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Sample records for thermal optical electrical

  1. Thermal transport of carbon nanotubes and graphene under optical and electrical heating measured by Raman spectroscopy

    Science.gov (United States)

    Hsu, I.-Kai

    This thesis presents systematic studies of thermal transport in individual single walled carbon nanotubes (SWCNTs) and graphene by optical and electrical approaches using Raman spectroscopy. In the work presented from Chapter 2 to Chapter 6, individual suspended CNTs are preferentially measured in order to explore their intrinsic thermal properties. Moreover, the Raman thermometry is developed to detect the temperature of the carbon nanotube (CNT). A parabolic temperature profile is observed in the suspended region of the CNT while a heating laser scans across it, providing a direct evidence of diffusive thermal transport in an individual suspended CNT. Based on the curvature of the temperature profile, we can solve for the ratio of thermal contact resistance to the thermal resistance of the CNT, which spans the range from 0.02 to 17. The influence of thermal contact resistance on the thermal transport in an individual suspended CNT is also studied. The Raman thermometry is carried out in the center of a CNT, while its contact length is successively shortened by an atomic force microscope (AFM) tip cutting technique. By investigating the dependence of the CNT temperature on its thermal contact length, the temperature of a CNT is found to increase dramatically as the contact length is made shorter. This work reveals the importance of manipulating the CNT thermal contact length when adopting CNT as a thermal management material. In using a focused laser to induce heating in a suspended CNT, one open question that remains unanswered is how many of the incident photons are absorbed by the CNT of interest. To address this question, micro-fabricated platinum thermometers, together with micro-Raman spectroscopy are used to quantify the optical absorption of an individual CNT. The absorbed power in the CNT is equal to the power detected by two thermometers at the end of the CNT. Our result shows that the optical absorption lies in the range between 0.03 to 0.44%. In

  2. Thermal Effect on the Structural, Electrical, and Optical Properties of In-Line Sputtered Aluminum Doped Zinc Oxide Films Explored with Thermal Desorption Spectroscopy

    Directory of Open Access Journals (Sweden)

    Shang-Chou Chang

    2014-01-01

    Full Text Available This work investigates the thermal effect on the structural, electrical, and optical properties of aluminum doped zinc oxide (AZO films. The AZO films deposited at different temperatures were measured using a thermal desorption system to obtain their corresponding thermal desorption spectroscopy (TDS. In addition to obtaining information of thermal desorption, the measurement of TDS also has the effect of vacuum annealing on the AZO films. The results of measuring TDS imply part of the doped aluminum atoms do not stay at substituted zinc sites in AZO films. The (002 preferential direction of the AZO films in X-ray diffraction spectra shifts to a lower angle after measurement of TDS. The grain size grows and surface becomes denser for all AZO films after measurement of TDS. The carrier concentration, mobility, and average optical transmittance increase while the electrical resistivity decreases for AZO films after measurement of TDS. These results indicate that the AZO films deposited at 200°C are appropriate selections if the AZO films are applied in device fabrication of heat-produced process.

  3. Study of light-absorbing crystal birefringence and electrical modulation mechanisms for coupled thermal-optical effects.

    Science.gov (United States)

    Zhou, Ji; He, Zhihong; Ma, Yu; Dong, Shikui

    2014-09-20

    This paper discusses Gaussian laser transmission in double-refraction crystal whose incident light wavelength is within its absorption wave band. Two scenarios for coupled radiation and heat conduction are considered: one is provided with an applied external electric field, the other is not. A circular heat source with a Gaussian energy distribution is introduced to present the crystal's light-absorption process. The electromagnetic field frequency domain analysis equation and energy equation are solved to simulate the phenomenon by using the finite element method. It focuses on the influence of different values such as wavelength, incident light intensity, heat transfer coefficient, ambient temperature, crystal thickness, and applied electric field strength. The results show that the refraction index of polarized light increases with the increase of crystal temperature. It decreases as the strength of the applied electric field increases if it is positive. The mechanism of electrical modulation for the thermo-optical effect is used to keep the polarized light's index of refraction constant in our simulation. The quantitative relation between thermal boundary condition and strength of applied electric field during electrical modulation is determined. Numerical results indicate a possible approach to removing adverse thermal effects such as depolarization and wavefront distortion, which are caused by thermal deposition during linear laser absorption.

  4. Thermal, optical, and electrical engineering of an innovative tunable white LED light engine

    Science.gov (United States)

    Trivellin, Nicola; Meneghini, Matteo; Ferretti, Marco; Barbisan, Diego; Dal Lago, Matteo; Meneghesso, Gaudenzio; Zanoni, Enrico

    2014-02-01

    Color temperature, intensity and blue spectrum of the light affects the ganglion receptors in human brain stimulating the human nervous system. With this work we review different methods for obtaining tunable light emission spectra and propose an innovative white LED lighting system. By an in depth study of the thermal, electrical and optical characteristics of GaN and GaP based compound semiconductors for optoelectronics a specific tunable spectra has been designed. The proposed tunable white LED system is able to achieve high CRI (above 95) in a large CCT range (3000 - 5000K).

  5. Synthesis and characterization of oligobenzimidazoles: Electrochemical, electrical, optical, thermal and rectification properties

    Science.gov (United States)

    Anand, Siddeswaran; Muthusamy, Athianna

    2018-03-01

    A series of benzimidazole monomers, (2-(2, 4-dihydroxyphenyl)-1H-benzimidazol-5-yl)(phenyl) methanone (BIKH), 2-(3-ethoxy-2-hydroxyphenyl)-1H-benzo [d]imidazole-5-yl) (phenyl) methanone (BIKE) and 2-(5-bromo-2-hydroxyphenyl)-1H-benzo [d]imidazole-5-yl) (phenyl) methanone (BIKB) were prepared by condensing three substituted aromatic aldehydes with 3, 4-diaminobenzophenone. In aqueous alkaline medium the benzimidazoles were converted in to oligomers by oxidative polycondensation using NaOCl as oxidant. The formation of monomers and oligomers were confirmed with 1H, 13C NMR, FT-IR, and UV-visible spectroscopic techniques. The oligomers were investigated for their optical, electrical, electrochemical and thermal properties. The electrochemical and optical band gaps of monomers and oligomers were calculated using both UV-visible spectroscopy and cyclic voltametry respectively. The band gap values of monomers are compared with band gap values obtained from quantum theoretical calculations with DFT. The electrical conductivity studies of iodine doped and undoped oligomers were done using two point probe technique. It is found that these values are showing good correlation with the charge densities on imidazole nitrogen obtained from Huckel method. The conductivity of oligomers increases with increase in iodine vapour contact time. The dielectric properties of oligomers have been investigated at different temperature and frequency. The dielectric measurement data were used to calculate the AC conductivity and activation energy of oligomers. Oligomer OBIKH is having greater thermal stability due to its number of chain propagation sites than other oligomers and is shown by its high carbines residue of around 60% at 600 °C in thermogravimetric analysis. I-V characteristics of oligobenzimidazole p-n diodes have shown good rectifying nature in the range -4 to 4 V.

  6. A Combined Optical, Thermal and Electrical Performance Study of a V-Trough PV System—Experimental and Analytical Investigations

    Directory of Open Access Journals (Sweden)

    Haitham M. Bahaidarah

    2015-04-01

    Full Text Available The objective of this study was to achieve higher efficiency of a PV system while reducing of the cost of energy generation. Concentration photovoltaics was employed in the present case as it uses low cost reflectors to enhance the efficiency of the PV system and simultaneously reduces the cost of electricity generation. For this purpose a V-trough integrated with the PV system was employed for low concentration photovoltaic (LCPV. Since the electrical output of the concentrating PV system is significantly affected by the temperature of the PV cells, the motivation of the research also included studying the ability to actively cool PV cells to achieve the maximum benefit. The optical, thermal and electrical performance of the V-trough PV system was theoretically modeled and validated with experimental results. Optical modeling of V-trough was carried out to estimate the amount of enhanced absorbed radiation. Due to increase in the absorbed radiation the module temperature was also increased which was predicted by thermal model. Active cooling techniques were studied and the effect of cooling was analyzed on the performance of V-trough PV system. With absorbed radiation and module temperature as input parameters, electrical modeling was carried out and the maximum power was estimated. For the V-trough PV system, experiments were performed for validating the numerical models and very good agreement was found between the two.

  7. Effects of rapid thermal annealing on the optical and electrical properties of InN epilayers

    International Nuclear Information System (INIS)

    Shu, G W; Wu, P F; Liu, Y W; Wang, J S; Shen, J L; Lin, T Y; Pong, P J; Chi, G C; Chang, H J; Chen, Y F; Lee, Y C

    2006-01-01

    We studied the optical and electrical properties of InN epilayers with rapid thermal annealing (RTA). The intensity of the photoluminescence (PL) and the carrier mobility were found to increase as the temperature of RTA was increased. We suggest that the formation of compensating acceptors (indium vacancies) after RTA is responsible for the improvement of the quality in InN. The dependence of the PL emission peak on carrier concentration provides a possible method for estimating the carrier concentration in degenerate InN. (letter to the editor)

  8. Synthesis, growth, spectral, electrical, mechanical and thermal characterization of a potential optical material: γ-glycine single crystal

    Science.gov (United States)

    Sivakumar, N.; Jayavel, R.; Anbalagan, G.; Yadav, R. R.

    2018-06-01

    Gamma glycine, an organic material was grown by slow solvent evaporation method. Conventional polythermal method was employed in the temperature range, 30-50 °C to obtain the solubility and the metastable zonewidth. The crystal and molecular structures were analyzed by X-ray powder diffraction, FT-IR and FT-Raman spectral studies. Optical refractive index was determined by prism coupling technique and was found to be 1.4488. Electrical properties such as ac conductivity and activation energy were studied for different temperatures in the frequency range from 40 Hz to 6 MHz. The dc electrical conductivity was estimated from the Cole-Cole plot and the values were found to be 2.19 × 10-6 Sm-1 at 353K and 1.46 × 10-6 Sm-1 at 373K respectively. Mechanical studies on the grown crystal revealed that the material belongs to soft materials category. Thermal conductivity and specific heat capacities were estimated by Hot Disk Thermal Constants Analyzer.

  9. Thermal and optical performance of encapsulation systems for flat-plate photovoltaic modules

    Science.gov (United States)

    Minning, C. P.; Coakley, J. F.; Perrygo, C. M.; Garcia, A., III; Cuddihy, E. F.

    1981-01-01

    The electrical power output from a photovoltaic module is strongly influenced by the thermal and optical characteristics of the module encapsulation system. Described are the methodology and computer model for performing fast and accurate thermal and optical evaluations of different encapsulation systems. The computer model is used to evaluate cell temperature, solar energy transmittance through the encapsulation system, and electric power output for operation in a terrestrial environment. Extensive results are presented for both superstrate-module and substrate-module design schemes which include different types of silicon cell materials, pottants, and antireflection coatings.

  10. Evaluation of electrical, structural, thermal and optical properties of Co_3O_4 semiconductor

    International Nuclear Information System (INIS)

    Dias, Jeferson A.; Maestrelli, Sylma C.; Morelli, Marcio R.

    2016-01-01

    Among the new semiconductors, the tricobalt tetraoxide is a material of increasing interest; nevertheless, there is a limited number of studies about its properties. Thus, this work has investigated the structural, thermal, optical and electronic properties of Co_3O_4 and its correlation with structure and microstructure. For that, the commercial material was characterized by X-ray diffraction, thermal analysis, diffuse reflectance, FTIR and impedance spectroscopy. The results have shown that the assessed Co_3O_4 has non-stoichiometric spinel structure, presenting a band gap energy capable to completely absorb the visible spectra (1.75 eV). Furthermore, it can be visualized in infrared spectra the bands related to Co-O bonds. The activation energy of electric conduction was 0.35 eV related to the hopping mechanism. Therefore, the results confirm the potentiality of use of Co_3O_4 in optoelectronic devices due to its promising properties for technological utilization. (author)

  11. Electrical and optical properties of zinc oxide: thin films

    International Nuclear Information System (INIS)

    Zuhairusnizam Md Darus; Abdul Jalil Yeop Majlis; Anis Faridah Md Nor; Burhanuddin Kamaluddin

    1992-01-01

    Zinc oxide films have been prepared by high temperature oxidation of thermally evaporated zinc films on glass substrates. The resulting films are characterized using X-ray diffraction, optical absorption and electrical conductivity measurements. These zinc oxide films are very transparent and photoconductive

  12. Electrical transport and optical band gap of NiFe2Ox thin films

    Science.gov (United States)

    Bougiatioti, Panagiota; Manos, Orestis; Klewe, Christoph; Meier, Daniel; Teichert, Niclas; Schmalhorst, Jan-Michael; Kuschel, Timo; Reiss, Günter

    2017-12-01

    We fabricated NiFe2Ox thin films on MgAl2O4(001) by reactive dc magnetron co-sputtering varying the oxygen partial pressure. The fabrication of a material with a variable oxygen deficiency leads to controllable electrical and optical properties which are beneficial for the investigations of the transport phenomena and could, therefore, promote the use of such materials in spintronic and spin caloritronic applications. We used several characterization techniques to investigate the film properties, focusing on their structural, magnetic, electrical, and optical properties. From the electrical resistivity, we obtained the conduction mechanisms that govern the systems in the high and low temperature regimes. We further extracted low thermal activation energies which unveil extrinsic transport mechanisms. The thermal activation energy decreases in the less oxidized samples revealing the pronounced contribution of a large amount of electronic states localized in the band gap to the electrical conductivity. The Hall coefficient is negative and decreases with increasing conductivity as expected for n-type conduction, while the Hall- and the drift mobilities show a large difference. The optical band gaps were determined via ultraviolet-visible spectroscopy. They follow a similar trend as the thermal activation energies, with lower band gap values in the less oxidized samples.

  13. optical, electrical and solid state properties of nano crystalline zinc ...

    African Journals Online (AJOL)

    Vincent

    electrical conductivity decreases as the energy increases while the optical conductivity increases gradually ... reflection coatings on window glass, video screen, camera ... are used for photo-thermal-devices. .... Transmission measurements were performed at normal ... The absorption coefficient (α) was determined from the.

  14. Structural, optical and electrical properties of CuIn{sub 5}S{sub 8} thin films grown by thermal evaporation method

    Energy Technology Data Exchange (ETDEWEB)

    Gannouni, M., E-mail: gm_mounir@yahoo.fr [Laboratoire de Photovoltaique et Materiaux Semi-conducteurs -ENIT BP 37, Le belvedere 1002-Tunis (Tunisia); Kanzari, M. [Laboratoire de Photovoltaique et Materiaux Semi-conducteurs -ENIT BP 37, Le belvedere 1002-Tunis (Tunisia)

    2011-05-19

    Highlights: > In this work, thin films of CuIn{sub 5}S{sub 8} were successfully deposited onto glass substrates by thermal evaporation and annealed in air. > Post-depositional annealing effects on structural, optical and electrical properties of thermal evaporated CuIn{sub 5}S{sub 8} thin films were studied. > The results reported in this work make this material attractive as an absorber material in solar cells applications. - Abstract: Stoichiometric compound of copper indium sulfur (CuIn{sub 5}S{sub 8}) was synthesized by direct reaction of high purity elemental copper, indium and sulfur in an evacuated quartz tube. The phase structure of the synthesized material revealed the cubic spinel structure. The lattice parameter (a) of single crystals was calculated to be 10.667 A. Thin films of CuIn{sub 5}S{sub 8} were deposited onto glass substrates under the pressure of 10{sup -6} Torr using thermal evaporation technique. CuIn{sub 5}S{sub 8} thin films were then thermally annealed in air from 100 to 300 deg. C for 2 h. The effects of thermal annealing on their physico-chemical properties were investigated using X-ray diffraction (XRD), Energy-dispersive X-ray spectroscopy (EDX), scanning electron microscope (SEM), optical transmission and hot probe method. XRD studies of CuIn{sub 5}S{sub 8} thin films showed that as-deposited films were amorphous in nature and transformed into polycrystalline spinel structure with strong preferred orientation along the (3 1 1) plane after the annealing at 200 deg. C. The composition is greatly affected by thermal treatment. From the optical transmission and reflection, an important absorption coefficient exceeds 10{sup 4} cm{sup -1} was found. As increasing the annealing temperature, the optical energy band gap decreases from 1.83 eV for the as-deposited films to 1.43 eV for the annealed films at 300 deg. C. It was found that CuIn{sub 5}S{sub 8} thin film is an n-type semiconductor at 300 deg. C.

  15. Electrically conductive carbon nanofiber/paraffin wax composites for electric thermal storage

    International Nuclear Information System (INIS)

    Zhang Kun; Han Baoguo; Yu Xun

    2012-01-01

    Highlights: ► Carbon nanofiber (CNF)/paraffin wax composite is found to be a promising electric thermal storage material. ► The thermal storage capacity of CNF/paraffin wax composite is five times of traditional electric thermal storage material. ► CNF is shown to be an effective conductive filler for the composite. - Abstract: The research of electric thermal storage (ETS) has attracted a lot of attention recently, which converts off-peak electrical energy into thermal energy and release it later at peak hours. In this study, new electric thermal storage composites are developed by employing paraffin wax as thermal storage media and carbon nanofiber (CNF) as conductive fillers. Electric heating and thermal energy release performances of the CNF/paraffin wax composites are experimentally investigated. Experimental results show that, when the composites are heated to about 70 °C, the developed electrically conductive CNF/paraffin wax composites present a thermal storage capacity of about 280 kJ/kg, which is five times of that of traditional thermal storage medium such as ceramic bricks (54 kJ/kg). The CNF/paraffin wax composites can also effectively store the thermal energy and release the thermal energy in later hours.

  16. Development of Tailorable Electrically Conductive Thermal Control Material Systems

    Science.gov (United States)

    Deshpande, M. S.; Harada, Y.

    1997-01-01

    The optical characteristics of surfaces on spacecraft are fundamental parameters in controlling its temperature. Passive thermal control coatings with designed solar absorptance and infrared emittance properties have been developed and have been in use for some time. In this total space environment, the coating must be stable and maintain its desired optical properties as well as mechanical properties for the course of the mission lifetime. The mission lifetimes are increasing and in our quest to save weight, newer substrates are being integrated which limit electrical grounding schemes. All of this has added to already existing concerns about spacecraft charging and related spacecraft failures or operational failures. The concern is even greater for thermal control surfaces that are very large. One way of alleviating such concerns is to design new thermal control material systems (TCMS) that can help to mitigate charging via providing charge leakage paths. The objective of this program was to develop two types of passive electrically conductive TCMS. The first was a highly absorbing/emitting black surface and the second was a low (alpha(sub s)/epsilon(sub N)) type white surface. The surface resistance goals for the black absorber was 10(exp 4) to 10(exp 9) Omega/square, and for the white surfaces it was 10(exp 6) to 10(exp 10) Omega/square. Several material system concepts were suggested and evaluated for space environment stability and electrical performance characterization. Our efforts in designing and evaluating these material systems have resulted in several developments. New concepts, pigments and binders have been developed to provide new engineering quality TCMS. Some of these have already found application on space hardware, some are waiting to be recognized by thermal designers, and some require further detailed studies to become state-of-the-art for future space hardware and space structures. Our studies on baseline state-of-the-art materials and

  17. Holography and thermalization in optical pump-probe spectroscopy

    Science.gov (United States)

    Bagrov, A.; Craps, B.; Galli, F.; Keränen, V.; Keski-Vakkuri, E.; Zaanen, J.

    2018-04-01

    Using holography, we model experiments in which a 2 +1 D strange metal is pumped by a laser pulse into a highly excited state, after which the time evolution of the optical conductivity is probed. We consider a finite-density state with mildly broken translation invariance and excite it by oscillating electric field pulses. At zero density, the optical conductivity would assume its thermalized value immediately after the pumping has ended. At finite density, pulses with significant dc components give rise to slow exponential relaxation, governed by a vector quasinormal mode. In contrast, for high-frequency pulses the amplitude of the quasinormal mode is strongly suppressed, so that the optical conductivity assumes its thermalized value effectively instantaneously. This surprising prediction may provide a stimulus for taking up the challenge to realize these experiments in the laboratory. Such experiments would test a crucial open question faced by applied holography: are its predictions artifacts of the large N limit or do they enjoy sufficient UV independence to hold at least qualitatively in real-world systems?

  18. Solar energy thermally powered electrical generating system

    Science.gov (United States)

    Owens, William R. (Inventor)

    1989-01-01

    A thermally powered electrical generating system for use in a space vehicle is disclosed. The rate of storage in a thermal energy storage medium is controlled by varying the rate of generation and dissipation of electrical energy in a thermally powered electrical generating system which is powered from heat stored in the thermal energy storage medium without exceeding a maximum quantity of heat. A control system (10) varies the rate at which electrical energy is generated by the electrical generating system and the rate at which electrical energy is consumed by a variable parasitic electrical load to cause storage of an amount of thermal energy in the thermal energy storage system at the end of a period of insolation which is sufficient to satisfy the scheduled demand for electrical power to be generated during the next period of eclipse. The control system is based upon Kalman filter theory.

  19. Effect of succinonitrile on electrical, structural, optical, and thermal properties of [poly(ethylene oxide)-succinonitrile]/LiI–I2 redox-couple solid polymer electrolyte

    International Nuclear Information System (INIS)

    Gupta, Ravindra Kumar; Rhee, Hee-Woo

    2012-01-01

    Effect of succinonitrile on electrical, structural, optical, and thermal properties of [poly(ethylene oxide)-succinonitrile]/LiI–I 2 redox-couple solid polymer electrolyte is reported for the first time. For the poly(ethylene oxide)-succinonitrile blend-based electrolyte electrical conductivity was noted as high as ∼3 × 10 −4 S cm −1 at 25 °C, which is an order of magnitude higher than that of pure poly(ethylene oxide)-based electrolyte. It also exhibited relatively better pseudo-activation energy (∼0.08 eV). X-ray diffractometry, polarized optical microscopy, and differential scanning calorimetry studies revealed that succinonitrile is helpful in reducing the poly(ethylene oxide) crystallinity due to its plasticizing property. FT-IR study showed significant modification of the poly(ethylene oxide) chain conformation due to the succinonitrile.

  20. Electrical and optical study of transparent V-based oxide semiconductors prepared by magnetron sputtering under different conditions

    Directory of Open Access Journals (Sweden)

    E. Prociow

    2011-04-01

    Full Text Available This work is focused on structural, optical and electrical behaviors of vanadium-based oxide thin films prepared by magnetron sputtering under different conditions. Thin films have been deposited on glass substrates from metallic vanadium target at low sputtering pressure. Different working gases: argon/oxygen mixture, and especially pure oxygen gas, have been applied. Results of X-ray diffraction together with optical transmission and temperature- dependent electrical resistivity measurements have been presented. Transmission coefficient, cut-off wavelength and the width of the optical band gap have been calculated from optical measurements. The d.c. resistivity values at room temperature and thermal activation energy have been obtained from electrical investigations. The influence of sputtering process conditions on optical and electrical properties has been discussed.

  1. Optical and electrical properties of thermally evaporated In49Se48Sn3 films

    International Nuclear Information System (INIS)

    Salem, A.M.; El-Gendy, Y.A.; El-Sayad, E.A.

    2009-01-01

    Nearly stoichiometric thin films of In 49 Se 48 Sn 3 were deposited at room temperature, by conventional thermal evaporation of the presynthesized materials, onto precleaned glass substrates. The microstructural studies on the as-deposited and annealed films, using transmission electron microscopy and diffraction (TEMD), revealed that the as-deposited films are amorphous in nature, while those annealed at 498 K are crystalline. The optical properties of the investigated films were determined from the transmittance and reflectance data, in the spectral range 650-2500 nm. An analysis of the optical absorption spectra revealed a non-direct energy gap characterizing the amorphous films, while both allowed and forbidden direct energy gaps characterized the crystalline films. The electrical resistance of the deposited films was carried out during heating and cooling cycles in the temperature range 300-600 K. The results show an irreproducible behavior, while after crystallization the results become reproducible. The analysis of the temperature dependence of the resistance (ln(R) vs. 1000/T) for crystalline films shows two straight lines corresponding to both extrinsic and intrinsic conduction. The room temperature I-V characteristics of the as-deposited films sandwiched between similar Ag metal electrodes shows an ohmic behavior, while non-ohmic behavior attributed to space charge limited conduction has been observed when the films are sandwiched between dissimilar Ag/Al metal electrodes.

  2. Graphene derivatives/Fe_3O_4/polymer nanocomposite films: Optical and electrical properties

    International Nuclear Information System (INIS)

    Hatel, Rhizlane; Goumri, Meryem; Ratier, Bernard; Baitoul, Mimouna

    2017-01-01

    This paper reports a simple solution casting method for the preparation of nanocomposite films in which graphene oxide (GO)/Fe_3O_4 nanocomposites are incorporated into poly (vinyl alcohol) (PVA) matrix. The films obtained with different weight percent of GO/Fe_3O_4 (0.5, 0.7 and 1 wt%) are subjected an in situ chemical and thermal reduction in order to explore the evolution and interactions between these components under different treatments and get an insight into on how this can affects the optical and electrical properties of these nanocomposites. Characterization was carried out using, UV–Vis absorption, Photoluminescence, electrical conductivity measurements, Fourier transform infrared spectroscopy (FT-IR) and Raman spectroscopy. Strong covalent functionalization occurs between the polymer and graphene derivatives (GD)/Fe_3O_4 hybrids. The experimental results obtained for our nanocomposites films exhibit significant enhancement in properties highlighted the efficiency of the in situ thermal reduction. The high absorption with strong photoluminescence and electrical conductivity achieved might promote these nanocomposites for opto-electronic devices in near future. - Highlights: • Novel inorganic-organic hybrid flexible films were successfully prepared. • Good interfacial interaction between the graphene/Fe_3O_4 and the hydroxyl-rich PVA. • Optical and electrical properties of Graphene Derivatives/Fe_3O_4/PVA were investigated. • Thermally reduced GO/Fe_3O_4/PVA films show high absorption and strong photoluminescence.

  3. Effects of Rapid Thermal Annealing on the Structural, Electrical, and Optical Properties of Zr-Doped ZnO Thin Films Grown by Atomic Layer Deposition

    Directory of Open Access Journals (Sweden)

    Jingjin Wu

    2016-08-01

    Full Text Available The 4 at. % zirconium-doped zinc oxide (ZnO:Zr films grown by atomic layer deposition (ALD were annealed at various temperatures ranging from 350 to 950 °C. The structural, electrical, and optical properties of rapid thermal annealing (RTA treated ZnO:Zr films have been evaluated to find out the stability limit. It was found that the grain size increased at 350 °C and decreased between 350 and 850 °C, while creeping up again at 850 °C. UV–vis characterization shows that the optical band gap shifts towards larger wavelengths. The Hall measurement shows that the resistivity almost keeps constant at low annealing temperatures, and increases rapidly after treatment at 750 °C due to the effect of both the carrier concentration and the Hall mobility. The best annealing temperature is found in the range of 350–550 °C. The ZnO:Zr film-coated glass substrates show good optical and electrical performance up to 550 °C during superstrate thin film solar cell deposition.

  4. Plasmonic Gold Nanorod Dispersions with Electrical and Optical Tunability

    Science.gov (United States)

    Grabowski, Christopher; Mahoney, Clare; Park, Kyoungweon; Jawaid, Ali; White, Timothy; Vaia, Richard

    The transmissive, absorptive, electrical, and thermal properties of plasmonic gold nanorods (NRs) have led to their employment in a broad range of applications. These electro-optical properties - governed by their size, shape, and composition - are widely and precisely tunable during synthesis. Gold NRs show promise for large scale optical elements as they have been demonstrated to align faster than liquid crystal films (μs) at low fields (1 V/ μm). Successfully dispersing a high volume fraction of gold NRs requires a strategy to control particle-particle separation and thus avoid aggregation. Herein, we discuss the role of theta temperature and the ability to swell or collapse the chains of polymer-grafted gold NRs to alter the interaction potential between particles. UV-Vis spectroscopy, scattering, and electrical susceptibility characterization methods were employed to determine nanoparticle dispersion along with the degree of gold NR alignment. The development of new agile photonic materials, controllable with both light and electric fields, will help address emerging needs in laser hardening (agile filters) and variable transmission visors.

  5. Studies on the Electrical and Optical Properties of Magnesium Phthalocyanine Thin Films

    Directory of Open Access Journals (Sweden)

    T. G. Gopinathan

    2004-01-01

    Full Text Available Thin films of Magnesium Phthalocyanine (MgPc are prepared by thermal evaporation technique at a base pressure of 10-5 m.bar on thoroughly cleaned glass substrates kept at different constant temperatures. Films of thickness 2400 A.U. coated at room temperature are subjected to post deposition annealing in air by keeping them in a furnace at different constant temperatures, for one hour. The electrical conductivity studies are conducted in the temperature range 300 K to 525 K. The electrical conductivity is plotted as a function of absolute temperature. The conduction mechanism is observed to be hopping. The thermal activation energy is calculated in different cases and is observed to vary with substrate temperature and annealing temperature. A phase change is observed due to post-deposition annealing at around 523 K. The optical absorption studies are done in the UV-Visible region. The optical band gap energies of the samples are calculated.

  6. Electric Motor Thermal Management

    Energy Technology Data Exchange (ETDEWEB)

    Bennion, Kevin S [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

    2017-09-01

    Thermal management enables more efficient and cost-effective motors. This Annual Merit Review presentation describes the technical accomplishments and progress in electric motor thermal management R&D over the last year. This project supports a broad industry demand for data, analysis methods, and experimental techniques to improve and better understand motor thermal management.

  7. Thermo-optically tuned photonic resonators with concurrent electrical connection and thermal isolation

    Science.gov (United States)

    Lentine, Anthony L.; Kekatpure, Rohan Deodatta; Zortman, William A.; Savignon, Daniel J.

    2016-06-14

    A photonic resonator system is designed to use thermal tuning to adjust the resonant wavelength of each resonator in the system, with a separate tuning circuit associated with each resonator so that individual adjustments may be made. The common electrical ground connection between the tuning circuits is particularly formed to provide thermal isolation between adjacent resonators by including a capacitor along each return path to ground, where the presence of the capacitor's dielectric material provides the thermal isolation. The use of capacitively coupling necessarily requires the use of an AC current as an input to the heater element (conductor/resistor) of each resonator, where the RMS value of the AC signal is indicative of the amount of heat that is generated along the element and the degree of wavelength tuning that is obtained.

  8. Electrical power system integrated thermal/electrical system simulation

    International Nuclear Information System (INIS)

    Freeman, W.E.

    1992-01-01

    This paper adds thermal properties to previously developed electrical Saber templates and incorporates these templates into a functional Electrical Power Subsystem (EPS) simulation. These combined electrical and thermal templates enable the complete and realistic simulation of a vehicle EPS on-orbit. Applications include on-orbit energy balance determinations for system load changes, initial array and battery EPS sizing for new EPS development, and array and battery technology trade studies. This effort proves the versatility of the Saber simulation program in handling varied and complex simulations accurately and in a reasonable amount of computer time. 9 refs

  9. Electric Motor Thermal Management R&D. Annual Report

    Energy Technology Data Exchange (ETDEWEB)

    Bennion, Kevin [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2016-04-01

    With the push to reduce component volumes, lower costs, and reduce weight without sacrificing performance or reliability, the challenges associated with thermal management increase for power electronics and electric motors. Thermal management for electric motors will become more important as the automotive industry continues the transition to more electrically dominant vehicle propulsion systems. The transition to more electrically dominant propulsion systems leads to higher-power duty cycles for electric drive systems. Thermal constraints place significant limitations on how electric motors ultimately perform, and as thermal management improves, there will be a direct trade-off between motor performance, efficiency, cost, and the sizing of electric motors to operate within the thermal constraints. The goal of this research project is to support broad industry demand for data, analysis methods, and experimental techniques to improve and better understand motor thermal management. Work in FY15 focused on two areas related to motor thermal management: passive thermal performance and active convective cooling. Passive thermal performance emphasized the thermal impact of materials and thermal interfaces among materials within an assembled motor. The research tasks supported the publication of test methods and data for thermal contact resistances and direction-dependent thermal conductivity within an electric motor. Active convective cooling focused on measuring convective heat-transfer coefficients using automatic transmission fluid (ATF). Data for average convective heat transfer coefficients for direct impingement of ATF jets was published. Also, experimental hardware for mapping local-scale and stator-scale convective heat transfer coefficients for ATF jet impingement were developed.

  10. Optical emission from a small scale model electric arc furnace in 250-600 nm region.

    Science.gov (United States)

    Mäkinen, A; Niskanen, J; Tikkala, H; Aksela, H

    2013-04-01

    Optical emission spectroscopy has been for long proposed for monitoring and studying industrial steel making processes. Whereas the radiative decay of thermal excitations is always taking place in high temperatures needed in steel production, one of the most promising environment for such studies are electric arc furnaces, creating plasma in excited electronic states that relax with intense characteristic emission in the optical regime. Unfortunately, large industrial scale electric arc furnaces also present a challenging environment for optical emission studies and application of the method is not straightforward. To study the usability of optical emission spectroscopy in real electric arc furnaces, we have developed a laboratory scale DC electric arc furnace presented in this paper. With the setup, optical emission spectra of Fe, Cr, Cr2O3, Ni, SiO2, Al2O3, CaO, and MgO were recorded in the wavelength range 250-600 nm and the results were analyzed with the help of reference data. The work demonstrates that using characteristic optical emission, obtaining in situ chemical information from oscillating plasma of electric arc furnaces is indeed possible. In spite of complications, the method could possibly be applied to industrial scale steel making process in order to improve its efficiency.

  11. Numerical study on optical and electric-thermal performance for solar concentrating PV/T air system

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Hybrid photovoltaic/thermal(PV/T)system with solar concentrator is an effective way to improve solar energy conversion efficiency.In this work,a single-pass PV/T air system with a three-trough compound parabolic concentrator(CPC)of concentration ratio 2.0 is designed and the solar incident distributions at the solar cell surface are calculated by ray tracing method.Based on energy balance,the heat transfer models of all main components in this system are developed.The effects of some main designing and operational parameters on the electric-thermal performance of the system are analyzed. The results show that the solar radiation intensity can be higher than 1200 W/m 2 at most area of the cell surface.The temperature of the air and cell surface increases along the length of the system.Thus the system efficiency of the CPC is higher than that of the system without the CPC.The thermal efficiency, exergy and electrical efficiency of this CPC system increase with increasing of the air mass flow rate and the length of the system.With increasing packing fraction the electrical efficiency increases,but the thermal efficiency decreases.The exergy efficiency increases slightly with the packing fraction rising.The data obtained in this work are valuable for the design and operation for this kind of solar concentrating PV/T systems.

  12. Effect of Mn content on structural, optical, opto-thermal and electrical properties of ZnO:Mn sprayed thin films compounds

    International Nuclear Information System (INIS)

    Mimouni, R.; Kamoun, O.; Yumak, A.; Mhamdi, A.; Boubaker, K.; Petkova, P.; Amlouk, M.

    2015-01-01

    Highlights: • Proposing an original explanation to the difference between manganese-doped zinc oxide and undoped behavior. • Presenting an original effective electrical and fluorescence-related calculation scheme. • Outlining original AC–DC investigation protocol. - Abstract: Manganese-doped zinc oxide thin films (ZnO:Mn) at different percentages (0–3%) were deposited on glass substrates using a chemical spray technique. The effects of manganese element content on structural, optical, opto-thermal and electrical conductivity of ZnO:Mn thin films were investigated by means of X-ray diffraction, optical measurement, Photoluminescence spectroscopy and impedance spectroscopy. XRD analysis revealed that all films consist of single phase ZnO and were well crystallized in würtzite phase with the crystallites preferentially oriented towards (0 0 2) direction parallel to c-axis. Doping manganese resulted in a slight decrease in the optical band gap energy of the films and a noticeably change in optical constants. The UV peak positions for ZnO:Mn samples slightly red shift to the longer wavelength in comparison with the pure ZnO which can be attributed to the change in the acceptor level induced by the substitutional Mn 2+ and the band-gap narrowing of ZnO with the Mn dopant. We have performed original AC and DC conductivity studies inspired from Jonscher and small polaron models. These studies helped establishing significant correlation between temperature and activation energy and Mn content. From the spectroscopy impedance analysis we investigated the frequency relaxation phenomenon and the circuit equivalent circuit of such thin films. Finally, all results have been discussed, as an objective of the actual work, in terms of the manganese doping concentration

  13. Surface plasmon resonances, optical properties, and electrical conductivity thermal hystersis of silver nanofibers produced by the electrospinning technique.

    Science.gov (United States)

    Barakat, Nasser A M; Woo, Kee-Do; Kanjwal, Muzafar A; Choi, Kyung Eun; Khil, Myung Seob; Kim, Hak Yong

    2008-10-21

    In the present study, silver metal nanofibers have been successfully prepared by using the electrospinning technique. Silver nanofibers have been produced by electrospinning a sol-gel consisting of poly(vinyl alcohol) and silver nitrate. The dried nanofiber mats have been calcined at 850 degrees C in an argon atmosphere. The produced nanofibers do have distinct plasmon resonance compared with the reported silver nanoparticles. Contrary to the introduced shapes of silver nanoparticles, the nanofibers have a blue-shifted plasmon resonance at 330 nm. Moreover, the optical properties study indicated that the synthesized nanofibers have two band gap energies of 0.75 and 2.34 eV. An investigation of the electrical conductivity behavior of the obtained nanofibers shows thermal hystersis. These privileged physical features greatly widen the applications of the prepared nanofibers in various fields.

  14. Electrical and optical properties of thermally-evaporated thin films from A2[TiO(C2O4)2] (A = K, PPh4) and 1,8-dihydroxyanthraquinone

    International Nuclear Information System (INIS)

    Carbia-Ruelas, E.; Sanchez-Vergara, M.E.; Garcia-Montalvo, V.; Morales-Saavedra, O.G.; Alvarez-Bada, J.R.

    2011-01-01

    In this work, the synthesis of molecular materials formed from A 2 [TiO(C 2 O 4 ) 2 ] (A = K, PPh4) and 1,8 dihydroxyanthraquinone is reported. The synthesized materials were characterized by atomic force microscopy (AFM), infrared (IR) and ultraviolet-visible (UV-vis) spectroscopy. IR spectroscopy showed that the molecular-material thin-films, deposited by vacuum thermal evaporation, exhibit the same intra-molecular vibration modes as the starting powders, which suggests that the thermal evaporation process does not alter the initial chemical structures. Electrical transport properties were studied by dc conductivity measurements. The electrical activation energies of the complexes, which were in the range of 0.003-1.16 eV, were calculated from Arrhenius plots. Optical absorption studies in the wavelength range of 190-1090 nm at room temperature showed that the optical band gaps of the thin films were around 1.9-2.3 eV for direct transitions Eg d . The cubic NLO effects were substantially enhanced for materials synthesized from K 2 [TiO(C 2 O 4 ) 2 ], where χ (3) (-3ω; ω, ω, ω) values in the promising range of 10 -12 esu have been evaluated.

  15. Thermal burn and electrical injuries among electric utility workers, 1995-2004.

    Science.gov (United States)

    Fordyce, Tiffani A; Kelsh, Michael; Lu, Elizabeth T; Sahl, Jack D; Yager, Janice W

    2007-03-01

    This study describes the occurrence of work-related injuries from thermal-, electrical- and chemical-burns among electric utility workers. We describe injury trends by occupation, body part injured, age, sex, and circumstances surrounding the injury. This analysis includes all thermal, electric, and chemical injuries included in the Electric Power Research Institute (EPRI) Occupational Health and Safety Database (OHSD). There were a total of 872 thermal burn and electric shock injuries representing 3.7% of all injuries, but accounting for nearly 13% of all medical claim costs, second only to the medical costs associated with sprain- and strain-related injuries (38% of all injuries). The majority of burns involved less than 1 day off of work. The head, hands, and other upper extremities were the body parts most frequently injured by burns or electric shocks. For this industry, electric-related burns accounted for the largest percentage of burn injuries, 399 injuries (45.8%), followed by thermal/heat burns, 345 injuries (39.6%), and chemical burns, 51 injuries (5.8%). These injuries also represented a disproportionate number of fatalities; of the 24 deaths recorded in the database, contact with electric current or with temperature extremes was the source of seven of the fatalities. High-risk occupations included welders, line workers, electricians, meter readers, mechanics, maintenance workers, and plant and equipment operators.

  16. Thermal and Electrical Conductivities of a Three-Dimensional Ideal Anyon Gas with Fractional Exclusion Statistics

    International Nuclear Information System (INIS)

    Qin Fang; Wen Wen; Chen Ji-Sheng

    2014-01-01

    The thermal and electrical transport properties of an ideal anyon gas within fractional exclusion statistics are studied. By solving the Boltzmann equation with the relaxation-time approximation, the analytical expressions for the thermal and electrical conductivities of a three-dimensional ideal anyon gas are given. The low-temperature expressions for the two conductivities are obtained by using the Sommerfeld expansion. It is found that the Wiedemann—Franz law should be modified by the higher-order temperature terms, which depend on the statistical parameter g for a charged anyon gas. Neglecting the higher-order terms of temperature, the Wiedemann—Franz law is respected, which gives the Lorenz number. The Lorenz number is a function of the statistical parameter g. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  17. Influence of PEG coating on optical and thermal response of gold nanoshperes and nanorods

    Science.gov (United States)

    Chen, Qin; Ren, Yatao; Qi, Hong; Ruan, Liming

    2018-06-01

    PEGylation is widely applied as a surface modification method for nanoparticles in biomedical applications to improve their biological properties, including biocompatibility and immunogenicity. In most of its biomedical applications, nanoparticles are served as optical or thermal contrast agents. Therefore, the impact of poly (ethylene glycol) (PEG) coating thickness on the optical and thermal properties of nanoparticles needs to be further investigated. In the present work, we studied two kinds of commonly used nanoparticles, including nanosphere and nanorod. The temperature and electric fields are obtained for nanoparticles with different PEG coating thicknesses. It is found that the change of PEG coating thickness on gold nanospheres only has impact on the absolute value of maximum absorption and scattering efficiencies, which barely influences the LSPR wavelength λmax and other optical and thermal characteristics. In contrast, for nanorod, the maximum efficiencies are barely influenced by the variation of PEG coating thickness. On the other hand, the localized surface plasmon resonance wavelength has an evident red shift with the increasing of PEG coating thickness. The maximum absorption efficiency is a way to evaluate the energy dissipation rate, which decides the scale of the heat source induced by nanoparticles. These findings are crucial for the accurate prediction of optical and thermal properties of nanoparticles in biomedical application. The present work also presents a possible way to manipulate the optical and thermal behaviors of nanoparticles in the application of biomedicine without changing the morphology of nanoparticles.

  18. Numerical study on optical and electric-thermal performance for solar concentrating PV/T air system

    Institute of Scientific and Technical Information of China (English)

    SUN Jian; SHI MingHeng

    2009-01-01

    Hybrid photovoltaic/thermsl(PV/T)system with solar concentrator is an effective way to improve solar energy conversion efficiency.In this work,a single-pass PV/T sir system with a three-trough compound parabolic concentrator(CPC)of concentration ratio 2.0 is designed and the solar incident distributions at the solar cell surface are calculated by ray tracing method.Based on energy balance,the heat transfer models of all main components in this system are developed.The effects of some main designing and operational parameters on the electric-thermal performance of the system are analyzed.The results show that the solar radiation intensity can be higher than 1200 W/m~2 at most area of the cell surface.The temperature of the air and cell surface increases along the length of the system.Thus the system efficiency of the CPC is higher than that of the system without the CPC.The thermal efficiency,exergy and electrical efficiency of this CPC system increase with increasing of the air mass flow rate and the length of the system.With increasing packing fraction the electrical efficiency increases,but the thermal efficiency decreases.The exergy efficiency increases slightly with the packing fraction rising.The data obtained in this work are valuable for the design and operation for this kind of solar concentrating PV/T systems.

  19. Thermal and electrical conductivities of Cd-Zn alloys

    International Nuclear Information System (INIS)

    Saatci, B; Ari, M; Guenduez, M; Meydaneri, F; Bozoklu, M; Durmus, S

    2006-01-01

    The composition and temperature dependences of the thermal and electrical conductivities of three different Cd-Zn alloys have been investigated in the temperature range of 300-650 K. Thermal conductivities of the Cd-Zn alloys have been determined by using the radial heat flow method. It has been found that the thermal conductivity decreases slightly with increasing temperature and the data of thermal conductivity are shifting together to the higher values with increasing Cd composition. In addition, the electrical measurements were determined by using a standard DC four-point probe technique. The resistivity increases linearly and the electrical conductivity decreases exponentially with increasing temperature. The resistivity and electrical conductivity are independent of composition of Cd and Zn. Also, the temperature coefficient of Cd-Zn alloys has been determined, which is independent of composition of Cd and Zn. Finally, Lorenz number has been calculated using the thermal and electrical conductivity values at 373 and 533 K. The results satisfy the Wiedemann-Franz (WF) relation at T 373 K), the WF relation could not hold and the phonon component contribution of thermal conductivity dominates the thermal conduction

  20. Graphene derivatives/Fe{sub 3}O{sub 4}/polymer nanocomposite films: Optical and electrical properties

    Energy Technology Data Exchange (ETDEWEB)

    Hatel, Rhizlane [University Sidi Mohammed Ben Abdellah, Faculty of Sciences Dhar El Mahraz, Laboratory of Solid State Physics, Group of Polymers and Nanomaterials, PO Box 1796, Atlas, Fez 30000 (Morocco); Goumri, Meryem [University Sidi Mohammed Ben Abdellah, Faculty of Sciences Dhar El Mahraz, Laboratory of Solid State Physics, Group of Polymers and Nanomaterials, PO Box 1796, Atlas, Fez 30000 (Morocco); XLIM UMR 7252- University of Limoges/CNRS, 123 Avenue Albert Thomas, 87060 Limoges Cedex (France); Ratier, Bernard [XLIM UMR 7252- University of Limoges/CNRS, 123 Avenue Albert Thomas, 87060 Limoges Cedex (France); Baitoul, Mimouna, E-mail: baitoul@yahoo.fr [University Sidi Mohammed Ben Abdellah, Faculty of Sciences Dhar El Mahraz, Laboratory of Solid State Physics, Group of Polymers and Nanomaterials, PO Box 1796, Atlas, Fez 30000 (Morocco)

    2017-06-01

    This paper reports a simple solution casting method for the preparation of nanocomposite films in which graphene oxide (GO)/Fe{sub 3}O{sub 4} nanocomposites are incorporated into poly (vinyl alcohol) (PVA) matrix. The films obtained with different weight percent of GO/Fe{sub 3}O{sub 4} (0.5, 0.7 and 1 wt%) are subjected an in situ chemical and thermal reduction in order to explore the evolution and interactions between these components under different treatments and get an insight into on how this can affects the optical and electrical properties of these nanocomposites. Characterization was carried out using, UV–Vis absorption, Photoluminescence, electrical conductivity measurements, Fourier transform infrared spectroscopy (FT-IR) and Raman spectroscopy. Strong covalent functionalization occurs between the polymer and graphene derivatives (GD)/Fe{sub 3}O{sub 4} hybrids. The experimental results obtained for our nanocomposites films exhibit significant enhancement in properties highlighted the efficiency of the in situ thermal reduction. The high absorption with strong photoluminescence and electrical conductivity achieved might promote these nanocomposites for opto-electronic devices in near future. - Highlights: • Novel inorganic-organic hybrid flexible films were successfully prepared. • Good interfacial interaction between the graphene/Fe{sub 3}O{sub 4} and the hydroxyl-rich PVA. • Optical and electrical properties of Graphene Derivatives/Fe{sub 3}O{sub 4}/PVA were investigated. • Thermally reduced GO/Fe{sub 3}O{sub 4}/PVA films show high absorption and strong photoluminescence.

  1. Thermal and optical study of parabolic trough collectors of Shiraz solar power plant

    Energy Technology Data Exchange (ETDEWEB)

    Mokhtari, A.; Yaghoubi, M.; Vadiee, A.; Hessami, R. [Shiraz Univ, Shiraz (Iran, Islamic Republic of); Kanan, P. [Renewable Energy Organization of Iran, Tehran (Iran, Islamic Republic of)

    2007-07-01

    The construction of the first 250 KW solar power plant in Shiraz, Iran was discussed. The power plant is comprised of a steam and oil cycle which includes 48 parabolic trough collectors (PTCs). Solar thermal power plants based on PTCs are currently the most successful solar technologies for electricity generation. These power plants are basically composed of a solar collector field and a power block. The solar collector field is designed to collect heat from the sun which it is continuously tracking. The reflecting surface concentrates direct solar radiation in the optical focal line of the collector where the heat collecting element (HCE) is located. The HCE absorbs the reflected energy and transmits it to the heat transfer fluid which is pumped to the conventional power block where electricity is generated. There is potential to significantly increase the performance and reduce the cost of PTC solar thermal electric technologies. However, it is necessary to characterize the optical performance and determine the optical losses of PTCs in order to improve the optical efficiency of these systems and to ensure the desired power quality. In this study, thermocouple sensors were used to record the collector oil inlet and outlet temperature along with the ambient temperature in the PTCs. In addition to measuring the wind speed, the solar beam radiation intensity was measured along with the oil's mass flow rate. All parameters were measured as a function of time. Based on these measurements, the intercept factor value and collector's incidence angle was determined and compared with other large size constructed commercial parabolic collectors. The maximum beam radiation during the experimental period was 735 2mW. The useful heat gain and the collector's instantaneous efficiency as a whole was evaluated on an hourly basis. All these parameters were strongly influenced by the incident beam radiation and found to follow each other. The optical and thermal

  2. Optical-Thermal Response of Laser-Irradiated Tissue

    CERN Document Server

    Welch, Ashley J

    2011-01-01

    The second edition of 'Optical-Thermal Response of Laser-Irradiated Tissue' maintains the standard of excellence established in the first edition, while adjusting the content to reflect changes in tissue optics and medical applications since 1995. The material concerning light propagation now contains new chapters devoted to electromagnetic theory for coherent light. The material concerning thermal laser-tissue interactions contains a new chapter on pulse ablation of tissue. The medical applications section now includes several new chapters on Optical Coherent Tomography, acoustic imaging, molecular imaging, forensic optics and nerve stimulation. A detailed overview is provided of the optical and thermal response of tissue to laser irradiation along with diagnostic and therapeutic examples including fiber optics. Sufficient theory is included in the book so that it is suitable for a one or two semester graduate or for senior elective courses. Material covered includes: 1. light propagation and diagnostic appl...

  3. Electrical and thermal conductivities in dense plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Faussurier, G., E-mail: gerald.faussurier@cea.fr; Blancard, C.; Combis, P.; Videau, L. [CEA, DAM, DIF, F-91297 Arpajon (France)

    2014-09-15

    Expressions for the electrical and thermal conductivities in dense plasmas are derived combining the Chester-Thellung-Kubo-Greenwood approach and the Kramers approximation. The infrared divergence is removed assuming a Drude-like behaviour. An analytical expression is obtained for the Lorenz number that interpolates between the cold solid-state and the hot plasma phases. An expression for the electrical resistivity is proposed using the Ziman-Evans formula, from which the thermal conductivity can be deduced using the analytical expression for the Lorenz number. The present method can be used to estimate electrical and thermal conductivities of mixtures. Comparisons with experiment and quantum molecular dynamics simulations are done.

  4. Electrical-thermal coupling of induction machine for improved ...

    African Journals Online (AJOL)

    Electrical-thermal coupling of induction machine for improved thermal performance. ... Nigerian Journal of Technology ... The interaction of its electrical and mechanical parts leads to an increase in temperature which if not properly monitored ...

  5. Use of thermal sieve to allow optical testing of cryogenic optical systems.

    Science.gov (United States)

    Kim, Dae Wook; Cai, Wenrui; Burge, James H

    2012-05-21

    Full aperture testing of large cryogenic optical systems has been impractical due to the difficulty of operating a large collimator at cryogenic temperatures. The Thermal Sieve solves this problem by acting as a thermal barrier between an ambient temperature collimator and the cryogenic system under test. The Thermal Sieve uses a set of thermally controlled baffles with array of holes that are lined up to pass the light from the collimator without degrading the wavefront, while attenuating the thermal background by nearly 4 orders of magnitude. This paper provides the theory behind the Thermal Sieve system, evaluates the optimization for its optical and thermal performance, and presents the design and analysis for a specific system.

  6. Improving Thermal and Electrical Efficiency in Photovoltaic Thermal Systems for Sustainable Cooling System Integration

    Directory of Open Access Journals (Sweden)

    Mohammad Alobaid

    2018-06-01

    Full Text Available Research into photovoltaic thermal systems is important in solar technologies as photovoltaic thermal systems are designed to produce both electrical and thermal energy, this can lead to improved performance of the overall system. The performance of photovoltaic thermal systems is based on several factors that include photovoltaic thermal materials, design, ambient temperature, inlet and outlet fluid temperature and photovoltaic cell temperature. The aim of this study is to investigate the effect of photovoltaic thermal outlet water temperatures and solar cell temperature on both electrical and thermal efficiency for different range of inlet water temperature. To achieve this, a mathematical model of a photovoltaic thermal system was developed to calculate the anticipated system performance. The factors that affect the efficiency of photovoltaic thermal collectors were discussed and the outlet fluid temperature from the photovoltaic thermal is investigated in order to reach the highest overall efficiency for the solar cooling system. An average thermal and electrical efficiency of 65% and 13.7%, respectively, was achieved and the photovoltaic thermal mathematical model was validated with experimental data from literature.

  7. Enhancement of the optical and electrical properties of ITO thin films deposited by electron beam evaporation technique

    Science.gov (United States)

    Ali, H. M.; Mohamed, H. A.; Mohamed, S. H.

    2005-08-01

    Indium tin oxide (ITO) is widely utilized in numerous industrial applications due to its unique combined properties of transparency to visible light and electrical conductivity. ITO films were deposited on glass substrates by an electron beam evaporation technique at room temperature from bulk samples, with different thicknesses. The film with 1500 Å thick was selected to perform annealing in the temperature range of 200 400 °C and annealing for varying times from 15 to 120 min at 400 °C. The X-ray diffraction of the films was analyzed in order to investigate its dependence on thickness, and annealing. Electrical and optical measurements were also carried out. Transmittance, optical energy gap, refractive index, carrier concentration, thermal emissivity and resistivity were investigated. It was found that the as-deposited films with different thicknesses were highly absorbing and have relatively poor electrical properties. The films become opaque with increasing the film thickness. After thermal annealing, the resistance decreases and a simultaneous variation in the optical transmission occurs. A transmittance value of 85.5% in the IR region and 82% in the visible region of the spectrum and a resistivity of 2.8 × 10-4 Ω Cm were obtained at annealing temperature of 400 °C for 120 min.

  8. Electric Motor Thermal Management R&D

    Energy Technology Data Exchange (ETDEWEB)

    Bennion, Kevin

    2016-06-07

    Thermal management enables more efficient and cost-effective motors. This Annual Merit Review presentation describes the technical accomplishments and progress in electric motor thermal management R&D over the last year. This project supports a broad industry demand for data, analysis methods, and experimental techniques to improve and better understand motor thermal management.

  9. Electrical and optical properties of indium tin oxide/epoxy composite film

    International Nuclear Information System (INIS)

    Guo Xia; Guo Chun-Wei; Chen Yu; Su Zhi-Ping

    2014-01-01

    The electrical and optical properties of the indium tin oxide (ITO)/epoxy composite exhibit dramatic variations as functions of the ITO composition and ITO particle size. Sharp increases in the conductivity in the vicinity of a critical volume fraction have been found within the framework of percolation theory. A conductive and insulating transition model is extracted by the ITO particle network in the SEM image, and verified by the resistivity dependence on the temperature. The dependence of the optical transmittance on the particle size was studied. Further decreasing the ITO particle size could further improve the percolation threshold and light transparency of the composite film. (condensed matter: structural, mechanical, and thermal properties)

  10. The limits to solar thermal electricity

    International Nuclear Information System (INIS)

    Trainer, Ted

    2014-01-01

    The potential and limits of solar thermal power systems depend primarily on their capacity to meet electricity demand in mid-winter, and the associated cost, storage and other implications. Evidence on output and costs is analysed. Most attention is given to central receivers. Problems of low radiation levels, embodied energy costs, variability and storage are discussed and are found to set significant difficulties for large scale solar thermal supply in less than ideal latitudes and seasons. It is concluded that for solar thermal systems to meet a large fraction of anticipated global electricity demand in winter would involve prohibitive capital costs. - Highlights: • Output and capital cost data for various solar thermal technologies is examined. • Special attention is given to performance in winter. • Attention is also given to the effect of solar intermittency. • Implications for storage are considered. • It is concluded that there are significant limits to solar thermal power

  11. Electrical and optical properties of Cu–Cr–O thin films fabricated by chemical vapour deposition

    Energy Technology Data Exchange (ETDEWEB)

    Lunca Popa, P., E-mail: petru.luncapopa@list.lu; Crêpellière, J.; Leturcq, R.; Lenoble, D.

    2016-08-01

    We present electrical and optical properties of CuCrO{sub 2} thin films deposited by chemical vapour deposition, as well as the influence of depositions' parameters on these properties. Oxygen partial pressure and precursor's concentrations have the greatest influence on optical and electrical properties of the films. Values of conductivities ranging from 10{sup −4} to 10 S/cm were obtained using different deposition conditions. The conductivity is thermally activated with an activation energy ranging from 57 to 283 meV. Thermoelectric measurements confirm the p-type conduction, and demonstrate high carrier concentration typical for a degenerate semiconductor. The as-deposited films show a medium degree of crystallinity, a maximum optical transmission up to 80% in the visible range with a corresponding band gap around 3.2 eV. - Highlights: • CuCrO{sub 2} thin films deposited via a new innovative method - DLICVD. • Band gap and electrical conductivity can be tuned by controlling deposition parameters • Key process parameter is the metallic/oxygen atomic ratio involved in the process • Electrical conductivities values spanning 5 orders of magnitudes were obtained using different deposition parameters.

  12. Novel double-stage high-concentrated solar hybrid photovoltaic/thermal (PV/T) collector with nonimaging optics and GaAs solar cells reflector

    International Nuclear Information System (INIS)

    Abdelhamid, Mahmoud; Widyolar, Bennett K.; Jiang, Lun; Winston, Roland; Yablonovitch, Eli; Scranton, Gregg; Cygan, David; Abbasi, Hamid; Kozlov, Aleksandr

    2016-01-01

    Highlights: • A novel hybrid concentrating photovoltaic thermal (PV/T) collector is developed. • Thermal component achieves 60× concentration using nonimaging optics. • GaAs solar cells used as spectrally selective mirrors for low energy photons. • Thermal efficiencies of 37% at 365 °C and electrical efficiencies of 8% achieved. • Combined electric efficiency reaches 25% of DNI for system cost of $283.10/m"2". - Abstract: A novel double stage high-concentration hybrid solar photovoltaic thermal (PV/T) collector using nonimaging optics and world record thin film single-junction gallium arsenide (GaAs) solar cells has been developed. We present a detailed design and simulation of the system, experimental setup, prototype, system performance, and economic analysis. The system uses a parabolic trough (primary concentrator) to focus sunlight towards a secondary nonimaging compound parabolic concentrator (CPC) to simultaneously generate electricity from single junction GaAs solar cells, as well as high temperature dispatchable heat. This study is novel in that (a) the solar cells inside the vacuum tube act as spectrally selective mirrors for lower energy photons to maximize the system exergy, and (b) secondary concentrator allows the thermal component to reach a concentration ratio ∼60×, which is significantly higher than conventional PV/T concentration ratios. The maximum outlet temperature reached was 365 °C, and on average the thermal efficiency of the experiment was around 37%. The maximum electrical efficiency was around 8%. The total system electricity generation is around 25% of incoming DNI, by assuming the high temperature stream is used to power a steam turbine. The installed system cost per unit of parabolic trough aperture area is $283.10 per m"2.

  13. Characterization of transimpedance amplifier as optical to electrical converter on designing optical instrumentation

    International Nuclear Information System (INIS)

    Hanto, D; Ula, R K

    2017-01-01

    Optical to electrical converter is the main components for designing of the optical instrumentations. In addition, this component is also used as signal conditioning. This component usually consists of a photo detector and amplifier. In this paper, characteristics of commercial amplifiers from Thorlabs PDA50B-EC has been observed. The experiment was conducted by diode laser with power of -5 dBm and wavelength 1310 nm; the optical attenuator to vary optical power from 0 to 60 dB, optical to electrical converter from Thorlabs Amplifier PDA50B-EC; multimode optical fiber to guide the laser; and digital voltmeter to measure the output of converter. The results of the characterization indicate that each channel amplification has a non-linear correlation between optical and electrical parameter; optical conversion measurement range of 20-23 dB to full scale; and different measurement coverage area. If this converter will be used as a part component of optical instrumentation so it should be adjusted suitably with the optical power source. Then, because of the correlation equation is not linear so calculation to determine the interpretation also should be considered in addition to the transfer function of the optical sensor. (paper)

  14. Characterization of transimpedance amplifier as optical to electrical converter on designing optical instrumentation

    Science.gov (United States)

    Hanto, D.; Ula, R. K.

    2017-05-01

    Optical to electrical converter is the main components for designing of the optical instrumentations. In addition, this component is also used as signal conditioning. This component usually consists of a photo detector and amplifier. In this paper, characteristics of commercial amplifiers from Thorlabs PDA50B-EC has been observed. The experiment was conducted by diode laser with power of -5 dBm and wavelength 1310 nm; the optical attenuator to vary optical power from 0 to 60 dB, optical to electrical converter from Thorlabs Amplifier PDA50B-EC; multimode optical fiber to guide the laser; and digital voltmeter to measure the output of converter. The results of the characterization indicate that each channel amplification has a non-linear correlation between optical and electrical parameter; optical conversion measurement range of 20-23 dB to full scale; and different measurement coverage area. If this converter will be used as a part component of optical instrumentation so it should be adjusted suitably with the optical power source. Then, because of the correlation equation is not linear so calculation to determine the interpretation also should be considered in addition to the transfer function of the optical sensor.

  15. Solar thermal energy conversion to electrical power

    International Nuclear Information System (INIS)

    Trinh, Anh-Khoi; González, Ivan; Fournier, Luc; Pelletier, Rémi; Sandoval V, Juan C.; Lesage, Frédéric J.

    2014-01-01

    The conversion of solar energy to electricity currently relies primarily on the photovoltaic effect in which photon bombardment of photovoltaic cells drives an electromotive force within the material. Alternatively, recent studies have investigated the potential of converting solar radiation to electricity by way of the Seebeck effect in which charge carrier mobility is generated by an asymmetric thermal differential. The present study builds upon these latest advancements in the state-of-the-art of thermoelectric system management by combining solar evacuated tube technology with commercially available Bismuth Telluride semiconductor modules. The target heat source is solar radiation and the target heat sink is thermal convection into the ambient air relying on wind aided forced convection. These sources of energy are reproduced in a laboratory controlled environment in order to maintain a thermal dipole across a thermoelectric module. The apparatus is then tested in a natural environment. The novelty of the present work lies in a net thermoelectric power gain for ambient environment applications and an experimental validation of theoretical electrical characteristics relative to a varying electrical load. - Highlights: • Solar radiation maintains a thermal tension which drives an electromotive force. • Voltage, current and electric power are reported and discussed. • Theoretical optimal thermoelectric conversion predictions are presented. • Theory is validated with experimentally measured data

  16. Effect of Se addition on optical and electrical properties of chalcogenide CdSSe thin films

    Science.gov (United States)

    Hassanien, A. S.; Akl, Alaa A.

    2016-01-01

    Compositional dependence of optical and electrical properties of chalcogenide CdSxSe1-x (0.4 ≥ x ≥ 0.0 at. %) thin films was studied. Cadmium sulphoselenide films were deposited by thermal evaporation technique at vacuum (8.2 × 10-4 Pa) onto preheated glass substrates (523 K). The evaporation rate and film thickness were kept constant at 2.50 nm/s and 375 ± 5 nm, respectively. X-ray diffractograms showed that, the deposited films have the low crystalline nature. Energy dispersive analysis by X-ray (EDAX) was used to check the compositional elements of deposited films. The absorption coefficient was determined from transmission and reflection measurements at room temperature in the wavelength range 300-2500 nm. Optical density, skin depth, optical energy gap and Urbach's parameters of CdSSe thin films have also been estimated. The direct optical energy gap decreased from 2.248 eV to 1.749 eV when the ratio of Se-content was increased from 0.60 to 1.00 . Conduction band and valance band positions were evaluated. The temperature dependence of dc-electrical resistivity in the temperature range (293-450 K) has been reported. Three conduction regions due to different conduction mechanisms were detected. Electrical sheet resistance, activation energy and pre-exponential parameters were discussed. The estimated values of optical and electrical parameters were strongly dependent upon the Se-content in CdSSe matrix.

  17. Diagnosis of the local thermal equilibrium by optical emission spectroscopy in the evolution of electric discharge

    International Nuclear Information System (INIS)

    Valdivia B, R.; Pacheco S, J.; Pacheco P, M.; Ramos F, F.; Cruz A, A.; Velazquez P, S.

    2008-01-01

    In this work applies the technique of optical emission spectroscopy to diagnose the temperature of the species generated in plasma in the transition to glow discharge arc. Whit this diagnosis is possible to determine the local thermal equilibrium conditions of the discharge. (Author)

  18. High thermal conductivity connector having high electrical isolation

    Science.gov (United States)

    Nieman, Ralph C.; Gonczy, John D.; Nicol, Thomas H.

    1995-01-01

    A method and article for providing a low-thermal-resistance, high-electrical-isolation heat intercept connection. The connection method involves clamping, by thermal interference fit, an electrically isolating cylinder between an outer metallic ring and an inner metallic disk. The connection provides durable coupling of a heat sink and a heat source.

  19. Effect of Composition on Electrical and Optical Properties of Thin Films of Amorphous GaxSe100−x Nanorods

    Directory of Open Access Journals (Sweden)

    Abdallah El-Hamidy SM

    2010-01-01

    Full Text Available Abstract We report the electrical and optical studies of thin films of a-GaxSe100−x nanorods (x = 3, 6, 9 and 12. Thin films of a-GaxSe100−x nanorods have been synthesized thermal evaporation technique. DC electrical conductivity of deposited thin films of a-GaxSe100−x nanorods is measured as a function of temperature range from 298 to 383 K. An exponential increase in the dc conductivity is observed with the increase in temperature, suggesting thereby a semiconducting behavior. The estimated value of activation energy decreases on incorporation of dopant (Ga content in the Se system. The calculated value of pre-exponential factor (σ0 is of the order of 101 Ω−1 cm−1, which suggests that the conduction takes place in the band tails of localized states. It is suggested that the conduction is due to thermally assisted tunneling of the carriers in the localized states near the band edges. On the basis of the optical absorption measurements, an indirect optical band gap is observed in this system, and the value of optical band gap decreases on increasing Ga concentration.

  20. Oxidative polycondensation of benzimidazole using NaOCl: Synthesis, characterization, optical, thermal and electrical properties of polybenzimidazoles

    Science.gov (United States)

    Anand, Siddeswaran; Muthusamy, Athianna; Dineshkumar, Sengottuvelu; Chandrasekaran, J.

    2017-11-01

    A series of polybenzimidazole polymers, poly-2-(1H-benzo[d] imidazole-2-yl) phenol (PBIP2), poly-3-(1H-benzo[d] imidazole-2-yl) phenol (PBIP3) and poly-4-(1H-benzo[d] imidazole-2-yl) phenol (PBIP4) were synthesized by oxidative polycondensation of benzimidazole monomers 2-(1H-benzo [d] imidazole-2-yl) phenol (BIP2), 3-(1H-benzo [d] imidazole-2-yl) phenol (BIP3) and 4-(1H-benzo [d] imidazole-2-yl) phenol (BIP4). The structure of benzimidazoles monomers and polybenzimidazoles (PBI) were confirmed by various spectroscopic techniques. The quantum theoretical calculations of band gap energy values of monomers were done with DFT and are compared with its optical band gap energy values. Fluorescence spectra of these compounds showed maximum emission in blue region. The electrical conductivity of PBIs was measured by four-point probe technique and showed good electrical response on iodine doping and conductivity increases with increase iodine doping time. The differences in conductivities among the three PBIs are in accordance with the charge density on imidazole nitrogens calculated by Huckel method. The high carbines residue (∼40%) at 500 °C in thermo gravimetric analysis shows that the PBIs are having reasonably good thermal stability. Polymers have recorded high dielectric constant at low applied frequency of 50 Hz at 393 K. The I-V characteristics of polybenzimidazoles p-n diodes showed rectifying nature with a typical forward to reverse current in the range -4 to 4 V. The high n values are caused by non homogeneities and effect of series resistance.

  1. A review of recent measurements of optical and thermal properties of α-mercuric iodide

    International Nuclear Information System (INIS)

    Burger, A.; Morgan, S.H.; Silberman, E.; Nason, D.; Cheng, A.Y.

    1991-01-01

    The knowledge of the physical properties of a crystal and their relation to the nature and content of defects are essential for both applications and fundamental reasons. Alpha-mercuric iodide (α-HgI 2 ) is a material which was found important applications as room temperature X-ray and gamma ray detectors. Some recent thermal and optical measurements of this material, using the samples of improved crystallinity which are now available, are reviewed below. Heretofore, these properties have received less attention than the mechanical and electrical properties, particularly at elevated temperatures. In the technology of α-HgI 2 where there is a continuing motivation to obtain larger single crystals without compromising the material quality, a better knowledge of the thermal and optical properties may lead to improvements in the processes of material purification, crystal growth and device fabrication

  2. Electrical and thermal behavior of unsaturated soils: experimental results

    Science.gov (United States)

    Nouveau, Marie; Grandjean, Gilles; Leroy, Philippe; Philippe, Mickael; Hedri, Estelle; Boukcim, Hassan

    2016-05-01

    When soil is affected by a heat source, some of its properties are modified, and in particular, the electrical resistivity due to changes in water content. As a result, these changes affect the thermal properties of soil, i.e., its thermal conductivity and diffusivity. We experimentally examine the changes in electrical resistivity and thermal conductivity for four soils with different grain size distributions and clay content over a wide range of temperatures, from 20 to 100 °C. This temperature range corresponds to the thermal conditions in the vicinity of a buried high voltage cable or a geothermal system. Experiments were conducted at the field scale, at a geothermal test facility, and in the laboratory using geophysical devices and probing systems. The results show that the electrical resistivity decreases and the thermal conductivity increases with temperature up to a critical temperature depending on soil types. At this critical temperature, the air volume in the pore space increases with temperature, and the resulting electrical resistivity also increases. For higher temperatures , the thermal conductivity increases sharply with temperature up to a second temperature limit. Beyond it, the thermal conductivity drops drastically. This limit corresponds to the temperature at which most of the water evaporates from the soil pore space. Once the evaporation is completed, the thermal conductivity stabilizes. To explain these experimental results, we modeled the electrical resistivity variations with temperature and water content in the temperature range 20 - 100°C, showing that two critical temperatures influence the main processes occurring during heating at temperatures below 100 °C.

  3. Experimental Investigation of Integrated Optical Intensive Impulse Electric Field Sensors

    International Nuclear Information System (INIS)

    Bao, Sun; Fu-Shen, Chen

    2009-01-01

    We design and fabricate an integrated optical electric field sensor with segmented electrode for intensive impulse electric field measurement. The integrated optical sensor is based on a Mach–Zehnder interferometer with segmented electrodes. The output/input character of the sensing system is analysed and measured. The maximal detectable electric field range (−75 kV/m to 245 kV/m) is obtained by analysing the results. As a result, the integrated optics electric field sensing system is suitable for transient intensive electric field measurement investigation

  4. COMPACT ATHERMAL OPTICAL WAVEGUIDE USING THERMAL EXPANSION AMPLIFICATION

    DEFF Research Database (Denmark)

    2001-01-01

    A method of temperature stabilising optical waveguides having positive thermal optical path length expansion, in particular fiber Bragg gratings or optical fiber DFB lasers or optical fiber DBR lasers, comprising affixing the optical waveguide to at least two points of a negative expanding fixture...

  5. Thermally Resilient, Broadband Optical Absorber from UV to IR Derived from Carbon Nanostructures

    Science.gov (United States)

    Kaul, Anupama B.; Coles, James B.

    2012-01-01

    Optical absorber coatings have been developed from carbon-based paints, metal blacks, or glassy carbon. However, such materials are not truly black and have poor absorption characteristics at longer wavelengths. The blackness of such coatings is important to increase the accuracy of calibration targets used in radiometric imaging spectrometers since blackbody cavities are prohibitively large in size. Such coatings are also useful potentially for thermal detectors, where a broadband absorber is desired. Au-black has been a commonly used broadband optical absorber, but it is very fragile and can easily be damaged by heat and mechanical vibration. An optically efficient, thermally rugged absorber could also be beneficial for thermal solar cell applications for energy harnessing, particularly in the 350-2,500 nm spectral window. It has been demonstrated that arrays of vertically oriented carbon nanotubes (CNTs), specifically multi-walled-carbon- nanotubes (MWCNTs), are an exceptional optical absorber over a broad range of wavelengths well into the infrared (IR). The reflectance of such arrays is 100x lower compared to conventional black materials, such as Au black in the spectral window of 350-2,500 nm. Total hemispherical measurements revealed a reflectance of approximately equal to 1.7% at lambda approximately equal to 1 micrometer, and at longer wavelengths into the infrared (IR), the specular reflectance was approximately equal to 2.4% at lambda approximately equal to 7 micrometers. The previously synthesized CNTs for optical absorber applications were formed using water-assisted thermal chemical vapor deposition (CVD), which yields CNT lengths in excess of 100's of microns. Vertical alignment, deemed to be a critical feature in enabling the high optical absorption from CNT arrays, occurs primarily via the crowding effect with thermal CVD synthesized CNTs, which is generally not effective in aligning CNTs with lengths less than 10 m. Here it has been shown that the

  6. Low-cost distributed solar-thermal-electric power generation

    Science.gov (United States)

    Der Minassians, Artin; Aschenbach, Konrad H.; Sanders, Seth R.

    2004-01-01

    Due to their high relative cost, solar electric energy systems have yet to be exploited on a widespread basis. It is believed in the energy community that a technology similar to photovoltaic (PV), but offered at about $1/W would lead to widespread deployment at residential and commercial sites. This paper addresses the investigation and feasibility study of a low-cost solar thermal electricity generation technology, suitable for distributed deployment. Specifically, we discuss a system based on nonimaging solar concentrators, integrated with free-piston Stirling engine devices incorporating integrated electric generation. We target concentrator-collector operation at moderate temperatures, in the range of 125°C to 150°C. This temperature is consistent with use of optical concentrators with concentration ratios on the order of 1-2. These low ratio concentrators admit wide angles of radiation acceptance and are thus compatible with no diurnal tracking, and no or only a few seasonal adjustments. Thus, costs and reliability hazards associated with tracking hardware systems are avoided. Further, we note that in the intended application, there is no shortage of incident solar energy, but rather it is the capital cost of the solar-electric system that is most precious. Thus, we outline a strategy for exploiting solar resources in a cost constrained manner. The paper outlines design issues, and a specific design for an appropriately dimensioned free-piston Stirling engine. Only standard low-cost materials and manufacturing methods are required to realize such a machine.

  7. An electrical method for the measurement of the thermal and electrical conductivity of reduced graphene oxide nanostructures.

    Science.gov (United States)

    Schwamb, Timo; Burg, Brian R; Schirmer, Niklas C; Poulikakos, Dimos

    2009-10-07

    This paper introduces an electrical four-point measurement method enabling thermal and electrical conductivity measurements of nanoscale materials. The method was applied to determine the thermal and electrical conductivity of reduced graphene oxide flakes. The dielectrophoretically deposited samples exhibited thermal conductivities in the range of 0.14-2.87 W m(-1) K(-1) and electrical conductivities in the range of 6.2 x 10(2)-6.2 x 10(3) Omega(-1) m(-1). The measured properties of each flake were found to be dependent on the duration of the thermal reduction and are in this sense controllable.

  8. Thermodynamic analysis of pumped thermal electricity storage

    International Nuclear Information System (INIS)

    White, Alexander; Parks, Geoff; Markides, Christos N.

    2013-01-01

    The increasing use of renewable energy technologies for electricity generation, many of which have an unpredictably intermittent nature, will inevitably lead to a greater need for electricity storage. Although there are many existing and emerging storage technologies, most have limitations in terms of geographical constraints, high capital cost or low cycle life, and few are of sufficient scale (in terms of both power and storage capacity) for integration at the transmission and distribution levels. This paper is concerned with a relatively new concept which will be referred to here as Pumped Thermal Electricity Storage (PTES), and which may be able to make a significant contribution towards future storage needs. During charge, PTES makes use of a high temperature ratio heat pump to convert electrical energy into thermal energy which is stored as ‘sensible heat’ in two thermal reservoirs, one hot and one cold. When required, the thermal energy is then converted back to electricity by effectively running the heat pump backwards as a heat engine. The paper focuses on thermodynamic aspects of PTES, including energy and power density, and the various sources of irreversibility and their impact on round-trip efficiency. It is shown that, for given compression and expansion efficiencies, the cycle performance is controlled chiefly by the ratio between the highest and lowest temperatures in each reservoir rather than by the cycle pressure ratio. The sensitivity of round-trip efficiency to various loss parameters has been analysed and indicates particular susceptibility to compression and expansion irreversibility

  9. Structural, optical and thermal properties of nanoporous aluminum

    International Nuclear Information System (INIS)

    Ghrib, Taher

    2015-01-01

    Highlights: • A simple electrochemical technique is presented and used to manufacture a porous aluminum layer. • Manufactured pores of 40 nm diameter and 200 nm depth are filled by nanocrystal of silicon and graphite. • Dimensions of pores increase with the anodization current which ameliorate the optical and thermal properties. • A new thermal method is presented which permit to determine the pores density and the layer thickness. • All properties show that the manufactured material can be used with success in solar cells. - Abstract: In this work the structural, thermal and optical properties of porous aluminum thin film formed with various intensities of anodization current in sulfuric acid are highlighted. The obtained pores at the surface are filled by sprayed graphite and nanocrystalline silicon (nc-Si) thin films deposited by plasma enhancement chemical vapor deposition (PECVD) which the role is to improve its optical and thermal absorption giving a structure of an assembly of three different media such as deposited thin layer (graphite or silicon)/(porous aluminum layer filled with the deposited layer)/(Al sample). The effect of anodization current on the microstructure of porous aluminum and the effect of the deposited layer were systematically studied by atomic force microscopy (AFM), transmission electron microscopy (TEM) and Raman spectroscopy. The thermal properties such as the thermal conductivity (K) and thermal diffusivity (D) are determined by the photothermal deflection (PTD) technique which is a non destructive technique. Based on this full characterization, it is demonstrated that the thermal and optical characteristics of these films are directly correlated to their micro-structural properties

  10. Thermal/structural/optical integrated design for optical sensor mounted on unmanned aerial vehicle

    Science.gov (United States)

    Zhang, Gaopeng; Yang, Hongtao; Mei, Chao; Wu, Dengshan; Shi, Kui

    2016-01-01

    With the rapid development of science and technology and the promotion of many local wars in the world, altitude optical sensor mounted on unmanned aerial vehicle is more widely applied in the airborne remote sensing, measurement and detection. In order to obtain high quality image of the aero optical remote sensor, it is important to analysis its thermal-optical performance on the condition of high speed and high altitude. Especially for the key imaging assembly, such as optical window, the temperature variation and temperature gradient can result in defocus and aberrations in optical system, which will lead to the poor quality image. In order to improve the optical performance of a high speed aerial camera optical window, the thermal/structural/optical integrated design method is developed. Firstly, the flight environment of optical window is analyzed. Based on the theory of aerodynamics and heat transfer, the convection heat transfer coefficient is calculated. The temperature distributing of optical window is simulated by the finite element analysis software. The maximum difference in temperature of the inside and outside of optical window is obtained. Then the deformation of optical window under the boundary condition of the maximum difference in temperature is calculated. The optical window surface deformation is fitted in Zernike polynomial as the interface, the calculated Zernike fitting coefficients is brought in and analyzed by CodeV Optical Software. At last, the transfer function diagrams of the optical system on temperature field are comparatively analyzed. By comparing and analyzing the result, it can be obtained that the optical path difference caused by thermal deformation of the optical window is 138.2 nm, which is under PV ≤1 4λ . The above study can be used as an important reference for other optical window designs.

  11. Integrated Vehicle Thermal Management - Combining Fluid Loops in Electric Drive Vehicles (Presentation)

    Energy Technology Data Exchange (ETDEWEB)

    Rugh, J. P.

    2013-07-01

    Plug-in hybrid electric vehicles and electric vehicles have increased vehicle thermal management complexity, using separate coolant loop for advanced power electronics and electric motors. Additional thermal components result in higher costs. Multiple cooling loops lead to reduced range due to increased weight. Energy is required to meet thermal requirements. This presentation for the 2013 Annual Merit Review discusses integrated vehicle thermal management by combining fluid loops in electric drive vehicles.

  12. Electrical and Optical Properties of GeSi−:H Thin Films Prepared by Thermal Evaporation Method

    Directory of Open Access Journals (Sweden)

    A. A. J. Al-Douri

    2010-01-01

    Full Text Available Thin a-GeSi1−:H films were grown successfully by fabrication of designated ingot followed by evaporation onto glass slides. A range of growth conditions, Ge contents, dopant concentration (Al and As, and substrate temperature, were employed. Stoichiometry of the thin films composition was confirmed using standard surface techniques. The structure of all films was amorphous. Film composition and deposition parameters were investigated for their bearing on film electrical and optical properties. More than one transport mechanism is indicated. It was observed that increasing substrate temperature, Ge contents, and dopant concentration lead to a decrease in the optical energy gap of those films. The role of the deposition conditions on values of the optical constants was determined. Accordingly, models of the density of states for the Ge0.5Si0.5:H thin films as pure, doped with 3.5% of Al (p-type and that doped with 3.5% As (n-type, were proposed.

  13. Bony ankylosis following thermal and electrical injury

    Energy Technology Data Exchange (ETDEWEB)

    Balen, P.F.; Helms, C.A. [Dept. of Radiology, Duke University Medical Center, Durham, NC (United States)

    2001-07-01

    Objective. Bony ankylosis has been described following trauma, paralysis, psoriasis, Reiter's syndrome, ankylosing spondylitis, juvenile chronic arthritis and rheumatoid arthritis. Reports of bony ankylosis following thermal and electrical injury are limited.Design and patients. Thirteen cases of burn-related joint ankylosis in four patients are presented.Conclusion. Patients with burns from thermal or electrical injury may develop bony ankylosis among other radiographic manifestations. This bony ankylosis may result either from bridging extra-articular heterotopic ossification with preservation of the underlying joint or from intra-articular fusion due to joint destruction. (orig.)

  14. Solar thermal electricity generation

    Science.gov (United States)

    Gasemagha, Khairy Ramadan

    1993-01-01

    This report presents the results of modeling the thermal performance and economic feasibility of large (utility scale) and small solar thermal power plants for electricity generation. A number of solar concepts for power systems applications have been investigated. Each concept has been analyzed over a range of plant power ratings from 1 MW(sub e) to 300 MW(sub e) and over a range of capacity factors from a no-storage case (capacity factor of about 0.25 to 0.30) up to intermediate load capacity factors in the range of 0.46 to 0.60. The solar plant's economic viability is investigated by examining the effect of various parameters on the plant costs (both capital and O & M) and the levelized energy costs (LEC). The cost components are reported in six categories: collectors, energy transport, energy storage, energy conversion, balance of plant, and indirect/contingency costs. Concentrator and receiver costs are included in the collector category. Thermal and electric energy transport costs are included in the energy transport category. Costs for the thermal or electric storage are included in the energy storage category; energy conversion costs are included in the energy conversion category. The balance of plant cost category comprises the structures, land, service facilities, power conditioning, instrumentation and controls, and spare part costs. The indirect/contingency category consists of the indirect construction and the contingency costs. The concepts included in the study are (1) molten salt cavity central receiver with salt storage (PFCR/R-C-Salt); (2) molten salt external central receiver with salt storage (PFCR/R-E-Salt); (3) sodium external central receiver with sodium storage (PFCR/RE-Na); (4) sodium external central receiver with salt storage (PFCR/R-E-Na/Salt); (5) water/steam external central receiver with oil/rock storage (PFCR/R-E-W/S); (6) parabolic dish with stirling engine conversion and lead acid battery storage (PFDR/SLAB); (7) parabolic dish

  15. Electrical and optical properties of thermally-evaporated thin films from A{sub 2}[TiO(C{sub 2}O{sub 4}){sub 2}] (A = K, PPh{sub 4}) and 1,8-dihydroxyanthraquinone

    Energy Technology Data Exchange (ETDEWEB)

    Carbia-Ruelas, E. [Coordinacion de Ingenieria Mecatronica. Facultad de Ingenieria, Universidad Anahuac Mexico Norte. Avenida Universidad Anahuac 46, Col. Lomas Anahuac, 52786, Huixquilucan (Mexico); Sanchez-Vergara, M.E., E-mail: elena.sanchez@anahuac.mx [Coordinacion de Ingenieria Mecatronica. Facultad de Ingenieria, Universidad Anahuac Mexico Norte. Avenida Universidad Anahuac 46, Col. Lomas Anahuac, 52786, Huixquilucan (Mexico); Garcia-Montalvo, V. [Instituto de Quimica, Universidad Nacional Autonoma de Mexico. Circuito Exterior, Ciudad Universitaria, 04510, Mexico, D. F (Mexico); Morales-Saavedra, O.G. [Centro de Ciencias Aplicadas y Desarrollo Tecnologico, Universidad Nacional Autonoma de Mexico, CCADET-UNAM. A. P. 70-186, Coyoacan, 04510, Mexico, D. F (Mexico); Alvarez-Bada, J.R. [Coordinacion de Ingenieria Mecatronica. Facultad de Ingenieria, Universidad Anahuac Mexico Norte. Avenida Universidad Anahuac 46, Col. Lomas Anahuac, 52786, Huixquilucan (Mexico)

    2011-02-01

    In this work, the synthesis of molecular materials formed from A{sub 2}[TiO(C{sub 2}O{sub 4}){sub 2}] (A = K, PPh4) and 1,8 dihydroxyanthraquinone is reported. The synthesized materials were characterized by atomic force microscopy (AFM), infrared (IR) and ultraviolet-visible (UV-vis) spectroscopy. IR spectroscopy showed that the molecular-material thin-films, deposited by vacuum thermal evaporation, exhibit the same intra-molecular vibration modes as the starting powders, which suggests that the thermal evaporation process does not alter the initial chemical structures. Electrical transport properties were studied by dc conductivity measurements. The electrical activation energies of the complexes, which were in the range of 0.003-1.16 eV, were calculated from Arrhenius plots. Optical absorption studies in the wavelength range of 190-1090 nm at room temperature showed that the optical band gaps of the thin films were around 1.9-2.3 eV for direct transitions Eg{sub d}. The cubic NLO effects were substantially enhanced for materials synthesized from K{sub 2}[TiO(C{sub 2}O{sub 4}){sub 2}], where {chi}{sup (3)} (-3{omega}; {omega}, {omega}, {omega}) values in the promising range of 10{sup -12} esu have been evaluated.

  16. Electrical and thermal modeling of railguns

    International Nuclear Information System (INIS)

    Kerrisk, J.F.

    1984-01-01

    Electrical and thermal modeling of railguns at Los Alamos has been done for two purposes: (1) to obtain detailed information about the behavior of specific railgun components such as the rails, and (2) to predict overall performance of railgun tests. Detailed electrical and thermal modeling has concentrated on calculations of the inductance and surface current distribution of long parallel conductors in the high-frequency limit and on calculations of current and thermal diffusion in rails. Inductance calculations for various rail cross sections and for magnetic flux compression generators (MFCG) have been done. Inductance and current distribution results were compared with experimental measurements. Twodimensional calculations of current and thermal diffusion in rail cross sections have been done; predictions of rail heating and melting as a function of rail size and total current have been made. An overall performance model of a railgun and power supply has been developed and used to design tests at Los Alamos. The lumped-parameter circuit model uses results from the detailed inductance and current diffusion calculations along with other circuit component models to predict rail current and projectile acceleration, velocity, and position as a function of time

  17. Determining an energy-optimal thermal management strategy for electric driven vehicles

    Energy Technology Data Exchange (ETDEWEB)

    Suchaneck, Andre; Probst, Tobias; Puente Leon, Fernando [Karlsruher Institut fuer Technology (KIT), Karlsruhe (Germany). Inst. of Industrial Information Technology (IIIT)

    2012-11-01

    In electric, hybrid electric and fuel cell vehicles, thermal management may have a significant impact on vehicle range. Therefore, optimal thermal management strategies are required. In this paper a method for determining an energy-optimal control strategy for thermal power generation in electric driven vehicles is presented considering all controlled devices (pumps, valves, fans, and the like) as well as influences like ambient temperature, vehicle speed, motor and battery and cooling cycle temperatures. The method is designed to be generic to increase the thermal management development process speed and to achieve the maximal energy reduction for any electric driven vehicle (e.g., by waste heat utilization). Based on simulations of a prototype electric vehicle with an advanced cooling cycle structure, the potential of the method is shown. (orig.)

  18. Structural, optical and electrical properties of tin oxide thin films for application as a wide band gap semiconductor

    Energy Technology Data Exchange (ETDEWEB)

    Sethi, Riti; Ahmad, Shabir; Aziz, Anver; Siddiqui, Azher Majid, E-mail: amsiddiqui@jmi.ac.in [Department of Physics, Jamia Millia Islamia, New Delhi-110025 (India)

    2015-08-28

    Tin oxide (SnO) thin films were synthesized using thermal evaporation technique. Ultra pure metallic tin was deposited on glass substrates using thermal evaporator under high vacuum. The thickness of the tin deposited films was kept at 100nm. Subsequently, the as-deposited tin films were annealed under oxygen environment for a period of 3hrs to obtain tin oxide films. To analyse the suitability of the synthesized tin oxide films as a wide band gap semiconductor, various properties were studied. Structural parameters were studied using XRD and SEM-EDX. The optical properties were studied using UV-Vis Spectrophotometry and the electrical parameters were calculated using the Hall-setup. XRD and SEM confirmed the formation of SnO phase. Uniform texture of the film can be seen through the SEM images. Presence of traces of unoxidised Sn has also been confirmed through the XRD spectra. The band gap calculated was around 3.6eV and the optical transparency around 50%. The higher value of band gap and lower value of optical transparency can be attributed to the presence of unoxidised Sn. The values of resistivity and mobility as measured by the Hall setup were 78Ωcm and 2.92cm{sup 2}/Vs respectively. The reasonable optical and electrical parameters make SnO a suitable candidate for optoelectronic and electronic device applications.

  19. Overview of Optical and Thermal Laser-Tissue Interaction and Nomenclature

    Science.gov (United States)

    Welch, Ashley J.; van Gemert, Martin J. C.

    The development of a unified theory for the optical and thermal response of tissue to laser radiation is no longer in its infancy, though it is still not fully developed. This book describes our current understanding of the physical events that can occur when light interacts with tissue, particularly the sequence of formulations that estimate the optical and thermal responses of tissue to laser radiation. This overview is followed by an important chapter that describes the basic interactions of light with tissue. Part I considers basic tissue optics. Tissue is treated as an absorbing and scattering medium and methods are presented for calculating and measuring light propagation, including polarized light. Also, methods for estimating tissue optical properties from measurements of reflection and transmission are discussed. Part II concerns the thermal response of tissue owing to absorbed light, and rate reactions are presented for predicting the extent of laser induced thermal damage. Methods for measuring temperature, thermal properties, rate constants, pulsed ablation and laser tissue interactions are detailed. Part III is devoted to examples that use the theory presented in Parts I and II to analyze various medical applications of lasers. Discussions of Optical Coherence Tomography (OCT), forensic optics, and light stimulation of nerves are also included.

  20. Optical and electrical properties of CuMO2 transparent p-type conductors

    Science.gov (United States)

    Draeseke, A. D.; Jayaraj, M. K.; Ulbrich, T.; Kroupp, M.; Tate, J.; Nagarajan, R.; Oblezov, A.; Sleight, A. W.

    2001-03-01

    Wide band gap oxides of the type CuMO2 with the delafossite structure are p-type conductors and many of them are transparent. Films of these p-type oxides have been grown by sputtering and thermal evaporation, and characterized electrically and optically. We present transport and optical transmission measurements for CuY_1-xCa_xO_2, CuScO_2+x and other similar materials. Conductivities are in the range 1 200 S/cm and depend on details of film preparation. The carriers are p-type as determined by thermopower measurements, and typical Seebeck coefficients are several hundred µV/K. Optical transparency varies considerably, but is about 40% at 550 nm for the highest conductivity films. Excellent transparency can be achieved at the expense of conductivity, and optimization is being studied. Band gaps derived from optical transmission are larger than 3.1 eV. Prototype all-oxide pn diodes have been fabricated. This work was partially supported by the NSF under DMR-0071727 and by the Research Corporation under RA0291.

  1. Microstructural evolution of pipelines for thermal electric power plants after a prolongated operation

    International Nuclear Information System (INIS)

    Twentyman, M.; Rosetti, R.; Porta, G.

    1991-01-01

    The study of failures originated in pipelines for thermal electric power plants allows an evaluation of the limit microstructural conditions that turn the system to critical conditions. A set of pipe samples with different microsctructural evolution which had been affected by direct flame were prepared. The samples were taken close to failures, away from them, from out of use pipes, etc. Metallographic studies were carried out using optical microscopy and scanning electron microscopy. Phase distribution, morphology and their relation with the different stages of aging were observed. (Author) [es

  2. Thermal and electrical conductivities of high purity tantalum

    International Nuclear Information System (INIS)

    Archer, S.L.

    1978-01-01

    The electrical resistivity and thermal conductivity of three high purity tantalum samples have been measured as functions of temperature over a temperature range of 5K to 65K. Sample purities ranged up to a resistivity ratio of 1714. The highest purity sample had a residual resistivity of .76 x 10 -10 OMEGA-m. The intrinsic resistivity varied as T 3 . 9 from 10K to 31K. The thermal conductivity of the purest sample had a maximum of 840 W/mK at 9.8K. The intrinsic thermal resistivity varied as T 2 . 4 from 10K to 35K. At low temperatures electrons were scattered primarily by impurities and by phonons with both interband and intraband transitions observed. The electrical and thermal resistivity is departed from Matthiessen's rule at low temperatures

  3. An improved electrical and thermal model of a microbolometer for electronic circuit simulation

    Science.gov (United States)

    Würfel, D.; Vogt, H.

    2012-09-01

    The need for uncooled infrared focal plane arrays (IRFPA) for imaging systems has increased since the beginning of the nineties. Examples for the application of IRFPAs are thermography, pedestrian detection for automotives, fire fighting, and infrared spectroscopy. It is very important to have a correct electro-optical model for the simulation of the microbolometer during the development of the readout integrated circuit (ROIC) used for IRFPAs. The microbolometer as the sensing element absorbs infrared radiation which leads to a change of its temperature due to a very good thermal insulation. In conjunction with a high temperature coefficient of resistance (TCR) of the sensing material (typical vanadium oxide or amorphous silicon) this temperature change results in a change of the electrical resistance. During readout, electrical power is dissipated in the microbolometer, which increases the temperature continuously. The standard model for the electro-optical simulation of a microbolometer includes the radiation emitted by an observed blackbody, radiation emitted by the substrate, radiation emitted by the microbolometer itself to the surrounding, a heat loss through the legs which connect the microbolometer electrically and mechanically to the substrate, and the electrical power dissipation during readout of the microbolometer (Wood, 1997). The improved model presented in this paper takes a closer look on additional radiation effects in a real IR camera system, for example the radiation emitted by the casing and the lens. The proposed model will consider that some parts of the radiation that is reflected from the casing and the substrate is also absorbed by the microbolometer. Finally, the proposed model will include that some fraction of the radiation is transmitted through the microbolometer at first and then absorbed after the reflection at the surface of the substrate. Compared to the standard model temperature and resistance of the microbolometer can be

  4. Reversible temperature regulation of electrical and thermal conductivity using liquid–solid phase transitions

    Science.gov (United States)

    Zheng, Ruiting; Gao, Jinwei; Wang, Jianjian; Chen, Gang

    2011-01-01

    Reversible temperature tuning of electrical and thermal conductivities of materials is of interest for many applications, including seasonal regulation of building temperature, thermal storage and sensors. Here we introduce a general strategy to achieve large contrasts in electrical and thermal conductivities using first-order phase transitions in percolated composite materials. Internal stress generated during a phase transition modulates the electrical and thermal contact resistances, leading to large contrasts in the electrical and thermal conductivities at the phase transition temperature. With graphite/hexadecane suspensions, the electrical conductivity changes 2 orders of magnitude and the thermal conductivity varies up to 3.2 times near 18 °C. The generality of the approach is also demonstrated in other materials such as graphite/water and carbon nanotube/hexadecane suspensions. PMID:21505445

  5. Reversible temperature regulation of electrical and thermal conductivity using liquid-solid phase transitions.

    Science.gov (United States)

    Zheng, Ruiting; Gao, Jinwei; Wang, Jianjian; Chen, Gang

    2011-01-01

    Reversible temperature tuning of electrical and thermal conductivities of materials is of interest for many applications, including seasonal regulation of building temperature, thermal storage and sensors. Here we introduce a general strategy to achieve large contrasts in electrical and thermal conductivities using first-order phase transitions in percolated composite materials. Internal stress generated during a phase transition modulates the electrical and thermal contact resistances, leading to large contrasts in the electrical and thermal conductivities at the phase transition temperature. With graphite/hexadecane suspensions, the electrical conductivity changes 2 orders of magnitude and the thermal conductivity varies up to 3.2 times near 18 °C. The generality of the approach is also demonstrated in other materials such as graphite/water and carbon nanotube/hexadecane suspensions.

  6. Electrically Driven Thermal Management: Flight Validation, Experiment Development, Future Technologies

    Science.gov (United States)

    Didion, Jeffrey R.

    2018-01-01

    Electrically Driven Thermal Management is an active research and technology development initiative incorporating ISS technology flight demonstrations (STP-H5), development of Microgravity Science Glovebox (MSG) flight experiment, and laboratory-based investigations of electrically based thermal management techniques. The program targets integrated thermal management for future generations of RF electronics and power electronic devices. This presentation reviews four program elements: i.) results from the Electrohydrodynamic (EHD) Long Term Flight Demonstration launched in February 2017 ii.) development of the Electrically Driven Liquid Film Boiling Experiment iii.) two University based research efforts iv.) development of Oscillating Heat Pipe evaluation at Goddard Space Flight Center.

  7. Study of the electrical and thermal performances of photovoltaic thermal collector-compound parabolic concentrated

    Directory of Open Access Journals (Sweden)

    Ahed Hameed Jaaz

    2018-06-01

    Full Text Available The importance of utilizing the solar energy as a very suitable source among multi-source approaches to replace the conventional energy is on the rise in the last four decades. The invention of the photovoltaic module (PV could be the corner stone in this process. However, the limited amount of energy obtained from PV was and still the main challenge of full utilization of the solar energy. In this paper, the use of the compound parabolic concentrator (CPC along with the thermal photovoltaic module (PVT where the cooling process of the CPC is conducted using a novel technique of water jet impingement has applied experimentally and physically tested. The test includes the effect of water jet impingement on the total power, electrical efficiency, thermal efficiency, and total efficiency on CPC-PVT system. The cooling process at the maximum irradiation by water jet impingement resulted in improving the electrical efficiency by 7%, total output power by 31% and the thermal efficiency by 81%. These results outperform the recent highest results recorded by the most recent work. Keywords: Photovoltaic thermal collectors, Electrical performance, Thermal performance, Compound parabolic concentrator, Jet impingement

  8. Electrically tunable Brillouin fiber laser based on a metal-coated single-mode optical fiber

    Directory of Open Access Journals (Sweden)

    S.M. Popov

    Full Text Available We explore tunability of the Brillouin fiber laser employing Joule heating. For this purpose, 10-m-length of a metal-coated single-mode optical cavity fiber has been directly included into an electrical circuit, like a conductor wire. With the current up to ∼3.5 A the laser tuning is demonstrated over a spectrum range of ∼400 MHz. The observed laser line broadening up to ∼2 MHz is explained by frequency drift and mode-hoping in the laser caused by thermal noise. Keywords: Brillouin fiber laser, Metal-coated optical fiber, Laser tuning, Fiber sensors

  9. Effect of γ-irradiation on the optical and electrical properties of fiber reinforced composites

    International Nuclear Information System (INIS)

    Anwar, Ahmad; Elfiky, Dalia; Ramadan, Ahmed M.; Hassan, G.M.

    2017-01-01

    The effect of gamma irradiation on the optical and electrical properties of the reinforced fiber polymeric based materials became an important issue. Fiberglass/epoxy and Kevlar fiber/epoxy were selected as investigated samples manufactured with hand lay-up without autoclave curing technique. The selected technique is simple and low cost while being rarely used in space materials production. The electric conductivity and dielectric constant for those samples were measured with increasing the gamma radiation dose. Moreover, the absorptivity, band gap and color change were determined. Fourier transform infrared (FTIR) was performed to each of the material's constituent to evaluate the change in the investigated materials due to radiation exposure dose. In this study, the change of electrical properties for both investigated materials showed a slight variation of the test parameters with respect to the gamma dose increase; this variation is placed in the insulators rang. The tested samples showed an insulator stable behavior during the test period. The change of optical properties for both composite specimens showed the maximum absorptivity at the gamma dose 750 kGy. These materials are suitable for structure materials and thermal control for orbital life less than 7 years. In addition, the transparency of epoxy matrix was degraded. However, there is no color change for either Kevlar fiber or fiberglass. - Highlights: • Space qualification for the reinforced fiber polymeric based materials which will be used for satellite structure. • Change of optical and electrical properties for selected material under the effect of gamma radiation. • Using a simple and low cost manufacturing method for space materials.

  10. Electrical, Magnetic, and Optical Measurement Facility

    Data.gov (United States)

    Federal Laboratory Consortium — FUNCTION: Provides tools necessary for electrical, magnetic, and optical characterization of bulk and thin-film materials. This includes the ability to determine the...

  11. Electrical and thermal properties of graphite/polyaniline composites

    Energy Technology Data Exchange (ETDEWEB)

    Bourdo, Shawn E., E-mail: sxbourdo@ualr.edu [Center for Integrative Nanotechnology Sciences, University of Arkansas at Little Rock, 2801 South University Avenue, Little Rock, AR 72204 (United States); Warford, Brock A.; Viswanathan, Tito [Department of Chemistry, University of Arkansas at Little Rock, 2801 South University Avenue, Little Rock, AR 72204 (United States)

    2012-12-15

    A composite of a carbon allotrope (graphite) and an inherently conducting polymer, polyaniline (PANI), has been prepared that exhibits an electrical conductivity greater than either of the two components. An almost 2-fold increase in the bulk conductivity occurs when only a small mass fraction of polyaniline exists in the composite (91% graphite/ 9% polyaniline, by mass). This increase in dc electrical conductivity is curious since in most cases a composite material will exhibit a conductivity somewhere between the two individual components, unless a modification to the electronic nature of the material occurs. In order to elucidate the fundamental electrical properties of the composite we have performed variable temperature conductivity measurements to better understand the nature of conduction in these materials. The results from these studies suggest a change in the mechanism of conduction as the amount of polyaniline is increased in the composite. Along with superior electrical properties, the composites exhibit an increase in thermal stability as compared to the graphite. - Graphical abstract: (Left) Room temperature electrical conductivity of G-PANI composites at different mass ratios. (Right) Electrical conductivity of G-PANI composites at temperatures from 5 K to 300 K. Highlights: Black-Right-Pointing-Pointer Composites of graphite and polyaniline have been synthesized with unique electrical and thermal properties. Black-Right-Pointing-Pointer Certain G-PANI composites are more conductive and more thermally stable than graphite alone. Black-Right-Pointing-Pointer G-PANI composites exhibit a larger conductivity ratio with respect to temperature than graphite alone.

  12. Electrical and optical properties of nickel ferrite/polyaniline nanocomposite

    Directory of Open Access Journals (Sweden)

    M. Khairy

    2015-07-01

    Full Text Available Polyaniline–NiFe2O4 nanocomposites (PANI–NiFe2O4 with different contents of NiFe2O4 (2.5, 5 and 50 wt% were prepared via in situ chemical oxidation polymerization, while the nanoparticles nickel ferrite were synthesized by sol–gel method. The prepared samples were characterized using some techniques such as Fourier transforms infrared (FTIR, X-ray diffraction (XRD, scanning electron microscopy (SEM and thermogravimetric analysis (TGA. Moreover, the electrical conductivity and optical properties of the nanocomposites were investigated. Pure (PANI and the composites containing 2.5 and 5 wt% NiFe2O4 showed amorphous structures, while the one with 50 wt% NiFe2O4 showed a spinel crystalline structure. The SEM images of the composites showed different aggregations for the different nickel ferrite contents. FTIR spectra revealed to the formation of some interactions between the PANI macromolecule and the NiFe2O4 nanoparticles, while the thermal analyses indicated an increase in the composites stability for samples with higher NiFe2O4 nanoparticles contents. The electrical conductivity of PANI–NiFe2O4 nanocomposite was found to increase with the rise in NiFe2O4 nanoparticle content, probably due to the polaron/bipolaron formation. The optical absorption experiments illustrate direct transition with an energy band gap of Eg = 1.0 for PANI–NiFe2O4 nanocomposite.

  13. Effective electrical and thermal conductivity of multifilament twisted superconductors

    International Nuclear Information System (INIS)

    Chechetkin, V.R.

    2013-01-01

    The effective electrical and thermal conductivity of composite wire with twisted superconducting filaments embedded into normal metal matrix is calculated using the extension of Bruggeman method. The resistive conductivity of superconducting filaments is described in terms of symmetric tensor, whereas the conductivity of a matrix is assumed to be isotropic and homogeneous. The dependence of the resistive electrical conductivity of superconducting filaments on temperature, magnetic field, and current density is implied to be parametric. The resulting effective conductivity tensor proved to be non-diagonal and symmetric. The non-diagonal transverse–longitudinal components of effective electrical conductivity tensor are responsible for the redistribution of current between filaments. In the limits of high and low electrical conductivity of filaments the transverse effective conductivity tends to that of obtained previously by Carr. The effective thermal conductivity of composite wires is non-diagonal and radius-dependent even for the isotropic and homogeneous thermal conductivities of matrix and filaments.

  14. Thermal Management of Power Electronics and Electric Motors for Electric-Drive Vehicles (Presentation)

    Energy Technology Data Exchange (ETDEWEB)

    Narumanchi, S.

    2014-09-01

    This presentation is an overview of the power electronics and electric motor thermal management and reliability activities at NREL. The focus is on activities funded by the Department of Energy Vehicle Technologies Office Advanced Power Electronics and Electric Motors Program.

  15. Post Deposition Annealing Effects on Optical, Electrical and Morphological Studies of ZnTTBPc Thin Films

    Directory of Open Access Journals (Sweden)

    B. R. Rejitha

    2012-01-01

    Full Text Available Phthalocyanines (Pcs act as efficient absorbants of photons in the visible region, specifically between 600 and 700 nm. It will produce an excited triplet state. In this paper we report the annealing effects of optical, electrical and surface morphological properties of thermal evaporated Zinc-tetra-tert-butyl-29H, 31H phthalocyanine (ZnTTBPc thin films. The optical transmittance measurements were done in the visible region (400-800 nm and, films were found to be absorbing in nature. From spectral data the absorption coefficient α, dielectric constant ε and the extinction coefficient k were evaluated and, results discussed. Also the optical band gap of the material was estimated. The activation energies were measured. Scanning electron microscopic studies was carried out to determine surface uniformity of films.

  16. Thermal injury secondary to laparoscopic fiber-optic cables.

    Science.gov (United States)

    Hindle, A Katharine; Brody, Fred; Hopkins, Vernon; Rosales, Greg; Gonzalez, Florencia; Schwartz, Arnold

    2009-08-01

    Laparoscopy requires a reliable light source to provide adequate visualization. However, thermal energy is produced as a by-product from the optical cable. This study attempts to quantify the degree of possible thermal damage secondary to the fiber-optic light source. Using a digital thermometer, temperature measurements were recorded at the tip of optical cables from five different light sources (Karl Storz, Inc., Tuttlingen, Germany). Temperature measurements were recorded with new and old bulbs. The tip of the cable was applied to surgical drapes and the time to charring was recorded. Subsequently, the tip of the optical cable was applied to a porcine model and tissue samples were obtained after varying amounts of time (5, 15, 30, 60, and 90 s). Sections of the damaged tissue were prepared for microscopic evaluation. Parameters for thermal injury included extent of epidermal, dermal, and subcutaneous fat damage and necrosis. The lateral extent and depth of injury were measured. The maximum temperature at the tip of the optical cable varied between 119.5 degrees C and 268.6 degrees C. When surgical drapes were exposed to the tip of the light source, the time to char was 3-6 s. The degree and volume of injury increased with longer exposure times, and significant injury was recorded with the optical cable 3 mm from the skin. This study demonstrates that the temperature at the tip of the optical light cord can induce extensive damage. The by-product of light, heat, can produce immediate superficial tissue necrosis that can extend into the subcutaneous fat even when the optical tip is not in direct contact with the skin. In addition, our study shows the variation in temperature that exists between light sources and bulb status. Overall, surgeons must realize and respect the potential complications associated with optical technology.

  17. Optical, thermal and electrical properties of polybenzimidazoles derived from substituted benzimidazoles

    Science.gov (United States)

    Anand, Siddeswaran; Muthusamy, Athianna

    2017-11-01

    Three benzimidazole monomers synthesized by condensing various substituted phenolic aldehydes with 4-methylphenylenediamine were converted in to polymers by oxidative polycondensation. The structure of the monomers and polymers were confirmed by various spectroscopic techniques. Electronic distribution of molecular frontier orbitals and optimized geometries of monomers were calculated by Gaussian 09 package. The spectral results showed that the repeating units are connected through both Csbnd C and Csbnd Osbnd C linkages. Both polymers and monomers are showing good fluorescence emission in blue region. The electrical conductivity of I2 doped PBIs was measured using two point probe technique. The conductivities of PBIs were compared on the basis of the charge densities obtained from Huckel method on imidazole nitrogen which is involved in iodine coordination. The conductivity of polymers increases with increase in iodine vapour contact time. The dielectric properties of the synthesized polymers have been investigated at different temperature and frequency. Among the PBIs, PBIOP is having greater thermal stability and is shown by high carbines residues of around 50% at 500 °C in thermogravimetric analysis.

  18. High-frequency thermal-electrical cycles for pyroelectric energy conversion

    International Nuclear Information System (INIS)

    Bhatia, Bikram; Damodaran, Anoop R.; Cho, Hanna; Martin, Lane W.; King, William P.

    2014-01-01

    We report thermal to electrical energy conversion from a 150 nm thick BaTiO 3 film using pyroelectric cycles at 1 kHz. A microfabricated platform enables temperature and electric field control with temporal resolution near 1 μs. The rapid electric field changes as high as 11 × 10 5  kV/cm-s, and temperature change rates as high as 6 × 10 5  K/s allow exploration of pyroelectric cycles in a previously unexplored operating regime. We investigated the effect of phase difference between electric field and temperature cycles, and electric field and temperature change rates on the electrical energy generated from thermal-electrical cycles based on the pyroelectric Ericsson cycle. Complete thermodynamic cycles are possible up to the highest cycle rates tested here, and the energy density varies significantly with phase shifts between temperature and electric field waveforms. This work could facilitate the design and operation of pyroelectric cycles at high cycle rates, and aid in the design of new pyroelectric systems

  19. Improvement of Thermal and Electrical Conductivity of Epoxy/boron Nitride/silver Nanoparticle Composite

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Seungyong; Lim, Soonho [Korea Institute of Science and Technology, Wanju (Korea, Republic of)

    2017-06-15

    In this study, we investigated the effect of BN (boron nitride) on the thermal and the electrical conductivity of composites. In case of epoxy/BN composites, the thermal conductivity was increased as the BN contents were increased. Epoxy/AgNP (Ag nanoparticle) nanocomposites exhibited a slight change of thermal conductivity and showed a electrical percolation threshold at 20 vol% of Ag nanoparticles. At the fixed Ag nanoparticle content below the electrical percolation threshold, increasing the amount of BN enhanced the electrical conductivity as well as thermal conductivity for the epoxy/AgNP/BN composites.

  20. On the design of thermally loaded fiber optics feedthroughs

    Directory of Open Access Journals (Sweden)

    Marinković Dragan Z.

    2016-01-01

    Full Text Available Thermo-mechanical design aspects of various structures exposed to cyclic thermal loading have a crucial impact on their lifetime. This is particularly valid for fiber optics feedthroughs that involve several materials with significantly different thermal expansion ratios. Thermal loading in such structures may give rise to non-trivial thermally induced deformations and therewith stresses, which can be adequately predicted and assessed only by a detailed 3-D numerical simulation. This paper considers a couple of design solutions of fiber optics feedthroughs, which have exhibited certain weaknesses in their application. Numerical simulation by means of the finite element method has been conducted to reveal the weak points of the design.

  1. Dynamic tuning of optical absorbers for accelerated solar-thermal energy storage.

    Science.gov (United States)

    Wang, Zhongyong; Tong, Zhen; Ye, Qinxian; Hu, Hang; Nie, Xiao; Yan, Chen; Shang, Wen; Song, Chengyi; Wu, Jianbo; Wang, Jun; Bao, Hua; Tao, Peng; Deng, Tao

    2017-11-14

    Currently, solar-thermal energy storage within phase-change materials relies on adding high thermal-conductivity fillers to improve the thermal-diffusion-based charging rate, which often leads to limited enhancement of charging speed and sacrificed energy storage capacity. Here we report the exploration of a magnetically enhanced photon-transport-based charging approach, which enables the dynamic tuning of the distribution of optical absorbers dispersed within phase-change materials, to simultaneously achieve fast charging rates, large phase-change enthalpy, and high solar-thermal energy conversion efficiency. Compared with conventional thermal charging, the optical charging strategy improves the charging rate by more than 270% and triples the amount of overall stored thermal energy. This superior performance results from the distinct step-by-step photon-transport charging mechanism and the increased latent heat storage through magnetic manipulation of the dynamic distribution of optical absorbers.

  2. Electro-thermal analysis and integration issues of lithium ion battery for electric vehicles

    International Nuclear Information System (INIS)

    Saw, L.H.; Ye, Y.; Tay, A.A.O.

    2014-01-01

    Highlights: • We modeled the electrical and thermal behavior of the Li-ion battery. • We validated the simulation results with experimental studies. • We compared the thermal performance of different size of cylindrical cells. • We investigated the integration issues of cylindrical cells into battery pack. - Abstract: Electrical and thermal characteristics of lithium-ion battery packs in electric vehicles in different operating conditions are important in order to design the battery pack thermal management system. In this work, electrical and thermal behaviors of different size of LiFePO 4 cylindrical cells are investigated under various operating conditions. The simulation results show good agreement with the experimental data under various operating modes. Due to the large thermal resistance of layered active material in a Li-ion cell, the temperature difference in the radial direction is significantly correlated with a diameter of cell and I t -rates. Compared with natural convection, strong forced convection will reduce the temperature uniformity in the cell and accelerate the thermal aging rate. Lastly, integration issues of the cells into a battery pack are discussed from mechanical, electrical, thermal, control and monitoring, manufacturing and maintenance aspects. These issues could impact the performance, cost, driving range and life cycle of the battery pack in electric vehicles

  3. Synthesis, structural and electrical characterizations of thermally ...

    African Journals Online (AJOL)

    Synthesis, structural and electrical characterizations of thermally evaporated Cu 2 SnS 3 thin films. ... The surface profilometer shows that the deposited films are rough. The XRD spectra identified the ... The electrical resistivity of the deposited Cu2SnS3 film is 2.55 x 10-3 Ωcm. The conductivity is in the order of 103 Ω-1cm-1.

  4. Structural, optical and electrical properties of chemically deposited ...

    Indian Academy of Sciences (India)

    Structural, optical and electrical properties of chemically deposited nonstoichiometric copper ... One of these compounds, CuInSe2, with its optical absorption .... is clear from SEM images that the number of grains goes on increasing with the ...

  5. Vibration, buckling and smart control of microtubules using piezoelectric nanoshells under electric voltage in thermal environment

    Energy Technology Data Exchange (ETDEWEB)

    Farajpour, A., E-mail: ariobarzan.oderj@gmail.com; Rastgoo, A.; Mohammadi, M.

    2017-03-15

    Piezoelectric nanomaterials such as zinc oxide (ZnO) are of low toxicity and have many biomedical applications including optical imaging, drug delivery, biosensing and harvesting biomechanical energy using hybrid nanogenerators. In this paper, the vibration, buckling and smart control of microtubules (MTs) embedded in an elastic medium in thermal environment using a piezoelectric nanoshell (PNS) are investigated. The MT and PNS are considered to be coupled by a filament network. The PNS is subjected to thermal loads and an external electric voltage which operates to control the mechanical behavior of the MT. Using the nonlocal continuum mechanics, the governing differential equations are derived. An exact solution is presented for simply supported boundary conditions. The differential quadrature method is also used to solve the governing equations for other boundary conditions. A detailed parametric study is conducted to investigate the effects of the elastic constants of surrounding medium and internal filament matrix, scale coefficient, electric voltage, the radius-to-thickness ratio of PNSs and temperature change on the smart control of MTs. It is found that the applied electric voltage can be used as an effective controlling parameter for the vibration and buckling of MTs.

  6. Optical Remote Sensing of Electric Fields Above Thunderstorms

    Science.gov (United States)

    Burns, B. M.; Carlson, B. E.; Lauben, D.; Cohen, M.; Smith, D.; Inan, U. S.

    2010-12-01

    Measurement of thunderstorm electric fields typically require balloon-borne measurements in the region of interest. Such measurements are cumbersome and provide limited information at a single point. Remote sensing of electric fields by Kerr-effect induced optical polarization changes of background skylight circumvents many of these difficulties and can in principle provide a high-speed movie of electric field behavior. Above-thundercloud 100 kV/m quasi-static electric fields are predicted to produce polarization changes at above the part in one million level that should be detectable at a ground instrument featuring 1 cm2sr geometric factor and 1 kHz bandwidth (though more sensitivity is nonetheless desired). Currently available optical and electronic components may meet these requirements. We review the principles of this measurement and discuss the current status of a field-ready prototype instrument currently in construction.

  7. Calcium fluoride whispering gallery mode optical resonator with reduced thermal sensitivity

    Science.gov (United States)

    Savchenkov, Anatoliy; Matsko, Andrey

    2018-03-01

    We demonstrate a crystalline CaF2 resonator with thermal sensitivity of the optical modes approaching zero. The resonator is made by laminating a calcium fluoride layer forming an optical monolithic cavity with ceramic compensation layers. The ceramics is characterized with negative thermal expansion coefficient achievable in a certain temperature range. The thermally compensated resonator has a potential application for laser frequency stabilization.

  8. Electricity storage using a thermal storage scheme

    Energy Technology Data Exchange (ETDEWEB)

    White, Alexander, E-mail: ajw36@cam.ac.uk [Hopkinson Laboratory, Cambridge University Engineering Department, Trumpington Street, Cambridge. CB2 1PZ (United Kingdom)

    2015-01-22

    The increasing use of renewable energy technologies for electricity generation, many of which have an unpredictably intermittent nature, will inevitably lead to a greater demand for large-scale electricity storage schemes. For example, the expanding fraction of electricity produced by wind turbines will require either backup or storage capacity to cover extended periods of wind lull. This paper describes a recently proposed storage scheme, referred to here as Pumped Thermal Storage (PTS), and which is based on “sensible heat” storage in large thermal reservoirs. During the charging phase, the system effectively operates as a high temperature-ratio heat pump, extracting heat from a cold reservoir and delivering heat to a hot one. In the discharge phase the processes are reversed and it operates as a heat engine. The round-trip efficiency is limited only by process irreversibilities (as opposed to Second Law limitations on the coefficient of performance and the thermal efficiency of the heat pump and heat engine respectively). PTS is currently being developed in both France and England. In both cases, the schemes operate on the Joule-Brayton (gas turbine) cycle, using argon as the working fluid. However, the French scheme proposes the use of turbomachinery for compression and expansion, whereas for that being developed in England reciprocating devices are proposed. The current paper focuses on the impact of the various process irreversibilities on the thermodynamic round-trip efficiency of the scheme. Consideration is given to compression and expansion losses and pressure losses (in pipe-work, valves and thermal reservoirs); heat transfer related irreversibility in the thermal reservoirs is discussed but not included in the analysis. Results are presented demonstrating how the various loss parameters and operating conditions influence the overall performance.

  9. Thermal conductivity of electron-doped CaMnO3 perovskites: Local lattice distortions and optical phonon thermal excitation

    International Nuclear Information System (INIS)

    Wang Yang; Sui Yu; Wang Xianjie; Su Wenhui; Liu Xiaoyang; Fan, Hong Jin

    2010-01-01

    The thermal transport properties of a series of electron-doped CaMnO 3 perovskites have been investigated. Throughout the temperature range 5-300 K, phonon thermal conductivity is dominant, and both electron and spin wave contributions are negligible. The short phonon mean free paths in this system result in the relatively low thermal conductivities. The strong phonon scatterings stem from the A-site mismatch and bond-length fluctuations induced by local distortions of MnO 6 octahedra. The thermal conductivity in the magnetically ordered state is enhanced as a result of the decrease in spin-phonon scattering. The results also indicate that above the magnetic ordering temperature, observable thermal excitation of optical phonons occurs. The contribution of optical phonons to thermal conductivity becomes non-negligible and is proposed to play an important role in the glass-like thermal transport behavior (i.e. positive temperature dependence of the thermal conductivity) in the paramagnetic state. These features can be understood in terms of an expression of thermal conductivity that includes both acoustic and optical phonon terms.

  10. Electricity pricing model in thermal generating stations under deregulation

    International Nuclear Information System (INIS)

    Reji, P.; Ashok, S.; Moideenkutty, K.M.

    2007-01-01

    In regulated public utilities with competitive power markets, deregulation has replaced the monopoly. Under the deregulated power market, the electricity price primarily depends on market mechanism and power demand. In this market, generators generally follow marginal pricing. Each generator fixes the electricity price based on their pricing strategy and it leads to more price volatility. This paper proposed a model to determine the electricity price considering all operational constraints of the plant and economic variables that influenced the price, for a thermal generating station under deregulation. The purpose of the model was to assist existing stations, investors in the power sector, regulatory authorities, transmission utilities, and new power generators in decision-making. The model could accommodate price volatility in the market and was based on performance incentive/penalty considering plant load factor, availability of the plant and peak/ off peak demand. The model was applied as a case study to a typical thermal utility in India to determine the electricity price. It was concluded that the case study of a thermal generating station in a deregulated environment showed that the electricity price mainly depended on the gross calorific value (GCV) of fuel, mode of operation, price of the fuel, and operating charges. 11 refs., 2 tabs., 1 fig

  11. Analysis Of ElectricalThermal Coupling Of Induction Machine ...

    African Journals Online (AJOL)

    The interaction of the Electrical and mechanical parts of Electrical machines gives rise to the heating of the machine's constituent parts. This consequently leads to an increase in temperature which if not properly monitored may lead to the breakdown of the machine. This paper therefore presents the Electrical and thermal ...

  12. Analysis of Large- Capacity Water Heaters in Electric Thermal Storage Programs

    Energy Technology Data Exchange (ETDEWEB)

    Cooke, Alan L. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Anderson, David M. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Winiarski, David W. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Carmichael, Robert T. [Cadeo Group, Washington D. C. (United States); Mayhorn, Ebony T. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Fisher, Andrew R. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2015-03-17

    This report documents a national impact analysis of large tank heat pump water heaters (HPWH) in electric thermal storage (ETS) programs and conveys the findings related to concerns raised by utilities regarding the ability of large-tank heat pump water heaters to provide electric thermal storage services.

  13. Model of optical phantoms thermal response upon irradiation with 975 nm dermatological laser

    Science.gov (United States)

    Wróbel, M. S.; Bashkatov, A. N.; Yakunin, A. N.; Avetisyan, Yu. A.; Genina, E. A.; Galla, S.; Sekowska, A.; Truchanowicz, D.; Cenian, A.; Jedrzejewska-Szczerska, M.; Tuchin, V. V.

    2018-04-01

    We have developed a numerical model describing the optical and thermal behavior of optical tissue phantoms upon laser irradiation. According to our previous studies, the phantoms can be used as substitute of real skin from the optical, as well as thermal point of view. However, the thermal parameters are not entirely similar to those of real tissues thus there is a need to develop mathematical model, describing the thermal and optical response of such materials. This will facilitate the correction factors, which would be invaluable in translation between measurements on skin phantom to real tissues, and gave a good representation of a real case application. Here, we present the model dependent on the data of our optical phantoms fabricated and measured in our previous preliminary study. The ambiguity between the modeling and the thermal measurements depend on lack of accurate knowledge of material's thermal properties and some exact parameters of the laser beam. Those parameters were varied in the simulation, to provide an overview of possible parameters' ranges and the magnitude of thermal response.

  14. Thermal and optical properties of porous silicon

    Directory of Open Access Journals (Sweden)

    Silva A. Ferreira da

    2001-01-01

    Full Text Available Thermal diffusivity and optical absorption have been investigated for porous silicon, at room temperature, using photoacoustic spectroscopy. The experimental results obtained conform well with the existing studies recently published. The value obtained for thermal diffusivity is 0.045 ± 0.002 cm²/s.The absorption onsets show energy structures, differing from the ordinary semiconductor of bulk type.

  15. A thermal study of an encapsulated electrical transformer

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, A. [Unidad Geotermia, Temixco (Mexico). Instituto de Investigaciones Electricas; Espinosa-Paredes, G. [Universidad Autonoma Metropolitana, Vicentina (Mexico). Dpto. de Ingenieria de Procesos e Hidraulica; Hernandez, I. [Centro de Sistemas de Manufactura, Nuevo Leon (Mexico). Instituto Tecnologico y de Estudios Superiores de Monterrey

    2002-11-01

    A thermal study of a 45 KVA-prototype encapsulated transformer is described. Casting resin systems were used as insulating systems for encapsulated electric transformers. Normal transformer operation is at full load and, thus the conductor and insulating system becomes hot owing to current circulation through the winding. To determine the various temperature distributions throughout the transformer, the thermal properties of the insulating system and boundary conditions must be known, so that hot spots are located via numerical modelling and maximum permissible temperatures are not attained. Results presented herein include thermal conductivity, thermal diffusivity, and specific heat capacity. Thermal conductivity was obtained experimentally by means of the line-source technique at various temperatures, between room temperature and 155{sup o}C which is the thermal limit of class F insulators. The thermal diffusivity was obtained by parameter estimation by fitting an approximate analytical model to the temperature-time data of the thermal conductivity experiment. Specific heat capacity was obtained from the definition of thermal diffusivity and the insulating-system density. In order to improve the electrical performance of the transformer criteria, a numerical simulation of the different dielectric structures was made using computer program. The boundary conditions for the thermal simulation stage were also determined experimentally from temperature test runs. Finally, in order to obtain data for thermal design, a numerical simulation of the high tension winding was carried out. The thermal simulation stage was performed at different current densities in the conductor with and without electrostatic shields to determine the temperature field and maximum attainable temperatures. Maximum transformer temperature were found to be 15-20{sup o}C below its thermal limit and a correlation of maximum temperature as function of circulating current was developed for design

  16. Electrical and optical deep level spectroscopy on Os doped p-InP

    International Nuclear Information System (INIS)

    Parveen, S.; Zafar, N.; Khan, A.; Qureshi, U.S.; Iqbal, M.Z.

    1997-01-01

    Transition metal (TM) impurities are introduced for obtaining semi insulating (III-V) compound semiconductors used as base material for electronic and optoelectronic devices. TM doping introduces near mid gap levels which are used to compensate shallow level donors and acceptors in (III-V) compound semiconductors. The study of electrical properties of heavier transition metals in InP has been turned to an active field of research owing to their potential to produce thermally stable semi insulating substrate materials. Osmium has been tried for this purpose in our work. InP: Os samples have been grown by low pressure metalorganic chemical vapour deposition (LP-MOCVD). Optical and electrical Deep Level Transient Spectroscopy Techniques have been used to characterise osmium related deep level defects in the p-type samples. Three majority carrier (Hole) emitting levels OsA, OsB, OsC and one minority carrier (electron) emitting level Osl are observed in the DLTS and ODLTS measurements on p-type InP:Os. ON optical injection, only Osl appears and all other majority carrier emitting levels disappear dramatically. Special emphasis is given to the detailed comparison by ODLTS and EDLTS, which yields important information on the relative capture cross-sections of Osmium induced levels in p-InP. (author)

  17. Thermal and Electrical Analysis of Mars Rover RTGs

    Energy Technology Data Exchange (ETDEWEB)

    Schock, Alfred; Or, Chuen T; Skrabek, Emanuel A

    2012-01-19

    The RTG designs described in the preceding paper in these proceedings were analyzed for their thermal and electrical performance. Each analysis consisted of coupled thermal, thermoelectric, and electrical analyses, using Fairchild-generated specialized computer codes. These were supplemented with preliminary structural and mass analyses. For each design, various cases representing different operating conditions (water-cooled/radiation-cooled, BOM/EOM, summer/winter, day/night) and different thermoelectric performance assumptions (from conservative to optimistic) were analyzed; and for every case, the heat flow rates, temperatures and electrical performance of each layer of thermoelectric elements and of the overall RTG were determined. The analyses were performed in great detail, to obtain accurate answers permitting meaningful comparisons between different designs. The results presented show the RTG performance achievable with current technology, and the performance improvements that would be achievable with various technology developments.

  18. Thermal and Electrical Conductivity Measurements of CDA 510 Phosphor Bronze

    Science.gov (United States)

    Tuttle, James E.; Canavan, Edgar; DiPirro, Michael

    2009-01-01

    Many cryogenic systems use electrical cables containing phosphor bronze wire. While phosphor bronze's electrical and thermal conductivity values have been published, there is significant variation among different phosphor bronze formulations. The James Webb Space Telescope (JWST) will use several phosphor bronze wire harnesses containing a specific formulation (CDA 510, annealed temper). The heat conducted into the JWST instrument stage is dominated by these harnesses, and approximately half of the harness conductance is due to the phosphor bronze wires. Since the JWST radiators are expected to just keep the instruments at their operating temperature with limited cooling margin, it is important to know the thermal conductivity of the actual alloy being used. We describe an experiment which measured the electrical and thermal conductivity of this material between 4 and 295 Kelvin.

  19. Differential and directional effects of perfusion on electrical and thermal conductivities in liver.

    Science.gov (United States)

    Podhajsky, Ronald J; Yi, Ming; Mahajan, Roop L

    2009-01-01

    Two different measurement probes--an electrical probe and a thermal conductivity probe--were designed, fabricated, calibrated, and used in experimental studies on a pig liver model that was designed to control perfusion rates. These probes were fabricated by photolithography and mounted in 1.5-mm diameter catheters. We measured the local impedance and thermal conductivity, respectively, of the artificially perfused liver at different flow rates and, by rotating the probes, in different directions. The results show that both the local electrical conductivity and the thermal conductivity varied location to location, that thermal conductivity increased with decreased distance to large blood vessels, and that significant directional differences exist in both electrical and thermal conductivities. Measurements at different perfusion rates demonstrated that both the local electrical and local thermal conductivities increased linearly with the square root of perfusion rate. These correlations may be of great value to many energy-based biomedical applications.

  20. Problems associated with accelerated thermal aging of electrical equipment

    International Nuclear Information System (INIS)

    Isgro, J.R.

    1984-01-01

    This paper discusses the potential problems that may be experienced when accounting for aging mechanisms in organic polymers when utilizing accelerated thermal aging techniques for electrical equipment qualification. Included are discussions of actual experiences and problems encountered in the qualification of electrical and electronic equipment for a complete nuclear power plant. The wide variety of approaches to thermal accelerated aging by various manufacturers of diverse equipment types provides depth to the discussion. A description of how to account for aging mechanisms is also presented

  1. Design of a fiber optical sensor for atmospheric electric field measurement

    International Nuclear Information System (INIS)

    Baghdasaryan, H.V.; Knyazyan, T.M.; Daryan, A.V.

    2016-01-01

    All-optical sensor for atmospheric electric field detection and measurement is suggested and numerically modelled. Thin electro- optical crystal sandwiched between two distributed Bragg reflectors (DBRs) forming multilayer Gires-Tournois (G-T) microresonator is used as a sensitive part of the electric field sensor. In the sensor device, an optical fiber delivers the wideband light spectrum to the sensing multilayer structure of G-T microresonator. The reflectance spectrum of the sensor contains information on the electric field strength and direction. The relevant reflectance peaks’ shift in the reflected spectrum can be observed by an optical spectrum analyzer (OSA). Numerical modelling has been done by the method of single expression that is a suitable tool for multi-boundary problems solution. The obtained results of modelling will be useful in a new type of non-distorting sensor’s elaboration for atmospheric electric field detection and measurement. (author)

  2. Solar thermal electric power information user study

    Energy Technology Data Exchange (ETDEWEB)

    Belew, W.W.; Wood, B.L.; Marle, T.L.; Reinhardt, C.L.

    1981-02-01

    The results of a series of telephone interviews with groups of users of information on solar thermal electric power are described. These results, part of a larger study on many different solar technologies, identify types of information each group needed and the best ways to get information to each group. The report is 1 of 10 discussing study results. The overall study provides baseline data about information needs in the solar community. An earlier study identified the information user groups in the solar community and the priority (to accelerate solar energy commercialization) of getting information to each group. In the current study only high-priority groups were examined. Results from five solar thermal electric power groups of respondents are analyzed: DOE-Funded Researchers, Non-DOE-Funded Researchers, Representatives of Utilities, Electric Power Engineers, and Educators. The data will be used as input to the determination of information products and services the Solar Energy Research Institute, the Solar Energy Information Data Bank Network, and the entire information outreach community should be preparing and disseminating.

  3. Electrically and Thermally Conducting Nanocomposites for Electronic Applications

    Directory of Open Access Journals (Sweden)

    Daryl Santos

    2010-02-01

    Full Text Available Nanocomposites made up of polymer matrices and carbon nanotubes are a class of advanced materials with great application potential in electronics packaging. Nanocomposites with carbon nanotubes as fillers have been designed with the aim of exploiting the high thermal, electrical and mechanical properties characteristic of carbon nanotubes. Heat dissipation in electronic devices requires interface materials with high thermal conductivity. Here, current developments and challenges in the application of nanotubes as fillers in polymer matrices are explored. The blending together of nanotubes and polymers result in what are known as nanocomposites. Among the most pressing current issues related to nanocomposite fabrication are (i dispersion of carbon nanotubes in the polymer host, (ii carbon nanotube-polymer interaction and the nature of the interface, and (iii alignment of carbon nanotubes in a polymer matrix. These issues are believed to be directly related to the electrical and thermal performance of nanocomposites. The recent progress in the fabrication of nanocomposites with carbon nanotubes as fillers and their potential application in electronics packaging as thermal interface materials is also reported.

  4. Optical interconnects

    CERN Document Server

    Chen, Ray T

    2006-01-01

    This book describes fully embedded board level optical interconnect in detail including the fabrication of the thin-film VCSEL array, its characterization, thermal management, the fabrication of optical interconnection layer, and the integration of devices on a flexible waveguide film. All the optical components are buried within electrical PCB layers in a fully embedded board level optical interconnect. Therefore, we can save foot prints on the top real estate of the PCB and relieve packaging difficulty reduced by separating fabrication processes. To realize fully embedded board level optical

  5. Impact of defects on the electrical transport, optical properties and failure mechanisms of GaN nanowires.

    Energy Technology Data Exchange (ETDEWEB)

    Armstrong, Andrew M.; Aubry, Sylvie; Shaner, Eric Arthur; Siegal, Michael P.; Li, Qiming; Jones, Reese E.; Westover, Tyler; Wang, George T.; Zhou, Xiao Wang; Talin, Albert Alec; Bogart, Katherine Huderle Andersen; Harris, C. Thomas; Huang, Jian Yu

    2010-09-01

    We present the results of a three year LDRD project that focused on understanding the impact of defects on the electrical, optical and thermal properties of GaN-based nanowires (NWs). We describe the development and application of a host of experimental techniques to quantify and understand the physics of defects and thermal transport in GaN NWs. We also present the development of analytical models and computational studies of thermal conductivity in GaN NWs. Finally, we present an atomistic model for GaN NW electrical breakdown supported with experimental evidence. GaN-based nanowires are attractive for applications requiring compact, high-current density devices such as ultraviolet laser arrays. Understanding GaN nanowire failure at high-current density is crucial to developing nanowire (NW) devices. Nanowire device failure is likely more complex than thin film due to the prominence of surface effects and enhanced interaction among point defects. Understanding the impact of surfaces and point defects on nanowire thermal and electrical transport is the first step toward rational control and mitigation of device failure mechanisms. However, investigating defects in GaN NWs is extremely challenging because conventional defect spectroscopy techniques are unsuitable for wide-bandgap nanostructures. To understand NW breakdown, the influence of pre-existing and emergent defects during high current stress on NW properties will be investigated. Acute sensitivity of NW thermal conductivity to point-defect density is expected due to the lack of threading dislocation (TD) gettering sites, and enhanced phonon-surface scattering further inhibits thermal transport. Excess defect creation during Joule heating could further degrade thermal conductivity, producing a viscous cycle culminating in catastrophic breakdown. To investigate these issues, a unique combination of electron microscopy, scanning luminescence and photoconductivity implemented at the nanoscale will be used in

  6. Optically and thermally controlled terahertz metamaterial via transition between direct and indirect electromagnetically induced transparency

    Directory of Open Access Journals (Sweden)

    Jiawei Sui

    2014-12-01

    Full Text Available This passage presents a design of tunable terahertz metamaterials via transition between indirect and direct electromagnetically induced transparency (EIT effects by changing semiconductor InSb’s properties to terahertz wave under optical and thermal stimuli. Mechanical model and its electrical circuit model are utilized in analytically calculating maximum transmission of transparency window. Simulated results show consistency with the analytical expressions. The results show that the metamaterials hold 98.4% modulation depth at 189 GHz between 300 K, σInSb =256000 S/m, and 80 K, σInSb =0.0162 S/m conditions , 1360 ps recovery time of the excited electrons in InSb under optical stimulus at 300 K mainly considering the direct EIT effect, and minimum bandwidth 1 GHz.

  7. Enhancement of the optical, thermal and electrical properties of PEO/PAM:Li polymer electrolyte films doped with Ag nanoparticles

    Science.gov (United States)

    Morsi, M. A.; El-Khodary, Sherif A.; Rajeh, A.

    2018-06-01

    Both lithium bromide (LiBr) and biosynthesized silver nanoparticles (Ag NPs) with average size 2-30 nm have been incorporated into the polymeric matrix of polyethylene oxide and polyacrylamide (PEO/PAM) blend by the casting method. FT-IR analysis indicates the formation of hydrogen bond between the blend components. Also, LiBr and Ag NPs interact with the functional groups of PEO/PAM matrix. The results of XRD analysis depict the semi-crystalline nature of these polymer samples and the degree of crystallinity is decreased due to the addition process. The values of optical energy gap from UV-Vis. data are decreased from 3.55 eV for blend to 3.26 for the nanocomposite sample in the indirect transition. LiBr/Ag NPs assist the improvement of the thermal stability of the PEO/PAM blend, as evidenced by TGA and DTA techniques. Upon the addition of LiBr and Ag NPs, an improvement for the conductivity, dielectric permittivity (έ) and dielectric loss (ἕ) of PEO/PAM solid polymer electrolytes are observed. It's clear that the improvement of the electrical conductivity and dielectric parameters for PEO/PAM: Li+/Ag NPs polymer electrolyte system makes it as a promising candidate for solid-state Li battery applications.

  8. Doping dependence of electrical and thermal conductivity of nanoscale polyaniline thin films

    Energy Technology Data Exchange (ETDEWEB)

    Jin Jiezhu; Wang Qing [Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA 16802 (United States); Haque, M A [Department of Mechanical and Nuclear Engineering, Pennsylvania State University, University Park, PA 16802 (United States)

    2010-05-26

    We performed simultaneous characterization of electrical and thermal conductivity of 55 nm thick polyaniline (PANI) thin films doped with different levels of camphor sulfonic acids (CSAs). The effect of the doping level is more pronounced on electrical conductivity than on thermal conductivity of PANIs, thereby greatly affecting their ratio that determines the thermoelectric efficiency. At the 60% (the molar ratio of CSA to phenyl-N repeat unit of PANI) doping level, PANI exhibited the maximum electrical and thermal conductivity due to the formation of mostly delocalized structures. Whereas polarons are the charge carriers responsible for the electrical conduction, phonons are believed to play a dominant role in the heat conduction in nanoscale doped PANI thin films.

  9. Thermal acclimation and thyroxine treatment modify the electric organ discharge frequency in an electric fish, Apteronotus leptorhynchus.

    Science.gov (United States)

    Dunlap, K D; Ragazzi, M A

    2015-11-01

    In ectotherms, the rate of many neural processes is determined externally, by the influence of the thermal environment on body temperature, and internally, by hormones secreted from the thyroid gland. Through thermal acclimation, animals can buffer the influence of the thermal environment by adjusting their physiology to stabilize certain processes in the face of environmental temperature change. The electric organ discharge (EOD) used by weak electric fish for electrocommunication and electrolocation is highly temperature sensitive. In some temperate species that naturally experience large seasonal fluctuations in environmental temperature, the thermal sensitivity (Q10) of the EOD shifts after long-term temperature change. We examined thermal acclimation of EOD frequency in a tropical electric fish, Apteronotus leptorhynchus that naturally experiences much less temperature change. We transferred fish between thermal environments (25.3 and 27.8 °C) and measured EOD frequency and its thermal sensitivity (Q10) over 11 d. After 6d, fish exhibited thermal acclimation to both warming and cooling, adjusting the thermal dependence of EOD frequency to partially compensate for the small change (2.5 °C) in water temperature. In addition, we evaluated the thyroid influence on EOD frequency by treating fish with thyroxine or the anti-thyroid compound propylthiouricil (PTU) to stimulate or inhibit thyroid activity, respectively. Thyroxine treatment significantly increased EOD frequency, but PTU had no effect. Neither thyroxine nor PTU treatment influenced the thermal sensitivity (Q10) of EOD frequency during acute temperature change. Thus, the EOD of Apteronotus shows significant thermal acclimation and responds to elevated thyroxine. Copyright © 2015 Elsevier Inc. All rights reserved.

  10. A 10 Gbit/s OCDMA system based on electric encoding and optical transmission

    Science.gov (United States)

    Li, Chuan-qi; Hu, Jin-lin; He, Dong-dong; Chen, Mei-juan; Wang, Da-chi; Chen, Yan

    2013-11-01

    An electric encoded/optical transmission system of code division multiple access (CDMA) is proposed. It encodes the user signal in electric domain, and transfers the different code slice signals via the different wavelengths of light. This electric domain encoder/decoder is compared with current traditional encoder/decoder. Four-user modulation/demodulation optical CDMA (OCDMA) system with rate of 2.5 Gbit/s is simulated, which is based on the optical orthogonal code (OCC) designed in our laboratory. The results show that the structure of electric encoding/optical transmission can encode/decode signal correctly, and can achieve the chip rate equal to the user data rate. It can overcome the rate limitation of electronic bottleneck, and bring some potential applications in the electro-optical OCDMA system.

  11. Thermal management evaluation of the complex electro-optical system

    Directory of Open Access Journals (Sweden)

    Nijemčević Srećko S.

    2017-01-01

    Full Text Available The thermal management of a complex electro-optical system aimed for outdoor application is challenging task due to the requirement of having an air-sealed enclosure, harsh working environment, and an additional thermal load generated by sunlight. It is essential to consider the effect of heating loads in the system components, as well as the internal temperature distribution, that can have influence on the system life expectancy, operational readiness and parameters, and possibility for catastrophic failure. The main objective of this paper is to analyze internal temperature distribution and evaluate its influence on system component operation capability. The electro-optical system simplified model was defined and related thermal balance simulation model based on Solid Works thermal analysis module was set and applied for temperature distribution calculation. Various outdoor environment scenarios were compared to evaluate system temperature distribution and evaluate its influence on system operation, reliability, and life time in application environment. This work was done during the design process as a part of the electro-optical system optimization. The results show that temperature distribution will not be cause for catastrophic failure and malfunction operation during operation in the expected environment.

  12. Performance results of a solar greenhouse combining electrical and thermal energy production

    NARCIS (Netherlands)

    Sonneveld, P.J.; Swinkels, G.L.A.M.; Campen, J.B.; Tuijl, van B.A.J.; Janssen, H.J.J.; Bot, G.P.A.

    2010-01-01

    Performance results are given of a new type of greenhouse, which combines reflection of near infrared radiation (NIR) with electrical power generation using hybrid photovoltaic cell/thermal collector modules. Besides the generation of electrical and thermal energy, the reflection of the NIR will

  13. Dynamic nonlinear thermal optical effects in coupled ring resonators

    Directory of Open Access Journals (Sweden)

    Chenguang Huang

    2012-09-01

    Full Text Available We investigate the dynamic nonlinear thermal optical effects in a photonic system of two coupled ring resonators. A bus waveguide is used to couple light in and out of one of the coupled resonators. Based on the coupling from the bus to the resonator, the coupling between the resonators and the intrinsic loss of each individual resonator, the system transmission spectrum can be classified by three different categories: coupled-resonator-induced absorption, coupled-resonator-induced transparency and over coupled resonance splitting. Dynamic thermal optical effects due to linear absorption have been analyzed for each category as a function of the input power. The heat power in each resonator determines the thermal dynamics in this coupled resonator system. Multiple “shark fins” and power competition between resonators can be foreseen. Also, the nonlinear absorption induced thermal effects have been discussed.

  14. Experimental investigation on thermal management of electric vehicle battery with heat pipe

    International Nuclear Information System (INIS)

    Rao Zhonghao; Wang Shuangfeng; Wu Maochun; Lin Zirong; Li Fuhuo

    2013-01-01

    Highlights: ► The thermal management system of electric vehicle battery with heat pipes was designed. ► Temperature rise is a key factor for the design of power battery thermal management system. ► Temperature distribution is inevitable to reference for better design of heat pipes used for heat dissipation. ► Heat pipes are effective for power batteries thermal management within electric vehicles. - Abstract: In order to increase the cycle time of power batteries and decrease the overall cost of electric vehicles, the thermal management system equipped with heat pipes was designed according to the heat generated character of power batteries. The experimental result showed that the maximum temperature could be controlled below 50 °C when the heat generation rate was lower than 50 W. Coupled with the desired temperature difference, the heat generation rate should not exceed 30 W. The maximum temperature and temperature difference are kept within desired rang under unsteady operating conditions and cycle testing conditions. Applying heat pipes based power batteries thermal management is an effective method for energy saving in electric vehicles.

  15. Manufacturing and testing flexible microfluidic devices with optical and electrical detection mechanisms

    Science.gov (United States)

    Ivan, Marius G.; Vivet, Frédéric; Meinders, Erwin R.

    2010-06-01

    Flexible microfluidic devices made of poly(dimethylsiloxane) (PDMS) were manufactured by soft lithography, and tested in detection of ionic species using optical absorption spectroscopy and electrical measurements. PDMS was chosen due to its flexibility and ease of surface modification by exposure to plasma and UV treatment, its transparency in UV-Vis regions of the light spectrum, and biocompatibility. The dual-detection mechanism allows the user more freedom in choosing the detection tool, and a functional device was successfully tested. Optical lithography was employed for manufacturing templates, which were subsequently used for imprinting liquid PDMS by thermal curing. Gold electrodes having various widths and distances among them were patterned with optical lithography on the top part which sealed the microchannels, and the devices were employed for detection of ionic species in aqueous salt solutions as well as micro-electrolysis cells. Due to the transparency of PDMS in UV-Vis the microfluidics were also used as photoreactors, and the in-situ formed charged species were monitored by applying a voltage between electrodes. Upon addition of a colorimetric pH sensor, acid was detected with absorption spectroscopy.

  16. Fiber Optic Thermal Health Monitoring of Composites

    Science.gov (United States)

    Wu, Meng-Chou; Winfree, William P.; Moore, Jason P.

    2010-01-01

    A recently developed technique is presented for thermographic detection of flaws in composite materials by performing temperature measurements with fiber optic Bragg gratings. Individual optical fibers with multiple Bragg gratings employed as surface temperature sensors were bonded to the surfaces of composites with subsurface defects. The investigated structures included a 10-ply composite specimen with subsurface delaminations of various sizes and depths. Both during and following the application of a thermal heat flux to the surface, the individual Bragg grating sensors measured the temporal and spatial temperature variations. The data obtained from grating sensors were analyzed with thermal modeling techniques of conventional thermography to reveal particular characteristics of the interested areas. Results were compared with the calculations using numerical simulation techniques. Methods and limitations for performing in-situ structural health monitoring are discussed.

  17. Thermal modeling of secondary lithium batteries for electric vehicle/hybrid electric vehicle applications

    Science.gov (United States)

    Al-Hallaj, Said; Selman, J. R.

    A major obstacle to the development of commercially successful electric vehicles (EV) or hybrid electric vehicles (HEV) is the lack of a suitably sized battery. Lithium ion batteries are viewed as the solution if only they could be "scaled-up safely", i.e. if thermal management problems could be overcome so the batteries could be designed and manufactured in much larger sizes than the commercially available near-2-Ah cells. Here, we review a novel thermal management system using phase-change material (PCM). A prototype of this PCM-based system is presently being manufactured. A PCM-based system has never been tested before with lithium-ion (Li-ion) batteries and battery packs, although its mode of operation is exceptionally well suited for the cell chemistry of the most common commercially available Li-ion batteries. The thermal management system described here is intended specifically for EV/HEV applications. It has a high potential for providing effective thermal management without introducing moving components. Thereby, the performance of EV/HEV batteries may be improved without complicating the system design and incurring major additional cost, as is the case with "active" cooling systems requiring air or liquid circulation.

  18. Thermal energy storage for electricity-driven space heating in a day-ahead electricity market

    DEFF Research Database (Denmark)

    Pensini, Alessandro

    2012-01-01

    Thermal Energy Storage (TES) in a space heating (SH) application was investigated. The study aimed to determine the economic benefits of introducing TES into an electricity-driven SH system under a day-ahead electricity market. The performance of the TES was assessed by comparing the cost...... of electricity in a system with a TES unit to the case where no storage is in use and the entire heat requirement is fulfilled by purchasing electricity according to the actual load. The study had two goals: 1. Determining how the size – in terms of electricity input (Pmax) and energy capacity (Emax...

  19. Possibilities for retrofitting of the existing thermal electric power plants using solar power technologies

    International Nuclear Information System (INIS)

    Matjanov, Erkinjon K.; Abduganieva, Farogat A.; Aminov, Zarif Z.

    2012-01-01

    Full text: Total installed electric power output of the existing thermal electric power plants in Uzbekistan is reaches 12 GW. Thermal electric power plants, working on organic fuel, produce around 88 % of the electricity in the country. The emission coefficient of CO 2 gases is 620 gram/kwph. Average electric efficiency of the thermal electric power plants is 32.1 %. The mentioned above data certifies, that the existing thermal electric power plants of Uzbekistan are physically and morally aged and they need to be retrofitted. Retrofitting of the existing thermal electric power plants can be done by several ways such as via including gas turbine toppings, by using solar technologies, etc. Solar thermal power is a relatively new technology which has already shown its enormous promise. With few environmental impacts and a massive resource, it offers a comparable opportunity to the sunniest Uzbekistan. Solar thermal power uses direct sunlight, so it must be sited in regions with high direct solar radiation. In many regions, one square km of land is enough to generate as much as 100-120 GWh of electricity per year using the solar thermal technology. This is equivalent to the annual production of a 50 MW conventional coal or gas-fired mid-load power plant. Solar thermal power plants can be designed for solar-only or for hybrid operation. Producing electricity from the energy in the sun's rays is a straightforward process: direct solar radiation can be concentrated and collected by a range of Concentrating Solar Power technologies to provide medium- to high temperature heat. This heat is then used to operate a conventional power cycle, for example through a steam turbine or a Stirling engine. Solar heat collected during the day can also be stored in liquid or solid media such as molten salts, ceramics, concrete or, in the future, phase-changing salt mixtures. At night, it can be extracted from the storage medium thereby continuing turbine operation. Currently, the

  20. Solar electric power generation photovoltaic energy systems

    CERN Document Server

    Krauter, Stefan CW

    2007-01-01

    Solar electricity is a viable, environmentally sustainable alternative to the world's energy supplies. In support, this work examines the various technical parameters of photovoltaic systems. It analyzes the study of performance and yield (including optical, thermal, and electrical parameters and interfaces).

  1. Thermal and Electrical Characterization of Alumina Substrate for Microelectronic Applications

    International Nuclear Information System (INIS)

    Ahmad, S.; Ibrahim, A.; Alias, R.; Shapee, S. M.; Ambak, Z.; Zakaria, S. Z.; Yahya, M. R.; Mat, A. F. A.

    2010-01-01

    This paper reports the effect of sintering temperature on thermal and electrical properties of alumina material as substrate for microelectronic devices. Alumina materials in the form of green sheet with 1 mm thickness were sintered at 1100 deg. C, 1300 deg. C and 1500 deg. C for about 20 hours using heating and cooling rates of 2 deg. C/min. The densities were measured using densitometer and the microstructures of the samples were analyzed using SEM micrographs. Meanwhile thermal and electrical properties of the samples were measured using flash method and impedance analyzer respectively. It was found that thermal conductivity and thermal diffusivity of the substrate increases as sintering temperature increases. It was found also that the dielectric constant of alumina substrate increases as the sintering temperature increases.

  2. Thermal and Electrical Characterization of Alumina Substrate for Microelectronic Applications

    Science.gov (United States)

    Ahmad, S.; Ibrahim, A.; Alias, R.; Shapee, S. M.; Ambak, Z.; Zakaria, S. Z.; Yahya, M. R.; Mat, A. F. A.

    2010-03-01

    This paper reports the effect of sintering temperature on thermal and electrical properties of alumina material as substrate for microelectronic devices. Alumina materials in the form of green sheet with 1 mm thickness were sintered at 1100° C, 1300° C and 1500° C for about 20 hours using heating and cooling rates of 2° C/min. The densities were measured using densitometer and the microstructures of the samples were analyzed using SEM micrographs. Meanwhile thermal and electrical properties of the samples were measured using flash method and impedance analyzer respectively. It was found that thermal conductivity and thermal diffusivity of the substrate increases as sintering temperature increases. It was found also that the dielectric constant of alumina substrate increases as the sintering temperature increases.

  3. Electric-field effects in optically generated spin transport

    International Nuclear Information System (INIS)

    Miah, M. Idrish

    2009-01-01

    Transport of spin-polarized electrons in semiconductors is studied experimentally. Spins are generated by optical excitation because of the selection rules governing optical transitions from heavy-hole and light-hole states to conduction-band states. Experiments designed for the control of spins in semiconductors investigate the bias-dependent spin transport process and detect the spin-polarized electrons during transport. A strong bias dependence is observed. The electric-field effects on the spin-polarized electron transport are also found to be depended on the excitation photon energy and temperature. Based on a field-dependent spin relaxation mechanism, the electric-field effects in the transport process are discussed.

  4. Electric-field effects in optically generated spin transport

    Energy Technology Data Exchange (ETDEWEB)

    Miah, M. Idrish [Nanoscale Science and Technology Centre and School of Biomolecular and Physical Sciences, Griffith University, Nathan, Brisbane, QLD 4111 (Australia); Department of Physics, University of Chittagong, Chittagong 4331 (Bangladesh)], E-mail: m.miah@griffith.edu.au

    2009-05-25

    Transport of spin-polarized electrons in semiconductors is studied experimentally. Spins are generated by optical excitation because of the selection rules governing optical transitions from heavy-hole and light-hole states to conduction-band states. Experiments designed for the control of spins in semiconductors investigate the bias-dependent spin transport process and detect the spin-polarized electrons during transport. A strong bias dependence is observed. The electric-field effects on the spin-polarized electron transport are also found to be depended on the excitation photon energy and temperature. Based on a field-dependent spin relaxation mechanism, the electric-field effects in the transport process are discussed.

  5. Effect of ethylene carbonate as a plasticizer on CuI/PVA nanocomposite: Structure, optical and electrical properties

    Directory of Open Access Journals (Sweden)

    Shaimaa A. Mohamed

    2014-01-01

    Full Text Available Layers of ethylene carbonate (EC modified CuI/PVA polymer composites were prepared by growth of CuI nano-particles in an aqueous solution of PVA followed by casting at room temperature. The structural, thermal, optical, electrical and di-electrical characterization of polymer composites was investigated using different techniques. These investigations confirm the growth of CuI nano-particles and reduction of PVA crystallinity by increasing ethylene carbonate concentration. These results show that energy band gap and bulk conductivity increase while activation energy reduces with the increase of EC concentration in the composite. Moreover, the variation of the dielectric permittivity and dielectric loss with EC content are found to obey Debye dispersion relations.

  6. The chromatographic separation of particles using optical electric fields

    DEFF Research Database (Denmark)

    Javier Alvarez, Nicolas; Jeppesen, Claus; Yvind, Kresten

    2013-01-01

    We introduce a new field-flow fractionation (FFF) technique, whereby molecules are separated based on their differential interaction (dielectrophoresis (DEP)) with optical electric fields, i.e. electric fields with frequencies in the visible and near-infrared range. The results show that a parall...

  7. Optical and Electrical Studies of Polyaniline/ZnO Nanocomposite

    Directory of Open Access Journals (Sweden)

    Manawwer Alam

    2013-01-01

    Full Text Available Polyaniline (Pani/ZnO nanocomposite with diameter 40–50 nm was successfully fabricated by coprecipitation method of ZnO via in situ polymerization of Pani. X-ray diffraction (XRD, high resolution transmission electron microscopy (HRTEM, fourier transformation infrared (FT-IR, UV-Vis absorption spectra, thermogravimetric analysis (TGA, and electrical properties were studied. HRTEM studies showed that the prepared ZnO nanoparticles were uniformly dispersed and highly stabilized throughout the polymer chain and formed uniform metal oxide-conducting polymer nanocomposite material. UV-Vis spectra of Pani/ZnO nanocomposite were studied to investigate the optical behavior after doping the ZnO nanoparticle into the polymer matrix. The inclusion of ZnO nanoparticle gives rise to the red shift of π-π* transition of Pani. The nanocomposite was found to be thermally stable upto 130°C and showed conductivity value of 3.0×10−2 Scm−1.

  8. Thermally promoted addition of undecylenic acid on thermally hydrocarbonized porous silicon optical reflectors

    OpenAIRE

    Jalkanen, Tero; Mäkilä, Ermei; Sakka, Tetsuo; Salonen, Jarno; Ogata, Yukio H

    2012-01-01

    Thermally promoted addition of undecylenic acid is studied as a method for modifying porous silicon optical reflectors that have been pre-treated with thermal hydrocarbonization. Successful derivatization of undecylenic acid is demonstrated and confirmed with Fourier transform infrared and X-ray photoelectron spectroscopies. The results indicate that the hydrocarbonization pre-treatment considerably improves stability against oxidation and chemical dissolution in basic environments. The two-s...

  9. Experimental investigation of an optical water filter for Photovoltaic/Thermal conversion module

    International Nuclear Information System (INIS)

    Al-Shohani, Wisam A.M.; Sabouri, Aydin; Al-Dadah, Raya; Mahmoud, Saad; Butt, Haider

    2016-01-01

    Highlights: • New design of Photovoltaic/Thermal system is proposed. • Using the optical water layer as a spectrum splitter is tested experimentally. • Optical rig is developed to study the optical performance of water layer. • Energy conversion under different water layer thicknesses is determined. - Abstract: This paper presents an experimental investigation of a novel optical water filter used for Photovoltaic/Thermal and Concentrating Photovoltaic/Thermal modules. A water layer is used as a spectrum splitter of solar radiation placed above the photovoltaic cells and as a thermal working fluid simultaneously. The water layer absorbs the ultraviolet and part of infrared, which are not used by the photovoltaic, but transmits the visible and some of infrared to the solar cell surface which are used by the photovoltaic. In this work, the transmittance of the optical water filter was measured for different water thicknesses (1, 2, 3, 4, and 5 cm) and radiation wavelength ranging from 0.35 to 1 μm. Results show that there is a significant effect of the water layer thickness on the transmittance of the spectra where the transmittance decreases as the water layer increases. Moreover, energy conversion rate of photovoltaic with the optical water filter at different water layer thicknesses has been determined.

  10. Characterization of Contact and Bulk Thermal Resistance of Laminations for Electric Machines

    Energy Technology Data Exchange (ETDEWEB)

    Cousineau, J. Emily [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Bennion, Kevin [National Renewable Energy Laboratory (NREL), Golden, CO (United States); DeVoto, Doug [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Mihalic, Mark [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Narumanchi, Sreekant [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

    2015-06-30

    The ability to remove heat from an electric machine depends on the passive stack thermal resistances within the machine and the convective cooling performance of the selected cooling technology. This report focuses on the passive thermal design, specifically properties of the stator and rotor lamination stacks. Orthotropic thermal conductivity, specific heat, and density are reported. Four materials commonly used in electric machines were tested, including M19 (29 and 26 gauge), HF10, and Arnon 7 materials.

  11. Sectoral Innovation Foresight. Electrical and Optical Equipment Sector. Final report. Task 2

    NARCIS (Netherlands)

    Broek, T. van den; Giessen, A.M. van der

    2010-01-01

    The goal of this study is to highlight possible future developments of importance to the electrical and optical (E&O) equipment sector, paying particular importance to ‘radical’ changes and discussing policy options and future scenarios. The electrical & optical equipment sector plays a vital role

  12. Thermal electric effects and heat generation in polypyrrole coated PET fabrics

    OpenAIRE

    Avloni, J.; Florio, L.; Henn, A. R.; Sparavigna, A.

    2007-01-01

    Polypyrrole chemically synthesized on PET gives rise to textiles with a high electric conductivity, suitable for several applications from antistatics to electromagnetic interference shielding devices. Here, we discuss investigations on thermal electric performances of the polypyrrole coated PET in a wide range of temperatures above room temperature. The Seebeck coefficient turns out to be comparable with that of metal thermocouple materials. Since polypyrrole shows extremely low thermal diff...

  13. Structural, optical and electrical properties of quasi-monocrystalline silicon thin films obtained by rapid thermal annealing of porous silicon layers

    International Nuclear Information System (INIS)

    Hajji, M.; Khardani, M.; Khedher, N.; Rahmouni, H.; Bessais, B.; Ezzaouia, H.; Bouchriha, H.

    2006-01-01

    Quasi-mono-crystalline silicon (QMS) layers have a top surface like crystalline silicon with small voids in the body. Such layers are reported to have a higher absorption coefficient than crystalline silicon at the interesting range of the solar spectrum for photovoltaic application. In this work we present a study of the structural, optical and electrical properties of quasimonocrystalline silicon thin films. Quasimonocrystalline silicon thin films were obtained from porous silicon, which has been annealed at a temperature ranging from 950 to 1050 deg. C under H 2 atmosphere for different annealing durations. The porous layers were prepared by conventional electrochemical anodization using a double tank cell and a HF / Ethanol electrolyte. Porous silicon is formed on highly doped p + -type silicon substrates that enable us to prevent back contacts for the anodization. Atomic Force Microscope (AFM) was used to study the morphological quality of the prepared layers. Optical properties were extracted from transmission and reflectivity spectra. Dark I-V characteristics were used to determine the electrical conductivity of quasimonocrystalline silicon thin films. Results show an important improvement of the absorption coefficient of the material and electrical conductivity reaches a value of twenty orders higher than that of starting mesoporous silicon

  14. On-line energy and battery thermal management for hybrid electric heavy-duty truck

    NARCIS (Netherlands)

    Pham, H.T.; Kessels, J.T.B.A.; Bosch, van den P.P.J.; Huisman, R.G.M.; Nevels, R.M.P.A.

    2013-01-01

    This paper discusses an integrated approach for energy and thermal management to minimize the fuel consumption of a hybrid electric heavy-duty truck. Conventional Energy Management Systems (EMS) operate separately from the Battery Thermal Management System (BTMS) in Hybrid Electric Vehicles (HEVs).

  15. Structural, optical and electrical characteristics of nickel oxide thin films synthesised through chemical processing method

    Science.gov (United States)

    Akinkuade, Shadrach; Mwankemwa, Benanrd; Nel, Jacqueline; Meyer, Walter

    2018-04-01

    A simple and cheap chemical deposition method was used to produce a nickel oxide (NiO) thin film on glass substrates from a solution that contained Ni2+ and monoethanolamine. Thermal treatment of the film at temperatures above 350 °C for 1 h caused decomposition of the nickel hydroxide into nickel oxide. Structural, optical and electrical properties of the film were studied using X-ray diffraction (XRD), spectrophotometry, current-voltage measurements and scanning electron microscopy (SEM). The film was found to be polycrystalline with interplanar spacing of 0.241 nm, 0.208 nm and 0.148 nm for (111), (200) and (220) planes respectively, the lattice constant a was found to be 0.417 nm. The film had a porous surface morphology, formed from a network of nanowalls of average thickness of 66.67 nm and 52.00 nm for as-deposited and annealed films respectively. Transmittance of visible light by the as-deposited film was higher and the absorption edge of the film blue-shifted after annealing. The optical band gap of the annealed film was 3.8 eV. Electrical resistivity of the film was 378 Ωm.

  16. An FBG Optical Approach to Thermal Expansion Measurements under Hydrostatic Pressure.

    Science.gov (United States)

    Rosa, Priscila F S; Thomas, Sean M; Balakirev, Fedor F; Betts, Jon; Seo, Soonbeom; Bauer, Eric D; Thompson, Joe D; Jaime, Marcelo

    2017-11-04

    We report on an optical technique for measuring thermal expansion and magnetostriction at cryogenic temperatures and under applied hydrostatic pressures of 2.0 GPa. Optical fiber Bragg gratings inside a clamp-type pressure chamber are used to measure the strain in a millimeter-sized sample of CeRhIn₅. We describe the simultaneous measurement of two Bragg gratings in a single optical fiber using an optical sensing instrument capable of resolving changes in length [dL/L = (L- L₀)/L₀] on the order of 10 -7 . Our results demonstrate the possibility of performing high-resolution thermal expansion measurements under hydrostatic pressure, a capability previously hindered by the small working volumes typical of pressure cells.

  17. Fiber Optic Thermal Detection of Composite Delaminations

    Science.gov (United States)

    Wu, Meng-Chou; Winfree, William P.

    2011-01-01

    A recently developed technique is presented for thermographic detection of delaminations in composites by performing temperature measurements with fiber optic Bragg gratings. A single optical fiber with multiple Bragg gratings employed as surface temperature sensors was bonded to the surface of a composite with subsurface defects. The investigated structure was a 10-ply composite specimen with prefabricated delaminations of various sizes and depths. Both during and following the application of a thermal heat flux to the surface, the individual Bragg grating sensors measured the temporal and spatial temperature variations. The data obtained from grating sensors were analyzed with thermal modeling techniques of conventional thermography to reveal particular characteristics of the interested areas. Results were compared and found to be consistent with the calculations using numerical simulation techniques. Also discussed are methods including various heating sources and patterns, and their limitations for performing in-situ structural health monitoring.

  18. Crystal growth, structural, optical, thermal, mechanical, laser damage threshold and electrical properties of triphenylphosphine oxide 4-nitrophenol (TP4N) single crystals for nonlinear optical applications

    Science.gov (United States)

    Karuppasamy, P.; Senthil Pandian, Muthu; Ramasamy, P.; Verma, Sunil

    2018-05-01

    The optically good quality single crystals of triphenylphosphine oxide 4-nitrophenol (TP4N) with maximum dimension of 15 × 10 × 5 mm3 were grown by slow evaporation solution technique (SEST) at room temperature. The cell dimensions of the grown TP4N crystal were confirmed by single crystal X-ray diffraction (SXRD) and the crystalline purity was confirmed and planes were indexed by powder X-ray diffraction (PXRD) analysis. Functional groups of TP4N crystal were confirmed by Fourier transform infrared (FTIR) spectral analysis. The optical transmittance of the grown crystal was determined by the UV-Vis NIR spectral analysis and it has good optical transparency in the entire visible region. The band tail (Urbach) energy of the grown crystal was analyzed and it appears to be minimum, which indicates that the TP4N has good crystallinity. The position of valence band (Ev) and conduction band (Ec) of the TP4N have been determined from the electron affinity energy (EA) and the ionization energy (EI) of its elements and using the optical band gap. The thermal behaviour of the grown crystal was investigated by thermogravimetric and differential thermal analysis (TG-DTA). Vickers microhardness analysis was carried out to identify the mechanical stability of the grown crystal and their indentation size effect (ISE) was explained by the Meyer's law (ML), Hays-Kendall's (HK) approach, proportional specimen resistance (PSR) model, modified PSR model (MPSR), elastic/plastic deformation (EPD) model and indentation induced cracking (IIC) model. Chemical etching study was carried out to find the etch pit density (EPD) of the grown crystal. Laser damage threshold (LDT) value was measured by using Nd:YAG laser (1064 nm). The dielectric permittivity (ε՛) and dielectric loss (tan δ) as a function of frequency was measured. The electronic polarizability (α) of the TP4N crystal was calculated. It is well matched to the value which was calculated from Clausius-Mossotti relation

  19. Structural, optical and electrical properties of cadmium-doped lead chalcogenide (PbSe) thin films

    International Nuclear Information System (INIS)

    Khan, Shamshad A.; Khan, Zishan H.; El-Sebaii, A.A.; Al-Marzouki, F.M.; Al-Ghamdi, A.A.

    2010-01-01

    (PbSe) 100-x Cd x thin films of thickness 3000 A with variable concentrations of Cd (x=5, 10, 15 and 20) were prepared by thermal evaporation on glass substrates at room temperature at a base pressure of 10 -6 Torr. The structural, optical and electrical properties of these films were studied. X-ray diffraction patterns were used to determine the crystal structure of the films. Films were of polycrystalline texture over the whole range of study. Optical constants of all films were determined by absorbance and reflection measurements in a wavelength range 400-1200 nm. Analysis of the optical absorption data showed that the rule of direct transitions predominates. The values of the absorption coefficient (α), extinction coefficient (k) and imaginary part of the dielectric constant were found to increase with increasing Cd content in lead chalcogenides while the refractive index (n) and real part of dielectric constant were increased with increasing Cd concentration up to 15% and then they decreased with 20% of Cd content in PbSe. These results were interpreted in terms of the change in concentration of localized states due to the shift in Fermi level. The dc conductivities and activation energies of the films were measured in the temperature range 298-398 K. It was observed that the dc conductivity increases at all temperatures with the increase of Cd content in lead chalcogenide system. The experimental data suggests that the conduction is due to the thermally assisted tunneling of the carriers in the localized states near the band edges. The activation energy and optical band gap were found to decrease with increasing Cd concentration in lead chalcogenide.

  20. Electrical and Thermal Conductivity and Conduction Mechanism of Ge2Sb2Te5 Alloy

    Science.gov (United States)

    Lan, Rui; Endo, Rie; Kuwahara, Masashi; Kobayashi, Yoshinao; Susa, Masahiro

    2018-06-01

    Ge2Sb2Te5 alloy has drawn much attention due to its application in phase-change random-access memory and potential as a thermoelectric material. Electrical and thermal conductivity are important material properties in both applications. The aim of this work is to investigate the temperature dependence of the electrical and thermal conductivity of Ge2Sb2Te5 alloy and discuss the thermal conduction mechanism. The electrical resistivity and thermal conductivity of Ge2Sb2Te5 alloy were measured from room temperature to 823 K by four-terminal and hot-strip method, respectively. With increasing temperature, the electrical resistivity increased while the thermal conductivity first decreased up to about 600 K then increased. The electronic component of the thermal conductivity was calculated from the Wiedemann-Franz law using the resistivity results. At room temperature, Ge2Sb2Te5 alloy has large electronic thermal conductivity and low lattice thermal conductivity. Bipolar diffusion contributes more to the thermal conductivity with increasing temperature. The special crystallographic structure of Ge2Sb2Te5 alloy accounts for the thermal conduction mechanism.

  1. Electrical and Thermal Conductivity and Conduction Mechanism of Ge2Sb2Te5 Alloy

    Science.gov (United States)

    Lan, Rui; Endo, Rie; Kuwahara, Masashi; Kobayashi, Yoshinao; Susa, Masahiro

    2017-11-01

    Ge2Sb2Te5 alloy has drawn much attention due to its application in phase-change random-access memory and potential as a thermoelectric material. Electrical and thermal conductivity are important material properties in both applications. The aim of this work is to investigate the temperature dependence of the electrical and thermal conductivity of Ge2Sb2Te5 alloy and discuss the thermal conduction mechanism. The electrical resistivity and thermal conductivity of Ge2Sb2Te5 alloy were measured from room temperature to 823 K by four-terminal and hot-strip method, respectively. With increasing temperature, the electrical resistivity increased while the thermal conductivity first decreased up to about 600 K then increased. The electronic component of the thermal conductivity was calculated from the Wiedemann-Franz law using the resistivity results. At room temperature, Ge2Sb2Te5 alloy has large electronic thermal conductivity and low lattice thermal conductivity. Bipolar diffusion contributes more to the thermal conductivity with increasing temperature. The special crystallographic structure of Ge2Sb2Te5 alloy accounts for the thermal conduction mechanism.

  2. Optical and Electrical Properties of Ar+ Implanted PET

    Science.gov (United States)

    Kumar, Rajiv; Shekhawat, Nidhi; Sharma, Annu; Aggarwal, Sanjeev; Kumar, Praveen; Kanjilal, D.

    2011-07-01

    In the present work, the effect of 100 keV argon ion implantation on the optical and electrical properties of PET has been studied. A continuous reduction in optical band gap (from 3.63 to 1.93 eV) with increasing implantation dose has been observed as analyzed using UV-Visible absorption spectroscopy. Current-Voltage (I-V) characteristics have been studied which clearly indicate the enhancement in the conductivity of PET specimens as an effect of implantation. This increase in conductivity has been correlated with the decrease in optical band gap.

  3. Crystal growth, vibrational, optical, thermal and theoretical studies of a nonlinear optical material: 2-Methyl 3,5-dinitrobenzoic acid

    Energy Technology Data Exchange (ETDEWEB)

    Sangeetha, K. [Department of Physics, Sri Sarada College for Women, Salem-16 (India); Guru Prasad, L. [Department of Science & Humanities, M. Kumarasamy College of Engineering, Karur (India); Mathammal, R. [Department of Physics, Sri Sarada College for Women, Salem-16 (India)

    2016-11-15

    Single crystals of 2-methyl 3,5-dinitro benzoic acid with reasonable size have been grown by slow evaporation solution growth method using ethanol as solvent. Quantum chemical calculation of 2-methyl 3,5-Dinitro benzoic acid was carried out by using DFT/B3LYP/6-31+G(d,p) method. The powder X-ray diffraction pattern was recorded and indexed. Both the experimental and theoretical vibrational spectrum validates the presence of functional groups. Polarizability, first order hyperpolarizability and the electric dipole moment values have been computed theoretically. The {sup 1}H and {sup 13}C NMR chemical shift of the molecule was calculated and compared with experimental results. TG/DSC analysis has been employed to understand the thermal and physio-chemical stability of the title compound. Frequency conversion property of the crystal was tested by Kurtz and Perry method. Optical absorption behavior of the grown crystal was examined by recording the optical spectrum and band gap energy was also estimated. The calculated HOMO and LUMO energy shows the charge transfer nature of the molecule.

  4. Modelling characteristics of photovoltaic panels with thermal phenomena taken into account

    International Nuclear Information System (INIS)

    Krac, Ewa; Górecki, Krzysztof

    2016-01-01

    In the paper a new form of the electrothermal model of photovoltaic panels is proposed. This model takes into account the optical, electrical and thermal properties of the considered panels, as well as electrical and thermal properties of the protecting circuit and thermal inertia of the considered panels. The form of this model is described and some results of measurements and calculations of mono-crystalline and poly-crystalline panels are presented

  5. Improvement and evaluation of thermal, electrical, sealing and mechanical contacts, and their interface materials

    Science.gov (United States)

    Luo, Xiangcheng

    Material contacts, including thermal, electrical, seating (fluid sealing and electromagnetic sealing) and mechanical (pressure) contacts, together with their interface materials, were, evaluated, and in some cases, improved beyond the state of the art. The evaluation involved the use of thermal, electrical and mechanical methods. For thermal contacts, this work evaluated and improved the heat transfer efficiency between two contacting components by developing various thermal interface pastes. Sodium silicate based thermal pastes (with boron nitride particles as the thermally conductive filler) as well as polyethylene glycol (PEG) based thermal pastes were developed and evaluated. The optimum volume fractions of BN in sodium silicate based pastes and PEG based pastes were 16% and 18% respectively. The contribution of Li+ ions to the thermal contact conductance in the PEG-based paste was confirmed. For electrical contacts, the relationship between the mechanical reliability and electrical reliability of solder/copper and silver-epoxy/copper joints was addressed. Mechanical pull-out testing was conducted on solder/copper and silver-epoxy/copper joints, while the contact electrical resistivity was measured. Cleansing of the copper surface was more effective for the reliability of silver-epoxy/copper joint than that of solder/copper joint. For sealing contacts, this work evaluated flexible graphite as an electromagnetic shielding gasket material. Flexible graphite was found to be at least comparable to conductive filled silicone (the state of the art) in terms of the shielding effectiveness. The conformability of flexible graphite with its mating metal surface under repeated compression was characterized by monitoring the contact electrical resistance, as the conformability is important to both electromagnetic scaling and fluid waling using flexible graphite. For mechanical contacts, this work focused on the correlation of the interface structure (such as elastic

  6. Thermal Management and Reliability of Power Electronics and Electric Machines

    Energy Technology Data Exchange (ETDEWEB)

    Narumanchi, Sreekant

    2016-06-13

    Increasing the number of electric-drive vehicles (EDVs) on America's roads has been identified as a strategy with near-term potential for dramatically decreasing the nation's dependence on oil - by the U.S. Department of Energy, the federal cross-agency EV-Everywhere Challenge, and the automotive industry. Mass-market deployment will rely on meeting aggressive technical targets, including improved efficiency and reduced size, weight, and cost. Many of these advances will depend on optimization of thermal management. Effective thermal management is critical to improving the performance and ensuring the reliability of EDVs. Efficient heat removal makes higher power densities and lower operating temperatures possible, and in turn enables cost and size reductions. The National Renewable Energy Laboratory (NREL), along with DOE and industry partners is working to develop cost-effective thermal management solutions to increase device and component power densities. In this presentation, the activities in recent years related to thermal management and reliability of automotive power electronics and electric machines are presented.

  7. Electro-thermal analysis of Lithium Iron Phosphate battery for electric vehicles

    Science.gov (United States)

    Saw, L. H.; Somasundaram, K.; Ye, Y.; Tay, A. A. O.

    2014-03-01

    Lithium ion batteries offer an attractive solution for powering electric vehicles due to their relatively high specific energy and specific power, however, the temperature of the batteries greatly affects their performance as well as cycle life. In this work, an empirical equation characterizing the battery's electrical behavior is coupled with a lumped thermal model to analyze the electrical and thermal behavior of the 18650 Lithium Iron Phosphate cell. Under constant current discharging mode, the cell temperature increases with increasing charge/discharge rates. The dynamic behavior of the battery is also analyzed under a Simplified Federal Urban Driving Schedule and it is found that heat generated from the battery during this cycle is negligible. Simulation results are validated with experimental data. The validated single cell model is then extended to study the dynamic behavior of an electric vehicle battery pack. The modeling results predict that more heat is generated on an aggressive US06 driving cycle as compared to UDDS and HWFET cycle. An extensive thermal management system is needed for the electric vehicle battery pack especially during aggressive driving conditions to ensure that the cells are maintained within the desirable operating limits and temperature uniformity is achieved between the cells.

  8. Big-Data-Based Thermal Runaway Prognosis of Battery Systems for Electric Vehicles

    Directory of Open Access Journals (Sweden)

    Jichao Hong

    2017-07-01

    Full Text Available A thermal runaway prognosis scheme for battery systems in electric vehicles is proposed based on the big data platform and entropy method. It realizes the diagnosis and prognosis of thermal runaway simultaneously, which is caused by the temperature fault through monitoring battery temperature during vehicular operations. A vast quantity of real-time voltage monitoring data is derived from the National Service and Management Center for Electric Vehicles (NSMC-EV in Beijing. Furthermore, a thermal security management strategy for thermal runaway is presented under the Z-score approach. The abnormity coefficient is introduced to present real-time precautions of temperature abnormity. The results illustrated that the proposed method can accurately forecast both the time and location of the temperature fault within battery packs. The presented method is flexible in all disorder systems and possesses widespread application potential in not only electric vehicles, but also other areas with complex abnormal fluctuating environments.

  9. PV Thermal systems: PV panels supplying renewable electricity and heat

    NARCIS (Netherlands)

    Helden, van W.G.J.; Zolingen, van R.J.C.; Zondag, H.A.

    2004-01-01

    With PV Thermal panels sunlight is converted into electricity and heat simultaneously. Per unit area the total efficiency of a PVT panel is higher than the sum of the efficiencies of separate PV panels and solar thermal collectors. During the last 20 years research into PVT techniques and concepts

  10. Structural, optical and thermal characterization of PVC/SnO2 nanocomposites

    Science.gov (United States)

    Taha, T. A.; Ismail, Z.; Elhawary, M. M.

    2018-04-01

    The structural, optical, and thermal properties of PVC/SnO2 nanocomposites were investigated. XRD patterns were used to explore the structures of these prepared samples. Optical UV-Vis measurements were analyzed to calculate the spectroscopic optical constants of the prepared PVC/SnO2 nanocomposites. Both direct and indirect optical band gaps decreased with increasing SnO2 content. The refractive index, high frequency dielectric constant, plasma frequency, and optical conductivity values increased with SnO2. The single oscillator energy increased from 5.64 to 10.97 eV and the dispersion energy increased from 6.35 to 19.80 eV with the addition of SnO2. The other optical parameters such as optical moments, single oscillator strength, volume energy loss, and surface energy loss were calculated for different SnO2 concentrations. Raman spectra of the PVC/SnO2 nanocomposite films revealed the characteristic vibrational modes of PVC and surface phonon modes of SnO2. The thermal stability of PVC/SnO2 nanocomposite films was studied using DTA and thermogravimetric analysis. The glass transition ( T g) values abruptly changed from 46 °C for PVC to an average value of 59 °C for the polymer films doped with 2.0, 4.0, and 6.0 wt% SnO2. The weight loss decreased as the SnO2 concentration increased in the temperature range of 350-500 °C, corresponding to enhanced thermal stability.

  11. Intense laser effects on nonlinear optical absorption and optical rectification in single quantum wells under applied electric and magnetic field

    International Nuclear Information System (INIS)

    Duque, C.A.; Kasapoglu, E.; Sakiroglu, S.; Sari, H.; Soekmen, I.

    2011-01-01

    In this work the effects of intense laser on the electron-related nonlinear optical absorption and nonlinear optical rectification in GaAs-Ga 1-x Al x As quantum wells are studied under, applied electric and magnetic field. The electric field is applied along the growth direction of the quantum well whereas the magnetic field has been considered to be in-plane. The calculations were performed within the density matrix formalism with the use of the effective mass and parabolic band approximations. The intense laser effects are included through the Floquet method, by modifying the confining potential associated to the heterostructure. Results are presented for the nonlinear optical absorption, the nonlinear optical rectification and the resonant peak of these two optical processes. Several configurations of the dimensions of the quantum well, the applied electric and magnetic fields, and the incident intense laser radiation have been considered. The outcome of the calculation suggests that the nonlinear optical absorption and optical rectification are non-monotonic functions of the dimensions of the heterostructure and of the external perturbations considered in this work.

  12. External electric field driving the ultra-low thermal conductivity of silicene.

    Science.gov (United States)

    Qin, Guangzhao; Qin, Zhenzhen; Yue, Sheng-Ying; Yan, Qing-Bo; Hu, Ming

    2017-06-01

    The manipulation of thermal transport is in increasing demand as heat transfer plays a critical role in a wide range of practical applications, such as efficient heat dissipation in nanoelectronics and heat conduction hindering in solid-state thermoelectrics. It is well established that the thermal transport in semiconductors and insulators (phonons) can be effectively modulated by structure engineering or materials processing. However, almost all the existing approaches involve altering the original atomic structure of materials, which would be hindered due to either irreversible structure change or limited tunability of thermal conductivity. Motivated by the inherent relationship between phonon behavior and interatomic electrostatic interaction, we comprehensively investigate the effect of external electric field, a widely used gating technique in modern electronics, on the lattice thermal conductivity (κ). Taking two-dimensional silicon (silicene) as a model, we demonstrate that by applying an electric field (E z = 0.5 V Å -1 ) the κ of silicene can be reduced to a record low value of 0.091 W m -1 K -1 , which is more than two orders of magnitude lower than that without an electric field (19.21 W m -1 K -1 ) and is even comparable to that of the best thermal insulation materials. Fundamental insights are gained from observing the electronic structures. With an electric field applied, due to the screened potential resulting from the redistributed charge density, the interactions between silicon atoms are renormalized, leading to phonon renormalization and the modulation of phonon anharmonicity through electron-phonon coupling. Our study paves the way for robustly tuning phonon transport in materials without altering the atomic structure, and would have significant impact on emerging applications, such as thermal management, nanoelectronics and thermoelectrics.

  13. Effect of 200 keV Ar+ implantation on optical & electrical properties of polyethyleneterepthalate (PET)

    Science.gov (United States)

    Kumar, Rajiv; Goyal, Meetika; Sharma, Ambika; Aggarwal, Sanjeev; Sharma, Annu; Kanjilal, D.

    2015-05-01

    In the present paper we have discussed the effect of 200 keV Ar+ ions on the electrical and optical properties of PET samples. PET samples were implanted with 200 keV Ar+ ions to various doses ranging from 1×1015 to 1×1017 Ar+ cm2. The changes in the electrical and optical properties of pristine and implanted PET specimens have been studied by using Keithley electrometer and UV-Visible absorption spectroscopy. The electrical conductivity has found to be increased with increasing ion dose. The optical studies have revealed the drastic alterations in optical band gap from 3.63 eV to 1.48 eV and also increase in number of carbon atoms per cluster from 215 to 537. Further, the change in the electrical conductivity and optical band gap has also been correlated with the formation of conductive islands in the implanted layers of PET.

  14. A new repeatable, optical writing and electrical erasing device based on photochromism and electrochromism of viologen

    International Nuclear Information System (INIS)

    Gao, Li-ping; Wei, Jian; Wang, Yue-chuan; Ding, Guo-jing; Yang, Yu-lin

    2012-01-01

    New optical writing and electrical erasing devices have been successfully fabricated that exploit the photochromism and electrochromism of viologen. In a preliminary study, both the structures of viologen and device were investigated in detail by UV–vis spectra in order to confirm their effects on the optical writing and electrical erasing performances of corresponding devices. For sandwiched, single and complementary devices based on benzyl viologen (BV 2+ ), only optical writing can be performed, not electrical erasing operations, which indicated these devices cannot realize optical information rewriting. For single and complementary devices based on styrene-functional viologen (V BV 2+ ) and acrylic-functional viologen (ACV 2+ ), optical writing and electrical erasing operations can be reversibly performed and optical information rewriting realized. It is clear that single devices based on V BV 2+ and ACV 2+ possess better performance accompanied with contrast without significant degradation and bleaching times and without significant deterioration over 10 repeated writing/erasing cycles. Furthermore, we put forward possible mechanisms for sandwiched, single and complementary devices based on V BV 2+ and ACV 2+ for the optical writing and electrical erasing operations. This study provides a new strategy to design optical writing and electrical erasing devices to realize optical information rewriting. (paper)

  15. Study of the electrical and thermal performances of photovoltaic thermal collector-compound parabolic concentrated

    Science.gov (United States)

    Jaaz, Ahed Hameed; Sopian, Kamaruzzaman; Gaaz, Tayser Sumer

    2018-06-01

    The importance of utilizing the solar energy as a very suitable source among multi-source approaches to replace the conventional energy is on the rise in the last four decades. The invention of the photovoltaic module (PV) could be the corner stone in this process. However, the limited amount of energy obtained from PV was and still the main challenge of full utilization of the solar energy. In this paper, the use of the compound parabolic concentrator (CPC) along with the thermal photovoltaic module (PVT) where the cooling process of the CPC is conducted using a novel technique of water jet impingement has applied experimentally and physically tested. The test includes the effect of water jet impingement on the total power, electrical efficiency, thermal efficiency, and total efficiency on CPC-PVT system. The cooling process at the maximum irradiation by water jet impingement resulted in improving the electrical efficiency by 7%, total output power by 31% and the thermal efficiency by 81%. These results outperform the recent highest results recorded by the most recent work.

  16. Optical and electrical characterizations of multifunctional silver phosphate glass and polymer-based optical fibers.

    Science.gov (United States)

    Rioux, Maxime; Ledemi, Yannick; Morency, Steeve; de Lima Filho, Elton Soares; Messaddeq, Younès

    2017-03-03

    In recent years, the fabrication of multifunctional fibers has expanded for multiple applications that require the transmission of both light and electricity. Fibers featuring these two properties are usually composed either of a single material that supports the different characteristics or of a combination of different materials. In this work, we fabricated (i) novel single-core step-index optical fibers made of electrically conductive AgI-AgPO 3 -WO 3 glass and (ii) novel multimaterial fibers with different designs made of AgI-AgPO 3 -WO 3 glass and optically transparent polycarbonate and poly (methyl methacrylate) polymers. The multifunctional fibers produced show light transmission over a wide range of wavelengths from 500 to 1000 nm for the single-core fibers and from 400 to 1000 nm for the multimaterial fibers. Furthermore, these fibers showed excellent electrical conductivity with values ranging between 10 -3 and 10 -1  S·cm -1 at room temperature within the range of AC frequencies from 1 Hz to 1 MHz. Multimodal taper-tipped fibre microprobes were then fabricated and were characterized. This advanced design could provide promising tools for in vivo electrophysiological experiments that require light delivery through an optical core in addition to neuronal activity recording.

  17. Electrical versus optical pumping of quantum dot amplifiers

    DEFF Research Database (Denmark)

    Berg, Tommy Winther; Bischoff, Svend; Mørk, Jesper

    2001-01-01

    The influence of the pumping mechanism for the dynamical properties of quantum dot amplifiers is investigated for 10, 40 and 160 GHz signals. A fast response is predicted in the case of optical pumping in the wetting layer (WL). The combination of fast relaxation and capture times and the presence...... of a reservoir of carriers in the WL opens up for the possibility of ultrafast gain recovery in QD devices. The strength of optical contra electrical pumping is that it reduces the bottleneck effect of a slow WL. Optical pumping thus allows significant improvement of the dynamical properties of QD devices....

  18. Optical absorption and electrical properties of MPc (M =Fe, Cu, Zn)-TCNQ interfaces for optoelectronic applications

    Science.gov (United States)

    Sánchez Vergara, M. E.; Medrano Gallardo, D.; Vera Estrada, I. L.; Jiménez Sandoval, O.

    2018-04-01

    This research is related to the growth and characterization of doped molecular semiconductor metallophthalocyanine-tetracyanoquinodimethane (MPc-TCNQ) films, with M = Fe, Zn, Cu. FT-IR and Raman spectroscopies were employed to study the chemical interactions taking place in the MPc-TCNQ films. XRD was carried out to determine the crystalline structure present in the samples, due to the facility of the MPcs to be in alpha and/or beta phases. The thin films were analized by SEM and UV-vis spectroscopy in order to study their morphological and optical properties. The absorption spectra recorded in the UV-Vis region for the deposited samples showed two bands, namely the Q and Soret bands. The absorption coefficient (α) and photon energy (hν) were calculated from the UV-vis spectra, to in turn determine the optic activation energy in each film and its semiconductor behavior. The values obtained for direct transitions due to the crystallinity of the films were: 1.2, 1.4 and 2 eV for FePc-TCNQ (MMFe), ZnPc-TCNQ (MMZn) and CuPc-TCNQ (MMCu), respectively. Additionally, I-V characteristics have been obtained from fabricated glass/ITO/MM/Ag devices using ohmic contacts both after annealing. The electrical properties of the devices, e.g. carrier mobility and concentration of thermally generated holes, were extracted from the J-V characteristics. The results show that the conduction process is ohmic for the MMZn and MMCu devices, at low voltages, while at high voltages, a space-charge-limited conduction (SCLC) is present. The effect of temperature on conductivity was also measured in these samples and the lower thermal activation energy calculated was 0.37 eV for MMZn. Moreover, it was found that the temperature-dependent electric current is always higher for the MMZn device and suggests a semiconductor-like behavior with an important conductivity of the order of 103 S cm-1. Anyhow, in terms not only of electric properties, but also of optic behavior, the results suggest that

  19. Probe branes thermalization in external electric and magnetic fields

    International Nuclear Information System (INIS)

    Ali-Akbari, M.; Ebrahim, H.; Rezaei, Z.

    2014-01-01

    We study thermalization on rotating probe branes in AdS 5 ×S 5 background in the presence of constant external electric and magnetic fields. In the AdS/CFT framework this corresponds to thermalization in the flavour sector in field theory. The horizon appears on the worldvolume of the probe brane due to its rotation in one of the sphere directions. For both electric and magnetic fields the behaviour of the temperature is independent of the probe brane dimension. We also study the open string metric and the fluctuations of the probe brane in such a set-up. We show that the temperatures obtained from open string metric and observed by the fluctuations are larger than the one calculated from the induced metric

  20. Optimization of Pockels electric field in transverse modulated optical voltage sensor

    Science.gov (United States)

    Huang, Yifan; Xu, Qifeng; Chen, Kun-Long; Zhou, Jie

    2018-05-01

    This paper investigates the possibilities of optimizing the Pockels electric field in a transverse modulated optical voltage sensor with a spherical electrode structure. The simulations show that due to the edge effect and the electric field concentrations and distortions, the electric field distributions in the crystal are non-uniform. In this case, a tiny variation in the light path leads to an integral error of more than 0.5%. Moreover, a 2D model cannot effectively represent the edge effect, so a 3D model is employed to optimize the electric field distributions. Furthermore, a new method to attach a quartz crystal to the electro-optic crystal along the electric field direction is proposed to improve the non-uniformity of the electric field. The integral error is reduced therefore from 0.5% to 0.015% and less. The proposed method is simple, practical and effective, and it has been validated by numerical simulations and experimental tests.

  1. Ultraviolet and visible BRDF data on spacecraft thermal control and optical baffle materials

    Science.gov (United States)

    Viehmann, W.; Predmore, R. E.

    1987-01-01

    Bidirectional scattering functions of numerous optical baffle materials and of spacecraft thermal control coatings and surfaces are presented. Measurements were made at 254 nm and at 633 nm. The coatings and surfaces include high-reflectance white paints, low-reflectance optical blacks, thermal control blankets, and various conversion coatings on aluminum.

  2. Laser cooling and optical detection of excitations in a LC electrical circuit

    DEFF Research Database (Denmark)

    Taylor, J. M.; Sørensen, Anders Søndberg; Marcus, Charles Masamed

    2011-01-01

    We explore a method for laser cooling and optical detection of excitations in a room temperature LC electrical circuit. Our approach uses a nanomechanical oscillator as a transducer between optical and electronic excitations. An experimentally feasible system with the oscillator capacitively...... coupled to the LC and at the same time interacting with light via an optomechanical force is shown to provide strong electromechanical coupling. Conditions for improved sensitivity and quantum limited readout of electrical signals with such an “optical loud speaker” are outlined....

  3. Electrical and optical transport properties of single layer WSe2

    Science.gov (United States)

    Tahir, M.

    2018-03-01

    The electronic properties of single layer WSe2 are distinct from the famous graphene due to strong spin orbit coupling, a huge band gap and an anisotropic lifting of the degeneracy of the valley degree of freedom under Zeeman field. In this work, band structure of the monolayer WSe2 is evaluated in the presence of spin and valley Zeeman fields to study the electrical and optical transport properties. Using Kubo formalism, an explicit expression for the electrical Hall conductivity is examined at finite temperatures. The electrical longitudinal conductivity is also evaluated. Further, the longitudinal and Hall optical conductivities are analyzed. It is observed that the contributions of the spin-up and spin-down states to the power absorption spectrum depend on the valley index. The numerical results exhibit absorption peaks as a function of photon energy, ℏ ω, in the range ∼ 1.5 -2 eV. Also, the optical response lies in the visible frequency range in contrast to the conventional two-dimensional electron gas or graphene where the response is limited to terahertz regime. This ability to isolate carriers in spin-valley coupled structures may make WSe2 a promising candidate for future spintronics, valleytronics and optical devices.

  4. An Approach for Designing Thermal Management Systems for Electric and Hybrid Vehicle Battery Packs

    International Nuclear Information System (INIS)

    Pesaran, Ahmad A.; Keyser, Matthew; Burch, Steve

    1999-01-01

    If battery packs for electric vehicles (EVs) and hybrid electric vehicles (HEVs) are to operate effectively in all climates, thermal management of the packs is essential. In this paper, we will review a systematic approach for designing and evaluating battery pack thermal management systems. A thermal management system using air as the heat transfer medium is less complicated than a system using liquid cooling/heating. Generally, for parallel HEVs, an air thermal management system is adequate, whereas for EVs and series HEVs, liquid-based systems may be required for optimum thermal performance. Further information on battery thermal management can be found on the Web site www.ctts.nrel.gov/BTM

  5. Fabrication, thermal and electrical properties of polyphenylene sulphide/copper composites

    International Nuclear Information System (INIS)

    Goyal, R.K.; Kambale, K.R.; Nene, S.S.; Selukar, B.S.; Arbuj, S.; Mulik, U.P.

    2011-01-01

    Highlights: → Polyphenylene sulphide/copper composites show a low percolation threshold, i.e., about 6 vol% Cu. → Both pre- and post- glass transition coefficient of thermal expansion (CTE) of composites decreased significantly. → The microhardness was increased by more than 50% compared to pure PPS matrix. → The electrical conductivity was increased by about eight orders of magnitude for 18 vol% Cu composite. → Dielectric constant and dissipation factor of composites measured at MHz was increased to about 6-fold and 70-fold compared to PPS matrix. - Abstract: The thermal and electrical properties of high performance poly(phenylene sulphide) (PPS) composites reinforced up to 31 vol% Cu particles were investigated to be used as materials for electronic applications. The thermal stability and char yield of the composites increased significantly. Both pre- and post- glass transition coefficient of thermal expansion (CTE) of composites decreased significantly. The microhardness was increased by more than 50% compared to pure PPS matrix. Microhardness and CTE of composites correlated well with the rule of mixtures. A percolation threshold about 6 vol% Cu was obtained. The electrical conductivity was increased by about eight orders of magnitude for 18 vol% composite. Dielectric constant and dissipation factor of composites at 1 MHz was increased by about 6-fold and 70-fold compared to matrix, respectively. They decreased gradually with increasing frequency up to 1 MHz and thereafter, there was insignificant change. The scanning electron microscope showed almost uniform distribution of Cu particles in the matrix. Owing to better dimensional stability and good electrical properties, these composites are very promising for electronic applications.

  6. Thermal noise from optical coatings in gravitational wave detectors.

    Science.gov (United States)

    Harry, Gregory M; Armandula, Helena; Black, Eric; Crooks, D R M; Cagnoli, Gianpietro; Hough, Jim; Murray, Peter; Reid, Stuart; Rowan, Sheila; Sneddon, Peter; Fejer, Martin M; Route, Roger; Penn, Steven D

    2006-03-01

    Gravitational waves are a prediction of Einstein's general theory of relativity. These waves are created by massive objects, like neutron stars or black holes, oscillating at speeds appreciable to the speed of light. The detectable effect on the Earth of these waves is extremely small, however, creating strains of the order of 10(-21). There are a number of basic physics experiments around the world designed to detect these waves by using interferometers with very long arms, up to 4 km in length. The next-generation interferometers are currently being designed, and the thermal noise in the mirrors will set the sensitivity over much of the usable bandwidth. Thermal noise arising from mechanical loss in the optical coatings put on the mirrors will be a significant source of noise. Achieving higher sensitivity through lower mechanical loss coatings, while preserving the crucial optical and thermal properties, is an area of active research right now.

  7. Long-distance thermal temporal ghost imaging over optical fibers

    Science.gov (United States)

    Yao, Xin; Zhang, Wei; Li, Hao; You, Lixing; Wang, Zhen; Huang, Yidong

    2018-02-01

    A thermal ghost imaging scheme between two distant parties is proposed and experimentally demonstrated over long-distance optical fibers. In the scheme, the weak thermal light is split into two paths. Photons in one path are spatially diffused according to their frequencies by a spatial dispersion component, then illuminate the object and record its spatial transmission information. Photons in the other path are temporally diffused by a temporal dispersion component. By the coincidence measurement between photons of two paths, the object can be imaged in a way of ghost imaging, based on the frequency correlation between photons in the two paths. In the experiment, the weak thermal light source is prepared by the spontaneous four-wave mixing in a silicon waveguide. The temporal dispersion is introduced by single mode fibers of 50 km, which also could be looked as a fiber link. Experimental results show that this scheme can be realized over long-distance optical fibers.

  8. Thermal Energy Storage for Building Load Management: Application to Electrically Heated Floor

    Directory of Open Access Journals (Sweden)

    Hélène Thieblemont

    2016-07-01

    Full Text Available In cold climates, electrical power demand for space conditioning becomes a critical issue for utility companies during certain periods of the day. Shifting a portion or all of it to off-peak periods can help reduce peak demand and reduce stress on the electrical grid. Sensible thermal energy storage (TES systems, and particularly electrically heated floors (EHF, can store thermal energy in buildings during the off-peak periods and release it during the peak periods while maintaining occupants’ thermal comfort. However, choosing the type of storage system and/or its configuration may be difficult. In this paper, the performance of an EHF for load management is studied. First, a methodology is developed to integrate EHF in TRNSYS program in order to investigate the impact of floor assembly on the EHF performance. Then, the thermal comfort (TC of the night-running EHF is studied. Finally, indicators are defined, allowing the comparison of different EHF. Results show that an EHF is able to shift 84% of building loads to the night while maintaining acceptable TC in cold climate. Moreover, this system is able to provide savings for the customer and supplier if there is a significant difference between off-peak and peak period electricity prices.

  9. PID temperature controller in pig nursery: improvements in performance, thermal comfort, and electricity use.

    Science.gov (United States)

    de Souza Granja Barros, Juliana; Rossi, Luiz Antonio; Sartor, Karina

    2016-08-01

    The use of smarter temperature control technologies in heating systems can optimize the use of electric power and performance of piglets. Two control technologies of a resistive heating system were assessed in a pig nursery: a PID (proportional, integral, and derivative) controller and a thermostat. The systems were evaluated regarding thermal environment, piglet performance, and use of electric power for 99 days. The heating system with PID controller improved the thermal environment conditions and was significantly (P PID-controlled heating system is more efficient in electricity use and provides better conditions for thermal comfort and animal performance than heating with thermostat.

  10. Electrical and Optical Enhancement in Internally Nanopatterned Organic Light-Emitting Diodes

    Science.gov (United States)

    Fina, Michael Dane

    Organic light-emitting diodes (OLEDs) have made tremendous technological progress in the past two decades and have emerged as a top competitor for next generation light-emitting displays and lighting. State-of-the-art OLEDs have been reported in literature to approach, and even surpass, white fluorescent tube efficiency. However, despite rapid technological progress, efficiency metrics must be improved to compete with traditional inorganic light-emitting diode (LED) technology. Organic materials possess specialized traits that permit manipulations to the light-emitting cavity. Overall, as demonstrated within, these modifications can be used to improve electrical and optical device efficiencies. This work is focused at analyzing the effects that nanopatterned geometric modifications to the organic active layers play on device efficiency. In general, OLED efficiency is complicated by the complex, coupled processes which contribute to spontaneous dipole emission. A composite of three sub-systems (electrical, exciton and optical) ultimately dictate the OLED device efficiency. OLED electrical operation is believed to take place via a low-mobility-modified Schottky injection process. In the injection-limited regime, geometric effects are expected to modify the local electric field leading to device current enhancement. It is shown that the patterning effect can be used to enhance charge carrier parity, thereby enhancing overall recombination. Current density and luminance characteristics are shown to be improved by OLED nanopatterning from both the model developed within and experimental techniques. Next, the optical enhancement effects produced by the nanopatterned array are considered. Finite-difference time-domain (FDTD) simulations are used to determine positional, spectral optical enhancement for the nanopatterned device. The results show beneficial effects to the device performance. The optical enhancements are related to the reduction in internal radiative

  11. Thermal Management and Reliability of Power Electronics and Electric Machines

    Energy Technology Data Exchange (ETDEWEB)

    Narumanchi, Sreekant

    2016-08-03

    Increasing the number of electric-drive vehicles (EDVs) on America's roads has been identified as a strategy with near-term potential for dramatically decreasing the nation's dependence on oil -- by the U.S. Department of Energy, the federal cross-agency EV-Everywhere Challenge, and the automotive industry. Mass-market deployment will rely on meeting aggressive technical targets, including improved efficiency and reduced size, weight, and cost. Many of these advances will depend on optimization of thermal management. Effective thermal management is critical to improving the performance and ensuring the reliability of EDVs. Efficient heat removal makes higher power densities and lower operating temperatures possible, and in turn enables cost and size reductions. The National Renewable Energy Laboratory (NREL), along with DOE and industry partners is working to develop cost-effective thermal management solutions to increase device and component power densities. In this presentation, the activities in recent years related to thermal management and reliability of automotive power electronics and electric machines will be presented.

  12. Software architecture for hybrid electrical/optical data center network

    DEFF Research Database (Denmark)

    Mehmeri, Victor; Vegas Olmos, Juan José; Tafur Monroy, Idelfonso

    2016-01-01

    This paper presents hardware and software architecture based on Software-Defined Networking (SDN) paradigm and OpenFlow/NETCONF protocols for enabling topology management of hybrid electrical/optical switching data center networks. In particular, a development on top of SDN open-source controller...... OpenDaylight is presented to control an optical switching matrix based on Micro-Electro-Mechanical System (MEMS) technology....

  13. An optical, electrical and ultrasonic layered single sensor for ingredient measurement in liquid

    International Nuclear Information System (INIS)

    Kimoto, A; Kitajima, T

    2010-01-01

    In this paper, an optical, electrical and ultrasonic layered single sensor is proposed as a new, non-invasive sensing method for the measurement of ingredients in liquid, particularly in the food industry. In the proposed sensor, the photo sensors and the PVDF films with the transparent conductive electrode are layered and the optical properties of the liquid are measured by a light emitting diode (LED) and a phototransistor (PT). In addition, the electrical properties are measured by indium tin oxide (ITO) film electrodes as the transparent conductive electrodes of PVDF films arranged on the surfaces of the LED and PT. Moreover, the ultrasonic properties are measured by PVDF films. Thus, the optical, electrical and ultrasonic properties in the same space of the liquid can be simultaneously measured at a single sensor. To test the sensor experimentally, three parameters of the liquid—such as concentrations of yellow color, sodium chloride (NaCl) and ethanol in distilled water—were estimated using the measurement values of the optical, electrical and ultrasonic properties obtained with the proposed sensor. The results suggested that it is possible to estimate the three ingredient concentrations in the same space of the liquid from the optical, electrical and ultrasonic properties measured by the proposed single sensor, although there are still some problems such as measurement accuracy that must be solved

  14. Thermoelectric System in Different Thermal and Electrical Configurations: Its Impact in the Figure of Merit

    Directory of Open Access Journals (Sweden)

    Alexander Vargas-Almeida

    2013-05-01

    Full Text Available In this work, we analyze different configurations of a thermoelectric system (TES composed of three thermoelectric generators (TEGs. We present the following considerations: (a TES thermally and electrically connected in series (SC; (b TES thermally and electrically connected in parallel (PSC; and (c parallel thermally and series electrical connection (SSC. We assume that the parameters of the TEGs are temperature-independent. The systems are characterized by three parameters, as it has been showed in recent investigations, namely, its internal electrical resistance, R, thermal conductance under open electrical circuit condition, K, and Seebeck coefficient α. We derive the equivalent parameters for each of the configurations considered here and calculate the Figure of Merit Z for the equivalent system. We show the impact of the configuration of the system on Z, and we suggest optimum configuration. In order to justify the effectiveness of the equivalent Figure of Merit, the corresponding efficiency has been calculated for each configuration.

  15. Morphology, thermal, electrical and electrochemical stability of nano

    Indian Academy of Sciences (India)

    In the present work, an attempt has been made to develop nano aluminium oxide (Al2O3)-filled polyvinyl alcohol (PVA) composite gel electrolytes. Surface morphological studies, thermal behaviour, electrochemical stability and electrical characterization of these composite gel electrolytes have been performed. An increase ...

  16. Investigation of the Promotion of Wind Power Consumption Using the Thermal-Electric Decoupling Techniques

    Directory of Open Access Journals (Sweden)

    Shuang Rong

    2015-08-01

    Full Text Available In the provinces of north China, combined heat and electric power generations (CHP are widely utilized to provide both heating source and electricity. While, due to the constraint of thermal-electric coupling within CHP, a mass of wind turbines have to offline operate during heating season to maintain the power grid stability. This paper proposes a thermal-electric decoupling (TED approach to release the energy waste. Within the thermal-electric decoupling system, heat storage and electric boiler/heat pump are introduced to provide an auxiliary thermal source during hard peak shaving period, thus relying on the participation of an outside heat source, the artificial electric power output change interval could be widened to adopt more wind power and reduce wind power curtailment. Both mathematic models and methods are proposed to calculate the evaluation indexes to weight the effect of TED, by using the Monte Carlo simulation technique. Numerical simulations have been conducted to demonstrate the effectiveness of the proposed methods, and the results show that the proposed approach could relieve up to approximately 90% of wind power curtailment and the ability of power system to accommodate wind power could be promoted about 32%; moreover, the heating source is extended, about 300 GJ heat could be supplied by TED during the whole heating season, which accounts for about 18% of the total heat need.

  17. Peripapillary retinal thermal coagulation following electrical injury

    Directory of Open Access Journals (Sweden)

    Manjari Tandon

    2013-01-01

    Full Text Available In this study, we have presented the case report of a 20 year old boy who suffered an electric injury shock, following which he showed peripapillary retinal opacification and increased retinal thickening that subsequently progressed to retinal atrophy. The fluorescein angiogram revealed normal retinal circulation, thus indicating thermal damage to retina without any compromise to retinal circulation.

  18. Third-order optical intensity correlation measurements of pseudo-thermal light

    International Nuclear Information System (INIS)

    Chen Xi-Hao; Wu Wei; Meng Shao-Ying; Li Ming-Fei

    2014-01-01

    Third-order Hanbrury Brown—Twiss and double-slit interference experiments with a pseudo-thermal light are performed by recording intensities in single, double and triple optical paths, respectively. The experimental results verifies the theoretical prediction that the indispensable condition for achieving a interference pattern or ghost image in Nth-order intensity correlation measurements is the synchronous detection of the same light field by each reference detector, no matter the intensities recorded in one, or two, or N optical paths. It is shown that, when the reference detectors are scanned in the opposite directions, the visibility and resolution of the third-order spatial correlation function of thermal light is much better than that scanned in the same direction, but it is no use for obtaining the Nth-order interference pattern or ghost image in the thermal Nth-order interference or ghost imaging. (general)

  19. Qualitative thermal characterization and cooling of lithium batteries for electric vehicles

    Science.gov (United States)

    Mariani, A.; D'Annibale, F.; Boccardi, G.; Celata, G. P.; Menale, C.; Bubbico, R.; Vellucci, F.

    2014-04-01

    The paper deals with the cooling of batteries. The first step was the thermal characterization of a single cell of the module, which consists in the detection of the thermal field by means of thermographic tests during electric charging and discharging. The purpose was to identify possible critical hot points and to evaluate the cooling demand during the normal operation of an electric car. After that, a study on the optimal configuration to obtain the flattening of the temperature profile and to avoid hot points was executed. An experimental plant for cooling capacity evaluation of the batteries, using air as cooling fluid, was realized in our laboratory in ENEA Casaccia. The plant is designed to allow testing at different flow rate and temperatures of the cooling air, useful for the assessment of operative thermal limits in different working conditions. Another experimental facility was built to evaluate the thermal behaviour changes with water as cooling fluid. Experimental tests were carried out on the LiFePO4 batteries, under different electric working conditions using the two loops. In the future, different type of batteries will be tested and the influence of various parameters on the heat transfer will be assessed for possible optimal operative solutions.

  20. Qualitative thermal characterization and cooling of lithium batteries for electric vehicles

    International Nuclear Information System (INIS)

    Mariani, A; D'Annibale, F; Boccardi, G; Celata, G P; La Sapienza (Italy))" data-affiliation=" (University of Roma La Sapienza (Italy))" >Menale, C; La Sapienza (Italy))" data-affiliation=" (University of Roma La Sapienza (Italy))" >Bubbico, R; Vellucci, F

    2014-01-01

    The paper deals with the cooling of batteries. The first step was the thermal characterization of a single cell of the module, which consists in the detection of the thermal field by means of thermographic tests during electric charging and discharging. The purpose was to identify possible critical hot points and to evaluate the cooling demand during the normal operation of an electric car. After that, a study on the optimal configuration to obtain the flattening of the temperature profile and to avoid hot points was executed. An experimental plant for cooling capacity evaluation of the batteries, using air as cooling fluid, was realized in our laboratory in ENEA Casaccia. The plant is designed to allow testing at different flow rate and temperatures of the cooling air, useful for the assessment of operative thermal limits in different working conditions. Another experimental facility was built to evaluate the thermal behaviour changes with water as cooling fluid. Experimental tests were carried out on the LiFePO4 batteries, under different electric working conditions using the two loops. In the future, different type of batteries will be tested and the influence of various parameters on the heat transfer will be assessed for possible optimal operative solutions.

  1. Optical Emissions of Sprite Streamers in Weak Electric Fields

    Science.gov (United States)

    Liu, N.; Pasko, V. P.

    2004-12-01

    Sprites commonly consist of large numbers of needle-shaped filaments of ionization [e.g., Gerken and Inan, JASTP, 65, 567, 2003] and typically initiate at altitudes 70-75 km in a form of upward and downward propagating streamers [Stanley et al., GRL, 26, 3201, 1999; Stenbaek-Nielsen et al., GRL, 27, 3829, 2000; McHarg et al., JGR, 107, 1364, 2002; Moudry et al., JASTP, 65, 509, 2003]. The strong electric fields E exceeding the conventional breakdown threshold field Ek are needed for initiation of sprite streamers from single electron avalanches and recent modeling studies indicate that streamers propagating in fields E>Ek experience strong acceleration and expansion in good agreement with the above cited observations [Liu and Pasko, JGR, 109, A04301, 2004]. The initiated streamers are capable of propagating in fields substantially lower than Ek [Allen and Ghaffar, J. Phys. D: Appl. Phys., 28, 331, 1995] and it is expected that a significant part of sprite optical output comes from regions with EEk). Additionally, the values of electric fields inside of the streamer channel are always well below Ek and since the excitation coefficients for optical emissions are very sensitive to the driving electric field magnitude most of the optical luminosity of streamers in this case arises from streamer tips, indicating that observed streamer filaments in many cases may be produced by time averaging of optical luminosity coming from localized regions around streamer tips as streamers move through an instrument's field of view. We will discuss pressure dependent differences of optical emissions at different sprite altitudes, and important similarities between observed sprite streamers and recent time resolved (van Veldhuizen et al., IEEE Trans. Plasma Sci., 30, 162, 2002; Yi and Williams, J. Phys. D. Appl. Phys., 35, 205, 2002].

  2. Electrical stimulation vs thermal effects in a complex electromagnetic environment.

    Science.gov (United States)

    Paniagua, Jesús M; Rufo, Montaña; Jiménez, Antonio; Antolín, Alicia; Sánchez, Miguel

    2009-08-01

    Studies linking exposure to low levels of radiofrequencies with adverse health effects, notwithstanding their present apparent inconsistency, have contributed to a steady improvement in the quality of evaluating that exposure. In complex electromagnetic environments, with a multitude of emissions of different frequencies acting simultaneously, knowledge of the spectral content is fundamental to evaluating human exposure to non-ionizing radiation. In the present work, we quantify the most significant spectral components in the frequency band 0.5-2200 MHz in an urban area. The measurements were made with a spectrum analyzer and monopole, biconical, and log-periodic antennas. Power density levels were calculated separately for the medium wave, short wave, and frequency modulation radio broadcasting bands, and for the television and GSM, DCS, and UMTS mobile telephony bands. The measured levels were compared with the ICNIRP reference levels for exposure to multiple frequency sources for thermal effects and electrical stimulation. The results showed the criterion limiting exposure on the basis of preventing electrical stimulation of peripheral nerves and muscles to be stricter (exposure quotient 24.7 10(-4)) than that based on thermal considerations (exposure quotient 0.16 10(-4)). The bands that contribute most to the latter are short wave, with 46.2%, and mobile telephony with 32.6% of the total exposure. In a complex electromagnetic environment, knowledge of the radiofrequency spectrum is essential in order to quantify the contribution of each type of emission to the public's exposure. It is also necessary to evaluate the electrical effects as well as the thermal effects because the criterion to limit exposure on the basis of the effect of the electrical stimulation of tissues is stricter than that based on thermal effects.

  3. Electrical stimulation vs thermal effects in a complex electromagnetic environment

    International Nuclear Information System (INIS)

    Paniagua, Jesus M.; Rufo, Montana; Jimenez, Antonio; Antolin, Alicia; Sanchez, Miguel

    2009-01-01

    Studies linking exposure to low levels of radiofrequencies with adverse health effects, notwithstanding their present apparent inconsistency, have contributed to a steady improvement in the quality of evaluating that exposure. In complex electromagnetic environments, with a multitude of emissions of different frequencies acting simultaneously, knowledge of the spectral content is fundamental to evaluating human exposure to non-ionizing radiation. In the present work, we quantify the most significant spectral components in the frequency band 0.5-2200 MHz in an urban area. The measurements were made with a spectrum analyzer and monopole, biconical, and log-periodic antennas. Power density levels were calculated separately for the medium wave, short wave, and frequency modulation radio broadcasting bands, and for the television and GSM, DCS, and UMTS mobile telephony bands. The measured levels were compared with the ICNIRP reference levels for exposure to multiple frequency sources for thermal effects and electrical stimulation. The results showed the criterion limiting exposure on the basis of preventing electrical stimulation of peripheral nerves and muscles to be stricter (exposure quotient 24.7 10 -4 ) than that based on thermal considerations (exposure quotient 0.16 10 -4 ). The bands that contribute most to the latter are short wave, with 46.2%, and mobile telephony with 32.6% of the total exposure. In a complex electromagnetic environment, knowledge of the radiofrequency spectrum is essential in order to quantify the contribution of each type of emission to the public's exposure. It is also necessary to evaluate the electrical effects as well as the thermal effects because the criterion to limit exposure on the basis of the effect of the electrical stimulation of tissues is stricter than that based on thermal effects.

  4. Optical properties of an elliptic quantum ring: Eccentricity and electric field effects

    Science.gov (United States)

    Bejan, Doina; Stan, Cristina; Niculescu, Ecaterina C.

    2018-04-01

    We have theoretically studied the electronic and optical properties of a GaAs/AlGaAs elliptic quantum ring under in-plane electric field. The effects of an eccentric internal barrier -placed along the electric field direction, chosen as x-axis- and incident light polarization are particularly taken into account. The one-electron energy spectrum and wave functions are found using the adiabatic approximation and the finite element method within the effective-mass model. We show that it is possible to repair the structural distortion by applying an appropriate in-plane electric field, and the compensation is almost complete for all electronic states under study. For both concentric and eccentric quantum ring the intraband optical properties are very sensitive to the electric field and probe laser polarization. As expected, in the systems with eccentricity distortions the energy spectrum, as well as the optical response, strongly depends on the direction of the externally applied electric field, an effect that can be used as a signature of ring eccentricity. We demonstrated the possibility of generating second harmonic response at double resonance condition for incident light polarized along the x-axis if the electric field or/and eccentric barrier break the inversion symmetry. Also, strong third harmonic signal can be generated at triple resonance condition for a specific interval of electric field values when using y-polarized light.

  5. Studies on the growth aspects, structural, thermal, dielectric and third order nonlinear optical properties of solution grown 4-methylpyridinium p-nitrophenolate single crystal

    Science.gov (United States)

    Devi, S. Reena; Kalaiyarasi, S.; Zahid, I. MD.; Kumar, R. Mohan

    2016-11-01

    An ionic organic optical crystal of 4-methylpyridinium p-nitrophenolate was grown from methanol by slow evaporation method at ambient temperature. Powder and single crystal X-ray diffraction studies revealed the crystal system and its crystalline perfection. The rocking curve recorded from HRXRD study confirmed the crystal quality. FTIR spectral analysis confirmed the functional groups present in the title compound. UV-visible spectral study revealed the optical window and band gap of grown crystal. The thermal, electrical and surface laser damage threshold properties of harvested crystal were examined by using TGA/DTA, LCR/Impedance Analyzer and Nd:YAG laser system respectively. The third order nonlinear optical property of grown crystal was elucidated by Z-scan technique.

  6. Miniaturized Integrated Platform for Electrical and Optical Monitoring of Cell Cultures

    Directory of Open Access Journals (Sweden)

    Costin Brasoveanu

    2012-08-01

    Full Text Available The following paper describes the design and functions of a miniaturized integrated platform for optical and electrical monitoring of cell cultures and the necessary steps in the fabrication and testing of a silicon microchip Micro ElectroMechanical Systems (MEMS-based technology for cell data recording, monitoring and stimulation. The silicon microchip consists of a MEMS machined device containing a shank of 240 μm width, 3 mm long and 50 μm thick and an enlarged area of 5 mm × 5 mm hosting the pads for electrical connections. Ten platinum electrodes and five sensors are placed on the shank and are connected with the external electronics through the pads. The sensors aim to monitor the pH, the temperature and the impedance of the cell culture. The electrodes are bidirectional and can be used both for electrical potential recording and stimulation of cells. The fabrication steps are presented, along with the electrical and optical characterization of the system. The target of the research is to develop a new and reconfigurable platform according to the particular applications needs, as a tool for the biologist, chemists and medical doctors working is the field of cell culture monitoring in terms of growth, maintenance conditions, reaction to electrical or chemical stimulation (drugs, toxicants, etc.. HaCaT (Immortalised Human Keratinocyte cell culture has been used for demonstration purposes in order to provide information on the platform electrical and optical functions.

  7. Electrical and optical response of a laser diode to transient ionizing radiation

    International Nuclear Information System (INIS)

    Baggio, J.; Brisset, C.; Sommer, J.L.; D'hose, C.; Lalande, P.; Leray, J.L.; Musseau, O.

    1996-01-01

    The authors have studied transient irradiation effects on the optical and electrical responses of a laser diode. The influence of dose rate, ranging from 10 9 to 10 12 rad(Si)/s, has been investigated through a complete experimental study. Dose rate vulnerability of the laser diode has been observed. Electrical and optical transient responses are determined by the dose rate, the diode structure, and its operating point

  8. Optical and electrical properties of disordered layers in GaAs crystals produced by Si+ ion implantation

    International Nuclear Information System (INIS)

    Shigetomi, S.; Matsumori, T.

    1981-01-01

    The ion dose dependence and the annealing behavior of GaAs after implantation with 200 keV 2 x 10 12 -2 x 10 16 Si + ions/cm 2 as studied by using optical absorption, reflection, photoluminescence, sheet-resistivity, Hall effect and field effect methods. The experimental results of the optical absorption and reflection indicate that, when annealed at about 400 0 C, the disordered layers produced by high-dose implantation (2 x 10 15 -2 x 10 16 ions/cm 2 ), reorder epitaxially on the underlying crystal leaving relatively little residual disorder in the near-surface. However, from the experimental results of optical reflection, 800 0 C annealing is required for perfect recrystallization. The temperature dependence of the sheet-resistivity, with annealing temperature as a parameter, indicates that, next to the variable-range hopping and phonon-assisted hopping regions, a new region is observed. Holes, thermally-activated from localized states near the Fermi level Esub(F) to the mobility edge Esub(V) near the valence band, are responsible for electrical conduction in this region. (orig.)

  9. Electrical and optical properties of highly oriented nanocrystalline vanadium pentoxide

    International Nuclear Information System (INIS)

    Bahgat, A.A.; Ibrahim, F.A.; El-Desoky, M.M.

    2005-01-01

    Highly oriented nanocrystalline hydrated vanadium pentoxide, V 2 O 5 .nH 2 O, were grown epitaxially on a glass substrate along the c-axis to form a film of 200 nm thick. The films were prepared by dissolving V 2 O 5 powder in hydrogen peroxide, H 2 O 2 , solution. X-ray diffraction, transmission electron micrograph and electron diffraction were used to identify the structure of the obtained nanocrystals. Homogenous nanocrystals of 7.0 ± 1.0 nm in size were obtained and were closed packed and are distributed evenly. Electrical conductivity and thermoelectric power were measured in the temperature range 300-480 K for the as prepared films parallel to the substrate surface; i.e. normal to the c-axis. The obtained results showed an n-type semiconducting behavior within the whole temperature range. It is also clear to see that a reversible abnormality at about 340 K is realized during the cooling electrical conductivity measurements. On the other hand, optical transmission and reflection were used to evaluate different optical parameters such as; optical band gap, nature of donor levels and different absorption bands parameters. Both the electrical and optical data are correlated and accordingly the conduction mechanism is verified. Electronic parameters such as effective mass, carriers' type and concentration and drift mobility were evaluated

  10. Optical and thermal simulation chain for LED package

    NARCIS (Netherlands)

    Tapaninen, O.; Myohanen, P.; Majanen, M.; Sitomaniemi, A.; Olkkonen, J.; Hildenbrand, V.; Gielen, A.W.J.; Mackenzie, F.V.; Barink, M.; Smilauer, V.; Patzak, B.

    2016-01-01

    This paper presents a test case for coupling two physical aspects of an LED, optical and thermal, using specific simulation models coupled through an open source platform for distributed multi-physics modelling. The glue code for coupling is written with Python programming language including

  11. Enhanced Thermo-Optical Switching of Paraffin-Wax Composite Spots under Laser Heating.

    Science.gov (United States)

    Said, Asmaa; Salah, Abeer; Fattah, Gamal Abdel

    2017-05-12

    Thermo-optical switches are of particular significance in communications networks where increasingly high switching speeds are required. Phase change materials (PCMs), in particular those based on paraffin wax, provide wealth of exciting applications with unusual thermally-induced switching properties, only limited by paraffin's rather low thermal conductivity. In this paper, the use of different carbon fillers as thermal conductivity enhancers for paraffin has been investigated, and a novel structure based on spot of paraffin wax as a thermo-optic switch is presented. Thermo-optical switching parameters are enhanced with the addition of graphite and graphene, due to the extreme thermal conductivity of the carbon fillers. Differential Scanning Calorimetry (DSC) and Scanning electron microscope (SEM) are performed on paraffin wax composites, and specific heat capacities are calculated based on DSC measurements. Thermo-optical switching based on transmission is measured as a function of the host concentration under conventional electric heating and laser heating of paraffin-carbon fillers composites. Further enhancements in thermo-optical switching parameters are studied under Nd:YAG laser heating. This novel structure can be used in future networks with huge bandwidth requirements and electric noise free remote aerial laser switching applications.

  12. Electronic and optical properties of finite carbon nanotubes in an electric field

    International Nuclear Information System (INIS)

    Chen, R B; Lee, C H; Chang, C P; Lin, M F

    2007-01-01

    The effects, caused by the geometric structure and an electric field (E), on the electronic and optical properties of quasi-zero-dimensional finite carbon nanotubes are explored by employing the tight-binding model coupled with curvature effects. Electronic properties (state energies, symmetry of electronic states, energy spacing and state degeneracy) are significantly affected by the magnitude and the direction of the electric field and the geometric structure (radius, length and chirality). The electric field, by lowering the symmetry of finite carbon nanotubes, modifies the electronic properties. Thus, the optical excitation spectra, excited by electric polarization parallel to the nanotube axis, exhibit rich delta-function-like peaks, which reveal the characteristics of the electronic properties. Therefore it follows that geometric structure and E influence the low-energy absorption spectra, i.e. the change of frequency of the first peak, the alternation of the peak height and the production of the new peaks. There are more absorption peaks when E is oriented closer to the cross-section plane. Moreover, the very complicated optical absorption spectra are characteristic for the individual chiral carbon nanotube due to its specific geometric structure. Above all, the predicted absorption spectra and the associated electronic properties could be verified by optical measurements

  13. 38.2-Gb/s Optical-Wireless Transmission in 75-110 GHz Based on Electrical OFDM with Optical Comb Expansion

    DEFF Research Database (Denmark)

    Deng, Lei; Pang, Xiaodan; Beltrán, Marta

    2012-01-01

    We demonstrate scalable optical comb- and heterodyning-based generation, optical and 1.3-m wireless transmission, and electrical heterodyne detection of multiband OFDM up to 38.2 Gb/s occupying 14.4-GHz RF bandwidth, for high-capacity optical-wireless links in 75-110 GHz....

  14. Thermal modelling of Li-ion polymer battery for electric vehicle drive cycles

    Science.gov (United States)

    Chacko, Salvio; Chung, Yongmann M.

    2012-09-01

    Time-dependent, thermal behaviour of a lithium-ion (Li-ion) polymer cell has been modelled for electric vehicle (EV) drive cycles with a view to developing an effective battery thermal management system. The fully coupled, three-dimensional transient electro-thermal model has been implemented based on a finite volume method. To support the numerical study, a high energy density Li-ion polymer pouch cell was tested in a climatic chamber for electric load cycles consisting of various charge and discharge rates, and a good agreement was found between the model predictions and the experimental data. The cell-level thermal behaviour under stressful conditions such as high power draw and high ambient temperature was predicted with the model. A significant temperature increase was observed in the stressful condition, corresponding to a repeated acceleration and deceleration, indicating that an effective battery thermal management system would be required to maintain the optimal cell performance and also to achieve a full battery lifesapn.

  15. Effect of 200 keV Ar+ implantation on optical and electrical properties of polyethyleneterepthalate (PET)

    International Nuclear Information System (INIS)

    Kumar, Rajiv; Goyal, Meetika; Sharma, Ambika; Aggarwal, Sanjeev; Sharma, Annu; Kanjilal, D.

    2015-01-01

    In the present paper we have discussed the effect of 200 keV Ar + ions on the electrical and optical properties of PET samples. PET samples were implanted with 200 keV Ar + ions to various doses ranging from 1×10 15 to 1×10 17 Ar + cm 2 . The changes in the electrical and optical properties of pristine and implanted PET specimens have been studied by using Keithley electrometer and UV-Visible absorption spectroscopy. The electrical conductivity has found to be increased with increasing ion dose. The optical studies have revealed the drastic alterations in optical band gap from 3.63 eV to 1.48 eV and also increase in number of carbon atoms per cluster from 215 to 537. Further, the change in the electrical conductivity and optical band gap has also been correlated with the formation of conductive islands in the implanted layers of PET

  16. Generalized 1D photopyroelectric technique for optical and thermal characterization of liquids

    International Nuclear Information System (INIS)

    Balderas-López, J A

    2012-01-01

    The analytical solution for the one-dimensional heat diffusion problem for a three-layer system, in the Beer–Lambert model for light absorption, is used for the implementation of a photopyroelectric (PPE) methodology for thermal and optical characterization of pigments in liquid solution, even for those ones potentially harmful to the pyroelectric sensor, taking the liquid sample's thickness as the only variable. Exponential decay of the PPE amplitude followed by a constant PPE phase for solutions at low pigment concentration, and exponential decay of the PPE amplitude but a linear decrease of the PPE phase for the concentrated ones are theoretically shown, allowing measurements of the optical absorption coefficient (at the wavelength used for the analysis) and the thermal diffusivity for the liquid sample, respectively. This PPE methodology was tested by measuring the thermal diffusivity of a concentrated solution of methylene blue in distilled water and the optical absorption coefficient, at two wavelengths (658 and 785 nm), of water solutions of copper sulfate at various concentrations. These optical parameters were used for measuring the molar absorption coefficient of this last pigment in water solution at these two wavelengths. This last optical property was also measured using a commercial spectrometer, finding very good agreement with the corresponding ones using this PPE technique. (paper)

  17. Evaluation of Electrical and Thermal Conductivity of Polymeric ...

    African Journals Online (AJOL)

    PROF HORSFALL

    ABSTRACT: This work being gingered by the big menace being posed on our environment by polymeric waste and it's rechanneling involved the studying of the electrical and thermal conductivities of the polymers PP, PE, PS and nylon66 doped with charcoal and graphite. Five grams of each polymer was mixed with ...

  18. Computer modeling of electrical and thermal performance during bipolar pulsed radiofrequency for pain relief

    International Nuclear Information System (INIS)

    Pérez, Juan J.; Pérez-Cajaraville, Juan J.; Muñoz, Víctor; Berjano, Enrique

    2014-01-01

    Purpose: Pulsed RF (PRF) is a nonablative technique for treating neuropathic pain. Bipolar PRF application is currently aimed at creating a “strip lesion” to connect the electrode tips; however, the electrical and thermal performance during bipolar PRF is currently unknown. The objective of this paper was to study the temperature and electric field distributions during bipolar PRF. Methods: The authors developed computer models to study temperature and electric field distributions during bipolar PRF and to assess the possible ablative thermal effect caused by the accumulated temperature spikes, along with any possible electroporation effects caused by the electrical field. The authors also modeled the bipolar ablative mode, known as bipolar Continuous Radiofrequency (CRF), in order to compare both techniques. Results: There were important differences between CRF and PRF in terms of electrical and thermal performance. In bipolar CRF: (1) the initial temperature of the tissue impacts on temperature progress and hence on the thermal lesion dimension; and (2) at 37 °C, 6-min of bipolar CRF creates a strip thermal lesion between the electrodes when these are separated by a distance of up to 20 mm. In bipolar PRF: (1) an interelectrode distance shorter than 5 mm produces thermal damage (i.e., ablative effect) in the intervening tissue after 6 min of bipolar RF; and (2) the possible electroporation effect (electric fields higher than 150 kV m −1 ) would be exclusively circumscribed to a very small zone of tissue around the electrode tip. Conclusions: The results suggest that (1) the clinical parameters considered to be suitable for bipolar CRF should not necessarily be considered valid for bipolar PRF, and vice versa; and (2) the ablative effect of the CRF mode is mainly due to its much greater level of delivered energy than is the case in PRF, and therefore at same applied energy levels, CRF, and PRF are expected to result in same outcomes in terms of thermal

  19. Computer modeling of electrical and thermal performance during bipolar pulsed radiofrequency for pain relief

    Energy Technology Data Exchange (ETDEWEB)

    Pérez, Juan J. [Instituto de Investigación Interuniversitario en Bioingeniería y Tecnología Orientada al Ser Humano, Universitat Politècnica de València, Valencia 46022 (Spain); Pérez-Cajaraville, Juan J. [Pain Unit and Department of Anesthesia and Critical Care, Clínica Universidad de Navarra, University of Navarra, Pamplona 31008 (Spain); Muñoz, Víctor [Neurotherm Spain, Barcelona 08303 (Spain); Berjano, Enrique, E-mail: eberjano@eln.upv.es [Biomedical Synergy, Electronic Engineering Department, Universitat Politècnica de València 46022 (Spain)

    2014-07-15

    Purpose: Pulsed RF (PRF) is a nonablative technique for treating neuropathic pain. Bipolar PRF application is currently aimed at creating a “strip lesion” to connect the electrode tips; however, the electrical and thermal performance during bipolar PRF is currently unknown. The objective of this paper was to study the temperature and electric field distributions during bipolar PRF. Methods: The authors developed computer models to study temperature and electric field distributions during bipolar PRF and to assess the possible ablative thermal effect caused by the accumulated temperature spikes, along with any possible electroporation effects caused by the electrical field. The authors also modeled the bipolar ablative mode, known as bipolar Continuous Radiofrequency (CRF), in order to compare both techniques. Results: There were important differences between CRF and PRF in terms of electrical and thermal performance. In bipolar CRF: (1) the initial temperature of the tissue impacts on temperature progress and hence on the thermal lesion dimension; and (2) at 37 °C, 6-min of bipolar CRF creates a strip thermal lesion between the electrodes when these are separated by a distance of up to 20 mm. In bipolar PRF: (1) an interelectrode distance shorter than 5 mm produces thermal damage (i.e., ablative effect) in the intervening tissue after 6 min of bipolar RF; and (2) the possible electroporation effect (electric fields higher than 150 kV m{sup −1}) would be exclusively circumscribed to a very small zone of tissue around the electrode tip. Conclusions: The results suggest that (1) the clinical parameters considered to be suitable for bipolar CRF should not necessarily be considered valid for bipolar PRF, and vice versa; and (2) the ablative effect of the CRF mode is mainly due to its much greater level of delivered energy than is the case in PRF, and therefore at same applied energy levels, CRF, and PRF are expected to result in same outcomes in terms of

  20. Computer modeling of electrical and thermal performance during bipolar pulsed radiofrequency for pain relief.

    Science.gov (United States)

    Pérez, Juan J; Pérez-Cajaraville, Juan J; Muñoz, Víctor; Berjano, Enrique

    2014-07-01

    Pulsed RF (PRF) is a nonablative technique for treating neuropathic pain. Bipolar PRF application is currently aimed at creating a "strip lesion" to connect the electrode tips; however, the electrical and thermal performance during bipolar PRF is currently unknown. The objective of this paper was to study the temperature and electric field distributions during bipolar PRF. The authors developed computer models to study temperature and electric field distributions during bipolar PRF and to assess the possible ablative thermal effect caused by the accumulated temperature spikes, along with any possible electroporation effects caused by the electrical field. The authors also modeled the bipolar ablative mode, known as bipolar Continuous Radiofrequency (CRF), in order to compare both techniques. There were important differences between CRF and PRF in terms of electrical and thermal performance. In bipolar CRF: (1) the initial temperature of the tissue impacts on temperature progress and hence on the thermal lesion dimension; and (2) at 37 °C, 6-min of bipolar CRF creates a strip thermal lesion between the electrodes when these are separated by a distance of up to 20 mm. In bipolar PRF: (1) an interelectrode distance shorter than 5 mm produces thermal damage (i.e., ablative effect) in the intervening tissue after 6 min of bipolar RF; and (2) the possible electroporation effect (electric fields higher than 150 kV m(-1)) would be exclusively circumscribed to a very small zone of tissue around the electrode tip. The results suggest that (1) the clinical parameters considered to be suitable for bipolar CRF should not necessarily be considered valid for bipolar PRF, and vice versa; and (2) the ablative effect of the CRF mode is mainly due to its much greater level of delivered energy than is the case in PRF, and therefore at same applied energy levels, CRF, and PRF are expected to result in same outcomes in terms of thermal damage zone dimension.

  1. Novel polymer composite having diamond particles and boron nitride platelets for thermal management of electric vehicle motors

    Science.gov (United States)

    Nakajima, Anri; Shoji, Atsushi; Yonemori, Kei; Seo, Nobuhide

    2016-02-01

    Thermal conductivities of silicone matrix polymers including fillers of diamond particles and/or hexagonal boron nitride (h-BN) platelets were systematically investigated in an attempt to find a thermal interface material (TIM) having high isotropic thermal conductivity and high electrical insulating ability to enable efficient heat dissipation from the motor coil ends of electric vehicles. The TIM with mixed fillers of diamond particles and h-BN platelets had a maximum thermal conductivity of 6.1 W m-1 K-1 that was almost isotropic. This is the highest value among the thermal conductivities of TIMs with silicone matrix polymer reported to date. The mechanism behind the thermal conductivity of the TIMs was also examined from the viewpoint of the change in the number of thermally conductive networks and/or a decrease in the thermal resistivity of junctions of neighboring diamond particles through the incorporation of h-BN platelets. The TIMs developed in this study will make it possible to manage the heat of electric motors and will help to popularize electric vehicles.

  2. Monitoring of interaction of low-frequency electric field with biological tissues upon optical clearing with optical coherence tomography.

    Science.gov (United States)

    Peña, Adrián F; Doronin, Alexander; Tuchin, Valery V; Meglinski, Igor

    2014-08-01

    The influence of a low-frequency electric field applied to soft biological tissues ex vivo at normal conditions and upon the topical application of optical clearing agents has been studied by optical coherence tomography (OCT). The electro-kinetic response of tissues has been observed and quantitatively evaluated by the double correlation OCT approach, utilizing consistent application of an adaptive Wiener filtering and Fourier domain correlation algorithm. The results show that fluctuations, induced by the electric field within the biological tissues are exponentially increased in time. We demonstrate that in comparison to impedance measurements and the mapping of the temperature profile at the surface of the tissue samples, the double correlation OCT approach is much more sensitive to the changes associated with the tissues' electro-kinetic response. We also found that topical application of the optical clearing agent reduces the tissues' electro-kinetic response and is cooling the tissue, thus reducing the temperature induced by the electric current by a few degrees. We anticipate that dcOCT approach can find a new application in bioelectrical impedance analysis and monitoring of the electric properties of biological tissues, including the resistivity of high water content tissues and its variations.

  3. Athermal silicon optical add-drop multiplexers based on thermo-optic coefficient tuning of sol-gel material.

    Science.gov (United States)

    Namnabat, Soha; Kim, Kyung-Jo; Jones, Adam; Himmelhuber, Roland; DeRose, Christopher T; Trotter, Douglas C; Starbuck, Andrew L; Pomerene, Andrew; Lentine, Anthony L; Norwood, Robert A

    2017-09-04

    Silicon photonics has gained interest for its potential to provide higher efficiency, bandwidth and reduced power consumption compared to electrical interconnects in datacenters and high performance computing environments. However, it is well known that silicon photonic devices suffer from temperature fluctuations due to silicon's high thermo-optic coefficient and therefore, temperature control in many applications is required. Here we present an athermal optical add-drop multiplexer fabricated from ring resonators. We used a sol-gel inorganic-organic hybrid material as an alternative to previously used materials such as polymers and titanium dioxide. In this work we studied the thermal curing parameters of the sol-gel and their effect on thermal wavelength shift of the rings. With this method, we were able to demonstrate a thermal shift down to -6.8 pm/°C for transverse electric (TE) polarization in ring resonators with waveguide widths of 325 nm when the sol-gel was cured at 130°C for 10.5 hours. We also achieved thermal shifts below 1 pm/°C for transverse magnetic (TM) polarization in the C band under different curing conditions. Curing time compared to curing temperature shows to be the most important factor to control sol-gel's thermo-optic value in order to obtain an athermal device in a wide temperature range.

  4. Effect of electrical pulse treatment on the thermal fatigue resistance of bionic compacted graphite cast iron processed in water

    International Nuclear Information System (INIS)

    Liu, Yan; Zhou, Hong; Su, Hang; Yang, Chunyan; Cheng, Jingyan; Zhang, Peng; Ren, Luquan

    2012-01-01

    Highlights: ► Electrical pulse treatment can reduce cracks on bionic units before thermal fatigue tests. ► Electrical pulse treatment can reduce crack sources during thermal fatigue tests. ► Thermal fatigue resistance of bionic units processed in water is enhanced. ► Thermal fatigue resistance of bionic CGI processed in water is improved. -- Abstract: In order to further enhance the thermal fatigue resistance of bionic compacted graphite cast iron (CGI) which is processed by laser in water, the electrical pulse treatment is applied to improve the thermal fatigue resistance of bionic units. The results show that the electrical pulse treatment causes the supersaturated carbon atoms located in the lattice of austenite to react with the iron atoms to form the Fe 3 C. The microstructures of the bionic units processed in water are refined by the electrical pulse treatment. The cracks on the bionic units are reduced by the electrical pulse treatment before the thermal fatigue tests; and during the tests, the thermal fatigue resistance of bionic units is therefore enhanced by reducing the crack sources. By this way, the thermal fatigue resistance of bionic CGI processed in water is improved.

  5. Enhanced thermoelectric efficiency via orthogonal electrical and thermal conductances in phosphorene.

    Science.gov (United States)

    Fei, Ruixiang; Faghaninia, Alireza; Soklaski, Ryan; Yan, Jia-An; Lo, Cynthia; Yang, Li

    2014-11-12

    Thermoelectric devices that utilize the Seebeck effect convert heat flow into electrical energy and are highly desirable for the development of portable, solid state, passively powered electronic systems. The conversion efficiencies of such devices are quantified by the dimensionless thermoelectric figure of merit (ZT), which is proportional to the ratio of a device's electrical conductance to its thermal conductance. In this paper, a recently fabricated two-dimensional (2D) semiconductor called phosphorene (monolayer black phosphorus) is assessed for its thermoelectric capabilities. First-principles and model calculations reveal not only that phosphorene possesses a spatially anisotropic electrical conductance, but that its lattice thermal conductance exhibits a pronounced spatial-anisotropy as well. The prominent electrical and thermal conducting directions are orthogonal to one another, enhancing the ratio of these conductances. As a result, ZT may reach the criterion for commercial deployment along the armchair direction of phosphorene at T = 500 K and is close to 1 even at room temperature given moderate doping (∼2 × 10(16) m(-2) or 2 × 10(12) cm(-2)). Ultimately, phosphorene hopefully stands out as an environmentally sound thermoelectric material with unprecedented qualities. Intrinsically, it is a mechanically flexible material that converts heat energy with high efficiency at low temperatures (∼300 K), one whose performance does not require any sophisticated engineering techniques.

  6. Ocean thermal gradient as a generator of electricity. OTEC power plant

    Science.gov (United States)

    Enrique, Luna-Gomez Victor; Angel, Alatorre-Mendieta Miguel

    2016-04-01

    The OTEC (Ocean Thermal Energy Conversion) is a power plant that uses the thermal gradient of the sea water between the surface and a depth of about 700 meters. It works by supplying the heat to a steam machine, for evaporation, with sea water from the surface and cold, to condense the steam, with deep sea water. The energy generated by the power plant OTEC can be transferred to the electric power grid, another use is to desalinate seawater. During the twentieth century in some countries experimental power plants to produce electricity or obtaining drinking water they were installed. On the Mexico's coast itself this thermal gradient, as it is located in tropical seas it occurs, so it has possibilities of installing OTEC power plant type. In this paper one type OTEC power plant operation is represented in most of its components.

  7. Electrical and thermal conductivity of low temperature CVD graphene: the effect of disorder

    International Nuclear Information System (INIS)

    Vlassiouk, Ivan; Datskos, Panos; Smirnov, Sergei; Ivanov, Ilia; Hensley, Dale; Lavrik, Nickolay V; Fulvio, Pasquale F; Dai Sheng; Meyer, Harry; Chi Miaofang

    2011-01-01

    In this paper we present a study of graphene produced by chemical vapor deposition (CVD) under different conditions with the main emphasis on correlating the thermal and electrical properties with the degree of disorder. Graphene grown by CVD on Cu and Ni catalysts demonstrates the increasing extent of disorder at low deposition temperatures as revealed by the Raman peak ratio, I G /I D . We relate this ratio to the characteristic domain size, L a , and investigate the electrical and thermal conductivity of graphene as a function of L a . The electrical resistivity, ρ, measured on graphene samples transferred onto SiO 2 /Si substrates shows linear correlation with L a -1 . The thermal conductivity, K, measured on the same graphene samples suspended on silicon pillars, on the other hand, appears to have a much weaker dependence on L a , close to K ∼ L a 1/3 . It results in an apparent ρ ∼ K 3 correlation between them. Despite the progressively increasing structural disorder in graphene grown at lower temperatures, it shows remarkably high thermal conductivity (10 2 -10 3 W K -1 m -1 ) and low electrical (10 3 -3 x 10 5 Ω) resistivities suitable for various applications.

  8. Thermoelectric properties of V{sub 2}O{sub 5} thin films deposited by thermal evaporation

    Energy Technology Data Exchange (ETDEWEB)

    Santos, R.; Loureiro, J., E-mail: joa.loureiro@gmail.com; Nogueira, A.; Elangovan, E.; Pinto, J.V.; Veiga, J.P.; Busani, T.; Fortunato, E.; Martins, R.; Ferreira, I., E-mail: imf@fct.unl.pt

    2013-10-01

    This work reports the structural, optical, electrical and thermoelectric properties of vanadium pentoxide (V{sub 2}O{sub 5}) thin films deposited at room temperature by thermal evaporation on Corning glass substrates. A post-deposition thermal treatment up to 973 K under atmospheric conditions induces the crystallization of the as-deposited amorphous films with an orthorhombic V{sub 2}O{sub 5} phase with grain sizes around 26 nm. As the annealing temperature rises up to 773 K the electrical conductivity increases. The films exhibit thermoelectric properties with a maximum Seebeck coefficient of −218 μV/K and electrical conductivity of 5.5 (Ω m){sup −1}. All the films show NIR-Vis optical transmittance above 60% and optical band gap of 2.8 eV.

  9. Smart window using a thermally and optically switchable liquid crystal cell

    Science.gov (United States)

    Oh, Seung-Won; Kim, Sang-Hyeok; Baek, Jong-Min; Yoon, Tae-Hoon

    2018-02-01

    Light shutter technologies that can control optical transparency have been studied extensively for developing curtain-free smart windows. We introduce thermally and optically switchable light shutters using LCs doped with push-pull azobenzene, which is known to speed up thermal relaxation. The liquid crystal light shutter can be switched between translucent and transparent states or transparent and opaque states by phase transition through changing temperature or photo-isomerization of doped azobenzene. The liquid crystal light shutter can be used for privacy windows with an initial translucent state or energy-saving windows with an initial transparent state.

  10. Compositional dependence thermal and optical properties of a novel germanate glass

    International Nuclear Information System (INIS)

    El-Rabaie, S.; Taha, T.A.; Higazy, A.A.

    2014-01-01

    A series of zinc lithium germanate glasses of the composition (45−x)Li 2 O–xZnO–55GeO 2 have been synthesized via melt quenching technique. Dependencies of their thermal and optical properties on composition were investigated. It is found that the gradual replacement of Li 2 O by ZnO, decreases the glass transition temperature from 430 to 280 °C and increases the thermal stability (ΔT) of the studied glasses. The optical band gap E opt also decreases from 2.31 to 1.40 eV with increasing the mole content of ZnO

  11. Thermal limiting effects in optical plasmonic waveguides

    International Nuclear Information System (INIS)

    Ershov, A.E.; Gerasimov, V.S.; Gavrilyuk, A.P.; Karpov, S.V.; Zakomirnyi, V.I.; Rasskazov, I.L.; Polyutov, S.P.

    2017-01-01

    We have studied thermal effects occurring during excitation of optical plasmonic waveguide (OPW) in the form of linear chain of spherical Ag nanoparticles by pulsed laser radiation. It was shown that heating and subsequent melting of the first irradiated particle in a chain can significantly deteriorate the transmission efficiency of OPW that is the crucial and limiting factor and continuous operation of OPW requires cooling devices. This effect is caused by suppression of particle's surface plasmon resonance due to reaching the melting point temperature. We have determined optimal excitation parameters which do not significantly affect the transmission efficiency of OPW. - Highlights: • The thermodynamic model was developed to study thermal effects at nanoscale. • Developed model considers temperature-dependent permittivity of the nanoparticles. • Thermal effects significantly suppress transmission efficiency of plasmonic chains. • Optimal parameters for stable operation of plasmonic chains were defined.

  12. Detection of thermal gradients through fiber-optic Chirped Fiber Bragg Grating (CFBG): Medical thermal ablation scenario

    Science.gov (United States)

    Korganbayev, Sanzhar; Orazayev, Yerzhan; Sovetov, Sultan; Bazyl, Ali; Schena, Emiliano; Massaroni, Carlo; Gassino, Riccardo; Vallan, Alberto; Perrone, Guido; Saccomandi, Paola; Arturo Caponero, Michele; Palumbo, Giovanna; Campopiano, Stefania; Iadicicco, Agostino; Tosi, Daniele

    2018-03-01

    In this paper, we describe a novel method for spatially distributed temperature measurement with Chirped Fiber Bragg Grating (CFBG) fiber-optic sensors. The proposed method determines the thermal profile in the CFBG region from demodulation of the CFBG optical spectrum. The method is based on an iterative optimization that aims at minimizing the mismatch between the measured CFBG spectrum and a CFBG model based on coupled-mode theory (CMT), perturbed by a temperature gradient. In the demodulation part, we simulate different temperature distribution patterns with Monte-Carlo approach on simulated CFBG spectra. Afterwards, we obtain cost function that minimizes difference between measured and simulated spectra, and results in final temperature profile. Experiments and simulations have been carried out first with a linear gradient, demonstrating a correct operation (error 2.9 °C); then, a setup has been arranged to measure the temperature pattern on a 5-cm long section exposed to medical laser thermal ablation. Overall, the proposed method can operate as a real-time detection technique for thermal gradients over 1.5-5 cm regions, and turns as a key asset for the estimation of thermal gradients at the micro-scale in biomedical applications.

  13. Tunable electronic, electrical and optical properties of graphene oxide sheets by ion irradiation

    Science.gov (United States)

    Jayalakshmi, G.; Saravanan, K.; Panigrahi, B. K.; Sundaravel, B.; Gupta, Mukul

    2018-05-01

    The tunable electronic, electrical and optical properties of graphene oxide (GO) sheets were investigated using a controlled reduction by 500 keV Ar+-ion irradiation. The carbon to oxygen ratio of the GO sheets upon the ion beam reduction has been estimated using resonant Rutherford backscattering spectrometry analyses and its effect on the electrical and optical properties of GO sheets has been studied using sheet resistance measurements and photoluminescence (PL) measurements. The restoration of sp 2-hybridized carbon atoms within the sp 3 matrix is found to be increases with increasing the Ar+-ion fluences as evident from Fourier transform infrared, and x-ray absorption near-edge structure measurements. The decrease in the number of disorder-induced local density of states (LDOSs) within the π-π* gap upon the reduction causes the shifting of PL emission from near infra-red to blue region and decreases the sheet resistance. The improved electrical and optical properties of GO sheets were correlated to the decrease in the number of LDOSs within the π-π* gap. Our experimental investigations suggest ion beam irradiation is one of an effective approaches to reduce GO to RGO and to tailor its electronic, electrical and optical properties.

  14. Synthesis, growth, structural, optical, thermal, electrical and mechanical properties of hydrogen bonded organic salt crystal: Triethylammonium-3, 5-dinitrosalicylate

    Science.gov (United States)

    Rajkumar, Madhu; Chandramohan, Angannan

    2017-04-01

    Triethylammonium-3, 5-dinitrosalicylate, an organic salt was synthesized and single crystals grown by slow solvent evaporation solution growth technique using methanol as a solvent. The presence of various functional groups and mode of vibrations has been confirmed by FT-IR spectroscopic technique. The UV-vis-NIR Spectrum was recorded in the range 200-1200 nm to find optical transmittance window and lower cut off wavelength of the title crystal. The formation of the salt and the molecular structure was confirmed by NMR spectroscopic technique. Crystal system, crystalline nature, cell parameters and hydrogen bonding interactions of the grown crystal were determined by single crystal x-ray diffraction analysis. The thermal characteristics of grown crystal were analyzed by thermo gravimetric and differential thermal analyses. Dielectric studies were carried out to study the distribution of charges within the crystal. The mechanical properties of the title crystal were studied by Vicker's microhardness technique.

  15. Electrically and Thermally Insulated Joint for Liquid Nitrogen Transfer

    DEFF Research Database (Denmark)

    Rasmussen, Carsten; Jensen, Kim Høj; Holbøll, Joachim T.

    1999-01-01

    A prototype of a superconducting cable is currently under construction. The cable conductor is cooled by liquid nitrogen in order to obtain superconductivity. The peripheral cooling circuit is kept at ground potential. This requires a joint which insulates both electrically and thermally...

  16. Superconducting Electric Boost Pump for Nuclear Thermal Propulsion, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — A submersible, superconducting electric boost pump sized to meet the needs of future Nuclear Thermal Propulsion systems in the 25,000 lbf thrust range is proposed....

  17. Electrical transport in crystalline phase change materials

    International Nuclear Information System (INIS)

    Woda, Michael

    2012-01-01

    In this thesis, the electrical transport properties of crystalline phase change materials are discussed. Phase change materials (PCM) are a special class of semiconducting and metallic thin film alloys, typically with a high amount of the group five element antimony or the group six element tellurium, such as Ge 2 Sb 2 Te 5 . The unique property portfolio of this material class makes it suitable for memory applications. PCMs reveal fast switching between two stable room-temperature phases (amorphous and crystalline) realized by optical laser or electrical current pulses in memory devices. Additionally, a pronounced property contrast in form of optical reflectivity and electrical conductivity between the amorphous and crystalline phase is the characteristic fingerprint of PCMs. The emerging electrical solid state memory PCRAM is a very promising candidate to replace Flash memory in the near future or to even become a universal memory, which is non-volatile and shows the speed and cyclability of DRAM. One of the main technological challenges is the switching process into the amorphous state, which is the most power demanding step. In order to reduce the switching power, the crystalline resistivity needs to be increased at a given voltage. Thus understanding and tayloring of this property is mandatory. In this work, first the technological relevance, i.e. optical and electrical memory concepts based on PCMs are introduced. Subsequently a description of the physical properties of PCMs in four categories is given. Namely, structure, kinetics, optical properties and electrical properties are discussed. Then important recent developments such as the identification of resonant bonding in crystalline PCMs and a property predicting coordination scheme are briefly reviewed. The following chapter deals with the theoretical background of electrical transport, while the next chapter introduces the experimental techniques: Sputtering, XRR, XRD, DSC, thermal annealing

  18. Thermal and electrical energy management in a PEMFC stack - An analytical approach

    Energy Technology Data Exchange (ETDEWEB)

    Pandiyan, S.; Jayakumar, K.; Rajalakshmi, N.; Dhathathreyan, K.S. [Centre for Fuel Cell Technology, ARC International (ARCI), 120, Mambakkam Main Road, Medavakkam, Chennai 601 302 (India)

    2008-02-15

    An analytical method has been developed to differentiate the electrical and thermal resistance of the PEM fuel cell assembly in the fuel cell operating conditions. The usefulness of this method lies in the determination of the electrical resistance based on the polarization curve and the thermal resistance from the mass balance. This method also paves way for the evaluation of cogeneration from a PEMFC power plant. Based on this approach, the increase in current and resistance due to unit change in temperature at a particular current density has been evaluated. It was observed that the internal resistance of the cell is dependent on the electrode fabrication process, which also play a major role in the thermal management of the fuel cell stack. (author)

  19. Integrated Electrical and Thermal Grid Facility - Testing of Future Microgrid Technologies

    Directory of Open Access Journals (Sweden)

    Sundar Raj Thangavelu

    2015-09-01

    Full Text Available This paper describes the Experimental Power Grid Centre (EPGC microgrid test facility, which was developed to enable research, development and testing for a wide range of distributed generation and microgrid technologies. The EPGC microgrid facility comprises a integrated electrical and thermal grid with a flexible and configurable architecture, and includes various distributed energy resources and emulators, such as generators, renewable, energy storage technologies and programmable load banks. The integrated thermal grid provides an opportunity to harness waste heat produced by the generators for combined heat, power and cooling applications, and support research in optimization of combined electrical-thermal systems. Several case studies are presented to demonstrate the testing of different control and operation strategies for storage systems in grid-connected and islanded microgrids. One of the case studies also demonstrates an integrated thermal grid to convert waste heat to useful energy, which thus far resulted in a higher combined energy efficiency. Experiment results confirm that the facility enables testing and evaluation of grid technologies and practical problems that may not be apparent in a computer simulated environment.

  20. Thermal lens and all optical switching of new organometallic compound doped polyacrylamide gel

    Science.gov (United States)

    Badran, Hussain Ali

    In this work thermal lens spectrometry (TLS) is applied to investigate the thermo-optical properties of new organometallic compound containing azomethine group, Dichloro bis [2-(2-hydroxybenzylideneamino)-5-methylphenyl] telluride platinum(II), doped polyacrylamide gel using transistor-transistor logic (TTL) modulated cw 532 nm laser beam as an excitation beam modulated at 10 Hz frequency and probe beam wavelength 635 nm at 14 mW. The technique is applied to determine the thermal diffusivities, ds/dT and the linear thermal expansion coefficient of the sample. All-optical switching effects with low background and high stability are demonstrated.

  1. Metamorphosis of strain/stress on optical band gap energy of ZAO thin films via manipulation of thermal annealing process

    International Nuclear Information System (INIS)

    Malek, M.F.; Mamat, M.H.; Musa, M.Z.; Soga, T.; Rahman, S.A.; Alrokayan, Salman A.H.; Khan, Haseeb A.; Rusop, M.

    2015-01-01

    We report on the growth of Al-doped ZnO (ZAO) thin films prepared by the sol–gel technique associated with dip-coating onto Corning 7740 glass substrates. The influence of varying thermal annealing (T a ) temperature on crystallisation behaviour, optical and electrical properties of ZAO films has been systematically investigated. All films are polycrystalline with a hexagonal wurtzite structure with a preferential orientation according to the direction 〈0 0 2〉. The metamorphosis of strain/stress effects in ZAO thin films has been investigated using X-ray diffraction. The as growth films have a large compressive stress of 0.55 GPa, which relaxed to 0.25 GPa as the T a was increased to 500 °C. Optical parameters such as optical transmittance, absorption coefficient, refractive index and optical band gap energy have been studied and discussed with respect to T a . All films exhibit a transmittance above 80–90% along the visible–NIR range up to 1500 nm and a sharp absorption onset below 400 nm corresponding to the fundamental absorption edge of ZnO. Experimental results show that the tensile stress in the films reveals an incline pattern with the optical band gap energy, while the compressive stress shows opposite relation. - Highlights: • Minimum stress of highly c-axis oriented ZAO was grown at suitable T a temperature. • The ZAO crystal orientation was influenced by strain/stress of the film. • Minimum stress/strain of ZAO film leads to lower defects. • Bandgap and defects were closely intertwined with strain/stress. • We report additional optical and electrical properties based on T a temperature

  2. Metamorphosis of strain/stress on optical band gap energy of ZAO thin films via manipulation of thermal annealing process

    Energy Technology Data Exchange (ETDEWEB)

    Malek, M.F., E-mail: firz_solarzelle@yahoo.com [NANO-ElecTronic Centre (NET), Faculty of Electrical Engineering, Universiti Teknologi MARA (UiTM), 40450 Shah Alam, Selangor (Malaysia); NANO-SciTech Centre (NST), Institute of Science (IOS), Universiti Teknologi MARA UiTM, 40450 Shah Alam, Selangor (Malaysia); Mamat, M.H. [NANO-ElecTronic Centre (NET), Faculty of Electrical Engineering, Universiti Teknologi MARA (UiTM), 40450 Shah Alam, Selangor (Malaysia); Musa, M.Z. [NANO-ElecTronic Centre (NET), Faculty of Electrical Engineering, Universiti Teknologi MARA (UiTM), 40450 Shah Alam, Selangor (Malaysia); Faculty of Electrical Engineering, Universiti Teknologi MARA (UiTM) Pulau Pinang, Jalan Permatang Pauh, 13500 Permatang Pauh, Pulau Pinang (Malaysia); Soga, T. [Department of Frontier Materials, Nagoya Institute of Technology (NITech), Nagoya 466-8555 (Japan); Rahman, S.A. [Low Dimensional Materials Research Centre (LDMRC), Department of Physics, Faculty of Science, Universiti Malaya (UM), 50603 Kuala Lumpur (Malaysia); Alrokayan, Salman A.H.; Khan, Haseeb A. [Department of Biochemistry, College of Science, King Saud University (KSU), Riyadh 11451 (Saudi Arabia); Rusop, M. [NANO-ElecTronic Centre (NET), Faculty of Electrical Engineering, Universiti Teknologi MARA (UiTM), 40450 Shah Alam, Selangor (Malaysia); NANO-SciTech Centre (NST), Institute of Science (IOS), Universiti Teknologi MARA UiTM, 40450 Shah Alam, Selangor (Malaysia)

    2015-04-15

    We report on the growth of Al-doped ZnO (ZAO) thin films prepared by the sol–gel technique associated with dip-coating onto Corning 7740 glass substrates. The influence of varying thermal annealing (T{sub a}) temperature on crystallisation behaviour, optical and electrical properties of ZAO films has been systematically investigated. All films are polycrystalline with a hexagonal wurtzite structure with a preferential orientation according to the direction 〈0 0 2〉. The metamorphosis of strain/stress effects in ZAO thin films has been investigated using X-ray diffraction. The as growth films have a large compressive stress of 0.55 GPa, which relaxed to 0.25 GPa as the T{sub a} was increased to 500 °C. Optical parameters such as optical transmittance, absorption coefficient, refractive index and optical band gap energy have been studied and discussed with respect to T{sub a}. All films exhibit a transmittance above 80–90% along the visible–NIR range up to 1500 nm and a sharp absorption onset below 400 nm corresponding to the fundamental absorption edge of ZnO. Experimental results show that the tensile stress in the films reveals an incline pattern with the optical band gap energy, while the compressive stress shows opposite relation. - Highlights: • Minimum stress of highly c-axis oriented ZAO was grown at suitable T{sub a} temperature. • The ZAO crystal orientation was influenced by strain/stress of the film. • Minimum stress/strain of ZAO film leads to lower defects. • Bandgap and defects were closely intertwined with strain/stress. • We report additional optical and electrical properties based on T{sub a} temperature.

  3. Optimal joint scheduling of electrical and thermal appliances in a smart home environment

    International Nuclear Information System (INIS)

    Shirazi, Elham; Zakariazadeh, Alireza; Jadid, Shahram

    2015-01-01

    Highlights: • Thermal appliances are scheduled based on desired temperature and energy prices. • A discomfort index has been introduced within the home energy scheduling model. • Appliances are scheduled based on activity probability and desired options. • Starting probability depends on the social random factor and consumption behavior. - Abstract: With the development of home area network, residents have the opportunity to schedule their power usage in the home by themselves aiming at reducing electricity expenses. Moreover, as renewable energy sources are deployed in home, a home energy management system needs to consider both energy consumption and generation simultaneously to minimize the energy cost. In this paper, a smart home energy management model has been presented in which electrical and thermal appliances are jointly scheduled. The proposed method aims at minimizing the electricity cost of a residential customer by scheduling various type of appliances considering the residents consumption behavior, seasonal probability, social random factor, discomfort index and appliances starting probability functions. In this model, the home central controller receives the electricity price information, environmental factors data as well as the resident desired options in order to optimally schedule appliances including electrical and thermal. The scheduling approach is tested on a typical home including variety of home appliances, a small wind turbine, photovoltaic panel, combined heat and power unit, boiler and electrical and thermal storages over a 24-h period. The results show that the scheduling of different appliances can be reached simultaneously by using the proposed formulation. Moreover, simulation results evidenced that the proposed home energy management model exhibits a lower cost and, therefore, is more economical.

  4. Mechanical and electrical properties of red blood cells using optical tweezers

    International Nuclear Information System (INIS)

    Fontes, A; Castro, M L Barjas; Brandão, M M; Fernandes, H P; Huruta, R R; Costa, F F; Saad, S T O; Thomaz, A A; Pozzo, L Y; Barbosa, L C; Cesar, C L

    2011-01-01

    Optical tweezers are a very sensitive tool, based on photon momentum transfer, for individual, cell by cell, manipulation and measurements, which can be applied to obtain important properties of erythrocytes for clinical and research purposes. Mechanical and electrical properties of erythrocytes are critical parameters for stored cells in transfusion centers, immunohematological tests performed in transfusional routines and in blood diseases. In this work, we showed methods, based on optical tweezers, to study red blood cells and applied them to measure apparent overall elasticity, apparent membrane viscosity, zeta potential, thickness of the double layer of electrical charges and adhesion in red blood cells

  5. Optical sensors for the measurement of electric current and voltage

    Energy Technology Data Exchange (ETDEWEB)

    Rutgers, W R; Hulshof, H J.M.; Laurensse, I J; van der Wey, A H

    1987-01-01

    Optical sensors for the measurement of electrical current and voltage were developed for application in electric power systems. The current sensor, based on the Faraday effect in a monomode glass fiber, and the voltage sensor, based on the transverse Pockels effect in a crystal, are demonstrated in wide-band (10 MHz) interference-free measurements of pulsed currents and impulse voltages.

  6. Coherent phonon optics in a chip with an electrically controlled active device.

    Science.gov (United States)

    Poyser, Caroline L; Akimov, Andrey V; Campion, Richard P; Kent, Anthony J

    2015-02-05

    Phonon optics concerns operations with high-frequency acoustic waves in solid media in a similar way to how traditional optics operates with the light beams (i.e. photons). Phonon optics experiments with coherent terahertz and sub-terahertz phonons promise a revolution in various technical applications related to high-frequency acoustics, imaging, and heat transport. Previously, phonon optics used passive methods for manipulations with propagating phonon beams that did not enable their external control. Here we fabricate a phononic chip, which includes a generator of coherent monochromatic phonons with frequency 378 GHz, a sensitive coherent phonon detector, and an active layer: a doped semiconductor superlattice, with electrical contacts, inserted into the phonon propagation path. In the experiments, we demonstrate the modulation of the coherent phonon flux by an external electrical bias applied to the active layer. Phonon optics using external control broadens the spectrum of prospective applications of phononics on the nanometer scale.

  7. Multi-Directional Optical Diagnostics of Thermal Plasma Jets

    Czech Academy of Sciences Publication Activity Database

    Hlína, Jan; Chvála, František; Šonský, Jiří; Gruber, Jan

    2008-01-01

    Roč. 19, č. 1 (2008), s. 1-6 ISSN 0957-0233 R&D Projects: GA ČR(CZ) GA202/05/0728 Institutional research plan: CEZ:AV0Z20570509 Keywords : thermal plasma jet * optical diagnostics * Radon transform Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.493, year: 2008

  8. Optical and structural properties of CuSbS2 thin films grown by thermal evaporation method

    International Nuclear Information System (INIS)

    Rabhi, A.; Kanzari, M.; Rezig, B.

    2009-01-01

    Structural, optical and electrical properties of CuSbS 2 thin films grown by thermal evaporation have been studied relating the effects of substrate heating conditions of these properties. The CuSbS 2 thin films were carried out at substrate temperatures in the temperature range 100-200 deg. C . The structure and composition were characterized by XRD, SEM and EDX. X-ray diffraction revealed that the films are (111) oriented upon substrate temperature 170 deg. C and amorphous for the substrate temperatures below 170 deg. C . No secondary phases are observed for all the films. The optical absorption coefficients and band gaps of the films were estimated by optical transmission and reflection measurements at room temperature. Strong absorption coefficients in the range 10 5 -10 6 cm -1 at 500 nm were found. The direct gaps Eg lie between 0.91-1.89 eV range. It is observed that there is a decrease in optical band gap Eg with increasing the substrate temperature. Resistivity of 0.03-0.96 Ω cm, in dependence on substrate temperature was characterized. The all unheated films exhibit p-type conductivity. The characteristics reported here also offer perspective for CuSbS 2 as an absorber material in solar cells applications

  9. Significant improvement in the thermal annealing process of optical resonators

    Science.gov (United States)

    Salzenstein, Patrice; Zarubin, Mikhail

    2017-05-01

    Thermal annealing performed during process improves the quality of the roughness of optical resonators reducing stresses at the periphery of their surface thus allowing higher Q-factors. After a preliminary realization, the design of the oven and the electronic method were significantly improved thanks to nichrome resistant alloy wires and chopped basalt fibers for thermal isolation during the annealing process. Q-factors can then be improved.

  10. Solar thermal electric power generation - an attractive option for Pakistan

    International Nuclear Information System (INIS)

    Khan, N.A

    1999-01-01

    Solar Thermal Energy is being successfully used for production of electricity in few developed countries for more than 10 years. In solar Electric Generating Systems high temperature is generated by concentrating solar energy on black absorber pipe in evacuated glass tubes. This heat is absorbed and transported with the help of high temperature oil in to highly insulated heat exchanger storage tanks. They are subsequently used to produce steam that generates power through steam turbines as in standard thermal power plants. Various components involved in Solar thermal field have been developed at the Solar Systems Laboratory of College of EME, NUST Rawalpindi. It is considered as a cost effective alternate for power generation. The research has been partially sponsored by Ministry of Science and Technology under its Public Sector Development Program (PSDP) in (1996-1998). Parabolic mirror design, fabrication, polishing, installation, solar tracking, absorber pipe, glass tubes, steam generation al have been developed. This paper will cover the details of indigenous technological break through made in this direction. (author)

  11. Nanostructure design for drastic reduction of thermal conductivity while preserving high electrical conductivity.

    Science.gov (United States)

    Nakamura, Yoshiaki

    2018-01-01

    The design and fabrication of nanostructured materials to control both thermal and electrical properties are demonstrated for high-performance thermoelectric conversion. We have focused on silicon (Si) because it is an environmentally friendly and ubiquitous element. High bulk thermal conductivity of Si limits its potential as a thermoelectric material. The thermal conductivity of Si has been reduced by introducing grains, or wires, yet a further reduction is required while retaining a high electrical conductivity. We have designed two different nanostructures for this purpose. One structure is connected Si nanodots (NDs) with the same crystal orientation. The phonons scattering at the interfaces of these NDs occurred and it depended on the ND size. As a result of phonon scattering, the thermal conductivity of this nanostructured material was below/close to the amorphous limit. The other structure is Si films containing epitaxially grown Ge NDs. The Si layer imparted high electrical conductivity, while the Ge NDs served as phonon scattering bodies reducing thermal conductivity drastically. This work gives a methodology for the independent control of electron and phonon transport using nanostructured materials. This can bring the realization of thermoelectric Si-based materials that are compatible with large scale integrated circuit processing technologies.

  12. Harvesting electrical energy from torsional thermal actuation driven by natural convection.

    Science.gov (United States)

    Kim, Shi Hyeong; Sim, Hyeon Jun; Hyeon, Jae Sang; Suh, Dongseok; Spinks, Geoffrey M; Baughman, Ray H; Kim, Seon Jeong

    2018-06-07

    The development of practical, cost-effective systems for the conversion of low-grade waste heat to electrical energy is an important area of renewable energy research. We here demonstrate a thermal energy harvester that is driven by the small temperature fluctuations provided by natural convection. This harvester uses coiled yarn artificial muscles, comprising well-aligned shape memory polyurethane (SMPU) microfibers, to convert thermal energy to torsional mechanical energy, which is then electromagnetically converted to electrical energy. Temperature fluctuations in a yarn muscle, having a maximum hot-to-cold temperature difference of about 13 °C, were used to spin a magnetic rotor to a peak torsional rotation speed of 3,000 rpm. The electromagnetic energy generator converted the torsional energy to electrical energy, thereby producing an oscillating output voltage of up to 0.81 V and peak power of 4 W/kg, based on SMPU mass.

  13. Optical and electrical properties of chemical bath deposited cobalt sulphide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Govindasamy, Geetha [R& D Centre, Bharathiar University, Coimbatore (India); Murugasen, Priya, E-mail: priyamurugasen15@gmail.com [Department of Physics, Saveetha Engineering, Chennai, Tamil Nadu (India); Sagadevan, Suresh [Department of Physics, AMET University, Chennai, Tamil Nadu (India)

    2017-01-15

    Cobalt sulphide (CoS) thin films were synthesized using the Chemical Bath Deposition (CBD) technique. X-ray diffraction (XRD) analysis was used to study the structure and the crystallite size of CoS thin film. Scanning Electron Microscope (SEM) studies reveal the surface morphology of these films. The optical properties of the CoS thin films were determined using UV-Visible absorption spectrum. The optical band gap of the thin films was found to be 1.6 eV. Optical constants such as the refractive index, the extinction coefficient and the electric susceptibility were determined. The dielectric studies were carried out at different frequencies and at different temperatures for the prepared CoS thin films. In addition, the plasma energy of the valence electron, Penn gap or average energy gap, the Fermi energy and electronic polarizability of the thin films were determined. The AC electrical conductivity measurement was also carried out for the thin films. The activation energy was determined by using DC electrical conductivity measurement. (author)

  14. Transmutor demo unit and thermal into electrical energy transformation problems

    International Nuclear Information System (INIS)

    Matal, O.; Fiedler, J.

    1999-01-01

    In the three circuits layout of the transmutor the heat is transferred from the primary through the secondary circuits by a favourable heat carrier into the tertiary circuit where the thermal into electrical energy transformation in turbo-generator comes into force. Properties as well as parameters of the heat carrier in the secondary circuit affect basically both the conceptual layout of the tertiary circuit and consequently investments costs for its realization and the effectiveness of the transformation of thermal into electrical energy. For several heat carriers considered for the transmutor secondary circuit particular tertiary circuit concepts for the demonstration transmutor unit of approx. 15 W thermal power rate are analyzed, layout features and possibilities of turbogenerator selection are commented and investment costs as well as effectiveness of thermal into electrical energy transformation are estimated. Some of the results are as follows: (i) Heat carrier properties influence thermodynamics of the TDU water/steam cycle substantially. One of the dominant parameters is the melting (freezing) temperature of the heat carrier. (ii) Heat carrier properties influence investment costs of components of the TDU tertiary circuit substantially. Dominantly influenced are costs of the steam generator, steam turbine and high pressure regeneration system. (iii) If the heat carrier has to be a molten salt than a salt with a low melting temperature is recommended to be selected, for example KHF2. (iv) Eutectic alloy Pb-Bi as the heat carrier serves changes to design the TDU with efficient thermodynamics, with acceptable low investment costs of the tertiary as well as secondary circuit components and with an acceptable level of the nuclear safety

  15. Thermal and Arc Flash Analysis of Electric Motor Drives in Distribution Networks

    OpenAIRE

    Nikolovski, Srete; Mlakić, Dragan; Alibašić, Emir

    2017-01-01

    The paper presents thermal analysis and arc flash analysis taking care of protection relays coordination settings for electric motor drives connected to the electrical network. Power flow analysis is performed to check if there are any voltage and loading violation conditions in the system. Fault analysis is performed to check the short circuit values and compute arc flash energy dissipated at industrial busbars to eliminate damage to electrical equipment and electrical shocks and hazard to p...

  16. Optical properties and thermal stability of LaYbO3 ternary oxide for high-k dielectric application

    Science.gov (United States)

    Su, Wei-tao; Yang, Li; Li, Bin

    2011-01-01

    A new ternary rare oxide dielectric LaYbO3 film had been prepared on silicon wafers and quartz substrates by reactive sputtering method using a La-Yb metal target. A range of analysis techniques was performed to determine the optical band gap, thermal stability, and electrical property of the deposited samples. It was found the band gap of LaYbO3 film was about 5.8 eV. And the crystallization temperature for rapid thermal annealing (20 s) was between 900 and 950 °C. X-ray photoelectron spectroscopy results indicate the formation of the SiO2 and silicate in the interface between silicon wafer and LaYbO3 film. The dielectric constant is about 23 from the calculation of capacitance-voltage curve, which is comparable higher than previously reported La2O3 or Yb2O3 film.

  17. Electrical Versus Optical: Comparing Methods for Detecting Terahertz Radiation Using Neon Lamps

    Science.gov (United States)

    Slocombe, L. L.; Lewis, R. A.

    2018-05-01

    Terahertz radiation impinging on a lit neon tube causes additional ionization of the encapsulated gas. As a result, the electrical current flowing between the electrodes increases and the glow discharge in the tube brightens. These dual phenomena suggest two distinct modes of terahertz sensing. The electrical mode simply involves measuring the electrical current. The optical mode involves monitoring the brightness of the weakly ionized plasma glow discharge. Here, we directly compare the two detection modes under identical experimental conditions. We measure 0.1-THz radiation modulated at frequencies in the range 0.1-10 kHz, for lamp currents in the range 1-10 mA. We find that electrical detection provides a superior signal-to-noise ratio while optical detection has a faster response. Either method serves as the basis of a compact, robust, and inexpensive room-temperature detector of terahertz radiation.

  18. Optical losses due to tracking on solar thermal collectors

    DEFF Research Database (Denmark)

    Sallaberry, Fabienne; Pujol-Nadal, Ramn; Peres, Bengt

    2017-01-01

    For a wide range of operational temperatures, the solar thermal collectors can use optical concentration systems to optimize their efficiency. However, as optical concentration relies on direct solar radiation, it is necessary to use a solar tracker following the sun direction to maximize...... the amount of useful solar radiation received. The selection of the appropriate tracking systems matching the optical concentration factor is essential to achieve optimal collector efficiency. Otherwise, the concentrator would experience high optical losses due to the inadequate focusing of the direct solar...... radiation onto its receiver, regardless of its quality. This paper gives the state-of-the-art of the methodologies available to characterize the tracking error of a concentrating collector, a summary of different previous studies done in this subject and of the standardization regarding the tracking...

  19. Design and Testing of a Thermal Storage System for Electric Vehicle Cabin Heating

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Mingyu [MAHLE Behr Troy Inc.; WolfeIV, Edward [MAHLE Behr Troy Inc.; Craig, Timothy [MAHLE Behr Troy Inc.; LaClair, Tim J [ORNL; Gao, Zhiming [ORNL; Abdelaziz, Omar [ORNL

    2016-01-01

    Without the waste heat available from the engine of a conventional automobile, electric vehicles (EVs) must provide heat to the cabin for climate control using energy stored in the vehicle. In current EV designs, this energy is typically provided by the traction battery. In very cold climatic conditions, the power required to heat the EV cabin can be of a similar magnitude to that required for propulsion of the vehicle. As a result, the driving range of an EV can be reduced very significantly during winter months, which limits consumer acceptance of EVs and results in increased battery costs to achieve a minimum range while ensuring comfort to the EV driver. To minimize the range penalty associated with EV cabin heating, a novel climate control system that includes thermal energy storage has been designed for use in EVs and plug-in hybrid electric vehicles (PHEVs). The system uses the stored latent heat of an advanced phase change material (PCM) to provide cabin heating. The PCM is melted while the EV is connected to the electric grid for charging of the electric battery, and the stored energy is subsequently transferred to the cabin during driving. To minimize thermal losses when the EV is parked for extended periods, the PCM is encased in a high performance insulation system. The electrical PCM-Assisted Thermal Heating System (ePATHS) was designed to provide enough thermal energy to heat the EV s cabin for approximately 46 minutes, covering the entire daily commute of a typical driver in the U.S.

  20. Performance investigation of a concentrating photovoltaic/thermal system with transmissive Fresnel solar concentrator

    International Nuclear Information System (INIS)

    Feng, Chaoqing; Zheng, Hongfei; Wang, Rui; Ma, Xinglong

    2016-01-01

    Highlights: • A common design method of a cycloidal transmissive Fresnel solar concentrator was presented. • The gallium arsenide high concentrated solar was used as the receiver. • High efficiency of electric generating could be achieved at noon. • Fresnel solar concentrator was studied and compared in hazy weather and clear weather. - Abstract: A design method of a cycloidal transmissive Fresnel solar concentrator which can provide a certain width focal line was presented in this study. Based on the optical principle of refraction, the dimensions of each wedge-shaped element of Fresnel lens are calculated. An optical simulation has been done to obtain the optical efficiency of the concentrator for different tracking error and axial incidence angle. It has been found that about 80% of the incident sunlight can still be gathered by the absorber when the tracking error is within 0.7°. When the axial angle of incidence is within 10°, it almost has no influence to the receiving rate. The concentrating photovoltaic/thermal system with transmissive Fresnel solar concentrator has been designed in this paper. Take the gallium arsenide high concentrated battery as the receiver, experimental research about cylindrical Fresnel concentrating photovoltaic/thermal system is undertaken in the real sky. Main parameters are tested such as the temperature distribution on receiver, electric energy and thermal energy outputs of concentrating photovoltaic/thermal system, the efficiency of multipurpose utilization of electric and heat, and so on. The test results in clear weather show that maximum electric generating efficiency is about 18% at noon, the maximum heat receiving rate of cooling water is about 45%. At noon time (11:00–13:00), the total efficiency of thermal and electricity can reach more than 55%. Performance of this concentrating photovoltaic/thermal system with transmissive Fresnel solar concentrator is studied and compared in two types typical weather, hazy

  1. Survey of solar thermal energy storage subsystems for thermal/electric applications

    Energy Technology Data Exchange (ETDEWEB)

    Segaser, C. L.

    1978-08-01

    A survey of the current technology and estimated costs of subsystems for storing the thermal energy produced by solar collectors is presented. The systems considered were capable of producing both electricity and space conditioning for three types of loads: a single-family detached residence, an apartment complex of 100 units, and a city of 30,000 residents, containing both single-family residences and apartments. Collector temperatures will be in four ranges: (1) 100 to 250/sup 0/F (used for space heating and single-cycle air conditioners and organic Rankine low-temperature turbines); (2) 300 to 400/sup 0/F (used for dual-cycle air conditioners and low-temperature turbines); (3) 400 to 600/sup 0/F (using fluids from parabolic trough collectors to run Rankine turbines); (4) 800 to 1000/sup 0/F (using fluids from heliostats to run closed-cycle gas turbines and steam Rankine turbines). The solar thermal energy subsystems will require from 60 to 36 x 10/sup 5/ kWhr (2.05 x 10/sup 5/ to 1.23 x 10/sup 10/ Btu) of thermal storage capacity. In addition to sensible heat and latent heat storage materials, several other media were investigated as potential thermal energy storage materials, including the clathrate and semiclathrate hydrates, various metal hydrides, and heat storage based on inorganic chemical reactions.

  2. Electrical and Optical Properties of Nanosized Perovskite-type La ...

    African Journals Online (AJOL)

    Electrical and Optical Properties of Nanosized Perovskite-type La 0.5 Ca 0.5 MO 3 (M=Co,Ni) ... In addition, the TEM images show that the average particle size of ... of both compounds decreases exponentially by increasing the temperature.

  3. Full-energy-chain analysis of greenhouse gas emissions for solar thermal electric power generation systems

    International Nuclear Information System (INIS)

    Norton, B.; Lawson, W.R.

    1997-01-01

    Technical attributes and environmental impacts of solar thermal options for centralized electricity generation are discussed. In particular, the full-energy-chain, including embodied energy and energy production, is considered in relation to greenhouse gas emission arising from solar thermal electricity generation. Central receiver, parabolic dish, parabolic trough and solar pond systems are considered. (author)

  4. Composite cavity based fiber optic Fabry–Perot strain sensors demodulated by an unbalanced fiber optic Michelson interferometer with an electrical scanning mirror

    International Nuclear Information System (INIS)

    Zhang, Jianzhong; Yang, Jun; Sun, Weimin; Yuan, Libo; Jin, Wencai; Peng, G D

    2008-01-01

    A composite cavity based fiber optic Fabry–Perot strain sensor system, interrogated by a white light source and demodulated by an unbalanced fiber optic Michelson interferometer with an electrical scanning mirror, is proposed and demonstrated. Comparing with the traditional extrinsic fiber optic Fabry–Perot strain sensor, the potential multiplexing capability and the dynamic measurement range are improved simultaneously. At the same time, the measurement stability of the electrical scanning mirror system is improved by the self-referenced signal of the sensor structure

  5. Investigation on surface, electrical and optical properties of ITO-Ag-ITO coated glass

    International Nuclear Information System (INIS)

    Aslan Necdet; Sen, Tuba; Coruhlu Turgay; Senturk Kenan; Keskin Sinan; Seker Sedat; Dobrovolskiy Andrey

    2015-01-01

    The aim of this work was to study the optical and electrical properties of thick ITO-Ag-ITO multilayer coating onto glass. ITO-Ag-ITO coatings with thickness of ITO layers 110 nm, 185 nm and intermediate Ag layer thickness 40 nm were prepared by magnetron sputtering. The optical, electrical and atomic properties of the coating were examined by scanning electron microscope, atomic force microscope, X-ray diffraction analysis and ultraviolet-visible spectroscopy

  6. Vector optical fields with polarization distributions similar to electric and magnetic field lines.

    Science.gov (United States)

    Pan, Yue; Li, Si-Min; Mao, Lei; Kong, Ling-Jun; Li, Yongnan; Tu, Chenghou; Wang, Pei; Wang, Hui-Tian

    2013-07-01

    We present, design and generate a new kind of vector optical fields with linear polarization distributions modeling to electric and magnetic field lines. The geometric configurations of "electric charges" and "magnetic charges" can engineer the spatial structure and symmetry of polarizations of vector optical field, providing additional degrees of freedom assisting in controlling the field symmetry at the focus and allowing engineering of the field distribution at the focus to the specific applications.

  7. Aerosol absorption measurement with a sinusoidal phase modulating fiber optic photo thermal interferometer

    Science.gov (United States)

    Li, Shuwang; Shao, Shiyong; Mei, Haiping; Rao, Ruizhong

    2016-10-01

    Aerosol light absorption plays an important role in the earth's atmosphere direct and semi-direct radiate forcing, simultaneously, it also has a huge influence on the visibility impairment and laser engineering application. Although various methods have been developed for measuring aerosol light absorption, huge challenge still remains in precision, accuracy and temporal resolution. The main reason is that, as a part of aerosol light extinction, aerosol light absorption always generates synchronously with aerosol light scattering, and unfortunately aerosol light scattering is much stronger in most cases. Here, a novel photo-thermal interferometry is proposed only for aerosol absorption measurement without disturbance from aerosol scattering. The photo-thermal interferometry consists of a sinusoidal phase-modulating single mode fiber-optic interferometer. The thermal dissipation, caused by aerosol energy from photo-thermal conversion when irritated by pump laser through interferometer, is detected. This approach is completely insensitive to aerosol scattering, and the single mode fiber-optic interferometer is compact, low-cost and insensitive to the polarization shading. The theory of this technique is illustrated, followed by the basic structure of the sinusoidal phase-modulating fiber-optic interferometer and demodulation algorithms. Qualitative and quantitative analysis results show that the new photo-thermal interference is a potential approach for aerosol absorption detection and environmental pollution detection.

  8. Intrinsic and extrinsic electrical and thermal transport of bulk black phosphorus

    Science.gov (United States)

    Hu, Sile; Xiang, Junsen; Lv, Meng; Zhang, Jiahao; Zhao, Hengcan; Li, Chunhong; Chen, Genfu; Wang, Wenhong; Sun, Peijie

    2018-01-01

    We report a comprehensive investigation of the electrical, thermal, and thermoelectric transport properties of bulk single-crystalline black phosphorus in wide temperature (2-300 K) and field (0-9 T) ranges. Electrical transport below T ≈ 250 K is found to be dominated by extrinsic hole-type charge carriers with large mobility exceeding 104 cm2/V s at low temperatures. While thermal transport measurements reveal an enhanced in-plane thermal conductivity maximum κ = 180 W/m K at T ≈ 25 K, it appears still to be largely constrained by extrinsic phonon scattering processes, e.g., the electron-phonon process, in addition to intrinsic umklapp scattering. The thermoelectric power and Nernst effect seem to be strongly influenced by ambipolar transport of charge carriers with opposite signs in at least the high-temperature region above 200 K, which diminishes the thermoelectric power factor of this material. Our results provide a timely update to the transport properties of bulk black phosphorus for future fundamental and applied research.

  9. Effect of rapid oxidation on optical and electrical properties of silicon nanowires obtained by chemical etching

    Science.gov (United States)

    Karyaoui, M.; Bardaoui, A.; Ben Rabha, M.; Harmand, J. C.; Amlouk, M.

    2012-05-01

    In the present work, we report the investigation of passivated silicon nanowires (SiNWs) having an average radius of 3.7 μm, obtained by chemical etching of p-type silicon (p-Si). The surface passivation of the SiNWs was performed through a rapid oxidation conducted under a controlled atmosphere at different temperatures and durations. The morphology of the SiNWs was examined using a scanning electron microscope (SEM) that revealed a wave-like structure of dense and vertically aligned one-dimensional silicon nanostructures. On the other hand, optical and electrical characterizations of the SiNWs were studied using a UV-Vis-NIR spectrometer, the Fourier transform infrared spectroscopy (FTIR) and I-V measurements. The reflectance of SiNWs has been dropped to approximately 2% in comparison to that of bare p-Si. This low reflectance slightly increased after carrying out the rapid thermal annealing. The observed behavior was attributed to the formation of a SiO2 layer, as confirmed by FTIR measurements. Finally, the electrical measurements have shown that the rapid oxidation, at certain conditions, contributes to the improvement of the electrical responses of the SiNWs, which can be of great interest for photovoltaic applications.

  10. Electrically conductive, black thermal control coatings for spacecraft applications. III - Plasma-deposited ceramic matrix

    Science.gov (United States)

    Hribar, V. F.; Bauer, J. L.; O'Donnell, T. P.

    1987-01-01

    Five black, electrically-conductive thermal control coatings have been formulated and tested for application on the Galileo spacecraft. The coatings consist of both organic and inorganic systems applied on titanium, aluminum, and glass/epoxy composite surfaces. The coatings were tested under simulated space environment conditions. Coated specimens were subjected to thermal radiation, convective and combustive heating, and cryogenic conditions over a temperature range between -196 C and 538 C. Mechanical, physical, thermal, electrical, and thermooptical properties are presented for one of these coatings. This paper describes the preparation, characteristics, and spraying of iron titanate on titanium and aluminum, and presents performance results.

  11. Integration of plug-in hybrid electric vehicles in a regional wind-thermal power system

    International Nuclear Information System (INIS)

    Goeransson, Lisa; Karlsson, Sten; Johnsson, Filip

    2010-01-01

    This study investigates consequences of integrating plug-in hybrid electric vehicles (PHEVs) in a wind-thermal power system supplied by one quarter of wind power and three quarters of thermal generation. Four different PHEV integration strategies, with different impacts on the total electric load profile, have been investigated. The study shows that PHEVs can reduce the CO 2 -emissions from the power system if actively integrated, whereas a passive approach to PHEV integration (i.e. letting people charge the car at will) is likely to result in an increase in emissions compared to a power system without PHEV load. The reduction in emissions under active PHEV integration strategies is due to a reduction in emissions related to thermal plant start-ups and part load operation. Emissions of the power sector are reduced with up to 4.7% compared to a system without PHEVs, according to the simulations. Allocating this emission reduction to the PHEV electricity consumption only, and assuming that the vehicles in electric mode is about 3 times as energy efficient as standard gasoline operation, total emissions from PHEVs would be less than half the emissions of a standard car, when running in electric mode.

  12. Electrical crosstalk-coupling measurement and analysis for digital closed loop fibre optic gyro

    International Nuclear Information System (INIS)

    Jing, Jin; Hai-Ting, Tian; Xiong, Pan; Ning-Fang, Song

    2010-01-01

    The phase modulation and the closed-loop controller can generate electrical crosstalk-coupling in digital closed-loop fibre optic gyro. Four electrical cross-coupling paths are verified by the open-loop testing approach. It is found the variation of ramp amplitude will lead to the alternation of gyro bias. The amplitude and the phase parameters of the electrical crosstalk signal are measured by lock-in amplifier, and the variation of gyro bias is confirmed to be caused by the alternation of phase according to the amplitude of the ramp. A digital closed-loop fibre optic gyro electrical crosstalk-coupling model is built by approximating the electrical cross-coupling paths as a proportion and integration segment. The results of simulation and experiment show that the modulation signal electrical crosstalk-coupling can cause the dead zone of the gyro when a small angular velocity is inputted, and it could also lead to a periodic vibration of the bias error of the gyro when a large angular velocity is inputted

  13. Optical and electrical properties of nickel xanthate thin films

    Indian Academy of Sciences (India)

    Administrator

    metal-xanthate thin films' production, nor their optical, electrical properties and .... vibration of –CH3 at 894 cm–1, (vii) the symmetric bend- ing vibration of C–O–C at 458 .... vity values are the two most important factors, affecting band width.

  14. Understanding the thermal, mechanical and electrical properties of epoxy nanocomposites

    International Nuclear Information System (INIS)

    Sarathi, R.; Sahu, R.K.; Rajeshkumar, P.

    2007-01-01

    In the present work, the electrical, mechanical and thermal properties of epoxy nanocomposite materials were studied. The electrical insulation characteristics were analyzed through short time breakdown voltage test, accelerated electrical ageing test, and by tracking test. The breakdown voltage increases with increase in nano-clay content up to 5 wt%, under AC and DC voltages. The volume resistivity, permittivity and tan(δ) of the epoxy nanocomposites were measured. The Weibull studies indicate that addition of nanoclay upto 5 wt% enhances the characteristic life of epoxy nanocomposite insulation material. The tracking test results indicate that the tracking time is high with epoxy nanocomposites as compared to pure epoxy. Ageing studies were carried out to understand the surface characteristic variation through contact angle measurement. The hydrophobicity of the insulating material was analysed through contact angle measurement. The diffusion coefficients of the material with different percentage of clay in epoxy nanocomposites were calculated. The exfoliation characteristics in epoxy nanocomposites were analyzed through wide angle X-ray diffraction (WAXD) studies. The thermal behaviour of the epoxy nanocomposites was analyzed by carrying out thermo gravimetric-differential thermal analysis (TG-DTA) studies. Heat deflection temperature of the material was measured to understand the stability of the material for intermittent temperature variation. The dynamic mechanical analysis (DMA) results indicated that storage modulus of the material increases with small amount of clay in epoxy resin. The activation energy of the material was calculated from the DMA results

  15. Optical investigations of the effect of solvent and thermal annealing on the optoelectronic properties of Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) films

    Energy Technology Data Exchange (ETDEWEB)

    Laskarakis, A., E-mail: alask@physics.auth.gr; Karagiannidis, P.G.; Georgiou, D.; Nikolaidou, D.M.; Logothetidis, S.

    2013-08-31

    Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is one of the most promising conducting polymers that can be used as transparent electrode or as buffer layer for organic electronic devices. However, when used as an electrode, its conductivity has to be optimized either by the addition of solvents or by post-deposition processing. In this work, we investigate the effect of the addition of the polar solvent dimethylsulfoxide (DMSO) to an aqueous PEDOT:PSS solution on its optical and electrical properties by the implementation of the Drude model for the analysis of the measured pseudo-dielectric function by Spectroscopic Ellipsometry from the near infrared to the visible–far ultraviolet spectral range. The results show that the addition of DMSO increases significantly the film conductivity, which reaches a maximum value at an optimum DMSO concentration as it has confirmed by experimentally measured conductivity values. The post-deposition thermal annealing has been found to have a smaller effect on the film conductivity. - Highlights: • Optical study of Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) • The Drude model provides information for PEDOT:PSS conductivity. • The addition of dimethylsulfoxide increases the electrical conductivity of PEDOT:PSS. • The increase in conductivity is correlated to increase of PEDOT grain size. • The thermal treatment has a smaller effect on PEDOT:PSS properties.

  16. Optical investigations of the effect of solvent and thermal annealing on the optoelectronic properties of Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) films

    International Nuclear Information System (INIS)

    Laskarakis, A.; Karagiannidis, P.G.; Georgiou, D.; Nikolaidou, D.M.; Logothetidis, S.

    2013-01-01

    Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is one of the most promising conducting polymers that can be used as transparent electrode or as buffer layer for organic electronic devices. However, when used as an electrode, its conductivity has to be optimized either by the addition of solvents or by post-deposition processing. In this work, we investigate the effect of the addition of the polar solvent dimethylsulfoxide (DMSO) to an aqueous PEDOT:PSS solution on its optical and electrical properties by the implementation of the Drude model for the analysis of the measured pseudo-dielectric function by Spectroscopic Ellipsometry from the near infrared to the visible–far ultraviolet spectral range. The results show that the addition of DMSO increases significantly the film conductivity, which reaches a maximum value at an optimum DMSO concentration as it has confirmed by experimentally measured conductivity values. The post-deposition thermal annealing has been found to have a smaller effect on the film conductivity. - Highlights: • Optical study of Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) • The Drude model provides information for PEDOT:PSS conductivity. • The addition of dimethylsulfoxide increases the electrical conductivity of PEDOT:PSS. • The increase in conductivity is correlated to increase of PEDOT grain size. • The thermal treatment has a smaller effect on PEDOT:PSS properties

  17. Studies of Electrical and Thermal Conductivities of Sheared Multi-Walled Carbon Nanotube with Isotactic Polypropylene Polymer Composites

    Directory of Open Access Journals (Sweden)

    Parvathalu Kalakonda

    2015-01-01

    at higher temperature due to isotropic electrical and thermal contact in both directions. Oriented MWCNT/iPP nanocomposites exhibit higher electrical and thermal conductivities, attributed primarily by orientation of nanotubes due to the shearing fabrication process.

  18. Fiber-Optic Temperature and Pressure Sensors Applied to Radiofrequency Thermal Ablation in Liver Phantom: Methodology and Experimental Measurements

    Directory of Open Access Journals (Sweden)

    Daniele Tosi

    2015-01-01

    Full Text Available Radiofrequency thermal ablation (RFA is a procedure aimed at interventional cancer care and is applied to the treatment of small- and midsize tumors in lung, kidney, liver, and other tissues. RFA generates a selective high-temperature field in the tissue; temperature values and their persistency are directly related to the mortality rate of tumor cells. Temperature measurement in up to 3–5 points, using electrical thermocouples, belongs to the present clinical practice of RFA and is the foundation of a physical model of the ablation process. Fiber-optic sensors allow extending the detection of biophysical parameters to a vast plurality of sensing points, using miniature and noninvasive technologies that do not alter the RFA pattern. This work addresses the methodology for optical measurement of temperature distribution and pressure using four different fiber-optic technologies: fiber Bragg gratings (FBGs, linearly chirped FBGs (LCFBGs, Rayleigh scattering-based distributed temperature system (DTS, and extrinsic Fabry-Perot interferometry (EFPI. For each instrument, methodology for ex vivo sensing, as well as experimental results, is reported, leading to the application of fiber-optic technologies in vivo. The possibility of using a fiber-optic sensor network, in conjunction with a suitable ablation device, can enable smart ablation procedure whereas ablation parameters are dynamically changed.

  19. Growth, optical, thermal and dielectric studies of an amino acid organic nonlinear optical material: L-Alanine

    International Nuclear Information System (INIS)

    Caroline, M. Lydia; Sankar, R.; Indirani, R.M.; Vasudevan, S.

    2009-01-01

    Good transparent bulk single crystals of L-alanine (nonlinear optical material) have been grown successfully by slow cooling technique from aqueous solution at pH value of 2.0. Optically transparent crystals with dimensions 2.4 cm x 1.2 cm x 1.6 cm, were grown by optimizing the growth parameters within a growth period of 2 weeks. The crystallinity of L-alanine crystal was confirmed by the powder X-ray diffraction study and diffraction peaks are indexed. The vibrational structure of the molecule is elucidated from FTIR spectra. The thermal behaviour of the grown crystal was investigated by thermogravimetric (TG) and differential thermal analyses (DTA) techniques in a nitrogen atmosphere. The result showed that the material starts decomposing at 297 deg. C. Its optical behaviour has been examined by UV-vis spectral analysis, which shows the absence of absorbance between the wavelengths ranging from 200 to 1200 nm. The NLO property was confirmed by the powder technique of Kurtz and Perry. The dielectric behaviour of the sample was also studied for the first time

  20. Prospects for solar thermal electricity generation - an introduction

    International Nuclear Information System (INIS)

    DeLaquil, P.

    1991-01-01

    The future potential for solar thermal electric power plants is quite significant. The size of the renewable energy resource base for the United States of America alone is almost 500 times its current primary energy consumption. Unfortunately, the levels of current utilization are quite small. Why have these technologies not made a larger contribution to today's market? The answer is that significant barriers still exist. (orig.)

  1. Thermal hypersensitisation and grating evolution in Ge-doped optical fibre

    DEFF Research Database (Denmark)

    Sørensen, Henrik Rokkjær; Canning, John; Kristensen, Martin

    2005-01-01

    Low temperature (sub 1000°C) thermal hypersensitisation is reported in germanosilicate optical waveguides. Gratings are written using a CW 266nm laser source. In contrast to laser hypersensitisation, thermal excitation is generally dispersive involving a range of specific glass sites. More comple...... grating profiles presenting evidence of solid-state autocatalysis and bistability at increasingly high sensitisation temperatures are observed. More specifically, at 500°C, a behaviour resembling type IIA grating response is observed....

  2. Combined simulation of energy and thermal management for an electric vehicle

    Energy Technology Data Exchange (ETDEWEB)

    Mohrmann, Bjoern; Jeck, Peter [Institut fuer Kraftfahrzeuge Aachen (Germany); Simon, Carsten [fortiss GmbH, Muenchen (Germany); Ungermann, Jochen [Audi AG, Ingolstadt (Germany)

    2012-11-01

    The project eperformance, which is funded by the BMBF, is conducted by project partners from RWTH Aachen, Audi, Bosch Engineering and fortiss GmbH, in order to demonstrate the concept of an electric vehicle on the basis of a holistic development approach. To support this, several simulation platforms come into use, i.e. CFD Simulation for cooling concepts, electromagnetic simulations for electric machine design, physical simulation of cooling circuits as well as vehicle mechanics and controller design. To develop an energy efficient vehicle management, some of these simulation domains have to be combined, to simulate interdependencies between for example usage of high-voltage batteries, their thermal response and the impact for controller strategies. Within the project it was decided to use the Tool TISC (TLK Inter Software Connector) to combine as well a physical model, based on Modelica/Dymola to simulate thermal behaviours of components with a longitudinal vehicle model and a controller model, both based in MATLAB/Simulink. Advantages of such a coupled simulation are the re-usability of existing models in both tools with their tool-specific benefits as well as the possibility to cluster the models on different computers. The article will explain how the combined simulation is set up and parameterized, and will show two use cases: the thermal management of the two independent battery systems of the demonstrator vehicle and the torque distribution on the three electric machines in the vehicle, depending on the drive situation and the thermal state of the machines. (orig)

  3. Assessing energy efficiency of electric car bottom furnaces intended for thermal energization of minerals

    Science.gov (United States)

    Nizhegorodov, A. I.

    2017-01-01

    The paper deals with a new concept of electric furnaces for roasting and thermal energization of vermiculite and other minerals with vibrational transportation of a single-layer mass under constant thermal field. The paper presents performance calculation and comparative assessment of energy data for furnaces of different modifications: flame and electric furnaces with three units, furnaces with six units and ones with series-parallel connection of units, and furnaces of new concept.

  4. Mechanical, Thermal, and Electrical Energy Storage in a Single Working Body: Electrification and Thermal Effects upon Pressure-Induced Water Intrusion-Extrusion in Nanoporous Solids.

    Science.gov (United States)

    Grosu, Yaroslav; Mierzwa, Michał; Eroshenko, Valentine A; Pawlus, Sebastian; Chorażewski, Mirosław; Nedelec, Jean-Marie; Grolier, Jean-Pierre E

    2017-03-01

    This paper presents the first experimental evidence of pronounced electrification effects upon reversible cycle of forced water intrusion-extrusion in nanoporous hydrophobic materials. Recorded generation of electricity combined with high-pressure calorimetric measurements improves the energy balance of {nanoporous solid + nonwetting liquid} systems by compensating mechanical and thermal energy hysteresis in the cycle. Revealed phenomena provide a novel way of "mechanical to electrical" and/or "thermal to electrical" energy transformation with unprecedented efficiency and additionally open a perspective to increase the efficiency of numerous energy applications based on such systems taking advantage of electricity generation during operational cycle.

  5. Demonstration of a high speed hybrid electrical and optical sensing system for next generation launcher applications

    Science.gov (United States)

    Ibrahim, Selwan K.; O'Dowd, John A.; Honniball, Arthur; Bessler, Vivian; Farnan, Martin; O'Connor, Peter; Melicher, Milos; Gleeson, Danny

    2017-09-01

    The Future Launchers Preparatory Programme (FLPP) supported by the European Space Agency (ESA) has a goal of developing various launch vehicle system concepts and identifying the technologies required for the design of Europe's Next-Generation Launcher (NGL) while maintaining competitiveness on the commercial market. Avionics fiber optic sensing technology was investigated as part of the FLPP programme. Here we demonstrate and evaluate a high speed hybrid electrical/optical data acquisition system based on commercial off the shelf (COTS) technology capable of acquiring data from traditional electrical sensors and optical Fibre Bragg Grating (FBG) sensors. The proposed system consists of the KAM-500 data acquisition system developed by Curtis-Wright and the I4 tunable laser based fiber optic sensor interrogator developed by FAZ Technology. The key objective was to demonstrate the capability of the hybrid system to acquire data from traditional electrical sensors used in launcher applications e.g. strain, temperature and pressure in combination with optical FBG sensors, as well as data delivery to spacecraft avionics systems. The KAM-500 was configured as the main acquisition unit (MAU) and provided a 1 kHz sampling clock to the I4 interrogator that was configured as the secondary acquisition unit (SAU) to synchronize the data acquisition sample rate between both systems. The SAU acquired data from an array of optical FBG sensors, while the MAU data acquisition system acquired data from the electrical sensors. Data acquired from the optical sensors was processed by the FAZ I4 interrogation system and then encapsulated into UDP/IP packets and transferred to the KAM-500. The KAM-500 encapsulated the optical sensor data together with the data acquired from electrical sensors and transmitted the data over MIL-STD-1553 and Ethernet data interface. The temperature measurements resulted in the optical and electrical sensors performing on a par with each other, with all

  6. Electrical, thermal and abusive tests on lithium thionyl chloride cells

    Science.gov (United States)

    Frank, H. A.

    1980-04-01

    Electrical characterizations, thermal characterizations, and outer limits tests of lithium thionyl chloride cells are discussed. Graphs of energy density vs power density and heat rate vs time are presented along with results of forced reversal and high rate discharge tests.

  7. Simultaneous optical and electrical modeling of plasmonic light trapping in thin-film amorphous silicon photovoltaic devices

    Science.gov (United States)

    Gandhi, Keyur K.; Nejim, Ahmed; Beliatis, Michail J.; Mills, Christopher A.; Henley, Simon J.; Silva, S. Ravi P.

    2015-01-01

    Rapid prototyping of photovoltaic (PV) cells requires a method for the simultaneous simulation of the optical and electrical characteristics of the device. The development of nanomaterial-enabled PV cells only increases the complexity of such simulations. Here, we use a commercial technology computer aided design (TCAD) software, Silvaco Atlas, to design and model plasmonic gold nanoparticles integrated in optoelectronic device models of thin-film amorphous silicon (a-Si:H) PV cells. Upon illumination with incident light, we simulate the optical and electrical properties of the cell simultaneously and use the simulation to produce current-voltage (J-V) and external quantum efficiency plots. Light trapping due to light scattering and localized surface plasmon resonance interactions by the nanoparticles has resulted in the enhancement of both the optical and electrical properties due to the reduction in the recombination rates in the photoactive layer. We show that the device performance of the modeled plasmonic a-Si:H PV cells depends significantly on the position and size of the gold nanoparticles, which leads to improvements either in optical properties only, or in both optical and electrical properties. The model provides a route to optimize the device architecture by simultaneously optimizing the optical and electrical characteristics, which leads to a detailed understanding of plasmonic PV cells from a design perspective and offers an advanced tool for rapid device prototyping.

  8. Application of complex geometrical optics to determination of thermal, transport, and optical parameters of thin films by the photothermal beam deflection technique.

    Science.gov (United States)

    Korte, Dorota; Franko, Mladen

    2015-01-01

    In this work, complex geometrical optics is, for what we believe is the first time, applied instead of geometrical or wave optics to describe the probe beam interaction with the field of the thermal wave in photothermal beam deflection (photothermal deflection spectroscopy) experiments on thin films. On the basis of this approach the thermal (thermal diffusivity and conductivity), optical (energy band gap), and transport (carrier lifetime) parameters of the semiconductor thin films (pure TiO2, N- and C-doped TiO2, or TiO2/SiO2 composites deposited on a glass or aluminum support) were determined with better accuracy and simultaneously during one measurement. The results are in good agreement with results obtained by the use of other methods and reported in the literature.

  9. Effect of Ar bombardment on the electrical and optical properties of ...

    Indian Academy of Sciences (India)

    The influence of low-energy Ar ion beam irradiation on both electrical and optical properties of low-density polyethylene (LDPE) films is presented. The polymer films were bombarded with 320 keV Ar ions with fuences up to 1 × 10 15 cm − 2 . Electrical properties of LDPE films were measured and the effect of ion ...

  10. Toward Highly Efficient Nanostructured Solar Cells Using Concurrent Electrical and Optical Design

    KAUST Repository

    Wang, Hsin-Ping

    2017-07-11

    Recent technological advances in conventional planar and microstructured solar cell architectures have significantly boosted the efficiencies of these devices near the corresponding theoretical values. Nanomaterials and nanostructures have promising potential to push the theoretical limits of solar cell efficiency even higher using the intrinsic advantages associated with these materials, including efficient photon management, rapid charge transfer, and short charge collection distances. However, at present the efficiency of nanostructured solar cells remains lower than that of conventional solar devices due to the accompanying losses associated with the employment of nanomaterials. The concurrent design of both optical and electrical components will presumably be an imperative route toward breaking the present-day limit of nanostructured solar cells. This review summarizes the losses in traditional solar cells, and then discusses recent advances in applications of nanotechnology to solar devices from both optical and electrical perspectives. Finally, a rule for nanostructured solar cells by concurrently engineering the optical and electrical design is devised. Following these guidelines should allow for exceeding the theoretical limit of solar cell efficiency soon.

  11. Evaluation of electrical and thermal conductivity of polymeric wastes ...

    African Journals Online (AJOL)

    This work being gingered by the big menace being posed on our environment by polymeric waste and it's rechanneling involved the studying of the electrical and thermal conductivities of the polymers PP, PE, PS and nylon66 doped with charcoal and graphite. Five grams of each polymer was mixed with varying ...

  12. Experiment Investigation on Electrical and Thermal Performances of a Semitransparent Photovoltaic/Thermal System with Water Cooling

    Directory of Open Access Journals (Sweden)

    Guiqiang Li

    2014-01-01

    Full Text Available Different from the semitransparent building integrated photovoltaic/thermal (BIPV/T system with air cooling, the semitransparent BIPV/T system with water cooling is rare, especially based on the silicon solar cells. In this paper, a semitransparent photovoltaic/thermal system (SPV/T with water cooling was set up, which not only would provide the electrical power and hot water, but also could attain the natural illumination for the building. The PV efficiency, thermal efficiency, and exergy analysis were all adopted to illustrate the performance of SPV/T system. The results showed that the PV efficiency and the thermal efficiency were about 11.5% and 39.5%, respectively, on the typical sunny day. Furthermore, the PV and thermal efficiencies fit curves were made to demonstrate the SPV/T performance more comprehensively. The performance analysis indicated that the SPV/T system has a good application prospect for building.

  13. New Electro-Thermal Battery Pack Model of an Electric Vehicle

    Directory of Open Access Journals (Sweden)

    Muhammed Alhanouti

    2016-07-01

    Full Text Available Since the evolution of the electric and hybrid vehicle, the analysis of batteries’ characteristics and influence on driving range has become essential. This fact advocates the necessity of accurate simulation modeling for batteries. Different models for the Li-ion battery cell are reviewed in this paper and a group of the highly dynamic models is selected for comparison. A new open circuit voltage (OCV model is proposed. The new model can simulate the OCV curves of lithium iron magnesium phosphate (LiFeMgPO4 battery type at different temperatures. It also considers both charging and discharging cases. The most remarkable features from different models, in addition to the proposed OCV model, are integrated in a single hybrid electrical model. A lumped thermal model is implemented to simulate the temperature development in the battery cell. The synthesized electro-thermal battery cell model is extended to model a battery pack of an actual electric vehicle. Experimental tests on the battery, as well as drive tests on the vehicle are performed. The proposed model demonstrates a higher modeling accuracy, for the battery pack voltage, than the constituent models under extreme maneuver drive tests.

  14. Thermal stability and electrical conductivity in polyethers-molybdenum disulfide nanocomposites

    International Nuclear Information System (INIS)

    Mirabal, N.; Aguirre, P.; Santa Ana, M.A.; Benavente, E.; Gonzalez, Guillermo

    2003-01-01

    The intercalation of poly(ethylene oxide) (PEO), into molybdenum disulfide, like that of other electron pair donors, leads to mixed ionic-electronic conductors. At room temperature, intercalates show electrical and lithium-ion conductivities better than MoS 2 and bulk PEO composites, respectively. However, these products are known to be sensitive to temperature; indeed, in the range 80-100 deg. C an irreversible decrease of the electrical conductivity is observed. In order to investigate these features, the thermal behavior of a series of polyethers of different molecular weights (poly(ethylene glycol) (Mw 3400) and PEO with Mw in the range 10 4 -4x10 6 , pure and intercalated in MoS 2 , (Li x (MoS 2 )(polyether) y with x∼0.1 and y=1.1-1.5), was comparatively analyzed. Furthermore, the effect of thermal treatment of the sample on the electrical conductivity was studied for one of the intercalated products. Results indicate that irreversible changes, detected by both loss of weight and a significant conductivity lowering, are occurring in the range from about 100 deg. C to a temperature near to the decomposition point of the organic phase at about 350 deg. C

  15. Recouping the thermal-to-electric conversion loss by the use of waste heat

    International Nuclear Information System (INIS)

    Bradley, W.J.

    1976-01-01

    This paper looks at ways to recoup the thermal-to-electric conversion loss of our thermal power generating stations. These stations now produce twice as much low-grade waste heat as they do electricity. We can improve the situation in two ways: by improving the station efficiency, and by utilizing the low-grade heat beneficially. The following options are examined: N 2 O 4 turbines condensing at 10 deg C; power from moderator waste heat; 50 MW heat pump for district heating; industrial parks with integrated waste heat upgrading station. (author)

  16. Electrical transport in crystalline phase change materials

    Energy Technology Data Exchange (ETDEWEB)

    Woda, Michael

    2012-01-06

    In this thesis, the electrical transport properties of crystalline phase change materials are discussed. Phase change materials (PCM) are a special class of semiconducting and metallic thin film alloys, typically with a high amount of the group five element antimony or the group six element tellurium, such as Ge{sub 2}Sb{sub 2}Te{sub 5}. The unique property portfolio of this material class makes it suitable for memory applications. PCMs reveal fast switching between two stable room-temperature phases (amorphous and crystalline) realized by optical laser or electrical current pulses in memory devices. Additionally, a pronounced property contrast in form of optical reflectivity and electrical conductivity between the amorphous and crystalline phase is the characteristic fingerprint of PCMs. The emerging electrical solid state memory PCRAM is a very promising candidate to replace Flash memory in the near future or to even become a universal memory, which is non-volatile and shows the speed and cyclability of DRAM. One of the main technological challenges is the switching process into the amorphous state, which is the most power demanding step. In order to reduce the switching power, the crystalline resistivity needs to be increased at a given voltage. Thus understanding and tayloring of this property is mandatory. In this work, first the technological relevance, i.e. optical and electrical memory concepts based on PCMs are introduced. Subsequently a description of the physical properties of PCMs in four categories is given. Namely, structure, kinetics, optical properties and electrical properties are discussed. Then important recent developments such as the identification of resonant bonding in crystalline PCMs and a property predicting coordination scheme are briefly reviewed. The following chapter deals with the theoretical background of electrical transport, while the next chapter introduces the experimental techniques: Sputtering, XRR, XRD, DSC, thermal annealing

  17. Optical pump-and-probe test system for thermal characterization of thin metal and phase-change films

    International Nuclear Information System (INIS)

    Watabe, Kazuo; Polynkin, Pavel; Mansuripur, Masud

    2005-01-01

    A single-shot optical pump-and-probe test system is reported. The system is designed for thermal characterization of thin-film samples that can change their phase state under the influence of a short and intense laser pulse on a subnanosecond time scale. In combination with numerical analysis, the system can be used to estimate thermal constants of thin films, such as specific heat and thermal conductivity. In-plane and out-of plane thermal conductivity can be estimated independently. The system is intended for use in research on optical data storage and material processing with pulsed laser light. The system design issues are discussed. As application examples, we report on using the system to study thermal dynamics in two different thin-film samples: a gold film on a glass substrate (a single-phase system) and the quadrilayer phase-change stack typical in optical data-storage applications

  18. Optical diagnostics of atmospheric pressure air plasmas

    International Nuclear Information System (INIS)

    Laux, C O; Spence, T G; Kruger, C H; Zare, R N

    2003-01-01

    Atmospheric pressure air plasmas are often thought to be in local thermodynamic equilibrium owing to fast interspecies collisional exchange at high pressure. This assumption cannot be relied upon, particularly with respect to optical diagnostics. Velocity gradients in flowing plasmas and/or elevated electron temperatures created by electrical discharges can result in large departures from chemical and thermal equilibrium. This paper reviews diagnostic techniques based on optical emission spectroscopy and cavity ring-down spectroscopy that we have found useful for making temperature and concentration measurements in atmospheric pressure plasmas under conditions ranging from thermal and chemical equilibrium to thermochemical nonequilibrium

  19. High throughput integrated thermal characterization with non-contact optical calorimetry

    Science.gov (United States)

    Hou, Sichao; Huo, Ruiqing; Su, Ming

    2017-10-01

    Commonly used thermal analysis tools such as calorimeter and thermal conductivity meter are separated instruments and limited by low throughput, where only one sample is examined each time. This work reports an infrared based optical calorimetry with its theoretical foundation, which is able to provide an integrated solution to characterize thermal properties of materials with high throughput. By taking time domain temperature information of spatially distributed samples, this method allows a single device (infrared camera) to determine the thermal properties of both phase change systems (melting temperature and latent heat of fusion) and non-phase change systems (thermal conductivity and heat capacity). This method further allows these thermal properties of multiple samples to be determined rapidly, remotely, and simultaneously. In this proof-of-concept experiment, the thermal properties of a panel of 16 samples including melting temperatures, latent heats of fusion, heat capacities, and thermal conductivities have been determined in 2 min with high accuracy. Given the high thermal, spatial, and temporal resolutions of the advanced infrared camera, this method has the potential to revolutionize the thermal characterization of materials by providing an integrated solution with high throughput, high sensitivity, and short analysis time.

  20. Ice thermal storage air conditioning system for electric load leveling; Denryoku heijunka to hyochikunetsu system

    Energy Technology Data Exchange (ETDEWEB)

    Shigenaga, Y. [Daikin Industries Ltd., Osaka (Japan)

    1998-08-15

    Thermal storage air conditioning system is the one to use energy stored into thermal storing materials by using night electric power and to operate effective air conditioning. Therefore, as load can be treated by the stored energy, volume of the apparatus can be reduced. And, by reduction of the consumed power at day time, it can contribute to leveling of electric power demand. In general, there are two types in the thermal storage method: one is a method to store as thermal energy, and the other is that to store as chemical energy. For conditions required for the storing materials, important elements on their actual uses are not only physical properties such as large thermal storage per unit and easy thermal in- and out-puts, but also safety, long-term reliability, and easy receiving and economics containing future. The ice thermal storage air conditioning system is classified at the viewpoint of type of ice, kind of thermal storing medium, melting method on using cooling and heating, kinds of thermal medium on cooling and heating. 3 refs., 5 figs., 2 tabs.

  1. Nanomechanical Optical Fiber with Embedded Electrodes Actuated by Joule Heating.

    Science.gov (United States)

    Lian, Zhenggang; Segura, Martha; Podoliak, Nina; Feng, Xian; White, Nicholas; Horak, Peter

    2014-07-31

    Nanomechanical optical fibers with metal electrodes embedded in the jacket were fabricated by a multi-material co-draw technique. At the center of the fibers, two glass cores suspended by thin membranes and surrounded by air form a directional coupler that is highly temperature-dependent. We demonstrate optical switching between the two fiber cores by Joule heating of the electrodes with as little as 0.4 W electrical power, thereby demonstrating an electrically actuated all-fiber microelectromechanical system (MEMS). Simulations show that the main mechanism for optical switching is the transverse thermal expansion of the fiber structure.

  2. Nanomechanical Optical Fiber with Embedded Electrodes Actuated by Joule Heating

    Science.gov (United States)

    Lian, Zhenggang; Segura, Martha; Podoliak, Nina; Feng, Xian; White, Nicholas; Horak, Peter

    2014-01-01

    Nanomechanical optical fibers with metal electrodes embedded in the jacket were fabricated by a multi-material co-draw technique. At the center of the fibers, two glass cores suspended by thin membranes and surrounded by air form a directional coupler that is highly temperature-dependent. We demonstrate optical switching between the two fiber cores by Joule heating of the electrodes with as little as 0.4 W electrical power, thereby demonstrating an electrically actuated all-fiber microelectromechanical system (MEMS). Simulations show that the main mechanism for optical switching is the transverse thermal expansion of the fiber structure. PMID:28788148

  3. Electrical-optical characterization of multijunction solar cells under 2000X concentration

    Science.gov (United States)

    Bonsignore, Gaetano; Gallitto, Aurelio Agliolo; Agnello, Simonpietro; Barbera, Marco; Candia, Roberto; Cannas, Marco; Collura, Alfonso; Dentici, Ignazio; Gelardi, Franco Mario; Cicero, Ugo Lo; Montagnino, Fabio Maria; Paredes, Filippo; Sciortino, Luisa

    2014-09-01

    In the framework of the FAE "Fotovoltaico ad Alta Efficienza" ("High Efficiency Photovoltaic") Research Project (PO FESR Sicilia 2007/2013 4.1.1.1), we have performed electrical and optical characterizations of commercial InGaP/InGaAs/Ge triple-junction solar cells (1 cm2) mounted on a prototype HCPV module, installed in Palermo (Italy). This system uses a reflective optics based on rectangular off-axis parabolic mirror with aperture 45×45 cm2 leading to a geometrical concentration ratio of 2025. In this study, we report the I-V curve measured under incident power of about 700 W/m2 resulting in an electrical power at maximum point (PMP) of 41.4 W. We also investigated the optical properties by the electroluminescence (EL) spectra of the top (InGaP) and middle (InGaAs) subcells. From the analysis of the experimental data we extracted the bandgap energies of these III-V semiconductors in the range 305÷385 K.

  4. Electrical and optical properties of silicon-doped gallium nitride

    Indian Academy of Sciences (India)

    Si-doped GaN films in polycrystalline form were deposited on quartz substrates at deposition temperatures ranging from 300–623 K using r.f. sputtering technique. Electrical, optical and microstructural properties were studied for these films. It was observed that films deposited at room temperature contained mainly ...

  5. Spectroscopic, thermal, and electrical properties of MgO/ polyvinyl pyrrolidone/ polyvinyl alcohol nanocomposites

    Science.gov (United States)

    Mohammed, Gh.; El Sayed, Adel M.; Morsi, W. M.

    2018-04-01

    In this study, we aimed to control the optical and electrical properties of polyvinyl alcohol (PVA) in order to broaden its industrial and technological applications, which we achieved by blending PVA with polyvinyl pyrrolidone (PVP) and adding sol-gel prepared MgO nanopowder. The blended film and nanocomposite films were prepared using the solution casting technique. X-ray diffraction analyses showed that the crystallite size was ∼18.4 nm for MgO and the highest degree of crystallinity (XC) in the films was about 24.34% at 1.0 wt% MgO. High resolution transmission electron microscopy determined the nanoribbon morphology of MgO. Scanning electron microscopy (SEM) indicated the uniform distribution of the MgO nanoribbons on the surfaces of the PVA/PVP films. SEM and Fourier transform infrared spectroscopy also confirmed the interaction between the blend and MgO fillers. The effects of the additives on the glass transition (Tg) and melting (Tm) temperatures were evaluated by differential thermal analysis and differential scanning calorimetry. The appearance of one melting point confirmed the miscibility of the two polymers. According to ultraviolet-visible-near infrared spectroscopy measurements, the optical properties and optical constants of PVA could be adjusted by the addition of PVP and MgO, where the optical band gap (Eg) determined for PVA increased with the PVP content, whereas it decreased to 4.8 eV as the MgO content increased. The DC conductivity (σdc) of the films increased whereas the activation energy (Ea) decreased after the addition of MgO, possibly because the nanoribbon shape fixed the preferred conducting pathways. In addition, MgO could break the H-bond in sbnd OH groups of the blends to allow the free movement of the molecular chains.

  6. Electrically tunable coherent optical absorption in graphene with ion gel.

    Science.gov (United States)

    Thareja, Vrinda; Kang, Ju-Hyung; Yuan, Hongtao; Milaninia, Kaveh M; Hwang, Harold Y; Cui, Yi; Kik, Pieter G; Brongersma, Mark L

    2015-03-11

    We demonstrate electrical control over coherent optical absorption in a graphene-based Salisbury screen consisting of a single layer of graphene placed in close proximity to a gold back reflector. The screen was designed to enhance light absorption at a target wavelength of 3.2 μm by using a 600 nm-thick, nonabsorbing silica spacer layer. An ionic gel layer placed on top of the screen was used to electrically gate the charge density in the graphene layer. Spectroscopic reflectance measurements were performed in situ as a function of gate bias. The changes in the reflectance spectra were analyzed using a Fresnel based transfer matrix model in which graphene was treated as an infinitesimally thin sheet with a conductivity given by the Kubo formula. The analysis reveals that a careful choice of the ionic gel layer thickness can lead to optical absorption enhancements of up to 5.5 times for the Salisbury screen compared to a suspended sheet of graphene. In addition to these absorption enhancements, we demonstrate very large electrically induced changes in the optical absorption of graphene of ∼3.3% per volt, the highest attained so far in a device that features an atomically thick active layer. This is attributable in part to the more effective gating achieved with the ion gel over the conventional dielectric back gates and partially by achieving a desirable coherent absorption effect linked to the presence of the thin ion gel that boosts the absorption by 40%.

  7. Electrical resistivity and thermal properties of compatibilized multi-walled carbon nanotube/polypropylene composites

    Directory of Open Access Journals (Sweden)

    A. Szentes

    2012-06-01

    Full Text Available The electrical resistivity and thermal properties of multi-walled carbon nanotube/polypropylene (MWCNT/PP composites have been investigated in the presence of coupling agents applied for improving the compatibility between the nanotubes and the polymer. A novel olefin-maleic-anhydride copolymer and an olefin-maleic-anhydride copolymer based derivative have been used as compatibilizers to achieve better dispersion of MWCNTs in the polymer matrix. The composites have been produced by extrusion followed by injection moulding. They contained different amounts of MWCNTs (0.5, 2, 3 and 5 wt% and coupling agent to enhance the interactions between the carbon nanotubes and the polymer. The electrical resistivity of the composites has been investigated by impedance spectroscopy, whereas their thermal properties have been determined using a thermal analyzer operating on the basis of the periodic thermal perturbation method. Rheological properties, BET-area and adsorption-desorption isotherms have been determined. Dispersion of MWCNTs in the polymer has been studied by scanning electron microscopy (SEM.

  8. Thermal tunability of photonic bandgaps in liquid crystal infiltrated microstructured polymer optical fibers

    DEFF Research Database (Denmark)

    Yuan, Scott Wu; Wei, Lei; Alkeskjold, Thomas Tanggaard

    2009-01-01

    We demonstrate the photonic bandgap effect and the thermal tunability of bandgaps in microstructured polymer optical fibers infiltrated with liquid crystal. Two liquid crystals with opposite sign of the temperature gradient of the ordinary refractive index (E7 and MDA-00- 1444) are used to demons......We demonstrate the photonic bandgap effect and the thermal tunability of bandgaps in microstructured polymer optical fibers infiltrated with liquid crystal. Two liquid crystals with opposite sign of the temperature gradient of the ordinary refractive index (E7 and MDA-00- 1444) are used...... to demonstrate that both signs of the thermal tunability of the bandgaps are possible. The useful bandgaps are ultimately bounded to the visible range by the transparency window of the polymer....

  9. Dynamic thermal characteristics of heat pipe via segmented thermal resistance model for electric vehicle battery cooling

    Science.gov (United States)

    Liu, Feifei; Lan, Fengchong; Chen, Jiqing

    2016-07-01

    Heat pipe cooling for battery thermal management systems (BTMSs) in electric vehicles (EVs) is growing due to its advantages of high cooling efficiency, compact structure and flexible geometry. Considering the transient conduction, phase change and uncertain thermal conditions in a heat pipe, it is challenging to obtain the dynamic thermal characteristics accurately in such complex heat and mass transfer process. In this paper, a ;segmented; thermal resistance model of a heat pipe is proposed based on thermal circuit method. The equivalent conductivities of different segments, viz. the evaporator and condenser of pipe, are used to determine their own thermal parameters and conditions integrated into the thermal model of battery for a complete three-dimensional (3D) computational fluid dynamics (CFD) simulation. The proposed ;segmented; model shows more precise than the ;non-segmented; model by the comparison of simulated and experimental temperature distribution and variation of an ultra-thin micro heat pipe (UMHP) battery pack, and has less calculation error to obtain dynamic thermal behavior for exact thermal design, management and control of heat pipe BTMSs. Using the ;segmented; model, the cooling effect of the UMHP pack with different natural/forced convection and arrangements is predicted, and the results correspond well to the tests.

  10. Joining and Performance of Alkali Metal Thermal-to-electric Converter (AMTEC)

    Energy Technology Data Exchange (ETDEWEB)

    Suh, Min-Soo; Lee, Wook-Hyun; Woo, Sang-Kuk [Korea Institute of Energy Research, Daejeon (Korea, Republic of)

    2017-07-15

    The alkali-Metal Thermal-to-electric Converter (AMTEC) is one of the promising static energy conversion technologies for the direct conversion of thermal energy to electrical energy. The advantages over a conventional energy converter are its high theoretical conversion efficiency of 40% and power density of 500 W/kg. The working principle of an AMTEC battery is the electrochemical reaction of the sodium through an ion conducting electrolyte. Sodium ion pass through the hot side of the beta”-alumina solid electrolyte (BASE) primarily as a result of the pressure difference. This pressure difference across the BASE has a significant effect on the overall performance of the AMTEC system. In order to build the high pressure difference across the BASE, hermeticity is required for each joined components for high temperature range of 900°C. The AMTEC battery was manufactured by utilizing robust joining technology of BASE/insulator/metal flange interfaces of the system for both structural and electrical stability. The electrical potential difference between the anode and cathode sides, where the electrons emitted from sodium ionization and recombined into sodium, was characterized as the open-circuit voltage. The efforts of technological improvement were concentrated on a high-power output and conversion efficiency. This paper discusses about the joining and performance of the AMTEC systems.

  11. Thermal and Electrical Characterization of the Carbon Nanofibers Based Cement Composites

    Directory of Open Access Journals (Sweden)

    Agnieszka ŚLOSARCZYK

    2017-08-01

    Full Text Available The paper describes the influence of chemical modification of vapor grown carbon nanofibers (VGCnFs on the thermal and electrical properties of the cement composites. The surface modification of nanofibers was performed by means of ozone and nitric acid treatments. It was shown that the oxidized carbon nanofibers surface plays an important role in shaping the mechanical and especially electrical properties of cement composite. For cement matrix modified with carbon nanofibers subjected to oxidized treatment, the slightly increase of cement paste resistivity was observed. It confirms the better adhesion of carbon nanofibers to cement paste. However, independently of carbon nanofibers modification, the occurrence of VGCnFs in cement paste increased the electrical conductivity of the composite in comparison to the cement paste without fibers. The obtained values of electrical resistivity were comparable with values of cement composites modified with 4 mm long carbon fibers. Moreover, it was shown that the chemical modification of carbon nanofibers surface does not influence on the thermal properties of cement composites. In case of cement paste with unmodified and modified carbon nanofibers, the Seebeck voltage was proportional to the temperature difference and was independent of the oxidation degree of carbon nanofibers.DOI: http://dx.doi.org/10.5755/j01.ms.23.2.14993

  12. High-performance flat-panel solar thermoelectric generators with high thermal concentration

    Science.gov (United States)

    Kraemer, Daniel; Poudel, Bed; Feng, Hsien-Ping; Caylor, J. Christopher; Yu, Bo; Yan, Xiao; Ma, Yi; Wang, Xiaowei; Wang, Dezhi; Muto, Andrew; McEnaney, Kenneth; Chiesa, Matteo; Ren, Zhifeng; Chen, Gang

    2011-07-01

    The conversion of sunlight into electricity has been dominated by photovoltaic and solar thermal power generation. Photovoltaic cells are deployed widely, mostly as flat panels, whereas solar thermal electricity generation relying on optical concentrators and mechanical heat engines is only seen in large-scale power plants. Here we demonstrate a promising flat-panel solar thermal to electric power conversion technology based on the Seebeck effect and high thermal concentration, thus enabling wider applications. The developed solar thermoelectric generators (STEGs) achieved a peak efficiency of 4.6% under AM1.5G (1 kW m-2) conditions. The efficiency is 7-8 times higher than the previously reported best value for a flat-panel STEG, and is enabled by the use of high-performance nanostructured thermoelectric materials and spectrally-selective solar absorbers in an innovative design that exploits high thermal concentration in an evacuated environment. Our work opens up a promising new approach which has the potential to achieve cost-effective conversion of solar energy into electricity.

  13. High-performance flat-panel solar thermoelectric generators with high thermal concentration.

    Science.gov (United States)

    Kraemer, Daniel; Poudel, Bed; Feng, Hsien-Ping; Caylor, J Christopher; Yu, Bo; Yan, Xiao; Ma, Yi; Wang, Xiaowei; Wang, Dezhi; Muto, Andrew; McEnaney, Kenneth; Chiesa, Matteo; Ren, Zhifeng; Chen, Gang

    2011-05-01

    The conversion of sunlight into electricity has been dominated by photovoltaic and solar thermal power generation. Photovoltaic cells are deployed widely, mostly as flat panels, whereas solar thermal electricity generation relying on optical concentrators and mechanical heat engines is only seen in large-scale power plants. Here we demonstrate a promising flat-panel solar thermal to electric power conversion technology based on the Seebeck effect and high thermal concentration, thus enabling wider applications. The developed solar thermoelectric generators (STEGs) achieved a peak efficiency of 4.6% under AM1.5G (1 kW m(-2)) conditions. The efficiency is 7-8 times higher than the previously reported best value for a flat-panel STEG, and is enabled by the use of high-performance nanostructured thermoelectric materials and spectrally-selective solar absorbers in an innovative design that exploits high thermal concentration in an evacuated environment. Our work opens up a promising new approach which has the potential to achieve cost-effective conversion of solar energy into electricity. © 2011 Macmillan Publishers Limited. All rights reserved

  14. Influence of thermal treatment in N{sub 2} atmosphere on chemical, microstructural and optical properties of indium tin oxide and nitrogen doped indium tin oxide rf-sputtered thin films

    Energy Technology Data Exchange (ETDEWEB)

    Stroescu, H.; Anastasescu, M.; Preda, S.; Nicolescu, M.; Stoica, M. [Institute of Physical Chemistry “Ilie Murgulescu” of the Romanian Academy, Spl. Independentei 202, 060021 Bucharest (Romania); Stefan, N. [National Institute for Lasers, Plasma and Radiation Physics, Atomistilor 409, RO-77125, Bucharest-Magurele (Romania); Kampylafka, V.; Aperathitis, E. [FORTH-IESL, Crete (Greece); Modreanu, M. [Tyndall National Institute, University College Cork, Cork (Ireland); Zaharescu, M. [Institute of Physical Chemistry “Ilie Murgulescu” of the Romanian Academy, Spl. Independentei 202, 060021 Bucharest (Romania); Gartner, M., E-mail: mgartner@icf.ro [Institute of Physical Chemistry “Ilie Murgulescu” of the Romanian Academy, Spl. Independentei 202, 060021 Bucharest (Romania)

    2013-08-31

    We report the influence of the normal thermal treatment (TT) and of rapid thermal annealing (RTA) on the microstructural, optical and electrical properties of indium tin oxide (ITO) and nitrogen doped indium tin oxide (ITO:N) thin films. The TT was carried out for 1 h at 400 °C and the RTA for 1 min up to 400 °C, both in N{sub 2} atmosphere. The ITO and ITO:N films were deposited by reactive sputtering in Argon, and respectively Nitrogen plasma, on Si with (100) and (111) orientation. The present study brings data about the microstructural and optical properties of ITO thin films with thicknesses around 300–400 nm. Atomic Force Microscopy analysis showed the formation of continuous and homogeneous films, fully covered by quasi-spherical shaped particles, with higher roughness values on Si(100) as compared to Si(111). Spectroscopic ellipsometry allowed the determination of film thickness, optical band gap as well as of the dispersion curves of n and k optical constants. X-ray diffraction analysis revealed the presence of diffraction peaks corresponding to the same nominal bulk composition of ITO, but with different intensities and preferential orientation depending on the substrate, atmosphere of deposition and type of thermal treatment. - Highlights: ► Stability of the films can be monitored by experimental ellipsometric spectra. ► The refractive index of indium tin oxide film on 0.3–30 μm range is reported. ► Si(100) substrate induces rougher film surfaces than Si(111). ► Rapid thermal annealing and normal thermal treatment lead to stable conductive film. ► The samples have a higher preferential orientation after rapid thermal annealing.

  15. Electrical properties and thermal expansion of strontium aluminates

    Energy Technology Data Exchange (ETDEWEB)

    Zakharchuk, K.V. [Department of Materials and Ceramic Engineering, CICECO, University of Aveiro, 3810-193 Aveiro (Portugal); Yaremchenko, A.A., E-mail: ayaremchenko@ua.pt [Department of Materials and Ceramic Engineering, CICECO, University of Aveiro, 3810-193 Aveiro (Portugal); Fagg, D.P. [TEMA-NRD, Mechanical Engineering Department, University of Aveiro, 3810-193 Aveiro (Portugal)

    2014-11-15

    Highlights: • Sr{sub 3}Al{sub 2}O{sub 6}, SrAl{sub 2}O{sub 4} and Sr{sub 4}Al{sub 14}O{sub 25} ceramics are semiconductors. • Electrical conductivity is as low as 10{sup −6}−4×10{sup −5} S/cm at 1273 K in dry air. • SrAl{sub 2}O{sub 4} is a mixed conductor with predominant ionic conductivity. • Sr{sub 3}Al{sub 2}O{sub 6} shows significant contribution of protonic transport in wet atmospheres. • Average TECs vary in the range (8.5–11.1)×10{sup −6} K{sup −1} and are p(O{sub 2})-independent. - Abstract: Strontium aluminate ceramics, including Sr{sub 3}Al{sub 2}O{sub 6}, SrAl{sub 2}O{sub 4} and Sr{sub 4}Al{sub 14}O{sub 25}, synthesized by glycine–nitrate combustion and sintered at 1773 K in air, were characterized by thermal analysis, dilatometry and electrical measurements in controlled atmospheres. All studied strontium aluminates are semiconductors with electrical conductivities as low as 10{sup −6}−4×10{sup −5} S/cm at 1273 K in dry air. Electrical measurements in controlled atmospheres in combination with ion transference number determination demonstrated that SrAl{sub 2}O{sub 4} is a mixed conductor with predominant ionic conductivity and increasing n-type and p-type electronic contributions under highly reducing and oxidizing conditions, respectively. While the behavior of electrical conductivity of Sr{sub 3}Al{sub 2}O{sub 6} in dry atmospheres was qualitatively similar to that of SrAl{sub 2}O{sub 4}, a significant increase of conductivity in wet atmospheres was attributed to a protonic contribution to electrical conduction, in correlation with thermogravimetric data and the tendency of this material to form a hydrogarnet at low temperatures. The average thermal expansion coefficients of strontium aluminates, (8.5–11.1)×10{sup −6} K{sup −1} at 333–1373 K, increase with increasing strontium content in the sequence Sr{sub 4}Al{sub 14}O{sub 25} < SrAl{sub 2}O{sub 4} < Sr{sub 3}Al{sub 2}O{sub 6} and are essentially

  16. Electrically and magnetically controlled optical spanner based on the transfer of spin angular momentum of light in an optically active medium

    International Nuclear Information System (INIS)

    Chen Lixiang; Zheng Guoliang; She Weilong

    2007-01-01

    An optical spanner is a light beam that can exert a torque on an object. It is demonstrated in this Rapid Communication that, with the aid of applied electric and magnetic fields, a light beam with initially linear polarization and initially zero total spin angular momentum can interact with an optically active medium, resulting in a change of the ratio of left-handed circularly polarized photons to right-handed ones. Thus the total spin angular momentum of the light is changed, which leads to a torque, creating an electrically and magnetically controlled optical spanner on the medium. For a linearly polarized 632.8 nm laser beam incident on a 100-μm-long Ce:Bi 12 TiO 20 whisker crystal with 5 μm radius, if the magnetic field is fixed at -1.8 T, both the left- (right-)handed circularly polarized photon number and the total spin angular momentum vary with the applied electric field in a sinusoidal way, which means the torque exerted by the optical spanner on the crystal also varies sinusoidally with the electric field. It is found that at 50 (or-50) kV/cm, 56% right- (left-)handed circularly polarized photons are translated into left- (right-)handed ones, which corresponds to a transfer of 0.56(ℎ/2π) spin angular momentum contributed by each photon

  17. Thin films of molecular materials synthesized from C32H20N10M (M Co, Pb, Fe): Film formation, electrical and optical properties

    International Nuclear Information System (INIS)

    Rodriguez, A.; Sanchez Vergara, M.E.; Garcia Montalvo, V.; Ortiz, A.; Alvarez, J.R.

    2010-01-01

    In this work, the synthesis of molecular materials formed from metallic phthalocyanines and 1,4-phenylenediamine is reported. The powder and thin film (∼80-115 nm thickness) samples of the synthesized materials, deposited by vacuum thermal evaporation, show the same intra-molecular bonds in the IR spectroscopy studies, which suggests that the thermal evaporation process does not alter these bonds. The morphology of the deposited films was studied using scanning electron microscopy (SEM) and atomic force microscopy (AFM) and their optical and electrical properties were studied as well. The optical parameters have been investigated using spectrophotometric measurements of transmittance in the wavelength range 200-1200 nm. The absorption spectra recorded in the UV-vis region for the deposited samples showed two bands, namely the Q and Soret bands. The optical activation energy was calculated and found to be 3.41 eV for the material with cobalt, 3.34 eV for the material including lead and 3.5 eV for the material with iron. The effect of temperature on conductivity was measured for the thin films and the corresponding conduction processes are discussed in this work.

  18. Extra phase noise from thermal fluctuations in nonlinear optical crystals

    DEFF Research Database (Denmark)

    César, J. E. S.; Coelho, A.S.; Cassemiro, K.N.

    2009-01-01

    We show theoretically and experimentally that scattered light by thermal phonons inside a second-order nonlinear crystal is the source of additional phase noise observed in optical parametric oscillators. This additional phase noise reduces the quantum correlations and has hitherto hindered the d...

  19. Electrical excitation and optical detection of ultrasounds in PZT based piezoelectric transducers

    Energy Technology Data Exchange (ETDEWEB)

    Babilotte, P; Diallo, O; Hue, L-P Tran Hu; Feuillard, G [University Francois Rabelais de Tours, Laboratory Imaging and Brain, Team Ultrasonic Characterisation and Piezoelectricity, ENIVL, Rue de la Chocolaterie, 41034 BLOIS CEDEX (France); Kosec, M; Kuscer, D, E-mail: philippe.babilotte@univ-tours.fr [Josef Stefan Institute, Jamova cesta 39, 1000 LJUBLJANA (Slovenia)

    2011-01-01

    The displacement response of piezoelectric PZT thick films fabricated by means of electrophoretic deposition and laid down an alumina substrate is investigated using coherent optical detection. According to thickness properties determined by electrical impedance measurements, the film presents a resonance around 40 MHz. Other resonance peaks are observed that correspond to eigen modes of the film substrate couple structure. Uniformity of the response of the integrated structure is studied across the surface of the sample when excited by either a continuous or impulse electrical voltage. Results on the amplitude of the detected signal versus the frequency and the input excitation voltage are reported. The optical detection used in these experiments is complementary to conventional techniques of characterization of piezoelectric devices such as electrical impedance measurements and allows getting information on the displacement response of the device.

  20. Thermal and Electrical Investigation of Conductive Polylactic Acid Based Filaments

    Science.gov (United States)

    Dobre, R. A.; Marcu, A. E.; Drumea, A.; Vlădescu, M.

    2018-06-01

    Printed electronics gain momentum as the involved technologies become affordable. The ability to shape electrostatic dissipative materials in almost any form is useful. The idea to use a general-purpose 3D printer to manufacture the electrical interconnections for a circuit is very attractive. The advantage of using a 3D printed structure over other technologies are mainly the lower price, less requirements concerning storage and use conditions, and the capability to build thicker traces while maintaining flexibility. The main element allowing this to happen is a printing filament with conductive properties. The paper shows the experiments that were performed to determine the thermal and electrical properties of polylactic acid (PLA) based ESD dissipative filament. Quantitative results regarding the thermal behavior of the DC resistance and the variation of the equivalent parallel impedance model parameters (losses resistance, capacitance, impedance magnitude and phase angle) with frequency are shown.. Using these results, new applications like printed temperature sensors can be imagined.

  1. Optical and thermal energy discharge from tritiated solid hydrogen

    International Nuclear Information System (INIS)

    Magnotta, F.; Mapoles, E.R.; Collins, G.W.; Souers, P.C.

    1991-01-01

    The authors are investigating mechanisms of energy storage and release in tritiated solid hydrogens, by a variety of techniques including ESR, NMR and thermal and optical emission. The nuclear decay of a triton in solid hydrogen initiates the conversion of nuclear energy into stored chemical energy by producing unpaired hydrogen atoms which are trapped within the molecular lattice. The ability to store large quantities of atoms in this manner has been demonstrated and can serve as a basis for new forms of high energy density materials. This paper presents preliminary results of a study of the optical emission from solid hydrogen containing tritium over the visible and near infrared (NIR) spectral regions. Specifically, they have studied optical emission from DT and T 2 using CCD, silicon diode and germanium diode arrays. 8 refs., 6 figs

  2. Thermal design of an electric motor using Particle Swarm Optimization

    International Nuclear Information System (INIS)

    Jandaud, P-O; Harmand, S; Fakes, M

    2012-01-01

    In this paper, flow inside an electric machine called starter-alternator is studied parametrically with CFD in order to be used by a thermal lumped model coupled to an optimization algorithm using Particle Swarm Optimization (PSO). In a first case, the geometrical parameters are symmetric allowing us to model only one side of the machine. The optimized thermal results are not conclusive. In a second case, all the parameters are independent. In this case, the flow is strongly influenced by the dissymmetry. Optimization results are this time a clear improvement compared to the original machine.

  3. Mathematical modeling of thermal runaway in semiconductor laser operation

    NARCIS (Netherlands)

    Smith, W.R.

    2000-01-01

    A mathematical model describing the coupling of electrical, optical and thermal effects in semiconductor lasers is introduced. Through a systematic asymptotic expansion, the governing system of differential equations is reduced to a single second-order boundary value problem. This highly nonlinear

  4. The performance of residential micro-cogeneration coupled with thermal and electrical storage

    Science.gov (United States)

    Kopf, John

    Over 80% of residential secondary energy consumption in Canada and Ontario is used for space and water heating. The peak electricity demands resulting from residential energy consumption increase the reliance on fossil-fuel generation stations. Distributed energy resources can help to decrease the reliance on central generation stations. Presently, distributed energy resources such as solar photovoltaic, wind and bio-mass generation are subsidized in Ontario. Micro-cogeneration is an emerging technology that can be implemented as a distributed energy resource within residential or commercial buildings. Micro-cogeneration has the potential to reduce a building's energy consumption by simultaneously generating thermal and electrical power on-site. The coupling of a micro-cogeneration device with electrical storage can improve the system's ability to reduce peak electricity demands. The performance potential of micro-cogeneration devices has yet to be fully realized. This research addresses the performance of a residential micro-cogeneration device and it's ability to meet peak occupant electrical loads when coupled with electrical storage. An integrated building energy model was developed of a residential micro-cogeneration system: the house, the micro-cogeneration device, all balance of plant and space heating components, a thermal storage device, an electrical storage device, as well as the occupant electrical and hot water demands. This model simulated the performance of a micro-cogeneration device coupled to an electrical storage system within a Canadian household. A customized controller was created in ESP-r to examine the impact of various system control strategies. The economic performance of the system was assessed from the perspective of a local energy distribution company and an end-user under hypothetical electricity export purchase price scenarios. It was found that with certain control strategies the micro-cogeneration system was able to improve the

  5. Electron-Beam Produced Air Plasma: Optical and Electrical Diagnostics

    Science.gov (United States)

    Vidmar, Robert; Stalder, Kenneth; Seeley, Megan

    2006-10-01

    High energy electron impact excitation is used to stimulate optical emissions that quantify the measurement of electron beam current. A 100 keV 10-ma electron beam source is used to produce air plasma in a test cell at a pressure between 1 mTorr and 760 Torr. Optical emissions originating from the N2 2^nd positive line at 337.1 nm and the N2^+ 1^st negative line at 391.4 nm are observed. Details on calibration using signals from an isolated transmission window and a Faraday plate are discussed. Results using this technique and other electrical signal are presented.

  6. High efficiency thermal to electric energy conversion using selective emitters and spectrally tuned solar cells

    Science.gov (United States)

    Chubb, Donald L.; Flood, Dennis J.; Lowe, Roland A.

    1992-01-01

    Thermophotovoltaic (TPV) systems are attractive possibilities for direct thermal-to-electric energy conversion, but have typically required the use of black body radiators operating at high temperatures. Recent advances in both the understanding and performance of solid rare-earth oxide selective emitters make possible the use of TPV at temperatures as low as 1500 K. Depending on the nature of parasitic losses, overall thermal-to-electric conversion efficiencies greater than 20 percent are feasible.

  7. Integrated fiber optical and thermal sensor for noninvasive monitoring of blood and human tissue

    Science.gov (United States)

    Saetchnikov, Vladimir A.; Tcherniavskaia, Elina A.; Schiffner, Gerhard

    2007-05-01

    A novel concept of noninvasive monitoring of human tissue and blood based on optical diffuse reflective spectroscopy combined with metabolic heat measurements has been under development. A compact integrated fiber optical and thermal sensor has been developed. The idea of the method was to evaluate by optical spectroscopy haemoglobin and derivative concentrations and supplement with data associated with the oxidative metabolism of glucose. Body heat generated by glucose oxidation is based on the balance of capillary glucose and oxygen supply to the cells. The variation in glucose concentration is followed also by a difference from a distance (or depth) of scattered through the body radiation. So, blood glucose can be estimated by measuring the body heat and the oxygen supply. The sensor pickup contains of halogen lamp and LEDs combined with fiber optical bundle to deliver optical radiation inside and through the patient body, optical and thermal detectors. Fiber optical probe allows diffuse scattering measurement down to a depth of 2.5 mm in the skin including vascular system, which contributes to the control of the body temperature. The sensor pickup measures thermal generation, heat balance, blood flow rate, haemoglobin and derivative concentrations, environmental conditions. Multivariate statistical analysis was applied to convert various signals from the sensor pickup into physicochemical variables. By comparing the values from the noninvasive measurement with the venous plasma result, analytical functions for patient were obtained. Cluster analysis of patient groups was used to simplify a calibration procedure. Clinical testing of developed sensor is being performed.

  8. Printed optically transparent graphene cellulose electrodes

    Science.gov (United States)

    Sinar, Dogan; Knopf, George K.; Nikumb, Suwas; Andrushchenko, Anatoly

    2016-02-01

    Optically transparent electrodes are a key component in variety of products including bioelectronics, touch screens, flexible displays, low emissivity windows, and photovoltaic cells. Although highly conductive indium tin oxide (ITO) films are often used in these electrode applications, the raw material is very expensive and the electrodes often fracture when mechanically stressed. An alternative low-cost material for inkjet printing transparent electrodes on glass and flexible polymer substrates is described in this paper. The water based ink is created by using a hydrophilic cellulose derivative, carboxymethyl cellulose (CMC), to help suspend the naturally hydrophobic graphene (G) sheets in a solvent composed of 70% DI water and 30% 2-butoxyethanol. The CMC chain has hydrophobic and hydrophilic functional sites which allow adsorption on G sheets and, therefore, permit the graphene to be stabilized in water by electrostatic and steric forces. Once deposited on the functionalized substrate the electrical conductivity of the printed films can be "tuned" by decomposing the cellulose stabilizer using thermal reduction. The entire electrode can be thermally reduced in an oven or portions of the electrode thermally modified using a laser annealing process. The thermal process can reduce the sheet resistance of G-CMC films to < 100 Ω/sq. Experimental studies show that the optical transmittance and sheet resistance of the G-CMC conductive electrode is a dependent on the film thickness (ie. superimposed printed layers). The printed electrodes have also been doped with AuCl3 to increase electrical conductivity without significantly increasing film thickness and, thereby, maintain high optical transparency.

  9. Effect of carrier doping and external electric field on the optical properties of graphene quantum dots

    Science.gov (United States)

    Basak, Tista; Basak, Tushima

    2018-02-01

    In this paper, we demonstrate that the optical properties of finite-sized graphene quantum dots can be effectively controlled by doping it with different types of charge carriers (electron/hole). In addition, the role played by a suitably directed external electric field on the optical absorption of charge-doped graphene quantum dots have also been elucidated. The computations have been performed on diamond-shaped graphene quantum dot (DQD) within the framework of the Pariser-Parr-Pople (PPP) model Hamiltonian, which takes into account long-range Coulomb interactions. Our results reveal that the energy band-gap increases when the DQD is doped with holes while it decreases on doping it with electrons. Further, the optical absorption spectra of DQD exhibits red/blue-shift on doping with electrons/holes. Our computations also indicate that the application of external transverse electric field results in a substantial blue-shift of the optical spectrum for charge-doped DQD. However, it is observed that the influence of charge-doping is more prominent in tuning the optical properties of finite-sized graphene quantum dots as compared to externally applied electric field. Thus, tailoring the optical properties of finite-sized graphene quantum dots by manipulative doping with charge carriers and suitably aligned external electric field can greatly enhance its potential application in designing nano-photonic devices.

  10. Tailoring of the electrical and thermal properties using ultra-short period non-symmetric superlattices

    Directory of Open Access Journals (Sweden)

    Paulina Komar

    2016-10-01

    Full Text Available Thermoelectric modules based on half-Heusler compounds offer a cheap and clean way to create eco-friendly electrical energy from waste heat. Here we study the impact of the period composition on the electrical and thermal properties in non-symmetric superlattices, where the ratio of components varies according to (TiNiSnn:(HfNiSn6−n, and 0 ⩽ n ⩽ 6 unit cells. The thermal conductivity (κ showed a strong dependence on the material content achieving a minimum value for n = 3, whereas the highest value of the figure of merit ZT was achieved for n = 4. The measured κ can be well modeled using non-symmetric strain relaxation applied to the model of the series of thermal resistances.

  11. Dosimetry based on thermally and optically stimulated luminescence

    International Nuclear Information System (INIS)

    Agersnap Larsen, Niels

    1999-01-01

    Thermally Stimulated Luminescence (TL) and Optically Stimulated Luminescence (OSL) properties of quartz and α-Al 2 O 3 have been investigated. Anneling-induced OSL and TL sensitivity changes in quartz has been investigated by experiments and modelling. This study does not support a pre-dose effect to account for the observed annealing-induced sensitivity change. The experimental data indicates a more simple mechanism that involves alteration of the concentration of the defect centers. Results from modelling of removal or creation of defect centers comparing well with experimentally obtained data. Thermal quenching of luminescence for the main emission center, the F-center, in α-Al 2 O 3 :C has been investigated by analysing TL curves obtained at different heating rates. The thermal quenching dependence of luminescence is found to follow the classical Mott-Seitz expression. Basic investigations of OSL properties of αAl 2 O 3 :C, including: the thermal depth of the OSL traps, the temperature dependence of OSL, and the OSL stimulation spectra. Simultaneous measurements of TL and thermally stimulated conductivity (TSC) are presented for γ-irradiated αAl 2 O 3 :C. Activation energy analysis of the data reveals a superposition of several first-order TL and TSC peaks caused by release of charge carriers from a distribution of trapping states. Furthermore a description of an experimental method developed to determine the sign of the thermally released charge carriers has been presented. (au)

  12. Dispersed solar thermal generation employing parabolic dish-electric transport with field modulated generator systems

    Science.gov (United States)

    Ramakumar, R.; Bahrami, K.

    1981-01-01

    This paper discusses the application of field modulated generator systems (FMGS) to dispersed solar-thermal-electric generation from a parabolic dish field with electric transport. Each solar generation unit is rated at 15 kWe and the power generated by an array of such units is electrically collected for insertion into an existing utility grid. Such an approach appears to be most suitable when the heat engine rotational speeds are high (greater than 6000 r/min) and, in particular, if they are operated in the variable speed mode and if utility-grade a.c. is required for direct insertion into the grid without an intermediate electric energy storage and reconversion system. Predictions of overall efficiencies based on conservative efficiency figures for the FMGS are in the range of 25 per cent and should be encouraging to those involved in the development of cost-effective dispersed solar thermal power systems.

  13. High-precision thermal and electrical characterization of thermoelectric modules

    Science.gov (United States)

    Kolodner, Paul

    2014-05-01

    This paper describes an apparatus for performing high-precision electrical and thermal characterization of thermoelectric modules (TEMs). The apparatus is calibrated for operation between 20 °C and 80 °C and is normally used for measurements of heat currents in the range 0-10 W. Precision thermometry based on miniature thermistor probes enables an absolute temperature accuracy of better than 0.010 °C. The use of vacuum isolation, thermal guarding, and radiation shielding, augmented by a careful accounting of stray heat leaks and uncertainties, allows the heat current through the TEM under test to be determined with a precision of a few mW. The fractional precision of all measured parameters is approximately 0.1%.

  14. Simultaneous high crystallinity and sub-bandgap optical absorptance in hyperdoped black silicon using nanosecond laser annealing

    Energy Technology Data Exchange (ETDEWEB)

    Franta, Benjamin, E-mail: bafranta@gmail.com; Pastor, David; Gandhi, Hemi H.; Aziz, Michael J.; Mazur, Eric [School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138 (United States); Rekemeyer, Paul H.; Gradečak, Silvija [Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

    2015-12-14

    Hyperdoped black silicon fabricated with femtosecond laser irradiation has attracted interest for applications in infrared photodetectors and intermediate band photovoltaics due to its sub-bandgap optical absorptance and light-trapping surface. However, hyperdoped black silicon typically has an amorphous and polyphasic polycrystalline surface that can interfere with carrier transport, electrical rectification, and intermediate band formation. Past studies have used thermal annealing to obtain high crystallinity in hyperdoped black silicon, but thermal annealing causes a deactivation of the sub-bandgap optical absorptance. In this study, nanosecond laser annealing is used to obtain high crystallinity and remove pressure-induced phases in hyperdoped black silicon while maintaining high sub-bandgap optical absorptance and a light-trapping surface morphology. Furthermore, it is shown that nanosecond laser annealing reactivates the sub-bandgap optical absorptance of hyperdoped black silicon after deactivation by thermal annealing. Thermal annealing and nanosecond laser annealing can be combined in sequence to fabricate hyperdoped black silicon that simultaneously shows high crystallinity, high above-bandgap and sub-bandgap absorptance, and a rectifying electrical homojunction. Such nanosecond laser annealing could potentially be applied to non-equilibrium material systems beyond hyperdoped black silicon.

  15. Tuning the Electronic, Optical, and Magnetic Properties of Monolayer GaSe with a Vertical Electric Field

    Science.gov (United States)

    Ke, Congming; Wu, Yaping; Guo, Guang-Yu; Lin, Wei; Wu, Zhiming; Zhou, Changjie; Kang, Junyong

    2018-04-01

    Inspired by two-dimensional material with their unique physical properties and innovative device applications, here we report a design framework on monolayer GaSe, an important member of the two-dimensional material family, in an effort to tune the electronic, optical, and magnetic properties through a vertical electric field. A transition from indirect to direct band gap in monolayer GaSe is found with an electric field of 0.09 V /Å . The giant Stark effect results in a reduction of the band gap with a Stark coefficient of 3.54 Å. Optical and dielectric properties of monolayer GaSe are dependent on the vertical electric field. A large regulation range for polarization E ∥c ^ is found for the static dielectric constant. The optical anisotropy with the dipole transition from E ∥c ^ to E ⊥c ^ is achieved. Induced by the spin-orbit coupling, spin-splitting energy at the valence band maximum increases linearly with the electric field. The effective mass of holes is highly susceptible to the vertical electric field. Switchable spin-polarization features in spin texture of monolayer GaSe are predicted. The tunable electronic, optical, and magnetic properties of monolayer GaSe hold great promise for applications in both the optoelectronic and spintronic devices.

  16. The Thermal Electrical Conductivity Probe (TECP) for Phoenix

    Science.gov (United States)

    Zent, Aaron P.; Hecht, Michael H.; Cobos, Doug R.; Campbell, Gaylon S.; Campbell, Colin S.; Cardell, Greg; Foote, Marc C.; Wood, Stephen E.; Mehta, Manish

    2009-01-01

    The Thermal and Electrical Conductivity Probe (TECP) is a component of the Microscopy, Electrochemistry, and Conductivity Analyzer (MECA) payload on the Phoenix Lander. TECP will measure the temperature, thermal conductivity and volumetric heat capacity of the regolith. It will also detect and quantify the population of mobile H2O molecules in the regolith, if any, throughout the polar summer, by measuring the electrical conductivity of the regolith, as well as the dielectric permittivity. In the vapor phase, TECP is capable of measuring the atmospheric H2O vapor abundance, as well as augment the wind velocity measurements from the meteorology instrumentation. TECP is mounted near the end of the 2.3 m Robotic Arm, and can be placed either in the regolith material or held aloft in the atmosphere. This paper describes the development and calibration of the TECP. In addition, substantial characterization of the instrument has been conducted to identify behavioral characteristics that might affect landed surface operations. The greatest potential issue identified in characterization tests is the extraordinary sensitivity of the TECP to placement. Small gaps alter the contact between the TECP and regolith, complicating data interpretation. Testing with the Phoenix Robotic Arm identified mitigation techniques that will be implemented during flight. A flight model of the instrument was also field tested in the Antarctic Dry Valleys during the 2007-2008 International Polar year. 2

  17. Technological drivers in data centers and telecom systems: Multiscale thermal, electrical, and energy management

    International Nuclear Information System (INIS)

    Garimella, Suresh V.; Persoons, Tim; Weibel, Justin; Yeh, Lian-Tuu

    2013-01-01

    Highlights: ► Thermal management approaches reviewed against energy usage of IT industry. ► Challenges of energy efficiency in large-scale electronic systems highlighted. ► Underlying drivers for progress at the business and technology levels identified. ► Thermal, electrical and energy management challenges discussed as drivers. ► Views of IT system operators, manufacturers and integrators represented. - Abstract: We identify technological drivers for tomorrow’s data centers and telecommunications systems, including thermal, electrical and energy management challenges, based on discussions at the 2nd Workshop on Thermal Management in Telecommunication Systems and Data Centers in Santa Clara, California, on April 25–26, 2012. The relevance of thermal management in electronic systems is reviewed against the background of the energy usage of the information technology (IT) industry, encompassing perspectives of different sectors of the industry. The underlying drivers for progress at the business and technology levels are identified. The technological challenges are reviewed in two main categories – immediate needs and future needs. Enabling cooling techniques that are currently under development are also discussed

  18. Electrically Insulated Sensing of Respiratory Rate and Heartbeat Using Optical Fibers

    Directory of Open Access Journals (Sweden)

    Ernesto Suaste-Gómez

    2014-11-01

    Full Text Available Respiratory and heart rates are among the most important physiological parameters used to monitor patients’ health. It is important to design devices that can measure these parameters without risking or altering the subject’s health. In this context, a novel sensing method to monitor simultaneously the heartbeat and respiratory rate signals of patients within an electrically safety environment was developed and tested. An optical fiber-based sensor was used in order to detect two optical phenomena. Photo-plethysmography and the relation between bending radius and attenuation of optical fiber were coupled through a single beam light traveling along this fiber.

  19. Novel gas sensor with dual response under CO(g) exposure: Optical and electrical stimuli

    Science.gov (United States)

    Rocha, L. S. R.; Cilense, M.; Ponce, M. A.; Aldao, C. M.; Oliveira, L. L.; Longo, E.; Simoes, A. Z.

    2018-05-01

    In this work, a lanthanum (La) doped ceria (CeO2) film, which depicted a dual gas sensing response (electric and optical) for CO(g) detection, was obtained by the microwave-assisted hydrothermal (HAM) synthesis and deposited by the screen-printing technique, in order to prevent deaths by intoxication with this life-threatening gas. An electric response under CO(g) exposure was obtained, along with an extremely fast optical response for a temperature of 380 °C, associated with Ce+4 reduction and vacancy generation. A direct optical gap was found to be around 2.31 eV from UV-Vis results, which corresponds to a transition from valence band to 4f states. Due to the anomalous electron configuration of cerium atoms with 4f electrons in its reduced state, they are likely to present an electric conduction based on the small polaron theory with a hopping mechanism responsible for its dual sensing response with a complete reversible behaviour.

  20. Influence of ion beam irradiation induced defects on the structural, optical and electrical properties of tellurium nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Narinder [Department of Physics, Chaudhary Devi Lal University, Sirsa, 125055 (India); Department of Physics, Haryana College of Technology & Management, Kaithal, 136027 (India); Kumar, Rajesh [Department of Physics, RN College of Engineering & Technology, Madlauda, 132104 (India); Kumar, Sushil, E-mail: sushil_phys@rediffmail.com [Department of Physics, Chaudhary Devi Lal University, Sirsa, 125055 (India); Chakarvarti, S.K. [Research and Development, Manav Rachana International University, Faridabad, 121001 (India)

    2016-11-01

    In this study, tellurium nanowires were electrodeposited into the polymer membranes from aqueous acidic bath containing HTeO{sub 2}{sup +} ions. The field emission scanning electron microscopy (FESEM) images confirmed the formation of uniform and straight nanowires. The influence of 110 MeV Ni{sup 8+} ion irradiation induced defects on the structural, optical and electrical properties of as–deposited tellurium nanowires were examined using X-ray diffraction (XRD), UV–visible absorption spectroscopy and current–voltage (I–V) measurements. The XRD data depicted the hexagonal phase of tellurium nanowires and further revealed a variation in the intensity of diffraction peaks of ion irradiated nanowires. Williamson–Hall (WH) analysis is used for convoluting the size and microstrain contributions to the width of diffraction peaks. Tellurium nanowires exhibited a distinct absorbance band in the visible region at 686 nm, while this was absent in bulk tellurium. Electrical properties of nanowires are explored on the basis of I–V curves, which revealed a significant increase in the electrical conductivity of irradiated nanowires. A possible mechanism for the enhanced electrical conductivity is the increase in carrier concentration due to thermally excited defects. The defects produced by ion irradiation play a vital role in modifying the properties of semiconducting nanowires. - Highlights: • 110 MeV Ni{sup 8+} ion beam induced changes in tellurium nanowires have been examined. • Nanowires were prepared using template electrodeposition method. • Irradiation improved the electrical conductivity of tellurium nanowires. • Mechanism for enhanced electrical conductivity of irradiated nanowires was discussed.

  1. Combination of optical spectroscopy and electrical impedancemetry for nutrition behavior characterizations

    Science.gov (United States)

    Perchik, Alexey; Pavlov, Konstantin; Vilenskii, Maksim; Popov, Mikhail

    2017-07-01

    Unhealthy nutrition trends determination technique is described. Combination of optical spectroscopy and electrical impedancemetry will lead to development of a healthcare device that will predict unhealthy eating habits and decrease risk factors of diseases development.

  2. Study on thermal electric conversion system for FBR plant. Investigation for effective EVST waste heat recovery system

    International Nuclear Information System (INIS)

    Maekawa, Isamu; Kurata, Chikatoshi

    2004-02-01

    Recently, it has been important to reuse discharged heat energy from present nuclear plant, especially from sodium cooled FBR, which are typical high temperature system, in the view of reduction of environmental burden and improvement of heat efficiency for plant. The thermal electric conversion system can work only the temperature difference and has been applied to the limited fields such as space or military, however, that results show good merits for reliability, maintenance free, and so on. Recently, the development of new thermal electric conversion elements has made remarkable progress. In this study, for the effective utilization of waste heat from Monju', the prototype plant of FBR, we made an investigation of electric power generating system maintaining the cooling faculty by applying the thermal electric conversion system to sodium cooling line of EVST. Using the new type iron based thermal electric conversion elements, which are plentiful, economical and good for environmental harmonization, we have calculated the amount of heat exchange and power generation from sodium cooling line of EVST, and have investigated the module sizing, cost and subject to be settled. The results were , (1)The amount of power generation from sodium cooling line of EVST is smaller about one figure than motive power of sodium cooler fan. However, if Seebeck coefficient and heat conductivity of iron based thermal electric conversion elements shall be improved, power from sodium cooling line shall be able to cover the motive power. (2) The amount of heat released from sodium cooling line after the installation of thermal electric conversion module covers the necessity to maintain the sodium cooling faculty. (3) In case of the installation of module to the sodium cooler, it should be reconstructed because of tube arrangement modification. In case of the installation of module to the sodium connecting line, air ventilation system is needed to suppress the room temperature. (4) As

  3. Localization of thermal anomalies in electrical equipment using Infrared Thermography and support vector machine

    Science.gov (United States)

    Laib dit Leksir, Y.; Mansour, M.; Moussaoui, A.

    2018-03-01

    Analysis and processing of databases obtained from infrared thermal inspections made on electrical installations require the development of new tools to obtain more information to visual inspections. Consequently, methods based on the capture of thermal images show a great potential and are increasingly employed in this field. However, there is a need for the development of effective techniques to analyse these databases in order to extract significant information relating to the state of the infrastructures. This paper presents a technique explaining how this approach can be implemented and proposes a system that can help to detect faults in thermal images of electrical installations. The proposed method classifies and identifies the region of interest (ROI). The identification is conducted using support vector machine (SVM) algorithm. The aim here is to capture the faults that exist in electrical equipments during an inspection of some machines using A40 FLIR camera. After that, binarization techniques are employed to select the region of interest. Later the comparative analysis of the obtained misclassification errors using the proposed method with Fuzzy c means and Ostu, has also be addressed.

  4. Studies on dielectric properties, opto-electrical parameters and electronic polarizability of thermally evaporated amorphous Cd{sub 50}S{sub 50−x}Se{sub x} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Hassanien, Ahmed Saeed, E-mail: a.s.hassanien@gmail.com [Engineering Mathematics and Physics Department, Faculty of Engineering (Shoubra), Benha University (Egypt); Physics Department, Faculty of Science and Humanities in Ad-Dawadmi, Shaqra University, 11911 (Saudi Arabia)

    2016-06-25

    The objective of this work is to study the influence of the addition of more Se on dielectric properties, opto-electrical parameters and electronic polarizability of amorphous chalcogenide Cd{sub 50}S{sub 50−x}Se{sub x} thin films (30 ≤ x ≤ 50 at%). Thin films of thickness 200 nm were synthesized by vacuum deposition at ≈8.2 × 10{sup −4} Pa. Both refractive index and extinction coefficient were used to obtain all the studied parameters. The high frequency dielectric constant, real and imaginary parts of dielectric constant were discussed. Drude theory was applied to investigate opto-electrical parameters, like optical carrier concentration, optical mobility and optical resistivity. Moreover, other parameters were investigated and studied, e.g. Drude parameters, volume and surface energy loss functions, dielectric loss factor, dielectric relaxation time, complex optical conductivity and electronic polarizability as well as optical electronegativity and third-order nonlinear optical susceptibility. Values of electronic polarizability and nonlinear optical susceptibility were found to be decreased while optical electronegativity increased as Se-content was increased. Increment of Se-content in amorphous Cd{sub 50}S{sub 50−x}Se{sub x} thin films has also led to minimize the energy losses when electromagnetic waves propagate through films as well as optical conductivity and the speed of light increased. The other studied properties and parameters of Cd{sub 50}S{sub 50−x}Se{sub x} films were found to be strongly dependent upon Se-content. - Highlights: • Thermally evaporated amorphous Cd{sub 50}S{sub 50−x}Se{sub x} (30 ≤ x ≤ 50) thin films were deposited. • Refractive index and absorption index were used to determine almost all properties. • Dielectric properties, Drude parameters and electronic polarizability were studied. • Addition of more Se to CdSSe matrix led to improve the opto-electrical properties. • New data were obtained and

  5. Hydrogen-induced electrical and optical switching in Pd capped Pr ...

    Indian Academy of Sciences (India)

    Wintec

    Abstract. In this study, modification in the properties of hydrogen-induced switchable mirror based on Pr nanoparticle layers is reported. The reversible changes in hydrogen-induced electrical and optical properties of Pd capped Pr nanoparticle layers have been studied as a function of hydrogenation time and compared.

  6. Modeling of Thermal Phase Noise in a Solid Core Photonic Crystal Fiber-Optic Gyroscope.

    Science.gov (United States)

    Song, Ningfang; Ma, Kun; Jin, Jing; Teng, Fei; Cai, Wei

    2017-10-26

    A theoretical model of the thermal phase noise in a square-wave modulated solid core photonic crystal fiber-optic gyroscope has been established, and then verified by measurements. The results demonstrate a good agreement between theory and experiment. The contribution of the thermal phase noise to the random walk coefficient of the gyroscope is derived. A fiber coil with 2.8 km length is used in the experimental solid core photonic crystal fiber-optic gyroscope, showing a random walk coefficient of 9.25 × 10 -5 deg/√h.

  7. The effect of the optical system on the electrical performance of III–V concentrator triple junction solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Schultz, R.D., E-mail: S206029578@nmmu.ac.za; Dyk, E.E. van; Vorster, F.J.

    2016-01-01

    High Concentrated Photovoltaic (H-CPV) technologies utilize relatively inexpensive reflective and refractive optical components for concentration to achieve high energy yield. The electrical performance of H-CPV systems is, however, dependent on the properties and configuration of the optical components. The focus of this paper is to summarize the effect of the properties of the optical system on the electrical performance of a Concentrator Triple Junction (CTJ) InGaP/InGaAs/Ge cell. Utilizing carefully designed experiments that include spectral measurements and intensity profiles in the optical plane of the CTJ cell, the influence of photon absorption, Fresnel lens properties and chromatic aberration created by the optical system on the electrical performance of a CTJ cell is shown. From the results obtained, it is concluded that good characterization and understanding of the optical system’s properties may add to improved design of future multi-junction devices.

  8. Sparse Reconstruction for Temperature Distribution Using DTS Fiber Optic Sensors with Applications in Electrical Generator Stator Monitoring

    Science.gov (United States)

    Bazzo, João Paulo; Pipa, Daniel Rodrigues; da Silva, Erlon Vagner; Martelli, Cicero; Cardozo da Silva, Jean Carlos

    2016-01-01

    This paper presents an image reconstruction method to monitor the temperature distribution of electric generator stators. The main objective is to identify insulation failures that may arise as hotspots in the structure. The method is based on temperature readings of fiber optic distributed sensors (DTS) and a sparse reconstruction algorithm. Thermal images of the structure are formed by appropriately combining atoms of a dictionary of hotspots, which was constructed by finite element simulation with a multi-physical model. Due to difficulties for reproducing insulation faults in real stator structure, experimental tests were performed using a prototype similar to the real structure. The results demonstrate the ability of the proposed method to reconstruct images of hotspots with dimensions down to 15 cm, representing a resolution gain of up to six times when compared to the DTS spatial resolution. In addition, satisfactory results were also obtained to detect hotspots with only 5 cm. The application of the proposed algorithm for thermal imaging of generator stators can contribute to the identification of insulation faults in early stages, thereby avoiding catastrophic damage to the structure. PMID:27618040

  9. Electric field manipulation in Al/CdTe/Pt detectors under optical perturbations

    Energy Technology Data Exchange (ETDEWEB)

    Turturici, A.A. [Dipartimento di Fisica e Chimica, Università di Palermo, Viale delle Scienze, Edificio 18, Palermo 90128 (Italy); Franc, J.; Grill, R.; Dědič, V. [Institute of Physics of Charles University, MFF, Ke Karlovu 5, Prague 2 (Czech Republic); Abbene, L., E-mail: leonardo.abbene@unipa.it [Dipartimento di Fisica e Chimica, Università di Palermo, Viale delle Scienze, Edificio 18, Palermo 90128 (Italy); Principato, F. [Dipartimento di Fisica e Chimica, Università di Palermo, Viale delle Scienze, Edificio 18, Palermo 90128 (Italy)

    2017-06-21

    Al/CdTe/Pt detectors are very attractive devices for high-resolution X-ray spectroscopy, even though they suffer from polarization phenomena, which cause a progressive time degradation of the spectroscopic performance. In this work we investigated on the time dependence of the electric field of an Al/CdTe/Pt detector under optical perturbation by means of Pockels effect measurements. A tunable laser with wavelengths ranging within 700−1000 nm and a 940 nm light emitting diode (LED) were used. The measurements of both the electric field profile and the total current were used to better understand the effects of the optical perturbation on polarization phenomena. The results point out as the above band-gap light, due to the trapping of photo-generated holes at the anode (the Al/CdTe blocking contact), brings to a reduction of the negative space charge caused by the bias voltage (bias induced polarization) and the LED irradiation (radiation induced polarization). The reduction of the negative space charge ensures a quite stable and uniform electric field distribution, typically termed depolarization. Conversely, optical perturbation with sub-band-gap light enhances the polarization with the formation of two oppositely charged regions within the detector.

  10. Study of thermal treatments and irradiation on natural amethyst by optical absorption

    International Nuclear Information System (INIS)

    Dotto, C.T.

    1987-01-01

    Thermal treatment effects on the samples of amethyst from Minas Gerais and Rio Grande do Sul, through optical absorption measurements, are studied. The effects of cobalt 60 gama ray radiation on the amethyst from Minas Gerais through optical absorption measurements, are studied. The optical absorption spectra shows a basic line and bands in 10,500 cm -1 (k), in 18,300 cm -1 (θ) and in 28,000 cm -1 (ζ). The correlation between thermal treatment effects and radiation effects shows that the θ and ζ bands belongs to a same center and the k band to another center. The basic line vanishes by thermal treatments at 270 0 C. The analyses of the isothermal treatment decay and dose-curve reveal a complex kinetics, suggesting that the kinetic mechanisms involve the electron (s) and hole (s) migration in the lattice. The amethyst from Minas Gerais after being discolored at 470 0 C and irradiated again shows that the optical absorption bands don't recover the original absorbance, suggesting the existence of iron diffusion mechanisms in the lattice. After being isothermally annealed the amethyst from Rio Grande do Sul above 400 0 C temperature yield a yellow-brown color, probably due to the formation of Fe 2 O 3 precipitate. We suggest the this formation is due to iron diffusion and pre-existent oxygen vacancies. This model is reinforced through the observation the amethyst from Minas Gerais, isothermally treated at 470 0 C in highly reducing, also gets a yellow-brown color. (author) [pt

  11. Electrical and optical properties of CZTS thin films prepared by SILAR method

    Directory of Open Access Journals (Sweden)

    J. Henry

    2016-03-01

    Full Text Available In the present work, Cu2ZnSnS4 (CZTS thin film was deposited onto the glass substrate by simple and economic SILAR method and its structural, morphological, optical and electrical properties were analyzed. X-ray diffraction (XRD analysis confirms the formation of CZTS with kesterite structure and the average crystallite size is found to be 142 nm. Scanning electron microscope (SEM image shows that the film has homogeneous, agglomerated surface without any cracks. The prepared CZTS film shows good optical absorption (104 cm−1 in the visible region and the optical band gap energy is found to be quite close to the optimum value of about 1.54 eV for solar cell application. The refractive index of the prepared film is found to be 2.85. The electrical resistivity of the film is found to be ∼10−2 Ω cm at room temperature.

  12. Airborne Thematic Thermal InfraRed and Electro-Optical Imaging System, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — The innovation is an advanced Airborne Thematic Thermal InfraRed and Electro-Optical Imaging System (ATTIREOIS). ATTIREOIS sensor payload consists of two sets of...

  13. Dielectric optical antenna thermal emitters and metamaterials

    Science.gov (United States)

    Schuller, Jonathan Aaron

    Optical antennas are critical components in nanophotonics research due to their unparalleled ability to concentrate electromagnetic energy into nanoscale volumes. Researchers typically construct such antennas from wavelength-size metallic structures. However, recent research has begun to exploit the scattering resonances of high-permittivity particles to realize all-dielectric optical antennas, emitters, and metamaterials. In this thesis, we experimentally and theoretically characterize the resonant modes of subwavelength rod-shaped dielectric particles and demonstrate their use in negative index metamaterials and novel infrared light emitters. At mid-infrared frequencies, Silicon Carbide (SiC) is an ideal system for studying the behavior of dielectric optical antennas. At frequencies below the TO phonon resonance, SiC behaves like a dielectric with very large refractive index. Using infrared spectroscopy and analytical Mie calculations we show that individual rod-shaped SiC particles exhibit a multitude of resonant modes. Detailed investigations of these SiC optical antennas reveal a wealth of new physics and applications. We discuss the distinct electromagnetic field profile for each mode, and demonstrate that two of the dielectric-type Mie resonances can be combined in a particle array to form a negative index metamaterial. We further show that these particles can serve as "broadcasting" antennas. Using a custom-built thermal emission microscope we collect emissivity spectra from single SiC particles at elevated temperatures, highlighting their use as subwavelength resonant light emitters. Finally, we derive and verify a variety of general analytical results applicable to all cylindrical dielectric antennas.

  14. Simultaneous Thermal and Gamma Radiation Aging of Electrical Cable Polymers

    Energy Technology Data Exchange (ETDEWEB)

    Fifield, Leonard S.

    2018-04-11

    The polymers used for insulation in nuclear power plant electrical cables are susceptible to aging during long term operation. Elevated temperature is the primary contributor to changes in polymer structure that result loss of mechanical and electrical properties, but gamma radiation is also a significant source of degradation for polymers used within relevant plant locations. Despite many years of polymer degradation research, the combined effects of simultaneous exposure to thermal and radiation stress are not well understood. As nuclear operators contemplate and prepare for extended operations beyond initial license periods, a predictive understanding of exposure-based cable material degradation is becoming an increasingly important input to safety, licensing, operations and economic decisions. We are focusing on carefully-controlled simultaneous thermal and gamma radiation accelerating aging and characterization of the most common nuclear cable polymers to understand the relative contributions of temperature, time, dose and dose rate to changes in cable polymer material structure and properties. Improved understanding of cable performance in long term operation will help support continued sustainable nuclear power generation.

  15. Thermal conductivities of thin, sputtered optical films

    International Nuclear Information System (INIS)

    Henager, C.H. Jr.; Pawlewicz, W.T.

    1991-05-01

    The normal component of the thin film thermal conductivity has been measured for the first time for several advanced sputtered optical materials. Included are data for single layers of boron nitride (BN), aluminum nitride (AIN), silicon aluminum nitride (Si-Al-N), silicon aluminum oxynitride (Si-Al-O-N), silicon carbide (SiC), and for dielectric-enhanced metal reflectors of the form Al(SiO 2 /Si 3 N 4 ) n and Al(Al 2 O 3 /AIN) n . Sputtered films of more conventional materials like SiO 2 , Al 2 O 3 , Ta 2 O 5 , Ti, and Si have also been measured. The data show that thin film thermal conductivities are typically 10 to 100 times lower than conductivities for the same materials in bulk form. Structural disorder in the amorphous or very fine-grained films appears to account for most of the conductivity difference. Conclusive evidence for a film/substrate interface contribution is presented

  16. Structural, morphological and optical properties of thermal annealed TiO thin films

    International Nuclear Information System (INIS)

    Zribi, M.; Kanzari, M.; Rezig, B.

    2008-01-01

    Structural, morphological and optical properties of TiO thin films grown by single source thermal evaporation method were studied. The films were annealed from 300 to 520 deg. C in air after evaporation. Qualitative film analysis was performed with X-ray diffraction, atomic force microscopy and optical transmittance and reflectance spectra. A correlation was established between the optical properties, surface roughness and growth morphology of the evaporated TiO thin films. The X-ray diffraction spectra indicated the presence of the TiO 2 phase for the annealing temperature above 400 deg. C

  17. Thermal Management and Reliability of Automotive Power Electronics and Electric Machines

    Energy Technology Data Exchange (ETDEWEB)

    Narumanchi, Sreekant V [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Bennion, Kevin S [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Cousineau, Justine E [National Renewable Energy Laboratory (NREL), Golden, CO (United States); DeVoto, Douglas J [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Feng, Xuhui [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Kekelia, Bidzina [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Kozak, Joseph P [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Major, Joshua [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Moreno, Gilberto [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Paret, Paul P [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Tomerlin, Jeff J [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

    2018-02-09

    Low-cost, high-performance thermal management technologies are helping meet aggressive power density, specific power, cost, and reliability targets for power electronics and electric machines. The National Renewable Energy Laboratory is working closely with numerous industry and research partners to help influence development of components that meet aggressive performance and cost targets through development and characterization of cooling technologies, and thermal characterization and improvements of passive stack materials and interfaces. Thermomechanical reliability and lifetime estimation models are important enablers for industry in cost-and time-effective design.

  18. Integrated energy and advanced thermal management system for hybrid electric vehicles

    NARCIS (Netherlands)

    Wei, C.

    2017-01-01

    Hybrid electric vehicles (HEVs) featuring a fuel source engine and an energy storage source battery play an important role in improving fuel efficiency compared with its conventional counterparts. In view of the drawbacks of the existing research neglecting the thermal aspects when it comes to

  19. Optical properties of electrically connected plasmonic nanoantenna dimer arrays

    Science.gov (United States)

    Zimmerman, Darin T.; Borst, Benjamin D.; Carrick, Cassandra J.; Lent, Joseph M.; Wambold, Raymond A.; Weisel, Gary J.; Willis, Brian G.

    2018-02-01

    We fabricate electrically connected gold nanoantenna arrays of homodimers and heterodimers on silica substrates and present a systematic study of their optical properties. Electrically connected arrays of plasmonic nanoantennas make possible the realization of novel photonic devices, including optical sensors and rectifiers. Although the plasmonic response of unconnected arrays has been studied extensively, the present study shows that the inclusion of nanowire connections modifies the device response significantly. After presenting experimental measurements of optical extinction for unconnected dimer arrays, we compare these to measurements of dimers that are interconnected by gold nanowire "busbars." The connected devices show the familiar dipole response associated with the unconnected dimers but also show a second localized surface plasmon resonance (LSPR) that we refer to as the "coupled-busbar mode." Our experimental study also demonstrates that the placement of the nanowire along the antenna modifies the LSPR. Using finite-difference time-domain simulations, we confirm the experimental results and investigate the variation of dimer gap and spacing. Changing the dimer gap in connected devices has a significantly smaller effect on the dipole response than it does in unconnected devices. On the other hand, both LSPR modes respond strongly to changing the spacing between devices in the direction along the interconnecting wires. We also give results for the variation of E-field strength in the dimer gap, which will be important for any working sensor or rectenna device.

  20. Combined Optical and Electrical Spectrum Shaping for High-Baud-Rate Nyquist-WDM Transceivers

    DEFF Research Database (Denmark)

    Porto da Silva, Edson; Borkowski, Robert; Preussler, Stefan

    2016-01-01

    bandwidth is related to the optical comb parameters 25 and the pulse shaping of the modulating waveforms in the electrical domain. Such de- 26 pendence may result in broadening of the modulated spectra, which can degrade the 27 performance of Nyquist-WDM systems due to interchannel crosstalk penalties....... To investigate the benefits of the proposed approach, we demonstrate 32 the first WDM Nyquist-OTDM signal generation based on the periodic train of sinc pulses 33 and electrical spectrum shaping. Straight line transmission of five 112.5-Gbd Nyquist- 34 OTDM dual-polarization quadrature phase-shift keying (QPSK......We discuss the benefits and limitations of optical time-division multiplexing 22 (OTDM) techniques based on the optical generation of a periodic train of sinc pulses for 23 wavelength-division multiplexing (WDM) transmission at high baud rates. It is shown 24 how the modulated OTDM spectrum...

  1. Dosimetry based on thermally and optically stimulated luminescence

    Energy Technology Data Exchange (ETDEWEB)

    Agersnap Larsen, Niels

    1999-01-01

    Thermally Stimulated Luminescence (TL) and Optically Stimulated Luminescence (OSL) properties of quartz and {alpha}-Al{sub 2}O{sub 3} have been investigated. Anneling-induced OSL and TL sensitivity changes in quartz has been investigated by experiments and modelling. This study does not support a pre-dose effect to account for the observed annealing-induced sensitivity change. The experimental data indicates a more simple mechanism that involves alteration of the concentration of the defect centers. Results from modelling of removal or creation of defect centers comparing well with experimentally obtained data. Thermal quenching of luminescence for the main emission center, the F-center, in {alpha}-Al{sub 2}O{sub 3}:C has been investigated by analysing TL curves obtained at different heating rates. The thermal quenching dependence of luminescence is found to follow the classical Mott-Seitz expression. Basic investigations of OSL properties of {alpha}Al{sub 2}O{sub 3}:C, including: the thermal depth of the OSL traps, the temperature dependence of OSL, and the OSL stimulation spectra. Simultaneous measurements of TL and thermally stimulated conductivity (TSC) are presented for {gamma}-irradiated {alpha}Al{sub 2}O{sub 3}:C. Activation energy analysis of the data reveals a superposition of several first-order TL and TSC peaks caused by release of charge carriers from a distribution of trapping states. Furthermore a description of an experimental method developed to determine the sign of the thermally released charge carriers has been presented. (au) 8 tabs., 59 ills., 90 refs.

  2. A thermally regenerative ammonia-based battery for efficient harvesting of low-grade thermal energy as electrical power

    KAUST Repository

    Zhang, Fang

    2015-01-01

    © 2015 The Royal Society of Chemistry. Thermal energy was shown to be efficiently converted into electrical power in a thermally regenerative ammonia-based battery (TRAB) using copper-based redox couples [Cu(NH3)4 2+/Cu and Cu(ii)/Cu]. Ammonia addition to the anolyte (2 M ammonia in a copper-nitrate electrolyte) of a single TRAB cell produced a maximum power density of 115 ± 1 W m-2 (based on projected area of a single copper mesh electrode), with an energy density of 453 W h m-3 (normalized to the total electrolyte volume, under maximum power production conditions). Adding a second cell doubled both the voltage and maximum power. Increasing the anolyte ammonia concentration to 3 M further improved the maximum power density to 136 ± 3 W m-2. Volatilization of ammonia from the spent anolyte by heating (simulating distillation), and re-addition of this ammonia to the spent catholyte chamber with subsequent operation of this chamber as the anode (to regenerate copper on the other electrode), produced a maximum power density of 60 ± 3 W m-2, with an average discharge energy efficiency of ∼29% (electrical energy captured versus chemical energy in the starting solutions). Power was restored to 126 ± 5 W m-2 through acid addition to the regenerated catholyte to decrease pH and dissolve Cu(OH)2 precipitates, suggesting that an inexpensive acid or a waste acid could be used to improve performance. These results demonstrated that TRABs using ammonia-based electrolytes and inexpensive copper electrodes can provide a practical method for efficient conversion of low-grade thermal energy into electricity.

  3. Thermal conduction properties of Mo/Si multilayers for extreme ultraviolet optics

    Science.gov (United States)

    Bozorg-Grayeli, Elah; Li, Zijian; Asheghi, Mehdi; Delgado, Gil; Pokrovsky, Alexander; Panzer, Matthew; Wack, Daniel; Goodson, Kenneth E.

    2012-10-01

    Extreme ultraviolet (EUV) lithography requires nanostructured optical components, whose reliability can be influenced by radiation absorption and thermal conduction. Thermal conduction analysis is complicated by sub-continuum electron and phonon transport and the lack of thermal property data. This paper measures and interprets thermal property data, and their evolution due to heating exposure, for Mo/Si EUV mirrors with 6.9 nm period and Mo/Si thickness ratios of 0.4/0.6 and 0.6/0.4. We use time-domain thermoreflectance and the 3ω method to estimate the thermal resistance between the Ru capping layer and the Mo/Si multilayers (RRu-Mo/Si = 1.5 m2 K GW-1), as well as the out-of-plane thermal conductivity (kMo/Si 1.1 W m-1 K-1) and thermal anisotropy (η = 13). This work also reports the impact of annealing on thermal conduction in a co-deposited MoSi2 layer, increasing the thermal conductivity from 1.7 W m-1 K-1 in the amorphous phase to 2.8 W m-1 K-1 in the crystalline phase.

  4. Large format lithium ion pouch cell full thermal characterisation for improved electric vehicle thermal management

    Science.gov (United States)

    Grandjean, Thomas; Barai, Anup; Hosseinzadeh, Elham; Guo, Yue; McGordon, Andrew; Marco, James

    2017-08-01

    It is crucial to maintain temperature homogeneity in lithium ion batteries in order to prevent adverse voltage distributions and differential ageing within the cell. As such, the thermal behaviour of a large-format 20 Ah lithium iron phosphate pouch cell is investigated over a wide range of ambient temperatures and C rates during both charging and discharging. Whilst previous studies have only considered one surface, this article presents experimental results, which characterise both surfaces of the cell exposed to similar thermal media and boundary conditions, allowing for thermal gradients in-plane and perpendicular to the stack to be quantified. Temperature gradients, caused by self-heating, are found to increase with increasing C rate and decreasing temperature to such an extent that 13.4 ± 0.7% capacity can be extracted using a 10C discharge compared to a 0.5C discharge, both at -10 °C ambient temperature. The former condition causes an 18.8 ± 1.1 °C in plane gradient and a 19.7 ± 0.8 °C thermal gradient perpendicular to the stack, which results in large current density distributions and local state of charge differences within the cell. The implications of these thermal and electrical inhomogeneities on ageing and battery pack design for the automotive industry are discussed.

  5. Thermal modelling of the calorimeter used for energy measurement of LMJ laser pulse

    Directory of Open Access Journals (Sweden)

    Crespy C.

    2013-11-01

    Full Text Available In this work, a 3D thermal model of the LMJ calorimeter is developed using Comsol multiphysics. The unknown thermal properties of the system are identified by comparing the model results with the measured temperature. Several model's applications, such as comparing deposition modes (electrical and optical or defining calibration procedure, are presented.

  6. Influence of substrate temperature on the optical and electrical properties magnetron sputtering ITO films

    International Nuclear Information System (INIS)

    Khripunov, G.S.; Yurchenko, G.V.

    1999-01-01

    Electrical and optical properties of ITO films obtained at substrate temperature from 200 degree C to 500 degree C by magnetron sputtering of target 95% In 2 O 3 - 5% SnO 2 were studied. It was shown that the ITO film obtained at the substrate temperature 300 i N have optimum combination of the optical and electrical characteristics: resistivity 2.1 centre dot 10 -4 Ω cm, transmittance in visible spectral range about 88% at the thickness film 0.61 μ, factor of quality reaches 8.2 centre dot 10 -2 Ω 1

  7. Manipulation of local optical properties and structures in molybdenum-disulfide monolayers using electric field-assisted near-field techniques.

    Science.gov (United States)

    Nozaki, Junji; Fukumura, Musashi; Aoki, Takaaki; Maniwa, Yutaka; Yomogida, Yohei; Yanagi, Kazuhiro

    2017-04-05

    Remarkable optical properties, such as quantum light emission and large optical nonlinearity, have been observed in peculiar local sites of transition metal dichalcogenide monolayers, and the ability to tune such properties is of great importance for their optoelectronic applications. For that purpose, it is crucial to elucidate and tune their local optical properties simultaneously. Here, we develop an electric field-assisted near-field technique. Using this technique we can clarify and tune the local optical properties simultaneously with a spatial resolution of approximately 100 nm due to the electric field from the cantilever. The photoluminescence at local sites in molybdenum-disulfide (MoS 2 ) monolayers is reversibly modulated, and the inhomogeneity of the charge neutral points and quantum yields is suggested. We successfully etch MoS 2 crystals and fabricate nanoribbons using near-field techniques in combination with an electric field. This study creates a way to tune the local optical properties and to freely design the structural shapes of atomic monolayers using near-field optics.

  8. Optical pulling and pushing forces exerted on silicon nanospheres with strong coherent interaction between electric and magnetic resonances.

    Science.gov (United States)

    Liu, Hongfeng; Panmai, Mingcheng; Peng, Yuanyuan; Lan, Sheng

    2017-05-29

    We investigated theoretically and numerically the optical pulling and pushing forces acting on silicon (Si) nanospheres (NSs) with strong coherent interaction between electric and magnetic resonances. We examined the optical pulling and pushing forces exerted on Si NSs by two interfering waves and revealed the underlying physical mechanism from the viewpoint of electric- and magnetic-dipole manipulation. As compared with a polystyrene (PS) NS, it was found that the optical pulling force for a Si NS with the same size is enlarged by nearly two orders of magnitude. In addition to the optical pulling force appearing at the long-wavelength side of the magnetic dipole resonance, very large optical pushing force is observed at the magnetic quadrupole resonance. The correlation between the optical pulling/pushing force and the directional scattering characterized by the ratio of the forward to backward scattering was revealed. More interestingly, it was found that the high-order electric and magnetic resonances in large Si NSs play an important role in producing optical pulling force which can be generated by not only s-polarized wave but also p-polarized one. Our finding indicates that the strong coherent interaction between the electric and magnetic resonances existing in nanoparticles with large refractive indices can be exploited to manipulate the optical force acting on them and the correlation between the optical force and the directional scattering can be used as guidance. The engineering and manipulation of optical forces will find potential applications in the trapping, transport and sorting of nanoparticles.

  9. The Effect of Deposition Rate on Electrical, Optical and Structural Properties of ITO Thin Films

    Directory of Open Access Journals (Sweden)

    P. S. Raghupathi

    2005-01-01

    Full Text Available Indium tin oxide (ITO thin films have been prepared using the reactive evaporation technique on glass substrates in an oxygen atmosphere. It is found that the deposition rate plays prominent role in controlling the electrical and optical properties of the ITO thin films. Resistivity, electrical conductivity, activation energy, optical transmission and band gap energy were investigated. A transmittance value of more than 90% in the visible region of the spectrum and an electrical conductivity of 3x10–6 Ωm has been obtained with a deposition rate of 2 nm/min. XRD studies showed that the films are polycrystalline.

  10. Study of the effect of the deposition parameters on the structural, electric and optical characteristics of polymorphous silicon films prepared by low frequency PECVD

    Energy Technology Data Exchange (ETDEWEB)

    Moreno, M., E-mail: mmoreno@inaoep.mx [Instituto Nacional de Astrofisica, Optica y Electronica, INAOE, Puebla (Mexico); Torres, A. [Instituto Nacional de Astrofisica, Optica y Electronica, INAOE, Puebla (Mexico); Ambrosio, R. [Universidad Autonoma de Ciudad Juarez, Electrical Deparment, Chihuahua (Mexico); Zuniga, C.; Torres-Rios, A.; Monfil, K.; Rosales, P.; Itzmoyotl, A. [Instituto Nacional de Astrofisica, Optica y Electronica, INAOE, Puebla (Mexico)

    2011-10-25

    In this work we present our results on the deposition and characterization of polymorphous silicon (pm-Si:H) films prepared by low frequency plasma enhanced chemical vapor deposition (LF-PECVD). We have studied the effect of the plasma deposition parameters (as the chamber pressure and gas flow rates of SiH{sub 4} and H{sub 2}) on the structural, electric, and optical characteristics of the films. The temperature dependence of conductivity ({sigma}(T)), activation energy (E{sub a}), optical band gap (E{sub g}) and deposition rate (V{sub d}) were extracted for pm-Si:H films deposited at different pressure values and different gas flow rates. We observed that the chamber pressure is an important parameter that has a significant effect on the electric characteristics, and as well on the morphology of the pm-Si:H films (deduced from atomic force microscopy). It was found an optimal pressure range, in order to produce pm-Si:H films with high E{sub a} and room temperature conductivity, {sigma}{sub RT}, which are key parameters for thermal detection applications.

  11. Study of the effect of the deposition parameters on the structural, electric and optical characteristics of polymorphous silicon films prepared by low frequency PECVD

    International Nuclear Information System (INIS)

    Moreno, M.; Torres, A.; Ambrosio, R.; Zuniga, C.; Torres-Rios, A.; Monfil, K.; Rosales, P.; Itzmoyotl, A.

    2011-01-01

    In this work we present our results on the deposition and characterization of polymorphous silicon (pm-Si:H) films prepared by low frequency plasma enhanced chemical vapor deposition (LF-PECVD). We have studied the effect of the plasma deposition parameters (as the chamber pressure and gas flow rates of SiH 4 and H 2 ) on the structural, electric, and optical characteristics of the films. The temperature dependence of conductivity (σ(T)), activation energy (E a ), optical band gap (E g ) and deposition rate (V d ) were extracted for pm-Si:H films deposited at different pressure values and different gas flow rates. We observed that the chamber pressure is an important parameter that has a significant effect on the electric characteristics, and as well on the morphology of the pm-Si:H films (deduced from atomic force microscopy). It was found an optimal pressure range, in order to produce pm-Si:H films with high E a and room temperature conductivity, σ RT , which are key parameters for thermal detection applications.

  12. Modification of optical and electrical properties of chemical bath deposited CdS using plasma treatments

    International Nuclear Information System (INIS)

    Gonzalez, G.; Krishnan, B.; Avellaneda, D.; Castillo, G. Alan; Das Roy, T.K.; Shaji, S.

    2011-01-01

    Cadmium sulphide (CdS) is a well known n-type semiconductor that is widely used in solar cells. Here we report preparation and characterization of chemical bath deposited CdS thin films and modification of their optical and electrical properties using plasma treatments. CdS thin films were prepared from a chemical bath containing Cadmium chloride, Triethanolamine and Thiourea under various deposition conditions. Good quality thin films were obtained during deposition times of 5, 10 and 15 min. CdS thin films prepared for 10 min. were treated using a glow discharge plasma having nitrogen and argon carrier gases. The changes in morphology, optical and electrical properties of these plasma treated CdS thin films were analyzed in detail. The results obtained show that plasma treatment is an effective technique in modification of the optical and electrical properties of chemical bath deposited CdS thin films.

  13. Modification of optical and electrical properties of chemical bath deposited CdS using plasma treatments

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez, G. [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, San Nicolas de los Garza, Nuevo Leon, C.P 66450 (Mexico); Krishnan, B. [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, San Nicolas de los Garza, Nuevo Leon, C.P 66450 (Mexico); CIIDIT, Universidad Autonoma de Nuevo Leon, Apodaca, Nuevo Leon (Mexico); Avellaneda, D.; Castillo, G. Alan; Das Roy, T.K. [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, San Nicolas de los Garza, Nuevo Leon, C.P 66450 (Mexico); Shaji, S., E-mail: sshajis@yahoo.com [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, San Nicolas de los Garza, Nuevo Leon, C.P 66450 (Mexico); CIIDIT, Universidad Autonoma de Nuevo Leon, Apodaca, Nuevo Leon (Mexico)

    2011-08-31

    Cadmium sulphide (CdS) is a well known n-type semiconductor that is widely used in solar cells. Here we report preparation and characterization of chemical bath deposited CdS thin films and modification of their optical and electrical properties using plasma treatments. CdS thin films were prepared from a chemical bath containing Cadmium chloride, Triethanolamine and Thiourea under various deposition conditions. Good quality thin films were obtained during deposition times of 5, 10 and 15 min. CdS thin films prepared for 10 min. were treated using a glow discharge plasma having nitrogen and argon carrier gases. The changes in morphology, optical and electrical properties of these plasma treated CdS thin films were analyzed in detail. The results obtained show that plasma treatment is an effective technique in modification of the optical and electrical properties of chemical bath deposited CdS thin films.

  14. Anisotropic electrical, thermal and magnetic properties of Al{sub 13}Ru{sub 4} decagonal quasicrystalline approximant

    Energy Technology Data Exchange (ETDEWEB)

    Wencka, Magdalena [Polish Academy of Sciences, Poznan (Poland). Inst. of Molecular Physics; Vrtnik, Stanislav; Kozelj, Primoz; Dolinsek, Janez [Ljubljana Univ. (Slovenia). Faculty of Mathematics and Physics; Jozef Stefan Institute, Ljubljana (Slovenia); Jaglicic, Zvonko [Ljubljana Univ. (Slovenia). Inst. of Mathematics, Physics and Mechanics; Gille, Peter [Muenchen Univ. (Germany). Crystallography Section

    2017-09-01

    We present measurements of the anisotropic electrical and thermal transport coefficients (the electrical resistivity, the thermoelectric power, the thermal conductivity), the magnetization and the specific heat of the Al{sub 13}Ru{sub 4} monoclinic approximant to the decagonal quasicrystal, in comparison to the isostructural Al{sub 13}Fe{sub 4}. The electrical and thermal transport parameters of Al{sub 13}Ru{sub 4} were found to exhibit significant anisotropy, qualitatively similar to that found previously in the Al{sub 13}Fe{sub 4} (P. Popcevic, et al., Phys. Rev. B 2010, 81, 184203). The crystallographic b direction, corresponding to the stacking direction of the (a,c) atomic planes, is the most conducting direction for the electricity and heat. The thermopower is strongly anisotropic with a complicated temperature dependence, exhibiting maxima, minima, crossovers and sign change. The electronic density of states (DOS) at the Fermi energy is reduced to 35% of the DOS of Al metal. The magnetic susceptibility is diamagnetic and the diamagnetism is by a factor of 2 stronger for the magnetic field along the stacking b direction.

  15. Effects of simulated nuclear thermal pulses on fiber optic cables

    International Nuclear Information System (INIS)

    Baba, A.J.; Share, S.; Wasilik, J.H.

    1979-01-01

    The effects of pulsed thermal radiation on fiber optic cables with a variety of jackets (polyurethane, PVC, fluorocarbon) are presented. Exposure between 27 and 85 cal/cm 2 did not sever the optical fibers, but the radiation did cause disintegration of the jackets and the Kevlar strength members, which resulted in a significant reduction of the cable's ability to survive mechanical stress. Hardening techniques are discussed. The addition of low absorptance materials (white Teflon tape and aluminum foil) under clear or white Teflon jackets prevented some types of cables from being affected at fluences up to 110 cal/cm 2

  16. Critical success factors for BOT electric power projects in China: Thermal power versus wind power

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Zhen-Yu. [School of Business Administration, North China Electric Power University, Beijing 102206 (China); Zuo, Jian; Zillante, George [School of Natural and Built Environments, University of South Australia, Adelaide 5001 (Australia); Wang, Xin-Wei [Shandong Nuclear Power Equipment Manufacturing Co. Ltd, Haiyang, Shandong 265118 (China)

    2010-06-15

    Chinese electric power industry has adopted Build-Operate-Transfer (BOT) approach in a number of projects to alleviate the pressure of sole state-owned investment. The Chinese government has taken enormous efforts to create an environment to facilitate the application of BOT approach in electric power projects. Moreover, the growing attention on the sustainability issues puts the traditional major source of electricity - thermal power project under more strict scrutiny. As a result, various renewable energy projects, particularly the wind power projects have involved private sector funds. Both thermal power and wind power projects via BOT approach have met with a varying degree of success. Therefore, it is imperative to understand the factors contributing towards the success of both types of BOT power projects. Using an extensive literature survey, this paper identifies 31 success factors under 5 categories for Chinese BOT electric power projects. This is followed by a questionnaire survey to exam relative significance of these factors. The results reveal the different levels of significance of success factors for BOT thermal power projects versus wind power projects. Finally, survey results were analyzed to explore the underlying construction and distributions among the identified success factors. This study provides a valuable reference for all involved parties that are interested in developing BOT electric power projects in China. (author)

  17. Optical and thermal response of single-walled carbon nanotube–copper sulfide nanoparticle hybrid nanomaterials

    International Nuclear Information System (INIS)

    Tseng, Yi-Hsuan; He Yuan; Que Long; Lakshmanan, Santana; Yang Chang; Chen Wei

    2012-01-01

    This paper reports the optical and thermal response of a single-walled carbon nanotube–copper sulfide nanoparticle (SWNT–CuS NP) hybrid nanomaterial and its application as a thermoelectric generator. The hybrid nanomaterial was synthesized using oleylamine molecules as the linker molecules between SWNTs and CuS NPs. Measurements found that the hybrid nanomaterial has significantly increased light absorption (up to 80%) compared to the pure SWNT. Measurements also found that the hybrid nanomaterial thin-film devices exhibit a clear optical and thermal switching effect, which can be further enhanced up to 10 × by asymmetric illumination of light and thermal radiation on the thin-film devices instead of symmetric illumination. A simple prototype thermoelectric generator enabled by the hybrid nanomaterials is demonstrated, indicating a new route for achieving thermoelectricity. (paper)

  18. Integration and Validation of a Thermal Energy Storage System for Electric Vehicle Cabin Heating

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Mingyu [MAHLE Behr Troy Inc.; Craig, Timothy [MAHLE Behr Troy Inc.; Wolfe, Edward [MAHLE Behr Troy Inc.; LaClair, Tim J. [ORNL; Gao, Zhiming [ORNL; Levin, Michael [Ford Motor Company; Demitroff, Danrich [Ford Motor Company; Shaikh, Furqan [Ford Motor Company

    2017-03-01

    It is widely recognized in the automotive industry that, in very cold climatic conditions, the driving range of an Electric Vehicle (EV) can be reduced by 50% or more. In an effort to minimize the EV range penalty, a novel thermal energy storage system has been designed to provide cabin heating in EVs and Plug-in Hybrid Electric Vehicles (PHEVs) by using an advanced phase change material (PCM). This system is known as the Electrical PCM-based Thermal Heating System (ePATHS) [1, 2]. When the EV is connected to the electric grid to charge its traction battery, the ePATHS system is also “charged” with thermal energy. The stored heat is subsequently deployed for cabin comfort heating during driving, for example during commuting to and from work.The ePATHS system, especially the PCM heat exchanger component, has gone through substantial redesign in order to meet functionality and commercialization requirements. The final system development for EV implementation has occurred on a mid-range EV and has been evaluated for its capability to extend the driving range. Both simulated driving in a climatic tunnel and actual road testing have been carried out. The ePATHS has demonstrated its ability to supply the entire cabin heating needs for a round trip commute totaling 46 minutes, including 8 hours of parking, at an ambient temperature of -10°C.

  19. Optical and Electric Multifunctional CMOS Image Sensors for On-Chip Biosensing Applications

    Directory of Open Access Journals (Sweden)

    Kiyotaka Sasagawa

    2010-12-01

    Full Text Available In this review, the concept, design, performance, and a functional demonstration of multifunctional complementary metal-oxide-semiconductor (CMOS image sensors dedicated to on-chip biosensing applications are described. We developed a sensor architecture that allows flexible configuration of a sensing pixel array consisting of optical and electric sensing pixels, and designed multifunctional CMOS image sensors that can sense light intensity and electric potential or apply a voltage to an on-chip measurement target. We describe the sensors’ architecture on the basis of the type of electric measurement or imaging functionalities.

  20. Effect of substrate temperature on structural, optical and electrical properties of pulsed laser ablated nanostructured indium oxide films

    International Nuclear Information System (INIS)

    Beena, D.; Lethy, K.J.; Vinodkumar, R.; Mahadevan Pillai, V.P.; Ganesan, V.; Phase, D.M.; Sudheer, S.K.

    2009-01-01

    Nanocrystalline indium oxide (INO) films are deposited in a back ground oxygen pressure at 0.02 mbar on quartz substrates at different substrate temperatures (T s ) ranging from 300 to 573 K using pulsed laser deposition technique. The films are characterized using GIXRD, XPS, AFM and UV-visible spectroscopy to study the effect of substrate temperature on the structural and optical properties of films. The XRD patterns suggest that the films deposited at room temperature are amorphous in nature and the crystalline nature of the films increases with increase in substrate temperature. Films prepared at T s ≥ 473 K are polycrystalline in nature (cubic phase). Crystalline grain size calculation based on Debye Scherrer formula indicates that the particle size enhances with the increase in substrate temperature. Lattice constant of the films are calculated from the XRD data. XPS studies suggest that all the INO films consist of both crystalline and amorphous phases. XPS results show an increase in oxygen content with increase in substrate temperature and reveals that the films deposited at higher substrate temperatures exhibit better stoichiometry. The thickness measurements using interferometric techniques show that the film thickness decreases with increase in substrate temperature. Analysis of the optical transmittance data of the films shows a blue shift in the values of optical band gap energy for the films compared to that of the bulk material owing to the quantum confinement effect due to the presence of quantum dots in the films. Refractive index and porosity of the films are also investigated. Room temperature DC electrical measurements shows that the INO films investigated are having relatively high electrical resistivity in the range of 0.80-1.90 Ωm. Low temperature electrical conductivity measurements in the temperature range of 50-300 K for the film deposited at 300 K give a linear Arrhenius plot suggesting thermally activated conduction. Surface

  1. Novel thermal annealing methodology for permanent tuning polymer optical fiber Bragg gratings to longer wavelengths.

    Science.gov (United States)

    Pospori, A; Marques, C A F; Sagias, G; Lamela-Rivera, H; Webb, D J

    2018-01-22

    The Bragg wavelength of a polymer optical fiber Bragg grating can be permanently shifted by utilizing the thermal annealing method. In all the reported fiber annealing cases, the authors were able to tune the Bragg wavelength only to shorter wavelengths, since the polymer fiber shrinks in length during the annealing process. This article demonstrates a novel thermal annealing methodology for permanently tuning polymer optical fiber Bragg gratings to any desirable spectral position, including longer wavelengths. Stretching the polymer optical fiber during the annealing process, the period of Bragg grating, which is directly related with the Bragg wavelength, can become permanently longer. The methodology presented in this article can be used to multiplex polymer optical fiber Bragg gratings at any desirable spectral position utilizing only one phase-mask for their photo-inscription, reducing thus their fabrication cost in an industrial setting.

  2. Controlling Lateral Fano Interference Optical Force with Au-Ge2Sb2Te5 Hybrid Nanostructure

    DEFF Research Database (Denmark)

    Cao, Tun; Bao, Jiaxin; Mao, Libang

    2016-01-01

    is revealed through optical singularity in the Poynting vector. A thermal-electric simulation is adopted to investigate the temporal change of the Ge2Sb2Te5 film's temperature, which demonstrates the possibility of transiting the Ge2Sb2Te5 state by electrical heating. Our mechanism by tailoring the DQ...... in flexible nanomechanical control and may provide a new means of biomedical sensing and nano -optical conveyor belts....

  3. Optical and electrical properties of structured multilayer with tunable transparency rate

    International Nuclear Information System (INIS)

    Bou, Adrien; Torchio, Philippe; Barakel, Damien; Guillou, Aurélie; Thoulon, Pierre-Yves; Ricci, Marc; Ayachi, Boubakeur

    2015-01-01

    An experimental study has been carried out on structured multilayer with tunable transparency rate. In this paper, we present the optical and electrical characterization of an oxide | metal | oxide structured electrode manufactured by e-beam deposition and patterned by a lift-off process. The obtained samples are made of grids with different geometrical parameters that lead to varying surface coverage rate on glass. The electrical and optical parameters of SnO x |Ag|SnO x grids are investigated to determine the efficiency, sustainability and limitations of such structures. A linear relationship between the transmittance of the electrodes and the increase of the surface coverage rate is obtained. Coupled to an optimization process, we are able to define a high transparency in a chosen spectral range. Electrical results show a relative stability of the resistivity from 2.9   ×   10   −  4  Ω.cm for an as-grown electrode to 5.6   ×   10   −  4  Ω.cm for a structured electrode with a surface coverage rate of 59%. (paper)

  4. Precision optical systems for the control and measurement of electric power

    International Nuclear Information System (INIS)

    MacKellar, R.

    2000-01-01

    Development od three optical systems for use in the measurement of electric power -- the optical current transducer (NXCT), the optical voltage transducer (NCVT) and the optical voltage and current transducer (NXVCT) -- are discussed. Market for these systems is estimated at $ 600 million and growing, based on the aging infrastructure, the effects of deregulation and application in other market areas. Some competing products by other developers are also described, along with some discussion of the economic advantages to NxtPhase customers in terms of lower acquisition and installation cost, accuracy, and bandwidth. The importance of strategic partnerships and the strengths that strategic partners bring to a enterprise (domain knowledge, access, site for installation, investment capital, critical feedback) are reviewed. Preliminary results of field trials of NxtPhase's NXVCT are also discussed

  5. Preliminary Optical And Electric Field Pulse Statistics From Storm Overflights During The Altus Cumulus Electrification Study

    Science.gov (United States)

    Mach, D. A.; Blakeslee, R. J.; Bailey, J. C.; Farrell, W. M.; Goldberg, R. A.; Desch, M. D.; Houser, J. G.

    2003-01-01

    The Altus Cumulus Electrification Study (ACES) was conducted during the month of August, 2002 in an area near Key West, Florida. One of the goals of this uninhabited aerial vehicle (UAV) study was to collect high resolution optical pulse and electric field data from thunderstorms. During the month long campaign, we acquired 5294 lightning generated optical pulses with associated electric field changes. Most of these observations were made while close to the top of the storms. We found filtered mean and median 10-10% optical pulse widths of 875 and 830 microns respectively while the 50-50% mean and median optical pulse widths are 422 and 365 microns respectively. These values are similar to previous results as are the 10-90% mean and median rise times of 327 and 265 microns. The peak electrical to optical pulse delay mean and median were 209 and 145 microns which is longer than one would expect from theoretical results. The results of the pulse analysis will contribute to further validation of the Optical Transient Detector (OTD) and the Lightning Imaging Sensor (LIS) satellites. Pre-launch estimates of the flash detection efficiency were based on a small sample of optical pulse measurements associated with less than 350 lightning discharges collected by NASA U-2 aircraft in the early 1980s. Preliminary analyses of the ACES measurements show that we have greatly increased the number of optical pulses available for validation of the LIS and other orbital lightning optical sensors. Since the Altus was often close to the cloud tops, many of the optical pulses are from low-energy pulses. From these low-energy pulses, we can determine the fraction of optical lightning pulses below the thresholds of LIS, OTD, and any future satellite-based optical sensors such as the geostationary Lightning Mapping Sensor.

  6. Impedance measurements on a fast transition-edge sensor for optical and near-infrared range

    International Nuclear Information System (INIS)

    Taralli, E; Portesi, C; Lolli, L; Monticone, E; Rajteri, M; Novikov, I; Beyer, J

    2010-01-01

    Impedance measurements of superconducting transition-edge sensors (TESs) are a powerful tool to obtain information about the TES thermal and electrical properties. We apply this technique to a 20 μm x 20 μm Ti/Au TES, suitable for application in the optical and near-infrared range, and extend the measurements up to 250 kHz in order to obtain a complete frequency response in the complex plane. From these measurements we obtain important thermal and electrical device parameters such as heat capacity C, thermal conductance G and effective thermal time constant τ eff that will be compared with the corresponding values obtained from noise measurements.

  7. Optical, electrical and the related parameters of amorphous Ge-Bi-Se thin films

    International Nuclear Information System (INIS)

    El-Korashy, A.; El-Kabany, N.; El-Zahed, H.

    2005-01-01

    The related optical and electrical parameters of amorphous Ge-Bi-Se thin films were studied. The dependence of optical and electrical properties on the Bi content was observed in most compositions. At Bi >10at% the behavior show a switch from p to n type conduction mechanism. The correlation between the optical band gap E g and the average heats of atomization H s were observed. The results indicated that both the number of topological constant N con and the radial and angular N α , N β valence force constants exhibit the same trend with increasing Bi content. On the other hand, the mean bond energy increases with increasing Bi content to x=15at%. It may be concluded that is a function of the mean coordination number N co , the type of bonds, the degree of cross-linking and the band energy forming the network

  8. Interpretation of Simultaneous Mechanical-Electrical-Thermal Failure in a Lithium-Ion Battery Module: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Chao; Santhanagopalan, Shriram; Stock, Mark J.; Brunhart-Lupo, Nicholas; Gruchalla, Kenny

    2016-12-01

    Lithium-ion batteries are currently the state-of- the-art power sources for electric vehicles, and their safety behavior when subjected to abuse, such as a mechanical impact, is of critical concern. A coupled mechanical-electrical-thermal model for simulating the behavior of a lithium-ion battery under a mechanical crush has been developed. We present a series of production-quality visualizations to illustrate the complex mechanical and electrical interactions in this model.

  9. Thermal Effusivity Determination of Metallic Films of Nanometric Thickness by the Electrical Micropulse Method

    Science.gov (United States)

    Lugo, J. M.; Oliva, A. I.

    2017-02-01

    The thermal effusivity of gold, aluminum, and copper thin films of nanometric thickness (20 nm to 200 nm) was investigated in terms of the films' thickness. The metallic thin films were deposited onto glass substrates by thermal evaporation, and the thermal effusivity was estimated by using experimental parameters such as the specific heat, thermal conductivity, and thermal diffusivity values obtained at room conditions. The specific heat, thermal conductivity, and thermal diffusivity values of the metallic thin films are determined with a methodology based on the behavior of the thermal profiles of the films when electrical pulses of few microseconds are applied at room conditions. For all the investigated materials, the thermal effusivity decreases with decreased thickness. The thermal effusivity values estimated by the presented methodology are consistent with other reported values obtained under vacuum conditions and more elaborated methodologies.

  10. Simultaneous topographical, electrical and optical microscopy of optoelectronic devices at the nanoscale

    KAUST Repository

    Kumar, Naresh; Zoladek-Lemanczyk, Alina; Guilbert, Anne A. Y.; Su, Weitao; Tuladhar, Sachetan M.; Kirchartz, Thomas; Schroeder, Bob C.; McCulloch, Iain; Nelson, Jenny; Roy, Debdulal; Castro, Fernando A.

    2017-01-01

    resolution by combining plasmonic optical signal enhancement with electrical-mode scanning probe microscopy. We demonstrate that this combined approach offers subsurface sensitivity that can be exploited to provide molecular information with a nanoscale

  11. Synthesis Al complex and investigating effect of doped ZnO nanoparticles in the electrical and optical efficiency of OLEDS

    Science.gov (United States)

    Shahedi, Zahra; Jafari, Mohammad Reza

    2017-01-01

    In this study, an organometallic complex based on aluminum ions is synthesized. And it is utilized as fluorescent material in the organic light-emitting diodes (OLEDs). The synthesized complex was characterized using XRD, UV-Vis, FT-IR as well as PL spectroscopy analyses. The energy levels of Al complex were determined by cyclic voltammetry measurements. Then, the effects of ZnO nanoparticles (NPs) of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate), PEDOT:PSS, on the electrical and optical performance of the organic light-emitting diodes have been investigated. For this purpose, two samples containing ITO/PEDOT:PSS/PVK/Alq3/PBD/Al with two different concentration and two samples containing ITO/PEDOT:PSS:ZnO/PVK/Alq3/PBD/Al with two different concentration were prepared. Then, hole transport, electron transport and emissive layers were deposited by the spin coating method and the cathode layer (Al) was deposited by the thermal evaporation method. The OLED simulation was also done by constructing the model and choosing appropriate parameters. Then, the experimental data were collected and the results interpreted both qualitatively and quantitatively. The results of the simulations were compared with experimental data of the J-V spectra. Comparing experimental data and simulation results showed that the electrical and optical efficiency of the samples with ZnO NPs is appreciably higher than the samples without ZnO NPs.

  12. Plug-in hybrid electric vehicle LiFePO4 battery life implications of thermal management, driving conditions, and regional climate

    Science.gov (United States)

    Yuksel, Tugce; Litster, Shawn; Viswanathan, Venkatasubramanian; Michalek, Jeremy J.

    2017-01-01

    Battery degradation strongly depends on temperature, and many plug-in electric vehicle applications employ thermal management strategies to extend battery life. The effectiveness of thermal management depends on the design of the thermal management system as well as the battery chemistry, cell and pack design, vehicle system characteristics, and operating conditions. We model a plug-in hybrid electric vehicle with an air-cooled battery pack composed of cylindrical LiFePO4/graphite cells and simulate the effect of thermal management, driving conditions, regional climate, and vehicle system design on battery life. We estimate that in the absence of thermal management, aggressive driving can cut battery life by two thirds; a blended gas/electric-operation control strategy can quadruple battery life relative to an all-electric control strategy; larger battery packs can extend life by an order of magnitude relative to small packs used for all-electric operation; and batteries last 73-94% longer in mild-weather San Francisco than in hot Phoenix. Air cooling can increase battery life by a factor of 1.5-6, depending on regional climate and driving patterns. End of life criteria has a substantial effect on battery life estimates.

  13. On the relationship between satellite-estimated bio-optical and thermal properties in the Gulf of Mexico

    Science.gov (United States)

    Jolliff, Jason K.; Kindle, John C.; Penta, Bradley; Helber, Robert; Lee, Zhongping; Shulman, Igor; Arnone, Robert; Rowley, Clark D.

    2008-03-01

    Three years of Sea-viewing Wide Field-of-view Sensor (SeaWiFS) ocean color data were combined with three-dimensional thermal fields generated by the U.S. Navy's Modular Ocean Data Assimilation System (MODAS) in order to examine the interdependencies between bio-optical fields and their relationship to seasonal and mesoscale changes in upper ocean thermal structure. The combined data set suggests that the oceanic boundary layer within the Gulf of Mexico may be broadly defined by two seasonally occurring bio-thermal periods. A winter mixing period, characterized by net heat losses to the atmosphere, deepening of the isothermal layer depth, and annual maxima of satellite-estimated colored detrital matter (CDM) absorption coefficients and surface pigment concentration, was followed by a thermally stratified period characterized by net surface ocean heating, reduced isothermal layer depths, and annual minima in surface bio-optical fields. Variability in the interdependencies of ocean color products was used to diagnose an attendant shift in the size-structure of surface phytoplankton communities as well as identify CDM as the constituent responsible for the majority of blue-light absorption in Gulf of Mexico surface waters. The mesoscale circulation, as resolved by MODAS thermal fields into cold and warm-core eddies, appears to significantly modulate the seasonal bio-optical cycle of CDM absorption and surface pigment concentration. An empirical model was developed to describe CDM absorption as a function of upper ocean thermal energy. The model accounted for nearly half the variance in the satellite-estimate of this bio-optical variable. Large mismatches between the model and satellite data implied episodes of shelf water export to the deep Gulf of Mexico.

  14. Thin films of molecular materials synthesized from C{sub 32}H{sub 20}N{sub 10}M (M Co, Pb, Fe): Film formation, electrical and optical properties

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez, A. [Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico, A.P. 70-360, Coyoacan, 04510 Mexico, D.F. (Mexico); Sanchez Vergara, M.E., E-mail: elena.sanchez@anahuac.mx [Coordinacion de Ingenieria Mecatronica, Facultad de Ingenieria, Universidad Anahuac del Norte, Avenida Lomas Anahuac 46, Colonia Lomas Anahuac, 52786, Huixquilucan, Estado de Mexico (Mexico); Garcia Montalvo, V. [Instituto de Quimica, Universidad Nacional Autonoma de Mexico, Circuito Exterior, Ciudad Universitaria, 04510 Mexico, D.F. (Mexico); Ortiz, A. [Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico, A.P. 70-360, Coyoacan, 04510 Mexico, D.F. (Mexico); Alvarez, J.R. [Instituto Tecnologico y de Estudios Superiores de Monterrey, Campus Ciudad de Mexico, Calle del Puente 222, Colonia Ejidos de Huipulco, 14380 Mexico, D.F. (Mexico)

    2010-03-15

    In this work, the synthesis of molecular materials formed from metallic phthalocyanines and 1,4-phenylenediamine is reported. The powder and thin film ({approx}80-115 nm thickness) samples of the synthesized materials, deposited by vacuum thermal evaporation, show the same intra-molecular bonds in the IR spectroscopy studies, which suggests that the thermal evaporation process does not alter these bonds. The morphology of the deposited films was studied using scanning electron microscopy (SEM) and atomic force microscopy (AFM) and their optical and electrical properties were studied as well. The optical parameters have been investigated using spectrophotometric measurements of transmittance in the wavelength range 200-1200 nm. The absorption spectra recorded in the UV-vis region for the deposited samples showed two bands, namely the Q and Soret bands. The optical activation energy was calculated and found to be 3.41 eV for the material with cobalt, 3.34 eV for the material including lead and 3.5 eV for the material with iron. The effect of temperature on conductivity was measured for the thin films and the corresponding conduction processes are discussed in this work.

  15. New Methods of Enhancing the Thermal Durability of Silica Optical Fibers.

    Science.gov (United States)

    Wysokiński, Karol; Stańczyk, Tomasz; Gibała, Katarzyna; Tenderenda, Tadeusz; Ziołowicz, Anna; Słowikowski, Mateusz; Broczkowska, Małgorzata; Nasiłowski, Tomasz

    2014-10-13

    Microstructured optical fibers can be precisely tailored for many different applications, out of which sensing has been found to be particularly interesting. However, placing silica optical fiber sensors in harsh environments results in their quick destruction as a result of the hydrolysis process. In this paper, the degradation mechanism of bare and metal-coated optical fibers at high temperatures under longitudinal strain has been determined by detailed analysis of the thermal behavior of silica and metals, like copper and nickel. We furthermore propose a novel method of enhancing the lifetime of optical fibers by the deposition of electroless nickel-phosphorous alloy in a low-temperature chemical process. The best results were obtained for a coating comprising an inner layer of copper and outer layer of low phosphorous nickel. Lifetime values obtained during the annealing experiments were extrapolated to other temperatures by a dedicated model elaborated by the authors. The estimated copper-coated optical fiber lifetime under cycled longitudinal strain reached 31 h at 450 °C.

  16. A Simplified Top-Oil Temperature Model for Transformers Based on the Pathway of Energy Transfer Concept and the Thermal-Electrical Analogy

    Directory of Open Access Journals (Sweden)

    Muhammad Hakirin Roslan

    2017-11-01

    Full Text Available This paper presents an alternative approach to determine the simplified top-oil temperature (TOT based on the pathway of energy transfer and thermal-electrical analogy concepts. The main contribution of this study is the redefinition of the nonlinear thermal resistance based on these concepts. An alternative approximation of convection coefficient, h, based on heat transfer theory was proposed which eliminated the requirement of viscosity. In addition, the lumped capacitance method was applied to the thermal-electrical analogy to derive the TOT thermal equivalent equation in differential form. The TOT thermal model was evaluated based on the measured TOT of seven transformers with either oil natural air natural (ONAN or oil natural air forced (ONAF cooling modes obtained from temperature rise tests. In addition, the performance of the TOT thermal model was tested on step-loading of a transformer with an ONAF cooling mode obtained from previous studies. A comparison between the TOT thermal model and the existing TOT Thermal-Electrical, Exponential (IEC 60076-7, and Clause 7 (IEEE C57.91-1995 models was also carried out. It was found that the measured TOT of seven transformers are well represented by the TOT thermal model where the highest maximum and root mean square (RMS errors are 6.66 °C and 2.76 °C, respectively. Based on the maximum and RMS errors, the TOT thermal model performs better than Exponential and Clause 7 models and it is comparable with the Thermal-Electrical 1 (TE1 and Thermal-Electrical 2 (TE2 models. The same pattern is found for the TOT thermal model under step-loading where the maximum and RMS errors are 5.77 °C and 2.02 °C.

  17. ARE THE VARIATIONS IN QUASAR OPTICAL FLUX DRIVEN BY THERMAL FLUCTUATIONS?

    International Nuclear Information System (INIS)

    Kelly, Brandon C.; Siemiginowska, Aneta; Bechtold, Jill

    2009-01-01

    We analyze a sample of optical light curves for 100 quasars, 70 of which have black hole mass estimates. Our sample is the largest and broadest used yet for modeling quasar variability. The sources in our sample have z 42 ∼ λ (5100 A) ∼ 46 , and 10 6 ∼ BH /M sun ∼ 10 . We model the light curves as a continuous time stochastic process, providing a natural means of estimating the characteristic timescale and amplitude of quasar variations. We employ a Bayesian approach to estimate the characteristic timescale and amplitude of flux variations; our approach is not affected by biases introduced from discrete sampling effects. We find that the characteristic timescales strongly correlate with black hole mass and luminosity, and are consistent with disk orbital or thermal timescales. In addition, the amplitude of short-timescale variations is significantly anticorrelated with black hole mass and luminosity. We interpret the optical flux fluctuations as resulting from thermal fluctuations that are driven by an underlying stochastic process, such as a turbulent magnetic field. In addition, the intranight variations in optical flux implied by our empirical model are ∼<0.02 mag, consistent with current microvariability observations of radio-quiet quasars. Our stochastic model is therefore able to unify both long- and short-timescale optical variations in radio-quiet quasars as resulting from the same underlying process, while radio-loud quasars have an additional variability component that operates on timescales ∼<1 day.

  18. Optical and electrical phenomena in dielectric materials under irradiation

    CERN Document Server

    Plaksin, O A; Stepanov, P A; Demenkov, P V; Chernov, V M; Krutskikh, A O

    2002-01-01

    Optical and acoustic properties of the materials based on Al sub 2 O sub 3 , SiO sub 2 and BN under 8 MeV proton irradiation (<10 sup 4 Gy/s) have been measured. Electric charge partitioning has been shown to result in charging the microscopic regions in the bulk of the dielectrics under irradiation, which is due to different mobility of free electrons and holes (sapphire), concentration inhomogeneity in the system of charge carrier traps (alumina), or thermodynamic instability of the homogeneous distribution of the filled traps (silica glasses). Prevalent charge carrier recombination in the grain boundaries causes re-crystallization of pyrolytic boron nitride under irradiation, which shows up as simultaneous decrease of the intensity of radiation-induced luminescence (RIL) of the centres in the grain boundaries and the BN. The local charging results in optical inhomogeneity of the silica glasses which is sustained by the optical loss spectra of the irradiated glasses, features of kinetics of bleaching, RI...

  19. Structural, optical and electrical characterization of ITO, ITO/Ag and ITO/Ni transparent conductive electrodes

    International Nuclear Information System (INIS)

    Ali, Ahmad Hadi; Shuhaimi, Ahmad; Hassan, Zainuriah

    2014-01-01

    We report on the transparent conductive oxides (TCO) characteristics based on the indium tin oxides (ITO) and ITO/metal thin layer as an electrode for optoelectronics device applications. ITO, ITO/Ag and ITO/Ni were deposited on Si and glass substrate by thermal evaporator and radio frequency (RF) magnetron sputtering at room temperature. Post deposition annealing was performed on the samples in air at moderate temperature of 500 °C and 600 °C. The structural, optical and electrical properties of the ITO and ITO/metal were characterized using X-ray diffraction (XRD), UV–Vis spectrophotometer, Hall effect measurement system and atomic force microscope (AFM). The XRD spectrum reveals significant polycrystalline peaks of ITO (2 2 2) and Ag (1 1 1) after post annealing process. The post annealing also improves the visible light transmittance and electrical resistivity of the samples. Figure of merit (FOM) of the ITO, ITO/Ag and ITO/Ni were determined as 5.5 × 10 −3 Ω −1 , 8.4 × 10 −3 Ω −1 and 3.0 × 10 −5 Ω −1 , respectively. The results show that the post annealed ITO with Ag intermediate layer improved the efficiency of the transparent conductive electrodes (TCE) as compared to the ITO and ITO/Ni.

  20. Study of an electrical heating system with ductless air supply and shape-stabilized PCM for thermal storage

    International Nuclear Information System (INIS)

    Lin, Kunping; Zhang, Yinping; Di, Hongfa; Yang, Rui

    2007-01-01

    A kind of electrical floor heating system with a shape-stabilized phase change material (PCM) which has been studied at Tsinghua University in our previous studies, can provide space heating during the whole day and can be controlled conventionally. However, this is not suitable for office buildings where no space heating is needed at night. The effective control is very important for the heating system in such buildings. In this paper, we studied a kind of new electrical floor heating system with ductless air supply and shape-stabilized PCM for thermal storage in order to overcome the shortcomings of the passive under-floor electric heating system with thermal storage. In this paper, we investigated its thermal performance by experiments and simulation, calculated the effects of various factors and discussed the application feasibility in different climate regions. The results show that the total electrical energy consumption was shifted from the peak period to the off-peak period, which would provide significant economic benefits because of the different day and night electricity tariffs. The system can be designed by choosing PCM with proper melting temperature and be controlled by varying velocity of air supply in different conditions

  1. Electrical resistivity, optical and magnetic properties of the layered oxyselenide SmCuOSe

    International Nuclear Information System (INIS)

    Llanos, Jaime; Pena, Octavio

    2005-01-01

    The electrical and magnetic properties of the tetragonal phase SmCuOSe are reported as a function of the temperature. The optical properties were studied by means of diffuse reflectance spectrum in the UV-Vis range. The electrical resistivity measurements as well as diffuse reflectance spectrum show that SmCuOSe is a semiconductor with an optical band gap (E g ) of 2.6eV. In this phase, Cu is at its monovalent oxidation state and, as such, it does not contribute to the total magnetic moment, whereas Sm is in its 3+ oxidation state, with a large VanVleck contribution due to the admixture of the fundamental state with higher energy levels

  2. Measurement of optically and thermally stimulated electron emission from natural minerals

    DEFF Research Database (Denmark)

    Ankjærgaard, C.; Murray, A.S.; Denby, P.M.

    2006-01-01

    to a Riso TL/OSL reader, enabling optically stimulated electrons (OSE) and thermally stimulated electrons (TSE) to be measured simultaneously with optically stimulated luminescence (OSL) and thermoluminescence (TL). Repeated irradiation and measurement is possible without removing the sample from...... the counting chamber. Using this equipment both OSE and TSE from loose sand-sized grains of natural minerals has been recorded. It is shown that both the surface electron traps (giving rise to the OSE signals) and the bulk traps (giving rise to OSL) have the same dosimetric properties. A comparison of OSL...

  3. Gamma irradiation effects on the thermal, optical and structural properties of Cr-39 nuclear track detector

    International Nuclear Information System (INIS)

    Nouh, S.A.; Said, A.F.; Atta, M.R.; EL-Mellegy, W.M.; EL-Meniawi, S.

    2006-01-01

    A study of the effect of gamma irradiation on the thermal, optical and structural properties of CR-39 diglycol carbonate solid state nuclear track detector (SSNTD) has been carried out. Samples from CR-39 polymer were irradiated with gamma doses at levels between 20 and 300 KGy. Non-isothermal studies were carried out using thermo-gravimetry (TG), differential thermo-gravimetry (DTG) and differential thermal analysis (DTA) to obtain the activation energy of decomposition and the transition temperatures for the non-irradiated and irradiated CR-39 samples. In addition, optical and structural property studies were performed on non-irradiated and irradiated CR-39 samples using refractive index and X-ray diffraction measurements. The variation of onset temperature of decomposition (To) thermal activation energy of decomposition (Ea) melting temperature (Tm) refractive index (n) and the mass fraction of the amorphous phase with the gamma dose were studied. It was found that many changes in the thermal, optical and structural properties of the CR-39 polymer could be produced by gamma irradiation via the degradation and cross linking mechanisms. Also, the gamma dose gave an advantage for increasing the correlation between the thermal stability of CR-39 polymer and the bond formation created by the ionizing effect of gamma radiation

  4. Novel design of electrical sensing interface for prosthetic limbs using optical micro cavities

    Science.gov (United States)

    Ali, Amir R.; Kamel, Mohamed A.

    2018-04-01

    This paper uses optical whispering galley modes (WGM) cavities to construct a new electrical sensing interface between prosthetic limb and the brain. The sensing element will detect the action potential signal in the neural membrane and the prosthetic limb will be actuated accordingly. The element is a WGM dielectric polymeric cavity. WGM based optical cavities can achieve very high values of sensitivity and quality factor; thus, any minute perturbations in the morphology of the cavity can be captured and measured. The action potential signal will produce an applied external electric field on the dielectric cavity causing it to deform due to the electrostriction effect. The resulting deformation will cause WGM shifts in the transmission spectrum of the cavity. Thus, the action potential or the applied electric field can be measured using these shifts. In this paper the action potential signal will be simulated through the use of a function generator and two metal electrodes. The sensing element will be situated between these electrodes to detect the electrical signal passing through. The achieved sensitivity is 27.5 pm/V in measuring the simulated action potential signal; and 0.32 pm/V.m-1 in measuring the applied electric field due to the passage of the simulated signal.

  5. Fiber-optic thermometer application of thermal radiation from rare-earth end-doped SiO2 fiber

    International Nuclear Information System (INIS)

    Katsumata, Toru; Morita, Kentaro; Komuro, Shuji; Aizawa, Hiroaki

    2014-01-01

    Visible light thermal radiation from SiO 2 glass doped with Y, La, Ce, Pr, Nd, Eu, Tb, Dy, Ho, Er, Tm, Yb, and Lu were studied for the fiber-optic thermometer application based on the temperature dependence of thermal radiation. Thermal radiations according to Planck's law of radiation are observed from the SiO 2 fibers doped with Y, La, Ce, Pr, Eu, Tb, and Lu at the temperature above 1100 K. Thermal radiations due to f-f transitions of rare-earth ions are observed from the SiO 2 fibers doped with Nd, Dy, Ho, Er, Tm, and Yb at the temperature above 900 K. Peak intensities of thermal radiations from rare-earth doped SiO 2 fibers increase sensitively with temperature. Thermal activation energies of thermal radiations by f-f transitions seen in Nd, Dy, Ho, Er, Tm, and Yb doped SiO 2 fibers are smaller than those from SiO 2 fibers doped with Y, La, Ce, Pr, Eu, Tb, and Lu. Thermal radiation due to highly efficient f-f transitions in Nd, Dy, Ho, Er, Tm, and Yb ions emits more easily than usual thermal radiation process. Thermal radiations from rare-earth doped SiO 2 are potentially applicable for the fiber-optic thermometry above 900 K

  6. Thermal, electrical and mechanical properties during cristallization of the amorphous alloy Co33Zr67

    International Nuclear Information System (INIS)

    Nicolaus, M.M.

    1992-01-01

    Topic of this work is to study the crystallization process of amorphous CO 33 Zr 67 alloy and to characterize its thermal, electrical and mechanical properties. Studies were carried out by calorimetry, vibrating-Reed technique, electrical-resistance measurement, dilatometry, X-ray diffraction and electron-transmission-microscopy. Results of microstructure analysis, kinetic analysis, specific heat, dilatometry (isothermal and non-isothermal) and electrical resistance are discussed in detail here

  7. Preparation of InSe Thin Films by Thermal Evaporation Method and Their Characterization: Structural, Optical, and Thermoelectrical Properties

    Directory of Open Access Journals (Sweden)

    Sarita Boolchandani

    2018-01-01

    Full Text Available The indium selenium (InSe bilayer thin films of various thickness ratios, InxSe(1-x (x = 0.25, 0.50, 0.75, were deposited on a glass substrate keeping overall the same thickness of 2500 Ǻ using thermal evaporation method under high vacuum atmosphere. Electrical, optical, and structural properties of these bilayer thin films have been compared before and after thermal annealing at different temperatures. The structural and morphological characterization was done using XRD and SEM, respectively. The optical bandgap of these thin films has been calculated by Tauc’s relation that varies within the range of 1.99 to 2.05 eV. A simple low-cost thermoelectrical power measurement setup is designed which can measure the Seebeck coefficient “S” in the vacuum with temperature variation. The setup temperature variation is up to 70°C. This setup contains a Peltier device TEC1-12715 which is kept between two copper plates that act as a reference metal. Also, in the present work, the thermoelectric power of indium selenide (InSe and aluminum selenide (AlSe bilayer thin films prepared and annealed in the same way is calculated. The thermoelectric power has been measured by estimating the Seebeck coefficient for InSe and AlSe bilayer thin films. It was observed that the Seebeck coefficient is negative for InSe and AlSe thin films.

  8. Numerical Model and Experimental Analysis of the Thermal Behavior of Electric Radiant Heating Panels

    Directory of Open Access Journals (Sweden)

    Giovanni Ferrarini

    2018-01-01

    Full Text Available Electric radiant heating panels are frequently selected during the design phase of residential and industrial heating systems, especially for retrofit of existing buildings, as an alternative to other common heating systems, such as radiators or air conditioners. The possibility of saving living and working space and the ease of installation are the main advantages of electric radiant solutions. This paper investigates the thermal performance of a typical electric radiant panel. A climatic room was equipped with temperature sensors and heat flow meters to perform a steady state experimental analysis. For the dynamic behavior, a mathematical model was created and compared to a thermographic measurement procedure. The results showed for the steady state an efficiency of energy transformation close to one, while in a transient thermal regime the time constant to reach the steady state condition was slightly faster than the typical ones of hydronic systems.

  9. Electric vehicles batteries thermal management systems employing phase change materials

    Science.gov (United States)

    Ianniciello, Lucia; Biwolé, Pascal Henry; Achard, Patrick

    2018-02-01

    Battery thermal management is necessary for electric vehicles (EVs), especially for Li-ion batteries, due to the heat dissipation effects on those batteries. Usually, air or coolant circuits are employed as thermal management systems in Li-ion batteries. However, those systems are expensive in terms of investment and operating costs. Phase change materials (PCMs) may represent an alternative which could be cheaper and easier to operate. In fact, PCMs can be used as passive or semi-passive systems, enabling the global system to sustain near-autonomous operations. This article presents the previous developments introducing PCMs for EVs battery cooling. Different systems are reviewed and solutions are proposed to enhance PCMs efficiency in those systems.

  10. Novel thermal management system using boiling cooling for high-powered lithium-ion battery packs for hybrid electric vehicles

    Science.gov (United States)

    Al-Zareer, Maan; Dincer, Ibrahim; Rosen, Marc A.

    2017-09-01

    A thermal management system is necessary to control the operating temperature of the lithium ion batteries in battery packs for electrical and hybrid electrical vehicles. This paper proposes a new battery thermal management system based on one type of phase change material for the battery packs in hybrid electrical vehicles and develops a three dimensional electrochemical thermal model. The temperature distributions of the batteries are investigated under various operating conditions for comparative evaluations. The proposed system boils liquid propane to remove the heat generated by the batteries, and the propane vapor is used to cool the part of the battery that is not covered with liquid propane. The effect on the thermal behavior of the battery pack of the height of the liquid propane inside the battery pack, relative to the height of the battery, is analyzed. The results show that the propane based thermal management system provides good cooling control of the temperature of the batteries under high and continuous charge and discharge cycles at 7.5C.

  11. Growth, structural, optical, thermal and mechanical studies on 4-Aminopyridinium monophthalate: A novel nonlinear optical crystal

    Science.gov (United States)

    Marudhu, G.; Krishnan, S.; Palanichamy, M.

    2016-03-01

    A novel nonlinear optical crystal of 4-Aminopyridinium monophthalate (4-APMP) was grown by slow evaporation technique using methanol as solvent. Single crystal X-ray diffraction analysis confirms that the grown crystal belongs to orthorhombic system. The presence of functional groups was qualitatively determined by FTIR analysis. The optical absorption studies reveal very low absorption in the entire visible region. The fluorescence emission spectrum shows the emission is in blue region. The thermal stability of the grown crystal is found to be around 197.2 °C. The SHG efficiency of the grown crystal is found to be 1.1 times than that of KDP crystals.

  12. Site-specific Pt deposition and etching on electrically and thermally isolated SiO2 micro-disk surfaces

    International Nuclear Information System (INIS)

    Saraf, Laxmikant V

    2010-01-01

    Electrically and thermally isolated surfaces are crucial for improving the detection sensitivity of microelectronic sensors. The site-specific in situ growth of Pt nano-rods on thermally and electrically isolated SiO 2 micro-disks using wet chemical etching and a focused ion/electron dual beam (FIB-SEM) is demonstrated. Fabrication of an array of micro-cavities on top of a micro-disk is also demonstrated. The FIB source is utilized to fabricate through-holes in the micro-disks. Due to the amorphous nature of SiO 2 micro-disks, the Ga implantation possibly modifies through-hole sidewall surface chemistry rather than affecting its transport properties. Some sensor design concepts based on micro-fabrication of SiO 2 micro-disks utilizing thermally and electrically isolated surfaces are discussed from the viewpoint of applications in photonics and bio-sensing.

  13. Influence of crystal field excitations on thermal and electrical resistivity of normal rare-earth metals

    Energy Technology Data Exchange (ETDEWEB)

    Durczewski, K.; Gajek, Z.; Mucha, J. [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Wroclaw (Poland)

    2014-11-15

    A simple formula describing the influence of the crystalline electric field free-ion excitations on the temperature dependence of the contribution of the s-f scattering to the thermal resistivity of normal rare-earth metals is presented. The corresponding formula for the electrical resistivity is also given and compared to the one being currently used. Theoretical electron-phonon scattering contributions derived in earlier papers and constant impurity scattering contributions are added to the derived s-f contribution formulae in order to fit the total electrical and thermal resistivity represented as functions of the temperature to experimental dependences on the temperature for DyIn{sub 3} and in this way to manifest applicability of the derived formulae to real materials. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  14. Influence of crystal field excitations on thermal and electrical resistivity of normal rare-earth metals

    International Nuclear Information System (INIS)

    Durczewski, K.; Gajek, Z.; Mucha, J.

    2014-01-01

    A simple formula describing the influence of the crystalline electric field free-ion excitations on the temperature dependence of the contribution of the s-f scattering to the thermal resistivity of normal rare-earth metals is presented. The corresponding formula for the electrical resistivity is also given and compared to the one being currently used. Theoretical electron-phonon scattering contributions derived in earlier papers and constant impurity scattering contributions are added to the derived s-f contribution formulae in order to fit the total electrical and thermal resistivity represented as functions of the temperature to experimental dependences on the temperature for DyIn 3 and in this way to manifest applicability of the derived formulae to real materials. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  15. Optical and electrochromic properties of Sn:WO3 cermets

    International Nuclear Information System (INIS)

    Ashrit, P.V.; Bader, G.; Girouard, F.E.; Truong, V.V.

    1989-01-01

    This paper discusses optical and electrochromic properties of Sn:WO 3 cermets deposited by alternate layer thermal deposition. These cermets exhibit electrical and optical behavior in the as deposited state. The inclusion of Sn in the WO 3 matrix enhances the Electrical conductivity of the system and renders them fairly transparent in the visible region. The electrochromic behavior of such systems is studied under both proton and Li + ion injection. The good conductivity and good transmission combined with good electrochromic characteristics of these systems indicate the possibility of utilizing this type of cermet for the dual role of transparent conductor (TC) and electrochromic (EC) layer

  16. A thermal and electrical dynamic mathematical model for squirrel cage induction motors; Modelamento matematico dinamico termico e eletrico de motores de inducao

    Energy Technology Data Exchange (ETDEWEB)

    Sousa, Ronaldo Martins de

    1996-01-01

    A thermal and electrical dynamic mathematical model for squirrel cage induction motors is presented. The electrical model is described by Park equation and the torque equation, while the thermal model is described by a system of four first order differential equations that represent the motor heat transfer process. The model presented can be used to determine thermal and electrical performance for any operation condition. However, it is suitable mainly for machines operating under continuously transient condition. The presented mathematical model also incorporate variation of rotor winding electrical parameters due to skin effect. (author)

  17. Experience of Milled Peat Burning at Thermal Electric Power Plant

    Directory of Open Access Journals (Sweden)

    G. I. Zhikhar

    2013-01-01

    Full Text Available The paper presents extensive knowledge and practical experience on burning of milled peat in the boilers of thermal electric power plants in Belarus and Russia. The accumulated experience can be used for solution of problems pertaining to substitution of some types of fuel imported to Belarus by milled peat which is extracted at many fuel effective peat enterprises of the Republic.

  18. A method to obtain the thermal parameters and the photothermal transduction efficiency in an optical hyperthermia device based on laser irradiation of gold nanoparticles.

    Science.gov (United States)

    Sánchez López de Pablo, Cristina; Olmedo, José Javier Serrano; Rosales, Alejandra Mina; Ramírez Hernández, Norma; Del Pozo Guerrero, Francisco

    2014-01-01

    Optical hyperthermia systems based on the laser irradiation of gold nanorods seem to be a promising tool in the development of therapies against cancer. After a proof of concept in which the authors demonstrated the efficiency of this kind of systems, a modeling process based on an equivalent thermal-electric circuit has been carried out to determine the thermal parameters of the system and an energy balance obtained from the time-dependent heating and cooling temperature curves of the irradiated samples in order to obtain the photothermal transduction efficiency. By knowing this parameter, it is possible to increase the effectiveness of the treatments, thanks to the possibility of predicting the response of the device depending on the working configuration. As an example, the thermal behavior of two different kinds of nanoparticles is compared. The results show that, under identical conditions, the use of PEGylated gold nanorods allows for a more efficient heating compared with bare nanorods, and therefore, it results in a more effective therapy.

  19. 40 Gb/s Lane Rate NG-PON using Electrical/Optical Duobinary, PAM-4 and Low Complex Equalizations

    DEFF Research Database (Denmark)

    Wei, J. L.; Grobe, Klaus; Wagner, Christoph

    2016-01-01

    We present the first numerical investigation and comparison of 40-Gb/s lane rate electrical Duobinary, optical Duobinary and PAM-4 for NG-PONs incorporating low complex linear and nonlinear post-equalizations.......We present the first numerical investigation and comparison of 40-Gb/s lane rate electrical Duobinary, optical Duobinary and PAM-4 for NG-PONs incorporating low complex linear and nonlinear post-equalizations....

  20. Optical and electrical properties of ion beam textured Kapton and Teflon

    Science.gov (United States)

    Mirtich, M. J.; Sovey, J. S.

    1977-01-01

    An electron bombardment argon ion source was used to ion etch polyimide (Kapton) and fluorinated ethylene, FEP (Teflon). Samples of polyimide and FEP were exposed to (0.5-1.0) keV Ar ions at ion current densities of (1.0-1/8) mA/sq cm for various exposure times. Changes in the optical and electrical properties of the samples were used to characterize the exposure. Spectral reflectance and transmittance measurements were made between 0.33 and 2.16 micron m using an integrating sphere after each exposure. From these measurements, values of solar absorptance were obtained. Total emittance measurements were also recorded for some samples. Surface resistivity was used to determine changes in the electrical conductivity of the etched samples. A scanning electron microscope recorded surface structure after exposure. Spectral optical data, resistivity measurements, calculated absorptance and emittance measurements are presented along with photomicrographs of the surface structure for the various exposures to Ar ions.

  1. Hybrid Perovskite Phase Transition and Its Ionic, Electrical and Optical Properties

    Energy Technology Data Exchange (ETDEWEB)

    Hoque, Md Nadim Ferdous; Islam, Nazifah; Zhu, Kai; Fan, Zhaoyang

    2017-01-01

    Hybrid perovskite solar cells (PSCs) under normal operation will reach a temperature above ~ 60 °C, across the tetragonal-cubic structural phase transition of methylammonium lead iodide (MAPbI3). Whether the structural phase transition could result in dramatic changes of ionic, electrical and optical properties that may further impact the PSC performances should be studied. Herein, we report a structural phase transition temperature of MAPbI3thin film at ~ 55 °C, but a striking contrast occurred at ~ 45 °C in the ionic and electrical properties of MAPbI3due to a change of the ion activation energy from 0.7 eV to 0.5 eV. The optical properties exhibited no sharp transition except for the steady increase of the bandgap with temperature. It was also observed that the activation energy for ionic migration steadily increased with increased grain sizes, and reduction of the grain boundary density reduced the ionic migration.

  2. Parametric studies and optimisation of pumped thermal electricity storage

    International Nuclear Information System (INIS)

    McTigue, Joshua D.; White, Alexander J.; Markides, Christos N.

    2015-01-01

    Highlights: • PTES is modelled by cycle analysis and a Schumann-style model of the thermal stores. • Optimised trade-off surfaces show a flat efficiency vs. energy density profile. • Overall roundtrip efficiencies of around 70% are not inconceivable. - Abstract: Several of the emerging technologies for electricity storage are based on some form of thermal energy storage (TES). Examples include liquid air energy storage, pumped heat energy storage and, at least in part, advanced adiabatic compressed air energy storage. Compared to other large-scale storage methods, TES benefits from relatively high energy densities, which should translate into a low cost per MW h of storage capacity and a small installation footprint. TES is also free from the geographic constraints that apply to hydro storage schemes. TES concepts for electricity storage rely on either a heat pump or refrigeration cycle during the charging phase to create a hot or a cold storage space (the thermal stores), or in some cases both. During discharge, the thermal stores are depleted by reversing the cycle such that it acts as a heat engine. The present paper is concerned with a form of TES that has both hot and cold packed-bed thermal stores, and for which the heat pump and heat engine are based on a reciprocating Joule cycle, with argon as the working fluid. A thermodynamic analysis is presented based on traditional cycle calculations coupled with a Schumann-style model of the packed beds. Particular attention is paid to the various loss-generating mechanisms and their effect on roundtrip efficiency and storage density. A parametric study is first presented that examines the sensitivity of results to assumed values of the various loss factors and demonstrates the rather complex influence of the numerous design variables. Results of an optimisation study are then given in the form of trade-off surfaces for roundtrip efficiency, energy density and power density. The optimised designs show a

  3. Faraday anomalous dispersion optical tuners

    Science.gov (United States)

    Wanninger, P.; Valdez, E. C.; Shay, T. M.

    1992-01-01

    Common methods for frequency stabilizing diode lasers systems employ gratings, etalons, optical electric double feedback, atomic resonance, and a Faraday cell with low magnetic field. Our method, the Faraday Anomalous Dispersion Optical Transmitter (FADOT) laser locking, is much simpler than other schemes. The FADOT uses commercial laser diodes with no antireflection coatings, an atomic Faraday cell with a single polarizer, and an output coupler to form a compound cavity. This method is vibration insensitive, thermal expansion effects are minimal, and the system has a frequency pull in range of 443.2 GHz (9A). Our technique is based on the Faraday anomalous dispersion optical filter. This method has potential applications in optical communication, remote sensing, and pumping laser excited optical filters. We present the first theoretical model for the FADOT and compare the calculations to our experimental results.

  4. Electrical and optical performance of transparent conducting oxide films deposited by electrostatic spray assisted vapour deposition.

    Science.gov (United States)

    Hou, Xianghui; Choy, Kwang-Leong; Liu, Jun-Peng

    2011-09-01

    Transparent conducting oxide (TCO) films have the remarkable combination of high electrical conductivity and optical transparency. There is always a strong motivation to produce TCO films with good performance at low cost. Electrostatic Spray Assisted Vapor Deposition (ESAVD), as a variant of chemical vapour deposition (CVD), is a non-vacuum and low-cost deposition method. Several types of TCO films have been deposited using ESAVD process, including indium tin oxide (ITO), antimony-doped tin oxide (ATO), and fluorine doped tin oxide (FTO). This paper reports the electrical and optical properties of TCO films produced by ESAVD methods, as well as the effects of post treatment by plasma hydrogenation on these TCO films. The possible mechanisms involved during plasma hydrogenation of TCO films are also discussed. Reduction and etching effect during plasma hydrogenation are the most important factors which determine the optical and electrical performance of TCO films.

  5. NEW OPTICAL/ULTRAVIOLET COUNTERPARTS AND THE SPECTRAL ENERGY DISTRIBUTIONS OF NEARBY, THERMALLY EMITTING, ISOLATED NEUTRON STARS

    International Nuclear Information System (INIS)

    Kaplan, D. L.; Kamble, A.; Van Kerkwijk, M. H.; Ho, W. C. G.

    2011-01-01

    We present Hubble Space Telescope optical and ultraviolet photometry for five nearby, thermally emitting neutron stars. With these measurements, all seven such objects have confirmed optical and ultraviolet counterparts. Combining our data with archival space-based photometry, we present spectral energy distributions for all sources and measure the 'optical excess': the factor by which the measured photometry exceeds that extrapolated from X-ray spectra. We find that the majority have optical and ultraviolet fluxes that are inconsistent with that expected from thermal (Rayleigh-Jeans) emission, exhibiting more flux at longer wavelengths. We also find that most objects have optical excesses between 5 and 12, but that one object (RX J2143.0+0654) exceeds the X-ray extrapolation by a factor of more than 50 at 5000 A, and that this is robust to uncertainties in the X-ray spectra and absorption. We consider explanations for this ranging from atmospheric effects, magnetospheric emission, and resonant scattering, but find that none is satisfactory.

  6. Sparse Reconstruction for Temperature Distribution Using DTS Fiber Optic Sensors with Applications in Electrical Generator Stator Monitoring

    Directory of Open Access Journals (Sweden)

    João Paulo Bazzo

    2016-09-01

    Full Text Available This paper presents an image reconstruction method to monitor the temperature distribution of electric generator stators. The main objective is to identify insulation failures that may arise as hotspots in the structure. The method is based on temperature readings of fiber optic distributed sensors (DTS and a sparse reconstruction algorithm. Thermal images of the structure are formed by appropriately combining atoms of a dictionary of hotspots, which was constructed by finite element simulation with a multi-physical model. Due to difficulties for reproducing insulation faults in real stator structure, experimental tests were performed using a prototype similar to the real structure. The results demonstrate the ability of the proposed method to reconstruct images of hotspots with dimensions down to 15 cm, representing a resolution gain of up to six times when compared to the DTS spatial resolution. In addition, satisfactory results were also obtained to detect hotspots with only 5 cm. The application of the proposed algorithm for thermal imaging of generator stators can contribute to the identification of insulation faults in early stages, thereby avoiding catastrophic damage to the structure.

  7. High-speed Integrated Circuits for electrical/Optical Interfaces

    DEFF Research Database (Denmark)

    Jespersen, Christoffer Felix

    2008-01-01

    This thesis is a continuation of the effort to increase the bandwidth of communicationnetworks. The thesis presents the results of the design of several high-speed electrical ircuits for an electrical/optical interface. These circuits have been a contribution to the ESTA project in collaboration...... circuits at the receiver interface, though VCOs are also found in the transmitter where a multitude of independent sources have to be mutually synchronized before multiplexing. The circuits are based on an InP DHBT process (VIP-2) supplied by Vitesse and made publicly available as MPW. The VIP-2 process...... represents the avant-garde of InP technology, with ft and fmax well above 300 GHz. Principles of high speed design are presented and described as a useful background before proceeding to circuits. A static divider is used as an example to illustrate many of the design principles. Theory and fundamentals...

  8. Electro-optical and physic-mechanical properties of colored alicyclic polyimide

    Science.gov (United States)

    Kravtsova, V.; Umerzakova, M.; Korobova, N.; Timoshenkov, S.; Timoshenkov, V.; Orlov, S.; Iskakov, R.; Prikhodko, O.

    2016-09-01

    Main optical, thermal and mechanical properties of new compositions based on alicyclic polyimide and active bright red 6C synthetic dye have been studied. It was shown that the transmission ratio of the new material in the region of 400-900 nm and 2.0 wt.% dye concentration was around 60-70%. Thermal, mechanical and electrical properties of new colored compositions were comparable with the properties of original polyimide.

  9. Crosslinked polyimide electro-optic materials

    Energy Technology Data Exchange (ETDEWEB)

    Kowalczyk, T.C.; Kosc, T.Z.; Singer, K.D. [Case Western Reserve University, Department of Physics, Cleveland, Ohio 44106-7079 (United States); Beuhler, A.J.; Wargowski, D.A. [Amoco Research Center, Amoco Chemical Co., Naperville, Illinois 60566 (United States); Cahill, P.A.; Seager, C.H.; Meinhardt, M.B. [Sandia National Laboratories, Division 1811, Albuquerque, New Mexico 87185-1407 (United States); Ermer, S. [Lockheed Research and Development Division, Palo Alto, California 94304 (United States)

    1995-11-15

    We report studies of the optical and electro-optic properties of guest--host polymeric nonlinear optical materials based on aromatic, fluorinated, fully imidized, organic soluble, thermally, and photochemically crosslinkable, guest--host polyimides. We have introduced temperature stable nonlinear optical chromophores into these polyimides and studied optical losses, electric field poling, electro-optic properties, and orientational stability. We measured electro-optic coefficients of 5.5 and 12.0 pm/V for ((2,6-Bis(2-(3-(9-(ethyl)carbazolyl))ethenyl)4H-pyran-4-ylidene)propanedinitrile) (4-(Dicyanomethylene)-2-methyl-6-(p -dimethylaminostyryl)-4H-pyran) DCM-doped guest--host systems at 800 nm using a poling field of 1.3 MV/cm. Poling induced nonlinearities in single-layer films were in agreement with the oriented gas model, but were lower in three-layer films due to voltage division across the layers. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

  10. A β-cyclodextrin based binary dopant for polyaniline: Structural, thermal, electrical, and sensing performance

    Energy Technology Data Exchange (ETDEWEB)

    Sen, Tanushree; Mishra, Satyendra [University Institute of Chemical Technology, North Maharashtra University, Jalgaon 425001, Maharashtra (India); Shimpi, Navinchandra G., E-mail: navin_shimpi@rediffmail.com [Department of Chemistry, University of Mumbai, Kalina, Mumbai 400098, Maharashtra (India)

    2017-06-15

    Highlights: • A binary dopant based on β-cyclodextrin has been proposed for PANI. • The binary dopant provided long term stability to electrically conducting PANI. • The β-cyclodextrin based binary dopant rendered PANI sensitive towards CO at RT. - Abstract: The effect of hydrochloric acid/β-cyclodextrin (HCl/β-CD) binary dopant on the morphological, thermal, electrical, and sensing properties of PANI was investigated and compared with those of the conventionally doped PANI. The PANI samples were characterized using FTIR, UV–Vis, {sup 1}H NMR, and FESEM. Significant changes were observed in the structural, thermal, and electrical character of PANI doped with the HCl/β-CD binary dopant. A higher doping level was obtained for the PANI-binary dopant system, as observed from its {sup 1}H NMR spectra. Moreover, the binary dopant imparted long-term stability to the sensor in its conductive form. In addition, the PANI-binary dopant system exhibited a significantly high gas response towards carbon monoxide gas at room temperature.

  11. Optical and electrical characterization of r.f. sputtered ITO films developed as art protection coatings

    International Nuclear Information System (INIS)

    Boycheva, Sylvia; Sytchkova, Anna Krasilnikova; Piegari, Angela

    2007-01-01

    Transparent and conductive tin-doped indium oxide (ITO) films have been prepared by r.f. plasma sputtering technique in Ar and Ar + O 2 gas mixture. The influence of the deposition conditions, film thickness, and substrate heating, as well as the post-annealing treatment on the optical and electrical properties of the ITO films has been investigated. The present study has extended the optical behaviour characterization of the ITO films in a wide UV-VIS-IR spectral region in addition to the comprehensive optical studies of this material at shorter wavelengths. The optical constants: refractive index (n), extinction (k) and absorption (α) coefficient, and the optical band gap (E go ) have been calculated for the ITO films in the spectral range between 350 and 2500 nm. A combination of several well-known theoretical models has been applied to describe precisely the complex optical behaviour of ITO films in separate spectral parts. In this approach, a good overlapping between the experimental and the simulated spectra in the whole investigated spectral region has been achieved. The deposition conditions and the optical and electrical properties of the ITO films have been optimized with respect to the requirements for their applications in art protection coatings

  12. Towards Electrically Pumped Nanolasers for Terabit Communication

    DEFF Research Database (Denmark)

    Lupi, Alexandra

    This thesis deals with modeling, design, fabrication and characterization of vertically electrically pumped photonic crystal light-emitting devices. For this purpose a new material platform of III-V semiconductors on silicon has been developed. The devices fabricated on this platform can be used...... as optical interconnects, where compatibility with Complementary Metal Oxide Semiconductor (CMOS) technology is required. The first part of this work is dedicated to modeling and simulations of electrically pumped photonic crystal nanolasers with diverse material configurations and different concepts...... for electrical injection. The analysis of the models is conducted with focus on laser performances, energy efficiency, and thermal properties. The second part of this thesis deals with design, fabrication and characterization of vertically electrically pumped photonic crystal light-emitting devices. The devices...

  13. Fabrication and characterization of stearic acid/polyaniline composite with electrical conductivity as phase change materials for thermal energy storage

    International Nuclear Information System (INIS)

    Wang, Yi; Ji, Hui; Shi, Huan; Zhang, Ting; Xia, TianDong

    2015-01-01

    Highlights: • Stearic acid/polyaniline composite PCM with electrical conductivity was fabricated. • Stearic acid acted as thermal energy storage media and doping acid. • Latent heats of SA/PANI are as high as the same type composites. • Improved electrical conductivity of capsules is 0.7042 S cm −1 . - Abstract: This paper presents the experimental investigation on the thermal properties and electrical conductivity of the new microencapsulated phase change material by entrapping of stearic acid (SA) into PANI (polyaniline) shell through self-assembly method. Experimental results reveal that PANI nuclei grew on the surface of SA, and then copied its original morphological structure and finally exhibited peony flower-like morphology. The two components have good compatibility and have no chemical reaction both in the process of fabrication and subsequent use, while hydrogen bondings between the imino groups and carboxyl groups exist. The maximum mass fraction of stearic acid loaded in SA/PANI is determined as high as 62.1 wt% without seepage of melted SA from capsules. Due to the secondary doping with carboxyl group, the composite phase change material embedded with SA exhibits improved electrical conductivity from 0.3968 S cm −1 to 0.7042 S cm −1 when compared to PANI. The phase change temperatures and latent heats of SA/PANI are measured to be 55.6 °C and 113.02 J/g for melting and, 50.8 °C and 112.58 J/g for freezing, respectively. TG analysis test revealed that the prepared SA/PANI composite PCM has high thermal durability in working temperature range. Moreover, the results of DSC, FT-IR, TG, conductivity investigation and thermal cycling test are all show that the thermal reliability and electrical conductivity of the SA/APNI have imperceptible changes. In total, the additional electrical conductivity, high heat storage potential and good thermal reliability and stability facilitated SA/PANI to be considered as a viable candidate for thermal

  14. Analysis of the optical and thermal properties of transparent insulating materials containing gas bubbles

    International Nuclear Information System (INIS)

    Cai, Qilin; Ye, Hong; Lin, Qizhao

    2016-01-01

    Highlights: • Transparent insulating medium containing gas bubbles was proposed. • Radiative transfer and thermal conduction models were constructed. • Bulk transmittance increases first and then decreases with the bubble number. • Effective thermal conductivity decreases with increasing filling ratio. • High filling ratio with large bubbles is preferred for good performance. - Abstract: As a medium of low absorption and low thermal conduction, introducing gas bubbles into semitransparent mediums, such as glass and polycarbonate (PC), may simultaneously improve their light transmission and thermal insulation performances. However, gas bubbles can also enhance light scattering, which is in competition with the effect of the absorption decrease. Moreover, the balance between the visible light transmittance and the effective thermal conductivity should also be considered in the material design. Therefore, a radiative transfer model and the Maxwell–Eucken model for such material were employed to analyze the optical and thermal performances, respectively. The results demonstrate that the transmittance increases when the bubble radius (r) increases with a fixed volume fraction of the gas bubbles (f_v) due to the increased scattering intensity. In addition, the effective thermal conductivity always decreases with increasing f_v. Thus, to achieve both good optical and thermal performances, high f_v with large r is preferred. When f_v=0.5, the transmittance can be kept larger than 50% as long as r ≥ 0.7 mm. To elucidate the application performance, the heat transfer of a freezer adopting the glass or PC with gas bubbles as a cover was analyzed and the energy saving can be nearly 10%.

  15. The Optical and Electrical Properties of ZnO/Ag/ZnO Films on Flexible Substrate

    Science.gov (United States)

    Yu, Xiaojing; Zhang, Dongyan; Wang, Pangpang; Murakami, Ri-Ichi; Ding, Bingjun; Song, Xiaoping

    The deposition of ZnO/Ag/ZnO film on polyethylene terephthalate (PET) substrate was fabricated by DC magnetron sputtering method. The thicknesses of ZnO layers were 30 nm and Ag films' thicknesses were changed from 1 nm to 6 nm by controlled the sputtering time. This kind of film can be used as transparent conductive oxide (TCO) materials. The electrical and optical properties of composite layers were determined by Ag films. The optimum sputtering time of Ag thin films was found to be 20 s for the high optical transmittance with good electrical conductivity. The ZnO/Ag(20 s)/ZnO layer, which has high optical transmittance of 73% at 550 nm, shows sheet resistance as low as 6.7 ohm/sq. These multilayer transparent films had low electrical resistance as the widely used transparent conductive oxide electrodes. SEM, XRD, the UV-Vis-NIR and Hall Effect measurement system were used to characterize properties of fabricated films. The reasons for the change of transmittance and resistance will also be interpreted.

  16. Predictive values of thermal and electrical dental pulp tests: a clinical study.

    Science.gov (United States)

    Villa-Chávez, Carlos E; Patiño-Marín, Nuria; Loyola-Rodríguez, Juan P; Zavala-Alonso, Norma V; Martínez-Castañón, Gabriel A; Medina-Solís, Carlo E

    2013-08-01

    For a diagnostic test to be useful, it is necessary to determine the probability that the test will provide the correct diagnosis. Therefore, it is necessary to calculate the predictive value of diagnostics. The aim of the present study was to identify the sensitivity, specificity, positive and negative predictive values, accuracy, and reproducibility of thermal and electrical tests of pulp sensitivity. The thermal tests studied were the 1, 1, 1, 2-tetrafluoroethane (cold) and hot gutta-percha (hot) tests. For the electrical test, the Analytic Technology Pulp Tester (Analytic Technology, Redmond, WA) was used. A total of 110 teeth were tested: 60 teeth with vital pulp and 50 teeth with necrotic pulps (disease prevalence of 45%). The ideal standard was established by direct pulp inspection. The sensitivities of the diagnostic tests were 0.88 for the cold test, 0.86 for the heat test, and 0.76 for the electrical test, and the specificity was 1.0 for all 3 tests. The negative predictive value was 0.90 for the cold test, 0.89 for the heat test, and 0.83 for the electrical test, and the positive predictive value was 1.0 for all 3 tests. The highest accuracy (0.94) and reproducibility (0.88) were observed for the cold test. The cold test was the most accurate method for diagnostic testing. Copyright © 2013 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  17. Effects of deposition temperatures and annealing conditions on the microstructural, electrical and optical properties of polycrystalline Al-doped ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Joon-Ho [Department of Materials Science and Engineering, Korea University, Seoul 136-713 (Korea, Republic of); Kim, Kyoung-Kook [Department of Nano-Optical Engineering, Korea Polytechnic University, Gyeonggi 429-793 (Korea, Republic of); Seong, Tae-Yeon, E-mail: tyseong@korea.ac.kr [Department of Materials Science and Engineering, Korea University, Seoul 136-713 (Korea, Republic of)

    2011-01-15

    Al-doped ZnO (AZO, ZnO:Al{sub 2}O{sub 3} = 98:2 wt%) films are deposited on different substrates by an RF magnetron sputtering and subsequently annealed at three different conditions to investigate the microstructural, electrical, and optical properties. X-ray diffraction and scanning electron microscope results show that all the samples are polycrystalline and the samples rapid-thermal-annealed at 900 deg. C in an N{sub 2} ambient contain larger grains compared to the furnace-annealed samples. It is shown that the sample deposited at room temperature on the sapphire gives a resistivity of 5.57 x 10{sup -4} {Omega} cm when furnace-annealed at 500 deg. C in a mixture of N{sub 2}:H{sub 2} (9:1). It is also shown that the Hall mobility vs. carrier concentration ({mu}-n) relation is divided into two groups, depending on the annealing conditions, namely, either rapid-thermal annealing or furnace annealing. The relations are described in terms of either grain boundary scattering or ionized impurity scattering mechanism. In addition, the samples produce fairly high transmittance of 91-96.99% across the wavelength region of 400-1100 nm. The optical bandgaps of the samples increase with increasing carrier concentration.

  18. New Methods of Enhancing the Thermal Durability of Silica Optical Fibers

    Directory of Open Access Journals (Sweden)

    Karol Wysokiński

    2014-10-01

    Full Text Available Microstructured optical fibers can be precisely tailored for many different applications, out of which sensing has been found to be particularly interesting. However, placing silica optical fiber sensors in harsh environments results in their quick destruction as a result of the hydrolysis process. In this paper, the degradation mechanism of bare and metal-coated optical fibers at high temperatures under longitudinal strain has been determined by detailed analysis of the thermal behavior of silica and metals, like copper and nickel. We furthermore propose a novel method of enhancing the lifetime of optical fibers by the deposition of electroless nickel-phosphorous alloy in a low-temperature chemical process. The best results were obtained for a coating comprising an inner layer of copper and outer layer of low phosphorous nickel. Lifetime values obtained during the annealing experiments were extrapolated to other temperatures by a dedicated model elaborated by the authors. The estimated copper-coated optical fiber lifetime under cycled longitudinal strain reached 31 h at 450 °C.

  19. Manufacturing and testing flexible microfluidic devices with optical and electrical detection mechanisms

    NARCIS (Netherlands)

    Ivan, M.G.; Vivet, F.; Meinders, E.R.

    2010-01-01

    Flexible microfluidic devices made of poly(dimethylsiloxane) (PDMS) were manufactured by soft lithography, and tested in detection of ionic species using optical absorption spectroscopy and electrical measurements. PDMS was chosen due to its flexibility and ease of surface modification by exposure

  20. Nonlinear optical rectification and optical absorption in GaAs-Ga1-xAlxAs asymmetric double quantum wells: Combined effects of applied electric and magnetic fields and hydrostatic pressure

    International Nuclear Information System (INIS)

    Karabulut, I.; Mora-Ramos, M.E.; Duque, C.A.

    2011-01-01

    The intersubband electron-related nonlinear optical absorption and nonlinear optical rectification in GaAs-Ga 1-x Al x As asymmetric double quantum wells are studied, under the influence of combined or independent applied electric and magnetic fields as well as hydrostatic pressure. The outcome of the density matrix formalism and the effective mass, and parabolic-band approximations have been considered as main theoretical tools for the description. It is obtained that under particular geometrical conditions, with or without electric and/or magnetic field strength, the optical rectification is null and, simultaneously, in such circumstances the optical absorption has a relative maximum. It is also detected that the influence of the hydrostatic pressure leads to increasing or decreasing behaviors of the nonlinear optical absorption in dependence of the particular regime of pressure values considered, with significant distinction of the cases of opposite electric field orientations. - Highlights: → Maxima of the NOA correspond to zero in the NOR. → Electric fields can couple the double quantum wells. → Hydrostatic pressure can couple the double quantum wells. → NOA can increase/decrease with hydrostatic pressure. → Overlap between wave functions depends on the magnetic field.

  1. Sectoral Innovation Watch electrical and Optical Equipment Sector. Final sector report

    NARCIS (Netherlands)

    Broek, T. van den; Giessen, A.M. van der

    2011-01-01

    The electrical and optical equipment sector is a high-tech manufacturing sector. It is one of the most innovative sectors in Europe with investments and advances in fundamental research, applied R&D and innovation in the actual use of equipment. This sector is also one of the most global sectors

  2. Nonlinear optical rectification in semiparabolic quantum wells with an applied electric field

    International Nuclear Information System (INIS)

    Karabulut, ibrahim; Safak, Haluk

    2005-01-01

    The optical rectification (OR) in a semiparabolic quantum well with an applied electric field has been theoretically investigated. The electronic states in a semiparabolic quantum well with an applied electric field are calculated exactly, within the envelope function and the displaced harmonic oscillator approach. Numerical results are presented for the typical Al x Ga 1- x As/GaAs quantum well. These results show that the applied electric field and the confining potential frequency of the semiparabolic quantum well have a great influence on the OR coefficient. Moreover, the OR coefficient also depends sensitively on the relaxation rate of the semiparabolic quantum well system

  3. Electrical and thermal transport properties of layered Bi{sub 2}YO{sub 4}Cu{sub 2}Se{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Yu; Pei, Yanling; Chang, Cheng; Zhang, Xiao [School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Tan, Xing [State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Ye, Xinxin [Department of Physics, South University of Science and Technology of China, Shenzhen 518055 (China); Gong, Shengkai [School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Lin, Yuanhua [State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); He, Jiaqing [Department of Physics, South University of Science and Technology of China, Shenzhen 518055 (China); Zhao, Li-Dong, E-mail: zhaolidong@buaa.edu.cn [School of Materials Science and Engineering, Beihang University, Beijing 100191 (China)

    2016-07-15

    Bi{sub 2}YO{sub 4}Cu{sub 2}Se{sub 2} possesses a low thermal conductivity and high electrical conductivity at room temperature, which was considered as a potential thermoelectric material. In this work, we have investigated the electrical and thermal transport properties of Bi{sub 2}YO{sub 4}Cu{sub 2}Se{sub 2} system in the temperature range from 300 K to 873 K. We found that the total thermal conductivity decreases from ~1.8 W m{sup −1} K{sup −1} to ~0.9 W m{sup −1} K{sup −1}, and the electrical conductivity decreases from ~850 S/cm to ~163 S/cm in the measured temperature range. To investigate how potential of Bi{sub 2}YO{sub 4}Cu{sub 2}Se{sub 2} system, we prepared the heavily Iodine doped samples to counter-dope intrinsically high carrier concentration and improve the electrical transport properties. Interestingly, the Seebeck coefficient could be enhanced to ~+80 μV/K at 873 K, meanwhile, we found that a low thermal conductivity of ~0.7 W m{sup −1} K{sup −1} could be achieved. The intrinsically low thermal conductivity in this system is related to the low elastic properties, such as Young's modulus of 70–72 GPa, and Grüneisen parameters of 1.55–1.71. The low thermal conductivity makes Bi{sub 2}YO{sub 4}Cu{sub 2}Se{sub 2} system to be a potential thermoelectric material, the ZT value ~0.06 at 873 K was obtained, a higher performance is expected by optimizing electrical transport properties through selecting suitable dopants, modifying band structures or by further reducing thermal conductivity through nanostructuring etc. - Highlights: • The total thermal conductivity decreases from 1.8 to 0.9 Wm{sup –1}K{sup –1} at 300–873K. • The electrical conductivity decreased from 850 to 163 S/cm at 300–873K. • The Seebeck coefficients were enhanced through heavily Iodine doping. • The ZT ~0.06 at 873K suggests that Bi{sub 2}YO{sub 4}Cu{sub 2}Se{sub 2} systems are potential thermoelectrical materials.

  4. Energy savings and increased electric vehicle range through improved battery thermal management

    International Nuclear Information System (INIS)

    Smith, Joshua; Hinterberger, Michael; Schneider, Christoph; Koehler, Juergen

    2016-01-01

    Lithium-ion cells are temperature sensitive: operation outside the optimal operating range causes premature aging and correspondingly reduces vehicle range and battery system lifetime. In order to meet consumer demands for electric and hybrid-electric vehicle performance, especially in adverse climates, a battery thermal management system (BTMS) is often required. This work presents a novel experimental method for analyzing BTMS using three sample cooling plate concepts. For each concept, the input parameters (ambient temperature, coolant temperature and coolant flow rate) are varied and the resulting effect on the average temperature and temperature distribution across and between cells is compared. Additionally, the pressure loss along the coolant path is utilized as an indicator of energy efficiency. Using the presented methodology, various cooling plate layouts optimized for production alternative techniques are compared to the state of the art. It is shown that these production-optimized cooling plates provide sufficient thermal performance with the additional benefit of mechanical integration within the battery and/or vehicle system. It is also shown that the coolant flow influences battery cell thermal behavior more than the solid material and that pressure drop is more sensitive to geometrical changes in the cooling plate than temperature changes at the module.

  5. The Electrical and Thermal Conductivity of Woven Pristine and Intercalated Graphite Fiber-Polymer Composites

    Science.gov (United States)

    Gaier, James R.; Vandenburg, Yvonne Yoder; Berkebile, Steven; Stueben, Heather; Balagadde, Frederick

    2002-01-01

    A series of woven fabric laminar composite plates and narrow strips were fabricated from a variety of pitch-based pristine and bromine intercalated graphite fibers in an attempt to determine the influence of the weave on the electrical and thermal conduction. It was found generally that these materials can be treated as if they are homogeneous plates. The rule of mixtures describes the resistivity of the composite fairly well if it is realized that only the component of the fibers normal to the equipotential surface will conduct current. When the composite is narrow with respect to the fiber weave, however, there is a marked angular dependence of the resistance which was well modeled by assuming that the current follows only along the fibers (and not across them in a transverse direction), and that the contact resistance among the fibers in the composite is negligible. The thermal conductivity of composites made from less conductive fibers more closely followed the rule of mixtures than that of the high conductivity fibers, though this is thought to be an artifact of the measurement technique. Electrical and thermal anisotropy could be induced in a particular region of the structure by weaving together high and low conductivity fibers in different directions, though this must be done throughout all of the layers of the structure as interlaminar conduction precludes having only the top layer carry the anisotropy. The anisotropy in the thermal conductivity is considerably less than either that predicted by the rule of mixtures or the electrical resistivity.

  6. Electrical and optical properties of sub-10 nm nickel silicide films for silicon solar cells

    International Nuclear Information System (INIS)

    Brahmi, Hatem; Ravipati, Srikanth; Yarali, Milad; Wang, Weijie; Ryou, Jae-Hyun; Mavrokefalos, Anastassios; Shervin, Shahab

    2017-01-01

    Highly conductive and transparent films of ultra-thin p-type nickel silicide films have been prepared by RF magnetron sputtering of nickel on silicon substrates followed by rapid thermal annealing in an inert environment in the temperature range 400–600 °C. The films are uniform throughout the wafer with thicknesses in the range of 3–6 nm. The electrical and optical properties are presented for nickel silicide films with varying thickness. The Drude–Lorentz model and Fresnel equations were used to calculate the dielectric properties, sheet resistance, absorption and transmission of the films. These ultrathin nickel silicide films have excellent optoelectronic properties for p-type contacts with optical transparencies up to 80% and sheet resistance as low as ∼0.15 µΩ cm. Furthermore, it was shown that the use of a simple anti-reflection (AR) coating can recover most of the reflected light approaching the values of a standard Si solar cell with the same AR coating. Overall, the combination of ultra-low thickness, high transmittance, low sheet resistance and ability to recover the reflected light by utilizing standard AR coating makes them ideal for utilization in silicon based photovoltaic technologies as a p-type transparent conductor. (paper)

  7. Electrical and optical properties of sub-10 nm nickel silicide films for silicon solar cells

    Science.gov (United States)

    Brahmi, Hatem; Ravipati, Srikanth; Yarali, Milad; Shervin, Shahab; Wang, Weijie; Ryou, Jae-Hyun; Mavrokefalos, Anastassios

    2017-01-01

    Highly conductive and transparent films of ultra-thin p-type nickel silicide films have been prepared by RF magnetron sputtering of nickel on silicon substrates followed by rapid thermal annealing in an inert environment in the temperature range 400-600 °C. The films are uniform throughout the wafer with thicknesses in the range of 3-6 nm. The electrical and optical properties are presented for nickel silicide films with varying thickness. The Drude-Lorentz model and Fresnel equations were used to calculate the dielectric properties, sheet resistance, absorption and transmission of the films. These ultrathin nickel silicide films have excellent optoelectronic properties for p-type contacts with optical transparencies up to 80% and sheet resistance as low as ~0.15 µΩ cm. Furthermore, it was shown that the use of a simple anti-reflection (AR) coating can recover most of the reflected light approaching the values of a standard Si solar cell with the same AR coating. Overall, the combination of ultra-low thickness, high transmittance, low sheet resistance and ability to recover the reflected light by utilizing standard AR coating makes them ideal for utilization in silicon based photovoltaic technologies as a p-type transparent conductor.

  8. Effects of thermal deformation on optical instruments for space application

    Science.gov (United States)

    Segato, E.; Da Deppo, V.; Debei, S.; Cremonese, G.

    2017-11-01

    Optical instruments for space missions work in hostile environment, it's thus necessary to accurately study the effects of ambient parameters variations on the equipment. In particular optical instruments are very sensitive to ambient conditions, especially temperature. This variable can cause dilatations and misalignments of the optical elements, and can also lead to rise of dangerous stresses in the optics. Their displacements and the deformations degrade the quality of the sampled images. In this work a method for studying the effects of the temperature variations on the performance of imaging instrument is presented. The optics and their mountings are modeled and processed by a thermo-mechanical Finite Element Model (FEM) analysis, then the output data, which describe the deformations of the optical element surfaces, are elaborated using an ad hoc MATLAB routine: a non-linear least square optimization algorithm is adopted to determine the surface equations (plane, spherical, nth polynomial) which best fit the data. The obtained mathematical surface representations are then directly imported into ZEMAX for sequential raytracing analysis. The results are the variations of the Spot Diagrams, of the MTF curves and of the Diffraction Ensquared Energy due to simulated thermal loads. This method has been successfully applied to the Stereo Camera for the BepiColombo mission reproducing expected operative conditions. The results help to design and compare different optical housing systems for a feasible solution and show that it is preferable to use kinematic constraints on prisms and lenses to minimize the variation of the optical performance of the Stereo Camera.

  9. Simulation of thermal stresses in anode-supported solid oxide fuel cell stacks. Part II: Loss of gas-tightness, electrical contact and thermal buckling

    Science.gov (United States)

    Nakajo, Arata; Wuillemin, Zacharie; Van herle, Jan; Favrat, Daniel

    Structural stability issues in planar solid oxide fuel cells arise from the mismatch between the coefficients of thermal expansion of the components. The stress state at operating temperature is the superposition of several contributions, which differ depending on the component. First, the cells accumulate residual stresses due to the sintering phase during the manufacturing process. Further, the load applied during assembly of the stack to ensure electric contact and flatten the cells prevents a completely stress-free expansion of each component during the heat-up. Finally, thermal gradients cause additional stresses in operation. The temperature profile generated by a thermo-electrochemical model implemented in an equation-oriented process modelling tool (gPROMS) was imported into finite-element software (ABAQUS) to calculate the distribution of stress and contact pressure on all components of a standard solid oxide fuel cell repeat unit. The different layers of the cell in exception of the cathode, i.e. anode, electrolyte and compensating layer were considered in the analysis to account for the cell curvature. Both steady-state and dynamic simulations were performed, with an emphasis on the cycling of the electrical load. The study includes two different types of cell, operation under both thermal partial oxidation and internal steam-methane reforming and two different initial thicknesses of the air and fuel compressive sealing gaskets. The results generated by the models are presented in two papers: Part I focuses on cell cracking. In the present paper, Part II, the occurrences of loss of gas-tightness in the compressive gaskets and/or electrical contact in the gas diffusion layer were identified. In addition, the dependence on temperature of both coefficients of thermal expansion and Young's modulus of the metallic interconnect (MIC) were implemented in the finite-element model to compute the plastic deformation, while the possibilities of thermal buckling

  10. Solar thermal power systems point-focusing thermal and electric applications projects. Volume 1: Executive summary

    Science.gov (United States)

    Marriott, A.

    1980-01-01

    The activities of the Point-Focusing Thermal and Electric Applications (PETEA) project for the fiscal year 1979 are summarized. The main thrust of the PFTEA Project, the small community solar thermal power experiment, was completed. Concept definition studies included a small central receiver approach, a point-focusing distributed receiver system with central power generation, and a point-focusing distributed receiver concept with distributed power generation. The first experiment in the Isolated Application Series was initiated. Planning for the third engineering experiment series, which addresses the industrial market sector, was also initiated. In addition to the experiment-related activities, several contracts to industry were let and studies were conducted to explore the market potential for point-focusing distributed receiver (PFDR) systems. System analysis studies were completed that looked at PFDR technology relative to other small power system technology candidates for the utility market sector.

  11. Electrical properties of pressure quenched silicon by thermal spraying

    International Nuclear Information System (INIS)

    Tan, S.Y.; Gambino, R.J.; Sampath, S.; Herman, H.

    2007-01-01

    High velocity thermal spray deposition of polycrystalline silicon film onto single crystal substrates, yields metastable high pressure forms of silicon in nanocrystalline form within the deposit. The phases observed in the deposit include hexagonal diamond-Si, R-8, BC-8 and Si-IX. The peculiar attribute of this transformation is that it occurs only on orientation silicon substrate. The silicon deposits containing the high pressure phases display a substantially higher electrical conductivity. The resistivity profile of the silicon deposit containing shock induced metastable silicon phases identified by X-ray diffraction patterns. The density of the pressure induced polymorphic silicon is higher at deposit/substrate interface. A modified two-layer model is presented to explain the resistivity of the deposit impacted by the pressure induced polymorphic silicon generated by the thermal spraying process. The pressure quenched silicon deposits on the p - silicon substrate, with or without metastable phases, display the barrier potential of about 0.72 eV. The measured hall mobility value of pressure quenched silicon deposits is in the range of polycrystalline silicon. The significance of this work lies in the fact that the versatility of thermal spray may enable applications of these high pressure forms of silicon

  12. Computational modelling of internally cooled wet (ICW) electrodes for radiofrequency ablation: impact of rehydration, thermal convection and electrical conductivity.

    Science.gov (United States)

    Trujillo, Macarena; Bon, Jose; Berjano, Enrique

    2017-09-01

    (1) To analyse rehydration, thermal convection and increased electrical conductivity as the three phenomena which distinguish the performance of internally cooled electrodes (IC) and internally cooled wet (ICW) electrodes during radiofrequency ablation (RFA), (2) Implement a RFA computer model with an ICW which includes these phenomena and (3) Assess their relative influence on the thermal and electrical tissue response and on the coagulation zone size. A 12-min RFA in liver was modelled using an ICW electrode (17 G, 3 cm tip) by an impedance-control pulsing protocol with a constant current of 1.5 A. A model of an IC electrode was used to compare the ICW electrode performance and the computational results with the experimental results. Rehydration and increased electrical conductivity were responsible for an increase in coagulation zone size and a delay (or absence) in the occurrence of abrupt increases in electrical impedance (roll-off). While the increased electrical conductivity had a remarkable effect on enlarging the coagulation zone (an increase of 0.74 cm for differences in electrical conductivity of 0.31 S/m), rehydration considerably affected the delay in roll-off, which, in fact, was absent with a sufficiently high rehydration level. In contrast, thermal convection had an insignificant effect for the flow rates considered (0.05 and 1 mL/min). Computer results suggest that rehydration and increased electrical conductivity were mainly responsible for the absence of roll-off and increased size of the coagulation zone, respectively, and in combination allow the thermal and electrical performance of ICW electrodes to be modelled during RFA.

  13. Experimental study of thermal field deriving from an underground electrical power cable buried in non-homogeneous soils

    International Nuclear Information System (INIS)

    Lieto Vollaro, Roberto de; Fontana, Lucia; Vallati, Andrea

    2014-01-01

    The electrical cables ampacity mainly depends on the cable system operation temperature. To achieve a better cable utilization and reduce the conservativeness typically employed in buried cable design, an accurate evaluation of the heat dissipation through the cables and the surrounding soil is important. In the traditional method adopted by the International Electrotechnical Commission (IEC) and the Institute of Electrical and Electronics Engineers (IEEE) for the computation of the thermal resistance between an existing underground cable system and the external environment, it is still assumed that the soil is homogeneous and has uniform thermal conductivity. Numerical studies have been conducted to predict the temperature distribution around the cable for various configurations and thermal properties of the soil. The paper presents an experimental study conducted on a scale model to investigate the heat transfer of a buried cable, with different geometrical configurations and thermal properties of the soil, and to validate a simplified model proposed by the authors in 2012 for the calculation of the thermal resistance between the underground pipe or electrical cable and the ground surface, in cases where the filling of the trench is filled with layers of materials with different thermal properties. Results show that experimental data are in good agreement with the numerical ones. -- Highlights: • Heat transfer of a buried cable has been experimentally studied on a scale model. • Different configurations and thermal properties of the soil have been tested. • Authors previously proposed a simplified model and obtained numerical results. • Experimental results and numerical ones previously obtained were in accordance

  14. Building a digital scale using optical fiber sensors for teaching shift

    International Nuclear Information System (INIS)

    Diaz, L.; Torres, C.

    2016-01-01

    In this article is show the implementation of an electronic balance using Optics fibers for teaching displacement sensors. The system is based on displacement detections using an fiber optical bifurcated as active optical medium, commercial pointers of power lesser 10mW, a converter sensor of light intensities at electric, a PIC for signal processing and LCD to display the data. The importance of the implemented prototype lies in having an electronic device developed by students of the electives of optoelectronic, applying displacement sensing, also, the balance built could be used in zones classified with electromagnetic interference and in the areas hazardous by not using or storing sufficient electrical or thermal energy it can ignite a flammable atmosphere environment. (Author

  15. Optically stimulated luminescence of ZnO obtained by thermal treatment of ZnS chemically synthesized

    International Nuclear Information System (INIS)

    Cruz V, C.; Burruel I, S.E.; Orante B, V.R.; Grijalva M, H.; Perez S, R.; Bernal, R.

    2005-01-01

    In this work, we report the optically stimulated luminescence (OSL) dosimetry of new nano phosphors of ZnO obtained by thermal annealing of chemically synthesized ZnS powder. The synthesized ZnS nano powder was compressed in order to form pellet shaped pellets, which were afterwards subjected to a thermal annealing at 700 C during 24 h under air atmosphere. X-ray diffraction (XRD) patterns and energy-disperse X-ray Spectrometry (EDS) analyses confirmed the transformation of ZnS to ZnO. Samples were exposed to several doses of beta radiation up to 600 Gy, and the optically stimulated luminescence with 470 nm wavelength light was recorded as a function of dose. The intensity of the OSL signal increases by increasing dose, for what it is concluded that these new phosphor materials are suitable to be used in optically stimulated luminescence dosimetry. (Author)

  16. Thickness and microstructure effects in the optical and electrical properties of silver thin films

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Guowen, E-mail: gding@intermolecular.com; Clavero, César; Schweigert, Daniel; Le, Minh [Intermolecular, Inc., 3011 North First Street, San Jose, CA 95134 (United States)

    2015-11-15

    The optical and electrical response of metal thin films approaching thicknesses in the range of the electron mean free path is highly affected by electronic scattering with the interfaces and defects. Here, we present a theoretical and experimental study on how thickness and microstructure affect the properties of Ag thin films. We are able to successfully model the electrical resistivity and IR optical response using a thickness dependent electronic scattering time. Remarkably, the product of electronic scattering time and resistivity remains constant regardless of the thickness (τx ρ = C), with a value of 59 ± 2 μΩ cm ⋅ fs for Ag films in the investigated range from 3 to 74 nm. Our findings enable us to develop a theoretically framework that allows calculating the optical response of metal thin films in the IR by using their measured thickness and resistivity. An excellent agreement is found between experimental measurements and predicted values. This study also shows the theoretical lower limit for emissivity in Ag thin films according to their microstructure and thickness. Application of the model presented here will allow rapid characterization of the IR optical response of metal thin films, with important application in a broad spectrum of fundamental and industrial applications, including optical coatings, low-emissivity windows and semiconductor industry.

  17. Improved Thermal-Vacuum Compatible Flat Plate Radiometric Source For System-Level Testing Of Optical Sensors

    Science.gov (United States)

    Schwarz, Mark A.; Kent, Craig J.; Bousquet, Robert; Brown, Steven W.

    2016-01-01

    In this work, we describe an improved thermal-vacuum compatible flat plate radiometric source which has been developed and utilized for the characterization and calibration of remote optical sensors. This source is unique in that it can be used in situ, in both ambient and thermal-vacuum environments, allowing it to follow the sensor throughout its testing cycle. The performance of the original flat plate radiometric source was presented at the 2009 SPIE1. Following the original efforts, design upgrades were incorporated into the source to improve both radiometric throughput and uniformity. The pre-thermal-vacuum (pre-TVAC) testing results of a spacecraft-level optical sensor with the improved flat plate illumination source, both in ambient and vacuum environments, are presented. We also briefly discuss potential FPI configuration changes in order to improve its radiometric performance.

  18. Constructing nanoporous carbon nanotubes/Bi2Te3 composite for synchronous regulation of the electrical and thermal performances

    Science.gov (United States)

    Zhang, Qihao; Xu, Leilei; Zhou, Zhenxing; Wang, Lianjun; Jiang, Wan; Chen, Lidong

    2017-02-01

    Porous nanograined thermoelectric materials exhibit low thermal conductivity due to scattering of phonons by pores, which are favorable for thermoelectric applications. However, the benefit is not large enough to overcome the deficiency in the electrical performance. Herein, an approach is presented to reduce the thermal conductivity and synchronously enhance the electrical conductivity through constructing a nanoporous thermoelectric composite. Carbon nanotubes (CNTs) are truncated and homogeneously dispersed within the Bi2Te3 matrix by a cryogenic grinding (CG) technique for the first time, which efficiently suppress the Bi2Te3 grain growth and create nanopores with the size ranging from dozens to hundreds of nanometers. The lattice thermal conductivity is substantially decreased by broad wavelength phonon scattering resulting from nanopores, increased grain boundaries, and newly formed interfaces. Meanwhile, the electrical conductivity is improved due to the enhanced carrier mobility, which may originate from the bridging effect between the Bi2Te3 grains and CNTs. The maximum ZT is improved by almost a factor of 2 due to the simultaneous optimization of electrical and thermal performances. Our study demonstrates the superiority of constructing a bulk thermoelectric composite with nanopores by the uniform dispersion of CNTs through a CG technique for enhanced thermoelectric properties, which provides a wider approach to thermoelectric nanostructure engineering.

  19. Convective Heat Transfer Coefficients of Automatic Transmission Fluid Jets with Implications for Electric Machine Thermal Management: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Bennion, Kevin; Moreno, Gilberto

    2015-09-29

    Thermal management for electric machines (motors/ generators) is important as the automotive industry continues to transition to more electrically dominant vehicle propulsion systems. Cooling of the electric machine(s) in some electric vehicle traction drive applications is accomplished by impinging automatic transmission fluid (ATF) jets onto the machine's copper windings. In this study, we provide the results of experiments characterizing the thermal performance of ATF jets on surfaces representative of windings, using Ford's Mercon LV ATF. Experiments were carried out at various ATF temperatures and jet velocities to quantify the influence of these parameters on heat transfer coefficients. Fluid temperatures were varied from 50 degrees C to 90 degrees C to encompass potential operating temperatures within an automotive transaxle environment. The jet nozzle velocities were varied from 0.5 to 10 m/s. The experimental ATF heat transfer coefficient results provided in this report are a useful resource for understanding factors that influence the performance of ATF-based cooling systems for electric machines.

  20. Outdoor thermal and electrical characterisation of photovoltaic modules and systems

    OpenAIRE

    Herteleer, Bert

    2016-01-01

    Current and future investors in photovoltaic systems are interested in how well the system performs, and how predictable this is over the expected lifetime. To do so, models have been developed and measurements of photovoltaic systems have been done. This dissertation presents the outdoor measurement set-up that has been developed for thermal and electrical characterisation of photovoltaic modules and systems, aimed at measuring transient effects and changes. The main design decisions and ...

  1. Macroeconomic impact of the Solar Thermal Electricity Industry in Spain

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2011-10-15

    In the last three years, Solar Thermal Electricity (STE) in Spain has grown significantly. Its weight within the renewables mix is becoming relevant, and even more so, its impact on economics, society, the environment, and reducing energy dependence. This report was carried out by Deloitte for Protermosolar to quantitatively and qualitatively evaluate the main macroeconomic variables derived from the development of this technology in Spain from 2008 to 2010, and forecast its possible future impact.

  2. Fiber-Optic Thermal Sensor for TiN Film Crack Monitoring

    Directory of Open Access Journals (Sweden)

    Hsiang-Chang Hsu

    2017-11-01

    Full Text Available The study focuses on the thermal and temperature sensitivity behavior of an optical fiber sensor device. In this article, a titanium nitride (TiN-coated fiber Bragg grating (FBG sensor fabricated using an ion beam sputtering system was investigated. The reflection spectra of the FBG sensor were tested using R-soft optical software to simulate the refractive index sensitivity. In these experiments, the temperature sensitivity of the TiN FBG was measured at temperatures ranging from 100 to 500 °C using an optical spectrum analyzer (OSA. The results showed that the temperature sensitivity of the proposed TiN FBG sensor reached 12.8 pm/°C for the temperature range of 100 to 300 °C and 20.8 pm/°C for the temperature range of 300 to 500 °C. Additionally, we found that the produced oxidation at temperatures of 400-500 °C caused a crack, with the crack becoming more and more obvious at higher and higher temperatures.

  3. Mechatronics design and experimental verification of an electric-vehicle-based hybrid thermal management system

    Directory of Open Access Journals (Sweden)

    Yi-Hsuan Hung

    2016-02-01

    Full Text Available In this study, an electric-vehicle-based thermal management system was designed for dual energy sources. An experimental platform developed in a previous study was modified. Regarding the mechanical components, a heat exchanger with a radiator, proportional valve, coolant pipes, and coolant pump was appropriately integrated. Regarding the electric components, two heaters emulating waste heat were controlled using two programmable power supply machines. A rapid-prototyping controller with two temperature inputs and three outputs was designed. Rule-based control strategies were coded to maintain optimal temperatures for the emulated proton exchange membrane fuel cells and lithium batteries. To evaluate the heat power of dual energy sources, driving cycles, energy management control, and efficiency maps of energy sources were considered for deriving time-variant values. The main results are as follows: (a an advanced mechatronics platform was constructed; (b a driving cycle simulation was successfully conducted; and (c coolant temperatures reached their optimal operating ranges when the proportional valve, radiator, and coolant pump were sequentially controlled. The benefits of this novel electric-vehicle-based thermal management system are (a high-efficiency operation of energy sources, (b low occupied volume integrated with energy sources, and (c higher electric vehicle traveling mileage. This system will be integrated with real energy sources and a real electric vehicle in the future.

  4. Optical nonlinearities associated to applied electric fields in parabolic two-dimensional quantum rings

    International Nuclear Information System (INIS)

    Duque, C.M.; Morales, A.L.; Mora-Ramos, M.E.; Duque, C.A.

    2013-01-01

    The linear and nonlinear optical absorption as well as the linear and nonlinear corrections to the refractive index are calculated in a disc shaped quantum dot under the effect of an external magnetic field and parabolic and inverse square confining potentials. The exact solutions for the two-dimensional motion of the conduction band electrons are used as the basis for a perturbation-theory treatment of the effect of a static applied electric field. In general terms, the variation of one of the different potential energy parameters – for a fixed configuration of the remaining ones – leads to either blueshifts or redshifts of the resonant peaks as well as to distinct rates of change for their amplitudes. -- Highlights: • Optical absorption and corrections to the refractive in quantum dots. • Electric and magnetic field and parabolic and inverse square potentials. • Perturbation-theory treatment of the effect of the electric field. • Induced blueshifts or redshifts of the resonant peaks are studied. • Evolution of rates of change for amplitudes of resonant peaks

  5. Optical nonlinearities associated to applied electric fields in parabolic two-dimensional quantum rings

    Energy Technology Data Exchange (ETDEWEB)

    Duque, C.M., E-mail: cduque@fisica.udea.edu.co [Instituto de Física, Universidad de Antioquia, AA 1226, Medellín (Colombia); Morales, A.L. [Instituto de Física, Universidad de Antioquia, AA 1226, Medellín (Colombia); Mora-Ramos, M.E. [Instituto de Física, Universidad de Antioquia, AA 1226, Medellín (Colombia); Facultad de Ciencias, Universidad Autónoma del Estado de Morelos, Ave. Universidad 1001, CP 62209, Cuernavaca, Morelos (Mexico); Duque, C.A. [Instituto de Física, Universidad de Antioquia, AA 1226, Medellín (Colombia)

    2013-11-15

    The linear and nonlinear optical absorption as well as the linear and nonlinear corrections to the refractive index are calculated in a disc shaped quantum dot under the effect of an external magnetic field and parabolic and inverse square confining potentials. The exact solutions for the two-dimensional motion of the conduction band electrons are used as the basis for a perturbation-theory treatment of the effect of a static applied electric field. In general terms, the variation of one of the different potential energy parameters – for a fixed configuration of the remaining ones – leads to either blueshifts or redshifts of the resonant peaks as well as to distinct rates of change for their amplitudes. -- Highlights: • Optical absorption and corrections to the refractive in quantum dots. • Electric and magnetic field and parabolic and inverse square potentials. • Perturbation-theory treatment of the effect of the electric field. • Induced blueshifts or redshifts of the resonant peaks are studied. • Evolution of rates of change for amplitudes of resonant peaks.

  6. Estimation of Equivalent Thermal Conductivity for Impregnated Electrical Windings Formed from Profiled Rectangular Conductors

    OpenAIRE

    Ayat, Sabrina S; Wrobel, Rafal; Goss, James; Drury, David

    2016-01-01

    In order to improve accuracy and reduce model setting-up, and solving time in thermal analysis of electrical machines, transformers and wound passive components, the multi-material winding region is frequently homogenised. The existing winding homogenization techniques are predo-minantly focused on winding constructions with round conductors, where thermal conductivity across conductors is usually assumed to be isotropic. However, for the profiled rectangular conductors that assumption is no ...

  7. Optically resonant magneto-electric cubic nanoantennas for ultra-directional light scattering

    Energy Technology Data Exchange (ETDEWEB)

    Sikdar, Debabrata, E-mail: debabrata.sikdar@monash.edu; Premaratne, Malin [Advanced Computing and Simulation Laboratory (A chi L), Department of Electrical and Computer Systems Engineering, Monash University, Clayton 3800, Victoria (Australia); Cheng, Wenlong [Department of Chemical Engineering, Faculty of Engineering, Monash University, Clayton 3800, Victoria (Australia); The Melbourne Centre for Nanofabrication, 151 Wellington Road, Clayton 3168, Victoria (Australia)

    2015-02-28

    Cubic dielectric nanoparticles are promising candidates for futuristic low-loss, ultra-compact, nanophotonic applications owing to their larger optical coefficients, greater packing density, and relative ease of fabrication as compared to spherical nanoparticles; besides possessing negligible heating at nanoscale in contrast to their metallic counterparts. Here, we present the first theoretical demonstration of azimuthally symmetric, ultra-directional Kerker's-type scattering of simple dielectric nanocubes in visible and near-infrared regions via simultaneous excitation and interference of optically induced electric- and magnetic-resonances up to quadrupolar modes. Unidirectional forward-scattering by individual nanocubes is observed at the first generalized-Kerker's condition for backward-scattering suppression, having equal electric- and magnetic-dipolar responses. Both directionality and magnitude of these unidirectional-scattering patterns get enhanced where matching electric- and magnetic-quadrupolar responses spectrally overlap. While preserving azimuthal-symmetry and backscattering suppression, a nanocube homodimer provides further directionality improvement for increasing interparticle gap, but with reduced main-lobe magnitude due to emergence of side-scattering lobes from diffraction-grating effect. We thoroughly investigate the influence of interparticle gap on scattering patterns and propose optimal range of gap for minimizing side-scattering lobes. Besides suppressing undesired side-lobes, significant enhancement in scattering magnitude and directionality is attained with increasing number of nanocubes forming a linear chain. Optimal directionality, i.e., the narrowest main-scattering lobe, is found at the wavelength of interfering quadrupolar resonances; whereas the largest main-lobe magnitude is observed at the wavelength satisfying the first Kerker's condition. These unique optical properties of dielectric nanocubes thus can

  8. Structural, optical and electrical characterization of ITO, ITO/Ag and ITO/Ni transparent conductive electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Ali, Ahmad Hadi, E-mail: ahadi@uthm.edu.my [Nano-Optoelectronics Research and Technology Laboratory, School of Physics, Universiti Sains Malaysia, Penang (Malaysia); Science Department, Faculty of Science, Technology and Human Development, Universiti Tun Hussein Onn Malaysia, Johor (Malaysia); Shuhaimi, Ahmad [Low Dimensional Materials Research Centre, Department of Physics, Faculty of Science, Universiti Malaya, Kuala Lumpur (Malaysia); Hassan, Zainuriah [Nano-Optoelectronics Research and Technology Laboratory, School of Physics, Universiti Sains Malaysia, Penang (Malaysia)

    2014-01-01

    We report on the transparent conductive oxides (TCO) characteristics based on the indium tin oxides (ITO) and ITO/metal thin layer as an electrode for optoelectronics device applications. ITO, ITO/Ag and ITO/Ni were deposited on Si and glass substrate by thermal evaporator and radio frequency (RF) magnetron sputtering at room temperature. Post deposition annealing was performed on the samples in air at moderate temperature of 500 °C and 600 °C. The structural, optical and electrical properties of the ITO and ITO/metal were characterized using X-ray diffraction (XRD), UV–Vis spectrophotometer, Hall effect measurement system and atomic force microscope (AFM). The XRD spectrum reveals significant polycrystalline peaks of ITO (2 2 2) and Ag (1 1 1) after post annealing process. The post annealing also improves the visible light transmittance and electrical resistivity of the samples. Figure of merit (FOM) of the ITO, ITO/Ag and ITO/Ni were determined as 5.5 × 10{sup −3} Ω{sup −1}, 8.4 × 10{sup −3} Ω{sup −1} and 3.0 × 10{sup −5} Ω{sup −1}, respectively. The results show that the post annealed ITO with Ag intermediate layer improved the efficiency of the transparent conductive electrodes (TCE) as compared to the ITO and ITO/Ni.

  9. 160 MeV Ni12+ ion irradiation effects on the structural, optical and electrical properties of spherical polypyrrole nanoparticles

    International Nuclear Information System (INIS)

    Hazarika, J.; Kumar, A.

    2014-01-01

    Highlights: • Upon SHI irradiation the average diameters of PPy nanoparticles increases. • Crystallinity of PPy nanoparticles increases with increasing ion fluence. • IR active vibrational bands have different cross sections for SHI irradiation. • Upon SHI irradiation optical band gap energy of PPy nanoparticles decreases. • Upon SHI irradiation thermal stability of PPy nanoparticles increases. -- Abstract: In this study we report 160 MeV Ni 12+ swift heavy ion irradiation induced enhancement in the structural, optical and electrical properties of spherical polypyrrole (PPy) nanoparticles. High resolution transmission electron microscope results show that the pristine PPy nanoparticles have an average diameter of 11 nm while upon irradiation the average diameter increases to 18 nm at the highest ion fluence of 1 × 10 12 ions/cm 2 . X-ray diffraction studies show an enhancement of crystallinity and average crystallite size of PPy nanoparticles with increasing fluence. Studies of Fourier transform infrared spectra suggest the structural modifications of different functional groups upon irradiation. It also reveals that different functional groups have different sensitivity to irradiation. The infrared active N–H vibrational band at 3695 cm −1 is more sensitive to irradiation with a formation cross-section of 5.77 × 10 −13 cm 2 and effective radius of 4.28 nm. The UV–visible absorption spectra of PPy nanoparticles show that the absorption band undergoes a red shift with increasing fluence. Moreover upon irradiation the optical band gap energy decreases and Urbach’s energy increases with fluence. Thermo-gravimetric analysis studies suggest that upon irradiation the thermal stability of PPy nanoparticles increases which may be attributed to their enhanced crystallinity. Current–voltage characteristics of PPy nanoparticles exhibit non-Ohmic, symmetric behavior which increases with fluence

  10. Optical transparency and electrical conductivity of nonstoichiometric ultrathin InxOy films

    International Nuclear Information System (INIS)

    Joseph, Shay; Berger, Shlomo

    2011-01-01

    The effect of thickness and composition on the electrical conductivity and optical transparency, mainly in the infrared, of ultrathin In x O y films was studied. In x O y films 35-470 A thick with oxygen atomic fractions of ∼0.3 and ∼0.5 were prepared via dc magnetron sputtering. All films were polycrystalline, consisting of only the cubic bixbiyte phase of In 2 O 3 . The average grain size of the films increased from 30 to 95 nm as the film thickness increased. The weak dependence of the electrical conductivity on the frequency and the low activation energies for conduction, a few hundredths of an eV, provided an indication that free band conduction was the primary electrical conduction mechanism in the case of all ultrathin In x O y films. It was found that introducing a high degree of nonstoichiometry in the form of oxygen deficiency did not help improve the electrical conductivity, since not all vacancies contributed two free electrons for conduction and due to impurity scattering. The optical nature of these films, studied mainly by ellipsometry, was found to be dependent on the film's composition and thickness. In the infrared, the dielectric function of all In x O y films was consistent with the Drude model, inferring that the transparency loss in this region was a result of free charge carriers. In the visible however, In x O y films under 170 A, which had an oxygen atomic fraction of ∼0.5, were modeled by extending the Drude model to the shorter wavelengths. Films over 170 A, with the same composition, were modeled using the Cauchy dispersion model, meaning that no absorption was measured. These results indicate that, optically, under specific compositions, ultrathin In x O y films undergo a transition from metalliclike behavior to dielectric behavior with increasing film thickness. Using a figure of merit approach, it was determined that a nonstoichiometric 230 A thick In x O y film, with an oxygen atomic fraction of ∼0.3, had the best combination

  11. Modeling of thermal spalling during electrical discharge machining of titanium diboride

    International Nuclear Information System (INIS)

    Gadalla, A.M.; Bozkurt, B.; Faulk, N.M.

    1991-01-01

    Erosion in electrical discharge machining has been described as occurring by melting and flushing the liquid formed. Recently, however, thermal spalling was reported as the mechanism for machining refractory materials with low thermal conductivity and high thermal expansion. The process is described in this paper by a model based on a ceramic surface exposed to a constant circular heating source which supplied a constant flux over the pulse duration. The calculations were based on TiB 2 mechanical properties along a and c directions. Theoretical predictions were verified by machining hexagonal TiB 2 . Large flakes of TiB 2 with sizes close to grain size and maximum thickness close to the predicted values were collected, together with spherical particles of Cu and Zn eroded from cutting wire. The cutting surfaces consist of cleavage planes sometimes contaminated with Cu, Zn, and impurities from the dielectric fluid

  12. Electrical and optical co-stimulation in the deaf white cat

    Science.gov (United States)

    Cao, Zhiping; Xu, Yingyue; Tan, Xiaodong; Suematsu, Naofumi; Robinson, Alan; Richter, Claus-Peter

    2018-02-01

    Spatial selectivity of neural stimulation with photons, such as infrared neural stimulation (INS) is higher than the selectivity obtained with electrical stimulation. To obtain more independent channels for stimulation in neural prostheses, INS may be implemented to better restore the fidelity of the damaged neural system. However, irradiation with infrared light also bares the risk of heat accumulation in the target tissue with subsequent neural damage. Lowering the threshold for stimulation could reduce the amount of heat delivered to the tissue and the risk for subsequent tissue damage. It has been shown in the rat sciatic nerve that simultaneous irradiation with infrared light and the delivery of biphasic sub-threshold electrical pulses can reduce the threshold for INS [1]. In this study, deaf white cats have been used to test whether opto-electrical co-stimulation can reduce the stimulation threshold for INS in the auditory system too. The cochleae of the deaf white cats have largely reduced spiral ganglion neuron counts and significant degeneration of the organ of Corti and do not respond to acoustic stimuli. Combined electrical and optical stimulation was used to demonstrate that simultaneous stimulation with infrared light and biphasic electrical pulses can reduce the threshold for stimulation.

  13. Assessment of optical performance of three non-tracking, non-imaging, external compound parabolic concentrators designed for high temperature solar thermal collector units

    OpenAIRE

    Cisneros, Jesus

    2010-01-01

    The objective of this thesis is to perform a preliminary optical assessment of the external compound parabolic concentrator (XCPC) component in three concentrating solar thermal units. Each solar thermal unit consists an optical element (the non-imaging concentrating reflector) and a thermal element (the evacuated glass tube solar absorber). The three concentrating solar thermal units discussed in this work are DEWAR 58, a direct flow all-glass dewar, DEWAR 47 an indirect flow ...

  14. Optical absorption and thermal transport of individual suspended carbon nanotube bundles.

    Science.gov (United States)

    Hsu, I-Kai; Pettes, Michael T; Bushmaker, Adam; Aykol, Mehmet; Shi, Li; Cronin, Stephen B

    2009-02-01

    A focused laser beam is used to heat individual single-walled carbon nanotube bundles bridging two suspended microthermometers. By measurement of the temperature rise of the two thermometers, the optical absorption of 7.4-10.3 nm diameter bundles is found to be between 0.03 and 0.44% of the incident photons in the 0.4 microm diameter laser spot. The thermal conductance of the bundle is obtained with the additional measurement of the temperature rise of the nanotubes in the laser spot from shifts in the Raman G band frequency. According to the nanotube bundle diameter determined by transmission electron microscopy, the thermal conductivity is obtained.

  15. A review on battery thermal management in electric vehicle application

    Science.gov (United States)

    Xia, Guodong; Cao, Lei; Bi, Guanglong

    2017-11-01

    The global issues of energy crisis and air pollution have offered a great opportunity to develop electric vehicles. However, so far, cycle life of power battery, environment adaptability, driving range and charging time seems far to compare with the level of traditional vehicles with internal combustion engine. Effective battery thermal management (BTM) is absolutely essential to relieve this situation. This paper reviews the existing literature from two levels that are cell level and battery module level. For single battery, specific attention is paid to three important processes which are heat generation, heat transport, and heat dissipation. For large format cell, multi-scale multi-dimensional coupled models have been developed. This will facilitate the investigation on factors, such as local irreversible heat generation, thermal resistance, current distribution, etc., that account for intrinsic temperature gradients existing in cell. For battery module based on air and liquid cooling, series, series-parallel and parallel cooling configurations are discussed. Liquid cooling strategies, especially direct liquid cooling strategies, are reviewed and they may advance the battery thermal management system to a new generation.

  16. Fiber Optic Temperature Sensors in TPS: Arc Jet Model Design & Testing

    Science.gov (United States)

    Black, Richard; Feldman, Jay; Ellerby, Donald; Monk, Joshua; Moslehi, Behzad; Oblea, Levy; Switzer, Matthew

    2017-01-01

    Techniques for using fiber optics with Fiber Bragg Gratings (FBGs) have been developed by IFOS Corp. for use in thermal protection systems (TPS) on spacecraft heat shield materials through NASA Phase 1 and 2 SBIR efforts and have been further improved in a recent collaboration between IFOS and NASA that will be described here. Fiber optic temperature sensors offer several potential advantages over traditional thermocouple sensors including a) multiplexing many sensors in a single fiber to increase sensor density in a given array or to provide spatial resolution, b) improved thermal property match between sensor and TPS to reduce heat flow disruption, c) lack of electrical conductivity.

  17. Exergy analysis of thermal management system for range-extended electric vehicles

    Energy Technology Data Exchange (ETDEWEB)

    Hamut, H. S.; Dincer, I.; Naterer, G. F. [Faculty of Engineering and Applied Science, University of Ontario Institute of Technology (Canada)], email: Ibrahim.Dincer@uoit.ca

    2011-07-01

    In the last few decades, the energy crisis, increasing gas prices and concerns over environmental pollution have encouraged the development of electric vehicle (EV) and hybrid electric vehicle (HEV) technologies. In this paper, a thermal management system (TMS) installed in a range-extended electric vehicle is examined and is found to have a substantial impact on battery efficiency and vehicle performance. An exergy analysis was conducted on the refrigeration and coolant circuits and the Coefficient of Performance (COP) of the baseline system was determined to be 2.0 with a range of 1.8 to 2.4. The overall exergy was found to be 32% with a range of 26% to 39%. Ambient temperature had the largest impact on overall exergy efficiency but there is a need to further investigate temperature effects on battery efficiency, since the battery's performance has such a high impact on vehicle performance overall.

  18. Thermal and electrical energy yield analysis of a directly water cooled photovoltaic module

    Directory of Open Access Journals (Sweden)

    Mtunzi Busiso

    2016-01-01

    Full Text Available Electrical energy of photovoltaic modules drops by 0.5% for each degree increase in temperature. Direct water cooling of photovoltaic modules was found to give improved electrical and thermal yield. A prototype was put in place to analyse the field data for a period of a year. The results showed an initial high performance ratio and electrical power output. The monthly energy saving efficiency of the directly water cooled module was found to be approximately 61%. The solar utilisation of the naturally cooled photovoltaic module was found to be 8.79% and for the directly water cooled module its solar utilisation was 47.93%. Implementation of such systems on households may reduce the load from the utility company, bring about huge savings on electricity bills and help in reducing carbon emissions.

  19. The effects of thermal annealing in structural and optical properties of RF sputtered amorphous silicon

    International Nuclear Information System (INIS)

    Abdul Fatah Awang Mat

    1988-01-01

    The effect of thermal annealing on structural and optical properties of amorphous silicon are studied on samples prepared by radio-frequency sputtering. The fundamental absorption edge of these films are investigated at room temperature and their respective parameters estimated. Annealing effect on optical properties is interpreted in terms of the removal of voids and a decrease of disorder. (author)

  20. The influence of temperature calibration on the OC–EC results from a dual-optics thermal carbon analyzer

    Science.gov (United States)

    The Sunset Laboratory Dual-Optical Carbonaceous Analyzer that simultaneously measures transmission and reflectance signals is widely used in thermal-optical analysis of particulate matter samples. Most often this instrument is used to measure total carbon (TC), organic carbon (O...

  1. Computer modeling of the combined effects of perfusion, electrical conductivity, and thermal conductivity on tissue heating patterns in radiofrequency tumor ablation.

    Science.gov (United States)

    Ahmed, Muneeb; Liu, Zhengjun; Humphries, Stanley; Goldberg, S Nahum

    2008-11-01

    To use an established computer simulation model of radiofrequency (RF) ablation to characterize the combined effects of varying perfusion, and electrical and thermal conductivity on RF heating. Two-compartment computer simulation of RF heating using 2-D and 3-D finite element analysis (ETherm) was performed in three phases (n = 88 matrices, 144 data points each). In each phase, RF application was systematically modeled on a clinically relevant template of application parameters (i.e., varying tumor and surrounding tissue perfusion: 0-5 kg/m(3)-s) for internally cooled 3 cm single and 2.5 cm cluster electrodes for tumor diameters ranging from 2-5 cm, and RF application times (6-20 min). In the first phase, outer thermal conductivity was changed to reflect three common clinical scenarios: soft tissue, fat, and ascites (0.5, 0.23, and 0.7 W/m- degrees C, respectively). In the second phase, electrical conductivity was changed to reflect different tumor electrical conductivities (0.5 and 4.0 S/m, representing soft tissue and adjuvant saline injection, respectively) and background electrical conductivity representing soft tissue, lung, and kidney (0.5, 0.1, and 3.3 S/m, respectively). In the third phase, the best and worst combinations of electrical and thermal conductivity characteristics were modeled in combination. Tissue heating patterns and the time required to heat the entire tumor +/-a 5 mm margin to >50 degrees C were assessed. Increasing background tissue thermal conductivity increases the time required to achieve a 50 degrees C isotherm for all tumor sizes and electrode types, but enabled ablation of a given tumor size at higher tissue perfusions. An inner thermal conductivity equivalent to soft tissue (0.5 W/m- degrees C) surrounded by fat (0.23 W/m- degrees C) permitted the greatest degree of tumor heating in the shortest time, while soft tissue surrounded by ascites (0.7 W/m- degrees C) took longer to achieve the 50 degrees C isotherm, and complete ablation

  2. Structural, optical and electrical characterization of Ag doped lead chalcogenide (PbSe) thin films

    Energy Technology Data Exchange (ETDEWEB)

    Al-Ghamdi, A.A., E-mail: aghamdi90@hotmail.com [Department of Physics, Faculty of Science, King Abdulaziz University, Jeddah (Saudi Arabia); Al-Heniti, S. [Department of Physics, Faculty of Science, King Abdulaziz University, Jeddah (Saudi Arabia); Khan, Shamshad A. [Department of Physics, St. Andrew' s College, Gorakhpur, UP (India)

    2013-03-15

    Research and development efforts are currently underway to fabricate a variety of solid state devices. A good deal of information regarding the synthesis, structural, optical and electrical properties of Ag doped lead chalcogenides have been revealed. The bulk polycrystalline (PbSe){sub 100-x}Ag{sub x} ternary chalcogenides are prepared by diffusion technique. The XRD patterns recorded for the (PbSe){sub 100-x}Ag{sub x} thin films prepared by vacuum deposition technique, show that these films are polycrystalline in nature. The optical measurements reveal that the (PbSe){sub 100-x}Ag{sub x} thin films possess direct band gap and the band gap energy decreases with an increase of Ag concentration. The extinction coefficient (k) and refractive index (n) are found to be changing by increasing Ag concentration in PbSe. These results are interpreted in terms of the change in concentration of localized states due to the shift in Fermi level. The dc conductivities of (PbSe){sub 100-x}Ag{sub x} thin films are measured in temperature range 303-403 K. It is observed that the dc conductivity increases at all the temperatures with an increase of Ag content in PbSe system. The experimental data suggests that the conduction is due to thermally assisted tunneling of the charge carriers in the localized states near the band edges. The activation energy and optical band gap are found to decrease with increasing Ag concentration in lead chalcogenide and there are good agreements between these two values. - Highlights: Black-Right-Pointing-Pointer (PbSe){sub 100-x}Ag{sub x} thin films has been investigated. Black-Right-Pointing-Pointer Polycrystalline nature has been verified by X-ray diffraction. Black-Right-Pointing-Pointer Optical absorption data showed the rules of direct transitions predominate. Black-Right-Pointing-Pointer Dc conductivity increases with an increase of Ag content in PbSe system. Black-Right-Pointing-Pointer Increase of Ag concentration causes a decrease in E{sub g

  3. Effect of annealing time on optical and electrical properties of CdS thin films

    Science.gov (United States)

    Soliya, Vanshika; Tandel, Digisha; Patel, Chandani; Patel, Kinjal

    2018-05-01

    Cadmium sulphide (CdS) is semiconductor compound of II-VI group. Thin film of CdS widely used in the applications such as, a buffer layer in copper indium diselenide (CIS) hetrojunction based solar cells, transistors, photo detectors and light emitting diodes. Because of the ease of making like chemical bath deposition (CBD), screen printing and thermal evaporation. It is extensively used in the CIS based solar cells as a buffer layers. The buffer layers usually used for reducing the interface recombination of the photo generated carriers by means of improving the lattice mismatch between the layers. The optimum thickness and the optoelectronics properties of CdS thin films like, optical band gap, electrical resistivity, structure, and composition etc., are to be considering for its use as a buffer layer. In the present study the CdS thin film were grown by simple dip coating method. In this method we had prepared 0.1M Cadmium-thiourea precursor solution. Before the deposition process of CdS, glass substrate has been cleaned using Methanol, Acetone, Trichloroethylene and De-ionized (DI) water. After coating of precursor layer, it was heated at 200 °C for themolysis. Then after CdS films were annealed at 200 °C for different time and studied its influence on the optical transmission, band gap, XRD, raman and the electrical resistivity. As increasing the annealing time we had observed the average transmission of the films was reduce after the absorption edge. In addition to the blue shift of absorption edge was observed. The observed optimum band gap was around 2.50 eV. XRD and raman analysis confirms the cubuc phase of CdS. Hot probe method confirms the n-type conductivity of the CdS film. Hall probe data shows the resistivity of the films was in the order of 103 Ωcm. Observed data signifies its future use in the many optoelectronics devices.

  4. Understanding the electric field control of the electronic and optical properties of strongly-coupled multi-layered quantum dot molecules.

    Science.gov (United States)

    Usman, Muhammad

    2015-10-21

    Strongly-coupled quantum dot molecules (QDMs) are widely employed in the design of a variety of optoelectronic, photovoltaic, and quantum information devices. An efficient and optimized performance of these devices demands engineering of the electronic and optical properties of the underlying QDMs. The application of electric fields offers a way to realise such a control over the QDM characteristics for a desired device operation. We performed multi-million-atom atomistic tight-binding calculations to study the influence of electric fields on the electron and hole wave function confinements and symmetries, the ground-state transition energies, the band-gap wavelengths, and the optical transition modes. Electrical fields parallel (Ep) and anti-parallel (Ea) to the growth direction were investigated to provide a comprehensive guide for understanding the electric field effects. The strain-induced asymmetry of the hybridized electron states is found to be weak and can be balanced by applying a small Ea electric field, of the order of 1 kV cm(-1). The strong interdot couplings completely break down at large electric fields, leading to single QD states confined at the opposite edges of the QDM. This mimics a transformation from a type-I band structure to a type-II band structure for the QDMs, which is a critical requirement for the design of intermediate-band solar cells (IBSCs). The analysis of the field-dependent ground-state transition energies reveals that the QDM can be operated both as a high dipole moment device by applying large electric fields and as a high polarizability device under the application of small electric field magnitudes. The quantum confined Stark effect (QCSE) red shifts the band-gap wavelength to 1.3 μm at the 15 kV cm(-1) electric field; however the reduced electron-hole wave function overlaps lead to a decrease in the interband optical transition strengths by roughly three orders of magnitude. The study of the polarisation-resolved optical

  5. Electrical, thermal and magnetic behaviour of the metallic glass Fe80B20 in the crystallization process

    International Nuclear Information System (INIS)

    Isalgue, A.; Cusido, J.A.

    1986-01-01

    The thermal, electrical DC conductivity and magnetic properties have been studied in the crystallization process of the metallic glass Fe 80 B 20 (Metglass 2605) induced by heat treatment. The electrical and thermal conductivity, the coercive force and the remanence are strongly affected with the crystallization of the glass. Two steps can be dicerned from the magnetic measurements; the differences between the two steps are interpreted in the basis of the ''spherulite-type'', grown of Fe 3 B in the first crystallization step and the aparition of Fe 2 B in the second step. (author)

  6. Imaging axial and radial electric field components in dielectric targets under plasma exposure

    NARCIS (Netherlands)

    Slikboer, E.T.; Sobota, A.; Guaitella, O.; Garcia-Caurel, E.

    2018-01-01

    This work presents new ways to investigate the individual electric field components in a dielectric target induced by a non thermal atmospheric pressure plasma jet. Mueller polarimetry is applied to investigate electro-optic crystals under exposure of guided ionization waves produced by a plasma

  7. Electrical and Optical Characterization of Nanowire based Semiconductor Devices

    Science.gov (United States)

    Ayvazian, Talin

    This research project is focused on a new strategy for the creation of nanowire based semiconductor devices. The main goal is to understand and optimize the electrical and optical properties of two types of nanoscale devices; in first type lithographically patterned nanowire electrodeposition (LPNE) method has been utilized to fabricate nanowire field effect transistors (NWFET) and second type involved the development of light emitting semiconductor nanowire arrays (NWLED). Field effect transistors (NWFETs) have been prepared from arrays of polycrystalline cadmium selenide (pc-CdSe) nanowires using a back gate configuration. pc-CdSe nanowires were fabricated using the lithographically patterned nanowire electrode- position (LPNE) process on SiO2 /Si substrates. After electrodeposition, pc-CdSe nanowires were thermally annealed at 300 °C x 4 h either with or without exposure to CdCl 2 in methanol a grain growth promoter. The influence of CdCl2 treatment was to increase the mean grain diameter as determined by X-ray diffraction pattern and to convert the crystal structure from cubic to wurtzite. Transfer characteristics showed an increase of the field effect mobility (mu eff) by an order of magnitude and increase of the Ion/I off ratio by a factor of 3-4. Light emitting devices (NW-LED) based on lithographically patterned pc-CdSe nanowire arrays have been investigated. Electroluminescence (EL) spectra of CdSe nanowires under various biases exhibited broad emission spectra centered at 750 nm close to the band gap of CdSe (1.7eV). To enhance the intensity of the emitted light and the external quantum efficiency (EQE), the distance between the contacts were reduced from 5 mum to less than 1 mum which increased the efficiency by an order of magnitude. Also, increasing the annealing temperature of nanowires from 300 °C x4 h to 450 This research project is focused on a new strategy for the creation of nanowire based semiconductor devices. The main goal is to understand

  8. Photovoltaic. Solar thermal. Solar thermal electricity

    International Nuclear Information System (INIS)

    2009-01-01

    The year 2008 was excellent for solar energy in the European Union. The growth of the installed capacity for photovoltaic was +159% (it means +4747.018 MW) to reach 9689.952 MW and that for solar thermal was +51.5% (it means +3172.5 MW) to reach 19982.7 MW. Worldwide concentrated solar thermal capacity stood at 679 MW in 2009, while this figure may seem low, the sector has a promising future ahead of it. (A.C.)

  9. Lightning Strike Ablation Damage Influence Factors Analysis of Carbon Fiber/Epoxy Composite Based on Coupled Electrical-Thermal Simulation

    Science.gov (United States)

    Yin, J. J.; Chang, F.; Li, S. L.; Yao, X. L.; Sun, J. R.; Xiao, Y.

    2017-10-01

    According to the mathematical analysis model constructed on the basis of energy-balance relationship in lightning strike, and accompany with the simplified calculation strategy of composite resin pyrolysis degree dependent electrical conductivity, an effective three dimensional thermal-electrical coupling analysis finite element model of composite laminate suffered from lightning current was established based on ABAQUS, to elucidate the effects of lighting current waveform parameters and thermal/electrical properties of composite laminate on the extent of ablation damage. Simulated predictions agree well with the composite lightning strike directed effect experimental data, illustrating the potential accuracy of the constructed model. The analytical results revealed that extent of composite lightning strike ablation damage can be characterized by action integral validly, there exist remarkable power function relationships between action integral and visual damage area, projected damage area, maximum damage depth and damage volume of ablation damage, and enhancing the electrical conductivity and specific heat of composite, ablation damage will be descended obviously, power function relationships also exist between electrical conductivity, specific heat and ablation damage, however, the impact of thermal conductivity on the extent of ablation damage is not notable. The conclusions obtained provide some guidance for composite anti-lightning strike structure-function integration design.

  10. An optical, electro-optic and thermal characterisation of various organic crystals

    International Nuclear Information System (INIS)

    Lochran, Stephen

    1997-01-01

    The organic materials S - 3 - methyl - 5 - nitro - N - (1 - phenylethyl) - 2 - pyridinamine [3- methyl-MBANP] and S - N - methyl - 5 - nitro - N -(1 - phenylethyl) - 2 - pyridinamine [N- methyl-MBANP] belong to a family of compounds based on the 2-(α-methylbenzylamino)-5- nitropyridine molecule and were identified as promising nonlinear optical materials by the powder disk test. Large single crystals were grown from solution for N-methyl-MBANP, which crystallises in a monoclinic space group, and from the melt and solution for 3-methyl-MBANP which crystallises in an orthorhombic space group. Orthoscopic examination of N-methyl-MBANP revealed no dispersion of the dielectric axes unlike the parent molecule and the position of the dielectric axes was correlated with the molecular structure. Preparation of prisms from single crystals of both materials facilitated the measurement of refractive indices in the visible and the near infra-red. The values obtained were correlated with the crystal structure and a Sellmeier equation fitted to each of the dispersion curves. The nonlinear optical properties of both materials were evaluated by use of the Maker fringe technique and phase matched intensities. By means of these two methods, the full nonlinear d ij tensor was obtained for both materials at a fundamental wavelength of 1064nm. The linear electro-optic properties of N-methyl-MBANP were evaluated using a conoscopic experiment and correlated with the crystal structure together with the magnitude of all non-zero elements in the d ij tensor. Separately, the thermal properties of N-methylurea (NMU), 4-nitro-4'-methylbenzylidene aniline (NMBA) and Zinc TrisThiourea Sulfate (ZTS) were evaluated and all correlated with the crystal structure and bonding. (author)

  11. Optical, electrical and sensing properties of β-ketoimine calix[4]arene thin films

    Energy Technology Data Exchange (ETDEWEB)

    Echabaane, M., E-mail: mosaab.echabaane@yahoo.fr [Laboratoire des Interfaces et Matériaux Avancés (LIMA), Faculté des Sciences de Monastir, Avenue de l' environnement, 5000 Monastir (Tunisia); Rouis, A. [Laboratoire des Interfaces et Matériaux Avancés (LIMA), Faculté des Sciences de Monastir, Avenue de l' environnement, 5000 Monastir (Tunisia); Bonnamour, I. [Institut de Chimie and Biochimie Moléculaires and Supramoléculaires (ICBMS), UMR CNRS 5246, 43 Boulevard du 11 Novembre 1918, Université Claude Bernard Lyon 1, 69100 Villeurbanne (France); Ben Ouada, H. [Laboratoire des Interfaces et Matériaux Avancés (LIMA), Faculté des Sciences de Monastir, Avenue de l' environnement, 5000 Monastir (Tunisia)

    2013-09-16

    Optical, electrical and ion sensing properties of β-ketoimine calix[4]arene thin films have been investigated. These calix[4]arene derivative films exhibit absorption spectra with a resolved electronic structure in the UV–vis and the energy gap was found to be 3.65 eV. Electrical properties of ITO/β-ketoimine calix[4]arene/Al devices have been investigated by I–V characteristics and impedance spectroscopy measurements. The conduction is governed by space-charge-limited current (SCLC) mechanism. The impedance spectroscopy study showed a hopping transport process, a typical behavior of disordered materials. The device was modeled by a single parallel resistor and capacitor network in series with a resistance. The β-ketoimine calix[4]arene was used for the conception of the novel optical chemical sensor and the detection of Cu{sup 2+} ions was monitored by UV–visible spectroscopy. The linear dynamic range for the determination of Cu{sup 2+} has been 10{sup −5}–10{sup −3.7} M with a detection limit of 10{sup −5} M. The characteristics of this optode such as regeneration, repeatability, reproducibility, short-term stability, life time and ion selectivity have been discussed. - Highlights: • We examine optical properties of β-ketoimine calix[4]arene ligand. • We investigate the electric properties of ITO/β-ketoimine calix[4]arene/Al device. • We study the sensing properties of optode films for the detection of copper (II)

  12. Physical factors affecting the electrically assisted thermal bitumen recovery

    Energy Technology Data Exchange (ETDEWEB)

    Bogdanov, I.I.; Torres, J.-A.; Kamp, A.M. [CHLOE, University of Pau (France); Corre, B. [CSTJF, Total (France)

    2011-07-01

    In the heavy oil industry, thermal processes are used to enhance oil recovery by increasing the reservoir temperature which results in better oil mobility. Low frequency heating (LFH) is a technology using electrical conductivity of connate water to propagate current between electrodes, thus generating heat in the reservoir through the Joule effect. During the preheating and production periods, many physical factors may affect the LFH process and the aim of this study was to determine which factors affect the process and how, using a particular pattern of electrodes. Simulations were conducted using the CMG Stars reservoir simulator under different configurations, conditions and parameters. Important physical properties and operational conditions affecting the LFH process were determined and results showed that convection heat, bulk electrical conductivity and power distribution can be improved by salt water circulation. This paper highlighted the physical factors affecting LFH efficiency and these findings will be useful for future process design.

  13. Crystal growth and structure, electrical, and optical characterization of the semiconductor Cu2SnSe3

    International Nuclear Information System (INIS)

    Marcano, G.; Rincon, C.; Chalbaud, L. M. de; Bracho, D. B.; Perez, G. Sanchez

    2001-01-01

    X-ray powder diffraction by p-type Cu 2 SnSe 3 , prepared by the vertical Bridgman--Stockbarger technique, shows that this material crystallizes in a monoclinic structure, space group Cc, with unit cell parameters a=6.5936(1)Aa, b=12.1593(4)Aa, c=6.6084(3)Aa, and β=108.56(2) o . The temperature variation of the hole concentration p obtained from the Hall effect and electrical resistivity measurements from about 160 to 300 K, is explained as due to the thermal activation of an acceptor level with an ionization energy of 0.067 eV, whereas below 100 K, the conduction in the impurity band dominates the electrical transport process. From the analysis of the p vs T data, the density-of-states effective mass of the holes is estimated to be nearly of the same magnitude as the free electron mass. In the valence band, the temperature variation of the hole mobility is analyzed by taking into account the scattering of charge carriers by ionized and neutral impurities, and acoustic phonons. In the impurity band, the mobility is explained as due to the thermally activated hopping transport. From the analysis of the optical absorption spectra at room temperature, the fundamental energy gap was determined to be 0.843 eV. The photoconductivity spectra show the presence of a narrow band gap whose main peak is observed at 0.771 eV. This band is attributed to a free-to-bound transition from the defect acceptor level to the conduction band. The origin of this acceptor state, consistent with the chemical composition of the samples and screening effects, is tentatively attributed to selenium interstitials. copyright 2001 American Institute of Physics

  14. Impurity-related nonlinear optical properties in delta-doped quantum rings: Electric field effects

    Energy Technology Data Exchange (ETDEWEB)

    Restrepo, R.L., E-mail: rrestre@gmail.com [Escuela de Ingeniería de Antioquia-EIA, Medellín (Colombia); Grupo de Materia Condensada-UdeA, Instituto de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Antioquia UdeA, Calle 70 No. 52-21, Medellín (Colombia); Morales, A.L. [Grupo de Materia Condensada-UdeA, Instituto de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Antioquia UdeA, Calle 70 No. 52-21, Medellín (Colombia); Martínez-Orozco, J.C. [Unidad Académica de Física, Universidad Autónoma de Zacatecas, CP 98060, Zacatecas (Mexico); Baghramyan, H.M.; Barseghyan, M.G. [Department of Solid State Physics, Yerevan State University, Al. Manookian 1, 0025 Yerevan (Armenia); Mora-Ramos, M.E. [Grupo de Materia Condensada-UdeA, Instituto de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Antioquia UdeA, Calle 70 No. 52-21, Medellín (Colombia); Facultad de Ciencias, Universidad Autónoma del Estado de Morelos, Ave. Universidad 1001, CP 62209, Cuernavaca, Morelos (Mexico); Duque, C.A. [Grupo de Materia Condensada-UdeA, Instituto de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Antioquia UdeA, Calle 70 No. 52-21, Medellín (Colombia)

    2014-11-15

    Using a variational procedure within the effective mass approximation, we have calculated the donor impurity binding energy for the ground (1s-like) and the excited (2p{sub z}-like) states as well as the impurity-related nonlinear optical absorption and relative changes in the refraction index in a GaAs single quantum ring with axial n-type delta-doping. The delta-like potential along the z-direction is an approximate model analytically described using a Lorentzian function with two parameters. Additionally we consider the application of an electric field along the z-direction. It is found that the changes in the geometry of the quantum ring, the change in the 2D impurity density of the delta-like doping, and different values of the electric field lead to a shifting of the resonant peaks of the optical responses spectrum.

  15. Impurity-related nonlinear optical properties in delta-doped quantum rings: Electric field effects

    International Nuclear Information System (INIS)

    Restrepo, R.L.; Morales, A.L.; Martínez-Orozco, J.C.; Baghramyan, H.M.; Barseghyan, M.G.; Mora-Ramos, M.E.; Duque, C.A.

    2014-01-01

    Using a variational procedure within the effective mass approximation, we have calculated the donor impurity binding energy for the ground (1s-like) and the excited (2p z -like) states as well as the impurity-related nonlinear optical absorption and relative changes in the refraction index in a GaAs single quantum ring with axial n-type delta-doping. The delta-like potential along the z-direction is an approximate model analytically described using a Lorentzian function with two parameters. Additionally we consider the application of an electric field along the z-direction. It is found that the changes in the geometry of the quantum ring, the change in the 2D impurity density of the delta-like doping, and different values of the electric field lead to a shifting of the resonant peaks of the optical responses spectrum

  16. Thermal effects in high average power optical parametric amplifiers.

    Science.gov (United States)

    Rothhardt, Jan; Demmler, Stefan; Hädrich, Steffen; Peschel, Thomas; Limpert, Jens; Tünnermann, Andreas

    2013-03-01

    Optical parametric amplifiers (OPAs) have the reputation of being average power scalable due to the instantaneous nature of the parametric process (zero quantum defect). This Letter reveals serious challenges originating from thermal load in the nonlinear crystal caused by absorption. We investigate these thermal effects in high average power OPAs based on beta barium borate. Absorption of both pump and idler waves is identified to contribute significantly to heating of the nonlinear crystal. A temperature increase of up to 148 K with respect to the environment is observed and mechanical tensile stress up to 40 MPa is found, indicating a high risk of crystal fracture under such conditions. By restricting the idler to a wavelength range far from absorption bands and removing the crystal coating we reduce the peak temperature and the resulting temperature gradient significantly. Guidelines for further power scaling of OPAs and other nonlinear devices are given.

  17. Analysis of thermal characteristics of electrical wiring for load groups in cattle barns.

    Science.gov (United States)

    Kim, Doo Hyun; Yoo, Sang-Ok; Kim, Sung Chul; Hwang, Dong Kyu

    2015-01-01

    The purpose of the current study is to analyze the thermal characteristics of electrical wirings depending on the number of operating load by connecting four types of electrical wirings that are selected by surveying the conditions for the electric fans, automatic waterers and halogen warm lamps that were installed in cattle barns in different years. The conditions of 64 cattle barns were surveyed and an experimental test was conducted at a cattle barn. The condition-survey covered inappropriate design, construction and misuse of electrical facility, including electrical wiring mostly used, and the mode of load current was evaluated. The survey showed that the mode of load current increased as the installation year of the fans, waterers and halogen lamps became older. Accordingly, the cattle barn manager needed to increase the capacity of the circuit breaker, which promoted the degradation of insulation of the electrical wires' sheath and increased possibility for electrical fires in the long-run. The test showed that the saturation temperature of the wire insulated sheath increased depending on the installation year of the load groups, in case of VCTFK and VFF electric wires, therefore, requiring their careful usage in the cattle barns.

  18. Thermophysical Properties of Cold and Vacuum Plasma Sprayed Cu-Cr-X Alloys, NiAl and NiCrAlY Coatings. Part 1; Electrical and Thermal Conductivity, Thermal Diffusivity, and Total Hemispherical Emissivity

    Science.gov (United States)

    Raj, S. V.

    2017-01-01

    This two-part paper reports the thermophysical properties of several cold and vacuum plasma sprayed monolithic Cu and Ni-based alloy coatings. Part I presents the electrical and thermal conductivity, thermal diffusivity, and total hemispherical emissivity data while Part II reports the specific heat capacity data for these coatings. Metallic copper alloys, stoichiometric NiAl and NiCrAlY coatings were fabricated by either the cold sprayed or the vacuum plasma spray deposition processes for thermal property measurements between 77 and 1223 K. The temperature dependencies of the thermal conductivities, thermal diffusivities, electrical conductivities and total hemispherical emissivities of these cold and vacuum sprayed monolithic coatings are reported in this paper. The electrical and thermal conductivity data correlate reasonably well for Cu-8%Cr-1%Al, Cu-23%Cr-5%Al and NiAl in accordance with the Wiedemann-Franz (WF) law although a better fit is obtained using the Smith-Palmer relationship. The Lorentz numbers determined from the WF law are close to the theoretical value.

  19. Electrical equivalent thermal network for direct contact membrane distillation modeling and analysis

    KAUST Repository

    Karam, Ayman M.

    2016-09-19

    Membrane distillation (MD) is an emerging water desalination technology that offers several advantages compared to conventional desalination methods. Although progress has been made to model the physics of the process, there are two common limitations of existing models. Firstly, many of the models are based on the steady-state analysis of the process and secondly, some of the models are based on partial differential equations, which when discretized introduce many states which are not accessible in practice. This paper presents the derivation of a novel dynamic model, based on the analogy between electrical and thermal systems, for direct contact membrane distillation (DCMD). An analogous electrical thermal network is constructed and its elements are parameterized such that the response of the network models the DCMD process. The proposed model captures the spatial and temporal responses of the temperature distribution along the flow direction and is able to accurately predict the distilled water flux output. To demonstrate the adequacy of the proposed model, validation with time varying and steady-state experimental data is presented. (C) 2016 Elsevier Ltd. All righ