WorldWideScience

Sample records for short-circuit photocurrent density

  1. Enhancement of short-circuit current density in polymer bulk heterojunction solar cells comprising plasmonic silver nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Yuzhao; Lin, Xiaofeng; Ou, Jiemei; Chen, Xudong, E-mail: cescxd@mail.sysu.edu.cn, E-mail: stszx@mail.sysu.edu.cn, E-mail: chenyj69@mail.sysu.edu.cn [Key Laboratory for Polymeric Composite and Functional Materials of Ministry of Education of China, Sun Yat-sen University, Guangzhou 510275 (China); Qing, Jian; Zhong, Zhenfeng; Zhou, Xiang, E-mail: cescxd@mail.sysu.edu.cn, E-mail: stszx@mail.sysu.edu.cn, E-mail: chenyj69@mail.sysu.edu.cn; Chen, Yujie, E-mail: cescxd@mail.sysu.edu.cn, E-mail: stszx@mail.sysu.edu.cn, E-mail: chenyj69@mail.sysu.edu.cn [State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-sen University, Guangzhou 510275 (China); Hu, Chenglong [Key Laboratory of Optoelectronic Chemical Materials and Devices of Ministry of Education, Jianghan University, Wuhan 430056 (China)

    2014-03-24

    We demonstrate that the influence of plasmonic effects based on silver nanowires (Ag NWs) on the characteristics of polymer solar cells (PSCs). The solution-processed Ag NWs are situated at the interface of anode buffer layer and active layer, which could enhance the performance especially the photocurrent of PSCs by scattering, localized surface plasmon resonance, and surface plasmon polaritons. Plasmonic effects are confirmed by the enhancement of extinction spectra, external quantum efficiency, and steady state photoluminescence. Consequently, the short-circuit current density (J{sub sc}) and power conversion efficiency enhance about 24% and 18%, respectively, under AM1.5 illumination when Ag NWs plasmonic nanostructure incorporated into PSCs.

  2. Defects influence on short circuit current density in p-i-n silicon solar cell

    International Nuclear Information System (INIS)

    Wagah F Mohamad; Alhan M Mustafa

    2006-01-01

    The admittance analysis method has been used to calculate the collection efficiency and the short circuit current density in a-Si:H p-i-n solar cell, as a function of the thickness of i-layer. Its is evident that the results of the short circuit current can be used to determine the optimal thickness of the i-layer of a cell, and it will be more accurate in comparison with the previous studies using a constant generation rate or an empirical exponential function for the generation of charge carriers throughout the i-layer

  3. Spatially resolved determination of the short-circuit current density of silicon solar cells via lock-in thermography

    International Nuclear Information System (INIS)

    Fertig, Fabian; Greulich, Johannes; Rein, Stefan

    2014-01-01

    We present a spatially resolved method to determine the short-circuit current density of crystalline silicon solar cells by means of lock-in thermography. The method utilizes the property of crystalline silicon solar cells that the short-circuit current does not differ significantly from the illuminated current under moderate reverse bias. Since lock-in thermography images locally dissipated power density, this information is exploited to extract values of spatially resolved current density under short-circuit conditions. In order to obtain an accurate result, one or two illuminated lock-in thermography images and one dark lock-in thermography image need to be recorded. The method can be simplified in a way that only one image is required to generate a meaningful short-circuit current density map. The proposed method is theoretically motivated, and experimentally validated for monochromatic illumination in comparison to the reference method of light-beam induced current.

  4. Short-circuit current density imaging of crystalline silicon solar cells via lock-in thermography: Robustness and simplifications

    International Nuclear Information System (INIS)

    Fertig, Fabian; Greulich, Johannes; Rein, Stefan

    2014-01-01

    Spatially resolved determination of solar cell parameters is beneficial for loss analysis and optimization of conversion efficiency. One key parameter that has been challenging to access by an imaging technique on solar cell level is short-circuit current density. This work discusses the robustness of a recently suggested approach to determine short-circuit current density spatially resolved based on a series of lock-in thermography images and options for a simplified image acquisition procedure. For an accurate result, one or two emissivity-corrected illuminated lock-in thermography images and one dark lock-in thermography image have to be recorded. The dark lock-in thermography image can be omitted if local shunts are negligible. Furthermore, it is shown that omitting the correction of lock-in thermography images for local emissivity variations only leads to minor distortions for standard silicon solar cells. Hence, adequate acquisition of one image only is sufficient to generate a meaningful map of short-circuit current density. Beyond that, this work illustrates the underlying physics of the recently proposed method and demonstrates its robustness concerning varying excitation conditions and locally increased series resistance. Experimentally gained short-circuit current density images are validated for monochromatic illumination in comparison to the reference method of light-beam induced current

  5. High short-circuit current density CdTe solar cells using all-electrodeposited semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Echendu, O.K., E-mail: oechendu@yahoo.com; Fauzi, F.; Weerasinghe, A.R.; Dharmadasa, I.M.

    2014-04-01

    CdS/CdTe and ZnS/CdTe n–n heterojunction solar cells have been fabricated using all-electrodeposited semiconductors. The best devices show remarkable high short-circuit current densities of 38.5 mAcm{sup −2} and 47.8 mAcm{sup −2}, open-circuit voltages of 630 mV and 646 mV and conversion efficiencies of 8.0% and 12.0% respectively. The major strength of these device structures lies in the combination of n–n heterojunction with a large Schottky barrier at the n-CdTe/metal back contact which provides the required band bending for the separation of photo-generated charge carriers. This is in addition to the use of a high quality n-type CdTe absorber layer with high electron mobility. The potential barrier heights estimated for these devices from the current–voltage characteristics exceed 1.09 eV and 1.13 eV for CdS/CdTe and ZnS/CdTe cells respectively. The diode rectification factors of both devices are in excess of four orders of magnitude with reverse saturation current densities of 1.0 × 10{sup −7} Acm{sup −2} and 4.0 × 10{sup −7} Acm{sup −2} respectively. These all-electrodeposited solar cell device structures are currently being studied and developed as an alternative to the well-known p–n junction structures which utilise chemical bath-deposited CdS. The preliminary material growth, device fabrication and assessment results are presented in this paper. - Highlights: • Two-electrode deposition. • High J{sub sc} Schottky barrier solar cells. • CdCl{sub 2} + CdF{sub 2} treatment.

  6. Small-bandgap polymer solar cells with unprecedented short-circuit current density and high fill factor.

    Science.gov (United States)

    Choi, Hyosung; Ko, Seo-Jin; Kim, Taehyo; Morin, Pierre-Olivier; Walker, Bright; Lee, Byoung Hoon; Leclerc, Mario; Kim, Jin Young; Heeger, Alan J

    2015-06-03

    Small-bandgap polymer solar cells (PSCs) with a thick bulk heterojunction film of 340 nm exhibit high power conversion efficiencies of 9.40% resulting from high short-circuit current density (JSC ) of 20.07 mA cm(-2) and fill factor of 0.70. This remarkable efficiency is attributed to maximized light absorption by the thick active layer and minimized recombination by the optimized lateral and vertical morphology through the processing additive. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Short-circuit logic

    NARCIS (Netherlands)

    Bergstra, J.A.; Ponse, A.

    2010-01-01

    Short-circuit evaluation denotes the semantics of propositional connectives in which the second argument is only evaluated if the first argument does not suffice to determine the value of the expression. In programming, short-circuit evaluation is widely used. A short-circuit logic is a variant of

  8. [Shunt and short circuit].

    Science.gov (United States)

    Rangel-Abundis, Alberto

    2006-01-01

    Shunt and short circuit are antonyms. In French, the term shunt has been adopted to denote the alternative pathway of blood flow. However, in French, as well as in Spanish, the word short circuit (court-circuit and cortocircuito) is synonymous with shunt, giving rise to a linguistic and scientific inconsistency. Scientific because shunt and short circuit made reference to a phenomenon that occurs in the field of the physics. Because shunt and short circuit are antonyms, it is necessary to clarify that shunt is an alternative pathway of flow from a net of high resistance to a net of low resistance, maintaining the stream. Short circuit is the interruption of the flow, because a high resistance impeaches the flood. This concept is applied to electrical and cardiovascular physiology, as well as to the metabolic pathways.

  9. Improvement of Short-Circuit Current Density in Dye-Sensitized Solar Cells Using Sputtered Nanocolumnar TiO2 Compact Layer

    Directory of Open Access Journals (Sweden)

    Lung-Chien Chen

    2010-01-01

    Full Text Available The effect of a nanocolumnar TiO2 compact layer in dye-sensitized solar cells (DSSCs was examined. Such a compact layer was sputtered on a glass substrate with an indium tin oxide (ITO film using TiO2 powder as the raw material, with a thickness of ~100 nm. The compact layer improved the short-circuit current density and the efficiency of conversion of solar energy to electricity by the DSSC by 53.37% and 59.34%, yielding values of 27.33 mA/cm2 and 9.21%, respectively. The performance was attributed to the effective electron pathways in the TiO2 compact layer, which reduced the back reaction by preventing direct contact between the redox electrolyte and the conductive substrate.

  10. Short-circuit impedance measurement

    DEFF Research Database (Denmark)

    Pedersen, Knud Ole Helgesen; Nielsen, Arne Hejde; Poulsen, Niels Kjølstad

    2003-01-01

    Methods for estimating the short-circuit impedance in the power grid are investigated for various voltage levels and situations. The short-circuit impedance is measured, preferably from naturally occurring load changes in the grid, and it is shown that such a measurement system faces different...

  11. Cell short circuit, preshort signature

    Science.gov (United States)

    Lurie, C.

    1980-01-01

    Short-circuit events observed in ground test simulations of DSCS-3 battery in-orbit operations are analyzed. Voltage signatures appearing in the data preceding the short-circuit event are evaluated. The ground test simulation is briefly described along with performance during reconditioning discharges. Results suggest that a characteristic signature develops prior to a shorting event.

  12. Detecting short circuits during assembly

    Science.gov (United States)

    Deboo, G. J.

    1980-01-01

    Detector circuit identifies shorts between bus bars of electronic equipment being wired. Detector sounds alarm and indicates which planes are shorted. Power and ground bus bars are scanned continuously until short circuit occurs.

  13. Enhanced photocurrent density in graphene/Si based solar cell (GSSC) by optimizing active layer thickness

    Energy Technology Data Exchange (ETDEWEB)

    Rosikhin, Ahmad, E-mail: a.rosikhin86@yahoo.co.id; Hidayat, Aulia Fikri; Syuhada, Ibnu; Winata, Toto, E-mail: toto@fi.itb.ac.id [Department of physics, physics of electronic materials research division Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung Jl. Ganesha 10, Bandung 40132, Jawa Barat – Indonesia (Indonesia)

    2015-12-29

    Thickness dependent photocurrent density in active layer of graphene/Si based solar cell has been investigated via analytical – simulation study. This report is a preliminary comparison of experimental and analytical investigation of graphene/Si based solar cell. Graphene sheet was interfaced with Si thin film forming heterojunction solar cell that was treated as a device model for photocurrent generator. Such current can be enhanced by optimizing active layer thickness and involving metal oxide as supporting layer to shift photons absorption. In this case there are two type of devices model with and without TiO{sub 2} in which the silicon thickness varied at 20 – 100 nm. All of them have examined and also compared with each other to obtain an optimum value. From this calculation it found that generated currents almost linear with thickness but there are saturated conditions that no more enhancements will be achieved. Furthermore TiO{sub 2} layer is effectively increases photon absorption but reducing device stability, maximum current is fluctuates enough. This may caused by the disturbance of excitons diffusion and resistivity inside each layer. Finally by controlling active layer thickness, it is quite useful to estimate optimization in order to develop the next solar cell devices.

  14. Enhanced photocurrent density in graphene/Si based solar cell (GSSC) by optimizing active layer thickness

    International Nuclear Information System (INIS)

    Rosikhin, Ahmad; Hidayat, Aulia Fikri; Syuhada, Ibnu; Winata, Toto

    2015-01-01

    Thickness dependent photocurrent density in active layer of graphene/Si based solar cell has been investigated via analytical – simulation study. This report is a preliminary comparison of experimental and analytical investigation of graphene/Si based solar cell. Graphene sheet was interfaced with Si thin film forming heterojunction solar cell that was treated as a device model for photocurrent generator. Such current can be enhanced by optimizing active layer thickness and involving metal oxide as supporting layer to shift photons absorption. In this case there are two type of devices model with and without TiO 2 in which the silicon thickness varied at 20 – 100 nm. All of them have examined and also compared with each other to obtain an optimum value. From this calculation it found that generated currents almost linear with thickness but there are saturated conditions that no more enhancements will be achieved. Furthermore TiO 2 layer is effectively increases photon absorption but reducing device stability, maximum current is fluctuates enough. This may caused by the disturbance of excitons diffusion and resistivity inside each layer. Finally by controlling active layer thickness, it is quite useful to estimate optimization in order to develop the next solar cell devices

  15. Shapeable short circuit resistant capacitor

    Science.gov (United States)

    Taylor, Ralph S.; Myers, John D.; Baney, William J.

    2015-10-06

    A ceramic short circuit resistant capacitor that is bendable and/or shapeable to provide a multiple layer capacitor that is extremely compact and amenable to desirable geometries. The capacitor that exhibits a benign failure mode in which a multitude of discrete failure events result in a gradual loss of capacitance. Each event is a localized event in which localized heating causes an adjacent portion of one or both of the electrodes to vaporize, physically cleaning away electrode material from the failure site. A first metal electrode, a second metal electrode, and a ceramic dielectric layer between the electrodes are thin enough to be formed in a serpentine-arrangement with gaps between the first electrode and the second electrode that allow venting of vaporized electrode material in the event of a benign failure.

  16. Short- circuit tests of circuit breakers

    OpenAIRE

    Chorovský, P.

    2015-01-01

    This paper deals with short-circuit tests of low voltage electrical devices. In the first part of this paper, there are described basic types of short- circuit tests and their principles. Direct and indirect (synthetic) tests with more details are described in the second part. Each test and principles are explained separately. Oscilogram is obtained from short-circuit tests of circuit breakers at laboratory. The aim of this research work is to propose a test circuit for performing indirect test.

  17. The Short Circuit Model of Reading.

    Science.gov (United States)

    Lueers, Nancy M.

    The name "short circuit" has been given to this model because, in many ways, it adequately describes what happens bioelectrically in the brain. The "short-circuiting" factors include linguistic, sociocultural, attitudinal and motivational, neurological, perceptual, and cognitive factors. Research is reviewed on ways in which each one affects any…

  18. Worst Asymmetrical Short-Circuit Current

    DEFF Research Database (Denmark)

    Arana Aristi, Iván; Holmstrøm, O; Grastrup, L

    2010-01-01

    In a typical power plant, the production scenario and the short-circuit time were found for the worst asymmetrical short-circuit current. Then, a sensitivity analysis on the missing generator values was realized in order to minimize the uncertainty of the results. Afterward the worst asymmetrical...

  19. Short circuit in deep brain stimulation.

    Science.gov (United States)

    Samura, Kazuhiro; Miyagi, Yasushi; Okamoto, Tsuyoshi; Hayami, Takehito; Kishimoto, Junji; Katano, Mitsuo; Kamikaseda, Kazufumi

    2012-11-01

    The authors undertook this study to investigate the incidence, cause, and clinical influence of short circuits in patients treated with deep brain stimulation (DBS). After the incidental identification of a short circuit during routine follow-up, the authors initiated a policy at their institution of routinely evaluating both therapeutic impedance and system impendence at every outpatient DBS follow-up visit, irrespective of the presence of symptoms suggesting possible system malfunction. This study represents a report of their findings after 1 year of this policy. Implanted DBS leads exhibiting short circuits were identified in 7 patients (8.9% of the patients seen for outpatient follow-up examinations during the 12-month study period). The mean duration from DBS lead implantation to the discovery of the short circuit was 64.7 months. The symptoms revealing short circuits included the wearing off of therapeutic effect, apraxia of eyelid opening, or dysarthria in 6 patients with Parkinson disease (PD), and dystonia deterioration in 1 patient with generalized dystonia. All DBS leads with short circuits had been anchored to the cranium using titanium miniplates. Altering electrode settings resulted in clinical improvement in the 2 PD cases in which patients had specific symptoms of short circuits (2.5%) but not in the other 4 cases. The patient with dystonia underwent repositioning and replacement of a lead because the previous lead was located too anteriorly, but did not experience symptom improvement. In contrast to the sudden loss of clinical efficacy of DBS caused by an open circuit, short circuits may arise due to a gradual decrease in impedance, causing the insidious development of neurological symptoms via limited or extended potential fields as well as shortened battery longevity. The incidence of short circuits in DBS may be higher than previously thought, especially in cases in which DBS leads are anchored with miniplates. The circuit impedance of DBS

  20. Achieving 12.8% Efficiency by Simultaneously Improving Open-Circuit Voltage and Short-Circuit Current Density in Tandem Organic Solar Cells.

    Science.gov (United States)

    Qin, Yunpeng; Chen, Yu; Cui, Yong; Zhang, Shaoqing; Yao, Huifeng; Huang, Jiang; Li, Wanning; Zheng, Zhong; Hou, Jianhui

    2017-06-01

    Tandem organic solar cells (TOSCs), which integrate multiple organic photovoltaic layers with complementary absorption in series, have been proved to be a strong contender in organic photovoltaic depending on their advantages in harvesting a greater part of the solar spectrum and more efficient photon utilization than traditional single-junction organic solar cells. However, simultaneously improving open circuit voltage (V oc ) and short current density (J sc ) is a still particularly tricky issue for highly efficient TOSCs. In this work, by employing the low-bandgap nonfullerene acceptor, IEICO, into the rear cell to extend absorption, and meanwhile introducing PBDD4T-2F into the front cell for improving V oc , an impressive efficiency of 12.8% has been achieved in well-designed TOSC. This result is also one of the highest efficiencies reported in state-of-the-art organic solar cells. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. SITE WIDE SHORT CIRCUIT STUDY ASSESSMENT

    International Nuclear Information System (INIS)

    CARRATT, R.T.

    2004-01-01

    The Department of Energy requested that Fluor Hanford develop a plan to update the electrical distribution studies for FH managed facilities. Toward this end, an assessment of FH's nuclear facilities was performed to determine whether a current short circuit study of the facility electrical distribution system exists, and the status of such study. This report presents the methodology and results of that assessment. The assessment identified 29 relevant facilities. Of these, a short circuit study could not be identified for 15 facilities. A short circuit study was found to exist for fourteen facilities, however, of these 14, four were not released into a controlled document system, and two were not performed for the entire electrical distribution system. It is recommended that for four of the facilities no further action is required based upon the limited nature of the existing electrical system, or as in the case of PFP, the status of the existing short circuit study was determined adequate. For the majority of the facilities without a short circuit study, it is recommended that one is performed, and released into a controlled document system. Two facilities require further evaluation due to missing or conflicting documentation. For the remainder of the facilities, the recommendations are to review and revise as appropriate the existing study, and release into a controlled document system. A summation of the recommendations is presented

  2. Estimating the short-circuit impedance

    DEFF Research Database (Denmark)

    Nielsen, Arne Hejde; Pedersen, Knud Ole Helgesen; Poulsen, Niels Kjølstad

    1997-01-01

    A method for establishing a complex value of the short-circuit impedance from naturally occurring variations in voltage and current is discussed. It is the symmetrical three phase impedance at the fundamental grid frequency there is looked for. The positive sequence components in voltage...... and current are derived each period, and the short-circuit impedance is estimated from variations in these components created by load changes in the grid. Due to the noisy and dynamic grid with high harmonic distortion it is necessary to threat the calculated values statistical. This is done recursively...... through a RLS-algorithm. The algorithms have been tested and implemented on a PC at a 132 kV substation supplying a rolling mill. Knowing the short-circuit impedance gives the rolling mill an opportunity to adjust the arc furnace operation to keep flicker below a certain level. Therefore, the PC performs...

  3. Ag2S/CdS/TiO2 Nanotube Array Films with High Photocurrent Density by Spotting Sample Method.

    Science.gov (United States)

    Sun, Hong; Zhao, Peini; Zhang, Fanjun; Liu, Yuliang; Hao, Jingcheng

    2015-12-01

    Ag2S/CdS/TiO2 hybrid nanotube array films (Ag2S/CdS/TNTs) were prepared by selectively depositing a narrow-gap semiconductor-Ag2S (0.9 eV) quantum dots (QDs)-in the local domain of the CdS/TiO2 nanotube array films by spotting sample method (SSM). The improvement of sunlight absorption ability and photocurrent density of titanium dioxide (TiO2) nanotube array films (TNTs) which were obtained by anodic oxidation method was realized because of modifying semiconductor QDs. The CdS/TNTs, Ag2S/TNTs, and Ag2S/CdS/TNTs fabricated by uniformly depositing the QDs into the TNTs via the successive ionic layer adsorption and reaction (SILAR) method were synthesized, respectively. The X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectrum (XPS) results demonstrated that the Ag2S/CdS/TNTs prepared by SSM and other films were successfully prepared. In comparison with the four films of TNTs, CdS/TNTs, Ag2S/TNTs, and Ag2S/CdS/TNTs by SILAR, the Ag2S/CdS/TNTs prepared by SSM showed much better absorption capability and the highest photocurrent density in UV-vis range (320~800 nm). The cycles of local deposition have great influence on their photoelectric properties. The photocurrent density of Ag2S/CdS/TNTs by SSM with optimum deposition cycles of 6 was about 37 times that of TNTs without modification, demonstrating their great prospective applications in solar energy utilization fields.

  4. Ag2S/CdS/TiO2 Nanotube Array Films with High Photocurrent Density by Spotting Sample Method

    OpenAIRE

    Sun, Hong; Zhao, Peini; Zhang, Fanjun; Liu, Yuliang; Hao, Jingcheng

    2015-01-01

    Ag2S/CdS/TiO2 hybrid nanotube array films (Ag2S/CdS/TNTs) were prepared by selectively depositing a narrow-gap semiconductor—Ag2S (0.9 eV) quantum dots (QDs)—in the local domain of the CdS/TiO2 nanotube array films by spotting sample method (SSM). The improvement of sunlight absorption ability and photocurrent density of titanium dioxide (TiO2) nanotube array films (TNTs) which were obtained by anodic oxidation method was realized because of modifying semiconductor QDs. The CdS/TNTs, Ag2S/TNT...

  5. Textbook Error: Short Circuiting on Electrochemical Cell

    Science.gov (United States)

    Bonicamp, Judith M.; Clark, Roy W.

    2007-01-01

    Short circuiting an electrochemical cell is an unreported but persistent error in the electrochemistry textbooks. It is suggested that diagrams depicting a cell delivering usable current to a load be postponed, the theory of open-circuit galvanic cells is explained, the voltages from the tables of standard reduction potentials is calculated and…

  6. Automatic location of short circuit faults

    Energy Technology Data Exchange (ETDEWEB)

    Lehtonen, M. [VTT Energy, Espoo (Finland); Hakola, T.; Antila, E. [ABB Power Oy, Helsinki (Finland); Seppaenen, M. [North-Carelian Power Company (Finland)

    1996-12-31

    In this presentation, the automatic location of short circuit faults on medium voltage distribution lines, based on the integration of computer systems of medium voltage distribution network automation is discussed. First the distribution data management systems and their interface with the substation telecontrol, or SCADA systems, is studied. Then the integration of substation telecontrol system and computerised relay protection is discussed. Finally, the implementation of the fault location system is presented and the practical experience with the system is discussed

  7. Automatic location of short circuit faults

    Energy Technology Data Exchange (ETDEWEB)

    Lehtonen, M [VTT Energy, Espoo (Finland); Hakola, T; Antila, E [ABB Power Oy (Finland); Seppaenen, M [North-Carelian Power Company (Finland)

    1998-08-01

    In this chapter, the automatic location of short circuit faults on medium voltage distribution lines, based on the integration of computer systems of medium voltage distribution network automation is discussed. First the distribution data management systems and their interface with the substation telecontrol, or SCADA systems, is studied. Then the integration of substation telecontrol system and computerized relay protection is discussed. Finally, the implementation of the fault location system is presented and the practical experience with the system is discussed

  8. Automatic location of short circuit faults

    Energy Technology Data Exchange (ETDEWEB)

    Lehtonen, M [VTT Energy, Espoo (Finland); Hakola, T; Antila, E [ABB Power Oy, Helsinki (Finland); Seppaenen, M [North-Carelian Power Company (Finland)

    1997-12-31

    In this presentation, the automatic location of short circuit faults on medium voltage distribution lines, based on the integration of computer systems of medium voltage distribution network automation is discussed. First the distribution data management systems and their interface with the substation telecontrol, or SCADA systems, is studied. Then the integration of substation telecontrol system and computerised relay protection is discussed. Finally, the implementation of the fault location system is presented and the practical experience with the system is discussed

  9. Synchronous Condenser Allocation for Improving System Short Circuit Ratio

    DEFF Research Database (Denmark)

    Jia, Jundi; Yang, Guangya; Nielsen, Arne Hejde

    2018-01-01

    With converter-based renewable energy sources increasingly integrated into power systems and conventional power plants gradually phased out, future power systems will experience reduced short circuit strength. The deployment of synchronous condensers can serve as a potential solution. This paper...... presents an optimal synchronous condenser allocation method for improving system short circuit ratio at converter point of common coupling using a modified short circuit analysis approach. The total cost of installing new synchronous condensers is minimized while the system short circuit ratios...

  10. 30 CFR 56.12065 - Short circuit and lightning protection.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Short circuit and lightning protection. 56... Electricity § 56.12065 Short circuit and lightning protection. Powerlines, including trolley wires, and telephone circuits shall be protected against short circuits and lightning. ...

  11. 30 CFR 57.12065 - Short circuit and lightning protection.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Short circuit and lightning protection. 57... MINES Electricity Surface Only § 57.12065 Short circuit and lightning protection. Powerlines, including trolley wires, and telephone circuits shall be protected against short circuits and lightning. ...

  12. Modelling the short-circuit current of polymer bulk heterojunction solar cells

    International Nuclear Information System (INIS)

    Geens, Wim; Martens, Tom; Poortmans, Jef; Aernouts, Tom; Manca, Jean; Lutsen, Laurence; Heremans, Paul; Borghs, Staf; Mertens, Robert; Vanderzande, Dirk

    2004-01-01

    An analytical model has been developed to estimate the short-circuit current density of conjugated polymer/fullerene bulk heterojunction solar cells. The model takes into account the solvent-dependent molecular morphology of the donor/acceptor blend, which was revealed by transmission electron microscopy. Field-effect transistors based on single and composite organic layers were fabricated to determine values for the charge carrier mobilities of such films. These values served as input parameters of the model. It is shown that the difference in short-circuit current density that was measured between toluene-cast and chlorobenzene-cast conjugated polymer/fullerene photovoltaic cells (Appl. Phys. Lett. 78 (2001) 841) could be very well simulated with the model. Moreover, the calculations illustrate how increasing the hole and electron mobilities in the photoactive blend can improve the overall short-circuit current density of the solar cell

  13. Effect of the depth base along the vertical on the electrical parameters of a vertical parallel silicon solar cell in open and short circuit

    Directory of Open Access Journals (Sweden)

    Gokhan Sahin

    2018-03-01

    Full Text Available This article presented a modeling study of effect of the depth base initiating on vertical parallel silicon solar cell’s photovoltaic conversion efficiency. After the resolution of the continuity equation of excess minority carriers, we calculated the electrical parameters such as the photocurrent density, the photovoltage, series resistance and shunt resistances, diffusion capacitance, electric power, fill factor and the photovoltaic conversion efficiency. We determined the maximum electric power, the operating point of the solar cell and photovoltaic conversion efficiency according to the depth z in the base. We showed that the photocurrent density decreases with the depth z. The photovoltage decreased when the depth base increases. Series and shunt resistances were deduced from electrical model and were influenced and the applied the depth base. The capacity decreased with the depth z of the base. We had studied the influence of the variation of the depth z on the electrical parameters in the base. Keywords: Depth base, Conversion efficiency, Electrical parameters, Open circuit, Short circuit

  14. LS1 Report: short-circuit tests

    CERN Multimedia

    Katarina Anthony

    2014-01-01

    As the LS1 draws to an end, teams move from installation projects to a phase of intense testing. Among these are the so-called 'short-circuit tests'. Currently under way at Point 7, these tests verify the cables, the interlocks, the energy extraction systems, the power converters that provide current to the superconducting magnets and the cooling system.   Thermal camera images taken during tests at point 4 (IP4). Before putting beam into the LHC, all of the machine's hardware components need to be put to the test. Out of these, the most complicated are the superconducting circuits, which have a myriad of different failure modes with interlock and control systems. While these will be tested at cold - during powering tests to be done in August - work can still be done beforehand. "While the circuits in the magnets themselves cannot be tested at warm, what we can do is verify the power converter and the circuits right up to the place the cables go into the magn...

  15. Short-Circuit Modeling of a Wind Power Plant: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Muljadi, E.; Gevorgian, V.

    2011-03-01

    This paper investigates the short-circuit behavior of a WPP for different types of wind turbines. The short-circuit behavior will be presented. Both the simplified models and detailed models are used in the simulations and both symmetrical faults and unsymmetrical faults are discussed.

  16. Thyristor based short circuit current injection in isolated grids

    OpenAIRE

    Hoff, Bjarte; Sharma, Pawan; Østrem, Trond

    2017-01-01

    This paper proposes a thyristor based short circuit current injector for providing short circuit current in isolated and weak grids, where sufficient fault current to trigger circuit breakers may not be available. This will allow the use of conventional miniature circuit breakers, which requires high fault current for instantaneous tripping. The method has been validated through experiments.

  17. TCAD analysis of short-circuit oscillations in IGBTs

    DEFF Research Database (Denmark)

    Reigosa, Paula Diaz; Iannuzzo, Francesco; Rahimo, Munaf

    2017-01-01

    Insulated-Gate Bipolar Transistors (IGBTs) exhibit a gate-voltage oscillation phenomenon during short-circuit, which can result in a gate-oxide breakdown. The oscillations have been investigated through device simulations and experimental investigations of a 3.3-kV IGBT. It has been found...... during short circuit....

  18. Short circuit protection for a power distribution system

    Science.gov (United States)

    Owen, J. R., III

    1969-01-01

    Sensing circuit detects when the output from a matrix is present and when it should be present. The circuit provides short circuit protection for a power distribution system where the selection of the driven load is accomplished by digital logic.

  19. Capacitive short circuit detection in transformer core laminations

    International Nuclear Information System (INIS)

    Schulz, Carl A.; Duchesne, Stephane; Roger, Daniel; Vincent, Jean-Noel

    2008-01-01

    A capacitive measurement procedure is proposed that serves to detect burr-induced short circuits in transformer core laminations. The tests are conducted on stacks of transformer steel sheets as used for transformer core production and yield a short-circuit probability indicative of the additional eddy current losses to be expected. Applied during the assembly of transformer cores, the measurements can help to decide whether the burr treatment process is working efficiently or has to be readjusted

  20. Improved Short-Circuit Protection for Power Cells in Series

    Science.gov (United States)

    Davies, Francis

    2008-01-01

    A scheme for protection against short circuits has been devised for series strings of lithium electrochemical cells that contain built-in short-circuit protection devices, which go into a high-resistance, current-limiting state when heated by excessive current. If cells are simply connected in a long series string to obtain a high voltage and a short circuit occurs, whichever short-circuit protection device trips first is exposed to nearly the full string voltage, which, typically, is large enough to damage the device. Depending on the specific cell design, the damage can defeat the protective function, cause a dangerous internal short circuit in the affected cell, and/or cascade to other cells. In the present scheme, reverse diodes rated at a suitably high current are connected across short series sub-strings, the lengths of which are chosen so that when a short-circuit protection device is tripped, the voltage across it does not exceed its rated voltage. This scheme preserves the resetting properties of the protective devices. It provides for bypassing of cells that fail open and limits cell reversal, though not as well as does the more-expensive scheme of connecting a diode across every cell.

  1. Simulation and experimental study on lithium ion battery short circuit

    International Nuclear Information System (INIS)

    Zhao, Rui; Liu, Jie; Gu, Junjie

    2016-01-01

    Highlights: • Both external and internal short circuit tests were performed on Li-ion batteries. • An electrochemical–thermal model with an additional nail site heat source is presented. • The model can accurately simulate the temperature variations of non-venting batteries. • The model is reliable in predicting the occurrence and start time of thermal runaway. • A hydrogel cooling system proves its strength in preventing battery thermal runaway. - Abstract: Safety is the first priority in lithium ion (Li-ion) battery applications. A large portion of electrical and thermal hazards caused by Li-ion battery is associated with short circuit. In this paper, both external and internal short circuit tests are conducted. Li-ion batteries and battery packs of different capacities are used. The results indicate that external short circuit is worse for smaller size batteries due to their higher internal resistances, and this type of short can be well managed by assembling fuses. In internal short circuit tests, higher chance of failure is found on larger capacity batteries. A modified electrochemical–thermal model is proposed, which incorporates an additional heat source from nail site and proves to be successful in depicting temperature changes in batteries. Specifically, the model is able to estimate the occurrence and approximate start time of thermal runaway. Furthermore, the effectiveness of a hydrogel based thermal management system in suppressing thermal abuse and preventing thermal runaway propagation is verified through the external and internal short tests on batteries and battery packs.

  2. Fabrication and characterization of ZnO nanowires array electrodes with high photocurrent densities: Effects of the seed layer calcination time

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Yi-Jing; Liu, Ching-Fang; Hu, Chi-Chang, E-mail: cchu@che.nthu.edu.tw; Kuo, Jen-Hou; Boddula, Rajender

    2017-03-01

    In this work, we demonstrate that vertically grown ZnO nanowire (NW) arrays of the wurzite phase were successfully fabricated on fluorine doped tin oxide (FTO) substrates via a hydrothermal method. The coating of a seed layer onto the FTO substrates was found to favor the growth of a uniform ZnO NWs array which shows saturation in the photocurrent density with a relatively low potential bias. Furthermore, prolonging the calcination time of the seed layer makes the ZnO NWs behave the better charge separation and improve the photo-electrochemical performance. Under the irradiation at a 75 mW cm{sup −2} from a simulated sunlight source, the ZnO NWs array electrode prepared from the seed layer with calcination at 350 °C for 5 h shows a saturated photocurrent density of 514 μA cm{sup −2} and a maximum half-cell solar-to-hydrogen (HC-STH) efficiency of 0.26% was obtained at 0.6 V versus reversible hydrogen electrode (RHE) in neutral electrolyte. - Highlights: • The seed layer annealing time strongly influences the textural and photo-activity of ZnO NWs. • The average diameter and density of ZnO NWs were controlled to 47–70 nm and 46–70 NWs μm{sup −2}, respectively. • ZnO NWs show promising application potential in solar-electrocatalytic water splitting under potential bias. • The ZnO NWs with SL annealing time = 5 h achieve the highest HC-STH efficiency of 0.26% at 0.6 V.

  3. NREL/NASA Internal Short-Circuit Instigator in Lithium Ion Cells

    Energy Technology Data Exchange (ETDEWEB)

    Keyser, Matthew; Long, Dirk; Pesaran, Ahmad; Darcy, Eric; Shoesmith, Mark; McCarthy, Ben

    2015-10-11

    Lithium-ion cells provide the highest specific energy (>280 Wh/kg) and energy density (>600 Wh/L) rechargeable battery building block to date with the longest life. Electrode/electrolyte thermal instability and flammability of the electrolyte of Li-ion cells make them prone to catastrophic thermal runaway under some rare internal short circuit conditions. Despite extensive QC/QA, standardized industry safety testing, and over 18 years of manufacturing experience, major recalls have taken place and incidents still occur. Many safety incidents that take place in the field originate due to an internal short that was not detectable or predictable at the point of manufacture. The Internal Short-Circuit Instigator can be used to study types of separators, non-flammable electrolytes, electrolyte additives, fusible tabs, propagation studies, and gas generation within a cell.

  4. Prevention of short circuits in solution-processed OLED devices

    NARCIS (Netherlands)

    Jolt Oostra, A.; Blom, P.W.M.; Michels, J.J.

    2014-01-01

    Pinholes in the emitting layer of an organic light emitting diode (OLED), e.g. induced by particle contamination or processing flaws, lead to direct contact between the hole-injection layer (HIL) and the cathode. The resulting short circuits give rise to catastrophic device failure. We demonstrate

  5. Packaging Solutions for Mitigating IGBT Short-Circuit Instabilities

    DEFF Research Database (Denmark)

    Reigosa, Paula Diaz; Iannuzzo, Francesco; Blaabjerg, Frede

    2017-01-01

    In this paper, the gate voltage oscillations occurring under short-circuit conditions in Insulated-Gate Bipolar Transistors are investigated, together with their dependency with respect to stray inductance variations. By using AnSYS Q3D Extractor, electromagnetic simulations are conducted to extr...

  6. Full Digital Short Circuit Protection for Advanced IGBTs

    OpenAIRE

    谷村, 拓哉; 湯浅, 一史; 大村, 一郎

    2011-01-01

    A full digital short circuit protection method for advanced IGBTs has been proposed and experimentally demonstrated for the first time. The method employs combination of digital circuit, the gate charge sense instead of the conventional sense IGBT and analog circuit configuration. Digital protection scheme has significant advantages in thevprotection speed and flexibility.

  7. A Computer Program for Short Circuit Analysis of Electric Power ...

    African Journals Online (AJOL)

    The Short Circuit Analysis Program (SCAP) is to be used to assess the composite effects of unbalanced and balanced faults on the overall reliability of electric power system. The program uses the symmetrical components method to compute all phase and sequence quantities for any bus or branch of a given power network ...

  8. Electrical short circuit and current overload tests on aircraft wiring

    Science.gov (United States)

    Cahill, Patricia

    1995-01-01

    The findings of electrical short circuit and current overload tests performed on commercial aircraft wiring are presented. A series of bench-scale tests were conducted to evaluate circuit breaker response to overcurrent and to determine if the wire showed any visible signs of thermal degradation due to overcurrent. Three types of wire used in commercial aircraft were evaluated: MIL-W-22759/34 (150 C rated), MIL-W-81381/12 (200 C rated), and BMS 1360 (260 C rated). A second series of tests evaluated circuit breaker response to short circuits and ticking faults. These tests were also meant to determine if the three test wires behaved differently under these conditions and if a short circuit or ticking fault could start a fire. It is concluded that circuit breakers provided reliable overcurrent protection. Circuit breakers may not protect wire from ticking faults but can protect wire from direct shorts. These tests indicated that the appearance of a wire subjected to a current that totally degrades the insulation looks identical to a wire subjected to a fire; however the 'fire exposed' conductor was more brittle than the conductor degraded by overcurrent. Preliminary testing indicates that direct short circuits are not likely to start a fire. Preliminary testing indicated that direct short circuits do not erode insulation and conductor to the extent that ticking faults did. Circuit breakers may not safeguard against the ignition of flammable materials by ticking faults. The flammability of materials near ticking faults is far more important than the rating of the wire insulation material.

  9. The short-circuit concept used in field equivalence principles

    DEFF Research Database (Denmark)

    Appel-Hansen, Jørgen

    1990-01-01

    In field equivalence principles, electric and magnetic surface currents are specified and considered as impressed currents. Often the currents are placed on perfect conductors. It is shown that these currents can be treated through two approaches. The first approach is decomposition of the total...... field into partial fields caused by the individual impressed currents. When this approach is used, it is shown that, on a perfect electric (magnetic) conductor, impressed electric (magnetic) surface currents are short-circuited. The second approach is to note that, since Maxwell's equations...... and the boundary conditions are satisfied, none of the impressed currents is short-circuited and no currents are induced on the perfect conductors. Since all currents and field quantities are considered at the same time, this approach is referred to as the total-field approach. The partial-field approach leads...

  10. [Electric short-circuit incident observed with "Upsher" laryngoscopes].

    Science.gov (United States)

    Tritsch, L; Vailly, B

    2006-01-01

    We observed an electrical short-circuit between a fasten screw of the printed circuit and the handle of an Upsher universal laryngoscope (serial number UQ1). The isolating Silicone layer was broken above the screw. This isolation defect was found all over our Upsher laryngoscopes of the UQ1 series. No doubt that if accumulators were used instead of batteries, emitted heat would be in largest amount and perhaps dangerous.

  11. Short-circuit experiments on a high Tc-superconducting cable conductor

    DEFF Research Database (Denmark)

    Tønnesen, Ole; Jensen, E.H.; Traholt, C.

    2002-01-01

    A high temperature superconductor (HTS) cable conductor (CC) with a critical current of 2.1 kA was tested over a range of short-circuit currents up to 20 kA. The duration of the short-circuit currents is 1 s. Between each short-circuit test the critical current of the HTS CC was measured in order...

  12. 30 CFR 77.600 - Trailing cables; short-circuit protection; disconnecting devices.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Trailing cables; short-circuit protection... AREAS OF UNDERGROUND COAL MINES Trailing Cables § 77.600 Trailing cables; short-circuit protection; disconnecting devices. Short-circuit protection for trailing cables shall be provided by an automatic circuit...

  13. 30 CFR 75.601 - Short circuit protection of trailing cables.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Short circuit protection of trailing cables. 75... MINE SAFETY AND HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Trailing Cables § 75.601 Short circuit protection of trailing cables. [Statutory Provisions] Short circuit protection for trailing cables...

  14. 30 CFR 75.601-1 - Short circuit protection; ratings and settings of circuit breakers.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Short circuit protection; ratings and settings... Trailing Cables § 75.601-1 Short circuit protection; ratings and settings of circuit breakers. Circuit breakers providing short circuit protection for trailing cables shall be set so as not to exceed the...

  15. 30 CFR 75.601-2 - Short circuit protection; use of fuses; approval by the Secretary.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Short circuit protection; use of fuses... Trailing Cables § 75.601-2 Short circuit protection; use of fuses; approval by the Secretary. Fuses shall not be employed to provide short circuit protection for trailing cables unless specifically approved...

  16. 30 CFR 75.518 - Electric equipment and circuits; overload and short circuit protection.

    Science.gov (United States)

    2010-07-01

    ... short circuit protection. 75.518 Section 75.518 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION... Equipment-General § 75.518 Electric equipment and circuits; overload and short circuit protection... installed so as to protect all electric equipment and circuits against short circuit and overloads. Three...

  17. 30 CFR 75.518-2 - Incandescent lamps, overload and short circuit protection.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Incandescent lamps, overload and short circuit...-General § 75.518-2 Incandescent lamps, overload and short circuit protection. Incandescent lamps installed... or direct current feeder circuits, need not be provided with separate short circuit or overload...

  18. Closed Form Solution of Synchronous Machine Short Circuit Transients

    Directory of Open Access Journals (Sweden)

    Gibson H.M. Sianipar

    2010-05-01

    Full Text Available This paper presents the closed form solution of the synchronous machine transients undergoing short circuit. That analytic formulation has been derived based on linearity and balanced conditions of the fault. Even though restrictive, the proposed method will serve somehow or other as a new resource for EMTP productivity. Indisputably superior, the closed-form formulation has some features inimitable by discretization such as continuity, accuracy and absolute numerical stability. Moreover, it enables us to calculate states at one specific instant independent of previous states or a snapshot, which any discretization methods cannot do.

  19. A Simple Short Circuit Analysis for Power Networks

    Directory of Open Access Journals (Sweden)

    Koşalay İlhan

    2016-01-01

    Full Text Available This study investigates the transient behavior of short circuits in power circuits. The circuit consists of two part; input part and load part. These two parts are connected with a circuit breaker switch. The circuit works in two modes; first mode is when the switch is open and second mode is when the switch is closed. This study analyses the circuit when the switch is closed. The analysis is done with different types of closing angle. The analysis is done by forming state equations and those equations are solved numerically by using Matlab. The analysis and conclusion is performed by observing the behaviors of the graphs.

  20. Improving the Short-Circuit Reliability in IGBTs

    DEFF Research Database (Denmark)

    Reigosa, Paula Diaz; Iannuzzo, Francesco; Rahimo, Munaf

    2018-01-01

    takes place during the IGBT short-circuit, whose time-varying element is the Miller capacitance, which is involved in the amplification mechanism. This hypothesis has been validated through simulations and its mitigation is possible by increasing the electric field at the emitter of the IGBT......In this paper, the oscillation mechanism limiting the ruggedness of IGBTs is investigated through both circuit and device analysis. The work presented here is based on a time-domain approach for two different IGBT cell structures (i.e., trench-gate and planar), illustrating the 2-D effects during...

  1. Capacitive effects in IGBTs limiting their reliability under short circuit

    DEFF Research Database (Denmark)

    Reigosa, Paula Diaz; Iannuzzo, Francesco; Rahimo, Munaf

    2017-01-01

    The short-circuit oscillation mechanism in IGBTs is investigated in this paper by the aid of semiconductor device simulation tools. A 3.3-kV IGBT cell has been used for the simulations demonstrating that a single IGBT cell is able to oscillate together with the external circuit parasitic elements....... The work presented here through both circuit and device analysis, confirms that the oscillations can be understood with focus on the device capacitive effects coming from the interaction between carrier concentration and the electric field. The paper also shows the 2-D effects during one oscillation cycle...

  2. Short-Circuit Degradation of 10-kV 10-A SiC MOSFET

    DEFF Research Database (Denmark)

    Eni, Emanuel-Petre; Beczkowski, Szymon; Munk-Nielsen, Stig

    2017-01-01

    The short-circuit behavior of power devices is highly relevant for converter design and fault protection. In this work, the degradation during short-circuit of a 10 kV 10 A 4H-SiC MOSFET is investigated at 6 kV DC-link voltage. The study aims to present the behavior of the device during short-circuit...... transients as it sustains increasing short-circuit pulses during its life-time. As the short-circuit pulse length increases, degradation of the device can be observed in periodically performed characterizations. The initial degradation seems to be associated with the channel region, and continuous stressing...

  3. Investigation on the Short Circuit Safe Operation Area of SiC MOSFET Power Modules

    DEFF Research Database (Denmark)

    Reigosa, Paula Diaz; Luo, Haoze; Iannuzzo, Francesco

    2016-01-01

    This paper gives a better insight of the short circuit capability of state-of-the-art SiC MOSFET power modules rated at 1.2 kV by highlighting the physical limits under different operating conditions. Two different failure mechanisms have been identified, both reducing the short-circuit capability...... of SiC power modules in respect to discrete SiC devices. Based on such failure mechanisms, two short circuit criteria (i.e., short circuit current-based criterion and gate voltage-based criterion) are proposed in order to ensure their robustness under short-circuit conditions. A Safe Operation Area (SOA...

  4. A Short-Circuit Safe Operation Area Identification Criterion for SiC MOSFET Power Modules

    DEFF Research Database (Denmark)

    Reigosa, Paula Diaz; Iannuzzo, Francesco; Luo, Haoze

    2017-01-01

    This paper proposes a new method for the investigation of the short-circuit safe operation area (SCSOA) of state-of-the-art SiC MOSFET power modules rated at 1.2 kV based on the variations in SiC MOSFET electrical parameters (e.g., short-circuit current and gate–source voltage). According...... to the experimental results, two different failure mechanisms have been identified, both reducing the short-circuit capability of SiC power modules with respect to discrete SiC devices. Based on such failure mechanisms, two short-circuit safety criteria have been formulated: 1) the short-circuit...

  5. Analysis of High Power IGBT Short Circuit Failures

    Energy Technology Data Exchange (ETDEWEB)

    Pappas, G.

    2005-02-11

    The Next Linear Collider (NLC) accelerator proposal at SLAC requires a highly efficient and reliable, low cost, pulsed-power modulator to drive the klystrons. A solid-state induction modulator has been developed at SLAC to power the klystrons; this modulator uses commercial high voltage and high current Insulated Gate Bipolar Transistor (IGBT) modules. Testing of these IGBT modules under pulsed conditions was very successful; however, the IGBTs failed when tests were performed into a low inductance short circuit. The internal electrical connections of a commercial IGBT module have been analyzed to extract self and mutual partial inductances for the main current paths as well as for the gate structure. The IGBT module, together with the partial inductances, has been modeled using PSpice. Predictions for electrical paths that carry the highest current correlate with the sites of failed die under short circuit tests. A similar analysis has been carried out for a SLAC proposal for an IGBT module layout. This paper discusses the mathematical model of the IGBT module geometry and presents simulation results.

  6. Tin Whisker Electrical Short Circuit Characteristics. Part 2

    Science.gov (United States)

    Courey, Karim J.; Asfour, Shihab S.; Onar, Arzu; Bayliss, Jon A.; Ludwig, Lawrence L.; Wright, Maria C.

    2009-01-01

    Existing risk simulations make the assumption that when a free tin whisker has bridged two adjacent exposed electrical conductors, the result is an electrical short circuit. This conservative assumption is made because shorting is a random event that has an unknown probability associated with it. Note however that due to contact resistance electrical shorts may not occur at lower voltage levels. In our first article we developed an empirical probability model for tin whisker shorting. In this paper, we develop a more comprehensive empirical model using a refined experiment with a larger sample size, in which we studied the effect of varying voltage on the breakdown of the contact resistance which leads to a short circuit. From the resulting data we estimated the probability distribution of an electrical short, as a function of voltage. In addition, the unexpected polycrystalline structure seen in the focused ion beam (FIB) cross section in the first experiment was confirmed in this experiment using transmission electron microscopy (TEM). The FIB was also used to cross section two card guides to facilitate the measurement of the grain size of each card guide's tin plating to determine its finish.

  7. Consequences and mitigation of saltwater intrusion induced by short-circuiting during aquifer storage and recovery in a coastal subsurface

    Science.gov (United States)

    Gerardus Zuurbier, Koen; Stuyfzand, Pieter Jan

    2017-02-01

    Coastal aquifers and the deeper subsurface are increasingly exploited. The accompanying perforation of the subsurface for those purposes has increased the risk of short-circuiting of originally separated aquifers. This study shows how this short-circuiting negatively impacts the freshwater recovery efficiency (RE) during aquifer storage and recovery (ASR) in coastal aquifers. ASR was applied in a shallow saltwater aquifer overlying a deeper, confined saltwater aquifer, which was targeted for seasonal aquifer thermal energy storage (ATES). Although both aquifers were considered properly separated (i.e., a continuous clay layer prevented rapid groundwater flow between both aquifers), intrusion of deeper saltwater into the shallower aquifer quickly terminated the freshwater recovery. The presumable pathway was a nearby ATES borehole. This finding was supported by field measurements, hydrochemical analyses, and variable-density solute transport modeling (SEAWAT version 4; Langevin et al., 2007). The potentially rapid short-circuiting during storage and recovery can reduce the RE of ASR to null. When limited mixing with ambient groundwater is allowed, a linear RE decrease by short-circuiting with increasing distance from the ASR well within the radius of the injected ASR bubble was observed. Interception of deep short-circuiting water can mitigate the observed RE decrease, although complete compensation of the RE decrease will generally be unattainable. Brackish water upconing from the underlying aquitard towards the shallow recovery wells of the ASR system with multiple partially penetrating wells (MPPW-ASR) was observed. This leakage may lead to a lower recovery efficiency than based on current ASR performance estimations.

  8. Extra-high short-circuit current for bifacial solar cells in sunny and dark-light conditions.

    Science.gov (United States)

    Duan, Jialong; Duan, Yanyan; Zhao, Yuanyuan; He, Benlin; Tang, Qunwei

    2017-09-05

    We present here a symmetrically structured bifacial solar cell tailored by two fluorescent photoanodes and a platinum/titanium/platinum counter electrode, yielding extra-high short-circuit current densities as high as 28.59 mA cm -2 and 119.9 μA cm -2 in simulated sunlight irradiation (100 mW cm -2 , AM1.5) and dark-light conditions, respectively.

  9. Mineral processing by short circuits in protoplanetary disks

    DEFF Research Database (Denmark)

    Mcnally, C.P.; Hubbard, A.; Mac Low, M.-M.

    2013-01-01

    Meteoritic chondrules were formed in the early solar system by brief heating of silicate dust to melting temperatures. Some highly refractory grains (Type B calcium-aluminum-rich inclusions, CAIs) also show signs of transient heating. A similar process may occur in other protoplanetary disks......, as evidenced by observations of spectra characteristic of crystalline silicates. One possible environment for this process is the turbulent magnetohydrodynamic flow thought to drive accretion in these disks. Such flows generally form thin current sheets, which are sites of magnetic reconnection, and dissipate...... the magnetic fields amplified by a disk dynamo. We suggest that it is possible to heat precursor grains for chondrules and other high-temperature minerals in current sheets that have been concentrated by our recently described short-circuit instability. We extend our work on this process by including...

  10. On-Demand Cell Internal Short Circuit Device

    Science.gov (United States)

    Darcy, Eric; Keyser, Matthew

    2014-01-01

    A device implantable in Li-ion cells that can generate a hard internal short circuit on-demand by exposing the cell to 60?C has been demonstrated to be valuable for expanding our understanding of cell responses. The device provides a negligible impact to cell performance and enables the instigation of the 4 general categories of cell internal shorts to determine relative severity and cell design susceptibility. Tests with a 18650 cell design indicates that the anode active material short to the aluminum cathode current collector tends to be more catastrophic than the 3 other types of internal shorts. Advanced safety features (such as shutdown separators) to prevent or mitigate the severity of cell internal shorts can be verified with this device. The hard short success rate achieved to date in 18650 cells is about 80%, which is sufficient for using these cells in battery assemblies for field-failure-relevant, cell-cell thermal runaway propagation verification tests

  11. Performance of Llampuedken with short circuit and plasma loads

    International Nuclear Information System (INIS)

    Chuaqui, Hernan; Mitchell, Ian H.; Aliaga-Rossel, Raul; Favre, Mario; Wyndham, Edmund S.

    2002-01-01

    Llampuedken is a pulsed power generator designed to deliver a 1 MA, 250 ns risetime current pulse into a dense plasma load. The main novel feature of this generator is the two auxiliary transmission lines which transmit the energy not absorbed by the load, reflect it at the open end of the line and deliver it to the load when the energy from the main lines is decreasing. With the auxiliary lines an increase of 30% on the current as well as a decrease of the voltage at the load is obtained. To date Llampuedken has been operated up to the 400 kA level, into both short circuit and plasma loads. Details of actual performance of the pulse power generator are presented and compared with simulations

  12. Short circuit analysis of distribution system with integration of DG

    DEFF Research Database (Denmark)

    Su, Chi; Liu, Zhou; Chen, Zhe

    2014-01-01

    and as a result bring challenges to the network protection system. This problem has been frequently discussed in the literature, but mostly considering only the balanced fault situation. This paper presents an investigation on the influence of full converter based wind turbine (WT) integration on fault currents......Integration of distributed generation (DG) such as wind turbines into distribution system is increasing all around the world, because of the flexible and environmentally friendly characteristics. However, DG integration may change the pattern of the fault currents in the distribution system...... during both balanced and unbalanced faults. Major factors such as external grid short circuit power capacity, WT integration location, connection type of WT integration transformer are taken into account. In turn, the challenges brought to the protection system in the distribution network are presented...

  13. Short Circuit Tests First Step of LHC Hardware Commissioning Completion

    CERN Document Server

    Barbero-Soto, E; Bordry, Frederick; Casas Lino, M P; Coelingh, G J; Cumer, G; Dahlerup-Petersen, K; Guillaume, J C; Inigo-Golfin, J; Montabonnet, V; Nisbet, D; Pojer, M; Principe, R; Rodríguez-Mateos, F; Saban, R; Schmidt, R; Thiesen, H; Vergara-Fernández, A; Zerlauth, M; Castaneda Serra, A; Romera Ramirez, I

    2008-01-01

    For the two counter rotating beams in the Large Hadron Collider (LHC) about 8000 magnets (main dipole and quadrupole magnets, corrector magnets, separation dipoles, matching section quadrupoles etc.) are powered in about 1500 superconducting electrical circuits. The magnets are powered by power converters that have been designed for the LHC with a current between 60 and 13000A. Between October 2005 and September 2007 the so-called Short Circuit Tests were carried-out in 15 underground zones where the power converters of the superconducting circuits are placed. The tests aimed to qualify the normal conducting equipments of the circuits such as power converters and normal conducting high current cables. The correct operation of interlock and energy extraction systems was validated. The infrastructure systems including AC distribution, water and air cooling and the control systems was also commissioned. In this paper the results of the two year test campaign are summarized with particular attention to problems e...

  14. MINERAL PROCESSING BY SHORT CIRCUITS IN PROTOPLANETARY DISKS

    Energy Technology Data Exchange (ETDEWEB)

    McNally, Colin P. [Niels Bohr International Academy, Niels Bohr Institute, DK-2100 Copenhagen (Denmark); Hubbard, Alexander; Mac Low, Mordecai-Mark [Department of Astrophysics, American Museum of Natural History, New York, NY 10024-5192 (United States); Ebel, Denton S. [Department of Earth and Planetary Sciences, American Museum of Natural History, New York, NY 10024-5192 (United States); D' Alessio, Paola, E-mail: cmcnally@nbi.dk, E-mail: ahubbard@amnh.org, E-mail: mordecai@amnh.org, E-mail: debel@amnh.org, E-mail: p.dalessio@crya.unam.mx [Centro de Radioastronomia y Astrofisica, Universidad Nacional Autonoma de Mexico, 58089 Morelia, MICH (Mexico)

    2013-04-10

    Meteoritic chondrules were formed in the early solar system by brief heating of silicate dust to melting temperatures. Some highly refractory grains (Type B calcium-aluminum-rich inclusions, CAIs) also show signs of transient heating. A similar process may occur in other protoplanetary disks, as evidenced by observations of spectra characteristic of crystalline silicates. One possible environment for this process is the turbulent magnetohydrodynamic flow thought to drive accretion in these disks. Such flows generally form thin current sheets, which are sites of magnetic reconnection, and dissipate the magnetic fields amplified by a disk dynamo. We suggest that it is possible to heat precursor grains for chondrules and other high-temperature minerals in current sheets that have been concentrated by our recently described short-circuit instability. We extend our work on this process by including the effects of radiative cooling, taking into account the temperature dependence of the opacity; and by examining current sheet geometry in three-dimensional, global models of magnetorotational instability. We find that temperatures above 1600 K can be reached for favorable parameters that match the ideal global models. This mechanism could provide an efficient means of tapping the gravitational potential energy of the protoplanetary disk to heat grains strongly enough to form high-temperature minerals. The volume-filling nature of turbulent magnetic reconnection is compatible with constraints from chondrule-matrix complementarity, chondrule-chondrule complementarity, the occurrence of igneous rims, and compound chondrules. The same short-circuit mechanism may perform other high-temperature mineral processing in protoplanetary disks such as the production of crystalline silicates and CAIs.

  15. Enhanced charging kinetics of porous electrodes: surface conduction as a short-circuit mechanism.

    Science.gov (United States)

    Mirzadeh, Mohammad; Gibou, Frederic; Squires, Todd M

    2014-08-29

    We use direct numerical simulations of the Poisson-Nernst-Planck equations to study the charging kinetics of porous electrodes and to evaluate the predictive capabilities of effective circuit models, both linear and nonlinear. The classic transmission line theory of de Levie holds for general electrode morphologies, but only at low applied potentials. Charging dynamics are slowed appreciably at high potentials, yet not as significantly as predicted by the nonlinear transmission line model of Biesheuvel and Bazant. We identify surface conduction as a mechanism which can effectively "short circuit" the high-resistance electrolyte in the bulk of the pores, thus accelerating the charging dynamics and boosting power densities. Notably, the boost in power density holds only for electrode morphologies with continuous conducting surfaces in the charging direction.

  16. Photocurrent of Photovoltaic Cells

    Science.gov (United States)

    Peeler, Seth; McIntyre, Max; Cossel, Raquel; Bowser, Chris; Tzolov, Marian

    Photovoltaic cells can be used to harness clean, renewable energy from light. Examined in this project were photovoltaic cells based on a bulk heterojunction between PCPDTBT and PCBM sandwiched between an ITO anode and an Al cathode. Current-voltage characteristics and impedance spectra for multiple photovoltaic devices were taken under varying DC electrical bias and different level of illumination. This data was interpreted in terms of an equivalent circuit with linear elements, e.g. capacitance, series resistance, and parallel resistance. A physical interpretation of each circuit element will be presented. The spectral response of the devices was characterized by optical transmission and photocurrent spectroscopy using a spectrometer in the spectral range from 300 to 900 nm. The DC measurements confirmed that the devices are electrically rectifying. The AC measurements allowed modeling of the devices as a dielectric between two electrodes with injection current passing through it. The characteristic peaks for both PCBDTBT and PCBM are clearly visible in both the photocurrent and transmission data. The good correlation between the photocurrent and transmission data indicates photocurrent generation due to absorption in both materials constituting the heterojunction.

  17. Grating-coupled surface plasmon enhanced short-circuit current in organic thin-film photovoltaic cells.

    Science.gov (United States)

    Baba, Akira; Aoki, Nobutaka; Shinbo, Kazunari; Kato, Keizo; Kaneko, Futao

    2011-06-01

    In this study, we demonstrate the fabrication of grating-coupled surface plasmon resonance (SPR) enhanced organic thin-film photovoltaic cells and their improved photocurrent properties. The cell consists of a grating substrate/silver/P3HT:PCBM/PEDOT:PSS structure. Blu-ray disk recordable substrates are used as the diffraction grating substrates on which silver films are deposited by vacuum evaporation. P3HT:PCBM films are spin-coated on silver/grating substrates. Low conductivity PEDOT:PSS/PDADMAC layer-by-layer ultrathin films deposited on P3HT:PCBM films act as the hole transport layer, whereas high conductivity PEDOT:PSS films deposited by spin-coating act as the anode. SPR excitations are observed in the fabricated cells upon irradiation with white light. Up to a 2-fold increase in the short-circuit photocurrent is observed when the surface plasmon (SP) is excited on the silver gratings as compared to that without SP excitation. The finite-difference time-domain simulation indicates that the electric field in the P3HT:PCBM layer can be increased using the grating-coupled SP technique. © 2011 American Chemical Society

  18. A Comprehensive Investigation on the Short Circuit Performance of MW-level IGBT Power Modules

    DEFF Research Database (Denmark)

    Wu, Rui; Reigosa, Paula Diaz; Iannuzzo, Francesco

    2015-01-01

    This paper investigates the short circuit performance of commercial 1.7 kV / 1 kA IGBT power modules by means of a 6 kA Non-Destructive-Tester. A mismatched current distribution among the parallel chips has been observed, which can reduce the short circuit capability of the IGBT power module unde...... short circuit conditions. Further Spice simulations reveal that the stray parameters inside the module play an important role in contributing to such a phenomenon....

  19. Integrated Power Flow and Short Circuit Calculation Method for Distribution Network with Inverter Based Distributed Generation

    OpenAIRE

    Yang, Shan; Tong, Xiangqian

    2016-01-01

    Power flow calculation and short circuit calculation are the basis of theoretical research for distribution network with inverter based distributed generation. The similarity of equivalent model for inverter based distributed generation during normal and fault conditions of distribution network and the differences between power flow and short circuit calculation are analyzed in this paper. Then an integrated power flow and short circuit calculation method for distribution network with inverte...

  20. Research Tool to Evaluate the Safety Response of Lithium Batteries to an Internal Short Circuit

    Energy Technology Data Exchange (ETDEWEB)

    Keyser, Matthew; Darcy, Eric; Pesaran, Ahmad

    2016-06-19

    Li-ion cells provide the highest specific energy and energy density rechargeable battery with the longest life. Many safety incidents that take place in the field originate due to an internal short that was not detectable or predictable at the point of manufacture. NREL's internal short circuit (ISC) device is capable of simulating shorts and produces consistent and reproducible results. The cell behaves normally until the ISC device is activated wherein a latent defect (i.e., built into the cell during manufacturing) gradually moves into position to create an internal short while the battery is in use, providing relevant data to verify abuse models. The ISC device is an effective tool for studying the safety features of parts of Li-ion batteries.

  1. Avoiding short circuits from zinc metal dendrites in anode by backside-plating configuration

    Science.gov (United States)

    Higashi, Shougo; Lee, Seok Woo; Lee, Jang Soo; Takechi, Kensuke; Cui, Yi

    2016-01-01

    Portable power sources and grid-scale storage both require batteries combining high energy density and low cost. Zinc metal battery systems are attractive due to the low cost of zinc and its high charge-storage capacity. However, under repeated plating and stripping, zinc metal anodes undergo a well-known problem, zinc dendrite formation, causing internal shorting. Here we show a backside-plating configuration that enables long-term cycling of zinc metal batteries without shorting. We demonstrate 800 stable cycles of nickel–zinc batteries with good power rate (20 mA cm−2, 20 C rate for our anodes). Such a backside-plating method can be applied to not only zinc metal systems but also other metal-based electrodes suffering from internal short circuits. PMID:27263471

  2. Approximative calculation of transient short-circuit currents in power-systems

    Energy Technology Data Exchange (ETDEWEB)

    Heuck, K; Rosenberger, R; Dettmann, K D; Kegel, R

    1986-08-01

    The paper shows that it is approximatively possible to calculate the transient short-circuit currents for symmetrical and asymmetrical faults in power-systems. For that purpose a simple equivalent network is found. Its error of approximation is small. For the important maximum short-circuit current limits of error are pointed out compared to VDE 0102.

  3. Thirteen years test experience with short-circuit withstand capability of large power transformers

    NARCIS (Netherlands)

    Smeets, R.P.P.; Paske, te L.H.; Leufkens, P.P.; Fogelberg, T.

    2009-01-01

    The ability to withstand a short circuit is recognised more and more as an essential characteristic of power transformers. IEC and IEEE Standards, as well as other national standards specify short-circuit testing and how to check the withstand capability. Unfortunately, however, there is extensive

  4. Built-in unit with short-circuit insulation for hermetic cable ducts

    International Nuclear Information System (INIS)

    Tschacher, B.; Gurr, W.; Kusserow, J.; Katzmarek, W.

    1984-01-01

    The invention concerns a built-in unit with short-circuit insulation for hermetic cable ducts, especially for containments of nuclear power reactors. The short-circuit insulation is achieved by an insulation plate made from radiation-resistant insulating materials of high mechanical strength

  5. Fourteen years of test experience with short-circuit withstand capability of large power transformers

    NARCIS (Netherlands)

    Smeets, R.P.P.; Paske, te L.H.

    2010-01-01

    Experience is reported of short-circuit testing of large power transformers during the past 14 years by KEMA in the Netherlands. In total, 119 transformers > 25 MVA participated in the survey. KEMA shows that at initial access to standard IEC short-circuit tests, 28% failed initially in a wide range

  6. Robustness of MW-Level IGBT modules against gate oscillations under short circuit events

    DEFF Research Database (Denmark)

    Reigosa, Paula Diaz; Wu, Rui; Iannuzzo, Francesco

    2015-01-01

    The susceptibility of MW-level IGBT power modules to critical gate voltage oscillations during short circuit events has been evidenced experimentally. This paper proposes a sensitivity analysis method to better understand the oscillating behavior dependence on different operating conditions (i...... the oscillation phenomenon, as well as to further improve the device performance during short circuit....

  7. 30 CFR 77.506 - Electric equipment and circuits; overload and short-circuit protection.

    Science.gov (United States)

    2010-07-01

    ... short-circuit protection. 77.506 Section 77.506 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION... circuits; overload and short-circuit protection. Automatic circuit-breaking devices or fuses of the correct type and capacity shall be installed so as to protect all electric equipment and circuits against short...

  8. On-line diagnosis of inter-turn short circuit fault for DC brushed motor.

    Science.gov (United States)

    Zhang, Jiayuan; Zhan, Wei; Ehsani, Mehrdad

    2018-06-01

    Extensive research effort has been made in fault diagnosis of motors and related components such as winding and ball bearing. In this paper, a new concept of inter-turn short circuit fault for DC brushed motors is proposed to include the short circuit ratio and short circuit resistance. A first-principle model is derived for motors with inter-turn short circuit fault. A statistical model based on Hidden Markov Model is developed for fault diagnosis purpose. This new method not only allows detection of motor winding short circuit fault, it can also provide estimation of the fault severity, as indicated by estimation of the short circuit ratio and the short circuit resistance. The estimated fault severity can be used for making appropriate decisions in response to the fault condition. The feasibility of the proposed methodology is studied for inter-turn short circuit of DC brushed motors using simulation in MATLAB/Simulink environment. In addition, it is shown that the proposed methodology is reliable with the presence of small random noise in the system parameters and measurement. Copyright © 2018 ISA. Published by Elsevier Ltd. All rights reserved.

  9. 30 CFR 75.601-3 - Short circuit protection; dual element fuses; current ratings; maximum values.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Short circuit protection; dual element fuses... Trailing Cables § 75.601-3 Short circuit protection; dual element fuses; current ratings; maximum values. Dual element fuses having adequate current-interrupting capacity shall meet the requirements for short...

  10. Sixteen years of test experiences with short-circuit withstand capability of large power transformers

    NARCIS (Netherlands)

    Smeets, R.P.P.; Paske, te L.H.

    2012-01-01

    Experience is reported of short-circuit testing of large power transformers during the past 16 years by KEMA in the Netherlands. In total, 174 transformers > 25 MVA participated in the survey. KEMA shows that at initial access to standard IEC short-circuit tests, 24% failed initially in a wide range

  11. Three-phase short circuit calculation method based on pre-computed surface for doubly fed induction generator

    Science.gov (United States)

    Ma, J.; Liu, Q.

    2018-02-01

    This paper presents an improved short circuit calculation method, based on pre-computed surface to determine the short circuit current of a distribution system with multiple doubly fed induction generators (DFIGs). The short circuit current, injected into power grid by DFIG, is determined by low voltage ride through (LVRT) control and protection under grid fault. However, the existing methods are difficult to calculate the short circuit current of DFIG in engineering practice due to its complexity. A short circuit calculation method, based on pre-computed surface, was proposed by developing the surface of short circuit current changing with the calculating impedance and the open circuit voltage. And the short circuit currents were derived by taking into account the rotor excitation and crowbar activation time. Finally, the pre-computed surfaces of short circuit current at different time were established, and the procedure of DFIG short circuit calculation considering its LVRT was designed. The correctness of proposed method was verified by simulation.

  12. Evaporating short-circuits in the ATLAS liquid argon barrel presampler 006

    CERN Document Server

    Belhorma, B; Lund-Jensen, B; Rydström, S; Yamouni, M

    2005-01-01

    A technique to eliminate or limit the implications of short-circuits in the ATLAS barrel presampler is described. A high voltage capacitor with a large capacity is charged at different high voltages and discharged through the short-circuit which allows either to disintegrate the dust being the origin of the short-circuit, or to burn away a thin etched copper strip which acts as a fuse on the corresponding presampler anode. This effect is possible even in the presence of a resistive HV cable (10 to 30 ohms) in series which dampens the pulse.

  13. Direct observation of short-circuit diffusion during the formation of a single cupric oxide nanowire

    International Nuclear Information System (INIS)

    Cheng, C-L; Ma, Y-R; Chou, M H; Huang, C Y; Yeh, V; Wu, S Y

    2007-01-01

    Short-circuit diffusion was observed in a single CuO nanowire synthesized using a thermal oxidation method. The confocal Raman spectra of a single CuO nanowire permit direct observation of the nature of an individual CuO nanowire. The parameter order obtained from the inverse Raman B g 2 peak linewidth results in the length dependence of the linewidth and a short-circuit diffusion length of 3.3 μm. The observed structural information is also consistent with the energy dispersive x-ray spectroscopic mapping. The results confirm that the growth of CuO nanowires occurs through the short-circuit diffusion mechanism

  14. Non-Destructive Investigation on Short Circuit Capability of Wind-Turbine-Scale IGBT Power Modules

    DEFF Research Database (Denmark)

    Wu, Rui; Iannuzzo, Francesco; Wang, Huai

    2014-01-01

    This paper presents a comprehensive investigation on the short circuit capability of wind-turbine-scale IGBT power modules by means of a 6 kA/1.1 kV non-destructive testing system. A Field Programmable Gate Array (FPGA) supervising unit is adpoted to achieve an accurate time control for short...... circuit test, which enables to define the driving signals with an accuracy of 10 ns. Thanks to the capability and the effectiveness of the constructed setup, oscillations appearing during short circuits of the new-generation 1.7 kV/1 kA IGBT power modules have been evidenced and characterized under...

  15. 30 CFR 77.506-1 - Electric equipment and circuits; overload and short circuit protection; minimum requirements.

    Science.gov (United States)

    2010-07-01

    ... short circuit protection; minimum requirements. 77.506-1 Section 77.506-1 Mineral Resources MINE SAFETY...-1 Electric equipment and circuits; overload and short circuit protection; minimum requirements. Devices providing either short circuit protection or protection against overload shall conform to the...

  16. 30 CFR 75.518-1 - Electric equipment and circuits; overload and short circuit protection; minimum requirements.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Electric equipment and circuits; overload and short circuit protection; minimum requirements. 75.518-1 Section 75.518-1 Mineral Resources MINE SAFETY... short circuit protection; minimum requirements. A device to provide either short circuit protection or...

  17. Short-circuited coil in a solenoid circuit of a pulse magnetic field

    International Nuclear Information System (INIS)

    Kivshik, A.F.; Dubrovin, V.Yu.

    1976-01-01

    A short-circuited coil at the end of a long pulse solenoid attenuates the dissipation field by 3-5 times. A plug-configuration field is set up in the middle portion of the pulse solenoid incorporating the short-circuited coils. Shunting of the coils with the induction current by resistor Rsub(shunt) provides for the adjustment of the plug ratio γ

  18. PSPICE simulation of bipolar pulse converter based on short-circuited coaxial transmission line

    International Nuclear Information System (INIS)

    Shi Lei; Fan Yajun

    2010-01-01

    The operating principle of the bipolar pulse converter based on short-circuited coaxial transmission line type is given. The output bipolar pulses are simulated by using PSPICE program on condition of different electric length and different impedance of the short-circuited coaxial transmission line. The bipolar pulses are generated by using unipolar pulse with pulse width of 2 ns in experiment, the experimental result fit well with the simulation result. (authors)

  19. Modeling of Short-Circuit-Related Thermal Stress in Aged IGBT Modules

    DEFF Research Database (Denmark)

    Bahman, Amir Sajjad; Iannuzzo, Francesco; Uhrenfeldt, Christian

    2017-01-01

    In this paper, the thermal stress on bond wires of aged IGBT modules under short-circuit conditions has been studied with respect to different solder delamination levels. To ensure repeatable test conditions, ad-hoc DBC (direct bond copper) samples with delaminated solder layers have been purposely...... in the surface temperature distribution, which confirms the hypothesis that short-circuit events produce significantly uneven stresses on bond wires....

  20. Prediction of Short-Circuit-Related Thermal Stress in Aged IGBT Modules

    DEFF Research Database (Denmark)

    Bahman, Amir Sajjad; Iannuzzo, Francesco; Uhrenfeldt, Christian

    2016-01-01

    In this paper, the thermal stress on bond wires of aged IGBT modules under short-circuit conditions has been studied with respect to different solder delamination levels. To ensure repeatable test conditions, ad-hoc DBC (direct bond copper) samples with delaminated solder layers have been purposely...... in the surface temperature distribution which confirms the hypothesis that short-circuit events produce significantly uneven stresses on bond wires....

  1. Short-Circuit Current Analysis for DFIG Wind Farm Considering the Action of a Crowbar

    Directory of Open Access Journals (Sweden)

    Yan Hong Yuan

    2018-02-01

    Full Text Available With the increasing capacity of wind farms integrated into the power grid, the short-circuit current analysis for wind farms becomes more and more important. Since the wind turbine is usually integrated into the power grid via power electronic devices, the “crowbar” is installed in the wind turbine to protect the power electronic devices and to improve the fault ride through capability. The impact of the crowbar has to be considered during the short-circuit current analysis for the wind farm. In order to fully analyze the short-circuit current characteristics of a wind farm, the short-circuit currents for a doubly-fed induction generator (DFIG wind turbine under symmetrical and asymmetrical faults considering the crowbar action characteristic are derived firstly. Then the action situation of the crowbar of a DFIG wind turbine is studied and the action area curve is obtained. Taking the crowbar action, or not, as the grouping criterion, wind turbines in the wind farm are divided into two groups, and the wind farm is aggregated into two equivalent wind turbines. Using the equivalent model, the short-circuit current of a wind farm can be calculated accurately. Finally, simulations are performed in MATLAB/Simulink which is the commercial math software produced by the MathWorks company in Natick, Massachusetts, the United States to verify the proposed short-circuit current calculation method for the DFIG wind farm.

  2. Minimum short-circuit ratios for grid interconnection of wind farms with induction generators

    Energy Technology Data Exchange (ETDEWEB)

    Reginatto, Romeu; Rocha, Carlos [Western Parana State University (UNIOESTE), Foz do Iguacu, PR (Brazil). Center for Engineering and Exact Sciences], Emails: romeu@unioeste.br, croberto@unioeste.br

    2009-07-01

    This paper concerns the problem of determining the minimum value for the short-circuit ratio which is adequate for the interconnection of a given wind farms to a given grid point. First, a set of 3 criteria is defined in order to characterize the quality/safety of the interconnection: acceptable terminal voltage variations, a minimum active power margin, and an acceptable range for the internal voltage angle. Then, the minimum short circuit ratio requirement is determined for 6 different induction generator based wind turbines, both fixed-speed (with and without reactive power compensation) and variable-speed (with the following control policies: reactive power, power factor, and terminal voltage regulation). The minimum short-circuit ratio is determined and shown in graphical results for the 6 wind turbines considered, for X/R in the range 0-15, also analyzing the effect of more/less stringent tolerances for the interconnection criteria. It is observed that the tighter the tolerances the larger the minimum short-circuit ratio required. For the same tolerances in the interconnection criteria, a comparison of the minimum short circuit ratio required for the interconnection of both squirrel-cage and doubly-fed induction generators is presented, showing that the last requires much smaller values for the short-circuit ratio. (author)

  3. Modulating light propagation in ZnO-Cu₂O-inverse opal solar cells for enhanced photocurrents.

    Science.gov (United States)

    Yantara, Natalia; Pham, Thi Thu Trang; Boix, Pablo P; Mathews, Nripan

    2015-09-07

    The advantages of employing an interconnected periodic ZnO morphology, i.e. an inverse opal structure, in electrodeposited ZnO/Cu2O devices are presented. The solar cells are fabricated using low cost solution based methods such as spin coating and electrodeposition. The impact of inverse opal geometry, mainly the diameter and thickness, is scrutinized. By employing 3 layers of an inverse opal structure with a 300 nm pore diameter, higher short circuit photocurrents (∼84% improvement) are observed; however the open circuit voltages decrease with increasing interfacial area. Optical simulation using a finite difference time domain method shows that the inverse opal structure modulates light propagation within the devices such that more photons are absorbed close to the ZnO/Cu2O junction. This increases the collection probability resulting in improved short circuit currents.

  4. The Simulation Computer Based Learning (SCBL) for Short Circuit Multi Machine Power System Analysis

    Science.gov (United States)

    Rahmaniar; Putri, Maharani

    2018-03-01

    Strengthening Competitiveness of human resources become the reply of college as a conductor of high fomal education. Electrical Engineering Program UNPAB (Prodi TE UNPAB) as one of the department of electrical engineering that manages the field of electrical engineering expertise has a very important part in preparing human resources (HR), Which is required by where graduates are produced by DE UNPAB, Is expected to be able to compete globally, especially related to the implementation of Asean Economic Community (AEC) which requires the active participation of graduates with competence and quality of human resource competitiveness. Preparation of HR formation Competitive is done with the various strategies contained in the Seven (7) Higher Education Standard, one part of which is the implementation of teaching and learning process in Electrical system analysis with short circuit analysis (SCA) This course is a course The core of which is the basis for the competencies of other subjects in the advanced semester at Development of Computer Based Learning model (CBL) is done in the learning of interference analysis of multi-machine short circuit which includes: (a) Short-circuit One phase, (B) Two-phase Short Circuit Disruption, (c) Ground Short Circuit Disruption, (d) Short Circuit Disruption One Ground Floor Development of CBL learning model for Electrical System Analysis course provides space for students to be more active In learning in solving complex (complicated) problems, so it is thrilling Ilkan flexibility of student learning how to actively solve the problem of short-circuit analysis and to form the active participation of students in learning (Student Center Learning, in the course of electrical power system analysis.

  5. Method of repair of short circuits for in-situ leaching

    International Nuclear Information System (INIS)

    Baughman, D.R.; Bergeson, J.R.

    1984-01-01

    In an acidic in-situ leaching system, a short circuit passage through a subterranean formation between a fracture associated with an injection well and a fracture associated with a production well can be plugged by introducing a non-acidic liquid for displacing acidic leach liquid from the short circuit passage, introducing into the injection well a basic composition including a sealing material that gels under acidic conditions, and introducing sufficient liquid into the injection well to displace at least a portion of the basic composition containing sealing material from the injection well into the short circuit passage. Liquid flow between the injection well and the production well is then discontinued for a sufficient time for residual acid in the subterranean formation surrounding the short circuit passage to contact the sealing material and cause gelation of the sealing material in the short circuit passage. The introduction of acidic leach liquid to the formation can then continue. The sealing material may be a polymer or a water soluble silicate

  6. Short Circuits of a 10 MW High Temperature Superconducting Wind Turbine Generator

    DEFF Research Database (Denmark)

    Song, Xiaowei (Andy); Liu, Dong; Polinder, Henk

    2016-01-01

    Direct drive high temperature superconducting (HTS) wind turbine generators have been proposed to tackle challenges for ever increasing wind turbine ratings. Due to smaller reactances in HTS generators, higher fault currents and larger transient torques could occur if sudden short circuits happen...... at generator terminals. In this paper, a finite element model that couples magnetic fields and the generator’s equivalent circuits is developed to simulate short circuit faults. Afterwards, the model is used to study the transient performance of a 10 MW HTS wind turbine generator under four different short...... that the short circuits pose great challenges to the generator, and careful consideration should be given to protect the generator. The results presented in this paper would be beneficial to the design, operation and protection of an HTS wind turbine generator....

  7. Short Circuits of a 10-MW High-Temperature Superconducting Wind Turbine Generator

    DEFF Research Database (Denmark)

    Song, Xiaowei (Andy); Liu, Dong; Polinder, Henk

    2017-01-01

    Direct Drive high-temperature superconducting (HTS) wind turbine generators have been proposed to tackle challenges for ever increasing wind turbine ratings. Due to smaller reactances in HTS generators, higher fault currents and larger transient torques could occur if sudden short circuits take...... place at generator terminals. In this paper, a finite element model that couples magnetic fields and the generator's equivalent circuits is developed to simulate short-circuit faults. Afterward, the model is used to study the transient performance of a 10-MW HTS wind turbine generator under four...... show that the short circuits pose great challenges to the generator, and careful consideration should be given to protect the generator. The findings presented in this paper would be beneficial to the design, operation and protection of an HTS wind turbine generator....

  8. Fault Detection and Location of IGBT Short-Circuit Failure in Modular Multilevel Converters

    Directory of Open Access Journals (Sweden)

    Bin Jiang

    2018-06-01

    Full Text Available A single fault detection and location for Modular Multilevel Converter (MMC is of great significance, as numbers of sub-modules (SMs in MMC are connected in series. In this paper, a novel fault detection and location method is proposed for MMC in terms of the Insulated Gate Bipolar Translator (IGBT short-circuit failure in SM. The characteristics of IGBT short-circuit failures are analyzed, based on which a Differential Comparison Low-Voltage Detection Method (DCLVDM is proposed to detect the short-circuit fault. Lastly, the faulty IGBT is located based on the capacitor voltage of the faulty SM by Continuous Wavelet Transform (CWT. Simulations have been done in the simulation software PSCAD/EMTDC and the results confirm the validity and reliability of the proposed method.

  9. In-situ short-circuit protection system and method for high-energy electrochemical cells

    Science.gov (United States)

    Gauthier, Michel; Domroese, Michael K.; Hoffman, Joseph A.; Lindeman, David D.; Noel, Joseph-Robert-Gaetan; Radewald, Vern E.; Rouillard, Jean; Rouillard, Roger; Shiota, Toshimi; Trice, Jennifer L.

    2003-04-15

    An in-situ thermal management system for an energy storage device. The energy storage device includes a plurality of energy storage cells each being coupled in parallel to common positive and negative connections. Each of the energy storage cells, in accordance with the cell's technology, dimensions, and thermal/electrical properties, is configured to have a ratio of energy content-to-contact surface area such that thermal energy produced by a short-circuit in a particular cell is conducted to a cell adjacent the particular cell so as to prevent the temperature of the particular cell from exceeding a breakdown temperature. In one embodiment, a fuse is coupled in series with each of a number of energy storage cells. The fuses are activated by a current spike capacitively produced by a cell upon occurrence of a short-circuit in the cell, thereby electrically isolating the short-circuited cell from the common positive and negative connections.

  10. In-situ short circuit protection system and method for high-energy electrochemical cells

    Science.gov (United States)

    Gauthier, Michel; Domroese, Michael K.; Hoffman, Joseph A.; Lindeman, David D.; Noel, Joseph-Robert-Gaetan; Radewald, Vern E.; Rouillard, Jean; Rouillard, Roger; Shiota, Toshimi; Trice, Jennifer L.

    2000-01-01

    An in-situ thermal management system for an energy storage device. The energy storage device includes a plurality of energy storage cells each being coupled in parallel to common positive and negative connections. Each of the energy storage cells, in accordance with the cell's technology, dimensions, and thermal/electrical properties, is configured to have a ratio of energy content-to-contact surface area such that thermal energy produced by a short-circuit in a particular cell is conducted to a cell adjacent the particular cell so as to prevent the temperature of the particular cell from exceeding a breakdown temperature. In one embodiment, a fuse is coupled in series with each of a number of energy storage cells. The fuses are activated by a current spike capacitively produced by a cell upon occurrence of a short-circuit in the cell, thereby electrically isolating the short-circuited cell from the common positive and negative connections.

  11. Data on the natural ventilation performance of windcatcher with anti-short-circuit device (ASCD).

    Science.gov (United States)

    Nejat, Payam; Calautit, John Kaiser; Majid, Muhd Zaimi Abd; Hughes, Ben Richard; Jomehzadeh, Fatemeh

    2016-12-01

    This article presents the datasets which were the results of the study explained in the research paper 'Anti-short-circuit device: a new solution for short-circuiting in windcatcher and improvement of natural ventilation performance' (P. Nejat, J.K. Calautit, M.Z. Abd. Majid, B.R. Hughes, F. Jomehzadeh, 2016) [1] which introduces a new technique to reduce or prevent short-circuiting in a two-sided windcatcher and also lowers the indoor CO2 concentration and improve the ventilation distribution. Here, we provide details of the numerical modeling set-up and data collection method to facilitate reproducibility. The datasets includes indoor airflow, ventilation rates and CO2 concentration data at several points in the flow field. The CAD geometry of the windcatcher models are also included.

  12. Allocation of synchronous condensers for restoration of system short-circuit power

    DEFF Research Database (Denmark)

    Marrazi, Emanuel; Yang, Guangya; Weinreich-Jensen, Peter

    2017-01-01

    Modern power systems, employing an increasing number of converter-based renewable energy sources (RES) and decreasing the usage of conventional power plants, are leading to lower levels of short-circuit power and rotational inertia. A solution to this is the employment of synchronous condensers...... in the grid, in order to provide sufficient short-circuit power. This results in the increase of the short-circuit ratio (SCR) at transmission system bus-bars serving as points of interconnection (POI) to renewable generation. Evaluation of the required capacity and grid-location of the synchronous condensers......, isinherently a mixed integer non-linear optimization problem, which could not be done on manual basis considering each type of machine and all bus-bars. This study therefore proposes a method of optimal allocation of synchronous condensers in a hypothetic future scenario of a transmission system fed...

  13. Allocation of synchronous condensers for restoration of system short-circuit power

    DEFF Research Database (Denmark)

    Marrazi, Emanuel; Yang, Guangya; Weinreich-Jensen, Peter

    2017-01-01

    Modern power systems, employing an increasing number of converter-based renewable energy sources (RES) and decreasing the usage of conventional power plants, are leading to lower levels of short-circuit power and rotational inertia. A solution to this is the employment of synchronous condensers...... in the grid, in order to provide sufficient short-circuit power. This results in the increase of the short-circuit ratio (SCR) at transmission system bus-bars serving as points of interconnection (POI) to renewable generation. Evaluation of the required capacity and grid-location of the synchronous condensers...... by renewable generation. Total cost of synchronous condenser installations in the system is minimized and the SCRs at the POIs of central renewable power plants are strengthened. The method has potential for application on larger grids, aiding grid-integration of RES....

  14. Controlled Conjugated Backbone Twisting for an Increased Open-Circuit Voltage while Having a High Short-Circuit Current in Poly(hexylthiophene) Derivatives

    KAUST Repository

    Ko, Sangwon

    2012-03-21

    Conjugated polymers with nearly planar backbones have been the most commonly investigated materials for organic-based electronic devices. More twisted polymer backbones have been shown to achieve larger open-circuit voltages in solar cells, though with decreased short-circuit current densities. We systematically impose twists within a family of poly(hexylthiophene)s and examine their influence on the performance of polymer:fullerene bulk heterojunction (BHJ) solar cells. A simple chemical modification concerning the number and placement of alkyl side chains along the conjugated backbone is used to control the degree of backbone twisting. Density functional theory calculations were carried out on a series of oligothiophene structures to provide insights on how the sterically induced twisting influences the geometric, electronic, and optical properties. Grazing incidence X-ray scattering measurements were performed to investigate how the thin-film packing structure was affected. The open-circuit voltage and charge-transfer state energy of the polymer:fullerene BHJ solar cells increased substantially with the degree of twist induced within the conjugated backbone-due to an increase in the polymer ionization potential-while the short-circuit current decreased as a result of a larger optical gap and lower hole mobility. A controlled, moderate degree of twist along the poly(3,4-dihexyl-2,2′:5′,2′′- terthiophene) (PDHTT) conjugated backbone led to a 19% enhancement in the open-circuit voltage (0.735 V) vs poly(3-hexylthiophene)-based devices, while similar short-circuit current densities, fill factors, and hole-carrier mobilities were maintained. These factors resulted in a power conversion efficiency of 4.2% for a PDHTT:[6,6]-phenyl-C 71-butyric acid methyl ester (PC 71BM) blend solar cell without thermal annealing. This simple approach reveals a molecular design avenue to increase open-circuit voltage while retaining the short-circuit current. © 2012 American

  15. Controlled conjugated backbone twisting for an increased open-circuit voltage while having a high short-circuit current in poly(hexylthiophene) derivatives.

    Science.gov (United States)

    Ko, Sangwon; Hoke, Eric T; Pandey, Laxman; Hong, Sanghyun; Mondal, Rajib; Risko, Chad; Yi, Yuanping; Noriega, Rodrigo; McGehee, Michael D; Brédas, Jean-Luc; Salleo, Alberto; Bao, Zhenan

    2012-03-21

    Conjugated polymers with nearly planar backbones have been the most commonly investigated materials for organic-based electronic devices. More twisted polymer backbones have been shown to achieve larger open-circuit voltages in solar cells, though with decreased short-circuit current densities. We systematically impose twists within a family of poly(hexylthiophene)s and examine their influence on the performance of polymer:fullerene bulk heterojunction (BHJ) solar cells. A simple chemical modification concerning the number and placement of alkyl side chains along the conjugated backbone is used to control the degree of backbone twisting. Density functional theory calculations were carried out on a series of oligothiophene structures to provide insights on how the sterically induced twisting influences the geometric, electronic, and optical properties. Grazing incidence X-ray scattering measurements were performed to investigate how the thin-film packing structure was affected. The open-circuit voltage and charge-transfer state energy of the polymer:fullerene BHJ solar cells increased substantially with the degree of twist induced within the conjugated backbone--due to an increase in the polymer ionization potential--while the short-circuit current decreased as a result of a larger optical gap and lower hole mobility. A controlled, moderate degree of twist along the poly(3,4-dihexyl-2,2':5',2''-terthiophene) (PDHTT) conjugated backbone led to a 19% enhancement in the open-circuit voltage (0.735 V) vs poly(3-hexylthiophene)-based devices, while similar short-circuit current densities, fill factors, and hole-carrier mobilities were maintained. These factors resulted in a power conversion efficiency of 4.2% for a PDHTT:[6,6]-phenyl-C(71)-butyric acid methyl ester (PC(71)BM) blend solar cell without thermal annealing. This simple approach reveals a molecular design avenue to increase open-circuit voltage while retaining the short-circuit current.

  16. Short-Circuit Current Analysis for DFIG Wind Farm Considering the Action of a Crowbar

    OpenAIRE

    Yan Hong Yuan; Feng Wu

    2018-01-01

    With the increasing capacity of wind farms integrated into the power grid, the short-circuit current analysis for wind farms becomes more and more important. Since the wind turbine is usually integrated into the power grid via power electronic devices, the “crowbar” is installed in the wind turbine to protect the power electronic devices and to improve the fault ride through capability. The impact of the crowbar has to be considered during the short-circuit current analysis for the wind farm....

  17. Influence of an inner short-circuit on the behaviour of the superconducting magnet

    International Nuclear Information System (INIS)

    Zizek, F.

    1984-01-01

    On exciting one of the superconducting quadrupole magnets, voltage pulses were observed on the winding outlets. Over a certain current level the pulses disappeared and a quench of the magnet was registered. A subsequent analysis proved that phenomenon was caused by short-circuiting of the turns inside one of the quadrupole coils. The voltage pulses were caused by repeated quenches of the short-circuited part of the winding. The above effect did not appear until a certain rate of rise of the current was attained

  18. Influence of an inner short-circuit on the behaviour of the superconducting magnet

    Energy Technology Data Exchange (ETDEWEB)

    Zizek, F. (Skoda k.p., Plzen (Czechoslovakia))

    1984-01-01

    On exciting one of the superconducting quadrupole magnets, voltage pulses were observed on the winding outlets. Over a certain current level the pulses disappeared and a quench of the magnet was registered. A subsequent analysis proved that phenomenon was caused by short-circuiting of the turns inside one of the quadrupole coils. The voltage pulses were caused by repeated quenches of the short-circuited part of the winding. The above effect did not appear until a certain rate of rise of the current was attained.

  19. Forces and stresses in cryoturbogenerator rotor in presence of short circuit

    International Nuclear Information System (INIS)

    Kovarskii, M.E.; Rubinraut, A.M.; Tsyrlin, A.L.

    1981-01-01

    A method is presented for determining the electrodynamic forces, mechanical stresses, and strains in the shells of a cryogenic-turbogenerator cryostat in the presence of an abrupt short circuit. The physical pattern of occurrence of forces in a cryostat shell is considered for capacitive, inductive, and active armature-current cases. It is shown that in addition to the radial component, there is a tangential component of the electrodynamic forces, with the interaction of the two components governing the strength in the presence of short circuits. Results are reported for mechanical-strength calculations, based on the proposed method, for a 200 kw cryogenic turbogenerator

  20. Clearance of short circuited ion optics electrodes by capacitive discharge. [in ion thrusters

    Science.gov (United States)

    Poeschel, R. L.

    1976-01-01

    The ion optics electrodes of low specific impulse (3000 sec) mercury electron bombardment ion thrusters are vulnerable to short circuits by virtue of their relatively small interelectrode spacing (0.5 mm). Metallic flakes from backsputtered deposits are the most probable cause of such 'shorts' and 'typical' flakes have been simulated here using refractory wire that has a representative, but controllable, cross section. Shorting wires can be removed by capacitive discharge without significant damage to the electrodes. This paper describes an evaluation of 'short' removal versus electrode damage for several combinations of capacitor voltage, stored energy, and short circuit conditions.

  1. Voltage Recovery of Grid-Connected Wind Turbines with DFIG After a Short-Circuit Fault

    DEFF Research Database (Denmark)

    Sun, Tao; Chen, Zhe; Blaabjerg, Frede

    2004-01-01

    The fast development of wind power generation brings new requirements for wind turbine integration to the network. After clearance of an external short-circuit fault, the voltage at the wind turbine terminal should be re-established with minimized power losses. This paper concentrates on voltage......-establish the wind turbine terminal voltage after the clearance of an external short-circuit fault, and the restore the normal operation of the variable speed wind turbine with DFIG, which has been demonstrated by simulation results....

  2. Characteristics of photocurrent generation in the near-ultraviolet region in Si quantum-dot sensitized solar cells

    International Nuclear Information System (INIS)

    Uchida, Giichiro; Sato, Muneharu; Seo, Hyunwoong; Kamataki, Kunihiro; Itagaki, Naho; Koga, Kazunori; Shiratani, Masaharu

    2013-01-01

    We have studied photocurrent generation in Si quantum-dot (QD) sensitized solar cells, where QD thin films composed of Si nanoparticles were deposited using the double multi-hollow discharge plasma chemical vapor deposition process in an SiH 4 /H 2 and CH 4 or N 2 gas mixture. The short-circuit current density of the Si QD sensitized solar cells increases by a factor of 2.5 by using Si nanoparticles prepared by irradiation of CH 4 or N 2 plasma onto the Si nanoparticle surface. We have measured incident photon-to-current conversion efficiency (IPCE) in the near-ultraviolet range using quartz-glass front panels of the QD sensitized solar cells. With decreasing the wavelength of irradiation light, IPCE gradually increases upon light irradiation in a wavelength range less than about 600 nm, and then steeply increases below 300 nm, corresponding to 2.2 times the optical band-gap energy of Si QD film. - Highlights: • We have developed on Si quantum-dot sensitized solar cells using Si particles. • Current of solar cells increases by surface-termination of Si particles. • Incident photo-to-current conversion efficiency increases below 300 nm

  3. Characteristics of photocurrent generation in the near-ultraviolet region in Si quantum-dot sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Uchida, Giichiro, E-mail: uchida@ed.kyushu-u.ac.jp [Graduate School of Information Science and Electrical Engineering, Kyushu University, Fukuoka 819-0395 (Japan); Sato, Muneharu; Seo, Hyunwoong [Graduate School of Information Science and Electrical Engineering, Kyushu University, Fukuoka 819-0395 (Japan); Kamataki, Kunihiro [Faculty of Arts and Science, Kyushu University, Fukuoka 819-0395 (Japan); Itagaki, Naho [Graduate School of Information Science and Electrical Engineering, Kyushu University, Fukuoka 819-0395 (Japan); PRESTO, Japan Science and Technology Agency, Tokyo 102-0075 (Japan); Koga, Kazunori; Shiratani, Masaharu [Graduate School of Information Science and Electrical Engineering, Kyushu University, Fukuoka 819-0395 (Japan)

    2013-10-01

    We have studied photocurrent generation in Si quantum-dot (QD) sensitized solar cells, where QD thin films composed of Si nanoparticles were deposited using the double multi-hollow discharge plasma chemical vapor deposition process in an SiH{sub 4}/H{sub 2} and CH{sub 4} or N{sub 2} gas mixture. The short-circuit current density of the Si QD sensitized solar cells increases by a factor of 2.5 by using Si nanoparticles prepared by irradiation of CH{sub 4} or N{sub 2} plasma onto the Si nanoparticle surface. We have measured incident photon-to-current conversion efficiency (IPCE) in the near-ultraviolet range using quartz-glass front panels of the QD sensitized solar cells. With decreasing the wavelength of irradiation light, IPCE gradually increases upon light irradiation in a wavelength range less than about 600 nm, and then steeply increases below 300 nm, corresponding to 2.2 times the optical band-gap energy of Si QD film. - Highlights: • We have developed on Si quantum-dot sensitized solar cells using Si particles. • Current of solar cells increases by surface-termination of Si particles. • Incident photo-to-current conversion efficiency increases below 300 nm.

  4. Verification of the short-circuit current making capability of high-voltage switching devices

    NARCIS (Netherlands)

    Smeets, R.P.P.; Linden, van der W.A.

    2001-01-01

    Switching-in of short-circuit current leads to pre-arcing in the switching device. Pre-arcing affects the ability of switchgear to close and latch. In three-phase systems, making is associated with transient voltage phenomena that may have a significant impact on the duration of the pre-arcing

  5. Development of internal/external short circuit protection for lithium D cells

    Science.gov (United States)

    Mcdonald, Robert C.; Bragg, Bobby J.

    1992-01-01

    A brief discussion of short circuit protection for lithium D cells is given in viewgraph format. The following topics are presented: (1) historical need; (2) program objectives; (3) composite thermal switch (CTS) development; (4) laboratory cells with CTS; and (5) the incorporation of CTS into lithium D cells.

  6. Short Circuits of a 10 MW High Temperature Superconducting Wind Turbine Generator

    NARCIS (Netherlands)

    Song, X.; Polinder, H.; Liu, D.; Mijatovic, Nenad; Holbøll, Joachim; Jensen, Bogi Bech

    Direct drive high temperature superconducting (HTS) wind turbine generators have been proposed to tackle challenges for ever increasing wind turbine ratings. Due to smaller reactances in HTS generators, higher fault currents and larger transient torques could occur if sudden short circuits happen at

  7. Electro-thermal modeling of high power IGBT module short-circuits with experimental validation

    DEFF Research Database (Denmark)

    Wu, Rui; Iannuzzo, Francesco; Wang, Huai

    2015-01-01

    A novel Insulated Gate Bipolar Transistor (IGBT) electro-thermal modeling approach involving PSpice and ANSYS/Icepak with both high accuracy and simulation speed has been presented to study short-circuit of a 1.7 kV/1 kA commercial IGBT module. The approach successfully predicts the current...

  8. Network model and short circuit program for the Kennedy Space Center electric power distribution system

    Science.gov (United States)

    1976-01-01

    Assumptions made and techniques used in modeling the power network to the 480 volt level are discussed. Basic computational techniques used in the short circuit program are described along with a flow diagram of the program and operational procedures. Procedures for incorporating network changes are included in this user's manual.

  9. Estimating the Probability of Electrical Short Circuits from Tin Whiskers. Part 2

    Science.gov (United States)

    Courey, Karim J.; Asfour, Shihab S.; Onar, Arzu; Bayliss, Jon A.; Ludwig, Larry L.; Wright, Maria C.

    2010-01-01

    To comply with lead-free legislation, many manufacturers have converted from tin-lead to pure tin finishes of electronic components. However, pure tin finishes have a greater propensity to grow tin whiskers than tin-lead finishes. Since tin whiskers present an electrical short circuit hazard in electronic components, simulations have been developed to quantify the risk of said short circuits occurring. Existing risk simulations make the assumption that when a free tin whisker has bridged two adjacent exposed electrical conductors, the result is an electrical short circuit. This conservative assumption is made because shorting is a random event that had an unknown probability associated with it. Note however that due to contact resistance electrical shorts may not occur at lower voltage levels. In our first article we developed an empirical probability model for tin whisker shorting. In this paper, we develop a more comprehensive empirical model using a refined experiment with a larger sample size, in which we studied the effect of varying voltage on the breakdown of the contact resistance which leads to a short circuit. From the resulting data we estimated the probability distribution of an electrical short, as a function of voltage. In addition, the unexpected polycrystalline structure seen in the focused ion beam (FIB) cross section in the first experiment was confirmed in this experiment using transmission electron microscopy (TEM). The FIB was also used to cross section two card guides to facilitate the measurement of the grain size of each card guide's tin plating to determine its finish .

  10. Short-Circuit Robustness Assessment in Power Electronic Modules for Megawatt Applications

    DEFF Research Database (Denmark)

    Iannuzzo, Francesco

    2016-01-01

    In this paper, threats and opportunities in testing of megawatt power electronic modules under short circuit are presented and discussed, together with the introduction of some basic principles of non-destructive testing, a key technique to allow post-failure analysis. The non-destructive testing...

  11. L2 Reading Ability: Further Insight into the Short-Circuit Hypothesis.

    Science.gov (United States)

    Taillefer, Gail F.

    1996-01-01

    Discusses the notion of a language proficiency threshold that short circuits the transfer of reading ability from the native language (L1) to a second language (L2). This study, in which cognitive complexity of tasks and students' L2 proficiency levels vary, focuses on university students in France reading preprofessional English texts. (39…

  12. Integrated Power Flow and Short Circuit Calculation Method for Distribution Network with Inverter Based Distributed Generation

    Directory of Open Access Journals (Sweden)

    Shan Yang

    2016-01-01

    Full Text Available Power flow calculation and short circuit calculation are the basis of theoretical research for distribution network with inverter based distributed generation. The similarity of equivalent model for inverter based distributed generation during normal and fault conditions of distribution network and the differences between power flow and short circuit calculation are analyzed in this paper. Then an integrated power flow and short circuit calculation method for distribution network with inverter based distributed generation is proposed. The proposed method let the inverter based distributed generation be equivalent to Iθ bus, which makes it suitable to calculate the power flow of distribution network with a current limited inverter based distributed generation. And the low voltage ride through capability of inverter based distributed generation can be considered as well in this paper. Finally, some tests of power flow and short circuit current calculation are performed on a 33-bus distribution network. The calculated results from the proposed method in this paper are contrasted with those by the traditional method and the simulation method, whose results have verified the effectiveness of the integrated method suggested in this paper.

  13. Results of experimental research of the modes of short circuit in a traction network

    Directory of Open Access Journals (Sweden)

    P.Ye. Mykhalichenko

    2012-08-01

    Full Text Available In the article the results, namely oscillograms of the transitional feeder electric values obtained by the experimental tests of the short circuit modes in case of setting off different types of substation fast-acting switches are presented. The experiments were conducted on the operating electrified track sections of the Prydniprovs’ka Railway.

  14. EQUATIONS OF ELECTRIC MOTOR POWER SUPPLY UNIT DISSYMMETRY UNDER PHASE SHORT-CIRCUIT FAULT

    Directory of Open Access Journals (Sweden)

    V.Y. Tchaban

    2013-04-01

    Full Text Available In the paper, a formula is introduced for calculating electric motor supply unit voltage under feeding by a common transformer in the condition of a phase short-circuit in one of the motors. The formula is used in every time step of electromechanical state equations integration.

  15. The influence of gamma irradiation on short-circuit current in CuGaSe2

    International Nuclear Information System (INIS)

    Gasimoglu, I.; Mamedova, I.A.; Bagirov, A.G.

    2005-01-01

    Full text : The influence of gamma irradiation on a short-circuit current at 77 K was investigated. The appeared strip with a maximum at 1,61 ///// after irradiation in spectral dependence connected with p-type radiating defects [ru

  16. Comparison of short-circuit characteristics of trench gate and planar gate U-shaped channel SOI-LIGBTs

    Science.gov (United States)

    Zhang, Long; Zhu, Jing; Sun, Weifeng; Zhao, Minna; Huang, Xuequan; Chen, Jiajun; Shi, Longxing; Chen, Jian; Ding, Desheng

    2017-09-01

    Comparison of short-circuit (SC) characteristics of 500 V rated trench gate U-shaped channel (TGU) SOI-LIGBT and planar gate U-shaped channel (PGU) SOI-LIGBT is made for the first time in this paper. The on-state carrier profile of the TGU structure is reshaped by the dual trenches (a gate trench G1 and a hole barrier trench G2), which leads to a different conduction behavior from that of the PGU structure. The TGU structure exhibits a higher latchup immunity but a severer self-heating effect. At current density (JC) 640 A/cm2. Comparison of layouts and fabrication processes are also made between the two types of devices.

  17. Strong photocurrent enhancements in plasmonic organic photovoltaics by biomimetic nanoarchitectures with efficient light harvesting.

    Science.gov (United States)

    Leem, Jung Woo; Kim, Sehwan; Park, Chihyun; Kim, Eunkyoung; Yu, Jae Su

    2015-04-01

    We propose the biomimetic moth-eye nanoarchitectures as a novel plasmonic light-harvesting structure for further enhancing the solar-generated photocurrents in organic photovoltaics (OPVs). The full moth-eye nanoarchitectures are composed of two-dimensional hexagonal periodic grating arrays on surfaces of both the front zinc oxide (ZnO) and rear active layers, which are prepared by a simple and cost-effective soft imprint nanopatterning technique. For the 380 nm period ZnO and 650 nm period active gratings (i.e., ZnO(P380)/Active(P650)), the poly(3-hexylthiophene-2,5-diyl):indene-C60 bis-adduct (P3HT:ICBA)-based plasmonic OPVs exhibit an improvement of the absorption spectrum compared to the pristine OPVs over a broad wavelength range of 350-750 nm, showing absorption enhancement peaks at wavelengths of ∼370, 450, and 670 nm, respectively. This leads to a considerable increase of short-circuit current density (Jsc) from 10.9 to 13.32 mA/cm(2), showing a large Jsc enhancement percentage of ∼22.2%. As a result, the strongly improved power conversion efficiency (PCE) of 6.28% is obtained compared to that (i.e., PCE = 5.12%) of the pristine OPVs. For the angle-dependent light-absorption characteristics, the plasmonic OPVs with ZnO(P380)/Active(P650) have a better absorption performance than that of the pristine OPVs at incident angles of 20-70°. For optical absorption characteristics and near-field intensity distributions of plasmonic OPVs, theoretical analyses are also performed by a rigorous coupled-wave analysis method, which gives a similar tendency with the experimentally measured data.

  18. The effect of recombination under short-circuit conditions on the determination of charge transport properties in nanostructured photoelectrodes.

    Science.gov (United States)

    Villanueva-Cab, J; Anta, J A; Oskam, G

    2016-01-28

    We report on the commonly unaccounted for process of recombination under short-circuit conditions in nanostructured photoelectrodes with special attention to the charge collection efficiency. It is observed that when recombination under short circuit conditions is significant, small perturbation methods overestimate the charge-collection efficiency, which is related to the inaccurate determination of the electron diffusion coefficient and diffusion length.

  19. Approaching Repetitive Short Circuit Tests on MW-Scale Power Modules by means of an Automatic Testing Setup

    DEFF Research Database (Denmark)

    Reigosa, Paula Diaz; Wang, Huai; Iannuzzo, Francesco

    2016-01-01

    An automatic testing system to perform repetitive short-circuit tests on megawatt-scale IGBT power modules is pre-sented and described in this paper, pointing out the advantages and features of such testing approach. The developed system is based on a non-destructive short-circuit tester, which has...

  20. Several problems of algorithmization in integrated computation programs on third generation computers for short circuit currents in complex power networks

    Energy Technology Data Exchange (ETDEWEB)

    Krylov, V.A.; Pisarenko, V.P.

    1982-01-01

    Methods of modeling complex power networks with short circuits in the networks are described. The methods are implemented in integrated computation programs for short circuit currents and equivalents in electrical networks with a large number of branch points (up to 1000) on a computer with a limited on line memory capacity (M equals 4030 for the computer).

  1. Measurements of impedances for determinating the minimum short-circuit current in main systems 500 V of underground mining establishments

    Energy Technology Data Exchange (ETDEWEB)

    Rittinghaus, D

    1981-09-01

    The complex short-circuit impedances of energized low-voltage main systems were measured with a double-bridge in underground mining operation. The magnitude of the short-circuit currents depends on these impedances. Customary calculations of such currents depend on empirical approximations. To verify the accuracy of these approximations, the measured impedances of 61 nodes in three different main systems were compared with the results of the calculations. The comparison made between the short-circuit currents determined by measurable quantities and the values calculated according to VDE 0118 shows that the stipulated coefficients for calculating the minimum short-circuit currents lie very far on the safe side. An amendment for calculating the short-circuit in accordance with VDE 0118 is therefore suggested.

  2. Short-circuit protection of LLC resonant converter using voltages across resonant tank elements

    Directory of Open Access Journals (Sweden)

    Denys Igorovych Zaikin

    2015-06-01

    Full Text Available This paper describes two methods for the short-circuit protection of the LLC resonant converter. One of them uses the voltage across the capacitor and the other uses the voltage across the inductor of the resonant tank. These voltages can be processed (integrated or differentiated to recover the resonant tank current. The two circuits illustrated in the described methods make it possible to develop a robust LLC converter design and to avoid using lossy current measurement elements, such as a shunt resistor or current transformer. The methods also allow measuring resonant tank current without breaking high-current paths and connecting the measuring circuit in parallel with the inductor or capacitor of the resonant tank. Practical implementations of these indirect current measurements have been experimentally tested for the short-circuit protection of the 1600 W LLC converter.

  3. Model-based evaluation of the short-circuited tripolar cuff configuration.

    Science.gov (United States)

    Andreasen, Lotte N S; Struijk, Johannes J

    2006-05-01

    Recordings of neural information for use as feedback in functional electrical stimulation are often contaminated with interfering signals from muscles and from stimulus pulses. The cuff electrode used for the neural recording can be optimized to improve the S/I ratio. In this work, we evaluate a model of both the nerve signal and the interfering signals recorded by a cuff, and subsequently use this model to study the signal to interference ratio of different cuff designs and to evaluate a recently introduced short-circuited tripolar cuff configuration. The results of the model showed good agreement with results from measurements in rabbits and confirmed the superior performance of the short-circuited tripolar configuration as compared with the traditionally used tripolar configuration.

  4. Control of internal and external short circuits in lithium batteries using a composite thermal switch

    Science.gov (United States)

    Mcdonald, Robert C.; Pickett, Jerome; Goebel, Franz

    1991-01-01

    A composite material has been developed, consisting of a blend of metal and fluorocarbon particles, which behaves as an electronic conductor at room temperature and which abruptly becomes an insulator at a predetermined temperature. This switching behavior results from the difference in thermal expansion coefficients between the conductive and non-conductive portions of the composite. This material was applied as a thin film between the carbon cathode in Li/SOCl2 cells, and the metallic cathode current collector. Using test articles incorporating this feature it was shown that lithium cells externally heated or internally heated during a short circuit lost rate capability and the ability to overheat well below the melting point of lithium (180 C). Thus, during an internal or external cell short circuit, the potential for thermal runaway involving reactions of molten lithium is avoided.

  5. Unstable behaviour of normally-off GaN E-HEMT under short-circuit

    Science.gov (United States)

    Martínez, P. J.; Maset, E.; Sanchis-Kilders, E.; Esteve, V.; Jordán, J.; Bta Ejea, J.; Ferreres, A.

    2018-04-01

    The short-circuit capability of power switching devices plays an important role in fault detection and the protection of power circuits. In this work, an experimental study on the short-circuit (SC) capability of commercial 600 V Gallium Nitride enhancement-mode high-electron-mobility transistors (E-HEMT) is presented. A different failure mechanism has been identified for commercial p-doped GaN gate (p-GaN) HEMT and metal-insulator-semiconductor (MIS) HEMT. In addition to the well known thermal breakdown, a premature breakdown is shown on both GaN HEMTs, triggered by hot electron trapping at the surface, which demonstrates that current commercial GaN HEMTs has requirements for improving their SC ruggedness.

  6. Asymmetrical short circuits in medium-voltage networks with grounded neutral through resistance

    Energy Technology Data Exchange (ETDEWEB)

    Tanasescu, M.; Maries, H.

    1981-01-01

    This article introduces the concepts of ''damage to ground'' and ''current to ground indicator'', which characterize the efficiency of the operating mode of the neutral. The values of these two indicators are assigned by directive (eletric power plan design instruction PE109/1980) and must be provided when selecting the parameters of compensating devices installed in the neutral. Possible aymmetrical short circuits in medium-voltage networks with neutral ground are examined. Formulas are derived for determining the short-circuiting currents and undamaged phase voltages in order to determine the damage to ground indicator and ground current indicator; an example of a calculation is given.

  7. Short Circuit Ratio analysis of multi-infeed HVDC system with a VSC-HVDC link

    DEFF Research Database (Denmark)

    Liu, Yan; Chen, Zhe

    2011-01-01

    As an important indicator of system stability, Short Circuit Ratio (SCR) is commonly used in power system analysis. For systems include HVDC link connection, the Effective SCR (ESCR) is mostly applied to indicate the strength of HVDC infeed bus. The contribution of VSC-HVDC link to multi......-infeed HVDC system stability has been analyzed a lot but the study on ESCR of this kind of system is still insufficient. This paper presents a calculation method for ESCR of the hybrid multi infeed HVDC system based on a simple two-infeed HVDC system model. The equivalent circuit of this system under short...... circuit situation is firstly obtained based on the model. Then its Thevenin equivalent circuit is derived and system ESCR can be calculated. At last, simulation study verified that the calculated ESCR value under different cases can indicate the change of system stability....

  8. Influence of wavelength on transient short-circuit current in polycrystalline silicon solar cells

    International Nuclear Information System (INIS)

    Ba, B.; Kane, M.

    1993-10-01

    The influence of the wavelength of a monochromatic illumination on transient short-circuit current in an n/p polycrystalline silicon part solar cell junction is investigated. A wavelength dependence in the initial part of the current decay is observed in the case of cells with moderate grain boundary effects. This influence is attenuated in polycrystalline cells with strong grain boundary activity. (author). 10 refs, 6 figs

  9. On Demand Internal Short Circuit Device Enables Verification of Safer, Higher Performing Battery Designs

    Energy Technology Data Exchange (ETDEWEB)

    Darcy, Eric; Keyser, Matthew

    2017-05-15

    The Internal Short Circuit (ISC) device enables critical battery safety verification. With the aluminum interstitial heat sink between the cells, normal trigger cells cannot be driven into thermal runaway without excessive temperature bias of adjacent cells. With an implantable, on-demand ISC device, thermal runaway tests show that the conductive heat sinks protected adjacent cells from propagation. High heat dissipation and structural support of Al heat sinks show high promise for safer, higher performing batteries.

  10. Increased short circuit current in an azafullerene-based organic solar cell.

    Science.gov (United States)

    Cambarau, Werther; Fritze, Urs F; Viterisi, Aurélien; Palomares, Emilio; von Delius, Max

    2015-01-21

    We report the synthesis of a solution-processable, dodecyloxyphenyl-substituted azafullerene monoadduct (DPC59N) and its application as electron acceptor in bulk heterojunction organic solar cells (BHJ-OSCs). Due to its relatively strong absorption of visible light, DPC59N outperforms PC60BM in respect to short circuit current (JSC) and external quantum efficiency (EQE) in blends with donor P3HT.

  11. An Empirical Model for Estimating the Probability of Electrical Short Circuits from Tin Whiskers. Part 2

    Science.gov (United States)

    Courey, Karim; Wright, Clara; Asfour, Shihab; Onar, Arzu; Bayliss, Jon; Ludwig, Larry

    2009-01-01

    In this experiment, an empirical model to quantify the probability of occurrence of an electrical short circuit from tin whiskers as a function of voltage was developed. This empirical model can be used to improve existing risk simulation models. FIB and TEM images of a tin whisker confirm the rare polycrystalline structure on one of the three whiskers studied. FIB cross-section of the card guides verified that the tin finish was bright tin.

  12. Apparatus including a plurality of spaced transformers for locating short circuits in cables

    Science.gov (United States)

    Cason, R. L.; Mcstay, J. J. (Inventor)

    1978-01-01

    A cable fault locator is described for sensing faults such as short circuits in power cables. The apparatus includes a plurality of current transformers strategically located along a cable. Trigger circuits are connected to each of the current transformers for placing a resistor in series with a resistive element responsive to an abnormally high current flowing through that portion of the cable. By measuring the voltage drop across the resistive element, the location of the fault can be determined.

  13. An Investigation of Short Circuits in All-solution Processed and All-organic Solar Cells

    OpenAIRE

    Johansson, Jim

    2015-01-01

    Organic solar cells have shown great promise of becoming a cheaper alternative to inorganic solar cells. Additionally, they can also be made semitransparent. To avoid using expensive indium tin oxide electrodes in organic solar cells the electrodes can be made from conductive polymer, poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS). However, these so-called PEDOT-PEDOT solar cells are prone to short-circuiting. The work behind this thesis thus aimed to find the cause of the...

  14. Modeling and Fault Diagnosis of Interturn Short Circuit for Five-Phase Permanent Magnet Synchronous Motor

    Directory of Open Access Journals (Sweden)

    Jian-wei Yang

    2015-01-01

    Full Text Available Taking advantage of the high reliability, multiphase permanent magnet synchronous motors (PMSMs, such as five-phase PMSM and six-phase PMSM, are widely used in fault-tolerant control applications. And one of the important fault-tolerant control problems is fault diagnosis. In most existing literatures, the fault diagnosis problem focuses on the three-phase PMSM. In this paper, compared to the most existing fault diagnosis approaches, a fault diagnosis method for Interturn short circuit (ITSC fault of five-phase PMSM based on the trust region algorithm is presented. This paper has two contributions. (1 Analyzing the physical parameters of the motor, such as resistances and inductances, a novel mathematic model for ITSC fault of five-phase PMSM is established. (2 Introducing an object function related to the Interturn short circuit ratio, the fault parameters identification problem is reformulated as the extreme seeking problem. A trust region algorithm based parameter estimation method is proposed for tracking the actual Interturn short circuit ratio. The simulation and experimental results have validated the effectiveness of the proposed parameter estimation method.

  15. Load Flow and Short Circuit Analysis of the Class III Power System of HANARO

    Energy Technology Data Exchange (ETDEWEB)

    Kim, H. K.; Jung, H. S

    2005-12-15

    The planning, design, and operation of electric power system require engineering studies to assist in the evaluation of the system performance, reliability, safety and economics. The Class III power of HANARO supplies power for not only HANARO but also RIPF and IMEF. The starting current of most ac motors is five to ten times normal full load current. The loads of the Class III power are connected in consecutive orders at an interval for 10 seconds to avoid excessive voltage drop. This technical report deals with the load flow study and motor starting study for the Class III power of HANARO using ETAP(Electrical Transient Analyzer Program) to verify the capacity of the diesel generator. Short-circuit studies are done to determine the magnitude of the prospective currents flowing throughout the power system at various time intervals after a fault occurs. Short-circuit studies can be performed at the planning stage in order to help finalize the system layout, determine voltage levels, and size cables, transformers, and conductors. From this study, we verify the short circuit current capacity of air circuit breaker(ACB) and automatic transfer switch(ATS) of the Class III power.

  16. Conditions of the existence of 'short circuit' effect for plasma in a conducting cylinder

    International Nuclear Information System (INIS)

    Zhilinskij, A.P.; Kuteev, B.V.

    1975-01-01

    It has been experimentally established that in a cylindrical container with conducting side and end walls, the phenomenon of short circuit (the Symon effect) is not always realized. The short circuiting of plane end and of side surfaces causes an acceleration of a plasma decay only during the initial stage in a comparatively short time. Characteristic lifetimes during the late stage remain unchanged in this case. In conditions of a stable plasma they correspond to classical values of the plasma decay constant at the ambipolar diffusion of charged particles along and across force lines of a magnetic field. A fundamental change in the nature of the diffusion and a decrease of the plasma lifetime almost by two orders are realized in an instrument in which an end conducting wall for plasma in created with a short cylinder at the end of a solenoid in a sharply nonuniform magnetic field. The data obtained testify to the fact that the short circuit effect takes place in conditions when on boundaries of plasma the possibility of simultaneous flowing of unipolar electron flows along and of ion flows across a magnetic field is assured. The results of the experiments are compared with a theory

  17. Investigation on a short circuit of large-area OLED lighting panels

    International Nuclear Information System (INIS)

    Park, J W; Kim, T W; Park, J B

    2013-01-01

    A short circuit often arises from large-area organic light-emitting device (OLED) lighting panels due to particles (i.e. dust, organic or metal debris) or the spike-like surface of the indium–tin–oxide (ITO) anode. On the emergence of a short circuit, an instant current crowding occurs, thereby reducing substantially the resistance of the panels and causing a failure of a dimming control. In this paper, we investigate the effect of the surface morphology of ITO on the resistance and dimmability of the panels. We have demonstrated that the peak-to-valley roughness of ITO should be much less than 20 nm or the resistance of the panels should be much higher than 1 MΩ in order to avoid an unwanted short-circuit phenomenon and thus achieve the high-yield fabrication of OLED lighting panels. It is also addressed that much care is taken to ensure a dimming control of OLED lighting panels with a larger active area because the resistance of those panels varies depending more sensitively on the surface roughness of ITO. (paper)

  18. Enhanced photocurrent in engineered bacteriorhodopsin monolayer.

    Science.gov (United States)

    Patil, Amol V; Premaruban, Thenhuan; Berthoumieu, Olivia; Watts, Anthony; Davis, Jason J

    2012-01-12

    The integration of the transmembrane protein bacteriorhodopsin (BR) with man-made electrode surfaces has attracted a great deal of interest for some two decades or more and holds significant promise from the perspective of derived photoresponse or energy capture interfaces. Here we demonstrate that a novel and strategically engineered cysteine site (M163C) can be used to intimately and effectively couple delipidated BR to supporting metallic electrode surfaces. By virtue of the combined effects of the greater surface molecular density afforded by delipidation, and the vicinity of the electrostatic changes associated with proton pumping to the transducing metallic continuum, the resulting films generate a considerably greater photocurrent density on wavelength-selective illumination than previously achievable with monolayers of BR. Given the uniquely photoresponsive, wavelength-selective, and photostable characteristics of this protein, the work has implications for utilization in solar energy capture and photodetector devices.

  19. Short-Circuit Characterization of 10 kV 10A 4H-SiC MOSFET

    DEFF Research Database (Denmark)

    Eni, Emanuel-Petre; Beczkowski, Szymon; Munk-Nielsen, Stig

    2016-01-01

    The short-circuit capability of a power device is highly relevant for converter design and fault protection. In this paper a 10kV 10A 4H-SiC MOSFET is characterized and its short circuit withstand capability is studied and analyzed at 6 kV DC-link voltage. The test setup for this study is also...... introduced as its design, especially the inductance in the switching loop, can affect the experimental results. The study aims to present insights specific to the device which are different from that of silicon (Si) based devices. During the short-circuit operation, MOSFET saturation current, ID...

  20. Hybrid solar cells with outstanding short-circuit currents based on a room temperature soft-chemical strategy: the case of P3HT:Ag2S.

    Science.gov (United States)

    Lei, Yan; Jia, Huimin; He, Weiwei; Zhang, Yange; Mi, Liwei; Hou, Hongwei; Zhu, Guangshan; Zheng, Zhi

    2012-10-24

    P3HT:Ag(2)S hybrid solar cells with broad absorption from the UV to NIR band were directly fabricated on ITO glass by using a room temperature, low energy consumption, and low-cost soft-chemical strategy. The resulting Ag(2)S nanosheet arrays facilitate the construction of a perfect percolation structure with organic P3HT to form ordered bulk heterojunctions (BHJ); without interface modification, the assembled P3HT:Ag(2)S device exhibits outstanding short-circuit current densities (J(sc)) around 20 mA cm(-2). At the current stage, the optimized device exhibited a power conversion efficiency of 2.04%.

  1. Correction: The effect of recombination under short-circuit conditions on the determination of charge transport properties in nanostructured photoelectrodes.

    Science.gov (United States)

    Villanueva-Cab, J; Anta, J A; Oskam, G

    2016-05-28

    Correction for 'The effect of recombination under short-circuit conditions on the determination of charge transport properties in nanostructured photoelectrodes' by J. Villanueva-Cab et al., Phys. Chem. Chem. Phys., 2016, 18, 2303-2308.

  2. Maximizing the short circuit current of organic solar cells by partial decoupling of electrical and optical properties

    Science.gov (United States)

    Qarony, Wayesh; Hossain, Mohammad I.; Jovanov, Vladislav; Knipp, Dietmar; Tsang, Yuen Hong

    2018-03-01

    The partial decoupling of electronic and optical properties of organic solar cells allows for realizing solar cells with increased short circuit current and energy conversion efficiency. The proposed device consists of an organic solar cell conformally prepared on the surface of an array of single and double textured pyramids. The device geometry allows for increasing the optical thickness of the organic solar cell, while the electrical thickness is equal to the nominal thickness of the solar cell. By increasing the optical thickness of the solar cell, the short circuit current is distinctly increased. The quantum efficiency and short circuit current are determined using finite-difference time-domain simulations of the 3D solar cell structure. The influence of different solar cell designs on the quantum efficiency and short circuit current is discussed and optimal device dimensions are proposed.

  3. Reducing the Risk of Damage to Power Transformers of 110 kV and Above Accompanying Internal Short Circuits

    Energy Technology Data Exchange (ETDEWEB)

    L’vova, M. M. [JSC “R& D Center at Federal Grid Company of the Unified Power System” (Russian Federation); L’vov, S. Yu. [Presselektro LLC (Russian Federation); Komarov, V. B. [IPCE RAS (Russian Federation); Lyut’ko, E. O. [JSC “R& D Center at Federal Grid Company of the Unified Power System” (Russian Federation); Vdoviko, V. P. [EMA Ltd. (Russian Federation); Demchenko, V. V. [JSC “Boguchanskaya HPP” (Russian Federation); Belyaev, S. G. [PKF Konif Ltd. (Russian Federation); Savel’ev, V. A. [Ivanovo State Power University (Russian Federation); L’vov, M. Yu., E-mail: timashova@nte-power.ru; L’vov, Yu. N. [JSC “R& D Center at Federal Grid Company of the Unified Power System” (Russian Federation)

    2015-03-15

    Methods of increasing the operating reliability of power transformers, autotransformers and shunting reactors in order to reduce the risk of damage, which accompany internal short circuits and equipment fires and explosions, are considered.

  4. Fullerene solubility-current density relationship in polymer solar cells

    International Nuclear Information System (INIS)

    Renz, Joachim A.; Gobsch, Gerhard; Hoppe, Harald; Troshin, Pavel A.; Razumov, V.F.

    2008-01-01

    During the last decade polymer solar cells have undergone a steady increase in overall device efficiency. To date, essential efficiency improvements of polymer-fullerene solar cells require the development of new materials. Whilst most research efforts aim at an improved or spectrally extended absorption of the donor polymer, not so much attention has been paid to the fullerene properties themselves. We have investigated a number of structurally related fullerenes, in order to study the relationship between chemical structure and resulting polymer-fullerene bulk heterojunction photovoltaic properties. Our study reveals a clear connection between the fullerene solubility as material property on one hand and the solar cells short circuit photocurrent on the other hand. The tendency of the less soluble fullerene derivates to aggregate was accounted for smaller current densities in the respective solar cells. Once a minimum solubility of approx. 25 mg/ml in chlorobenzene was overcome by the fullerene derivative, the short circuit current density reached a plateau, of about 8-10 mA/cm 2 . Thus the solubility of the fullerene derivative directly influences the blend morphology and displays an important parameter for efficient polymer-fullerene bulk heterojunction solar cell operation. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (Abstract Copyright [2008], Wiley Periodicals, Inc.)

  5. Laser induced photocurrent and photovoltage transient measurements of dye-sensitized solar cells based on TiO_2 nanosheets and TiO_2 nanoparticles

    International Nuclear Information System (INIS)

    Ghaithan, Hamid M.; Qaid, Saif M.H.; Hezam, Mahmoud; Labis, Joselito P.; Alduraibi, Mohammad; Bedja, Idriss M.; Aldwayyan, Abdullah S.

    2016-01-01

    Dye-sensitized solar cells (DSSCs) based on TiO_2 nanoparticles and TiO_2 nanosheets with exposed {001} facets are investigated using laser-induced photovoltage and photocurrent transient decay (LIPVCD) measurements. We adopted a simplified version of LIPVCD technique, in which a single illumination light source and a laboratory oscilloscope could be conveniently used for the measurements. Although the {001} surface of TiO_2 nanosheets allowed a noticeably slower recombination with the electrolyte, this was counterpoised by a slower electron transport probably due to its planar morphology, resulting in a shorter diffusion length in TiO_2 nanosheets. The nanosheet morphology also resulted in less surface area and therefore reduced short circuit current density in the fabricated devices. Our work highlights the fact that the morphological parameters of TiO_2 nanosheets finally resulting after electrode film deposition is of no less importance than the reported efficient dye adsorption and slow electron recombination at the surface of individual nanosheets.

  6. Determination of Carrier Lifetimes in Organic-Inorganic Hybrid Solar Cells Based on Sb2S3 by Using the Time-Resolved Photocurrent

    Science.gov (United States)

    Jo, Hyun-Jun; Mun, Young Hee; Kim, Jong Su; Kim, Seung Hyun; Lee, Sang-Ju; Sung, Shi-Joon; Kim, Dae-Hwan

    2018-03-01

    This paper presents organic-inorganic hybrid solar cells (SCs) based on ZnO/Sb2S3/P3HT heterojunctions. The ZnO and the Sb2S3 layers were grown using atomic layer deposition (ALD). Although four cells were fabricated on one substrate by using the same process, their open-circuit voltages ( V OC ) and short-circuit current densities ( J SC ) were different. The SC with a high V OC has a low J SC . The causes of the changes in the V OC and the JSC were investigated by using photoluminescence (PL) spectroscopy and optically-biased time-resolved photocurrent (TRPC) measurements. The PL results at 300 K showed that the emission positions of the Sb2S3 layers in all cells were similar at approximately 1.71 eV. The carrier lifetime of the SCs was calculated from the TRPC results. The lifetime of cell 4 with the highest J SC decreased drastically with increasing intensity of the continuous-wave optical bias beam. Therefore, the defect states in the ZnO layer contribute to the J SC , but degrade the V OC .

  7. A survey of SiC power MOSFETs short-circuit robustness and failure mode analysis

    DEFF Research Database (Denmark)

    Ceccarelli, L.; Reigosa, P. D.; Iannuzzo, F.

    2017-01-01

    The aim of this paper is to provide an extensive overview about the state-of-art commercially available SiC power MOSFET, focusing on their short-circuit ruggedness. A detailed literature investigation has been carried out, in order to collect and understand the latest research contribution within...... this topic and create a survey of the present scenario of SiC MOSFETs reliability evaluation and failure mode analysis, pointing out the evolution and improvements as well as the future challenges in this promising device technology....

  8. A Nanostructured Composites Thermal Switch Controls Internal and External Short Circuit in Lithium Ion Batteries

    Science.gov (United States)

    McDonald, Robert C.; VanBlarcom, Shelly L.; Kwasnik, Katherine E.

    2013-01-01

    A document discusses a thin layer of composite material, made from nano scale particles of nickel and Teflon, placed within a battery cell as a layer within the anode and/or the cathode. There it conducts electrons at room temperature, then switches to an insulator at an elevated temperature to prevent thermal runaway caused by internal short circuits. The material layer controls excess currents from metal-to-metal or metal-to-carbon shorts that might result from cell crush or a manufacturing defect

  9. Device for testing continuity and/or short circuits in a cable

    Science.gov (United States)

    Hayhurst, Arthur R. (Inventor)

    1995-01-01

    A device for testing current paths is attachable to a conductor. The device automatically checks the current paths of the conductor for continuity of a center conductor, continuity of a shield and a short circuit between the shield and the center conductor. The device includes a pair of connectors and a circuit to provide for testing of the conductive paths of the cable. The pair of connectors electrically connects the conductive paths of a cable to be tested with the circuit paths of the circuit. The circuit paths in the circuit include indicators to simultaneously indicate the results of the testing.

  10. Development of processing procedures for advanced silicon solar cells. [antireflection coatings and short circuit currents

    Science.gov (United States)

    Scott-Monck, J. A.; Stella, P. M.; Avery, J. E.

    1975-01-01

    Ten ohm-cm silicon solar cells, 0.2 mm thick, were produced with short circuit current efficiencies up to thirteen percent and using a combination of recent technical advances. The cells were fabricated in conventional and wraparound contact configurations. Improvement in cell collection efficiency from both the short and long wavelengths region of the solar spectrum was obtained by coupling a shallow junction and an optically transparent antireflection coating with back surface field technology. Both boron diffusion and aluminum alloying techniques were evaluated for forming back surface field cells. The latter method is less complicated and is compatible with wraparound cell processing.

  11. The effect of different solar simulators on the measurement of short-circuit current temperature coefficients

    Science.gov (United States)

    Curtis, H. B.; Hart, R. E., Jr.

    1982-01-01

    Gallium arsenide solar cells are considered for several high temperature missions in space. Both near-Sun and concentrator missions could involve cell temperatures on the order of 200 C. Performance measurements of cells at elevated temperatures are usually made using simulated sunlight and a matched reference cell. Due to the change in bandgap with increasing temperature at portions of the spectrum where considerable simulated irradiance is present, there are significant differences in measured short circuit current at elevated temperatures among different simulators. To illustrate this, both experimental and theoretical data are presented for gallium arsenide cells.

  12. Errors in short circuit measurements due to spectral mismatch between sunlight and solar simulators

    Science.gov (United States)

    Curtis, H. B.

    1976-01-01

    Errors in short circuit current measurement were calculated for a variety of spectral mismatch conditions. The differences in spectral irradiance between terrestrial sunlight and three types of solar simulator were studied, as well as the differences in spectral response between three types of reference solar cells and various test cells. The simulators considered were a short arc xenon lamp AMO sunlight simulator, an ordinary quartz halogen lamp, and an ELH-type quartz halogen lamp. Three types of solar cells studied were a silicon cell, a cadmium sulfide cell and a gallium arsenide cell.

  13. Variations in the electrical short-circuit current decay for recombination lifetime and velocity measurements

    Science.gov (United States)

    Jung, Tae-Won; Lindholm, Fredrik A.; Neugroschel, Arnost

    1987-01-01

    An improved measurement system for electrical short-circuit current decay is presented that extends applicability of the method to silicon solar cells having an effective lifetime as low as 1 microsec. The system uses metal/oxide/semiconductor transistors as voltage-controlled switches. Advances in theory developed here increase precision and sensitivity in the determination of the minority-carrier recombination lifetime and recombination velocity. A variation of the method, which exploits measurements made on related back-surface field and back-ohmic contact devices, further improves precision and sensitivity. The improvements are illustrated by application to 15 different silicon solar cells.

  14. Short circuit detection in the winding and operation of superconducting magnets

    International Nuclear Information System (INIS)

    Walstrom, P.L.

    1982-01-01

    Three categories of shorts will be discussed: (1) shorts to the metallic bobbin or other structural elements, (2) shorts between turns caused by instrumentation wires that are deliberately connected to a turn at the end (e.g., voltage taps) and that short out to another turn but are not completely severed in the process, and (3) short circuits between turns caused by direct contact due to insulation failure by chips of metal bridging turns and by instrumentation wires that bridge turns but are severed in the process of shorting

  15. Short-circuit testing of monofilar Bi-2212 coils connected in series and in parallel

    International Nuclear Information System (INIS)

    Polasek, A; Dias, R; Serra, E T; Filho, O O; Niedu, D

    2010-01-01

    Superconducting Fault Current Limiters (SCFCL's) are one of the most promising technologies for fault current limitation. In the present work, resistive SCFCL components based on Bi-2212 monofilar coils are subjected to short-circuit testing. These SCFCL components can be easily connected in series and/or in parallel by using joints and clamps. This allows a considerable flexibility to developing larger SCFCL devices, since the configuration and size of the whole device can be easily adapted to the operational conditions. The single components presented critical current (Ic) values of 240-260 A, at 77 K. Short-circuits during 40-120 ms were applied. A single component can withstand a voltage drop of 126-252 V (0.3-0.6 V/cm). Components connected in series withstand higher voltage levels, whereas parallel connection allows higher rated currents during normal operation, but the limited current is also higher. Prospective currents as high as 10-40 kA (peak value) were limited to 3-9 kA (peak value) in the first half cycle.

  16. Methods for stable recording of short-circuit current in a Na+-transporting epithelium.

    Science.gov (United States)

    Gondzik, Veronika; Awayda, Mouhamed S

    2011-07-01

    Epithelial Na(+) transport as measured by a variety of techniques, including the short-circuit current technique, has been described to exhibit a "rundown" phenomenon. This phenomenon manifests as time-dependent decrease of current and resistance and precludes the ability to carry out prolonged experiments aimed at examining the regulation of this transport. We developed methods for prolonged stable recordings of epithelial Na(+) transport using modifications of the short-circuit current technique and commercial Ussing-type chambers. We utilize the polarized MDCK cell line expressing the epithelial Na(+) channel (ENaC) to describe these methods. Briefly, existing commercial chambers were modified to allow continuous flow of Ringer solution and precise control of such flow. Chamber manifolds and associated plumbing were modified to allow precise temperature clamp preventing temperature oscillations. Recording electrodes were modified to eliminate the use of KCl and prevent membrane depolarization from KCl leakage. Solutions utilized standard bicarbonate-based buffers, but all gasses were prehydrated to clamp buffer osmolarity. We demonstrate that these modifications result in measurements of current and resistance that are stable for at least 2 h. We further demonstrate that drifts in osmolarity similar to those obtained before prior to our modifications can lead to a decrease of current and resistance similar to those attributed to rundown.

  17. An Investigation of the Electrical Short Circuit Characteristics of Tin Whiskers

    Science.gov (United States)

    Courey, Karim J.

    2008-01-01

    Existing risk simulations make the assumption that when a free tin whisker has bridged two adjacent exposed electrical conductors, the result is an electrical short circuit. This conservative assumption is made because shorting is a random event that has a currently unknown probability associated with it. Due to contact resistance electrical shorts may not occur at lower voltage levels. In this experiment, we study the effect of varying voltage on the breakdown of the contact resistance which leads to a short circuit. From this data we can estimate the probability of an electrical short, as a function of voltage, given that a free tin whisker has bridged two adjacent exposed electrical conductors. Also, three tin whiskers grown from the same Space Shuttle Orbiter card guide used in the aforementioned experiment were cross-sectioned and studied using a focused ion beam (FIB). The rare polycrystalline structure seen in the FIB cross section was confirmed using transmission electron microscopy (TEM). The FIB was also used to cross section two card guides to facilitate the measurement of the grain size to determine that the tin plating on the card guides had a bright finish.

  18. Adrenomedullin increases the short-circuit current in the mouse seminal vesicle: actions on chloride secretion.

    Science.gov (United States)

    Liao, S B; Cheung, K H; O, W S; Tang, Fai

    2014-08-01

    Adrenomedullin (ADM) may regulate seminal vesicle fluid secretion, and this may affect sperm quality. In this study, we investigated the effect of ADM on chloride secretion in the mouse seminal vesicle. The presence of ADM in mouse seminal vesicle was confirmed using immunostaining, and the molecular species was determined using gel filtration chromatography coupled with enzyme-linked assay for ADM. The effects of ADM on chloride secretion were studied by short-circuit current technique in a whole-mount preparation of mouse seminal vesicle in an Ussing chamber. The effects of specific ADM and calcitonin gene-related peptide (CGRP) receptor antagonists were investigated. Whether the ADM effect depended on the cAMP- and/or calcium-activated chloride channel was also studied using specific chloride channel blockers. The results showed that ADM was present in seminal vesicle epithelial cells. The major molecular species was precursor in the mouse seminal vesicle. ADM increased short-circuit current through the calcium-activated chloride channel in mouse seminal vesicle, and CGRP receptor was involved. We conclude that ADM may regulate chloride and fluid secretion from the seminal vesicle, which may affect the composition of the seminal plasma bathing the sperm and, hence, fertility. © 2014 by the Society for the Study of Reproduction, Inc.

  19. Spectral analysis to detection of short circuit fault of solar photovoltaic modules in strings

    International Nuclear Information System (INIS)

    Sevilla-Camacho, P.Y.; Robles-Ocampo, J.B.; Zuñiga-Reyes, Marco A.

    2017-01-01

    This research work presents a method to detect the number of short circuit faulted solar photovoltaic modules in strings of a photovoltaic system by taking into account speed, safety, and non-use of sensors and specialized and expensive equipment. The method consists on apply the spectral analysis and statistical techniques to the alternating current output voltage of a string and detect the number of failed modules through the changes in the amplitude of the component frequency of 12 kHz. For that, the analyzed string is disconnected of the array; and a small pulsed voltage signal of frequency of 12 kHz introduces him under dark condition and controlled temperature. Previous to the analysis, the signal is analogic filtered in order to reduce the direct current signal component. The spectral analysis technique used is the Fast Fourier Transform. The obtained experimental results were validated through simulation of the alternating current equivalent circuit of a solar cell. In all experimental and simulated test, the method allowed to identify correctly the number of photovoltaic modules with short circuit in the analyzed string. (author)

  20. Small-Molecule Solar Cells with Simultaneously Enhanced Short-Circuit Current and Fill Factor to Achieve 11% Efficiency.

    Science.gov (United States)

    Nian, Li; Gao, Ke; Jiang, Yufeng; Rong, Qikun; Hu, Xiaowen; Yuan, Dong; Liu, Feng; Peng, Xiaobin; Russell, Thomas P; Zhou, Guofu

    2017-08-01

    High-efficiency small-molecule-based organic photovoltaics (SM-OPVs) using two electron donors (p-DTS(FBTTh 2 ) 2 and ZnP) with distinctively different absorption and structural features are reported. Such a combination works well and synergically improves device short-circuit current density (J sc ) to 17.99 mA cm -2 and fill factor (FF) to 77.19%, yielding a milestone efficiency of 11%. To the best of our knowledge, this is the highest power conversion efficiency reported for SM-OPVs to date and the first time to combine high J sc over 17 mA cm -2 and high FF over 77% into one SM-OPV. The strategy of using multicomponent materials, with a selecting role of balancing varied electronic and structural necessities can be an important route to further developing higher performance devices. This development is important, which broadens the dimension and versatility of existing materials without much chemistry input. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. An alternative explanation for the occurrence of short circuit current increases in the small intestine following challenge by bacterial enterotoxins.

    Science.gov (United States)

    Lucas, M L

    2013-10-01

    Secretory diarrhoeal disease due to enterotoxins is thought to arise from the enhancement to pathologically high rates of normally occurring chloride ion and therefore fluid secretion from enterocytes. In support of this concept, many enterotoxins increase intestinal short-circuit current, regarded now as faithfully reflecting the increased chloride ion secretion. Contradicting this assumption, STa reduces absorption but does not cause secretion in vivo although short-circuit current is increased in vitro. There is therefore a mismatch between an assumed enterocyte mediated secretory event that should but does not cause net fluid secretion and an undoubtedly increased short-circuit current. It is proposed here that short-circuit current increases are not themselves secretory events but result from interrupted fluid absorption. A noteworthy feature of compounds that inhibit the increase in short-circuit current is that the majority are vasoactive, neuroactive or both. In general, vasodilator substances increase current. An alternative hypothesis for the origin of short-circuit current increases is that these result from reflex induction of electrogenic fluid absorption. This reflex enhances a compensatory response that is also present at a cellular level. An intestinal reflex is therefore proposed by which decreases in interstitial and intravascular volume or pressure within the intestine initiate an electrogenic fluid absorption mechanism that compensates for the loss of electrically neutral fluid absorption. This hypothesis would explain the apparently complex pharmacology of short-circuit current increases since many depressor substances have receptors in common with enterocytes and enteric nerves. The proposed alternative view of the origin of short-circuit current increases assumes that these do not represent chloride secretion from the enterocytes. This view may therefore aid the successful development of anti-diarrhoeal drugs to overcome a major cause of

  2. Three-Phase Short-Circuit Current Calculation of Power Systems with High Penetration of VSC-Based Renewable Energy

    Directory of Open Access Journals (Sweden)

    Niancheng Zhou

    2018-03-01

    Full Text Available Short-circuit current level of power grid will be increased with high penetration of VSC-based renewable energy, and a strong coupling between transient fault process and control strategy will change the fault features. The full current expression of VSC-based renewable energy was obtained according to transient characteristics of short-circuit current. Furtherly, by analyzing the closed-loop transfer function model of controller and current source characteristics presented in steady state during a fault, equivalent circuits of VSC-based renewable energy of fault transient state and steady state were proposed, respectively. Then the correctness of the theory was verified by experimental tests. In addition, for power grid with VSC-based renewable energy, superposition theorem was used to calculate AC component and DC component of short-circuit current, respectively, then the peak value of short-circuit current was evaluated effectively. The calculated results could be used for grid planning and design, short-circuit current management as well as adjustment of relay protection. Based on comparing calculation and simulation results of 6-node 500 kV Huainan power grid and 35-node 220 kV Huaisu power grid, the effectiveness of the proposed method was verified.

  3. Transient stability of DFIG wind turbines at an external short-circuit fault

    DEFF Research Database (Denmark)

    Sun, Tao; Chen, Zhe; Blaabjerg, Frede

    2005-01-01

    The fast development of wind power generation brings new requirements for wind turbine integration into the network. After clearance of an external short-circuit fault, gridconnected wind turbines should restore their normal operation without power loss caused by disconnections. This article...... are described in detail. The transient process of grid-connected wind turbines with DFIGs at an external shortcircuit fault is analysed, and in critical post-fault situations a measure is proposed for the voltage recovery of DFIG wind turbines after fault clearance. Simulation results demonstrate...... that in uncritical post-fault situations the control schemes are able to restore the wind turbine's normal operation without disconnections.lt is also proved that the proposed measure is effective in re-establishing the voltage at the wind turbine terminal in critical post-fault situations....

  4. Short-circuit current improvement in thin cells with a gridded back contact

    Science.gov (United States)

    Giuliano, M.; Wohlgemuth, J.

    1980-01-01

    The use of gridded back contact on thin silicon solar cells 50 micrometers was investigated. An unexpected increase in short circuit current of almost 10 percent was experienced for 2 cm x 2 cm cells. Control cells with the standard continuous contact metallization were fabricated at the same time as the gridded back cells with all processes identical up to the formation of the back contact. The gridded back contact pattern was delineated by evaporation of Ti-Pd over a photo-resist mask applied to the back of the wafer; the Ti-Pd film on the controls was applied in the standard fashion in a continuous layer over the back of the cell. The Ti-Pd contacts were similarly applied to the front of the wafer, and the grid pattern on both sides of the cell was electroplated with 8-10 micrometers of silver.

  5. Growth Mechanism Studies of ZnO Nanowires: Experimental Observations and Short-Circuit Diffusion Analysis.

    Science.gov (United States)

    Shih, Po-Hsun; Wu, Sheng Yun

    2017-07-21

    Plenty of studies have been performed to probe the diverse properties of ZnO nanowires, but only a few have focused on the physical properties of a single nanowire since analyzing the growth mechanism along a single nanowire is difficult. In this study, a single ZnO nanowire was synthesized using a Ti-assisted chemical vapor deposition (CVD) method to avoid the appearance of catalytic contamination. Two-dimensional energy dispersive spectroscopy (EDS) mapping with a diffusion model was used to obtain the diffusion length and the activation energy ratio. The ratio value is close to 0.3, revealing that the growth of ZnO nanowires was attributed to the short-circuit diffusion.

  6. On the short circuit resilience of organic solar cells: prediction and validation.

    Science.gov (United States)

    Oostra, A Jolt; Smits, Edsger C P; de Leeuw, Dago M; Blom, Paul W M; Michels, Jasper J

    2015-09-07

    The operational characteristics of organic solar cells manufactured with large area processing methods suffers from the occurrence of short-circuits due to defects in the photoactive thin film stack. In this work we study the effect of a shunt resistance on an organic solar cell and demonstrate that device performance is not affected negatively as long as the shunt resistance is higher than approximately 1000 Ohm. By studying charge transport across PSS-lithium fluoride/aluminum (LiF/Al) shunting junctions we show that this prerequisite is already met by applying a sufficiently thick (>1.5 nm) LiF layer. We demonstrate that this remarkable shunt-resilience stems from the formation of a significant charge transport barrier at the PSS-LiF/Al interface. We validate our predictions by fabricating devices with deliberately severed photoactive layers and find an excellent agreement between the calculated and experimental current-voltage characteristics.

  7. Short circuit current changes in electron irradiated GaAlAs/GaAs solar cells

    Science.gov (United States)

    Walker, G. H.; Conway, E. J.

    1978-01-01

    Heteroface p-GaAlAs/p-GaAs/n-GaAs solar cells with junction depths of 0.8, 1.5, and 4 microns were irradiated with 1 MeV electrons. The short-circuit current for the 4 micron junction depth cells is significantly reduced by the electron irradiation. Reduction of the junction depth to 1.5 microns improves the electron radiation resistance of the cells while further reduction of the junction depth to 0.8 microns improves the stability of the cells even more. Primary degradation is in the blue region of the spectrum. Considerable recovery of lost response is obtained by annealing the cells at 200 C. Computer modeling shows that the degradation is caused primarily by a reduction in the minority carrier diffusion length in the p-GaAs.

  8. Effect of Short-Circuit Pathways on Water Quality in Selected Confined Aquifers (Invited)

    Science.gov (United States)

    McMahon, P. B.

    2010-12-01

    Confined aquifers in the United States generally contain fewer anthropogenic contaminants than unconfined aquifers because confined aquifers often contain water recharged prior to substantial human development and redox conditions are more reducing, which favors degradation of common contaminants like nitrate and chlorinated solvents. Groundwater in a confined part of the High Plains aquifer near York, Nebraska had an adjusted radiocarbon age of about 2,000 years, and groundwater in a confined part of the Floridan aquifer near Tampa, Florida had apparent ages greater than 60 years on the basis of tritium measurements. Yet compounds introduced more recently into the environment (anthropogenic nitrate and volatile organic compounds) were detected in selected public-supply wells completed in both aquifers. Depth-dependent measurements of flow and chemistry in the pumping supply wells, groundwater age dating, numerical modeling of groundwater flow, and other monitoring data indicated that the confined aquifers sampled by the supply wells were connected to contaminated unconfined aquifers by short-circuit pathways. In the High Plains aquifer, the primary pathways appeared to be inactive irrigation wells screened in both the unconfined and confined aquifers. In the Floridan aquifer, the primary pathways were karst sinkholes and conduits. Heavy pumping in both confined systems exacerbated the problem by reducing the potentiometric surface and increasing groundwater velocities, thus enhancing downward gradients and reducing reaction times for processes like denitrification. From a broader perspective, several confined aquifers in the U.S. have experienced large declines in their potentiometric surfaces because of groundwater pumping and this could increase the potential for contamination in those aquifers, particularly where short-circuit pathways connect them to shallower, contaminated sources of water, such as was observed in York and Tampa.

  9. Effect of dislocations on the open-circuit voltage, short-circuit current and efficiency of heteroepitaxial indium phosphide solar cells

    Science.gov (United States)

    Jain, Raj K.; Flood, Dennis J.

    1990-01-01

    Excellent radiation resistance of indium phosphide solar cells makes them a promising candidate for space power applications, but the present high cost of starting substrates may inhibit their large scale use. Thin film indium phosphide cells grown on Si or GaAs substrates have exhibited low efficiencies, because of the generation and propagation of large number of dislocations. Dislocation densities were calculated and its influence on the open circuit voltage, short circuit current, and efficiency of heteroepitaxial indium phosphide cells was studied using the PC-1D. Dislocations act as predominant recombination centers and are required to be controlled by proper transition layers and improved growth techniques. It is shown that heteroepitaxial grown cells could achieve efficiencies in excess of 18 percent AMO by controlling the number of dislocations. The effect of emitter thickness and surface recombination velocity on the cell performance parameters vs. dislocation density is also studied.

  10. Utilisation of symmetrical components in a communication-based protection for loop MV feeders with variable short-circuit power

    DEFF Research Database (Denmark)

    Ciontea, Catalin-Iosif; Bak, Claus Leth; Blaabjerg, Frede

    2018-01-01

    -circuit power is presented. It relies on utilisation of symmetrical components of the short-circuit currents and on communication between the protection relays. The proposed method addresses the Single Phase to Ground (SPG) faults occurring in directly grounded distribution networks, with focus on closed......Variability of the available short-circuit power also implies variation of the fault level, which can potentially cause several protection problems in the electric networks. In this paper, a novel protection method that is insensitive to the fault level changes caused by variable short......-loop Medium Voltage (MV) feeders. Case studies are presented, which demonstrate that the proposed protection scheme is capable of effectively detecting the SPG faults in closed-loop feeders with variable short-circuit power....

  11. Implications of electronic short circuiting in plasma sprayed solid oxide fuel cells on electrode performance evaluation by electrochemical impedance spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    White, B.D. [Department of Mechanical Engineering, The University of British Columbia, 2054-6250 Applied Sciences Lane, Vancouver, British Columbia (Canada); Kesler, O. [Department of Mechanical and Industrial Engineering, University of Toronto, 5 King' s College Road, Toronto, Ontario (Canada)

    2008-02-15

    Electronic short circuiting of the electrolyte in a solid oxide fuel cell (SOFC) arising from flaws in the plasma spray fabrication process has been found to have a significant effect on the perceived performance of the electrodes, as evaluated by electrochemical impedance spectroscopy (EIS). The presence of a short circuit has been found to lead to the underestimation of the electrode polarization resistance (R{sub p}) and hence an overestimation of electrode performance. The effect is particularly noticeable when electrolyte resistance is relatively high, for example during low to intermediate temperature operation, leading to an obvious deviation from the expected Arrhenius-type temperature dependence of R{sub p}. A method is developed for determining the real electrode performance from measurements of various cell properties, and strategies for eliminating the occurrence of short circuiting in plasma sprayed cells are identified. (author)

  12. Implications of electronic short circuiting in plasma sprayed solid oxide fuel cells on electrode performance evaluation by electrochemical impedance spectroscopy

    Science.gov (United States)

    White, B. D.; Kesler, O.

    Electronic short circuiting of the electrolyte in a solid oxide fuel cell (SOFC) arising from flaws in the plasma spray fabrication process has been found to have a significant effect on the perceived performance of the electrodes, as evaluated by electrochemical impedance spectroscopy (EIS). The presence of a short circuit has been found to lead to the underestimation of the electrode polarization resistance (R p) and hence an overestimation of electrode performance. The effect is particularly noticeable when electrolyte resistance is relatively high, for example during low to intermediate temperature operation, leading to an obvious deviation from the expected Arrhenius-type temperature dependence of R p. A method is developed for determining the real electrode performance from measurements of various cell properties, and strategies for eliminating the occurrence of short circuiting in plasma sprayed cells are identified.

  13. Representative-Sandwich Model for Mechanical-Crush and Short-Circuit Simulation of Lithium-ion Batteries

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Chao; Santhanagopalan, Shriram; Sprague, Michael A.; Pesaran, Ahmad A.

    2015-07-28

    Lithium-ion batteries are currently the state-of-the-art power sources for a variety of applications, from consumer electronic devices to electric-drive vehicles (EDVs). Being an energized component, failure of the battery is an essential concern, which can result in rupture, smoke, fire, or venting. The failure of Lithium-ion batteries can be due to a number of external abusive conditions (impact/crush, overcharge, thermal ramp, etc.) or internal conditions (internal short circuits, excessive heating due to resistance build-up, etc.), of which the mechanical-abuse-induced short circuit is a very practical problem. In order to better understand the behavior of Lithium-ion batteries under mechanical abuse, a coupled modeling methodology encompassing the mechanical, thermal and electrical response has been developed for predicting short circuit under external crush.

  14. Effects of Armature Winding Segmentation with Multiple Converters on the Short Circuit Torque of 10-MW Superconducting Wind Turbine Generators

    DEFF Research Database (Denmark)

    Liu, Dong; Polinder, Henk; Abrahamsen, Asger Bech

    2017-01-01

    Superconducting synchronous generators (SCSGs) are drawing more attention in large direct-drive wind turbine applications. Despite low weight and compactness, the short circuit torque of an SCSG may be too high for wind turbine constructions due to a large magnetic air gap of an SCSG. This paper...... aims at assessing the effects of armature winding segmentation on reducing the short circuit torque of 10-MW SCSGs. A concept of armature winding segmentation with multiple power electronic converters is presented. Four SCSG designs using different topologies are examined. Results show that armature...... winding segmentation effectively reduce the short circuit torque in all the four SCSG designs when one segment is shorted at the terminal....

  15. Transient analysis of the output short-circuit fault of high power and high voltage DC power supply

    International Nuclear Information System (INIS)

    Yang Zhigang; Zhang Jian; Huang Yiyun; Hao Xu; Sun Haozhang; Guo Fei

    2014-01-01

    The transient conditions of output short-circuit fault of high voltage DC power supply was introduced, and the energy of power supply injecting into klystron during the protection process of three-electrode gas switch were analyzed and calculated in detail when klystron load happening electrode arc faults. The results of calculation and simulation are consistent with the results of the experiment. When the output short-circuit fault of high voltage power supply occurs, switch can be shut off in the microsecond, and the short circuit current can be controlled in 200 A. It has verified the rapidity and reliability of the three-electrode gas switch protection, and it has engineering application value. (authors)

  16. Increasing emitter efficiency in 3.3-kV enhanced trench IGBTs for higher short-circuit capability

    DEFF Research Database (Denmark)

    Reigosa, Paula Diaz; Iannuzzo, Francesco; Rahimo, Munaf

    2018-01-01

    In this paper, a 3.3-kV Enhanced Trench IGBT has been designed with a high emitter efficiency, for improving its short-circuit robustness. The carrier distribution profile has been shaped in a way that it is possible to increase the electric field at the surface of the IGBT, and thereby, counteract...... the Kirk Effect onset. This design approach is beneficial for mitigating high-frequency oscillations, typically observed in IGBTs under short-circuit conditions. The effectiveness of the proposed design rule is validated by means of mixed-mode device simulations. Then, two IGBTs have been fabricated...... with different emitter efficiencies and tested under short circuit, validating that the high-frequency oscillations can be mitigated, with higher emitter efficiency IGBT designs....

  17. Transient Analysis of Grid-Connected Wind Turbines with DFIG After an External Short-Circuit Fault

    DEFF Research Database (Denmark)

    Sun, Tao; Chen, Zhe; Blaabjerg, Frede

    2004-01-01

    The fast development of wind power generation brings new requirements for wind turbine integration to the network. After the clearance of an external short-circuit fault, the grid-connected wind turbine should restore its normal operation with minimized power losses. This paper concentrates...... on transient analysis of variable speed wind turbines with doubly fed induction generator (DFIG) after an external short-circuit fault. A simulation model of a MW-level variable speed wind turbine with DFIG developed in PSCAD/EMTDC is presented, and the control and protection schemes are described in detail....... After the clearance of an external short-circuit fault the control schemes manage to restore the wind turbine?s normal operation, and their performances are demonstrated by simulation results both during the fault and after the clearance of the fault....

  18. The Effect of Current-Limiting Reactors on the Tripping of Short Circuits in High-Voltage Electrical Equipment

    International Nuclear Information System (INIS)

    Volkov, M. S.; Gusev, Yu. P.; Monakov, Yu. V.; Cho, Gvan Chun

    2016-01-01

    The insertion of current-limiting reactors into electrical equipment operating at a voltage of 110 and 220 kV produces a change in the parameters of the transient recovery voltages at the contacts of the circuit breakers for disconnecting short circuits, which could be the reason for the increase in the duration of the short circuit, damage to the electrical equipment and losses in the power system. The results of mathematical modeling of the transients, caused by tripping of the short circuit in a reactive electric power transmission line are presented, and data are given on the negative effect of a current-limiting resistor on the rate of increase and peak value of the transient recovery voltages. Methods of ensuring the standard requirements imposed on the parameters of the transient recovery voltages when using current-limiting reactors in the high-voltage electrical equipment of power plants and substations are proposed and analyzed

  19. The short-circuit current of the ileum, but not the colon, is altered in the streptozotocin diabetic rat.

    Science.gov (United States)

    Forrest, Abigail; Makwana, Rajesh; Parsons, Mike

    2006-02-01

    Ion transport in control and streptozotocin-diabetic rat colon and ileum was studied using the Ussing chamber technique. No differences were observed between control and diabetic colonic mucosal short-circuit current under either basal or carbachol (100 nmol/L-1 micromol/L)-stimulated or prostaglandin E2 (100 nmol/L-1 micromol/L)-stimulated conditions. Similarly to colonic tissues, no differences in the short circuit current in either carbachol-stimulated or prostaglandin E2-stimulated tissues were observed between control and diabetic ileal mucosa. The basal diabetic ileal short circuit current (99.58 +/- 22.67 microA) was significantly greater than that of control ileal tissues (29.67 +/- 4.45 microA). This difference was abolished by the sodium-glucose-cotransporter inhibitor, phloridzin (50 micromol/L) (118.00 +/- 28.09 microA vs. 25.60 +/- 4.59 microA) and was also prevented by the replacement of glucose with mannitol in the buffer bathing the apical side of the tissue (control: 17.05 +/- 5.85 microA vs. 17.90 +/- 3.10 microA). Acetazolamide (450 micromol/L; a carbonic anhydrase inhibitor), amiloride, and bumetanide (100 micromol/L each; Na+-channel blockers), piroxicam (50 micromol/L; a COX1 cyclooxygenase inhibitor), and ouabain (1 mmol/L; a K+ transport inhibitor) had no effect on the basal short circuit current of either control or diabetic ileal tissues. This indicated that the alteration in the basal short circuit current of diabetic ileal tissues was due to a change in cellular glucose transport, whereas the evoked changes in short circuit current were unaffected by the diabetic state.

  20. Effect of the depth base along the vertical on the electrical parameters of a vertical parallel silicon solar cell in open and short circuit

    Science.gov (United States)

    Sahin, Gokhan; Kerimli, Genber

    2018-03-01

    This article presented a modeling study of effect of the depth base initiating on vertical parallel silicon solar cell's photovoltaic conversion efficiency. After the resolution of the continuity equation of excess minority carriers, we calculated the electrical parameters such as the photocurrent density, the photovoltage, series resistance and shunt resistances, diffusion capacitance, electric power, fill factor and the photovoltaic conversion efficiency. We determined the maximum electric power, the operating point of the solar cell and photovoltaic conversion efficiency according to the depth z in the base. We showed that the photocurrent density decreases with the depth z. The photovoltage decreased when the depth base increases. Series and shunt resistances were deduced from electrical model and were influenced and the applied the depth base. The capacity decreased with the depth z of the base. We had studied the influence of the variation of the depth z on the electrical parameters in the base.

  1. Transient analysis of unbalanced short circuits of the ERDA-NASA 100 kW wind turbine alternator

    Science.gov (United States)

    Hwang, H. H.; Gilbert, L. J.

    1976-01-01

    Unbalanced short-circuit faults on the alternator of the ERDA-NASA Mod-O100-kW experimental wind turbine are studied. For each case, complete solutions for armature, field, and damper-circuit currents; short-circuit torque; and open-phase voltage are derived directly by a mathematical analysis. Formulated results are tabulated. For the Mod-O wind turbine alternator, numerical calculations are given, and results are presented by graphs. Comparisons for significant points among the more important cases are summarized. For these cases the transients are found to be potentially severe. The effect of the alternator neutral-to-ground impedance is evaluated.

  2. Compact electro-thermal modeling of a SiC MOSFET power module under short-circuit conditions

    DEFF Research Database (Denmark)

    Ceccarelli, Lorenzo; Reigosa, Paula Diaz; Bahman, Amir Sajjad

    2017-01-01

    A novel physics-based, electro-thermal model which is capable of estimating accurately the short-circuit behavior and thermal instabilities of silicon carbide MOSFET multi-chip power modules is proposed in this paper. The model has been implemented in PSpice and describes the internal structure.......2 kV breakdown voltage and about 300 A rated current. The short-circuit behavior of the module is investigated experimentally through a non-destructive test setup and the model is validated. The estimation of overcurrent and temperature distribution among the chips can provide useful information...

  3. Experimental study on short-circuit characteristics of the new protection circuit of insulated gate bipolar transistor

    International Nuclear Information System (INIS)

    Ji, In-Hwan; Choi, Young-Hwan; Ha, Min-Woo; Han, Min-Koo; Choi, Yearn-Ik

    2006-01-01

    A new protection circuit employing the collector to emitter voltage (V CE ) sensing scheme for short-circuit withstanding capability of the insulated gate bipolar transistor (IGBT) is proposed and verified by experimental results. Because the current path between the gate and collector can be successfully eliminated in the proposed protection circuit, the power consumption can be reduced and the gate input impedance can be increased. Previous study is limited to dc characteristics. However, experimental results show that the proposed protection circuit successfully reduces the over-current of main IGBT by 80.4% under the short-circuit condition

  4. Technical Study on Improvement of Endurance Capability of Limit Short-circuit Current of Charge Control SMART Meter

    Science.gov (United States)

    Li, W. W.; Du, Z. Z.; Yuan, R. m.; Xiong, D. Z.; Shi, E. W.; Lu, G. N.; Dai, Z. Y.; Chen, X. Q.; Jiang, Z. Y.; Lv, Y. G.

    2017-10-01

    Smart meter represents the development direction of energy-saving smart grid in the future. The load switch, one of the core parts of smart meter, should be of high reliability, safety and endurance capability of limit short-circuit current. For this reason, this paper discusses the quick simulation of relationship between attraction and counterforce of load switch without iteration, establishes dual response surface model of attraction and counterforce and optimizes the design scheme of load switch for charge control smart meter, thus increasing electromagnetic attraction and spring counterforce. In this way, this paper puts forward a method to improve the withstand capacity of limit short-circuit current.

  5. Application of photoconductivity decay and photocurrent generation ...

    Indian Academy of Sciences (India)

    Unknown

    ... (PCD) and photocurrent generation (PCG) methods are simple and low cost methods of ... flection based detection of the change in photoconductivity .... 2.2 Photoconductivity decay behaviour .... con solar cell of known spectral response. 4.

  6. Short circuit experiment on an FCL coil wound with YBCO tape with a high-resistance stabilizing layer

    Energy Technology Data Exchange (ETDEWEB)

    Yazawa, T; Iijima, Y; Saito, T [Toshiba Corporation, Fujikura Ltd (Japan); Amemiya, N [Toshiba Corporation, Yokohama National University (Japan); Shiohara, Y [Toshiba Corporation, ISTEC SRL (Japan); Koyanagi, K; Ono, M; Urata, M, E-mail: takashi.yazawa@toshiba.co.jp

    2008-02-15

    One of the programs in the Ministry of Economy, Trade and Industry regarding R and D for developing YBCO conductors is to evaluate the suitability of the conductors in several applications. This paper focuses on one of the expected power applications, namely, a fault current limiter (FCL). YBCO tape conductors with ion beam assisted deposition (IBAD) substrates are used in this work. In order to increase the resistivity of the conductor, which is preferable for FCL applications, the thickness of a protective layer made of silver was decreased as much as possible. After obtaining the required current limiting performance in short sample experiments, a model coil was developed aiming at 6.6 kV-class FCLs. Short circuit experiments were conducted with a short-circuit generator. The coil successfully suppressed a short-circuit current of over 1.4 kA to about 500 A under an applied voltage of 3.8 kV, which is the nominal phase-to-ground voltage. The coil also suppressed a short-circuit current of 17 kA down to 700 A. The experimental results are as expected and show promise toward FCL applications.

  7. Other origins for the fluorescence modulation of single dye molecules in open-circuit and short-circuit devices.

    Science.gov (United States)

    Teguh, Jefri S; Kurniawan, Michael; Wu, Xiangyang; Sum, Tze Chien; Yeow, Edwin K L

    2013-01-07

    Fluorescence intensity modulation of single Atto647N dye molecules in a short-circuit device and a defective device, caused by damaging an open-circuit device, is due to a variation in the excitation light focus as a result of the formation of an alternating electric current.

  8. Short circuit experiment on an FCL coil wound with YBCO tape with a high-resistance stabilizing layer

    International Nuclear Information System (INIS)

    Yazawa, T; Iijima, Y; Saito, T; Amemiya, N; Shiohara, Y; Koyanagi, K; Ono, M; Urata, M

    2008-01-01

    One of the programs in the Ministry of Economy, Trade and Industry regarding R and D for developing YBCO conductors is to evaluate the suitability of the conductors in several applications. This paper focuses on one of the expected power applications, namely, a fault current limiter (FCL). YBCO tape conductors with ion beam assisted deposition (IBAD) substrates are used in this work. In order to increase the resistivity of the conductor, which is preferable for FCL applications, the thickness of a protective layer made of silver was decreased as much as possible. After obtaining the required current limiting performance in short sample experiments, a model coil was developed aiming at 6.6 kV-class FCLs. Short circuit experiments were conducted with a short-circuit generator. The coil successfully suppressed a short-circuit current of over 1.4 kA to about 500 A under an applied voltage of 3.8 kV, which is the nominal phase-to-ground voltage. The coil also suppressed a short-circuit current of 17 kA down to 700 A. The experimental results are as expected and show promise toward FCL applications

  9. Short-Circuit Fault Detection and Classification Using Empirical Wavelet Transform and Local Energy for Electric Transmission Line.

    Science.gov (United States)

    Huang, Nantian; Qi, Jiajin; Li, Fuqing; Yang, Dongfeng; Cai, Guowei; Huang, Guilin; Zheng, Jian; Li, Zhenxin

    2017-09-16

    In order to improve the classification accuracy of recognizing short-circuit faults in electric transmission lines, a novel detection and diagnosis method based on empirical wavelet transform (EWT) and local energy (LE) is proposed. First, EWT is used to deal with the original short-circuit fault signals from photoelectric voltage transformers, before the amplitude modulated-frequency modulated (AM-FM) mode with a compactly supported Fourier spectrum is extracted. Subsequently, the fault occurrence time is detected according to the modulus maxima of intrinsic mode function (IMF₂) from three-phase voltage signals processed by EWT. After this process, the feature vectors are constructed by calculating the LE of the fundamental frequency based on the three-phase voltage signals of one period after the fault occurred. Finally, the classifier based on support vector machine (SVM) which was constructed with the LE feature vectors is used to classify 10 types of short-circuit fault signals. Compared with complementary ensemble empirical mode decomposition with adaptive noise (CEEMDAN) and improved CEEMDAN methods, the new method using EWT has a better ability to present the frequency in time. The difference in the characteristics of the energy distribution in the time domain between different types of short-circuit faults can be presented by the feature vectors of LE. Together, simulation and real signals experiment demonstrate the validity and effectiveness of the new approach.

  10. Microscale failure mechanisms leading to internal short circuit in Li-ion batteries under complex loading scenarios

    NARCIS (Netherlands)

    Sahraei, E.; Bosco, E.; Dixon, B.; Lai, B.

    2016-01-01

    One of the least understood mechanisms of Li-ion batteries is the development of internal short circuits under mechanical loads. In this study, a micro mechanical model is developed and subjected to various loading scenarios to understand the sequence of failure in the multi-layer, multi-material

  11. Developing an Empirical Model for Estimating the Probability of Electrical Short Circuits from Tin Whiskers. Part 2

    Science.gov (United States)

    Courey, Karim J.; Asfour, Shihab S.; Onar, Arzu; Bayliss, Jon A.; Ludwig, Larry L.; Wright, Maria C.

    2009-01-01

    To comply with lead-free legislation, many manufacturers have converted from tin-lead to pure tin finishes of electronic components. However, pure tin finishes have a greater propensity to grow tin whiskers than tin-lead finishes. Since tin whiskers present an electrical short circuit hazard in electronic components, simulations have been developed to quantify the risk of said short circuits occurring. Existing risk simulations make the assumption that when a free tin whisker has bridged two adjacent exposed electrical conductors, the result is an electrical short circuit. This conservative assumption is made because shorting is a random event that had an unknown probability associated with it. Note however that due to contact resistance electrical shorts may not occur at lower voltage levels. In our first article we developed an empirical probability model for tin whisker shorting. In this paper, we develop a more comprehensive empirical model using a refined experiment with a larger sample size, in which we studied the effect of varying voltage on the breakdown of the contact resistance which leads to a short circuit. From the resulting data we estimated the probability distribution of an electrical short, as a function of voltage. In addition, the unexpected polycrystalline structure seen in the focused ion beam (FIB) cross section in the first experiment was confirmed in this experiment using transmission electron microscopy (TEM). The FIB was also used to cross section two card guides to facilitate the measurement of the grain size of each card guide's tin plating to determine its finish.

  12. Fast and Accurate Icepak-PSpice Co-Simulation of IGBTs under Short-Circuit with an Advanced PSpice Model

    DEFF Research Database (Denmark)

    Wu, Rui; Iannuzzo, Francesco; Wang, Huai

    2014-01-01

    A basic problem in the IGBT short-circuit failure mechanism study is to obtain realistic temperature distribution inside the chip, which demands accurate electrical simulation to obtain power loss distribution as well as detailed IGBT geometry and material information. This paper describes an unp...

  13. Failure Analysis of Short-Circuited Lithium-Ion Battery with Nickel-Manganese-Cobalt/Graphite Electrode.

    Science.gov (United States)

    Lee, Seung-Mi; Kim, Jea-Yeon; Byeon, Jai-Won

    2018-09-01

    Accidental failures and explosions of lithium-ion batteries have been reported in recent years. To determine the root causes and mechanisms of these failures from the perspective of material degradation, failure analysis was conducted for an intentionally shorted lithium-ion battery. The battery was subjected to electrical overcharging and mechanical pressing to simulate internal short-circuiting. After in situ measurement of the temperature increase during the short-circuiting of the electrodes, the disassembled battery components (i.e., the anode, cathode, and separator) were analyzed by scanning electron microscopy and energy-dispersive X-ray spectroscopy. Regardless of the simulated short-circuit method (mechanical or electrical), damage was observed in the shorted batteries. Numerous small cracks and chemical reaction products were observed on the electrode surface, along with pore shielding on the separator. The event of short-circuiting increased the surface temperature of the battery to approximately 90 °C, which prompted the deterioration and decomposition of the electrolyte, thus affecting the overall battery performance; this was attributed to the decomposition of the lithium salt at 60 °C. The gas generation due to the breakdown of the electrolyte causes pressure accumulation inside the cell; therefore, the electrolyte leaks.

  14. EQUATIONS OF ELECTRIC MOTOR POWER SUPPLY UNIT DISSYMMETRY UNDER PHASE-TO-PHASE SHORT-CIRCUIT FAULT

    Directory of Open Access Journals (Sweden)

    V.Y. Tchaban

    2013-10-01

    Full Text Available In the paper, a formula is introduced to calculate electric motor supply unit voltage under feeding by a common transformer in the condition of a phase-to-phase short-circuit. The formula is used in every time step of electromechanical state equations integration.

  15. An iterative approach for symmetrical and asymmetrical Short-circuit calculations with converter-based connected renewable energy sources

    DEFF Research Database (Denmark)

    Göksu, Ömer; Teodorescu, Remus; Bak-Jensen, Birgitte

    2012-01-01

    As more renewable energy sources, especially more wind turbines are installed in the power system, analysis of the power system with the renewable energy sources becomes more important. Short-circuit calculation is a well known fault analysis method which is widely used for early stage analysis...

  16. Mode of the short circuit in the direct current electric traction network with different feed charts of fyder area

    Directory of Open Access Journals (Sweden)

    P. Mihalichenko

    2012-12-01

    Full Text Available In the article the results of mathematical design of the system of electric traction of direct current are represented in the mode of short circuit and different feed charts of fyder area: two-sided; one-sided. Comparison of transitional electric sizes which characterize electromagnetic processes during these malfunctions is analysed and executed.

  17. Detection of Internal Short Circuit in Lithium Ion Battery Using Model-Based Switching Model Method

    Directory of Open Access Journals (Sweden)

    Minhwan Seo

    2017-01-01

    Full Text Available Early detection of an internal short circuit (ISCr in a Li-ion battery can prevent it from undergoing thermal runaway, and thereby ensure battery safety. In this paper, a model-based switching model method (SMM is proposed to detect the ISCr in the Li-ion battery. The SMM updates the model of the Li-ion battery with ISCr to improve the accuracy of ISCr resistance R I S C f estimates. The open circuit voltage (OCV and the state of charge (SOC are estimated by applying the equivalent circuit model, and by using the recursive least squares algorithm and the relation between OCV and SOC. As a fault index, the R I S C f is estimated from the estimated OCVs and SOCs to detect the ISCr, and used to update the model; this process yields accurate estimates of OCV and R I S C f . Then the next R I S C f is estimated and used to update the model iteratively. Simulation data from a MATLAB/Simulink model and experimental data verify that this algorithm shows high accuracy of R I S C f estimates to detect the ISCr, thereby helping the battery management system to fulfill early detection of the ISCr.

  18. Optical effects of shadow masks on short circuit current of organic photovoltaic devices.

    Science.gov (United States)

    Lin, Chi-Feng; Lin, Bing-Hong; Liu, Shun-Wei; Hsu, Wei-Feng; Zhang, Mi; Chiu, Tien-Lung; Wei, Mau-Kuo; Lee, Jiun-Haw

    2012-03-21

    In this paper, we have employed different shadow masks attached on top of organic photovoltaic (OPV) devices to study the optical effects of the former on the short circuit current (J(SC)). To rule out possible lateral electrical conduction and simplify the optical effects inside the device, a small-molecular heterojunction OPV device with a clear donor/acceptor interface was employed with a hole extraction layer exhibiting high resistance intentionally. Careful calibration with a shadow mask was employed. By attaching two layers of opaque masks in combination with a suitable holder design to shield the light from the edges and backside, the value of J(SC) approached that of the dark current, even under 1-sun radiation. With different illumination areas, we found that the photons illuminating the non-active region of the device contributed to 40% of the J(SC) by optical effect within the width of about 1 mm around the active region. When illuminating the non-active area with 12 mm to the active area, a 5.6 times improvement in the J(SC) was observed when the incident angle was 75°. With the introduction of a microstructured film onto the OPV device and an increase in the reflection from the non-active region, a 15% enhancement of the J(SC) compared to the control device was achieved.

  19. Solar Cell Short Circuit Current Errors and Uncertainties During High Altitude Calibrations

    Science.gov (United States)

    Snyder, David D.

    2012-01-01

    High altitude balloon based facilities can make solar cell calibration measurements above 99.5% of the atmosphere to use for adjusting laboratory solar simulators. While close to on-orbit illumination, the small attenuation to the spectra may result in under measurements of solar cell parameters. Variations of stratospheric weather, may produce flight-to-flight measurement variations. To support the NSCAP effort, this work quantifies some of the effects on solar cell short circuit current (Isc) measurements on triple junction sub-cells. This work looks at several types of high altitude methods, direct high altitude meas urements near 120 kft, and lower stratospheric Langley plots from aircraft. It also looks at Langley extrapolation from altitudes above most of the ozone, for potential small balloon payloads. A convolution of the sub-cell spectral response with the standard solar spectrum modified by several absorption processes is used to determine the relative change from AMO, lscllsc(AMO). Rayleigh scattering, molecular scatterin g from uniformly mixed gases, Ozone, and water vapor, are included in this analysis. A range of atmosph eric pressures are examined, from 0. 05 to 0.25 Atm to cover the range of atmospheric altitudes where solar cell calibrations a reperformed. Generally these errors and uncertainties are less than 0.2%

  20. Investigation of Permanent Magnet Demagnetization in Synchronous Machines during Multiple Short-Circuit Fault Conditions

    Directory of Open Access Journals (Sweden)

    Stefan Sjökvist

    2017-10-01

    Full Text Available Faults in electrical machines can vary in severity and affect different parts of the machine. This study focuses on various kinds of short-circuits on the terminal side of a generic 20 kW surface mounted permanent magnet synchronous generator and how successive faults affect the performance of the machine. The study was conducted with the commercially available finite element method software COMSOL Multiphysics ® , and two time-dependent models for demagnetization of permanent magnets were compared, one using only internal models and the other using a proprietary external function. The study is simulation based and the two models were compared to a previously experimentally verified stationary model. Results showed that the power output decreased by more than 30% after five successive faults. In addition, the no-load voltage had become unsymmetrical, which was explained by the uneven demagnetization of the permanent magnets. The permanent magnet with the lowest reduction in average remanence was decreased by 0.8%, while the highest average reduction was 23.8% in another permanent magnet. The internal simulation model was about four times faster than the external model, but slightly overestimated the demagnetization.

  1. Investigation and Classification of Short-Circuit Failure Modes Based on Three-Dimensional Safe Operating Area for High-Power IGBT Modules

    DEFF Research Database (Denmark)

    Chen, Yuxiang; Li, Wuhua; Iannuzzo, Francesco

    2018-01-01

    is implemented to motivate advanced contributions in future dependence research of device short-circuit failure modes on temperature. Consequently, a comprehensive and thoughtful review of where the development of short-circuit failure mode research works of IGBT stands and is heading is provided....

  2. THE RATE OF CURRENT CHANGE DURING A SHORT CIRCUIT IN THE POWER CIRCUITS OF THE ELECTRIC ROLLING STOCK WITH REGARD TO EDDY CURRENTS

    Directory of Open Access Journals (Sweden)

    L. V. Dubinets

    2010-04-01

    Full Text Available In the article the issue of influence of vortical currents on rate of change of short circuit current is considered, a mathematical model for the calculation of short circuit currents in the traction mode in the power circuits of DC electric rolling stock is presented, and the research results are given.

  3. The short-circuit test results of 6.9 kV/2.3 kV 400 kVA-class YBCO model transformer

    International Nuclear Information System (INIS)

    Tomioka, A.; Otonari, T.; Ogata, T.; Iwakuma, M.; Okamoto, H.; Hayashi, H.; Iijima, Y.; Saito, T.; Gosho, Y.; Tanabe, K.; Izumi, T.; Shiohara, Y.

    2011-01-01

    The 6.9 kV/2.3 kV 400 kVA-class single-phase YBCO model transformer with the YBCO tape with copper tape was manufactured for short-circuit current test. Short-circuit test was performed and the short-circuit current of primary winding was 346 A which was about six times larger than the rated current. The I-V characteristics of the winding did not change before and after the test. The transformer withstood short-circuit current. We are planning to turn the result into a consideration of a 66 kV/6.9 kV-20 MVA-class three-phase superconducting transformer. We are developing an elemental technology for 66 kV/6.9 kV 20 MVA-class power transformer with YBCO conductors. The protection of short-circuit technology is one of the elemental technologies for HTS transformer. Since short-circuit current is much higher than critical current of YBCO tape, there is a possibility that superconducting characteristics may be damaged during short-circuit period. We made a conductor to compose the YBCO tape with copper tape. We manufactured 6.9 kV/2.3 kV 400 kVA-class YBCO model transformer using this conductor and performed short-circuit current test. The short-circuit current of primary winding was 346 A which was about six times larger than the rated current. The I-V characteristics of the winding did not change before and after the test. We may consider this conductor withstands short-circuit current.

  4. Experimental investigation of internal short circuits in lithium-ion batteries

    Science.gov (United States)

    Poramapojana, Poowanart

    With outstanding performance of Lithium-ion batteries, they have been widely used in many applications. For hybrid electric vehicles and electric vehicles, customer concerns of battery safety have been raised as a number of car accidents were reported. To evaluate safety performance of these batteries, a nail penetration test is used to simulate and induce internal short circuits instantaneously. Efforts to explain failure mechanisms of the penetration using electrochemical-thermal coupled models have been proposed. However, there is no experimental validation because researchers lack of a diagnostic tool to acquire important cell characteristics at a shorting location, such as shorting current and temperature. In this present work, diagnostic nails have been developed to acquire nail center temperatures and shorting current flow through the nails during nail penetration tests. Two types of cylindrical wall structures are used to construct the nails: a double-layered stainless steel wall and a composite cylindrical wall. An inner hollow cylinder functions as a sensor holder where two wires and one thermocouple are installed. To study experimental reproducibility and repeatability of experimental results, two nail penetration tests are conducted using two diagnostic nails with the double-layered wall. Experimental data shows that the shorting resistance at the initial stage is a critical parameter to obtain repeatable results. The average shorting current for both tests is approximately 40 C-rate. The fluctuation of the shorting current is due to random sparks and fire caused loose contacts between the nail and the cell components. Moreover, comparative experimental results between the two wall structures reveal that the wall structure does not affect the cell characteristics and Ohmic heat generation of the nail. The wall structure effects to current measurements inside the nail. With the composite wall, the actual current redistribution into the inner wall is

  5. Interaction of ultrashort laser pulses and silicon solar cells under short circuit conditions

    Energy Technology Data Exchange (ETDEWEB)

    Mundus, M., E-mail: markus.mundus@ise.fraunhofer.de; Giesecke, J. A.; Fischer, P.; Hohl-Ebinger, J.; Warta, W. [Fraunhofer Institute for Solar Energy Systems (ISE), Heidenhofstraße 2, 79110 Freiburg (Germany)

    2015-02-28

    Ultrashort pulse lasers are promising tools for numerous measurement purposes. Among other benefits their high peak powers allow for efficient generation of wavelengths in broad spectral ranges and at spectral powers that are orders of magnitude higher than in conventional light sources. Very recently this has been exploited for the establishment of sophisticated measurement facilities for electrical characterization of photovoltaic (PV) devices. As the high peak powers of ultrashort pulses promote nonlinear optical effects they might also give rise to nonlinear interactions with the devices under test that possibly manipulate the measurement outcome. In this paper, we present a comprehensive theoretical and experimental study of the nonlinearities affecting short circuit current (I{sub SC}) measurements of silicon (Si) solar cells. We derive a set of coupled differential equations describing the radiation-device interaction and discuss the nonlinearities incorporated in those. By a semi-analytical approach introducing a quasi-steady-state approximation and integrating a Green's function we solve the system of equations and obtain simulated I{sub SC} values. We validate the theoretical model by I{sub SC} ratios obtained from a double ring resonator setup capable for reproducible generation of various ultrashort pulse trains. Finally, we apply the model to conduct the most prominent comparison of I{sub SC} generated by ultrashort pulses versus continuous illumination. We conclude by the important finding that the nonlinearities induced by ultrashort pulses are negligible for the most common I{sub SC} measurements. However, we also find that more specialized measurements (e.g., of concentrating PV or Si-multijunction devices as well as highly localized electrical characterizations) will be biased by two-photon-absorption distorting the I{sub SC} measurement.

  6. Vasotocin- and mesotocin-induced increases in short-circuit current across tree frog skin.

    Science.gov (United States)

    Takada, Makoto; Fujimaki-Aoba, Kayo; Hokari, Shigeru

    2011-02-01

    In adult amphibian skin, Na(+) crosses from outside to inside. This Na(+) transport can be measured as the amiloride-blockable short-circuit current (SCC) across the skin. We investigated the effects of arginine vasotocin (AVT) and mesotocin (MT), and those of antagonists of the vasopressin and oxytocin receptors, on the SCC across Hyla japonica skin. (1) Both AVT (100 pmol/L or more) and MT (1 nmol/L or more) increased the SCC. (2) The AVT- and MT-induced increases in SCC recovered with time (downregulation). (3) These AVT/MT-induced effects were blocked by application of OPC-31260 (vasopressin V(2)-receptor antagonist). (4) The OPC-31260 concentration needed to block the AVT-induced response was lower upon post-application (after application of agonist) than upon pre-application (before application of agonist), suggesting the number of receptors may have decreased after AVT application. (5) Upon repeated application of AVT (100 pmol/L), the induced SCC increase did not differ significantly between the 1st and 2nd applications. (6) The time to reach the half-maximum value of the AVT-induced or MT-induced increase in SCC was not significantly different between washout and post-application of OPC-31260, suggesting that post-application of OPC-31260 cleared AVT and MT from their receptors. The effects of AVT, MT, and their antagonists in H. japonica, which is adapted to a terrestrial habitat, are compared with our previously published data on Rana catesbeiana (=Lithobates catesbeianus), which is adapted to a semiaquatic habitat.

  7. cAMP Stimulates Transepithelial Short-Circuit Current and Fluid Transport Across Porcine Ciliary Epithelium.

    Science.gov (United States)

    Cheng, Angela King-Wah; Civan, Mortimer M; To, Chi-Ho; Do, Chi-Wai

    2016-12-01

    To investigate the effects of cAMP on transepithelial electrical parameters and fluid transport across porcine ciliary epithelium. Transepithelial electrical parameters were determined by mounting freshly isolated porcine ciliary epithelium in a modified Ussing chamber. Similarly, fluid movement across intact ciliary body was measured with a custom-made fluid flow chamber. Addition of 1, 10, and 100 μM 8-Br-cAMP (cAMP) to the aqueous side (nonpigmented ciliary epithelium, NPE) induced a sustained increase in short-circuit current (Isc). Addition of niflumic acid (NFA) to the aqueous surface effectively blocked the cAMP-induced Isc stimulation. The administration of cAMP to the stromal side (pigmented ciliary epithelium, PE) triggered a significant stimulation of Isc only at 100 μM. No additive effect was observed with bilateral application of cAMP. Likewise, forskolin caused a significant stimulation of Isc when applied to the aqueous side. Concomitantly, cAMP and forskolin increased fluid transport across porcine ciliary epithelium, and this stimulation was effectively inhibited by aqueous NFA. Depleting Cl- in the bathing solution abolished the baseline Isc and inhibited the subsequent stimulation by cAMP. Pretreatment with protein kinase A (PKA) blockers (H89/KT5720) significantly inhibited the cAMP- and forskolin-induced Isc responses. Our results suggest that cAMP triggers a sustained stimulation of Cl- and fluid transport across porcine ciliary epithelium; Cl- channels in the NPE cells are potentially a cellular site for this PKA-sensitive cAMP-mediated response.

  8. An Empirical Model for Estimating the Probability of Electrical Short Circuits from Tin Whiskers-Part I

    Science.gov (United States)

    Courey, Karim; Wright, Clara; Asfour, Shihab; Bayliss, Jon; Ludwig, Larry

    2008-01-01

    Existing risk simulations make the assumption that when a free tin whisker has bridged two adjacent exposed electrical conductors, the result is an electrical short circuit. This conservative assumption is made because shorting is a random event that has a currently unknown probability associated with it. Due to contact resistance, electrical shorts may not occur at lower voltage levels. In this experiment, we study the effect of varying voltage on the breakdown of the contact resistance which leads to a short circuit. From this data, we can estimate the probability of an electrical short, as a function of voltage, given that a free tin whisker has bridged two adjacent exposed electrical conductors. In addition, three tin whiskers grown from the same Space Shuttle Orbiter card guide used in the aforementioned experiment were cross sectioned and studied using a focused ion beam (FIB).

  9. Small-angle scattering theory revisited: Photocurrent and spatial localization

    DEFF Research Database (Denmark)

    Basse, N.P.; Zoletnik, S.; Michelsen, Poul

    2005-01-01

    In this paper theory on collective scattering measurements of electron density fluctuations in fusion plasmas is revisited. We present the first full derivation of the expression for the photocurrent beginning at the basic scattering concepts. Thereafter we derive detailed expressions for the auto......- and crosspower spectra obtained from measurements. These are discussed and simple simulations made to elucidate the physical meaning of the findings. In this context, the known methods of obtaining spatial localization are discussed and appraised. Where actual numbers are applied, we utilize quantities from two...

  10. Short-circuit tests of 1650 and 96 MVA transformers for 1300 MW french nuclear power plants

    International Nuclear Information System (INIS)

    Mailhot, M.

    1989-01-01

    Power evacuation and feeding of the auxiliaries directly from the 400 kV grid are sensitive points governing the security of 1300 MW PWR Nuclear Power Plants of the French Program. These two different functions are provided by two specific types of transformers. - Banks of 3 single-phase 550 MVA - 400 kV/20 kV transformers. - Three-phase 96 MVA - 400 kV / 3 x 6.8 kV transformers. These passive elements must have a never failing reliability and assure a continuous service in spite of electric, thermal and mechanical stresses that may occur during the lifetime of the power plant. Dielectric and thermal tests carried out in the manufacturers test floors insure these stresses withstand capabilities of transformers. In France, high short-circuit power for the 400 kV network added to often low impedance voltages for transformers impose on them very high stresses during short-circuits. Calculation and experimentation on scale or partial models are not sufficient to insure short-circuit currents withstand capabilities of transformers. The margin of uncertainty dependent on obligatory extrapolations for this kind of complex systems [steel, magnetic sheets, copper, oil, paper and transformerboard] can be reduced in a significant way only by real scale tests on prototypes. These tests that need both high power and voltage cannot be performed in manufacturers test floors. So, in France they are carried out at the EDF Les Renardieres Laboratory. Following paper deals with SHELL TYPE TRANSFORMERS which, particularly thanks to their interleaved rectangular windings display a great resistance to short-circuit stresses

  11. Cage-rotor induction motor inter-turn short circuit fault detection with and without saturation effect by MEC model.

    Science.gov (United States)

    Naderi, Peyman

    2016-09-01

    The inter-turn short fault for the Cage-Rotor-Induction-Machine (CRIM) is studied in this paper and its local saturation is taken into account. However, in order to observe the exact behavior of machine, the Magnetic-Equivalent-Circuit (MEC) and nonlinear B-H curve are proposed to provide an insight into the machine model and saturation effect respectively. The electrical machines are generally operated near to their saturation zone due to some design necessities. Hence, when the machine is exposed to a fault such as short circuit or eccentricities, it is operated within its saturation zone and thus, time and space harmonics are integrated and as a result, current and torque harmonics are generated which the phenomenon cannot be explored when saturation is dismissed. Nonetheless, inter-turn short circuit may lead to local saturation and this occurrence is studied in this paper using MEC model. In order to achieve the mentioned objectives, two and also four-pole machines are modeled as two samples and the machines performances are analyzed in healthy and faulty cases with and without saturation effect. A novel strategy is proposed to precisely detect inter-turn short circuit fault according to the stator׳s lines current signatures and the accuracy of the proposed method is verified by experimental results. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.

  12. Double-layer rotor magnetic shield performance analysis in high temperature superconducting synchronous generators under short circuit fault conditions

    Science.gov (United States)

    Hekmati, Arsalan; Aliahmadi, Mehdi

    2016-12-01

    High temperature superconducting, HTS, synchronous machines benefit from a rotor magnetic shield in order to protect superconducting coils against asynchronous magnetic fields. This magnetic shield, however, suffers from exerted Lorentz forces generated in light of induced eddy currents during transient conditions, e.g. stator windings short-circuit fault. In addition, to the exerted electromagnetic forces, eddy current losses and the associated effects on the cryogenic system are the other consequences of shielding HTS coils. This study aims at investigating the Rotor Magnetic Shield, RMS, performance in HTS synchronous generators under stator winding short-circuit fault conditions. The induced eddy currents in different circumferential positions of the rotor magnetic shield along with associated Joule heating losses would be studied using 2-D time-stepping Finite Element Analysis, FEA. The investigation of Lorentz forces exerted on the magnetic shield during transient conditions has also been performed in this paper. The obtained results show that double line-to-ground fault is of the most importance among different types of short-circuit faults. It was revealed that when it comes to the design of the rotor magnetic shields, in addition to the eddy current distribution and the associated ohmic losses, two phase-to-ground fault should be taken into account since the produced electromagnetic forces in the time of fault conditions are more severe during double line-to-ground fault.

  13. Detection Method for Soft Internal Short Circuit in Lithium-Ion Battery Pack by Extracting Open Circuit Voltage of Faulted Cell

    Directory of Open Access Journals (Sweden)

    Minhwan Seo

    2018-06-01

    Full Text Available Early detection of internal short circuit which is main cause of thermal runaway in a lithium-ion battery is necessary to ensure battery safety for users. As a promising fault index, internal short circuit resistance can directly represent degree of the fault because it describes self-discharge phenomenon caused by the internal short circuit clearly. However, when voltages of individual cells in a lithium-ion battery pack are not provided, the effect of internal short circuit in the battery pack is not readily observed in whole terminal voltage of the pack, leading to difficulty in estimating accurate internal short circuit resistance. In this paper, estimating the resistance with the whole terminal voltages and the load currents of the pack, a detection method for the soft internal short circuit in the pack is proposed. Open circuit voltage of a faulted cell in the pack is extracted to reflect the self-discharge phenomenon obviously; this process yields accurate estimates of the resistance. The proposed method is verified with various soft short conditions in both simulations and experiments. The error of estimated resistance does not exceed 31.2% in the experiment, thereby enabling the battery management system to detect the internal short circuit early.

  14. Effect of cAMP on short-circuit current in isolated human ciliary body.

    Science.gov (United States)

    Wu, Ren-yi; Ma, Ning; Hu, Qian-qian

    2013-07-01

    Cyclic adenosine monophosphate (cAMP) could activate chloride channels in bovine ciliary body and trigger an increase in the ionic current (short-circuit current, Isc) across the ciliary processes in pigs. The purpose of this study was to investigate how cAMP modulates Isc in isolated human ciliary processes and the possible involvement of chloride transport across the tissue in cAMP-induced Isc change. In an Ussing-type chamber system, the Isc changes induced by the cAMP analogue 8-bromo-cAMP and an adenylyl cyclase activator forskolin in isolated human ciliary processes were assessed. The involvement of Cl(-) component in the bath solution was investigated. The effect of Cl(-) channel (10 µmol/L niflumic acid and 1 mmol/L 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS)), K(+) channel (10 mmol/L tetraethylammonium chloride (TEA)), or Na(+) channel blockers (1 mmol/L amiloride) on 8-bromo-cAMP-induced Isc change was also studied. Dose-dependently, 8-bromo-cAMP (10 nmol/L-30 µmol/L) or forskolin (10 nmol/L-3 µmol/L) increased Isc across the ciliary processes with an increase in negative potential difference on the non-pigmented epithelium (NPE) side of the tissue. Isc increase induced by 8-bromo-cAMP was more pronounced when the drug was applied on the NPE side than on the pigmented epithelium side. When the tissue was bathed in low Cl(-) solutions, the Isc increase was significantly inhibited. Finally, niflumic acid and DIDS, but not TEA or amiloride, significantly prevented the Isc increase induced by 8-bromo-cAMP. cAMP stimulates stroma-to-aqueous anionic transport in isolated human ciliary processes. Chloride is likely to be among the ions, the transportation of which across the tissue is triggered by cAMP, suggesting the potential role of cAMP in the process of aqueous humor formation in human eyes.

  15. The dependence of the short circuit current with γ-radiation in CuGaSe2

    International Nuclear Information System (INIS)

    Gasimoglu, I.; Mamedova, I.A.; Bagirov, A.G.

    2005-01-01

    Full text: The A I B III C IV semiconducting compounds are of interest for semiconducting devising. In particular the presence of the birefringence makes the compounds as a perspective materials for using in nonlinear optical transformers. Besides, the complex generation-recombination processes in these compounds are due to the local states in the band gap, which is also due to the complex chemical structure of these compounds. In this report the results of the influence of γ-radiation on the short circuit current in CuGaSe 2 are presented. The Co 6 0 with the quantum energy of 1.25 MeV was a source of radiation. The resistance was 10 2 kΩ at 300 K. The In-Ga eutectic was used as a contact. The measurements have been carried out at 77 K. The electrometer B7-30 was used for the short circuit current measurements, sensitivity of which is 10 -15 A. The intensity of γ-rays was 20 R/s, durability of radiation was 15 min. The spectrometer SPM-2 was used as a source of radiation of monoxrmator light. The spectral dependence of short circuit current of non radiated CuGaSe 2 crystal has a maximum at λ=700 nm (0.77 eV) with the half width of 0.26 eV. The maximum of short circuit current is in good agreement with the value 1.8 eV at 300 K. That is why one can assume that observed peak in J sc ∼∼f(λ) dependence with the maximum at 1.77 eV is due to electronic transitions from the valence band to conduction band. After radiation of CuGaSe 2 crystal new maximum is observed in the spectral dependence of short circuit current at λ=770 nm (1.61 eV) at 77 K. Splitting between the peaks is 0.13 eV. The appearance of the second peak maybe is due to the formation of radiation defects of acceptor type, which are located for 0.13 eV above than the top of valence band. The peak at 1.59 eV, which is due the donor-acceptor recombination, is observed in photoluminescence spectra. It is assumed that, Se vacancy forms the donor levels, Cu vacancy -acceptor levels

  16. THE RELIABILITY OF DETERMINING THE SHORT CIRCUIT ZONE OF THE LINES OF 6–35 kV

    Directory of Open Access Journals (Sweden)

    F. А. Romaniuk

    2018-01-01

    Full Text Available A method of increasing the reliability of determining the zone of short-circuit at the current step protection of the lines of 6–35 kV with unilateral power, aimed at improvement of their technical perfection, is presented in the paper. Having taken the relative simpleness of the current protection into account the authors consider the unilateral remote method of accounting the parameters of the emergency mode and the type of fault to be the most suitable for the implementation of the algorithm of its functioning as compared with the existing methods of fault location. The major factors affecting the accuracy of determining the short circuit zone based on the remote method are noted. With the use of the method of computational experiment the influence of the load currents and contact resistances of various levels on the magnitude and character of changes of errors of determination of the calculated distance of the point of fault from the protection installation location taking into account the errors of measuring transformers. It is demonstrated that in many cases of arc short circuit in a loaded line in order to define the zone of short-circuit with fair accuracy correction of the estimated distance to the fault as calculated by the parameters of the damaged loop (loops is required. According to the results of numerical experiments corrective expressions on the basis of two relative asymmetry currents determined by the current values of the differences of the phase currents of the line for detecting a type of a short circuit have been obtained. The assessment of the efficiency of the proposed method has been performed. It is shown that the application of the proposed correction method makes it possible to increase the accuracy of fault zone detection. The dynamic properties of the proposed method applied to different modes of the line functioning have been studied. It is determined that in the worst case the definition of the fault zone for a

  17. Electromechanical stress in transformers caused by three-phase short-circuits; Estresse eletromecanico em transformadores causado por curtos-circuitos trifasicos

    Energy Technology Data Exchange (ETDEWEB)

    Rosentino, A.J.J. Pereira; Delaiba, A.C.; Saraiva, E.; Oliveira, J.C. de; Lynce, M. [Universidade Federal de Uberlandia (UFU), MG (Brazil). Fac. de Engenharia Eletrica], Emails: arnaldoufu@gmail.com, delaiba@ufu.br, elise.saraiva@yahoo.com.br, jcoliveira@ufu.br, lynce@ufu.br; Bronzeado, H. de S. [Companhia Hidro Eletrica do Sao Francisco (CHESF), Recife, PE (Brazil)], Emails: herivelto.bronzeado@gmail.com, hebron@chesf.gov.br

    2009-07-01

    One of the reasons for internal failures of transformers is the weakness of the isolation of its conductors/coils due to vibrations caused by electromechanics forces produced by the high short-circuit currents. In this context, this paper presents a methodology to estimate the electromechanical stress in transformers caused by three-phase short circuits. Details of the characteristics of radial and axial forces that can occur in concentric windings of transformers, focusing mainly on the axial are presented. It is presented the preliminary description of techniques for diagnosis and monitoring of transformers in the face of mechanical stress caused by short circuit. This study considers the transformers core involved.

  18. Calculations of the displacement damage and short-circuit current degradation in proton irradiated (AlGa)As-GaAs solar cells

    Science.gov (United States)

    Yeh, C. S.; Li, S. S.; Loo, R. Y.

    1987-01-01

    A theoretical model for computing the displacement damage defect density and the short-circuit current (I sub sc) degradation in proton-irradiated (AlGa)As-GaAs p-n junction solar cells is presented. Assumptions were made with justification that the radiation induced displacement defects form an effective recombination center which controls the electron and hole lifetimes in the junction space charge region and in the n-GaAs active layer of the irradiated GaAs p-n junction cells. The degradation of I sub sc in the (AlGa)As layer was found to be negligible compared to the total degradation. In order to determine the I sub sc degradation, the displacement defect density, path length, range, reduced energy after penetrating a distance x, and the average number of displacements formed by one proton scattering event were first calculated. The I sub sc degradation was calculated by using the electron capture cross section in the p-diffused layer and the hole capture cross section in the n-base layer as well as the wavelength dependent absorption coefficients. Excellent agreement was found between the researchers calculated values and the measured I sub sc in the proton irradiated GaAs solar cells for proton energies of 100 KeV to 10 MeV and fluences from 10 to the 10th power p/square cm to 10 to the 12th power p/square cm.

  19. High performance of PbSe/PbS core/shell quantum dot heterojunction solar cells: short circuit current enhancement without the loss of open circuit voltage by shell thickness control.

    Science.gov (United States)

    Choi, Hyekyoung; Song, Jung Hoon; Jang, Jihoon; Mai, Xuan Dung; Kim, Sungwoo; Jeong, Sohee

    2015-11-07

    We fabricated heterojunction solar cells with PbSe/PbS core shell quantum dots and studied the precisely controlled PbS shell thickness dependency in terms of optical properties, electronic structure, and solar cell performances. When the PbS shell thickness increases, the short circuit current density (JSC) increases from 6.4 to 11.8 mA cm(-2) and the fill factor (FF) enhances from 30 to 49% while the open circuit voltage (VOC) remains unchanged at 0.46 V even with the decreased effective band gap. We found that the Fermi level and the valence band maximum level remain unchanged in both the PbSe core and PbSe/PbS core/shell with a less than 1 nm thick PbS shell as probed via ultraviolet photoelectron spectroscopy (UPS). The PbS shell reduces their surface trap density as confirmed by relative quantum yield measurements. Consequently, PbS shell formation on the PbSe core mitigates the trade-off relationship between the open circuit voltage and the short circuit current density. Finally, under the optimized conditions, the PbSe core with a 0.9 nm thick shell yielded a power conversion efficiency of 6.5% under AM 1.5.

  20. Evidence of Gate Voltage Oscillations during Short Circuit of Commercial 1.7 kV/ 1 kA IGBT Power Modules

    DEFF Research Database (Denmark)

    Reigosa, Paula Diaz; Wu, Rui; Iannuzzo, Francesco

    2015-01-01

    This paper analyzes the evidence of critical gate voltage oscillations in 1.7 kV/1 kA Insulated-Gate Bipolar Transistor (IGBT) power modules under short circuit conditions. A 6 kA/1.1 kV Non-Destructive Test (NDT) set up for repeatable short circuit tests has been built with a 40 nH stray inducta...

  1. Round busbar concept for 30 nH, 1.7 kV, 10 kA IGBT non-destructive short-circuit tester

    DEFF Research Database (Denmark)

    Smirnova, Liudmila; Pyrhönen, Juha; Iannuzzo, Francesco

    2014-01-01

    Design of a Non-Destructive Test (NDT) set-up for short-circuit tests of 1.7 kV, 1 kA IGBT modules is discussed in this paper. The test set-up allows achieving short-circuit current up to 10 kA. The important objective during the design of the test set-up is to minimize the parasitic inductance...

  2. Modeling photocurrent transients in organic solar cells

    International Nuclear Information System (INIS)

    Hwang, I; Greenham, N C

    2008-01-01

    We investigate the transient photocurrents of organic photovoltaic devices in response to a sharp turn-on of illumination, by numerical modeling of the drift-diffusion equations. We show that the photocurrent turn-on dynamics are determined not only by the transport dynamics of free charges, but also by the time required for the population of geminate charge pairs to reach its steady-state value. The dissociation probability of a geminate charge pair is found to be a key parameter in determining the device performance, not only by controlling the efficiency at low intensities, but also in determining the fate of charge pairs formed by bimolecular recombination at high intensities. Bimolecular recombination is shown to reduce the turn-on time at high intensities, since the typical distance traveled by a charge pair is reduced.

  3. Various mechanisms and clinical phenotypes in electrical short circuits of high-voltage devices: report of four cases and review of the literature.

    Science.gov (United States)

    Tsurugi, Takuo; Matsui, Shogo; Nakajima, Hiroshi; Nishii, Nobuhiro; Honda, Toshihiro; Kaneko, Yoshiaki

    2015-06-01

    An electrical short circuit is a rare complication in a high-voltage implantable cardioverter-defibrillator (ICD). However, the inability of an ICD to deliver appropriate shock therapy can be life-threatening. During the last 2 years, four cases of serious complications related to an electrical short circuit have been reported in Japan. A spark due to an electrical short circuit resulted in the failure of an ICD shock to terminate ventricular tachycardia and total damage to the ICD generator in three of four cases. Two of the four patients died from an electrical short circuit between the right ventricle and superior vena cava (SVC) leads. The others had audible sounds from the ICD generator site and were diagnosed with a lead-to-can abrasion, which was manifested by the arc mark on the surface of the can. It is still difficult to predict the occurrence of an electrical short circuit in current ICD systems. To reduce the probability of an electrical short circuit, we suggest the following: (i) avoid lead stress at ICD implantation, (ii) select a single-coil lead instead of a dual-coil lead, or (iii) use a unique algorithm which automatically disconnect can or SVC lead from shock deliver circuit when excessive current was detected. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2015. For permissions please email: journals.permissions@oup.com.

  4. A geometric approach for fault detection and isolation of stator short circuit failure in a single asynchronous machine

    KAUST Repository

    Khelouat, Samir

    2012-06-01

    This paper deals with the problem of detection and isolation of stator short-circuit failure in a single asynchronous machine using a geometric approach. After recalling the basis of the geometric approach for fault detection and isolation in nonlinear systems, we will study some structural properties which are fault detectability and isolation fault filter existence. We will then design filters for residual generation. We will consider two approaches: a two-filters structure and a single filter structure, both aiming at generating residuals which are sensitive to one fault and insensitive to the other faults. Some numerical tests will be presented to illustrate the efficiency of the method.

  5. Matlab/Simulink Implementation of Wave-based Models for Microstrip Structures utilizing Short-circuited and Opened Stubs

    Directory of Open Access Journals (Sweden)

    Biljana P. Stošić

    2011-12-01

    Full Text Available This paper describes modeling and analyzing procedures for microstrip filters based on use of one-dimensional wave digital approach. Different filter structures are observed. One filter is based on quarter-wave length short-circuited stubs and connecting transmission lines. The other one is based on cross-junction opened stubs. Frequency responses are obtained by direct analysis of the block-based networks formed in Simulink toolbox of MATLAB environment. This wave-based method allows an accurate and efficient analysis of different microwave structures.

  6. Fast-responding short circuit protection system with self-reset for use in circuit supplied by DC power

    Science.gov (United States)

    Burns, Bradley M. (Inventor); Blalock, Norman N. (Inventor)

    2011-01-01

    A short circuit protection system includes an inductor, a switch, a voltage sensing circuit, and a controller. The switch and inductor are electrically coupled to be in series with one another. A voltage sensing circuit is coupled across the switch and the inductor. A controller, coupled to the voltage sensing circuit and the switch, opens the switch when a voltage at the output terminal of the inductor transitions from above a threshold voltage to below the threshold voltage. The controller closes the switch when the voltage at the output terminal of the inductor transitions from below the threshold voltage to above the threshold voltage.

  7. Hotspot related plasmon assisted multiphoton photocurrents in metal-insulator-metal junctions

    Energy Technology Data Exchange (ETDEWEB)

    Differt, Dominik; Pfeiffer, Walter [Universitaet Bielefeld, Universitaetsstr. 25, 33615 Bielefeld (Germany); Diesing, Detlef [Universitaet Duisburg-Essen, Universitaetsstr. 5, 45117 Essen (Germany)

    2011-07-01

    Scanning photocurrent microscopy of metal-insulator-metal junctions (MIM) is used to investigate the mechanisms of femtosecond multiphoton photocurrent injection at liquid nitrogen temperature. The locally induced multiphoton photocurrent in a Ag-TaO-Ta MIM junction is measured in a scanning microscope cryostat under focused illumination (5{mu}m focus diameter, 800 nm, 30 fs, 80 MHz repetition rate). The intensity dependence reveals a mixture of two-photon and three-photon processes that are responsible for the photocurrent. Its lateral variation shows hotspot-like behaviour with significant magnitude variations on a 100 to 200 nm length scale. Assuming an injection current duration of 40fs the peak injection current density of about 10{sup 4} A cm{sup -2} is estimated - 10{sup 6} times higher than that for 400 nm continuous wave illumination slightly below the damage threshold. The simultaneously measured extinction of the incident radiation reveals a 20 to 30% increased absorption at the hotspots. We attribute the local photocurrent enhancement to the defect-assisted excitation of surface plasmon polaritons at the silver electrode leading to an enhanced local excitation.

  8. Effect of short circuited DC link capacitor of an AC–DC–AC inverter on the performance of induction motor

    Directory of Open Access Journals (Sweden)

    Hadeed Ahmed Sher

    2016-07-01

    Full Text Available Induction motors are widely used in industrial power plants due to their robustness, reliability and high performance under variable operating conditions in the electrical power system. Modern industrial progress is dependent on these ruggedly constructed induction motors. Almost every sophisticated process of the industry is based on induction motors. Most of these motors are controlled by means of inverters that change the line frequency. The change in parameters of inverter makes it possible to control the motor according to the design requirements. The reliability of inverter based motor control is an important issue for industrial applications and therefore, it becomes very vital for design engineers to have comprehensive analysis of the inverter fed induction machine. This paper investigates one of the faults that may occur on the DC link of an inverter fed induction motor. The effect of the capacitor short circuit is presented in this paper. It also deals with the effects of short circuited capacitor on freewheeling diode. DC link capacitors are well designed and even the probability of capacitor failure is high, it is always a rare case if they puncture, however this analysis will add to the reliability of the induction machine under variable operating condition.

  9. Detection of inter-turn short-circuit at start-up of induction machine based on torque analysis

    Directory of Open Access Journals (Sweden)

    Pietrowski Wojciech

    2017-12-01

    Full Text Available Recently, interest in new diagnostics methods in a field of induction machines was observed. Research presented in the paper shows the diagnostics of induction machine based on torque pulsation, under inter-turn short-circuit, during start-up of a machine. In the paper three numerical techniques were used: finite element analysis, signal analysis and artificial neural networks (ANN. The elaborated numerical model of faulty machine consists of field, circuit and motion equations. Voltage excited supply allowed to determine the torque waveform during start-up. The inter-turn short-circuit was treated as a galvanic connection between two points of the stator winding. The waveforms were calculated for different amounts of shorted-turns from 0 to 55. Due to the non-stationary waveforms a wavelet packet decomposition was used to perform an analysis of the torque. The obtained results of analysis were used as input vector for ANN. The response of the neural network was the number of shorted-turns in the stator winding. Special attention was paid to compare response of general regression neural network (GRNN and multi-layer perceptron neural network (MLP. Based on the results of the research, the efficiency of the developed algorithm can be inferred.

  10. Stator Vibration Characteristic Identification of Turbogenerator among Single and Composite Faults Composed of Static Air-Gap Eccentricity and Rotor Interturn Short Circuit

    Directory of Open Access Journals (Sweden)

    Yu-Ling He

    2016-01-01

    Full Text Available This paper investigates the radial stator vibration characteristics of turbogenerator under the static air-gap eccentricity (SAGE fault, the rotor interturn short circuit (RISC fault, and the composite faults (CFs composed of SAGE and RISC, respectively. Firstly, the impact of the faulty types on the magnetic flux density (MFD is analyzed, based on which the detailed expressions of the magnetic pull per unit area (MPPUA on the stator under different performing conditions are deduced. Then, numerical FEM simulations based on Ansoft and an experimental study are carried out, taking the SDF-9 type fault simulating generator as the study object. It is shown that SAGE will increase the stator vibration at 2f (f is the electrical frequency which already exists even in normal condition, while RISC and CF will bring in stator vibrations at f, 2f, 3f, and 4f at the same time. The vibration amplitudes under CF are larger than those under RISC. As SAGE increases, the vibration amplitudes of each harmonic component under CF will all be increased, while the development of RISC will decrease the 2nd harmonic vibration but meanwhile increase the 4th harmonic vibration. The achievements of this paper are beneficial for fault identification and condition monitoring of the turbogenerator.

  11. Photocurrent enhanced by singlet fission in a dye-sensitized solar cell.

    Science.gov (United States)

    Schrauben, Joel N; Zhao, Yixin; Mercado, Candy; Dron, Paul I; Ryerson, Joseph L; Michl, Josef; Zhu, Kai; Johnson, Justin C

    2015-02-04

    Investigations of singlet fission have accelerated recently because of its potential utility in solar photoconversion, although only a few reports definitively identify the role of singlet fission in a complete solar cell. Evidence of the influence of singlet fission in a dye-sensitized solar cell using 1,3-diphenylisobenzofuran (DPIBF, 1) as the sensitizer is reported here. Self-assembly of the blue-absorbing 1 with co-adsorbed oxidation products on mesoporous TiO2 yields a cell with a peak internal quantum efficiency of ∼70% and a power conversion efficiency of ∼1.1%. Introducing a ZrO2 spacer layer of thickness varying from 2 to 20 Å modulates the short-circuit photocurrent such that it is initially reduced as thickness increases but 1 with 10-15 Å of added ZrO2. This rise can be explained as being due to a reduced rate of injection of electrons from the S1 state of 1 such that singlet fission, known to occur with a 30 ps time constant in polycrystalline films, has the opportunity to proceed efficiently and produce two T1 states per absorbed photon that can subsequently inject electrons into TiO2. Transient spectroscopy and kinetic simulations confirm this novel mode of dye-sensitized solar cell operation and its potential utility for enhanced solar photoconversion.

  12. Control of Internal and External Short Circuits in Lithium Ion and Lithium Batteries, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — NASA has identified needs for compact high-energy-density primary and secondary batteries. Lithium and Lithium Ion cells, respectively, are meeting these needs for...

  13. Study on Turn-to-turn Short Circuit On一line Monitoring System for Dry一type Ai r一core Reactor

    Directory of Open Access Journals (Sweden)

    GAO Zi-wei

    2017-04-01

    Full Text Available The change of current value caused by turn-to-turn short circuit of dry-type air-core reactor is so little that failure detection is difficult to be carried out. In order to solve this problem,a new on-line monitoring system based on impedance variation of turn-to-turn short circuit is proposed. The numerical method is applied to analyze the variation of equivalent resistance and equivalent reactance when dry-type air-core reactor winding short circuit happens in different places,and the monitoring method based on harmonic analysis method and quasi- synchronization sampling method is analyzed by theory. The hardware system,which takes single-chip microcomputer as the core of data processing and logic control,completes data acquisition of voltage signal and current signal of the reactor. In the respect of software design,the impedance variation will be uploaded to the PC after it has been calculated by using the above monitoring method,and then monitoring of turn-to-turn short circuit fault will be realized. Finally,the design of on-line monitoring system is studied by testing. The research result shows that,the equivalent resistance increases and the equivalent reactance decreases when turn-to-turn short circuit occurs,and the variation of equivalent resistance is more obvious than equivalent reactance. The experiment results prove that this monitoring method is true and the on-line monitoring system is feasible.

  14. Diagnosis of Short-Circuit Fault in Large-Scale Permanent-Magnet Wind Power Generator Based on CMAC

    Directory of Open Access Journals (Sweden)

    Chin-Tsung Hsieh

    2013-01-01

    Full Text Available This study proposes a method based on the cerebellar model arithmetic controller (CMAC for fault diagnosis of large-scale permanent-magnet wind power generators and compares the results with Error Back Propagation (EBP. The diagnosis is based on the short-circuit faults in permanent-magnet wind power generators, magnetic field change, and temperature change. Since CMAC is characterized by inductive ability, associative ability, quick response, and similar input signals exciting similar memories, it has an excellent effect as an intelligent fault diagnosis implement. The experimental results suggest that faults can be diagnosed effectively after only training CMAC 10 times. In comparison to training 151 times for EBP, CMAC is better than EBP in terms of training speed.

  15. Laser induced non-monotonic degradation in short-circuit current of triple-junction solar cells

    Science.gov (United States)

    Dou, Peng-Cheng; Feng, Guo-Bin; Zhang, Jian-Min; Song, Ming-Ying; Zhang, Zhen; Li, Yun-Peng; Shi, Yu-Bin

    2018-06-01

    In order to study the continuous wave (CW) laser radiation effects and mechanism of GaInP/GaAs/Ge triple-junction solar cells (TJSCs), 1-on-1 mode irradiation experiments were carried out. It was found that the post-irradiation short circuit current (ISC) of the TJSCs initially decreased and then increased with increasing of irradiation laser power intensity. To explain this phenomenon, a theoretical model had been established and then verified by post-damage tests and equivalent circuit simulations. Conclusion was drawn that laser induced alterations in the surface reflection and shunt resistance were the main causes for the observed non-monotonic decrease in the ISC of the TJSCs.

  16. Effect of notch depth of modified current collector on internal-short-circuit mitigation for lithium-ion battery

    Science.gov (United States)

    Wang, Meng; Noelle, Daniel J.; Shi, Yang; Le, Anh V.; Qiao, Yu

    2018-01-01

    Formation of internal short circuit (ISC) may result in catastrophic thermal runaway of lithium-ion battery (LIB). Among LIB cell components, direct contact between cathode and anode current collectors is most critical to the ISC behavior, yet is still relatively uninvestigated. In the current study, we analyze the effect of heterogeneity of current collector on the temperature increase of LIB cells subjected to mechanical abuse. The cathode current collector is modified by surface notches, so that it becomes effectively brittle and the ISC site can be isolated. Results from impact tests on LIB cells with modified current collectors suggest that their temperature increase can be negligible. The critical parameters include the failure strain and the failure work of modified current collector, both of which are related to the notch depth.

  17. Rapid battery depletion and loss of therapy due to a short circuit in bipolar DBS for essential tremor.

    Science.gov (United States)

    Allert, Niels; Barbe, Michael Thomas; Timmermann, Lars; Coenen, Volker Arnd

    2017-05-01

    Technical dysfunctions have been reported reducing efficacy of deep brain stimulation (DBS). Here, we report on an essential-tremor patient in whom a short circuit in bipolar DBS resulted not only in unilateral loss of therapy but also in high current flow and thereby rapid decline of the impulse-generator battery voltage from 2.83 V a week before the event to 2.54 V, indicating the need for an impulse-generator replacement. Immediate re-programming restored therapeutic efficacy. Moreover, the reduction in current flow allowed the battery voltage to recover without immediate surgical intervention to 2.81 V a week later.

  18. Proton exchange membrane fuel cell operation and degradation in short-circuit.

    OpenAIRE

    Silva , R.E.; Harel , F.; Jemei , S.; Gouriveau , Rafael; Hissel , Daniel; Boulon , L.; Agbossou , K.

    2013-01-01

    International audience; Hybridization of proton exchange membrane fuel cells (PEMFC) and ultra capacitors (UC) are considered as an alternative way to implement high autonomy, high dynamic, and reversible energy sources. PEMFC allow high efficiency and high autonomy, however their dynamic response is limited and this source does not allow recovering energy. UC appears to be a complementary source to fuel cell systems (FCS) due to their high power density, fast dynamics, and reversibility. A d...

  19. Model-based fault diagnosis approach on external short circuit of lithium-ion battery used in electric vehicles

    International Nuclear Information System (INIS)

    Chen, Zeyu; Xiong, Rui; Tian, Jinpeng; Shang, Xiong; Lu, Jiahuan

    2016-01-01

    Highlights: • The characteristics of ESC fault of lithium-ion battery are investigated experimentally. • The proposed method to simulate the electrical behavior of ESC fault is viable. • Ten parameters in the presented fault model were optimized using a DPSO algorithm. • A two-layer model-based fault diagnosis approach for battery ESC is proposed. • The effective and robustness of the proposed algorithm has been evaluated. - Abstract: This study investigates the external short circuit (ESC) fault characteristics of lithium-ion battery experimentally. An experiment platform is established and the ESC tests are implemented on ten 18650-type lithium cells considering different state-of-charges (SOCs). Based on the experiment results, several efforts have been made. (1) The ESC process can be divided into two periods and the electrical and thermal behaviors within these two periods are analyzed. (2) A modified first-order RC model is employed to simulate the electrical behavior of the lithium cell in the ESC fault process. The model parameters are re-identified by a dynamic-neighborhood particle swarm optimization algorithm. (3) A two-layer model-based ESC fault diagnosis algorithm is proposed. The first layer conducts preliminary fault detection and the second layer gives a precise model-based diagnosis. Four new cells are short-circuited to evaluate the proposed algorithm. It shows that the ESC fault can be diagnosed within 5 s, the error between the model and measured data is less than 0.36 V. The effectiveness of the fault diagnosis algorithm is not sensitive to the precision of battery SOC. The proposed algorithm can still make the correct diagnosis even if there is 10% error in SOC estimation.

  20. Photocurrent and photothermal current of polypyrrole (PPy) film

    Energy Technology Data Exchange (ETDEWEB)

    Zhao Chongjun; Wang Haihong; Jiang Zhiyu

    2003-02-28

    The photoelectrochemical properties of polypyrrole (PPy) film in aqueous solutions in the potential region of -0.7 to 0.5 V (versus Ag/AgCl) were investigated by using photocurrent, photothermal and photothermal current methods under the irradiation of laser beams with wavelength of 532 and 632.8 nm, respectively. It was found that the photocurrent at more negative potential was caused by the p-type semiconductor properties, while the photocurrent at more positive potential was caused by the local temperature rather than the semiconductor properties of the films. The effect of the film thickness on the photocurrent of PPy films was studied in detail.

  1. Photocurrent and photothermal current of polypyrrole (PPy) film

    International Nuclear Information System (INIS)

    Zhao Chongjun; Wang Haihong; Jiang Zhiyu

    2003-01-01

    The photoelectrochemical properties of polypyrrole (PPy) film in aqueous solutions in the potential region of -0.7 to 0.5 V (versus Ag/AgCl) were investigated by using photocurrent, photothermal and photothermal current methods under the irradiation of laser beams with wavelength of 532 and 632.8 nm, respectively. It was found that the photocurrent at more negative potential was caused by the p-type semiconductor properties, while the photocurrent at more positive potential was caused by the local temperature rather than the semiconductor properties of the films. The effect of the film thickness on the photocurrent of PPy films was studied in detail

  2. The principle of elaboration of the relay protection against short circuits between the closely placed phases of high voltage electrical line

    Directory of Open Access Journals (Sweden)

    Kiorsak M.

    2015-12-01

    Full Text Available The article is devoted to the elaboration of the principle of relay protection against short circuits between the closely placed phases of higher voltage electrical line with self-compensation, based on the six phase’s symmetrical components. It is shown that the unsymmetrical short circuits between the closely placed phases are characterized by appearance of zero and tertiary sequences of symmetrical components. This fact can be used to choose them for relay protection. The electrical basic circuits and formulas for calculation of the passive parameters of zero and tertiary filters of currents (voltages are done. It is presented the structural-functional basic circuit scheme for relay protection against short circuits between the closely placed phases of higher voltage electrical line with self-compensation.

  3. Optimization of the short-circuit current in an InP nanowire array solar cell through opto-electronic modeling.

    Science.gov (United States)

    Chen, Yang; Kivisaari, Pyry; Pistol, Mats-Erik; Anttu, Nicklas

    2016-09-23

    InP nanowire arrays with axial p-i-n junctions are promising devices for next-generation photovoltaics, with a demonstrated efficiency of 13.8%. However, the short-circuit current in such arrays does not match their absorption performance. Here, through combined optical and electrical modeling, we study how the absorption of photons and separation of the resulting photogenerated electron-hole pairs define and limit the short-circuit current in the nanowires. We identify how photogenerated minority carriers in the top n segment (i.e. holes) diffuse to the ohmic top contact where they recombine without contributing to the short-circuit current. In our modeling, such contact recombination can lead to a 60% drop in the short-circuit current. To hinder such hole diffusion, we include a gradient doping profile in the n segment to create a front surface barrier. This approach leads to a modest 5% increase in the short-circuit current, limited by Auger recombination with increased doping. A more efficient approach is to switch the n segment to a material with a higher band gap, like GaP. Then, a much smaller number of holes is photogenerated in the n segment, strongly limiting the amount that can diffuse and disappear into the top contact. For a 500 nm long top segment, the GaP approach leads to a 50% higher short-circuit current than with an InP top segment. Such a long top segment could facilitate the fabrication and contacting of nanowire array solar cells. Such design schemes for managing minority carriers could open the door to higher performance in single- and multi-junction nanowire-based solar cells.

  4. Analytical model for the photocurrent-voltage characteristics of bilayer MEH-PPV/TiO2 photovoltaic devices

    Directory of Open Access Journals (Sweden)

    Chen Chong

    2011-01-01

    Full Text Available Abstract The photocurrent in bilayer polymer photovoltaic cells is dominated by the exciton dissociation efficiency at donor/acceptor interface. An analytical model is developed for the photocurrent-voltage characteristics of the bilayer polymer/TiO2 photovoltaic cells. The model gives an analytical expression for the exciton dissociation efficiency at the interface, and explains the dependence of the photocurrent of the devices on the internal electric field, the polymer and TiO2 layer thicknesses. Bilayer polymer/TiO2 cells consisting of poly[2-methoxy-5-(2-ethylhexyloxy-1,4-phenylenevinylene] (MEH-PPV and TiO2, with different thicknesses of the polymer and TiO2 films, were prepared for experimental purposes. The experimental results for the prepared bilayer MEH-PPV/TiO2 cells under different conditions are satisfactorily fitted to the model. Results show that increasing TiO2 or the polymer layer in thickness will reduce the exciton dissociation efficiency in the device and further the photocurrent. It is found that the photocurrent is determined by the competition between the exciton dissociation and charge recombination at the donor/acceptor interface, and the increase in photocurrent under a higher incident light intensity is due to the increased exciton density rather than the increase in the exciton dissociation efficiency.

  5. A method of increasing the sensitivity of protection from single-phase short-circuits to ground in the 6 – 10 kV network

    International Nuclear Information System (INIS)

    Manilov, A. M.; Mel’nik, D. A.

    2012-01-01

    A method of increasing the sensitivity of protection from single-phase short-circuits to ground by acting on the signal with brief dummy grounding of the neutral is described. After determining the damage, the neutral is again grounded through a high resistance and an arc-quenching reactor. An increase in the protection sensitivity is thereby obtained, the damage detection time is shortened, and the probability of the single-phase short-circuit to ground converting into double and multipoint earth faults is reduced.

  6. Improve photocurrent quantum efficiency of carbon nanotube by chemical treatment

    International Nuclear Information System (INIS)

    Wang Hongguang; Wei Jinquan; Jia Yi; Li Zhen; Zhu Hongwei; Wang Kunlin; Wu Dehai

    2012-01-01

    Highlights: ► The QE of photocurrent for the H 2 O 2 -treated CNTs reaches to 5.28% at U bias = 0.1 V. ► Moderate chemical treatment can enhance the QE of photocurrent of CNTs. ► Excessive chemical treatment decreases the photocurrent quantum efficiency of CNTs. - Abstract: High photocurrent quantum efficiency (QE) of carbon nanotubes (CNTs) is important to their photovoltaic applications. The ability of photocurrent generation of CNTs depends on their band structure and surface state. For given CNTs, it is possible to improve the QE of photocurrent by chemical modification. Here, we study the effects of simple chemical treatment on the QE of CNTs by measuring the photocurrent of macroscopic CNT bundles. The QE of the H 2 O 2 -treated CNT bundle reaches 5.28% at 0.1 V bias voltage at a laser (λ = 473 nm) illumination, which is 85% higher than that of the pristine sample. But the QE of the CNTs treated in concentrated HNO 3 is lower than that of the pristine sample. It shows that moderate chemical treatment can enhance the photocurrent QE and excessive chemical treatment will decrease the QE because of introducing lots of structural defects.

  7. Fast Calculation Model and Theoretical Analysis of Rotor Unbalanced Magnetic Pull for Inter-Turn Short Circuit of Field Windings of Non-Salient Pole Generators

    Directory of Open Access Journals (Sweden)

    Guangtao Zhang

    2017-05-01

    Full Text Available Inter-turn short circuit of field windings (ISCFW may cause the field current of a generator to increase, output reactive power to decrease, and unit vibration to intensify, seriously affecting its safe and stable operation. Full integration of mechanical and electrical characteristics can improve the sensitivity of online monitoring, and detect the early embryonic period fault of small turns. This paper studies the calculations and variations of unbalanced magnetic pull (UMP, of which the excitation source of rotor vibration is the basis and key to online fault monitoring. In grid load operation, ISCFW are first calculated with the multi-loop method, so as to obtain the numerical solutions of the stator and the rotor currents during the fault. Next, the air-gap magnetic field of the ISCFW is analyzed according to the actual composition modes of the motor loops in the fault, so as to obtain the analytic expressions of the air-gap magnetic motive force (MMF and magnetic density. The UMP of the rotor is obtained by solving the integral of the Maxwell stress. The correctness of the electric quantity calculation is verified by the ISCFW experiment, conducted in a one pair-pole non-salient pole model machine. On this basis, comparing the simulation analysis with the calculation results of the model in this paper not only verifies the accuracy of the electromagnetic force calculation, but also proves that the latter has the advantages of a short time consumption and high efficiency. Finally, the influencing factors and variation law of UMP are analyzed by means of an analytic model. This develops a base for the online monitoring of ISCFW with the integration of mechanical and electrical information.

  8. Controlled Conjugated Backbone Twisting for an Increased Open-Circuit Voltage while Having a High Short-Circuit Current in Poly(hexylthiophene) Derivatives

    KAUST Repository

    Ko, Sangwon; Hoke, Eric T.; Pandey, Laxman; Hong, Sanghyun; Mondal, Rajib; Risko, Chad; Yi, Yuanping; Noriega, Rodrigo; McGehee, Michael D.; Bré das, Jean-Luc; Salleo, Alberto; Bao, Zhenan

    2012-01-01

    and charge-transfer state energy of the polymer:fullerene BHJ solar cells increased substantially with the degree of twist induced within the conjugated backbone-due to an increase in the polymer ionization potential-while the short-circuit current decreased

  9. Modelling Li-ion cell thermal runaway triggered by an internal short circuit device using an efficiency factor and Arrhenius formulations

    DEFF Research Database (Denmark)

    Coman, Paul Tiberiu; Darcy, Eric; Veje, Christian

    2017-01-01

    This paper presents a novel model for analyzing the thermal runaway in Li-ion battery cells with an internal short circuit device implanted in the cell. The model is constructed using Arrhenius formulations for representing the self-heating chemical reactions and the State of Charge. The model...

  10. Short-circuit ruggedness assessment of a 1.2 kV/180 A SiC MOSFET power module

    DEFF Research Database (Denmark)

    Ionita, Claudiu; Nawaz, Muhammad; Ilves, Kalle

    2017-01-01

    is typically encountered in applications for devices of these ratings. Five modules were failed in total, with a critical short-circuit energy, Ecr ranging from 7.3 J to 9.7 J. The failure mechanism is generally the thermal runaway. Prior to failure, a decrease in VGS can be observed which is an indication...

  11. Prospective single and multi-phase short-circuit current levels in the Dutch transmission, sub-transmission and distribution grids

    NARCIS (Netherlands)

    Janssen, A.L.J.; van Riet, M.J.M.; Smeets, R.P.P.; Kanters, J.; van den Akker, W.F.; Aanhaanen, G.L.P.

    2012-01-01

    As elsewhere in the world, also in the Netherlands utilities face an increase in the actual and future short-circuit current levels at all voltages. This development is provoked by the required increase in transmission capacity as well as the concentration of power generation capacity. Large

  12. Sub-module Short Circuit Fault Diagnosis in Modular Multilevel Converter Based on Wavelet Transform and Adaptive Neuro Fuzzy Inference System

    DEFF Research Database (Denmark)

    Liu, Hui; Loh, Poh Chiang; Blaabjerg, Frede

    2015-01-01

    for continuous operation and post-fault maintenance. In this article, a fault diagnosis technique is proposed for the short circuit fault in a modular multi-level converter sub-module using the wavelet transform and adaptive neuro fuzzy inference system. The fault features are extracted from output phase voltage...

  13. The factors influencing nonlinear characteristics of the short-circuit current in dye-sensitized solar cells investigated by a numerical model.

    Science.gov (United States)

    Shi, Yushuai; Dong, Xiandui

    2013-06-24

    A numerical model for interpretation of the light-intensity-dependent nonlinear characteristics of the short-circuit current in dye-sensitized solar cells is suggested. The model is based on the continuity equation and includes the influences of the nongeminate recombination between electrons and electron acceptors in the electrolyte and the geminate recombination between electrons and oxidized dye molecules. The influences of the order and rate constant of the nongeminate recombination reaction, the light-absorption coefficient of the dye, the film thickness, the rate constant of geminate recombination, and the regeneration rate constant on the nonlinear characteristics of the short-circuit current are simulated and analyzed. It is proposed that superlinear and sublinear characteristics of the short-circuit current should be attributed to low electron-collection efficiency and low dye-regeneration efficiency, respectively. These results allow a deep understanding of the origin of the nonlinear characteristics of the short-circuit current in solar cells. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Effects of an electromagnetic shield and armature teeth on the short-circuit performance of a direct drive superconducting generator for 10 MW wind turbines

    DEFF Research Database (Denmark)

    Liu, Dong; Polinder, Henk; Abrahamsen, Asger Bech

    2015-01-01

    reactance. An electromagnetic (EM) shield between the rotor and the stator as well as iron or non-magnetic composite (NMC) armature teeth affects the sub-transient reactance of a superconducting machine so that they play a role in the short-circuit performance of a superconducting wind generator. This paper...

  15. MATHEMATICAL MODELING OF TRANSIENT EMERGENCY ELECTROMAGNETIC PROCESSES IN THE SYSTEM OF THE ELECTROMAGNETIC TRACTION DC. 2. SHORT CIRCUIT WITH ELECTRIC ROLLING STOCK

    Directory of Open Access Journals (Sweden)

    P. E. Mihalichenko

    2010-04-01

    Full Text Available The article deals with the description of mathematical model of the system of traction electric power supply with load in the short circuit condition as well as the calculation results of this emergency process. The transition values as well as the character of their change, which can be used for detection of emergency processes, have been determined.

  16. Room Temperature Magnetic Field Measurements as a Tool to Localize Inter-turns Electrical Short Circuits in the LHC Main Dipole coils

    CERN Document Server

    Bellesia, B; Todesco, E

    2006-01-01

    In this report the method for the localization of the electric shorts circuits in the main LHC dipoles using the magnetic measurements at room temperature is presented. The steps of the method are discussed, and two cases are studied in detail. A complete statistics of the 12 cases analyzed up to now is given.

  17. A new method for determining the transient photocurrent in an irradiated diode

    International Nuclear Information System (INIS)

    Bruguier, G.; Pelanchon, F.; Sudre, C.; Moreau, Y.; De la Rochette, H.; Baggio, J.; Gasiot, J.; Azais, B.

    1994-01-01

    An analytical expression of the photocurrent in a n-p junction exposed to an ionizing radiation pulse is derived by using a specific decomposition of the minority carrier density. Modeling can be applied to any shape of actual radiation pulses, in particular with significant rise times. Comparisons with experiments and numerical resolutions have shown the validity of the modeling. (author). 8 refs., 2 figs., Appendix (calculations)

  18. On-Line Detection of Coil Inter-Turn Short Circuit Faults in Dual-Redundancy Permanent Magnet Synchronous Motors

    Directory of Open Access Journals (Sweden)

    Yiguang Chen

    2018-03-01

    Full Text Available In the aerospace and military fields, with high reliability requirements, the dual-redundancy permanent magnet synchronous motor (DRPMSM with weak thermal coupling and no electromagnetic coupling is needed. A common fault in the DRPMSM is the inter-turn short circuit fault (ISCF. However, research on how to diagnose ISCF and the set of faulty windings in the DRPMSM is lacking. In this paper, the structure of the DRPMSM is analyzed and mathematical models of the motor under normal and faulty conditions are established. Then an on-line ISCF detection scheme, which depends on the running modes of the DRPMSM and the average values for the difference of the d-axis voltages between two sets of windings in the latest 20 sampling periods, is proposed. The main contributions of this paper are to analyze the calculation for the inductance of each part of the stator windings and propose the on-line diagnosis method of the ISCF under various operating conditions. The simulation and experimental results show that the proposed method can quickly and effectively diagnose ISCF and determine the set of faulty windings of the DRPMSM.

  19. KNOWLEDGE TRANSFER AND LEARNING: PROBLEMS OF KNOWLEDGE TRANSFER ASSOCIATED WITH TRYING TO SHORT-CIRCUIT THE LEARNING CYCLE

    Directory of Open Access Journals (Sweden)

    Sue Newell

    2006-11-01

    Full Text Available Knowledge is considered to be a key organizational resource in the 21st century and the knowledge management ‘movement’ has alerted organizations to the fact that they should more strategically exploit their knowledge assets. Companies are thus lured by the suggestion that they can gain competitive advantage by the more astute management of their knowledge base and in particular, by the transfer of knowledge across individuals, groups and organizational units, using IT to accomplish this. In this paper, we reflect on this common view of knowledge transfer. More specifically, we question an implication of this view - essentially the possibility of short-circuiting the learning cycle, so that individuals do not have to rely on their personal or shared experiences to identify better practices, but can learn from the codified lessons of others in IT systems. More importantly, we consider the characteristics of knowledge – that knowledge is distributed, ambiguous and disruptive – that makes its transfer highly problematic. Drawing on case research, we relate this to the learning cycle (Kolb 1984 and thereby identify barriers to knowledge transfer. We conclude by considering ways of overcoming these barriers by emphasizing the importance of social systems alongside technical systems.

  20. Theoretical and experimental analysis of a linear accelerator endowed with single feed coupler with movable short-circuit

    International Nuclear Information System (INIS)

    Forno, Massimo Dal; Craievich, Paolo; Penco, Giuseppe; Vescovo, Roberto

    2013-01-01

    The front-end injection systems of the FERMI@Elettra linac produce high brightness electron beams that define the performance of the Free Electron Laser. The photoinjector mainly consists of the radiofrequency (rf) gun and of two S-band rf structures which accelerate the beam. Accelerating structures endowed with a single feed coupler cause deflection and degradation of the electron beam properties, due to the asymmetry of the electromagnetic field. In this paper, a new type of single feed structure with movable short-circuit is proposed. It has the advantage of having only one waveguide input, but we propose a novel design where the dipolar component is reduced. Moreover, the racetrack geometry allows to reduce the quadrupolar component. This paper presents the microwave design and the analysis of the particle motion inside the linac. A prototype has been machined at the Elettra facility to verify the new coupler design and the rf field has been measured by adopting the bead-pull method. The results are here presented, showing good agreement with the expectations

  1. Simultaneous improvement in short circuit current, open circuit voltage, and fill factor of polymer solar cells through ternary strategy.

    Science.gov (United States)

    An, Qiaoshi; Zhang, Fujun; Li, Lingliang; Wang, Jian; Sun, Qianqian; Zhang, Jian; Tang, Weihua; Deng, Zhenbo

    2015-02-18

    We present a smart strategy to simultaneously increase the short circuit current (Jsc), the open circuit voltage (Voc), and the fill factor (FF) of polymer solar cells (PSCs). A two-dimensional conjugated small molecule photovoltaic material (SMPV1), as the second electron donor, was doped into the blend system of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C71-butyric acid methyl (PC71BM) to form ternary PSCs. The ternary PSCs with 5 wt % SMPV1 doping ratio in donors achieve 4.06% champion power conversion efficiency (PCE), corresponding to about 21.2% enhancement compared with the 3.35% PCE of P3HT:PC71BM-based PSCs. The underlying mechanism on performance improvement of ternary PSCs can be summarized as (i) harvesting more photons in the longer wavelength region to increase Jsc; (ii) obtaining the lower mixed highest occupied molecular orbital (HOMO) energy level by incorporating SMPV1 to increase Voc; (iii) forming the better charge carrier transport channels through the cascade energy level structure and optimizing phase separation of donor/acceptor materials to increase Jsc and FF.

  2. Mechanism of the entire overdischarge process and overdischarge-induced internal short circuit in lithium-ion batteries.

    Science.gov (United States)

    Guo, Rui; Lu, Languang; Ouyang, Minggao; Feng, Xuning

    2016-07-22

    Lithium-ion batteries connected in series are prone to be overdischarged. Overdischarge results in various side effects, such as capacity degradation and internal short circuit (ISCr). However, most of previous research on the overdischarge of a cell was terminated when the cell voltage dropped to 0 V, leaving the further impacts of overdischarge unclear. This paper investigates the entire overdischarge process of large-format lithium-ion batteries by discharging the cell to -100% state of charge (SOC). A significant voltage platform is observed at approximately -12% SOC, and ISCr is detected after the cell is overdischarged when passing the platform. The scanning electron microscopy (SEM) and X-ray diffraction (XRD) results indicate that the overdischarge-induced ISCr is caused by Cu deposition on electrodes, suggesting possible Cu collector dissolution at the voltage platform near -12% SOC. A prognostic/mechanistic model considering ISCr is used to evaluate the resistance of ISCr (RISCr), the value of which decreases sharply at the beginning of ISCr formation. Inducing the ISCr by overdischarge is effective and well controlled without any mechanical deformation or the use of a foreign substance.

  3. Eco-friendly preparation of large-sized graphene via short-circuit discharge of lithium primary battery.

    Science.gov (United States)

    Kang, Shaohong; Yu, Tao; Liu, Tingting; Guan, Shiyou

    2018-02-15

    We proposed a large-sized graphene preparation method by short-circuit discharge of the lithium-graphite primary battery for the first time. LiC x is obtained through lithium ions intercalation into graphite cathode in the above primary battery. Graphene was acquired by chemical reaction between LiC x and stripper agents with dispersion under sonication conditions. The gained graphene is characterized by Raman spectrum, X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Atomic force microscope (AFM) and Scanning electron microscopy (SEM). The results indicate that the as-prepared graphene has a large size and few defects, and it is monolayer or less than three layers. The quality of graphene is significant improved compared to the reported electrochemical methods. The yield of graphene can reach 8.76% when the ratio of the H 2 O and NMP is 3:7. This method provides a potential solution for the recycling of waste lithium ion batteries. Copyright © 2017 Elsevier Inc. All rights reserved.

  4. Theoretical and experimental analysis of a linear accelerator endowed with single feed coupler with movable short-circuit.

    Science.gov (United States)

    Dal Forno, Massimo; Craievich, Paolo; Penco, Giuseppe; Vescovo, Roberto

    2013-11-01

    The front-end injection systems of the FERMI@Elettra linac produce high brightness electron beams that define the performance of the Free Electron Laser. The photoinjector mainly consists of the radiofrequency (rf) gun and of two S-band rf structures which accelerate the beam. Accelerating structures endowed with a single feed coupler cause deflection and degradation of the electron beam properties, due to the asymmetry of the electromagnetic field. In this paper, a new type of single feed structure with movable short-circuit is proposed. It has the advantage of having only one waveguide input, but we propose a novel design where the dipolar component is reduced. Moreover, the racetrack geometry allows to reduce the quadrupolar component. This paper presents the microwave design and the analysis of the particle motion inside the linac. A prototype has been machined at the Elettra facility to verify the new coupler design and the rf field has been measured by adopting the bead-pull method. The results are here presented, showing good agreement with the expectations.

  5. Impact of hydroelectric installations on the morphology's short-circuited reaches of the Durance and the Verdon Rivers

    International Nuclear Information System (INIS)

    Lefort, Philippe; Chapuis, Margot

    2012-01-01

    Attenuation of flood peaks by the reservoirs of Serre Poncon and along the Verdon River, and diversions of the Durance River's flow in the industrial canal significantly modify the flow regime in the short-circuited beds. Upstream inflow of gravel materials is decreased, bed-load transport is significantly reduced, channels' mobility is atrophied, or becomes even nonexistent. The vegetation impact leads then to an obstruction of the braided channel, the rare occurrence of high flows is not able to prevent. Clearing the bed has been and stays an efficient response to the vegetation encroachment, and a necessary condition to maintain the discharge capacity during high flow, the originality and the diversity of the natural landforms. The loss of mobility is also due to bed-load transport's interruption through dams, but even more to the past gravel extractions and to weirs that sustain low flow: bed-load transport restoration through dams, sedimentary recharge of the bed with gravels coming from lateral terraces and increasing of high flows intensity will lead to a minimal required mobility. (authors)

  6. Radial direct bandgap p-i-n GaNP microwire solar cells with enhanced short circuit current

    Energy Technology Data Exchange (ETDEWEB)

    Sukrittanon, Supanee [Graduate Program of Materials Science and Engineering, University of California, San Diego, La Jolla, California 92037 (United States); Liu, Ren; Pan, Janet L. [Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California 92037 (United States); Breeden, Michael C. [Department of Nanoengineering, University of California, San Diego, La Jolla, California 92037 (United States); Jungjohann, K. L. [Center for Integrated Nanotechnologies, Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States); Tu, Charles W., E-mail: ctu@ece.ucsd.edu, E-mail: sdayeh@ece.ucsd.edu; Dayeh, Shadi A., E-mail: ctu@ece.ucsd.edu, E-mail: sdayeh@ece.ucsd.edu [Graduate Program of Materials Science and Engineering, University of California, San Diego, La Jolla, California 92037 (United States); Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California 92037 (United States)

    2016-08-07

    We report the demonstration of dilute nitride heterostructure core/shell microwire solar cells utilizing the combination of top-down reactive-ion etching to create the cores (GaP) and molecular beam epitaxy to create the shells (GaNP). Systematic studies of cell performance over a series of microwire lengths, array periods, and microwire sidewall morphologies examined by transmission electron microscopy were conducted to shed light on performance-limiting factors and to optimize the cell efficiency. We show by microscopy and correlated external quantum efficiency characterization that the open circuit voltage is degraded primarily due to the presence of defects at the GaP/GaNP interface and in the GaNP shells, and is not limited by surface recombination. Compared to thin film solar cells in the same growth run, the microwire solar cells exhibit greater short circuit current but poorer open circuit voltage due to greater light absorption and number of defects in the microwire structure, respectively. The comprehensive understanding presented in this work suggests that performance benefits of dilute nitride microwire solar cells can be achieved by further tuning of the epitaxial quality of the underlying materials.

  7. Short-Circuit Fault Tolerant Control of a Wind Turbine Driven Induction Generator Based on Sliding Mode Observers

    Directory of Open Access Journals (Sweden)

    Takwa Sellami

    2017-10-01

    Full Text Available The installed energy production capacity of wind turbines is growing intensely on a global scale, making the reliability of wind turbine subsystems of greater significance. However, many faults like Inter-Turn Short-Circuit (ITSC may affect the turbine generator and quickly lead to a decline in supplied power quality. In this framework, this paper proposes a Sliding Mode Observer (SMO-based Fault Tolerant Control (FTC scheme for Induction Generator (IG-based variable-speed grid-connected wind turbines. First, the dynamic models of the wind turbine subsystems were developed. The control schemes were elaborated based on the Maximum Power Point Tracking (MPPT method and Indirect Rotor Flux Oriented Control (IRFOC method. The grid control was also established by regulating the active and reactive powers. The performance of the wind turbine system and the stability of injected power to the grid were hence analyzed under both healthy and faulty conditions. The robust developed SMO-based Fault Detection and Isolation (FDI scheme was proved to be fast and efficient for ITSC detection and localization.Afterwards, SMO were involved in scheming the FTC technique. Accordingly, simulation results assert the efficacy of the proposed ITSC FTC method for variable-speed wind turbines with faulty IG in protecting the subsystems from damage and ensuring continuous connection of the wind turbine to the grid during ITSC faults, hence maintaining power quality.

  8. Effect of photocurrent enhancement in porphyrin–graphene covalent hybrids

    International Nuclear Information System (INIS)

    Tang, Jianguo; Niu, Lin; Liu, Jixian; Wang, Yao; Huang, Zhen; Xie, Shiqiang; Huang, Linjun; Xu, Qingsong; Wang, Yuan; Belfiore, Laurence A.

    2014-01-01

    Graphene oxide (GO) sheets were covalently functionalized with 5-p-aminophenyl-10,15,20-triphenylporphyrin (NH 2 TPP) by an amidation reaction between the amino group in NH 2 TPP and carboxyl groups in GO. The Fourier transform infrared spectroscopy, nuclear magnetic resonance, scanning and transmission electron microscopies reveal that NH 2 TPP covalent bonds form on the double surface of graphene oxide sheets, generating a unique nano-framework, i.e., NH 2 TPP-graphene-NH 2 TPP. Its UV–visible spectroscopy reveals that the absorption spectrum is not a linear superposition of the spectra of NH 2 TPP and graphene oxide, because a 59 nm red shift of the strong graphene oxide absorption is observed from 238 to 297 nm, with significant spectral broadening between 300 and 700 nm. Fluorescence emission spectroscopy indicates efficient quenching of NH 2 TPP photoluminescence in this hybrid material, suggesting that photo-induced electron transfer occurs at the interface between NH 2 TPP and GO. A reversible on/off photo-current density of 47 mA/cm 2 is observed when NH 2 TPP-graphene-NH 2 TPP hybrid sandwiches are subjected to pulsed white-light illumination. Covalently-bound porphyrins decrease the optical HOMO/LUMO band gap of graphene oxide by ≈ 1 eV, according to UV–visible spectroscopy. Cyclic voltammetry predicts a small HOMO/LUMO band gap of 0.84 eV for NH 2 TPP-graphene-NH 2 TPP hybrid sandwiches, which is consistent with efficient electron transfer and fluorescence quenching. - Highlights: • Porphyrins are covalently bound to sheets of graphene oxide via an amidation reaction. • The formed hetero-junction interface decreases the optical band gap of graphene oxide. • Cyclic voltammetry predicts a graphene oxide band gap of 0.84 eV, which is easily photo-excited. • Its on/off photo-current density of 46 μA/cm 2 is 5-fold larger than that for physically stacked hybrid

  9. Mediator-assisted photocurrent extraction from the thylakoids

    International Nuclear Information System (INIS)

    Yu, Yue; Zuo, Fulin; Li, Chen-Zhong

    2014-01-01

    Photocurrent extracted from the thylakoids has been studied as a function of electron mediator concentration. Phenazine methosulfate is used to facilitate the charge transfer from the thylakoid's charge transport chain to the outside medium. The photocurrent has been shown to originate from the photosynthesis on the thylakoid membranes. Comparing with a previous study using para-Benzoquinone as the mediator, a similar peak effect in the photocurrent as a function of concentration is observed, but the magnitude of the current is nearly a thousand times greater. A semi-quantitative analysis is presented to explain the data found in those systems

  10. Model of Organic Solar Cell Photocurrent Including the Effect of Charge Accumulation at Interfaces and Non-Uniform Carrier Generation

    DEFF Research Database (Denmark)

    Torto, Lorenzo; Cester, Andrea; Rizzo, Antonio

    2017-01-01

    We developed an improved model to fit the photocurrent density versus voltage in organic solar cells. The model has been validated by fitting data from P3HT:PCBM solar cells. Our model quantitatively accounts for the band bending near the electrodes caused by charge accumulation in the active layer...

  11. Minimization of the Electromagnetic Torque Ripple Caused by the Coils Inter-Turn Short Circuit Fault in Dual-Redundancy Permanent Magnet Synchronous Motors

    Directory of Open Access Journals (Sweden)

    Yiguang Chen

    2017-11-01

    Full Text Available With the development of electric vehicles and More-Electric/All-Electric aircraft, high reliability is required in motor servo systems. The redundancy technique is one of the most effective methods to improve the reliability of motor servo systems. In this paper, the structure of dual-redundancy permanent magnet synchronous motor (DRPMSM with weak thermal coupling and no electromagnetic coupling is analyzed and the mathematical model of this motor is established. However, there is little research on how to suppress the torque ripple caused by short-circuited coils in the DRPMSM. The main contribution of this paper is to present the advantages of DRPMSM and to find a way to suppress the torque ripple caused by the short circuit fault in DRPMSM. In order to improve operation quality and enhance the reliability of DRPMSM after a short circuit occurs, the torque ripple caused by the coils inter-turn short circuit fault in DRPMSM is analyzed in detail. Then, a control method for suppressing the electromagnetic torque ripple of a short-circuited coil is proposed for the first time by using an improved adaptive proportional resonant (PR controller and a proportional integral (PI controller in parallel. PR control is a method of controlling alternating components without steady-state error, and it can be used to suppress torque ripple. DRPMSM adopts speed and current double closed-loop control strategies. An improved adaptive PR controller and a PI controller are employed in parallel for the speed loop, while traditional PI control is adopted in current loop. From the simulation and experimental results, the torque ripple is reduced from 45.4 to 5.6% when the torque ripple suppression strategy proposed in this paper is adopted, in the case that the speed is 600 r/min. The torque ripple suppression strategy based on the PR controller can quickly and effectively suppress the torque ripple caused by the short-circuited coils, which makes the motor speed

  12. Imaging of Polarization-dependent Photocurrent in Graphene Photodevices

    Science.gov (United States)

    Kim, Minjung; Yoon, Duhee; Ang Yoon, Ho; Lee, Sang Wook; Cheong, Hyeonsik

    2012-02-01

    Recently, a metal-graphene-metal photodetector for high-speed optical communications was reported. In addition, a graphene-based photodetector was reported to be able to absorb broadband light owing to the unique band structure of graphene [Mueller et al., Nature Photonics 4, 297 (2010)]. We investigated the polarization dependence of the photocurrent generated in metal-graphene-metal junctions. The graphene photodevice was fabricated by depositing Pd/Au and Ti/Au electrodes on single-layer graphene samples. When the polarization of incident laser beam is rotated with respect to the metal-graphene-metal junction, the photocurrent is significantly modulated. In addition, we measured the exact positions where the photocurrent is generated by measuring the photocurrent and Raman images of the graphene photodevices simultaneously.

  13. Photocurrent analysis of AgIn5S8 crystal

    Indian Academy of Sciences (India)

    Similarly, the dark current–voltage characteristics consisted of a single ... Photocurrent; spectral distribution; trapping; temperature dependence; .... powder was analysed by using XRD system (Rigaku Ultima- ... then drop and fill these holes.

  14. Nanoscale imaging of photocurrent enhancement by resonator array photovoltaic coatings

    Science.gov (United States)

    Ha, Dongheon; Yoon, Yohan; Zhitenev, Nikolai B.

    2018-04-01

    Nanoscale surface patterning commonly used to increase absorption of solar cells can adversely impact the open-circuit voltage due to increased surface area and recombination. Here, we demonstrate absorptivity and photocurrent enhancement using silicon dioxide (SiO2) nanosphere arrays on a gallium arsenide (GaAs) solar cell that do not require direct surface patterning. Due to the combined effects of thin-film interference and whispering gallery-like resonances within nanosphere arrays, there is more than 20% enhancement in both absorptivity and photocurrent. To determine the effect of the resonance coupling between nanospheres, we perform a scanning photocurrent microscopy based on a near-field scanning optical microscopy measurement and find a substantial local photocurrent enhancement. The nanosphere-based antireflection coating (ARC), made by the Meyer rod rolling technique, is a scalable and a room-temperature process; and, can replace the conventional thin-film-based ARCs requiring expensive high-temperature vacuum deposition.

  15. Limiting photocurrent analysis of a wide channel photoelectrochemical flow reactor

    International Nuclear Information System (INIS)

    Davis, Jonathan T; Esposito, Daniel V

    2017-01-01

    The development of efficient and scalable photoelectrochemical (PEC) reactors is of great importance for the eventual commercialization of solar fuels technology. In this study, we systematically explore the influence of convective mass transport and light intensity on the performance of a 3D-printed PEC flow cell reactor based on a wide channel, parallel plate geometry. Using this design, the limiting current density generated from the hydrogen evolution reaction at a p-Si metal–insulator–semiconductor (MIS) photocathode was investigated under varied reactant concentration, fluid velocity, and light intensity. Additionally, a simple model is introduced to predict the range of operating conditions (reactant concentration, light intensity, fluid velocity) for which the photocurrent generated in a parallel plate PEC flow cell is limited by light absorption or mass transport. This model can serve as a useful guide for the design and operation of wide-channel PEC flow reactors. The results of this study have important implications for PEC reactors operating in electrolytes with dilute reactant concentrations and/or under high light intensities where high fluid velocities are required in order to avoid operation in the mass transport-limited regime. (paper)

  16. The effect of acute hypoxia on short-circuit current and epithelial resistivity in biopsies from human colon.

    Science.gov (United States)

    Carra, Graciela E; Ibáñez, Jorge E; Saraví, Fernando D

    2013-09-01

    In isolated colonic mucosa, decreases in short-circuit current (ISC) and transepithelial resistivity (RTE) occur when hypoxia is either induced at both sides or only at the serosal side of the epithelium. We assessed in human colon biopsies the sensitivity to serosal-only hypoxia and mucosal-only hypoxia and whether Na, K-ATPase blockade with ouabain interacts with hypoxia. Biopsy material from patients undergoing colonoscopy was mounted in an Ussing chamber for small samples (1-mm2 window). In a series of experiments we assessed viability and the electrical response to the mucolytic, dithiothreitol (1 mmol/l). In a second series, we explored the effect of hypoxia without and with ouabain. In a third series, we evaluated the response to a cycle of hypoxia and reoxygenation induced at the serosal or mucosal side while keeping the oxygenation of the opposite side. 1st series: Dithiothreitol significantly decreased the unstirred layer and ISC but increased RTE. 2nd series: Both hypoxia and ouabain decreased ISC, but ouabain increased RTE and this effect on RTE prevailed even during hypoxia. 3rd series: Mucosal hypoxia caused lesser decreases of ISC and RTE than serosal hypoxia; in the former, but not in the latter, recovery was complete upon reoxygenation. In mucolytic concentration, dithiothreitol modifies ISC and RTE. Oxygen supply from the serosal side is more important to sustain ISC and RTE in biopsy samples. The different effect of hypoxia and Na, K-ATPase blockade on RTE suggests that their depressing effect on ISC involves different mechanisms.

  17. A multilayer electro-thermal model of pouch battery during normal discharge and internal short circuit process

    International Nuclear Information System (INIS)

    Chen, Mingbiao; Bai, Fanfei; Song, Wenji; Lv, Jie; Lin, Shili

    2017-01-01

    Highlights: • 2D network equivalent circuit considers the interplay of cell units. • The temperature non-uniformity Φ of multilayer model is bigger than that of lumped model. • The temperature non-uniformity is quantified and the reason of non-uniformity is analyzed. • Increasing the thermal conductivity of the separator can effectively relieve the heat spot effect of ISC. - Abstract: As the electrical and thermal characteristic will affect the batteries’ safety, performance, calendar life and capacity fading, an electro-thermal coupled model for pouch battery LiFePO_4/C is developed in normal discharge and internal short circuit process. The battery is discretized into many cell elements which are united as a 2D network equivalent circuit. The electro-thermal model is solved with finite difference method. Non-uniformity of current distribution and temperature distribution is simulated and the result is validated with experiment data at various discharge rates. Comparison of the lumped model and the multilayer structure model shows that the temperature non-uniformity Φ of multilayer model is bigger than that of lumped model and shows more precise. The temperature non-uniformity is quantified and the reason of non-uniformity is analyzed. The electro-thermal model can also be used to guide the safety design of battery. The temperature of the ISC element near tabs is the highest because the equivalent resistance of the external circuit (not including the ISC element) is the smallest when the resistance of cell units is small. It is found that increasing the thermal conductivity of integrated layer can effectively relieve the heat spot effect of ISC.

  18. Approximate entropy—a new statistic to quantify arc and welding process stability in short-circuiting gas metal arc welding

    International Nuclear Information System (INIS)

    Cao Biao; Xiang Yuanpeng; Lü Xiaoqing; Zeng Min; Huang Shisheng

    2008-01-01

    Based on the phase state reconstruction of welding current in short-circuiting gas metal arc welding using carbon dioxide as shielding gas, the approximate entropy of welding current as well as its standard deviation has been calculated and analysed to investigate their relation with the stability of electric arc and welding process. The extensive experimental and calculated results show that the approximate entropy of welding current is significantly and positively correlated with arc and welding process stability, whereas its standard deviation is correlated with them negatively. A larger approximate entropy and a smaller standard deviation imply a more stable arc and welding process, and vice versa. As a result, the approximate entropy of welding current promises well in assessing and quantifying the stability of electric arc and welding process in short-circuiting gas metal arc welding

  19. Increased short circuit current in organic photovoltaic using high-surface area electrode based on ZnO nanowires decorated with CdTe quantum dots.

    Science.gov (United States)

    Aga, R S; Gunther, D; Ueda, A; Pan, Z; Collins, W E; Mu, R; Singer, K D

    2009-11-18

    A photosensitized high-surface area transparent electrode has been employed to increase the short circuit current of a photovoltaic device with a blend of poly(3-hexylthiophene) (P3HT) and (6,6)-phenyl C61 butyric acid methyl ester (PCBM) as the active layer. This is achieved by directly growing ZnO nanowires on indium tin oxide (ITO) film via a physical vapor method. The nanowire surface is then decorated with CdTe quantum dots by pulsed electron-beam deposition (PED). The nanowires alone provided a 20-fold increase in the short circuit current under visible light illumination. This was further increased by a factor of approximately 1.5 by the photosensitization effect of CdTe, which has an optical absorption of up to 820 nm.

  20. Feasibility study of superconducting power cables for DC electric railway feeding systems in view of thermal condition at short circuit accident

    Science.gov (United States)

    Kumagai, Daisuke; Ohsaki, Hiroyuki; Tomita, Masaru

    2016-12-01

    A superconducting power cable has merits of a high power transmission capacity, transmission losses reduction, a compactness, etc., therefore, we have been studying the feasibility of applying superconducting power cables to DC electric railway feeding systems. However, a superconducting power cable is required to be cooled down and kept at a very low temperature, so it is important to reveal its thermal and cooling characteristics. In this study, electric circuit analysis models of the system and thermal analysis models of superconducting cables were constructed and the system behaviors were simulated. We analyzed the heat generation by a short circuit accident and transient temperature distribution of the cable to estimate the value of temperature rise and the time required from the accident. From these results, we discussed a feasibility of superconducting cables for DC electric railway feeding systems. The results showed that the short circuit accident had little impact on the thermal condition of a superconducting cable in the installed system.

  1. Inverted Fuel Cell: Room-Temperature Hydrogen Separation from an Exhaust Gas by Using a Commercial Short-Circuited PEM Fuel Cell without Applying any Electrical Voltage.

    Science.gov (United States)

    Friebe, Sebastian; Geppert, Benjamin; Caro, Jürgen

    2015-06-26

    A short-circuited PEM fuel cell with a Nafion membrane has been evaluated in the room-temperature separation of hydrogen from exhaust gas streams. The separated hydrogen can be recovered or consumed in an in situ olefin hydrogenation when the fuel cell is operated as catalytic membrane reactor. Without applying an outer electrical voltage, there is a continuous hydrogen flux from the higher to the lower hydrogen partial pressure side through the Nafion membrane. On the feed side of the Nafion membrane, hydrogen is catalytically split into protons and electrons by the Pt/C electrocatalyst. The protons diffuse through the Nafion membrane, the electrons follow the short-circuit between the two brass current collectors. On the cathode side, protons and electrons recombine, and hydrogen is released. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Analysis of the impact of connecting a larger number of small hydroelectric power plants to the short-circuit currents values and relay protection system of distribution network

    Directory of Open Access Journals (Sweden)

    Sučević Nikola

    2017-01-01

    Full Text Available In this paper the influence of a large number of small hydro power plants on the short-circuit currents is analysed, as well as the operation of the relay protection system within the real distribution network in Serbia. The necessary modification of the existing protection functions, as well as the implementation of the new proposed protection functions, are presented and discussed. Network modeling and analysis are performed using the program tool DIgSILENT PowerFactory.

  3. Internal short circuit and accelerated rate calorimetry tests of lithium-ion cells: Considerations for methane-air intrinsic safety and explosion proof/flameproof protection methods.

    Science.gov (United States)

    Dubaniewicz, Thomas H; DuCarme, Joseph P

    2016-09-01

    Researchers with the National Institute for Occupational Safety and Health (NIOSH) studied the potential for lithium-ion cell thermal runaway from an internal short circuit in equipment for use in underground coal mines. In this third phase of the study, researchers compared plastic wedge crush-induced internal short circuit tests of selected lithium-ion cells within methane (CH 4 )-air mixtures with accelerated rate calorimetry tests of similar cells. Plastic wedge crush test results with metal oxide lithium-ion cells extracted from intrinsically safe evaluated equipment were mixed, with one cell model igniting the chamber atmosphere while another cell model did not. The two cells models exhibited different internal short circuit behaviors. A lithium iron phosphate (LiFePO 4 ) cell model was tolerant to crush-induced internal short circuits within CH 4 -air, tested under manufacturer recommended charging conditions. Accelerating rate calorimetry tests with similar cells within a nitrogen purged 353-mL chamber produced ignitions that exceeded explosion proof and flameproof enclosure minimum internal pressure design criteria. Ignition pressures within a 20-L chamber with 6.5% CH 4 -air were relatively low, with much larger head space volume and less adiabatic test conditions. The literature indicates that sizeable lithium thionyl chloride (LiSOCl 2 ) primary (non rechargeable) cell ignitions can be especially violent and toxic. Because ignition of an explosive atmosphere is expected within explosion proof or flameproof enclosures, there is a need to consider the potential for an internal explosive atmosphere ignition in combination with a lithium or lithium-ion battery thermal runaway process, and the resulting effects on the enclosure.

  4. Radiation-Induced Prompt Photocurrents in Microelectronics Physics

    CERN Document Server

    Dodd, P E; Buller, D L; Doyle, B L; Vizkelethy, G; Walsh, D S

    2003-01-01

    The effects of photocurrents in nuclear weapons induced by proximal nuclear detonations are well known and remain a serious hostile environment threat for the US stockpile. This report describes the final results of an LDRD study of the physical phenomena underlying prompt photocurrents in microelectronic devices and circuits. The goals of this project were to obtain an improved understanding of these phenomena, and to incorporate improved models of photocurrent effects into simulation codes to assist designers in meeting hostile radiation requirements with minimum build and test cycles. We have also developed a new capability on the ion microbeam accelerator in Sandia's Ion Beam Materials Research Laboratory (the Transient Radiation Microscope, or TRM) to supply ionizing radiation in selected micro-regions of a device. The dose rates achieved in this new facility approach those possible with conventional large-scale dose-rate sources at Sandia such as HERMES III and Saturn. It is now possible to test the phy...

  5. Photocurrent extraction efficiency in colloidal quantum dot photovoltaics

    KAUST Repository

    Kemp, K. W.; Wong, C. T. O.; Hoogland, S. H.; Sargent, E. H.

    2013-01-01

    The efficiency of photocurrent extraction was studied directly inside operating Colloidal Quantum Dot (CQD) photovoltaic devices. A model was derived from first principles for a thin film p-n junction with a linearly spatially dependent electric field. Using this model, we were able to clarify the origins of recent improvement in CQD solar cell performance. From current-voltage diode characteristics under 1 sun conditions, we extracted transport lengths ranging from 39 nm to 86 nm for these materials. Characterization of the intensity dependence of photocurrent extraction revealed that the dominant loss mechanism limiting the transport length is trap-mediated recombination. © 2013 AIP Publishing LLC.

  6. Water quality, hydrology, and the effects of changes in phosphorus loading to Pike Lake, Washington County, Wisconsin, with special emphasis on inlet-to-outlet short-circuiting

    Science.gov (United States)

    Rose, William J.; Robertson, Dale M.; Mergener, Elizabeth A.

    2004-01-01

    Pike Lake is a 459-acre, mesotrophic to eutrophic dimictic lake in southeastern Wisconsin. Because of concern over degrading water quality in the lake associated with further development in its watershed, a study was conducted by the U.S. Geological Survey from 1998 to 2000 to describe the water quality and hydrology of the lake, quantify sources of phosphorus including the effects of short-circuiting of inflows, and determine how changes in phosphorus loading should affect the water quality of the lake. Measuring all significant water and phosphorus sources and estimating lesser sources was the method used to construct detailed water and phosphorus budgets. The Rubicon River, ungaged near-lake surface inflow, precipitation, and ground water provide 55, 20, 17, and 7 percent of the total inflow, respectively. Water leaves the lake through the Rubicon River outlet (87 percent) or by evaporation (13 percent). Total input of phosphorus to the lake was about 3,500 pounds in 1999 and 2,400 pounds in 2000. About 80 percent of the phosphorus was from the Rubicon River, about half of which came from the watershed and half from a waste-water treatment plant in Slinger, Wisconsin. Inlet-to-outlet short-circuiting of phosphorus is facilitated by a meandering segment of the Rubicon River channel through a marsh at the north end of the lake. It is estimated that 77 percent of phosphorus from the Rubicon River in monitoring year 1999 and 65 percent in monitoring year 2000 was short-circuited to the outlet without entering the main body of the lake.

  7. Fault clearance in medium-voltage networks using remote-monitored short-circuit alarms; Stoerungsbeseitigung im MS-Netz mit fernueberwachten Kurzschlussmeldern

    Energy Technology Data Exchange (ETDEWEB)

    Beran, B. [Reginalzentrum Neckar-Franken der EnBW Regional AG, Oehringen (Germany). Bereich Netzfuehrung; Deiss, R. [RBS Genius GmbH, Stuttgart (Germany). Bereich Korrosionsschutz und Gaslecksuche; Stibbe, T. [Phoenix Contact GmbH und Co KG, Blomberg (Lippe) (Germany). Vertrieb Deutschland

    2006-04-15

    In March 2005, a pilot project on remote monitoring of short-circuit alarms using GSM was started. In cooperation with RBS Genius GmbH (100 percent subsidiary of EnBW Regional AG) who already use a similar technology for controlling cathodic corrosion protection systems, and the EnBW-Regionalzentrum Neckar-Franken, the functionalities were specified. After only five months of development and assembly time, the first 15 units were installed in exposed and difficult-to-access sites. All sites were located along very long power lines in which localisation of the defect would be very time-consuming. (orig.)

  8. A Flexible Power Control Method of VSC-HVDC Link for the Enhancement of Effective Short-Circuit Ratio in a Hybrid Multi-Infeed HVDC System

    DEFF Research Database (Denmark)

    Liu, Yan; Chen, Zhe

    2013-01-01

    . To evaluate the contribution of the VSC-HVDC link on the voltage stability of HMIDC system, this paper proposes an effective short circuit ratio (ESCR) calculation method. Through the calculation, the voltage support capability of the VSC-HVDC link can be quantitatively represented by the ESCR. Furthermore......, based on the calculation results, a flexible power control strategy for the VSC-HVDC link is developed to provide maximum reactive power support under grid faults. The theoretical analysis of the HMIDC system is based on the Danish transmission grid, evaluated through PSCAD simulations under different...

  9. A study on the short-circuit test by fault angle control and the recovery characteristics of the fault current limiter using coated conductor

    International Nuclear Information System (INIS)

    Park, D.K.; Kim, Y.J.; Ahn, M.C.; Yang, S.E.; Seok, B.-Y.; Ko, T.K.

    2007-01-01

    Superconducting fault current limiters (SFCLs) have been developed in many countries, and they are expected to be used in the recent electric power systems, because of their great efficiency for operating these power system stably. It is necessary for resistive FCLs to generate resistance immediately and to have a fast recovery characteristic after the fault clearance, because of re-closing operation. Short-circuit tests are performed to obtained current limiting operational and recovery characteristics of the FCL by a fault controller using a power switching device. The power switching device consists of anti-parallel connected thyristors. The fault occurs at the desired angle by controlling the firing angle of thyristors. Resistive SFCLs have different current limiting characteristics with respect to the fault angle in the first swing during the fault. This study deals with the short-circuit characteristic of FCL coils using two different YBCO coated conductors (CCs), 344 and 344s, by controlling the fault angle and experimental studies on the recovery characteristic by a small current flowing through the SFCL after the fault clearance. Tests are performed at various voltages applied to the SFCL in a saturated liquid nitrogen cooling system

  10. Feasibility Study of the PS Injection for 2 GeV LIU Beams with an Upgraded KFA-45 Injection Kicker System Operating in Short Circuit Mode

    CERN Document Server

    Kramer, Thomas; Borburgh, Jan; Ducimetière, Laurent; Feliciano, Luis; Ferrero Colomo, Alvaro; Goddard, Brennan; Sermeus, Luc

    2016-01-01

    Under the scope of the LIU project the CERN PS Booster to PS beam transfer will be modified to match the requirements for the future 2 GeV beams. This paper describes the evaluation of the proposed upgrade of the PS injection kicker. Different schemes of an injection for LIU beams into the PS have been outlined in the past already under the aspect of individual transfer kicker rise and fall time performances. Homogeneous rise and fall time requirements in the whole PSB to PS transfer chain have been established which allowed to consider an upgrade option of the present injection kicker system operated in short circuit mode. The challenging pulse quality constraints require an improvement of the flat top and post pulse ripples. Both operation modes, terminated and short circuit mode are analysed and analogue circuit simulations for the present and upgraded system are outlined. Recent measurements on the installed kickers are presented and analysed together with the simulation data. First measurements verifying...

  11. Evolution of short circuit levels in the National Electric System, years 2007 to 2011; Evolucion de los niveles de cortocircuito del Sistema Electrico Nacional, anos 2007 al 2011

    Energy Technology Data Exchange (ETDEWEB)

    Quintana Castaneda, J; Reyes Escobedo, G [Instituto de Investigaciones Electricas (Mexico)]. E-mails: jqc@iie.org.mx; gustavo.reyes@iie.org.mx; Ibarra Romo, F.G. [Comision Federal de Electricidad (Mexico)]. E-mail: federico.ibarra@cfe.gob.mx

    2013-03-15

    The present document shows an analysis of 2011 short-circuit levels on the different nodes (substations) that integrate the National Electric System. This analysis presents the figures of short-circuit levels on past years, stating on 2007, with the purpose of detecting the variation on each one of these nodes and identify the cases that because it's high levels are considered as critical nodes of the transmission system. At the end of the analysis some recommendations to minimize the potential risks are given on those substations classified as critical nodes. [Spanish] En este documento se expone un analisis de los niveles de cortocircuito que se presentaron en el 2011 en los distintos nodos (subestaciones) que conforman la red del Sistema Electrico Nacional (SEN). Este analisis muestra las cifras de los niveles de cortocircuito que se han presentado desde el ano 2007, a fin de estudiar el comportamiento y evolucion que han tenido los nodos de la red electrica, identificando aquellos puntos que por sus altos niveles de cortocircuito se consideran como nodos criticos. En la parte final del analisis se dan algunas recomendaciones para disminuir los riesgos que se pudieran presentar en aquellas subestaciones clasificadas como nodos criticos.

  12. Adrenomedullin increases the short-circuit current in the rat prostate: Receptors, chloride channels, the effects of cAMP and calcium ions and implications on fluid secretion.

    Science.gov (United States)

    Liao, S B; Cheung, K H; Cheung, M P L; Wong, P F; O, W S; Tang, F

    2014-05-01

    In this study, we have investigated the effects of adrenomedullin on chloride and fluid secretion in the rat prostate. The presence of adrenomedullin (ADM) in rat prostate was confirmed using immunostaining, and the molecular species was determined using gel filtration chromatography coupled with an enzyme-linked assay for ADM. The effects of ADM on fluid secretion were studied by short-circuit current technique in a whole mount preparation of the prostate in an Ussing chamber. The results indicated that the ADM level was higher in the ventral than the dorso-lateral prostate and the major molecular species was the active peptide. ADM increased the short-circuit current through both the cAMP- and calcium-activated chloride channels in the ventral lobe, but only through the calcium-activated channels in the dorso-lateral lobe. These stimulatory effects were blocked by the calcitonin gene-related peptide (CGRP) receptor antagonist, hCGRP8-37. We conclude that ADM may regulate prostatic fluid secretion through the chloride channels, which may affect the composition of the seminal plasma bathing the spermatozoa and hence fertility. © 2014 American Society of Andrology and European Academy of Andrology.

  13. Influence of Metal Transfer Stability and Shielding Gas Composition on CO and CO2 Emissions during Short-circuiting MIG/MAG Welding

    Directory of Open Access Journals (Sweden)

    Valter Alves de Meneses

    Full Text Available Abstract: Several studies have demonstrated the influence of parameters and shielding gas on metal transfer stability or on the generation of fumes in MIG/MAG welding, but little or nothing has been discussed regarding the emission of toxic and asphyxiating gases, particularly as it pertains to parameterization of the process. The purpose of this study was to analyze and evaluate the effect of manufacturing aspects of welding processes (short-circuit metal transfer stability and shielding gas composition on the gas emission levels during MIG/MAG welding (occupational health and environmental aspects. Using mixtures of Argon with CO2 and O2 and maintaining the same average current and the same weld bead volume, short-circuit welding was performed with carbon steel welding wire in open (welder’s breathing zone and confined environments. The welding voltage was adjusted to gradually vary the transfer stability. It was found that the richer the composition of the shielding gas is in CO2, the more CO and CO2 are generated by the arc. However, unlike fume emission, voltage and transfer stability had no effect on the generation of these gases. It was also found that despite the large quantity of CO and CO2 emitted by the arc, especially when using pure CO2 shielding gas, there was no high level residual concentration of CO and CO2 in or near the worker’s breathing zone, even in confined work cells.

  14. Detecting the single line to ground short circuit fault in the submarine’s power system using the artificial neural network

    Directory of Open Access Journals (Sweden)

    Behniafar Ali

    2013-01-01

    Full Text Available The electric marine instruments are newly inserted in the trade and industry, for which the existence of an equipped and reliable power system is necessitated. One of the features of such a power system is that it cannot have an earth system causing the protection relays not to be able to detect the single line to ground short circuit fault. While on the other hand, the occurrence of another similar fault at the same time can lead to the double line fault and thereby the tripping of relays and shortening of vital loads. This in turn endangers the personals' security and causes the loss of military plans. From the above considerations, it is inferred that detecting the single line to ground fault in the marine instruments is of a special importance. In this way, this paper intends to detect the single line to ground fault in the power systems of the marine instruments using the wavelet transform and Multi-Layer Perceptron (MLP neural network. In the numerical analysis, several different types of short circuit faults are simulated on several marine power systems and the proposed approach is applied to detect the single line to ground fault. The results are of a high quality and preciseness and perfectly demonstrate the effectiveness of the proposed approach.

  15. Controlling Blend Morphology for Ultra-High Current Density in Non-Fullerene Acceptor Based Organic Solar Cells

    KAUST Repository

    Song, Xin; Gasparini, Nicola; Ye, Long; Yao, Huifeng; Hou, Jianhui; Ade, Harald; Baran, Derya

    2018-01-01

    Due to the high absorption coefficient and modulated band gap of non-fullerene small molecule acceptors (NFAs), photons can be utilized more efficiently in near-infrared (NIR) range. In this report, we highlight a system with a well-known polymer donor (PTB7-Th) blended with a narrow bandgap non-fullerene acceptor (IEICO-4F) as active layer and 1-chloronaphthalene (CN) as the solvent additive. The optimization of the photoactive layer nanomorphology yields short-circuit current density value (Jsc) of 27.3 mA/cm2, one of the highest value in OSCs reported to date, which competes with other types of solution processed solar cells such as perovskite or quantum dot devices. Along with decent open-circuit voltage (0.71V) and fill factor values (66%), a power conversion efficiency of 12.8% is achieved for the champion devices. Grazing incidence wide-angle X-ray scattering (GIWAXS) patterns and resonant soft X-ray scattering (R-SoXS) elucidate that the origin of this high photocurrent is mainly due to increased π-π coherence length of the acceptor, the domain spacing as well as the mean-square composition variation of the blend. Optoelectronic measurements confirm a balanced hole and electron mobility and reduced trap-assisted recombination for the best devices. These findings unveil the relevant solvent processing-nanostructure-electronic properties correlation in low band gap non-fullerene based solar cells, which provide a helpful guide for maximizing photocurrent that can pave the way for high efficiency organic solar cells.

  16. Controlling Blend Morphology for Ultra-High Current Density in Non-Fullerene Acceptor Based Organic Solar Cells

    KAUST Repository

    Song, Xin

    2018-01-23

    Due to the high absorption coefficient and modulated band gap of non-fullerene small molecule acceptors (NFAs), photons can be utilized more efficiently in near-infrared (NIR) range. In this report, we highlight a system with a well-known polymer donor (PTB7-Th) blended with a narrow bandgap non-fullerene acceptor (IEICO-4F) as active layer and 1-chloronaphthalene (CN) as the solvent additive. The optimization of the photoactive layer nanomorphology yields short-circuit current density value (Jsc) of 27.3 mA/cm2, one of the highest value in OSCs reported to date, which competes with other types of solution processed solar cells such as perovskite or quantum dot devices. Along with decent open-circuit voltage (0.71V) and fill factor values (66%), a power conversion efficiency of 12.8% is achieved for the champion devices. Grazing incidence wide-angle X-ray scattering (GIWAXS) patterns and resonant soft X-ray scattering (R-SoXS) elucidate that the origin of this high photocurrent is mainly due to increased π-π coherence length of the acceptor, the domain spacing as well as the mean-square composition variation of the blend. Optoelectronic measurements confirm a balanced hole and electron mobility and reduced trap-assisted recombination for the best devices. These findings unveil the relevant solvent processing-nanostructure-electronic properties correlation in low band gap non-fullerene based solar cells, which provide a helpful guide for maximizing photocurrent that can pave the way for high efficiency organic solar cells.

  17. Estimation of carrier leakage in InGaN light emitting diodes from photocurrent measurements

    Science.gov (United States)

    Hafiz, Shopan; Zhang, Fan; Monavarian, Morteza; Okur, Serdal; Avrutin, Vitaliy; Morkoç, Hadis; Özgür, Ümit

    2014-02-01

    Carrier transport in double heterostructure (DH) InGaN light emitting diodes (LEDs) was investigated using photocurrent measurements performed under CW HeCd laser (325 nm wavelength) excitation. The effect of electron injector thicknesses was investigated by monitoring the excitation density and applied bias dependent escape of photogenerated carriers from the active region and through energy band structure and carrier transport simulations using Silvaco Atlas. For quad (4x) 3-nm DH LED structures incorporating staircase electron injectors (SEIs), photocurrent increased with SEI thickness due to reduced effective barrier opposing carrier escape from the active region as confirmed by simulations. The carrier leakage percentile at -3V bias and 280 Wcm-2 optical excitation density increased from 24 % to 55 % when In 0.04Ga0.96N + In0.08Ga0.92N SEI thickness was increased from 4 nm + 4 nm to 30 nm + 30 nm. The increased leakage with thicker SEI correlates with increased carrier overflow under forward bias.

  18. SPIN-POLARIZED PHOTOCURRENT THROUGH QUANTUM DOT PHOTODETECTOR

    Directory of Open Access Journals (Sweden)

    Nguyen Van Hieu

    2017-11-01

    Full Text Available The theory of the photocurrent through the photodetector based on a two-level semiconductor quantum dot (QD is presented. The analytical expressions of the matrix elements of the electronic transitions generated by the absorption of the circularly polarized photons are derived in the lowest order of the perturbation theory with respect to the electron tunneling interaction as well as the electron-photon interaction. From these expressions the mechanism of the generation of the spin-polarized of electrons in the photocurrent is evident. It follows that the photodetector based on the two-level semiconductor QD can be used as the model of a source of highly spinpolarized electrons.

  19. {Ni4O4} Cluster Complex to Enhance the Reductive Photocurrent Response on Silicon Nanowire Photocathodes

    Directory of Open Access Journals (Sweden)

    Yatin J. Mange

    2017-02-01

    Full Text Available Metal organic {Ni4O4} clusters, known oxidation catalysts, have been shown to provide a valuable route in increasing the photocurrent response on silicon nanowire (SiNW photocathodes. {Ni4O4} clusters have been paired with SiNWs to form a new photocathode composite for water splitting. Under AM1.5 conditions, the combination of {Ni4O4} clusters with SiNWs gave a current density of −16 mA/cm2, which corresponds to an increase in current density of 60% when compared to bare SiNWs. The composite electrode was fully characterised and shown to be an efficient and stable photocathode for water splitting.

  20. Photocurrent and photovoltage induced in a 2DEG under intense, pulsed THz radiation

    International Nuclear Information System (INIS)

    Lewis, R.A.; Xu, W.; Pellemans, H.P.M.; Langerak, C.J.G.M.

    1999-01-01

    Full text: Intense THz radiation emitted by FELIX (Free Electron Laser for Infrared eXperiments) induces both photovoltage and photocurrent signals in a high-mobility (μ = 2 x 10 6 cm 2 /V s), low-density (n e = 2 x 10 11 cm -2 ) GaAs/AlGaAs-based 2DEG. Within the ∼5 μs FELIX macropulse, there is a rapid response in the longitudinal voltage of a Hall-bar sample, reproducible between pulses. A large response continues well after the pulse; this long-time-scale behaviour varies between pulses if the current exceeds a critical value (which decreases with radiation intensity and magnetic field). Within the macropulse, the photovoltage varies with magnetic field, saturating at low field (<100 mT). The photocurrent shows a rapid, non-resonant response, evident at integral filling factors in both longitudinal and transverse data, and a slower, cyclotron resonant response, peaking at ∼390 μs after the FELIX pulse. No anisotropy in the resistivity under polarised radiation was found

  1. Design and flight performance evaluation of the Mariners 6, 7, and 9 short-circuit current, open-circuit voltage transducers

    Science.gov (United States)

    Patterson, R. E.

    1973-01-01

    The purpose of the short-circuit voltage transducer is to provide engineering data to aid the evaluation of array performance during flight. The design, fabrication, calibration, and in-flight performance of the transducers onboard the Mariner 6, 7 and 9 spacecrafts are described. No significant differences were observed in the in-flight electrical performance of the three transducers. The transducers did experience significant losses due to coverslides or adhesive darkening, increased surface reflection, or spectral shifts within coverslide assembly. Mariner 6, 7 and 9 transducers showed non-cell current degradations of 3-1/2%, 3%, and 4%, respectively at Mars encounter and 6%, 3%, and 4-12%, respectively at end of mission. Mariner 9 solar Array Test 2 showed 3-12% current degradation while the transducer showed 4-12% degradation.

  2. Size optimization for complex permeability measurement of magnetic thin films using a short-circuited microstrip line up to 30 GHz

    Science.gov (United States)

    Takeda, Shigeru; Naoe, Masayuki

    2018-03-01

    High-frequency permeability spectra of magnetic films were measured over a wideband frequency range of 0.1-30 GHz using a shielded and short-circuited microstrip line jig. In this measurement, spurious resonances had to be suppressed up to the highest frequency. To suppress these resonances, characteristic impedance of the microstrip line should approach 50 Ω at the junction between connector and microstrip line. The main factors dominating these resonances were structures of the jig and the sample. The dimensions were optimized in various experiments, and results demonstrated that the frequency could be raised to at least 20 GHz. For the transverse electromagnetic mode to transmit stably along the microstrip line, the preferred sample was rectangular, with the shorter side parallel to the line and the longer side perpendicular to it, and characteristic impedance strongly depended on the signal line width of the jig. However, too small a jig and sample led to a lower S/N ratio.

  3. An Icepak-PSpice Co-Simulation Method to Study the Impact of Bond Wires Fatigue on the Current and Temperature Distribution of IGBT Modules under Short-Circuit

    DEFF Research Database (Denmark)

    Wu, Rui; Iannuzzo, Francesco; Wang, Huai

    2014-01-01

    Bond wires fatigue is one of the dominant failure mechanisms of IGBT modules. Prior-art research mainly focuses on its impact on the end-of-life failure, while its effect on the short-circuit capability of IGBT modules is still an open issue. This paper proposes a new electro-thermal simulation...... approach enabling analyze the impact of the bond wires fatigue on the current and temperature distribution on IGBT chip surface under short-circuit. It is based on an Icepack-PSpice co-simulation by taking the advantage of both a finite element thermal model and an advanced PSpice-based multi-cell IGBT...

  4. Micropatterned Carbon-on-Quartz Electrode Chips for Photocurrent Generation from Thylakoid Membranes

    DEFF Research Database (Denmark)

    Bunea, Ada-Ioana; Heiskanen, Arto R.; Pankratova, Galina

    2018-01-01

    Harvesting the energy generated by photosynthetic organisms through light-dependent reactions is a significant step towards a sustainable future energy supply. Thylakoid membranes are the site of photosynthesis, and thus particularly suited for developing photo-bioelectrochemical cells. Novel ele......]+/2+) are used for evaluating photocurrent generation from thylakoid membranes with different electrode geometries. Current densities up to 71 µA cm-2 are measured upon illumination through the transparent electrode chip with solar simulated irradiance (1000 W m-2)....... electrode materials and geometries could potentially improve the efficiency of energy harvesting using thylakoid membranes. For commercial applications, electrodes with large surface areas are needed. Photolithographic patterning of a photoresist, followed by pyrolysis, is a flexible and fast approach...

  5. Experimental Study on Short Circuit Phenomena in Air Switch of Distribution Line due to Sparkover between Different Poles on Which One Surge Arrester of the Three Ones is Omitted

    Science.gov (United States)

    Sato, Tomoyuki; Uemura, Satoshi; Asakawa, Akira; Yokoyama, Shigeru; Honda, Hideki; Horikoshi, Kazuhiro

    In this study, we experimentally examined the possibility of the internal short circuit of an air switch due to the sparkover between different poles under the condition that no surge arrester exists in neighboring poles and one of three surge arresters is omitted at the pole with an air switch. Experiments at Shiobara Testing Yard and Akagi Testing Center of CRIEPI clarified the following. Fault current may flow via the grounding point of a pole with an air switch and that of the next pole on a different phase from grounded phase of the pole with an air switch. If the low-voltage wire, overhead ground wire or communication wire forms a short circuit between them, ultimately the air switch may burn out. Moreover Fault current continues even if the length of the short-circuit between different poles is increased. Although the increase of the short-circuit length results in the increase of wire impedance, the amount of increase is still small compared with source impedance.

  6. Investigation on the Short-Circuit Behavior of an Aged IGBT Module Through a 6 kA/1.1 kV Non-Destructive Testing Equipment

    DEFF Research Database (Denmark)

    Wu, Rui; Smirnova, Liudmila; Iannuzzo, Francesco

    2014-01-01

    This paper describes the design and development of a 6 kA/1.1 kV non-destructive testing system, which aims for short circuit testing of high-power IGBT modules. An ultralow stray inductance of 37 nH is achieved in the implementation of the tester. An 100 MHz FPGA supervising unit enables 10 ns...

  7. Experimental and theoretical investigations of photocurrents in non-centrosymmetric semiconductor quantum wells

    Energy Technology Data Exchange (ETDEWEB)

    Duc, Huynh Thanh; Foerstner, Jens; Meier, Torsten [Department of Physics and CeOPP, University Paderborn (Germany); Priyadarshi, Shekar; Racu, Ana Maria; Pierz, Klaus; Siegner, Uwe; Bieler, Mark [Physikalisch-Technische Bundesanstalt, Braunschweig (Germany)

    2010-07-01

    We compute photocurrents generated by femtosecond single-color laser pulses in non-centrosymmetric semiconductor quantum wells by combining a 14 x 14 k.p band structure theory with multi-band semiconductor Bloch equations. The transient photocurrents are investigated experimentally by measuring the associated Terahertz emission. The dependencies of the photocurrent and the Terahertz emission on the excitation conditions are discussed for (110)-oriented GaAs quantum wells. The comparison between theory and experiment shows a good agreement.

  8. The short-circuit test results of 6.9 kV/2.3 kV 400 kVA-class YBCO model transformer with fault current limiting function

    International Nuclear Information System (INIS)

    Tomioka, A.; Bohno, T.; Kakami, S.; Isozaki, M.; Watanabe, K.; Toyama, K.; Sugiyama, S.; Konno, M.; Gosho, Y.; Okamoto, H.; Hayashi, H.; Tsutsumi, T.; Iwakuma, M.; Saito, T.; Tanabe, K.; Shiohara, Y.

    2013-01-01

    Highlights: ► We manufactured the 400 kV A-class YBCO model transformer with FCL function. ► Short-circuit test was performed by applying 6.9 kV on primary side. ► The short-circuit current was limited to 174 A for a prospective current of 559 A. ► It agreed with the design and we also confirmed the I c did not degrade. ► The results suggest the possibility to design YBCO transformers with FCL function. -- Abstract: We are developing an elemental technology for 66/6.9 kV 20 MVA-class superconducting power transformer with fault current limiting function. In order to obtain the characteristics of YBCO conductor when the AC over current supplied to the conductor, the model coils were manufactured with YBCO tapes and tested. Based on these results, we manufactured the 6.9 kV/2.3 kV 400 kVA-class YBCO model transformer with fault current limiting function and performed short-circuit test. At the 0.25 s after short-circuit, the short-circuit current of primary winding was limited to about 174 A for a prospective current of 559 A. It was consistent with the design. The I–V characteristics of the winding did not change before and after the test. We consider the model transformer to be able to withstand AC over-current with the function of current limiting. The results suggest the possibility to design YBCO superconducting transformers with fault current limiting function for practical power grid

  9. Back-reactions, short-circuits, leaks and other energy wasteful reactions in biological electron transfer: redox tuning to survive life in O(2).

    Science.gov (United States)

    Rutherford, A William; Osyczka, Artur; Rappaport, Fabrice

    2012-03-09

    The energy-converting redox enzymes perform productive reactions efficiently despite the involvement of high energy intermediates in their catalytic cycles. This is achieved by kinetic control: with forward reactions being faster than competing, energy-wasteful reactions. This requires appropriate cofactor spacing, driving forces and reorganizational energies. These features evolved in ancestral enzymes in a low O(2) environment. When O(2) appeared, energy-converting enzymes had to deal with its troublesome chemistry. Various protective mechanisms duly evolved that are not directly related to the enzymes' principal redox roles. These protective mechanisms involve fine-tuning of reduction potentials, switching of pathways and the use of short circuits, back-reactions and side-paths, all of which compromise efficiency. This energetic loss is worth it since it minimises damage from reactive derivatives of O(2) and thus gives the organism a better chance of survival. We examine photosynthetic reaction centres, bc(1) and b(6)f complexes from this view point. In particular, the evolution of the heterodimeric PSI from its homodimeric ancestors is explained as providing a protective back-reaction pathway. This "sacrifice-of-efficiency-for-protection" concept should be generally applicable to bioenergetic enzymes in aerobic environments. Copyright © 2012 Federation of European Biochemical Societies. All rights reserved.

  10. Extra high speed modified Lundell alternator parameters and open/short-circuit characteristics from global 3D-FE magnetic field solutions

    Science.gov (United States)

    Wang, R.; Demerdash, N. A.

    1992-06-01

    The combined magnetic vector potential - magnetic scalar potential method of computation of 3D magnetic fields by finite elements, introduced in a companion paper, is used for global 3D field analysis and machine performance computations under open-circuit and short-circuit conditions for an example 14.3 kVA modified Lundell alternator, whose magnetic field is of intrinsic 3D nature. The computed voltages and currents under these machine test conditions were verified and found to be in very good agreement with corresponding test data. Results of use of this modelling and computation method in the study of a design alteration example, in which the stator stack length of the example alternator is stretched in order to increase voltage and volt-ampere rating, are given here. These results demonstrate the inadequacy of conventional 2D-based design concepts and the imperative of use of this type of 3D magnetic field modelling in the design and investigation of such machines.

  11. Asbestos as 'toxic short-circuit' optic-fibre for UV within the cell-net: — Likely roles and hazards for secret UV and IR metabolism

    International Nuclear Information System (INIS)

    Traill, Robert R

    2011-01-01

    The most toxic asbestos fibres have widths 250nm-10nm, and this toxicity is 'physical', which could mean either mechanical or optical: Tangling with chromosomes is a mechanical hazard occasionally reported, and fibres 100nm wide — or chrysotile (white asbestos) is >150nm. In both cases, UV A /UV B -transmission would then predominate. (Chrysotile 150nm might be benign — escaping both mechanical and optical!). But what would generate such UV, and why would its transmission be toxic? Thar and Kühl (J.Theor.Biol.:2004) explain that the long mitochondria on microtubules may be able to act as UV-lasers, (and many observers since Gurwitsch 1923 have reported ultraweak UV emissions escaping from all types of living bio-tissue). That all suggests some universal secret role for UV, apparently related to mitosis. Insertion of fibre 'short-circuits' could then cause upsets in mitosis-control, and hence DNA irregularities. Such UV-control could parallel similar lower-powered Infra-Red control-systems (as considered elsewhere for coaxial myelin; or as portrayed by G.Albrecht-Buehler's online animations etc.); and the traditional short mitochondria seem better suited for this IR task.

  12. Effects of tetrodotoxin and ion replacements on the short-circuit current induced by Escherichiacoli heat stable enterotoxin across small intestine of the gerbil (Gerbillus cheesmani

    Directory of Open Access Journals (Sweden)

    Fawzia Yaqoub Al-Balool

    2004-03-01

    Full Text Available The effects of mucosally added Escherichia coli heat stable enterotoxin (STa 30 ng ml-1 on the basal short-circuit current (Isc in µA cm-2 across stripped and unstripped sheets of jejuna and ilea taken from fed, starved (4 days, water ad lib and undernourished (50% control food intake for 21 days gerbil (Gerbillus cheesmani were investigated. The effect of neurotoxin tetrodotoxin (TTX 10 µM and the effects of replacing chloride by gluconate or the effects of removing bicarbonate from bathing buffers on the maximum increase in Isc induced by STa were also investigated. The maximum increase in Isc which resulted from the addition of STa were significantly higher in jejuna and ilea taken from starved and undernourished gerbils when compared with the fed control both using stripped and unstripped sheets. In the two regions of the small intestine taken from fed and starved animals TTX reduced the maximum increase in Isc induced by STa across unstripped sheets only. Moreover in jejuna and ilea taken from undernourished gerbils TTX reduced significantly the maximum increase in Isc induced by STa across stripped and unstripped sheets. Replacing chloride by gluconate decreased the maximum increase in Isc induced by STa across jejuna and ilea taken from undernourished gerbils only. Removing bicarbonates from bathing buffer decreased the maximum increase in Isc across the jejuna and ilea taken from starved and undernourished gerbils.

  13. The short circuit current improvement in P3HT:PCBM based polymer solar cell by introducing PSBTBT as additional electron donor.

    Science.gov (United States)

    Sun, Lu; Shen, Liang; Mengd, Fanxu; Xu, Peng; Guo, Wenbin; Ruan, Shengping

    2014-05-01

    Here we demonstrate the influence of electron-donating polymer addition on the performance of poly(3-hexylthiophene) (P3HT):1 -(3-methoxycarbonyl)-propyl-1-phenyl-(6,6) C61 (PCBM) solar cells. Poly[(4,42-bis(2-ethylhexyl) dithieno [3,2-b:22,32-d] silole)-2,6-diylalt-(2,1,3-benzothiadiazole)-4,7-diyl] (PSBTBT) was chosen as the electron-donating polymer to improve the short circuit current (J(sc)) due to its distinct absorption in the near-IR range and similar HOMO level with that of P3HT. In the study, we found that J(sc) was improved for ternary blend (P3HT:PSBTBT:PCBM) solar cells. The dependence of device performance was investigated. J(sc) got decreased with increasing the ratio of PSBTBT. Result showed that J(sc) of ternary blend solar cells was improved greatly after thermal annealing at 150 degrees C, close to that of the binary blend (PSBTBT:PCBM) solar cells.

  14. Robust Diagnosis Method Based on Parameter Estimation for an Interturn Short-Circuit Fault in Multipole PMSM under High-Speed Operation.

    Science.gov (United States)

    Lee, Jewon; Moon, Seokbae; Jeong, Hyeyun; Kim, Sang Woo

    2015-11-20

    This paper proposes a diagnosis method for a multipole permanent magnet synchronous motor (PMSM) under an interturn short circuit fault. Previous works in this area have suffered from the uncertainties of the PMSM parameters, which can lead to misdiagnosis. The proposed method estimates the q-axis inductance (Lq) of the faulty PMSM to solve this problem. The proposed method also estimates the faulty phase and the value of G, which serves as an index of the severity of the fault. The q-axis current is used to estimate the faulty phase, the values of G and Lq. For this reason, two open-loop observers and an optimization method based on a particle-swarm are implemented. The q-axis current of a healthy PMSM is estimated by the open-loop observer with the parameters of a healthy PMSM. The Lq estimation significantly compensates for the estimation errors in high-speed operation. The experimental results demonstrate that the proposed method can estimate the faulty phase, G, and Lq besides exhibiting robustness against parameter uncertainties.

  15. Extra high speed modified Lundell alternator parameters and open/short-circuit characteristics from global 3D-FE magnetic field solutions

    Science.gov (United States)

    Wang, R.; Demerdash, N. A.

    1992-01-01

    The combined magnetic vector potential - magnetic scalar potential method of computation of 3D magnetic fields by finite elements, introduced in a companion paper, is used for global 3D field analysis and machine performance computations under open-circuit and short-circuit conditions for an example 14.3 kVA modified Lundell alternator, whose magnetic field is of intrinsic 3D nature. The computed voltages and currents under these machine test conditions were verified and found to be in very good agreement with corresponding test data. Results of use of this modelling and computation method in the study of a design alteration example, in which the stator stack length of the example alternator is stretched in order to increase voltage and volt-ampere rating, are given here. These results demonstrate the inadequacy of conventional 2D-based design concepts and the imperative of use of this type of 3D magnetic field modelling in the design and investigation of such machines.

  16. Ultrafast photocurrents in monolayer MoS2

    Science.gov (United States)

    Parzinger, Eric; Wurstbauer, Ursula; Holleitner, Alexander W.

    Two-dimensional transition metal dichalcogenides such as MoS2 have emerged as interesting materials for optoelectronic devices. In particular, the ultrafast dynamics and lifetimes of photoexcited charge carriers have attracted great interest during the last years. We investigate the photocurrent response of monolayer MoS2 on a picosecond time scale utilizing a recently developed pump-probe spectroscopy technique based on coplanar striplines. We discuss the ultrafast dynamics within MoS2 including photo-thermoelectric currents and the impact of built-in fields due to Schottky barriers as well as the Fermi level pinning at the contact region. We acknowledge support by the ERC via Project 'NanoREAL', the DFG via excellence cluster 'Nanosystems Initiative Munich' (NIM), and through the TUM International Graduate School of Science and Engineering (IGSSE) and BaCaTeC.

  17. Femtosecond upconverted photocurrent spectroscopy of InAs quantum nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Yamada, Yasuhiro [Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011 (Japan); Tex, David M.; Kanemitsu, Yoshihiko, E-mail: kanemitu@scl.kyoto-u.ac.jp [Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011 (Japan); Japan Science and Technology Agency, CREST, Kyoto University, Uji, Kyoto 611-0011 (Japan); Kamiya, Itaru [Toyota Technological Institute, Nagoya, Aichi 468-8511 (Japan)

    2015-07-06

    The carrier upconversion dynamics in InAs quantum nanostructures are studied for intermediate-band solar-cell applications via ultrafast photoluminescence and photocurrent (PC) spectroscopy based on femtosecond excitation correlation (FEC) techniques. Strong upconverted PC-FEC signals are observed under resonant excitation of quantum well islands (QWIs), which are a few monolayer-thick InAs quantum nanostructures. The PC-FEC signal typically decays within a few hundred picoseconds at room temperature, which corresponds to the carrier lifetime in QWIs. The photoexcited electron and hole lifetimes in InAs QWIs are evaluated as functions of temperature and laser fluence. Our results provide solid evidence for electron–hole–hole Auger process, dominating the carrier upconversion in InAs QWIs at room temperature.

  18. New Circuits or Short Circuits?

    Science.gov (United States)

    McLaughlin, Frank

    1967-01-01

    Schools must refuse to contribute to this age of "information overload" and, through an interdisciplinary approach, assist students to become receptive to humane feelings and to understand the complexities of a culture. To these ends, educators must "re-program" the entire educational system by relinquishing their attachment to their own…

  19. Electrospun photosensitive nanofibers: potential for photocurrent therapy in skin regeneration.

    Science.gov (United States)

    Jin, Guorui; Prabhakaran, Molamma P; Kai, Dan; Kotaki, Masaya; Ramakrishna, Seeram

    2013-01-01

    Poly(3-hexylthiophene) (P3HT) is one of the most promising photovoltaic (PV) polymers in photocurrent therapy. A novel photosensitive scaffold for skin tissue engineering was fabricated by blending P3HT with polycaprolactone (PCL) and electrospun to obtain composite PCL/P3HT nanofibers with three different weight ratios of PCL : P3HT (w/w) of 150 : 2 [PCL/P3HT(2)], 150 : 10 [PCL/P3HT(10)] and 150 : 20 [PCL/P3HT(20)]. The photosensitive properties of the blend solutions and the composite nanofibers of PCL/P3HT were investigated. The incident photon-to-electron conversion efficiencies of the PCL/P3HT(2), PCL/P3HT(10), PCL/P3HT(20) were identified as 2.0 × 10(-6), 1.6 × 10(-5) and 2.9 × 10(-5), respectively, which confirm the photosensitive ability of the P3HT-containing scaffolds. The biocompatibility of the scaffold was evaluated by culturing human dermal fibroblasts and the results showed that the proliferation of HDFs under light stimulation on PCL/P3HT(10) was 12.8%, 11.9%, and 11.6% (p ≤ 0.05) higher than the cell growth on PCL, PCL/P3HT(2) and PCL/P3HT(20), respectively. Human dermal fibroblasts cultured under light stimulation on PCL/P3HT(10) not only showed better cell proliferation but also retained cell morphology similar to the phenotype observed on tissue culture plates (control). Our experimental results suggest novel and potential application of an optimized amount of P3HT-containing scaffold, especially PCL/P3HT(10) nanofibrous scaffold in photocurrent therapy for skin regeneration.

  20. Application of Photocurrent Model on Polymer Solar Cells Under Forward Bias Stress

    DEFF Research Database (Denmark)

    Rizzo, Antonio; Torto, Lorenzo; Wrachien, Nicola

    2017-01-01

    We performed a constant current stress at forward bias on organic heterojunction solar cells. We measured current voltage curves in both dark and light at each stress step to calculate the photocurrent. An existing model applied to photocurrent experimental data allows the estimation of several...

  1. Effects of arginine vasotocin and mesotocin on the activation and development of amiloride-blockable short-circuit current across larval, adult, and cultured larval bullfrog skins.

    Science.gov (United States)

    Takada, Makoto; Fujimaki-Aoba, Kayo; Hokari, Shigeru

    2010-03-01

    Amphibian skin has osmoregulatory functions, with Na(+) crossing from outside to inside. Na(+) transport can be measured as the short-circuit current (SCC). We investigated the short-term and long-term effects of arginine vasotocin (AVT) and mesotocin (MT) (which modulate Na(+) transport) on the activation and development of an amiloride-blockable SCC (adult-type feature) in larval, adult, and corticoid-cultured larval bullfrog skins. We found: (1) AVT-receptor (AVT-R) and MT-receptor (MT-R) mRNAs could be detected in both larval and adult skins, (2) in the short term (within 60 min), the larval SCC (amiloride-stimulated SCC) was increased by AVT, forskolin, and MT, suggesting that AVT and MT did not activate the inactive ENaC (epithelial sodium channel) protein thought to be expressed in larval skin, (3) in the short term (within 90 min), AVT, forskolin, and MT stimulated the adult SCC (amiloride-blockable SCC), (4) AVT and MT increased both the larval and adult SCC via receptors insensitive to OPC-21268 (an antagonist of the V(1)-type receptor), OPC-31260 (an antagonist of the V(2)-type receptor), and ([d(CH(2))(5),Tyr(Me)(2),Thr(4),Orn(8),des-Gly-NH (2) (9) ]VT) (an antagonist of the oxytocin receptor), (5) culturing EDTA-treated larval skin with corticoids supplemented with AVT (1 microM) or MT (1 microM) for 2 weeks (long-term effects of AVT and MT) did not alter the corticoid-induced development of an amiloride-blockable SCC (adult-type feature). AVT and MT thus have the potential to stimulate SCC though channels that are already expressed, but they may not influence the development of the amiloride-blockable SCC (an adult-type feature) in larval skin.

  2. Bumetanide increases Cl--dependent short-circuit current in late distal colon: Evidence for the presence of active electrogenic Cl- absorption.

    Science.gov (United States)

    Tang, Lieqi; Fang, Xiefan; Winesett, Steven P; Cheng, Catherine Y; Binder, Henry J; Rivkees, Scott A; Cheng, Sam X

    2017-01-01

    Mammalian colonic epithelia consist of cells that are capable of both absorbing and secreting Cl-. The present studies employing Ussing chamber technique identified two opposing short-circuit current (Isc) responses to basolateral bumetanide in rat distal colon. Apart from the transepithelial Cl--secretory Isc in early distal colon that was inhibited by bumetanide, bumetanide also stimulated Isc in late distal colon that had not previously been identified. Since bumetanide inhibits basolateral Na+-K+-2Cl- cotransporter (NKCC) in crypt cells and basolateral K+-Cl- cotransporter (KCC) in surface epithelium, we proposed this stimulatory Isc could represent a KCC-mediated Cl- absorptive current. In support of this hypothesis, ion substitution experiments established Cl- dependency of this absorptive Isc and transport inhibitor studies demonstrated the involvement of an apical Cl- conductance. Current distribution and RNA sequencing analyses revealed that this Cl- absorptive Isc is closely associated with epithelial Na+ channel (ENaC) but is not dependent on ENaC activity. Thus, inhibition of ENaC by 10 μM amiloride or benzamil neither altered the direction nor its activity. Physiological studies suggested that this Cl- absorptive Isc senses dietary Cl- content; thus when dietary Cl- was low, Cl- absorptive Isc was up-regulated. In contrast, when dietary Cl- was increased, Cl- absorptive Isc was down-regulated. We conclude that an active Cl- extrusion mechanism exists in ENaC-expressing late distal colon and likely operates in parallel with ENaC to facilitate NaCl absorption.

  3. Effect of Short-Circuit Faults in the Back-to-Back Power Electronic Converter and Rotor Terminals on the Operational Behavior of the Doubly-Fed Induction Generator Wind Energy Conversion System

    Directory of Open Access Journals (Sweden)

    Dimitrios G. Giaourakis

    2015-02-01

    Full Text Available This paper deals with the operational behavior of the Doubly-Fed Induction Generator Wind Energy Conversion System under power electronic converter and rotor terminals faulty conditions. More specifically, the effect of the short-circuit fault both in one IGBT of the back-to-back power electronic converter and in rotor phases on the overall system behavior has been investigated via simulation using a system of 2 MW. Finally, the consequences of these faults have been evaluated.

  4. Photocurrent mapping of near-field optical antenna resonances

    KAUST Repository

    Barnard, Edward S.; Pala, Ragip A.; Brongersma, Mark L.

    2011-01-01

    An increasing number of photonics applications make use of nanoscale optical antennas that exhibit a strong, resonant interaction with photons of a specific frequency. The resonant properties of such antennas are conventionally characterized by far-field light-scattering techniques. However, many applications require quantitative knowledge of the near-field behaviour, and existing local field measurement techniques provide only relative, rather than absolute, data. Here, we demonstrate a photodetector platform that uses a silicon-on-insulator substrate to spectrally and spatially map the absolute values of enhanced fields near any type of optical antenna by transducing local electric fields into photocurrent. We are able to quantify the resonant optical and materials properties of nanoscale (∼50nm) and wavelength-scale (∼1μm) metallic antennas as well as high-refractive-index semiconductor antennas. The data agree well with light-scattering measurements, full-field simulations and intuitive resonator models. © 2011 Macmillan Publishers Limited. All rights reserved.

  5. Photocurrent mapping of near-field optical antenna resonances

    KAUST Repository

    Barnard, Edward S.

    2011-08-21

    An increasing number of photonics applications make use of nanoscale optical antennas that exhibit a strong, resonant interaction with photons of a specific frequency. The resonant properties of such antennas are conventionally characterized by far-field light-scattering techniques. However, many applications require quantitative knowledge of the near-field behaviour, and existing local field measurement techniques provide only relative, rather than absolute, data. Here, we demonstrate a photodetector platform that uses a silicon-on-insulator substrate to spectrally and spatially map the absolute values of enhanced fields near any type of optical antenna by transducing local electric fields into photocurrent. We are able to quantify the resonant optical and materials properties of nanoscale (∼50nm) and wavelength-scale (∼1μm) metallic antennas as well as high-refractive-index semiconductor antennas. The data agree well with light-scattering measurements, full-field simulations and intuitive resonator models. © 2011 Macmillan Publishers Limited. All rights reserved.

  6. Interpretation of photocurrent correlation measurements used for ultrafast photoconductive switch characterization

    DEFF Research Database (Denmark)

    Jacobsen, R. H.; Birkelund, Karen; Holst, T.

    1996-01-01

    of the switch. By using both photocurrent measurements and terahertz spectroscopy we verify the importance of space-charge effects on the carrier dynamics. Photocurrent nonlinearities and coherent effects are discussed as they appear in the correlation signals. An analysis based on a simple model allows......Photocurrent correlation measurements used for the characterization of ultrafast photoconductive switches based on GaAs and silicon-on-sapphire are demonstrated. The correlation signal arises from the interplay of the photoexcited carriers, the dynamics of the bias field and a subsequent recharging...

  7. Effects of excitation intensity on the photocurrent response of thin film silicon solar modules

    Science.gov (United States)

    Kim, Q.; Shumka, A.; Trask, J.

    1986-01-01

    Photocurrent responses of amorphous thin film silicon solar modules at room temperature were studied at different excitation intensities using various monochromatic light sources. Photocurrent imaging techniques have been effectively used to locate rapidly, and non-destructively, failure and defect sites in the multilayer thin film device. Differences observed in the photocurrent response characteristics for two different cells in the same amorphous thin film silicon solar module suggest the possibility of the formation of dissimilarly active devices, even though the module is processed in the same fabrication process. Possible mechanisms are discussed.

  8. Two Ti13-oxo-clusters showing non-compact structures, film electrode preparation and photocurrent properties.

    Science.gov (United States)

    Hou, Jin-Le; Luo, Wen; Wu, Yin-Yin; Su, Hu-Chao; Zhang, Guang-Lin; Zhu, Qin-Yu; Dai, Jie

    2015-12-14

    Two benzene dicarboxylate (BDC) and salicylate (SAL) substituted titanium-oxo-clusters, Ti13O10(o-BDC)4(SAL)4(O(i)Pr)16 (1) and Ti13O10(o-BDC)4(SAL-Cl)4(O(i)Pr)16 (2), are prepared by one step in situ solvothermal synthesis. Single crystal analysis shows that the two Ti13 clusters take a paddle arrangement with an S4 symmetry. The non-compact (non-sphere) structure is stabilized by the coordination of BDC and SAL. Film photoelectrodes are prepared by the wet coating process using the solution of the clusters and the photocurrent response properties of the electrodes are studied. It is found that the photocurrent density and photoresponsiveness of the electrodes are related to the number of coating layers and the annealing temperature. Using ligand coordinated titanium-oxo-clusters as the molecular precursors of TiO2 anatase films is found to be effective due to their high solubility, appropriate stability in solution and hence the easy controllability.

  9. Effect of the electrolyte cations and anions on the photocurrent of dodecylsulphate doped polypyrrole films

    Energy Technology Data Exchange (ETDEWEB)

    Martini, Milena; De Paoli, Marco-A. [Laboratorio de Poliimeros Condutores, Instituto de Quimica-UNICAMP, Universidade de Campinas, Cx Postal 6154, 13081-970 , SP Campinas (Brazil)

    2002-07-01

    Photoelectrochemical and UV-Vis spectroelectrochemical measurements were performed in a three-electrode cell containing dodecylsulphate-doped polypyrrole films as active layers in contact with different aqueous electrolytes. The effect of both cations and anions of the electrolyte on the photocurrent generation and on the absorption spectra of the system was studied. Dynamic photocurrent and absorption spectra measurements performed during the redox cycles of the films show that both cation and anion insertion and deinsertion occurs during the cycles. These results are in agreement with the previously reported redox mechanism proposed for amphiphilic anion doped polypyrrole. Reduced films show cathodic photocurrent at -0.4>E>-0.8V vs. Ag|AgCl. Photocurrent voltammograms are reproducible after the conditioning of the films and the higher cathodic currents were observed in films with thickness of =0.05-0.5{mu}m.

  10. Direct and inverse problems in dispersive time-of-flight photocurrent revisited

    Science.gov (United States)

    Sagues, Francesc; Sokolov, Igor M.

    2017-10-01

    Using the fact that the continuous time random walk (CTRW) scheme is a random process subordinated to a simple random walk under the operational time given by the number of steps taken by the walker up to a given time, we revisit the problem of strongly dispersive transport in disordered media, which first lead Scher and Montroll to introducing the power law waiting time distributions. Using a subordination approach permits to disentangle the complexity of the problem, separating the solution of the boundary value problem (which is solved on the level of normal diffusive transport) from the influence of the waiting times, which allows for the solution of the direct problem in the whole time domain (including short times, out of reach of the initial approach), and simplifying strongly the analysis of the inverse problem. This analysis shows that the current traces do not contain information sufficient for unique restoration of the waiting time probability densities, but define a single-parametric family of functions that can be restored, all leading to the same photocurrent forms. The members of the family have the power-law tails which differ only by a prefactor, but may look astonishingly different at their body. The same applies to the multiple trapping model, mathematically equivalent to a special limiting case of CTRW. Contribution to the Topical Issue "Continuous Time Random Walk Still Trendy: Fifty-year History, Current State and Outlook", edited by Ryszard Kutner and Jaume Masoliver.

  11. A photocurrent compensation method of bipolar transistors under high dose rate radiation and its experimental research

    International Nuclear Information System (INIS)

    Yin Xuesong; Liu Zhongli; Li Chunji; Yu Fang

    2005-01-01

    Experiment using discrete bipolar transistors has been performed to verify the effect of the photocurrent compensation method. The theory of the dose rate effects of bipolar transistors and the photocurrent compensation method are introduced. The comparison between the response of hardened and unhardened circuits under high dose rate radiation is discussed. The experimental results show instructiveness to the hardness of bipolar integrated circuits under transient radiation. (authors)

  12. Photocurrent enhancement of graphene photodetectors by photon tunneling of light into surface plasmons

    Science.gov (United States)

    Maleki, Alireza; Cumming, Benjamin P.; Gu, Min; Downes, James E.; Coutts, David W.; Dawes, Judith M.

    2017-10-01

    We demonstrate that surface plasmon resonances excited by photon tunneling through an adjacent dielectric medium enhance the photocurrent detected by a graphene photodetector. The device is created by overlaying a graphene sheet over an etched gap in a gold film deposited on glass. The detected photocurrents are compared for five different excitation wavelengths, ranging from {λ }0=570 {{nm}} to {λ }0=730 {{nm}}. Although the device is not optimized, the photocurrent excited with incident p-polarized light (which excites resonant surface plasmons) is significantly amplified in comparison with that for s-polarized light (without surface plasmon resonances). We observe that the photocurrent is greater for shorter wavelengths (for both s- and p-polarizations) with increased photothermal current. Position-dependent Raman spectroscopic analysis of the optically-excited graphene photodetector indicates the presence of charge carriers in the graphene near the metallic edge. In addition, we show that the polarity of the photocurrent reverses across the gap as the incident light spot moves across the gap. Graphene-based photodetectors offer a simple architecture which can be fabricated on dielectric waveguides to exploit the plasmonic photocurrent enhancement of the evanescent field. Applications for these devices include photodetection, optical sensing and direct plasmonic detection.

  13. Performance of conversion efficiency of a crystalline silicon solar cell with base doping density

    Directory of Open Access Journals (Sweden)

    Gokhan Sahin

    Full Text Available In this study, we investigate theoretically the electrical parameters of a crystalline silicon solar cell in steady state. Based on a one-dimensional modeling of the cell, the short circuit current density, the open circuit voltage, the shunt and series resistances and the conversion efficiency are calculated, taking into account the base doping density. Either the I-V characteristic, series resistance, shunt resistance and conversion efficiency are determined and studied versus base doping density. The effects applied of base doping density on these parameters have been studied. The aim of this work is to show how short circuit current density, open circuit voltage and parasitic resistances are related to the base doping density and to exhibit the role played by those parasitic resistances on the conversion efficiency of the crystalline silicon solar. Keywords: Crystalline silicon solar cell, Base doping density, Series resistance, Shunt resistance, Conversion efficiency

  14. Photocurrent response of B12As2 crystals to blue light, and its temperature- dependent electrical characterizations

    Directory of Open Access Journals (Sweden)

    R. Gul

    2016-02-01

    Full Text Available With the global shortage of 3He gas, researchers worldwide are looking for alternative materials for detecting neutrons. Among the candidate materials, semiconductors are attractive because of their light weight and ease in handling. Currently, we are looking into the suitability of boron arsenide (B12As2 for this specific application. As the first step in evaluating the material qualitatively, the photo-response of B12As2 bulk crystals to light with different wavelengths was examined. The crystals showed photocurrent response to a band of 407- and 470- nm blue light. The maximum measured photoresponsivity and the photocurrent density at 0.7 V for 470 nm blue light at room temperature were 0.25 A ⋅ W−1 and 2.47 mA ⋅ cm−2, respectively. In addition to photo current measurements, the electrical properties as a function of temperature (range: 50-320 K were measured. Reliable data were obtained for the low-temperature I-V characteristics, the temperature dependence of dark current and its density, and the resistivity variations with temperature in B12As2 bulk crystals. The experiments showed an exponential dependence on temperature for the dark current, current density, and resistivity; these three electrical parameters, respectively, had a variation of a few nA to μA, 1-100 μA ⋅ cm−2 and 7.6x105-7.7x103 Ω ⋅ cm, for temperature increasing from 50 K to 320 K. The results from this study reported the first photoresponse and demonstrated that B12As2 is a potential candidate for thermal-neutron detectors.

  15. Wireless system for location of permanent faults by short circuit current monitoring in electric power distribution network; Sistema wireless para localizacao de faltas permanentes atraves da monitoracao da corrente de curto-circuito em redes de distribuicao de energia eletrica

    Energy Technology Data Exchange (ETDEWEB)

    Machado, A.G.; Correa, A.C.; Machado, R.N. das M.; Ferreira, A.M.D.; Pinto, J.A.C. [Instituto Federal de Educacao, Ciencia e Tecnologia do Para (IFPA), Belem, PA (Brazil)], E-mail: alcidesmachado000@yahoo.com.br; Barra Junior, W. [Universidade Federal do Para (UFPA), Belem, PA (Brazil). Inst. de Tecnologia. Faculdade de Engenharia Eletrica], E-mail: walbarra@ufpa.br

    2009-07-01

    This paper presents the development of an automatic system for permanent short-circuits location in medium voltage (13.8 kV) electric power system distribution feeders, by indirect monitoring of the line current. When a permanent failure occurs, the developed system uses mobile telephony (GSM) text messages (SMS) to inform the power company operation center where the failure most likely took place. With this information in real time, the power company operation center may provide the network restoration in a faster and efficient way. (author)

  16. Relationships between body mass index and short-circuit current in human duodenal and colonic mucosal biopsies. Osbak PS, Bindslev N, Hansen MB. Acta Physiol (Oxf). 2011 Jan;201(1):47-53

    DEFF Research Database (Denmark)

    Osbak, Philip Samuel; Bindslev, Niels; Berner-Hansen, Mark

    2011-01-01

    Aim: Retrospectively, to investigate the relationship between body mass index (BMI) and basal electrogenic transport as measured by short-circuit current (SCC) in human duodenal and colonic mucosal biopsies. Methods: The study included biopsies from mucosa of normal appearance in the sigmoid colon...... and >25 kg m)2). Statistical significance was assessed by the unpaired t-test or Wilcoxon rank-sum test. Correlation coefficients were calculated by Pearson product moment correlation. Results: In colonic biopsies, basal SCC (mean standard deviation) was significantly higher in 59 biopsies from 30...

  17. Study on Oscillations during Short Circuit of MW-Scale IGBT Power Modules by Means of a 6-kA/1.1-kV Nondestructive Testing System

    DEFF Research Database (Denmark)

    Wu, Rui; Diaz Reigosa, Paula; Iannuzzo, Francesco

    2015-01-01

    This paper uses a 6-kA/1.1-kV nondestructive testing system for the analysis of the short-circuit behavior of insulated-gate bipolar transistor (IGBT) power modules. A field-programmable gate array enables the definition of control signals to an accuracy of 10 ns. Multiple 1.7-kV/1-kA IGBT power...... modules displayed severe divergent oscillations, which were subsequently characterized. Experimental tests indicate that nonnegligible circuit stray inductance plays an important role in the divergent oscillations. In addition, the temperature dependence of the transconductance is proposed as an important...

  18. Band gaps and photocurrent responses of two novel alkaline earth metal(II) complexes based on 4,5-di(4′-carboxylphenyl)benzene

    Energy Technology Data Exchange (ETDEWEB)

    Meng, Jiang Ping; Yan, Zhi Shuo; Long, Ji Ying [Department of Applied Chemistry, College of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400030 (China); Gong, Yun, E-mail: gongyun7211@cqu.edu.cn [Department of Applied Chemistry, College of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400030 (China); Lin, Jian Hua, E-mail: jhlin@pku.edu.cn [Department of Applied Chemistry, College of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400030 (China); State Key Laboratory of Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China)

    2017-01-15

    By using a rigid dicarboxylate ligand, 4,5-di(4′-carboxylphenyl)benzene (H{sub 2}L), two complexes formulated as SrL(DMF)(H{sub 2}O)·(CH{sub 3}CN) (DMF=N,N′-dimethylformamide) (1) and BaL(H{sub 2}O){sub 2} (2) were solvothermally synthesized and structurally characterized by single-crystal X-ray diffraction. Complexes 1 and 2 display two-dimensional (2D) layer structures. The two complexes exhibit different electrochemical and photoelectrochemical properties. Their thermal stabilities, cyclic voltammograms, UV–vis absorption and diffuse reflectance spectra and photoluminescence properties have been investigated. The band structures, the total density of states (TDOS) and partial density of states (PDOS) of the two complexes were calculated by CASTEP program. Complex 2 exhibits much higher photocurrent density than complex 1. The Mott–Schottky plots reveal that complexes 1 and 2 both are p-type semiconductors, which are in agreement with their band structure calculations. - Graphical abstract: Two alkaline earth metal(II) complexes with 2D layer structures are p-type semiconductors, they possess different band structures and density of states. And the Ba(II) complex 2 exhibits much higher photocurrent density than the Sr(II) complex 1.

  19. Physical Properties of Macroporous Tungsten Oxide Thin Films and Their Impact on the Photocurrent Density

    Directory of Open Access Journals (Sweden)

    I. Riech

    2013-01-01

    Full Text Available Tungsten trioxide (WO3 films were prepared using polystyrene spheres of two different diameters as a template in order to create porous layers. X-ray diffraction data and electron microscopy images show that annealed films exhibit polycrystalline structure with monoclinic phase and pore size of approximately hundred nanometers. The optical band gap energies have been determined by photoacoustic spectroscopy as 3.17 eV, and this value was not affected by sample morphology. Low temperature photoluminescence spectra exhibit broad band in the blue region. Deconvolutions of PL spectra show that there are two transitions which intensity depends on thin film pore size. We discuss the possible origin of this emissions associated with oxygen vacancies and surface states. A comparative study of the WO3 films used as photoanodes is presented and correlated with PL results.

  20. Optimized spacer layer thickness for plasmonic-induced enhancement of photocurrent in a-Si:H

    Energy Technology Data Exchange (ETDEWEB)

    Saleh, Z. M., E-mail: zaki.saleh@aauj.edu, E-mail: zakimsaleh@yahoo.com; Nasser, H.; Özkol, E.; Günöven, M.; Abak, K. [Middle East Technical University, Center for Solar Energy Research and Applications (GÜNAM) (Turkey); Canli, S. [Middle East Technical University, Central Laboratory (Turkey); Bek, A.; Turan, R. [Middle East Technical University, Center for Solar Energy Research and Applications (GÜNAM) (Turkey)

    2015-10-15

    Plasmonic interfaces consisting of silver nanoparticles of different sizes (50–100 nm) have been processed by the self-assembled dewetting technique and integrated to hydrogenated amorphous silicon (a-Si:H) using SiNx spacer layers to investigate the dependence of optical trapping enhancement on spacer layer thickness through the enhancements in photocurrent. Samples illuminated from the a-Si:H side exhibit a localized surface plasmon resonance (LSPR) that is red-shifted with the increasing particle size and broadened into the red with the increasing spacer layer thickness. The photocurrent measured in a-Si:H is not only consistent with the red-shift and broadening of the LSPR, but exhibits critical dependence on the spacer layer thickness also. The samples with plasmonic interfaces and a SiNx spacer layer exhibit appreciable enhancement of photocurrent compared with flat a-Si:H reference depending on the size of the Ag nanoparticle. Simulations conducted on one-dimensional square structures exhibit electric fields that are localized near the plasmonic structures but extend appreciably into the higher refractive index a-Si:H. These simulations produce a clear red-shift and broadening of extinction spectra for all spacer layer thicknesses and predict an enhancement in photocurrent in agreement with experimental results. The spectral dependence of photocurrent for six plasmonic interfaces with different Ag nanoparticle sizes and spacer layer thicknesses are correlated with the optical spectra and compared with the simulations to predict an optimal spacer layer thickness.

  1. Optoelectronic insights into the photovoltaic losses from photocurrent, voltage, and energy perspectives

    Science.gov (United States)

    Shang, Aixue; An, Yidan; Ma, Dong; Li, Xiaofeng

    2017-08-01

    Photocurrent and voltage losses are the fundamental limitations for improving the efficiency of photovoltaic devices. It is indeed that a comprehensive and quantitative differentiation of the performance degradation in solar cells will promote the understanding of photovoltaic physics as well as provide a useful guidance to design highly-efficient and cost-effective solar cells. Based on optoelectronic simulation that addresses electromagnetic and carrier-transport responses in a coupled finite-element method, we report a detailed quantitative analysis of photocurrent and voltage losses in solar cells. We not only concentrate on the wavelength-dependent photocurrent loss, but also quantify the variations of photocurrent and operating voltage under different forward electrical biases. Further, the device output power and power losses due to carrier recombination, thermalization, Joule heat, and Peltier heat are studied through the optoelectronic simulation. The deep insight into the gains and losses of the photocurrent, voltage, and energy will contribute to the accurate clarifications of the performance degradation of photovoltaic devices, enabling a better control of the photovoltaic behaviors for high performance.

  2. The transfer function method for the evaluation of short-circuit tests and on-site diagnostics of power transformers; Die Uebertragungsfunktion als Methode zur Beurteilung der Stosskurzschlusspruefung und Vor-Ort-Isolationsdiagnose

    Energy Technology Data Exchange (ETDEWEB)

    Christian, J.; Feser, K. [Stuttgart Univ. (Germany). Inst. fuer Energieuebertragung und Hochspannungstechnik; Leibfried, T. [Siemens AG, Nuernberg (Germany). Geschaeftsgebiet Leistungstransformatoren; Jaeggi, F. [Aare-Tessin AG fuer Elektrizitaet, Olten (Switzerland)

    1999-03-22

    A short circuit test according to IEC 76-5 was performed on a 125 MVA, 245 kV/53 kV power transformer from the Siemens factory in Nuremberg at the Kema high power laboratory (Arnhem, Netherlands) in March 1997. Thereby, the transfer function method was examined as an additional method for evaluating the short-circuit test. The visual inspection of the transformer after returning to the Nuremberg factory carried out by engineers from Atel and Siemens and representatives of Kema showed no changes of the core and coil assembly. At the Flumenthal substation a second transformer of the same type was installed. Before commissioning, the transfer functions of both transformers have been measured. These measurements provide essential information concerning the comparability of measurements from different transformers and are the basis for measurements to be carried out in the future. (orig.) [Deutsch] Im Maerz 1997 wurde ein 125-MVA-Leistungstranformator aus dem Siemens Transformatorenwerk Nuernberg im Hochleistungslabor der Kema, Arnheim einer Stosskurzschlusspruefung unterzogen. Dabei wurde die Analyse der Uebertragungsfunktion des Transformators als zusaetzliche Methode zur Beurteilung der Stosskurzschlusspruefung untersucht. Der Aktivteil wurde danach im Herstellerwerk begutachtet. Dabei ergaben sich keine Beanstandungen. Im Umspannwerk Flumenthal wurde ein zweiter baugleicher Transformator installiert. Vor der Inbetriebnahme wurden zusaetzliche Vergleichsmessungen an den zwei baugleichen Transformatoren durchgefuehrt. (orig.)

  3. Overcoming Short-Circuit in Lead-Free CH3NH3SnI3 Perovskite Solar Cells via Kinetically Controlled Gas-Solid Reaction Film Fabrication Process.

    Science.gov (United States)

    Yokoyama, Takamichi; Cao, Duyen H; Stoumpos, Constantinos C; Song, Tze-Bin; Sato, Yoshiharu; Aramaki, Shinji; Kanatzidis, Mercouri G

    2016-03-03

    The development of Sn-based perovskite solar cells has been challenging because devices often show short-circuit behavior due to poor morphologies and undesired electrical properties of the thin films. A low-temperature vapor-assisted solution process (LT-VASP) has been employed as a novel kinetically controlled gas-solid reaction film fabrication method to prepare lead-free CH3NH3SnI3 thin films. We show that the solid SnI2 substrate temperature is the key parameter in achieving perovskite films with high surface coverage and excellent uniformity. The resulting high-quality CH3NH3SnI3 films allow the successful fabrication of solar cells with drastically improved reproducibility, reaching an efficiency of 1.86%. Furthermore, our Kelvin probe studies show the VASP films have a doping level lower than that of films prepared from the conventional one-step method, effectively lowering the film conductivity. Above all, with (LT)-VASP, the short-circuit behavior often obtained from the conventional one-step-fabricated Sn-based perovskite devices has been overcome. This study facilitates the path to more successful Sn-perovskite photovoltaic research.

  4. Estimation of expected short-circuit current levels in and circuit-breaker requirements for the 330 to 750 kV networks of the southern integrated power grid

    Energy Technology Data Exchange (ETDEWEB)

    Krivushkin, L.F.; Gorazeeva, T.F.

    1978-08-01

    Studies were made in order to project the operating levels in the Southern Integrated Power Grid to the year 2000. The short-circuit current levels and, the requirements which circuit breakers will have to meet are estimated. A gradual transition from 330 to 750 kV generation is foreseen, with 330 kV networks remaining only for a purely distribution service. The number of 330 kV line hookups and the number of circuit breakers at nodal points (stations and substations) will not change significantly, they will account for 40% of all circuit breakers installed in 25% of all nodal points. Short-circuit currents are expected to reach the 46 kA level in 750 kV networks and 63 kA (standing wave voltage 1.5 to 2.5 kV/microsecond) in 330 kV networks. These are the ratings of circuit breakers; of the 63 kA ones 150 will be needed by 1980--1990 and 400 by 1990--2000. It will also be eventually worthwhile to install circuit breakers with a 63 kA-750 kV rating.

  5. Light-gated single CdSe nanowire transistor: photocurrent saturation and band gap extraction

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yang, E-mail: yangzh08@gmail.com; Chakraborty, Ritun; Kudera, Stefan; Krahne, Roman, E-mail: roman.krahne@iit.it [Istituto Italiano di Tecnologia, Nanochemistry department (Italy)

    2015-11-15

    CdSe nanowires are popular building blocks for many optoelectronic devices mainly owing to their direct band gap in the visible range of the spectrum. Here we investigate the optoelectronic properties of single CdSe nanowires fabricated by colloidal synthesis, in terms of their photocurrent–voltage characteristics and photoconductivity spectra recorded at 300 and 18 K. The photocurrent is identified as the secondary photocurrent, which gives rise to a photoconductive gain of ∼35. We observe a saturation of the photocurrent beyond a certain voltage bias that can be related to the finite drift velocity of electrons. From the photoconductivity spectra, we determine the band gap energy of the nanowires as ∼1.728 eV, and we resolve low-energy peaks that can be associated with sub-bandgap states.Graphical Abstract.

  6. Broad spectral photocurrent enhancement in Au-decorated CdSe nanowires

    KAUST Repository

    Chakraborty, Ritun; Greullet, Fanny; George, Chandramohan; Baranov, Dmitry; Di Fabrizio, Enzo M.; Krahne, Roman

    2013-01-01

    Metal-semiconductor hybrid nanostructures promise improved photoconductive performance due to plasmonic properties of the metal portions and intrinsic electric fields at the metal-semiconductor interface that possibly enhance charge separation. Here we report gold decorated CdSe nanowires as a novel functional material and investigate the influence of gold decoration on the lateral facets on the photoconductive properties. Gold decorated nanowires show typically an at least ten-fold higher photocurrent as compared to their bare counterparts. Interestingly, the photocurrent enhancement is wavelength independent, although the plasmon resonance related to the gold particles appears in the absorption spectra. Our experiments show that light scattering and Schottky fields associated with the metal-semiconductor interface are at the origin of the photocurrent enhancement. © 2013 The Royal Society of Chemistry.

  7. Development of system for automatic measurement of transient photocurrent and thermally stimulated current

    Directory of Open Access Journals (Sweden)

    Asdrubal Antonio Ramirez Botero

    2017-01-01

    Full Text Available This paper presents details of the design and implementation of a system for measuring of thermally stimulated current (TSC and transient photocurrent (Iph, developed using the Virtual Instrumentation concept. For that we have used National Instrument hardware and the LabView® package as software. The system is controlled by a virtual instrument (VI which includes facilities to perform measurements of photocurrent keeping the temperature of the sample and the pressure of the chamber of measurement controlled as well as  real time display of the Iph vs t and TSC vs T curves. The system was tested by performing transient photocurrent and TSC measurements on CH3NH3PbI3 thin films that are generally used as absorbent layer of solar cells. This type of characterization is very useful to get information of the  trapping and recombination processes that affect the transport properties of the devices.

  8. On the origin of the photocurrent of electrochemically passivated p-InP(100) photoelectrodes.

    Science.gov (United States)

    Goryachev, Andrey; Gao, Lu; van Veldhoven, René P J; Haverkort, Jos E M; Hofmann, Jan P; Hensen, Emiel J M

    2018-05-15

    III-V semiconductors such as InP are highly efficient light absorbers for photoelectrochemical (PEC) water splitting devices. Yet, their cathodic stability is limited due to photocorrosion and the measured photocurrents do not necessarily originate from H2 evolution only. We evaluated the PEC stability and activation of model p-InP(100) photocathodes upon photoelectrochemical passivation (i.e. repeated surface oxidation/reduction). The electrode was subjected to a sequence of linear potential scans with or without intermittent passivation steps (repeated passivation and continuous reduction, respectively). The evolution of H2 and PH3 gases was monitored by online electrochemical mass spectrometry (OLEMS) and the Faradaic efficiencies of these processes were determined. Repeated passivation led to an increase of the photocurrent in 0.5 M H2SO4, while continuous reduction did not affect the photocurrent of p-InP(100). Neither H2 nor PH3 formation increased to the same extent as the photocurrent during the repeated passivation treatment. Surface analysis of the spent electrodes revealed substantial roughening of the electrode surface by repeated passivation, while continuous reduction left the surface unaltered. On the other hand, photocathodic conditioning performed in 0.5 M HCl led to the expected correlation between photocurrent increase and H2 formation. Ultimately, the H2 evolution rates of the photoelectrodes in H2SO4 and HCl are comparable. The much higher photocurrent in H2SO4 is due to competing side-reactions. The results emphasize the need for a detailed evaluation of the Faradaic efficiencies of all the involved processes using a chemical-specific technique like OLEMS. Photo-OLEMS can be beneficial in the study of photoelectrochemical reactions enabling the instantaneous detection of small amounts of reaction by-products.

  9. Generation and control of spin-polarized photocurrents in GaMnAs heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Bezerra, Anibal T., E-mail: anibal@df.ufscar.br; Farinas, Paulo F.; Studart, Nelson [Departamento de Física, Universidade Federal de São Carlos, 13565-905 São Carlos, SP (Brazil); DISSE - Instituto Nacional de Ciência e Tecnologia de Nanodispositivos Semicondutores, CNPq/MCT, Rio de Janeiro, RJ (Brazil); Castelano, Leonardo K. [Departamento de Física, Universidade Federal de São Carlos, 13565-905 São Carlos, SP (Brazil); Degani, Marcos H.; Maialle, Marcelo Z. [Faculdade de Ciências Aplicadas, Universidade Estadual de Campinas, 13484-350 Limeira, SP (Brazil); DISSE - Instituto Nacional de Ciência e Tecnologia de Nanodispositivos Semicondutores, CNPq/MCT, Rio de Janeiro, RJ (Brazil)

    2014-01-13

    Photocurrents are calculated for a specially designed GaMnAs semiconductor heterostructure. The results reveal regions in the infrared range of the energy spectrum, in which the proposed structure is remarkably spin-selective. For such photon energies, the generated photocurrents are strongly spin-polarized. Application of a relatively small static bias in the growth direction of the structure is predicted to efficiently reverse the spin-polarization for some photon energies. This behavior suggests the possibility of conveniently simple switching mechanisms. The physics underlying the results is studied and understood in terms of the spin-dependent properties emerging from the particular potential profile of the structure.

  10. Insulator photocurrents: Application to dose rate hardening of CMOS/SOI integrated circuits

    International Nuclear Information System (INIS)

    Dupont-Nivet, E.; Coiec, Y.M.; Flament, O.; Tinel, F.

    1998-01-01

    Irradiation of insulators with a pulse of high energy x-rays can induce photocurrents in the interconnections of integrated circuits. The authors present, here, a new method to measure and analyze this effect together with a simple model. They also demonstrate that these insulator photocurrents have to be taken into account to obtain high levels of dose-rate hardness with CMOS on SOI integrated circuits, especially flip-flops or memory blocks of ASICs. They show that it explains some of the upsets observed in a SRAM embedded in an ASIC

  11. Ultrafast photocurrents and terahertz radiation in gallium arsenide and carbon based nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Prechtel, Hans Leonhard

    2011-08-15

    In this thesis we developed a measurement technique based on a common pump-probe scheme and coplanar stripline circuits that enables time-resolved photocurrent measurements of contacted nanosystems with a micrometer spatial and a picosecond time resolution. The measurement technique was applied to lowtemperature grown gallium arsenide (LT-GaAs), carbon nanotubes (CNTs), graphene, and p-doped gallium arsenide (GaAs) nanowires. The various mechanisms responsible for the generation of current pulses by pulsed laser excitation were reviewed. Furthermore the propagation of the resulting electromagnetic radiation along a coplanar stripline circuit was theoretically and numerically treated. The ultrafast photocurrent response of low-temperature grown GaAs was investigated. We found two photocurrent pulses in the time-resolved response. We showed that the first pulse is consistent with a displacement current pulse. We interpreted the second pulse to result from a transport current process. We further determined the velocity of the photo-generated charge carriers to exceed the drift, thermal and quantum velocities of single charge carriers. Hereby, we interpreted the transport current pulse to stem from an electron-hole plasma excitation. We demonstrated that the photocurrent response of CNTs comprises an ultrafast displacement current and a transport current. The data suggested that the photocurrent is finally terminated by the recombination lifetime of the charge carriers. To the best of our knowledge, we presented in this thesis the first recombination lifetime measurements of contacted, suspended, CVD grown CNT networks. In addition, we studied the ultrafast photocurrent dynamics of freely suspended graphene contacted by metal electrodes. At the graphene-metal interface, we demonstrated that built-in electric fields give rise to a photocurrent with a full-width-half-maximum of a few picoseconds and that a photo-thermoelectric effect generates a current with a decay time

  12. An analytical study of the minority carrier distribution and photocurrent of a p-i-n quantum dot solar cell based on the InAs/GaAs system

    Science.gov (United States)

    Biswas, Sayantan; Sinha, Amitabha

    2017-10-01

    An analytical study has been carried out on the InAs/GaAs p+-i-n+ quantum dot solar cell, taking into consideration the contributions of each region of the cell to the total photocurrent. The expressions for the excess minority carrier concentration and photocurrent from the front and the rear regions of the device have been obtained and their variations with different device parameters have been studied. Also, based on the investigations reported by some researchers earlier, the photocurrent contribution from the intrinsic region of the solar has been studied, taking into account the quantum dot ensemble absorption coefficient, which depends significantly on the quantum dot size and size dispersion. It is observed that all the three regions of the cell contribute to the overall internal quantum efficiency (IQE) of the cell. The contribution of each region of the solar cell to the total IQE has been shown graphically. From these studies it is observed that the incorporation of the quantum dots in the intrinsic region enhance the photocurrent density and hence the IQE of such solar cell, as it absorbs low energy photons, which are beyond the absorption range of GaAs. Finally, the fill factor of the solar cell has been calculated.

  13. Sandwiched confinement of quantum dots in graphene matrix for efficient electron transfer and photocurrent production

    DEFF Research Database (Denmark)

    Zhu, Nan; Zheng, Kaibo; J. Karki, Khadga

    2015-01-01

    matrix via interfacial self-assembly, leading to the formation of sandwiched hybrid QD-graphene nanofilms. We have explored structural features, electron transfer kinetics and photocurrent generation capacity of such hybrid nanofilms using a wide variety of advanced techniques. Graphene nanosheets...

  14. Photocurrent Enhanced by Singlet Fission in a Dye-Sensitized Solar Cell

    Czech Academy of Sciences Publication Activity Database

    Schrauben, J. N.; Zhao, Y.; Mercado, C.; Dron, P. I.; Ryerson, J. L.; Michl, Josef; Zhu, K.; Johnson, J. C.

    2015-01-01

    Roč. 7, č. 4 (2015), s. 2286-2293 ISSN 1944-8244 Institutional support: RVO:61388963 Keywords : photovoltaics * singlet fission * triplet * spectroscopy * charge transfer * photocurrent Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 7.145, year: 2015

  15. Low-frequency photocurrent oscillations in InP in magnetic field

    International Nuclear Information System (INIS)

    Slobodchikov, S.V.; Salikhov, Kh.M.; Kovalevskaya, G.G.

    1994-01-01

    Results of investigations of magnetic field effect on the oscillating photocurrent in InP crytals are presented. It is shown that the magnetic field plays the part of an additional source of photocarrier injection in the sample bulk. 3 refs., 2 figs

  16. Influence of injected charge carriers on photocurrents in polymer solar cells

    NARCIS (Netherlands)

    Wehenkel, D.J.; Koster, L.J.A.; Wienk, M.M.; Janssen, R.A.J.

    2012-01-01

    We determine and analyze the photocurrent Jph in polymer solar cells under conditions where, no, one, or two different charge carriers can be injected by choosing appropriate electrodes and compare the experimental results to simulations based on a drift-diffusion device model that accounts for

  17. Double functions of porous TiO2 electrodes on CH3NH3PbI3 perovskite solar cells: Enhancement of perovskite crystal transformation and prohibition of short circuiting

    Directory of Open Access Journals (Sweden)

    Govindhasamy Murugadoss

    2014-08-01

    Full Text Available In order to analyze the crystal transformation from hexagonal PbI2 to CH3NH3PbI3 by the sequential (two-step deposition process, perovskite CH3NH3PbI3 layers were deposited on flat and/or porous TiO2 layers. Although the narrower pores using small nanoparticles prohibited the effective transformation, the porous-TiO2 matrix was able to help the crystal transformation of PbI2 to CH3NH3PbI3 by sequential two-step deposition. The resulting PbI2 crystals in porous TiO2 electrodes did not deteriorate the photovoltaic effects. Moreover, it is confirmed that the porous TiO2 electrode had served the function of prohibiting short circuits between working and counter electrodes in perovskite solar cells.

  18. A kinetic Monte Carlo model with improved charge injection model for the photocurrent characteristics of organic solar cells

    Science.gov (United States)

    Kipp, Dylan; Ganesan, Venkat

    2013-06-01

    We develop a kinetic Monte Carlo model for photocurrent generation in organic solar cells that demonstrates improved agreement with experimental illuminated and dark current-voltage curves. In our model, we introduce a charge injection rate prefactor to correct for the electrode grid-size and electrode charge density biases apparent in the coarse-grained approximation of the electrode as a grid of single occupancy, charge-injecting reservoirs. We use the charge injection rate prefactor to control the portion of dark current attributed to each of four kinds of charge injection. By shifting the dark current between electrode-polymer pairs, we align the injection timescales and expand the applicability of the method to accommodate ohmic energy barriers. We consider the device characteristics of the ITO/PEDOT/PSS:PPDI:PBTT:Al system and demonstrate the manner in which our model captures the device charge densities unique to systems with small injection energy barriers. To elucidate the defining characteristics of our model, we first demonstrate the manner in which charge accumulation and band bending affect the shape and placement of the various current-voltage regimes. We then discuss the influence of various model parameters upon the current-voltage characteristics.

  19. Effective mobility and photocurrent in carbon nanotube-polymer composite photovoltaic cells

    International Nuclear Information System (INIS)

    Kymakis, E; Servati, P; Tzanetakis, P; Koudoumas, E; Kornilios, N; Rompogiannakis, I; Franghiadakis, Y; Amaratunga, G A J

    2007-01-01

    We examine the dark and the illuminated current-voltage (J-V) characteristics of poly(3-octylthiophene) (P3OT)/single-wall carbon nanotube (SWNT) composite photovoltaic cells as a function of SWNT concentration. Using an exponential band tail model, the influence of SWNT concentration on the J-V characteristics of the cells is analysed in terms of corresponding parameters such as effective hole mobility, short-circuit current, and open-circuit voltage. For the device with optimum 1% SWNT concentration, the increased photoresponse (∼500 times) as compared to the pristine P3OT cell can be attributed partly to the increase (∼50 times) in effective hole mobility, due to the reduction of localized states of the pristine P3OT matrix, and partly to the enhanced exciton extraction at the polymer/nanotube junctions

  20. Transient photocurrent in molecular junctions: singlet switching on and triplet blocking.

    Science.gov (United States)

    Petrov, E G; Leonov, V O; Snitsarev, V

    2013-05-14

    The kinetic approach adapted to describe charge transmission in molecular junctions, is used for the analysis of the photocurrent under conditions of moderate light intensity of the photochromic molecule. In the framework of the HOMO-LUMO model for the single electron molecular states, the analytic expressions describing the temporary behavior of the transient and steady state sequential (hopping) as well as direct (tunnel) current components have been derived. The conditions at which the current components achieve their maximal values are indicated. It is shown that if the rates of charge transmission in the unbiased molecular diode are much lower than the intramolecular singlet-singlet excitation/de-excitation rate, and the threefold degenerated triplet excited state of the molecule behaves like a trap blocking the charge transmission, a possibility of a large peak-like transient switch-on photocurrent arises.

  1. Photocurrent Spectroscopy of Perovskite Layers and Solar Cells: A Sensitive Probe of Material Degradation

    KAUST Repository

    Holovský , Jakub; De Wolf, Stefaan; Werner, Jé ré mie; Remeš, Zdeněk; Mü ller, Martin; Neykova, Neda; Ledinský , Martin; Černá , Ladislava; Hrzina, Pavel; Lö per, Philipp; Niesen, Bjoern; Ballif, Christophe

    2017-01-01

    Optical absorptance spectroscopy of polycrystalline CHNHPbI films usually indicates the presence of a PbI phase, either as a preparation residue or due to film degradation, but gives no insight on how this may affect electrical properties. Here, we apply photocurrent spectroscopy to both perovskite solar cells and coplanar-contacted layers at various stages of degradation. In both cases, we find that the presence of a PbI phase restricts charge-carrier transport, suggesting that PbI encapsulates CHNHPbI grains. We also find that PbI injects holes into the CHNHPbI grains, increasing the apparent photosensitivity of PbI. This phenomenon, known as modulation doping, is absent in the photocurrent spectra of solar cells, where holes and electrons have to be collected in pairs. This interpretation provides insights into the photogeneration and carrier transport in dual-phase perovskites.

  2. High-resolution photocurrent microscopy using near-field cathodoluminescence of quantum dots

    Directory of Open Access Journals (Sweden)

    Heayoung P. Yoon

    2013-06-01

    Full Text Available We report a fast, versatile photocurrent imaging technique to visualize the local photo response of solar energy devices and optoelectronics using near-field cathodoluminescence (CL from a homogeneous quantum dot layer. This approach is quantitatively compared with direct measurements of high-resolution Electron Beam Induced Current (EBIC using a thin film solar cell (n-CdS / p-CdTe. Qualitatively, the observed image contrast is similar, showing strong enhancement of the carrier collection efficiency at the p-n junction and near the grain boundaries. The spatial resolution of the new technique, termed Q-EBIC (EBIC using quantum dots, is determined by the absorption depth of photons. The results demonstrate a new method for high-resolution, sub-wavelength photocurrent imaging measurement relevant for a wide range of applications.

  3. Photocurrent Spectroscopy of Perovskite Layers and Solar Cells: A Sensitive Probe of Material Degradation

    KAUST Repository

    Holovský, Jakub

    2017-01-25

    Optical absorptance spectroscopy of polycrystalline CHNHPbI films usually indicates the presence of a PbI phase, either as a preparation residue or due to film degradation, but gives no insight on how this may affect electrical properties. Here, we apply photocurrent spectroscopy to both perovskite solar cells and coplanar-contacted layers at various stages of degradation. In both cases, we find that the presence of a PbI phase restricts charge-carrier transport, suggesting that PbI encapsulates CHNHPbI grains. We also find that PbI injects holes into the CHNHPbI grains, increasing the apparent photosensitivity of PbI. This phenomenon, known as modulation doping, is absent in the photocurrent spectra of solar cells, where holes and electrons have to be collected in pairs. This interpretation provides insights into the photogeneration and carrier transport in dual-phase perovskites.

  4. Observation of interface dependent spin polarized photocurrents in InAs/GaSb superlattice

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yuan, E-mail: liyuan12@semi.ac.cn; Liu, Yu; Zhu, Laipan; Qin, Xudong; Wu, Qing; Huang, Wei; Chen, Yonghai, E-mail: yhchen@semi.ac.cn [Key Laboratory of Semiconductor Materials Science, Institute of Semiconductors, Chinese Academy of Sciences, 100083 Beijing (China); Niu, Zhichuan; Xiang, Wei; Hao, Hongyue [The State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, 100083 Beijing (China)

    2015-05-11

    In this letter, we investigated the spin polarized photocurrents excited by mid-infrared radiation and near-infrared radiation, respectively, in InAs/GaSb type II superlattices with different kinds of interfaces. By periodically varying the polarization state of the radiation, we analyzed Rashba-type and Dresselhaus-type spin polarized photocurrents, which present different features depending on the interface types and excitation conditions. Under mid-infrared excitation, the ratio of Rashba-type and Dresselhaus-type spin polarized photocurrents of the superlattice with InSb-like interface is obviously larger than that of the superlattice with GaAs-like interface, the ratio of the superlattice with alternate interface is in the middle. Whereas under near-infrared excitation, the ratios of the three superlattices are nearly the same. Further researches reveal the synactic effects of interface dependent strain and asymmetric interface potential on the spin splitting. Besides, the polarized Raman spectroscopies of these structures were also analyzed.

  5. Observation of interface dependent spin polarized photocurrents in InAs/GaSb superlattice

    International Nuclear Information System (INIS)

    Li, Yuan; Liu, Yu; Zhu, Laipan; Qin, Xudong; Wu, Qing; Huang, Wei; Chen, Yonghai; Niu, Zhichuan; Xiang, Wei; Hao, Hongyue

    2015-01-01

    In this letter, we investigated the spin polarized photocurrents excited by mid-infrared radiation and near-infrared radiation, respectively, in InAs/GaSb type II superlattices with different kinds of interfaces. By periodically varying the polarization state of the radiation, we analyzed Rashba-type and Dresselhaus-type spin polarized photocurrents, which present different features depending on the interface types and excitation conditions. Under mid-infrared excitation, the ratio of Rashba-type and Dresselhaus-type spin polarized photocurrents of the superlattice with InSb-like interface is obviously larger than that of the superlattice with GaAs-like interface, the ratio of the superlattice with alternate interface is in the middle. Whereas under near-infrared excitation, the ratios of the three superlattices are nearly the same. Further researches reveal the synactic effects of interface dependent strain and asymmetric interface potential on the spin splitting. Besides, the polarized Raman spectroscopies of these structures were also analyzed

  6. Single-Molecule Photocurrent at a Metal-Molecule-Semiconductor Junction.

    Science.gov (United States)

    Vezzoli, Andrea; Brooke, Richard J; Higgins, Simon J; Schwarzacher, Walther; Nichols, Richard J

    2017-11-08

    We demonstrate here a new concept for a metal-molecule-semiconductor nanodevice employing Au and GaAs contacts that acts as a photodiode. Current-voltage traces for such junctions are recorded using a STM, and the "blinking" or "I(t)" method is used to record electrical behavior at the single-molecule level in the dark and under illumination, with both low and highly doped GaAs samples and with two different types of molecular bridge: nonconjugated pentanedithiol and the more conjugated 1,4-phenylene(dimethanethiol). Junctions with highly doped GaAs show poor rectification in the dark and a low photocurrent, while junctions with low doped GaAs show particularly high rectification ratios in the dark (>10 3 for a 1.5 V bias potential) and a high photocurrent in reverse bias. In low doped GaAs, the greater thickness of the depletion layer not only reduces the reverse bias leakage current, but also increases the volume that contributes to the photocurrent, an effect amplified by the point contact geometry of the junction. Furthermore, since photogenerated holes tunnel to the metal electrode assisted by the HOMO of the molecular bridge, the choice of the latter has a strong influence on both the steady state and transient metal-molecule-semiconductor photodiode response. The control of junction current via photogenerated charge carriers adds new functionality to single-molecule nanodevices.

  7. Surface plasma resonance enhanced photocurrent generation in NiO photoanode based solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zhong; Cui, Jin [Michael Grätzel Center for Mesoscopic Solar Cells, Wuhan National Laboratory for Optoelectronics Department, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan 430074, Hubei (China); Li, Junpeng [State Key Laboratory of Advanced Technologies for Comprehensive Utilization of Platinum Metals, Kunming Institute of Precious Metals, Kunming 650106 (China); Cao, Kun; Yuan, Shuai [Michael Grätzel Center for Mesoscopic Solar Cells, Wuhan National Laboratory for Optoelectronics Department, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan 430074, Hubei (China); Cheng, Yibing [Michael Grätzel Center for Mesoscopic Solar Cells, Wuhan National Laboratory for Optoelectronics Department, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan 430074, Hubei (China); Department of Materials Engineering, Monash University, Melbourne, Victoria 3800 (Australia); Wang, Mingkui, E-mail: mingkui.wang@mail.hust.edu.cn [Michael Grätzel Center for Mesoscopic Solar Cells, Wuhan National Laboratory for Optoelectronics Department, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan 430074, Hubei (China)

    2015-09-15

    Highlights: • SPR effect from Au-nanostructures was first investigated in NiO-based solar cells. • Enhanced photocurrent generation was observed in p-DSC and perovskite solar cell. • Au-nanorods SPR effect induced charge kinetics were investigated. - Abstract: Surface plasma resonance (SPR) effect has been demonstrated to improve solar cell performance. This work reports on the SPR effect from Au nanorod@SiO{sub 2} on p-type dye-sensitized solar cells. Au nanorod@SiO{sub 2} works as an antenna to transform photons with long wavelength into electric field followed by an enhanced excitation of dye. The devices using the NiO electrode containing Au nanorod@SiO{sub 2} shows overall power conversion efficiencies of about 0.2% in combination with I{sup −}/I{sub 3}{sup −} electrolyte, and 0.29% with T{sup −}/T{sub 2} electrolyte, which are superior to those without adding Au nanorods. Detailed investigation including spectroscopy and transient photovoltage decay measurements reveals that plasma effect of Au nanorod@SiO{sub 2} contribute to charge injection efficiency, and thus on the photocurrent. The effect of Au NRs can be further extended to the inverted planar perovskite solar cells, showing obviously improvement in photocurrent.

  8. Hybrid Tandem Quantum Dot/Organic Solar Cells with Enhanced Photocurrent and Efficiency via Ink and Interlayer Engineering

    KAUST Repository

    Kim, Taesoo

    2018-05-03

    Realization of colloidal quantum dot (CQD)/organic photovoltaic (OPV) tandem solar cells that integrate the strong infrared absorption of CQDs with large photovoltages of OPVs is an attractive option toward high-performing, low-cost thin film solar cells. To date, monolithic hybrid tandem integration of CQD/OPV solar cells has been restricted due to the CQD ink’s catastrophic damage to the organic subcell, thus forcing the low bandgap CQD to be used as front cell. This sub-optimal configuration limits the maximum achievable photocurrent in CQD/OPV hybrid tandem solar cells. In this work, we demonstrate hybrid tandem solar cells employing a low-bandgap CQD back cell on top of an organic front cell thanks to a modified CQD ink formulation and a robust interconnection layer (ICL) which together overcome the long-standing integration challenges for CQD and organic subcells. The resulting tandem architecture surpasses previously reported current densities by ~20-25% and yields a state-of-the-art power conversion efficiency (PCE) of 9.4%.

  9. Plasmon-enhanced photocurrent generation from self-assembled monolayers of phthalocyanine by using gold nanoparticle films.

    Science.gov (United States)

    Sugawa, Kosuke; Akiyama, Tsuyoshi; Kawazumi, Hirofumi; Yamada, Sunao

    2009-04-09

    The effect of localized electric fields on the photocurrent responses of phthalocyanine that was self-assembled on a gold nanoparticle film was investigated by comparing the conventional and the total internal reflection (TIR) experimental systems. In the case of photocurrent measurements, self-assembled monolayers (SAMs) of a thiol derivative of palladium phthalocyanine (PdPc) were prepared on the surface of gold-nanoparticle film that was fixed on the surface of indium-tin-oxide (ITO) substrate via a polyion (PdPc/AuP/polyion/ITO) or on the ITO surface (PdPc/ITO). Photocurrent action spectra from the two samples were compared by using the conventional spectrometer, and were found that PdPc/AuP/polyion/ITO gave considerably larger photocurrent signals than PdPc/ITO under the identical concentration of PdPc. In the case of the TIR experiments for the PdPc/AuP/polyion/ITO and the PdPc/AuP/Glass systems, incident-angle profiles of photocurrent and emission signals were correlated with each other, and they were different from that of the PdPc/ITO system. Accordingly, it was demonstrated that the photocurrent signals were certainly enhanced by the localized electric fields of the gold-nanoparticle film.

  10. Adrenomedullin increased the short-circuit current in the pig oviduct through chloride channels via the CGRP receptor: mediation by cAMP and calcium ions but not by nitric oxide.

    Science.gov (United States)

    Liao, S B; Cheung, K H; Cheung, M P L; To, Y T; O, W S; Tang, F

    2013-10-01

    The oviduct serves as a site for the fertilization of the ovum and the transport of the conceptus down to the uterus for implantation. In this study, we investigated the presence of adrenomedullin (ADM) and its receptor component proteins in the pig oviduct. The effect of ADM on oviductal secretion, the specific receptor, and the mechanisms involved were also investigated. The presence of ADM and its receptor component proteins in the pig oviduct were confirmed using immunostaining. Short-circuit current (I(sc)) technique was employed to study chloride ion secretion in the oviductal epithelium. ADM increased I(sc) through cAMP- and calcium-activated chloride channels, and this effect could be inhibited by the CGRP receptor antagonist, hCGRP8-37. In contrast, the nitric oxide synthase inhibitor, L-NG-nitroarginine methyl ester (L-NAME), could not block the effect of ADM on I(sc). In summary, ADM may increase oviductal fluid secretion via chloride secretion independent of the nitric oxide pathway for the transport of sperm and the conceptus.

  11. The Effect of UV-Irradiation (under Short-Circuit Condition) on Dye-Sensitized Solar Cells Sensitized with a Ru-Complex Dye Functionalized with a (diphenylamino)Styryl-Thio phen Group

    International Nuclear Information System (INIS)

    Nonomura, K.; Xu, Y.; Marinado, T.; Hagberg, D.P.; Sun, L.; Boschloo, G.; Hagfeldt, A.; Rong Zhang, R.; Boschloo, G.; Hagfeldt, A.

    2009-01-01

    A new ruthenium complex, cis-di(thiocyanato)(2,2'-bipyridine-4,4'-dicarboxylic acid)(4,4'-bis (2-(5-(2-(4-diphenylaminophenyl)ethenyl) -thiophen-2-yl)ethenyl)-2,2'-bipyridine)ruthenium(II) (named E322) has been synthesized for use in dye-sensitized solar cells (DSCs). Higher extinction coefficient and a broader absorption compared to the standard Ru-dye, N719, were aimed. DSCs were fabricated with E322, and the efficiency was 0.12% initially. (4.06% for N719, as reference). The efficiency was enhanced to 1.83% by exposing the cell under simulated sunlight containing UV-irradiation at short-circuit condition. The reasons of this enhancement are (1) enhanceing electron injection from sensitizer to TiO 2 following a shift toward positive potentials of the conduction band of TiO 2 by the adsorption of protons or cations from the sensitizer, or from the redox electrolyte and (2) improving the regeneration reaction of the oxidized dye by the redox electrolyte by the dissolution of aggregated dye from the surface of TiO 2 following the treatment.

  12. The short circuit instability in protoplanetary disks

    DEFF Research Database (Denmark)

    Hubbard, A.; McNally, C.P.; Mac Low, M.M.

    2013-01-01

    We introduce a magneto-hydrodynamic instability which occurs, among other locations, in the inner, hot regions of protoplanetary disks, and which alters the way in which resistive dissipation of magnetic energy into heat proceeds. This instability can be likened to both an electrical short circui...

  13. A Short-Circuit Method for Networks.

    Science.gov (United States)

    Ong, P. P.

    1983-01-01

    Describes a method of network analysis that allows avoidance of Kirchoff's Laws (providing the network is symmetrical) by reduction to simple series/parallel resistances. The method can be extended to symmetrical alternating current, capacitance or inductance if corresponding theorems are used. Symmetric cubic network serves as an example. (JM)

  14. Don't "Short Circuit" STEM Instruction

    Science.gov (United States)

    Bruxvoort, Crystal; Jadrich, James

    2016-01-01

    Science students should undertake engineering design projects and carry out scientific investigations, as recommended by the "Next Generation Science Standards" (NGSS Lead States 2013). However, studies show that students misconstrue the goals of science and engineering and are uncertain about their respective practices (Gilbert and Wade…

  15. Simon short circuit effect in ECRIS

    NARCIS (Netherlands)

    Drentje, AG; Wolters, U; Nadzeyka, A; Meyer, D; Wiesemann, K

    The plasma confinement within an electron cyclotron resonance ion source significantly influences the charge state distribution and hence the performance of the source. The different axial and radial diffusion processes govern the confinement time. In many experiments it has been shown that

  16. p-doped multiwall carbon nanotube/perylene diimide derivative photoelectrochemical cells for photocurrent generation

    Energy Technology Data Exchange (ETDEWEB)

    Troeger, Anna; Ledendecker, Marc; Margraf, Johannes T.; Sgobba, Vito; Guldi, Dirk M. [Department of Chemistry and Pharmacy and Interdisciplinary Center for Molecular Materials, Friedrich Alexander University Erlangen-Nuremberg, Erlangen (Germany); Vieweg, Benito F.; Spiecker, Erdmann [Center for Nanoanalysis and Electron Microscopy (CENEM) and Department Werkstoffwissenschaften/VII, Friedrich Alexander University Erlangen-Nuremberg, Erlangen (Germany); Suraru, Sabin-Lucian; Wuerthner, Frank [Institut fuer Organische Chemie and Roentgen Research Center for Complex Material Systems, Universitaet Wuerzburg, Wuerzburg (Germany)

    2012-05-15

    A perylene diimide (PDI) derivative bearing four chlorine substituents in the bay area is deposited together with pristine multiwall carbon nanotubes (MWNTs) and/or Nafion p-doped MWNTs (p-MWNTs) onto indium tin oxide (ITO) solid substrates by means of air-brushing. The resulting photoanodes are studied in photoelectrochemical cells and reveal highest photocurrent efficiencies when PDI and p-MWNT are combined as photoactive materials, indicating the beneficial effect of Nafion. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  17. Photocurrent spectroscopy of perovskite layers and solar cells: a sensitive probe of material degradation

    Czech Academy of Sciences Publication Activity Database

    Holovský, Jakub; De Wolf, S.; Werner, J.; Remeš, Zdeněk; Müller, Martin; Neykova, Neda; Ledinský, Martin; Černá, L.; Hrzina, P.; Löper, P.; Niesen, B.; Ballif, C.

    2017-01-01

    Roč. 8, č. 4 (2017), s. 838-843 ISSN 1948-7185 R&D Projects: GA ČR GJ17-26041Y; GA MŠk LM2015087 Grant - others:AV ČR(CZ) KONNECT-007 Program:Bilaterální spolupráce Institutional support: RVO:68378271 Keywords : photocurrent spectroscopy * perovskite layers * solar cells Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 9.353, year: 2016

  18. Comparison of electroluminescence intensity and photocurrent of polymer based solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Hoyer, Ulrich; Swonke, Thomas; Auer, Richard [Bayerisches Zentrum fuer Angewandte Energieforschung e.V., Erlangen (Germany); Pinna, Luigi; Brabec, Christoph J. [Bayerisches Zentrum fuer Angewandte Energieforschung e.V., Erlangen (Germany); I-MEET, University Erlangen (Germany); Stubhan, Tobias; Li, Ning [I-MEET, University Erlangen (Germany)

    2011-11-15

    The reciprocity theorem for solar cell predicts a linear relation between electroluminescence emission and photovoltaic quantum efficiency and an exponential dependence of the electroluminescence signal on the applied voltage. Both dependencies are experimentally verified for polymer based solar cells in this paper. Furthermore it is shown, that electroluminescence imaging of organic solar cells has the potential to visualize the photocurrent distribution significantly faster than standard laser beam induced current mapping (LBIC) techniques. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  19. Enhancement of photocurrent extraction and electron injection in dual-functional CH3NH3PbBr3 perovskite-based optoelectronic devices via interfacial engineering

    Science.gov (United States)

    Tsai, Chia-Lung; Lu, Yi-Chen; Hsiung Chang, Sheng

    2018-07-01

    Photocurrent extraction and electron injection in CH3NH3PbBr3 (MAPbBr3) perovskite-based optoelectronic devices are both significantly increased by improving the contact at the PCBM/MAPbBr3 interface with an extended solvent annealing (ESA) process. Photoluminescence quenching and x-ray diffraction experiments show that the ESA not only improves the contact at the PCBM/MAPbBr3 interface but also increases the crystallinity of the MAPbBr3 thin films. The optimized dual-functional PCBM-MAPbBr3 heterojunction based optoelectronic device has a high power conversion efficiency of 4.08% and a bright visible luminescence of 1509 cd m‑2. In addition, the modulation speed of the MAPbBr3 based light-emitting diodes is larger than 14 MHz, which indicates that the defect density in the MAPbBr3 thin film can be effectively reduced by using the ESA process.

  20. Um critério para determinar a regulagem da tensão em soldagem MIG/MAG por curto-circuito A criterion to determine voltage setting in short-circuit GMAW

    Directory of Open Access Journals (Sweden)

    Gabriel Maradei Carneiro de Rezende

    2011-06-01

    Full Text Available Este trabalho apresenta um estudo exploratório sobre um critério denominado "Critério Laprosolda para Estabilidade de Transferência em MIG/MAG com curto-circuito", o qual tem por finalidade uma análise quantitativa da regularidade da transferência metálica para regulagem de parâmetros para soldagem MIG/MAG por curto circuito convencional. Inicialmente é apresentado o embasamento para elaboração deste critério. A avaliação da confiabilidade do mesmo foi feita por meio de soldagens e comparações dos resultados com o rendimento de deposição e com as características geométricas do cordão de solda. Para isto, chapas de teste com 3,18 mm de espessura e abertura de raiz de 1 mm entre elas foram soldadas, dentro dos mesmos parâmetros de corrente e velocidade de alimentação, usando arame AWS ER70S-6 de 1,2 mm de diâmetro protegido pela mistura Argônio 85% - Dióxido de Carbono 15%. Para atender a relação proposta, varreu-se a regulagem de tensões de soldagem desde valores muito baixos até muito altos para o que se esperava para esta condição de soldagem. Os resultados confirmam a efetividade do "Índice de Regularidade" como meio de avaliar regulagens de soldagem MIG/MAG visando minimizar respingos e otimizar o acabamento do cordão.This paper presents an exploratory study on a criterion called "Criterion for Stability Laprosolda Transfer in MIG / MAG with short circuit", which aims at a quantitative analysis of the regularity of metal transfer for setting parameters for MIG / MAG conventional in short circuit. Initially it is stated the foundation for development of this criterion. The evaluation of that was made by welding and comparisons of results with the efficiency of deposition and the geometric characteristics of the weld bead. For this, the test plates with 3.18 mm thick and 1 mm gap between them was welded in the same range of current and feeding speed, using wire AWS ER70S-6 1.2 mm of diameter protected by the

  1. Identification of nickel-vacancy defects by combining experimental and ab initio simulated photocurrent spectra

    Science.gov (United States)

    Londero, E.; Bourgeois, E.; Nesladek, M.; Gali, A.

    2018-06-01

    There is a continuous search for solid state spin qubits operating at room temperature with excitation in the infrared communication bandwidth. Recently, we have introduced the photoelectric detection of magnetic resonance (PDMR) to read the electron spin state of nitrogen-vacancy (NV) centers in diamond, a technique which is promising for applications in quantum information technology. By measuring the photoionization spectra on a diamond crystal, we found two ionization thresholds of unknown origin. On the same sample we also observed absorption and photoluminescence signatures that were identified in the literature as Ni-associated defects. We performed ab initio calculations of the photoionization cross section of the nickel split-vacancy complex (NiV) and N-related defects in their relevant charge states and fitted the concentration of these defects to the measured photocurrent spectrum, which led to a surprising match between experimental and calculated spectra. This study enabled us to identify the two unknown ionization thresholds with the two acceptor levels of NiV. Because the excitation of NiV is in the infrared, the photocurrent detected from the paramagnetic NiV color centers is a promising way towards the design of electrically readout qubits.

  2. Characterization of the photocurrents generated by the laser of atomic force microscopes

    Energy Technology Data Exchange (ETDEWEB)

    Ji, Yanfeng; Hui, Fei; Shi, Yuanyuan; Lanza, Mario, E-mail: mlanza@suda.edu.cn [Institute of Functional Nano and Soft Materials (FUNSOM), Collaborative Innovation Center of Suzhou Nanoscience and Technology, Soochow University, 199 Ren-Ai Road, Suzhou 215123 (China); Iglesias, Vanessa [International Iberian Nanotechnology Laboratory, 4715-330 Braga (Portugal); Lewis, David [Nanonics Imaging, Har Hotzvim, Jerusalem 91487 (Israel); Niu, Jiebin; Long, Shibing; Liu, Ming [Laboratory of Nanofabrication and Novel Device Integration, Institute of Microelectronics, Chinese Academy of Sciences, Beijing 100029 (China); Hofer, Alexander; Frammelsberger, Werner; Benstetter, Guenther [Deggendorf Institute of Technology, Edlmairstr. 6+8, 94469 Deggendorf (Germany); Scheuermann, Andrew; McIntyre, Paul C. [Department of Materials Science and Engineering, Stanford University, Stanford, California 94305 (United States)

    2016-08-15

    The conductive atomic force microscope (CAFM) has become an essential tool for the nanoscale electronic characterization of many materials and devices. When studying photoactive samples, the laser used by the CAFM to detect the deflection of the cantilever can generate photocurrents that perturb the current signals collected, leading to unreliable characterization. In metal-coated semiconductor samples, this problem is further aggravated, and large currents above the nanometer range can be observed even without the application of any bias. Here we present the first characterization of the photocurrents introduced by the laser of the CAFM, and we quantify the amount of light arriving to the surface of the sample. The mechanisms for current collection when placing the CAFM tip on metal-coated photoactive samples are also analyzed in-depth. Finally, we successfully avoided the laser-induced perturbations using a two pass technique: the first scan collects the topography (laser ON) and the second collects the current (laser OFF). We also demonstrate that CAFMs without a laser (using a tuning fork for detecting the deflection of the tip) do not have this problem.

  3. Photocurrent Enhancement by a Rapid Thermal Treatment of Nanodisk-Shaped SnS Photocathodes.

    Science.gov (United States)

    Patel, Malkeshkumar; Kumar, Mohit; Kim, Joondong; Kim, Yu Kwon

    2017-12-21

    Photocathodes made from the earth-abundant, ecofriendly mineral tin monosulfide (SnS) can be promising candidates for p/n-type photoelectrochemical cells because they meet the strict requirements of energy band edges for each individual photoelectrode. Herein we fabricated SnS-based cell that exhibited a prolonged photocurrent for 3 h at -0.3 V vs the reversible hydrogen electrode (RHE) in a 0.1 M HCl electrolyte. An enhancement of the cathodic photocurrent from 2 to 6 mA cm -2 is observed through a rapid thermal treatment. Mott-Schottky analysis of SnS samples revealed an anodic shift of 0.7 V in the flat band potential under light illumination. Incident photon-to-current conversion efficiency (IPCE) analysis indicates that an efficient charge transfer appropriate for solar hydrogen generation occurs at the -0.3 V vs RHE potential. This work shows that SnS is a promising material for photocathode in PEC cells and its performance can be enhanced via simple postannealing.

  4. Tunneling Photocurrent Assisted by Interlayer Excitons in Staggered van der Waals Hetero-Bilayers.

    Science.gov (United States)

    Luong, Dinh Hoa; Lee, Hyun Seok; Neupane, Guru Prakash; Roy, Shrawan; Ghimire, Ganesh; Lee, Jin Hee; Vu, Quoc An; Lee, Young Hee

    2017-09-01

    Vertically stacked van der Waals (vdW) heterostructures have been suggested as a robust platform for studying interfacial phenomena and related electric/optoelectronic devices. While the interlayer Coulomb interaction mediated by the vdW coupling has been extensively studied for carrier recombination processes in a diode transport, its correlation with the interlayer tunneling transport has not been elucidated. Here, a contrast is reported between tunneling and drift photocurrents tailored by the interlayer coupling strength in MoSe 2 /MoS 2 hetero-bilayers (HBs). The interfacial coupling modulated by thermal annealing is identified by the interlayer phonon coupling in Raman spectra and the emerging interlayer exciton peak in photoluminescence spectra. In strongly coupled HBs, positive photocurrents are observed owing to the inelastic band-to-band tunneling assisted by interlayer excitons that prevail over exciton recombinations. By contrast, weakly coupled HBs exhibit a negative photovoltaic diode behavior, manifested as a drift current without interlayer excitonic emissions. This study sheds light on tailoring the tunneling transport for numerous optoelectronic HB devices. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Improvement in the photocurrent collection due to enhanced absorption of light by synthesizing staggered layers of silver nanoclusters in silicon

    International Nuclear Information System (INIS)

    Dhoubhadel, Mangal S.; Lakshantha, Wickramaarachchige J.; Rout, Bibhudutta; McDaniel, Floyd D.; Lightbourne, Sherard; D’Souza, Francis

    2015-01-01

    The quest for increased efficiency of solar cells has driven the research in synthesizing photovoltaic cells involving Si based materials. The efficiency of solar cells involving crystalline Si is stalled around 25% for the last decade. Recently Shi et al. had shown that light trapping can be enhanced by fabricating double layers of Ag nanoparticles in silicon based materials. The light trapping is critically important in a photo devices such as solar cells in order to increase light absorption and efficiency. In the present work, we report enhancement in the absorption of light in Ag ion implanted Si substrates. Multiple low energies Ag ions, ranging from ∼80 keV to ∼30 keV, with different fluences ranging from ∼1 × 10 16 to ∼1 × 10 17 atoms/cm 2 were sequentially implanted into commercially available Si (100) substrates followed by post-thermal annealing to create different sizes of Ag nanoclusters (NC) at different depths in the top 100 nm of the Si. The absorbance of light is increased in Ag implanted Si with a significant increase in the current collection in I-V (current-voltage) photo switching measurements. The experimental photovoltaic cells fabricated with the Ag-implanted Si samples were optically characterized under AM (air mass) 1.5 solar radiation conditions (∼1.0 kW/m 2 ). An enhancement in the charge collection were measured in the annealed samples, where prominent Ag NCs were formed in the Si matrix compared to the as-implanted samples with amorphous layers. We believe the enhancement of the photo-current density from the samples with Ag NC is due to the improvement of efficiency of charge collection of e − -h + pairs produced by the incident light

  6. Enhanced photocurrent in RuL2(NCS)2/di-(3-aminopropyl)-viologen/SnO2/ITO system

    International Nuclear Information System (INIS)

    Lee, Wonjoo; Kwak, Chang Gon; Mane, R.S.; Min, Sun Ki; Cai, Gangri; Ganesh, T.; Koo, Gumae; Chang, Jinho; Cho, Byung Won; Kim, Sei-Ki; Han, Sung-Hwan

    2008-01-01

    A Ru(2,2'-bipyridine-4,4'-dicarboxylic acid) 2 (NCS) 2 [RuL 2 (NCS) 2 ]/di-(3-aminopropyl)-viologen (DAPV)/tin oxide (SnO 2 ) system was prepared and applied to extensive photocurrent generation with its maximum surface area. The SnO 2 thin films on tin-doped indium oxide (ITO) were prepared using the chemical bath deposition method. Then, RuL 2 (NCS) 2 /DAPV on SnO 2 /ITO was easily prepared using self-assembled monolayers (SAMs). The photocurrent measurement of the system showed an excellent photocurrent of 20 nA cm -2 under the air mass 1.5 conditions (100 mW cm -2 ), which was increased by a factor of four compared to ones without SnO 2 layers

  7. Electrodeposition of gold nanoparticles on mesoporous TiO{sub 2} photoelectrode to enhance visible region photocurrent

    Energy Technology Data Exchange (ETDEWEB)

    Supriyono,; Krisnandi, Yuni Krisyuningsih; Gunlazuardi, Jarnuzi, E-mail: jarnuzi@ui.ac.id [Department of Chemistry, FMIPA, Universitas Indonesia, Kampus UI Depok (Indonesia)

    2016-04-19

    Electrodeposition of gold nanoparticles (Au NPs) on the mesoporous TiO{sub 2} photoelectrode to enchance visible region photocurrent have been investigated. Mesoporous TiO{sub 2} was prepared by a sol gel method and immobilized to the fluorine doped tin oxide (FTO) substrate by dip coating technique. Gold nanoparticles were electrodeposited on the TiO{sub 2} surface and the result FTO/TiO{sub 2}/Au was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), UV-Vis diffuse reflectance spectroscopy (DRS), and X-ray diffraction (XRD). The generated photocurrent was evaluated with an electrochemical workstation (e-DAQ/e-recorder 401) using 60 W wolfram lamp as visible light source. The photoelectrochemical evaluation indicated that the presence of gold nanoparticles on TiO{sub 2} photoelectrode shall enhance the photocurrent up to 50%.

  8. Effect of iodine doping of phthalocyanine on the photocurrent generation in a phthalocyanine/C{sub 60} heterojunction

    Energy Technology Data Exchange (ETDEWEB)

    Mizuta, Shinsei; Iyota, Masatoshi; Tanaka, Senku; Hiromitsu, Ichiro, E-mail: hiromitu@riko.shimane-u.ac.jp

    2012-06-30

    Photocurrent generation in an indium-tin oxide (ITO)/iodine-doped Ni-phthalocyanine (NiPc-I{sub x})/C{sub 60}/In/Al heterojunction device with x {approx} 1 was studied. By keeping the device in air after preparation, the device slowly reached a stationary state in which the sign of the photocurrent is opposite to that of a non-doped ITO/NiPc/C{sub 60}/In/Al device although the rectification direction for the dark current is the same. By a simulation of incident photon-to-current conversion efficiency spectra and a measurement of internal electric field by electroabsorption spectroscopy, it was elucidated that, in the doped device, the band bending near the phthalocyanine/C{sub 60} interface is absent and the photocurrent is generated by a weak Schottky barrier at the C{sub 60}/In interface. It is also shown that the C{sub 60} film encapsulates the doped iodine into the NiPc-I{sub x} layer to stabilize the doping level and prevent the reaction of iodine with In. - Highlights: Black-Right-Pointing-Pointer The C{sub 60} film deposited on a NiPc-I{sub x} film encapsulates the doped iodine. Black-Right-Pointing-Pointer An iodine-doped device generates a photocurrent of inverted direction. Black-Right-Pointing-Pointer The internal electric field is also inverted. Black-Right-Pointing-Pointer The activity of photocurrent generation at the heterojunction is quenched. Black-Right-Pointing-Pointer Photocurrent is generated at the C{sub 60}/In interface.

  9. Effect of iodine doping of phthalocyanine on the photocurrent generation in a phthalocyanine/C_<60> heterojunction

    OpenAIRE

    Mizuta, Shinsei; Iyota, Masatoshi; Tanaka, Senku; Hiromitsu, Ichiro

    2012-01-01

    Photocurrent generation in an indium?tin oxide (ITO)/iodine-doped Ni-phthalocyanine (NiPc-I_x)/C_/In/Al heterojunction device with x~1 was studied. By keeping the device in air after preparation, the device slowly reached a stationary state in which the sign of the photocurrent is opposite to that of a non-doped ITO/NiPc/C_/In/Al device although the rectification direction for the dark current is the same. By a simulation of incident photon-to-current conversion efficiency spectra and a measu...

  10. Effect of photocurrent amplification in In sub 2 O sub 3 -GaSe heterostructure

    CERN Document Server

    Drapak, S I

    2001-01-01

    The experimentally determined effects of originating the photocurrent amplification in the In sub 2 O sub 3 -GaSe heterostructure with localization of the barrier plane perpendicular to the semiconductor layers are described. The value of the amplification coefficient by the reverse displacement U = 10 V reached M approx = 82 and the absolute value of the current sensitivity - 30-32 A/W. The mechanism of the current transfer through the dielectric, inevitable originating on the gallium monoselenide surface, is determined on the basis of the volt-ampere characteristics study. The supposition is made on the change in the conductivity mechanisms by transferring the barrier plane from the parallel to the perpendicular one to the GaSe layers

  11. Gap-plasmon based broadband absorbers for enhanced hot-electron and photocurrent generation

    DEFF Research Database (Denmark)

    Lu, Yuhua; Dong, Wen; Chen, Zhuo

    2016-01-01

    Plasmonic hot-electron generation has recently come into focus as a new scheme for solar energy conversion. So far, however, due to the relatively narrow bandwidth of the surface plasmon resonances and the insufficient resonant light absorption, most of plasmonic photocatalysts show narrow......-band spectral responsivities and small solar energy conversion efficiencies. Here we experimentally demonstrate that a three-layered nanostructure, consisting of a monolayer gold-nanoparticles and a gold film separated by a TiO2 gap layer (Au-NPs/TiO2/Au-film), is capable of near-completely absorbing light...... within the whole visible region. We show that the Au-NPs/TiO2/Au-film device can take advantage of such strong and broadband light absorption to enhance the generation of hot electrons and thus the photocurrent under visible irradiation. As compared to conventional plasmonic photocatalysts such as Au...

  12. Giant photocurrent enhancement by transition metal doping in quantum dot sensitized solar cells

    Science.gov (United States)

    Rimal, Gaurab; Pimachev, Artem K.; Yost, Andrew J.; Poudyal, Uma; Maloney, Scott; Wang, Wenyong; Chien, TeYu; Dahnovsky, Yuri; Tang, Jinke

    2016-09-01

    A huge enhancement in the incident photon-to-current efficiency of PbS quantum dot (QD) sensitized solar cells by manganese doping is observed. In the presence of Mn dopants with relatively small concentration (4 at. %), the photoelectric current increases by an average of 300% (up to 700%). This effect cannot be explained by the light absorption mechanism because both the experimental and theoretical absorption spectra demonstrate several times decreases in the absorption coefficient. To explain such dramatic increase in the photocurrent we propose the electron tunneling mechanism from the LUMO of the QD excited state to the Zn2SnO4 (ZTO) semiconductor photoanode. This change is due to the presence of the Mn instead of Pb atom at the QD/ZTO interface. The ab initio calculations confirm this mechanism. This work proposes an alternative route for a significant improvement of the efficiency for quantum dot sensitized solar cells.

  13. Giant photocurrent enhancement by transition metal doping in quantum dot sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Rimal, Gaurab; Pimachev, Artem K.; Yost, Andrew J.; Poudyal, Uma; Maloney, Scott; Wang, Wenyong; Chien, TeYu; Dahnovsky, Yuri, E-mail: yurid@uwyo.edu, E-mail: jtang2@uwyo.edu; Tang, Jinke, E-mail: yurid@uwyo.edu, E-mail: jtang2@uwyo.edu [Department of Physics and Astronomy, University of Wyoming, Laramie, Wyoming 82071 (United States)

    2016-09-05

    A huge enhancement in the incident photon-to-current efficiency of PbS quantum dot (QD) sensitized solar cells by manganese doping is observed. In the presence of Mn dopants with relatively small concentration (4 at. %), the photoelectric current increases by an average of 300% (up to 700%). This effect cannot be explained by the light absorption mechanism because both the experimental and theoretical absorption spectra demonstrate several times decreases in the absorption coefficient. To explain such dramatic increase in the photocurrent we propose the electron tunneling mechanism from the LUMO of the QD excited state to the Zn{sub 2}SnO{sub 4} (ZTO) semiconductor photoanode. This change is due to the presence of the Mn instead of Pb atom at the QD/ZTO interface. The ab initio calculations confirm this mechanism. This work proposes an alternative route for a significant improvement of the efficiency for quantum dot sensitized solar cells.

  14. Probing Photocurrent Nonuniformities in the Subcells of Monolithic Perovskite/Silicon Tandem Solar Cells

    KAUST Repository

    Song, Zhaoning

    2016-11-23

    Perovskite/silicon tandem solar cells with high power conversion efficiencies have the potential to become a commercially viable photovoltaic option in the near future. However, device design and optimization is challenging because conventional characterization methods do not give clear feedback on the localized chemical and physical factors that limit performance within individual subcells, especially when stability and degradation is a concern. In this study, we use light beam induced current (LBIC) to probe photocurrent collection nonuniformities in the individual subcells of perovskite/silicon tandems. The choices of lasers and light biasing conditions allow efficiency-limiting effects relating to processing defects, optical interference within the individual cells, and the evolution of water-induced device degradation to be spatially resolved. The results reveal several types of microscopic defects and demonstrate that eliminating these and managing the optical properties within the multilayer structures will be important for future optimization of perovskite/silicon tandem solar cells.

  15. Correlation of morphology with photocurrent generation in a polymer blend photovoltaic device.

    Science.gov (United States)

    Ostrowski, David P; Vanden Bout, David A

    2014-05-14

    Morphological effects on photovoltaic (PV) properties are studied through scanning photocurrent (PC) and photoluminescence (PL) microscopy of a solution processed, polymer blend PV device composed of PFB [poly(9,9'-dioctylfluorene-co-bis-N,N-(4-butylphenyl)-bis-N,N-phenyl-1,4-phenylenediamine] and F8BT [poly(9,9'-dioctylfluorene-co-benzothiadiazole]. As PFB and F8BT have unique absorbance bands, it is possible to selectively excite only F8BT (488 nm) or both PFB and F8BT (408 nm). Local voltage-dependent photocurrent (LVPC) measurements from particular regions of interest in the PV show that the diode characteristics between different morphologies are essentially the same, except in regard to the magnitude of PC generated. A local PL spectrum is measured simultaneously with PC generation at each pixel in the image maps. Through integration of the local PL spectrum over particular wavelength ranges, PL image maps are created of PFB-PL (435 to 475 nm), F8BT-PL (530 to 570 nm), exciplex-PL (620 to 685 nm) and total-PL (entire spectrum). These data allow direct correlation of PC generation with local chemical composition variations within the PV device. PL image maps show morphological variations on the order of 0.5 to 1 µm of alternating PFB-rich and F8BT-rich phases. While illuminating only F8BT (488 nm light), the PFB-rich phases produce the most PC, however, while illuminating both polymers but mostly PFB (408 nm light), the F8BT-rich phases produce the most PC. These results show that in the morphology where the light absorbing material is less concentrated, the PC generation is increased. Additionally, the exciplex-PL is found to not be a significant radiative loss mechanism of charge carriers for PC generation. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Imaging the formation of a p-n junction in a suspended carbon nanotube with scanning photocurrent microscopy

    NARCIS (Netherlands)

    Buchs, G.; Barkelid, K.M.; Bagiante, S.; Steele, G.A.; Zwiller, V.

    2011-01-01

    We use scanning photocurrent microscopy (SPCM) to investigate individual suspended semiconducting carbon nanotube devices where the potential profile is engineered by means of local gates. In situ tunable p-n junctions can be generated at any position along the nanotube axis. Combining SPCM with

  17. The study of amplification circuit characteristics of photocurrent signal of high-energy industrial CT detection system

    International Nuclear Information System (INIS)

    Wang Jue; Tan Hui; Wang Xin; Chen Jiaoze

    2011-01-01

    According to characteristics of the Photocurrent signal from detection system of high energy industrial CT, sets up the integral amplifier circuit test platform based ACF2101, through the study of this amplifier circuit, a integral capacitor using air as dielectric is proposed in order to get high-gain. After experimental tests, results are good. (authors)

  18. Photocurrent spectra of semi-insulating GaAs M-S-M diodes: role of the contacts

    Czech Academy of Sciences Publication Activity Database

    Dubecký, F.; Oswald, Jiří; Kindl, Dobroslav; Hubík, Pavel; Dubecký, M.; Gombia, E.; Šagátová, A.; Boháček, P.; Sekáčová, M.; Nečas, V.

    2016-01-01

    Roč. 118, Apr (2016), 30-35 ISSN 0038-1101 Institutional support: RVO:68378271 Keywords : photocurrent spectroscopy * semi-insulating GaAs * detectors * contacts Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.580, year: 2016

  19. Potential and pH dependence of photocurrent transients for boron-doped diamond electrodes in aqueous electrolyte

    International Nuclear Information System (INIS)

    Green, S.J.; Mahe, L.S.A.; Rosseinsky, D.R.; Winlove, C.P.

    2013-01-01

    Using illumination at energies below the intrinsic diamond energy gap, photocurrent transients have been recorded for boron-doped diamond (BDD) as an electrode in an aqueous electrolyte of 0.1 M KH 2 PO 4 . The commercially-supplied BDD was in the form of a free-standing, polycrystalline film grown by chemical vapour deposition (CVD), with a boron acceptor concentration of ≥10 20 cm −3 . The effects of mechanical polishing of the BDD, of electrochemical hydrogen evolution and of electrochemical oxygen evolution (in 0.1 M KH 2 PO 4 ), on the potential dependence of the photocurrent transients have been examined. Measurements of the cathodic photocurrent at light switch-on have been used to determine the photocurrent onset potential as a measure of the flatband potential. Comparison with and between related literature observations has shown broad agreement across considerably varying BDD/electrolyte systems. The flatband potential shifted positively following electrochemical oxygen evolution, indicating the formation of oxygen-containing groups on the diamond surface, these increasing the potential drop across the Helmholtz layer. For the electrochemically oxidised electrode, the cathodic photocurrent transient at a fixed potential changed reproducibly with changing solution pH, owing to the participation of the oxygen-containing surface groups in acid–base equilibrium with the solution. This clear demonstration of BDD as a photoelectrochemical pH sensor is in principle extendable to mapping the spatial variation in pH across a BDD surface by use of a focussed light spot

  20. Configurations, band structures and photocurrent responses of 4-(4-oxopyridin-1(4H)-yl)phthalic acid and its metal-organic frameworks

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Xingxiu; Qiu, Xiandeng; Yan, Zhishuo; Li, Hongjiang [Department of Applied Chemistry, College of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400030 (China); Gong, Yun, E-mail: gongyun7211@cqu.edu.cn [Department of Applied Chemistry, College of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400030 (China); Lin, Jianhua, E-mail: jhlin@pku.edu.cn [Department of Applied Chemistry, College of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400030 (China); State Key Laboratory of Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China)

    2016-05-15

    4-(4-oxopyridin-1(4 H)-yl)phthalic acid (H{sub 2}L) and three H{sub 2}L-based metal-organic frameworks (MOFs) formulated as ZnL(DPE)(H{sub 2}O)·H{sub 2}O (DPE=(E)-1, 2-di(pyridine −4-yl)ethene) (1), CdL(H{sub 2}O){sub 2} (2) and CdL (3) were synthesized and structurally characterized by single-crystal X-ray diffraction. The free H{sub 2}L ligand shows an enol-form and the L{sup 2−} ligand in the three MOFs exists as the keto-form. Density functional theory (DFT) calculations indicate H{sub 2}L and the three MOFs possess different band structures. Due to the existence of the N-donor, DPE in MOF 1, the conduction band (CB) minimum and band gap of MOF 1 are much lower than those of H{sub 2}L. And MOF 1 yielded much larger photocurrent density than H{sub 2}L upon visible light illumination. Electrochemical impedance spectroscopy (EIS) shows the interfacial charge transfer impedance in the presence of MOF 1 is lower than that in the presence of H{sub 2}L. The hydrous MOF 2 and the anhydrous MOF 3 are both constructed by Cd(II) and L{sup 2−}, and they can be reversibly transformed to each other. However, MOFs 2 and 3 possess different CB minimums and VB maximums, and their band gaps are much larger than that of MOF 1. - Graphical abstract: The free ligand, 4-(4-oxopyridin-1(4H)-yl)phthalic acid (H{sub 2}L) shows different configuration from its three MOFs, and they possess different band structures. MOF 1 yielded much larger visible-light-driven photocurrent density than H{sub 2}L. The hydrous MOF 2 and the anhydrous MOF 3 can be transformed to each other, and they have larger band gaps than MOF 1.

  1. Estudo de alguns parâmetros básicos da soldagem GMAW com transferência por curto-circuito Evaluation of basic parameters of short-circuit GMA welding

    Directory of Open Access Journals (Sweden)

    Paulo J. Modenesi

    2011-03-01

    these limitations of GMA welding, the authors of the present work have been working on the development of a mathematical model to simulate the variation of operational and electrical parameters during welding. This paper aims to evaluate methodologies to determine two key variables of this model (the electrode electrical resistivity and the sum of the voltage drops in the arc anode and cathode regionsin short-circuit welding. Experimental trials were performed in a mechanized jig by depositing bead-onplate welds on low-carbon steel bars. Methodologies to evaluate those variables were developed based in proposals from the literature. Experimental details of these methodologies are analyzed and their results are compared to results from the literature. These procedures are evaluated, compared with data from the literature and new procedures are proposed to estimate those parameters and the contact resistance between the contact tip and the electrode. Results suggest values between 6 and 9 Ω for this last parameter.

  2. Photocurrents in retinal rods of pigeons (Columba livia): kinetics and spectral sensitivity.

    Science.gov (United States)

    Palacios, A G; Goldsmith, T H

    1993-01-01

    1. Membrane photocurrents were recorded from outer segments of isolated retinal rods of pigeons (Columba livia), the first such measurements on the photoreceptors of a bird. The amplitude of the response to 20 ms flashes of narrow wavelength bands of light increases linearly with intensity at low photon fluxes and saturates at higher intensities. The maximum (saturating) photocurrent observed in forty-nine rod cells was 50 pA. Larger responses with less variability in the intensity for half-maximal responses were observed when the physiological saline contained 20 mM bicarbonate (in addition to Hepes buffer). 2. The dependence of peak amplitude on intensity is well fitted by an exponential function; it is usually less well fitted by the Michaelis-Menten (Naka-Rushton) equation. 3. In the presence of bicarbonate, the average sensitivity of pigeon rods to dim flashes was 0.56 pA photon-1 microns -2. The effective collecting area per photon was 1.8 microns 2. About 83 +/- 26 (mean +/- S.D.) photoisomerizations were required for a half-saturating response. 4. The response kinetics of rods to dim flashes can be reasonably well described by a series of four to five either Poisson or independent filters. The time to peak, measured from the mid-point of a 20 ms flash, was 319 +/- 83 ms (mean +/- S.D.). The integration time of the response was 851 +/- 86 ms (mean +/- S.D.) with bicarbonate present and 572 +/- 126 ms in the absence of bicarbonate. The responses of pigeon rods appear to be slower than those of mammals at the same temperature. The fraction of current suppressed by a single photoisomerization is smaller in pigeon than in mammalian rods by a factor of at least two. 5. The spectral sensitivity function was measured between 680 and 330 nm. The maximum at about 505 nm (range 497-508 nm) corresponds to the alpha-band of a vertebrate rhodopsin and agrees with previous behavioural measurements of scotopic sensitivity of pigeons as well as the absorption spectrum of

  3. Analytic 1D pn junction diode photocurrent solutions following ionizing radiation and including time-dependent changes in the carrier lifetime.

    Energy Technology Data Exchange (ETDEWEB)

    Axness, Carl L.; Keiter, Eric Richard; Kerr, Bert (New Mexico Tech, Socorro, NM)

    2011-04-01

    Circuit simulation tools (e.g., SPICE) have become invaluable in the development and design of electronic circuits in radiation environments. These codes are often employed to study the effect of many thousands of devices under transient current conditions. Device-scale simulation tools (e.g., MEDICI) are commonly used in the design of individual semiconductor components, but require computing resources that make their incorporation into a circuit code impossible for large-scale circuits. Analytic solutions to the ambipolar diffusion equation, an approximation to the carrier transport equations, may be used to characterize the transient currents at nodes within a circuit simulator. We present new transient 1D excess carrier density and photocurrent density solutions to the ambipolar diffusion equation for low-level radiation pulses that take into account a finite device geometry, ohmic fields outside the depleted region, and an arbitrary change in the carrier lifetime due to neutron irradiation or other effects. The solutions are specifically evaluated for the case of an abrupt change in the carrier lifetime during or after, a step, square, or piecewise linear radiation pulse. Noting slow convergence of the raw Fourier series for certain parameter sets, we use closed-form formulas for some of the infinite sums to produce 'partial closed-form' solutions for the above three cases. These 'partial closed-form' solutions converge with only a few tens of terms, which enables efficient large-scale circuit simulations.

  4. Evidence for surface-generated photocurrent in (Bi,Sb)2Se3and(Bi,Sb)2Te3 thin films

    Science.gov (United States)

    Pan, Yu; Richardella, Anthony; Yao, Bing; Lee, Joon Sue; Flanagan, Thomas; Kandala, Abhinav; Samarth, Nitin; Yeats, Andrew; Mintun, Peter; Awschalom, David

    2015-03-01

    Illumination with circularly polarized light is known produce a helicity-dependent photocurrent in topological insulators such as Bi2Se3 [e.g. Nature Nanotech. 7, 96 (2012)]. However, the exact origin of this effect is still unclear since it is observed with photons well above the bulk band gap. We report measurements of the polarization-dependent photocurrent in a series of (Bi,Sb)2Se3 thin films with different carrier concentrations and find that the photocurrent is enhanced as we increase the population of the surface states. This finding is supported by a study of helicity-dependent photocurrents in back-gated (Bi,Sb)2Te3 thin films, where the chemical potential is varied electrostatically. By illuminating our samples at different wavelengths, we show that the helicity-dependent photocurrent is enhanced when the photon energy approaches the energy difference between the lowest and first excited (unoccupied) topological surface states. This leads us to attribute the helicity-dependent photocurrent in topological insulators to optical excitations between these two spin-textured surface states. We will also discuss experiments imaging the spatial variation of these helicity-dependent photocurrents. This work is supported by ONR.

  5. FY 1998 annual report on the research and development of superhigh-sensitivity photocurrent conversion devices; 1998 nendo chokokando koden henkan soshi ni kansuru kenkyu kaihatsu chosa hokokusho

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-03-01

    Described herein are research and development of superhigh-sensitivity photocurrent conversion devices. The huge photocurrent multiplication effect exhibited by a thin film of organic pigment semiconductor is expected to be applicable to various new devices, e.g., superhigh-sensitivity, intelligent optical sensor families and photocurrent devices. Photocurrent multiplier thin films of perylene is prepared by an ionized cluster beam method, to evaluate their structures and photocurrent characteristics as the basic knowledge for controlling their characteristics by the ion engineering procedures. Photocurrent multiplier thin films of new, two-layer structure are developed, and improvement and stabilization of their characteristics are studied. Increasing sensing sensitivity by, e.g., introduction of p-n junction and reducing dark current resulting from the light memory effect are found to be effective to improve the S/N ratio. An organic EL light-emitting layer capable of positive/negative feedback, as one of the elementary techniques for realizing intelligent devices, is made on a trial basis and evaluated for its characteristics, and studied for its application to photocurrent multiplier thin films. Functional devices in which the arithmetic and controlling functions of the thin films are utilized are also studied. (NEDO)

  6. New Aspects of Photocurrent Generation at Graphene pn Junctions Revealed by Ultrafast Optical Measurements

    Science.gov (United States)

    Aivazian, Grant; Sun, Dong; Jones, Aaron; Ross, Jason; Yao, Wang; Cobden, David; Xu, Xiaodong

    2012-02-01

    The remarkable electrical and optical properties of graphene make it a promising material for new optoelectronic applications. However, one important, but so far unexplored, property is the role of hot carriers in charge and energy transport at graphene interfaces. Here we investigate the photocurrent (PC) dynamics at a tunable graphene pn junction using ultrafast scanning PC microscopy. Pump-probe measurements show a temperature dependent relaxation time of photogenerated carriers that increases from 1.5ps at 290K to 4ps at 20K; while the amplitude of the PC is independent of the lattice temperature. These observations imply that it is hot carriers, not phonons, which dominate ultrafast energy transport. Gate dependent measurements show many interesting features such as pump induced saturation, enhancement, and sign reversal of probe generated PC. These observations reveal that the underlying PC mechanism is a combination of the thermoelectric and built-in electric field effects. Our results enhance the understanding of non-equilibrium electron dynamics, electron-electron interactions, and electron-phonon interactions in graphene. They also determine fundamental limits on ultrafast device operation speeds (˜500 GHz) for graphene-based photodetectors.

  7. Enhanced Photocurrent Efficiency of a Carbon Nanotube Embedded in a Photonic Structure

    Energy Technology Data Exchange (ETDEWEB)

    Wong, Bryan M. [Sandia National Lab. (SNL-CA), Livermore, CA (United States). Materials Science

    2008-08-01

    One of the most rapidly-growing areas in nanoscience is the ability to artificially manipulate optical and electrical properties at the nanoscale. In particular, nanomaterials such as single-wall carbon nanotubes offer enhanced methods for converting infrared light to electrical energy due to their unique one-dimensional electronic properties. However, in order for this energy conversion to occur, a realistic nanotube device would require high-intensity light to be confined on a nanometer scale. This arises from the fact that the diameter of a single nanotube is on the order of a nanometer, and infrared light from an external source must be tightly focused on the narrow nanotube for efficient energy conversion. To address this problem, I calculate the theoretical photocurrent of a nanotube p-n junction illuminated by a highly-efficient photonic structure. These results demonstrate the utility of using a photonic structure to couple large-scale infrared sources with carbon nanotubes while still retaining all the unique optoelectronic properties found at the nanoscale.

  8. Time dependent rise and decay of photocurrent in zinc oxide nanoparticles in ambient and vacuum medium

    Science.gov (United States)

    C, Rajkumar; Srivastava, Rajneesh K.

    2018-05-01

    Zinc oxide (ZnO) nanoparticle has been synthesized by cost effective Co-precipitation method and studied its photo-response activity. The synthesized ZnO nanomaterial was characterized by using various analytical techniques such as x-ray diffraction (XRD), UV–visible spectroscopy, FTIR spectroscopy, photoluminescence (PL) spectroscopy, and Scanning Electron Microscopy (SEM). From the XRD results, it is confirmed that synthesized ZnO nanomaterial possess hexagonal wurtzite phase structure with an average crystallite size of ∼16–17 nm. The UV-Visible absorption spectrum shows that it has blue shift compared to their bulk counterparts. Photoluminescence spectra of ZnO nanoparticles have a strong violet band at 423 nm and three weak bands at 485 nm (blue), 506 nm (green), and 529 nm (green). The presence of hydroxyl group was confirmed by FTIR. The photo-response analysis was studied by the time-dependent rise and decay photocurrent of ZnO nanoparticle was tested in the air as well as vacuum medium.

  9. Nonlinear photocurrent-intensity behavior of amorphous InZnO thin film transistors

    Science.gov (United States)

    Lu, Huiling; Zhou, Xiaoliang; Liang, Ting; Zhang, Letao; Zhang, Shengdong

    2018-01-01

    The photocurrent (IPH) of amorphous InZnO thin film transistors in the off-state is investigated as a function of incident optical power (P). The results show that IPH exhibits a nonlinear dependence on P. Additionally, the dependence of IPH on P exhibits a strong photon energy (hυ)-dependent feature. When P is relatively low, IPH is shown to be proportional to Pγ, where γ is greater than 1. The γ > 1 behavior may be ascribed to the source-barrier-lowering effect due to the accumulation of photo-induced positive charges at the source side. When P is relatively high, while IPH remains proportional to Pγ under the incident light with hυ larger than the optical bandgap (Eg) of a-IZO, it turns to increase at an exponential rate with P if hυ of the incident light is smaller than the Eg. The exponential increase in IPH is attributed to the source-barrier-thinning effect, which leads to a significantly enhanced tunneling current.

  10. Anode engineering for photocurrent enhancement in a polymer solar cell and applied on plastic substrate

    Energy Technology Data Exchange (ETDEWEB)

    Tsai, Hsing-Wang; Li, Pei-Wen [Department of Electrical Engineering, National Central University, Chungli 32001 (China); Pei, Zingway; Cheng, Shor-Jeng; Hsieh, Wei-Shung [Graduate Institute of Optoelectronic Engineering, Department of Electrical Engineering, National Chung Hsing University, Taichung 40227 (China); Chen, Chun-Chao; Chan, Yi-Jen [Electronics and Optoelectronics Research Laboratories (EOL), Industrial Technology Research Institute (ITRI), Hsinchu 31040 (China)

    2011-02-15

    In this work, a multilayer structure, PEDOT:PSS/insulator/PEDOT:PSS (CIC), was designed and used as the anode in a polymer solar cell (PSC) to enhance the efficiency at low annealing temperature. The efficiency for PSC with CIC multilayers could increase around 22% as compared to the reference cell. The internal electrical field enhancement due to the effective work function increase by CIC multilayer was assumed and responded to efficiency enhancement. The work function of the multilayer anode structure was explored by an electrostatic force microscopy (EFM) analysis. The EFM result shows that the surface potential of PEDPT:PSS in CIC structure is around 0.6 V higher than PEDOT:PSS in reference structure, indicating a higher work function for PEDOT:PSS in multilayer structure. By the input photon-to-current conversion efficiency (IPCE) study, the major enhancement in photocurrent occurred at solar spectrum range of 400-650 nm. Further applied to plastic substrate, the PSC exhibits 9.2% enhancement in efficiency. (author)

  11. Photon wavelength dependent valley photocurrent in multilayer MoS2

    Science.gov (United States)

    Guan, Hongming; Tang, Ning; Xu, Xiaolong; Shang, LiangLiang; Huang, Wei; Fu, Lei; Fang, Xianfa; Yu, Jiachen; Zhang, Caifeng; Zhang, Xiaoyue; Dai, Lun; Chen, Yonghai; Ge, Weikun; Shen, Bo

    2017-12-01

    The degree of freedom (DOF) of the K (K') valley in transition-metal dichalcogenides, especially molybdenum disulfide (MoS2), offers an opportunity for next-generation valleytronics devices. In this work, the K (K') valley DOF of multilayer MoS2 is studied by means of the photon wavelength dependent circular photogalvanic effect (CPGE) at room temperature upon a strong external out-of-plane electric field induced by an ionic liquid (IL) gate, which breaks the spatial-inversion symmetry. It is demonstrated that only on resonant excitations in the K (K') valley can the valley-related CPGE signals in multilayer MoS2 with an IL gate be detected, indicating that the valley contrast is indeed regenerated between the K and K' valleys when the electric field is applied. As expected, it can also be seen that the K (K') valley DOF in multilayer MoS2 can be modulated by the external electric field. The observation of photon wavelength dependent valley photocurrent in multilayer MoS2, with the help of better Ohmic contacts, may pave a way for optoelectronic applications of valleytronics in the future.

  12. Biexcitonic photocurrent induced by two-photon process at a telecommunication band

    International Nuclear Information System (INIS)

    Kodera, Tetsuo; Miyazawa, Toshiyuki; Kumagai, Naoto; Watanabe, Katsuyuki; Suzuki, Ayako; Takagi, Hiroyuki; Nakaoka, Toshihiro; Arakawa, Yasuhiko

    2009-01-01

    We report on photocurrent (PC) measurements of biexciton in a single self-assembled InAs quantum dot (QD) at a telecommunication wavelength of 1.3μm. We use shadow mask technique on an n-i Schottky photodiode structure with QDs to excite a single QD resonantly. Coherent pulse excitation is realized in two types of setups utilizing (i) an optical parametric oscillator and (ii) a stable semiconductor laser diode. In both setups we observe the biexcitonic PC peaks induced by a coherent two-photon process. Especially in the latter setups, the narrower pulse linewidth in energy provides a clearer biexcitonic PC peak because of reduced unwanted excitation. We estimate the binding energy ΔE B of our telecom-band biexciton to be 0.9 meV from the splitting between excitonic and biexcitonic resonances. The result suggests our telecom-band exciton-biexciton system is a good candidate for the building block of fiber-based controlled-rotation quantum logic operation. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  13. Definition of the electric requirements for the equipment associated to the limiter reactor on a 550 kV line occurring from manoeuvres under short circuits; Definicao dos requisitos eletricos dos equipamentos associados ao reator limitador em 550 kV, em decorrencia de manobras sob curtos-circuitos

    Energy Technology Data Exchange (ETDEWEB)

    Machado Junior, Camilo; Furuoka, Nita; Rose, Eber Havila [ELETRONORTE, Brasilia, DF (Brazil)]. E-mail: eber@eln.gov.br; Violin, Airton; Martinez, Manuel Luis Barreira [Escola Federal de Engenharia de Itajuba (EFEI), MG (Brazil). Inst. de Engenharia Eletrica. Lab. de Alta Tensao; Saraiva, Carlos Alberto Moura [Consorcio THEMAG-ENGEVIX, Sao Paulo, SP (Brazil)

    2001-07-01

    This paper presents the ascertaining based on the TRT study results performed to the definition of the new circuit breakers characteristics for the second stage of the Tucurui hydroelectric power plant, placed at the northern Brazil and with final configuration of two power houses and two air isolated substations, amounting 9 GVA. To reduce the short-circuit level to satisfactory values series reactors were used among the 550 kV substations. The result of the studies associated to the circuit breaker specifications are presented.

  14. A Low-Power CMOS Front-End for Photoplethysmographic Signal Acquisition With Robust DC Photocurrent Rejection.

    Science.gov (United States)

    Wong, A K Y; Kong-Pang Pun; Yuan-Ting Zhang; Ka Nang Leung

    2008-12-01

    A micro-power CMOS front-end, consisting of a transimpedance amplifier (TIA) and an ultralow cutoff frequency lowpass filter for the acquisition of photoplethysmographic signal (PPG) is presented. Robust DC photocurrent rejection for the pulsed signal source is achieved through a sample-and-hold stage in the feed-forward signal path and an error amplifier in the feedback path. Ultra-low cutoff frequency of the filter is achieved with a proposed technique that incorporates a pair of current-steering transistors that increases the effective filter capacitance. The design was realized in a 0.35-mum CMOS technology. It consumes 600 muW at 2.5 V, rejects DC photocurrent ranged from 100 nA to 53.6 muA, and achieves lower-band and upper-band - 3-dB cutoff frequencies of 0.46 and 2.8 Hz, respectively.

  15. A new time-dependent analytic model for radiation-induced photocurrent in finite 1D epitaxial diodes.

    Energy Technology Data Exchange (ETDEWEB)

    Verley, Jason C.; Axness, Carl L.; Hembree, Charles Edward; Keiter, Eric Richard; Kerr, Bert (New Mexico Institute of Mining and Technology, Socorro, NM)

    2012-04-01

    Photocurrent generated by ionizing radiation represents a threat to microelectronics in radiation environments. Circuit simulation tools such as SPICE [1] can be used to analyze these threats, and typically rely on compact models for individual electrical components such as transistors and diodes. Compact models consist of a handful of differential and/or algebraic equations, and are derived by making simplifying assumptions to any of the many semiconductor transport equations. Historically, many photocurrent compact models have suffered from accuracy issues due to the use of qualitative approximation, rather than mathematically correct solutions to the ambipolar diffusion equation. A practical consequence of this inaccuracy is that a given model calibration is trustworthy over only a narrow range of operating conditions. This report describes work to produce improved compact models for photocurrent. Specifically, an analytic model is developed for epitaxial diode structures that have a highly doped subcollector. The analytic model is compared with both numerical TCAD calculations, as well as the compact model described in reference [2]. The new analytic model compares well against TCAD over a wide range of operating conditions, and is shown to be superior to the compact model from reference [2].

  16. Combined effects of space charge and energetic disorder on photocurrent efficiency loss of field-dependent organic photovoltaic devices

    International Nuclear Information System (INIS)

    Yoon, Sangcheol; Hwang, Inchan; Park, Byoungchoo

    2015-01-01

    The loss of photocurrent efficiency by space-charge effects in organic solar cells with energetic disorder was investigated to account for how energetic disorder incorporates space-charge effects, utilizing a drift-diffusion model with field-dependent charge-pair dissociation and suppressed bimolecular recombination. Energetic disorder, which induces the Poole–Frenkel behavior of charge carrier mobility, is known to decrease the mobility of charge carriers and thus reduces photovoltaic performance. We found that even if the mobilities are the same in the absence of space-charge effects, the degree of energetic disorder can be an additional parameter affecting photocurrent efficiency when space-charge effects occur. Introducing the field-dependence parameter that reflects the energetic disorder, the behavior of efficiency loss with energetic disorder can differ depending on which charge carrier is subject to energetic disorder. While the energetic disorder that is applied to higher-mobility charge carriers decreases photocurrent efficiency further, the efficiency loss can be suppressed when energetic disorder is applied to lower-mobility charge carriers. (paper)

  17. Low temperature characterization of the photocurrent produced by two-photon transitions in a quantum dot intermediate band solar cell

    International Nuclear Information System (INIS)

    Antolin, E.; Marti, A.; Stanley, C.R.; Farmer, C.D.; Canovas, E.; Lopez, N.; Linares, P.G.; Luque, A.

    2008-01-01

    Conceived to exceed the conversion efficiency of conventional photovoltaic devices, the intermediate band solar cell bases its operation on exploiting, besides the usual band-to-band optical transitions, the absorption of two sub-bandgap photons. For the present, the only technology used to implement an intermediate band in real devices has been the growth of an InAs/GaAs quantum dot superlattice. In practice, the obtained material shows two limitations: the narrow energy gap between conduction and intermediate band and the appearance of growth defects due to the lattice stress. The consequences are the presence of non-radiative recombination mechanisms and the thermal escape of electrons from the intermediate to the conduction band, hindering the splitting of the quasi-Fermi levels associated with the intermediate and conduction bands and the observation of photocurrent associated with the two-photon absorption. By reducing the temperature at which the devices are characterised we have suppressed the parasitic thermal mechanisms and have succeeded in measuring the photocurrent caused by the absorption of two below bandgap photons. In this work, the characterization of this photocurrent at low temperature is presented and discussed

  18. Photocurrent characteristics of metal–AlGaN/GaN Schottky-on-heterojunction diodes induced by GaN interband excitation

    Science.gov (United States)

    Tang, Xi; Li, Baikui; Chen, Kevin J.; Wang, Jiannong

    2018-05-01

    The photocurrent characteristics of metal–AlGaN/GaN Schottky-on-heterojunction diodes were investigated. When the photon energy of incident light was larger than the bandgap of GaN but smaller than that of AlGaN, the alternating-current (ac) photocurrent measured using lock-in techniques increased with the chopper frequency. Analyzing the generation and flow processes of photocarriers revealed that the photocurrent induced by GaN interband excitation featured a transient behavior, and its direction reversed when the light excitation was removed. The abnormal dependence of the measured ac photocurrent magnitude on the chopper frequency was explained considering the detection principles of a lock-in amplifier.

  19. Controlled short-circuiting MIG-MAG welding process and procedures applied to the root pass in pipeline construction; Processo de soldagem MIG/MAG em curto-circuito controlado e procedimentos aplicados ao passe de raiz na construcao de linhas dutoviarias

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Regis H.G. e; Gohr Junior, Raul; Weck, Leonardo W.A. [Santa Catarina Univ., Florianopolis, SC (Brazil). Dept. de Engenharia Mecanica. Lab. de Soldagem e Mecatronica (LABSOLDA)

    2005-07-01

    The work deals with the study and development of the Controlled Short-Circuiting MIG/MAG Welding Process (CCC) and procedures for the root pass on pipes, in pipelines construction. The developed process (CCC) consists in an semi-automatic slag free operation, yielding higher productivity than the Coated Electrode and TIG processes, with satisfactory properties on the root weld. The significant influence of the welding over the time schedule and construction cost makes the development of this technology attractive, in order to become available at low cost, enhancing the companies' competitiveness in the globalized oil sector. The developed system, a MIG/MAG variant, features the advantages of short-circuiting metal transfer and avoids its inconveniences (mainly with high CO{sub 2} content gases), enabling its use on pipes root welding. This is possible through current waveform control, providing process and weld pool stability. Procedures for the root pass were determined for each of the welding positions reached in thick walled pipes welding, with the CCC. Also, the low welder training time was notable. (author)

  20. Analysis of electrical and thermal stress effects on PCBM:P3HT solar cells by photocurrent and impedance spectroscopy modeling

    DEFF Research Database (Denmark)

    Torto, Lorenzo; Rizzo, Antonio; Cester, Andrea

    2017-01-01

    We investigated the effects of electrical stress and thermal storage by means of photocurrent, Impedance Spectroscopy and Open Circuit Voltage Decay models. The electrical stress damages only the active layer, by reducing the generation rate, the polaron separation probability and the carrier...... lifetime. The thermal stress also degrades the anode interface. This reflects on the appearance of an inflection in the I-V photocurrent shape close to the operative region....

  1. Influence of double- and triple-layer antireflection coatings on the formation of photocurrents in multijunction III–V solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Musalinov, S. B.; Anzulevich, A. P.; Bychkov, I. V. [Chelyabinsk State University (Russian Federation); Gudovskikh, A. S. [Russian Academy of Sciences, St. Petersburg Academic University (Russian Federation); Shvarts, M. Z., E-mail: shvarts@scell.ioffe.ru [Russian Academy of Sciences, Ioffe Physical–Technical Institute (Russian Federation)

    2017-01-15

    The results of simulation by the transfer-matrix method of TiO{sub 2}/SiO{sub 2} double-layer and TiO{sub 2}/Si{sub 3}N{sub 4}/SiO{sub 2} triple-layer antireflection coatings for multijunction InGaP/GaAs/Ge heterostructure solar cells are presented. The TiO{sub 2}/SiO{sub 2} double-layer antireflection coating is experimentally developed and optimized. The experimental spectral dependences of the external quantum yield of the InGaP/GaAs/Ge heterostructure solar cell and optical characteristics of antireflection coatings, obtained in the simulation, are used to determine the photogenerated current densities of each subcell in the InGaP/GaAs/Ge solar cell under AM1.5D irradiation conditions (1000 W/m{sup 2}) and for the case of zero reflection loss. It is shown in the simulation that the optimized TiO{sub 2}/Si{sub 3}N{sub 4}/SiO{sub 2} triple-layer antireflection coating provides a 2.3 mA/cm{sup 2} gain in the photocurrent density for the Ge subcell under AM1.5D conditions in comparison with the TiO{sub 2}/SiO{sub 2} double-layer antireflection coating under consideration. This thereby provides an increase in the fill factor of the current–voltage curve and in the output electric power of the multijunction solar cell.

  2. Optical spectroscopy of the density of gap states in ETP-deposited a-Si:H

    NARCIS (Netherlands)

    Willekens, J.; Brinza, M.; Güngör, T.; Adriaenssens, G.J.; Nesladek, M.; Kessels, W.M.M.; Smets, A.H.M.; Sanden, van de M.C.M.

    2004-01-01

    The distribution and density of localized states in the band gap of hydrogenated amorphous silicon, as deposited by the expanding thermal plasma technique, were studied by means of a combined use of the constant photocurrent method (CPM), photothermal deflection spectroscopy (PDS) and time-of-flight

  3. Characterization of the voltage control systems and speed of a synchronous machine of high power for short circuit testing; Caracterizacion de los sistemas de control de voltaje y velocidad de una maquina sincrona de alta potencia para pruebas de corto circuito

    Energy Technology Data Exchange (ETDEWEB)

    Segura Ozuna, Victor Octavio; Hernandez Rodriguez, Isaura Victoria; Alcaide Godinez, Indira Xochiquetzal; Garduno Ramirez, Raul; Montero Cervantes, Julio Cesar [Instituto de Investigaciones Electricas, Cuernavaca, Morelos (Mexico); Ruiz Rodriguez, Genaro; Martinez Torres; Ricardo [CFE-LAPEM, Irapuato, Guanajuato (Mexico)

    2012-07-01

    This paper introduces a characterization of the behavior of the speed and voltage control systems of a special purpose synchronous machine (GCC) based on measuring and monitoring physical signals, and recording of the sampled waveforms. Basically, the GCC supplies the energy to perform high-power short-circuits tests to certify electrical equipment and components, as required by the Comision Federal de Electricidad (CFE) in Mexico. The GCC operates alternately as motor and generator. With the GCC operating as motor, speed control during startup, acceleration, re-acceleration and braking is carried out by a static frequency converter (SFC). Complementary, the voltage controller manipulates excitation power to control terminal voltage when the GCC operates as generator and regulates excitation current when the GCC operates as motor. Compared to conventional voltage regulation systems, which must go off in case of short-circuit, the GCC voltage regulator must keep controlling field excitation to maintain the required line current and terminal voltage during short-circuit tests. Monitoring of physical signals was carried out with a portable data acquisition system based on SCXI and PXI digital platforms. A total of 78 signals were monitored with a 6 kHz sampling rate that was enough to obtain detailed signal waveforms. Data captured was processed and plotted for analysis. The signal graphs show the current real behavior of both, the voltage control system and the speed control system, and constitute a precise characterization of their behavior. [Spanish] Este documento presenta una caracterizacion del comportamiento de los sistemas de control de velocidad y voltaje de una maquina sincrona de proposito especial (GCC) basada en la medicion y monitoreo de senales fisicas, asi como en el registro de las formas de onda muestreadas. Basicamente, la GCC suministra la energia para efectuar pruebas de corto circuito de alta potencia para certificar equipo y componentes

  4. Opto-electro-modulated transient photovoltage and photocurrent system for investigation of charge transport and recombination in solar cells.

    Science.gov (United States)

    Shi, Jiangjian; Li, Dongmei; Luo, Yanhong; Wu, Huijue; Meng, Qingbo

    2016-12-01

    An opto-electro-modulated transient photovoltage/photocurrent system has been developed to probe microscopic charge processes of a solar cell in its adjustable operating conditions. The reliability of this system is carefully determined by electric circuit simulations and experimental measurements. Using this system, the charge transport, recombination and storage properties of a conventional multicrystalline silicon solar cell under different steady-state bias voltages, and light illumination intensities are investigated. This system has also been applied to study the influence of the hole transport material layer on charge extraction and the microscopic charge processes behind the widely considered photoelectric hysteresis in perovskite solar cells.

  5. Graphene controlled H- and J-stacking of perylene dyes into highly stable supramolecular nanostructures for enhanced photocurrent generation

    DEFF Research Database (Denmark)

    Gan, Shiyu; Zhong, Lijie; Engelbrekt, Christian

    2014-01-01

    We report a new method for controlling H- and J-stacking in supramolecular self-assembly. Graphene nanosheets act as structure inducers to direct the self-assembly of a versatile organic dye, perylene into two distinct types of functional nanostructures, i.e. one-dimensional nanotubes via J......-stacking and two-dimensional branched nanobuds through H-stacking. Graphene integrated supramolecular nanocomposites are highly stable and show significant enhancement of photocurrent generation in these two configurations of photosensing devices, i.e. solid-state optoelectronic constructs and liquid...

  6. Initial surface film on magnesium metal: A characterization by X-ray photoelectron spectroscopy (XPS) and photocurrent spectroscopy (PCS)

    International Nuclear Information System (INIS)

    Santamaria, M.; Di Quarto, F.; Zanna, S.; Marcus, P.

    2007-01-01

    A detailed investigation of the initial film grown on mechanically polished Mg electrodes has been carried out by ex situ X-ray Photoelectron Spectroscopy (XPS) and in situ Photocurrent Spectroscopy (PCS), allowing to reach a detailed picture of the passive layer structure. The XPS data show that the films formed soon after mechanical treatment and immersion in aqueous electrolyte have a bilayer structure, consisting of an ultra-thin MgO inner layer (∼2.5 nm) and a Mg(OH) 2 external layer. The thickness of the Mg(OH) 2 layer is a function of immersion time and solution temperature. After mechanical treatment and immersion in aqueous solution at room temperature, the MgO/Mg(OH) 2 layer in some area of electrodes is so thin to allow an electron photoemission process from the Mg Fermi level to the electrolyte conduction band. Only internal photoemission processes are evidenced for Mg electrodes aged in NaOH at 80 deg. C, due the formation of a thicker Mg(OH) 2 layer. From anodic photocurrent spectra an optical band gap of ∼4.25 eV has been estimated for Mg(OH) 2 , lower with respect to the optical gap of the corresponding anhydrous counterpart

  7. Enhanced photocurrent in thin-film amorphous silicon solar cells via shape controlled three-dimensional nanostructures

    International Nuclear Information System (INIS)

    Hilali, Mohamed M; Banerjee, Sanjay; Sreenivasan, S V; Yang Shuqiang; Miller, Mike; Xu, Frank

    2012-01-01

    In this paper, we have explored manufacturable approaches to sub-wavelength controlled three-dimensional (3D) nano-patterns with the goal of significantly enhancing the photocurrent in amorphous silicon solar cells. Here we demonstrate efficiency enhancement of about 50% over typical flat a-Si thin-film solar cells, and report an enhancement of 20% in optical absorption over Asahi textured glass by fabricating sub-wavelength nano-patterned a-Si on glass substrates. External quantum efficiency showed superior results for the 3D nano-patterned thin-film solar cells due to enhancement of broadband optical absorption. The results further indicate that this enhanced light trapping is achieved with minimal parasitic absorption losses in the deposited transparent conductive oxide for the nano-patterned substrate thin-film amorphous silicon solar cell configuration. Optical simulations are in good agreement with experimental results, and also show a significant enhancement in optical absorption, quantum efficiency and photocurrent. (paper)

  8. Large enhancement in photocurrent by Mn doping in CdSe/ZTO quantum dot sensitized solar cells.

    Science.gov (United States)

    Pimachev, Artem; Poudyal, Uma; Proshchenko, Vitaly; Wang, Wenyong; Dahnovsky, Yuri

    2016-09-29

    We find a large enhancement in the efficiency of CdSe quantum dot sensitized solar cells by doping with manganese. In the presence of Mn impurities in relatively small concentrations (2.3%) the photoelectric current increases by up to 190%. The average photocurrent enhancement is about 160%. This effect cannot be explained by a light absorption mechanism because the experimental and theoretical absorption spectra demonstrate that there is no change in the absorption coefficient in the presence of the Mn impurities. To explain such a large increase in the injection current we propose a tunneling mechanism of electron injection from the quantum dot LUMO state to the Zn 2 SnO 4 (ZTO) semiconductor photoanode. The calculated enhancement is approximately equal to 150% which is very close to the experimental average value of 160%. The relative discrepancy between the calculated and experimentally measured ratios of the IPCE currents is only 6.25%. For other mechanisms (such as electron trapping, etc.) the remaining 6.25% cannot explain the large change in the experimental IPCE. Thus we have indirectly proved that electron tunneling is the major mechanism of photocurrent enhancement. This work proposes a new approach for a significant improvement in the efficiency of quantum dot sensitized solar cells.

  9. Effect of the polymeric coating thickness on the photocurrent performance of titanium dioxide nanorod arrays-polyaniline composite-based UV photosensor

    Science.gov (United States)

    Yusoff, M. M.; Mamat, M. H.; Malek, M. F.; Othman, , N.; Ismail, A. S.; Saidi, S. A.; Mohamed, R.; Suriani, A. B.; Khusaimi, Z.; Rusop, M.

    2018-05-01

    Titanium dioxide (TiO2) nanorod arrays (TNAs) were synthesized and deposited on fluorine tin oxide (FTO)-coated glass substrate using a one-step immersion method in a glass container. The effect of the polymeric coating thickness of p-type polyaniline (PANI) on the n-type TNAs was investigated in the p-n heterojunction photodiode (PD) for the application of ultraviolet (UV) photosensor. The fabricated photosensor demonstrated an increased photocurrent under UV irradiation in correlation with the thickness layer of PANI. The measured UV response showed the highest photocurrent of 0.014 µA at 1.0 V of reverse bias with low dark current under the UV radiation (365 nm, 750 µW/cm2). The thickness of the PANI film improved the photocurrent of the fabricated TNAs/PANI composite-based UV photosensor.

  10. Development of a transient photocurrent response method for non-destructive analysis of defects in solar cells; Entwicklung einer Transient Photocurrent Response-Methode zur zerstoerungsfreien Untersuchung von Stoerstellen in Solarzellen

    Energy Technology Data Exchange (ETDEWEB)

    Sperling, A

    1995-01-01

    A new measuring method for the destruction-free characterisation of impurities in basically large-surface [(20x20) mm{sup 2}]solar cells or photo detectors is explained. During this TPCR measuring method the transient photocurrent signal, generated by a repeating, rectangular, monochromatic irradiation, is recorded in dependence on the darkness between the irradiation pulses and on the temperature of the cells. (orig.) [Deutsch] Es wird ein neues Messverfahren zur zerstoerungsfreien Charakterisierung von Verunreinigungen in der Basis grossflaechiger [(20x20) mm{sup 2}] Solarzellen bzw. Photodetektoren vorgestellt. Bei diesem TPCR-Messverfahren wird das durch eine repetierende, rechteckfoermige, monochromatische Bestrahlung erzeugte transiente Photostrom-Signal in Abhaengigkeit von der Dunkelzeit zwischen den Bestrahlungspulsen und von der Tempeatur der Zelle aufgenommen. (orig./HW)

  11. Electric field dependent photocurrent generation in a thin-film organic photovoltaic device with a [70]fullerene-benzodifuranone dyad.

    Science.gov (United States)

    Ulmann, Pirmin A; Tanaka, Hideyuki; Matsuo, Yutaka; Xiao, Zuo; Soga, Iwao; Nakamura, Eiichi

    2011-12-21

    A [70]fullerene-benzodifuranone acceptor dyad synthesized by a Ag⁺-mediated coupling reaction was used to construct a thin-film organic solar cell. The fullerene and the benzodifuranone dye in the dyad have close-lying LUMO levels in the range of 3.7-3.9 eV, so that energy transfer from the dye to the fullerene can take place. A p-n heterojunction photovoltaic device consisting of a tetrabenzoporphyrin and a [70]fullerene-benzodifuranone dyad showed a weak but discernible contribution from light absorption of the dyad to the photocurrent under both a positive and a negative effective bias. These results indicate that the benzodifuranone moiety attached to the acceptor contributes to light-harvesting by energy transfer.

  12. Terahertz radiation by subpicosecond spin-polarized photocurrent originating from Dirac electrons in a Rashba-type polar semiconductor

    Science.gov (United States)

    Kinoshita, Yuto; Kida, Noriaki; Miyamoto, Tatsuya; Kanou, Manabu; Sasagawa, Takao; Okamoto, Hiroshi

    2018-04-01

    The spin-splitting energy bands induced by the relativistic spin-orbit interaction in solids provide a new opportunity to manipulate the spin-polarized electrons on the subpicosecond timescale. Here, we report one such example in a bulk Rashba-type polar semiconductor BiTeBr. Strong terahertz electromagnetic waves are emitted after the resonant excitation of the interband transition between the Rashba-type spin-splitting energy bands with a femtosecond laser pulse circularly polarized. The phase of the emitted terahertz waves is reversed by switching the circular polarization. This suggests that the observed terahertz radiation originates from the subpicosecond spin-polarized photocurrents, which are generated by the asymmetric depopulation of the Dirac state. Our result provides a way for the current-induced terahertz radiation and its phase control by the circular polarization of incident light without external electric fields.

  13. Sub-bandgap response of graphene/SiC Schottky emitter bipolar phototransistor examined by scanning photocurrent microscopy

    Science.gov (United States)

    Barker, Bobby G., Jr.; Chava, Venkata Surya N.; Daniels, Kevin M.; Chandrashekhar, M. V. S.; Greytak, Andrew B.

    2018-01-01

    Graphene layers grown epitaxially on SiC substrates are attractive for a variety of sensing and optoelectronic applications because the graphene acts as a transparent, conductive, and chemically responsive layer that is mated to a wide-bandgap semiconductor with large breakdown voltage. Recent advances in control of epitaxial growth and doping of SiC epilayers have increased the range of electronic device architectures that are accessible with this system. In particular, a recently-introduced Schottky-emitter bipolar phototransistor (SEPT) based on an epitaxial graphene (EG) emitter grown on a p-SiC base epilayer has been found to exhibit a maximum common emitter current gain of 113 and a UV responsivity of 7.1 A W-1. The behavior of this device, formed on an n +-SiC substrate that serves as the collector, was attributed to a very large minority carrier injection efficiency at the EG/p-SiC Schottky contact. This large minority carrier injection efficiency is in turn related to the large built-in potential found at a EG/p-SiC Schottky junction. The high performance of this device makes it critically important to analyze the sub bandgap visible response of the device, which provides information on impurity states and polytype inclusions in the crystal. Here, we employ scanning photocurrent microscopy (SPCM) with sub-bandgap light as well as a variety of other techniques to clearly demonstrate a localized response based on the graphene transparent electrode and an approximately 1000-fold difference in responsivity between 365 nm and 444 nm excitation. A stacking fault propagating from the substrate/epilayer interface, assigned as a single layer of the 8H-SiC polytype within the 4H-SiC matrix, is found to locally increase the photocurrent substantially. The discovery of this polytype heterojunction opens the potential for further development of heteropolytype devices based on the SEPT architecture.

  14. Density and mobility effects of the majority carriers in organic semiconductors under light excitation

    Energy Technology Data Exchange (ETDEWEB)

    Vagenas, N.; Giannopoulou, A.; Kounavis, P., E-mail: pkounavis@upatras.gr [Department of Electrical and Computer Engineering, University of Patras, 26504 Patra (Greece)

    2015-01-21

    This study demonstrates that the effect of light excitation on the density and the mobility of the majority carriers can be explored in organic semiconductors by modulated photocurrent spectroscopy. The spectra of phase and amplitude of the modulated photocurrent of pentacene films indicate a significant increase in the density of the photogenerated mobile holes (majority carriers). This increase is accompanied by a comparatively much smaller increase of the steady state photocurrent response which can be reconciled with a decrease in the mobility (μ) of holes. The decrease of μ is supported from an unusual increase of the Y/μ ratio of the out-of-phase modulated photocurrent (Y) signal to the mobility under light excitation. It is proposed that the mobile holes, which are generated from the dissociation of the light-created excitons more likely near the pentacene-substrate interface by electron trapping, populate grain boundaries charging them and producing a downward band bending. As a result, potential energy barriers are build up which limit the transport of holes interacting through trapping-detrapping with deep partially occupied traps in the charged grain boundaries. On the other hand, the transport of holes interacting through trapping-detrapping with empty traps is found unaffected.

  15. Lateral electrical transport, optical properties and photocurrent measurements in two-dimensional arrays of silicon nanocrystals embedded in SiO2

    Directory of Open Access Journals (Sweden)

    Gardelis Spiros

    2011-01-01

    Full Text Available Abstract In this study we investigate the electronic transport, the optical properties, and photocurrent in two-dimensional arrays of silicon nanocrystals (Si NCs embedded in silicon dioxide, grown on quartz and having sizes in the range between less than 2 and 20 nm. Electronic transport is determined by the collective effect of Coulomb blockade gaps in the Si NCs. Absorption spectra show the well-known upshift of the energy bandgap with decreasing NC size. Photocurrent follows the absorption spectra confirming that it is composed of photo-generated carriers within the Si NCs. In films containing Si NCs with sizes less than 2 nm, strong quantum confinement and exciton localization are observed, resulting in light emission and absence of photocurrent. Our results show that Si NCs are useful building blocks of photovoltaic devices for use as better absorbers than bulk Si in the visible and ultraviolet spectral range. However, when strong quantum confinement effects come into play, carrier transport is significantly reduced due to strong exciton localization and Coulomb blockade effects, thus leading to limited photocurrent.

  16. Observation of Switchable Photoresponse of a Monolayer WSe 2 –MoS 2 Lateral Heterostructure via Photocurrent Spectral Atomic Force Microscopic Imaging

    KAUST Repository

    Son, Youngwoo; Li, Ming-yang; Cheng, Chia-Chin; Wei, Kung-Hwa; Liu, Pingwei; Wang, Qing Hua; Li, Lain-Jong; Strano, Michael S.

    2016-01-01

    spectral atomic force microscopy to image the current and photocurrent generated between a biased PtIr tip and a monolayer WSe2-MoS2 lateral heterostructure. Current measurements in the dark in both forward and reverse bias reveal an opposite characteristic

  17. Comportamiento del tiempo de duración, la frecuencia de los cortocircuitos y la conductividad eléctrica durante el reencendido del arco en la soldadura SMAW (AC con electrodos E6013 Behavior of short-circuit frequency and duration time and electrical conductivity on arc turn- on during SMAW (AC with E6013 electrodes

    Directory of Open Access Journals (Sweden)

    Alejandro García Rodríguez

    2009-03-01

    Full Text Available El presente trabajo tiene como objetivo la evaluación del comportamiento del tiempo de duración, la frecuencia de los cortocircuitos y la conductividad durante el reencendido del arco en el proceso de soldadura SMAW (Shielded Metal Arc Welding, con corriente alterna y electrodos E6013. El análisis estadístico no-paramétrico garantiza un procesamiento robusto de los datos, atenuando la influencia de valores atípicos y errores derivados del empleo de aproximaciones a distribuciones continuas conocidas. La mediana y la mediana de la desviación absoluta (MAD, respecto a la mediana de los datos, constituyen los estimadores de localización y dispersión utilizados, respectivamente. El electrodo, en el régimen de 160 A, presenta una mayor estabilidad, en el aporte metálico, dada por el menor valor del MAD promedio del período de cortocircuito (39,36 ms y de la duración del cortocircuito (1,43 ms, reafirmada con la presencia de una mayor conductividad eléctrica durante el reencendido (1766,17x10-3 S·s-1.The objective of this work is the valuation of the behavior of short-circuits frequency and duration time and electrical conductivity on arc reigniting in SMAW (Shielded Metal Arc Welding process with alternate current and E6013 electrodes. The non parametric statistic analysis realize a robust data processing, minimizing the outliers influence and mistakes derivates about employ of approximations to well know continues distributions. The median and the median absolute deviation (MAD respect to median of the data are the localization and dispersion estimators used, respectively. The electrode at 160 A present a better stability on metal transference supported on the most little value of MAD for the period of transference (39,36 ms, and the MAD of the short-circuit duration (1,43 ms, according with the presence of a major electric conductivity during the arc reigniting (1766,17x10-3 S·s-1.

  18. The Effect of Electron versus Hole Photocurrent on Optoelectric Properties of p+-p-n-n+ Wz-GaN Reach-Through Avalanche Photodiodes

    Directory of Open Access Journals (Sweden)

    Moumita Ghosh

    2013-01-01

    Full Text Available The authors have made an attempt to investigate the effect of electron versus hole photocurrent on the optoelectric properties of p+-p-n-n+ structured Wurtzite-GaN (Wz-GaN reach-through avalanche photodiodes (RAPDs. The photo responsivity and optical gain of the devices are obtained within the wavelength range of 300 to 450 nm using a novel modeling and simulation technique developed by the authors. Two optical illumination configurations of the device such as Top Mounted (TM and Flip Chip (FC are considered for the present study to investigate the optoelectric performance of the device separately due to electron dominated and hole dominated photocurrents, respectively, in the visible-blind ultraviolet (UV spectrum. The results show that the peak unity gain responsivity and corresponding optical gain of the device are 555.78 mA W−1 and 9.4144×103, respectively, due to hole dominated photocurrent (i.e., in FC structure; while those are 480.56 mA W−1 and 7.8800×103, respectively, due to electron dominated photocurrent (i.e., in TM structure at the wavelength of 365 nm and for applied reverse bias of 85 V. Thus, better optoelectric performance of Wz-GaN RAPDs can be achieved when the photocurrent is made hole dominated by allowing the UV light to be shined on the n+-layer instead of p+-layer of the device.

  19. Internal Short Circuits in Lithium-Ion Cells for PHEVs

    Energy Technology Data Exchange (ETDEWEB)

    Sriramulu, Suresh [Tiax LLC, Lexington, MA (United States); Stringfellow, Richard [Tiax LLC, Lexington, MA (United States)

    2013-05-25

    Development of Plug-in Hybrid Electric Vehicles (PHEVs) has recently become a high national priority because of their potential to enable significantly reduced petroleum consumption by the domestic transportation sector in the relatively near term. Lithium-ion (Li-ion) batteries are a critical enabling technology for PHEVs. Among battery technologies with suitable operating characteristics for use in vehicles, Li-ion batteries offer the best combination of energy, power, life and cost. Consequently, worldwide, leading corporations and government agencies are supporting the development of Li-ion batteries for PHEVs, as well as the full spectrum of vehicular applications ranging from mild hybrid to all-electric. In this project, using a combination of well-defined experiments, custom designed cells and simulations, we have improved the understanding of the process by which a Li-ion cell that develops an internal short progresses to thermal runaway. Using a validated model for thermal runaway, we have explored the influence of environmental factors and cell design on the propensity for thermal runaway in full-sized PHEV cells. We have also gained important perspectives about internal short development and progression; specifically that initial internal shorts may be augmented by secondary shorts related to separator melting. Even though the nature of these shorts is very stochastic, we have shown the critical and insufficiently appreciated role of heat transfer in influencing whether a developing internal short results in a thermal runaway. This work should lead to enhanced perspectives on separator design, the role of active materials and especially cathode materials with respect to safety and the design of automotive cooling systems to enhance battery safety in PHEVs.

  20. Short circuit signatures from different wind turbine generator types

    DEFF Research Database (Denmark)

    Martinez, Jorge; Kjær, Philip C.; Rodriguez, Pedro

    2011-01-01

    Modern wind power plants are required and designed to ride through faults in the network, subjected to the fault clearance and following grid code demands. Beside voltage support during faults, the wind turbine fault current contribution is important to establish the correct settings for the relay...... of the protections. The following wind turbine generator during faults have been studied: (i) induction generator, (ii) induction generator with variable rotor resistance (iii) converter-fed rotor (often referred to as DFIG) and (iv) full scale converter. To make a clear comparison and performance analysis during...... faults, and the consequent effects on substation protections, the aforementioned configurations have been simulated using PSCAD/EMTDC, with the same power plant configuration, electrical grid and generator data. Additionally, a comparison of these wind turbine technologies with a conventional power plant...

  1. Limitation of short-circuit power due to distributed generation

    NARCIS (Netherlands)

    Morren, J.; Reckers, T.J.M.; Berende, M.J.C.; Slootweg, J.G.

    2012-01-01

    Introduction of DG units in the network will result in increasing fault current levels. In this contribution several solutions are described to limit the fault currents in the network, in order to avoid overloading and destruction of components in the networks. The main focus of the paper is on the

  2. Short-Circuiting the Bureaucracy: Policy Origins in Education.

    Science.gov (United States)

    Graham, Hugh Davis

    The Great Society's secret task forces created by Lyndon Johnson, particularly in the case-study area of federal education policy, show the use and misuse of the task force device. Modern use of it began with John F. Kennedy. Although he used the task force device effectively sometimes, he did not use it effectively in his educational programs in…

  3. Short-circuiting magma differentiation from basalt straight to rhyolite?

    Science.gov (United States)

    Ruprecht, P.; Winslow, H.

    2017-12-01

    Silicic magmas are the product of varying degrees of crystal fractionation and crustal assimilation/melting. Both processes lead to differentiation that is step-wise rather than continuous for example during melt separation from a crystal mush (Dufek and Bachmann, 2010). However, differentiation is rarely efficient enough to evolve directly from a basaltic to a rhyolitic magma. At Volcán Puyehue-Cordón Caulle, Chile, the magma series is dominated by crystal fractionation where mixing trends between primitive and felsic end members in the bulk rock compositions are almost absent (e.g. P, FeO, TiO2 vs. SiO2). How effective fraction is in this magmatic system is not well-known. The 2011-12 eruption at Cordón Caulle provides new constraints that rhyolitic melts may be derived directly from a basaltic mush. Minor, but ubiquitous mafic, crystal-rich enclaves co-erupted with the predominantly rhyolitic near-aphyric magma. These enclaves are among the most primitive compositions erupted at Puyehue-Cordón Caulle and geochemically resemble closely basaltic magmas that are >10 ka old (Singer et al. 2008) and that have been identified as a parental tholeiitic mantle-derived magma (Schmidt and Jagoutz, 2017) for the Southern Andean Volcanic Zone. The vesiculated nature, the presence of a microlite-rich groundmass, and a lack of a Eu anomaly in these encalves suggest that they represent recharge magma/mush rather than sub-solidus cumulates and therefore have potentially a direct petrogenetic link to the erupted rhyolites. Our results indicate that under some conditions crystal fractionation can be very effective and the presence of rhyolitic magmas does not require an extensive polybaric plumbing system. Instead, primitive mantle-derived magmas source directly evolved magmas. In the case, of the magma system beneath Puyehue-Cordón Caulle, which had three historic rhyolitic eruptions (1921-22, 1960, 2011-12) these results raise the question whether rhyolite magma extraction has been efficient for multiple eruptions? References: Dufek & Bachmann (2010) Geology 38, 687-690; Schmidt & Jagoutz (2017) G-cubed, doi: 10.1002/2016GC006699; Singer et al. (2008) GSA Bulletin 120, 599-618.

  4. Proposed budget cuts threaten to short-circuit Grid network

    CERN Multimedia

    Butler, D

    2001-01-01

    Changes to the budget for the European sixth Framework programme may jeapardize the Grid project. The EU Parliament have asked to cut the budget for infrastructure to 500 million euros from 900 and of this 150 million will probably be allocated to Ge the pan-European research network (1 page).

  5. Opto-mechano-electrical tripling in ZnO nanowires probed by photocurrent spectroscopy in a high-resolution transmission electron microscope

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, C.; Golberg, D., E-mail: xuzhi@iphy.ac.cn, E-mail: golberg.dmitri@nims.go.jp [International Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science (NIMS), Namiki 1-1, Tsukuba, Ibaraki 3050044 (Japan); Graduate School of Pure and Applied Sciences, University of Tsukuba, Tennodai 1, Tsukuba, Ibaraki 3058577 (Japan); Xu, Z., E-mail: xuzhi@iphy.ac.cn, E-mail: golberg.dmitri@nims.go.jp [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Kvashnin, D. G. [National University of Science and Technology, MISIS, Leninskiy Prospect 4, Moscow 119049 (Russian Federation); Tang, D.-M.; Xue, Y. M.; Bando, Y. [International Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science (NIMS), Namiki 1-1, Tsukuba, Ibaraki 3050044 (Japan); Sorokin, P. B. [National University of Science and Technology, MISIS, Leninskiy Prospect 4, Moscow 119049 (Russian Federation); Moscow Institute of Physics and Technology, Institutsky Lane 9, Dolgoprudny 141700 (Russian Federation)

    2015-08-31

    Photocurrent spectroscopy of individual free-standing ZnO nanowires inside a high-resolution transmission electron microscope (TEM) is reported. By using specially designed optical in situ TEM system capable of scanning tunneling microscopy probing paired with light illumination, opto-mechano-electrical tripling phenomenon in ZnO nanowires is demonstrated. Splitting of photocurrent spectra at around 3.3 eV under in situ TEM bending of ZnO nanowires directly corresponds to nanowire deformation and appearance of expanded and compressed nanowire sides. Theoretical simulation of a bent ZnO nanowire has an excellent agreement with the experimental data. The splitting effect could be explained by a change in the valence band structure of ZnO nanowires due to a lattice strain. The strain-induced splitting provides important clues for future flexible piezo-phototronics.

  6. Effect of top gate bias on photocurrent and negative bias illumination stress instability in dual gate amorphous indium-gallium-zinc oxide thin-film transistor

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Eunji; Chowdhury, Md Delwar Hossain; Park, Min Sang; Jang, Jin, E-mail: jjang@khu.ac.kr [Advanced Display Research Center and Department of Information Display, Kyung Hee University, Seoul 130-701 (Korea, Republic of)

    2015-12-07

    We have studied the effect of top gate bias (V{sub TG}) on the generation of photocurrent and the decay of photocurrent for back channel etched inverted staggered dual gate structure amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film-transistors. Upon 5 min of exposure of 365 nm wavelength and 0.7 mW/cm{sup 2} intensity light with negative bottom gate bias, the maximum photocurrent increases from 3.29 to 322 pA with increasing the V{sub TG} from −15 to +15 V. By changing V{sub TG} from negative to positive, the Fermi level (E{sub F}) shifts toward conduction band edge (E{sub C}), which substantially controls the conversion of neutral vacancy to charged one (V{sub O} → V{sub O}{sup +}/V{sub O}{sup 2+} + e{sup −}/2e{sup −}), peroxide (O{sub 2}{sup 2−}) formation or conversion of ionized interstitial (O{sub i}{sup 2−}) to neutral interstitial (O{sub i}), thus electron concentration at conduction band. With increasing the exposure time, more carriers are generated, and thus, maximum photocurrent increases until being saturated. After negative bias illumination stress, the transfer curve shows −2.7 V shift at V{sub TG} = −15 V, which gradually decreases to −0.42 V shift at V{sub TG} = +15 V. It clearly reveals that the position of electron quasi-Fermi level controls the formation of donor defects (V{sub O}{sup +}/V{sub O}{sup 2+}/O{sub 2}{sup 2−}/O{sub i}) and/or hole trapping in the a-IGZO /interfaces.

  7. Study on photocurrent of bilayers photoanodes using different combination of WO{sub 3} and Fe{sub 2}O{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Memar, Amir; Daud, Wan Ramli Wan; Eftekhari, Ehsan; Minggu, Lorna Jeffery [Institute of Fuel Cell, University Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia); Hosseini, Soraya [Department Chemical and Environmental Engineering, University Putra Malaysia, 43400 UPM Serdang, Selangor (Malaysia)

    2010-08-15

    Bilayer photoanodes were prepared onto glass substrates (FTO) in order to improve generated photocurrents using UV-vis light by water splitting process. A comparative study of photocatalytic was performed over the films surface using Fe{sub 2}O{sub 3,} WO{sub 3} and mixture of bicomponents (Fe{sub 2}O{sub 3}:WO{sub 3}). Different types of films were prepared using Fe{sub 2}O{sub 3,} WO{sub 3} and bicomponents (mixture) on FTO substrates. The films were grown by sol gel method with the PEG-300 as the structure-directing agent. The photo-generated of the samples were determined by measuring the currents and voltages under illumination of UV-vis light. The morphology, structure and related composition distribution of the films have been characterized by SEM, XRD and EDX respectively. Photocurrent measurements indicated surface roughness as the effective parameter in this study. The deposited surfaces by bicomponents or mixture are flat without any feature on the surface while the deposited surfaces by WO{sub 3} appears rough surface as small round (egg-shaped particles) and cauliflower-like. The surface deposited by Fe{sub 2}O{sub 3} show rough no as well as WO{sub 3} surface. The deposited surfaces by WO{sub 3} reveal the higher value of photocurrent measurement due to surface roughness. Indeed, the roughness can be effective in increasing contact surface area between film and electrolyte and diffuse reflection (light scattering effect). The solution (Fe{sub 2}O{sub 3}:WO{sub 3}) shows the low photocurrent value in compare to WO{sub 3} and Fe{sub 2}O{sub 3} hat it may be due to decomposition the compound at 450 {+-} 1 C to iron-tungstate Fe{sub 2}(WO{sub 4}){sub 3}. (author)

  8. Photocurrent increase by metal modification of Fe{sub 2}O{sub 3} photoanodes and its effect on photoelectrocatalytic hydrogen production by degradation of organic substances

    Energy Technology Data Exchange (ETDEWEB)

    Iervolino, Giuseppina [Department of Industrial Engineering, University of Salerno, Via Giovanni Paolo II, 132, Fisciano, Salerno, Italy, (Italy); Tantis, Iosif [Department of Chemical Engineering, University of Patras, 26500, Patras (Greece); Sygellou, Lamprini [FORTH/ICE-HT, P.O. Box 1414, 26504, Patras (Greece); Vaiano, Vincenzo, E-mail: vvaiano@unisa.it [Department of Industrial Engineering, University of Salerno, Via Giovanni Paolo II, 132, Fisciano, Salerno, Italy, (Italy); Sannino, Diana [Department of Industrial Engineering, University of Salerno, Via Giovanni Paolo II, 132, Fisciano, Salerno, Italy, (Italy); Lianos, Panagiotis, E-mail: lianos@upatras.gr [Department of Chemical Engineering, University of Patras, 26500, Patras (Greece)

    2017-04-01

    Highlights: • Metals-modified hematite photoanodes prepared by electrodeposition method. • Ti and Ni-modified hematite thin films showed the higher photocurrents values. • The optimal loading of modifier was found at nominal 1% for Ni and 3% for Ti. • The highest H2 production was obtained on 3%Ti-Fe2O3 in the presence of glucose. - Abstract: The present work reports the investigation of photocurrent increase by metal modification of Fe{sub 2}O{sub 3} photoanodes and its effect on photoelectrocatalytic hydrogen production using aqueous solutions containing various organic compounds. Fe{sub 2}O{sub 3} photoanodes were prepared by the electrodeposition method. The efficiency of various metal modifiers of the hematite structure (Ti, Ni, Sn, Co and Cu) has been tested by monitoring the photoelectrochemical behavior of the ensuing photoanodes. Hydrogen production was monitored in an H-shaped reactor using pure and metal-modified hematite films deposited on FTO electrodes as photocatalyst while a combination of commercial carbon paste with dispersed Pt nanoparticles was used as electrocatalyst. In all cases, hydrogen production was obtained by application of a small external electric bias (in the range 0.5- 0.7 V vs Ag/AgCl electrode). Highest photocurrent production has been achieved with a Ti-modified Fe{sub 2}O{sub 3} photoanode in the presence of glucose as sacrificial agent.

  9. Influencia de la generación distribuida en los niveles de cortocircuito y en las protecciones eléctricas en subestaciones de 110 / 34,5 kV; The effects caused due to the introduction of Distribution Generation in the short-circuit levels and the protecti

    Directory of Open Access Journals (Sweden)

    Marta Bravo de las Casas

    2011-02-01

    Full Text Available En este trabajo se muestran algunos resultados de los efectos provocados por la introducción de la GD enlas redes cubanas en lo que respecta a los niveles de cortocircuito y los ajustes de las protecciones en cincosubestaciones de 110 / 34,5 kV ubicadas en las provincias de Villa Clara, Cienfuegos y Sancti Spíritus. Seobtuvieron conclusiones importantes con respecto a las necesidades de funciones de protección y criteriosde ajuste de las protecciones. Además, con respecto a la necesidad de tener en las subestaciones relésdigitales modernos con el fin de que puedan responder correctamente y en el menor tiempo posible a losdiferentes escenarios de operación que tendrá el sistema en las nuevas condiciones y así corresponder a lasexigencias que impone la GD a los esquemas de protección. In this article, results are shown of the effects caused due to the introduction of Distribution Generation(DG in the Cuban Networks with respect to short-circuit levels and the protection settings of five 110/34.5kV substations located in the provinces of Villa Clara, Cienfuegos y Sancti Spíritus. Important conclusionshave been obtained with respect to the necessities of the protection functions and their settings criteria.Besides, with respect to the necessity of having modern digital relays in order to respond correctly and inthe least possible time to the different stages of operation that the system may have in the new conditionsof operation and in this manner corresponds to the demands that the DG imply in protection systems. 

  10. Road density

    Data.gov (United States)

    U.S. Environmental Protection Agency — Road density is generally highly correlated with amount of developed land cover. High road densities usually indicate high levels of ecological disturbance. More...

  11. Lung density

    DEFF Research Database (Denmark)

    Garnett, E S; Webber, C E; Coates, G

    1977-01-01

    The density of a defined volume of the human lung can be measured in vivo by a new noninvasive technique. A beam of gamma-rays is directed at the lung and, by measuring the scattered gamma-rays, lung density is calculated. The density in the lower lobe of the right lung in normal man during quiet...... breathing in the sitting position ranged from 0.25 to 0.37 g.cm-3. Subnormal values were found in patients with emphsema. In patients with pulmonary congestion and edema, lung density values ranged from 0.33 to 0.93 g.cm-3. The lung density measurement correlated well with the findings in chest radiographs...... but the lung density values were more sensitive indices. This was particularly evident in serial observations of individual patients....

  12. Fabrication and high visible-light-driven photocurrent response of g-C{sub 3}N{sub 4} film: The role of thiourea

    Energy Technology Data Exchange (ETDEWEB)

    Ye, Lijuan; Chen, Shijian, E-mail: sjchen@cqu.edu.cn

    2016-12-15

    Highlights: • Thiourea promotes the growth and crystalline of the g-C{sub 3}N{sub 4} films on ITO. • Thiourea introduces S dopants into the g-C{sub 3}N{sub 4} films. • The obtained S-doped g-C{sub 3}N{sub 4} thin films show high VLD photocurrent response. • Three heterojunction structure types based on the g-C{sub 3}N{sub 4} films are proposed. - Abstract: We report on a convenient CVD fabrication of the uniform, compact and reproducible g-C{sub 3}N{sub 4} solid films on indium-tin oxide substrates. It is found that mixing quantitative thiourea into melamine as co-precursor prompts the deposition of greenish-yellow, transparent and smooth g-C{sub 3}N{sub 4} thin films. The thiourea apparently affects the crystalline, the surface morphologies and the energy band structures of g-C{sub 3}N{sub 4} films by modulating the polymerization process of the precursors, and simultaneously introduces S dopants into the g-C{sub 3}N{sub 4} films. Due to these roles of thiourea, the obtained S-doped g-C{sub 3}N{sub 4} films as a photoelectrode show a high and stable visible-light-driven photocurrent response. To further improve the photocurrent, the construction of three heterojunction structure types based on g-C{sub 3}N{sub 4} films is proposed and the corresponding charge transfer mechanisms are well discussed. The successful fabrication of high quality g-C{sub 3}N{sub 4} films in this work provides a footstone to construct the heterojunction film structures based on the carbon nitrides for the photoelectrochemical overall water splitting.

  13. pH-induced photocurrent switching based on a highly stable drop-casting film of imidazole moiety-containing dinuclear Ru(II) Complex

    International Nuclear Information System (INIS)

    Xue, Long-Xin; Duan, Zhi-Ming; Jia, Jia; Wang, Ke-Zhi; Haga, Masa-aki

    2014-01-01

    Graphical abstract: > Solvent-casting Ru(II) complex modified electrode. > Positive shifting of half-wave potentials of Ru(III)/Ru(II) by pH decreases. > Greatly enhanced cathodic photocurrents by pH decreases. - Highlights: • Solvent-casting Ru(II) complex modified electrode. • Positive shifting of half-wave potentials of Ru(III)/Ru(II) by pH decreases. • Greatly enhanced cathodic photocurrents by pH decreases. - Abstract: A new dinuclear Ru(II) complex of [(H 2 L 1 )Ru(H 2 L 2 )Ru(H 2 L 1 )](ClO 4 ) 4 {H 2 L 1 = 2,6-bis(2-benzimidazolyl)pyridine; H 2 L 2 = 2,6-bis(4-([2,2′:6′,2″-terpyridin]-4′-yl)phenyl)-1,5- dihydrobenzo[1,2-d:4,5-d’]diimidazole} is synthesized and characterized. The Ru(II) complex modified indium-tin oxide electrode prepared using a drop-casting method, exhibited a couple of stable surface-confined Ru(III)/Ru(II)-based redox waves centered at +0.65 V vs saturated calomel electrode that were almost unchanged after 50 consecutive cyclic voltammetry scanning. The modified electrode showed pH-dependent redox behaviors with the formal potential being decreased by 430 mV due to the occurrance of the proton-coupled redox reactions. The cathodic photocurrent generation of the modified electrode was also found to be highly pH-dependent, switching from an “off” state at pH ∼11.0 to an “on” state at pH = 2.20 with an enhancement factor of 18. The modified electrode was shown to have promising applications as photoelectrochemical pH sensing and switching devices

  14. Broadband photocurrent enhancement and light-trapping in thin film Si solar cells with periodic Al nanoparticle arrays on the front

    DEFF Research Database (Denmark)

    Uhrenfeldt, C.; Villesen, T. F.; Tetu, A.

    2015-01-01

    Plasmonic resonances in metal nanoparticles are considered candidates for improved thin film Si photovoltaics. In periodic arrays the influence of collective modes can enhance the resonant properties of such arrays. We have investigated the use of periodic arrays of Al nanoparticles placed...... on the front of a thin film Si test solar cell. It is demonstrated that the resonances from the Al nanoparticle array cause a broadband photocurrent enhancement ranging from the ultraviolet to the infrared with respect to a reference cell. From the experimental results as well as from numerical simulations...

  15. Kinetics of photocurrent generation and an efficient charge separation of a dye-sensitized n-Cu2O/p-CuSCN junction photoelectrode in a solid-state photovoltaic cell

    International Nuclear Information System (INIS)

    Fernando, C A N; Kumara, N T R N; Gamage, T N

    2010-01-01

    A Cu/n-Cu 2 O/dye/p-CuSCN junction photoelectrode is fabricated to produce a solid-state dye-sensitized photovoltaic cell. Samples are characterized by XRD, SEM and surface resistivity measurements. Photocurrent generation is found due to light absorption of n-Cu 2 O thin film and dye sensitization between p-CuSCN and the dye. Kinetics of the photocurrent generation of the dye sensitization is studied solving the rate equations by the iteration method obtaining a relationship for the photocurrent quantum efficiency (Φ) depending on the surface concentration (D o ) of the dye and the rate constants of the reactions with connection to the dye sensitization process. The solution obtained in the steady state by iteration is found to be of the form Φ = AD o −BD o 2 (A and B are constants related to the reaction rates of the photocurrent generation process and the concentration of the n-Cu 2 O film). The variation of the n-Cu 2 O concentration with photocurrent is presented. A photocurrent enhancement is observed for the Cu/n-Cu 2 O/dye/p-CuSCN photovoltaic cell compared to that of Cu/n-Cu 2 O, Cu/p-CuSCN/dye and Cu/n-Cu 2 O/p-CuSCN photovoltaic cells. Good rectification characteristics are observed for the Cu/n-Cu 2 O/p-CuSCN photoelectrode compared to that of Cu/n-Cu 2 O and Cu/p-CuSCN photoelectrodes. Photocurrent enhancement is found due to the efficient charge separation process at the n–p junction. Energy band structures of the n–p junction are proposed according to the onset potentials which are used to discuss the mechanism of the efficient charge separation suppressing the recombination process

  16. Highly enhanced photocurrent of novel quantum-dot-co-sensitized PbS-Hg/CdS/Cu:ZnO thin films for photoelectrochemical applications

    International Nuclear Information System (INIS)

    Gohel, Jignasa V.; Jana, A.K.; Singh, Mohit

    2017-01-01

    A novel quantum-dot-co-sensitized PbS-Hg/CdS/Cu:ZnO thin films synthesized by low-cost process. The properties of ZnO are also enhanced by doping and co-doping. It is also compared with quantum-dot co-sensitization. Optical properties, crystal structure, morphology, and photocurrent are characterized by UV-Vis spectroscopy, XRD, SEM, and solar simulator, respectively. The bandgap is interestingly reduced highly to 2.6 eV for Ag co-doped Cu:ZnO. It is unprecedentedly reduced to 2.1 eV and even 1.97 eV for CdS and PbS-Hg QD-sensitized thin films, respectively. An exceptionally enhanced photocurrent of 17.1 mA/cm"2 is achieved with PbS-Hg-co-sensitized CdS-sensitized Cu:ZnO thin film. This is an excellent achievement, which highly supports the potential of low-cost solar conversion. (orig.)

  17. Analyzing a steady-state phenomenon using an ensemble of sequential transient events: A proof of concept on photocurrent of bacteriorhodopsin upon continuous photoexcitation

    Energy Technology Data Exchange (ETDEWEB)

    Hung, Chang-Wei; Chu, Li-Kang, E-mail: lkchu@mx.nthu.edu.tw [Department of Chemistry, National Tsing Hua University, 101, Sec. 2, Kuang-Fu Rd., Hsinchu 30013, Taiwan (China); Ho, Ching-Hwa [Interdisplinary Program of Science, National Tsing Hua University, 101, Sec. 2, Kuang-Fu Rd., Hsinchu 30013, Taiwan (China)

    2014-10-14

    The proton pump activity of bacteriorhodopsin in aqueous solution upon excitation with modulated continuous light was monitored electrochemically and analyzed by superimposing a series of transient proton translocation events Hᵢ⁺(t). An evolution function f(t)=(he{sup –lt}+k)/(h+k) , including a decay and a stationary offset, was introduced to weight the contribution of the individual transient events evolving with time in the envelope of the steady-state event. The evolution of the total proton concentration can be treated as an ensemble of weighted sequential transient events, H{sub total}⁺(t)=Σ{{sub i=0}sup n}Hᵢ⁺(t)∙f(t), and the temporal profile of the photocurrent is derived by differentiating the proton concentration with respect to time, (table) . The temporal profiles of the bacteriorhodopsin photocurrent in pH range of 6.3–8.1 were analyzed using a well-defined kinetics model and restricted mathematical formulization, and fitted temporal behaviors agreed with the observations. This successful proof-of-concept study on analyzing a steady-state phenomenon using an ensemble of sequential transient events can be generalized to quantify other phenomena upon continuous stimulation, such as estimation of the light-driven ion pump activities of the photosynthetic proteins upon illumination.

  18. Highly enhanced photocurrent of novel quantum-dot-co-sensitized PbS-Hg/CdS/Cu:ZnO thin films for photoelectrochemical applications

    Energy Technology Data Exchange (ETDEWEB)

    Gohel, Jignasa V.; Jana, A.K.; Singh, Mohit [Sardar Vallabhbhai National Institute of Technology, Chemical Engineering Department, Surat, Gujarat (India)

    2017-08-15

    A novel quantum-dot-co-sensitized PbS-Hg/CdS/Cu:ZnO thin films synthesized by low-cost process. The properties of ZnO are also enhanced by doping and co-doping. It is also compared with quantum-dot co-sensitization. Optical properties, crystal structure, morphology, and photocurrent are characterized by UV-Vis spectroscopy, XRD, SEM, and solar simulator, respectively. The bandgap is interestingly reduced highly to 2.6 eV for Ag co-doped Cu:ZnO. It is unprecedentedly reduced to 2.1 eV and even 1.97 eV for CdS and PbS-Hg QD-sensitized thin films, respectively. An exceptionally enhanced photocurrent of 17.1 mA/cm{sup 2} is achieved with PbS-Hg-co-sensitized CdS-sensitized Cu:ZnO thin film. This is an excellent achievement, which highly supports the potential of low-cost solar conversion. (orig.)

  19. Determination of density of band-gap states of hydrogenated amorphous silicon suboxide thin films

    International Nuclear Information System (INIS)

    Bacioglu, A.

    2005-01-01

    Variation of density of gap states of PECVD silicon suboxide films with different oxygen concentrations was evaluated through electrical and optical measurements. Optical transmission and constant photocurrent method (CPM) were used to determine absorption coefficient as a function of photon energy. From these measurements the localized density of states between the valance band mobility edge and Fermi level has been determined. To determine the variation of conduction band edge, steady state photoconductivity (SSPC), photoconductivity response time (PCRT) and transient photoconductivity (TPC) measurements were utilized. Results indicate that the conduction and valance band edges, both, widen monotonically with oxygen content

  20. Low Bone Density

    Science.gov (United States)

    ... Density Exam/Testing › Low Bone Density Low Bone Density Low bone density is when your bone density ... people with normal bone density. Detecting Low Bone Density A bone density test will determine whether you ...

  1. Impact of distributed generation in the probability density of voltage sags; Impacto da geracao distribuida na densidade de probabilidade de afundamentos de tensao

    Energy Technology Data Exchange (ETDEWEB)

    Ramos, Alessandro Candido Lopes [CELG - Companhia Energetica de Goias, Goiania, GO (Brazil). Generation and Transmission. System' s Operation Center], E-mail: alessandro.clr@celg.com.br; Batista, Adalberto Jose [Universidade Federal de Goias (UFG), Goiania, GO (Brazil)], E-mail: batista@eee.ufg.br; Leborgne, Roberto Chouhy [Universidade Federal do Rio Grande do Sul (UFRS), Porto Alegre, RS (Brazil)], E-mail: rcl@ece.ufrgs.br; Emiliano, Pedro Henrique Mota, E-mail: ph@phph.com.br

    2009-07-01

    This article presents the impact of distributed generation in studies of voltage sags caused by faults in the electrical system. We simulated short-circuit-to-ground in 62 lines of 230, 138, 69 and 13.8 kV that are part of the electrical system of the city of Goiania, of Goias state . For each fault position was monitored the bus voltage of 380 V in an industrial consumer sensitive to such sags. Were inserted different levels of GD near the consumer. The simulations of a short circuit, with the monitoring bar 380 V, were performed again. A study using stochastic simulation Monte Carlo (SMC) was performed to obtain, at each level of GD, the probability curves and sags of the probability density and its voltage class. With these curves were obtained the average number of sags according to each class, that the consumer bar may be submitted annually. The simulations were performed using the Program Analysis of Simultaneous Faults - ANAFAS. In order to overcome the intrinsic limitations of the methods of simulation of this program and allow data entry via windows, a computational tool was developed in Java language. Data processing was done using the MATLAB software.

  2. Level densities

    International Nuclear Information System (INIS)

    Ignatyuk, A.V.

    1998-01-01

    For any applications of the statistical theory of nuclear reactions it is very important to obtain the parameters of the level density description from the reliable experimental data. The cumulative numbers of low-lying levels and the average spacings between neutron resonances are usually used as such data. The level density parameters fitted to such data are compiled in the RIPL Starter File for the tree models most frequently used in practical calculations: i) For the Gilber-Cameron model the parameters of the Beijing group, based on a rather recent compilations of the neutron resonance and low-lying level densities and included into the beijing-gc.dat file, are chosen as recommended. As alternative versions the parameters provided by other groups are given into the files: jaeri-gc.dat, bombay-gc.dat, obninsk-gc.dat. Additionally the iljinov-gc.dat, and mengoni-gc.dat files include sets of the level density parameters that take into account the damping of shell effects at high energies. ii) For the backed-shifted Fermi gas model the beijing-bs.dat file is selected as the recommended one. Alternative parameters of the Obninsk group are given in the obninsk-bs.dat file and those of Bombay in bombay-bs.dat. iii) For the generalized superfluid model the Obninsk group parameters included into the obninsk-bcs.dat file are chosen as recommended ones and the beijing-bcs.dat file is included as an alternative set of parameters. iv) For the microscopic approach to the level densities the files are: obninsk-micro.for -FORTRAN 77 source for the microscopical statistical level density code developed in Obninsk by Ignatyuk and coworkers, moller-levels.gz - Moeller single-particle level and ground state deformation data base, moller-levels.for -retrieval code for Moeller single-particle level scheme. (author)

  3. Dye-Sensitized Solar Cells Based on the Principles and Materials of Photosynthesis: Mechanisms of Suppression and Enhancement of Photocurrent and Conversion Efficiency

    Directory of Open Access Journals (Sweden)

    Hiroyoshi Nagae

    2009-10-01

    Full Text Available Attempts have been made to develop dye-sensitized solar cells based on the principles and materials of photosynthesis: We first tested photosynthetic pigments, carotenoids (Cars, chlorophylls (Chls and their derivatives, to find sensitizers showing reasonable performance (photocurrent and conversion efficiency. We then tried to introduce the principles of photosynthesis, including electron transfer and energy transfer from Car to Phe a. Also, we tried co-sensitization using the pheophorbide (Phe a and Chl c2 pair which further enhanced the performance of the component sensitizers as follows: Jsc = 9.0 + 13.8 → 14.0 mA cm–2 and η = 3.4 + 4.6 → 5.4%.

  4. Dye-sensitized solar cells based on the principles and materials of photosynthesis: mechanisms of suppression and enhancement of photocurrent and conversion efficiency.

    Science.gov (United States)

    Koyama, Yasushi; Miki, Takeshi; Wang, Xiao-Feng; Nagae, Hiroyoshi

    2009-10-27

    Attempts have been made to develop dye-sensitized solar cells based on the principles and materials of photosynthesis: We first tested photosynthetic pigments, carotenoids (Cars), chlorophylls (Chls) and their derivatives, to find sensitizers showing reasonable performance (photocurrent and conversion efficiency). We then tried to introduce the principles of photosynthesis, including electron transfer and energy transfer from Car to Phe a. Also, we tried co-sensitization using the pheophorbide (Phe) a and Chl c(2) pair which further enhanced the performance of the component sensitizers as follows: J(sc) = 9.0 + 13.8 --> 14.0 mA cm(-2) and eta = 3.4 + 4.6 --> 5.4%.

  5. High photocurrent gain in NiO thin film/M-doped ZnO nanorods (M=Ag, Cd and Ni) heterojunction based ultraviolet photodiodes

    Energy Technology Data Exchange (ETDEWEB)

    Echresh, Ahmad, E-mail: ahmadechresh@gmail.com [Department of Science and Technology, Physical Electronics and Nanotechnology Division, Campus Norrköping, Linköping University, SE-601 74 Norrköping (Sweden); Echresh, Mohammad [Department of Physics, Sanati Hoveizeh University, Ahvaz (Iran, Islamic Republic of); Khranovskyy, Volodymyr [Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-5818358183 Linköping (Sweden); Nur, Omer; Willander, Magnus [Department of Science and Technology, Physical Electronics and Nanotechnology Division, Campus Norrköping, Linköping University, SE-601 74 Norrköping (Sweden)

    2016-10-15

    The thermal evaporation method has been used to deposit p-type NiO thin film, which was combined with hydrothermally grown n-type pure and M-doped ZnO nanorods (M=Ag, Cd and Ni) to fabricate a high performance p-n heterojunction ultraviolet photodiodes. The fabricated photodiodes show high rectification ratio and relatively low leakage current. The p-NiO/n-Zn{sub 0.94}Ag{sub 0.06}O heterojunction photodiode displays the highest photocurrent gain (~1.52×10{sup 4}), a photoresponsivity of ~4.48×10{sup 3} AW{sup −1} and a photosensitivity of ~13.56 compared with the other fabricated photodiodes. The predominated transport mechanisms of the p-n heterojunction ultraviolet photodiodes at low and high applied forward bias may be recombination-tunneling and space charge limited current, respectively.

  6. Bi facial silicon solar cell study in modelling in frequency dynamic regime under multispectral illumination: Recombination parameters determination methods

    International Nuclear Information System (INIS)

    ZERBO Issa

    2010-01-01

    A bibliographic study on the techniques of characterization of silicon solar cell, diodes, massifs and silicon wafer are presented. The influence of the modulation frequency and recombination in volume and in surface phenomena of on the profiles of carriers' densities, photocurrent and photovoltage has been put in evidence. The study of surface recombination velocities permitted to show that the bi facial silicon solar cell of Back Surface Field type behaves like an ohmic contacts solar cell for modulation frequencies above 40 khz. pplicability in frequency dynamic regime in the frequency range [0 - 40 khz] of three techniques of steady state recombination parameters determination is shown. A technique of diffusion length determination, in the range of (200 Hz - 40 khz] is proposed. It rests on the measurement of the short circuit current phase that is compared with the theoretical curve of short circuit current phase. The intersection of the experimental short circuit current phase and the theoretical curve of short circuit current phase permits to get the minority carriers effective diffusion length. An equivalent electric model of a solar cell in frequency dynamic regime is proposed. A study in modelling of the bi facial solar cell shunt resistance and space charge zone capacity is led from a determination method of these parameters proposed in steady state. (Author [fr

  7. Effects of Frequency Dependence of the External Quantum Efficiency of Perovskite Solar Cells.

    Science.gov (United States)

    Ravishankar, Sandheep; Aranda, Clara; Boix, Pablo P; Anta, Juan A; Bisquert, Juan; Garcia-Belmonte, Germà

    2018-06-07

    Perovskite solar cells are known to show very long response time scales, on the order of milliseconds to seconds. This generates considerable doubt over the validity of the measured external quantum efficiency (EQE) and consequently the estimation of the short-circuit current density. We observe a variation as high as 10% in the values of the EQE of perovskite solar cells for different optical chopper frequencies between 10 and 500 Hz, indicating a need to establish well-defined protocols of EQE measurement. We also corroborate these values and obtain new insights regarding the working mechanisms of perovskite solar cells from intensity-modulated photocurrent spectroscopy measurements, identifying the evolution of the EQE over a range of frequencies, displaying a singular reduction at very low frequencies. This reduction in EQE is ascribed to additional resistive contributions hindering charge extraction in the perovskite solar cell at short-circuit conditions, which are delayed because of the concomitant large low-frequency capacitance.

  8. Enhancement of photocurrents due to the oxidation of water and organic compounds at BiZn2VO6 particulate thin film electrodes by treatment with a TiCl4 solution

    International Nuclear Information System (INIS)

    Liu Haimei; Imanishi, Akihito; Yang Wensheng; Nakato, Yoshihiro

    2010-01-01

    Photocurrents due to water oxidation at BiZn 2 VO 6 (E g 2.4 eV) particulate thin film electrodes were largely enhanced by pre-treatment with an aqueous TiCl 4 solution. Photocurrents for BiZn 2 VO 6 electrodes with no TiCl 4 treatment were also enhanced by the addition of organic compounds such as methanol and trimethyl amine to the aqueous electrolyte. Interestingly, such enhanced photocurrents by organic compounds were further enhanced by the TiCl 4 pre-treatment. EDAX and SEM investigations showed the formation of a flock-like TiO 2 overlayer on BiZn 2 VO 6 particles after the TiCl 4 treatment. The photocurrent enhancement by the TiCl 4 pre-treatment is thus mainly attributed to the necking effect of the flock-like TiO 2 overlayer, which facilitates the transport of photogenerated electrons within the BiZn 2 VO 6 particulate thin film electrode.

  9. Dependence of the saturated light-induced defect density on macroscopic properties of hydrogenated amorphous silicon

    OpenAIRE

    Park, H. R.; Liu, J. Z.; Roca i Cabarrocas, P.; Maruyama, A.; Isomura, M.; Wagner, S.; Abelson, J. R.; Finger, F.

    2008-01-01

    We report a study of the saturated light-induced defect density Ns,sat in 37 hydrogenated (and in part fluorinated) amorphous silicon [a-Si:H(F)] films grown in six different reactors under widely different conditions. Ns,sat was attained by exposing the films to light from a krypton ion laser (λ=647.1 nm). Ns,sat is determined by the constant photocurrent method and lies between 5×1016 and 2×1017 cm−3. Ns,sat drops with decreasing optical gap Eopt and hydrogen content cH, but is not correlat...

  10. Role of Ag2S coupling on enhancing the visible-light-induced catalytic property of TiO2 nanorod arrays

    Science.gov (United States)

    Li, Zhengcao; Xiong, Shan; Wang, Guojing; Xie, Zheng; Zhang, Zhengjun

    2016-01-01

    In order to obtain a better photocatalytic performance under visible light, Ag2S-coupled TiO2 nanorod arrays (NRAs) were prepared through the electron beam deposition with glancing angle deposition (GLAD) technique, annealing in air, followed by the successive ionic layer absorption and reaction (SILAR) method. The properties of the photoelectrochemical and photocatalytic degradation of methyl orange (MO) were thus conducted. The presence of Ag2S on TiO2 NRAs was observed to have a significant improvement on the response to visible light. It’s resulted from that Ag2S coupling can improve the short circuit photocurrent density and enhance the photocatalytic activity remarkably.

  11. Monolithic Parallel Tandem Organic Photovoltaic Cell with Transparent Carbon Nanotube Interlayer

    Science.gov (United States)

    Tanaka, S.; Mielczarek, K.; Ovalle-Robles, R.; Wang, B.; Hsu, D.; Zakhidov, A. A.

    2009-01-01

    We demonstrate an organic photovoltaic cell with a monolithic tandem structure in parallel connection. Transparent multiwalled carbon nanotube sheets are used as an interlayer anode electrode for this parallel tandem. The characteristics of front and back cells are measured independently. The short circuit current density of the parallel tandem cell is larger than the currents of each individual cell. The wavelength dependence of photocurrent for the parallel tandem cell shows the superposition spectrum of the two spectral sensitivities of the front and back cells. The monolithic three-electrode photovoltaic cell indeed operates as a parallel tandem with improved efficiency.

  12. Two color interferometric electron density measurement in an axially blown arc

    Science.gov (United States)

    Stoller, Patrick; Carstensen, Jan; Galletti, Bernardo; Doiron, Charles; Sokolov, Alexey; Salzmann, René; Simon, Sandor; Jabs, Philipp

    2016-09-01

    High voltage circuit breakers protect the power grid by interrupting the current in case of a short circuit. To do so an arc is ignited between two contacts as they separate; transonic gas flow is used to cool and ultimately extinguish the arc at a current-zero crossing of the alternating current. A detailed understanding of the arc interruption process is needed to improve circuit breaker design. The conductivity of the partially ionized gas remaining after the current-zero crossing, a key parameter in determining whether the arc will be interrupted or not, is a function of the electron density. The electron density, in turn, is a function of the detailed dynamics of the arc cooling process, which does not necessarily occur under local thermodynamic equilibrium (LTE) conditions. In this work, we measure the spatially resolved line-integrated index of refraction in a near-current-zero arc stabilized in an axial flow of synthetic air with two nanosecond pulsed lasers at wavelengths of 532 nm and 671 nm. Generating a stable, cylindrically symmetric arc enables us to determine the three-dimensional index of refraction distribution using Abel inversion. Due to the wavelength dependence of the component of the index of refraction related to the free electrons, the information at two different wavelengths can be used to determine the electron density. This information allows us to determine how important it is to take into account non-equilibrium effects for accurate modeling of the physics of decaying arcs.

  13. Observation of Switchable Photoresponse of a Monolayer WSe2-MoS2 Lateral Heterostructure via Photocurrent Spectral Atomic Force Microscopic Imaging.

    Science.gov (United States)

    Son, Youngwoo; Li, Ming-Yang; Cheng, Chia-Chin; Wei, Kung-Hwa; Liu, Pingwei; Wang, Qing Hua; Li, Lain-Jong; Strano, Michael S

    2016-06-08

    In the pursuit of two-dimensional (2D) materials beyond graphene, enormous advances have been made in exploring the exciting and useful properties of transition metal dichalcogenides (TMDCs), such as a permanent band gap in the visible range and the transition from indirect to direct band gap due to 2D quantum confinement, and their potential for a wide range of device applications. In particular, recent success in the synthesis of seamless monolayer lateral heterostructures of different TMDCs via chemical vapor deposition methods has provided an effective solution to producing an in-plane p-n junction, which is a critical component in electronic and optoelectronic device applications. However, spatial variation of the electronic and optoelectonic properties of the synthesized heterojunction crystals throughout the homogeneous as well as the lateral junction region and the charge carrier transport behavior at their nanoscale junctions with metals remain unaddressed. In this work, we use photocurrent spectral atomic force microscopy to image the current and photocurrent generated between a biased PtIr tip and a monolayer WSe2-MoS2 lateral heterostructure. Current measurements in the dark in both forward and reverse bias reveal an opposite characteristic diode behavior for WSe2 and MoS2, owing to the formation of a Schottky barrier of dissimilar properties. Notably, by changing the polarity and magnitude of the tip voltage applied, pixels that show the photoresponse of the heterostructure are observed to be selectively switched on and off, allowing for the realization of a hyper-resolution array of the switchable photodiode pixels. This experimental approach has significant implications toward the development of novel optoelectronic technologies for regioselective photodetection and imaging at nanoscale resolutions. Comparative 2D Fourier analysis of physical height and current images shows high spatial frequency variations in substrate/MoS2 (or WSe2) contact that

  14. Observation of Switchable Photoresponse of a Monolayer WSe 2 –MoS 2 Lateral Heterostructure via Photocurrent Spectral Atomic Force Microscopic Imaging

    KAUST Repository

    Son, Youngwoo

    2016-04-27

    In the pursuit of two-dimensional (2D) materials beyond graphene, enormous advances have been made in exploring the exciting and useful properties of transition metal dichalcogenides (TMDCs), such as a permanent band gap in the visible range and the transition from indirect to direct band gap due to 2D quantum confinement, and their potential for a wide range of device applications. In particular, recent success in the synthesis of seamless monolayer lateral heterostructures of different TMDCs via chemical vapor deposition methods has provided an effective solution to producing an in-plane p-n junction, which is a critical component in electronic and optoelectronic device applications. However, spatial variation of the electronic and optoelectonic properties of the synthesized heterojunction crystals throughout the homogeneous as well as the lateral junction region and the charge carrier transport behavior at their nanoscale junctions with metals remain unaddressed. In this work, we use photocurrent spectral atomic force microscopy to image the current and photocurrent generated between a biased PtIr tip and a monolayer WSe2-MoS2 lateral heterostructure. Current measurements in the dark in both forward and reverse bias reveal an opposite characteristic diode behavior for WSe2 and MoS2, owing to the formation of a Schottky barrier of dissimilar properties. Notably, by changing the polarity and magnitude of the tip voltage applied, pixels that show the photoresponse of the heterostructure are observed to be selectively switched on and off, allowing for the realization of a hyper-resolution array of the switchable photodiode pixels. This experimental approach has significant implications toward the development of novel optoelectronic technologies for regioselective photodetection and imaging at nanoscale resolutions. Comparative 2D Fourier analysis of physical height and current images shows high spatial frequency variations in substrate/MoS2 (or WSe2) contact that

  15. Synthesis and characterization of Fe3+ doped TiO2 nanoparticles and films and their performance for photocurrent response under UV illumination

    International Nuclear Information System (INIS)

    Elghniji, Kais; Atyaoui, Atef; Livraghi, Stefano; Bousselmi, Latifa; Giamello, Elio; Ksibi, Mohamed

    2012-01-01

    Graphical abstract: Schematic diagram illustrating the charge transfer from excited TiO 2 to the different states of Fe 3+ ions; C B and V B refer to the energy levels of the conduction and valence bands of TiO 2 , respectively. Highlights: ► In this study we examine the Iron as catalyst precursor to synthesize the Fe 3+ doped TiO 2 nanoparticles. ► The Fe 3+ doped TiO 2 catalysts show the presence of a mixed phase of anatase. ► The iron is completely absent in the XRD pattern of the doped iron TiO 2 powder. ► The analysis of EPR result further confirms that Fe 3+ ion are successfully doped in the TiO 2 lattice by substituting Ti 4+ . ► Fe 3+ doping can efficiently separate the photo-generated electrons and holes. - Abstract: Undoped TiO 2 and Fe 3+ doped (0.1, 0.3, 0.6 and 1 wt.%) TiO 2 nanoparticles have been synthesized by the acid-catalyzed sol–gel method. Iron cations are introduced in the initial solution, before gelification, what promotes their lattice localization. The Fe 3+ doped TiO 2 films have been fabricated using a dip-coating technique. The effect of iron content on the crystalline structure, phase transformation and grain growth were determined by X-ray diffraction (XRD), Raman spectroscopy, UV–visible diffused reflectance spectroscopy (DRS) and Electron paramagnetic resonance (EPR) spectroscopy. It has demonstrated that all catalysts are composed of mixed-phase crystals of anatase and brookite with anatase as dominant phase. The crystallinity of the brookite and anatase phases decreased with increasing the iron content. The analysis of EPR result further confirms that Fe 3+ ion are successfully doped in the TiO 2 lattice by substituting Ti 4+ . It was demonstrated that Fe 3+ ion in the TiO 2 films plays a role as the intermediate for the efficient separation of photogenerated hole–electron pairs and increases the photocurrent response of the film under UV light irradiation. The maximum photocurrent is obtained on the Fe 3+ doped Ti

  16. Synthesis and characterization of Fe{sup 3+} doped TiO{sub 2} nanoparticles and films and their performance for photocurrent response under UV illumination

    Energy Technology Data Exchange (ETDEWEB)

    Elghniji, Kais [University of Sfax, Laboratoire Eau, Energie et Environnement (LR3E), Ecole Nationale d' Ingenieurs de Sfax, B.P. 1173, 3038 Sfax (Tunisia); Atyaoui, Atef [Centre de Recherches et des Technologies des Eaux, Technopole de Borj Cedria B.P. 273, 8020 Soliman (Tunisia); Livraghi, Stefano [Dipartimento di Chimica I.F.M and NIS, Universita degli Studi di Torino, Via P. Giuria, 7 10125 Torino (Italy); Bousselmi, Latifa [Centre de Recherches et des Technologies des Eaux, Technopole de Borj Cedria B.P. 273, 8020 Soliman (Tunisia); Giamello, Elio [Dipartimento di Chimica I.F.M and NIS, Universita degli Studi di Torino, Via P. Giuria, 7 10125 Torino (Italy); Ksibi, Mohamed, E-mail: Mohamed.Ksibi@tunet.tn [University of Sfax, Laboratoire Eau, Energie et Environnement (LR3E), Ecole Nationale d' Ingenieurs de Sfax, B.P. 1173, 3038 Sfax (Tunisia)

    2012-11-15

    plays a role as the intermediate for the efficient separation of photogenerated hole-electron pairs and increases the photocurrent response of the film under UV light irradiation. The maximum photocurrent is obtained on the Fe{sup 3+} doped TiO{sub 2} film with 0.1% Fe, which is 1.46 times that achieved on undoped TiO{sub 2} film.

  17. High performance of visible-NIR broad spectral photocurrent application of monodisperse PbSe nanocubes decorated on rGO sheets

    Science.gov (United States)

    Ghorban Shiravizadeh, A.; Elahi, S. M.; Sebt, S. A.; Yousefi, Ramin

    2018-02-01

    In this work, the photoresponse performance of monodisperse PbSe nanocubes in the range of visible and near-infrared (NIR) (400-1500 nm) regions was enhanced by reduced graphene oxide (rGO). A simple cost-effective method is presented to synthesize monodisperse PbSe nanocubes (NCs) that are decorated on the rGO sheets. By the addition of PbSe/rGO nanocomposites with different rGO concentrations, pristine PbSe NCs were synthesized with the same method. Microscopy images showed that the size of NCs was smaller than the exciton Bohr radius (46 nm) of PbSe bulk. Therefore, the UV-Vis-IR spectroscopy result revealed that the PbSe/rGO samples had absorption peaks in the NIR region around 1650 nm and showed a blue shift compared to the absorption peak of the PbSe bulk. J-V measurements of the samples indicated that monodisperse PbSe/rGO nanocomposites had a higher resistance than the other samples under dark condition. On the other hand, the resistance of the monodisperse PbSe/rGO nanocomposites decreased under different light source illuminations while the resistance of the other samples was increased under illumination. Photodetector measurements indicated that the monodisperse morphology of the PbSe NCs enhanced the photoresponse speed and photocurrent intensity. In addition, responsivity (R) and detectivity (D*) of the samples were higher in the NIR region.

  18. Persistent photocurrent and deep level traps in PLD-grown In-Ga-Zn-O thin films studied by thermally stimulated current spectroscopy

    Science.gov (United States)

    Wang, Buguo; Anders, Jason; Leedy, Kevin; Schuette, Michael; Look, David

    2018-02-01

    InGaZnO (IGZO) is a promising semiconductor material for thin-film transistors (TFTs) used in DC and RF switching applications, especially since it can be grown at low temperatures on a wide variety of substrates. Enhancement-mode TFTs based on IGZO thin films grown by pulsed laser deposition (PLD) have been recently fabricated and these transistors show excellent performance; however, compositional variations and defects can adversely affect film quality, especially in regard to electrical properties. In this study, we use thermally stimulated current (TSC) spectroscopy to characterize the electrical properties and the deep traps in PLD-grown IGZO thin films. It was found that the as-grown sample has a DC activation energy of 0.62 eV, and two major traps with activation energies at 0.16-0.26 eV and at 0.90 eV. However, a strong persistent photocurrent (PPC) sometimes exists in the as-grown sample, so we carry out post-growth annealing in an attempt to mitigate the effect. It was found that annealing in argon increases the conduction, produces more PPC and also makes more traps observable. Annealing in air makes the film more resistive, and removes PPC and all traps but one. This work demonstrates that current-based trap emission, such as that associated with the TSC, can effectively reveal electronic defects in highlyresistive semiconductor materials, especially those are not amenable to capacitance-based techniques, such as deeplevel transient spectroscopy (DLTS).

  19. Enhanced Photocurrent in BiFeO3 Materials by Coupling Temperature and Thermo-Phototronic Effects for Self-Powered Ultraviolet Photodetector System.

    Science.gov (United States)

    Qi, Jia; Ma, Nan; Ma, Xiaochen; Adelung, Rainer; Yang, Ya

    2018-04-25

    Ferroelectric materials can be utilized for fabricating photodetectors because of the photovoltaic effect. Enhancing the photovoltaic performance of ferroelectric materials is still a challenge. Here, a self-powered ultraviolet (UV) photodetector is designed based on the ferroelectric BiFeO 3 (BFO) material, exhibiting a high current/voltage response to 365 nm light in heating/cooling states. The photovoltaic performance of the BFO-based device can be well modulated by applying different temperature variations, where the output current and voltage can be enhanced by 60 and 75% in heating and cooling states, respectively. The enhancement mechanism of the photocurrent is associated with both temperature effect and thermo-phototronic effect in the photovoltaic process. Moreover, a 4 × 4 matrix photodetector array has been designed for detecting the 365 nm light distribution in the cooling state by utilizing photovoltage signals. This study clarifies the role of the temperature effect and the thermo-phototronic effect in the photovoltaic process of the BFO material and provides a feasible route for pushing forward practical applications of self-powered UV photodetectors.

  20. Magnetically tunable photocurrent in La{sub 0.7}Sr{sub 0.3}MnO{sub 3}/BaSnO{sub 3} heterojunctions

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Bingcheng; Hu, Junbiao [Department of Applied Physics, Northwestern Polytechnical University, Xi' an (China); Wang, Jing [Department of Applied Physics, Northwestern Polytechnical University, Xi' an (China); Department of Physics, Pennsylvania State University, University Park, PA (United States)

    2017-12-15

    Artificially constructed oxide heterointerfaces have attracted much attention. Herein, the novel all-perovskite p-n heterojunction composed of a colossal magnetoresistive manganite La{sub 0.7}Sr{sub 0.3} MnO{sub 3} (LSMO) and an n-type transparent semiconducting BaSnO{sub 3} (BSO) is designed via optimizing the growth condition. This LSMO/BSO p-n junction exhibits good rectification with a forward-to-reverse ratio of 275 at 1 V, high photo detection capability with a photo-to-dark current of 581.9 at -0.5 V, high ultraviolet light sensitivity with a UV (360 nm)-to-visible (532 nm) ratio of ∝2.4 x 10{sup 3}, and a significantly magneto-tunable photocurrent with a variation ratio of ∝1.25 % under 532 nm illumination and 0.5 T magnetic field. As a result, combining synergistically the functionality of diode and magnetically tunable photo detector, the LSMO/BSO p-n junction is a promising candidate for advanced magneto-optoelectronic devices. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)