Admissibility of building cost subsidy in the power grid above the low voltage level

International Nuclear Information System (INIS)

Foerster, Sven

2015-01-01

Electricity networks are essential to the provision of electrical power to businesses and individuals. In particular for manufacturing businesses a connection to the grid above the low-voltage level is often useful. Network operators demand a subsidy for the new connection and for the change to a higher network level under the auspices of construction cost. The power network market above the low-voltage level is a natural monopoly. This leaves consumers looking for a connection to the power grid with no possibility to select among different network operators. Construction cost subsidies are not regulated by law above the low voltage level. The lack of legal regulation and the natural monopoly above the low-voltage level affect the balance of power between network operators and system users. The lawfulness of the construction cost subsidies, the prerequisites for their demand and a review of the calculation models (Leistungspreismodell, 2-Ebenen-Modell) as well as a proposal for a reform of this system form the subject of this work.

Synchronised PWM Schemes for Three-level Inverters with Zero Common-mode Voltage

DEFF Research Database (Denmark)

Oleschuk, Valentin; Blaabjerg, Frede

2002-01-01

This paper presents results of analysis and comparison of novel synchronised schemes of pulsewidth modulation (PWM), applied to three-level voltage source inverters with control algorithms providing elimination of the common-mode voltage. The proposed approach is based on a new strategy of digital...

Technical and economic evaluation of voltage level in transmission network expansion planning using GA

International Nuclear Information System (INIS)

Jalilzadeh, S.; Kazemi, A.; Shayeghi, H.; Madavi, M.

2008-01-01

Transmission network expansion planning is an important part of power system planning. Its task is to determine an optimal network configuration according to load growth. It determines where, when and how many new transmission lines should be installed. Up to now, various methods have been presented to solve the static transmission network expansion planning (STNEP) problem, but in all of these methods, the STNEP problem has been solved regardless of voltage level of the lines. In this paper, due to different voltage levels in the transmission network, which cause different annual losses, STNEP has been studied considering the voltage level of the transmission lines and the network loss using the genetic algorithm (GA). Finally, the proposed idea has been examined on Garvers 6 bus network. The results show that considering the loss in a network with different voltage levels decreases the operational costs considerably, and the network satisfies the requirement of delivering electric power more safely and reliably to load centers

Five-Level Converter with Low Switching Frequency Applied as DC Voltage Supply

DEFF Research Database (Denmark)

Rasmussen, Tonny Wederberg

1999-01-01

This paper describes the use of a multi-level converter as a DC supply. Equations for the converter will be deduced in the nondissipative case. The equations provide solutions to DC voltage and the angle of converter voltage. In addition the spectrum for the harmonics after the elimination of sel...

Gamma radiographic exposure time indicator

International Nuclear Information System (INIS)

Risbud, V.H.; Thiagarajan, A.; Gangadharan, P.

1979-01-01

In industrial radiography, with the proper selection of source and film, the radiographic quality depends very much on the exposure time, which in turn depends upon the source strength and the source to film distance. Conventional methods to arrive at correct exposure time involve time consuming calculations and in these methods the knowledge of the above mentioned parameters is imperative. An instrument to determine the required exposure time has been developed which indicates exposure times in about 30 secs. This covers two commonly used gamma radiography sources, viz., 192 Ir and 60 Co and six commonly used radiography films of different speeds. Knowledge of source strength and source to film distance is not required with the use of this instrument. With a knowledge of the total exposure required by the film to give the required sensitivity and by the measurement of radiation level at the film location, the correct exposure time is determined. The radiation level is measured by placing a GM counter behind the radiographic specimen at the film location. To match the responses of the film and the GM counter, the counter is incorporated in a suitably designed probe. In this instruments, an integrator to integrate the GM-pulses and a constant current integrator (timer) are started simultaneously. The voltage at the GM-pulse integrator is compared with a preselected voltage, (selected on the basis of film type, source, source strength and order of object thickness) by a comparator. The comparator is so adjusted that when the GM-pulse integrator voltage exceeds the preselected voltage, it switches its state and stops the integration of constant current. The constant current integrator output which is proportional to the time taken for the GM-pulse integrator to reach the preselected voltage, is read on a meter graduated in terms of exposure time. The instrument can measure exposure times from 5 minutes to 10 hours read in two ranges, the range-changing being automatic

Mitigation of Flicker using STATCOM with Three-Level 12-pulse Voltage Source Inverter

OpenAIRE

Ali Z a'fari

2011-01-01

Voltage flicker is a disturbance in electrical power systems. The reason for this disturbance is mainly the large nonlinear loads such as electric arc furnaces. Synchronous static compensator (STATCOM) is considered as a proper technique to mitigate the voltage flicker. Application of more suitable and precise power electronic converter leads to a more precise performance of the compensator. In this paper a three-level 12-pulse voltage source inverter (VSI) with a 12-term...

A dynamic voltage restorer (DVR) with selective harmonic compensation at medium voltage level

DEFF Research Database (Denmark)

Newman, M.J.; Holmes, D.G.; Nielsen, J.G.

2005-01-01

Dynamic voltage restorers (DVRs) are now becoming more established in industry to reduce the impact of voltage sags to sensitive loads. However, DVRs spend most of their time in standby mode, since voltage sags occur very infrequently, and hence their utilization is low. In principle, it would...... be advantageous if the series-connected inverter of a DVR could also be used to compensate for any steady-state load voltage harmonics, since this would increase the power quality "value-added" benefits to the grid system. However, before this can be done, consideration must be given to the control of steady......-state power through the DVR, the increased losses, and the low modulation depths at which the scheme must operate to achieve acceptable harmonic compensation performance. This paper presents a selective harmonic feedback control strategy that can be easily added to medium-voltage DVR systems to provide...

Neutral-point voltage dynamic model of three-level NPC inverter for reactive load

DEFF Research Database (Denmark)

Maheshwari, Ram Krishan; Munk-Nielsen, Stig; Busquets-Monge, Sergio

2012-01-01

A three-level neutral-point-clamped inverter needs a controller for the neutral-point voltage. Typically, the controller design is based on a dynamic model. The dynamic model of the neutral-point voltage depends on the pulse width modulation technique used for the inverter. A pulse width modulati...

Response of dairy cattle to transient voltages and magnetic fields

International Nuclear Information System (INIS)

Reinemann, D.J.; Laughlin, N.K.; Stetson, L.E.

1995-01-01

Stray voltages in dairy facilities have been studied since the 1970's. Previous research using steady-state ac and dc voltages has defined cow-contact voltage levels which may cause behavior and associated production problems. This research was designed to address concerns over possible effects of transient voltages and magnetic fields on dairy cows. Dairy cows response to transient voltages and magnetic fields was measured. The waveforms of the transient voltages applied were: 5 cycles of 60-Hz ac with a total pulse time of 83 ms, 1 cycle of 60-Hz ac with a total pulse time of 16 ms, and 1 cycle of an ac square wave (spiking positive and negative) of 2-ms duration. Alternating magnetic fields were produced by passing 60-Hz ac fundamental frequency with 2nd and 3rd harmonic and random noise components in metal structures around the cows. The maximum magnetic field associated with this current flow was in excess of 4 G. A wide range of sensitivity to transient voltages was observed among cows. Response levels from 24 cows to each transient exposure were normally distributed. No responses to magnetic fields were observed

Harmonic elimination technique for a single-phase multilevel converter with unequal DC link voltage levels

DEFF Research Database (Denmark)

Ghasemi, N.; Zare, F.; Boora, A.A.

2012-01-01

Multilevel converters, because of the benefits they attract in generating high quality output voltage, are used in several applications. Various modulation and control techniques are introduced by several researchers to control the output voltage of the multilevel converters like space vector...... modulation and harmonic elimination (HE) methods. Multilevel converters may have a DC link with equal or unequal DC voltages. In this study a new HE technique based on the HE method is proposed for multilevel converters with unequal DC link voltage. The DC link voltage levels are considered as additional...

Aligned energy-level design for decreasing operation voltage of tandem white organic light-emitting diodes

International Nuclear Information System (INIS)

Chang, Chih-Hao; Wu, Zih-Jyun; Liang, Yi-Hu; Chang, Yu-Shuo; Chiu, Chuan-Hao; Tai, Cheng-Wei; Chang, Hsin-Hua

2013-01-01

In general, organic light-emitting devices (OLEDs) need to operate at higher current density levels to ensure an ample light flux. However, stressed operation will result in poor performance and limited device lifetime. Recently, a tandem structure has been proposed as a pivotal technique to meet the stringent lighting requirements for OLED commercialization, with a research focus on decreasing the concomitant higher operation voltage. Driving two connected emission units (EMUs) in a tandem structure often requires more than twice the driving voltage for a single EMU. This study investigates bipolar host materials and their effective employment in fabricating tandem white phosphorescent OLEDs (PhOLEDs). In addition, the design of a mechanism to align the energy level between the hole transport layer/emitting layer is shown to effectively mitigate operational voltages. In sharp contrast to devices using a unipolar host material, we demonstrate that the turn-on voltage of blue PhOLEDs could be decreased from 3.8 V to 2.7 V through utilizing a bipolar host. Furthermore, applying the proposed techniques to tandem white PhOLEDs produces a luminance of 10 3 cd/m 2 by a 10.1 V driving voltage. - Highlights: • The matched energy level between the hole transport/emitting layer lowers voltages. • Multiple conduction dopants were used to investigate charge generation layer. • Two-color emitters were used to quantify the charge generation strength

30 CFR 62.130 - Permissible exposure level.

Science.gov (United States)

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Permissible exposure level. 62.130 Section 62... REGULATIONS OCCUPATIONAL NOISE EXPOSURE § 62.130 Permissible exposure level. (a) The mine operator must assure that no miner is exposed during any work shift to noise that exceeds the permissible exposure level. If...

The need for a common standard for voltage levels of HVDC VSC technology

International Nuclear Information System (INIS)

Müller, H.K.; Torbaghan, S. Shariat; Gibescu, M.; Roggenkamp, M.M.; Meijden, M.A.M.M. van der

2013-01-01

The expansion of offshore wind energy as well as the increase in electricity trade between the North Sea countries leads to a growing need for additional transmission capacity. Due to the predominantly remote locations of offshore wind farms, the majority of future connections will be high-voltage direct current (HVDC) connections. In order to make the construction of offshore infrastructure more efficient, the North Sea states are currently discussing the development of a common offshore grid. Although this development still stands at the very beginning, we argue in this paper that some crucial elements should be standardized from the outset; the most important one being a common voltage level. Without such standardization, the development of a European offshore grid may be suboptimal, not cost-efficient and might even be prevented from coming into existence. We examine the technical and legal issues associated with introducing a common voltage level for the use of HVDC VSC technology, and discuss the optimal standard as well as the way in which this common standard can best be achieved. - Highlights: • We highlight the need for a common standard for HVDC VSC technology. • We outline that a standardized voltage level at ± 500 kV should be the initial focus. • We discuss the developments regarding standardization of HVDC VSC technology. • We conclude that current developments are not sufficient

Aligned energy-level design for decreasing operation voltage of tandem white organic light-emitting diodes

Energy Technology Data Exchange (ETDEWEB)

Chang, Chih-Hao, E-mail: chc@saturn.yzu.edu.tw [Department of Photonics Engineering, Yuan Ze University, Chung-Li 32003, Taiwan, ROC (China); Wu, Zih-Jyun; Liang, Yi-Hu; Chang, Yu-Shuo; Chiu, Chuan-Hao; Tai, Cheng-Wei [Department of Photonics Engineering, Yuan Ze University, Chung-Li 32003, Taiwan, ROC (China); Chang, Hsin-Hua, E-mail: hhua3@mail.vnu.edu.tw [Department of Electro-Optical Engineering, Vanung University, Chung-Li 32061, Taiwan, ROC (China)

2013-12-02

In general, organic light-emitting devices (OLEDs) need to operate at higher current density levels to ensure an ample light flux. However, stressed operation will result in poor performance and limited device lifetime. Recently, a tandem structure has been proposed as a pivotal technique to meet the stringent lighting requirements for OLED commercialization, with a research focus on decreasing the concomitant higher operation voltage. Driving two connected emission units (EMUs) in a tandem structure often requires more than twice the driving voltage for a single EMU. This study investigates bipolar host materials and their effective employment in fabricating tandem white phosphorescent OLEDs (PhOLEDs). In addition, the design of a mechanism to align the energy level between the hole transport layer/emitting layer is shown to effectively mitigate operational voltages. In sharp contrast to devices using a unipolar host material, we demonstrate that the turn-on voltage of blue PhOLEDs could be decreased from 3.8 V to 2.7 V through utilizing a bipolar host. Furthermore, applying the proposed techniques to tandem white PhOLEDs produces a luminance of 10{sup 3} cd/m{sup 2} by a 10.1 V driving voltage. - Highlights: • The matched energy level between the hole transport/emitting layer lowers voltages. • Multiple conduction dopants were used to investigate charge generation layer. • Two-color emitters were used to quantify the charge generation strength.

Three-Level Inverters with Common-Mode Voltage Cancellation Based on Synchronous Pulsewidth Modulation

DEFF Research Database (Denmark)

Oleschuk, Valentin; Blaabjerg, Frede

2002-01-01

A novel method of direct synchronous pulse-width modulation (PWM) is disseminated to three-level voltage source inverters with control algorithms with elimination of the common-mode voltages in three-phase drive systems with PWM. It provides smooth pulses-ratio changing and a quarter-wave symmetry...... of the voltage waveforms during the whole control range including overmodulation. Continuous, discontinuous and "direct-direct" schemes of synchronous PWM with both algebraic and trigonometric control functions have been analysed and compared. Simulations give the behaviour of the proposed methods and show some...... advantages of synchronous PWM in comparison with asynchronous at low ratios between the switching frequency and fundamental frequency....

Measurement and Modeling of Personal Exposure to the Electric and Magnetic Fields in the Vicinity of High Voltage Power Lines

Directory of Open Access Journals (Sweden)

Wafa Tourab

2016-06-01

Conclusion: We project to set own national standards for exposure to electromagnetic fields, in order to achieve a regional database that will be at the disposal of partners concerned to ensure safety of people and mainly workers inside high voltage electrical substations.

Stray voltage mitigation

Energy Technology Data Exchange (ETDEWEB)

Jamali, B.; Piercy, R.; Dick, P. [Kinetrics Inc., Toronto, ON (Canada). Transmission and Distribution Technologies

2008-04-09

This report discussed issues related to farm stray voltage and evaluated mitigation strategies and costs for limiting voltage to farms. A 3-phase, 3-wire system with no neutral ground was used throughout North America before the 1930s. Transformers were connected phase to phase without any electrical connection between the primary and secondary sides of the transformers. Distribution voltage levels were then increased and multi-grounded neutral wires were added. The earth now forms a parallel return path for the neutral current that allows part of the neutral current to flow continuously through the earth. The arrangement is responsible for causing stray voltage. Stray voltage causes uneven milk production, increased incidences of mastitis, and can create a reluctance to drink water amongst cows when stray voltages are present. Off-farm sources of stray voltage include phase unbalances, undersized neutral wire, and high resistance splices on the neutral wire. Mitigation strategies for reducing stray voltage include phase balancing; conversion from single to 3-phase; increasing distribution voltage levels, and changing pole configurations. 22 refs., 5 tabs., 13 figs.

High-voltage measurements on the 5 ppm relative uncertainty level with collinear laser spectroscopy

Science.gov (United States)

Krämer, J.; König, K.; Geppert, Ch; Imgram, P.; Maaß, B.; Meisner, J.; Otten, E. W.; Passon, S.; Ratajczyk, T.; Ullmann, J.; Nörtershäuser, W.

2018-04-01

We present the results of high-voltage collinear laser spectroscopy measurements on the 5 ppm relative uncertainty level using a pump and probe scheme at the 4s ^2S1/2 → 4p ^2P3/2 transition of {\\hspace{0pt}}40Ca+ involving the 3d ^2D5/2 metastable state. With two-stage laser interaction and a reference measurement we can eliminate systematic effects such as differences in the contact potentials due to different electrode materials and thermoelectric voltages, and the unknown starting potential of the ions in the ion source. Voltage measurements were performed between  -5 kV and  -19 kV and parallel measurements with stable high-voltage dividers calibrated to 5 ppm relative uncertainty were used as a reference. Our measurements are compatible with the uncertainty limits of the high-voltage dividers and demonstrate an unprecedented (factor of 20) increase in the precision of direct laser-based high-voltage measurements.

An Enhanced Three-Level Voltage Switching State Scheme for Direct Torque Controlled Open End Winding Induction Motor

Science.gov (United States)

Kunisetti, V. Praveen Kumar; Thippiripati, Vinay Kumar

2018-01-01

Open End Winding Induction Motors (OEWIM) are popular for electric vehicles, ship propulsion applications due to less DC link voltage. Electric vehicles, ship propulsions require ripple free torque. In this article, an enhanced three-level voltage switching state scheme for direct torque controlled OEWIM drive is implemented to reduce torque and flux ripples. The limitations of conventional Direct Torque Control (DTC) are: possible problems during low speeds and starting, it operates with variable switching frequency due to hysteresis controllers and produces higher torque and flux ripple. The proposed DTC scheme can abate the problems of conventional DTC with an enhanced voltage switching state scheme. The three-level inversion was obtained by operating inverters with equal DC-link voltages and it produces 18 voltage space vectors. These 18 vectors are divided into low and high frequencies of operation based on rotor speed. The hardware results prove the validity of proposed DTC scheme during steady-state and transients. From simulation and experimental results, proposed DTC scheme gives less torque and flux ripples on comparison to two-level DTC. The proposed DTC is implemented using dSPACE DS-1104 control board interface with MATLAB/SIMULINK-RTI model.

Grid Integration of Single Stage Solar PV System using Three-level Voltage Source Converter

Science.gov (United States)

Hussain, Ikhlaq; Kandpal, Maulik; Singh, Bhim

2016-08-01

This paper presents a single stage solar PV (photovoltaic) grid integrated power generating system using a three level voltage source converter (VSC) operating at low switching frequency of 900 Hz with robust synchronizing phase locked loop (RS-PLL) based control algorithm. To track the maximum power from solar PV array, an incremental conductance algorithm is used and this maximum power is fed to the grid via three-level VSC. The use of single stage system with three level VSC offers the advantage of low switching losses and the operation at high voltages and high power which results in enhancement of power quality in the proposed system. Simulated results validate the design and control algorithm under steady state and dynamic conditions.

Effective high voltage at X-ray tube in hard X-ray chest imaging

International Nuclear Information System (INIS)

Klein, J.

1987-01-01

The FRG standard TGL 36 661 (March 1980) for synoptical chest pictures of large size in adults specifies the 120 kV voltage at the X-ray tube together with maximal, 100% use of the capacity of the tube (hard picture, short exposure time). By means of circular recording and by measuring the high voltage at the X-ray tube it was quantitatively shown that the effective voltage during exposure is (according to the exposure time and the attenuation phase of the generator) always lower than the set-up voltage of 120 kV. This phenomenon is the more marked the shorter the actual exposure time in comparison with the attenuation phase of the generator. The typical characteristic of a hard X-ray chest picture is thus not given only by the setting-up of voltage. The impact of the reduction in voltage is thus quantitatively shown also from the aspect of the radiation burden for the patient. (author). 7 figs., 8 refs

Five-Phase Five-Level Open-Winding/Star-Winding Inverter Drive for Low-Voltage/High-Current Applications

DEFF Research Database (Denmark)

Padmanaban, Sanjeevi Kumar; Blaabjerg, Frede; Wheeler, Patrick

2016-01-01

This paper work proposed a five-phase five-level open-/star-winding multilevel AC converter suitable for low-voltage/high-current applications. Modular converter consists of classical two-level five-phase voltage source inverter (VSI) with slight reconfiguration to serve as a multilevel converter...... for open-/star-winding loads. Elaborately, per phase of the VSI is built with one additional bi-directional switch (MOSFET/IGBT) and all five legs links to the neutral through two capacitors. The structure allows multilevel generation to five-level output with greater potential for fault tolerability under...

Capacitor Voltages Measurement and Balancing in Flying Capacitor Multilevel Converters Utilizing a Single Voltage Sensor

DEFF Research Database (Denmark)

Farivar, Glen; Ghias, Amer M. Y. M.; Hredzak, Branislav

2017-01-01

This paper proposes a new method for measuring capacitor voltages in multilevel flying capacitor (FC) converters that requires only one voltage sensor per phase leg. Multiple dc voltage sensors traditionally used to measure the capacitor voltages are replaced with a single voltage sensor at the ac...... side of the phase leg. The proposed method is subsequently used to balance the capacitor voltages using only the measured ac voltage. The operation of the proposed measurement and balancing method is independent of the number of the converter levels. Experimental results presented for a five-level FC...

Loading Analysis of Modular Multi-level Converter for Offshore High-voltage DC Application under Various Grid Faults

DEFF Research Database (Denmark)

Liu, Hui; Ma, Ke; Loh, Poh Chiang

2016-01-01

challenges but may also result in overstressed components for the modular multi-level converter. However, the thermal loading of the modular multi-level converter under various grid faults has not yet been clarified. In this article, the power loss and thermal performance of the modular multi-level converter...... low-voltage ride-through strongly depend on the types and severity values of grid voltage dips. The thermal distribution among the three phases of the modular multi-level converter may be quite uneven, and some devices are much more stressed than the normal operating condition, which may...

Transient voltage sharing in series-coupled high voltage switches

Directory of Open Access Journals (Sweden)

Editorial Office

1992-07-01

Full Text Available For switching voltages in excess of the maximum blocking voltage of a switching element (for example, thyristor, MOSFET or bipolar transistor such elements are often coupled in series - and additional circuitry has to be provided to ensure equal voltage sharing. Between each such series element and system ground there is a certain parasitic capacitance that may draw a significant current during high-speed voltage transients. The "open" switch is modelled as a ladder network. Analy­sis reveals an exponential progression in the distribution of the applied voltage across the elements. Overstressing thus oc­curs in some of the elements at levels of the total voltage that are significantly below the design value. This difficulty is overcome by grading the voltage sharing circuitry, coupled in parallel with each element, in a prescribed manner, as set out here.

Low-Energy Real-Time OS Using Voltage Scheduling Algorithm for Variable Voltage Processors

OpenAIRE

Okuma, Takanori; Yasuura, Hiroto

2001-01-01

This paper presents a real-time OS based on $ mu $ITRON using proposed voltage scheduling algorithm for variable voltage processors which can vary supply voltage dynamically. The proposed voltage scheduling algorithms assign voltage level for each task dynamically in order to minimize energy consumption under timing constraints. Using the presented real-time OS, running tasks with low supply voltage leads to drastic energy reduction. In addition, the presented voltage scheduling algorithm is ...

Electrooptic Methods for Measurement of Small DC Currents at High Voltage Level

DEFF Research Database (Denmark)

Tønnesen, Ole; Beatty, Neville; Skilbreid, Asbjørn Ottar

1989-01-01

collectors are connected via resistors RA and RB to the protective side of the voltage to be measured and the emitters to the negative side. The currents flowing in to the bases of the transistors are independently controlled by the light levels following on the two photodiodes PDA, PDB....

A Robust Control Scheme for Medium-Voltage-Level DVR Implementation

DEFF Research Database (Denmark)

Blaabjerg, Frede; Loh, Poh Chiang; Li, Yun Wei

2007-01-01

of Hinfin controller weighting function selection, inner current loop tuning, and system disturbance rejection capability is presented. Finally, the designed control scheme is extensively tested on a laboratory 10-kV MV-level DVR system with varying voltage sag (balanced and unbalanced) and loading (linear....../nonlinear load and induction motor load) conditions. It is shown that the proposed control scheme is effective in both balanced and unbalanced sag compensation and load disturbance rejection, as its robustness is explicitly specified....

Direct Power Control for Three-Phase Two-Level Voltage-Source Rectifiers Based on Extended-State Observation

DEFF Research Database (Denmark)

Song, Zhanfeng; Tian, Yanjun; Yan, Zhuo

2016-01-01

This paper proposed a direct power control strategy for three-phase two-level voltage-source rectifiers based on extended-state observation. Active and reactive powers are directly regulated in the stationary reference frame. Similar to the family of predictive controllers whose inherent characte......This paper proposed a direct power control strategy for three-phase two-level voltage-source rectifiers based on extended-state observation. Active and reactive powers are directly regulated in the stationary reference frame. Similar to the family of predictive controllers whose inherent...

New Modulation Strategy to Balance the Neutral-Point Voltage for Three-Level Neutral-Clamped Inverter Systems

DEFF Research Database (Denmark)

Choi, Uimin; Lee, June-Seok; Lee, Kyo-Beum

2014-01-01

This paper proposes a new modulation strategy that balances the neutral-point voltage for three-level neutral-clamped inverter systems. The proposed modulation replaces the P-type or N-type small switching states with other switching states that do not affect the neutral-point voltage. The zero...... and medium switching states are employed to help the neutral-point voltage balancing. This method little bit increases the switching events and output total harmonic distortion. However, this method has a strong balancing ability at all regions. Further, it is very simple to implement in both space vector...

Development of acute exposure guideline levels for airborne exposures to hazardous substances.

Science.gov (United States)

Krewski, Daniel; Bakshi, Kulbir; Garrett, Roger; Falke, Ernest; Rusch, George; Gaylor, David

2004-04-01

Hazardous substances can be released into the atmosphere due to industrial and transportation accidents, fires, tornadoes, earthquakes, and terrorists, thereby exposing workers and the nearby public to potential adverse health effects. Various enforceable guidelines have been set by regulatory agencies for worker and ambient air quality. However, these exposure levels generally are not applicable to rare lifetime acute exposures, which possibly could occur at high concentrations. Acute exposure guideline levels (AEGLs) provide estimates of concentrations for airborne exposures for an array of short durations that possibly could cause mild (AEGL-1), severe, irreversible, potentially disabling adverse health effects (AEGL-2), or life threatening effects (AEGL-3). These levels can be useful for emergency responders and planners in reducing or eliminating potential risks to the public. Procedures and methodologies for deriving AEGLs are reviewed in this paper that have been developed in the United States, with direct input from international representatives of OECD member-countries, by the National Advisory Committee for Acute Exposure Guidelines for Hazardous Substances and reviewed by the National Research Council. Techniques are discussed for the extrapolation of effects across different exposure durations. AEGLs provide a viable approach for assisting in the prevention, planning, and response to acute airborne exposures to toxic agents.

Spectrum analysis of a voltage source converter due to semiconductor voltage drops

DEFF Research Database (Denmark)

Rasmussen, Tonny Wederberg; Eltouki, Mustafa

2017-01-01

It is known that power electronic voltage source converters are non-ideal. This paper presents a state-of-the-art review on the effect of semiconductor voltage drop on the output voltage spectrum, using single-phase H-bridge two-level converter topology with natural sampled pulse width modulation....... The paper describes the analysis of output voltage spectrum, when the semiconductor voltage drop is added. The results of the analysis of the spectral contribution including and excluding semiconductor voltage drop reveal a good agreement between the theoretical results, simulations and laboratory...

Simulation of rectifier voltage malfunction on OWECS, four-level converter, HVDC light link: Smart grid context tool

International Nuclear Information System (INIS)

Seixas, M.; Melício, R.; Mendes, V.M.F.

2015-01-01

Highlights: • Floating offshore wind turbine in deep water. • DC link and voltage malfunction. • Converter topology considered is four-level. • Controllers are based on fractional-order. • Smart grid context. - Abstract: This paper presents a model for the simulation of an offshore wind system having a rectifier input voltage malfunction at one phase. The offshore wind system model comprises a variable-speed wind turbine supported on a floating platform, equipped with a permanent magnet synchronous generator using full-power four-level neutral point clamped converter. The link from the offshore floating platform to the onshore electrical grid is done through a light high voltage direct current submarine cable. The drive train is modeled by a three-mass model. Considerations about the smart grid context are offered for the use of the model in such a context. The rectifier voltage malfunction domino effect is presented as a case study to show capabilities of the model

Controlling Voltage Levels of Distribution Network-Radial Feeder after Connecting Wind Turbines to the Network

Directory of Open Access Journals (Sweden)

Muhammad Al Badri

2017-11-01

Full Text Available Several factors in power generation and supply need to be taken into account such as shortages of energy supply, system stability, and energy quality and system disruption due to network losses, industrial development and population expansion. The addition of wind turbines to the distribution network is of great benefit in providing additional power and solving these problems, but this addition is accompanied by the problem of low voltage network. This research found optimal solutions to the problem of low voltage distribution network after connecting wind turbines. The main idea of this paper is to optimize the low-voltage problem as a result of connecting the wind turbines to the "far end" of the radial feeder for a distribution network and to obtain a voltage level within an acceptable and stable range. The problem of low voltage solved by using the load-drop compensation, capacitor-bank and “doubly-fed” induction generators. The results of this study were based on the operation of the entire design of the simulation system which would be compatible with the reality of the energy flow of all network components by using the PSCAD program. The present analysis program revealed an optimum solution for the low voltage profile of the distribution network after connecting the wind turbine.

Radiation exposure to children in intraoral dental radiology

International Nuclear Information System (INIS)

Looe, H. K.; Pfaffenberger, A.; Chofor, N.; Eenboom, F.; Sering, M.; Ruehmann, A.; Poplawski, A.; Willborn, K.; Poppe, B.

2006-01-01

In this study, dose area product (DAP) measurements have been performed aiming at establishing diagnostic reference levels (DRLs) in paediatric intraoral dental radiology. Measurements were carried out at 52 X-ray units for all types of intraoral examinations performed in clinical routine. Not all X-ray units have pre-set child exposure settings with reduced exposure time or in some cases lower tube voltage. Child examinations are carried out using adult exposure settings at these units, which increases the DAP third quartile values by up to 50%. For example, third quartile values for peri-apical examination ranges from 14.4 to 40.9 mGy cm 2 for child settings and 20.6 to 48.8 mGy cm 2 when the adult settings are included. The results show that there exists a large difference between the patient exposures among different dental facilities. It was also observed that clinics working with faster film type or higher tube voltage are not always associated with lower exposure. (authors)

High-Voltage-Input Level Translator Using Standard CMOS

Science.gov (United States)

Yager, Jeremy A.; Mojarradi, Mohammad M.; Vo, Tuan A.; Blalock, Benjamin J.

2011-01-01

proposed integrated circuit would translate (1) a pair of input signals having a low differential potential and a possibly high common-mode potential into (2) a pair of output signals having the same low differential potential and a low common-mode potential. As used here, "low" and "high" refer to potentials that are, respectively, below or above the nominal supply potential (3.3 V) at which standard complementary metal oxide/semiconductor (CMOS) integrated circuits are designed to operate. The input common-mode potential could lie between 0 and 10 V; the output common-mode potential would be 2 V. This translation would make it possible to process the pair of signals by use of standard 3.3-V CMOS analog and/or mixed-signal (analog and digital) circuitry on the same integrated-circuit chip. A schematic of the circuit is shown in the figure. Standard 3.3-V CMOS circuitry cannot withstand input potentials greater than about 4 V. However, there are many applications that involve low-differential-potential, high-common-mode-potential input signal pairs and in which standard 3.3-V CMOS circuitry, which is relatively inexpensive, would be the most appropriate circuitry for performing other functions on the integrated-circuit chip that handles the high-potential input signals. Thus, there is a need to combine high-voltage input circuitry with standard low-voltage CMOS circuitry on the same integrated-circuit chip. The proposed circuit would satisfy this need. In the proposed circuit, the input signals would be coupled into both a level-shifting pair and a common-mode-sensing pair of CMOS transistors. The output of the level-shifting pair would be fed as input to a differential pair of transistors. The resulting differential current output would pass through six standoff transistors to be mirrored into an output branch by four heterojunction bipolar transistors. The mirrored differential current would be converted back to potential by a pair of diode-connected transistors

Multilevel Converter by Cascading Two-Level Three-Phase Voltage Source Converter

Directory of Open Access Journals (Sweden)

Abdullrahman A. Al-Shamma’a

2018-04-01

Full Text Available This paper proposes a topology using isolated, cascaded multilevel voltage source converters (VSCs and employing two-winding magnetic elements for high-power applications. The proposed topology synthesizes 6 two-level, three-phase VSCs, so the power capability of the presented converter is six times the capability of each VSC module. The characteristics of the proposed topology are demonstrated through analyzing its current relationships, voltage relationships and power capability in detail. The power rating is equally shared among the VSC modules without the need for a sharing algorithm; thus, the converter operates as a single three-phase VSC. The comparative analysis with classical neutral-point clamped, flying capacitor and cascaded H-bridge exhibits the superior features of fewer insulated gate bipolar transistors (IGBTs, capacitor requirement and fewer diodes. To validate the theoretical performance of the proposed converter, it is simulated in a MATLAB/Simulink environment and the results are experimentally demonstrated using a laboratory prototype.

Voltage-dependent gating in a "voltage sensor-less" ion channel.

Directory of Open Access Journals (Sweden)

Harley T Kurata

2010-02-01

Full Text Available The voltage sensitivity of voltage-gated cation channels is primarily attributed to conformational changes of a four transmembrane segment voltage-sensing domain, conserved across many levels of biological complexity. We have identified a remarkable point mutation that confers significant voltage dependence to Kir6.2, a ligand-gated channel that lacks any canonical voltage-sensing domain. Similar to voltage-dependent Kv channels, the Kir6.2[L157E] mutant exhibits time-dependent activation upon membrane depolarization, resulting in an outwardly rectifying current-voltage relationship. This voltage dependence is convergent with the intrinsic ligand-dependent gating mechanisms of Kir6.2, since increasing the membrane PIP2 content saturates Po and eliminates voltage dependence, whereas voltage activation is more dramatic when channel Po is reduced by application of ATP or poly-lysine. These experiments thus demonstrate an inherent voltage dependence of gating in a "ligand-gated" K+ channel, and thereby provide a new view of voltage-dependent gating mechanisms in ion channels. Most interestingly, the voltage- and ligand-dependent gating of Kir6.2[L157E] is highly sensitive to intracellular [K+], indicating an interaction between ion permeation and gating. While these two key features of channel function are classically dealt with separately, the results provide a framework for understanding their interaction, which is likely to be a general, if latent, feature of the superfamily of cation channels.

Exposure levels and determinants of inhalable dust exposure in bakeries.

Science.gov (United States)

Burstyn, I; Teschke, K; Kennedy, S M

1997-12-01

The study's objectives were to measure full-shift exposure to inhalable dust in bakeries and define the determinants of full-shift exposure. Inhalable dust was measured gravimetrically. Ninety-six bakery workers, employed in seven different bakeries, participated in the study. Two side-by-side full-shift inhalable dust samples were obtained from each study participant on a single occasion. Samples were collected on 18 days selected at random. During the entire sampling period, bakers were observed and information on 14 different tasks was recorded at 15 min intervals. Other production characteristics were also recorded for each sampling day. These task and production variables were used in statistical modelling to identify significant predictors of exposure. The mean full-shift inhalable dust exposure was 8.2 mg/m3 (range: 0.1-110 mg/m3). A regression model explained 79% of the variability in exposure. The model indicated that tasks such as weighing, pouring and operating dough-brakers and reversible sheeters increased the exposure, while packing, catching and decorating decreased the exposure. Bread and bun production lines were associated with increased full-shift inhalable dust exposure, while cake production and substitution of dusting with the use of divider oil were associated with decreased exposure. Production tasks and characteristics are strong predictors of personal full-shift exposures to flour dust among bakers; these can be altered to reduce exposure levels.

Voltage-Level Selection of Future Two-Level LVdc Distribution Grids

DEFF Research Database (Denmark)

Diaz, Enrique Rodriguez; Chen, Fang; Quintero, Juan Carlos Vasquez

2016-01-01

significantly. Microgrids (MGs) come as a suitable solution for the installation of distributed sources in the low voltage grid, where most of the consumers are sparsely located. Microgrids ease the integration of distributed generators (DGs), especially renewable energy sources like solar panels and small wind...

A quasi-3-dimensional simulation method for a high-voltage level-shifting circuit structure

International Nuclear Information System (INIS)

Liu Jizhi; Chen Xingbi

2009-01-01

A new quasi-three-dimensional (quasi-3D) numeric simulation method for a high-voltage level-shifting circuit structure is proposed. The performances of the 3D structure are analyzed by combining some 2D device structures; the 2D devices are in two planes perpendicular to each other and to the surface of the semiconductor. In comparison with Davinci, the full 3D device simulation tool, the quasi-3D simulation method can give results for the potential and current distribution of the 3D high-voltage level-shifting circuit structure with appropriate accuracy and the total CPU time for simulation is significantly reduced. The quasi-3D simulation technique can be used in many cases with advantages such as saving computing time, making no demands on the high-end computer terminals, and being easy to operate. (semiconductor integrated circuits)

A quasi-3-dimensional simulation method for a high-voltage level-shifting circuit structure

Energy Technology Data Exchange (ETDEWEB)

Liu Jizhi; Chen Xingbi, E-mail: jzhliu@uestc.edu.c [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China)

2009-12-15

A new quasi-three-dimensional (quasi-3D) numeric simulation method for a high-voltage level-shifting circuit structure is proposed. The performances of the 3D structure are analyzed by combining some 2D device structures; the 2D devices are in two planes perpendicular to each other and to the surface of the semiconductor. In comparison with Davinci, the full 3D device simulation tool, the quasi-3D simulation method can give results for the potential and current distribution of the 3D high-voltage level-shifting circuit structure with appropriate accuracy and the total CPU time for simulation is significantly reduced. The quasi-3D simulation technique can be used in many cases with advantages such as saving computing time, making no demands on the high-end computer terminals, and being easy to operate. (semiconductor integrated circuits)

The fabrication of 3-D nanostructures by a low- voltage EBL

Energy Technology Data Exchange (ETDEWEB)

Oh, Seung Hun [Department of Nano Science and Technology, Pusan National University (Korea, Republic of); Kim, Jae Gu [Department of Nano-Mechanical Systems, Korea Institute of Machinery and Materials (Korea, Republic of); Kim, Chang Seok [Department of Cogno-Mechatronics Engineering, Pusan National University (Korea, Republic of); Choi, Doo Sun; Chang, Sunghwan [Department of Nano-Mechanical Systems, Korea Institute of Machinery and Materials (Korea, Republic of); Jeong, Myung Yung, E-mail: myjeong@pusan.ac.kr [Department of Cogno-Mechatronics Engineering, Pusan National University (Korea, Republic of)

2011-02-15

Three-dimensional (3-D) structures are used in many applications, including the fabrication of opto-electronic and bio-MEMS devices. Among the various fabrication techniques available for 3-D structures, nano imprint lithography (NIL) is preferred for producing nanoscale 3-D patterns because of its simplicity, relatively short processing time, and high manufacturing precision. For efficient replication in NIL, a precise 3-D stamp must be used as an imprinting tool. Hence, we attempted the fabrication of original 3-D master molds by low-voltage electron beam lithography (EBL). We then fabricated polydimethylsiloxane (PDMS) stamps from the original 3-D mold via replica molding with ultrasonic vibration.First, we experimentally analyzed the characteristics of low-voltage EBL in terms of various parameters such as resist thickness, acceleration voltage, aperture size, and baking temperature. From these e-beam exposure experiments, we found that the exposure depth and width were almost saturated at 3 kV or lesser, even when the electron dosage was increased. This allowed for the fabrication of various stepped 3-D nanostructures at a low voltage. In addition, by using line-dose EBL, V-groove patterns could be fabricated on a cured electron resist (ER) at a low voltage and low baking temperature. Finally, the depth variation could be controlled to within 10 nm through superposition exposure at 1 kV. From these results, we determined the optimum electron beam exposure conditions for the fabrication of various 3-D structures on ERs by low-voltage EBL. We then fabricated PDMS stamps via the replica molding process.

Design of Neutral-Point Voltage Controller of a Three-level NPC Inverter with Small DC-Link Capacitors

DEFF Research Database (Denmark)

Maheshwari, Ram Krishan; Munk-Nielsen, Stig; Busquets-Monge, S.

2013-01-01

A Neutral-Point-Clamped (NPC) three-level inverter with small dc-link capacitors is presented in this paper. The inverter requires zero average neutral-point current for stable neutral-point voltage. The small dc-link capacitors may not maintain capacitor voltage balance, even with zero neutral......-point voltage control on the basis of the continuous model. The design method for optimum performance is discussed. The implementation of the proposed modulation strategy and the controller is very simple. The controller is implemented in a 7.5 kW induction machine based drive with only 14 ìF dc-link capacitors...

Behavior of deep level defects on voltage-induced stress of Cu(In,Ga)Se{sub 2} solar cells

Energy Technology Data Exchange (ETDEWEB)

Lee, D.W.; Cho, S.E. [Department of Physics and Semiconductor Science, Dongguk University, Seoul (Korea, Republic of); Jeong, J.H. [Solar Cell Center, Korea Institute of Science and Technology, Seoul (Korea, Republic of); Cho, H.Y., E-mail: hycho@dongguk.edu [Department of Physics and Semiconductor Science, Dongguk University, Seoul (Korea, Republic of)

2015-05-01

The behavior of deep level defects by a voltage-induced stress for CuInGaSe{sub 2} (CIGS) solar cells has been investigated. CIGS solar cells were used with standard structures which are Al-doped ZnO/i-ZnO/CdS/CIGSe{sub 2}/Mo on soda lime glass, and that resulted in conversion efficiencies as high as 16%. The samples with the same structure were isothermally stressed at 100 °C under the reverse voltages. The voltage-induced stressing in CIGS samples causes a decrease in the carrier density and conversion efficiency. To investigate the behavior of deep level defects in the stressed CIGS cells, photo-induced current transient spectroscopy was utilized, and normally 3 deep level defects (including 2 hole traps and 1 electron trap) were found to be located at 0.18 eV and 0.29 eV above the valence band maximum (and 0.36 eV below the conduction band). In voltage-induced cells, especially, it was found that the decrease of the hole carrier density could be responsible for the increase of the 0.29 eV defect, which is known to be observed in less efficient CIGS solar cells. And the carrier density and the defects are reversible at least to a large extent by resting at room-temperature without the bias voltage. From optical capture kinetics in photo-induced current transient spectroscopy measurement, the types of defects could be distinguished into the isolated point defect and the extended defect. In this work, it is suggested that the increase of the 0.29 eV defect by voltage-induced stress could be due to electrical activation accompanied by a loss of positive ion species and the activated defect gives rise to reduction of the carrier density. - Highlights: • We investigated behavior of deep level defects by voltage-induced stress. • Defect generation could affect the decrease of the conversion efficiency of cells. • Defect generation could be electrically activated by a loss of positive ion species. • Type of defects could be studied with models of point defects

Space vector modulation strategy for neutral-point voltage balancing in three-level inverter systems

DEFF Research Database (Denmark)

Choi, Uimin; Lee, Kyo Beum

2013-01-01

This study proposes a space vector modulation (SVM) strategy to balance the neutral-point voltage of three-level inverter systems. The proposed method is implemented by combining conventional symmetric SVM with nearest three-vector (NTV) modulation. The conventional SVM is converted to NTV...... modulation by properly adding or subtracting a minimum gate-on time. In addition, using this method, the switching frequency is reduced and a decrease of switching loss would be yielded. The neutral-point voltage is balanced by the proposed SVM strategy without additional hardware or complex calculations....... Simulation and experimental results are shown to verify the validity and feasibility of the proposed SVM strategy....

Effects of high vs low-level radiation exposure

International Nuclear Information System (INIS)

Bond, V.P.

1983-01-01

In order to appreciate adequately the various possible effects of radiation, particularly from high-level vs low-level radiation exposure (HLRE, vs LLRE), it is necessary to understand the substantial differences between (a) exposure as used in exposure-incidence curves, which are always initially linear and without threshold, and (b) dose as used in dose-response curves, which always have a threshold, above which the function is curvilinear with increasing slope. The differences are discussed first in terms of generally familiar nonradiation situations involving dose vs exposure, and then specifically in terms of exposure to radiation, vs a dose of radiation. Examples are given of relevant biomedical findings illustrating that, while dose can be used with HLRE, it is inappropriate and misleading the LLRE where exposure is the conceptually correct measure of the amount of radiation involved

Self-aligned photolithography for the fabrication of fully transparent high-voltage devices

Science.gov (United States)

Zhang, Yonghui; Mei, Zengxia; Huo, Wenxing; Wang, Tao; Liang, Huili; Du, Xiaolong

2018-05-01

High-voltage devices, working in the range of hundreds of volts, are indispensable elements in the driving or readout circuits for various kinds of displays, integrated microelectromechanical systems and x-ray imaging sensors. However, the device performances are found hardly uniform or repeatable due to the misalignment issue, which are extremely common for offset drain high-voltage devices. To resolve this issue, this article reports a set of self-aligned photolithography technology for the fabrication of high-voltage devices. High-performance fully-transparent high-voltage thin film transistors, diodes and logic inverters are successfully fabricated with this technology. Unlike other self-aligned routes, opaque masks are introduced on the backside of the transparent substrate to facilitate proximity exposure method. The photolithography process is simulated and analyzed with technology computer aided design simulation to explain the working principle of the proximity exposure method. The substrate thickness is found to be vital for the implementation of this technology based on both simulation and experimental results. The electrical performance of high-voltage devices is dependent on the offset length, which can be delicately modulated by changing the exposure dose. The presented self-aligned photolithography technology is proved to be feasible in high-voltage circuits, demonstrating its huge potential in practical industrial applications.

Admissibility of building cost subsidy in the power grid above the low voltage level; Zulaessigkeit von Baukostenzuschuessen im Stromnetz oberhalb der Niederspannungsebene

Energy Technology Data Exchange (ETDEWEB)

Foerster, Sven [Kanzlei Norton Rose Fulbright LLP, Muenchen(Germany)

2015-07-01

Electricity networks are essential to the provision of electrical power to businesses and individuals. In particular for manufacturing businesses a connection to the grid above the low-voltage level is often useful. Network operators demand a subsidy for the new connection and for the change to a higher network level under the auspices of construction cost. The power network market above the low-voltage level is a natural monopoly. This leaves consumers looking for a connection to the power grid with no possibility to select among different network operators. Construction cost subsidies are not regulated by law above the low voltage level. The lack of legal regulation and the natural monopoly above the low-voltage level affect the balance of power between network operators and system users. The lawfulness of the construction cost subsidies, the prerequisites for their demand and a review of the calculation models (Leistungspreismodell, 2-Ebenen-Modell) as well as a proposal for a reform of this system form the subject of this work.

Exposure level of ergonomic risk factors in hotel industries

Science.gov (United States)

Nasrull Abdol Rahman, Mohd; Syahir Muhamad Jaffar, Mohd; Fahrul Hassan, Mohd; Zamani Ngali, Mohd; Pauline, Ong

2017-08-01

Ergonomic Risk Factors (ERFs) which contribute to Musculoskeletal Disorders (MSDs) among room attendants were considered as a problem or trouble since these ERFs would affect their work performance for hotel industries. The purpose of this study was to examine the exposure level of ERFs among room attendants in hotel industries. 65 of respondents were obtained from selected hotels in Peninsular Malaysia. Data were collected by direct observation via Workplace Ergonomic Risk Assessment (WERA) and Quick Exposure Checklist (QEC). There were 36 males and 29 females room attendants involved throughout the research. Most of room attendants experienced high exposure level for back, leg, forceful and vibration based on the exposure level evaluation through WERA while QEC results showed that all room attendants were found to have moderate exposure level for risk factors including back for movement use, shoulders/arms, wrists/hands and neck. All the results obtained showed that the related ERFs for MSDs were associated and essential ergonomic interventions are needed in order to eliminate risk of exposures to MSDs among room attendants in hotel industries.

Overview of the hazards of low-level exposure to radiation

International Nuclear Information System (INIS)

Ritenour, E.R.

1984-01-01

In this chapter the authors are concerned with low-level radiation, doses of ionizing radiations that are ten to thousands of times smaller than those required to contract ARS. Low-level radiation may be defined as an absorbed dose of 10 rem or less delivered over a short period of time. A larger dose delivered over a long period of time, for instance, 50 rem in 10 years, may also be considered low level. The definition is purposely loose so as to cover a wide variety of sources of radiation exposure, such as natural background (100 mrem/year) occupational exposures (<5 rem/year), and medical applications, such as diagnostic radiography (<1 rem). Low-level radiation exposure does not produce ARS. The health effects that may be of concern in regard to low-level radiation are its long-term sequelae. Studies of survivors of high-level radiation exposure (both human and laboratory animals) have indicated that there are three health effects that should be examined at low levels of exposure: induction of cancer, birth abnormalities (from irradiation in utero), and genetic effects. No other long-term effects of low-level exposure have been conclusively demonstrated in animals or humans

HELLE: Health Effects of Low Level Exposures

International Nuclear Information System (INIS)

Schoten, Eert

1998-01-01

The Health Council is closely involved in establishing the scientific foundation of exposure limits for substances and radiation in order to protect public health. Through the years, the Council has contributed to the formulation of principles and procedures, both for carcinogenic and for noncarcinogenic agents. As a rule, the discussion with regard to the derivation of health-based recommended exposure limits centers around the appropriateness of extrapolation methods (What can be inferred from data on high exposure levels and on experimental animals?). Generally speaking, there is a lack of direct information on the health effects of low levels of exposure. Effects at these levels cannot usually be detected by means of traditional animal experiments or epidemiological research. The capacity of these analytical instruments to distinguish between ''signal'' and ''noise'' is inadequate in most cases. Annex B of this report contains a brief outline of the difficulties and the established methods for tackling this problem. In spite of this, the hope exists that the posited weak signals, if they are indeed present, can be detected by other means. The search will have to take place on a deeper level. In other words, effort must be made to discover what occurs at underlying levels of biological organization when organisms are exposed to low doses of radiation or substances. Molecular and cell biology provide various methods and techniques which give an insight into the processes within the cell. This results in an increase in the knowledge about the molecular and cellular effects of exposure to agents, or stated differently, the working mechanisms which form the basis of the health effects. Last year, the Health Council considered that the time was ripe to take stock of the state of knowledge in this field. To this end, an international working conference was held from 19 to 21 October 1997, entitled ''Health Effects of Low Level Exposures: Scientific Developments and

Systematic Review of the Exposure Assessment and Epidemiology of High-Frequency Voltage Transients

Directory of Open Access Journals (Sweden)

Frank eDe Vocht

2016-03-01

Full Text Available Conclusions of epidemiological studies describing adverse health effects as a result of exposure to electromagnetic fields are not unanimous and often contradictory. It has been proposed that an explanation could be that high frequency voltage transients (dirty electricity [DE] which are superimposed on 50/60Hz fields, but are generally not measured, is the real causal agent. DE has been linked to many different health and wellbeing effects, and on the basis of this an industry selling measurement and filtering equipment is growing. We reviewed the available peer-reviewed evidence for DE as a causal agent for adverse human health effects.A literature search was performed in the Cochrane Library, PubMed, Web of Science, Google Scholar and additional publications were obtained from reference lists and from the grey literature. This search resulted in 25 publications; 16 included primary epidemiological and/or exposure data. All studies were reviewed by both authors independently, and including a re-review of studies included in a review of data available up to July 31 2009 by one of the authors. DE has been measured differently in different studies and comparison data are not available. There is no evidence for 50 Graham/Stetzer (G/S units as a safety threshold being anything more than arbitrary. The epidemiological evidence on human health effects of DE is primarily based on, often re-used, case descriptions. Quantitative evidence relies on self-reporting in non-blinded interventions, ecological associations, and one cross-sectional cohort study of cancer risk which does not point to DE as the causal agent. The available evidence for DE as an exposure affecting human health at present does not stand up to scientific scrutiny.

High voltage test techniques

CERN Document Server

Kind, Dieter

2001-01-01

The second edition of High Voltage Test Techniques has been completely revised. The present revision takes into account the latest international developments in High Voltage and Measurement technology, making it an essential reference for engineers in the testing field.High Voltage Technology belongs to the traditional area of Electrical Engineering. However, this is not to say that the area has stood still. New insulating materials, computing methods and voltage levels repeatedly pose new problems or open up methods of solution; electromagnetic compatibility (EMC) or components and systems al

Measurement and statistical analysis of single-molecule current-voltage characteristics, transition voltage spectroscopy, and tunneling barrier height.

Science.gov (United States)

Guo, Shaoyin; Hihath, Joshua; Díez-Pérez, Ismael; Tao, Nongjian

2011-11-30

We report on the measurement and statistical study of thousands of current-voltage characteristics and transition voltage spectra (TVS) of single-molecule junctions with different contact geometries that are rapidly acquired using a new break junction method at room temperature. This capability allows one to obtain current-voltage, conductance voltage, and transition voltage histograms, thus adding a new dimension to the previous conductance histogram analysis at a fixed low-bias voltage for single molecules. This method confirms the low-bias conductance values of alkanedithiols and biphenyldithiol reported in literature. However, at high biases the current shows large nonlinearity and asymmetry, and TVS allows for the determination of a critically important parameter, the tunneling barrier height or energy level alignment between the molecule and the electrodes of single-molecule junctions. The energy level alignment is found to depend on the molecule and also on the contact geometry, revealing the role of contact geometry in both the contact resistance and energy level alignment of a molecular junction. Detailed statistical analysis further reveals that, despite the dependence of the energy level alignment on contact geometry, the variation in single-molecule conductance is primarily due to contact resistance rather than variations in the energy level alignment.

Profiles of noise exposure levels in South African mining

CSIR Research Space (South Africa)

Edwards, A

2011-05-01

Full Text Available were exposed to noise levels of above the 85 dBA legislated occupational exposure level. The conclusion was made that information obtained through the study could be developed into a national personal noise exposure database, including audiometric...

Voltage scheduling for low power/energy

Science.gov (United States)

Manzak, Ali

2001-07-01

Power considerations have become an increasingly dominant factor in the design of both portable and desk-top systems. An effective way to reduce power consumption is to lower the supply voltage since voltage is quadratically related to power. This dissertation considers the problem of lowering the supply voltage at (i) the system level and at (ii) the behavioral level. At the system level, the voltage of the variable voltage processor is dynamically changed with the work load. Processors with limited sized buffers as well as those with very large buffers are considered. Given the task arrival times, deadline times, execution times, periods and switching activities, task scheduling algorithms that minimize energy or peak power are developed for the processors equipped with very large buffers. A relation between the operating voltages of the tasks for minimum energy/power is determined using the Lagrange multiplier method, and an iterative algorithm that utilizes this relation is developed. Experimental results show that the voltage assignment obtained by the proposed algorithm is very close (0.1% error) to that of the optimal energy assignment and the optimal peak power (1% error) assignment. Next, on-line and off-fine minimum energy task scheduling algorithms are developed for processors with limited sized buffers. These algorithms have polynomial time complexity and present optimal (off-line) and close-to-optimal (on-line) solutions. A procedure to calculate the minimum buffer size given information about the size of the task (maximum, minimum), execution time (best case, worst case) and deadlines is also presented. At the behavioral level, resources operating at multiple voltages are used to minimize power while maintaining the throughput. Such a scheme has the advantage of allowing modules on the critical paths to be assigned to the highest voltage levels (thus meeting the required timing constraints) while allowing modules on non-critical paths to be assigned

CT angiography for planning transcatheter aortic valve replacement using automated tube voltage selection: Image quality and radiation exposure

Energy Technology Data Exchange (ETDEWEB)

Mangold, Stefanie [Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC (United States); Department of Diagnostic and Interventional Radiology, Eberhard-Karls University Tuebingen, Tuebingen (Germany); De Cecco, Carlo N. [Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC (United States); Schoepf, U. Joseph, E-mail: schoepf@musc.edu [Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC (United States); Division of Cardiology, Department of Medicine, Medical University of South Carolina, Charleston, SC (United States); Kuhlman, Taylor S.; Varga-Szemes, Akos [Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC (United States); Caruso, Damiano [Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC (United States); Department of Radiological Sciences, Oncology and Pathology, University of Rome “Sapienza”, Rome (Italy); Duguay, Taylor M. [Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC (United States); Tesche, Christian [Department of Cardiology, Heart Centre Munich-Bogenhausen, Munich (Germany); Vogl, Thomas J. [Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC (United States); Department of Diagnostic and Interventional Radiology, University Hospital Frankfurt, Frankfurt (Germany); Nikolaou, Konstantin [Department of Diagnostic and Interventional Radiology, Eberhard-Karls University Tuebingen, Tuebingen (Germany); and others

2017-01-15

Highlights: • TAVR-planning CT was performed with automated tube voltage selection. • Automated tube voltage selection enables individual tube voltage adaptation. • Image quality was diagnostic while radiation exposure was significantly decreased. - Abstract: Purpose: To assess image quality and accuracy of CT angiography (CTA) for transcatheter aortic valve replacement (TAVR) planning performed with 3rd generation dual-source CT (DSCT). Material and methods: We evaluated 125 patients who underwent TAVR-planning CTA on 3rd generation DSCT. A two-part protocol was performed including retrospectively ECG-gated coronary CTA (CCTA) and prospectively ECG-triggered aortoiliac CTA using 60 mL of contrast medium. Automated tube voltage selection and advanced iterative reconstruction were applied. Effective dose (ED), signal-to-noise (SNR) and contrast-to-noise ratios (CNR) were calculated. Five-point scales were used for subjective image quality analysis. In patients who underwent TAVR, sizing parameters were obtained. Results: Image quality was rated good to excellent in 97.6% of CCTA and 100% of aortoiliac CTAs. CTA studies at >100 kV showed decreased objective image quality compared to 70–100 kV (SNR, all p ≤ 0.0459; CNR, all p ≤ 0.0462). Mean ED increased continuously from 70 to >100 kV (CCTA: 4.5 ± 1.7 mSv–13.6 ± 2.9 mSv, all p ≤ 0.0233; aortoiliac CTA: 2.4 ± 0.9 mSv–6.8 ± 2.7 mSv, all p ≤ 0.0414). In 39 patients TAVR was performed and annulus diameter was within the recommended range in all patients. No severe cardiac or vascular complications were noted. Conclusion: 3rd generation DSCT provides diagnostic image quality in TAVR-planning CTA and facilitates reliable assessment of TAVR device and delivery option while reducing radiation dose.

CT angiography for planning transcatheter aortic valve replacement using automated tube voltage selection: Image quality and radiation exposure

International Nuclear Information System (INIS)

Mangold, Stefanie; De Cecco, Carlo N.; Schoepf, U. Joseph; Kuhlman, Taylor S.; Varga-Szemes, Akos; Caruso, Damiano; Duguay, Taylor M.; Tesche, Christian; Vogl, Thomas J.; Nikolaou, Konstantin

2017-01-01

Highlights: • TAVR-planning CT was performed with automated tube voltage selection. • Automated tube voltage selection enables individual tube voltage adaptation. • Image quality was diagnostic while radiation exposure was significantly decreased. - Abstract: Purpose: To assess image quality and accuracy of CT angiography (CTA) for transcatheter aortic valve replacement (TAVR) planning performed with 3rd generation dual-source CT (DSCT). Material and methods: We evaluated 125 patients who underwent TAVR-planning CTA on 3rd generation DSCT. A two-part protocol was performed including retrospectively ECG-gated coronary CTA (CCTA) and prospectively ECG-triggered aortoiliac CTA using 60 mL of contrast medium. Automated tube voltage selection and advanced iterative reconstruction were applied. Effective dose (ED), signal-to-noise (SNR) and contrast-to-noise ratios (CNR) were calculated. Five-point scales were used for subjective image quality analysis. In patients who underwent TAVR, sizing parameters were obtained. Results: Image quality was rated good to excellent in 97.6% of CCTA and 100% of aortoiliac CTAs. CTA studies at >100 kV showed decreased objective image quality compared to 70–100 kV (SNR, all p ≤ 0.0459; CNR, all p ≤ 0.0462). Mean ED increased continuously from 70 to >100 kV (CCTA: 4.5 ± 1.7 mSv–13.6 ± 2.9 mSv, all p ≤ 0.0233; aortoiliac CTA: 2.4 ± 0.9 mSv–6.8 ± 2.7 mSv, all p ≤ 0.0414). In 39 patients TAVR was performed and annulus diameter was within the recommended range in all patients. No severe cardiac or vascular complications were noted. Conclusion: 3rd generation DSCT provides diagnostic image quality in TAVR-planning CTA and facilitates reliable assessment of TAVR device and delivery option while reducing radiation dose.

Energy-level alignment and open-circuit voltage at graphene/polymer interfaces: theory and experiment

Science.gov (United States)

Noori, Keian; Konios, Dimitrios; Stylianakis, Minas M.; Kymakis, Emmanuel; Giustino, Feliciano

2016-03-01

Functionalized graphene promises to become a key component of novel solar cell architectures, owing to its versatile ability to act either as transparent conductor, electron acceptor, or buffer layer. In spite of this promise, the solar energy conversion efficiency of graphene-based devices falls short of the performance of competing solution-processable photovoltaic technologies. Here we address the question of the maximum achievable open-circuit voltage of all-organic graphene: polymer solar cells using a combined theoretical/experimental approach, going from the atomic scale level to the device level. Our calculations on very large atomistic models of the graphene/polymer interface indicate that the ideal open-circuit voltage approaches one volt, and that epoxide functional groups can have a dramatic effect on the photovoltage. Our predictions are confirmed by direct measurements on complete devices where we control the concentration of functional groups via chemical reduction. Our findings indicate that the selective removal of epoxide groups and the use of ultradisperse polymers are key to achieving graphene solar cells with improved energy conversion efficiency.

Ultra Low-Voltage Energy Harvesting

Science.gov (United States)

2013-09-01

if in a solar battery charger the level of illumination were to drop due to cloud cover, the diode would prevent discharging of the battery when...the source voltage becomes lower than battery voltage. The drawback of a simple circuit like this is that once the source voltage is lower than the...longer charged when the battery voltage is above the OV setting. Figure 13. Block diagram of BQ25504 circuit . (From [10]) 18 THIS PAGE

Radiographic apparatus and method for monitoring film exposure time

International Nuclear Information System (INIS)

Vatne, R.S.; Woodmansee, W.E.

1981-01-01

In connection with radiographic inspection of structural and industrial materials, method and apparatus are disclosed for automatically determining and displaying the time required to expose a radiographic film positioned to receive radiation passed by a test specimen, so that the finished film is exposed to an optimum blackening (density) for maximum film contrast. A plot is made of the variations in a total exposure parameter (representing the product of detected radiation rate and time needed to cause optimum film blackening) as a function of the voltage level applied to an X-ray tube. An electronic function generator storing the shape of this plot is incorporated into an exposure monitoring apparatus, such that for a selected tube voltage setting, the function generator produces an electrical analog signal of the corresponding exposure parameter. During the exposure, another signal is produced representing the rate of radiation as monitored by a diode detector positioned so as to receive the same radiation that is incident on the film. The signal representing the detected radiation rate is divided, by an electrical divider circuit into the signal representing total exposure, and the resulting quotient is an electrical signal representing the required exposure time. (author)

Development of Multi-Functional Voltage Restore System

Science.gov (United States)

Suzuki, Satoshi; Ueda, Yoshinobu; Koganezawa, Takehisa; Ogihara, Yoshinori; Mori, Kenjiro; Fukazu, Naoaki

Recently, with the dawn of the electric deregulation, the installation of distributed generation with power electronics device has grown. This current causes a greater concern of power quality, primarily voltage disturbance for power companies, and their interest in power quality is peaking. Utilities are also interested in keeping their customers satisfied, as well as keeping them on-line and creating more revenue for the utility. As a countermeasure against the above surroundings, a variety type of devices based on power electronics has been developed to protect customers' load from power line voltage disturbance. One of them is the series type voltage restore. The series device is an active device, designed to provide a pure sinusoidal load voltage at all times, correcting voltage disturbance. Series type device compensates for voltage anomalies by inserting the ‘missing’ voltage onto the line through insertion transformer and inverter. This paper shows the setting guideline of target level to compensate voltage disturbance, that is, voltage dip, voltage harmonics, voltage imbalance and voltage flicker, and the design approach of the prototype of series voltage restores to accomplish the required compensation level. The prototype system gives satisfactory compensation performance through evaluation tests, which confirm the validity and effectiveness of the system.

Voltage stability in low voltage microgrids in aspects of active and reactive power demand

Directory of Open Access Journals (Sweden)

Parol Mirosław

2016-03-01

Full Text Available Low voltage microgrids are autonomous subsystems, in which generation, storage and power and electrical energy consumption appear. In the paper the main attention has been paid to the voltage stability issue in low voltage microgrid for different variants of its operation. In the introduction a notion of microgrid has been presented, and also the issue of influence of active and reactive power balance on node voltage level has been described. Then description of voltage stability issue has been presented. The conditions of voltage stability and indicators used to determine voltage stability margin in the microgrid have been described. Description of the low voltage test microgrid, as well as research methodology along with definition of considered variants of its operation have been presented further. The results of exemplary calculations carried out for the daily changes in node load of the active and reactive power, i.e. the voltage and the voltage stability margin indexes in nodes have been presented. Furthermore, the changes of voltage stability margin indexes depending on the variant of the microgrid operation have been presented. Summary and formulation of conclusions related to the issue of voltage stability in microgrids have been included at the end of the paper.

New strategy for eliminating zero-sequence circulating current between parallel operating three-level NPC voltage source inverters

DEFF Research Database (Denmark)

Li, Kai; Dong, Zhenhua; Wang, Xiaodong

2018-01-01

A novel strategy based on a zero common mode voltage pulse-width modulation (ZCMV-PWM) technique and zero-sequence circulating current (ZSCC) feedback control is proposed in this study to eliminate ZSCCs between three-level neutral point clamped (NPC) voltage source inverters, with common AC and DC......, the ZCMV-PWM method is presented to reduce CMVs, and a simple electric circuit is adopted to control ZSCCs and neutral point potential. Finally, simulation and experiment are conducted to illustrate effectiveness of the proposed strategy. Results show that ZSCCs between paralleled inverters can...

Voltage sags: Their impact on the utility and industrial customers

International Nuclear Information System (INIS)

Davis, T.; Beam, G.E.; Melhorn, C.J.

1995-01-01

This paper describes the impact of voltage sags on the utility and industrial customers. Several utility measures are presented to minimize the customer's exposure to voltage sags. However, these measures cannot completely eliminate the impact of voltage sags on sensitive equipment. A case study is presented in this paper that includes measurement results that were used to characterize the voltage sags experienced on the utility system and in the industrial facility, simulation results that were used to develop area of vulnerability curves for the industrial facility, mitigation equipment that was employed to improve the sensitive equipment's ride through capability, and the lessons learned from the systems approach analysis

Image evaluation and exposure dose with the application of tube voltage and adaptive statistical iterative reconstruction of low dose computed tomography

Energy Technology Data Exchange (ETDEWEB)

Moon, Tae Joon [Dept. of Radiology, Konkuk University Medical Center, Seoul (Korea, Republic of); Kim, Ki Jeong [Dept. of Radiology, Wonkwang University Hospital, Iksan (Korea, Republic of); Lee, Hye Nam [Dept. of Radiology, Gimsangyeong Internal Medicine Clinic, Nonsan (Korea, Republic of)

2017-06-15

The study has attempted to evaluate and compare the image evaluation and exposure dose by respectively applying filter back projection (FBP), the existing test method, and adaptive statistical iterative reconstruction (ASIR) with different values of tube voltage during the low dose computed tomography (LDCT). With the image reconstruction method as basis, chest phantom was utilized with the FBP and ASIR set at 10%, 20% respectively, and the change of tube voltage (100 kVp, 120 kVp). For image evaluation, back ground noise, signal-noise ratio (SNR) and contrast-noise ratio (CNR) were measured, and, for dose assessment, CTDIvol and DLP were measured respectively. In terms of image evaluation, there was significant difference in ascending aorta (AA) SNR and inpraspinatus muscle (IM) SNR with the different amount of tube voltage (p < 0.05). In terms of CTDIvol, the measured values with the same tube voltage of 120 kVp were 2.6 mGy with no-ASIR and 2.17 mGy with 20%-ASIR respectively, decreased by 0.43 mGy, and the values with 100 kVp were 1.61 mGy with no-ASIR and 1.34 mGy with 20%-ASIR, decreased by 0.27 mGy. In terms of DLP, the measured values with 120 kVp were 103.21 mGy‧cm with no-ASIR and 85.94 mGy‧cm with 20%-ASIR, decreased by 17.27mGy‧cm (about 16.7%), and the values with 100 kVp were 63.84 mGy‧cm with no-ASIR and 53.25 mGy‧cm with 20%-ASIR, a decrease by 10.62 mGy‧cm ( about 16.7%). At lower tube voltage, the rate of dose significantly decreased, but the negative effects on image evaluation was shown due to the increase of noise.

Image evaluation and exposure dose with the application of tube voltage and adaptive statistical iterative reconstruction of low dose computed tomography

International Nuclear Information System (INIS)

Moon, Tae Joon; Kim, Ki Jeong; Lee, Hye Nam

2017-01-01

The study has attempted to evaluate and compare the image evaluation and exposure dose by respectively applying filter back projection (FBP), the existing test method, and adaptive statistical iterative reconstruction (ASIR) with different values of tube voltage during the low dose computed tomography (LDCT). With the image reconstruction method as basis, chest phantom was utilized with the FBP and ASIR set at 10%, 20% respectively, and the change of tube voltage (100 kVp, 120 kVp). For image evaluation, back ground noise, signal-noise ratio (SNR) and contrast-noise ratio (CNR) were measured, and, for dose assessment, CTDIvol and DLP were measured respectively. In terms of image evaluation, there was significant difference in ascending aorta (AA) SNR and inpraspinatus muscle (IM) SNR with the different amount of tube voltage (p < 0.05). In terms of CTDIvol, the measured values with the same tube voltage of 120 kVp were 2.6 mGy with no-ASIR and 2.17 mGy with 20%-ASIR respectively, decreased by 0.43 mGy, and the values with 100 kVp were 1.61 mGy with no-ASIR and 1.34 mGy with 20%-ASIR, decreased by 0.27 mGy. In terms of DLP, the measured values with 120 kVp were 103.21 mGy‧cm with no-ASIR and 85.94 mGy‧cm with 20%-ASIR, decreased by 17.27mGy‧cm (about 16.7%), and the values with 100 kVp were 63.84 mGy‧cm with no-ASIR and 53.25 mGy‧cm with 20%-ASIR, a decrease by 10.62 mGy‧cm ( about 16.7%). At lower tube voltage, the rate of dose significantly decreased, but the negative effects on image evaluation was shown due to the increase of noise

Evaluation of the Voltage Support Strategies for the Low Voltage Grid Connected PV

DEFF Research Database (Denmark)

Demirok, Erhan; Sera, Dezso; Teodorescu, Remus

2010-01-01

Admissible range of grid voltage is one of the strictest constraints for the penetration of distributed photovoltaic (PV) generators especially connection to low voltage (LV) public networks. Voltage limits are usually fulfilled either by network reinforcements or limiting of power injections from...... PVs. In order to increase PV penetration level further, new voltage support control functions for individual inverters are required. This paper investigates distributed reactive power regulation and active power curtailment strategies regarding the development of PV connection capacity by evaluation...... of reactive power efforts and requirement of minimum active power curtailment. Furthermore, a small scale experimental setup is built to reflect real grid interaction in the laboratory by achieving critical types of grid (weak and sufficiently stiff)....

A transient simulation approach to obtaining capacitance-voltage characteristics of GaN MOS capacitors with deep-level traps

Science.gov (United States)

Fukuda, Koichi; Asai, Hidehiro; Hattori, Junichi; Shimizu, Mitsuaki; Hashizume, Tamotsu

2018-04-01

In this study, GaN MOS capacitance-voltage device simulations considering various interface and bulk traps are performed in the transient mode. The simulations explain various features of capacitance-voltage curves, such as plateau, hysteresis, and frequency dispersions, which are commonly observed in measurements of GaN MOS capacitors and arise from complicated combinations of interface and bulk deep-level traps. The objective of the present study is to provide a good theoretical tool to understand the physics of various nonideal measured curves.

Alterations in welding process voltage affect the generation of ultrafine particles, fume composition, and pulmonary toxicity.

Science.gov (United States)

Antonini, James M; Keane, Michael; Chen, Bean T; Stone, Samuel; Roberts, Jenny R; Schwegler-Berry, Diane; Andrews, Ronnee N; Frazer, David G; Sriram, Krishnan

2011-12-01

The goal was to determine if increasing welding voltage changes the physico-chemical properties of the fume and influences lung responses. Rats inhaled 40 mg/m³ (3 h/day × 3 days) of stainless steel (SS) welding fume generated at a standard voltage setting of 25 V (regular SS) or at a higher voltage (high voltage SS) of 30 V. Particle morphology, size and composition were characterized. Bronchoalveolar lavage was performed at different times after exposures to assess lung injury. Fumes collected from either of the welding conditions appeared as chain-like agglomerates of nanometer-sized primary particles. High voltage SS welding produced a greater number of ultrafine-sized particles. Fume generated by high voltage SS welding was higher in manganese. Pulmonary toxicity was more substantial and persisted longer after exposure to the regular SS fume. In summary, a modest raise in welding voltage affected fume size and elemental composition and altered the temporal lung toxicity profile.

Enhanced UV exposure on a ski-field compared with exposures at sea level.

Science.gov (United States)

Allen, Martin; McKenzie, Richard

2005-05-01

Personal erythemal UV monitoring badges, which were developed to monitor the UV exposure of school children, were used to measure UV exposures received by one of the authors (MA) at the Mt Hutt ski-field, in New Zealand. These were then compared with measurements taken at the same times from a nearby sea level site in Christchurch city. The badges were designed to give instantaneous readings of erythemally-weighted (i.e., "sun burning") UV radiation and were cross-calibrated against meteorological grade UV instruments maintained by the National Institute of Water & Atmospheric Research (NIWA). All skiing and calibration days were clear and almost exclusively cloud free. It was found that the UV maxima for horizontal surfaces at the ski-field (altitude approximately 2 km) were 20-30% greater than at the low altitude site. Larger differences between the sites were observed when the sensor was oriented perpendicular to the sun. The personal doses of UV received by a sensor on the skier's lapel during two days of skiing activity were less than those received by a stationary detector on a horizontal surface near sea level. The exposures depended strongly on the time of year, and in mid-October the maximum UV intensity on the ski-field was 60% greater than in mid-September. The UV exposure levels experienced during skiing were smaller than the summer maxima at low altitudes.

The monitoring results of electromagnetic radiation of 110-kV high-voltage lines in one urban location in Chongqing P.R. China.

Science.gov (United States)

Qin, Qi-Zhong; Chen, Yu; Fu, Ting-Ting; Ding, Li; Han, Ling-Li; Li, Jian-Chao

2012-03-01

To understand electromagnetic radiation field strength and its influencing factors of certain 110-kV high-voltage lines in one urban area of Chongqing by measuring 110-kV high-voltage line's electromagnetic radiation level. According to the methodology as determined by the National Hygienic Standards, we selected certain adjacent residential buildings, high-voltage lines along a specific street and selected different distances around its vertical projection point as monitoring points. The levels of electromagnetic radiations were measured respectively. In this investigation within the frequency of 5-1,000 Hz both the electric field strength and magnetic field strength of each monitoring sites were lower than the public exposure standards as determined by the International Commission on Non-Ionizing Radiation Protection. However, the electrical field strength on the roof adjacent to the high-voltage lines was significantly higher than that as measured on the other floors in the same buildings (p electromagnetic radiation measurements of different monitoring points, under the same high-voltage lines, showed the location which is nearer the high-voltage line maintain a consistently higher level of radiation than the more distant locations (p Electromagnetic radiation generated by high-voltage lines decreases proportionally to the distance from the lines. The buildings can to some extent shield (or absorb) the electric fields generated by high-voltage lines nearby. The electromagnetic radiation intensity near high-voltage lines may be mitigated or intensified by the manner in which the high-voltage lines are set up, and it merits attention for the potential impact on human health.

Human exposure to low level ionising radiation

International Nuclear Information System (INIS)

Paix, David

1988-01-01

This paper describes the low-level radiation sources and their effects on human populations, from a global perspective. 'Low-level' means exposures in the range of the natural background to which everybody is exposed. The quoted values are whole-world averages, but individual variations are mentioned in a few cases. (author). 22 refs

SEMICONDUCTOR INTEGRATED CIRCUITS: A quasi-3-dimensional simulation method for a high-voltage level-shifting circuit structure

Science.gov (United States)

Jizhi, Liu; Xingbi, Chen

2009-12-01

A new quasi-three-dimensional (quasi-3D) numeric simulation method for a high-voltage level-shifting circuit structure is proposed. The performances of the 3D structure are analyzed by combining some 2D device structures; the 2D devices are in two planes perpendicular to each other and to the surface of the semiconductor. In comparison with Davinci, the full 3D device simulation tool, the quasi-3D simulation method can give results for the potential and current distribution of the 3D high-voltage level-shifting circuit structure with appropriate accuracy and the total CPU time for simulation is significantly reduced. The quasi-3D simulation technique can be used in many cases with advantages such as saving computing time, making no demands on the high-end computer terminals, and being easy to operate.

Medium voltage three-level converters for the grid connection of a multi-MW wind turbine

DEFF Research Database (Denmark)

Senturk, Osman Selcuk; Helle, Lars; Munk-Nielsen, Stig

2009-01-01

Three-level (3L) neutral point clamped (NPC), flying capacitor (FC), and H-bridge (HB) voltage source converters (VSCs) as a grid-side full-scale medium voltage (MV) converter are modeled, controlled, and simulated for the grid connection of a hypothetical 6MW wind turbine. Via the converter...... topological features and the simulation results demonstrating the converter performance, these three 3L-VSCs are discussed and compared in terms of power density and reliability, which can be considered as two of the most important criteria for the converters placed in wind turbine nacelles. Given the grid...... connection circuit (without capacitive switching ripple filters), the 3L-HB-VSC is expected to be superior with respect to power density and reliability over the 3L-NPC- and -FC-VSCs....

Medium Voltage Three-level Converters for the Grid Connection of aMulti-MW Wind Turbine

DEFF Research Database (Denmark)

Senturk, Osman Selcuk; Helle, Lars; Munk-Nielsen, Stig

2009-01-01

Three-level (3L) neutral point clamped (NPC), flying capacitor (FC), and H-bridge (HB) voltage source converters (VSCs) as a grid-side full-scale medium voltage (MV) converter are modeled, controlled, and simulated for the grid connection of a hypothetical 6MW wind turbine. Via the converter...... topological features and the simulation results demonstrating the converter performance, these three 3L-VSCs are discussed and compared in terms of power density and reliability, which can be considered as two of the most important criteria for the converters placed in wind turbine nacelles. Given the grid...... connection circuit (without capacitive switching ripple filters), the 3L-HB-VSC is expected to be superior with respect to power density and reliability over the 3L-NPC- and -FC-VSCs....

Voltage Support from Electric Vehicles in Distribution Grid

DEFF Research Database (Denmark)

Huang, Shaojun; Pillai, Jayakrishnan Radhakrishna; Bak-Jensen, Birgitte

2013-01-01

The paper evaluates the voltage support functions from electric vehicles (EVs) on a typical Danish distribution grid with high EV penetration. In addition to the popular voltage control modes, such as voltage droop charging (low voltage level leads to low charging power) and reactive power support...

A comparison of magnetic fields inside and outside high-voltage urban 110-kV power substations with the exposure recommendations of the Ukrainian regulatory authorities

International Nuclear Information System (INIS)

Okun, Oleksandr; Shevchenko, Sergey; Korpinen, Leena

2013-01-01

The aim of this study was to carry out theoretical investigations of power frequency magnetic fields (MFs), produced inside and outside the domain of urban 110-kV power substations and to establish a correspondence between the levels of the fields and the specified population limits as defined by Ukrainian regulations. The fields produced by high-voltage substations were studied based on the application of the numerical finite element methodology. The investigations have shown that magnetic flux density values calculated inside and outside the considered 110-kV power substations do not reach the exposure limits specified by the Ukrainian regulations (1750 μT) and by international guidelines (ICNIRP 2010). Inside the domain of the substation, the maximum value of MFs was found under the 10-kV bus-bars and it equalled 420 μT. (authors)

Microprocessor-controlled, programmable ramp voltage generator

International Nuclear Information System (INIS)

Hopwood, J.

1978-11-01

A special-purpose voltage generator has been developed for driving the quadrupole mass filter of a residual gas analyzer. The generator is microprocessor-controlled with desired ramping parameters programmed by setting front-panel digital thumb switches. The start voltage, stop voltage, and time of each excursion are selectable. A maximum of five start-stop levels may be pre-selected for each program. The ramp voltage is 0 to 10 volts with sweep times from 0.1 to 999.99 seconds

Emergency exposure levels for natural uranium

International Nuclear Information System (INIS)

Spoor, N.L.; Harrison, N.T.

1980-12-01

An attempt is made to identify the inhalation hazards associated with the over-exposure of workers and of the general public, following an accidental release of uranium hexafluoride. Maximum emergency concentrations are recommended for periods of 10, 30, and 60 minutes. The quantitative aspect of the assessment is considered in the context of the development of exposure standards for chemical substances and this facilitates the derivation of levels which are compatible with occupational and public health experience and attainable by management, and to which most workers and members of the general public may be exposed without adverse effect. The radiological implications are also considered. (author)

Effect of pulsed corona discharge voltage and feed gas flow rate on dissolved ozone concentration

International Nuclear Information System (INIS)

Prasetyaningrum, A.; Ratnawati,; Jos, B.

2015-01-01

Ozonization is one of the methods extensively used for water purification and degradation of organic materials. Ozone (O 3 ) is recognized as a powerful oxidizing agent. Due to its strong oxidability and better environmental friendless, ozone increasing being used in domestic and industrial applications. Current technology in ozone production utilizes several techniques (corona discharge, ultra violet radiation and electrolysis). This experiment aimed to evaluating effect of voltage and gas flow rate on ozone production with corona discharge. The system consists of two net-type stainless steel electrode placed in a dielectric barrier. Three pulsed voltage (20, 30, 40 KV) and flow rate (5, 10, 15 L/min) were prepare for operation variable at high frequency (3.7 kHz) with AC pulsed power supply. The dissolved ozone concentration depends on the applied high-voltage level, gas flow rate and the discharge exposure duration. The ozone concentration increases with decreasing gas flow rate. Dissolved ozone concentrations greater than 200 ppm can be obtained with a minimum voltage 40 kV

Effect of pulsed corona discharge voltage and feed gas flow rate on dissolved ozone concentration

Science.gov (United States)

Prasetyaningrum, A.; Ratnawati, Jos, B.

2015-12-01

Ozonization is one of the methods extensively used for water purification and degradation of organic materials. Ozone (O3) is recognized as a powerful oxidizing agent. Due to its strong oxidability and better environmental friendless, ozone increasing being used in domestic and industrial applications. Current technology in ozone production utilizes several techniques (corona discharge, ultra violet radiation and electrolysis). This experiment aimed to evaluating effect of voltage and gas flow rate on ozone production with corona discharge. The system consists of two net-type stainless steel electrode placed in a dielectric barrier. Three pulsed voltage (20, 30, 40 KV) and flow rate (5, 10, 15 L/min) were prepare for operation variable at high frequency (3.7 kHz) with AC pulsed power supply. The dissolved ozone concentration depends on the applied high-voltage level, gas flow rate and the discharge exposure duration. The ozone concentration increases with decreasing gas flow rate. Dissolved ozone concentrations greater than 200 ppm can be obtained with a minimum voltage 40 kV.

Effect of pulsed corona discharge voltage and feed gas flow rate on dissolved ozone concentration

Energy Technology Data Exchange (ETDEWEB)

Prasetyaningrum, A., E-mail: ajiprasetyaningrum@gmail.com; Ratnawati,; Jos, B. [Department of Chemical Engineering, Faculty of Engineering, Diponegoro University Jl. Prof. H. Soedarto Tembalang, Semarang, Central Java, Indonesia, 50276 (Indonesia)

2015-12-29

Ozonization is one of the methods extensively used for water purification and degradation of organic materials. Ozone (O{sub 3}) is recognized as a powerful oxidizing agent. Due to its strong oxidability and better environmental friendless, ozone increasing being used in domestic and industrial applications. Current technology in ozone production utilizes several techniques (corona discharge, ultra violet radiation and electrolysis). This experiment aimed to evaluating effect of voltage and gas flow rate on ozone production with corona discharge. The system consists of two net-type stainless steel electrode placed in a dielectric barrier. Three pulsed voltage (20, 30, 40 KV) and flow rate (5, 10, 15 L/min) were prepare for operation variable at high frequency (3.7 kHz) with AC pulsed power supply. The dissolved ozone concentration depends on the applied high-voltage level, gas flow rate and the discharge exposure duration. The ozone concentration increases with decreasing gas flow rate. Dissolved ozone concentrations greater than 200 ppm can be obtained with a minimum voltage 40 kV.

General and Simple Decision Method for DG Penetration Level in View of Voltage Regulation at Distribution Substation Transformers

Directory of Open Access Journals (Sweden)

Joon-Ho Choi

2013-09-01

Full Text Available A distribution system was designed and operated by considering unidirectional power flow from a utility source to end-use loads. The large penetrations of distributed generation (DG into the existing distribution system causes a variety of technical problems, such as frequent tap changing problems of the on-load tap changer (OLTC transformer, local voltage rise, protection coordination, exceeding short-circuit capacity, and harmonic distortion. In view of voltage regulation, the intermittent fluctuation of the DG output power results in frequent tap changing operations of the OLTC transformer. Thus, many utilities limit the penetration level of DG and are eager to find the reasonable penetration limits of DG in the distribution system. To overcome this technical problem, utilities have developed a new voltage regulation method in the distribution system with a large DG penetration level. In this paper, the impact of DG on the OLTC operations controlled by the line drop compensation (LDC method is analyzed. In addition, a generalized determination methodology for the DG penetration limits in a distribution substation transformer is proposed. The proposed DG penetration limits could be adopted for a simplified interconnection process in DG interconnection guidelines.

Voltage-dependent motion of the catalytic region of voltage-sensing phosphatase monitored by a fluorescent amino acid.

Science.gov (United States)

Sakata, Souhei; Jinno, Yuka; Kawanabe, Akira; Okamura, Yasushi

2016-07-05

The cytoplasmic region of voltage-sensing phosphatase (VSP) derives the voltage dependence of its catalytic activity from coupling to a voltage sensor homologous to that of voltage-gated ion channels. To assess the conformational changes in the cytoplasmic region upon activation of the voltage sensor, we genetically incorporated a fluorescent unnatural amino acid, 3-(6-acetylnaphthalen-2-ylamino)-2-aminopropanoic acid (Anap), into the catalytic region of Ciona intestinalis VSP (Ci-VSP). Measurements of Anap fluorescence under voltage clamp in Xenopus oocytes revealed that the catalytic region assumes distinct conformations dependent on the degree of voltage-sensor activation. FRET analysis showed that the catalytic region remains situated beneath the plasma membrane, irrespective of the voltage level. Moreover, Anap fluorescence from a membrane-facing loop in the C2 domain showed a pattern reflecting substrate turnover. These results indicate that the voltage sensor regulates Ci-VSP catalytic activity by causing conformational changes in the entire catalytic region, without changing their distance from the plasma membrane.

Voltage-dependent motion of the catalytic region of voltage-sensing phosphatase monitored by a fluorescent amino acid

Science.gov (United States)

Sakata, Souhei; Jinno, Yuka; Kawanabe, Akira; Okamura, Yasushi

2016-01-01

The cytoplasmic region of voltage-sensing phosphatase (VSP) derives the voltage dependence of its catalytic activity from coupling to a voltage sensor homologous to that of voltage-gated ion channels. To assess the conformational changes in the cytoplasmic region upon activation of the voltage sensor, we genetically incorporated a fluorescent unnatural amino acid, 3-(6-acetylnaphthalen-2-ylamino)-2-aminopropanoic acid (Anap), into the catalytic region of Ciona intestinalis VSP (Ci-VSP). Measurements of Anap fluorescence under voltage clamp in Xenopus oocytes revealed that the catalytic region assumes distinct conformations dependent on the degree of voltage-sensor activation. FRET analysis showed that the catalytic region remains situated beneath the plasma membrane, irrespective of the voltage level. Moreover, Anap fluorescence from a membrane-facing loop in the C2 domain showed a pattern reflecting substrate turnover. These results indicate that the voltage sensor regulates Ci-VSP catalytic activity by causing conformational changes in the entire catalytic region, without changing their distance from the plasma membrane. PMID:27330112

Utilization of low- and high-voltage electric equipment at heights exceeding 1000 m above sea level

Energy Technology Data Exchange (ETDEWEB)

Karapetyan, M.M.

1980-01-01

The present-day state of high- and low-voltage equipment utilization at heights exceeding 1000 m above sea level is considered with allowance for the technical requirements applicable to the equipment, as provided for in the GOST (All-Union State Standards), and for the results of scientific research studies. 12 refs.

Mitigation of Voltage Swells by Static Series Compensator

DEFF Research Database (Denmark)

Awad, Hilmy; Blaabjerg, Frede

2004-01-01

Swells and overvoltages can cause overheating, tripping or even destruction of industrial equipment such as motor drives and control relays. This paper investigates the possibility of employing the Static Series Compensator (SSC) to mitigate voltage swells/overvoltages. In the case of voltage...... is lower than a predetermined voltage level, the active power is employed to charge the ESC to this voltage level; 2) otherwise, the overvoltage protection of the SSC must operate. This paper also applies an overvoltage protection scheme based on a combination of a dc resistor with a chopper and the valves...

Voltage Controlled Dynamic Demand Response

DEFF Research Database (Denmark)

Bhattarai, Bishnu Prasad; Bak-Jensen, Birgitte; Mahat, Pukar

2013-01-01

Future power system is expected to be characterized by increased penetration of intermittent sources. Random and rapid fluctuations in demands together with intermittency in generation impose new challenges for power balancing in the existing system. Conventional techniques of balancing by large...... central or dispersed generations might not be sufficient for future scenario. One of the effective methods to cope with this scenario is to enable demand response. This paper proposes a dynamic voltage regulation based demand response technique to be applied in low voltage (LV) distribution feeders....... An adaptive dynamic model has been developed to determine composite voltage dependency of an aggregated load on feeder level. Following the demand dispatch or control signal, optimum voltage setting at the LV substation is determined based on the voltage dependency of the load. Furthermore, a new technique...

Flying capacitor resonant pole inverter applying five voltage levels

NARCIS (Netherlands)

Settels, S.J.

2017-01-01

Industrial applications, e.g. semiconductor manufacturing equipment, require power amplifiers providing high power with high precision and bandwidth. Due to limitations in system infrastructure, increasing voltage is favorable to increasing current to generate more output power. This research

The Evaluation of Conventional X-ray Exposure Parameters Including Tube Voltage and Exposure Time in Private and Governmental Hospitals of Lorestan Province, Iran

Directory of Open Access Journals (Sweden)

Mehrdad Gholami

2015-07-01

Full Text Available Introduction In radiography, dose and image quality are dependent on radiographic parameters. The problem is caused from incorrect use of radiography equipment and from the radiation exposure to patients much more than required. Therefore, the aim of this study was to implement a quality-control program to detect changes in exposure parameters, which may affect diagnosis or patient radiation dose. Materials and Methods This cross-sectional study was performed on seven stationary X-ray units in sixhospitals of Lorestan province. The measurements were performed, using a factory-calibrated Barracuda dosimeter (model: SE-43137. Results According to the results, the highest output was obtained in A Hospital (M1 device, ranging from 107×10-3 to 147×10-3 mGy/mAs. The evaluation of tube voltage accuracy showed a deviation from the standard value, which ranged between 0.81% (M1 device and 17.94% (M2 device at A Hospital. The deviation ranges at other hospitals were as follows: 0.30-27.52% in B Hospital (the highest in this study, 8.11-20.34% in C Hospital, 1.68-2.58% in D Hospital, 0.90-2.42% in E Hospital and 0.10-1.63% in F Hospital. The evaluation of exposure time accuracy showed that E, C, D and A (M2 device hospitals complied with the requirements (allowing a deviation of ±5%, whereas A (M1 device, F and B hospitals exceeded the permitted limit. Conclusion The results of this study showed that old X-ray equipments with poor or no maintenance are probably the main sources of reducing radiographic image quality and increasing patient radiation dose.

Evaluation of noise pollution level based upon community exposure and response data

Science.gov (United States)

Edmiston, R. D.

1972-01-01

The results and procedures are reported from an evaluation of noise pollution level as a predictor of annoyance, based on aircraft noise exposure and community response data. The measures of noise exposure presented include composite noise rating, noise exposure forecast, noise and number index. A proposed measure as a universal noise exposure measure for noise pollution level (L sub NP) is discussed.

Radiation in complex exposure situations. Assessing health risks at low levels from concomitant exposures to radiation and chemicals

International Nuclear Information System (INIS)

Hornhardt, S.; Jung, T.; Burkart, W.

2000-01-01

Health effects from exposures to ionizing radiation are in general the result of complex multi-step reaction chains involving changes and responses on the level of molecules, cells, tissues and organisms. In environmental low dose exposure situations ionizing radiation only contributes a small fraction to the life-long attack on DNA by other exogenous and endogenous genotoxins. Nevertheless, efforts to assess and quantify deleterious effects at low exposure levels are directed mainly towards radiation as a single isolated agent, and rarely towards the concomitant presence of other natural and anthropogenic toxicants. Only these combined exposures may lead to observable health risk effects. In addition they might differ from those expected from simple addition of the individual risks due to interaction. The existing data base on combined effects is rudimentary, mainly descriptive and rarely covers exposure ranges large enough to make direct inferences to present day low dose exposure situations. Therefore, any risk assessment will have to consider the question whether combined effects, i.e. interaction between two or more agents will influence the health outcome from specific exposure situations in such a way that predictions derived from simple standard exposure situations would have to be revised. In view of the multitude of possible interactions between the large number of potentially harmful agents in the human environment, descriptive approaches will have to be supplemented by the use of mechanistic models for critical health endpoints such as cancer. Agents will have to be grouped depending on their physical or chemical mode of action at the molecular and cellular level, to generalize and predict the outcome of combined exposures at low exposure levels and the possibility of interactions. (author)

Heat-pump performance: voltage dip/sag, under-voltage and over-voltage

Directory of Open Access Journals (Sweden)

William J.B. Heffernan

2014-12-01

Full Text Available Reverse cycle air-source heat-pumps are an increasingly significant load in New Zealand and in many other countries. This has raised concern over the impact wide-spread use of heat-pumps may have on the grid. The characteristics of the loads connected to the power system are changing because of heat-pumps. Their performance during under-voltage events such as voltage dips has the potential to compound the event and possibly cause voltage collapse. In this study, results from testing six heat-pumps are presented to assess their performance at various voltages and hence their impact on voltage stability.

On the assessment of shooting sounds : Loudness-level weightings versus A- and C-weighted sound exposure levels (L)

NARCIS (Netherlands)

Vos, J.; Geurtsen, F.W.M.

2003-01-01

As an alternative to the A-weighted sound exposure level (ASEL) Schomer et al. [J. Acoust. Soc. Am. 110, 2390-2397 (2001)] used the equal-loudness level contours as a dynamic filter to determine the loudness-level-weighted sound exposure level (LLSEL). From their analyses they concluded that the

Theoretical and experimental studies of the current–voltage and capacitance–voltage of HEMT structures and field-effect transistors

Energy Technology Data Exchange (ETDEWEB)

Tarasova, E. A.; Obolenskaya, E. S., E-mail: obolensk@rf.unn.ru; Hananova, A. V.; Obolensky, S. V. [Lobachevsky State University of Nizhny Novgorod (NNSU) (Russian Federation); Zemliakov, V. E.; Egorkin, V. I. [National Research University of Electronic Technology (MIET) (Russian Federation); Nezhenzev, A. V. [Lobachevsky State University of Nizhny Novgorod (NNSU) (Russian Federation); Saharov, A. V.; Zazul’nokov, A. F.; Lundin, V. V.; Zavarin, E. E. [Russian Academy of Sciences, Ioffe Physical–Technical Institute (Russian Federation); Medvedev, G. V. [JSC RPE Salut (Russian Federation)

2016-12-15

The sensitivity of classical n{sup +}/n{sup –} GaAs and AlGaN/GaN structures with a 2D electron gas (HEMT) and field-effect transistors based on these structures to γ-neutron exposure is studied. The levels of their radiation hardness were determined. A method for experimental study of the structures on the basis of a differential analysis of their current–voltage characteristics is developed. This method makes it possible to determine the structure of the layers in which radiation-induced defects accumulate. A procedure taking into account changes in the plate area of the experimentally measured barrier-contact capacitance associated with the emergence of clusters of radiation-induced defects that form dielectric inclusions in the 2D-electron-gas layer is presented for the first time.

ELABORATION OF HIGH-VOLTAGE PULSE INSTALLATIONS AND PROVIDING THEIR OPERATION PROTECTIVE MEASURES

Directory of Open Access Journals (Sweden)

А. М. Hashimov

2016-01-01

Full Text Available The article presents design engineering methods for the high-voltage pulse installations of technological purpose for disinfection of drinking water, sewage, and edible liquids by high field micro- and nanosecond pulsing exposure. Designing potentialities are considered of the principal elements of the high-voltage part and the discharge circuit of the installations towards assuring the best efficient on-load utilization of the source energy and safe operation of the high-voltage equipment. The study shows that for disinfection of drinking water and sewage it is expedient to apply microsecond pulse actions causing the electrohydraulic effect in aqueous media with associated complex of physical processes (ultraviolet emission, generation of ozone and atomic oxygen, mechanical compression waves, etc. having detrimental effect on life activity of the microorganisms. In case of disinfecting edible liquids it is recommended to use the nanosecond pulses capable of straight permeating the biological cell nucleus, inactivating it. Meanwhile, the nutritive and biological values of the foodstuffs are saved and their organoleptic properties are improved. It is noted that in elaboration process of high-frequency pulse installations special consideration should be given to issues of the operating personnel safety discipline and securing conditions for the entire installation uninterrupted performance. With this objective in view the necessary requirements should be fulfilled on shielding the high- and low-voltage installation parts against high-frequency electromagnetic emissions registered by special differential sensors. Simultaneously, the abatement measures should be applied on the high-voltage equipment operational noise level. The authors offer a technique for noise abatement to admissible levels (lower than 80 dB A by means of coating the inside surface with shielded enclosure of densely-packed abutting sheets of porous electro-acoustic insulating

Ambient and at-the-ear occupational noise exposure and serum lipid levels

DEFF Research Database (Denmark)

Arlien-Søborg, Mai C; Schmedes, Astrid S; Stokholm, Z A

2016-01-01

-the-ear occupational noise exposure and serum levels of total cholesterol, low-density lipoprotein-cholesterol, high-density lipoprotein-cholesterol, and triglycerides when accounting for well-established predictors of lipid levels. METHODS: This cross-sectional study included 424 industrial workers and 84 financial......OBJECTIVES: Occupational and residential noise exposure has been related to increased risk of cardiovascular disease. Alteration of serum lipid levels has been proposed as a possible causal pathway. The objective of this study was to investigate the relation between ambient and at...... workers to obtain contrast in noise exposure levels. They provided a serum sample and wore portable dosimeters that every 5-s recorded ambient noise exposure levels during a 24-h period. We extracted measurements obtained during work and calculated the full-shift mean ambient noise level. For 331 workers...

Distance protection of multiple-circuit shared tower transmission lines with different voltages

DEFF Research Database (Denmark)

Silva, Filipe Miguel Faria da; Bak, Claus Leth

2017-01-01

Multiple-circuit transmission lines combining different voltage levels in one tower present extra challenges when setting a protection philosophy, as faults between voltage levels are possible. This study presents a detailed theoretical analysis of such combined faults, including the development...... of a formula for estimating the magnitude of the short-circuit current. It is demonstrated that if the faulted phase from the higher voltage level leads the faulted phase from the lower voltage level, a distance relay at the higher voltage level sees the fault in the forward direction, whereas a distance relay...

Low-voltage gyrotrons

International Nuclear Information System (INIS)

Glyavin, M. Yu.; Zavolskiy, N. A.; Sedov, A. S.; Nusinovich, G. S.

2013-01-01

For a long time, the gyrotrons were primarily developed for electron cyclotron heating and current drive of plasmas in controlled fusion reactors where a multi-megawatt, quasi-continuous millimeter-wave power is required. In addition to this important application, there are other applications (and their number increases with time) which do not require a very high power level, but such issues as the ability to operate at low voltages and have compact devices are very important. For example, gyrotrons are of interest for a dynamic nuclear polarization, which improves the sensitivity of the nuclear magnetic resonance spectroscopy. In this paper, some issues important for operation of gyrotrons driven by low-voltage electron beams are analyzed. An emphasis is made on the efficiency of low-voltage gyrotron operation at the fundamental and higher cyclotron harmonics. These efficiencies calculated with the account for ohmic losses were, first, determined in the framework of the generalized gyrotron theory based on the cold-cavity approximation. Then, more accurate, self-consistent calculations for the fundamental and second harmonic low-voltage sub-THz gyrotron designs were carried out. Results of these calculations are presented and discussed. It is shown that operation of the fundamental and second harmonic gyrotrons with noticeable efficiencies is possible even at voltages as low as 5–10 kV. Even the third harmonic gyrotrons can operate at voltages about 15 kV, albeit with rather low efficiency (1%–2% in the submillimeter wavelength region).

Personal carbon monoxide exposures of preschool children in Helsinki, Finland: levels and determinants

Science.gov (United States)

Alm, S.; Mukala, K.; Jantunen, M. J.

Personal CO exposures of 194 preschool children were measured with personal exposure monitors during a 24 week sampling period from fall 1990 to spring 1991 in Helsinki, Finland. Arithmetic mean of the maximum 1 and 8 h exposure levels were 6.0 and 3.3 mg m -3. The then Finnish ambient air quality guideline values for 1/8 h maximum CO level (30/10 mg m -3) were exceeded in 2/4% of the children's daily maximum 1/8 h exposure levels. Gas stove at home, parents, especially mother, smoking in the home, and living in high rise buildings — reflecting higher local population and traffic density — increased the children's CO exposures. The presence of a fireplace in the home was associated with decreased CO exposures. Father's high education reduced the children's CO exposure while mother's education level had no significant effect. The peak (15 min) exposure levels of the children commuting to day care center by car or bus were higher than those of the children who walked or came by bike.

Mitigation of Unbalanced Voltage Sags and Voltage Unbalance in CIGRE Low Voltage Distribution Network

DEFF Research Database (Denmark)

Mustafa, Ghullam; Bak-Jensen, Birgitte; Mahat, Pukar

2013-01-01

Any problem with voltage in a power network is undesirable as it aggravates the quality of the power. Power electronic devices such as Voltage Source Converter (VSC) based Static Synchronous Compensator (STATCOM) etc. can be used to mitigate the voltage problems in the distribution system...... to unbalanced faults. The compensation of unbalanced voltage sags and voltage unbalance in the CIGRE distribution network is done by using the four STATCOM compensators already existing in the test grid. The simulations are carried out in DIgSILENT power factory software version 15.0........ The voltage problems dealt with in this paper are to show how to mitigate unbalanced voltage sags and voltage unbalance in the CIGRE Low Voltage (LV) test network and net-works like this. The voltage unbalances, for the tested cases in the CIGRE LV test network are mainly due to single phase loads and due...

Population-Level Exposure to Particulate Air Pollution during Active Travel: Planning for Low-Exposure, Health-Promoting Cities.

Science.gov (United States)

Hankey, Steve; Lindsey, Greg; Marshall, Julian D

2017-04-01

Providing infrastructure and land uses to encourage active travel (i.e., bicycling and walking) are promising strategies for designing health-promoting cities. Population-level exposure to air pollution during active travel is understudied. Our goals were a ) to investigate population-level patterns in exposure during active travel, based on spatial estimates of bicycle traffic, pedestrian traffic, and particulate concentrations; and b ) to assess how those exposure patterns are associated with the built environment. We employed facility-demand models (active travel) and land use regression models (particulate concentrations) to estimate block-level ( n = 13,604) exposure during rush-hour (1600-1800 hours) in Minneapolis, Minnesota. We used the model-derived estimates to identify land use patterns and characteristics of the street network that are health promoting. We also assessed how exposure is correlated with indicators of health disparities (e.g., household income, proportion of nonwhite residents). Our work uses population-level rates of active travel (i.e., traffic flows) rather than the probability of walking or biking (i.e., "walkability" or "bikeability") to assess exposure. Active travel often occurs on high-traffic streets or near activity centers where particulate concentrations are highest (i.e., 20-42% of active travel occurs on blocks with high population-level exposure). Only 2-3% of blocks (3-8% of total active travel) are "sweet spots" (i.e., high active travel, low particulate concentrations); sweet spots are located a ) near but slightly removed from the city-center or b ) on off-street trails. We identified 1,721 blocks (~ 20% of local roads) where shifting active travel from high-traffic roads to adjacent low-traffic roads would reduce exposure by ~ 15%. Active travel is correlated with population density, land use mix, open space, and retail area; particulate concentrations were mostly unchanged with land use. Public health officials and

Secondhand smoke exposure and serum cotinine levels among current smokers in the USA.

Science.gov (United States)

Lindsay, Ryan P; Tsoh, Janice Y; Sung, Hai-Yen; Max, Wendy

2016-03-01

Secondhand smoke (SHS) likely provides additional exposure to nicotine and toxins for smokers, but has been understudied. Our objective was to determine whether SHS exposure among smokers yields detectable differences in cotinine levels compared with unexposed smokers at the population level. Using the US National Health and Nutrition Examination Survey (NHANES) for the years 1999-2012, we compared serum cotinine levels of 4547 current adult cigarette smokers stratified by self-reported SHS exposure sources (home and/or work) and smoking intensity. A weighted multivariable linear regression model determined the association between SHS exposure and cotinine levels among smokers. Smokers with SHS exposure at home (43.8%) had higher cotinine levels (β=0.483, p≤0.001) compared with those with no SHS exposure at home after controlling for the number of cigarettes smoked per day and number of days smoked in the previous 5 days, survey year, age, gender and education. Smokers with SHS exposure at work (20.0%) did not have significantly higher cotinine levels after adjustment. The adjusted geometric mean cotinine levels of light smokers (1-9 cigarettes per day) with no SHS exposure, exposure at work only, home only, and both home and work were 52.0, 62.7, 67.2, 74.4 ng/mL, respectively, compared with 219.4, 220.9, 255.2, 250.5 ng/mL among moderate/heavy smokers (≥10 cigarettes per day). Smokers living in residences where others smoke inside the home had significantly higher cotinine levels than smokers reporting no SHS exposure, regardless of individual smoking intensity. Future research should target the role that SHS exposure may have in nicotine dependence, cessation outcomes and other health impacts among smokers. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

Standing operating procedures for developing acute exposure guideline levels for hazardous chemicals

National Research Council Canada - National Science Library

National Research Council (U.S.). Subcommittee on Acute Exposure Guideline Levels

2001-01-01

Standing Operating Procedures for Developing Acute Exposure Guideline Levels for Hazardous Chemicals contains a detailed and comprehensive methodology for developing acute exposure guideline levels (AEGLs...

Current-Voltage Characteristics of Bi-dithiolbenzene in Parallel Arrangement

International Nuclear Information System (INIS)

Boudjella, Aissa

2011-01-01

The low voltage conductance of interacting two 1,4-dithiolbenzene (DTB) molecules is investigated. The simulation results show that the electron transport can be controlled either by changing the Fermi level position E f or modifying its inter-molecular spacing d. Molecular assembly system with close interaction between DTB units, affects significantly the conductance. In addition, the position of the Fermi plays an important role in determining the current flow. Moreover, it is important to note that E f affects not only the threshold voltage V th , but also the saturation voltage V sat . When E f approaches the LUMO energy level, V th decreases, while V sat increases. To conclude, the threshold voltage and the saturation voltage depend on the Fermi level position and the inter-molecular spacing.

DC Voltage Control and Power-Sharing of Multi-Terminal DC Grids Based on Optimal DC Power Flow and Flexible Voltage Droop Strategy

Directory of Open Access Journals (Sweden)

F. Azma

2015-06-01

Full Text Available This paper develops an effective control framework for DC voltage control and power-sharing of multi-terminal DC (MTDC grids based on an optimal power flow (OPF procedure and the voltage-droop control. In the proposed approach, an OPF algorithm is executed at the secondary level to find optimal reference of DC voltages and active powers of all voltage-regulating converters. Then, the voltage droop characteristics of voltage-regulating converters, at the primary level, are tuned based on the OPF results such that the operating point of the MTDC grid lies on the voltage droop characteristics. Consequently, the optimally-tuned voltage droop controller leads to the optimal operation of the MTDC grid. In case of variation in load or generation of the grid, a new stable operating point is achieved based on the voltage droop characteristics. By execution of a new OPF, the voltage droop characteristics are re-tuned for optimal operation of the MTDC grid after the occurrence of the load or generation variations. The results of simulation on a grid inspired by CIGRE B4 DC grid test system demonstrate efficient grid performance under the proposed control strategy.

Design and Control of a Dynamic Voltage Restorer

DEFF Research Database (Denmark)

Nielsen, John Godsk

voltage until the energy storage is completely drained or the voltages have returned to normal voltage levels. The control of the HV-DVR is a combined feedforward and feedback control to have a fast response time and load independent voltages. The control is implemented in a rotating dq-reference frame...... electric consumers against voltage dips and surges in the medium and low voltage distribution grid. The thesis first gives an introduction to relevant power quality issues for a DVR and power electronic controllers for voltage dip mitigation. Thereafter the operation and the elements in a DVR are described...... of symmetrical and non-symmetrical voltage dips. In most cases the DVR is capable of restoring the load voltages within 2 ms. During the transition phases load voltage oscillations can be generated and during the return of the supply voltages short time over-voltages can be generated by the DVR. Both...

Polychlorinated biphenyl exposure and corticosterone levels in seven polar seabird species

International Nuclear Information System (INIS)

Tartu, S.; Angelier, F.; Bustnes, J.O.; Moe, B.; Hanssen, S.A.; Herzke, D.; Gabrielsen, G.W.; Verboven, N.; Verreault, J.; Labadie, P.; Budzinski, H.; Wingfield, J.C.

2015-01-01

The role of polychlorinated biphenyls (PCBs) on exposure-related endocrine effects has been poorly investigated in wild birds. This is the case for stress hormones including corticosterone (CORT). Some studies have suggested that environmental exposure to PCBs and altered CORT secretion might be associated. Here we investigated the relationships between blood PCB concentrations and circulating CORT levels in seven free-ranging polar seabird species occupying different trophic positions, and hence covering a wide range of PCB exposure. Blood ∑ 7 PCB concentrations (range: 61–115,632 ng/g lw) were positively associated to baseline or stress-induced CORT levels in three species and negatively associated to stress-induced CORT levels in one species. Global analysis suggests that in males, baseline CORT levels generally increase with increasing blood ∑ 7 PCB concentrations, whereas stress-induced CORT levels decrease when reaching high blood ∑ 7 PCB concentrations. This study suggests that the nature of the PCB-CORT relationships may depend on the level of PCB exposure. - Highlights: • Relationships between PCBs and stress hormones (CORT) are not well known in birds. • We measured blood PCBs, baseline and stress-induced CORT in seven seabird species. • ∑PCB was positively associated to baseline or stress-induced CORT in three species. • ∑PCBs was negatively linked to stress-induced CORT in the most contaminated species. • The nature of the PCB-CORT relationships may depend on the level of PCB exposure. - In polar seabird species, the relationship between PCB and CORT concentrations may be related to the levels of contamination

Aggregate-level lead exposure, gun violence, homicide, and rape.

Science.gov (United States)

Boutwell, Brian B; Nelson, Erik J; Qian, Zhengmin; Vaughn, Michael G; Wright, John P; Beaver, Kevin M; Barnes, J C; Petkovsek, Melissa; Lewis, Roger; Schootman, Mario; Rosenfeld, Richard

2017-01-01

An increasing body of research has linked the geographic distribution of lead with various indicators of criminal and antisocial behavior. The current study, using data from an ongoing project related to lead exposure in St. Louis City, MO, analyzed the association between aggregate blood lead levels and specific indicators violent crime within the city. Ecological study. St. Louis, Missouri. Blood lead levels. Official reports of violent crimes were categorized as 1) crimes involving a firearm (yes/no), 2) assault crimes (with or without a firearm), 3) robbery crimes (with or without a firearm), 4) homicides and 5) rape. With the exception of rape, aggregate blood-lead levels were statistically significant predictors of violent crime at the census tract level. The risk ratios for each of the outcome measures were as follows: firearm crimes 1.03 (1.03-1.04), assault crimes 1.03 (1.02-1.03), robbery crimes 1.03 (1.02-1.04), homicide 1.03 (1.01, 1.04), and rape 1.01 (0.99-1.03). Extending prior research in St. Louis, results suggest that aggregated lead exposure at the census tract level predicted crime outcomes, even after accounting for important sociological variables. Moving forward, a more developed understanding of aggregate level crime may necessitate a shift toward studying the synergy between sociological and biological risk factors such as lead exposure.

Televised Antismoking Advertising: Effects of Level and Duration of Exposure

Science.gov (United States)

Cotter, Trish; Perez, Donna; Wakefield, Melanie

2013-01-01

Objectives. We assessed the effects of levels and duration of exposure to televised antismoking advertising on cognitive and behavioral changes. Methods. We used data from a serial cross-sectional telephone survey with weekly interviews of adult smokers and recent quitters in New South Wales, Australia (n = 13 301), between April 2005 and December 2010. We merged survey data with commercial TV ratings data to estimate individuals’ exposure to antismoking advertising. Results. Logistic regression analyses indicated that after adjustment for a wide range of potential confounders, exposure to antismoking advertising at levels between 100 and 200 gross rating points per week on average over 6 to 9 weeks was associated with an increased likelihood of having (1) salient quitting thoughts and (2) recent quit attempts. Associations between exposure for shorter periods and these outcomes were not significant. Conclusions. Broadcasting schedules may affect the success of antismoking ads. Campaign planners should ensure advertising exposure at adequate frequency over relatively sustained periods to maximize impact. PMID:23763419

Televised antismoking advertising: effects of level and duration of exposure.

Science.gov (United States)

Dunlop, Sally; Cotter, Trish; Perez, Donna; Wakefield, Melanie

2013-08-01

We assessed the effects of levels and duration of exposure to televised antismoking advertising on cognitive and behavioral changes. We used data from a serial cross-sectional telephone survey with weekly interviews of adult smokers and recent quitters in New South Wales, Australia (n = 13,301), between April 2005 and December 2010. We merged survey data with commercial TV ratings data to estimate individuals' exposure to antismoking advertising. Logistic regression analyses indicated that after adjustment for a wide range of potential confounders, exposure to antismoking advertising at levels between 100 and 200 gross rating points per week on average over 6 to 9 weeks was associated with an increased likelihood of having (1) salient quitting thoughts and (2) recent quit attempts. Associations between exposure for shorter periods and these outcomes were not significant. Broadcasting schedules may affect the success of antismoking ads. Campaign planners should ensure advertising exposure at adequate frequency over relatively sustained periods to maximize impact.

Distributed stability control using intelligent voltage-margin relay

Energy Technology Data Exchange (ETDEWEB)

Wiszniewski, A.; Rebizant, W. [Wroclaw Univ. of Technology (Poland); Klimek, A. [Powertech Labs Inc., Surrey, BC (Canada)

2010-07-01

This paper presented an intelligent relay that operates if the load to source impedance ratio decreases to a level that is dangerously close to the stability limit, which leads to power system blackouts. The intelligent voltage-margin/difference relay installed at receiving substations automatically initiates action if the voltage stability margin drops to a dangerously low level. The relay decides if the tap changing devices are to be blocked and if under-voltage load shedding should be initiated, thereby mitigating an evolving instability. The intelligent relay has two levels of operation. At the first stage, which corresponds to the higher load to source impedance ratio, the relay initiates blocking of the tap changer. At the second stage, corresponding to the lower source to load impedance ratio, load shedding is initiated. The relay operates when the load to source impedance ratio reaches a certain predetermined level, but it does not depend either on the level of the source voltage or on the difference of source and load impedance phase angles. The algorithm for the relay is relatively simple and uses only locally available signals. Consequently, the transformer is well controlled to eliminate the cases of voltage instability. 6 refs., 7 figs.

Novel Interleaved Converter with Extra-High Voltage Gain to Process Low-Voltage Renewable-Energy Generation

Directory of Open Access Journals (Sweden)

Chih-Lung Shen

2016-10-01

Full Text Available This paper presents a novel interleaved converter (NIC with extra-high voltage gain to process the power of low-voltage renewable-energy generators such as photovoltaic (PV panel, wind turbine, and fuel cells. The NIC can boost a low input voltage to a much higher voltage level to inject renewable energy to DC bus for grid applications. Since the NIC has two circuit branches in parallel at frond end to share input current, it is suitable for high power applications. In addition, the NIC is controlled in an interleaving pattern, which has the advantages that the NIC has lower input current ripple, and the frequency of the ripple is twice the switching frequency. Two coupled inductors and two switched capacitors are incorporated to achieve a much higher voltage gain than conventional high step-up converters. The proposed NIC has intrinsic features such as leakage energy totally recycling and low voltage stress on power semiconductor. Thorough theoretical analysis and key parameter design are presented in this paper. A prototype is built for practical measurements to validate the proposed NIC.

Quality and dose optimized CT trauma protocol. Recommendation from a university level-I trauma center

Energy Technology Data Exchange (ETDEWEB)

Kahn, Johannes; Boening, Georg; Rotzinger, Roman; Freyhardt, Patrick; Streitparth, Florian [Charite School of Medicine and Univ. Hospital Berlin (Germany). Dept. of Radiology; Kaul, David [Charite School of Medicine and Univ. Hospital Berlin (Germany). Dept. of Radiation Oncology; Schwabe, Philipp [Charite School of Medicine and Univ. Hospital Berlin (Germany). Dept. of Trauma Surgery; Maurer, Martin H. [Inselspital Bern (Switzerland). Dept. of Diagnostic, Interventional and Pediatric Radiology; Renz, Diane Miriam [Univ. Hospital Jena (Germany). Inst. of Diagnostic and Interventional Radiology

2017-09-15

As a supra-regional level-I trauma center, we evaluated computed tomography (CT) acquisitions of polytraumatized patients for quality and dose optimization purposes. Adapted statistical iterative reconstruction [(AS)IR] levels, tube voltage reduction as well as a split-bolus contrast agent (CA) protocol were applied. Materials and Methods 61 patients were split into 3 different groups that differed with respect to tube voltage (120 - 140 kVp) and level of applied ASIR reconstruction (ASIR 20 - 50%). The CT protocol included a native acquisition of the head followed by a single contrast-enhanced acquisition of the whole body (64-MSCT). CA (350 mg/ml iodine) was administered as a split bolus injection of 100 ml (2 ml/s), 20 ml NaCl (1 ml/s), 60 ml (4 ml/s), 40 ml NaCl (4 ml/s) with a scan delay of 85s to detect injuries of both the arterial system and parenchymal organs in a single acquisition. Both the quantitative (SNR/CNR) and qualitative (5-point Likert scale) image quality was evaluated in parenchymal organs that are often injured in trauma patients. Radiation exposure was assessed. The use of IR combined with a reduction of tube voltage resulted in good qualitative and quantitative image quality and a significant reduction in radiation exposure of more than 40% (DLP 1087 vs. 647 mGy x cm). Image quality could be improved due to a dedicated protocol that included different levels of IR adapted to different slice thicknesses, kernels and the examined area for the evaluation of head, lung, body and bone injury patterns. In synopsis of our results, we recommend the implementation of a polytrauma protocol with a tube voltage of 120 kVp and the following IR levels: cCT 5mm: ASIR 20; cCT 0.625 mm: ASIR 40; lung 2.5 mm: ASIR 30, body 5 mm: ASIR 40; body 1.25 mm: ASIR 50; body 0.625 mm: ASIR 0. A dedicated adaptation of the CT trauma protocol (level of reduction of tube voltage and of IR) according to the examined body region (head, lung, body, bone) combined with a

Quality and dose optimized CT trauma protocol. Recommendation from a university level-I trauma center

International Nuclear Information System (INIS)

Kahn, Johannes; Boening, Georg; Rotzinger, Roman; Freyhardt, Patrick; Streitparth, Florian; Kaul, David; Schwabe, Philipp; Maurer, Martin H.; Renz, Diane Miriam

2017-01-01

As a supra-regional level-I trauma center, we evaluated computed tomography (CT) acquisitions of polytraumatized patients for quality and dose optimization purposes. Adapted statistical iterative reconstruction [(AS)IR] levels, tube voltage reduction as well as a split-bolus contrast agent (CA) protocol were applied. Materials and Methods 61 patients were split into 3 different groups that differed with respect to tube voltage (120 - 140 kVp) and level of applied ASIR reconstruction (ASIR 20 - 50%). The CT protocol included a native acquisition of the head followed by a single contrast-enhanced acquisition of the whole body (64-MSCT). CA (350 mg/ml iodine) was administered as a split bolus injection of 100 ml (2 ml/s), 20 ml NaCl (1 ml/s), 60 ml (4 ml/s), 40 ml NaCl (4 ml/s) with a scan delay of 85s to detect injuries of both the arterial system and parenchymal organs in a single acquisition. Both the quantitative (SNR/CNR) and qualitative (5-point Likert scale) image quality was evaluated in parenchymal organs that are often injured in trauma patients. Radiation exposure was assessed. The use of IR combined with a reduction of tube voltage resulted in good qualitative and quantitative image quality and a significant reduction in radiation exposure of more than 40% (DLP 1087 vs. 647 mGy x cm). Image quality could be improved due to a dedicated protocol that included different levels of IR adapted to different slice thicknesses, kernels and the examined area for the evaluation of head, lung, body and bone injury patterns. In synopsis of our results, we recommend the implementation of a polytrauma protocol with a tube voltage of 120 kVp and the following IR levels: cCT 5mm: ASIR 20; cCT 0.625 mm: ASIR 40; lung 2.5 mm: ASIR 30, body 5 mm: ASIR 40; body 1.25 mm: ASIR 50; body 0.625 mm: ASIR 0. A dedicated adaptation of the CT trauma protocol (level of reduction of tube voltage and of IR) according to the examined body region (head, lung, body, bone) combined with a

Numerical Study on Open-Circuit Voltage of Single Layer Organic Solar Cells with Schottky Contacts: Effects of Molecular Energy Levels, Temperature and Thickness

International Nuclear Information System (INIS)

Rong-Hua, Li; Ying-Quan, Peng; Chao-Zhu, Ma; Run-Sheng, Wang; Hong-Wei, Xie; Ying, Wang; Wei-Min, Meng

2010-01-01

We numerically investigate the effects of the exciton generation rate G, temperature T, the active layer thickness d and the position of LUMO level E L related to the cathode work function W c at a given energy gap on the open-circuit voltage V oc of single layer organic solar cells with Schottky contact. It is demonstrated that open-circuit voltage increases concomitantly with the decreasing cathode work function W c for given anode work functions and exciton generation rates. In the case of given cathode and anode work functions, the open-circuit voltage first increases with the exciton generation rate and then reaches a saturation value, which equals to the built-in voltage. Additionally, it is worth noting that a significant improvement to V oc could be made by selecting an organic material which has a relative high LUMO level (low |E L | value). However, V oc decreases as the temperature increases, and the decreasing rate reduces with the enhancement of exciton generation rate. Our study also shows that it is of no benefit to improve the open-circuit voltage by increasing the device thickness because of an enhanced charge recombination in thicker devices. (cross-disciplinary physics and related areas of science and technology)

Low-level exposure to organophosphate pesticides leads to restrictive lung dysfunction.

Science.gov (United States)

Peiris-John, Roshini Janet; Ruberu, Dawala Kusuma; Wickremasinghe, Ananda Rajitha; van-der-Hoek, Wim

2005-10-01

Apart from symptomology, there are very few reports on lung function following exposure to low levels of organophosphate (OP) pesticides in man. Twenty-five occupationally exposed farmers and 22 environmentally exposed freshwater fishermen were evaluated between and during OP spray seasons. Forty marine fishermen living away from agricultural areas were recruited as a control group. Forced vital capacity (FVC) and forced expiratory volume in the first second (FEV(1)) were measured by spirometry. Haemoglobin corrected erythrocyte acetylcholinesterase (AChE) levels were measured during and between (baseline estimation) spray seasons using a portable WHO-approved Test-mate system (EQM Research, Ohio). FVC ratio was lower in the farmers as compared to the controls (P<0.001) between exposure seasons. In the farmers, FVC ratio decreased further during the exposure season (P=0.023). FEV(1) was lower in the farmers as compared to the controls in both periods (P<0.05). In the fishermen, the decrease in ratios of FVC and FEV(1) following exposure to pesticides was not significant. FEV(1)/FVC ratios were similar in the three groups between (P=0.988) and during (P=0.159) exposure periods. Following exposure to OPs, AChE levels dropped 12.75% in the farmers (P<0.001) and 5.62% in the freshwater fishermen (P=0.001). Occupational exposure to OP results in restrictive lung dysfunction, a phenomenon not observed following environmental exposure.

What happens at very low levels of radiation exposure ? Are the low dose exposures beneficial ?

International Nuclear Information System (INIS)

Deniz, Dalji

2006-01-01

Full text: Radiation is naturally present in our environment and has been since the birth of this planet. The human population is constantly exposed to low levels of natural background radiation, primarily from environmental sources, and to higher levels from occupational sources, medical therapy, and other human-mediated events. Radiation is one of the best-investigated hazardous agents. The biological effects of ionizing radiation for radiation protection consideration are grouped into two categories: The deterministic and the stochastic ones. Deterministic radiation effects can be clinically diagnosed in the exposed individual and occur when above a certain t hreshold a n appropriately high dose is absorbed in the tissues and organs to cause the death of a large number of cells and consequently to impair tissue or organ functions early after exposure. A clinically observable biological effect (Acute Radiation Sendromes, ARS) occurs days to months after an acute radiation dose. Stochastic radiation effects are the chronic effects of radiation result from relatively low exposure levels delivered over long periods of time. These are sort of effects that might result from occupational exposure, or to the background exposure levels. Such late effects might be the development of malignant (cancerous) disease and of the hereditary consequences. These effects may be observed many years after the radiation exposure. There is a latent period between the initial radiation exposure and the development of the biological effect. For this reason, a stochastic effect is called a Linear or Zero-Threshold (LNT) Dose-Response Effect. There is a stochastic correlation between the number of cases of cancers or genetic defects developed inside a population and the dose received by the population at relatively large levels of radiation. These changes in gene activation seem to be able to modify the response of cells to subsequent radiation exposure, termed the a daptive response

Dose level of occupational exposure in China

International Nuclear Information System (INIS)

Tian, Y.; Zhang, L.; Ju, Y.

2008-01-01

This paper discusses the dose level of Chinese occupational exposures during 1986-2000. Data on occupational exposures from the main categories in nuclear fuel cycle (uranium enrichment and conversion, fuel fabrication, reactor operation, waste management and research activity, except for uranium mining and milling because of the lack of data), medical uses of radiation (diagnostic radiation, nuclear medicine and radiotherapy) and industrial uses of radiation (industrial radiography and radioisotope production) are presented and summarised in detail. These are the main components of occupational exposures in China. In general, the average annual effective doses show a steady decreasing trend over periods: from 2.16 to 1.16 mSv in medical uses of radiation during 1990-2000; from 1.92 to 1.18 mSv in industrial radiography during 1990-2000; from 8.79 to 2.05 mSv in radioisotope production during the period 1980-2000. Almost all the average annual effective doses in discussed occupations were lower than 5 mSv in recent years (except for well-logging: 6.86 mSv in 1999) and no monitored workers were found to have received the occupational exposure exceeding 50 mSv in a single year or 100 mSv in a five-year period. So the Chinese protection status of occupation exposure has been improved in recent years. However, the average annual effective doses in some occupations, such as diagnostic radiology and coal mining, were still much higher than that of the whole world. There are still needs for further improvement and careful monitoring of occupational exposure to protect every worker from excessive occupational exposure, especially for the workers who were neglected before. (authors)

High voltage engineering fundamentals

CERN Document Server

Kuffel, E; Hammond, P

1984-01-01

Provides a comprehensive treatment of high voltage engineering fundamentals at the introductory and intermediate levels. It covers: techniques used for generation and measurement of high direct, alternating and surge voltages for general application in industrial testing and selected special examples found in basic research; analytical and numerical calculation of electrostatic fields in simple practical insulation system; basic ionisation and decay processes in gases and breakdown mechanisms of gaseous, liquid and solid dielectrics; partial discharges and modern discharge detectors; and over

Survey of RF exposure levels from mobile telephone base stations in Australia.

Science.gov (United States)

Henderson, S I; Bangay, M J

2006-01-01

This paper reports the results of an exposure level survey of radiofrequency electromagnetic energy originating from mobile telephone base station antennas. Measurements of CDMA800, GSM900, GSM1800, and 3G(UMTS) signals were performed at distances ranging over 50 to 500 m from 60 base stations in five Australian cities. The exposure levels from these mobile telecommunications base stations were found to be well below the general public exposure limits of the ICNIRP guidelines and the Australian radiofrequency standard (ARPANSA RPS3). The highest recorded level from a single base station was 7.8 x 10(-3) W/m(2), which translates to 0.2% of the general public exposure limit.

Mapping of radio frequency electromagnetic field exposure levels in outdoor environment and comparing with reference levels for general public health.

Science.gov (United States)

Cansiz, Mustafa; Abbasov, Teymuraz; Kurt, M Bahattin; Celik, A Recai

2018-03-01

In this study, radio frequency electromagnetic field exposure levels were measured on the main streets in the city center of Diyarbakır, Turkey. Measured electric field levels were plotted on satellite imagery of Diyarbakır and were compared with exposure guidelines published by the International Commission on Non-Ionizing Radiation Protection (ICNIRP). Exposure measurements were performed in dense urban, urban and suburban areas each day for 7 consecutive days. The measurement system consisted of high precision and portable spectrum analyzer, three-axis electric field antenna, connection cable and a laptop which was used to record the measurement samples as a data logger. The highest exposure levels were detected for two places, which are called Diclekent and Batıkent. It was observed that the highest instantaneous electric field strength value for Batıkent was 7.18 V/m and for Diclekent was 5.81 V/m. It was statistically determined that the main contributor band to the total exposure levels was Universal Mobile Telecommunications System band. Finally, it was concluded that all measured exposure levels were lower than the reference levels recommended by ICNIRP for general public health.

A matter of quantum voltages

Energy Technology Data Exchange (ETDEWEB)

Sellner, Bernhard; Kathmann, Shawn M., E-mail: Shawn.Kathmann@pnnl.gov [Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352 (United States)

2014-11-14

Voltages inside matter are relevant to crystallization, materials science, biology, catalysis, and aqueous chemistry. The variation of voltages in matter can be measured by experiment, however, modern supercomputers allow the calculation of accurate quantum voltages with spatial resolutions of bulk systems well beyond what can currently be measured provided a sufficient level of theory is employed. Of particular interest is the Mean Inner Potential (V{sub o}) – the spatial average of these quantum voltages referenced to the vacuum. Here we establish a protocol to reliably evaluate V{sub o} from quantum calculations. Voltages are very sensitive to the distribution of electrons and provide metrics to understand interactions in condensed phases. In the present study, we find excellent agreement with measurements of V{sub o} for vitrified water and salt crystals and demonstrate the impact of covalent and ionic bonding as well as intermolecular/atomic interactions. Certain aspects in this regard are highlighted making use of simple model systems/approximations. Furthermore, we predict V{sub o} as well as the fluctuations of these voltages in aqueous NaCl electrolytes and characterize the changes in their behavior as the resolution increases below the size of atoms.

Radiation-induced taste aversion: effects of radiation exposure level and the exposure-taste interval

International Nuclear Information System (INIS)

Spector, A.C.; Smith, J.C.; Hollander, G.R.

1986-01-01

Radiation-induced taste aversion has been suggested to possibly play a role in the dietary difficulties observed in some radiotherapy patients. In rats, these aversions can still be formed even when the radiation exposure precedes the taste experience by several hours. This study was conducted to examine whether increasing the radiation exposure level could extend the range of the exposure-taste interval that would still support the formation of a taste aversion. Separate groups of rats received either a 100 or 300 R gamma-ray exposure followed 1, 3, 6, or 24 h later by a 10-min saccharin (0.1% w/v) presentation. A control group received a sham exposure followed 1 h later by a 10-min saccharin presentation. Twenty-four hours following the saccharin presentation all rats received a series of twelve 23-h two-bottle preference tests between saccharin and water. The results indicated that the duration of the exposure-taste interval plays an increasingly more important role in determining the initial extent of the aversion as the dose decreases. The course of recovery from taste aversion seems more affected by dose than by the temporal parameters of the conditioning trial

Coordinated Voltage Control of Distributed PV Inverters for Voltage Regulation in Low Voltage Distribution Networks

DEFF Research Database (Denmark)

Nainar, Karthikeyan; Pokhrel, Basanta Raj; Pillai, Jayakrishnan Radhakrishna

2017-01-01

This paper reviews and analyzes the existing voltage control methods of distributed solar PV inverters to improve the voltage regulation and thereby the hosting capacity of a low-voltage distribution network. A novel coordinated voltage control method is proposed based on voltage sensitivity...... optimization. The proposed method is used to calculate the voltage bands and droop settings of PV inverters at each node by the supervisory controller. The local controller of each PV inverter implements the volt/var control and if necessary, the active power curtailment as per the received settings and based...... on measured local voltages. The advantage of the proposed method is that the calculated reactive power and active power droop settings enable fair contribution of the PV inverters at each node to the voltage regulation. Simulation studies are conducted using DigSilent Power factory software on a simplified...

Associations between cadmium exposure and circulating levels of sex hormones in postmenopausal women

Energy Technology Data Exchange (ETDEWEB)

Ali, Imran; Engström, Annette; Vahter, Marie [Institute of Environmental Medicine, Karolinska Institutet, 171 77 Stockholm (Sweden); Skerfving, Staffan; Lundh, Thomas [Division of Occupational and Environmental Medicine, University Hospital, Lund (Sweden); Lidfeldt, Jonas [Department of Community Health, Malmö University Hospital, Malmö (Sweden); Samsioe, Göran [Department of Gynecology and Obstetrics, University Hospital, Lund (Sweden); Halldin, Krister [Institute of Environmental Medicine, Karolinska Institutet, 171 77 Stockholm (Sweden); Åkesson, Agneta, E-mail: agneta.akesson@ki.se [Institute of Environmental Medicine, Karolinska Institutet, 171 77 Stockholm (Sweden)

2014-10-15

Recent epidemiological as well as in vivo and in vitro studies collectively suggest that the metalloestrogen cadmium (Cd) could be a potential risk factor for hormone-related cancers in particularly breast cancer. Assessment of the association between Cd exposure and levels of endogenous sex hormones is of pivotal importance, as increased levels of such have been associated with a higher risk of breast cancer in postmenopausal women. The present study investigated the perceived relationship (multivariable-adjusted linear regression analyses) between Cd exposure [blood Cd (B-Cd) and urinary Cd (U-Cd)], and serum levels of androstenedione, testosterone, estradiol, and sex-hormone binding globulin (SHBG), in 438 postmenopausal Swedish women without hormone replacement therapy (HRT). A significant positive association between B-Cd (median 3.4 nmol/L) and serum testosterone levels, as well as a significant inverse association between B-Cd and serum estradiol levels and with the estradiol/testosterone ratio were encountered. However, U-Cd (median 0.69 nmol/mmol creatinine) was inversely associated with serum estradiol levels only. Our data may suggest that Cd interferes with the levels of testosterone and estradiol in postmenopausal women, which might have implications for breast cancer risk. - Highlights: • Low level cadmium exposure may interfere with the levels of steroid hormones. • Cadmium exposure was associated with increased serum testosterone concentrations. • Cadmium exposure was associated with decreased estradiol/testosterone ratio. • Cadmium exposure may have implications for breast-cancer promotion.

Respiratory health effects of exposure to low levels of airborne endotoxin - a systematic review.

Science.gov (United States)

Farokhi, Azadèh; Heederik, Dick; Smit, Lidwien A M

2018-02-08

Elevated endotoxin levels have been measured in ambient air around livestock farms, which is a cause of concern for neighbouring residents. There is clear evidence that occupational exposure to high concentrations of airborne endotoxin causes respiratory inflammation, respiratory symptoms and lung function decline. However, health effects of exposure to low levels of endotoxin are less well described. The aim of this systematic review is to summarize published associations between exposure to relatively low levels of airborne endotoxin and respiratory health endpoints. Studies investigating respiratory effects of measured or modelled exposure to low levels of airborne endotoxin (average effects of exposure to low levels of endotoxin on respiratory symptoms and lung function. However, considerable heterogeneity existed in the outcomes of the included studies and no overall estimate could be provided by meta-analysis to quantify the possible relationship. Instead, a best evidence synthesis was performed among studies examining the exposure-response relationship between endotoxin and respiratory outcomes. Significant exposure-response relationships between endotoxin and symptoms and FEV 1 were shown in several studies, with no conflicting findings in the studies included in the best evidence synthesis. Significantly different effects of endotoxin exposure were also seen in vulnerable subgroups (atopics and patients with broncho-obstructive disease) and smokers. Respiratory health effects of exposure to low levels of airborne endotoxin (health effects, especially in vulnerable subgroups of the population.

Biomonitoring of organophosphate exposure of pesticide sprayers and comparison of exposure levels with other population groups in Thessaly (Greece).

Science.gov (United States)

Koureas, Michalis; Tsakalof, Andreas; Tzatzarakis, Manolis; Vakonaki, Elena; Tsatsakis, Aristidis; Hadjichristodoulou, Christos

2014-02-01

To evaluate the exposure of different population groups in Thessaly (Greece) to organophosphate pesticides (OPs) and investigate the dependence of exposure levels on pesticide application practices, personal protective and hygienic measures taken. For the exposure assessment, four dialkyl phosphate (DAP) metabolites of organophosphate pesticides were quantified in spot urine samples of 77 pesticide sprayers, 75 residents of the studied agricultural area non-involved in agricultural activities and 112 urban residents who served as a control group. Structured questionnaires were used to record demographic characteristics, pesticide application parameters and protective measures taken. Univariate and multivariate analysis of the obtained cross-sectional data was performed to identify potential risk factors associated with biomarker levels. It was found that total DAP median level in the sprayers' group was 24.9 μg/g creatinine (IQR: 13.0-42.1), while the rural and urban residents had significantly lower (p<0.001) levels of 11.3 μg/g creatinine (IQR: 5.3-18.7) and 11.9 μg/g creatinine (IQR: 6.3-20.3), respectively. In sprayers who had recently applied an OP pesticide (n=28), the median levels of DAP metabolites were 31.8 μg/g creatinine (IQR: 22.3-117.2). Logistic regression analysis showed that the use of full body coveralls while handling and spraying pesticides was significantly associated with lower DAP levels (OR 4.05, 95% CI 1.22 to 13.46). Also, changing clothes immediately after accidental contamination of clothing with pesticide amounts was found to be significantly associated with lower exposure levels (OR 4.04, CI 1.05 to 15.57). Our study findings confirm the increased exposure to OPs in pesticide sprayers and underline the importance of protective measures especially those that focus on dermal exposure mitigation.

Nickel exposure and plasma levels of biomarkers for assessing oxidative stress in nickel electroplating workers.

Science.gov (United States)

Tsao, Yu-Chung; Gu, Po-Wen; Liu, Su-Hsun; Tzeng, I-Shiang; Chen, Jau-Yuan; Luo, Jiin-Chyuan John

2017-07-01

The mechanism of nickel-induced pathogenesis remains elusive. To examine effects of nickel exposure on plasma oxidative and anti-oxidative biomarkers. Biomarker data were collected from 154 workers with various levels of nickel exposure and from 73 controls. Correlations between nickel exposure and oxidative and anti-oxidative biomarkers were determined using linear regression models. Workers with a exposure to high nickel levels had significantly lower levels of anti-oxidants (glutathione and catalase) than those with a lower exposure to nickel; however, only glutathione showed an independent association after multivariable adjustment. Exposure to high levels of nickel may reduce serum anti-oxidative capacity.

Modification of otoacoustic emissions following ear-level exposure to MP3 player music.

Science.gov (United States)

Bhagat, Shaum P; Davis, Anne M

2008-12-01

The purpose of this study was to examine if a pre-determined exposure level and duration of MP3 player music would result in significant changes in cochlear function when measured with audiometric and physiological methods. Distortion-product otoacoustic emissions (DPOAEs), synchronized spontaneous otoacoustic emissions (SSOAEs), and hearing thresholds were measured in 20 normal-hearing adults before and after a 30-minute MP3 player music exposure. DPOAEs were acquired with 65/45 dB SPL primary tones (f(2)=0.842-7.996 kHz) with a frequency resolution of 8 points/octave. A probe microphone system recorded ear-canal music levels and was used to equalize levels at approximately 85 dBC across individuals during the music presentation. Comparison of pre- and post-exposure measurements revealed no significant differences in hearing thresholds, but DPOAE levels in half-octave bands centered from 1.4-6.0 kHz were significantly reduced following the music exposure. Post-exposure shifts in SSOAE frequency and level were highly variable in individuals identified with SSOAEs. The results for the exposure conditions explored in this study indicate that changes in otoacoustic emissions may precede the development of music-induced hearing threshold shifts.

Relationship medical exposure in X-ray diagnosis and loading factor and film/screen system for reduction exposure dose in Aomori. An analysis based on the results of questionnaire

International Nuclear Information System (INIS)

Kon, Masanori; Fukushi, Shouji; Oota, Fumio; Kawamura, Kouji; Shinohe, Tetsuo; Suwa, Kouki; Fujii, Kiyosuke; Yamagami, Hirofumi

2000-01-01

A fact-finding questionnaire survey on medical exposure in Aomori Prefecture was conducted in September 1998. Of the 23 exposed sites in the body investigated, exposure at 17 sites in adults was investigated in terms of the type of high-voltage generator, imaging conditions (X-ray tube voltage, electric current, exposure time, etc.), photosensitive materials and relative photosensitivity, and entrance surface doses. At 6 of the 17 exposed sites, the relationships between these technical conditions and entrance surface doses were analyzed to consider further reduction of medical exposure. The most frequently used high-voltage generators were inverter generators (about 52%). In many institutions, additional filters were utilized for high-voltage imaging of the chest. Highly sensitive green-emission materials were the most frequently used photosensitive materials (73%). These findings indicate that many institutions are attempting to reduce exposure. Entrance surface doses varied greatly among institutions: and a 100-fold difference was observed in exposure to the chest, Martius, and the pelvis. Further efforts to lower entrance surface doses are therefore necessary to reduce medical exposure. Negative correlations were observed between electric voltage, electric current, and exposure time. Examination of the relationships between entrance surface doses, electric current, and exposure time yielded positive correlations. However, the entrance surface doses may not have been properly calculated in some institutions, and examination of the relationship between the relative sensitivity of the sensitive material and entrance surface doses showed great variability in entrance surface doses between institutions. Based on the above results, it is concluded that further reduction of medical exposure is possible, not only by improving the accuracy of X-ray units/devices, but by choosing a more appropriate of conditions to perform radiography. (K.H.)

A hybrid modeling with data assimilation to evaluate human exposure level

Science.gov (United States)

Koo, Y. S.; Cheong, H. K.; Choi, D.; Kim, A. L.; Yun, H. Y.

2015-12-01

Exposure models are designed to better represent human contact with PM (Particulate Matter) and other air pollutants such as CO, SO2, O3, and NO2. The exposure concentrations of the air pollutants to human are determined by global and regional long range transport of global and regional scales from Europe and China as well as local emissions from urban and road vehicle sources. To assess the exposure level in detail, the multiple scale influence from background to local sources should be considered. A hybrid air quality modeling methodology combing a grid-based chemical transport model with a local plume dispersion model was used to provide spatially and temporally resolved air quality concentration for human exposure levels in Korea. In the hybrid modeling approach, concentrations from a grid-based chemical transport model and a local plume dispersion model are added to provide contributions from photochemical interactions, long-range (regional) transport and local-scale dispersion. The CAMx (Comprehensive Air quality Model with Extensions was used for the background concentrations from anthropogenic and natural emissions in East Asia including Korea while the road dispersion by vehicle emission was calculated by CALPUFF model. The total exposure level of the pollutants was finally assessed by summing the background and road contributions. In the hybrid modeling, the data assimilation method based on the optimal interpolation was applied to overcome the discrepancies between the model predicted concentrations and observations. The air quality data from the air quality monitoring stations in Korea. The spatial resolution of the hybrid model was 50m for the Seoul Metropolitan Ares. This example clearly demonstrates that the exposure level could be estimated to the fine scale for the exposure assessment by using the hybrid modeling approach with data assimilation.

Early renal effects of occupational exposure to low-level hexavalent chromium

Energy Technology Data Exchange (ETDEWEB)

Nagaya, Teruo (Dept. of Public Health, Gifu Univ. School of Medicine, Tsukasa-machi (Japan)); Ishikawa, Noriko (Occupational Hygiene Center, Gifu Labour Standards Association, Hikie (Japan)); Hata, Hideo (Occupational Hygiene Center, Gifu Labour Standards Association, Hikie (Japan)); Takahashi, Akemi (Gifu-shi Central Public Health Center, Miyako-dori (Japan)); Yoshida, Izumi (Gifu-shi Central Public Health Center, Miyako-dori (Japan)); Okamoto, Yoshinari (Gifu-shi Central Public Health Center, Miyako-dori (Japan))

1994-05-01

To detect early renal effects of occupational exposure to hexavalent chromium (Cr), urinary total proteins (U-TP), urinary albumin (U-Alb) and urinary retinol-binding protein (U-RBP) were determined in 166 male Cr platers and 106 male controls. The mean employment time in Cr plating for the platers was 12.6 years. Urinary Cr (U-Cr), which was determined as an index of Cr exposure, ranged from ''not detected'' to 19.91 [mu]g/g creatinine in the platers. The U-Cr level was lower than those in other previous studies. Age-adjusted U-TP, U-Alb or U-RBP levels were not different between the platers and the controls. In the platers, a significant positive correlation was found between age-adjusted U-TP and U-Cr, but U-Cr had no significant relation to age-adjusted U-Alb or U-RBP level. Employment time had no effect on any age-adjusted urinary proteins. The Cr exposure may have been too low to induce definite renal dysfunction. Early renal effects of low-level Cr exposure may be mild, and may not be specific to renal function. (orig.)

Optimum voltage of auxiliary systems for thermal and nuclear power plants

International Nuclear Information System (INIS)

Tokumitsu, Iwao; Segawa, Motomichi

1979-01-01

In the power plants in Japan, their unit power output has been greatly enhanced since the introduction of new powerful thermal power plants from 1950's to 1960's. In both thermal and nuclear power plants, 1,000 MW machines have been already in operation. The increase of unit power output results in the increase of in-plant load capacity. Of these the voltage adopted for in-plant low voltage systems is now mainly 440 V at load terminals, and the voltage for in-plant high voltage systems has been changing to 6 kV level via 3 kV and 4 kV levels. As plant capacity increases, the load of low voltage systems significantly increases, and it is required to raise the voltage of 400 V level. By the way, the low voltage in AC is specified to be not higher than 600 V. This makes the change within the above range comparatively easy. Considering these conditions, it is recommended to change the voltage for low voltage systems to 575 V at power source terminals and 550 V at load terminals. Some merits in constructing power systems and in economy by raising the voltage were examined. Though demerits are also found, they are only about 15% of total merits. The most advantageous point in raising the voltage is to be capable of increasing the supplying range to low voltage system loads. (Wakatsuki, Y.)

Secondary Control for Voltage Quality Enhancement in Microgrids

DEFF Research Database (Denmark)

Savaghebi, Mehdi; Jalilian, Alireza; Vasquez, Juan Carlos

2012-01-01

In this paper, a hierarchical control scheme is proposed for enhancement of sensitive load bus (SLB) voltage quality in microgrids. The control structure consists of primary and secondary levels. The primary control level comprises distributed generators (DGs) local controllers. Each of these con......In this paper, a hierarchical control scheme is proposed for enhancement of sensitive load bus (SLB) voltage quality in microgrids. The control structure consists of primary and secondary levels. The primary control level comprises distributed generators (DGs) local controllers. Each...

Voltage Stabilizer Based on SPWM technique Using Microcontroller

OpenAIRE

K. N. Tarchanidis; J. N. Lygouras; P. Botsaris

2013-01-01

This paper presents an application of the well known SPWM technique on a voltage stabilizer, using a microcontroller. The stabilizer is AC/DC/AC type. So, the system rectifies the input AC voltage to a suitable DC level and the intelligent control of an embedded microcontroller regulates the pulse width of the output voltage in order to produce through a filter a perfect sinusoidal AC voltage. The control program on the microcontroller has the ability to change the FET transistor ...

Standing operating procedures for developing acute exposure guideline levels for hazardous chemicals

National Research Council Canada - National Science Library

National Research Council (U.S.). Subcommittee on Acute Exposure Guideline Levels

2001-01-01

... Exposure Guideline Levels for Hazardous Chemicals Subcommittee on Acute Exposure Guideline Levels Committee on Toxicology Board on Environmental Studies and Toxicology Commission on Life Sciences National Research Council NATIONAL ACADEMY PRESS Washington, D.C. i Copyrightthe cannot be not from book, paper however, version for formatting, origina...

Mitigation of Voltage Sags in CIGRE Low Voltage Distribution Network

DEFF Research Database (Denmark)

Mustafa, Ghullam; Bak-Jensen, Birgitte; Mahat, Pukar

2013-01-01

Any problem in voltage in a power network is undesirable as it aggravates the quality of the power. Power electronic devices such as Voltage Source Converter (VSC) based Static Synchronous Compensator (STATCOM), Dynamic Voltage Restorer (DVR) etc. are commonly used for the mitigation of voltage p....... The compensation of voltage sags in the different parts of CIGRE distribution network is done by using the four STATCOM compensators already existing in the test grid. The simulations are carried out in DIgSILENT power factory software version 15.0.......Any problem in voltage in a power network is undesirable as it aggravates the quality of the power. Power electronic devices such as Voltage Source Converter (VSC) based Static Synchronous Compensator (STATCOM), Dynamic Voltage Restorer (DVR) etc. are commonly used for the mitigation of voltage...... problems in the distribution system. The voltage problems dealt with in this paper are to show how to mitigate voltage sags in the CIGRE Low Voltage (LV) test network and networks like this. The voltage sags, for the tested cases in the CIGRE LV test network are mainly due to three phase faults...

Pesticide Exposure and Cholinesterase Levels in Migrant Farm Workers in Thailand.

Science.gov (United States)

Thetkathuek, Anamai; Yenjai, Pornthip; Jaidee, Wanlop; Jaidee, Patchana; Sriprapat, Poonsak

2017-01-01

In this study, we examined the effects of pesticides in migrant farm workers from Cambodia after workplace exposure on fruit plantations in eastern Thailand. We studied 891 migrant farm workers employed on pineapple, durian, and rambutan plantations in Thailand. Data were collected via a detailed questionnaire survey and measurements of serum cholinesterase level (SChE). The majority of subjects was male (57.7%), with an average age of 30.3 years. Most subjects (76.8%) were moderately aware of good industrial hygiene practices. SChE level was divided into four groups based on the results. Only 4.4% had normal levels of cholinesterase activity, 20.5% had slightly reduced levels, 58.5% had markedly reduced levels and were "at risk," and 16.6% who had highest levels of cholinesterase inhibition were deemed to be in an "unsafe" range. SChE was classified into two groups, SChE value of 87.5 was "normal" and 39 acres, use a backpack sprayer, or have a low level of compliance with accepted industrial hygiene practices. These three classes of workers are at increased risk of chemical exposures and developing acute or chronic illness from pesticide exposures.

Occupational exposure to beryllium in French enterprises: a survey of airborne exposure and surface levels.

Science.gov (United States)

Vincent, Raymond; Catani, Jacques; Créau, Yvon; Frocaut, Anne-Marie; Good, Andrée; Goutet, Pierre; Hou, Alain; Leray, Fabrice; André-Lesage, Marie-Ange; Soyez, Alain

2009-06-01

An assessment survey of occupational exposure to beryllium (Be) was conducted in France between late 2004 and the end of 2006. Exposure estimates were based on the analytical results of samples collected from workplace air and from work surfaces in 95 facilities belonging to 37 sectors of activity. The results of this study indicated airborne Be concentrations in excess of the occupational exposure limit value of 2 microg m(-3) recommended in France. Metallurgy and electronic component manufacturing represented the activities and occupations where workers had the highest arithmetic mean exposures to Be. Surface contamination levels were also high and frequently exceeded thresholds recommended by different bodies. These results should prompt the development of prevention programmes that include Be substitution, process control and surface decontamination, in conjunction with suitable medical surveillance.

Development of a New Cascade Voltage-Doubler for Voltage Multiplication

OpenAIRE

Toudeshki, Arash; Mariun, Norman; Hizam, Hashim; Abdul Wahab, Noor Izzri

2014-01-01

For more than eight decades, cascade voltage-doubler circuits are used as a method to produce DC output voltage higher than the input voltage. In this paper, the topological developments of cascade voltage-doublers are reviewed. A new circuit configuration for cascade voltage-doubler is presented. This circuit can produce a higher value of the DC output voltage and better output quality compared to the conventional cascade voltage-doubler circuits, with the same number of stages.

Evaluation of Image According to Exposure Conditions using Contrast-Detail Phantom for Chest Digital Radiography

Energy Technology Data Exchange (ETDEWEB)

Lee, In Ja [Dept. of Radiologic Tecnology, Dongnam Health College, Suwon (Korea, Republic of); Kim, You Hyun; Kim, Chang Nam [Dept. of Radiological Science, College of Health Science, Korea University, Seoul (Korea, Republic of); Kim, Chang Nam; Lee, Chang Yeob; Park, Kye Yeon [Dept. of Diagnostic Radiology, Korea University Guro Hospital, Seoul (Korea, Republic of)

2009-03-15

To find out proper photographing conditions in the chest DR imaging, the evaluation of images using the C-D phantom was carried out on relationship of identification capability, graininess, and exposure ratio. The conclusions were obtained as follows. 1. The patient's entrance skin Exposure (ESE) was decreased as tube voltage was increased. 2. According to the tube voltage change, the C-D phantom's identification capability of the exposure conditions was most visible at 110 kVp. 3. The identification capability according to the exposure ratio (mAs) change was most visible at 90 kVp for 0.5 times of low exposure ratio and at 110 kVp for 1.5 times. Therefore, it is known that the images were able to be better identified at a high exposure than a low exposure. 4. The graininess according to the exposure ratio at tube voltage of 110 kVp resulted in the best thing at 1.5 times of ratio when the exposure ratio was 1.5 times increased and the tube voltage was changed, the graininess showed the best result at 110 kVp. Therefore, the patient's exposure dose was low when kVp was increased and the adequate kVp was found to be 110. The image was better identified when exposure ratio was 1.5 times compared to 1.0 times. The graininess was also good when the exposure ratio became 1.5 times. The tube voltage was good at 110 kVp. However, once the exposure ratio is increased, the amount of radiation dose that the patients received get increased, so that the exposure condition has to be thoroughly considered.

Evaluation of Image According to Exposure Conditions using Contrast-Detail Phantom for Chest Digital Radiography

International Nuclear Information System (INIS)

Lee, In Ja; Kim, You Hyun; Kim, Chang Nam; Kim, Chang Nam; Lee, Chang Yeob; Park, Kye Yeon

2009-01-01

To find out proper photographing conditions in the chest DR imaging, the evaluation of images using the C-D phantom was carried out on relationship of identification capability, graininess, and exposure ratio. The conclusions were obtained as follows. 1. The patient's entrance skin Exposure (ESE) was decreased as tube voltage was increased. 2. According to the tube voltage change, the C-D phantom's identification capability of the exposure conditions was most visible at 110 kVp. 3. The identification capability according to the exposure ratio (mAs) change was most visible at 90 kVp for 0.5 times of low exposure ratio and at 110 kVp for 1.5 times. Therefore, it is known that the images were able to be better identified at a high exposure than a low exposure. 4. The graininess according to the exposure ratio at tube voltage of 110 kVp resulted in the best thing at 1.5 times of ratio when the exposure ratio was 1.5 times increased and the tube voltage was changed, the graininess showed the best result at 110 kVp. Therefore, the patient's exposure dose was low when kVp was increased and the adequate kVp was found to be 110. The image was better identified when exposure ratio was 1.5 times compared to 1.0 times. The graininess was also good when the exposure ratio became 1.5 times. The tube voltage was good at 110 kVp. However, once the exposure ratio is increased, the amount of radiation dose that the patients received get increased, so that the exposure condition has to be thoroughly considered.

Environmental tobacco smoke exposure among non-smoking waiters: measurement of expired carbon monoxide levels

Directory of Open Access Journals (Sweden)

Ronaldo Laranjeira

2000-07-01

Full Text Available CONTEXT: Exposure to environmental tobacco smoke is a health risk that is of concern to patrons and of particular concern to employees of restaurants and bars. OBJECTIVE: To assess environmental tobacco smoke exposure (using expired carbon monoxide levels in non-smoking waiters before and after a normal day's shift and to compare pre-exposure levels with non-smoking medical students. DESIGN: An observational study. SETTING: Restaurants with more than 50 tables or 100 places in São Paulo. SUBJECTS: 100 non-smoking restaurant waiters and 100 non-smoking medical students in São Paulo, Brazil. MAIN MEASUREMENTS: Levels of expired carbon monoxide, measured with a Smokerlyser (Bedfont EC 50 Scientific, before and after a normal day's work. RESULTS: Waiters' pre-exposure expired carbon monoxide levels were similar to those of medical students, but after a mean of 9 hours exposure in the workplace, median levels more than doubled (2.0 ppm vs. 5.0 ppm, P <0.001. Post-exposure carbon monoxide levels were correlated with the number of tables available for smokers (Kendall's tau = 0.2, P <0.0001. CONCLUSIONS: Exposure to environmental tobacco smoke is the most likely explanation for the increase in carbon monoxide levels among these non-smoking waiters. These findings can be used to inform the ongoing public health debate on passive smoking.

International comparison. High-precision comparison of voltages generated by SINIS and SIS Josephson junction arrays at the 10 mV level

Energy Technology Data Exchange (ETDEWEB)

Karpov, O.V.; Koutovoi, V.D.; Sherstobitov, S.V. [Institute for Physical-Technical and Radiotechnical Measurements, VNIIFTRI, Gostandart of Russia, Mendeleevo, Moscow Region (Russian Federation); Niemeyer, J. [Physikalisch-Technische Bundesanstalt, PTB, Braunschweig (Germany)

2001-07-01

A high-precision comparison of dc voltages generated by a 10 GHz SINIS (superconductor/insulator/normal/insulator/superconductor) Josephson non-hysteretic junction array and a 70 GHz SIS (superconductor/insulator/superconductor) Josephson junction array is described. The paper also describes a method of minimizing the Type A measurement uncertainty. The measurements were carried out at the 10 mV level. The agreement between both output voltages was determined to 0.2 nV with a Type A uncertainty of 0.5 nV. (authors)

Suppressing voltage transients in high voltage power supplies

International Nuclear Information System (INIS)

Lickel, K.F.; Stonebank, R.

1979-01-01

A high voltage power supply for an X-ray tubes includes voltage adjusting means, a high voltage transformer, switch means connected to make and interrupt the primary current of the transformer, and over-voltage suppression means to suppress the voltage transient produced when the current is switched on. In order to reduce the power losses in the suppression means, an impedance is connected in the transformer primary circuit on operation of the switch means and is subsequently short-circuited by a switch controlled by a timer after a period which is automatically adjusted to the duration of the transient overvoltage. (U.K.)

Accommodating brightness and exposure levels in densitometry of stained polyacrylamide electrophoresis gels

International Nuclear Information System (INIS)

Tan, Han Yen; Ng, Tuck Wah; Liew, Oi Wah

2010-01-01

Flatbed scanner densitometers can be operated under various illumination and recording exposure levels. In this work, we show that optical density measurement accuracy, sensitivity, and stability of stained polyacrylamide electrophoresis gel densitometry are crucially dependent on these two factors (brightness and exposure level), notwithstanding that the source is monochromatic, spatially uniform, and the measurements are made using an accurately calibrated step wedge in tandem. We further outline a method to accommodate the intensity deviations over a range of illumination and exposure levels in order to maintain sensitivity and repeatability in the computed optical densities. Comparisons were also made with results from a commercial densitometer.

Effect of Short-term 900 MHz low level electromagnetic radiation exposure on blood serotonin and glutamate levels.

Science.gov (United States)

Eris, A H; Kiziltan, H S; Meral, I; Genc, H; Trabzon, M; Seyithanoglu, H; Yagci, B; Uysal, O

2015-01-01

Long term exposure to low level electromagnetic radiation (LLER) by using cellular phones causes serious health problems. Ten male Wistar Albino rats were anesthetized 30 min before the LLER exposure, 0.5 ml blood was taken from the tail vein of rats in order to determine control values. Rats were grouped by three and placed on a plexi-glass flat. A fixed equivalent frequency emitter device was used. A sign to be an electromagnetic field 15.14 V/m (608 mW/m(2)) in strength in the head region with 100 kHz FM modulation at 900 MHz was applied to the animals. After calculating the ideal position for the device, electromagnetic LLER energy was applied for 45 minutes from a distance to be equal with energy transmitted by a mobile phone from a 0.5-1 cm distance to their head regions. After 1.5 hours and before the rats awoke, 0.5 ml of blood was taken from the tail veins in order to determine the treatment values. Plasma 5-HT and glutamate levels were measured by enzyme immunoassay (EIA) using commercial kits. It was found that a single 45 min of LLER exposure increased the blood 5-HT level significantly, but did not change the glutamate level of rats. It was concluded that even a single 45 min of LLER exposure may produce an increase in 5-HT level without changing the blood glutamate level. Increased 5-HT level may lead to a retarded learning and a deficit in spatial memory (Tab. 2, Fig. 2, Ref. 24).

Benzene metabolite levels in blood and bone marrow of B6C3F{sub 1} mice after low-level exposure

Energy Technology Data Exchange (ETDEWEB)

Bechtold, W.E.; Strunk, M.R.; Thornton-Manning, J.R. [and others

1995-12-01

Studies at the Inhalation Toxicology Research Institute (ITRI) have explored the species-specific uptake and metabolism of benzene. Results have shown that metabolism is dependent on both dose and route of administration. Of particular interest were shifts in the major metabolic pathways as a function of exposure concentration. In these studies, B6C3F{sub 1} mice were exposed to increasing levels of benzene by either gavage or inhalation. As benzene internal dose increased, the relative amounts of muconic acid and hydroquinone decreased. In contrast, the relative amount of catechol increased with increasing exposure. These results show that the relative levels of toxic metabolites are a function of exposure level. Based on these results and assuming a linear relationship between exposure concentration and levels of bone marrow metabolites, it would be difficult to detect an elevation of any phenolic metabolites above background after occupational exposures to the OSHA Permissible Exposure Limit of 1 ppm benzene.

Airborne exposure and soil levels associated with lead abatement of a steel tank.

Science.gov (United States)

Lange, John H

2002-02-01

This study reports on airborne exposure levels and soil concentrations of lead in regard to abatement of a steel structure (water tank). The tank was de-leaded by abrasive sand blasting. The ball of the tank had a lead surface level that exceeded the Environmental Protection Agency (EPA) definition of lead-based paint (LBP) (0.5% lead), but paint on stem and base was below this criterion. Personal and area airborne samples were collected during different activities of lead abatement of the tank. Summary results suggest during abrasive blasting of ball and stem/base personal exposure levels, as reported with arithmetic and geometric means, exceed the Occupational Safety and Health Administration (OSHA) permissible exposure limit (50 microg/m3). Highest personal exposure (occupational exposure) was associated with blasting of ball. Distribution of airborne and soil samples suggest non-normality and is best represented by a logarithmic form. Geometric standard deviations for air and soil lead support a non-normal distribution. Outlying values were found for personal and area air samples. Exposure levels associated with blasting stem/base section of tank support OSHA's policy requiring air monitoring of work at levels below the criterion established by EPA in identifying LBP. Area samples were statistically lower than personal samples associated with blasting ball and stem/base of tank. Exposure data suggest that workers performing abatement on steel structures have elevated lead exposure from surface lead. Respirator protection requirements are discussed. Soil lead concentration was suggested to decrease as distance increased from tank. Soil lead is suggested to be a result of deposition from LBP on tank surface. Minimal efforts were required to reduce average lead soil levels below EPA's upper acceptable criterion (1200 ppm Pb).

Noninvasive method for the calibration of the peak voltage (kVp) meters

International Nuclear Information System (INIS)

Macedo, E.M.; Navarro, M.V.T.; Pereira, L.; Garcia, I.F.M.; Navarro, V.C.C.

2015-01-01

Quality control in diagnostic radiology is one of the mechanisms that minimize radiation exposure, and the measurement of tube voltage is one of the main test in these procedures. So, the calibration of non-invasive tube voltage meters is essential to maintain the metrological reliability of quality control tests. Thus, this work describes the implementation of the calibration methodology of the quantity tube peak voltage by the substitution method, using non-invasive standard meter, at LABPROSAUD-IFBA. The results showed great performance and when compared with calibrations by invasive methods, showed maximum difference of 4%, contemplated in the uncertainty ranges of the calibrations. (author)

Stabilization of Voltage Parameters of Induction Generator Excited by a Voltage Inverter

Directory of Open Access Journals (Sweden)

Padalko D.A.

2017-12-01

Full Text Available The article reveals the operational aspects of induction generator. Methods for stabilization of induction generator (IG parameters under inverter excitation are investigated. The study was carried out using mathematical description and simulation modeling in MATLAB Simulink. The paper provides analysis of causes of generated voltage amplitude and frequency displacement when the loading condition and the rate vary. Due to the parametric resonance nature of IG self-excitation, the author introduces the expression that allows estimating the capacitor capacitance required to maintain the generation process, depending on the rotor speed of electric machine, load nature and rate. Based on the studies, it was proved that it is possible to stabilize the IG voltage parameters by maintaining the magnetizing circuit inductance Lm at the constant level., and realizing a control law close to U/f = const. The study proves that using the inverter together with the voltage regulator allows ensuring the quality of electricity corresponding to modern standards. The necessity of problem solving of the required quality of the voltage by the harmonic component for the exciter - inverter with PWM is shown. The prospects of the power generation system based on induction machine (IM with a semiconductor frequency converter, which serves as an adjustable supplier of capacitive current for IM for autonomous objects, are substantiated. The use of semiconductor frequency converters makes it possible to provide high stability of the output voltage parameters and good speed of the mechatronic generation system with an asynchronous machine.

Occupational exposure levels of bioaerosol components are associated with serum levels of the acute phase protein Serum Amyloid A in greenhouse workers

DEFF Research Database (Denmark)

Madsen, Anne Mette; Thilsing, Trine; Bælum, Jesper

2016-01-01

to elevated levels of bioaerosols. The objective of this study is to assess whether greenhouse workers personal exposure to bioaerosol components was associated with serum levels of the acute phase proteins Serum Amyloid A (SAA) and C-reactive protein (CRP). METHODS: SAA and CRP levels were determined......-glucan. RESULTS: Serum levels of SAA and CRP were not significantly different in greenhouse workers and a reference group, or on the two work days. In a mixed model, SAA levels were positively associated with endotoxin exposure levels (p = 0.0007). Results for fungi were not clear. CRP levels were positively...... associated with endotoxin exposures (p = 0.022). Furthermore, when workers were categorized into three groups based on SAA and CRP serum levels endotoxin exposure was highest in the group with the highest SAA levels and in the group with middle and highest CRP levels. SAA and CRP levels were elevated...

Improving transition voltage spectroscopy of molecular junctions

DEFF Research Database (Denmark)

Markussen, Troels; Chen, Jingzhe; Thygesen, Kristian Sommer

2011-01-01

Transition voltage spectroscopy (TVS) is a promising spectroscopic tool for molecular junctions. The principles in TVS is to find the minimum on a Fowler-Nordheim plot where ln(I/V2) is plotted against 1/V and relate the voltage at the minimum Vmin to the closest molecular level. Importantly, Vmin...

Subcell Light Current-Voltage Characterization of Irradiated Multijunction Solar Cell

Directory of Open Access Journals (Sweden)

Walker Don

2017-01-01

Full Text Available The degradation of individual subcell J-V parameters, such as short circuit current, open circuit voltage, fill factor, and power of a GaInP/GaInAs/Ge triple junction solar cell by 1 MeV electrons were derived utilizing the spectral reciprocity relation between electroluminescence and external quantum efficiency. After exposure to a fluence of 1 × 1015 1 MeV electrons, it was observed that up to 67% of the voltage loss is from the middle, GaInAs subcell. Also, the dark saturation current of the Ge and GaInAs subcells increased but a simultaneous decrease in ideality factor caused a reduction of the open circuit voltage. The reduced ideality factor further indicates a change in the primary recombination mechanism.

Selective compensation of voltage harmonics in grid-connected microgrids

DEFF Research Database (Denmark)

Savaghebi, Mehdi; Vasquez, Juan Carlos; Jalilian, Alireza

2013-01-01

In this paper, a novel approach is proposed for selective compensation of main voltage harmonics in a grid-connected microgrid. The aim of compensation is to provide a high voltage quality at the point of common coupling (PCC). PCC voltage quality is of great importance due to sensitive loads tha...... to an acceptable level....

Compatibility of automatic exposure control with new screen phosphors in diagnostic roentgenography

International Nuclear Information System (INIS)

Mulvaney, J.A.

1982-01-01

Automatic exposure control systems are used in diagnostic roentgenography to obtain proper film density for a variety of patient examinations and roentgenographic techniques. Most automatic exposure control systems have been designed for use with par speed, calcium tungstate intensifying screens. The use of screens with faster speeds and new phosphor materials has put extreme demands on present systems. The performance of a representative automatic exposure control system is investigated to determine its ability to maintain constant film density over a wide range of x-ray tube voltages and acrylic phantom thicknesses with four different intensifying screen phosphors. The effects of x-ray energy dependence, generator switching time and stored change are investigated. The system is able to maintain film density to within plus or minus 0.2 optical density units for techniques representing adult patients. A single nonadjustable tube voltage compensation circuit is adequate for the four different screen phosphors for x-ray tube voltages above sixty peak kilovolts. For techniques representing pediatric patients at high x-ray tube voltages, excess film density occurs due to stored charge in the transformer and high-voltage cables. An anticipation circuit in the automatic exposure control circuit can be modified to correct for stored charge effects. In a seperate experiment the energy dependence of three different ionization chamber detectors used in automatic exposure control systems is compared directly with the energy dependence of three different screen phosphors. The data on detector sensitivity and screen speed are combined to predict the best tube voltage compensation for each combination of screen and detector

Design and Implementation of a High-Voltage Generator with Output Voltage Control for Vehicle ER Shock-Absorber Applications

Directory of Open Access Journals (Sweden)

Chih-Lung Shen

2013-01-01

Full Text Available A self-oscillating high-voltage generator is proposed to supply voltage for a suspension system in order to control the damping force of an electrorheological (ER fluid shock absorber. By controlling the output voltage level of the generator, the damping force in the ER fluid shock absorber can be adjusted immediately. The shock absorber is part of the suspension system. The high-voltage generator drives a power transistor based on self-excited oscillation, which converts dc to ac. A high-frequency transformer with high turns ratio is used to increase the voltage. In addition, the system uses the car battery as dc power supply. By regulating the duty cycle of the main switch in the buck converter, the output voltage of the buck converter can be linearly adjusted so as to obtain a specific high voltage for ER. The driving system is self-excited; that is, no additional external driving circuit is required. Thus, it reduces cost and simplifies system structure. A prototype version of the actual product is studied to measure and evaluate the key waveforms. The feasibility of the proposed system is verified based on experimental results.

Low-voltage electricity-induced lung injury.

Science.gov (United States)

Truong, Thai; Le, Thuong Vu; Smith, David L; Kantrow, Stephen P; Tran, Van Ngoc

2018-02-01

We report a case of bilateral pulmonary infiltrates and haemoptysis following low-voltage electricity exposure in an agricultural worker. A 58-year-old man standing in water reached for an electric watering machine and sustained an exposure to 220 V circuit for an uncertain duration. The electricity was turned off by another worker, and the patient was asymptomatic for the next 10 h until he developed haemoptysis. A chest radiograph demonstrated bilateral infiltrates, and chest computed tomography (CT) revealed ground-glass opacities with interstitial thickening. Evaluations, including electrocardiogram, serum troponin, N-terminal pro-B-type natriuretic peptide (NT-pro BNP), coagulation studies, and echocardiogram, found no abnormality. The patient was treated for suspected electricity-induced lung injury and bleeding with tranexamic acid and for rhabdomyolysis with volume resuscitation. He recovered with complete resolution of chest radiograph abnormalities by Day 7. This is the first reported case of bilateral lung oedema and/or injury after electricity exposure without cardiac arrest.

Company-level, semi-quantitative assessment of occupational styrene exposure when individual data are not available.

Science.gov (United States)

Kolstad, Henrik A; Sønderskov, Jette; Burstyn, Igor

2005-03-01

In epidemiological research, self-reported information about determinants and levels of occupational exposures is difficult to obtain, especially if the disease under study has a high mortality rate or follow-up has exceeded several years. In this paper, we present a semi-quantitative exposure assessment strategy for nested case-control studies of styrene exposure among workers of the Danish reinforced plastics industry when no information on job title, task or other indicators of individual exposure were readily available from cases and controls. The strategy takes advantage of the variability in styrene exposure level and styrene exposure probability across companies. The study comprised 1522 cases of selected malignancies and neurodegenerative diseases and controls employed in 230 reinforced plastics companies and other related industries. Between 1960 and 1996, 3057 measurements of styrene exposure level obtained from 191 companies, were identified. Mixed effects models were used to estimate expected styrene exposure levels by production characteristics for all companies. Styrene exposure probability within each company was estimated for all but three cases and controls from the fraction of laminators, which was reported by a sample of 945 living colleagues of the cases and controls and by employers and dealers of plastic raw materials. The estimates were validated from a subset of 427 living cases and controls that reported their own work as laminators in the industry. We computed styrene exposure scores that integrated estimated styrene exposure level and styrene exposure probability. Product (boats), process (hand and spray lamination) and calendar year period were the major determinants of styrene exposure level. Within-company styrene exposure variability increased by calendar year and was accounted for when computing the styrene exposure scores. Exposure probability estimates based on colleagues' reports showed the highest predictive values in the

Statistical characteristics of transient enclosure voltage in ultra-high-voltage gas-insulated switchgear

Science.gov (United States)

Cai, Yuanji; Guan, Yonggang; Liu, Weidong

2017-06-01

Transient enclosure voltage (TEV), which is a phenomenon induced by the inner dielectric breakdown of SF6 during disconnector operations in a gas-insulated switchgear (GIS), may cause issues relating to shock hazard and electromagnetic interference to secondary equipment. This is a critical factor regarding the electromagnetic compatibility of ultra-high-voltage (UHV) substations. In this paper, the statistical characteristics of TEV at UHV level are collected from field experiments, and are analyzed and compared to those from a repeated strike process. The TEV waveforms during disconnector operations are recorded by a self-developed measurement system first. Then, statistical characteristics, such as the pulse number, duration of pulses, frequency components, magnitude and single pulse duration, are extracted. The transmission line theory is introduced to analyze the TEV and is validated by the experimental results. Finally, the relationship between the TEV and the repeated strike process is analyzed. This proves that the pulse voltage of the TEV is proportional to the corresponding breakdown voltage. The results contribute to the definition of the standard testing waveform of the TEV, and can aid the protection of electronic devices in substations by minimizing the threat of this phenomenon.

Power conditioning using dynamic voltage restorers under different voltage sag types.

Science.gov (United States)

Saeed, Ahmed M; Abdel Aleem, Shady H E; Ibrahim, Ahmed M; Balci, Murat E; El-Zahab, Essam E A

2016-01-01

Voltage sags can be symmetrical or unsymmetrical depending on the causes of the sag. At the present time, one of the most common procedures for mitigating voltage sags is by the use of dynamic voltage restorers (DVRs). By definition, a DVR is a controlled voltage source inserted between the network and a sensitive load through a booster transformer injecting voltage into the network in order to correct any disturbance affecting a sensitive load voltage. In this paper, modelling of DVR for voltage correction using MatLab software is presented. The performance of the device under different voltage sag types is described, where the voltage sag types are introduced using the different types of short-circuit faults included in the environment of the MatLab/Simulink package. The robustness of the proposed device is evaluated using the common voltage sag indices, while taking into account voltage and current unbalance percentages, where maintaining the total harmonic distortion percentage of the load voltage within a specified range is desired. Finally, several simulation results are shown in order to highlight that the DVR is capable of effective correction of the voltage sag while minimizing the grid voltage unbalance and distortion, regardless of the fault type.

Radiation exposure and dose evaluation in intraoral dental radiology

International Nuclear Information System (INIS)

Poppe, B.; Looe, H. K.; Pfaffenberger, A.; Eenboom, F.; Chofor, N.; Sering, M.; Ruehmann, A.; Poplawski, A.; Willborn, K.

2007-01-01

In this study, dose area product measurements have been performed to propose diagnostic reference levels (DRLs) in intraoral dental radiology. Measurements were carried out at 60 X-ray units for all types of intraoral examinations performed in clinical routine. The third quartile values calculated range from 26.2 to 87.0 mGy cm 2 . The results showed that there exists a large difference between the patient exposures among different dental facilities. It was also observed that dentists working with faster film type or higher tube voltage are not always associated with lower exposure. The study demonstrated the necessity to have the DRLs laid out as guidelines in dental radiology. (authors)

A recommended approach for calculating degraded voltage relay setpoints for nuclear generating stations

International Nuclear Information System (INIS)

Jancauskas, J.R.

1994-01-01

The purpose of degrading voltage relays (DVRs) is to ensure that adequate voltage is available to operate all Class 1E loads at all voltage distribution levels. Should voltage drop below the setpoint of the DVRs, the Class 1E power system is disconnected from its supply and resequenced onto the diesel generators in order to restore system voltages to acceptable levels. These relays represent one of the two levels of voltage protection required for the onsite power system. Determining the proper setpoint for degraded voltage relays in nuclear generating stations is a complex task which requires a complete understanding of the Class 1E power distribution system. Despite the importance of degraded voltage relay setpoint calculations, most of the available references only give clues on how not to set these relays rather than provide guidance on how to determine the appropriate setpoint. This paper presents an approach for performing these calculations which attempts to ensure that all of the relevant design issues are addressed

Elevated blood lead levels from exposure via a radiator workshop.

Science.gov (United States)

Treble, R G; Thompson, T S; Morton, D N

1998-04-01

Elevated lead levels were discovered in blood samples collected from family members where both the father and the mother worked in a radiator repair workshop. The father and mother were found to have blood lead levels of 2.0 and 0.5 mumol/L (41.7 and 10.4 micrograms/dL), respectively. The father's blood lead level was just below the Canadian occupational health and safety intervention level (2.5 mumol/L or 52.1 micrograms/dL). The two children had blood lead levels of 1.0 and 0.8 mumol/L (20.8 and 16.7 micrograms/dL), both of which are in excess of the recommended guideline for intervention in the case of children (0.5 mumol/L or 10.4 micrograms/dL). The exposure of the two children was possibly due to a combination of pathways including exposure at the workshop itself during visits and also the transportation of lead-containing dust to the home environment.

Quality and Dose Optimized CT Trauma Protocol - Recommendation from a University Level-I Trauma Center.

Science.gov (United States)

Kahn, Johannes; Kaul, David; Böning, Georg; Rotzinger, Roman; Freyhardt, Patrick; Schwabe, Philipp; Maurer, Martin H; Renz, Diane Miriam; Streitparth, Florian

2017-09-01

Purpose  As a supra-regional level-I trauma center, we evaluated computed tomography (CT) acquisitions of polytraumatized patients for quality and dose optimization purposes. Adapted statistical iterative reconstruction [(AS)IR] levels, tube voltage reduction as well as a split-bolus contrast agent (CA) protocol were applied. Materials and Methods  61 patients were split into 3 different groups that differed with respect to tube voltage (120 - 140 kVp) and level of applied ASIR reconstruction (ASIR 20 - 50 %). The CT protocol included a native acquisition of the head followed by a single contrast-enhanced acquisition of the whole body (64-MSCT). CA (350 mg/ml iodine) was administered as a split bolus injection of 100 ml (2 ml/s), 20 ml NaCl (1 ml/s), 60 ml (4 ml/s), 40 ml NaCl (4 ml/s) with a scan delay of 85 s to detect injuries of both the arterial system and parenchymal organs in a single acquisition. Both the quantitative (SNR/CNR) and qualitative (5-point Likert scale) image quality was evaluated in parenchymal organs that are often injured in trauma patients. Radiation exposure was assessed. Results  The use of IR combined with a reduction of tube voltage resulted in good qualitative and quantitative image quality and a significant reduction in radiation exposure of more than 40 % (DLP 1087 vs. 647 mGyxcm). Image quality could be improved due to a dedicated protocol that included different levels of IR adapted to different slice thicknesses, kernels and the examined area for the evaluation of head, lung, body and bone injury patterns. In synopsis of our results, we recommend the implementation of a polytrauma protocol with a tube voltage of 120 kVp and the following IR levels: cCT 5mm: ASIR 20; cCT 0.625 mm: ASIR 40; lung 2.5 mm: ASIR 30, body 5 mm: ASIR 40; body 1.25 mm: ASIR 50; body 0.625 mm: ASIR 0. Conclusion  A dedicated adaptation of the CT trauma protocol (level of reduction of tube voltage and of IR

Mitigation of voltage sags in the distribution system with dynamic voltage restorer

International Nuclear Information System (INIS)

Viglas, D.; Belan, A.

2012-01-01

Dynamic voltage restorer is a custom power device that is used to improve voltage sags or swells in electrical distribution system. The components of the Dynamic Voltage Restorer consist of injection transformers, voltage source inverter, passive filters and energy storage. The main function of the Dynamic voltage restorer is used to inject three phase voltage in series and in synchronism with the grid voltages in order to compensate voltage disturbances. This article deals with mitigation of voltage sags caused by three-phase short circuit. Dynamic voltage restorer is modelled in MATLAB/Simulink. (Authors)

Exposure to low levels of hydrogen sulfide : symptoms, sensory function, and cognitive performance

International Nuclear Information System (INIS)

Fiedler, N.; Kipen, H.; Lioy, P.; Zhang, J.; Weisel, C.

2003-01-01

Petroleum refineries, kraft paper mills, and coke ovens are some of the sources of hydrogen sulfide exposure. In 1987, the World Health Organization (WHO) recommended an ambient exposure standard of .003 ppm for odor and .01 ppm for eye irritation. In communities with high exposure levels, health effects have been documented as being headaches, eye and nasal symptoms, coughs, breathlessness and decreased psychomotor performance. Refinery workers in some jurisdictions around the world have been subjected to higher exposure levels. This report presents results of clinical studies on the neurobehavioral effects in rats. The tasks of memory and learning in rats parallels those in humans. A pilot exposure study examined the health effects of controlled exposures to 3 concentrations of hydrogen sulfide (.05, .50, and 5 ppm). It was concluded that changes in neurobehavioral measurements can be directly associated with exposure and dose-response. 25 figs

Calibration of the ISOLDE acceleration voltage using a high-precision voltage divider and applying collinear fast beam laser spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Krieger, A., E-mail: kriegea@uni-mainz.d [Institut fuer Kernchemie, Johannes Gutenberg, Universitaet Mainz, Fritz-Strassmann-Weg 2, 55128 Mainz (Germany); Geppert, Ch. [Institut fuer Kernchemie, Johannes Gutenberg, Universitaet Mainz, Fritz-Strassmann-Weg 2, 55128 Mainz (Germany); GSI Helmholtzzentrum fuer Schwerionenforschung, 64291 Darmstadt (Germany); Catherall, R. [CERN, CH-1211 Geneve 23 (Switzerland); Hochschulz, F. [Institut fuer Kernphysik, Universitaet Muenster, 48149 Muenster (Germany); Kraemer, J.; Neugart, R. [Institut fuer Kernchemie, Johannes Gutenberg, Universitaet Mainz, Fritz-Strassmann-Weg 2, 55128 Mainz (Germany); Rosendahl, S. [Institut fuer Kernphysik, Universitaet Muenster, 48149 Muenster (Germany); Schipper, J.; Siesling, E. [CERN, CH-1211 Geneve 23 (Switzerland); Weinheimer, Ch. [Institut fuer Kernphysik, Universitaet Muenster, 48149 Muenster (Germany); Yordanov, D.T. [Max-Planck-Institut fuer Kernphysik, 69117 Heidelberg (Germany); Noertershaeuser, W. [Institut fuer Kernchemie, Johannes Gutenberg, Universitaet Mainz, Fritz-Strassmann-Weg 2, 55128 Mainz (Germany); GSI Helmholtzzentrum fuer Schwerionenforschung, 64291 Darmstadt (Germany)

2011-03-11

A high-voltage divider with accuracy at the ppm level and collinear laser spectroscopy were used to calibrate the high-voltage installation at the radioactive ion beam facility ISOLDE at CERN. The accurate knowledge of this voltage is particularly important for collinear laser spectroscopy measurements. Beam velocity measurements using frequency-comb based collinear laser spectroscopy agree with the new calibration. Applying this, one obtains consistent results for isotope shifts of stable magnesium isotopes measured using collinear spectroscopy and laser spectroscopy on laser-cooled ions in a trap. The long-term stability and the transient behavior during recovery from a voltage dropout were investigated for the different power supplies currently applied at ISOLDE.

Voltage regulating circuit

NARCIS (Netherlands)

2005-01-01

A voltage regulating circuit comprising a rectifier (2) for receiving an AC voltage (Vmains) and for generating a rectified AC voltage (vrec), and a capacitor (3) connected in parallel with said rectified AC voltage for providing a DC voltage (VDC) over a load (5), characterized by a unidirectional

Comparison of three-phase three-level voltage source inverter with intermediate dc–dc boost converter and quasi-Z-source inverter

DEFF Research Database (Denmark)

Panfilov, Dmitry; Husev, Oleksandr; Blaabjerg, Frede

2016-01-01

This study compares a three-phase three-level voltage source inverter with an intermediate dc-dc boost converter and a quasi-Z-source inverter in terms of passive elements values and dimensions, semiconductor stresses, and overall efficiency. A comparative analysis was conducted with relative...

Occupational exposure to diesel engine exhaust and serum cytokine levels.

Science.gov (United States)

Dai, Yufei; Ren, Dianzhi; Bassig, Bryan A; Vermeulen, Roel; Hu, Wei; Niu, Yong; Duan, Huawei; Ye, Meng; Meng, Tao; Xu, Jun; Bin, Ping; Shen, Meili; Yang, Jufang; Fu, Wei; Meliefste, Kees; Silverman, Debra; Rothman, Nathaniel; Lan, Qing; Zheng, Yuxin

2018-03-01

The International Agency for Research on Cancer has classified diesel engine exhaust (DEE) as a human lung carcinogen. Given that inflammation is suspected to be an important underlying mechanism of lung carcinogenesis, we evaluated the relationship between DEE exposure and the inflammatory response using data from a cross-sectional molecular epidemiology study of 41 diesel engine testing workers and 46 unexposed controls. Repeated personal exposure measurements of PM 2.5 and other DEE constituents were taken for the diesel engine testing workers before blood collection. Serum levels of six inflammatory biomarkers including interleukin (IL)-1, IL-6, IL-8, tumor necrosis factor (TNF)-α, macrophage inflammatory protein (MIP)-1β, and monocyte chemotactic protein (MCP)-1 were analyzed in all subjects. Compared to unexposed controls, concentrations of MIP-1β were significantly reduced by ∼37% in DEE exposed workers (P 397 µg/m 3 ) compared to unexposed controls. Further, significant inverse exposure-response relationships for IL-8 and MCP-1 were also found in relation to increasing PM 2.5 levels among the DEE exposed workers. Given that IL-8, MIP-1β, and MCP-1 are chemokines that play important roles in recruitment of immunocompetent cells for immune defense and tumor cell clearance, the observed lower levels of these markers with increasing PM 2.5 exposure may provide insight into the mechanism by which DEE promotes lung cancer. Environ. Mol. Mutagen. 59:144-150, 2018. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

HELLE: Health Effects of Low Level Exposures/ Gezondheidseffecten van lage blootstellingniveaus [International workshop: Influence of low level exposures to chemicals and radiation on human and ecological health

Energy Technology Data Exchange (ETDEWEB)

Schoten, Eert

1998-11-26

The Health Council is closely involved in establishing the scientific foundation of exposure limits for substances and radiation in order to protect public health. Through the years, the Council has contributed to the formulation of principles and procedures, both for carcinogenic and for noncarcinogenic agents. As a rule, the discussion with regard to the derivation of health-based recommended exposure limits centers around the appropriateness of extrapolation methods (What can be inferred from data on high exposure levels and on experimental animals?). Generally speaking, there is a lack of direct information on the health effects of low levels of exposure. Effects at these levels cannot usually be detected by means of traditional animal experiments or epidemiological research. The capacity of these analytical instruments to distinguish between ''signal'' and ''noise'' is inadequate in most cases. Annex B of this report contains a brief outline of the difficulties and the established methods for tackling this problem. In spite of this, the hope exists that the posited weak signals, if they are indeed present, can be detected by other means. The search will have to take place on a deeper level. In other words, effort must be made to discover what occurs at underlying levels of biological organization when organisms are exposed to low doses of radiation or substances. Molecular and cell biology provide various methods and techniques which give an insight into the processes within the cell. This results in an increase in the knowledge about the molecular and cellular effects of exposure to agents, or stated differently, the working mechanisms which form the basis of the health effects. Last year, the Health Council considered that the time was ripe to take stock of the state of knowledge in this field. To this end, an international working conference was held from 19 to 21 October 1997, entitled ''Health Effects of

The high voltage divider - a tool for comparison of measurement equipment in diagnostic radiology

International Nuclear Information System (INIS)

Slavchev, A.; Litchev, A.; Constantinov, B.

2004-01-01

The high voltage divider (HVD) is designed for control and analysis of the characteristics of the X-ray generator. The low voltage analogous signals produced by the divider are proportional to the high voltage (kVp) applied to the x-ray tube by a ratio 1:1000 or 1:10000 and can be measured with external test devices like storage oscilloscope (or digital multimeter). The exposure duration and the wave form may be visualized, too. Apart of this invasive way the high voltage also may be measured non-invasively by means of appropriate devices as well as indirectly through calculations. Since the invasive method of measurement with the high voltage divider is distinguished by a high accuracy, it may be utilized as an effective tool for calibration of different devices and for comparison of the measurement methods. (authors)

Legal recourse for damages suffered from low-level radiation exposure

International Nuclear Information System (INIS)

Pesto-Edwards, M.M.

1984-01-01

In the past few years several events involving toxic substances have received widespread coverage by the media, thereby altering an already aware population to the hazards of exposure to toxic agents. Incidents such as Three Mile Islane, Love Canal, and Hemlock, Michigan, the exposure plight of veterans to radiation at the Nevada Test Site and to Agent Orange in Vietnam, and to the exposure of factory workers to asbestos, have been highly publicized. In part because of this publicity, the emphasis of the 1970's on controlling water and air pollution has been shifting slowly during the 1980s to the of control of hazardous waste pollution. Despite this shifting emphasis, legislative and judicial systems have been slow to respond. Few remedies are available to real and imagined victims of toxic substances. From a legal point of view, there is little difference between exposure to low levels of radiation and low levels of toxic chemicals. Both instances fall under the broader domain of environmental law. Depending on the circumstances, one instance might provide legal precedent for the other. This chapter presents examples drawn from both areas in order to illustrate current issues. The discussion is divided into four parts: (1) the common law tort theories that may be asserted when a plaintiff has suffered injury resulting from exposure to low-level radiation or other toxic substances; (2) the difficulties posed by the relief mechanisms rooted in traditional common law; (3) current federal legislation, along with its merits and shortcomings; and (4) solutions to the obstacles now faced by plaintiffs in attempting to recover their damages. Also discussed are suggested judicial and legislative solutions designed to remedy the damages caused to persons exposed to toxic wastes

Glutathione level after long-term occupational elemental mercury exposure

International Nuclear Information System (INIS)

Kobal, Alfred Bogomir; Prezelj, Marija; Horvat, Milena; Krsnik, Mladen; Gibicar, Darija; Osredkar, Josko

2008-01-01

Many in vitro and in vivo studies have elucidated the interaction of inorganic mercury (Hg) and glutathione. However, human studies are limited. In this study, we investigated the potential effects of remote long-term intermittent occupational elemental Hg vapour (Hg o ) exposure on erythrocyte glutathione levels and some antioxidative enzyme activities in ex-mercury miners in the period after exposure. The study included 49 ex-mercury miners divided into subgroups of 28 still active, Hg o -not-exposed miners and 21 elderly retired miners, and 41 controls, age-matched to the miners subgroup. The control workers were taken from 'mercury-free works'. Reduced glutathione (GSH) and oxidized disulphide glutathione (GSSG) concentrations in haemolysed erythrocytes were determined by capillary electrophoresis, while total glutathione (total GSH) and the GSH/GSSG ratio were calculated from the determined values. Catalase (CAT), glutathione peroxidase (GPx), and glutathione reductase (GR) activities in erythrocytes were measured using commercially available reagent kits, while urine Hg (U-Hg) concentrations were determined by cold vapour atomic absorption (CVAAS). No correlation of present U-Hg levels, GSH, GSSG, and antioxidative enzymes with remote occupational biological exposure indices were found. The mean CAT activity in miners and retired miners was significantly higher (p o could be an inductive and additive response to maintain the balance between GSH and antioxidative enzymes in interaction with the Hg body burden accumulated during remote occupational exposure, which does not represent a severely increased oxidative stress

Impact of distributed generators on the power loss and voltage profile of sub-transmission network

Directory of Open Access Journals (Sweden)

A.S.O. Ogunjuyigbe

2016-05-01

Full Text Available This paper presents the impact of distributed generator (DG on the power loss and voltage profile of sub-transmission network at different penetration levels (PLs. The various DG technologies are modeled based on their electrical output characteristics. Voltage profile index which allows a single value to represent how well the voltage matches the ideal value is developed. The index allows a fair comparison of the voltage profile obtained from different scenarios. The extent to which DGs affect power losses and voltage profile depend on the type of DG technology, PL and the location in which the DG is connected to the grid. The integration of DGs reduces power losses on the network, however, as the PL increases, the power losses begin to increase. A PL of 50–75% is achieved on 69 kV voltage level and 25–50% penetration on 13.8 kV voltage level without an increase in the power loss. Also more DG can be integrated into the network at point of common connection of higher voltage level compared to the low voltage level.

Consumer product exposures associated with urinary phthalate levels in pregnant women

Science.gov (United States)

Buckley, Jessie P.; Palmieri, Rachel T.; Matuszewski, Jeanine M.; Herring, Amy H.; Baird, Donna D.; Hartmann, Katherine E.; Hoppin, Jane A.

2012-01-01

Human phthalate exposure is ubiquitous, but little is known regarding predictors of urinary phthalate levels. To explore this, 50 pregnant women aged 18–38 years completed two questionnaires on potential phthalate exposures and provided a first morning void. Urine samples were analyzed for 12 phthalate metabolites. Associations with questionnaire items were evaluated via Wilcoxon tests and t-tests, and r-squared values were calculated in multiple linear regression models. Few measured factors were statistically significantly associated with phthalate levels. Individuals who used nail polish had higher levels of mono-butyl phthalate (p=0.048) than non-users. Mono-benzyl phthalate levels were higher among women who used eye makeup (p=0.034) or used makeup on a regular basis (p=0.004). Women who used cologne or perfume had higher levels of di-(2-ethylhexyl) phthalate metabolites. Household products, home flooring or paneling, and other personal care products were also associated with urinary phthalates. The proportion of variance in metabolite concentrations explained by questionnaire items ranged between 0.31 for mono-ethyl phthalate and 0.42 for mono-n-methyl phthalate. Although personal care product use may be an important predictor of urinary phthalate levels, most of the variability in phthalate exposure was not captured by our relatively comprehensive set of questionnaire items. PMID:22760436

Reliability of semiconductor and gas-filled diodes for over-voltage protection exposed to ionizing radiation

Directory of Open Access Journals (Sweden)

Stanković Koviljka

2009-01-01

Full Text Available The wide-spread use of semiconductor and gas-filled diodes for non-linear over-voltage protection results in a variety of possible working conditions. It is therefore essential to have a thorough insight into their reliability in exploitation environments which imply exposure to ionizing radiation. The aim of this paper is to investigate the influence of irradiation on over-voltage diode characteristics by exposing the diodes to californium-252 combined neutron/gamma radiation field. The irradiation of semiconductor over-voltage diodes causes severe degradation of their protection characteristics. On the other hand, gas-filled over-voltage diodes exhibit a temporal improvement of performance. The results are presented with the accompanying theoretical interpretations of the observed changes in over-voltage diode behaviour, based on the interaction of radiation with materials constituting the diodes.

Dose reduction in pulsed fluoroscopy by modifying the high-voltage pulse shape

International Nuclear Information System (INIS)

Sabau, M.N.; Phelps, G.

1988-01-01

This paper presents the dose reduction results in pulsed fluoroscopy by modifying the high-voltage pulse shape (HVPS). Since the HVPS in regular pulsed fluoroscopy has a long tail, the radiation pulse shape (RPS) is similar. Using specially designed circuitry in the high-voltage generator to produce a rectangular HVPS, and consequently a rectangular RPS, it was possible to obtain a reduction of up to 25% of patient exposure. This dose reduction obtained by cutting the long tail of RPS does not damage the image quality

Extension algorithm for generic low-voltage networks

Science.gov (United States)

Marwitz, S.; Olk, C.

2018-02-01

Distributed energy resources (DERs) are increasingly penetrating the energy system which is driven by climate and sustainability goals. These technologies are mostly connected to low- voltage electrical networks and change the demand and supply situation in these networks. This can cause critical network states. Network topologies vary significantly and depend on several conditions including geography, historical development, network design or number of network connections. In the past, only some of these aspects were taken into account when estimating the network investment needs for Germany on the low-voltage level. Typically, fixed network topologies are examined or a Monte Carlo approach is used to quantify the investment needs at this voltage level. Recent research has revealed that DERs differ substantially between rural, suburban and urban regions. The low-voltage network topologies have different design concepts in these regions, so that different network topologies have to be considered when assessing the need for network extensions and investments due to DERs. An extension algorithm is needed to calculate network extensions and investment needs for the different typologies of generic low-voltage networks. We therefore present a new algorithm, which is capable of calculating the extension for generic low-voltage networks of any given topology based on voltage range deviations and thermal overloads. The algorithm requires information about line and cable lengths, their topology and the network state only. We test the algorithm on a radial, a loop, and a heavily meshed network. Here we show that the algorithm functions for electrical networks with these topologies. We found that the algorithm is able to extend different networks efficiently by placing cables between network nodes. The main value of the algorithm is that it does not require any information about routes for additional cables or positions for additional substations when it comes to estimating

Application of physiologically based pharmacokinetic modeling in setting acute exposure guideline levels for methylene chloride.

NARCIS (Netherlands)

Bos, Peter Martinus Jozef; Zeilmaker, Marco Jacob; Eijkeren, Jan Cornelis Henri van

2006-01-01

Acute exposure guideline levels (AEGLs) are derived to protect the human population from adverse health effects in case of single exposure due to an accidental release of chemicals into the atmosphere. AEGLs are set at three different levels of increasing toxicity for exposure durations ranging from

Beyond voltage-gated ion channels: Voltage-operated membrane proteins and cellular processes.

Science.gov (United States)

Zhang, Jianping; Chen, Xingjuan; Xue, Yucong; Gamper, Nikita; Zhang, Xuan

2018-04-18

Voltage-gated ion channels were believed to be the only voltage-sensitive proteins in excitable (and some non-excitable) cells for a long time. Emerging evidence indicates that the voltage-operated model is shared by some other transmembrane proteins expressed in both excitable and non-excitable cells. In this review, we summarize current knowledge about voltage-operated proteins, which are not classic voltage-gated ion channels as well as the voltage-dependent processes in cells for which single voltage-sensitive proteins have yet to be identified. Particularly, we will focus on the following. (1) Voltage-sensitive phosphoinositide phosphatases (VSP) with four transmembrane segments homologous to the voltage sensor domain (VSD) of voltage-gated ion channels; VSPs are the first family of proteins, other than the voltage-gated ion channels, for which there is sufficient evidence for the existence of the VSD domain; (2) Voltage-gated proton channels comprising of a single voltage-sensing domain and lacking an identified pore domain; (3) G protein coupled receptors (GPCRs) that mediate the depolarization-evoked potentiation of Ca 2+ mobilization; (4) Plasma membrane (PM) depolarization-induced but Ca 2+ -independent exocytosis in neurons. (5) Voltage-dependent metabolism of phosphatidylinositol 4,5-bisphosphate (PtdIns[4,5]P 2 , PIP 2 ) in the PM. These recent discoveries expand our understanding of voltage-operated processes within cellular membranes. © 2018 Wiley Periodicals, Inc.

Planning aspects of ac extra high voltage lines

Energy Technology Data Exchange (ETDEWEB)

Engelhardt, H

1964-01-01

The technical points arising in any project for application of higher voltages on power grids in Europe are discussed. The cost aspects of two alternative ways of extending the voltage level of existing systems are discussed in detail. The short-circuit current in a high-power system with isolated or grounded neutral point and its relation to the mode of grounding is examined. For a transmission distance of 200 kVm, operating cost for each kWh transmitted are shown on curves for voltages of 220, 380 and 700 kV against transmitted energy. This shows that for any rated voltage there is a range of energy values which can be transmitted economically. Factors to be considered in maintaining, selecting or rejecting transformers and switchgear of other systems for higher voltage purposes are mentioned.

Neuroprotective effect of interleukin-6 regulation of voltage-gated Na+ channels of cortical neurons is time- and dose-dependent

Directory of Open Access Journals (Sweden)

Wei Xia

2015-01-01

Full Text Available Interleukin-6 has been shown to be involved in nerve injury and nerve regeneration, but the effects of long-term administration of high concentrations of interleukin-6 on neurons in the central nervous system is poorly understood. This study investigated the effects of 24 hour exposure of interleukin-6 on cortical neurons at various concentrations (0.1, 1, 5 and 10 ng/mL and the effects of 10 ng/mL interleukin-6 exposure to cortical neurons for various durations (2, 4, 8, 24 and 48 hours by studying voltage-gated Na + channels using a patch-clamp technique. Voltage-clamp recording results demonstrated that interleukin-6 suppressed Na + currents through its receptor in a time- and dose-dependent manner, but did not alter voltage-dependent activation and inactivation. Current-clamp recording results were consistent with voltage-clamp recording results. Interleukin-6 reduced the action potential amplitude of cortical neurons, but did not change the action potential threshold. The regulation of voltage-gated Na + channels in rat cortical neurons by interleukin-6 is time- and dose-dependent.

The Impact of Different Permissible Exposure Limits on Hearing Threshold Levels Beyond 25 dBA.

Science.gov (United States)

Sayapathi, Balachandar S; Su, Anselm Ting; Koh, David

2014-10-01

Development of noise-induced hearing loss is reliant on a few factors such as frequency, intensity, and duration of noise exposure. The occurrence of this occupational malady has doubled from 120 million to 250 million in a decade. Countries such as Malaysia, India, and the US have adopted 90 dBA as the permissible exposure limit. According to the US Occupational Safety and Health Administration (OSHA), the exposure limit for noise is 90 dBA, while that of the US National Institute of Occupational Safety and Health (NIOSH) is 85 dBA for 8 hours of noise exposure. This study aimed to assess the development of hearing threshold levels beyond 25 dBA on adoption of 85 dBA as the permissible exposure limit compared to 90 dBA. This is an intervention study done on two automobile factories. There were 203 employees exposed to noise levels beyond the action level. Hearing protection devices were distributed to reduce noise levels to a level between the permissible exposure limit and action level. The permissible exposure limits were 90 and 85 dBA in factories 1 and 2, respectively, while the action levels were 85 and 80 dBA, respectively. The hearing threshold levels of participants were measured at baseline and at first month of postshift exposure of noise. The outcome was measured by a manual audiometer. McNemar and chi-square tests were used in the statistical analysis. We found that hearing threshold levels of more than 25 dBA has changed significantly from pre-intervention to post-intervention among participants from both factories (3000 Hz for the right ear and 2000 Hz for the left ear). There was a statistically significant association between participants at 3000 Hz on the right ear at 'deteriorated' level ( χ² (1) = 4.08, φ = - 0.142, P = 0.043), whereas there was worsening of hearing threshold beyond 25 dBA among those embraced 90 dBA. The adoption of 85 dBA as the permissible exposure limit has preserved hearing threshold level among participants at 3000 Hz

Acute Exposure to Low-to-Moderate Carbon Dioxide Levels and Submariner Decision Making.

Science.gov (United States)

Rodeheffer, Christopher D; Chabal, Sarah; Clarke, John M; Fothergill, David M

2018-06-01

Submarines routinely operate with higher levels of ambient carbon dioxide (CO2) (i.e., 2000 - 5000 ppm) than what is typically considered normal (i.e., 400 - 600 ppm). Although significant cognitive impairments are rarely reported at these elevated CO2 levels, recent studies using the Strategic Management Simulation (SMS) test have found impairments in decision-making performance during acute CO2 exposure at levels as low as 1000 ppm. This is a potential concern for submarine operations, as personnel regularly make mission-critical decisions that affect the safety and efficiency of the vessel and its crew while exposed to similar levels of CO2. The objective of this study was to determine if submariner decision-making performance is impacted by acute exposure to levels of CO2 routinely present in the submarine atmosphere during sea patrols. Using a subject-blinded balanced design, 36 submarine-qualified sailors were randomly assigned to receive 1 of 3 CO2 exposure conditions (600, 2500, or 15,000 ppm). After a 45-min atmospheric acclimation period, participants completed an 80-min computer-administered SMS test as a measure of decision making. There were no significant differences for any of the nine SMS measures of decision making between the CO2 exposure conditions. In contrast to recent research demonstrating cognitive deficits on the SMS test in students and professional-grade office workers, we were unable to replicate this effect in a submariner population-even with acute CO2 exposures more than an order of magnitude greater than those used in previous studies that demonstrated such effects.Rodeheffer CD, Chabal S, Clarke JM, Fothergill DM. Acute exposure to low-to-moderate carbon dioxide levels and submariner decision making. Aerosp Med Hum Perform. 2018; 89(6):520-525.

Background radiation levels and medical exposure levels in Australia

International Nuclear Information System (INIS)

Webb, D.V.; Solomon, S.B.; Thomson, J.E.M.

1999-01-01

The average effective background dose received by the Australian population has been reassessed to be ∼1.5 millisievert (mSv) per year. Over half of this exposure arises from exposure from terrestrial radiation and cosmic rays, the remainder from radionuclides within the body and from inhalation of radon progeny. This background is to be compared with medical radiation, primarily diagnostic, which could add half as much again to the population exposure. This paper reviews research programmes carried out by the Australian Radiation Laboratory to study radiation exposure from natural background and from medical use. While the latter exposure is accepted to have a social benefit, there is a need to ensure that doses are no more than necessary to provide effective diagnosis and optimal treatment. Copyright (1999) Australasian Radiation Protection Society Inc

Bio-Inspired Carbon Monoxide Sensors with Voltage-Activated Sensitivity

KAUST Repository

Savagatrup, Suchol; Schroeder, Vera; He, Xin; Lin, Sibo; He, Maggie; Yassine, Omar; Salama, Khaled N.; Zhang, Xixiang; Swager, Timothy M.

2017-01-01

voltage offers a predicted extra dimension for sensing. Specifically, the sensors show a significant increase in sensitivity toward CO when negative gate voltage is applied. The dosimetric sensors are selective to ppm levels of CO and functional in air. UV

Methylene chloride exposure and carboxyhemoglobin levels in cabinetmakers

Science.gov (United States)

Banjoko, Sunny O.; Sridhar Mynapelli, K. C.; Ogunkola, Isiah O.; Masheyi, Olatunde O.

2007-01-01

Methylene chloride (MeCl2) is a clear colorless volatile sweet smelling lipophilic solvent used as a constituent of wood vanishes and paints. Human exposure is mainly due to inhalation and its biotransformation by the hepatic mixed function oxidases (MFO) leads to formation of carbon monoxide (CO). Simultaneous exposure to MeCl2 and increased ambient CO results in undesirably increased carboxyhemoglobin (COHb) formation, which predisposes to carboxyhemoglobinaemia with the central nervous system as the primary target organ of toxicity. In this study, ambient CO levels were determined using a CO personal monitor in different pasts of Ibadan Nigeria and work place microenvironment of 50 Cabinet makers (test group) and 50 volunteer (control) in non-furniture making occupations. Mann Whitney U and Kruskaal Wallis were the statistical methods of analysis used. Questionnaires were administered to both groups carboxyhaemoglobin levels were determined in venous blood drawn from individuals in the two groups by differential spectrophotometric method. Ambient CO levels in Ibadan were observed to be between 4 and 52 ppm with a mean of 20 ppm. Work environment CO levels were significantly higher in test subjects than controls at 5.2 ± 1.08 ppm and 2.08 ± 0.91 ppm respectively (P 0.05). It is therefore imperative to substitute MeCl2 for safer chemicals in wood vanish and paints and the use of protective gas masks and adequate ventilation should be mandatory whenever MeCl2 is used. PMID:21938216

Long-term exposure to low-level arsenic in drinking water and diabetes incidence

DEFF Research Database (Denmark)

Bräuner, Elvira Vaclavik; Nordsborg, Rikke Baastrup; Andersen, Zorana Jovanovic

2014-01-01

BACKGROUND: Established causes of diabetes do not fully explain the present epidemic. High-level arsenic exposure has been implicated in diabetes risk, but the effect of low-level arsenic exposure in drinking water remains unclear. OBJECTIVE: We sought to determine whether long-term exposure to low......-level arsenic in drinking water in Denmark is associated with an increased risk of diabetes using a large prospective cohort. METHODS: During 1993-1997, we recruited 57,053 persons. We followed each cohort member for diabetes occurrence from enrollment until 31 December 2006. We traced and geocoded residential...... exposure and diabetes incidence, separately for two definitions of diabetes: all cases and a more strict definition in which cases of diabetes based solely on blood glucose results were excluded. RESULTS: Over a mean follow-up period of 9.7 years for 52,931 eligible participants, there were a total of 4...

High voltage pulse generator. [Patent application

Science.gov (United States)

Fasching, G.E.

1975-06-12

An improved high-voltage pulse generator is described which is especially useful in ultrasonic testing of rock core samples. An N number of capacitors are charged in parallel to V volts and at the proper instance are coupled in series to produce a high-voltage pulse of N times V volts. Rapid switching of the capacitors from the paralleled charging configuration to the series discharging configuration is accomplished by using silicon-controlled rectifiers which are chain self-triggered following the initial triggering of the first rectifier connected between the first and second capacitors. A timing and triggering circuit is provided to properly synchronize triggering pulses to the first SCR at a time when the charging voltage is not being applied to the parallel-connected charging capacitors. The output voltage can be readily increased by adding additional charging networks. The circuit allows the peak level of the output to be easily varied over a wide range by using a variable autotransformer in the charging circuit.

Architecture, Voltage, and Components for a Turboelectric Distributed Propulsion Electric Grid

Science.gov (United States)

Armstrong, Michael J.; Blackwelder, Mark; Bollman, Andrew; Ross, Christine; Campbell, Angela; Jones, Catherine; Norman, Patrick

2015-01-01

The development of a wholly superconducting turboelectric distributed propulsion system presents unique opportunities for the aerospace industry. However, this transition from normally conducting systems to superconducting systems significantly increases the equipment complexity necessary to manage the electrical power systems. Due to the low technology readiness level (TRL) nature of all components and systems, current Turboelectric Distributed Propulsion (TeDP) technology developments are driven by an ambiguous set of system-level electrical integration standards for an airborne microgrid system (Figure 1). While multiple decades' worth of advancements are still required for concept realization, current system-level studies are necessary to focus the technology development, target specific technological shortcomings, and enable accurate prediction of concept feasibility and viability. An understanding of the performance sensitivity to operating voltages and an early definition of advantageous voltage regulation standards for unconventional airborne microgrids will allow for more accurate targeting of technology development. Propulsive power-rated microgrid systems necessitate the introduction of new aircraft distribution system voltage standards. All protection, distribution, control, power conversion, generation, and cryocooling equipment are affected by voltage regulation standards. Information on the desired operating voltage and voltage regulation is required to determine nominal and maximum currents for sizing distribution and fault isolation equipment, developing machine topologies and machine controls, and the physical attributes of all component shielding and insulation. Voltage impacts many components and system performance.

Polymer solar cells with enhanced open-circuit voltage and efficiency

Science.gov (United States)

Chen, Hsiang-Yu; Hou, Jianhui; Zhang, Shaoqing; Liang, Yongye; Yang, Guanwen; Yang, Yang; Yu, Luping; Wu, Yue; Li, Gang

2009-11-01

Following the development of the bulk heterojunction structure, recent years have seen a dramatic improvement in the efficiency of polymer solar cells. Maximizing the open-circuit voltage in a low-bandgap polymer is one of the critical factors towards enabling high-efficiency solar cells. Study of the relation between open-circuit voltage and the energy levels of the donor/acceptor in bulk heterojunction polymer solar cells has stimulated interest in modifying the open-circuit voltage by tuning the energy levels of polymers. Here, we show that the open-circuit voltage of polymer solar cells constructed based on the structure of a low-bandgap polymer, PBDTTT, can be tuned, step by step, using different functional groups, to achieve values as high as 0.76 V. This increased open-circuit voltage combined with a high short-circuit current density results in a polymer solar cell with a power conversion efficiency as high as 6.77%, as certified by the National Renewable Energy Laboratory.

Reliability of supply of switchgear for auxiliary low voltage in substations extra high voltage to high voltage

Directory of Open Access Journals (Sweden)

Perić Dragoslav M.

2015-01-01

Full Text Available Switchgear for auxiliary low voltage in substations (SS of extra high voltages (EHV to high voltage (HV - SS EHV/HV kV/kV is of special interest for the functioning of these important SS, as it provides a supply for system of protection and other vital functions of SS. The article addresses several characteristic examples involving MV lines with varying degrees of independence of their supply, and the possible application of direct transformation EHV/LV through special voltage transformers. Auxiliary sources such as inverters and diesel generators, which have limited power and expensive energy, are also used for the supply of switchgear for auxiliary low voltage. Corresponding reliability indices are calculated for all examples including mean expected annual engagement of diesel generators. The applicability of certain solutions of switchgear for auxiliary low voltage SS EHV/HV, taking into account their reliability, feasibility and cost-effectiveness is analyzed too. In particular, the analysis of applications of direct transformation EHV/LV for supply of switchgear for auxiliary low voltage, for both new and existing SS EHV/HV.

Charge-pump voltage converter

Science.gov (United States)

Brainard, John P [Albuquerque, NM; Christenson, Todd R [Albuquerque, NM

2009-11-03

A charge-pump voltage converter for converting a low voltage provided by a low-voltage source to a higher voltage. Charge is inductively generated on a transfer rotor electrode during its transit past an inductor stator electrode and subsequently transferred by the rotating rotor to a collector stator electrode for storage or use. Repetition of the charge transfer process leads to a build-up of voltage on a charge-receiving device. Connection of multiple charge-pump voltage converters in series can generate higher voltages, and connection of multiple charge-pump voltage converters in parallel can generate higher currents. Microelectromechanical (MEMS) embodiments of this invention provide a small and compact high-voltage (several hundred V) voltage source starting with a few-V initial voltage source. The microscale size of many embodiments of this invention make it ideally suited for MEMS- and other micro-applications where integration of the voltage or charge source in a small package is highly desirable.

SVPWM Technique with Varying DC-Link Voltage for Common Mode Voltage Reduction in a Matrix Converter and Analytical Estimation of its Output Voltage Distortion

Science.gov (United States)

Padhee, Varsha

Common Mode Voltage (CMV) in any power converter has been the major contributor to premature motor failures, bearing deterioration, shaft voltage build up and electromagnetic interference. Intelligent control methods like Space Vector Pulse Width Modulation (SVPWM) techniques provide immense potential and flexibility to reduce CMV, thereby targeting all the afore mentioned problems. Other solutions like passive filters, shielded cables and EMI filters add to the volume and cost metrics of the entire system. Smart SVPWM techniques therefore, come with a very important advantage of being an economical solution. This thesis discusses a modified space vector technique applied to an Indirect Matrix Converter (IMC) which results in the reduction of common mode voltages and other advanced features. The conventional indirect space vector pulse-width modulation (SVPWM) method of controlling matrix converters involves the usage of two adjacent active vectors and one zero vector for both rectifying and inverting stages of the converter. By suitable selection of space vectors, the rectifying stage of the matrix converter can generate different levels of virtual DC-link voltage. This capability can be exploited for operation of the converter in different ranges of modulation indices for varying machine speeds. This results in lower common mode voltage and improves the harmonic spectrum of the output voltage, without increasing the number of switching transitions as compared to conventional modulation. To summarize it can be said that the responsibility of formulating output voltages with a particular magnitude and frequency has been transferred solely to the rectifying stage of the IMC. Estimation of degree of distortion in the three phase output voltage is another facet discussed in this thesis. An understanding of the SVPWM technique and the switching sequence of the space vectors in detail gives the potential to estimate the RMS value of the switched output voltage of any

High voltage systems

International Nuclear Information System (INIS)

Martin, M.

1991-01-01

Industrial processes usually require electrical power. This power is used to drive motors, to heat materials, or in electrochemical processes. Often the power requirements of a plant require the electric power to be delivered at high voltage. In this paper high voltage is considered any voltage over 600 V. This voltage could be as high as 138,000 V for some very large facilities. The characteristics of this voltage and the enormous amounts of power being transmitted necessitate special safety considerations. Safety must be considered during the four activities associated with a high voltage electrical system. These activities are: Design; Installation; Operation; and Maintenance

Ultra-low Voltage CMOS Cascode Amplifier

OpenAIRE

Lehmann, Torsten; Cassia, Marco

2000-01-01

In this paper, we design a folded cascode operational transconductance amplifier in a standard CMOS process, which has a measured 69 dB DC gain, a 2 MHz bandwidth and compatible input- and output voltage levels at a 1 V power supply. This is done by a novel Current Driven Bulk (CDB) technique, which reduces the MOST threshold voltage by forcing a constant current though the transistor bulk terminal. We also look at limitations and improvements of this CDB technique.

Ultra-low Voltage CMOS Cascode Amplifier

DEFF Research Database (Denmark)

Lehmann, Torsten; Cassia, Marco

2000-01-01

In this paper, we design a folded cascode operational transconductance amplifier in a standard CMOS process, which has a measured 69 dB DC gain, a 2 MHz bandwidth and compatible input- and output voltage levels at a 1 V power supply. This is done by a novel Current Driven Bulk (CDB) technique......, which reduces the MOST threshold voltage by forcing a constant current though the transistor bulk terminal. We also look at limitations and improvements of this CDB technique....

New MMC capacitor voltage balancing using sorting-less strategy in nearest level control

DEFF Research Database (Denmark)

Ricco, Mattia; Máthé, Lászlo; Teodorescu, Remus

2016-01-01

This paper proposes a new strategy for balancing the Capacitor Voltages (CVs) for Modular Multilevel Converters (MMCs). The balancing is one of the main challenges in MMC applications and it is usually solved by adopting a global arm control approach. For performing such an approach, a sorted list...... of the SubModules (SMs) according to their capacitor voltages is required. A common way to accomplish this task is to implement a sorting algorithm in the same controller used for the modulation technique. However, the execution time and the computational efforts of these kinds of algorithms increase very...

[Myocardial ultrastructural changes in rats following different levels of acute +Gz exposure].

Science.gov (United States)

Zheng, Jun; Liu, Cheng-gang; Ren, Li; Xiao, Xiao-guang; Xu, Shu-xuan; Wang, Ping; Ji, Gui-ying

2004-06-01

To observe the effects of different levels of acute +Gz exposure on myocardial ultrastructure of rats and provide experimental basis for further development of anti-G measures. Twenty male Wistar rats were randomly divided into 4 groups (n=5): normal control group, +20 Gz group, +10 Gz group and +5 Gz group. Profile of the centrifuge +Gz exposure was trapezoidal, in which +20 Gz lasted for 30 s, +10 Gz for 1.5 min. +5 Gz exposure was repeated for 3 times with 30 min interval and each for 1.5 min. Myocardial tissue of left ventricle was sampled for transmission electron microscopy 5 h after exposure. +20 Gz and +10 Gz exposure caused obvious edema of myocardial and endothelial cells, myofibril disorder and injuries of mitochondria and nucleus. Breaks of myocardial fiber, formation of contraction bands and rupture of mitochondria were also observed in +20 Gz group. In +5 Gz group, there was still slight edema of myocardial and endothelial cells, while organic changes of myocardial ultrastructure were not observed. High +Gz exposure can cause myocardial ultrastructural injury in rats. Slight reversible injured response can also be observed in myocardial cell after repeated moderate level of +Gz exposure. This indicates that attention should be paid to the study of the effect of high +Gz on heart in pilots.

Radiation effects on residual voltage of polyethylene films

International Nuclear Information System (INIS)

Kyokane, Jun; Park, Dae-Hee; Yoshino, Katsumi.

1986-01-01

It has recently been pointed out that diagnosis of deterioration in insulating materials for electric cables used in nuclear power plants and outer space (communications satellite in particular) can be effectively performed based on measurements of residual voltage. In the present study, polyethylene films are irradiated with γ-rays or electron beam to examine the changes in residual voltage characteristics. Irradiation of electron beam and γ-rays are carried out to a dose of 0 - 90 Mrad and 0 - 100 Mrad, respectively. Measurements are made of the dependence of residual voltage on applied voltage, electron beam and γ-ray irradiation, annealing temperature and annealing time. Results show that carriers, which are once trapped after being released from the electrode, move within the material after the opening of the circuit to produce resiual voltage. The residual voltage increases with increasing dose of electron beam or γ-ray and levels off at high dose. Residual voltage is increased about several times by either electron beam or γ-rays, but electron beam tends to cause greater residual voltage than γ-ray. Polyethylene films irradiated with electron beam can recover upon annealing. It is concluded from observations made that residual voltage has close relations with defects in molecular structures caused by radiations, particularly the breaking of backbone chains and alteration in superstructures. (Nogami, K.)

Emissions from Electronic Cigarettes: Assessing Vapers' Intake of Toxic Compounds, Secondhand Exposures, and the Associated Health Impacts.

Science.gov (United States)

Logue, Jennifer M; Sleiman, Mohamad; Montesinos, V Nahuel; Russell, Marion L; Litter, Marta I; Benowitz, Neal L; Gundel, Lara A; Destaillats, Hugo

2017-08-15

E-cigarettes likely represent a lower risk to health than traditional combustion cigarettes, but they are not innocuous. Recently reported emission rates of potentially harmful compounds were used to assess intake and predict health impacts for vapers and bystanders exposed passively. Vapers' toxicant intake was calculated for scenarios in which different e-liquids were used with various vaporizers, battery power settings and vaping regimes. For a high rate of 250 puff day -1 using a typical vaping regime and popular tank devices with battery voltages from 3.8 to 4.8 V, users were predicted to inhale formaldehyde (up to 49 mg day -1 ), acrolein (up to 10 mg day -1 ) and diacetyl (up to 0.5 mg day -1 ), at levels that exceeded U.S. occupational limits. Formaldehyde intake from 100 daily puffs was higher than the amount inhaled by a smoker consuming 10 conventional cigarettes per day. Secondhand exposures were predicted for two typical indoor scenarios: a home and a bar. Contributions from vaping to air pollutant concentrations in the home did not exceed the California OEHHA 8-h reference exposure levels (RELs), except when a high emitting device was used at 4.8 V. In that extreme scenario, the contributions from vaping amounted to as much as 12 μg m -3 formaldehyde and 2.6 μg m -3 acrolein. Pollutant concentrations in bars were modeled using indoor volumes, air exchange rates and the number of hourly users reported in the literature for U.S. bars in which smoking was allowed. Predicted contributions to indoor air levels were higher than those in the residential scenario. Formaldehyde (on average 135 μg m -3 ) and acrolein (28 μg m -3 ) exceeded the acute 1-h exposure REL for the highest emitting vaporizer/voltage combination. Predictions for these compounds also exceeded the 8-h REL in several bars when less intense vaping conditions were considered. Benzene concentrations in a few bars approached the 8-h REL, and diacetyl levels were close to the lower limit

Calibration of the ISOLDE acceleration voltage using a high-precision voltage divider and applying collinear fast beam laser spectroscopy

CERN Document Server

Krieger, A.; Catherall, R.; Hochschulz, F.; Kramer, J.; Neugart, R.; Rosendahl, S.; Schipper, J.; Siesling, E.; Weinheimer, Ch.; Yordanov, D.T.; Nortershauser, W.

2011-01-01

A high-voltage divider with accuracy at the ppm level and collinear laser spectroscopy were used to calibrate the highvoltage installation at the radioactive ion beam facility ISOLDE at CERN. The accurate knowledge of this voltage is particularly important for collinear laser spectroscopy measurements. Beam velocity measurements using frequencycomb based collinear laser spectroscopy agree with the new calibration. Applying this, one obtains consistent results for isotope shifts of stable magnesium isotopes measured using collinear spectroscopy and laser spectroscopy on laser-cooled ions in a trap. The long-term stability and the transient behavior during recovery from a voltage dropout were investigated for the different power supplies currently applied at ISOLDE.

A Model to Determine the Level of Serum Aldosterone in the Workers Attributed to the Combined Effects of Sound Pressure Level, Exposure Time and Serum Potassium Level: A Field-Based Study

Directory of Open Access Journals (Sweden)

Parvin Nassiri

2016-09-01

Full Text Available Background Occupational exposure to excessive noise is one of the biggest work-related challenges in the world. This phenomenon causes the release of stress-related hormones, which in turn, negatively affects cardiovascular risk factors. Objectives The current study study aimed to determine the level of workers’ serum aldosterone in light of the combined effect of sound pressure level, exposure time and serum potassium level. Methods This cross-sectional, descriptive, analytical study was conducted on 45 workers of Gol-Gohar Mining and Industrial Company in the fall of 2014. The subjects were divided into three groups (one control and two case groups, each including 15 workers. Participants in the control group were selected from workers with administrative jobs (exposure to the background noise. On the other hand, participants in the case groups were selected from the concentrator and pelletizing factories exposed to excessive noise. Serum aldosterone and potassium levels of participants were assessed at three different time intervals: at the beginning of the shift and before exposure to noise (7:30 - 8:00 AM, during exposure to noise (10:00 - 10:30 AM, and during continuous exposure (1:30 - 2:00 PM. The obtained data were transferred into SPSS ver. 18. Repeated measures analysis of variance (ANOVA was used to develop the statistical model of workers’ aldosterone level in light of the combined effect of sound pressure level, exposure time, and serum potassium level. Results The results of the final statistical model to determine the level of serum aldosterone based on the combined effect of sound pressure level, exposure time and serum potassium level indicated that the sound pressure level had a significant influence on the human’s serum aldosterone level (P = 0.04. In addition, the effects of exposure time and serum potassium on aldosterone level were statistically significant with P-values of 0.008 and 0.001, respectively. Conclusions

Assessing multimedia/multipathway exposures to inorganic arsenic at population and individual level using MERLIN-Expo.

Science.gov (United States)

Van Holderbeke, Mirja; Fierens, Tine; Standaert, Arnout; Cornelis, Christa; Brochot, Céline; Ciffroy, Philippe; Johansson, Erik; Bierkens, Johan

2016-10-15

In this study, we report on model simulations performed using the newly developed exposure tool, MERLIN-Expo, in order to assess inorganic arsenic (iAs) exposure to adults resulting from past emissions by non-ferrous smelters in Belgium (Northern Campine area). Exposure scenarios were constructed to estimate external iAs exposure as well as the toxicologically relevant As (tAs, i.e., iAs, MMA and DMA) body burden in adults living in the vicinity of the former industrial sites as compared to adults living in adjacent areas and a reference area. Two scenarios are discussed: a first scenario studying exposure to iAs at the aggregated population level and a second scenario studying exposure at the individual level for a random sub-sample of subjects in each of the three different study areas. These two scenarios only differ in the type of human related input data (i.e., time-activity data, ingestion rates and consumption patterns) that were used, namely averages (incl. probability density functions, PDFs) in the simulation at population level and subject-specific values in the simulation at individual level. The model predictions are shown to be lower than the corresponding biomonitoring data from the monitoring campaign. Urinary tAs levels in adults, irrespective of the area they lived in, were under-predicted by MERLIN-Expo by 40% on average. The model predictions for individual adults, by contrast, under-predict the biomonitoring data by 7% on average, but with more important under-predictions for subjects at the upper end of exposure. Still, average predicted urinary tAs levels from the simulations at population level and at individual level overlap, and, at least for the current case, lead to similar conclusions. These results constitute a first and partial verification of the model performance of MERLIN-Expo when dealing with iAs in a complex site-specific exposure scenario, and demonstrate the robustness of the modelling tool for these situations. Copyright �

Bio-Inspired Carbon Monoxide Sensors with Voltage-Activated Sensitivity

KAUST Repository

Savagatrup, Suchol

2017-09-27

Carbon monoxide (CO) outcompetes oxygen when binding to the iron center of hemeproteins, leading to a reduction in blood oxygen level and acute poisoning. Harvesting the strong specific interaction between CO and the iron porphyrin provides a highly selective and customizable sensor. We report the development of chemiresistive sensors with voltage-activated sensitivity for the detection of CO comprising iron porphyrin and functionalized single-walled carbon nanotubes (F-SWCNTs). Modulation of the gate voltage offers a predicted extra dimension for sensing. Specifically, the sensors show a significant increase in sensitivity toward CO when negative gate voltage is applied. The dosimetric sensors are selective to ppm levels of CO and functional in air. UV/Vis spectroscopy, differential pulse voltammetry, and density functional theory reveal that the in situ reduction of FeIII to FeII enhances the interaction between the F-SWCNTs and CO. Our results illustrate a new mode of sensors wherein redox active recognition units are voltage-activated to give enhanced and highly specific responses.

Negative voltage modulated multi-level resistive switching by using a Cr/BaTiOx/TiN structure and quantum conductance through evidence of H2O2 sensing mechanism.

Science.gov (United States)

Chakrabarti, Somsubhra; Ginnaram, Sreekanth; Jana, Surajit; Wu, Zong-Yi; Singh, Kanishk; Roy, Anisha; Kumar, Pankaj; Maikap, Siddheswar; Qiu, Jian-Tai; Cheng, Hsin-Ming; Tsai, Ling-Na; Chang, Ya-Ling; Mahapatra, Rajat; Yang, Jer-Ren

2017-07-05

Negative voltage modulated multi-level resistive switching with quantum conductance during staircase-type RESET and its transport characteristics in Cr/BaTiO x /TiN structure have been investigated for the first time. The as-deposited amorphous BaTiO x film has been confirmed by high-resolution transmission electron microscopy. X-ray photo-electron spectroscopy shows different oxidation states of Ba in the switching material, which is responsible for tunable more than 10 resistance states by varying negative stop voltage owing to slow decay value of RESET slope (217.39 mV/decade). Quantum conductance phenomenon has been observed in staircase RESET cycle of the memory devices. By inspecting the oxidation states of Ba + and Ba 2+ through measuring H 2 O 2 with a low concentration of 1 nM in electrolyte/BaTiO x /SiO 2 /p-Si structure, the switching mechanism of each HRS level as well as the multi-level phenomenon has been explained by gradual dissolution of oxygen vacancy filament. Along with negative stop voltage modulated multi-level, current compliance dependent multi-level has also been demonstrated and resistance ratio up to 2000 has been achieved even for a thin (voltage switching curve has been simulated as well. Hence, multi-level resistive switching of Cr/BaTiO x /TiN structure implies the promising applications in high dense, multistate non-volatile memories in near future.

Low-level exposure of guinea pigs and marmosets to sarin vapour in air: Lowest-observable-adverse-effect level (LOAEL) for miosis

NARCIS (Netherlands)

Helden, H.P.M. van; Trap, H.C.; Kuijpers, W.C.; Oostdijk, J.P.; Benschop, H.P.; Langenberg, J.P.

2004-01-01

The purpose of this pilot study was to indicate, for low-level exposure of conscious guinea pigs and marmoset monkeys to sarin vapour in air, the lowest-observable-adverse-effect level (LOAEL) of sarin for miosis. This is the concentration × time (C·t) value (t = 5 h) of exposure at which miosis

The effects of repeated low-level blast exposure on hearing in marines

Directory of Open Access Journals (Sweden)

Lina R Kubli

2017-01-01

Full Text Available Background: The study evaluates a group of Military Service Members specialized in blast explosive training called “Breachers” who are routinely exposed to multiple low-level blasts while teaching breaching at the U.S. Marine Corps in Quantico Virginia. The objective of this study was to determine if there are any acute or long-term auditory changes due to repeated low-level blast exposures used in training. The performance of the instructor group “Breachers” was compared to a control group, “Engineers”. Methods: A total of 11 Breachers and four engineers were evaluated in the study. The participants received comprehensive auditory tests, including pure-tone testing, speech-in-noise (SIN measures, and central auditory behavioral and objective tests using early and late (P300 auditory evoked potentials over a period of 17 months. They also received shorter assessments immediately following the blast-exposure onsite at Quantico. Results: No acute or longitudinal effects were identified. However, there were some interesting baseline effects found in both groups. Contrary to the expected, the onsite hearing thresholds and distortion product otoacoustic emissions were slightly better at a few frequencies immediately after blast-exposure than measurements obtained with the same equipment weeks to months after each blast-exposure. Conclusions: To date, the current study is the most comprehensive study that evaluates the long-term effects of blast-exposure on hearing. Despite extensive testing to assess changes, the findings of this study suggest that the levels of current exposures used in this military training environment do not seem to have an obvious deleterious effect on hearing.

Low Level Exposure to GB Vapor in Air: Diagnosis/Dosimetry, Lowest Observable Effect Levels, Performance-Incapacitation, and Possible Delayed Effects

National Research Council Canada - National Science Library

1998-01-01

...: (I) A glass exposure chamber for whole-body exposure of unanesthetized guinea pigs and marmosets to low levels of OB vapor in air has been designed and constructed, and is in the implementation stage...

TECHNICAL AND ECONOMIC EVALUATION OF OPTIMAL VOLTAGE LEVEL FOR THE POWER SUPPLY OF DEEP MINE OPERATING HORIZONS

OpenAIRE

Shkrabets, F. P.; Ostapchuk, O. V.; Kozhevnikov, A. V.; Akulov, A. V.

2015-01-01

The most perspective option for possible deep mine power supply is the one with the deep input of 35 kV voltage by installing of underground 35kV/6 kV substation. This option is caused by the expected level of electrical loads, provided by mine development, the power consumers’ deep layout (considering the distance from the source to the shaft on the surface and from the shaft to the underground substation chamber) and primary and the most responsible power consumers (blind shaft lifting devi...

Lifetime Exposure to Intimate Partner Violence and Proinflammatory Cytokine Levels Across the Perinatal Period.

Science.gov (United States)

Robertson Blackmore, Emma; Mittal, Mona; Cai, Xueya; Moynihan, Jan A; Matthieu, Monica M; O'Connor, Thomas G

2016-10-01

Intimate partner violence (IPV) is a public health concern, affecting one-third of US women. Prior research suggests an association between exposure to IPV and poor maternal perinatal health, but the underlying biological correlates are not well understood. This study examined the relationship between exposure to IPV and proinflammatory cytokine levels, a candidate mechanism accounting for poor psychiatric and obstetric outcomes, across the perinatal period. Data were obtained from a prospective, longitudinal cohort study of 171 women receiving obstetrical care from a hospital-based practice serving a predominantly low-income minority population. Participants completed questionnaires on IPV exposure, psychiatric symptoms, and psychosocial and obstetric factors and provided blood samples at 18 and 32 weeks of gestation and 6 weeks and 6 months postpartum. Serum levels of interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-α) were assayed via enzyme-linked immunosorbent assay. Thirty-five (20.5%) women reported lifetime exposure to IPV and 7 (4.1%) reported being physically hurt in the preceding 12 months (4 while pregnant). Lifetime exposure to IPV was associated with increased likelihood of experiencing perinatal depression and smoking during pregnancy. Women with a history of IPV had significantly higher levels of TNF-α at 18 weeks (z = -2.29, p < 0.05), but significantly smaller changes in levels of IL-6 (β = -0.36, p = 0.04) across time. Lifetime exposure to IPV was associated with a range of adverse mental health outcomes and may affect proinflammatory cytokine levels in pregnancy.

High-Voltage Clock Driver for Photon-Counting CCD Characterization

Science.gov (United States)

Baker, Robert

2013-01-01

A document discusses the CCD97 from e2v technologies as it is being evaluated at Goddard Space Flight Center's Detector Characterization Laboratory (DCL) for possible use in ultra-low background noise space astronomy applications, such as Terrestrial Planet Finder Coronagraph (TPF-C). The CCD97 includes a photoncounting mode where the equivalent output noise is less than one electron. Use of this mode requires a clock signal at a voltage level greater than the level achievable by the existing CCD (charge-coupled-device) electronics. A high-voltage waveform generator has been developed in code 660/601 to support the CCD97 evaluation. The unit generates required clock waveforms at voltage levels from -20 to +50 V. It deals with standard and arbitrary waveforms and supports pixel rates from 50 to 500 kHz. The system is designed to interface with existing Leach CCD electronics.

Studies on low-voltage x-ray radiography for graphite materials

International Nuclear Information System (INIS)

Muraoka, Susumu; Itami, Hiroharu

1978-09-01

Low-voltage radiography has been studied to provide optimum technique for graphite less than 50 mm thick. First we determined the exposure conditions under which the most appropriate photographic density can be obtained. By parametric studies, an exposure chart was prepared. Then we studied how the environment of photographing affected the film density. Thirdly, by use of graphite materials with artificial flaws, Image Quality Indicator (I.Q.I.) sensitivity was determined. Detectability of a crack depended on an incidence angle of X-rays onto a crack. Finally, we photographed graphites having natural flaws and gained a useful information. (author)

CURRENT LEVELS OF MEDICAL EXPOSURE IN RUSSIA

Directory of Open Access Journals (Sweden)

M. I. Balonov

2015-01-01

Full Text Available We considered conditions of patients’ medical radiation exposure in Russian diagnostic radiology and nuclear medicine basing on the data of our own research, of the Unified system of individual dose control and of some relevant literature. We analyzed the data on the number of diagnostic examinations, patients’ individual and collective doses and their distribution by examination types. Time trends of the studied parameters are presented for the period between 1999 and 2013. Current level of Russian patients’ medical exposure is the lowest over the whole observation period and one of the lowest among the developed countries. The annual number of X-ray diagnostic examinations is 1.8 per capita. In 2013 median effective dose of medical exposure per capita in Russia was 0.45 mSv and median dose per procedure was 0.25 mSv. The major contribution to collective dose of medical exposure was from computed tomography and radiography; the largest individual doses were caused by interventional radiology, computed X-Ray and nuclear medicine tomographic examinations. The range of median doses comprises about four orders of magnitude, i.e. from several microSv in dental X-ray examinations up to several tens of milliSv in interventional and multistage tomographic examinations. The median effective dose of adult patients increases by about an order of magnitude with each transition from dental X-ray examinations to conventional radiology and further to computed tomography and interventional radiology examinations. During interventional X-Ray examinations, absorbed skin doses at radiation beam entrance site may reach several Gray, which may lead to deterministic radiation effects in skin and subcutaneous tissues. Due to replacement of low-dose ‘functional’ nuclear medicine examinations with more informative modern scintigraphy and tomography examination, patient doses substantially increased over the last decade. With current trend for re-equipment of

Cold exposure lowers energy expenditure at the cellular level.

Science.gov (United States)

Park, Seyeon; Chun, Sohyun; Kim, Danuh

2013-06-01

Mitochondrial function is intimately involved in various metabolic processes and is therefore essential to maintain cell viability. Of particular importance is the fact that mitochondrial membrane potential (ΔΨm ) is coupled with oxidative phosphorylation to drive adenosine triphosphate (ATP) synthesis. We have examined the effects of cold temperature stress on ΔΨm and the role of cold temperature receptor expression on ΔΨm . Human bronchial endothelial cell line, BEAS-2B, and human embryonic kidney, HEK293, cell line were transfected with the gene for cold temperature responsive receptor protein TRPM8 or TRPA1, and exposed to cold temperature. ΔΨm was monitored using 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazoyl carbocyanine iodide derivative (JC-10), a ΔΨm probe. While cold temperatures significantly increased ΔΨm and mitochondrial ATP levels in cells transfected with temperature responsive receptor TRPM8 or TRPA1, no change was noted in wild-type cells. Moreover, the change in ΔΨm and ATP level was a dynamic process. ΔΨm was raised to peak levels within 10 min of cold exposure, followed by a return to baseline levels at 30 min. Our findings suggest that cold temperature exposure increased mitochondrial ΔΨm via a mechanism involving cold temperature receptors. © 2013 International Federation for Cell Biology.

Exposure to meat-derived carcinogens and bulky DNA adduct levels in normal-appearing colon mucosa.

Science.gov (United States)

Ho, Vikki; Brunetti, Vanessa; Peacock, Sarah; Massey, Thomas E; Godschalk, Roger W L; van Schooten, Frederik J; Ashbury, Janet E; Vanner, Stephen J; King, Will D

2017-09-01

Meat consumption is a risk factor for colorectal cancer. This research investigated the relationship between meat-derived carcinogen exposure and bulky DNA adduct levels, a biomarker of DNA damage, in colon mucosa. Least squares regression was used to examine the relationship between meat-derived carcinogen exposure (PhIP and meat mutagenicity) and bulky DNA adduct levels in normal-appearing colon tissue measured using 32 P-postlabelling among 202 patients undergoing a screening colonoscopy. Gene-diet interactions between carcinogen exposure and genetic factors relevant to biotransformation and DNA repair were also examined. Genotyping was conducting using the MassARRAY ® iPLEX ® Gold SNP Genotyping assay. PhIP and higher meat mutagenicity exposures were not associated with levels of bulky DNA adducts in colon mucosa. The XPC polymorphism (rs2228001) was found to associate with bulky DNA adduct levels, whereby genotypes conferring lower DNA repair activity were associated with higher DNA adduct levels than the normal activity genotype. Among individuals with genotypes associated with lower DNA repair (XPD, rs13181 and rs1799179) or detoxification activity (GSTP1, rs1695), higher PhIP or meat mutagenicity exposures were associated with higher DNA adduct levels. Significant interactions between the XPC polymorphism (rs2228000) and both dietary PhIP and meat mutagenicity on DNA adduct levels was observed, but associations were inconsistent with the a priori hypothesized direction of effect. Exposure to meat-derived carcinogens may be associated with increased DNA damage occurring directly in the colon among genetically susceptible individuals. Copyright © 2017 Elsevier B.V. All rights reserved.

Gestational exposure to high perchlorate concentrations in drinking water and neonatal thyroxine levels.

Science.gov (United States)

Amitai, Yona; Winston, Gary; Sack, Joseph; Wasser, Janice; Lewis, Matthew; Blount, Benjamin C; Valentin-Blasini, Liza; Fisher, Nirah; Israeli, Avi; Leventhal, Alex

2007-09-01

To assess the effect of gestational perchlorate exposure through drinking water on neonatal thyroxine (T(4)). T(4) values were compared among newborns in Ramat Hasharon, Israel, whose mothers resided in suburbs where drinking water contained perchlorate water exclusively (as determined by a telephone interview) were analyzed as a subset. Serum perchlorate levels in blood from donors residing in the area were used as proxy indicators of exposure. Neonatal T(4) values (mean +/- SD) in the very high, high, and low exposure groups were 13.9 +/- 3.8, 13.9 +/- 3.4, and 14.0 +/- 3.5 microg/dL, respectively (p = NS). Serum perchlorate concentrations in blood from donors residing in areas corresponding to these groups were 5.99 +/- 3.89, 1.19 +/- 1.37, and 0.44 +/- 0.55 microg/L, respectively. T(4) levels of neonates with putative gestational exposure to perchlorate in drinking water were not statistically different from controls. This study finds no change in neonatal T(4) levels despite maternal consumption of drinking water that contains perchlorate at levels in excess of the Environmental Protection Agency (EPA) drinking water equivalent level (24.5 microg/L) based on the National Research Council reference dose (RfD) [0.7 microg/(kg.day)]. Therefore the perchlorate RfD is likely to be protective of thyroid function in neonates of mothers with adequate iodide intake.

Effect of Low Level Cadmium Exposure on Superoxide Dismutase ...

African Journals Online (AJOL)

Purpose: To investigate the effect of low level cadmium (Cd) exposure on the activity of superoxide dismutase ... cancer, aging and a diversity of diseases [5]. Superoxide .... responsible for the long biological half-life of cadmium [12]. ... indicator of the balance between the damaging effects and the ... Scand J Work Environ.

Integrated differential high-voltage transmitting circuit for CMUTs

DEFF Research Database (Denmark)

Llimos Muntal, Pere; Larsen, Dennis Øland; Farch, Kjartan

2015-01-01

In this paper an integrated differential high-voltage transmitting circuit for capacitive micromachined ultrasonic transducers (CMUTs) used in portable ultrasound scanners is designed and implemented in a 0.35 μm high-voltage process. Measurements are performed on the integrated circuit in order...... to assess its performance. The circuit generates pulses at differential voltage levels of 60V, 80V and 100 V, a frequency up to 5MHz and a measured driving strength of 1.75 V/ns with the CMUT connected. The total on-chip area occupied by the transmitting circuit is 0.18 mm2 and the power consumption...

Low level exposure to chemicals and immune system

International Nuclear Information System (INIS)

Colosio, C.; Birindelli, S.; Corsini, E.; Galli, C.L.; Maroni, M.

2005-01-01

Industrialized countries are facing an increase of diseases attributable to an alteration of the immune system function, and concern is growing that this trend could be at least partially attributable to new and modified patterns of exposure to chemicals. Among chemicals matter of concern, pesticides can be included. The Authors have reviewed the existing evidence of pesticide immunotoxicity in humans, showing that existing data are inadequate to raise conclusions on the immunotoxic risk related to these compounds. The limits of existing studies are: poor knowledge on exposure levels, heterogeneity of the approach, and difficulty in giving a prognostic significance to the slight changes often observed. To overcome these limits, the Authors have proposed a tier approach, based on three steps: the first, addressed at pointing out a possible immunomodulation; the second, at refining the results and the third one, when needed, to finalize the study and to point out concordance with previous results. Studies should preferably be carried out through comparison of pre- and post-exposure findings in the same groups of subjects to be examined immediately after the end of the exposure. A simplification of the first step approach can be used by the occupational health physician and the occupational toxicologist. Conclusions on the prognostic significance of the slight changes often observed will be reached only by validating the hypothesis generated by field studies with an epidemiological approach. In this field, the most useful option is represented by longitudinal perspective studies

trans-Caryophyllene, a Natural Sesquiterpene, Causes Tracheal Smooth Muscle Relaxation through Blockade of Voltage-Dependent Ca2+ Channels

Directory of Open Access Journals (Sweden)

Jader Santos Cruz

2012-10-01

Full Text Available trans-Caryophyllene is a major component in the essential oils of various species of medicinal plants used in popular medicine in Brazil. It belongs to the chemical class of the sesquiterpenes and has been the subject of a number of studies. Here, we evaluated the effects of this compound in airway smooth muscle. The biological activities of trans-caryophyllene were examined in isolated bath organs to investigate the effect in basal tonus. Electromechanical and pharmacomechanical couplings were evaluated through the responses to K+ depolarization and exposure to acetylcholine (ACh, respectively. Isolated cells of rat tracheal smooth muscle were used to investigate trans-caryophyllene effects on voltage-dependent Ca2+ channels by using the whole-cell voltage-clamp configuration of the patch-clamp technique. trans-Caryophyllene showed more efficiency in the blockade of electromechanical excitation-contraction coupling while it has only minor inhibitory effect on pharmacomechanical coupling. Epithelium removal does not modify tracheal smooth muscle response elicited by trans-caryophyllene in the pharmacomechanical coupling. Under Ca2+-free conditions, pre-exposure to trans-caryophyllene did not reduce the contraction induced by ACh in isolated rat tracheal smooth muscle, regardless of the presence of intact epithelium. In the whole-cell configuration, trans-caryophyllene (3 mM, inhibited the inward Ba2+ current (IBa to approximately 50% of control levels. Altogether, our results demonstrate that trans-caryophyllene has anti-spasmodic activity on rat tracheal smooth muscle which could be explained, at least in part, by the voltage-dependent Ca2+ channels blockade.

Phase diagrams and switching of voltage and magnetic field in dilute magnetic semiconductor nanostructures

Energy Technology Data Exchange (ETDEWEB)

Escobedo, R. [Departamento de Matematica Aplicada y Ciencias de la Computacion, Universidad de Cantabria, 39005 Santander (Spain); Carretero, M.; Bonilla, L.L. [G. Millan Institute, Fluid Dynamics, Nanoscience and Industrial Maths., Universidad Carlos III de Madrid, 28911 Leganes (Spain); Unidad Asociada al Instituto de Ciencia de Materiales, CSIC, 28049 Cantoblanco, Madrid (Spain); Platero, G. [Instituto de Ciencia de Materiales, CSIC, 28049 Cantoblanco, Madrid (Spain)

2010-04-15

The response of an n-doped dc voltage biased II-VI multi-quantum well dilute magnetic semiconductor nanostructure having its first well doped with magnetic (Mn) impurities is analyzed by sweeping wide ranges of both the voltage and the Zeeman level splitting induced by an external magnetic field. The level splitting versus voltage phase diagram shows regions of stable self-sustained current oscillations immersed in a region of stable stationary states. Transitions between stationary states and self-sustained current oscillations are systematically analyzed by both voltage and level splitting abrupt switching. Sudden voltage or/and magnetic field changes may switch on current oscillations from an initial stationary state, and reciprocally, current oscillations may disappear after sudden changes of voltage or/and magnetic field changes into the stable stationary states region. The results show how to design such a device to operate as a spin injector and a spin oscillator by tuning the Zeeman splitting (through the applied external magnetic field), the applied voltage and the sample configuration parameters (doping density, barrier and well widths, etc.) to select the desired stationary or oscillatory behavior. Phase diagram of Zeeman level splitting {delta} vs. dimensionless applied voltage {phi} for N = 10 QWs. White region: stable stationary states; black: stable self-sustained current oscillations. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Levels of oxylipins, endocannabinoids and related lipids in plasma before and after low-level exposure to acrolein in healthy individuals and individuals with chemical intolerance.

Science.gov (United States)

Claeson, Anna-Sara; Gouveia-Figueira, Sandra; Häggström, Jenny; Fowler, Christopher J; Nording, Malin L

2017-06-01

Oxylipins and endocannabinoids play important biological roles, including effects upon inflammation. It is not known whether the circulating levels of these lipids are affected by inhalation of the environmental pollutant acrolein. In the present study, we have investigated the consequences of low-level exposure to acrolein on oxylipin, endocannabinoid and related lipid levels in the plasma of healthy individuals and individuals with chemical intolerance (CI), an affliction with a suggested inflammatory origin. Participants were exposed twice (60min) to heptane and a mixture of heptane and acrolein. Blood samples were collected before exposure, after and 24h post-exposure. There were no overt effects of acrolein exposure on the oxylipin lipidome or endocannibinoids detectable in the bloodstream at the time points investigated. No relationship between basal levels or levels after exposure to acrolein and CI could be identified. This implicates a minor role of inflammatory mediators on the systemic level in CI. Copyright © 2017 Elsevier Ltd. All rights reserved.

Chronic exposure to environmental levels of tribromophenol impairs zebrafish reproduction

International Nuclear Information System (INIS)

Deng Jun; Liu Chunsheng; Yu Liqin; Zhou Bingsheng

2010-01-01

Tribromophenol (2,4,6-TBP) is ubiquitously found in aquatic environments and biota. In this study, we exposed zebrafish embryos (F 0 ; 2'''' days post-fertilization, dpf) to environmental concentration (0.3 μg/L) and a higher concentration (3.0 μg/L) of TBP and assessed the impact of chronic exposure (120 dpf) on reproduction. TBP exposure did not cause a significant increase in the malformation and reduction in the survival in the F 0 -generation fish. After TBP exposure, the plasma testosterone and estradiol levels significantly increased in males and decreased in females. The transcription of steroidogenic genes (3β-HSD, 17β-HSD, CYP17, CYP19A, CYP19B) was significantly upregulated in the brain and testes in males and downregulated in the brain and ovary in females. TBP exposure significantly downregulated and upregulated the expression of VTG in the liver of female and male fish, respectively. Meanwhile, TBP exposure altered the sex ratio toward a male-dominant state. The F 1 -generation larvae exhibited increased malformation, reduced survival, and retarded growth, suggesting that TBP in the aquatic environment has significant adverse effects on fish population.

Exposure to DEHP decreased four fatty acid levels in plasma of prepartum mice

International Nuclear Information System (INIS)

Nakashima, Ryosuke; Hayashi, Yumi; Khalequzzaman, Md.; Jia, Xiaofang; Wang, Dong; Naito, Hisao; Ito, Yuki; Kamijima, Michihiro; Gonzalez, Frank J.; Nakajima, Tamie

2013-01-01

Maternal exposure to di(2-ethylhexyl) phthalate (DEHP) decreased the plasma triglyceride in prepartum mice. To identify the fatty acid (FA) species involved and to understand the underlying mechanisms, pregnant Sv/129 wild-type (mPPARα), peroxisome proliferator-activated receptor α-null (Pparα-null) and humanized PPARα (hPPARα) mice were treated with diets containing 0%, 0.01%, 0.05% or 0.1% DEHP. Dams were dissected on gestational day 18 together with fetuses, and on postnatal day 2 together with newborns. n-3/n-6 polyunsaturated, saturated, and monounsaturated FAs in maternal plasma and in liver of wild-type offspring, and representative enzymes for FA desaturation and elongation in maternal liver, were measured. The plasma levels of linoleic acid, α-linolenic acid, palmitic acid and oleic acid were higher in the pregnant control mPPARa mice than in Ppara-null and hPPARa mice. DEHP exposure significantly decreased the levels of these four FAs only in pregnant mPPARα mice. Plasma levels of many FAs were higher in pregnant mice than in postpartum ones in a genotype-independent manner, while it was lower in the livers of fetuses than pups. DEHP exposure slightly increased hepatic arachidonic acid, α-linolenic acid, palmitoleic acid and oleic acid in fetuses, but not in pups. However, DEHP exposure did not clearly influence FA desaturase 1 and 2 nor elongase 2 and 5 expressions in the liver of all maternal mice. Taken together, the levels of plasma four FAs with shorter carbon chains were higher in pregnant mPPARα mice than in other genotypes, and DEHP exposure decreased these specific FA concentrations only in mPPARα mice, similarly to triglyceride levels

Voltage Sag due to Pollution Induced Flashover Across Ceramic Insulator Strings

Science.gov (United States)

Reddy B, Subba; Goswami, Arup Kumar

2017-11-01

Voltage sag or voltage dips are significant to industrial reliability. There is a necessity to characterize the feeder level power quality (PQ) and the PQ performance among various utility companies. Contamination/pollution induced flashover is the ultimate consequence of the creeping discharges across the insulator strings which induce voltage sag. These have a severe threat on the safe and reliable operation of power systems. In the present work an attempt has been made to experimentally investigate the occurrence of voltage sag/dips during pollution induced flashovers. Results show significant dip/sag in the voltage magnitude during the flashover process.

A Three-Level Quasi-Two-Stage Single-Phase PFC Converter with Flexible Output Voltage and Improved Conversion Efficiency

DEFF Research Database (Denmark)

Tang, Yi; Zhu, Dexuan; Jin, Chi

2015-01-01

voltages, and it will be very suitable for high-power applications where the output voltage can be either lower or higher than the peak ac input voltage, e.g., plug-in hybrid electric vehicle charging systems. Moreover, the involved dc/dc buck conversion stage may only need to process partial input power...

Mind-sets, low-level exposures, and research

International Nuclear Information System (INIS)

Sagan, L.A.

1993-01-01

Much of our environmental policy is based on the notion that carcinogenic agents are harmful at even minuscule doses. From where does this thinking come? What is the scientific evidence that supports such policy? Moreover, why is the public willing to buy into this? Or is it the other way around: Has the scientific community bought into a paradigm that has its origins in public imagery? Or, most likely, are there interactions between the two? It is essential that we find out whether or not there are risks associated with low-level exposures to radiation. The author can see three obvious areas where the future depends on better information: The increasing radiation exposures resulting from the use of medical diagnostic and therapeutic practices need to be properly evaluated for safety; Environmental policies, which direct enormous resources to the reduction of small radiation exposures, needs to be put on a firmer scientific basis; The future of nuclear energy, dependent as it is on public acceptance, may well rely upon a better understanding of low-dose effects. Nuclear energy could provide an important solution of global warming and other possible environmental hazards, but will probably not be implemented as long as fear of low-dose radiation persists. Although an established paradigm has great resilience, it cannot resist the onslaught of inconsistent scientific observations or of the social value system that supports it. Only new research will enable us to determine if a paradigm shift is in order here

Improved inhalation technology for setting safe exposure levels for workplace chemicals

Science.gov (United States)

Stuart, Bruce O.

1993-01-01

Threshold Limit Values recommended as allowable air concentrations of a chemical in the workplace are often based upon a no-observable-effect-level (NOEL) determined by experimental inhalation studies using rodents. A 'safe level' for human exposure must then be estimated by the use of generalized safety factors in attempts to extrapolate from experimental rodents to man. The recent development of chemical-specific physiologically-based toxicokinetics makes use of measured physiological, biochemical, and metabolic parameters to construct a validated model that is able to 'scale-up' rodent response data to predict the behavior of the chemical in man. This procedure is made possible by recent advances in personal computer software and the emergence of appropriate biological data, and provides an analytical tool for much more reliable risk evaluation and airborne chemical exposure level setting for humans.

Radiation exposure rate and liquid level measurement inside a high level liquid waste (HLLW) storage tank

International Nuclear Information System (INIS)

Sur, B.; Yue, S.; Thekkevarriam, A.

2007-01-01

An instrument based on an inexpensive, small silicon diode has been developed and used to measure, for the first time, the gamma radiation exposure rate profile inside a 6.4 mm diameter reentrant thermo-well tube, immersed in the highly radioactive liquid solution in an HLLW storage tank. The measurement agrees with previous calculations of exposure rate, and provides confirmation for safe and effective radiation work plans and material selection for investigations and remediation of the storage tank facility. The measured radiation exposure rate profile is also used to confirm that the position of tank internal structures have not changed because of aging and corrosion, and to obtain, within a few mm, the level of liquid inside the tank. (author)

Quantifying transition voltage spectroscopy of molecular junctions: Ab initio calculations

DEFF Research Database (Denmark)

Chen, Jingzhe; Markussen, Troels; Thygesen, Kristian Sommer

2010-01-01

Transition voltage spectroscopy (TVS) has recently been introduced as a spectroscopic tool for molecular junctions where it offers the possibility to probe molecular level energies at relatively low bias voltages. In this work we perform extensive ab initio calculations of the nonlinear current...

Effects of Electrode Material on the Voltage of a Tree-Based Energy Generator.

Science.gov (United States)

Hao, Zhibin; Wang, Guozhu; Li, Wenbin; Zhang, Junguo; Kan, Jiangming

2015-01-01

The voltage between a standing tree and its surrounding soil is regarded as an innovative renewable energy source. This source is expected to provide a new power generation system for the low-power electrical equipment used in forestry. However, the voltage is weak, which has caused great difficulty in application. Consequently, the development of a method to increase the voltage is a key issue that must be addressed in this area of applied research. As the front-end component for energy harvesting, a metal electrode has a material effect on the level and stability of the voltage obtained. This study aimed to preliminarily ascertain the rules and mechanisms that underlie the effects of electrode material on voltage. Electrodes of different materials were used to measure the tree-source voltage, and the data were employed in a comparative analysis. The results indicate that the conductivity of the metal electrode significantly affects the contact resistance of the electrode-soil and electrode-trunk contact surfaces, thereby influencing the voltage level. The metal reactivity of the electrode has no significant effect on the voltage. However, passivation of the electrode materials markedly reduces the voltage. Suitable electrode materials are demonstrated and recommended.

Perinatal alcohol exposure enhances nocistatin levels in adulthood.

Science.gov (United States)

Tekes, Kornélia; Hantos, Mónika; Gyenge, Melinda; Csaba, Gyorgy

2007-06-01

In earlier experiments perinatal hormonal imprinting by alcohol decreased the hormone content of immune cells for life. In the present study, both a single day (15% on the third postnatal day) and a long-term treatment schedule of alcohol exposure (3% for 21 days) of dams during lactation significantly (P < 0.01) enhanced endogenous levels of nocistatin in the blood plasma as well as in the cerebrospinal fluid of the offspring, measured in 3-month-old rats. Our data suggest that alcohol consumption during lactation can cause a life-long influence on nocistatin levels in the offspring and most likely modify nocistatin-related functions such as pain tolerance.

Multifunction Voltage-Mode Filter Using Single Voltage Differencing Differential Difference Amplifier

Directory of Open Access Journals (Sweden)

Chaichana Amornchai

2017-01-01

Full Text Available In this paper, a voltage mode multifunction filter based on single voltage differencing differential difference amplifier (VDDDA is presented. The proposed filter with three input voltages and single output voltage is constructed with single VDDDA, two capacitors and two resistors. Its quality factor can be adjusted without affecting natural frequency. Also, the natural frequency can be electronically tuned via adjusting of bias current. The filter can offer five output responses, high-pas (HP, band-pass (BP, band-reject (BR, low-pass (LP and all-ass (AP functions in the same circuit topology. The output response can be selected by choosing the suitable input voltage without the component matching condition and the requirement of additional double gain voltage amplifier. PSpice simulation results to confirm an operation of the proposed filter correspond to the theory.

Chronic exposure to low frequency noise at moderate levels causes impaired balance in mice.

Directory of Open Access Journals (Sweden)

Haruka Tamura

Full Text Available We are routinely exposed to low frequency noise (LFN; below 0.5 kHz at moderate levels of 60-70 dB sound pressure level (SPL generated from various sources in occupational and daily environments. LFN has been reported to affect balance in humans. However, there is limited information about the influence of chronic exposure to LFN at moderate levels for balance. In this study, we investigated whether chronic exposure to LFN at a moderate level of 70 dB SPL affects the vestibule, which is one of the organs responsible for balance in mice. Wild-type ICR mice were exposed for 1 month to LFN (0.1 kHz and high frequency noise (HFN; 16 kHz at 70 dB SPL at a distance of approximately 10-20 cm. Behavior analyses including rotarod, beam-crossing and footprint analyses showed impairments of balance in LFN-exposed mice but not in non-exposed mice or HFN-exposed mice. Immunohistochemical analysis showed a decreased number of vestibular hair cells and increased levels of oxidative stress in LFN-exposed mice compared to those in non-exposed mice. Our results suggest that chronic exposure to LFN at moderate levels causes impaired balance involving morphological impairments of the vestibule with enhanced levels of oxidative stress. Thus, the results of this study indicate the importance of considering the risk of chronic exposure to LFN at a moderate level for imbalance.

Consumer product exposures associated with urinary phthalate levels in pregnant women

OpenAIRE

Buckley, Jessie P.; Palmieri, Rachel T.; Matuszewski, Jeanine M.; Herring, Amy H.; Baird, Donna D.; Hartmann, Katherine E.; Hoppin, Jane A.

2012-01-01

Human phthalate exposure is ubiquitous, but little is known regarding predictors of urinary phthalate levels. To explore this, 50 pregnant women aged 18–38 years completed two questionnaires on potential phthalate exposures and provided a first morning void. Urine samples were analyzed for 12 phthalate metabolites. Associations with questionnaire items were evaluated via Wilcoxon tests and t-tests, and r-squared values were calculated in multiple linear regression models. Few measured factors...

Occupational exposure to mercury. What is a safe level?

OpenAIRE

Moienafshari, R.; Bar-Oz, B.; Koren, G.

1999-01-01

QUESTION: One of my pregnant patients, a dental hygienist, uses mercury in her workplace, but appears to have no symptoms of mercury toxicity. She has heard that mercury might affect her fetus. What should I recommend to her? What is a safe level of mercury in the air for pregnant women? ANSWER: Testing for levels of mercury in whole blood and, preferably, urine is useful for confirming exposure. Currently, mercury vapour concentrations greater than 0.01 mg/m3 are considered unsafe. Also, wom...

Exposure to pyrethroids insecticides and serum levels of thyroid-related measures in pregnant women

International Nuclear Information System (INIS)

Zhang, Jie; Hisada, Aya; Yoshinaga, Jun; Shiraishi, Hiroaki; Shimodaira, Kazuhisa; Okai, Takashi; Noda, Yumiko; Shirakawa, Miyako; Kato, Nobumasa

2013-01-01

Possible association between environmental exposure to pyrethroid insecticides and serum thyroid-related measures was explored in 231 pregnant women of 10–12 gestational weeks recruited at a university hospital in Tokyo during 2009–2011. Serum levels of free thyroxine (fT4), thyroid stimulating hormone (TSH) and thyroid biding globulin (TBG) and urinary pyrethroid insecticide metabolite (3-phenoxybenzoic acid, 3-PBA) were measured. Obstetrical information was obtained from medical records and dietary and lifestyle information was collected by self-administered questionnaire. Geometric mean concentration of creatinine-adjusted urinary 3-PBA was 0.363 (geometric standard deviation: 3.06) μg/g cre, which was consistent with the previously reported levels for non-exposed Japanese adult females. The range of serum fT4, TSH and TBG level was 0.83–3.41 ng/dL, 0.01–27.4 μIU/mL and 16.4–54.4 μg/mL, respectively. Multiple regression analysis was carried out by using either one of serum levels of thyroid-related measures as a dependent variable and urinary 3-PBA as well as other potential covariates (age, pre-pregnancy BMI, parity, urinary iodine, smoking and drinking status) as independent variables: 3-PBA was not found as a significant predictor of serum level of thyroid-related measures. Lack of association may be due to lower pyrethroid insecticide exposure level of the present subjects. Taking the ability of pyrethroid insecticides and their metabolite to bind to nuclear thyroid hormone (TH) receptor, as well as their ability of placental transfer, into consideration, it is warranted to investigate if pyrethroid pesticides do not have any effect on TH actions in fetus brain even though maternal circulating TH level is not affected. -- Highlights: • Pyrethroid exposure and thyroid hormone status was examined in pregnant women. • Urinary 3-phenoxybenzoic acid was used as a biomarker of exposure. • Iodine nutrition, age and other covariates were included

Exposure to pyrethroids insecticides and serum levels of thyroid-related measures in pregnant women

Energy Technology Data Exchange (ETDEWEB)

Zhang, Jie; Hisada, Aya [Department of Environmental Studies, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8563 (Japan); Yoshinaga, Jun, E-mail: junyosh@k.u-tokyo.ac.jp [Department of Environmental Studies, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8563 (Japan); Shiraishi, Hiroaki [National Institute for Environmental Studies, Onogawa 16-2, Tsukuba, Ibaraki 305-8563 (Japan); Shimodaira, Kazuhisa; Okai, Takashi [Department of Obstetrics and Gynecology, Showa University School of Medicine, 1-5-8 Hatanodai, Shinagawa, Tokyo 142-8555 (Japan); Noda, Yumiko; Shirakawa, Miyako; Kato, Nobumasa [Department of Psychiatry and Neurology, Showa University School of Medicine, 1-5-8 Hatanodai, Shinagawa, Tokyo 142-8555 (Japan)

2013-11-15

Possible association between environmental exposure to pyrethroid insecticides and serum thyroid-related measures was explored in 231 pregnant women of 10–12 gestational weeks recruited at a university hospital in Tokyo during 2009–2011. Serum levels of free thyroxine (fT4), thyroid stimulating hormone (TSH) and thyroid biding globulin (TBG) and urinary pyrethroid insecticide metabolite (3-phenoxybenzoic acid, 3-PBA) were measured. Obstetrical information was obtained from medical records and dietary and lifestyle information was collected by self-administered questionnaire. Geometric mean concentration of creatinine-adjusted urinary 3-PBA was 0.363 (geometric standard deviation: 3.06) μg/g cre, which was consistent with the previously reported levels for non-exposed Japanese adult females. The range of serum fT4, TSH and TBG level was 0.83–3.41 ng/dL, 0.01–27.4 μIU/mL and 16.4–54.4 μg/mL, respectively. Multiple regression analysis was carried out by using either one of serum levels of thyroid-related measures as a dependent variable and urinary 3-PBA as well as other potential covariates (age, pre-pregnancy BMI, parity, urinary iodine, smoking and drinking status) as independent variables: 3-PBA was not found as a significant predictor of serum level of thyroid-related measures. Lack of association may be due to lower pyrethroid insecticide exposure level of the present subjects. Taking the ability of pyrethroid insecticides and their metabolite to bind to nuclear thyroid hormone (TH) receptor, as well as their ability of placental transfer, into consideration, it is warranted to investigate if pyrethroid pesticides do not have any effect on TH actions in fetus brain even though maternal circulating TH level is not affected. -- Highlights: • Pyrethroid exposure and thyroid hormone status was examined in pregnant women. • Urinary 3-phenoxybenzoic acid was used as a biomarker of exposure. • Iodine nutrition, age and other covariates were included

Temporary over voltages in the high voltage networks

International Nuclear Information System (INIS)

Vukelja, Petar; Naumov, Radomir; Mrvic, Jovan; Minovski, Risto

2001-01-01

The paper treats the temporary over voltages that may arise in the high voltage networks as a result of: ground faults, loss of load, loss of one or two phases and switching operation. Based on the analysis, the measures for their limitation are proposed. (Original)

Voltage regulator for generator

Energy Technology Data Exchange (ETDEWEB)

Naoi, K

1989-01-17

It is an object of this invention to provide a voltage regulator for a generator charging a battery, wherein even if the ambient temperature at the voltage regulator rises abnormally high, possible thermal breakage of the semiconductor elements constituting the voltage regulator can be avoided. A feature of this invention is that the semiconductor elements can be protected from thermal breakage, even at an abnormal ambient temperature rise at the voltage regulator for the battery charging generator, by controlling a maximum conduction ratio of a power transistor in the voltage regulator in accordance with the temperature at the voltage regulator. This is achieved through a switching device connected in series to the field coil of the generator and adapted to be controlled in accordance with an output voltage of the generator and the ambient temperature at the voltage regulator. 6 figs.

Cognitive consequences of novelty and familiarity: how mere exposure influences level of construal

NARCIS (Netherlands)

Förster, J.

2009-01-01

Two experiments examine whether frequency of exposure influences level of construal. Using subliminal presentation, participants were exposed to neutral, unknown letters 0, 5, 15, or 40 times, and a typical mere exposure effect was found on evaluation. However, we hypothesized and showed in

A Quantification of the Energy Savings by Conservation Voltage Reduction

NARCIS (Netherlands)

Ellens, W.; Berry, A.; West, S.

2013-01-01

The introduction of `Smart grid' technologies in the electricity supply industry has attracted new attention to Conservation Voltage Reduction (CVR). CVR is a method that aims to save energy by reducing the voltage level of the electrical distribution network. However, not all devices consume less

Temporal development and chemical efficiency of positive streamers in a large scale wire-plate reactor as a function of voltage waveform parameters

Science.gov (United States)

Winands, G. J. J.; Liu, Z.; Pemen, A. J. M.; van Heesch, E. J. M.; Yan, K.; van Veldhuizen, E. M.

2006-07-01

In this paper a large-scale pulsed corona system is described in which pulse parameters such as pulse rise-time, peak voltage, pulse width and energy per pulse can be varied. The chemical efficiency of the system is determined by measuring ozone production. The temporal and spatial development of the discharge streamers is recorded using an ICCD camera with a shortest exposure time of 5 ns. The camera can be triggered at any moment starting from the time the voltage pulse arrives on the reactor, with an accuracy of less than 1 ns. Measurements were performed on an industrial size wire-plate reactor. The influence of pulse parameters like pulse voltage, DC bias voltage, rise-time and pulse repetition rate on plasma generation was monitored. It was observed that for higher peak voltages, an increase could be seen in the primary streamer velocity, the growth of the primary streamer diameter, the light intensity and the number of streamers per unit length of corona wire. No significant separate influence of DC bias voltage level was observed as long as the total reactor voltage (pulse + DC bias) remained constant and the DC bias voltage remained below the DC corona onset. For those situations in which the plasma appearance changed (e.g. different streamer velocity, diameter, intensity), a change in ozone production was also observed. The best chemical yields were obtained for low voltage (55 kV), low energetic pulses (0.4 J/pulse): 60 g (kWh)-1. For high voltage (86 kV), high energetic pulses (2.3 J/pulse) the yield decreased to approximately 45 g (kWh)-1, still a high value for ozone production in ambient air (RH 42%). The pulse repetition rate has no influence on plasma generation and on chemical efficiency up to 400 pulses per second.

Temporal development and chemical efficiency of positive streamers in a large scale wire-plate reactor as a function of voltage waveform parameters

Energy Technology Data Exchange (ETDEWEB)

Winands, G J J [EPS Group, Department of Electrical Engineering, Eindhoven University of Technology, 5600 MB, Eindhoven (Netherlands); Liu, Z [EPS Group, Department of Electrical Engineering, Eindhoven University of Technology, 5600 MB, Eindhoven (Netherlands); Pemen, A J M [EPS Group, Department of Electrical Engineering, Eindhoven University of Technology, 5600 MB, Eindhoven (Netherlands); Heesch, E J M van [EPS Group, Department of Electrical Engineering, Eindhoven University of Technology, 5600 MB, Eindhoven (Netherlands); Yan, K [EPS Group, Department of Electrical Engineering, Eindhoven University of Technology, 5600 MB, Eindhoven (Netherlands); Veldhuizen, E M van [EPG Group, Department of Applied Physics, Eindhoven University of Technology, 5600 MB, Eindhoven (Netherlands)

2006-07-21

In this paper a large-scale pulsed corona system is described in which pulse parameters such as pulse rise-time, peak voltage, pulse width and energy per pulse can be varied. The chemical efficiency of the system is determined by measuring ozone production. The temporal and spatial development of the discharge streamers is recorded using an ICCD camera with a shortest exposure time of 5 ns. The camera can be triggered at any moment starting from the time the voltage pulse arrives on the reactor, with an accuracy of less than 1 ns. Measurements were performed on an industrial size wire-plate reactor. The influence of pulse parameters like pulse voltage, DC bias voltage, rise-time and pulse repetition rate on plasma generation was monitored. It was observed that for higher peak voltages, an increase could be seen in the primary streamer velocity, the growth of the primary streamer diameter, the light intensity and the number of streamers per unit length of corona wire. No significant separate influence of DC bias voltage level was observed as long as the total reactor voltage (pulse + DC bias) remained constant and the DC bias voltage remained below the DC corona onset. For those situations in which the plasma appearance changed (e.g. different streamer velocity, diameter, intensity), a change in ozone production was also observed. The best chemical yields were obtained for low voltage (55 kV), low energetic pulses (0.4 J/pulse): 60 g (kWh){sup -1}. For high voltage (86 kV), high energetic pulses (2.3 J/pulse) the yield decreased to approximately 45 g (kWh){sup -1}, still a high value for ozone production in ambient air (RH 42%). The pulse repetition rate has no influence on plasma generation and on chemical efficiency up to 400 pulses per second.

Temporal development and chemical efficiency of positive streamers in a large scale wire-plate reactor as a function of voltage waveform parameters

International Nuclear Information System (INIS)

Winands, G J J; Liu, Z; Pemen, A J M; Heesch, E J M van; Yan, K; Veldhuizen, E M van

2006-01-01

In this paper a large-scale pulsed corona system is described in which pulse parameters such as pulse rise-time, peak voltage, pulse width and energy per pulse can be varied. The chemical efficiency of the system is determined by measuring ozone production. The temporal and spatial development of the discharge streamers is recorded using an ICCD camera with a shortest exposure time of 5 ns. The camera can be triggered at any moment starting from the time the voltage pulse arrives on the reactor, with an accuracy of less than 1 ns. Measurements were performed on an industrial size wire-plate reactor. The influence of pulse parameters like pulse voltage, DC bias voltage, rise-time and pulse repetition rate on plasma generation was monitored. It was observed that for higher peak voltages, an increase could be seen in the primary streamer velocity, the growth of the primary streamer diameter, the light intensity and the number of streamers per unit length of corona wire. No significant separate influence of DC bias voltage level was observed as long as the total reactor voltage (pulse + DC bias) remained constant and the DC bias voltage remained below the DC corona onset. For those situations in which the plasma appearance changed (e.g. different streamer velocity, diameter, intensity), a change in ozone production was also observed. The best chemical yields were obtained for low voltage (55 kV), low energetic pulses (0.4 J/pulse): 60 g (kWh) -1 . For high voltage (86 kV), high energetic pulses (2.3 J/pulse) the yield decreased to approximately 45 g (kWh) -1 , still a high value for ozone production in ambient air (RH 42%). The pulse repetition rate has no influence on plasma generation and on chemical efficiency up to 400 pulses per second

Prediction of breakdown voltages in novel gases for high voltage insulation

International Nuclear Information System (INIS)

Koch, M.

2015-01-01

This thesis submitted to the Swiss Federal Institute of Technology ETH in Zurich examines the use of sulphur hexafluoride (SF_6) and similar gases as important insulation media for high voltage equipment. Due to its superior insulation properties, SF_6 is widely used in gas-insulated switchgear. However, the gas also has a very high global warming potential and the content of SF_6 in the atmosphere is constantly increasing. The search for new insulation gases using classical breakdown experiments is discussed. A model for SF_6 based on the stepped leader model is described. This calculates the breakdown voltages in arbitrary electrode configurations and under standard voltage waveforms. Thus, the thesis provides a method for the prediction of breakdown voltages of arbitrary field configurations under standard voltage waveforms for gases with electron-attaching properties. With this, further gases can be characterized for usage as high voltage insulation media

The relationship between blood lead levels and occupational exposure in a pregnant population

OpenAIRE

Osmel La-Llave-León; José Manuel Salas Pacheco; Sergio Estrada Martínez; Eloísa Esquivel Rodríguez; Francisco X. Castellanos Juárez; Ada Sandoval Carrillo; Angélica María Lechuga Quiñones; Fernando Vázquez Alanís; Gonzalo García Vargas; Edna Madai Méndez Hernández; Jaime Duarte Sustaita

2016-01-01

Background Pregnant women exposed to lead are at risk of suffering reproductive damages, such as miscarriage, preeclampsia, premature delivery and low birth weight. Despite that the workplace offers the greatest potential for lead exposure, there is relatively little information about occupational exposure to lead during pregnancy. This study aims to assess the association between blood lead levels and occupational exposure in pregnant women from Durango, Mexico. Methods A cross-sectional stu...

Cigarette smoking increases radon working level exposures to all occupants of the smoker's home

International Nuclear Information System (INIS)

Johnson, R.H. Jr.; Rosario, A. Jr.

1990-01-01

This paper reports that the 1988 National Academy of Sciences report on radon health risks evaluated the combined effects of radon exposures and cigarettes on the lung cancer risk to smokers. This report showed that the risk of lung cancer is about 10 times greater for smokers than for nonsmokers at the same Working Level exposures. In 1986, the Surgeon General reported that 106,000 lung cancer deaths occurred among smokers. Therefore, the health risks of cigarettes alone or in combination with radon exposures are well recognized. What has not been studied is the effect of cigarette smoke on the Working Levels in homes that increases the exposure to radon decay products to all occupants, both smokers and nonsmokers. Preliminary studies in a radon chamber at Radon QC showed that the smoke from a single cigarette increased the Working Levels by a factor of five within four hours. Furthermore, the Working Levels remained at an elevated level for more than 24 hours. The equilibrium ratio of radon decay products to radon gas also went from about 14% up to 71%, with a slow decrease over 24 hours. Similar studies in the homes of a smoker and nonsmoker confirmed the laboratory observations. The studies in homes also showed the effects of thoron decay products

Experimental evaluation of voltage unbalance compensation in an islanded microgrid

DEFF Research Database (Denmark)

Savaghebi, Mehdi; Guerrero, Josep M.; Jalilian, Alireza

2011-01-01

In this paper, a method for voltage unbalance compensation in an islanded microgrid based on the proper control of distributed generators (DGs) interface converter is proposed. In this method, active and reactive power control loops are considered to control the power sharing among the DGs. Also......, a virtual impedance loop and voltage and current proportional-resonant controllers are included. Experimental results show the effectiveness of the proposed method for compensating voltage unbalance to an acceptable level....

Distance protection of multiple-circuit shared tower transmission lines with different voltages

DEFF Research Database (Denmark)

Silva, Filipe Miguel Faria da; Bak, Claus Leth

2017-01-01

combined faults, being advised to increase the resistive limit of the protection zone, if the network has lower short-circuit power. It is recommended to assure that the fault can only happen for cases where the faulted phase from the higher voltage level leads the faulted phase from the lower voltage......Multiple-circuit transmission lines combining different voltage levels in one tower present extra challenges when setting a protection philosophy, as faults between voltage levels are possible. In this study, the fault loop impedance of combined faults is compared with the fault loop impedance......-phase-to-ground faults. It is also demonstrated that the fault loop impedance of combined faults is more resistive, when compared with equivalent single-phase-to-ground faults. It is concluded that the settings used to protect a line against single-phase-to-ground faults are capable of protecting the line against...

Prenatal Earthquake Exposure and Midlife Uric Acid Levels Among Chinese Adults.

Science.gov (United States)

Ji, Chunpeng; Li, Yanping; Cui, Liufu; Cai, Jianfang; Shi, Jihong; Cheng, Feon W; Li, Yuqing; Curhan, Gary C; Wu, Shouling; Gao, Xiang

2017-05-01

To test whether prenatal exposure to earthquake (as a surrogate for acute prenatal stress) could have unfavorable effects on uric acid levels later in life. We included 536 individuals who had been prenatally exposed to the Tangshan earthquake in 1976, and 536 sex- and age-matched individuals without that exposure. Serum uric acid concentrations were measured based on fasting blood samples, which were repeatedly collected in 2006, 2008, and 2010. Mean uric acid concentrations in 2010 and the increasing rate from 2006 to 2010 were compared between the 2 groups, after adjustment for age, sex, body mass index, serum concentrations of glucose, triglycerides, C-reactive protein level, estimated glomerular filtration rate, and other potential confounders. We also used multiple logistic regression to estimate the risk of hyperuricemia (>416 μmole/liter in men or >357 μmole/liter in women) in 2010 by calculating the odds ratios (ORs) and 95% confidence intervals (95% CIs) after adjustment for the previously mentioned covariates. Participants with prenatal exposure to the earthquake had higher concentrations of serum uric acid (adjusted means 315 μmole/liter versus 296 μmole/liter; P = 0.001) and a higher likelihood of having hyperuricemia (multivariate adjusted OR 1.70 [95% CI 1.09-2.66]) in 2010 relative to those without the exposure. Prenatal exposure to the earthquake was consistently significantly associated with a faster increase in uric acid concentration from 2006 to 2010 (P earthquake was associated with higher serum uric acid and higher odds of hyperuricemia in early adulthood. © 2016, American College of Rheumatology.

Wideband Electrostatic Vibration Energy Harvester (e-VEH) Having a Low Start-Up Voltage Employing a High-Voltage Integrated Interface

International Nuclear Information System (INIS)

Dudka, A; Galayko, D; Basset, P; Cottone, F; Blokhina, E

2013-01-01

This paper reports on an electrostatic Vibration Energy Harvester (e-VEH) system, for which the energy conversion process is initiated with a low bias voltage and is compatible with wideband stochastic external vibrations. The system employs the auto-synchronous conditioning circuit topology with the use of a novel dedicated integrated low-power high-voltage switch that is needed to connect the charge pump and flyback – two main parts of the used conditioning circuit. The proposed switch is designed and implemented in AMS035HV CMOS technology. Thanks to the proposed switch device, which is driven with a low-voltage ground-referenced logic, the e-VEH system may operate within a large voltage range, from a pre-charge low voltage up to several tens volts. With such a high-voltage e-VEH operation, it is possible to obtain a strong mechanical coupling and a high rate of vibration energy conversion. The used transducer/resonator device is fabricated with a batch-processed MEMS technology. When excited with stochastic vibrations having an acceleration level of 0.8 g rms distributed in the band 110–170 Hz, up to 0.75 μW of net electrical power has been harvested with our system. This work presents an important milestone in the challenge of designing a fully integrated smart conditioning interface for the capacitive e-VEHs

Dynamic voltage stability of a distribution system with high penetration of grid-connected photovoltaic type solar generators

Directory of Open Access Journals (Sweden)

Zetty Adibah Kamaruzzaman

2016-06-01

Full Text Available This paper presents the impact of grid-connected photovoltaic (PV generator on dynamic voltage stability of a power distribution system by considering solar intermittency, PV penetration level, and contingencies such as line outage and load increase. The IEEE 13 node test feeder is used as a test system, and a solar PV of 0.48 kV/0.5 MVA is integrated into the test system. Test results show that system voltage is stable at high PV penetration levels. Increase in load causes voltage instability, in which voltage drops below its allowable operating limit. Thus, increase in PV penetration level does not improve system voltage stability because the system experiences voltage collapse during line outage.

Toxicity levels to humans during acute exposure to hydrogen fluoride

International Nuclear Information System (INIS)

Halton, D.M.; Dranitsaris, P.; Baynes, C.J.

1984-11-01

A literature review was conducted of the acute toxicity of hydrogen fluoride (HF) with emphasis on the effects of inhalation of gaseous HF. The data and findings of the relevant references were summarized under four categories: animal studies, controlled human studies, community exposure and industrial exposure. These were critically reviewed and then lethal concentration-time relationships were developed for humans, corresponding to LCsub(LO), LCsub(10) and LCsub(50) levels. The effects of age, health and other physiological variables on the sensitivity to HF were discussed, as well as antagonistic and synergistic effects with other substances

On-site voltage measurement with capacitive sensors on high voltage systems

NARCIS (Netherlands)

Wu, L.; Wouters, P.A.A.F.; Heesch, van E.J.M.; Steennis, E.F.

2011-01-01

In Extra/High-Voltage (EHV/HV) power systems, over-voltages occur e.g. due to transients or resonances. At places where no conventional voltage measurement devices can be installed, on-site measurement of these occurrences requires preferably non intrusive sensors, which can be installed with little

Prediction of breakdown voltages in novel gases for high voltage insulation

Energy Technology Data Exchange (ETDEWEB)

Koch, M.

2015-07-01

This thesis submitted to the Swiss Federal Institute of Technology ETH in Zurich examines the use of sulphur hexafluoride (SF{sub 6}) and similar gases as important insulation media for high voltage equipment. Due to its superior insulation properties, SF{sub 6} is widely used in gas-insulated switchgear. However, the gas also has a very high global warming potential and the content of SF{sub 6} in the atmosphere is constantly increasing. The search for new insulation gases using classical breakdown experiments is discussed. A model for SF{sub 6} based on the stepped leader model is described. This calculates the breakdown voltages in arbitrary electrode configurations and under standard voltage waveforms. Thus, the thesis provides a method for the prediction of breakdown voltages of arbitrary field configurations under standard voltage waveforms for gases with electron-attaching properties. With this, further gases can be characterized for usage as high voltage insulation media.

PV source based high voltage gain current fed converter

Science.gov (United States)

Saha, Soumya; Poddar, Sahityika; Chimonyo, Kudzai B.; Arunkumar, G.; Elangovan, D.

2017-11-01

This work involves designing and simulation of a PV source based high voltage gain, current fed converter. It deals with an isolated DC-DC converter which utilizes boost converter topology. The proposed converter is capable of high voltage gain and above all have very high efficiency levels as proved by the simulation results. The project intends to produce an output of 800 V dc from a 48 V dc input. The simulation results obtained from PSIM application interface were used to analyze the performance of the proposed converter. Transformer used in the circuit steps up the voltage as well as to provide electrical isolation between the low voltage and high voltage side. Since the converter involves high switching frequency of 100 kHz, ultrafast recovery diodes are employed in the circuitry. The major application of the project is for future modeling of solar powered electric hybrid cars.

High voltage engineering

CERN Document Server

Rizk, Farouk AM

2014-01-01

Inspired by a new revival of worldwide interest in extra-high-voltage (EHV) and ultra-high-voltage (UHV) transmission, High Voltage Engineering merges the latest research with the extensive experience of the best in the field to deliver a comprehensive treatment of electrical insulation systems for the next generation of utility engineers and electric power professionals. The book offers extensive coverage of the physical basis of high-voltage engineering, from insulation stress and strength to lightning attachment and protection and beyond. Presenting information critical to the design, selec

Device for monitoring cell voltage

Science.gov (United States)

Doepke, Matthias [Garbsen, DE; Eisermann, Henning [Edermissen, DE

2012-08-21

A device for monitoring a rechargeable battery having a number of electrically connected cells includes at least one current interruption switch for interrupting current flowing through at least one associated cell and a plurality of monitoring units for detecting cell voltage. Each monitoring unit is associated with a single cell and includes a reference voltage unit for producing a defined reference threshold voltage and a voltage comparison unit for comparing the reference threshold voltage with a partial cell voltage of the associated cell. The reference voltage unit is electrically supplied from the cell voltage of the associated cell. The voltage comparison unit is coupled to the at least one current interruption switch for interrupting the current of at least the current flowing through the associated cell, with a defined minimum difference between the reference threshold voltage and the partial cell voltage.

Operator dependency of the radiation exposure in cardiac interventions: feasibility of ultra low dose levels

International Nuclear Information System (INIS)

Emre Ozpelit, Mehmet; Ercan, Ertugrul; Pekel, Nihat; Tengiz, Istemihan; Yilmaz, Akar; Ozpelit, Ebru; Ozyurtlu, Ferhat

2017-01-01

Introduction: Mean radiation exposure in invasive cardiology varies greatly between different centres and interventionists. The International Commission on Radiological Protection and the EURATOM Council stipulate that, despite reference values, 'All medical exposure for radiodiagnostic purposes shall be kept as low as reasonably achievable' (ALARA). The purpose of this study is to establish the effects of the routine application of ALARA principles and to determine operator and procedure impact on radiation exposure in interventional cardiology. Materials and methods: A total of 240 consecutive cardiac interventional procedures were analysed. Five operators performed the procedures, two of whom were working in accordance with ALARA principles (Group 1 operators) with the remaining three working in a standard manner (Group 2 operators). Radiation exposure levels of these two groups were compared. Results: Total fluoroscopy time and the number of radiographic runs were similar between groups. However, dose area product and cumulative dose were significantly lower in Group 1 when compared with Group 2. Radiation levels of Group 1 were far below even the reference levels in the literature, thus representing an ultra-low-dose radiation exposure in interventional cardiology. Conclusion: By use of simple radiation reducing techniques, ultra-low-dose radiation exposure is feasible in interventional cardiology. Achievability of such levels depends greatly on operator awareness, desire, knowledge and experience of radiation protection. (authors)

Effects of Electrode Material on the Voltage of a Tree-Based Energy Generator.

Directory of Open Access Journals (Sweden)

Zhibin Hao

Full Text Available The voltage between a standing tree and its surrounding soil is regarded as an innovative renewable energy source. This source is expected to provide a new power generation system for the low-power electrical equipment used in forestry. However, the voltage is weak, which has caused great difficulty in application. Consequently, the development of a method to increase the voltage is a key issue that must be addressed in this area of applied research. As the front-end component for energy harvesting, a metal electrode has a material effect on the level and stability of the voltage obtained. This study aimed to preliminarily ascertain the rules and mechanisms that underlie the effects of electrode material on voltage. Electrodes of different materials were used to measure the tree-source voltage, and the data were employed in a comparative analysis. The results indicate that the conductivity of the metal electrode significantly affects the contact resistance of the electrode-soil and electrode-trunk contact surfaces, thereby influencing the voltage level. The metal reactivity of the electrode has no significant effect on the voltage. However, passivation of the electrode materials markedly reduces the voltage. Suitable electrode materials are demonstrated and recommended.

First high-voltage measurements using Ca{sup +} ions at the ALIVE experiment

Energy Technology Data Exchange (ETDEWEB)

König, K., E-mail: kkoenig@ikp.tu-darmstadt.de [Technische Universität Darmstadt, Institut für Kernphysik (Germany); Geppert, Ch. [Universität Mainz, Institut für Kernchemie (Germany); Krämer, J.; Maaß, B. [Technische Universität Darmstadt, Institut für Kernphysik (Germany); Otten, E. W. [Universität Mainz, Institut für Physik (Germany); Ratajczyk, T.; Nörtershäuser, W. [Technische Universität Darmstadt, Institut für Kernphysik (Germany)

2017-11-15

Many physics experiments depend on accurate high-voltage measurements to determine for example the exact retardation potential of an electron spectrometer as in the KATRIN experiment or the acceleration voltage of the ions at ISOL facilities. Until now only precision high-voltage dividers can be used to measure voltages up to 65 kV with an accuracy of 1 ppm. However, these dividers need frequent calibration and cross-checking and the direct traceability is not given. In this article we will describe the status of an experiment which aims to measure high voltages using collinear laser spectroscopy and which has the potential to provide a high-voltage standard and hence, a calibration source for precision high-voltage dividers on the 1 ppm level.

Common sole larvae survive high levels of pile-driving sound in controlled exposure experiments.

Directory of Open Access Journals (Sweden)

Loes J Bolle

Full Text Available In view of the rapid extension of offshore wind farms, there is an urgent need to improve our knowledge on possible adverse effects of underwater sound generated by pile-driving. Mortality and injuries have been observed in fish exposed to loud impulse sounds, but knowledge on the sound levels at which (sub-lethal effects occur is limited for juvenile and adult fish, and virtually non-existent for fish eggs and larvae. A device was developed in which fish larvae can be exposed to underwater sound. It consists of a rigid-walled cylindrical chamber driven by an electro-dynamical sound projector. Samples of up to 100 larvae can be exposed simultaneously to a homogeneously distributed sound pressure and particle velocity field. Recorded pile-driving sounds could be reproduced accurately in the frequency range between 50 and 1000 Hz, at zero to peak pressure levels up to 210 dB re 1µPa(2 (zero to peak pressures up to 32 kPa and single pulse sound exposure levels up to 186 dB re 1µPa(2s. The device was used to examine lethal effects of sound exposure in common sole (Solea solea larvae. Different developmental stages were exposed to various levels and durations of pile-driving sound. The highest cumulative sound exposure level applied was 206 dB re 1µPa(2s, which corresponds to 100 strikes at a distance of 100 m from a typical North Sea pile-driving site. The results showed no statistically significant differences in mortality between exposure and control groups at sound exposure levels which were well above the US interim criteria for non-auditory tissue damage in fish. Although our findings cannot be extrapolated to fish larvae in general, as interspecific differences in vulnerability to sound exposure may occur, they do indicate that previous assumptions and criteria may need to be revised.

Voltage-Sharing Converter to Supply Single-Phase Asymmetrical Four-Level Diode-Clamped Inverter With High Power Factor Loads

DEFF Research Database (Denmark)

Boora, Arash A.; Nami, Alireza; Zare, Firuz

2010-01-01

The output voltage quality of some of the single-phase multilevel inverters can be improved when their dc-link voltages are regulated asymmetrically. Symmetrical and asymmetrical multilevel diode-clamped inverters have the problem of dc-link capacitor voltage balancing, especially when power factor...... that the proposed combination of introduced multioutput dc–dc converter and single-phase ADCI is a good candidate for power conversion in residential photovoltaic (PV) utilization....

76 FR 70721 - Voltage Coordination on High Voltage Grids; Notice of Staff Workshop

Science.gov (United States)

2011-11-15

... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Docket No. AD12-5-000] Voltage Coordination on High Voltage Grids; Notice of Staff Workshop Take notice that the Federal Energy Regulatory Commission will hold a Workshop on Voltage Coordination on High Voltage Grids on Thursday, December 1, 2011...

Effects of combined radiofrequency radiation exposure on levels of reactive oxygen species in neuronal cells

International Nuclear Information System (INIS)

Kang, Kyoung Ah; Lee, Hyung Chul; Lee, Je-Jung

2014-01-01

The objective of this study was to investigate the effects of the combined RF radiation (837 MHz CDMA plus 1950 MHz WCDMA) signal on levels of intracellular reactive oxygen species (ROS) in neuronal cells. Exposure of the combined RF signal was conducted at specific absorption rate values of 2 W/kg of CDMA plus 2 W/kg of WCDMA for 2 h. Co-exposure to combined RF radiation with either H 2 O 2 or menadione was also performed. The experimental exposure groups were incubator control, sham-exposed, combined RF radiation-exposed with or without either H 2 O 2 or menadione groups. The intracellular ROS level was measured by flow cytometry using the fluorescent probe dichlorofluorescein diacetate. Intracellular ROS levels were not consistently affected by combined RF radiation exposure alone in a time-dependent manner in U87, PC12 or SH-SY5Y cells. In neuronal cells exposed to combined RF radiation with either H 2 O 2 or menadione, intracellular ROS levels showed no statically significant alteration compared with exposure to menadione or H 2 O 2 alone. These findings indicate that neither combined RF radiation alone nor combined RF radiation with menadione or H 2 O 2 influences the intracellular ROS level in neuronal cells such as U87, PC12 or SH-SY5Y. (author)

Residential exposure from extremely low frequency electromagnetic field (ELF EMF) radiation

Science.gov (United States)

Parthasarathy, Shamesh Raj; Tukimin, Roha

2018-01-01

ELF EMF radiation have received considerable attention as a potential threat to the safety and health of people living in the vicinity of high voltage transmission lines, electric distribution substations, power stations and even in close proximity to electronics and electrical household appliances. The paper highlights the study on the ELF EMF safety assessment performed at residences comprising of an owner-occupied house, a completed vacant house and an under construction condominium. The objectives of this study were to determine the ELF EMF radiation exposure level from the high voltage transmission line, electric distribution substation, power station and electrical household appliances in the residences, and to assess the potential exposure received by the occupants at the assessed locations. The results were logged in the electric and magnetic field strength with the units of volt per meter (V/m) and miliGauss (mG) respectively. The instrument setup and measurement protocols during the assessment were adopted from standard measurement method and procedures stipulated under the Institute of Electrical and Electronics Engineers (IEEE) Standard. The results were compared with the standards recommended in the International Commission on Non-Ionizing Radiation Protection (ICNIRP) guidelines.

Coplanar strips for Josephson voltage standard circuits

International Nuclear Information System (INIS)

Schubert, M.; May, T.; Wende, G.; Fritzsch, L.; Meyer, H.-G.

2001-01-01

We present a microwave circuit for Josephson voltage standards. Here, the Josephson junctions are integrated in a microwave transmission line designed as coplanar strips (CPS). The new layout offers the possibility of achieving a higher scale of integration and to considerably simplify the fabrication technology. The characteristic impedance of the CPS is about 50 Ω, and this should be of interest for programmable Josephson voltage standard circuits with SNS or SINIS junctions. To demonstrate the function of the microwave circuit design, conventional 10 V Josephson voltage standard circuits with 17000 Nb/AlO x /Nb junctions were prepared and tested. Stable Shapiro steps at the 10 V level were generated. Furthermore, arrays of 1400 SINIS junctions in this microwave layout exhibited first-order Shapiro steps. Copyright 2001 American Institute of Physics

Patient dose, gray level and exposure index with a computed radiography system

Science.gov (United States)

Silva, T. R.; Yoshimura, E. M.

2014-02-01

Computed radiography (CR) is gradually replacing conventional screen-film system in Brazil. To assess image quality, manufactures provide the calculation of an exposure index through the acquisition software of the CR system. The objective of this study is to verify if the CR image can be used as an evaluator of patient absorbed dose too, through a relationship between the entrance skin dose and the exposure index or the gray level values obtained in the image. The CR system used for this study (Agfa model 30-X with NX acquisition software) calculates an exposure index called Log of the Median (lgM), related to the absorbed dose to the IP. The lgM value depends on the average gray level (called Scan Average Level (SAL)) of the segmented pixel value histogram of the whole image. A Rando male phantom was used to simulate a human body (chest and head), and was irradiated with an X-ray equipment, using usual radiologic techniques for chest exams. Thermoluminescent dosimeters (LiF, TLD100) were used to evaluate entrance skin dose and exit dose. The results showed a logarithm relation between entrance dose and SAL in the image center, regardless of the beam filtration. The exposure index varies linearly with the entrance dose, but the angular coefficient is beam quality dependent. We conclude that, with an adequate calibration, the CR system can be used to evaluate the patient absorbed dose.

The Effects on Absorbed Dose Distribution in Intraoral X-ray Imaging When Using Tube Voltages of 60 and 70 kV for Bitewing Imaging

Directory of Open Access Journals (Sweden)

Kristina Hellén-Halme

2013-10-01

Full Text Available Objectives: Efforts are made in radiographic examinations to obtain the best image quality with the lowest possible absorbed dose to the patient. In dental radiography, the absorbed dose to patients is very low, but exposures are relatively frequent. It has been suggested that frequent low-dose exposures can pose a risk for development of future cancer. It has previously been reported that there was no significant difference in the diagnostic accuracy of approximal carious lesions in radiographs obtained using tube voltages of 60 and 70 kV. The aim of this study was, therefore, to evaluate the patient dose resulting from exposures at these tube voltages to obtain intraoral bitewing radiographs.Material and Methods: The absorbed dose distributions resulting from two bitewing exposures were measured at tube voltages of 60 and 70 kV using Gafchromic® film and an anatomical head phantom. The dose was measured in the occlusal plane, and ± 50 mm cranially and caudally to evaluate the amount of scattered radiation. The same entrance dose to the phantom was used. The absorbed dose was expressed as the ratio of the maximal doses, the mean doses and the integral doses at tube voltages of 70 and 60 kV.Results: The patient receives approximately 40 - 50% higher (mean and integral absorbed dose when a tube voltage of 70 kV is used.Conclusions: The results of this study clearly indicate that 60 kV should be used for dental intraoral radiographic examinations for approximal caries detection.

Exposure levels of farmers and veterinarians to particulate matter and gases uring operational tasks in pig-fattening houses

Directory of Open Access Journals (Sweden)

Nele Van Ransbeeck

2014-09-01

Full Text Available The main objective of the study was to assess particulate matter (PM exposure levels for both the farmer and the veterinarian during different operational tasks in pig-fattening houses, and to estimate their exposure levels on a daily working basis (time-weighted average (TWA. The measured PM fractions were: inhalable and respirable PM, PM10, PM2.5 and PM1. The effects of pig age, pen floor type (conventional or low emission surface and cleaning of the pens on the personal PM exposure were also investigated. Indoor concentrations of NH[sub]3[/sub], CH[sub]4[/sub], and CO[sub]2[/sub] were additionally measured during some operational tasks. The results showed that personal exposure levels can become extremely high during some operational tasks performed by the farmer or veterinarian. The highest concentration levels were observed during feed shovelling and blood sampling, the lowest during the weighing of the pigs. For the farmer, the estimated TWA exposure levels of inhalable and respirable PM were 6.0 and 0.29 mg m[sup] -3[/sup] , respectively. These exposure levels for the veterinarian were, respectively, 10.6 and 0.74 mg m[sup] -3[/sup] . The PM concentration levels were mainly determined by the performed operational tasks. There was no significant effect of pig age, pen floor type, nor cleaning of the pens on the personal exposure levels.

A Transformerless Medium Voltage Multiphase Motor Drive System

Directory of Open Access Journals (Sweden)

Dan Wang

2016-04-01

Full Text Available A multiphase motor has several major advantages, such as high reliability, fault tolerance, and high power density. It is a critical issue to develop a reliable and efficient multiphase motor drive system. In this paper, a transformerless voltage source converter-based drive system for a medium-voltage (MV multiphase motor is proposed. This drive converter employs cascaded H-bridge rectifiers loaded by H-bridge inverters as the interface between the grid and multiphase motor. The cascaded H-bridge rectifier technique makes the drive system able to be directly connected to the MV grid without the phase-shifting transformer because it can offset the voltage level gap between the MV grid and the semiconductor devices, provide near-sinusoidal AC terminal voltages without filters, and draw sinusoidal line current from the grid. Based on a digital signal processor (DSP, a complete improved Phase Disposition Pulse Width Modulation (PD-PWM method is developed to ensure the individual DC-link capacitor voltage balancing for enhancing the controllability and limiting the voltage and power stress on the H-bridge cells. A downscaled prototype is designed and developed based on a nine-phase motor. The experimental results verify the excellent performances of the proposed drive system and control strategy in steady-state and variant-frequency startup operations.

Voltage-gated calcium flux mediates Escherichia coli mechanosensation.

Science.gov (United States)

Bruni, Giancarlo N; Weekley, R Andrew; Dodd, Benjamin J T; Kralj, Joel M

2017-08-29

Electrically excitable cells harness voltage-coupled calcium influx to transmit intracellular signals, typically studied in neurons and cardiomyocytes. Despite intense study in higher organisms, investigations of voltage and calcium signaling in bacteria have lagged due to their small size and a lack of sensitive tools. Only recently were bacteria shown to modulate their membrane potential on the timescale of seconds, and little is known about the downstream effects from this modulation. In this paper, we report on the effects of electrophysiology in individual bacteria. A genetically encoded calcium sensor expressed in Escherichia coli revealed calcium transients in single cells. A fusion sensor that simultaneously reports voltage and calcium indicated that calcium influx is induced by voltage depolarizations, similar to metazoan action potentials. Cytoplasmic calcium levels and transients increased upon mechanical stimulation with a hydrogel, and single cells altered protein concentrations dependent on the mechanical environment. Blocking voltage and calcium flux altered mechanically induced changes in protein concentration, while inducing calcium flux reproduced these changes. Thus, voltage and calcium relay a bacterial sense of touch and alter cellular lifestyle. Although the calcium effectors remain unknown, these data open a host of new questions about E. coli , including the identity of the underlying molecular players, as well as other signals conveyed by voltage and calcium. These data also provide evidence that dynamic voltage and calcium exists as a signaling modality in the oldest domain of life, and therefore studying electrophysiology beyond canonical electrically excitable cells could yield exciting new findings.

1991 implementation of As Low As Reasonably Achievable (ALARA) administrative radiation exposure levels: Experiences and lessons learned

International Nuclear Information System (INIS)

Aldridge, T.L.; Baumann, B.L.

1993-06-01

As Low As Reasonably Achievable (ALARA) radiation exposure levels were implemented on January 1, 1991, by Westinghouse Hanford Company (WHC), a prime US Department of Energy (DOE) contractor, located in Richland, Washington. This paper describes the radiation exposure levels which were implemented and the associated experiences and lessons learned. The issue of a report from the Committee on Biological Effectiveness of Ionizing Radiation in 1989 prompted DOE to re-evaluate its position on radiation exposure limits and the resulting doses received by occupational radiation workers. DOE requested that all it's contractors determine the impacts to operations from reduced radiation exposure levels

Prediction of windings temperature rise in induction motors supplied with distorted voltage

Energy Technology Data Exchange (ETDEWEB)

Gnacinski, P. [Gdynia Maritime University, Department of Ship Electrical Power Engineering, Morska Street 83, 81-225 Gdynia (Poland)

2008-04-15

One of the features of ship power systems is a different level and intensity of disturbances appearing during routine operation - the rms voltage value and frequency deviation, voltage unbalance and waveform voltage distortion. As a result, marine induction machines are exposed to overheating due to the lowered voltage quality. This paper is devoted to windings temperature rise prediction in marine induction cage machines supplied with distorted voltage, which means real voltage conditions. The proposed method of prediction does not require detailed knowledge of the thermal properties of a machine. Although the method was developed for marine induction motors, it is applicable for industry machines supplied with distorted voltage. It can also be generalized and used for estimation of the steady state windings temperature rise of any electrical machinery in various work conditions. (author)

Prediction of windings temperature rise in induction motors supplied with distorted voltage

International Nuclear Information System (INIS)

Gnacinski, P.

2008-01-01

One of the features of ship power systems is a different level and intensity of disturbances appearing during routine operation - the rms voltage value and frequency deviation, voltage unbalance and waveform voltage distortion. As a result, marine induction machines are exposed to overheating due to the lowered voltage quality. This paper is devoted to windings temperature rise prediction in marine induction cage machines supplied with distorted voltage, which means real voltage conditions. The proposed method of prediction does not require detailed knowledge of the thermal properties of a machine. Although the method was developed for marine induction motors, it is applicable for industry machines supplied with distorted voltage. It can also be generalized and used for estimation of the steady state windings temperature rise of any electrical machinery in various work conditions

Number-to-voltage converter on commutated condensers

International Nuclear Information System (INIS)

Grekhov, Yu.N.

1975-01-01

A code-voltage converter using precision voltage dividers based on commutated capacitors [1] is described which is distinguished by the absence of precision elements. Each digit includes eight field-effect transistors in two 1KT682 microcircuit assemblies and three microcapacitors with a conventional unstable capacitance 6200 pF +- 50%. The converter has a speed of response that is not inferior to that of converters based on R-2R matrices, while in time stability of the characteristics, low interference level, and low output impedance it is superior to such converters

Voltage control in smart grid using T2FLS

DEFF Research Database (Denmark)

Khodayar, Yaser; Sabahi, Kamel; Hajizadeh, Amin

2017-01-01

coordinated to keep the voltage within the standard range. Therefore, in this paper, a multi-agent controller based on type-2 fuzzy logic system (T2FLS) is utilized to coordinate the DG, ULTC, and load to regulate the voltage of the smart grid in the presence of noise and uncertainty. The proposed fuzzy...... system identifies the different parts of the smart grid as an agent (i.e. ULTC, DG, and load) and regulates the voltage by managing them. A 16-bus power system has been utilized to demonstrate the effectiveness of the proposed method. It has been shown that the proposed T2FLS controller outperforms...... the type-1 fuzzy controller and regulates the voltage in an appropriate way even in the presence of the different levels of measurement noise and uncertainty....

Reproducible and controllable induction voltage adder for scaled beam experiments

Energy Technology Data Exchange (ETDEWEB)

Sakai, Yasuo; Nakajima, Mitsuo; Horioka, Kazuhiko [Department of Energy Sciences, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8502 (Japan)

2016-08-15

A reproducible and controllable induction adder was developed using solid-state switching devices and Finemet cores for scaled beam compression experiments. A gate controlled MOSFET circuit was developed for the controllable voltage driver. The MOSFET circuit drove the induction adder at low magnetization levels of the cores which enabled us to form reproducible modulation voltages with jitter less than 0.3 ns. Preliminary beam compression experiments indicated that the induction adder can improve the reproducibility of modulation voltages and advance the beam physics experiments.

Oscillation of Critical Current by Gate Voltage in Cooper Pair Transistor

International Nuclear Information System (INIS)

Kim, N.; Cheong, Y.; Song, W.

2010-01-01

We measured the critical current of a Cooper pair transistor consisting of two Josephson junctions and a gate electrode. The Cooper pair transistors were fabricated by using electron-beam lithography and double-angle evaporation technique. The Gate voltage dependence of critical current was measured by observing voltage jumps at various gate voltages while sweeping bias current. The observed oscillation was 2e-periodic, which shows the Cooper pair transistor had low level of quasiparticle poisoning.

Radiographic detection of initial carious lesions on the proximal surfaces of teeth. Part I. The influence of exposure conditions

International Nuclear Information System (INIS)

Arnold, L.V.

1987-01-01

The relationship between a number of technical exposure conditions and the diagnostic value of bitewing radiographs in the interpretation of initial proximal carious lesions was evaluated. The most important exposure factors for radiographs are tube voltage, filtration, and exposure time. Tube voltage and filtration were found to have an insignificant influence on the diagnostic quality. Exposure time proved to be the most critical factor in influencing diagnostic quality. The greatest difference in diagnostic quality, however, was caused by differences between observers

Influence of current limitation on voltage stability with voltage sourced converter HVDC

DEFF Research Database (Denmark)

Zeni, Lorenzo; Jóhannsson, Hjörtur; Hansen, Anca Daniela

2013-01-01

A first study of voltage stability with relevant amount of Voltage Sourced Converter based High Voltage Direct Current (VSC-HVDC) transmission is presented, with particular focus on the converters’ behaviour when reaching their rated current. The detrimental effect of entering the current...

Is beryllium-induced lung cancer caused only by soluble forms and high exposure levels?

Science.gov (United States)

Schubauer-Berigan, Mary K; Couch, James R; Deddens, James A

2017-08-01

The US Occupational Safety and Health Administration (OSHA) recently proposed a permissible exposure limit of 0.2 µg/m 3 for beryllium, based partly on extrapolated estimates of lung cancer risk from a pooled occupational cohort. The purpose of the present analysis was to evaluate whether cohort members exposed at lower levels to mainly insoluble forms of beryllium exhibit increased risk of lung cancer. We conducted Cox proportional hazards regression analyses among 75 lung cancer cases in age-based risk sets within two lower exposure plants in the pooled cohort followed from 1940 to 2005. We used categorical and power models to evaluate exposure-response patterns for mean and cumulative beryllium exposures in the two-plant cohort, comparing findings with the full pooled cohort. We also evaluated the distribution of exposure-years in each cohort by solubility class (soluble, insoluble and mixed). 98% of workers in the two-plant cohort were hired between 1955 and 1969. The mean beryllium exposure averaged 1.3 µg/m 3 and the predominant form was insoluble. Adjusting for confounders, we observed a monotonic increase in lung cancer mortality across exposure categories in the two-plant cohort. The exposure-response coefficients (per unit ln exposure) were 0.270 (p=0.061) for mean exposure and 0.170 (p=0.033) for cumulative exposure, compared with 0.155 and 0.094 (respectively) in the full cohort. The low-exposure levels at these two plants and the predominance of insoluble beryllium suggest that the overall pooled cohort findings on which OSHA's lung cancer risk assessment is based are relevant for current workers exposed to any form of beryllium. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Double input converters for different voltage sources with isolated charger

Directory of Open Access Journals (Sweden)

Chalash Sattayarak

2014-09-01

Full Text Available This paper presents the double input converters for different voltage input sources with isolated charger coils. This research aims to increase the performance of the battery charger circuit. In the circuit, there are the different voltage levels of input source. The operating modes of the switch in the circuit use the microcontroller to control the battery charge and to control discharge mode automatically when the input voltage sources are lost from the system. The experimental result of this research shows better performance for charging at any time period of the switch, while the voltage input sources work together. Therefore, this research can use and develop to battery charger for present or future.

Restoration of Low-Voltage Distribution Systems with Inverter-Interfaced DG Units

DEFF Research Database (Denmark)

Dietmannsberger, Markus; Wang, Xiongfei; Blaabjerg, Frede

2018-01-01

-area voltage collapse. This paper proposes a restoration strategy from zero voltage conditions for inverter-interfaced DG under islanded conditions. In the approach, a flexible and scalable Master DG inverter concept is introduced for distributed generations, where no communication is needed and an outage......The increasing share of distributed generation (DG) offers new chances in grid restoration of low-voltage distribution grids. Instead of relying on the transmission or high- and medium-voltage levels, establishing islanding operation in low-voltage grids might be a good option after a wide...... of the Master can be balanced by other DG inverters. The control strategy ensures the tracking of nominal values of the system voltage and frequency without zero steady-state error. The influences of non-controllable DG are also taken into account in the strategy with an effective countermeasure developed...

Mapping of Residues Forming the Voltage Sensor of the Voltage-Dependent Anion-Selective Channel

Science.gov (United States)

Thomas, Lorie; Blachly-Dyson, Elizabeth; Colombini, Marco; Forte, Michael

1993-06-01

Voltage-gated ion-channel proteins contain "voltage-sensing" domains that drive the conformational transitions between open and closed states in response to changes in transmembrane voltage. We have used site-directed mutagenesis to identify residues affecting the voltage sensitivity of a mitochondrial channel, the voltage-dependent anion-selective channel (VDAC). Although charge changes at many sites had no effect, at other sites substitutions that increased positive charge also increased the steepness of voltage dependance and substitutions that decreased positive charge decreased voltage dependance by an appropriate amount. In contrast to the plasma membrane K^+ and Na^+ channels, these residues are distributed over large parts of the VDAC protein. These results have been used to define the conformational transitions that accompany voltage gating of an ion channel. This gating mechanism requires the movement of large portions of the VDAC protein through the membrane.

Molecular mechanism of voltage sensing in voltage-gated proton channels

Science.gov (United States)

Rebolledo, Santiago; Perez, Marta E.

2013-01-01

Voltage-gated proton (Hv) channels play an essential role in phagocytic cells by generating a hyperpolarizing proton current that electrically compensates for the depolarizing current generated by the NADPH oxidase during the respiratory burst, thereby ensuring a sustained production of reactive oxygen species by the NADPH oxidase in phagocytes to neutralize engulfed bacteria. Despite the importance of the voltage-dependent Hv current, it is at present unclear which residues in Hv channels are responsible for the voltage activation. Here we show that individual neutralizations of three charged residues in the fourth transmembrane domain, S4, all reduce the voltage dependence of activation. In addition, we show that the middle S4 charged residue moves from a position accessible from the cytosolic solution to a position accessible from the extracellular solution, suggesting that this residue moves across most of the membrane electric field during voltage activation of Hv channels. Our results show for the first time that the charge movement of these three S4 charges accounts for almost all of the measured gating charge in Hv channels. PMID:23401575

Vivitron 1995, transient voltage simulation, high voltage insulator tests, electric field calculation

International Nuclear Information System (INIS)

Frick, G.; Osswald, F.; Heusch, B.

1996-01-01

Preliminary investigations showed clearly that, because of the discrete electrode structure of the Vivitron, important overvoltage leading to insulator damage can appear in case of a spark. The first high voltage tests showed damage connected with such events. This fact leads to a severe voltage limitation. This work describes, at first, studies made to understand the effects of transients and the associated over-voltage appearing in the Vivitron. Then we present the high voltage tests made with full size Vivitron components using the CN 6 MV machine as a pilot machine. Extensive field calculations were made. These involve simulations of static stresses and transient overvoltages, on insulating boards and electrodes. This work gave us the solutions for arrangements and modifications in the machine. After application, the Vivitron runs now without any sparks and damage at 20 MV. In the same manner, we tested column insulators of a new design and so we will find out how to get to higher voltages. Electric field calculation around the tie bars connecting the discrete electrodes together showed field enhancements when the voltages applied on the discrete electrodes are not equally distributed. This fact is one of the sources of discharges and voltage limitations. A scenario of a spark event is described and indications are given how to proceed towards higher voltages, in the 30 MV range. (orig.)

An Estimation Method of System Voltage Sag Profile using Recorded Sag Data

Science.gov (United States)

Tanaka, Kazuyuki; Sakashita, Tadashi

The influence of voltage sag to electric equipment has become big issues because of wider utilization of voltage sensitive devices. In order to reduce the influence of voltage sag appearing at each customer side, it is necessary to recognize the level of receiving voltage drop due to lightning faults for transmission line. However it is hard to measure directly those sag level at every load node. In this report, a new method of efficiently estimating system voltage sag profile is proposed based on symmetrical coordinate. In the proposed method, limited recorded sag data is used as the estimation condition which is recorded at each substation in power systems. From the point of view that the number of the recorded node is generally far less than those of the transmission route, a fast solution method is developed to calculate only recorder faulted voltage by applying reciprocity theorem for Y matrix. Furthermore, effective screening process is incorporated, in which the limited candidate of faulted transmission line can be chosen. Demonstrative results are presented using the IEEJ East10 standard system and actual 1700 bus system. The results show that estimation accuracy is sufficiently acceptable under less computation labor.

Effects of low-level blast exposure on the nervous system: Is there really a controversy?

Directory of Open Access Journals (Sweden)

Gregory A Elder

2014-12-01

Full Text Available High-pressure blast waves can cause extensive CNS injury in humans. However, in combat settings such as Iraq and Afghanistan, lower level exposures associated with mild TBI (mTBI or subclinical exposure have been much more common. Yet controversy exists concerning what traits can be attributed to low-level blast, in large part due to the difficulty of distinguishing blast-related mTBI from post-traumatic stress disorder (PTSD. We describe how TBI is defined in humans and the problems posed in using current definitions to recognize blast-related mTBI. We next consider the problem of applying definitions of human mTBI to animal models, in particular that TBI severity in humans is defined in relation to alteration of consciousness at the time of injury, which typically cannot be assessed in animals. However, based on outcome assessments a condition of low-level blast exposure can be defined in animals that likely approximates human mTBI or subclinical exposure. We review blast injury modeling in animals noting that inconsistencies in experimental approach have contributed to uncertainty over the effects of low-level blast. Yet animal studies show that low-level blast pressure waves are transmitted to the brain. In brain low-level blast exposures cause behavioral, biochemical, pathological and physiological effects on the nervous system including the induction of PTSD-related behavioral traits in the absence of a psychological stressor. We review the relationship of blast exposure to chronic neurodegenerative diseases noting the paradoxical lowering of Abeta by blast, which along with other observations suggest that blast-related TBI is pathophysiologically distinct from non-blast TBI. Human neuroimaging studies show that blast-related mTBI is associated with a variety of chronic effects that are unlikely to be explained by co-morbid PTSD. We conclude that abundant evidence supports low-level blast as having long-term effects on the nervous system.

EPG waveform library for Graphocephala atropunctata (Hemiptera: Cicadellidae): Effect of adhesive, input resistor, and voltage levels on waveform appearance and stylet probing behaviors.

Science.gov (United States)

Cervantes, Felix A; Backus, Elaine A

2018-05-31

Blue-green sharpshooter, Graphocephala atropunctata, is a native California vector of Xylella fastidiosa (Xf), a foregut-borne bacterium that is the causal agent of Pierce's disease in grapevines. A 3rd-generation, AC-DC electropenetrograph (EPG monitor) was used to record stylet probing and ingestion behaviors of adult G. atropunctata on healthy grapevines. This study presents for the first time a complete, updated waveform library for this species, as well as effects of different electropenetrograph settings and adhesives on waveform appearances. Both AC and DC applied signals were used with input resistor (Ri) levels (amplifier sensitivities) of 10 6 , 10 7 , 10 8 and 10 9  Ohms, as well as two type of adhesives, conducting silver paint and handmade silver glue. Waveform description, characterization of electrical origins (R versus emf components), and proposed biological meanings of waveforms are reported, as well as qualitative differences in waveform appearances observed with different electropenetrograph settings and adhesives. In addition, a quantitative study with AC signal, using two applied voltage levels (50 and 200 mV) and two Ri levels (10 7 and 10 9  Ohms) was performed. Intermediate Ri levels 10 7 and 10 8  Ohms provided EPG waveforms with the greatest amount of information, because both levels captured similar proportions of R and emf components, as supported by appearance, clarity, and definition of waveforms. Similarly, use of a gold wire loop plus handmade silver glue provided more definition of waveforms than a gold wire loop plus commercial conducting silver paint. Qualitative/observational evidence suggested that AC applied signal caused fewer aberrant behaviors/waveforms than DC applied signal. In the quantitative study, behavioral components of the sharpshooter X wave were the most affected by changes in Ri and voltage level. Because the X wave probably represents X. fastidiosa inoculation behavior, future studies of X. fastidiosa

Low-frequency fields - sources and exposure

International Nuclear Information System (INIS)

Kunsch, B.

1993-01-01

The author briefly discusses definition of terms, gives an introduction to measurement techniques and describes the characteristics of various low-frequency fields and their causes using typical examples: natural electric fields (thunderstroms), natural magnetic fields, technical electric constant fields (urban transportation, households), static magnetic fields (urban transportation, nuclear magnetic resonance imaging), technical electric alternating fields (high-voltage transmission lines, households), and magnetic alternating fields (high-voltage transmission lines). The author discusses both occupational exposure and that of the general public while underpinning his statements by numerous tables, measurement diagrams and charts. (Uhe) [de

High-voltage pulsed life of multistressed polypropylene capacitor dielectric

International Nuclear Information System (INIS)

Laghari, J.R.

1992-01-01

High-voltage polypropylene capacitors were aged under singular as well as simultaneous multiple stresses (electrical, thermal, and radiation) at the University of Buffalo's 2 MW thermal nuclear reactor. These stresses were combined neutron-gamma radiation with a total dose of 1.6 x 10 6 rad, electrical stress at 40 V rms /μm, and thermal stress at 90 degrees C. After exposure, the polypropylene dielectric was tested for life (number of pulses to fail) under high-voltage high-repetition-rate (100 pps) pulses. Pulsed life data were also compared with ac life data. Results show that radiation stress causes the most degradation in life, either acting alone or in combination with other stresses. The largest reduction in life occurs when polypropylene is aged under simultaneous multiple stresses (electrical, thermal, and radiation). In this paper, it is shown that pulsed life can be equivalently compared with ac life

Technological Aspects: High Voltage

CERN Document Server

Faircloth, D.C.

2013-12-16

This paper covers the theory and technological aspects of high-voltage design for ion sources. Electric field strengths are critical to understanding high-voltage breakdown. The equations governing electric fields and the techniques to solve them are discussed. The fundamental physics of high-voltage breakdown and electrical discharges are outlined. Different types of electrical discharges are catalogued and their behaviour in environments ranging from air to vacuum are detailed. The importance of surfaces is discussed. The principles of designing electrodes and insulators are introduced. The use of high-voltage platforms and their relation to system design are discussed. The use of commercially available high-voltage technology such as connectors, feedthroughs and cables are considered. Different power supply technologies and their procurement are briefly outlined. High-voltage safety, electric shocks and system design rules are covered.

Voltage-controlled spin selection in a magnetic resonant tunneling diode.

Science.gov (United States)

Slobodskyy, A; Gould, C; Slobodskyy, T; Becker, C R; Schmidt, G; Molenkamp, L W

2003-06-20

We have fabricated all II-VI semiconductor resonant tunneling diodes based on the (Zn,Mn,Be)Se material system, containing dilute magnetic material in the quantum well, and studied their current-voltage characteristics. When subjected to an external magnetic field the resulting spin splitting of the levels in the quantum well leads to a splitting of the transmission resonance into two separate peaks. This is interpreted as evidence of tunneling transport through spin polarized levels, and could be the first step towards a voltage controlled spin filter.

Secondary Control for Compensation of Voltage Harmonics and Unbalance in Microgrids

DEFF Research Database (Denmark)

Savaghebi, Mehdi; Vasquez, Juan Carlos; Jalilian, Alireza

2012-01-01

of these controllers includes a selective virtual impedance loop which is considered to improve sharing of fundamental and harmonic components of load current among the DG units. The sharing improvement is provided at the expense of increasing voltage unbalance and harmonic distortion. Thus, the secondary control...... level is applied to manage the compensation of SLB voltage unbalance and harmonics by sending proper control signals to the primary level. DGs compensation efforts are controlled locally at the primary level. The system design procedure for selecting proper control parameters is discussed. Simulation...

High Efficiency Power Converter for Low Voltage High Power Applications

DEFF Research Database (Denmark)

Nymand, Morten

The topic of this thesis is the design of high efficiency power electronic dc-to-dc converters for high-power, low-input-voltage to high-output-voltage applications. These converters are increasingly required for emerging sustainable energy systems such as fuel cell, battery or photo voltaic based......, and remote power generation for light towers, camper vans, boats, beacons, and buoys etc. A review of current state-of-the-art is presented. The best performing converters achieve moderately high peak efficiencies at high input voltage and medium power level. However, system dimensioning and cost are often...

2.3-MW Medium-Voltage, Three-Level Wind Energy Inverter Applying a Unique Bus Structure and 4.5-kV Si/SiC Hybrid Isolated Power Modules: Preprint

Energy Technology Data Exchange (ETDEWEB)

Erdman, W.; Keller, J.; Grider, D.; VanBrunt, E.

2014-11-01

A high-efficiency, 2.3-MW, medium-voltage, three-level inverter utilizing 4.5-kV Si/SiC (silicon carbide) hybrid modules for wind energy applications is discussed. The inverter addresses recent trends in siting the inverter within the base of multimegawatt turbine towers. A simplified split, three-layer laminated bus structure that maintains low parasitic inductances is introduced along with a low-voltage, high-current test method for determining these inductances. Feed-thru bushings, edge fill methods, and other design features of the laminated bus structure provide voltage isolation that is consistent with the 10.4-kV module isolation levels. Inverter efficiency improvement is a result of the (essential) elimination of the reverse recovery charge present in 4.5-kV Si PIN diodes, which can produce a significant reduction in diode turn-off losses as well as insulated-gate bipolar transistor (IGBT) turn-on losses. The hybrid modules are supplied in industry-standard 140 mm x 130 mm and 190 mm x 130 mm packages to demonstrate direct module substitution into existing inverter designs. A focus on laminated bus/capacitor-bank/module subassembly level switching performance is presented.

Prenatal exposure to lead in Spain: cord blood levels and associated factors.

Science.gov (United States)

Llop, Sabrina; Aguinagalde, Xabier; Vioque, Jesus; Ibarluzea, Jesús; Guxens, Mònica; Casas, Maribel; Murcia, Mario; Ruiz, María; Amurrio, Ascensión; Rebagliato, Marisa; Marina, Loreto Santa; Fernandez-Somoano, Ana; Tardon, Adonina; Ballester, Ferran

2011-05-01

Lead is a known neurotoxic. Fetuses and infants are very vulnerable to lead exposure, since their blood-brain barrier is not completely formed. Hence, there is an importance for monitoring of blood lead levels prenatally and during early infancy. The aim of this study is to evaluate the prenatal exposure to lead and its association with maternal factors in four population based mother-child cohorts in Spain. The present research was carried out within the framework of the INMA project INfancia y Medio Ambiente (Environment and Childhood). A total of 1462 pregnant women were recruited between 2004 and 2008. Lead was analyzed in a sample of cord blood by thermal decomposition, amalgation, and Atomic Absorption Spectrometry. Maternal sociodemographic, lifestyle and dietary factors were obtained by questionnaires during pregnancy. A multivariate logistic regression model was constructed. The dependent variable was a dichotomous lead level variable (detected vs no detected, i.e. ≥ vs < 2μg/dL). A low percentage of cord blood samples with lead levels ≥ 2μg/dL were found (5.9%). Geometric mean and maximum were 1.06μg/dL and 19μg/dL, respectively. Smoking at the beginning of pregnancy, age, social class, weight gain during pregnancy, gravidity, and place of residence were the maternal factors associated with detectable cord blood lead levels. Mother's diet does not appear to be a determining factor of lead exposure. Nevertheless, daily intake of iron and zinc may act as a protective factor against having cord blood lead levels ≥ 2μg/dL. In the different regions of Spain taking part in this study, lead levels to which newborns are exposed are low. Mobilization of lead from bones may be the main contributor to the cord blood levels. Copyright © 2011 Elsevier B.V. All rights reserved.

Low level methylmercury exposure affects neuropsychological function in adults

Directory of Open Access Journals (Sweden)

Platt Illeane

2003-06-01

Full Text Available Abstract Background The neurotoxic effects of methylmercury (MeHg have been demonstrated in both human and animal studies. Both adult and fetal brains are susceptible to the effects of MeHg toxicity. However, the specific effects of adult exposures have been less well-documented than those of children with prenatal exposures. This is largely because few studies of MeHg exposures in adults have used sensitive neurological endpoints. The present study reports on the results of neuropsychological testing and hair mercury concentrations in adults (>17 yrs living in fishing communities of Baixada Cuiabana (Mato Grosso in the Pantanal region of Brazil. Methods A cross-sectional study was conducted in six villages on the Cuiaba River. Participants included 129 men and women older than 17 years of age. They were randomly selected in proportion to the age range and number of inhabitants in each village. Questionnaire information was collected on demographic variables, including education, occupation, and residence history. Mercury exposure was determined by analysis of hair using flameless atomic absorption spectrophotometry. The neurocognitive screening battery included tests from the Wechsler Memory Scale and the Wechsler Adult Intelligence Scale, Concentrated Attention Test of the Toulouse-Pierron Factorial Battery, the Manual Ability Subtests of the Tests of Mechanical Ability, and the Profile of Mood States. Results Mercury exposures in this population were associated with fish consumption. The hair mercury concentration in the 129 subjects ranged from 0.56 to 13.6 μg/g; the mean concentration was 4.2 ± 2.4 micrograms/g and the median was 3.7 μg/g. Hair mercury levels were associated with detectable alterations in performance on tests of fine motor speed and dexterity, and concentration. Some aspects of verbal learning and memory were also disrupted by mercury exposure. The magnitude of the effects increased with hair mercury concentration

Mapping very low level occupational exposure in medical imaging: A useful tool in risk communication and decision making

Energy Technology Data Exchange (ETDEWEB)

Covens, P., E-mail: pcovens@vub.ac.be [Health Physics Department, Vrije Universiteit Brussel and UZ Brussel, Laarbeeklaan 103, 1090 Brussels (Belgium); Beeldvorming en Fysische Wetenschappen (BEFY), Vrije Universiteit Brussel, Laarbeeklaan 103, 1090 Brussels (Belgium); Berus, D., E-mail: dberus@vub.ac.be [Health Physics Department, Vrije Universiteit Brussel and UZ Brussel, Laarbeeklaan 103, 1090 Brussels (Belgium); Mey, J. de, E-mail: Johan.DeMey@uzbrussel.be [Department of Radiology, UZ Brussel, Laarbeeklaan 101, 1090 Brussels (Belgium); Beeldvorming en Fysische Wetenschappen (BEFY), Vrije Universiteit Brussel, Laarbeeklaan 103, 1090 Brussels (Belgium); Buls, N., E-mail: Nico.Buls@uzbrussel.be [Department of Radiology, UZ Brussel, Laarbeeklaan 101, 1090 Brussels (Belgium); Beeldvorming en Fysische Wetenschappen (BEFY), Vrije Universiteit Brussel, Laarbeeklaan 103, 1090 Brussels (Belgium)

2012-09-15

Objectives: The use of ionising radiation in medical imaging is accompanied with occupational exposure which should be limited by optimised room design and safety instructions. These measures can however not prevent that workers are exposed to instantaneous dose rates, e.g. the residual exposure through shielding or the exposure of discharged nuclear medicine patients. The latter elements are often questioned by workers and detailed assessment should give more information about the impact on the individual radiation dose. Methods: Cumulated radiation exposure was measured in a university hospital during a period of 6 months by means of thermoluminescent dosimeters. Radiation exposure was measured at background locations and at locations where enhanced exposure levels are expected but where the impact on the individual exposure is unclear. Results: The results show a normal distribution of the cumulated background radiation level. No enhanced cumulated radiation exposure which significantly differs from this background level could be found during the operation of intra-oral apparatus, during ultrasonography procedures among nuclear medicine patients and at operator consoles of most CT-rooms. Conclusions: This 6 months survey offers useful information about occupational low level exposure in medical imaging and the findings can be useful in both risk communication and decision making.

Mapping very low level occupational exposure in medical imaging: A useful tool in risk communication and decision making

International Nuclear Information System (INIS)

Covens, P.; Berus, D.; Mey, J. de; Buls, N.

2012-01-01

Objectives: The use of ionising radiation in medical imaging is accompanied with occupational exposure which should be limited by optimised room design and safety instructions. These measures can however not prevent that workers are exposed to instantaneous dose rates, e.g. the residual exposure through shielding or the exposure of discharged nuclear medicine patients. The latter elements are often questioned by workers and detailed assessment should give more information about the impact on the individual radiation dose. Methods: Cumulated radiation exposure was measured in a university hospital during a period of 6 months by means of thermoluminescent dosimeters. Radiation exposure was measured at background locations and at locations where enhanced exposure levels are expected but where the impact on the individual exposure is unclear. Results: The results show a normal distribution of the cumulated background radiation level. No enhanced cumulated radiation exposure which significantly differs from this background level could be found during the operation of intra-oral apparatus, during ultrasonography procedures among nuclear medicine patients and at operator consoles of most CT-rooms. Conclusions: This 6 months survey offers useful information about occupational low level exposure in medical imaging and the findings can be useful in both risk communication and decision making

High voltage transmission lines - what are the hazards

International Nuclear Information System (INIS)

Repacholi, M.H.

1985-01-01

With the increasing use of high voltage alternating current (HVAC) transmission lines there is a growing concern among the public about possible human health effects resulting from exposure to the electric fields associated with these lines. While there is no definitive evidence of such effects, mounting public fear and activism over hypothesized health risks is already causing delays in the licensing and constuction of major power transmission facilities, and is encouraging the formation of regulatory policy. This paper briefly reviews the concerns, biological effects data and standards for HVAC transmission lines

Comparative Study of Breakdown Voltage of Mineral, Synthetic and Natural Oils and Based Mineral Oil Mixtures under AC and DC Voltages

Directory of Open Access Journals (Sweden)

Abderrahmane Beroual

2017-04-01

ester in DC, the breakdown voltage values of all the tested mixtures were in accordance with the normal distribution, which made it possible to define the breakdown voltages for the risk levels of 1%, 10%, and 50% of probability.

Impact of 900 MHz electromagnetic field exposure on main male reproductive hormone levels: a Rattus norvegicus model

Science.gov (United States)

Sepehrimanesh, Masood; Saeb, Mehdi; Nazifi, Saeed; Kazemipour, Nasrin; Jelodar, Gholamali; Saeb, Saeedeh

2014-09-01

This work analyzes the effects of radiofrequency-electromagnetic field (RF-EMF) exposure on the reproductive system of male rats, assessed by measuring circulating levels of FSH, LH, inhibin B, activin B, prolactin, and testosterone. Twenty adult male Sprague-Dawley rats (180 ± 10 g) were exposed to 900 MHz RF-EMF in four equal separated groups. The duration of exposure was 1, 2, and 4 h/day over a period of 30 days and sham-exposed animals were kept under the same environmental conditions as the exposed group except with no RF-EMF exposure. Before the exposure, at 15 and 30 days of exposure, determination of the abovementioned hormone levels was performed using ELISA. At the end of the experiment, FSH and LH values of the long time exposure (LTE) group were significantly higher than the sham-exposed group ( p reproductive hormone levels are disturbed as a result of RF-EMF exposure and it may possibly affect reproductive functions. However, testosterone and inhibin B concentrations as a fertility marker and spermatogenesis were decreased significantly.

Engineering of a genetically encodable fluorescent voltage sensor exploiting fast Ci-VSP voltage-sensing movements.

Science.gov (United States)

Lundby, Alicia; Mutoh, Hiroki; Dimitrov, Dimitar; Akemann, Walther; Knöpfel, Thomas

2008-06-25

Ci-VSP contains a voltage-sensing domain (VSD) homologous to that of voltage-gated potassium channels. Using charge displacement ('gating' current) measurements we show that voltage-sensing movements of this VSD can occur within 1 ms in mammalian membranes. Our analysis lead to development of a genetically encodable fluorescent protein voltage sensor (VSFP) in which the fast, voltage-dependent conformational changes of the Ci-VSP voltage sensor are transduced to similarly fast fluorescence read-outs.

Tributyltin exposure alters cytokine levels in mouse serum.

Science.gov (United States)

Lawrence, Shanieek; Pellom, Samuel T; Shanker, Anil; Whalen, Margaret M

2016-11-01

Tributyltin (TBT), a toxic environmental contaminant, has been widely utilized for various industrial, agricultural and household purposes. Its usage has led to a global contamination and its bioaccumulation in aquatic organisms and terrestrial mammals. Previous studies suggest that TBT has debilitating effects on the overall immune function of animals, rendering them more vulnerable to diseases. TBT (at concentrations that have been detected in human blood) alters secretion of inflammatory cytokines from human lymphocytes ex vivo. Thus, it is important to determine if specified levels of TBT can alter levels of cytokines in an in vivo system. Mice were exposed to biologically relevant concentrations of TBT (200, 100 or 25 nM final concentrations). The quantitative determination of interferon (IFN)-γ, tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL2, IL5, IL7, IL12βp40, IL13, IL15, keratinocyte chemoattractant (KC), macrophage inflammatory protein 1β (MIP), MIP2 and regulated on activation normal T-cell-expressed and secreted (RANTES) was performed in mouse sera by MAGPIX analysis and Western blot. Results indicated alterations (both decreases and increases) in several cytokines. The pro-inflammatory cytokines IFNγ, TNFα, IL-1β, IL-2, IL5, IL12βp40 and IL-15 were altered as were the chemokines MIP-1 and RANTES and the anti-inflammatory cytokine IL-13. Increases in IFNγ and TNFα were seen in the serum of mice exposed to TBT for less than 24 h. Levels of IL1β, IL-12 βp40, IL-5 and IL-15 were also modulated in mouse serum, depending on the specific experiment and exposure level. IL-2 was consistently decreased in mouse serum when animals were exposed to TBT. There were also TBT-induced increases in MIP-1β, RANTES and IL-13. These results from human and murine samples clearly suggest that TBT exposures modulate the secretion inflammatory cytokines.

Hexachlorobenzene sources, levels and human exposure in the environment of China

NARCIS (Netherlands)

Wang, G.; Lu, Y.L.; Han, Jingyi; Luo, W.; Shi, Y.J.; Wang, T.Y.; Sun, Y.M.

2010-01-01

This article summarizes the published scientific data on sources, levels and human exposure of hexachlorobenzene (HCB) in China. Potential sources of unintended HCB emission were assessed by production information, emission factors and environmental policies. HCB was observed in various

Seasonal variations of radon and the radiation exposure levels in Nerja cave, Spain

International Nuclear Information System (INIS)

Duenas, C.; Fernandez, M.C.; Canete, S.; Perez, M.; Gordo, E.

2011-01-01

222 Rn concentrations in the air in Nerja cave (Spain) (3 o 52'35''W 36 o 43'50''N) were measured by continuous monitoring using Alpha-Guard, Genitron instrument equipment. The 222 Rn measurements were carried out for a complete annual cycle in the different halls: Vestibule hall from July 2003 to June 2004, Ballet hall from July 2004 to June 2005 and Mirador hall from July 2005 to June 2006. Starting from the entrance of the cave we successively find the Vestibule hall, the Ballet hall and the Mirador hall. The range of 222 Rn levels were of 8-627 Bq m -3 for the Vestibule hall, 28-575 Bq m -3 for the Ballet hall and 38-578 Bq m -3 for the Mirador. The aim of this study was to detect seasonal variation patterns of 222 Rn concentrations. The seasonal variations of 222 Rn concentrations are discussed in relation to various meteorological factors measured inside and outside the cave. The radiation exposure levels for workers and tourists with different equilibrium factors have been evaluated. The radiation exposure levels for workers and tourists only represent a low percentage of the exposure guides for the general population. - Highlights: → The aim of the study was to detect seasonal variation of 222 Rn concentrations. → 222 Rn concentrations in the air-cave were measured by continuous monitoring. → The 222 Rn measurements were carried out in the different halls of the cave. → The radiation exposure levels for workers and tourists have been evaluated.

Technological Aspects: High Voltage

International Nuclear Information System (INIS)

Faircloth, D C

2013-01-01

This paper covers the theory and technological aspects of high-voltage design for ion sources. Electric field strengths are critical to understanding high-voltage breakdown. The equations governing electric fields and the techniques to solve them are discussed. The fundamental physics of high-voltage breakdown and electrical discharges are outlined. Different types of electrical discharges are catalogued and their behaviour in environments ranging from air to vacuum are detailed. The importance of surfaces is discussed. The principles of designing electrodes and insulators are introduced. The use of high-voltage platforms and their relation to system design are discussed. The use of commercially available high-voltage technology such as connectors, feedthroughs and cables are considered. Different power supply technologies and their procurement are briefly outlined. High-voltage safety, electric shocks and system design rules are covered. (author)

Voltage Management in Unbalanced Low Voltage Networks Using a Decoupled Phase-Tap-Changer Transformer

DEFF Research Database (Denmark)

Coppo, Massimiliano; Turri, Roberto; Marinelli, Mattia

2014-01-01

The paper studies a medium voltage-low voltage transformer with a decoupled on load tap changer capability on each phase. The overall objective is the evaluation of the potential benefits on a low voltage network of such possibility. A realistic Danish low voltage network is used for the analysis...

Automatic voltage imbalance detector

Science.gov (United States)

Bobbett, Ronald E.; McCormick, J. Byron; Kerwin, William J.

1984-01-01

A device for indicating and preventing damage to voltage cells such as galvanic cells and fuel cells connected in series by detecting sequential voltages and comparing these voltages to adjacent voltage cells. The device is implemented by using operational amplifiers and switching circuitry is provided by transistors. The device can be utilized in battery powered electric vehicles to prevent galvanic cell damage and also in series connected fuel cells to prevent fuel cell damage.

Engineering of a genetically encodable fluorescent voltage sensor exploiting fast Ci-VSP voltage-sensing movements.

Directory of Open Access Journals (Sweden)

Alicia Lundby

2008-06-01

Full Text Available Ci-VSP contains a voltage-sensing domain (VSD homologous to that of voltage-gated potassium channels. Using charge displacement ('gating' current measurements we show that voltage-sensing movements of this VSD can occur within 1 ms in mammalian membranes. Our analysis lead to development of a genetically encodable fluorescent protein voltage sensor (VSFP in which the fast, voltage-dependent conformational changes of the Ci-VSP voltage sensor are transduced to similarly fast fluorescence read-outs.

Trends in x-ray photography and patient exposure dose

International Nuclear Information System (INIS)

Orito, Takeo; Sanada, Shigeru; Maekawa, Ryuichi; Koshida, Kichiro; Hiraki, Tatsunosuke

1980-01-01

The exposure doses of patients in X-ray photography are influenced by such technological factors as X-ray tube voltage, filter, sensitizing screen, film and grid. Survey by questionnnaire was made previously in 1973 on the above factors. The trends five years after were surveyed similarly, in connection with the exposure doses of patients. Questionnaires were sent to 200 radiation technicians, and 121 (60.5%) answered the survey in March, 1979. The results in the cases of simple X-ray photography and obstetric, infant and breast X-ray photographings are described. X-ray tube voltage is generally on the increase. In the sensitizing screens, exposure doses are fairly decreased due to the use of improved intensifying screen (LT-II). In the grid, the ratio 8 : 1 is used more than 5 : 1. In the usage of additional filters and in the distance of photography, improvements are desired. (J.P.N.)

Galvanizing industry: evaluation of exposure levels using biomonitors

International Nuclear Information System (INIS)

Menezes, Maria Angela de B.C.; Sabino, Claudia de V.S.; Amaral, Angela Maria; Mattos, Silvania V. de M.; S. Filho, Serafim; Maia, Elene Cristina P.

1999-01-01

In Brazil, statistical surveys concerning occupational diseases refer to accidents and damages. The surveys do not refer to the occupational diseases developed through long exposures to hazardous work conditions, involving physical risk and toxic chemical substances. The Program of Medical Control of Occupational Health determines the Maximum Biological Levels Allowed and the Values of Normality References. But concerning metal and toxic inorganic, values of only few elements are established. In Belo Horizonte and surroundings areas, which is an important industrial centre in the country, there are different industries distributed over various areas. There are about 80 galvanizing industries which are responsible for the majority of the metal contamination hospitalities. A preliminary sampling was performed in order to conduct a survey of the exposures to elements related to occupational diseases in galvanizing industry. The preliminary results for toxic and non-toxic elements obtained using hair and fingernails as biomonitors are shown. The K 0 parametric neutron activation analysis method was applied and the elements determined were: Ag, Al, Au, Cl, Co, Cr, Cu, Fe, I, Mn, Na, Ti, V, Ta, and Zn. (author)

Guidelines on radiation exposure levels for emergency situations

International Nuclear Information System (INIS)

1992-07-01

This document provides guidelines for establishing occupational exposure levels for undertaking actions in emergency situations resulting from a nuclear accident. There are three categories of exposed persons identifiable in relation to the circumstances under which they receive exposures resulting from an accident: (i) emergency workers exposed while undertaking urgent corrective actions; (ii) workers exposed while undertaking subsequent remedial actions, including countermeasures to protect the public; (iii) persons living in an environment contaminated by a nuclear accident. Although no dose limit can be easily stated for the first category, doses should be kept below 0.5 Sv. For the second category, normal dose limits would apply with a maximum of 0.05 Sv in a given year; however, in some circumstances where a few key experts are required doses up to 0.1 Sv could be permitted. For the third category the approach to be taken is to apply the ICRP's concept of dose constraint - a fraction of the worker's dose limit, but above the public dose limit. (L.L.) (6 refs., tab.)

Low levels of vitamin D poorly responsive to daylight exposure in patients with therapy-resistant schizophrenia.

Science.gov (United States)

Bogers, Jan P.A.M.; Bostoen, Tijmen; Broekman, Theo G.

2016-01-01

Low vitamin D levels are associated with schizophrenia, but the possible association between vitamin D levels and illness severity or duration of exposure to daylight has barely been investigated. To compare vitamin D levels in therapy-refractory severely ill schizophrenia patients and members of staff. To investigate the influence of daylight exposure on vitamin D levels in patients. Vitamin D was measured in patients with therapy-resistant schizophrenia in April, after the winter, and in patients and staff members in June, after an exceptionally sunny spring. Vitamin D levels in April and June were compared in patients, and levels in June were compared in patients and staff. The influence of daylight was taken into account by comparing the time patients spent outdoors during the day with the recommended minimum time for adequate vitamin D synthesis, and by comparing time spent outdoors in patients and staff. Patients had high rates of vitamin D deficiency (79-90%) and lower levels of vitamin D than staff members (p vitamin D levels did not normalize, despite the considerably longer than recommended exposure of the skin to daylight (p vitamin D deficiency of therapy-resistant schizophrenia patients is pronounced and cannot be explained by differences in skin pigmentation or by an inactive, indoor lifestyle on the ward. Even theoretically sufficient exposure of the patients to daylight did not ameliorate the low vitamin D levels. While vitamin D deficiency probably plays a role in somatic health problems, it may also play a role in schizophrenia. Interestingly, exposure to daylight during an unusually sunny spring was not sufficient to correct the vitamin D deficiency seen in the patients. This emphasizes the need to measure and correct vitamin D levels in these patients.

Hierarchical Control Scheme for Voltage Harmonics Compensation in an Islanded Droop-Controlled Microgrid

DEFF Research Database (Denmark)

Savaghebi, Mehdi; Guerrero, Josep M.; Jalilian, Alireza

2011-01-01

In this paper, a microgrid hierarchical control scheme is proposed which includes primary and secondary control levels. The primary level comprises distributed generators (DGs) local controllers. The local controller mainly consists of active and reactive power controllers, voltage and current...... controllers, and virtual impedance loop. A novel virtual impedance structure is proposed to achieve proper sharing of non-fundamental power among the microgrid DGs. The secondary level is designed to manage compensation of voltage harmonics at the microgrid load bus (LB) to which the sensitive loads may...... be connected. Also, restoration of LB voltage amplitude and microgrid frequency to the rated values is directed by the secondary level. These functions are achieved by sending proper control signals to the local controllers. The simulation results show the effectiveness of the proposed control scheme....

On-chip high-voltage generator design design methodology for charge pumps

CERN Document Server

Tanzawa, Toru

2016-01-01

This book provides various design techniques for switched-capacitor on-chip high-voltage generators, including charge pump circuits, regulators, level shifters, references, and oscillators.  Readers will see these techniques applied to system design in order to address the challenge of how the on-chip high-voltage generator is designed for Flash memories, LCD drivers, and other semiconductor devices to optimize the entire circuit area and power efficiency with a low voltage supply, while minimizing the cost.  This new edition includes a variety of useful updates, including coverage of power efficiency and comprehensive optimization methodologies for DC-DC voltage multipliers, modeling of extremely low voltage Dickson charge pumps, and modeling and optimum design of AC-DC switched-capacitor multipliers for energy harvesting and power transfer for RFID.

Influence of different exposure modes on image quality and radiation dose in digital mammography

International Nuclear Information System (INIS)

Liu Jie; Wang Xia; Li Xiaokang; Liu Peifang

2013-01-01

Objective: To evaluate the effect of different exposure modes on radiation dose and image quality in digital mammography, and to explore how to reduce patient's radiation injury by choosing proper exposure mode and exposure conditions without sacrifice image quality. Methods: A breast phantom was exposed by using automatic exposure mode (60 mAs, 28 k/V) and manual exposure modes (37.5 to 70 mAs range, 24 to 32 kV range) respectively. Same oppression thickness and pressure were set for all modes. The average glandular dose (AGD), entrance surface dose (ESD), and image quality score according to American College of Radiology (ACR) criteria were recorded for each image. Kruskal Wallis test was used to compare the image quality scores between automatic and manual modes. All statistic analyses were performed by using SPSS17.0. Results: Compared to automatic exposure mode (60 mAs, 28 k/V), the overall score of image quality of manual modes (45 to 70 mAs range, 26 to 32 kV range) had no significant difference. Both ESD and ACD decreased 26.1% and increased 15.4% when the tube loading was changed from 60 mAs to 45 mAs and 70 mAs respectively. The ESD and ACD decreased 22.6%, 28.2% and increased 47.0%, 62.7% when the tube voltage was changed from 28 kV to 26 kV and 32 kV respectively. Conclusion: When the image quality reaches to a certain level, it will not be raised by a higher photographic condition. Without sacrifice image quality, the tube loading and tube voltage can be manually decreased to reduce radiation dose. (authors)

Electrocardiogram voltage discordance: Interpretation of low QRS voltage only in the precordial leads.

Science.gov (United States)

Kim, Diana H; Verdino, Ralph J

To define clinical correlates of low voltage isolated to precordial leads on the surface electrocardiogram (ECG). Low voltage (V) on the ECG is defined as QRS Vvoltage isolated to the precordial leads with normal limb lead voltages is unclear. Twelve-lead ECGs with QRS V>5mm in one or more limb leads and voltage was found in 256 of 150,000 ECGs (~0.2%). 50.4% of patients had discordant ECGs that correlated with classic etiologies, with a higher incidence of LV dilation in those with classic etiologies than those without. Low precordial voltage is associated with classic etiologies and LV dilation. Copyright © 2017 Elsevier Inc. All rights reserved.

Excitation of high energy levels under laser exposure of suspensions of nanoparticles in liquids

Energy Technology Data Exchange (ETDEWEB)

Shafeev, G.A. [Wave Research Center of A.M. Prokhorov General Physics Institute, 38, Vavilov Street, 119991 Moscow (Russian Federation)], E-mail: shafeev@kapella.gpi.ru; Simakin, A.V. [Wave Research Center of A.M. Prokhorov General Physics Institute, 38, Vavilov Street, 119991 Moscow (Russian Federation); Bozon-Verduraz, F. [ITODYS, UMR CNRS 7086, Universite Paris 7-Denis Diderot, 2, place Jussieu, 75251 Paris cedex 05 (France); Robert, M. [Laboratoire d' Electrochimie Moleculaire, UMR CNRS 7591, Universite Paris 7 Denis Diderot, 2, place Jussieu, 75251 Paris cedex 05 (France)

2007-12-15

Laser exposure of suspensions of nanoparticles in liquids leads to excitation of high energy levels in both liquid and nanoparticle material. The emission spectrum of the colloidal solution under exposure of a suspension metallic nanoparticles in water to radiation of a Nd:YAG laser of a picosecond range of pulse duration is discussed. Excitation of nuclear energy levels and neutron release is experimentally studied on the model system of transmutation of Hg into Au that occurs under exposure of Hg nanodrops suspended in D{sub 2}O. The proposed mechanism involves: (i) emission of X-ray photons by Hg nanoparticles upon laser exposure, leading to neutron release from D{sub 2}O, (ii) initiation of Hg {yields} Au transmutation by the capture of neutrons. The effect of transmutation is more pronounced using {sup 196}Hg isotope instead of Hg of natural isotope composition. The influence of laser pulse duration on the degree of transmutation (from fs through ns range) is discussed.

Development of a source-exposure matrix for occupational exposure assessment of electromagnetic fields in the INTEROCC study.

Science.gov (United States)

Vila, Javier; Bowman, Joseph D; Figuerola, Jordi; Moriña, David; Kincl, Laurel; Richardson, Lesley; Cardis, Elisabeth

2017-07-01

To estimate occupational exposures to electromagnetic fields (EMF) for the INTEROCC study, a database of source-based measurements extracted from published and unpublished literature resources had been previously constructed. The aim of the current work was to summarize these measurements into a source-exposure matrix (SEM), accounting for their quality and relevance. A novel methodology for combining available measurements was developed, based on order statistics and log-normal distribution characteristics. Arithmetic and geometric means, and estimates of variability and maximum exposure were calculated by EMF source, frequency band and dosimetry type. The mean estimates were weighted by our confidence in the pooled measurements. The SEM contains confidence-weighted mean and maximum estimates for 312 EMF exposure sources (from 0 Hz to 300 GHz). Operator position geometric mean electric field levels for radiofrequency (RF) sources ranged between 0.8 V/m (plasma etcher) and 320 V/m (RF sealer), while magnetic fields ranged from 0.02 A/m (speed radar) to 0.6 A/m (microwave heating). For extremely low frequency sources, electric fields ranged between 0.2 V/m (electric forklift) and 11,700 V/m (high-voltage transmission line-hotsticks), whereas magnetic fields ranged between 0.14 μT (visual display terminals) and 17 μT (tungsten inert gas welding). The methodology developed allowed the construction of the first EMF-SEM and may be used to summarize similar exposure data for other physical or chemical agents.

Effect of neutron irradiation on the breakdown voltage of power MOSFET's

International Nuclear Information System (INIS)

Hasan, S.M.Y.; Kosier, S.L.; Schrimpf, R.D.; Galloway, K.F.

1994-01-01

The effect of neutron irradiation on power metal-oxide-semiconductor field effect transistor (power MOSFET) breakdown voltage has been investigated. Transistors with various breakdown voltage ratings were irradiated in a TRIGA nuclear reactor with cumulative fluence levels up to 5 x 10 14 neutrons/cm 2 (1 MeV equivalent). Noticeable increases in the breakdown voltages are observed in n-type MOSFET's after 10 13 neutrons/cm 2 and in p-type MOSFETs after 10 12 neutrons/cm 2 . An increase in breakdown voltage of as much as 30% is observed after 5 x 10 14 neutrons/cm 2 . The increase in breakdown voltage is attributed to the neutron-irradiation-induced defects which decrease the mean free path and trap majority carriers in the space charge region. The effect of positive trapped oxide charge due to concomitant gamma radiation and the effect of the termination structure on the increase in breakdown voltage are considered. An empirical model is presented to predict the value of the breakdown voltage as a function of neutron fluence

PMU-Aided Voltage Security Assessment for a Wind Power Plant: Preprint

Energy Technology Data Exchange (ETDEWEB)

Jiang, H.; Zhang, Y. C.; Zhang, J. J.; Muljadi, E.

2015-04-08

Because wind power penetration levels in electric power systems are continuously increasing, voltage stability is a critical issue for maintaining power system security and operation. The traditional methods to analyze voltage stability can be classified into two categories: dynamic and steady-state. Dynamic analysis relies on time-domain simulations of faults at different locations; however, this method needs to exhaust faults at all locations to find the security region for voltage at a single bus. With the widely located phasor measurement units (PMUs), the Thevenin equivalent matrix can be calculated by the voltage and current information collected by the PMUs. This paper proposes a method based on a Thevenin equivalent matrix to identify system locations that will have the greatest impact on the voltage at the wind power plant’s point of interconnection. The number of dynamic voltage stability analysis runs is greatly reduced by using the proposed method. The numerical results demonstrate the feasibility, effectiveness, and robustness of the proposed approach for voltage security assessment for a wind power plant.

Lower power by voltage stacking : a fine-grained system design approach

NARCIS (Netherlands)

Blutman, K.; Kapoor, A.; Martinez, J.G.; Fatemi, S.H.; Pineda de Gyvez, J.

2016-01-01

Stacking voltage domains on top of each other is a design approach that is getting the attention of engineering communities due to the implicit high efficiency of the power delivery. Previous works have shown voltage stacking at the core level only. In this paper we present a more involved approach

Changes in peripheral nervous system activity produced in rats by prenatal exposure to carbon monoxide

Energy Technology Data Exchange (ETDEWEB)

Carratu, M.R. (Inst. of Pharmacology, Bari Univ. (Italy)); Renna, G. (Inst. of Pharmacology, Bari Univ. (Italy)); Giustino, A. (Inst. of Pharmacology, Bari Univ. (Italy)); De Salvia, M.A. (Inst. of Pharmacology, Bari Univ. (Italy)); Cuomo, V. (Inst. of Pharmacology, Bari Univ. (Italy))

1993-06-01

The present experiments were designed to investigate whether alterations of peripheral nervous system activity may be produced in male Wistar rats by prenatal exposure (from day 0 to day 20 of pregnancy) to relatively low levels of CO (75 and 150 ppm). The voltage clamp analysis of ionic currents recorded from sciatic nerve fibres showed that prenatal exposure to CO produced modifications of sodium current properties. In particular, in 40-day-old rats exposed to CO (75 and 150 ppm) during gestation, the inactivation kinetics of transient sodium current were significantly slowed. Analysis of the potential dependence of steady-state Na inactivation, h[sub [infinity

Does apartment's distance to an in-built transformer room predict magnetic field exposure levels?

Science.gov (United States)

Huss, Anke; Goris, Kelly; Vermeulen, Roel; Kromhout, Hans

2013-01-01

It has been shown that magnetic field exposure in apartments located directly on top or adjacent to transformer rooms is higher compared with exposure in apartments located further away from the transformer rooms. It is unclear whether this also translates into exposure contrast among individuals living in these apartments. We performed spot measurements of magnetic fields in 35 apartments in 14 apartment buildings with an in-built transformer and additionally performed 24-h personal measurements in a subsample of 24 individuals. Apartments placed directly on top of or adjacent to a transformer room had on average exposures of 0.42 μT, apartments on the second floor on top of a transformer room, or sharing a corner or edge with the transformer room had 0.11 μT, and apartments located further away from the transformer room had levels of 0.06 μT. Personal exposure levels were approximately a factor 2 lower compared with apartment averages, but still showed exposure contrasts, but only for those individuals who live in the apartments directly on top or adjacent to a transformer room compared with those living further away, with 0.23 versus 0.06 μT for personal exposure when indoors, respectively. A classification of individuals into 'high' and 'low' exposed based on the location of their apartment within a building with an in-built transformer is possible and could be applied in future epidemiological studies.

Sex specific response in cholesterol level in zebrafish (Danio rerio) after long-term exposure of difenoconazole

International Nuclear Information System (INIS)

Mu, Xiyan; Wang, Kai; Chai, Tingting; Zhu, Lizhen; Yang, Yang; Zhang, Jie; Pang, Sen; Wang, Chengju; Li, Xuefeng

2015-01-01

Difenoconazole is a widely used triazole fungicide, its extensive application may potentially cause toxic effects on non-target organisms. To investigate the effect of difenoconazole on cholesterol content and related mechanism, adult zebrafish were exposed to environmental related dosage (0.1, 10 and 500 μg/L) difenoconazole. The body weight and hepatic total cholesterol (TCHO) level was tested at 7, 15 and 30 days post exposure (dpe). The expressions of eight cholesterol synthesis genes and one cholesterol metabolism gene were assessed via Quantitative PCR method. The significant decrease of TCHO level in male zebrafish liver was observed at 15 and 30 dpe, which was accompanied by apparent hepatic cholesterol-genesis genes expression decline. In comparison with males, female zebrafish showed different transcription modification of tested genes, and the cholesterol content maintain normal level during the whole exposure. - Highlights: • Difenoconazle could reduce TCHO level in male zebrafish liver. • Difenoconazole could inhibit sterol-genesis genes expression in male zebrafish. • Female zebrafish didn't show obvious change of TCHO level after exposure. • Difenoconazole could inhibit body weight of both male and female zebrafish. - Difenoconazle could reduce cholesterol level and sterol-genesis genes expression in male zebrafish. While female zebrafish showed no obvious cholesterol content change during exposure

Blood morphology and the levels of selected cytokines related to hematopoiesis in occupational short-term exposure to lead

International Nuclear Information System (INIS)

Dobrakowski, Michał; Boroń, Marta; Czuba, Zenon P.; Birkner, Ewa; Chwalba, Artur; Hudziec, Edyta; Kasperczyk, Sławomir

2016-01-01

The aim of the study was to investigate the influence of a short-term exposure to lead on the blood morphology and the levels of selected cytokines related to hematopoiesis in occupationally exposed workers. The study population included 37 males occupationally exposed to lead for 36 to 44 days. Their blood lead level raised from 10.7 ± 7.67 μg/dl at baseline to the level of 49.1 ± 14.1 μg/dl at the end of the study. The level of hemoglobin and values of MCH and MCHC were decreased due to a short-term exposure to lead by 2%, 2%, and 1%, respectively. The counts of WBC, LYM, and MXD increased significantly by 5%, 7%, and 35%. Similarly, the count of PLT increased by 7%, while PDW, MPV, and P-LCR decreased by 6%, 3%, and 9%, respectively. The levels of IL-7, G-CSF, HGF, PDGF AB/BB, SCF, and PECAM-1, decreased significantly by 30%, 33%, 8%, 30%, 25%, and 20%, respectively. A short-term occupational exposure to lead results in a decreased hemoglobin level and increased counts of WBC and PLT. Changes in counts and proportions of different types of leukocytes and decreased values of PLT indices, such as PDW, MPV, and P-LCR, due to the subacute lead-exposure may be associated with lead-induced decreased levels of cytokines related to hematopoiesis, including SCF, G-CSF, IL-7, and PDGF. - Highlights: • Subacute exposure to lead results in a decreased hemoglobin level. • Subacute exposure to lead results in increased counts of WBC and PLT. • Subacute exposure to lead decreases the levels of SCF, G-CSF, IL-7, and PDGF.

Blood morphology and the levels of selected cytokines related to hematopoiesis in occupational short-term exposure to lead

Energy Technology Data Exchange (ETDEWEB)

Dobrakowski, Michał, E-mail: michal.dobrakowski@poczta.fm [Department of Biochemistry, School of Medicine with the Division of Dentistry, Medical University of Silesia, ul. Jordana 19, 41-808 Zabrze (Poland); Boroń, Marta [Institute of Occupational Medicine and Environmental Health in Sosnowiec, ul. Kościelna 13, 41-200 Sosnowiec (Poland); Czuba, Zenon P. [Department of Microbiology and Immunology, School of Medicine with the Division of Dentistry, Medical University of Silesia, ul. Jordana 19, 41-808 Zabrze (Poland); Birkner, Ewa [Department of Biochemistry, School of Medicine with the Division of Dentistry, Medical University of Silesia, ul. Jordana 19, 41-808 Zabrze (Poland); Chwalba, Artur [SP ZOZ Municipal Hospital, Department of Internal Medicine, ul. Strzelców Bytomskich 11, 41-500 Chorzów (Poland); Hudziec, Edyta; Kasperczyk, Sławomir [Department of Biochemistry, School of Medicine with the Division of Dentistry, Medical University of Silesia, ul. Jordana 19, 41-808 Zabrze (Poland)

2016-08-15

The aim of the study was to investigate the influence of a short-term exposure to lead on the blood morphology and the levels of selected cytokines related to hematopoiesis in occupationally exposed workers. The study population included 37 males occupationally exposed to lead for 36 to 44 days. Their blood lead level raised from 10.7 ± 7.67 μg/dl at baseline to the level of 49.1 ± 14.1 μg/dl at the end of the study. The level of hemoglobin and values of MCH and MCHC were decreased due to a short-term exposure to lead by 2%, 2%, and 1%, respectively. The counts of WBC, LYM, and MXD increased significantly by 5%, 7%, and 35%. Similarly, the count of PLT increased by 7%, while PDW, MPV, and P-LCR decreased by 6%, 3%, and 9%, respectively. The levels of IL-7, G-CSF, HGF, PDGF AB/BB, SCF, and PECAM-1, decreased significantly by 30%, 33%, 8%, 30%, 25%, and 20%, respectively. A short-term occupational exposure to lead results in a decreased hemoglobin level and increased counts of WBC and PLT. Changes in counts and proportions of different types of leukocytes and decreased values of PLT indices, such as PDW, MPV, and P-LCR, due to the subacute lead-exposure may be associated with lead-induced decreased levels of cytokines related to hematopoiesis, including SCF, G-CSF, IL-7, and PDGF. - Highlights: • Subacute exposure to lead results in a decreased hemoglobin level. • Subacute exposure to lead results in increased counts of WBC and PLT. • Subacute exposure to lead decreases the levels of SCF, G-CSF, IL-7, and PDGF.

In situ scanning tunnelling microscopy of redox molecules. Coherent electron transfer at large bias voltages

DEFF Research Database (Denmark)

Zhang, Jingdong; Kuznetsov, A.M.; Ulstrup, Jens

2003-01-01

Theories of in situ scanning tunnelling microscopy (STM) of molecules with redox levels near the substrate and tip Fermi levels point to 'spectroscopic' current-overpotential features. Prominent features require a narrow 'probing tip', i.e. a small bias voltage, eV(bias), compared...... a broad tunnelling current-overpotential range at a constant (large) bias voltage of +0.2 V. The current is found to be constant over a 0.25 V overpotential range, which covers roughly the range where the oxidised and reduced redox levels are located within the energy tip. STM contrast and apparent...... of previous theoretical work on in situ STM of redox molecules, to large bias voltages, \\eV(bias)\\ > E-r. Large bias voltages give tunnelling contrasts independent of the overpotential over a broad range, as both the oxidised and reduced redox levels are located within the 'energy tip' between the substrate...

Low-Voltage Consumption Coordination for Loss Minimization and Voltage Control

DEFF Research Database (Denmark)

Juelsgaard, Morten; Sloth, Christoffer; Wisniewski, Rafal

2014-01-01

This work presents a strategy for minimizing active power losses in low-voltage grids, by coordinating the consumption of electric vehicles and power generation from solar panels. We show that minimizing losses, also reduces voltage variations, and illustrate how this may be employed for increasing...

Mercury exposure may suppress baseline corticosterone levels in juvenile birds.

Science.gov (United States)

Herring, Garth; Ackerman, Joshua T; Herzog, Mark P

2012-06-05

Mercury exposure has been associated with a wide variety of negative reproductive responses in birds, however few studies have examined the potential for chick impairment via the hypothalamic-pituitary-adrenal (HPA) axis. The HPA axis regulates corticosterone levels during periods of stress. We examined the relationship between baseline fecal corticosterone metabolite concentrations and mercury concentrations in down feathers of recently hatched (feathers (decreasing by 45% across the range of observed mercury concentrations) while accounting for stronger positive correlations between corticosterone concentrations and colony nest abundance and date. These results indicate that chronic mercury exposure may suppress baseline corticosterone concentrations in tern chicks and suggests that a juvenile bird's ability to respond to stress may be reduced via the downregulation of the HPA axis.

DC-link Voltage Control to Compensate Voltage Deviation for PV–BESSs Integrated System in Low-Voltage (LV Networks

Directory of Open Access Journals (Sweden)

Lee Gyu-sub

2016-01-01

Full Text Available The exhaustion of fossil fuel and the greenhouse gas emission are one of the most significant energy and environmental issues, respectively. Photovoltaic (PV generators and battery energy storage systems (BESSs have been significantly increased for recent years. The BESSs are mainly used for smoothing active power fluctuation of the PV. In this paper, PV–BESSs integration of two DC/DC converters and one AC/DC converter is investigated and DC-link voltage control to compensate the AC voltage deviation is proposed for the PV‒BESS system in low-voltage (LV networks.

1-Hydroxypyrene Levels in Blood Samples of Rats After Exposure to Generator Fumes

Science.gov (United States)

Ifegwu, Clinton; Igwo-Ezikpe, Miriam N.; Anyakora, Chimezie; Osuntoki, Akinniyi; Oseni, Kafayat A.; Alao, Eragbae O.

2013-01-01

Polynuclear Aromatic Hydrocarbons (PAHs) are a major component of fuel generator fumes. Carcinogenicity of these compounds has long been established. In this study, 37 Swiss albino rats were exposed to generator fumes at varied distances for 8 hours per day for a period of 42 days and the level of 1-hydroxypyrene in their blood was evaluated. This study also tried to correlate the level of blood 1-hyroxypyrene with the distance from the source of pollution. Plasma was collected by centrifuging the whole blood sample followed by complete hydrolysis of the conjugated 1-hydroxypyrene glucuronide to yield the analyte of interest, 1-hydroxypyrene, which was achieved using beta glucuronidase. High performance liquid chromatography (HPLC) with UV detector was used to determine the 1-hydroxypyrene concentrations in the blood samples. The mobile phase was water:methanol (12:88 v/v) isocratic run at the flow rate of 1.2 mL/min with CI8 stationary phase at 250 nm. After 42 days of exposure, blood concentration level of 1-hydroxypyrene ranged from 34 μg/mL to 26.29 μg/mL depending on the distance from source of exposure. The control group had no 1-hydroxypyrene in their blood. After the period of exposure, percentage of death correlated with the distance from the source of exposure. Percentage of death ranged from 56% to zero depending on the proximity to source of pollution. PMID:24179393

Health effects of subchronic exposure to environmental levels of diesel exhaust.

Science.gov (United States)

Reed, M D; Gigliotti, A P; McDonald, J D; Seagrave, J C; Seilkop, S K; Mauderly, J L

2004-04-01

Diesel exhaust is a public health concern and contributor to both ambient and occupational air pollution. As part of a general health assessment of multiple anthropogenic source emissions conducted by the National Environmental Respiratory Center (NERC), a series of health assays was conducted on rats and mice exposed to environmentally relevant levels of diesel exhaust. This article summarizes the study design and exposures, and reports findings on several general indicators of toxicity and carcinogenic potential. Diesel exhaust was generated from a commonly used 2000 model 5.9-L, 6-cylinder turbo diesel engine operated on a variable-load heavy-duty test cycle burning national average certification fuel. Animals were exposed to clean air (control) or four dilutions of whole emissions based on particulate matter concentration (30, 100, 300, and 1000 microg/m(3)). Male and female F344 rats and A/J mice were exposed by whole-body inhalation 6 h/day, 7 days/wk, for either 1 wk or 6 mo. Exposures were characterized in detail. Effects of exposure on clinical observations, body and organ weights, serum chemistry, hematology, histopathology, bronchoalveolar lavage, and serum clotting factors were mild. Significant exposure-related effects occurring in both male and female rats included decreases in serum cholesterol and clotting Factor VII and slight increases in serum gamma-glutamyl transferase. Several other responses met screening criteria for significant exposure effects but were not consistent between genders or exposure times and were not corroborated by related parameters. Carcinogenic potential as determined by micronucleated reticulocyte counts and proliferation of adenomas in A/J mice were unaffected by 6 mo of exposure. Parallel studies demonstrated effects on cardiac function and resistance to viral infection; however, the results reported here show few and only modest health hazards from subchronic or shorter exposures to realistic concentrations of

In utero exposure to benzene increases embryonic c-Myb and Pim-1 protein levels in CD-1 mice

International Nuclear Information System (INIS)

Wan, Joanne; Winn, Louise M.

2008-01-01

Benzene is a known human leukemogen, but its role as an in utero leukemogen remains controversial. Epidemiological studies have correlated parental exposure to benzene with an increased incidence of childhood leukemias. We hypothesize that in utero exposure to benzene may cause leukemogenesis by affecting the embryonic c-Myb/Pim-1 signaling pathway and that this is mediated by oxidative stress. To investigate this hypothesis, pregnant CD-1 mice were treated with either 800 mg/kg of benzene or corn oil (i.p.) on days 10 and 11 of gestation and in some cases pretreated with 25 kU/kg of PEG-catalase. Phosphorylated and total embryonic c-Myb and Pim-1 protein levels were assessed using Western blotting and maternal and embryonic oxidative stress were assessed by measuring reduced to oxidized glutathione ratios. Our results show increased oxidative stress at 4 and 24 h after exposure, increased phosphorylated Pim-1 protein levels 4 h after benzene exposure, and increased Pim-1 levels at 24 and 48 h after benzene exposure. Embryonic c-Myb levels were elevated at 24 h after exposure. PEG-catalase pretreatment prevented benzene-mediated increases in embryonic c-Myb and Pim-1 protein levels, and benzene-induced oxidative stress. These results support a role for ROS in c-Myb and Pim-1 alterations after in utero benzene exposure

Congestion management considering voltage security of power systems

International Nuclear Information System (INIS)

Esmaili, Masoud; Shayanfar, Heidar Ali; Amjady, Nima

2009-01-01

Congestion in a power network is turned up due to system operating limits. To relieve congestion in a deregulated power market, the system operator pays to market participants, GENCOs and DISCOs, to alter their active powers considering their bids. After performing congestion management, the network may be operated with a low security level because of hitting some flows their upper limit and some voltages their lower limit. In this paper, a novel congestion management method based on the voltage stability margin sensitivities is introduced. Using the proposed method, the system operator so alleviates the congestion that the network can more retain its security. The proposed method not only makes the system more secure after congestion management than other methods already presented for this purpose but also its cost of providing security is lower than the earlier methods. Test results of the proposed method along with the earlier ones on the New-England test system elaborate the efficiency of the proposed method from the viewpoint of providing a better voltage stability margin and voltage profile as well as a lower security cost. (author)

Prenatal exposure to lead in Spain: Cord blood levels and associated factors

Energy Technology Data Exchange (ETDEWEB)

Llop, Sabrina, E-mail: llop_sab@gva.es [Centre of Public Health Research (CSISP), Av Catalunya 21, 46020, Valencia (Spain); Carlos III Health Institute (ISCIII), 20220 Majadahonda, Madrid (Spain); CIBER de Epidemiologia y Salud Publica (CIBERESP), Doctor Aiguader 88, 8003 Barcelona (Spain); Aguinagalde, Xabier [Public Health Laboratory of Alava, Direccion de Salud Publica, Gobierno Vasco, Santiago 11, 01002, Vitoria-Gasteiz, Basque Country (Spain); Vioque, Jesus [CIBER de Epidemiologia y Salud Publica (CIBERESP), Doctor Aiguader 88, 8003 Barcelona (Spain); Universidad Miguel Hernandez, Av de Alicante KM 87, 03550, Sant Joan d' Alacant (Spain); Ibarluzea, Jesus [CIBER de Epidemiologia y Salud Publica (CIBERESP), Doctor Aiguader 88, 8003 Barcelona (Spain); Departamento de Sanidad Gobierno Vasco, Subdireccion de Salud Publica de Gipuzkoa, Avenida de Navarra 4, 20013 San Sebastian (Spain); Biodonostia, Instituto de Investigacion Biomedica, San Sebastian (Spain); Guxens, Monica [CIBER de Epidemiologia y Salud Publica (CIBERESP), Doctor Aiguader 88, 8003 Barcelona (Spain); Centre for Research of Environmental Epidemiology (CREAL), Doctor Aiguader 88, 8003 Barcelona (Spain); Municipal Institute of Medical Research (IMIM-Hospital del Mar), Doctor Aiguader 88, 8003 Barcelona (Spain); Casas, Maribel [Centre for Research of Environmental Epidemiology (CREAL), Doctor Aiguader 88, 8003 Barcelona (Spain); Municipal Institute of Medical Research (IMIM-Hospital del Mar), Doctor Aiguader 88, 8003 Barcelona (Spain); Murcia, Mario [Centre of Public Health Research (CSISP), Av Catalunya 21, 46020, Valencia (Spain); CIBER de Epidemiologia y Salud Publica (CIBERESP), Doctor Aiguader 88, 8003 Barcelona (Spain); Ruiz, Maria [Centre for Research of Environmental Epidemiology (CREAL), Doctor Aiguader 88, 8003 Barcelona (Spain); Municipal Institute of Medical Research (IMIM-Hospital del Mar), Doctor Aiguader 88, 8003 Barcelona (Spain); and others

2011-05-01

Introduction and Objective: Lead is a known neurotoxic. Fetuses and infants are very vulnerable to lead exposure, since their blood-brain barrier is not completely formed. Hence, there is an importance for monitoring of blood lead levels prenatally and during early infancy. The aim of this study is to evaluate the prenatal exposure to lead and its association with maternal factors in four population based mother-child cohorts in Spain. The present research was carried out within the framework of the INMA project INfancia y Medio Ambiente (Environment and Childhood). Methods: A total of 1462 pregnant women were recruited between 2004 and 2008. Lead was analyzed in a sample of cord blood by thermal decomposition, amalgation, and Atomic Absorption Spectrometry. Maternal sociodemographic, lifestyle and dietary factors were obtained by questionnaires during pregnancy. A multivariate logistic regression model was constructed. The dependent variable was a dichotomous lead level variable (detected vs no detected, i.e. {>=} vs < 2 {mu}g/dL). Results: A low percentage of cord blood samples with lead levels {>=} 2 {mu}g/dL were found (5.9%). Geometric mean and maximum were 1.06 {mu}g/dL and 19 {mu}g/dL, respectively. Smoking at the beginning of pregnancy, age, social class, weight gain during pregnancy, gravidity, and place of residence were the maternal factors associated with detectable cord blood lead levels. Mother's diet does not appear to be a determining factor of lead exposure. Nevertheless, daily intake of iron and zinc may act as a protective factor against having cord blood lead levels {>=} 2 {mu}g/dL. Conclusion: In the different regions of Spain taking part in this study, lead levels to which newborns are exposed are low. Mobilization of lead from bones may be the main contributor to the cord blood levels. - Research Highlights: {yields} Pb is a ubiquitous environmental pollutant with harmful effects on neurodevelopment. {yields} Cord blood Pb levels in

Prenatal exposure to lead in Spain: Cord blood levels and associated factors

International Nuclear Information System (INIS)

Llop, Sabrina; Aguinagalde, Xabier; Vioque, Jesus; Ibarluzea, Jesus; Guxens, Monica; Casas, Maribel; Murcia, Mario; Ruiz, Maria

2011-01-01

Introduction and Objective: Lead is a known neurotoxic. Fetuses and infants are very vulnerable to lead exposure, since their blood-brain barrier is not completely formed. Hence, there is an importance for monitoring of blood lead levels prenatally and during early infancy. The aim of this study is to evaluate the prenatal exposure to lead and its association with maternal factors in four population based mother-child cohorts in Spain. The present research was carried out within the framework of the INMA project INfancia y Medio Ambiente (Environment and Childhood). Methods: A total of 1462 pregnant women were recruited between 2004 and 2008. Lead was analyzed in a sample of cord blood by thermal decomposition, amalgation, and Atomic Absorption Spectrometry. Maternal sociodemographic, lifestyle and dietary factors were obtained by questionnaires during pregnancy. A multivariate logistic regression model was constructed. The dependent variable was a dichotomous lead level variable (detected vs no detected, i.e. ≥ vs < 2 μg/dL). Results: A low percentage of cord blood samples with lead levels ≥ 2 μg/dL were found (5.9%). Geometric mean and maximum were 1.06 μg/dL and 19 μg/dL, respectively. Smoking at the beginning of pregnancy, age, social class, weight gain during pregnancy, gravidity, and place of residence were the maternal factors associated with detectable cord blood lead levels. Mother's diet does not appear to be a determining factor of lead exposure. Nevertheless, daily intake of iron and zinc may act as a protective factor against having cord blood lead levels ≥ 2 μg/dL. Conclusion: In the different regions of Spain taking part in this study, lead levels to which newborns are exposed are low. Mobilization of lead from bones may be the main contributor to the cord blood levels. - Research Highlights: → Pb is a ubiquitous environmental pollutant with harmful effects on neurodevelopment. → Cord blood Pb levels in Spanish newborn are low in

Field angle dependence of voltage-induced ferromagnetic resonance under DC bias voltage

International Nuclear Information System (INIS)

Shiota, Yoichi; Miwa, Shinji; Tamaru, Shingo; Nozaki, Takayuki; Kubota, Hitoshi; Fukushima, Akio; Suzuki, Yoshishige; Yuasa, Shinji

2016-01-01

We studied the rectification function of microwaves in CoFeB/MgO-based magnetic tunnel junctions using voltage-induced ferromagnetic resonance (FMR). Our findings reveal that the shape of the structure of the spectrum depends on the rotation angle of the external magnetic field, providing clear evidence that FMR dynamics are excited by voltage-induced magnetic anisotropy changes. Further, enhancement of the rectified voltage was demonstrated under a DC bias voltage. In our experiments, the highest microwave detection sensitivity obtained was 350 mV/mW, at an RF frequency of 1.0 GHz and field angle of θ_H=80°, ϕ_H=0°. The experimental results correlated with those obtained via simulation, and the calculated results revealed the magnetization dynamics at the resonance state. - Highlights: • Examined voltage-induced ferromagnetic resonance (FMR) under various field angles. • FMR dynamics are excited by voltage-induced magnetic anisotropy changes. • Microwave detection sensitivity depends on input RF and elevation angle. • Microwave detection sensitivity=350 mV/mW at RF=1.0 GHz, θ_H=80°, ϕ_H=0°.

Comparative Study of Modulation Techniques for Two-Level Voltage Source Inverters

Directory of Open Access Journals (Sweden)

Barry W. Williams

2016-06-01

Full Text Available A detailed comparative study of modulation techniques for single and three phase dc-ac inverters is presented.  Sinusoidal Pulse Width Modulation, Triplen Sinusoidal Pulse Width Modulation, Space Vector Modulation, Selective Harmonic Elimination and Wavelet Modulation are assessed and compared in terms of maximum fundamental output, harmonic performance, switching losses and operational mode.  The presented modulation techniques are applied to single and three phase voltage source inverters and are simulated using SIMULINK.  The simulation results clarify the inverter performance achieved using the different modulations techniques.

Pulse-voltage fast generator

International Nuclear Information System (INIS)

Valeev, R.I.; Nikiforov, M.G.; Kharchenko, A.F.

1988-01-01

The design is described and the test results of a four-channel pulse-voltage generator with maximum output voltage 200 kV are presented. The measurement results of generator triggering time depending on the value and polarity of the triggering voltage pulse for different triggering circuits are presented. The tests have shown stable triggering of all four channels of the generator in the range up to 40 % from selfbreakdown voltage. The generator triggering delay in the given range is <25 ns, asynchronism in channel triggering is <±1 ns

Analysis of operating conditions of the voltage transformer

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Fastiy G. P.

2017-12-01

Full Text Available In electrical networks, constant monitoring of the electrical equipment operation is necessary. To accomplish this task, current transformers and voltage transformers (VT are used, on which the accuracy of electrical measurements, electricity metering, and the reliability of the emergency control system depend. The results of the analysis of the conditions for forming the magnetization of a voltage transformer in the mode with unilateral connection of overhead transmission lines, as well as variants of violations in the 110 kV network that may exist for a relatively long time have been presented. It should be noted that the considered network has its own peculiarities: the overhead transmission lines connected in series have a significant length and a low level of load, which may be a condition for the appearance of a transmission lines capacitive effect (the Ferranti effect, the latter can cause overvoltage. Overvoltage occurs when the operating modes are temporary in terms of operation, adverse combinations of network parameters take place, and can continue until the circuit and network modes change. Most often they appear in asymmetric modes, with short circuits to ground, etc. Asymmetric modes caused by incomplete-phase commutations and wire breaks on the overhead line, as well as wire breaks with subsequent disconnection of power transformers that can affect the voltage level on the VT have been considered. The possibility of VT magnetizing with a prolonged voltage rise in symmetric modes, namely, the manifestation of the Ferranti effect with various loads at substations up to complete switching-off and power transformers switching off has been investigated. The analysis of the measuring voltage transformer operating conditions has been based on materials provided by the "Kolenergo" services.

Elevated lead levels from e-waste exposure are linked to decreased olfactory memory in children.

Science.gov (United States)

Zhang, Bo; Huo, Xia; Xu, Long; Cheng, Zhiheng; Cong, Xiaowei; Lu, Xueling; Xu, Xijin

2017-12-01

Lead (Pb) is a developmental neurotoxicant and can cause abnormal development of the nervous system in children. Hence, the aim of this study was to investigate the effect of Pb exposure on child olfactory memory by correlating the blood Pb levels of children in Guiyu with olfactory memory tests. We recruited 61 preschool children, 4- to 7-years of age, from Guiyu and 57 children from Haojiang. The mean blood Pb level of Guiyu children was 9.40 μg/dL, significantly higher than the 5.04 μg/dL mean blood Pb level of Haojiang children. In addition, approximately 23% of Guiyu children had blood Pb levels exceeding 10.00 μg/dL. The correlation analysis showed that blood Pb levels in children highly correlated with e-waste contact (r s  = 0.393). Moreover, the mean concentration of serum BDNF in Guiyu children (35.91 ng/ml) was higher than for Haojiang (28.10 ng/ml) and was positively correlated with blood Pb levels. Both item and source olfactory memory tests at 15 min, 5 h and 24 h after odor exposure showed that scores were lower in Guiyu children indicative of reduced olfactory memory in Guiyu children. Olfactory memory tests scores negatively correlated with blood Pb and serum BDNF levels, but were positively associated with parental education levels. At the same time, scores of both tests on children in the high blood Pb level group (blood Pb levels > 5.00 μg/dL) were lower than those in the low blood Pb level group (blood Pb levels ≤ 5.00 μg/dL), implying that Pb exposure decreases olfactory memory in children. Our findings suggest that Pb exposure in e-waste recycling and dismantling areas could result in an increase in serum BDNF level and a decrease in child olfactory memory, in addition, BDNF might be involved in olfactory memory impairment. Copyright © 2017 Elsevier Ltd. All rights reserved.

A Novel Index for Online Voltage Stability Assessment Based on Correlation Characteristic of Voltage Profiles

Directory of Open Access Journals (Sweden)

M. R. Aghamohammadi

2011-06-01

Full Text Available Abstract: Voltage instability is a major threat for security of power systems. Preserving voltage security margin at a certain limit is a vital requirement for today’s power systems. Assessment of voltage security margin is a challenging task demanding sophisticated indices. In this paper, for the purpose of on line voltage security assessment a new index based on the correlation characteristic of network voltage profile is proposed. Voltage profile comprising all bus voltages contains the effect of network structure, load-generation patterns and reactive power compensation on the system behaviour and voltage security margin. Therefore, the proposed index is capable to clearly reveal the effect of system characteristics and events on the voltage security margin. The most attractive feature for this index is its fast and easy calculation from synchronously measured voltage profile without any need to system modelling and simulation and without any dependency on network size. At any instant of system operation by merely measuring network voltage profile and no further simulation calculation this index could be evaluated with respect to a specific reference profile. The results show that the behaviour of this index with respect to the change in system security is independent of the selected reference profile. The simplicity and easy calculation make this index very suitable for on line application. The proposed approach has been demonstrated on IEEE 39 bus test system with promising results showing its effectiveness and applicability.

[Internal Exposure Levels of PAHs of Primary School Students in Guangzhou].

Science.gov (United States)

Su, Hui; Zhao, Bo; Zhang, Su-kun; Liu, Shan; Ren, Ming-zhong; Li, Jie; Shi, Xiao-xia

2015-12-01

In order to investigate the internal exposure levels of polycyclic aromatic hydrocarbons (PAHs) in primary school students of Guangzhou, the research collected urine of 78 and 86 primary school students from two primary schools in the summer of 2014, one school located in the ordinary residential area and the other in the industrial area. The contents of 10 kinds of OH-PAHs were tested by the rapid liquid chromatography coupled to triple quadruple tandem mass spectrometry. The results showed that the concentrations of total OH-PAHs in primary school students in the residential zone ranged from 0.83 µmol · mol⁻¹ to 80.63 µmol · mol⁻¹, while those in industrial area ranged from 1.06 µmol · mol⁻¹ to 72.47 µmol · mol⁻¹. The geometric average concentrations were 6.18 µmol · mol⁻¹ and 6.47 µmol · mol⁻¹, respectively, and there was no statistical significance between them (P > 0.05). Comparison of the exposure levels of different components of PAHs in the two areas found that all the OH-PAHs had no significant difference except for the levels of 1- OHP (P transportation emissions.

Advanced Control of the Dynamic Voltage Restorer for Mitigating Voltage Sags in Power Systems

Directory of Open Access Journals (Sweden)

Dung Vo Tien

2018-01-01

Full Text Available The paper presents a vector control with two cascaded loops to improve the properties of Dynamic Voltage Restorer (DVR to minimize Voltage Sags on the grid. Thereby, a vector controlled structure was built on the rotating dq-coordinate system with the combination of voltage control and the current control. The proposed DVR control method is modelled using MATLAB-Simulink. It is tested using balanced/unbalanced voltage sags as well as fluctuant and distorted voltages. As a result, by using this controlling method, the dynamic characteristics of the system have been improved significantly. The system performed with higher accuracy, faster response and lower distortion in the voltage sags compensation. The paper presents real time experimental results to verify the performance of the proposed method in real environments.

EMI performance comparison of two-level and three-level inverters in small dc-link capacitors based motor drives

DEFF Research Database (Denmark)

Maheshwari, Ram Krishan; Munk-Nielsen, Stig; Busquets-Monge, S.

2012-01-01

The size of passive components in an adjustable speed drive can be reduced by using small dc-link capacitors. The EMI filter in the drive also consists of passive components. The size of the filter can be reduced by using a three-level inverter, which can have low output voltage distortion. However......, the three-level inverter based on small dc-link capacitors requires a PWM strategy to maintain neutral-point voltage balance. In this paper, the common mode voltage, which is the determining factor for the EMI filter size, is analyzed for a virtual-vector-based PWM strategy. The common mode voltage......, the shaft voltage, and the conducted emission for the small dc-link capacitor based three-level inverter are compared with that of the two-level inverter operated with space vector PWM strategy. Experimental results for the common mode voltage, the shaft voltage, and the conducted emission are presented...

Secondary Voltage Unbalance Compensation for Three-Phase Four-Wire Islanded Microgrids

DEFF Research Database (Denmark)

Tang, Fen; Zhou, Xiao; Meng, Lexuan

2014-01-01

This paper proposes a secondary voltage unbalance control approach that compensate voltage unbalances in three-phase four-wire islanded microgrid systems. It is implemented in the secondary control level of the microgrid hierarchical control structure. By sending information through low......-bandwidth communication links to the primary control level, the required unbalanced factors at sensitive buses are achieved. Also, negative and zero sequence equivalent circuits and unbalance compensation principle are derived. Finally, real-time hardware-in-the-loop results show the feasibility of the proposed approach...

Fifth harmonic and sag impact on PMSG wind turbines with a balancing new strategy for capacitor voltages

International Nuclear Information System (INIS)

Seixas, M.; Melício, R.; Mendes, V.M.F.

2014-01-01

Highlights: • Impact on wind turbines due to fifth harmonic and sag content. • Converter topologies considered are two-level and three-level ones. • Controllers are based on PI and fractional-order methods. • New control strategy for the selection of output voltage vectors. • Balancing voltages in the DC-link capacitors. - Abstract: This paper deals with the computing simulation of the impact on permanent magnet synchronous generator wind turbines due to fifth harmonic content and grid voltage decrease. Power converter topologies considered in the simulations are the two-level and the three-level ones. The three-level converters are limited by unbalance voltages in the DC-link capacitors. In order to lessen this limitation, a new control strategy for the selection of the output voltage vectors is proposed. Controller strategies considered in the simulation are respectively based on proportional integral and fractional-order controllers. Finally, a comparison between the results of the simulations with the two controller strategies is presented in order to show the main advantage of the proposed strategy

Association of hypothyroidism with low-level arsenic exposure in rural West Texas

International Nuclear Information System (INIS)

Gong, Gordon; Basom, Janet; Mattevada, Sravan; Onger, Frederick

2015-01-01

It has been reported recently that a higher airborne arsenic level was correlated with higher urinary arsenic concentration and lower serum thyroxin level among urban policemen and rural highway workmen in Italy. The current study was to determine whether exposure to low-level arsenic groundwater (2–22 µg/L) is associated with hypothyroidism among 723 participants (118 male and 267 female Hispanics; 108 male and 230 female non-Hispanic whites, NHW) living in rural West Texas counties. Arsenic and iodine levels in their groundwater used for drinking and or cooking were estimated by the inverse distance weighted (IDW) interpolation technique. Groundwater arsenic was ≥8 µg/L in 36% of the subjects' wells while iodine concentration was <1 µg/L in 91% of their wells. Logistic regression analysis showed that arsenic in groundwater ≥8 µg/L and cumulative arsenic exposure (groundwater arsenic concentration multiplied by the number of years living in the current address) but not groundwater iodine concentration were significant predictors for hypothyroidism among Hispanics (p<0.05) but not NHW after adjusting for covariates such as age, gender, annual household income and health insurance coverage. The ethnic difference may be due to a marginally higher percentage of Hispanics (p=0.0622) who lived in areas with groundwater arsenic ≥8 µg/L compared with NHW. The prevalence of hypothyroidism was significantly higher in Hispanics or NHW of this rural cohort than the national prevalence. Measures should be taken to reduce arsenic in drinking water in order to prevent hypothyroidism in rural areas. - Highlights: • We determined if arsenic exposure is associated with hypothyroidism in rural Texas. • Groundwater arsenic level is associated with hypothyroidism among Hispanics only. • The rate of hypothyroidism in rural Texas was higher than the US general population

Association of hypothyroidism with low-level arsenic exposure in rural West Texas

Energy Technology Data Exchange (ETDEWEB)

Gong, Gordon, E-mail: gordon.gong@ttuhsc.edu [F. Marie Hall Institute for Rural and Community Health, Texas Tech University Health Sciences Center, Lubbock, TX (United States); Basom, Janet [F. Marie Hall Institute for Rural and Community Health, Texas Tech University Health Sciences Center, Lubbock, TX (United States); Department of Family and Community Medicine, Texas Tech University Health Sciences Center, Lubbock, TX (United States); Mattevada, Sravan [Department of Internal Medicine, University of North Texas Health Science Center, Fort Worth, TX (United States); Onger, Frederick [Department of Family and Community Medicine, Texas Tech University Health Sciences Center, Lubbock, TX (United States)

2015-04-15

It has been reported recently that a higher airborne arsenic level was correlated with higher urinary arsenic concentration and lower serum thyroxin level among urban policemen and rural highway workmen in Italy. The current study was to determine whether exposure to low-level arsenic groundwater (2–22 µg/L) is associated with hypothyroidism among 723 participants (118 male and 267 female Hispanics; 108 male and 230 female non-Hispanic whites, NHW) living in rural West Texas counties. Arsenic and iodine levels in their groundwater used for drinking and or cooking were estimated by the inverse distance weighted (IDW) interpolation technique. Groundwater arsenic was ≥8 µg/L in 36% of the subjects' wells while iodine concentration was <1 µg/L in 91% of their wells. Logistic regression analysis showed that arsenic in groundwater ≥8 µg/L and cumulative arsenic exposure (groundwater arsenic concentration multiplied by the number of years living in the current address) but not groundwater iodine concentration were significant predictors for hypothyroidism among Hispanics (p<0.05) but not NHW after adjusting for covariates such as age, gender, annual household income and health insurance coverage. The ethnic difference may be due to a marginally higher percentage of Hispanics (p=0.0622) who lived in areas with groundwater arsenic ≥8 µg/L compared with NHW. The prevalence of hypothyroidism was significantly higher in Hispanics or NHW of this rural cohort than the national prevalence. Measures should be taken to reduce arsenic in drinking water in order to prevent hypothyroidism in rural areas. - Highlights: • We determined if arsenic exposure is associated with hypothyroidism in rural Texas. • Groundwater arsenic level is associated with hypothyroidism among Hispanics only. • The rate of hypothyroidism in rural Texas was higher than the US general population.

Mitigating voltage lead errors of an AC Josephson voltage standard by impedance matching

Science.gov (United States)

Zhao, Dongsheng; van den Brom, Helko E.; Houtzager, Ernest

2017-09-01

A pulse-driven AC Josephson voltage standard (ACJVS) generates calculable AC voltage signals at low temperatures, whereas measurements are performed with a device under test (DUT) at room temperature. The voltage leads cause the output voltage to show deviations that scale with the frequency squared. Error correction mechanisms investigated so far allow the ACJVS to be operational for frequencies up to 100 kHz. In this paper, calculations are presented to deal with these errors in terms of reflected waves. Impedance matching at the source side of the system, which is loaded with a high-impedance DUT, is proposed as an accurate method to mitigate these errors for frequencies up to 1 MHz. Simulations show that the influence of non-ideal component characteristics, such as the tolerance of the matching resistor, the capacitance of the load input impedance, losses in the voltage leads, non-homogeneity in the voltage leads, a non-ideal on-chip connection and inductors between the Josephson junction array and the voltage leads, can be corrected for using the proposed procedures. The results show that an expanded uncertainty of 12 parts in 106 (k  =  2) at 1 MHz and 0.5 part in 106 (k  =  2) at 100 kHz is within reach.

Galvanizing industry: evaluation of exposure levels using biomonitors

Energy Technology Data Exchange (ETDEWEB)

Menezes, Maria Angela de B.C.; Sabino, Claudia de V.S.; Amaral, Angela Maria [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN), Belo Horizonte, MG (Brazil); Mattos, Silvania V. de M. [FUNED, Belo Horizonte, MG (Brazil). Div. de Bromatologia e Toxicologia; S. Filho, Serafim [Secretaria Municipal de Saude de Belo Horizonte, MG (Brazil). Coordenacao de Saude do Trabalhador; Maia, Elene Cristina P. [Minas Gerais Univ., Belo Horizonte, MG (Brazil). Dept. de Quimica

1999-11-01

In Brazil, statistical surveys concerning occupational diseases refer to accidents and damages. The surveys do not refer to the occupational diseases developed through long exposures to hazardous work conditions, involving physical risk and toxic chemical substances. The Program of Medical Control of Occupational Health determines the Maximum Biological Levels Allowed and the Values of Normality References. But concerning metal and toxic inorganic, values of only few elements are established. In Belo Horizonte and surroundings areas, which is an important industrial centre in the country, there are different industries distributed over various areas. There are about 80 galvanizing industries which are responsible for the majority of the metal contamination hospitalities. A preliminary sampling was performed in order to conduct a survey of the exposures to elements related to occupational diseases in galvanizing industry. The preliminary results for toxic and non-toxic elements obtained using hair and fingernails as biomonitors are shown. The K{sub 0} parametric neutron activation analysis method was applied and the elements determined were: Ag, Al, Au, Cl, Co, Cr, Cu, Fe, I, Mn, Na, Ti, V, Ta, and Zn. (author) 8 refs., 3 figs., 2 tabs.; e-mail: menezes at urano.cdtn.br

Voltage Dependence of Supercapacitor Capacitance

Directory of Open Access Journals (Sweden)

Szewczyk Arkadiusz

2016-09-01

Full Text Available Electronic Double-Layer Capacitors (EDLC, called Supercapacitors (SC, are electronic devices that are capable to store a relatively high amount of energy in a small volume comparing to other types of capacitors. They are composed of an activated carbon layer and electrolyte solution. The charge is stored on electrodes, forming the Helmholtz layer, and in electrolyte. The capacitance of supercapacitor is voltage- dependent. We propose an experimental method, based on monitoring of charging and discharging a supercapacitor, which enables to evaluate the charge in an SC structure as well as the Capacitance-Voltage (C-V dependence. The measurement setup, method and experimental results of charging/discharging commercially available supercapacitors in various voltage and current conditions are presented. The total charge stored in an SC structure is proportional to the square of voltage at SC electrodes while the charge on electrodes increases linearly with the voltage on SC electrodes. The Helmholtz capacitance increases linearly with the voltage bias while a sublinear increase of total capacitance was found. The voltage on SC increases after the discharge of electrodes due to diffusion of charges from the electrolyte to the electrodes. We have found that the recovery voltage value is linearly proportional to the initial bias voltage value.

The relationship between blood lead levels and occupational exposure in a pregnant population

Directory of Open Access Journals (Sweden)

Osmel La-Llave-León

2016-12-01

Full Text Available Abstract Background Pregnant women exposed to lead are at risk of suffering reproductive damages, such as miscarriage, preeclampsia, premature delivery and low birth weight. Despite that the workplace offers the greatest potential for lead exposure, there is relatively little information about occupational exposure to lead during pregnancy. This study aims to assess the association between blood lead levels and occupational exposure in pregnant women from Durango, Mexico. Methods A cross-sectional study was carried out in a population of 299 pregnant women. Blood lead was measured in 31 women who worked in jobs where lead is used (exposed group and 268 who did not work in those places (control group. Chi-square test was applied to compare exposed and control groups with regard to blood lead levels. Odds ratio (OR and 95% confidence intervals (CI were calculated. Multivariable regression analysis was applied to determine significant predictors of blood lead concentrations in the exposed group. Results Exposed women had higher blood lead levels than those in the control group (4.00 ± 4.08 μg/dL vs 2.65 ± 1.75 μg/dL, p = 0.002. Furthermore, women in the exposed group had 3.82 times higher probability of having blood lead levels ≥ 5 μg/dL than those in the control group. Wearing of special workwear, changing clothes after work, living near a painting store, printing office, junkyard or rubbish dump, and washing the workwear together with other clothes resulted as significant predictors of elevated blood lead levels in the exposed group. Conclusions Pregnant working women may be at risk of lead poisoning because of occupational and environmental exposure. The risk increases if they do not improve the use of protective equipment and their personal hygiene.

The relationship between blood lead levels and occupational exposure in a pregnant population.

Science.gov (United States)

La-Llave-León, Osmel; Salas Pacheco, José Manuel; Estrada Martínez, Sergio; Esquivel Rodríguez, Eloísa; Castellanos Juárez, Francisco X; Sandoval Carrillo, Ada; Lechuga Quiñones, Angélica María; Vázquez Alanís, Fernando; García Vargas, Gonzalo; Méndez Hernández, Edna Madai; Duarte Sustaita, Jaime

2016-12-07

Pregnant women exposed to lead are at risk of suffering reproductive damages, such as miscarriage, preeclampsia, premature delivery and low birth weight. Despite that the workplace offers the greatest potential for lead exposure, there is relatively little information about occupational exposure to lead during pregnancy. This study aims to assess the association between blood lead levels and occupational exposure in pregnant women from Durango, Mexico. A cross-sectional study was carried out in a population of 299 pregnant women. Blood lead was measured in 31 women who worked in jobs where lead is used (exposed group) and 268 who did not work in those places (control group). Chi-square test was applied to compare exposed and control groups with regard to blood lead levels. Odds ratio (OR) and 95% confidence intervals (CI) were calculated. Multivariable regression analysis was applied to determine significant predictors of blood lead concentrations in the exposed group. Exposed women had higher blood lead levels than those in the control group (4.00 ± 4.08 μg/dL vs 2.65 ± 1.75 μg/dL, p = 0.002). Furthermore, women in the exposed group had 3.82 times higher probability of having blood lead levels ≥ 5 μg/dL than those in the control group. Wearing of special workwear, changing clothes after work, living near a painting store, printing office, junkyard or rubbish dump, and washing the workwear together with other clothes resulted as significant predictors of elevated blood lead levels in the exposed group. Pregnant working women may be at risk of lead poisoning because of occupational and environmental exposure. The risk increases if they do not improve the use of protective equipment and their personal hygiene.

Postnatal odorant exposure induces peripheral olfactory plasticity at the cellular level.

Science.gov (United States)

Cadiou, Hervé; Aoudé, Imad; Tazir, Bassim; Molinas, Adrien; Fenech, Claire; Meunier, Nicolas; Grosmaitre, Xavier

2014-04-02

Mammalian olfactory sensory neurons (OSNs) form the primary elements of the olfactory system. Inserted in the olfactory mucosa lining of the nasal cavity, they are exposed to the environment and their lifespan is brief. Several reports say that OSNs are regularly regenerated during the entire life and that odorant environment affects the olfactory epithelium. However, little is known about the impact of the odorant environment on OSNs at the cellular level and more precisely in the context of early postnatal olfactory exposure. Here we exposed MOR23-green fluorescent protein (GFP) and M71-GFP mice to lyral or acetophenone, ligands for MOR23 or M71, respectively. Daily postnatal exposure to lyral induces plasticity in the population of OSNs expressing MOR23. Their density decreases after odorant exposure, whereas the amount of MOR23 mRNA and protein remain stable in the whole epithelium. Meanwhile, quantitative PCR indicates that each MOR23 neuron has higher levels of olfactory receptor transcripts and also expresses more CNGA2 and phosphodiesterase 1C, fundamental olfactory transduction pathway proteins. Transcript levels return to baseline after 4 weeks recovery. Patch-clamp recordings reveal that exposed MOR23 neurons respond to lyral with higher sensitivity and broader dynamic range while the responses' kinetics were faster. These effects are specific to the odorant-receptor pair lyral-MOR23: there was no effect of acetophenone on MOR23 neurons and no effect of acetophenone and lyral on the M71 population. Together, our results clearly demonstrate that OSNs undergo specific anatomical, molecular, and functional adaptation when chronically exposed to odorants in the early stage of life.

Effect of voltage sags on digitally controlled line connected switched-mode power supplies

DEFF Research Database (Denmark)

Török, Lajos; Munk-Nielsen, Stig

2012-01-01

Different voltage disorders like voltage fluctuations, sags, frequency variations may occur in the power supply networks due to different fault conditions. These deviations from normal operation affects in different ways the line connected devices. Standards were developed to protect and ensure...... of voltage sags is analyzed. Fault tolerant control algorithm was designed, implemented and is discussed. The fault conditions and their effects were investigated at different power levels....

Using a Voltage Domain Programmable Technique for Low-Power Management Cell-Based Design

Directory of Open Access Journals (Sweden)

Ching-Hwa Cheng

2011-09-01

Full Text Available The Multi-voltage technique is an effective way to reduce power consumption. In the proposed cell-based voltage domain programmable (VDP technique, the high and low voltages applied to logic gates are programmable. The flexible voltage domain reassignment allows the chip performance and power consumption to be dynamically adjusted. In the proposed technique, the power switches possess the feature of flexible programming after chip manufacturing. This VDP method does not use an external voltage regulator to regulate the supply voltage level from outside of the chip but can be easily integrated within the design. This novel technique is proven by use of a video decoder test chip, which shows 55% and 61% power reductions compared to conventional single-Vdd and low-voltage designs, respectively. This power-aware performance adjusting mechanism shows great power reduction with a good power-performance management mechanism.

Effects of low-level exposure to xenobiotics present in paints on oxidative stress in workers.

Science.gov (United States)

Moro, Angela M; Charão, Mariele; Brucker, Natália; Bulcão, Rachel; Freitas, Fernando; Guerreiro, Gilian; Baierle, Marília; Nascimento, Sabrina; Waechter, Fernanda; Hirakata, Vânia; Linden, Rafael; Thiesen, Flávia V; Garcia, Solange Cristina

2010-09-15

Paints are composed of an extensive variety of hazardous substances, such as organic solvents and heavy metals. Biomonitoring is an essential tool for assessing the risk to occupational health. Thus, this study analyzed the levels of biomarkers of exposure for toluene, xylene, styrene, ethylbenzene, and lead, as well as the oxidative stress biomarker alterations in painters of an industry. Lipid peroxidation biomarker (MDA), delta-aminolevulinate dehydratase (ALA-D), nonprotein thyol groups, superoxide dismutase and catalase (CAT) were analyzed in exposed and nonexposed subjects. We estimated which of the paint constituents have the greatest influence on the changes in the biomarkers of oxidative stress in this case of co-exposure. The results demonstrated that despite the fact that all the biomarkers of exposure were below the biological exposure limits, the MDA levels and antioxidant enzyme activities were increased, while nonprotein thyol groups and ALA-D levels were decreased in painters when compared with nonexposed subjects. After statistic test, toluene could be suggested as the principal factor responsible for increased lipid peroxidation and inhibition of ALA-D enzyme; however, further studies on the inhibition of ALA-D enzyme by toluene are necessary. Copyright 2010 Elsevier B.V. All rights reserved.

Voltage-Sensitive Load Controllers for Voltage Regulation and Increased Load Factor in Distribution Systems

DEFF Research Database (Denmark)

Douglass, Philip James; Garcia-Valle, Rodrigo; Østergaard, Jacob

2014-01-01

This paper presents a novel controller design for controlling appliances based on local measurements of voltage. The controller finds the normalized voltage deviation accounting for the sensitivity of voltage measurements to appliance state. The controller produces a signal indicating desired pow...

Voltage Stress on Y Capacitors from Indirect Lightning Pulses According to ED-14/DO-160

Science.gov (United States)

Meier, F.

2012-05-01

Transients due to lightning strikes on an aircraft's fuselage impose stress on the input filters of elec- tronic equipment. Permanent damage can occur when exceeding the voltage handling capacity of filter components causing a short circuit to ground. In ED-14/DO-160, section 22, a number of waveforms and levels are defined which are used to check the airworthiness of avionics equipment. Depending on pro- cedure and level, Y-capacitors are stressed by transient voltages which exceed their dielectric strength. The design engineer's task is a properly select the type and voltage rating of capacitors. With moderate simplifications, a LCR-series network is justified to calculate the peak voltage dependent on the capacitance.

High voltage series protection of neutral injectors with crossed-field tubes

International Nuclear Information System (INIS)

Hofmann, G.A.; Thomas, D.G.

1976-01-01

High voltage neutral beam injectors for fusion machines require either parallel or series protection schemes to limit fault currents in case of arcing to safe levels. The protection device is usually located between the high voltage supply and beam injector and either crowbars (parallel protection) or disconnects (series protection) the high voltage supply when a fault occurs. Because of its isolating property, series protection is preferred. The Hughes crossed-field tube is uniquely suited for series protection schemes. The tube can conduct 40 A continuously upon application of voltage (approximately 300 V) and a static magnetic field (approximately 100 G). It is also capable of interrupting currents of 1000 A within 10 μs and withstand voltage of more than 120 kV. Experiments were performed to simulate the duty of a crossed-field tube as a series protection element in a neutral injector circuit under fault conditions. Results of on-switching tests under high and low voltage and interruption of fault currents are presented. An example of a possible protection circuit with crossed-field tubes is discussed

Estimation of quantitative levels of diesel exhaust exposure and the health impact in the contemporary Australian mining industry.

Science.gov (United States)

Peters, Susan; de Klerk, Nicholas; Reid, Alison; Fritschi, Lin; Musk, Aw Bill; Vermeulen, Roel

2017-03-01

To estimate quantitative levels of exposure to diesel exhaust expressed by elemental carbon (EC) in the contemporary mining industry and to describe the excess risk of lung cancer that may result from those levels. EC exposure has been monitored in Western Australian miners since 2003. Mixed-effects models were used to estimate EC levels for five surface and five underground occupation groups (as a fixed effect) and specific jobs within each group (as a random effect). Further fixed effects included sampling year and duration, and mineral mined. On the basis of published risk functions, we estimated excess lifetime risk of lung cancer mortality for several employment scenarios. Personal EC measurements (n=8614) were available for 146 different jobs at 124 mine sites. The mean estimated EC exposure level for surface occupations in 2011 was 14 µg/m 3 for 12 hour shifts. Levels for underground occupation groups ranged from 18 to 44 µg/m 3 . Underground diesel loader operators had the highest exposed specific job: 59 µg/m 3 . A lifetime career (45 years) as a surface worker or underground miner, experiencing exposure levels as estimated for 2011 (14 and 44 µg/m 3 EC), was associated with 5.5 and 38 extra lung cancer deaths per 1000 males, respectively. EC exposure levels in the contemporary Australian mining industry are still substantial, particularly for underground workers. The estimated excess numbers of lung cancer deaths associated with these exposures support the need for implementation of stringent occupational exposure limits for diesel exhaust. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

Global levels of radiation exposure: Latest international findings

International Nuclear Information System (INIS)

Gonzalez, A.J.

1993-01-01

The radiation exposure of the world's population has recently been reviewed by the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR). UNSCEAR has reconfirmed that the normal operation of all peaceful nuclear installations contributes insignificantly to the global exposure to radiation. Even taking into account all the nuclear accidents to date (including Chernobyl), the additional exposure would be equivalent to only about 20 days of natural exposure. Military uses of nuclear energy have committed the world to most of the radiation exposure caused by human activities

An implantable neurostimulator with an integrated high-voltage inductive power-recovery frontend

International Nuclear Information System (INIS)

Wang Yuan; Zhang Xu; Liu Ming; Li Peng; Chen Hongda

2014-01-01

This paper present a highly-integrated neurostimulator with an on-chip inductive power-recovery frontend and high-voltage stimulus generator. In particular, the power-recovery frontend includes a high-voltage full-wave rectifier (up to 100 V AC input), high-voltage series regulators (24/5 V outputs) and a linear regulator (1.8/3.3 V output) with bandgap voltage reference. With the high voltage output of the series regulator, the proposed neurostimulator could deliver a considerably large current in high electrode-tissue contact impedance. This neurostimulator has been fabricated in a CSMC 1 μm 5/40/700 V BCD process and the total silicon area including pads is 5.8 mm 2 . Preliminary tests are successful as the neurostimulator shows good stability under a 13.56 MHz AC supply. Compared to previously reported works, our design has advantages of a wide induced voltage range (26–100 V), high output voltage (up to 24 V) and high-level integration, which are suitable for implantable neurostimulators. (semiconductor integrated circuits)

Symmetric voltage-controlled variable resistance

Science.gov (United States)

Vanelli, J. C.

1978-01-01

Feedback network makes resistance of field-effect transistor (FET) same for current flowing in either direction. It combines control voltage with source and load voltages to give symmetric current/voltage characteristics. Since circuit produces same magnitude output voltage for current flowing in either direction, it introduces no offset in presense of altering polarity signals. It is therefore ideal for sensor and effector circuits in servocontrol systems.

Exploration of genetically encoded voltage indicators based on a chimeric voltage sensing domain

Directory of Open Access Journals (Sweden)

Yukiko eMishina

2014-09-01

Full Text Available Deciphering how the brain generates cognitive function from patterns of electrical signals is one of the ultimate challenges in neuroscience. To this end, it would be highly desirable to monitor the activities of very large numbers of neurons while an animal engages in complex behaviours. Optical imaging of electrical activity using genetically encoded voltage indicators (GEVIs has the potential to meet this challenge. Currently prevalent GEVIs are based on the voltage-sensitive fluorescent protein (VSFP prototypical design or on the voltage dependent state transitions of microbial opsins.We recently introduced a new VSFP design in which the voltage-sensing domain (VSD is sandwiched between a FRET pair of fluorescent proteins (termed VSFP-Butterflies and also demonstrated a series of chimeric VSD in which portions of the VSD of Ciona intestinalis voltage-sensitive phosphatase (Ci-VSP are substituted by homologous portions of a voltage-gated potassium channel subunit. These chimeric VSD had faster sensing kinetics than that of the native Ci-VSD. Here, we describe a new set of VSFPs that combine chimeric VSD with the Butterfly structure. We show that these chimeric VSFP-Butterflies can report membrane voltage oscillations of up to 200 Hz in cultured cells and report sensory evoked cortical population responses in living mice. This class of GEVIs may be suitable for imaging of brain rhythms in behaving mammalians.

Exploration of genetically encoded voltage indicators based on a chimeric voltage sensing domain.

Science.gov (United States)

Mishina, Yukiko; Mutoh, Hiroki; Song, Chenchen; Knöpfel, Thomas

2014-01-01

Deciphering how the brain generates cognitive function from patterns of electrical signals is one of the ultimate challenges in neuroscience. To this end, it would be highly desirable to monitor the activities of very large numbers of neurons while an animal engages in complex behaviors. Optical imaging of electrical activity using genetically encoded voltage indicators (GEVIs) has the potential to meet this challenge. Currently prevalent GEVIs are based on the voltage-sensitive fluorescent protein (VSFP) prototypical design or on the voltage-dependent state transitions of microbial opsins. We recently introduced a new VSFP design in which the voltage-sensing domain (VSD) is sandwiched between a fluorescence resonance energy transfer pair of fluorescent proteins (termed VSFP-Butterflies) and also demonstrated a series of chimeric VSD in which portions of the VSD of Ciona intestinalis voltage-sensitive phosphatase are substituted by homologous portions of a voltage-gated potassium channel subunit. These chimeric VSD had faster sensing kinetics than that of the native Ci-VSD. Here, we describe a new set of VSFPs that combine chimeric VSD with the Butterfly structure. We show that these chimeric VSFP-Butterflies can report membrane voltage oscillations of up to 200 Hz in cultured cells and report sensory evoked cortical population responses in living mice. This class of GEVIs may be suitable for imaging of brain rhythms in behaving mammalians.

Precise derating of three phase induction motors with unbalanced voltages

International Nuclear Information System (INIS)

Faiz, Jawad; Ebrahimpour, H.

2007-01-01

Performance analysis of three phase induction motors under supply voltage unbalance conditions is normally conducted using the well-known symmetrical components analysis. In this analysis, the voltage unbalance level at the terminals of the machine is assessed by means of the NEMA or IEC definitions. Both definitions lead to a relatively large error in predicting the performance of a machine. A method has recently been proposed in which, in addition to the voltage unbalance factor (VUF), the phase angle has been taken into account in the analysis. This means that the voltage unbalance factor is regarded as a complex value. This paper shows that although the use of the complex VUF reduces the computational error considerably, it is still high. This is proven by evaluating the derating factor of a three phase induction motor. A method is introduced to determine the derating factor precisely using the complex unbalance factor for an induction motor operating under any unbalanced supply condition. A practical case for derating of a typical three phase squirrel cage induction motor supplied by an unbalanced voltage is studied in the paper