temperature response reversibility of a holographic sensor is evaluated. These experimental results can expand the practical application field of holographic sensing strategy and accelerate the development of holographic sensors.

  12. Remote Sensing.

    Science.gov (United States)

    Williams, Richard S., Jr.; Southworth, C. Scott

    1983-01-01

    The Landsat Program became the major event of 1982 in geological remote sensing with the successful launch of Landsat 4. Other 1982 remote sensing accomplishments, research, publications, (including a set of Landsat worldwide reference system index maps), and conferences are highlighted. (JN)

  13. Mycosphere Essay 8: A review of genus Agaricus in tropical and humid subtropical regions of Asia

    OpenAIRE

    Karunarathna, Samantha Chandranath; Chen, J.; Mortimer, P.E.; Xu, J.C.; Zhao, R.L.; Callac, Philippe; Hyde, K.D.

    2016-01-01

    The genus Agaricus includes both edible and poisonous species, with more than 400 species worldwide. This genus includes many species, which are enormously important as sources of food and medicine, such as the button mushroom (Agaricus bisporus) and the almond mushroom (Agaricus subrufescens). This paper reviews the genus Agaricus in tropical and humid subtropical regions of Asia, including the history, characteristics, pertinent morphological and organoleptic taxonomic traits, molecular phy...

  14. Energy-Efficient Management of Mechanical Ventilation and Relative Humidity in Hot-Humid Climates

    Energy Technology Data Exchange (ETDEWEB)

    Withers, Jr., Charles R. [Building America Partnership for Improved Residential Construction, Cocoa, FL (United States)

    2016-12-01

    In hot and humid climates, it is challenging to energy-efficiently maintain indoor RH at acceptable levels while simultaneously providing required ventilation, particularly in high performance low cooling load homes. The fundamental problem with solely relying on fixed capacity central cooling systems to manage moisture during low sensible load periods is that they are oversized for cooler periods of the year despite being 'properly sized' for a very hot design cooling day. The primary goals of this project were to determine the impact of supplementing a central space conditioning system with 1) a supplemental dehumidifier and 2) a ductless mini-split on seasonal energy use and summer peak power use as well as the impact on thermal distribution and humidity control inside a completely furnished lab home that was continuously ventilated in accordance with ASHRAE 62.2-2013.

  15. Make Sense?

    DEFF Research Database (Denmark)

    Gyrd-Jones, Richard; Törmälä, Minna

    Purpose: An important part of how we sense a brand is how we make sense of a brand. Sense-making is naturally strongly connected to how we cognize about the brand. But sense-making is concerned with multiple forms of knowledge that arise from our interpretation of the brand-related stimuli...... sense of brands is related to who people think they are in their context and this shapes what they enact and how they interpret the brand (Currie & Brown, 2003; Weick, Sutcliffe, & Obstfeld, 2005; Weick, 1993). Our subject of interest in this paper is how stakeholders interpret and ascribe meaning...... to the brand and how these meaning narratives play out over time to create meta-narratives that drive brand meaning co-creation. In this paper we focus on the concept of brand identity since it is at the level of identity that the brand creates meaning for individuals (Kapferer, 2012; Csaba & Bengtsson, 2006)....

  16. Piezoelectric Active Humidity Sensors Based on Lead-Free NaNbO₃ Piezoelectric Nanofibers.

    Science.gov (United States)

    Gu, Li; Zhou, Di; Cao, Jun Cheng

    2016-06-07

    The development of micro-/nano-scaled energy harvesters and the self-powered sensor system has attracted great attention due to the miniaturization and integration of the micro-device. In this work, lead-free NaNbO₃ piezoelectric nanofibers with a monoclinic perovskite structure were synthesized by the far-field electrospinning method. The flexible active humidity sensors were fabricated by transferring the nanofibers from silicon to a soft polymer substrate. The sensors exhibited outstanding piezoelectric energy-harvesting performance with output voltage up to 2 V during the vibration process. The output voltage generated by the NaNbO₃ sensors exhibited a negative correlation with the environmental humidity varying from 5% to 80%, where the peak-to-peak value of the output voltage generated by the sensors decreased from 0.40 to 0.07 V. The sensor also exhibited a short response time, good selectively against ethanol steam, and great temperature stability. The piezoelectric active humidity sensing property could be attributed to the increased leakage current in the NaNbO₃ nanofibers, which was generated due to proton hopping among the H₃O⁺ groups in the absorbed H₂O layers under the driving force of the piezoelectric potential.

  17. Flexible room-temperature resistive humidity sensor based on silver nanoparticles

    Science.gov (United States)

    Traiwatcharanon, Pranlekha; Timsorn, Kriengkri; Wongchoosuk, Chatchawal

    2017-08-01

    In this work, a low-cost and flexible room-temperature humidity sensor was developed from pure resistive silver nanoparticles (AgNPs) synthesized through a simple green route using Pistia stratiotes extract as a reducing agent for AgNO3 under light illuminations. UV-Vis spectroscopic results showed that various synthesis parameters including AgNO3 concentration, reaction time, pH value and light irradiation strongly affected on the formation of AgNPs. AgNPs were also confirmed to exhibit spherical shapes with different sizes depending on pH by transmission electron microscopy. To fabricate the sensor, AgNPs were deposited on a transparent polyethylene substrate with pre-patterned Ag interdigitated electrodes via a drop coating method. From humidity-sensing results, the flexible pure AgNPs sensor exhibited high sensitivity to relative humidity (RH) with high repeatability and stability at room temperature. Moreover, the sensor electrical resistance and sensor response showed linear relationships to RH in the range of 20-85% with short response and recovery times of 10 s and 11 s, respectively.

  18. Compliment Graphene Oxide Coating on Silk Fiber Surface via Electrostatic Force for Capacitive Humidity Sensor Applications

    Science.gov (United States)

    Han, Kook In; Kim, Seungdu; Lee, In Gyu; Kim, Jong Pil; Kim, Jung-Ha; Hong, Suck Won; Cho, Byung Jin; Hwang, Wan Sik

    2017-01-01

    Cylindrical silk fiber (SF) was coated with Graphene oxide (GO) for capacitive humidity sensor applications. Negatively charged GO in the solution was attracted to the positively charged SF surface via electrostatic force without any help from adhesive intermediates. The magnitude of the positively charged SF surface was controlled through the static electricity charges created on the SF surface. The GO coating ability on the SF improved as the SF’s positive charge increased. The GO-coated SFs at various conditions were characterized using an optical microscope, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), Raman spectroscopy, and LCR meter. Unlike the intact SF, the GO-coated SF showed clear response-recovery behavior and well-behaved repeatability when it was exposed to 20% relative humidity (RH) and 90% RH alternatively in a capacitive mode. This approach allows humidity sensors to take advantage of GO’s excellent sensing properties and SF’s flexibility, expediting the production of flexible, low power consumption devices at relatively low costs. PMID:28218728

  19. ZnO–TiO2 nanocomposite: Characterization and moisture sensing studies

    Indian Academy of Sciences (India)

    N K Pandey; K Tiwari; Akash Roy

    2012-06-01

    This paper reports morphological and relative humidity sensing behaviour of ZnO–TiO2 nanocomposite powder pellets obtained through solid-state reaction route. Resistance of the pellets is observed to decrease with increase in relative humidity in the 10–90% range. Sensing element with 15 wt%of TiO2 in ZnO shows best results with a sensitivity of 9.08 M/%RH in 10–90% relative humidity range. This sensing element manifests crystallite size of 71 nm as measured from XRD and average grain size of 207 nm calculated from SEM micrograph. This sensing element manifests low hysteresis, less effect of ageing and good reproducibility. Response and recovery times of this sensing element are measured to be 84 s and 396 s, respectively.

  20. Mine remote sensing monitoring and assessment characteristics and the index system%矿山遥感监测评估特点与指标体系

    Institute of Scientific and Technical Information of China (English)

    周进生; 牛建英; 张旭; 于艳蕊

    2014-01-01

    矿山遥感监测评估是通过遥感监测手段获得对矿产资源开发利用状况、矿山环境和矿产资源规划执行情况的评判,为改进矿产资源规划、整顿矿业秩序、治理矿山环境等提供依据。根据矿山遥感监测实施效果评估的对象多、内容多、应用面广及难度大等特点,提出了矿产资源监管效果、效率和效益3个一级指标,9个二级指标的评估体系,并根据实验性评估结论提出简化指标体系、侧重连续监测区动态评估等建议。%Remote sensing monitoring is used by mine remote sensing monitoring and assessment so as to understand the situation of mineral resources development, mining environment and evaluate mineral resource planning implementation, thus providing the basis for mineral resources planning, mining order rectifying and mine environment governing. The authors analyzed the situation of evaluating the implementation effect of the mine remote sensing monitoring, which is characterized by numerous objects and contents, wide applications and considerable difficulties. In view of such a complex situation, this paper puts forward the index evaluation system for the mineral resources monitoring result, benefit and efficiency, which consists of three primary and nine secondary indexes. According to the experimental evaluation conclusion, some constructive suggestions, such as simplification of the index system and emphasis on the dynamic assessment of continuous monitoring area, have been put forward in this paper.

  1. Potentialities of laser systems for remote sensing of the atmosphere at a wide variability of optical and physical characteristics: dimensionless-parametric modelling

    Science.gov (United States)

    Agishev, R. R.

    2017-02-01

    Within the framework of generalisation of different approaches to the modelling of atmospheric lidars, the methodology capabilities for dimensionless-parametric analysis are expanded. The developed approach simplifies the analysis of the signal-to-noise ratio and potential capabilities of existing and newly developed monitoring systems with a wide variability of atmospheric and optical conditions and a great variety of modern lidars. Its applicability to the problems of remote atmospheric sensing, environmental monitoring and lidar navigation in providing the eye safety, noise immunity and reliability is discussed.

  2. Absolute Humidity and the Seasonality of Influenza (Invited)

    Science.gov (United States)

    Shaman, J. L.; Pitzer, V.; Viboud, C.; Grenfell, B.; Goldstein, E.; Lipsitch, M.

    2010-12-01

    Much of the observed wintertime increase of mortality in temperate regions is attributed to seasonal influenza. A recent re-analysis of laboratory experiments indicates that absolute humidity strongly modulates the airborne survival and transmission of the influenza virus. Here we show that the onset of increased wintertime influenza-related mortality in the United States is associated with anomalously low absolute humidity levels during the prior weeks. We then use an epidemiological model, in which observed absolute humidity conditions temper influenza transmission rates, to successfully simulate the seasonal cycle of observed influenza-related mortality. The model results indicate that direct modulation of influenza transmissibility by absolute humidity alone is sufficient to produce this observed seasonality. These findings provide epidemiological support for the hypothesis that absolute humidity drives seasonal variations of influenza transmission in temperate regions. In addition, we show that variations of the basic and effective reproductive numbers for influenza, caused by seasonal changes in absolute humidity, are consistent with the general timing of pandemic influenza outbreaks observed for 2009 A/H1N1 in temperate regions. Indeed, absolute humidity conditions correctly identify the region of the United States vulnerable to a third, wintertime wave of pandemic influenza. These findings suggest that the timing of pandemic influenza outbreaks is controlled by a combination of absolute humidity conditions, levels of susceptibility and changes in population mixing and contact rates.

  3. A physically based analytical spatial air temperature and humidity model

    Science.gov (United States)

    Yang Yang; Theodore A. Endreny; David J. Nowak

    2013-01-01

    Spatial variation of urban surface air temperature and humidity influences human thermal comfort, the settling rate of atmospheric pollutants, and plant physiology and growth. Given the lack of observations, we developed a Physically based Analytical Spatial Air Temperature and Humidity (PASATH) model. The PASATH model calculates spatial solar radiation and heat...

  4. Optimizing the Materials Response in Humidity Capacitive Sensors

    Directory of Open Access Journals (Sweden)

    Elham Noroozi Afshar

    2015-10-01

    Full Text Available The number of humidity outputs on the cap of a cylindrical capacitance sensor is optimized by designing three different probes with direct and indirect windows. The time interval is measured within which 30-70 % humidity can influence the dielectric constant and conductivity of the capacitance when exposed to a range of relative humidity. It is then compared with a simple set-up including a simplified equivalent circuit. The direct probes had four and double outputs on the window of the cylindrical capacitive sensor while the indirect probe had a thin plastic layer only. We observed that the dielectric constant and its conductivity depend closely to the humidity outgoing pathway and also to the increasing rate of humidity between the capacitance plates. The final variation in the materials properties alters the capacitance of the sensor which is measured simply by a LCR. This technique presents a simple method for tracking the recovery and reliability of the humidity sensors over time and assists in optimizing and controlling the materials response to the relative environment humidity. As a result, by controlling the environment humidity rate (0.02 %/s., we could measure the increment rate of capacitance with accuracy of 0.01 pf/%.

  5. EXPERIMENTAL DEVICE OF THE HIGH HUMIDITY AIR ELECTROSTATIC ELIMINATOR

    Institute of Scientific and Technical Information of China (English)

    吴筱青; 何尉岚

    1990-01-01

    As for electrostatic elimination there are many means.But the high humidity air electrostatic eliminator has simple,efficient, lightproof and fireproof etc. advantages. Thus it is often used in some industrial enterprises. The aim of this paper is to introduce an experimental device of high humidity air electrostatic eliminator and its principle and experimental data.

  6. RESEARCH ON MICROWAVE HUMIDITY TESTING OF CERAMIC PRODUCTS

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    This paper analyses the principle of microwave humidity testing. According to the problems in the production procedure of ceramic products, a microwave humidity testing system is designed and analyzed for its advantages. Furthermore, the system has been applied to the production line that produces ceramic products and the testing results are also satisfying.

  7. DNA-Based Nanopore Sensing.

    Science.gov (United States)

    Liu, Lei; Wu, Hai-Chen

    2016-12-05

    Nanopore sensing is an attractive, label-free approach that can measure single molecules. Although initially proposed for rapid and low-cost DNA sequencing, nanopore sensors have been successfully employed in the detection of a wide variety of substrates. Early successes were mostly achieved based on two main strategies by 1) creating sensing elements inside the nanopore through protein mutation and chemical modification or 2) using molecular adapters to enhance analyte recognition. Over the past five years, DNA molecules started to be used as probes for sensing rather than substrates for sequencing. In this Minireview, we highlight the recent research efforts of nanopore sensing based on DNA-mediated characteristic current events. As nanopore sensing is becoming increasingly important in biochemical and biophysical studies, DNA-based sensing may find wider applications in investigating DNA-involving biological processes. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. New UV-A laser-induced fluorescence imaging system for near-field remote sensing of vegetation: characteristics and performance

    Science.gov (United States)

    Sowinska, Malgorzata; Cunin, Bernard; Heisel, Francine; Miehe, Joseph-Albert

    1999-05-01

    In this paper, a compact, new UV-A laser induced fluorescence imaging system implemented in an all-road car for near-field remote sensing of vegetation will be described. It has been developed as a part of a European Community Program INTERREG II* and is consisting of three main parts: excitation, detection and control units. The excitation light pulses (10 ns) are produced by a frequency tripled Nd:YAG laser emitting at 355 nm with a variable repetition rate up to approximately equals 22 kHz and a pulse energy typically of 40 (mu) J. The laser spot size is adjusted by means of a variable beam expander. Fluorescence images are recorded via entrance lenses and 10 nm bandpass filters with a gated intensified digital CCD camera operating at 50 frames per second. The 'head of the system' (laser and camera) can be directed in site and azimuth, and can be high until a 6 meters height. All the functions like the system positioning, localization and distance detection, spot size adjustment, focus, sharpness, selection of the filter, laser and camera synchronization, gain of the intensifier, real time visualization of images, acquisition time are controlled by a newly developed software which also allows image storage, analysis and treatment. Examples of remote sensing fluorescence images recorded at a distance between 10 and 30 m are presented.

  9. On the distribution of relative humidity in cirrus clouds

    Directory of Open Access Journals (Sweden)

    P. Spichtinger

    2004-01-01

    Full Text Available We have analysed relative humidity statistics from measurements in cirrus clouds taken unintentionally during the Measurement of OZone by Airbus In-service airCraft project (MOZAIC. The shapes of the in-cloud humidity distributions change from nearly symmetric in relatively warm cirrus (warmer than −40° to considerably positively skew (i.e. towards high humidities in colder clouds. These results are in agreement to findings obtained recently from the INterhemispheric differences in Cirrus properties from Anthropogenic emissions (INCA campaign (Ovarlez et al., 2002. We interprete the temperature dependence of the shapes of the humidity distributions as an effect of the length of time a cirrus cloud needs from formation to a mature equilibrium stage, where the humidity is close to saturation. The duration of this transitional period increases with decreasing temperature. Hence cold cirrus clouds are more often met in the transitional stage than warm clouds.

  10. On the distribution of relative humidity in cirrus clouds

    Directory of Open Access Journals (Sweden)

    P. Spichtinger

    2004-01-01

    Full Text Available We have analysed relative humidity statistics from measurements in cirrus clouds taken unintentionally during the Measurement of OZone by Airbus In-service airCraft project (MOZAIC. The shapes of the in-cloud humidity distributions change from nearly symmetric in relatively warm cirrus (warmer than −40°C to considerably positively skew (i.e. towards high humidities in colder clouds. These results are in agreement to findings obtained recently from the INterhemispheric differences in Cirrus properties from Anthropogenic emissions (INCA campaign (Ovarlez et al., 2002. We interprete the temperature dependence of the shapes of the humidity distributions as an effect of the length of time a cirrus cloud needs from formation to a mature equilibrium stage, where the humidity is close to saturation. The duration of this transitional period increases with decreasing temperature. Hence cold cirrus clouds are more often met in the transitional stage than warm clouds.

  11. Nano-enabled paper humidity sensor for mobile based point-of-care lung function monitoring.

    Science.gov (United States)

    Bhattacharjee, Mitradip; Nemade, Harshal B; Bandyopadhyay, Dipankar

    2017-03-22

    The frequency of breathing and peak flow rate of exhaled air are necessary parameters to detect chronic obstructive pulmonary diseases (COPDs) such as asthma, bronchitis, or pneumonia. We developed a lung function monitoring point-of-care-testing device (LFM-POCT) consisting of mouthpiece, paper-based humidity sensor, micro-heater, and real-time monitoring unit. Fabrication of a mouthpiece of optimal length ensured that the exhaled air was focused on the humidity-sensor. The resistive relative humidity sensor was developed using a filter paper coated with nanoparticles, which could easily follow the frequency and peak flow rate of the human breathing. Adsorption followed by condensation of the water molecules of the humid air on the paper-sensor during the forced exhalation reduced the electrical resistance of the sensor, which was converted to an electrical signal for sensing. A micro-heater composed of a copper-coil embedded in a polymer matrix helped in maintaining an optimal temperature on the sensor surface. Thus, water condensed on the sensor surface only during forcible breathing and the sensor recovered rapidly after the exhalation was complete by rapid desorption of water molecules from the sensor surface. Two types of real-time monitoring units were integrated into the device based on light emitting diodes (LEDs) and smart phones. The LED based unit displayed the diseased, critical, and fit conditions of the lungs by flashing LEDs of different colors. In comparison, for the mobile based monitoring unit, an application was developed employing an open source software, which established a wireless connectivity with the LFM-POCT device to perform the tests.

  12. Variability of subtropical upper tropospheric humidity

    Directory of Open Access Journals (Sweden)

    J.-M. Ryoo

    2008-01-01

    Full Text Available Analysis of Atmospheric Infrared Sounder (AIRS measurements for five northern winters shows significant longitudinal variations in subtropical upper tropospheric relative humidity (RH, not only in the climatological mean values but also in the local distributions and temporal variability. The largest climatological mean values in the northern subtropics occur over the eastern Pacific and Atlantic oceans, where there is also large day-to-day variability. In contrast, there are smaller mean values, and smaller variability that occurs at lower frequency, over the Indian and western Pacific oceans. These differences in the distribution and variability of subtropical RH are related to differences in the key transport processes in the different sectors. The large variability and intermittent high and low RH over the Eastern Pacific and Atlantic oceans, and to a smaller extent over the Indian ocean, are due to intrusions of high potential vorticity air into the subtropics. Intrusions seldom occur over the eastern Indian and western Pacific oceans, and here the subtropical RH is more closely linked to the location and strength of subtropical anticyclones. In this region there are eastward propagating features in the subtropical RH that are out of phase with the tropical RH, and are caused by modulation of the subtropical anticyclones by the Madden-Julian Oscillation.

  13. Impact of temperature and humidity on perceived indoor air quality

    Energy Technology Data Exchange (ETDEWEB)

    Fang, Lei

    1997-11-01

    This thesis deals with the impact of temperature and humidity on the emission of pollutants from five building materials and on the perception of air polluted by the material emissions. The impact was studied in the temperature range 18-28 deg. C and the humidity range 30-70%RH, corresponding to conditions often pertaining in normal non-industrial indoor environments. The five building materials used in the study were: PVC flooring, waterborne acrylic floor varnish, loomed polyamide carpet with latex backing, waterborn acrylic wall paint and acrylic sealant; all these materials are commonly use din buildings. The effect of temperature and humidity on emission and perception of air pollutant emitted from the five building materials is described, using a specially developed exposure system. A computer-controlled exposure system was developed. The design of the system allowed the impact of temperature and humidity on the emission of pollutants from the materials to be judged separately from the impact on perception. The effect of temperature and humidity on emission and on perception was investigated at nine different combinations of three temperature levels 18 deg. C, 23 deg. C, 28 deg. C and three relative humidity levels 30%, 50%, 70%. A sensory panel assessed the acceptability of the air after facial exposure. Chemical measurements of the pollutants emitted were also made. The impact of temperature and humidity on perception of air quality during whole-body exposure is discussed. The influence of the pre-exposure temperature/humidity on perception of air quality and the time course of adaptation of air quality perception with different combinations of temperature and humidity were also investigated. It is recommended that future ventilation standards should include the effect of indoor air temperature and humidity in ventilation requirements. (EG) 86 refs.

  14. Structural Characteristics and Diversity of the Tree Species in the mid-montane Humid Ever-green Broad-leaved Forest in the Gaoligong Mountains, Yunnan%高黎贡山中山湿性常绿阔叶林树种结构及多样性特征

    Institute of Scientific and Technical Information of China (English)

    柴勇; 孟广涛; 李贵祥; 袁春明; 李品荣

    2015-01-01

    Structural characteristics and diversity of the tree species in the mid-montane humid ever-green broad-leaved forest in the Gaoligong Mountains in Yunnan Province were studied .The results showed that the forest is characterized by evergreen mesophanerophytes with simple and leathery and entire mesophylls , having a few decid-uous trees in the canopy layer and an unconspicuous seasonal aspect .In the plot , the species richness and the a-bundance are most among trees with height <5 m or with 1 cm≤DBH<5 cm, and decreased with the increase of the height or DBH class, respectively, which can be fitted very well with linear function or negative exponential function.The basal area are largest among trees with 11 m≤H<14 m or with 20 cm≤DBH<25 cm.In the plot, there were 10 546 individuals in 95 species, and ite Shannon-Weiner indes is 1.716, its Simpson index is 0.014, and its evenness index is 0.867 , indicating a higher level of species diversity in the whole .The species richness , the abundance and the Shannon-Weiner index were decreased gradually with the increase of the height and DBH class, but the Simpson index and the evenness index showed the opposite trend .Compared with other domestic plots, the species richness , density, basal area per ha of Gaoligongshan plot were at the middle level , but the maximum importance value was the lowest , and the proportion of the rare species was only higher than one plot , showing a higher diversity among these plots .%对高黎贡山中山湿性常绿阔叶林树种结构及多样性特征进行了研究。结果表明,高黎贡山中山湿性常绿阔叶林动态监测样地中树种以单叶、革质、全缘、中型叶为主,群落外貌以常绿的中高位芽植物为主,落叶树种较少,群落季相变化不明显。群落中树种数、树木个体数分别在H<5 m高度级及1 cm≤DBH<5 cm胸径级最多,并随高度或胸径的增加而不断减少,这种变化趋势可用直线函数或

  15. Humidity sorption on natural building stone

    Science.gov (United States)

    Franzen, C.; Mirwald, P.

    2003-04-01

    processes, physical, chemical or biological, depend on the presence of water. Like most porous materials building stone respond on humidity by water uptake. The sorption isotherm represents the equilibrium moisture, specific for each material. The determination of the isotherm for stone of low and small porosity like marble is difficult. With the help of a newly developed water sorption analysis chamber [2], which allows the simultaneous measurement of 11 samples, good results on stone/rock samples have been obtained. Even at marble species with pore volumes lower than 0.4 % isotherms are measured. This analytical method offers new insights in the pore behaviour of low porosity materials. The advantages of this technique which supplements other techniques (e.g. BET, Hg-porosimetry) are: i) the testing agent is identical to the weathering agent, water; ii) the atmospheric parameters at the measurement reflect the natural conditions - thus no changes to the material properties have to be considered; iii) due to the small diameter of the water molecule (~0.28 nm), smaller pores are reached than e.g. with N2 (~0.31 nm). Sorption isotherms of sandstone (Baumberg, Obernkirchen, Groeden), granite (Brixen), and marble (Sterzing, Laas) are presented. Particular as to marbles the resolution is considerably higher. A previously observed negative hysteresis [3] seems an effect due to limited data resolution. [1] Snethlage, R. (1984) Steinkonservierung, Bayer. LA Denkmalpflege, Ah. 22, 203 S. [2] Griesser, U.J., Dillenz, J. (2002) Neuartiges, vollautomatisches Feuchtesorptionsprüfgerät mit hohem Probendurchsatz, Feuchtetag 2002, Weimar, 85-93. [3] Fimmel, R. (1996) Verwitterungsverhalten der alpinen Marmore von Laas und Sterzing, Diss. Univ. Ibk, 116 S.

  16. Is Obsidian Hydration Dating Affected by Relative Humidity?

    Science.gov (United States)

    Friedman, I.; Trembour, F.W.; Smith, G.I.; Smith, F.L.

    1994-01-01

    Experiments carried out under temperatures and relative humidities that approximate ambient conditions show that the rate of hydration of obsidian is a function of the relative humidity, as well as of previously established variables of temperature and obsidian chemical composition. Measurements of the relative humidity of soil at 25 sites and at depths of between 0.01 and 2 m below ground show that in most soil environments, at depths below about 0.25 m, the relative humidity is constant at 100%. We have found that the thickness of the hydrated layer developed on obsidian outcrops exposed to the sun and to relative humidities of 30-90% is similar to that formed on other portions of the outcrop that were shielded from the sun and exposed to a relative humidity of approximately 100%. Surface samples of obsidian exposed to solar heating should hydrate more rapidly than samples buried in the ground. However, the effect of the lower mean relative humidity experiences by surface samples tends to compensate for the elevated temperature, which may explain why obsidian hydration ages of surface samples usually approximate those derived from buried samples.

  17. Single time point isothermal drug stability experiments at constant humidity.

    Science.gov (United States)

    Tao, Jian-Lin; Zhan, Xian-Cheng; Li, Lin-Li; Lin, Bing; Jiang, Lu

    2009-03-01

    A single time point isothermal drug stability experiments at constant humidity is introduced. In the new method, kinetic parameters related to both moisture and temperature were obtained by a single pair of experiments: these related to moisture by one with a group of testing humidities and a fixed temperature, those related to temperature by the other with a group of testing temperatures and a constant humidity. By a simulation, the estimates for the kinetic parameters (E(a), m, A) obtained by the proposed method and the reported programmed humidifying and heating method were statistically evaluated and were compared with those obtained by the isothermal measurements at constant humidity. Results indicated that under the same experimental conditions, the estimates obtained by the proposed method were significantly more precise than those obtained by the reported programmed humidifying and heating method. The estimates obtained by the isothermal method at constant humidity were somewhat more precise than those obtained by the proposed method. However, the experimental period needed by the isothermal method at constant humidity was greatly longer than that needed by the proposed method. The stability of dicloxacillin sodium, as a solid state model, was investigated by the single time point isothermal drug stability experiments at constant humidity. The results indicated that the kinetic parameters obtained by the proposed method were comparable to those from the reported.

  18. Geometrical Sense Making: Findings of Analysis Based on the Characteristics of the van Hiele Theory among a Sample of South African Grade 10 Learners

    Science.gov (United States)

    Alex, Jogymol K.; Mammen, Kuttickattu J.

    2016-01-01

    This paper reports on one part of a large study which attempted to identify the linguistic and hierarchical characteristics of van Hiele theory amongst grade 10 learners. The sample consisted of a total of 359 participants from five purposively selected schools from Mthatha District in the Eastern Cape Province of South Africa. The performance of…

  19. Geometrical Sense Making: Findings of Analysis Based on the Characteristics of the van Hiele Theory among a Sample of South African Grade 10 Learners

    Science.gov (United States)

    Alex, Jogymol K.; Mammen, Kuttickattu J.

    2016-01-01

    This paper reports on one part of a large study which attempted to identify the linguistic and hierarchical characteristics of van Hiele theory amongst grade 10 learners. The sample consisted of a total of 359 participants from five purposively selected schools from Mthatha District in the Eastern Cape Province of South Africa. The performance of…

  20. Effect of time-varying humidity on the performance of a polymer electrolyte membrane fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Noorani, Shamsuddin [Department of Mechanical Engineering, University of Michigan-Dearborn (United States); Shamim, Tariq [Mechanical Engineering, Masdar Institute of Science and Technology (United Arab Emirates)], E-mail: tshamim@masdar.ac.ae

    2011-07-01

    In the energy sector, fuel cells constitute a promising solution for the future due to their energy-efficient and environment-friendly characteristics. However, the performance of fuel cells is very much affected by the humidification level of the reactants, particularly in hot regions. The aim of this paper is to develop a better understanding of the effect of driving conditions on the performance of fuel cells. A macroscopic single-fuel-cell-based, one dimensional, isothermal model was used on a polymer electrolyte membrane fuel cell to carry out a computational study of the impact of humidity conditions which vary over time. It was found that the variation of humidity has a significant effect on water distribution but a much lower impact on power and current densities. This paper provided useful information on fuel cells' performance under varying conditions which could be used to improve their design for mobile applications.

  1. SAW RFID-Tags for Mass-Sensitive Detection of Humidity and Vapors.

    Science.gov (United States)

    Lieberzeit, Peter A; Palfinger, Christian; Dickert, Franz L; Fischerauer, Gerhard

    2009-01-01

    One-port surface acoustic wave (SAW) devices with defined reflector patterns give characteristic signal patterns in the time domain making them identifiable and leading to so-called RFID-Tags. Each sensor responds with a burst of signals, their timed positions giving the identification code, while the amplitudes can be related to the analyte concentration. This paper presents the first combination of such a transducer with chemically sensitive layer materials. These include crosslinked polyvinyl alcohol for determining relative humidity and tert-butylcalix[4]arene for detecting solvent vapors coated on the free space between the reflectors. In going from the time domain to the frequency domain by Fourier transformation, changes in frequency and phase lead to sensor responses. Hence, it is possible to measure the concentration of tetrachloroethene in air down to 50 ppm, as well as 1% changes in relative humidity.

  2. SAW RFID-Tags for Mass-Sensitive Detection of Humidity and Vapors

    Directory of Open Access Journals (Sweden)

    Gerhard Fischerauer

    2009-12-01

    Full Text Available One-port surface acoustic wave (SAW devices with defined reflector patterns give characteristic signal patterns in the time domain making them identifiable and leading to so-called RFID-Tags. Each sensor responds with a burst of signals, their timed positions giving the identification code, while the amplitudes can be related to the analyte concentration. This paper presents the first combination of such a transducer with chemically sensitive layer materials. These include crosslinked polyvinyl alcohol for determining relative humidity and tert-butylcalix[4]arene for detecting solvent vapors coated on the free space between the reflectors. In going from the time domain to the frequency domain by Fourier transformation, changes in frequency and phase lead to sensor responses. Hence, it is possible to measure the concentration of tetrachloroethene in air down to 50 ppm, as well as 1% changes in relative humidity.

  3. Urban heat island and bioclimatological conditions in a hot-humid tropical city: the example of Akure, Nigeria

    Directory of Open Access Journals (Sweden)

    Balogun, Ifeoluwa A.

    2014-09-01

    Full Text Available The impact of weather on human health has become an issue of increased significance in recent times, considering the increasing rate of urbanisation and the much associated heat island phenomenon. This study examines the urbanisation influence on human bioclimatic conditions in Akure, a medium sized hot-humid tropical city in Nigeria, utilising data from measurements at urban and rural sites in the city. Differences in the diurnal, monthly and seasonal variation of human bioclimatic characteristics between both environments were evaluated and tested for statistical significance. Higher frequencies of high temperatures observed in the city centre suggest a significant heat stress and health risk in this hot-humid city.

  4. Measure Guideline: Supplemental Dehumidification in Warm-Humid Climates

    Energy Technology Data Exchange (ETDEWEB)

    Rudd, Armin [Building Science Corporation, Somerville, MA (United States)

    2014-10-01

    This document covers a description of the need and applied solutions for supplemental dehumidification in warm-humid climates, especially for energy efficient homes where the sensible cooling load has been dramatically reduced. Cooling loads are typically high and cooling equipment runs a lot to cool the air in older homes in warm-humid climates. The cooling process also removes indoor moisture, reducing indoor relative humidity. However, at current residential code levels, and especially for above-code programs, sensible cooling loads have been so dramatically reduced that the cooling system does not run a lot to cool the air, resulting in much less moisture being removed. In these new homes, cooling equipment is off for much longer periods of time especially during spring/fall seasons, summer shoulder months, rainy periods, some summer nights, and winter days. In warm-humid climates, those long-off periods allow indoor humidity to become elevated due to internally generated moisture and ventilation air change. Elevated indoor relative humidity impacts comfort, indoor air quality, and building material durability. Industry is responding with supplemental dehumidification options, but that effort is really in its infancy regarding year-round humidity control in low-energy homes. Available supplemental humidity control options are discussed. Some options are less expensive but may not control indoor humidity as well as more expensive and comprehensive options. The best performing option is one that avoids overcooling and adding unnecessary heat to the space by using waste heat from the cooling system to reheat the cooled and dehumidified air to room-neutral temperature.

  5. Measure Guideline: Supplemental Dehumidification in Warm-Humid Climates

    Energy Technology Data Exchange (ETDEWEB)

    Rudd, A.

    2014-10-01

    This document covers a description of the need and applied solutions for supplemental dehumidification in warm-humid climates, especially for energy efficient homes where the sensible cooling load has been dramatically reduced. In older homes in warm-humid climates, cooling loads are typically high and cooling equipment runs a lot to cool the air. The cooling process also removes indoor moisture, reducing indoor relative humidity. However, at current residential code levels, and especially for above-code programs, sensible cooling loads have been so dramatically reduced that the cooling system does not run a lot to cool the air, resulting in much less moisture being removed. In these new homes, cooling equipment is off for much longer periods of time especially during spring/fall seasons, summer shoulder months, rainy periods, some summer nights, and some winter days. In warm-humid climates, those long off periods allow indoor humidity to become elevated due to internally generated moisture and ventilation air change. Elevated indoor relative humidity impacts comfort, indoor air quality, and building material durability. Industry is responding with supplemental dehumidification options, but that effort is really in its infancy regarding year-round humidity control in low-energy homes. Available supplemental humidity control options are discussed. Some options are less expensive but may not control indoor humidity as well as more expensive and comprehensive options. The best performing option is one that avoids overcooling and avoids adding unnecessary heat to the space by using waste heat from the cooling system to reheat the cooled and dehumidified air to room-neutral temperature.

  6. Effects of humidity during photoprocessing on thin film metallization adhesion

    Energy Technology Data Exchange (ETDEWEB)

    Norwood, D.P.

    1980-03-01

    Humidity effects during photoprocessing on tantalum/chromium/gold thin film networks (TFNs) were investigated. Humidity conditions at various process steps were controlled by placing either desiccant or water in handling containers for the TFNs. The TFNs photoprocessed in humid conditions had a much higher occurrence of metallization failures compared to TFNs processed in dry conditions. Ceramic surface defects were shown to cause pores in the thin films, and these pores enhanced corrosion susceptibility for the films. This study resulted in a desiccated storage process for production of TFNs.

  7. Refractive Index of Humid Air in the Infrared: Model Fits

    CERN Document Server

    Mathar, R J

    2006-01-01

    The theory of summation of electromagnetic line transitions is used to tabulate the Taylor expansion of the refractive index of humid air over the basic independent parameters (temperature, pressure, humidity, wavelength) in five separate infrared regions from the H to the Q band at a fixed percentage of Carbon Dioxide. These are least-squares fits to raw, highly resolved spectra for a set of temperatures from 10 to 25 C, a set of pressures from 500 to 1023 hPa, and a set of relative humidities from 5 to 60%. These choices reflect the prospective application to characterize ambient air at mountain altitudes of astronomical telescopes.

  8. Modeling of humidity-related reliability in enclosures with electronics

    DEFF Research Database (Denmark)

    Hygum, Morten Arnfeldt; Popok, Vladimir

    2015-01-01

    Reliability of electronics that operate outdoor is strongly affected by environmental factors such as temperature and humidity. Fluctuations of these parameters can lead to water condensation inside enclosures. Therefore, modelling of humidity distribution in a container with air and freely exposed...... to predict humidity-related reliability of a printed circuit board (PCB) located in a cabinet by combining structural reliability methods and non-linear diffusion models. This framework can, thus, be used for reliability prediction from a climatic point-of-view. The proposed numerical approach is then tested...

  9. A Comparison of the Classification of Vegetation Characteristics by Spectral Mixture Analysis and Standard Classifiers on Remotely Sensed Imagery within the Siberia Region

    OpenAIRE

    Tan, S.-Y.

    2003-01-01

    As an alternative to the traditional method of inferring vegetation cover characteristics from satellite data by classifying each pixel into a specific land cover type based on predefined classification schemes, the Spectral Mixture Analysis (SMA) method is applied to images of the Siberia region. A linear mixture model was applied to determine proportional estimates of land cover for, (a) agriculture and floodplain soils, (b) broadleaf, and (c) conifer classes, in pixels of 30 m resolution L...

  10. The contribution of hyperspectral remote sensing to identify vegetation characteristics necessary to assess the fate of Persistent Organic Pollutants (POPs in the environment

    Directory of Open Access Journals (Sweden)

    A. Di Guardo

    2006-06-01

    Full Text Available During recent years hyperspectral remote sensing data were successfully used to characterise the state and properties of vegetation. The information on vegetation cover and status is useful for a range of environmental modelling studies. Recent works devoted to the understanding of the fate of Persistent Organic Pollutants (POPs in the environment showed that forests and vegetation in general act as a «sponge» for chemicals present in air and the intensity of this «capture» effect depends on some vegetation parameters such as surface area, leaf composition, turnover etc. In the framework of the DARFEM experiment conducted in late June 2001, different airborne hyperspectral images were acquired and analysed to derive some vegetation parameters of relevance for multimedia models, such as the spatial distribution of plant species and their relative foliage biomass. The study area, south west of Milan, encompasses a range of land cover types typical of Northern Italy, including intensive poplar plantations and natural broad-leaf forest. An intensive field campaign was accomplished during the aerial survey to collect vegetation parameters and radiometric measurements. Results obtained from the analysis of hyperspectral images, map of vegetation species, Leaf Area Index (LAI and foliage biomass are presented and discussed.

  11. Effect of synthesis route on electrical and ethanol sensing characteristics for LaFeO3-δ nanoparticles by citric sol-gel method

    Science.gov (United States)

    Cao, Ensi; Yang, Yuqing; Cui, Tingting; Zhang, Yongjia; Hao, Wentao; Sun, Li; Peng, Hua; Deng, Xiao

    2017-01-01

    LaFeO3-δ nanoparticles were prepared by citric sol-gel method with different raw material choosing and calcination process. The choosing of polyethylene glycol instead of ethylene glycol as raw material and additional pre-calcination at 400 °C rather than direct calcination at 600 °C could result in the decrease of resistance due to the reduction of activation energy Ea. Meanwhile, the choosing of ethylene glycol as raw material and additional pre-calcination leads to the enhancement of sensitivity to ethanol. Comprehensive analysis on the sensitivity and XRD, SEM, TEM, XPS results indicates that the sensing performance of LaFeO3-δ should be mainly determined by the adsorbed oxygen species on Fe ions, with certain contribution from native active oxygen. The best sensitivity of 46.1-200 ppm ethanol at prime working temperature of 112 °C is obtained by the sample using ethylene glycol as raw material with additional pre-calcination, which originates from its uniformly-sized and well-dispersed particles as well as high atomic ratio of Fe/La at surface region.

  12. A geochemical examination of humidity cell tests

    Science.gov (United States)

    Maest, Ann; Nordstrom, D. Kirk

    2017-01-01

    Humidity cell tests (HCTs) are long-term (20 to >300 weeks) leach tests that are considered by some to be the among the most reliable geochemical characterization methods for estimating the leachate quality of mined materials. A number of modifications have been added to the original HCT method, but the interpretation of test results varies widely. We suggest that the HCTs represent an underutilized source of geochemical data, with a year-long test generating approximately 2500 individual chemical data points. The HCT concentration peaks and valleys can be thought of as a “chromatogram” of reactions that may occur in the field, whereby peaks in concentrations are associated with different geochemical processes, including sulfate salt dissolution, sulfide oxidation, and dissolution of rock-forming minerals, some of which can neutralize acid. Some of these reactions occur simultaneously, some do not, and geochemical modeling can be used to help distinguish the dominant processes. Our detailed examination, including speciation and inverse modeling, of HCTs from three projects with different geology and mineralization shows that rapid sulfide oxidation dominates over a limited period of time that starts between 40 and 200 weeks of testing. The applicability of laboratory tests results to predicting field leachate concentrations, loads, or rates of reaction has not been adequately demonstrated, although early flush releases and rapid sulfide oxidation rates in HCTs should have some relevance to field conditions. Knowledge of possible maximum solute concentrations is needed to design effective treatment and mitigation approaches. Early flush and maximum sulfide oxidation results from HCTs should be retained and used in environmental models. Factors that complicate the use of HCTs include: sample representation, time for microbial oxidizers to grow, sample storage before testing, geochemical reactions that add or remove constituents, and the HCT results chosen for use

  13. HUMID AIR TURBINE CYCLE TECHNOLOGY DEVELOPMENT PROGRAM

    Energy Technology Data Exchange (ETDEWEB)

    Richard Tuthill

    2002-07-18

    The Humid Air Turbine (HAT) Cycle Technology Development Program focused on obtaining HAT cycle combustor technology that will be the foundation of future products. The work carried out under the auspices of the HAT Program built on the extensive low emissions stationary gas turbine work performed in the past by Pratt & Whitney (P&W). This Program is an integral part of technology base development within the Advanced Turbine Systems Program at the Department of Energy (DOE) and its experiments stretched over 5 years. The goal of the project was to fill in technological data gaps in the development of the HAT cycle and identify a combustor configuration that would efficiently burn high moisture, high-pressure gaseous fuels with low emissions. The major emphasis will be on the development of kinetic data, computer modeling, and evaluations of combustor configurations. The Program commenced during the 4th Quarter of 1996 and closed in the 4th Quarter of 2001. It teamed the National Energy Technology Laboratory (NETL) with P&W, the United Technologies Research Center (UTRC), and a subcontractor on-site at UTRC, kraftWork Systems Inc. The execution of the program started with bench-top experiments that were conducted at UTRC for extending kinetic mechanisms to HAT cycle temperature, pressure, and moisture conditions. The fundamental data generated in the bench-top experiments was incorporated into the analytical tools available at P&W to design the fuel injectors and combustors. The NETL then used the hardware to conduct combustion rig experiments to evaluate the performance of the combustion systems at elevated pressure and temperature conditions representative of the HAT cycle. The results were integrated into systems analysis done by kraftWork to verify that sufficient understanding of the technology had been achieved and that large-scale technological application and demonstration could be undertaken as follow-on activity. An optional program extended the

  14. Remotely sensed vegetation moisture as explanatory variable of Lyme borreliosis incidence

    Science.gov (United States)

    Barrios, J. M.; Verstraeten, W. W.; Maes, P.; Clement, J.; Aerts, J. M.; Farifteh, J.; Lagrou, K.; Van Ranst, M.; Coppin, P.

    2012-08-01

    The strong correlation between environmental conditions and abundance and spatial spread of the tick Ixodes ricinus is widely documented. I. ricinus is in Europe the main vector of the bacterium Borrelia burgdorferi, the pathogen causing Lyme borreliosis (LB). Humidity in vegetated systems is a major factor in tick ecology and its effects might translate into disease incidence in humans. Time series of two remotely sensed indices with sensitivity to vegetation greenness and moisture were tested as explanatory variables of LB incidence. Wavelet-based multiresolution analysis allowed the examination of these signals at different temporal scales in study sites in Belgium, where increases in LB incidence were reported in recent years. The analysis showed the potential of the tested indices for disease monitoring, the usefulness of analyzing the signal in different time frames and the importance of local characteristics of the study area for the selection of the vegetation index.

  15. TAO/TRITON, RAMA, and PIRATA Buoys, Quarterly, Relative Humidity

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset has quarterly Relative Humidity data from the TAO/TRITON (Pacific Ocean, http://www.pmel.noaa.gov/tao/), RAMA (Indian Ocean,...

  16. TAO/TRITON, RAMA, and PIRATA Buoys, Monthly, Relative Humidity

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset has monthly Relative Humidity data from the TAO/TRITON (Pacific Ocean, http://www.pmel.noaa.gov/tao/), RAMA (Indian Ocean,...

  17. TAO/TRITON, RAMA, and PIRATA Buoys, Daily, Relative Humidity

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset has daily Relative Humidity data from the TAO/TRITON (Pacific Ocean, http://www.pmel.noaa.gov/tao/), RAMA (Indian Ocean,...

  18. Computational Model for Internal Relative Humidity Distributions in Concrete

    Directory of Open Access Journals (Sweden)

    Wondwosen Ali

    2014-01-01

    Full Text Available A computational model is developed for predicting nonuniform internal relative humidity distribution in concrete. Internal relative humidity distribution is known to have a direct effect on the nonuniform drying shrinkage strains. These nonuniform drying shrinkage strains result in the buildup of internal stresses, which may lead to cracking of concrete. This may be particularly true at early ages of concrete since the concrete is relatively weak while the difference in internal relative humidity is probably high. The results obtained from this model can be used by structural and construction engineers to predict critical drying shrinkage stresses induced due to differential internal humidity distribution. The model uses finite elment-finite difference numerical methods. The finite element is used to space discretization while the finite difference is used to obtain transient solutions of the model. The numerical formulations are then programmed in Matlab. The numerical results were compared with experimental results found in the literature and demonstrated very good agreement.

  19. NOS CO-OPS Meteorological Data, Relative Humidity, 6-Minute

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset has Relative Humidity data from NOAA NOS Center for Operational Oceanographic Products and Services (CO-OPS). WARNING: These preliminary data have not...

  20. The near-surface methane humidity on Titan

    CERN Document Server

    Lora, Juan M

    2016-01-01

    We retrieve vertical and meridional variations of methane mole fraction in Titan's lower troposphere by re-analyzing near-infrared ground-based observations from 17 July 2014 UT (Adamkovics et al., 2016). We generate synthetic spectra using atmospheric methane profiles that do not contain supersaturation or discontinuities to fit the observations, and thereby retrieve minimum saturation altitudes and corresponding specific humidities in the boundary layer. We relate these in turn to surface-level relative humidities using independent surface temperature measurements. We also compare our results with general circulation model simulations to interpret and constrain the relationship between humidities and surface liquids. The results show that Titan's lower troposphere is undersaturated at latitudes south of 60N, consistent with a dry surface there, but increases in humidity toward the north pole indicate appreciable surface liquid coverage. While our observations are consistent with considerably more liquid met...

  1. The influence of humidity fluxes on offshore wind speed profiles

    DEFF Research Database (Denmark)

    Barthelmie, Rebecca Jane; Sempreviva, Anna Maria; Pryor, Sara

    2010-01-01

    Wind energy developments offshore focus on larger turbines to keep the relative cost of the foundation per MW of installed capacity low. Hence typical wind turbine hub-heights are extending to 100 m and potentially beyond. However, measurements to these heights are not usually available, requiring...... extrapolation from lower measurements. With humid conditions and low mechanical turbulence offshore, deviations from the traditional logarithmic wind speed profile become significant and stability corrections are required. This research focuses on quantifying the effect of humidity fluxes on stability corrected...... wind speed profiles. The effect on wind speed profiles is found to be important in stable conditions where including humidity fluxes forces conditions towards neutral. Our results show that excluding humidity fluxes leads to average predicted wind speeds at 150 m from 10 m which are up to 4% higher...

  2. Passive Wireless SAW Humidity Sensors and System Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Phase I demonstrated the technical feasibility of creating surface acoustic wave (SAW) based humidity sensors that respond rapidly (under 0.5 second) and reversibly...

  3. Searching for new solutions Humidity measurements in the environments

    Directory of Open Access Journals (Sweden)

    Gianina Creţu

    2008-05-01

    Full Text Available More attention is nowadays being paid to thequality of the air we breathe, resulting in an increasingneed for humidity measurements in the home and officeenvironments. Maintaining the proper level of relativehumidity is also necessary to avoid conditions of extremehumidity condensation in buildings.The facts that construction problems and excessive waterand humidity often go together is well-known around theworld today. Moisture and water damage is a wellknown problem in construction in many countries.Problems of all construction are caused by humidity and50 per cent of all buildings have some kind of moisturerelatedproblems. Growing awareness of percentages suchas these has led to greater attention being paid toconstruction humidity and its measurement throughoutthe world in recent years.This paper presents a condensed review of nowadayshumidity sensors technology, problem implicated andsome modern tendencies.

  4. Numerical Analysis of Shock Induced Separation Delay by Air Humidity

    Institute of Scientific and Technical Information of China (English)

    Piotr DOERFFER; Slawomir DYKAS

    2005-01-01

    @@ In this paper numerical calculations of the dry and humid air flows in the nozzle are presented. The dry air flow (adiabatic flow) and the humid air flow (flow with homogeneous condensation, diabatic flow) are modeled with the use of Reynolds Averaged Navier-Stokes (RANS) equations. The comparison of these two types of flow is carried out. The influence of the air humidity on the shock wave location and its interaction with the boundary layer is examined. Obtained numerical results present a first numerical approach of the condensation and evaporation process in transonic flow of humid air. The phenomena considered here are very complex and complicated and need further in-depth numerical analysis.

  5. Nanostructured Humidity Sensor for Spacecraft Life Support Systems Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Humidity is a critical variable for monitoring and control on extended duration missions because it can affect the operation and efficiency of closed loop life...

  6. Food analysis using artificial senses.

    Science.gov (United States)

    Śliwińska, Magdalena; Wiśniewska, Paulina; Dymerski, Tomasz; Namieśnik, Jacek; Wardencki, Waldemar

    2014-02-19

    Nowadays, consumers are paying great attention to the characteristics of food such as smell, taste, and appearance. This motivates scientists to imitate human senses using devices known as electronic senses. These include electronic noses, electronic tongues, and computer vision. Thanks to the utilization of various sensors and methods of signal analysis, artificial senses are widely applied in food analysis for process monitoring and determining the quality and authenticity of foods. This paper summarizes achievements in the field of artificial senses. It includes a brief history of these systems, descriptions of most commonly used sensors (conductometric, potentiometric, amperometic/voltammetric, impedimetric, colorimetric, piezoelectric), data analysis methods (for example, artificial neural network (ANN), principal component analysis (PCA), model CIE L*a*b*), and application of artificial senses to food analysis, in particular quality control, authenticity and falsification assessment, and monitoring of production processes.

  7. Humidity Sensors Printed on Recycled Paper and Cardboard

    Directory of Open Access Journals (Sweden)

    Matija Mraović

    2014-07-01

    Full Text Available Research, design, fabrication and results of various screen printed capacitive humidity sensors is presented in this paper. Two types of capacitive humidity sensors have been designed and fabricated via screen printing on recycled paper and cardboard, obtained from the regional paper and cardboard industry. As printing ink, commercially available silver nanoparticle-based conductive ink was used. A considerable amount of work has been devoted to the humidity measurement methods using paper as a dielectric material. Performances of different structures have been tested in a humidity chamber. Relative humidity in the chamber was varied in the range of 35%–80% relative humidity (RH at a constant temperature of 23 °C. Parameters of interest were capacitance and conductance of each sensor material, as well as long term behaviour. Process reversibility has also been considered. The results obtained show a mainly logarithmic response of the paper sensors, with the only exception being cardboard-based sensors. Recycled paper-based sensors exhibit a change in value of three orders of magnitude, whereas cardboard-based sensors have a change in value of few 10s over the entire scope of relative humidity range (RH 35%–90%. Two different types of capacitor sensors have been investigated: lateral (comb type sensors and modified, perforated flat plate type sensors. The objective of the present work was to identify the most important factors affecting the material performances with humidity, and to contribute to the development of a sensor system supported with a Radio Frequency Identification (RFID chip directly on the material, for use in smart packaging applications. Therefore, the authors built a passive and a battery-supported wireless module based on SL900A smart sensory tag’s IC to achieve UHF-RFID functionality with data logging capability.

  8. Novel Polymer Resistive-type Humidity Sensitive Materials

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    1 Results Humidity sensors have been widely investigated in recent years[1,2].In this work,two kinds of polymer resistive-type humidity sensitive materials were prepared as follows: 1) polymer electrolyte with an IPN structure formed by the simultaneous quaternization and crosslinking of poly(4-vinylpyridine) (P4VP) and poly(glycidyl methacrylate) (PGMA) with 1,4-dibromobutane (DBB) and diethyltriamine (DETA) respectively; 2) silicon-containing polyelectrolyte with crosslinking structure formed by a sim...

  9. Humidity sensors printed on recycled paper and cardboard.

    Science.gov (United States)

    Mraović, Matija; Muck, Tadeja; Pivar, Matej; Trontelj, Janez; Pleteršek, Anton

    2014-07-28

    Research, design, fabrication and results of various screen printed capacitive humidity sensors is presented in this paper. Two types of capacitive humidity sensors have been designed and fabricated via screen printing on recycled paper and cardboard, obtained from the regional paper and cardboard industry. As printing ink, commercially available silver nanoparticle-based conductive ink was used. A considerable amount of work has been devoted to the humidity measurement methods using paper as a dielectric material. Performances of different structures have been tested in a humidity chamber. Relative humidity in the chamber was varied in the range of 35%-80% relative humidity (RH) at a constant temperature of 23 °C. Parameters of interest were capacitance and conductance of each sensor material, as well as long term behaviour. Process reversibility has also been considered. The results obtained show a mainly logarithmic response of the paper sensors, with the only exception being cardboard-based sensors. Recycled paper-based sensors exhibit a change in value of three orders of magnitude, whereas cardboard-based sensors have a change in value of few 10s over the entire scope of relative humidity range (RH 35%-90%). Two different types of capacitor sensors have been investigated: lateral (comb) type sensors and modified, perforated flat plate type sensors. The objective of the present work was to identify the most important factors affecting the material performances with humidity, and to contribute to the development of a sensor system supported with a Radio Frequency Identification (RFID) chip directly on the material, for use in smart packaging applications. Therefore, the authors built a passive and a battery-supported wireless module based on SL900A smart sensory tag's IC to achieve UHF-RFID functionality with data logging capability.

  10. Analysis and Test of UHF RFID Humidity Sensor%超高频射频识别湿度传感器的分析与测试

    Institute of Scientific and Technical Information of China (English)

    关硕; 奚经天; 王俊宇

    2011-01-01

    读写器和标签组成的射频识别系统(RFID)可以用于湿度测量.本文通过理论分析,数值仿真以及实验测试给出了可用于湿度传感器的EPC Gen2电子标签的特性.分析结果表明,当湿度变化时,标签天线和标签之间的阻抗匹配系数单调变化的标签才可用做湿度传感器.在空气中,标签天线和标签芯片完全匹配的标签可以用于湿度测量.本文还在实验中考虑了纸张在湿度增加或减少时对基于电子标签的湿度传感器测量结果的影响,并且给出了分析结果.%The combination of the RFID reader and the tag is able to measure humidity. Theoretical analysis, mathematical simulations, and experiments for EPC Gen2 tags used as humidity sensors are conducted to deduce the reason why RFID tags can be used as humidity sensors. According to the analysis, an appropriate RFID tag used for humidity sensing requires that the impedance matching factor between the tag antenna and the tag changes monotonically when the humidity changes. The tag can be used to measure humidity when the impedances of the tag antenna and the tag chip are perfectly matched. The experiment considers that the moisture content absorbed by paper when the humidity rises is different from that desorbed by paper when the humidity decreases and the analysis is given.

  11. Variations of relative humidity in relation to meningitis in Africa

    Science.gov (United States)

    Seefeldt, M. W.; Hopson, T. M.

    2011-12-01

    The meningitis belt is a region covering Sub-Saharan Africa from the Sahel of West Africa eastward to western Ethiopia. The region is prone to meningitis epidemics during the dry season extending from approximately January to May, depending on the region. Relative humidity has been found to be a critical environmental factor indicating the susceptibility of a region to meningitis epidemics. This study evaluates the variation of relative humidity across West Africa over 30 dry-seasons (1979 - 2009) using the NASA-MERRA dataset. The method of self-organizing maps is employed to characterize the changes in relative humidity patterns across the region within a given dry season as well as changes over the 30 years. A general pattern of changes in relative humidity is indicated as the rainbelt retreats to the south at the onset of the dry season and then returns to the region at the end of the dry season. Within each dry season there is a unique pattern. The climatological conditions of relative humidity at the onset of the dry season provide an indication of the moisture environment for the entire dry season. Year to year variation in the relative humidity patterns are found to be gradual. Future applications involve using the results from the SOM evaluation to be used for future decisions involving prevention of meningitis epidemics.

  12. Making Sense

    Science.gov (United States)

    Golding, Clinton

    2009-01-01

    In this article, the author provides a self-portrait of his intellectual life. He states that overall his approach to teaching and researching is about "making sense" where inadequate or incongruous conceptions fall into place or are transformed so they are congruous and adequate. In his teaching the author applies the methods of…

  13. Pervasive sensing

    Science.gov (United States)

    Nagel, David J.

    2000-11-01

    The coordinated exploitation of modern communication, micro- sensor and computer technologies makes it possible to give global reach to our senses. Web-cameras for vision, web- microphones for hearing and web-'noses' for smelling, plus the abilities to sense many factors we cannot ordinarily perceive, are either available or will be soon. Applications include (1) determination of weather and environmental conditions on dense grids or over large areas, (2) monitoring of energy usage in buildings, (3) sensing the condition of hardware in electrical power distribution and information systems, (4) improving process control and other manufacturing, (5) development of intelligent terrestrial, marine, aeronautical and space transportation systems, (6) managing the continuum of routine security monitoring, diverse crises and military actions, and (7) medicine, notably the monitoring of the physiology and living conditions of individuals. Some of the emerging capabilities, such as the ability to measure remotely the conditions inside of people in real time, raise interesting social concerns centered on privacy issues. Methods for sensor data fusion and designs for human-computer interfaces are both crucial for the full realization of the potential of pervasive sensing. Computer-generated virtual reality, augmented with real-time sensor data, should be an effective means for presenting information from distributed sensors.

  14. Development of Smart Ventilation Control Algorithms for Humidity Control in High-Performance Homes in Humid U.S. Climates

    Energy Technology Data Exchange (ETDEWEB)

    Less, Brennan; Ticci, Sara

    2017-04-11

    Past field research and simulation studies have shown that high performance homes experience elevated indoor humidity levels for substantial portions of the year in humid climates. This is largely the result of lower sensible cooling loads, which reduces the moisture removed by the cooling system. These elevated humidity levels lead to concerns about occupant comfort, health and building durability. Use of mechanical ventilation at rates specified in ASHRAE Standard 62.2-2013 are often cited as an additional contributor to humidity problems in these homes. Past research has explored solutions, including supplemental dehumidification, cooling system operational enhancements and ventilation system design (e.g., ERV, supply, exhaust, etc.). This project’s goal is to develop and demonstrate (through simulations) smart ventilation strategies that can contribute to humidity control in high performance homes. These strategies must maintain IAQ via equivalence with ASHRAE Standard 62.2-2013. To be acceptable they must not result in excessive energy use. Smart controls will be compared with dehumidifier energy and moisture performance. This work explores the development and performance of smart algorithms for control of mechanical ventilation systems, with the objective of reducing high humidity in modern high performance residences. Simulations of DOE Zero-Energy Ready homes were performed using the REGCAP simulation tool. Control strategies were developed and tested using the Residential Integrated Ventilation (RIVEC) controller, which tracks pollutant exposure in real-time and controls ventilation to provide an equivalent exposure on an annual basis to homes meeting ASHRAE 62.2-2013. RIVEC is used to increase or decrease the real-time ventilation rate to reduce moisture transport into the home or increase moisture removal. This approach was implemented for no-, one- and two-sensor strategies, paired with a variety of control approaches in six humid climates (Miami

  15. Ozone Production With Dielectric Barrier Discharge: Effects of Power Source and Humidity

    KAUST Repository

    Zhang, Xuming

    2016-08-24

    Ozone synthesis in air dielectric barrier discharge (DBD) was studied with an emphasis on the effects of power sources and humidity. Discharge characteristics were investigated to understand the physical properties of plasma and corresponding system performance. It was found that 10-ns pulsed DBD produced a homogeneous discharge mode, while ac DBD yielded an inhomogeneous pattern with many microdischarge channels. At a similar level of the energy density (ED), decreasing the flowrate is more effective in the production of ozone for the cases of the ac DBD, while increased voltage is more effective for the pulsed DBD. Note that the maximum ozone production efficiency (110 g/kWh) was achieved with the pulsed DBD. At the ED of ∼ 85 J/L, the ozone concentrations with dry air were over three times higher than those with the relative humidity of 100% for both the ac DBD and pulsed DBD cases. A numerical simulation was conducted using a global model to understand a detailed chemical role of water vapor to ozone production. It was found HO and OH radicals from water vapor significantly consumed O atoms, resulting in a reduction in ozone production. The global model qualitatively captured the experimental trends, providing further evidence that the primary effect of humidity on ozone production is chemical in nature.

  16. Ultrafast water sensing and thermal imaging by a metal-organic framework with switchable luminescence

    Science.gov (United States)

    Chen, Ling; Ye, Jia-Wen; Wang, Hai-Ping; Pan, Mei; Yin, Shao-Yun; Wei, Zhang-Wen; Zhang, Lu-Yin; Wu, Kai; Fan, Ya-Nan; Su, Cheng-Yong

    2017-06-01

    A convenient, fast and selective water analysis method is highly desirable in industrial and detection processes. Here a robust microporous Zn-MOF (metal-organic framework, Zn(hpi2cf)(DMF)(H2O)) is assembled from a dual-emissive H2hpi2cf (5-(2-(5-fluoro-2-hydroxyphenyl)-4,5-bis(4-fluorophenyl)-1H-imidazol-1-yl)isophthalic acid) ligand that exhibits characteristic excited state intramolecular proton transfer (ESIPT). This Zn-MOF contains amphipathic micropores (<3 Å) and undergoes extremely facile single-crystal-to-single-crystal transformation driven by reversible removal/uptake of coordinating water molecules simply stimulated by dry gas blowing or gentle heating at 70 °C, manifesting an excellent example of dynamic reversible coordination behaviour. The interconversion between the hydrated and dehydrated phases can turn the ligand ESIPT process on or off, resulting in sensitive two-colour photoluminescence switching over cycles. Therefore, this Zn-MOF represents an excellent PL water-sensing material, showing a fast (on the order of seconds) and highly selective response to water on a molecular level. Furthermore, paper or in situ grown ZnO-based sensing films have been fabricated and applied in humidity sensing (RH<1%), detection of traces of water (<0.05% v/v) in various organic solvents, thermal imaging and as a thermometer.

  17. Application of principal component analysis to gas sensing characteristics of Cr0.8Fe0.2NbO4 thick film array.

    Science.gov (United States)

    Sree Rama Murthy, A; Pathak, Dhruv; Sharma, Gautam; Gnanasekar, K I; Jayaraman, V; Umarji, A M; Gnanasekaran, T

    2015-09-10

    The transient changes in resistances of Cr0.8Fe0.2NbO4 thick film sensors towards specified concentrations of H2, NH3, acetonitrile, acetone, alcohol, cyclohexane and petroleum gas at different operating temperatures were recorded. The analyte-specific characteristics such as slopes of the response and retrace curves, area under the curve and sensitivity deduced from the transient curve of the respective analyte gas have been used to construct a data matrix. Principal component analysis (PCA) was applied to this data and the score plot was obtained. Distinguishing one reducing gas from the other is demonstrated based on this approach, which otherwise is not possible by measuring relative changes in conductivity. This methodology is extended for three Cr0.8Fe0.2NbO4 thick film sensor array operated at different temperatures.

  18. Biominerals doped nanocrystalline nickel oxide as efficient humidity sensor: A green approach

    Energy Technology Data Exchange (ETDEWEB)

    John Kennedy, L. [Materials Division, School of Advanced Sciences, Vellore Institute of Technology (VIT) Chennai, Chennai 600 048, Tamil Nadu (India); Magesan, P. [Department of Chemistry, College of Engineering Guindy, Anna University Chennai, Chennai 600 025, Tamil Nadu (India); Judith Vijaya, J. [Catalysis and Nanomaterials Research Laboratory, Department of Chemistry, Loyola College (Autonomous), Chennai 600 034, Tamil Nadu (India); Umapathy, M.J. [Department of Chemistry, College of Engineering Guindy, Anna University Chennai, Chennai 600 025, Tamil Nadu (India); Aruldoss, Udaya, E-mail: udayaevs@yahoo.co.in [Department of Chemistry, College of Engineering Guindy, Anna University Chennai, Chennai 600 025, Tamil Nadu (India)

    2014-12-15

    Graphical abstract: - Highlights: • A new resistive type of sensor was prepared by green synthesis. • The mineral oxide from seed part of Hygrophila spinosa T. Anders (HST) plant is chosen as a dopant in NiO. • The HST plant is found abundantly and commercially available in many countries. • The band gap of NH2 (Ni:HST of 0.5:0.5 weight ratio) sample is greater than prepared bulk NiO due to quantum effects. • The NH2 sample shows remarkable changes in the humidity sensing properties. - Abstract: The simple and green method is adopted for the preparation of biominerals (derived from the Hygrophila spinosa T. Anders plant seeds) doped nanocrystalline NiO. The prepared samples were subjected to instrumental analysis such as XRD, FT-IR, HR-SEM, EDX, UV–vis–DRS techniques. The surface area of all the samples was calculated from the Williamson–Hall's plot. The humidity sensitivity factor (S{sub f}) of the prepared samples was evaluated by two probe dc electrical resistance method at different relative humidity levels. The change in the resistance was observed for the entire sensor samples except pure NiO (NH0). Compared to all the other composition, HST of 0.5% in NiO (NH2 sample) enhances the sensitivity factor (S{sub f}) of about 90,000. The NH2 sample exhibited good linearity, reproducibility and response and recovery time about 210 ± 5 s and 232 ± 4 s, respectively. It is found that the sensitivity largely depends on composition, crystallite size and surface area.

  19. Comparative study of all-printed polyimide humidity sensors with single- and multiwalled carbon nanotube gas-permeable top electrodes

    Science.gov (United States)

    Itoh, Eiji; Yuan, Zihan

    2017-05-01

    We have developed printed capacitive humidity sensors with highly gas permeable carbon nanotube top electrodes using solution techniques. The hydrophobic, porous multiwalled carbon nanotube (MWCNT) network was suitable for gas permeation, and the response of the capacitive humidity sensors was faster than that of a device with a single-walled carbon nanotube (SWCNT) top electrode. The newly developed measurement system consisting of a small measurement chamber, a computer-controlled high-speed solenoid valve, and a mass-flow controller enabled us to vary the ambient relative humidity within 0.1 s. A comparative study of the devices consisting of a 1.1-µm-thick partially fluorinated polyimide dielectric layer and an MWCNT or SWCNT top electrode revealed that the rise time (humidification process) of the device with MWCNTs (0.49 s) in the transient measurement was almost 3 times shorter than that with SWCNTs (1.48 s) owing to the hydrophobic surface of the MWCNTs. A much larger difference was observed during the drying process (recovery time) probably owing to the hydrophilic parts of the SWCNT surface. It was revealed that the response time was almost proportional to the square of the thickness of the polyimide dielectric layer, d, and the sensitivity was inversely proportional to d. The rise time decreased to 0.15 s and a sensitivity per unit area of 12.1 pF %RH-1 cm-2 was obtained in a device with 0.6-µm-thick polyimide and MWCNT top electrodes. This value is suitable for use in high-speed humidity sensors to realize a real-time humidity and breath-sensing measurement system.

  20. Variation of elastic moduli of clays with humidity

    Science.gov (United States)

    Kuila, U.; Prasad, M.

    2012-12-01

    The elastic moduli of clays are highly variable. The reported values of elastic moduli of clays in the literature provide a large range: ranging from 0.15 GPa to 400 GPa. One of the many probable reasons for this variation is different external experimental environments leading to varied amounts of cations and bound water in the interlayers. The clay structure is affected by the kind of water associated with it: free water and bound water, the water in the interlayer. Smectite and mixed-layered illite-smectite (I-S) are capable of retaining significant electrostatic bound water in excess of 200C and can rapidly adsorb moisture from the air depending upon the humidity conditions. These can lead to the variation in their elastic properties. Prior experimental studies of acoustic velocity measurement in compacted clay pellets showed comparable trends (Figure 1) but different velocities for same reported porosity. This can be attributed to the humidity difference in the lab ambient conditions where the measurements were made. Molecular simulation studies on montmorillonite clays shows similar dependence of Young's Modulus on the hydration state of the clays (Pal Bathija 2009). In this paper, we studied the effect of humidity on the elastic properties of compacted pellets of Na-montmorillonite. This can be achieved by placing the Na-montmorillonite pellets in bell jars containing different saturated salt solutions. These salt solutions are used as a standard for relative humidity measurements. Figure 2 shows an experimental set-up used to the experiment. We will present the results of the variation of elastic properties of clays with varying humidity conditions. Preliminary results suggest that acoustic velocities through the compacted Na-montmorillonite pellet depend on the humidity conditions. The varying amount of interlayer clay-bound water and capillary condensation of water in small micropores in clays with varying humidity conditions resulted in the change in the

  1. Dry heat microbial reduction at various humidity conditions

    Science.gov (United States)

    Haberer, Klaus; Schuehlein, Karl-Heinz

    In accordance with interplanetary protection requirements space-craft intended to land on other planets must be of high microbiological purity. High temperatures and long exposure times are needed, to sufficiently treat space craft materials with dry heat. Humidity has been reported to have a major influence on dry heat inactivation of microorganisms. Data obtained in the 1970es show, that dry heat sterilization lethality in the temperature range 104C to 125C increased significantly if environmental humidity during treatment was lowered. However, lethality of the process might no longer be affected by humidity at temperatures under 125C. In order to expand the available body of data, an equipment for simultaneous exposure of multiple inoculated coupons under controlled ambient temperature conditions has been designed. The thermal exposure concept is based on constant heat radiation from an insulated heating block. Exposure chambers are continuously flushed by a pre-heated stream of air of controlled absolute humidity. The systems allows for rapid heating of steel carriers loaded with a defined number of bacterial spores. Relative sterilization effectiveness under changing exposure conditions including heat-up and cool down phases was determined, based on temperature profiles. Parallel exposure of 20 replicate carriers allowed for statistical analysis of the kill time by evaluation of the number of samples showing growth / no growth (fraction negative analysis). Experiments performed at temperatures between 120C and 200C at 5 absolute humidity conditions between 0.1 and 10 g/m of air showed no clear influence of absolute humidity. Pre-equilibration of the spores at relative humidity levels of 15, 48, and 85 percent showed higher sensitivity of the spores pre-incubated under dry conditions.

  2. Influence of fine water droplets to temperature and humidity

    Science.gov (United States)

    Hafidzal, M. H. M.; Hamzah, A.; Manaf, M. Z. A.; Saadun, M. N. A.; Zakaria, M. S.; Roslizar, A.; Jumaidin, R.

    2015-05-01

    Excessively dry air can cause dry skin, dry eyes and exacerbation of medical conditions. Therefore, many researches have been done in order to increase humidity in our environment. One of the ways is by using water droplets. Nowadays, it is well known in market stand fan equipped with water mister in order to increase the humidity of certain area. In this study, the same concept is applied to the ceiling fan. This study uses a model that combines a humidifier which functions as cooler, ceiling fan and scaled down model of house. The objective of this study is to analyze the influence of ceiling fan humidifier to the temperature and humidity in a house. The mechanism of this small model uses batteries as the power source, connected to the fan and the humidifier. The small water tank's function is to store and supply water to the humidifier. The humidifier is used to cool the room by changing water phase to fine water droplets. Fine water droplets are created from mechanism of the humidifier, which is by increasing the kinetic energy of water molecule using high frequency vibration that overcome the holding force between water molecules. Thus, the molecule of water will change to state of gas or mist. The fan is used to spread out the mist of water to surrounding of the room in order to enhance the humidity. Thermocouple and humidity meter are used to measure temperature and humidity in some period of times. The result shows that humidity increases and temperature decreases with time. This application of water droplet can be applied in the vehicles and engine in order to decrease the temperature.

  3. Humidity Dependence of Adhesion for Silane Coated Microcantilevers

    Energy Technology Data Exchange (ETDEWEB)

    DE BOER,MAARTEN P.; MAYER,THOMAS M.; CARPICK,ROBERT W.; MICHALSKE,TERRY A.; SRINIVASAN,U.; MABOUDIAN,R.

    1999-11-09

    This study examines adhesion between silane-coated micromachined surfaces that are exposed to humid conditions. Our quantitative values for interfacial adhesion energies are determined from an in-situ optical measurement of deformations in partly-adhered cantilever beams. We coated micromachined cantilevers with either ODTS (C{sub 18}H{sub 37}SiCl{sub 3}) or FDTS (C{sub 8}F{sub 17}C{sub 2}H{sub 4}SiCl{sub 3}) with the objective of creating hydrophobic surfaces whose adhesion would be independent of humidity. In both cases, the adhesion energy is significantly lower than for uncoated, hydrophilic surfaces. For relative humidities (RH) less than 95% (ODTS) and 80% (FDTS) the adhesion energy was extremely low and constant. In fact, ODTS-coated beams exposed to saturated humidity conditions and long (48 hour) exposures showed only a factor of two increase in adhesion energy. Surprisingly, FDTS coated beams, which initially have a higher contact angle (115{degree}) with water than do ODTS coated beams (112{degree}), proved to be much more sensitive to humidity. The FDTS coated surfaces showed a factor of one hundred increase in adhesion energy after a seven hour exposure to 90% RH. Atomic force microscopy revealed agglomerated coating material after exposed to high RH, suggesting a redistribution of the monolayer film. This agglomeration was more prominent for FDTS than ODTS. These findings suggest a new mechanism for uptake of moisture under high humidity conditions. At high humidities, the silane coatings can reconfigure from a surface to a bulk phase leaving behind locally hydrophilic sites which increase the average measured adhesion energy. In order for the adhesion increase to be observed, a significant fraction of the monolayer must be converted from the surface to the bulk phase.

  4. Smartphones for distributed multimode sensing: biological and environmental sensing and analysis

    Science.gov (United States)

    Feitshans, Tyler; Williams, Robert

    2013-05-01

    Active and Agile Environmental and Biological sensing are becoming obligatory to generate prompt warnings for the troops and law enforcements conducting missions in hostile environments. The traditional static sensing mesh networks which provide a coarse-grained (far-field) measurement of the environmental conditions like air quality, radiation , CO2, etc … would not serve the dynamic and localized changes in the environment, which requires a fine-grained (near-field) sensing solutions. Further, sensing the biological conditions of (healthy and injured) personnel in a contaminated environment and providing a personalized analysis of the life-threatening conditions in real-time would greatly aid the success of the mission. In this vein, under SATE and YATE programs, the research team at AFRL Tec^Edge Discovery labs had demonstrated the feasibility of developing Smartphone applications , that employ a suite of external environmental and biological sensors, which provide fine-grained and customized sensing in real-time fashion. In its current state, these smartphone applications leverage a custom designed modular standalone embedded platform (with external sensors) that can be integrated seamlessly with Smartphones for sensing and further provides connectivity to a back-end data architecture for archiving, analysis and dissemination of real-time alerts. Additionally, the developed smartphone applications have been successfully tested in the field with varied environmental sensors to sense humidity, CO2/CO, wind, etc…, ; and with varied biological sensors to sense body temperature and pulse with apt real-time analysis

  5. [Remote sensing analysis of forest resources characteristics in main ecological restoration counties in the Three-gorge area based on the 2nd-class inventory data].

    Science.gov (United States)

    Wu, Zhao-Ping; Shao, Jing-An; Huang, Zhi-Lin; Su, Wei-Ci; Liao, Ming-Rong

    2014-01-01

    Based on high-resolution SPOT-5 images, combined with topographic (1:10000) calculating terrain-bit index, the distribution characteristics of woodlands in different terrain niches, and the buffer radii of different roads, water bodies and settlements were identified by using ArcGIS space overlay and buffer analysis function. Results showed that woodland resources were abundant, and arbor woodland and shrub land were the main species, which mainly distributed in two mountain areas (Fangdou Mountain, Qiyao Mountain) affected by topographic restriction and woodland natural basis. The woodland terrain niche distribution index showed an overall upward trend with increasing terrain niche gradient, especially for the arbor woodland and shrub land, while the other woodland types presented an opposite trend. The percentage of woodland area occupying the corresponding buffer radius around the roads, waterbodies and settlements had a strong similarity with the woodland terrain niche distribution index. Only around the settlements, bamboo forest, sparse woodland and immature woodland occupied higher percentages of the woodland area of the corresponding buffer radius than that of arbor woodland and shrub land. Woodland distribution was mainly controlled by large landform patterns of mountain features, while the distribution of woodlands in the different terrain niches and the different buffer radii of roads, waterbodies and settlements were driven mainly by duress of human activities under the auspices of the large landform patterns.

  6. Conversational sensing

    Science.gov (United States)

    Preece, Alun; Gwilliams, Chris; Parizas, Christos; Pizzocaro, Diego; Bakdash, Jonathan Z.; Braines, Dave

    2014-05-01

    Recent developments in sensing technologies, mobile devices and context-aware user interfaces have made it pos- sible to represent information fusion and situational awareness for Intelligence, Surveillance and Reconnaissance (ISR) activities as a conversational process among actors at or near the tactical edges of a network. Motivated by use cases in the domain of Company Intelligence Support Team (CoIST) tasks, this paper presents an approach to information collection, fusion and sense-making based on the use of natural language (NL) and controlled nat- ural language (CNL) to support richer forms of human-machine interaction. The approach uses a conversational protocol to facilitate a ow of collaborative messages from NL to CNL and back again in support of interactions such as: turning eyewitness reports from human observers into actionable information (from both soldier and civilian sources); fusing information from humans and physical sensors (with associated quality metadata); and assisting human analysts to make the best use of available sensing assets in an area of interest (governed by man- agement and security policies). CNL is used as a common formal knowledge representation for both machine and human agents to support reasoning, semantic information fusion and generation of rationale for inferences, in ways that remain transparent to human users. Examples are provided of various alternative styles for user feedback, including NL, CNL and graphical feedback. A pilot experiment with human subjects shows that a prototype conversational agent is able to gather usable CNL information from untrained human subjects.

  7. High-resolution Surface Relative Humidity Computation Using MODIS Image in Peninsular Malaysia

    Institute of Scientific and Technical Information of China (English)

    PENG Guangxiong; LI Jing; CHEN Yunhao; Abdul Patah NORIZAN; Liphong TAY

    2006-01-01

    Forest fire is a serious disaster all over the world. The Fire Weather Index (FWI) System can be used in applied forestry as a tool to investigate and manage all types of fire. Relative humidity (RH) is a very important parameter to calculate FWI. However, RH interpolated from meteorological data may not be able to provide precise and confident values for areas between far separated stations. The principal objective of this study is to provide high-resolution RH for FWI using MODIS data. The precipitable water vapor (PW) can be retrieved from MODIS using split window techniques. Four-year-time-series (2000-2003) of 8-day mean PW and specific humidity (Q) of Peninsular Malaysia were analyzed and the statistic expression between PW and Q was developed. The root-mean-square-error (RMSE) of Q estimated by PW is generally less than 0.0004 and the correlation coefficient is 0.90. Based on the experiential formula between PW and Q, surface RH can be computed with combination of auxiliary data such as DEM and air temperature (Ta). The mean absolute errors of the estimated RH in Peninsular Malaysia are less than 5% compared to the measured RH and the correlation coefficient is 0.8219. It is proven to be a simple and feasible model to compute high-resolution RH using remote sensing data.

  8. Nanostructured Ag-zeolite Composites as Luminescence-based Humidity Sensors

    Science.gov (United States)

    Dieu, Bjorn; Roeffaers, Maarten B.J.; Hofkens, Johan

    2016-01-01

    Small silver clusters confined inside zeolite matrices have recently emerged as a novel type of highly luminescent materials. Their emission has high external quantum efficiencies (EQE) and spans the whole visible spectrum. It has been recently reported that the UV excited luminescence of partially Li-exchanged sodium Linde type A zeolites [LTA(Na)] containing luminescent silver clusters can be controlled by adjusting the water content of the zeolite. These samples showed a dynamic change in their emission color from blue to green and yellow upon an increase of the hydration level of the zeolite, showing the great potential that these materials can have as luminescence-based humidity sensors at the macro and micro scale. Here, we describe the detailed procedure to fabricate a humidity sensor prototype using silver-exchanged zeolite composites. The sensor is produced by suspending the luminescent Ag-zeolites in an aqueous solution of polyethylenimine (PEI) to subsequently deposit a film of the material onto a quartz plate. The coated plate is subjected to several hydration/dehydration cycles to show the functionality of the sensing film. PMID:27911397

  9. Self-Activated Transparent All-Graphene Gas Sensor with Endurance to Humidity and Mechanical Bending.

    Science.gov (United States)

    Kim, Yeon Hoo; Kim, Sang Jin; Kim, Yong-Jin; Shim, Yeong-Seok; Kim, Soo Young; Hong, Byung Hee; Jang, Ho Won

    2015-10-27

    Graphene is considered as one of leading candidates for gas sensor applications in the Internet of Things owing to its unique properties such as high sensitivity to gas adsorption, transparency, and flexibility. We present self-activated operation of all graphene gas sensors with high transparency and flexibility. The all-graphene gas sensors which consist of graphene for both sensor electrodes and active sensing area exhibit highly sensitive, selective, and reversible responses to NO2 without external heating. The sensors show reliable operation under high humidity conditions and bending strain. In addition to these remarkable device performances, the significantly facile fabrication process enlarges the potential of the all-graphene gas sensors for use in the Internet of Things and wearable electronics.

  10. Effect of humidity on the filter pressure drop

    Energy Technology Data Exchange (ETDEWEB)

    Vendel, J.; Letourneau, P. [Institut de Protection et de Surete Nucleaire, Gif-sur-Yvette (France)

    1995-02-01

    The effects of humidity on the filter pressure drop have been reported in some previous studies in which it is difficult to draw definite conclusions. These studies show contradictory effects of humidity on the pressure drop probably due to differences in the hygroscopicity of the test aerosols. The objective of this paper is to present experimental results on the evolution of the filter pressure drop versus mass loading, for different test aerosols and relative humidities. Present results are compared to those found in various publication. An experimental device has been designed to measure filter pressure drop as the function of the areal density for relative humidity varying in the range of 9 % to 85 %. Experiments have been conducted with hygroscopic: (CsOH) and nonhygroscopic aerosols (TiO{sub 2}). Cesium hydroxyde (CsOH) of size of 2 {mu} M AMMD has been generated by an ultrasonic generator and the 0.7 {mu}m AMMD titanium oxyde has been dispersed by a {open_quotes}turn-table{close_quotes} generator. As it is noted in the BISWAS`publication [3], present results show, in the case of nonhygroscopic aerosols, a linear relationship of pressure drop to mass loading. For hygroscopic aerosols two cases must be considered: for relative humidity below the deliquescent point of the aerosol, the relationship of pressure drop to mass loading remains linear; above the deliquescent point, the results show a sudden increase in the pressure drop and the mass capacity of the filter is drastically reduced.

  11. Influenza virus transmission is dependent on relative humidity and temperature.

    Directory of Open Access Journals (Sweden)

    Anice C Lowen

    2007-10-01

    Full Text Available Using the guinea pig as a model host, we show that aerosol spread of influenza virus is dependent upon both ambient relative humidity and temperature. Twenty experiments performed at relative humidities from 20% to 80% and 5 degrees C, 20 degrees C, or 30 degrees C indicated that both cold and dry conditions favor transmission. The relationship between transmission via aerosols and relative humidity at 20 degrees C is similar to that previously reported for the stability of influenza viruses (except at high relative humidity, 80%, implying that the effects of humidity act largely at the level of the virus particle. For infected guinea pigs housed at 5 degrees C, the duration of peak shedding was approximately 40 h longer than that of animals housed at 20 degrees C; this increased shedding likely accounts for the enhanced transmission seen at 5 degrees C. To investigate the mechanism permitting prolonged viral growth, expression levels in the upper respiratory tract of several innate immune mediators were determined. Innate responses proved to be comparable between animals housed at 5 degrees C and 20 degrees C, suggesting that cold temperature (5 degrees C does not impair the innate immune response in this system. Although the seasonal epidemiology of influenza is well characterized, the underlying reasons for predominant wintertime spread are not clear. We provide direct, experimental evidence to support the role of weather conditions in the dynamics of influenza and thereby address a long-standing question fundamental to the understanding of influenza epidemiology and evolution.

  12. Uncertainty Analysis in Humidity Measurements by the Psychrometer Method

    Science.gov (United States)

    Chen, Jiunyuan; Chen, Chiachung

    2017-01-01

    The most common and cheap indirect technique to measure relative humidity is by using psychrometer based on a dry and a wet temperature sensor. In this study, the measurement uncertainty of relative humidity was evaluated by this indirect method with some empirical equations for calculating relative humidity. Among the six equations tested, the Penman equation had the best predictive ability for the dry bulb temperature range of 15–50 °C. At a fixed dry bulb temperature, an increase in the wet bulb depression increased the error. A new equation for the psychrometer constant was established by regression analysis. This equation can be computed by using a calculator. The average predictive error of relative humidity was <0.1% by this new equation. The measurement uncertainty of the relative humidity affected by the accuracy of dry and wet bulb temperature and the numeric values of measurement uncertainty were evaluated for various conditions. The uncertainty of wet bulb temperature was the main factor on the RH measurement uncertainty. PMID:28216599

  13. Temperature insensitive hysteresis free highly sensitive polymer optical fiber Bragg grating humidity sensor

    DEFF Research Database (Denmark)

    Woyessa, Getinet; Nielsen, Kristian; Stefani, Alessio

    2016-01-01

    sensitivity and a high hysteresis in the humidity response, in particular when operated at high temperature. PMMA mPOFBGs annealed at high humidity show higher and more linear humidity sensitivity with negligible hysteresis. We also report how annealing at high humidity can blue-shift the FBG wavelength more...

  14. Understanding and predicting bed humidity in fluidized bed granulation.

    Science.gov (United States)

    Hu, Xinhui; Cunningham, John; Winstead, Denita

    2008-04-01

    Bed humidity is a critical parameter that needs to be controlled in a fluidized bed granulation to ensure reliability. To predict and control the bed humidity during the fluidized bed granulation process, a simple model based on the mass conservation of moisture was developed. The moisture mass balance model quantitatively simulates the effects of spray rate, binder solution concentration, airflow rate, inlet air temperature, and dew point on the bed humidity. The model was validated by a series of granulations performed in different scale granulators including Glatt GPCG-1, GPCG-15, and GPCG-60. Good agreement was observed between the theoretical prediction and the measured loss on drying (LOD). The model developed in the current work enables us to choose the appropriate parameters for the fluidized bed granulation and can be used as a valuable tool in process scaling-up.

  15. Humidity evolution (breathing effect) in enclosures with electronics

    DEFF Research Database (Denmark)

    Hygum, Morten Arnfeldt; Popok, Vladimir

    2015-01-01

    Packaging and enclosures used for protecting power electronics operating outdoors are designed to withstand the local climatic and environmental changes. Hermetic enclosures are expensive and therefore other solutions for protecting the electronics from a harsh environment are required. One...... of the dangerous parameters is high humidity of air. Moisture can inevitable reach the electronics either due to diffusion through the wall of an enclosure or small holes, which are designed for electrical or other connections. A driving force for humid air movement is the temperature difference between...... the operating electronics and the surrounding environment. This temperature, thus, gives rise to a natural convection, which we also refer to as breathing. Robust and intelligent enclosure designs must account for this breathing as it can significantly change the humidity distribution in the enclosure...

  16. Hologram-based humidity indicator for domestic and packaging applications

    Science.gov (United States)

    Naydenova, I.; Jallapuram, R.; Toal, V.; Martin, S.

    2007-04-01

    A passive indicator for Relative Humidity based on a photopolymer recorded hologram has been developed. The indicator works on the principle that the wavelength reconstructed by a reflection hologram is dependent on the spacing between the fringe planes of the hologram. As the Relative Humidity changes, the hologram swells or shrinks and the apparent colour of the reconstructed image changes. The response time, operational range and reversibility of the indicator have been studied in a controlled humidity environment. Response times from less than a minute to tens of minutes depending on the holograms physical properties have been measured. Indicators with different operational ranges have been designed. For some indicators the operational range extends from 10% RH to 80% RH. The indicator is completely reversible in its present formulation. It could have an extensive market in industrial monitoring, food packaging and household applications.

  17. Miniature environmental chambers for temperature humidity bias testing of microelectronics.

    Science.gov (United States)

    Hook, Michael David; Mayer, Michael

    2017-03-01

    Environmental chambers are commonly used for reliability testing of microelectronics and other products and materials. These chambers are large, expensive, and limit electrical connectivity to devices under test. In this paper, we present a collection of ten small, low-cost environmental chambers, with humidity control based on mixtures of water and glycerol placed inside the chambers. We demonstrate relative humidities from 44% to 90%, at temperatures from 30 to 85 °C, enabling industry-standard testing at 85% humidity and 85 °C. The division of samples between ten separate chambers allows different conditions to be applied to each sample, in order to quickly characterize the effects of the environment on device reliability, enabling extrapolation to estimate lifetimes in working conditions.

  18. Application of activated charcoal radon collectors in high humidity environments

    Energy Technology Data Exchange (ETDEWEB)

    Iimoto, Takeshi E-mail: iimoto@rcnst.u-tokyo.ac.jp; Tokonami, Shinji; Morishita, Yasuaki; Kosako, Toshiso

    2004-09-01

    Most commercially based activated charcoal radon collectors were designed for use in indoor environments. However, at present, they are often used for research in radon surveys in unique environments, such as in the bathrooms, underground areas, mines, caves and tunnels. In these environments, the relative humidity would be around 100%, and a change in the sensitivity of cpm(Bq m{sup -3}){sup -1}(radon) would occur. For this study, the reduction in the sensitivity of activated charcoal radon collector due to environmental humidity was investigated, and the data correction was discussed. Here, ST-100 (Pico-Rad) was selected as an example of a familiar activated charcoal radon collector. According to our performance test, the humidity of 90% (20 deg. C) resulted in a 15% reduction of the sensitivity for 24 h collection. The ST-100 user should discuss the necessity of data correction by comparing the change of sensitivity with other levels of estimation errors.

  19. Application of activated charcoal radon collectors in high humidity environments.

    Science.gov (United States)

    Iimoto, Takeshi; Tokonami, Shinji; Morishita, Yasuaki; Kosako, Toshiso

    2005-01-01

    Most commercially based activated charcoal radon collectors were designed for use in indoor environments. However, at present, they are often used for research in radon surveys in unique environments, such as in the bathrooms, underground areas, mines, caves and tunnels. In these environments, the relative humidity would be around 100%, and a change in the sensitivity of cpm(Bq m(-3))(-1)(radon) would occur. For this study, the reduction in the sensitivity of activated charcoal radon collector due to environmental humidity was investigated, and the data correction was discussed. Here, ST-100 (Pico-Rad) was selected as an example of a familiar activated charcoal radon collector. According to our performance test, the humidity of 90% (20 degrees C) resulted in a 15% reduction of the sensitivity for 24 h collection. The ST-100 user should discuss the necessity of data correction by comparing the change of sensitivity with other levels of estimation errors.

  20. Humidity Testing of PME and BME Ceramic Capacitors with Cracks

    Science.gov (United States)

    Teverovsky, Alexander A.; Herzberger, Jaemi

    2014-01-01

    Cracks in ceramic capacitors are one of the major causes of failures during operation of electronic systems. Humidity testing has been successfully used for many years to verify the absence of cracks and assure quality of military grade capacitors. Traditionally, only precious metal electrode (PME) capacitors were used in high reliability applications and the existing requirements for humidity testing were developed for this type of parts. With the advance of base metal electrode (BME) capacitors, there is a need for assessment of the applicability of the existing techniques for the new technology capacitors. In this work, variety of different PME and BME capacitors with introduced cracks were tested in humid environments at different voltages and temperatures. Analysis of the test results indicates differences in the behavior and failure mechanisms for BME and PME capacitors and the need for different testing conditions.