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This paper presents a feasibility analysis of vertical wake steering for floating turbines by differential ballast control. This new concept is based on the idea of pitching the floater with respect to the water surface, thereby achieving a desired tilt of the turbine rotor disk. The pitch attitude is controlled by moving water ballast among the columns of the floater. This study considers the application of differential ballast control to a conceptual 10MW wind turbine installed on two platforms, differing in size, weight, and geometry. The analysis considers the following: (a) the aerodynamic effects caused by rotor tilt on the power capture of the wake-steering turbine and at various downstream distances in its wake; (b) the effects of tilting on fatigue and ultimate loads, limitedly to one of the two turbine-platform layouts; and (c) for both configurations, the necessary amount of water movement, the time to achieve a desired attitude, and the associated energy expenditure. Results indicate that - in accordance with previous research - steering the wake towards the sea surface leads to larger power gains than steering it towards the sky. Limitedly to the structural analysis conducted on one of the turbine-platform configurations, it appears that these gains can be obtained with only minor effects on loads, assuming a cautious application of vertical steering only in benign ambient conditions. Additionally, it is found that rotor tilt can be achieved on the order of minutes for the lighter of the two configurations, with reasonable water ballast movements. Although the analysis is preliminary and limited to the specific cases considered here, results seem to suggest that the concept is not unrealistic and should be further investigated as a possible means to achieve variable tilt control for vertical wake steering in floating turbines. [ABSTRACT FROM AUTHOR]

The objective of this work is to study the influence of a pulsed power supply on the energy efficiency of high-intensity discharge lamps in comparison with a pseudo-continuous ballast. The results presented in this paper concern the dynamic behaviour of discharges in mercury vapour doped with thallium iodide. The acquisition of the arc current, arc voltage and spectral radiation enables us to investigate the influence of the pulsed power supply on the electrical characteristics of the lamp such as the behaviour of the lamp conductance and spectral radiance. The analysis of the 577 nm mercury line's response to the current pulse excitation allowed us to identify several phases. Good agreement has been found between simulation and experimental results. [ABSTRACT FROM AUTHOR]

In this paper, a wireless ballastless lighting system for fluorescent lamps is proposed and implement-ted. The key is to utilize magnetic resonant coupling to achieve wireless power transfer (WPT) while igniting the fluorescent lamp without using any magnetic or electronic ballast. Meanwhile, series-parallel compensation is identified to be more suitable for this WPT system. Also, burst firing control is utilized to achieve efficient light dimming. In order to achieve the fully wireless feature, remote lighting control via Bluetooth is realized by a smart phone. As an example, an experimental setup, which can light up an 8 W fluorescent lamp with illuminance of 2330 lx, has been designed and developed. In particular, it can achieve the transmission efficiency of 57% and the operating frequency of 51 kHz, with distance up to 56 cm. Both theoretical analyses and experimental results are given to validate the feasibility and flexibility of the proposed system. [ABSTRACT FROM AUTHOR]

The equipment designed for use in explosive atmospheres has to fulfil the requirements of ATEX Directive 2014/34/EU (transposed into Romanian legislation by GD 245/2016). In order to verify the explosion protection characteristics of equipment these shall be subjected to type tests. In case of fluorescent luminaires with type of protection increased safety "e", supplied by electronic ballasts, these shall be subjected to the asymmetric pulse and asymmetric power tests. The purpose of this paper is to present the importance of the asymmetric pulse and asymmetric power tests, and also, to underline the testing methodology developed based on the requirements imposed by the applicable standards. [ABSTRACT FROM AUTHOR]

By using a ballast resistor having resistance of 10 MΩ, varying the gap distance from 23 mm to 0 mm and using a fixed dc voltage at 14 kV, the streamer corona, single filament, transient glow, dc glow, and spark modes and their transitions are demonstrated in positive needle-to-plate air discharge at atmospheric pressure. The electrical characteristics, the rotational temperature, and vibrational temperature of N2, as well as the temporal behavior of streamer propagation in these discharge modes, are investigated. First, to the best of our knowledge, the transient glow mode between the single filament mode and the dc glow mode, operated in a stable repetitive fashion, is reported for the first time in positive dc air discharges. The pulse repetition frequency ranges from 7.5 to 15 kHz. The current density and the rotational temperature are in the range of 27–105 A/mm2 and 600–850 K, respectively. Its temporal behavior reveals that after the primary streamer arrives at the cathode, the secondary streamer initiates within several nanoseconds near the anode and then propagates at a high speed of 105–106 m/s. There is no transition to spark even after the secondary streamer arrives at the cathode. Second, the transition from single filament to transient glow is characterized by the sudden decrease in the pulse repetition frequency and the abrupt increase in the current amplitude, the pulse width, and the gas temperature. Third, the transition from transient glow to dc glow is identified visibly by the formation of typical glow structure (positive column, Faraday dark space, and negative glow), which is accompanied by the transition of the discharge current from nanosecond pulse to dc. In addition, both the ballast resistor and the stray capacitor exert significant influence on the transition of discharge modes. [ABSTRACT FROM AUTHOR]

A wattage-independent (7–18 W) compact fluorescent lamp (CFL) model has been developed in Matlab-Simulink and validated in low-frequency (50 Hz) operation in our earlier work. In this paper, the same lamp model is simulated for high-frequency operation and then validated experimentally with a 9 W test CFL driven by a compatible electronic ballast (e-ballast). Simulation results have shown a maximum 6.4% deviation compared to the measured data. Thereafter, the developed model is applied to obtain the arc resistance versus power and power versus frequency characteristics of CFLs required to design dimmable e-ballasts. An algorithm is developed to compute design parameters of a dimmable e-ballast based on voltage-fed series-parallel resonant inverter topology. The electrical performance of the designed e-ballast is simulated at three different power levels (100%, 75% and 50%) using Matlab-Simulink. [ABSTRACT FROM AUTHOR]

Repetitive or cyclic rail loading deteriorates the engineering properties of the railway ballast by particle crushing and rearrangement. Most of the classical elasto-plastic models are unable to predict such ballast degradation despite successfully predicting the overall load-deformation behavior during cyclic densification. In this context, the present study delivers a novel hypo-plastic modeling approach coupled with breakage mechanics theory to bridge the gap of the conventional models. The hypo-plastic approach enables to predict the nonlinear load-deformation response of ballast-type granular materials for both monotonic and cyclic loading conditions, while circumventing the requirement of notional yield condition to predict the inelastic behavior. Breakage mechanics theory, on the other hand, establishes the links between particle comminution and the macroscopic deformation. The novelty of the proposed approach is threefold. Firstly, unlike the conventional hypo-plastic approaches, the development of the proposed model is within the continuum thermodynamics framework. Secondly, the model requires less number of physically identifiable parameters as compared to that of earlier models employed for assessing the particle breakage under cyclic loading. Third and finally, the numerical implementation of the model as a user-defined material is simple for solving boundary value problems. Under the compressive deformation regime, the model prediction of the ballast degradation along with the cyclic densification response agrees reasonably well with the experimental results found in the literature. [ABSTRACT FROM AUTHOR]

The vertical loading-unloading trial was conducted on the polyurethane-mixed ballast of high-speed railway, obtaining the evolution law of macro energy of the polyurethane-mixed ballast. The discrete element model of the polyurethane-mixed ballast was established by PFC3D, and the parameters were calibrated and verified by the field test data. The evolution laws of micro energy of under the quasi-static load and trainload were analyzed. The results show that there were four main energies in the polyurethane-mixed ballast, namely elastic strain energy, viscous strain energy, friction energy and dashpot energy. The friction energy was the main form of energy, followed by the elastic strain energy. The viscous strain energy was larger than the dashpot energy under the quasi-static load, while the dashpot energy was larger than the viscous strain energy under the trainload. Under the quasi-static load, the elastic strain energy of the contact points between sleeper and ballast decreased at power rate, while other energy decreased exponentially. Under the trainload, the four kinds of energy of sleeper-ballast contact points decreased exponentially. The friction energy and elastic strain energy had a higher proportion on the bottom of sleeper. The viscous strain energy and dashpot energy had a higher proportion on the side of sleeper. [ABSTRACT FROM AUTHOR]

With an increase in the train load on the axis and the speed of the trains, the vibrodynamic load from the wheels to the ballast layer increases, characterized by the amplitude of the oscillations, frequency, vibration speed and other parameters. The main indicators of the state of the track, their deviations from the normative position in the profile and in the plan directly depend on the bearing capacity of the ballast layer. Vibrodynamic impact on the ballast layer is known to have a negative effect on the strength and deformation characteristics, which entails a decrease in the bearing capacity of the ballast layer. [ABSTRACT FROM AUTHOR]

An improved vehicle-track coupled dynamics model that takes into account the differential ballast settlement is presented in this paper. Central to this formulation is an iterative method for acquiring the mapping relationship between the ballast settlement and the deflection of rail and sleepers. The proposed method is validated by comparing the results obtained with those of the finite element method (FEM) and the equilibrium state calculated for the track with the ballast settlement. Using the proposed method and dynamic model, numerical analyses have been performed for the static deflection of the rail and sleepers and for the dynamic response of the vehicle-track coupled system. The results indicate that the upper track structure will settle along with the ballast bed, and sleepers are likely to become unsupported when the settlement amplitude is large or when the settlement wavelength is small. The contact between the sleeper and the ballast bed changes dynamically when the vehicle passes through the settlement area. The ballast settlement has a significant effect on the deformation of the track and sleepers, thereby deteriorating the running safety and ride comfort of the vehicle. [ABSTRACT FROM AUTHOR]

A distortion analysis of InGaP/GaAs HBT is presented based on Volterra Series. The interdependence between emitter ballasting resistor and linearity has been quantitatively analyzed. An optimized emitter ballasted power amplifier (PA) is designed and fabricated. Third-order intermodulation (IM3) of the PA is suppressed by 3–8 dB without sacrificing power gain and PAE. The theoretical calculation and measurement results show the optimization of emitter ballasting resistor is an alternative technique to improve PAs' linearity. [ABSTRACT FROM AUTHOR]

In nature, metal ores such as iron, lead, aluminum and others are found in an impure state, sometimes oxidized and mixed with silicates of other metals. During casting, when the ore is exposed to high temperatures, these impurities are separated from the molten metal and can be removed. The mass formed by these compounds is slag. Slag is the co-product of the smelting of ore to purify metals. It may be considered a mixture of metal oxides, but may also contain metal sulphites and metal atoms in their elemental form. After it is reprocessed to separate the metals contained, the co-products of this process can be used in cement, rail ballast, road paving and various other purposes. The objective of this research work is the presentation of the chemical and mineralogical characterization tests of the silicon-manganese iron slag with the purpose of reusing the co-product as rail ballast. X-ray diffraction tests, quantitative chemical analyzes, scanning electron microscopy and free lime content were prepared for these characterizations. The results of these tests showed the technical feasibility of using slag as rail ballast. [ABSTRACT FROM AUTHOR]

In this paper, the dimming effects on the photometric and electric characteristics of high intensity discharge lamps supplied by a low frequency square waveform are evaluated. For this evaluation an electronic ballast is presented. The ballast consists of a current source, AC/DC converter and a full-bridge inverter. The electronic supply provides to the lamp a different form of current excitation (square waves with variable short drops). Dimming control and the characteristics of low frequency operated high intensity discharge lamps are described. The lamp is represented in a simulation by its conductance model and coupled to its electronic power supply. Experimental results are shown and compared with the simulation. A dimming range from 100% to about 60% has been achieved. [ABSTRACT FROM AUTHOR]

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Influence of gravel segregation on gluing solution distribution in a realistic railway ballasts is investigated numerically. The rheological characteristics of the gluing solution are accounted for by using a coupled elasto-visco-plastic stress model with an asymptotic time increasing viscosity. The realistic railway ballast is accomplished by using the vertex identification technique, in which the regulations of the gravel composition in ballast practice are followed. Specifically, a uniformly distributed one and a segregated one induced by the difference in gravel size and gravel shape are generated. The rheological model of the gluing solution and twofold ballasts are incorporated into the finite element code of ANSYS $$^{\copyright }$$ to study the flow characteristics and time-dependent solidification of the gluing solution. Relatively concrete vertical and lateral gravel-gravel adhesion in twofold ballasts can be generated by using denser network arrangement of the gluing solution; the vertical penetration in the uniform ballast is slightly deeper than that in the segregated ballast, while a slightly reverse tendency in the lateral extension near the upper and central parts appears. However, the difference in the solidified gluing solution distributions in both ballasts is essentially insignificant, indicating that the influence of the gravel segregation needs not necessary to be taken into account in gluing practice when percolation is not taken into account. [ABSTRACT FROM AUTHOR]

Coarse-grained materials (CGMs), including gravel, ballast, and rockfill material, exhibit a complicated stress-strain-volume change behavior, which is state dependent and influenced by considerable particle breakage even under relatively low pressure. A generalized plasticity model with a multiaxial formulation is developed for CGMs based on the critical state concept. The effect of particle breakage on their critical state behavior, including the nonlinear variation of both shear strength and void ratio with the mean effective stress, is fully incorporated with an implicit form in the current model. Two state functions and the corresponding virtual stress ratios are proposed to construct the new formulation of dilatancy, plastic flow, loading direction, and plastic modulus in the present model. The numerical analyses are performed for a series of true triaxial tests on CGMs, and model predictions are in good agreement with experimental results of true triaxial tests over a wide range of pressures. In summary, the proposed model is capable of accurately characterizing the highly nonlinear shear behavior due to particle breakage of CGMs, particularly including their strain softening/hardening and plastic dilation/contraction in various load paths. [ABSTRACT FROM AUTHOR]

The main advantages of high-frequency electronic ballasts for high-intensity discharge lamps are high luminous efficacy, small size, lightweight and longer lifetime. This is why high-intensity discharge lamps operating at high frequency are widely used. This paper proposes an approach for designing resonant circuit electronic ballasts controlled by frequency variation for high-intensity discharge lamps. The proposed technique including an AC/DC rectifier, a power factor correction circuit and a DC/AC half bridge inverter. These electronic ballasts offer a wide range of dimming controls and can avoid acoustic resonance. However, under dimming, the electric and photometric characteristics of the lamp change. In order to study these effects under the process of dimming, this work studies the lamp properties by varying both lamp power and operating frequency. [ABSTRACT FROM AUTHOR]

This paper proposes a novel single stage single switch resonant inverter with high power factor for electronic ballast. The power factor correction circuit is at the input side. It is designed to operate at discontinuous conduction mode. The lamp power is controlled by adjusting the duty ratio of the active switch of the power factor correction circuit. The circuit operation is analyzed in detail to derive the design equations. Circuit parameters are designed based on design considerations. Finally, prototype electronic ballast for a 40-W compact fluorescent lamp is built and tested. The efficiency and the performance of the proposed converter are verified for the designed prototype. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The aim of this paper is to study and compare the temperature profile and energy performance of traditional and Vegetative Roofs (VRs) during winter season in Lebanon, a country in the Middle East. Three roof mockups were installed on the rooftop of the Chemical Engineering Department at the University of Balamand: a Traditional Gravel Ballasted Roof (TGBR) and two Extensive Green Roofs (EGRs) with different substrate depth and composition. Each minute, the temperature of air, on TGBR surface, and at different depths of EGR was recorded. The daily cooling and heating demands were also calculated. Results confirmed that VRs protect the roof membrane from high temperature fluctuations and decrease air temperature by a factor of one and a half during sunny winter days ( T airmax = 32 ° C ). Findings of this study also showed that the total cooling demand of EGR decreased by 90% compared to TGBR. [ABSTRACT FROM AUTHOR]

Electronic ballasts are implemented for obtaining a high power factor and a good operation of the lamp; these goals are reached traditionally by implementing multiple stages. On the first stage, a unity power factor is obtained and the second stage is designed in order to feed properly the lamp. Different topologies have been studied not only for decreasing the number of employed controllers and stages, but also reducing the number of components and active switches. Electronic ballasts, which are based on the “Z” and “qZ” source inverters, are considered in this paper, where the proposed systems have a single stage. Two topologies are illustrated: the first one for the fluorescent lamps and the second one for the high intensity discharge lamps, where electronic ballasts with a high power factor are obtained. The operation, analysis, and experimental results are shown. [ABSTRACT FROM PUBLISHER]

The low-pressure electric discharge established in mercury rare gas mixtures is the basis of many applications both in the field of lighting as for industrial applications. This present work presents the design of a high-frequency current supply based on a pulse width modulation inverter powering a low-pressure ultraviolet lamp dedicated for a germicidal effect in water purification. The basic open-loop system delivers voltage and current at a frequency of 50 kHz modulated in an envelop oscillating at 1 kHz, thus decreasing the operating efficiency of the system for an optimal germicide effect. A proportional-integral controller introduced in the ballast suppresses the modulation of the RMS intensity envelop but cannot assume robustness to external disturbances such as variation of the temperature of the water to disinfect. Thus, to increase the reliability of the whole system, the classic controller is originally replaced by a fuzzy controller, which significantly improves the quality of the waveforms of the lamp arc current and arc voltage. This new control strategy is more robust since it supports very large perturbations of the temperature of the water basin. [ABSTRACT FROM AUTHOR]

This paper deals with the design, modeling, analysis and implementation of unity power factor (UPF) based electronic ballast for a fluorescent lamp (FL). The proposed electronic ballast uses a boost AC-DC converter as a power factor corrector (PFC) to improve the power quality at the input ac mains. In this single-stage UPF based electronic ballast, boost PFC converter and a half bridge series resonant inverter (HBSRI) share a common power switch. Thus one power switch is reduced as compared to the conventional two-stage approach. The design, modeling, analysis and implementation of this topology were carried out in MATLAB-Simulink environment for a T8 36 W, 220 V, 50 Hz fluorescent lamp. The switching frequency was kept more than the resonant frequency of the inverter, to ensure the zero voltage switching (ZVS) operation of both power switches. This resulted in reduction of high frequency switching losses. The power quality parameters such as displacement power factor (DPF), distortion factor (DF), power factor (PF), crest factor (CF) and total harmonic distortion of ac mains current (THD) were evaluated to analyze the performance of proposed electronic ballast. Test results on a developed prototype of PFC electronic ballast were included to validate the design and simulated results. [ABSTRACT FROM AUTHOR]

In this paper, we investigate multilayer tubular conductor for multi-MHz Wireless Power Transfer systems high- Q (quality factor) resonators. The conductor layers’ thicknesses and current sharing between them are optimized at 13.56 MHz, showing significant reduction in conductor ac resistance R{AC}. Capacitive ballast is used as a practical method for current sharing between layers and operation of coil near resonance. A two-layer conductor is designed, fabricated, and characterized at 27.93 MHz, showing 18.1% and 12.8% reduction in R{AC}, compared with an identical conductor without capacitive ballast and a same size solid conductor, respectively. [ABSTRACT FROM PUBLISHER]

This paper presents a design methodology for an electronic ballast applied to ultraviolet radiation (UV) lamps for a drinking water purifier, providing adjustable UV dose in order to ensure the inactivation of microorganisms’ reproduction, commonly found in untreated water, which can be harmful to human health. The design methodology is based on the multiple segment summation source model, used for defining the UV dose applied to penstock purifiers, considering immersed lamps on a water slide enclosure, which in combination with its hydraulic behavior, provide a good performance for the microorganisms UV absorption along the entire purifier structure ducts. Thus, the water purifier was designed using hydrostatic simulations, in order to ensure compliance with the NSF/ANSI Standard 55, for commercial and residential applications. Thereby, an electronic ballast that guarantees a controlled preheating process for the UV lamp electrodes before its ignition and sets the nominal power point on the steady state, was implemented in order to guarantee the designed UV dose. Furthermore, the ballast incorporates a power factor correction flyback input rectifier stage, in discontinuous conduction mode, with universal input voltage range (90 V \text{rms}–240 V \text{rms}), attending the limits imposed by IEC 61000-3-2 Standard, for class-C devices. [ABSTRACT FROM PUBLISHER]

This paper presents an interleaved half-wave rectifier circuit, which constitutes an electronic ballast with high open-voltage gain and current doubler. It is suitable for applications in short-arc xenon lamp needing high open-circuit voltage and low operating voltage. By integrating interleaved half-wave rectifier with LCC resonant circuit, the electronic ballast can provide a low arc-sustaining current dc power source with low ripple and dimmable capability along with starting current suppression feature. Finally, a 25-A 500-W short-arc xenon lamp electronic ballast is developed to possess full load efficiency as high as 91.32% along with dimming range falling between 7.6% and 100% and peak starting current being as low as 16 A. [ABSTRACT FROM AUTHOR]

The essence of methodological and engineering questions solved during the preparation and implementation of historic dives of the manned submersibles Mir-1 and Mir-2, allowing humans to see the bottom of the North Pole at a depth of 4300 m, are described together with innovative developments in underwater navigation, as well as the Mir's propulsion, ballast, and other systems that ensured the safety of the dives. These innovative methods have opened up the Arctic's underice space for scientific research and practical exploration for minerals with the direct participation of scientists and specialists. [ABSTRACT FROM AUTHOR]

In order to optimally schedule railway track maintenance operations, it is essential to accurately estimate future track conditions. This study proposes a railway track geometry degradation model that considers uncertainties in the forecast by defining a track geometry reliability parameter. The degradation model is integrated in a multiobjective optimization approach to assess railway track maintenance strategies considering a cost-reliability trade off. Finally, a numerical application of the model to a real case study is presented. The results show the usefulness of the proposed approach to guarantee a required track geometry performance with effective maintenance investments. [ABSTRACT FROM AUTHOR]

This study focuses on the behavior of a cylindrical metal halide discharge lamp powered by frequency-controlled electronic ballast. Half-bridge electronic ballast was designed and achieved. [ABSTRACT FROM AUTHOR]

An LED driver compatible with various electronic ballasts that are currently commercially used is newly proposed, which adopts a variable switched capacitor by controlling the switching duty cycle for LED power regulation. The resonant frequency of an LC resonant tank of electronic ballasts can be changed, which makes the proposed LED driver versatile for electronic ballasts for various switching frequencies. In this way, the fluorescent lamp is replaced with an LED lamp, where the electronic ballast in the lighting infrastructure remains unchanged. The zero voltage switching is applied for the variable switched capacitor in the electronic ballast, operating at a frequency of 30–60 kHz. Neither an inductor nor a transformer is introduced in the proposed LED driver, which leads to compact size and high efficiency. Furthermore, no electrolytic capacitor is used, which is beneficial for the long lifetime of LED drivers. A prototype LED driver of 16 W was implemented and verified for the three types of electronic ballasts that are most popular in markets. The LED power was well regulated for a wide range of the source voltage variations between 180 and 270 V, and the power efficiencies of the proposed LED driver were 95.8%, 96.1%, and 94.1% for the instant start, rapid start, and programmed start types of the electronic ballasts, respectively. [ABSTRACT FROM PUBLISHER]

In this paper, a new technique to equalize light-emitting diode (LED) currents in multiarray LED lamps is proposed. The current through the LEDs is controlled by changing the inductance of a variable inductor. The proposed technique can be employed to control the current through each LED branch independently. The operation principle of this technique and a design example of the proposed system are presented in detail in this paper. As an example, a forward converter has been selected to supply the LED branches, which can be designed to operate with one or several outputs. The component values of the converter as well as the LED current control circuit are also calculated as a design example. A prototype of the circuit has been implemented. The experimental results obtained at the laboratory are satisfactory and in accordance to the proposed design methodology. The proposed technique can prove to be very cost-effective for LED drivers in the range of 100 W and beyond with multiple independent LED arrays. [ABSTRACT FROM AUTHOR]

Bucket foundation has been used for offshore wind turbine in Qidong city, China. In order to transport and install bucket foundations together with the upper offshore wind turbines, a non-self-propelled integrated transportation and installation vessel is designed. Wet tow of the dedicated vessel with two bucket foundations and the upper offshore wind turbines, one of the key issues of the integrated transportation and installation techniques, has been studied through a series of field experiments with different air pressures inside the bucket foundations and different ballasts in the vessel. The motion behaviors of the dedicated vessel are investigated. The results show that the dedicated vessel is quite stable during wet tows. In addition, with the air pressures inside the bucket foundations increase, the vessel becomes more stable. However, larger draft makes the vessel less stable and the ballast in the vessel may have little effect on the stability. [ABSTRACT FROM AUTHOR]

Current-controlled variable inductors adjust the inductance of an alternating current (ac) coil by applying a controlled dc current to saturate the iron cores of the ac coil. The controlled dc current has to be maintained during operation, which results in increased power losses. This paper presents a new stress-based variable inductor to control inductance using the inverse magnetostrictive effect of a magnetostrictive material. The stress can be applied by a piezoelectrical material, and thus a voltage-controlled variable inductor can be realized with zero-power consumption. The new stress-based variable inductor concept is validated using a 3-D finite-element analysis. A prototype was manufactured, and the experimental results are presented. A linear relationship between inductance and applied stress can be achieved. [ABSTRACT FROM AUTHOR]

The emissions of polychlorinated biphenyl (PCB) congeners from thirteen caulk samples were tested in a micro-chamber system. Twelve samples were from PCB-contaminated buildings and one was prepared in the laboratory. Nineteen light ballasts collected from buildings that represent 13 different models from five manufacturers were tested in 53-L environmental chambers. The rates of PCB congener emissions from caulking materials and light ballasts were determined. Several factors that may have affected the emission rates were evaluated. The experimentally determined emission factors showed that, for a given PCB congener, there is a linear correlation between the emission factor and the concentration of the PCB congener in the source. Furthermore, the test results showed that an excellent log-linear correlation exists between the normalized emission factor and the vapor pressure (coefficient of determination, r 2 ⩾ 0.8846). The PCB congener emissions from ballasts at or near room temperature were relatively low with or without electrical load. However, the PCB congener emission rates increased significantly as the temperature increased. The results of this research provide new data and models for ranking the primary sources of PCBs and supports the development and refinement of exposure assessment models for PCBs. [ABSTRACT FROM AUTHOR]

Ultralow-loss passive ballasts for T5 fluorescent lamps have previously been proven to be more energy efficient than their electronic counterparts at room temperature operation. The absence of electrolytic capacitor, switched-mode circuit, and control integrated circuit makes them particularly suitable for extreme temperature conditions. This paper first describes the challenges required for low-temperature operation and frequent ignition of T5 high-efficiency lamps. Then, the design of passive inductive–capacitive (LC) ballast for T5 28-W lamps based on a physical discharge lamp model is illustrated. To reduce the blackening effects of the filaments, a bypass resistor is incorporated to each filament to avoid local hot spot formation. Frequent ignition tests have been conducted for the proposed ballast and electronic ballast to confirm the effectiveness of the bypass resistors in protecting the filaments. [ABSTRACT FROM AUTHOR]

This paper presents the current stabilization technique that uses high-frequency voltage pulses to supply discharge lamps and takes advantage of the resistivity of the plasma to limit the current through the lamp. A computational model that regards the chemical and physical discharge characteristics for high-pressure sodium lamp was implemented in MATLAB to validate the proposed power supply. A 150-W prototype was implemented to confirm the current stabilization technique. [ABSTRACT FROM PUBLISHER]

This study deals with the design, modelling and implementation of unity power factor (UPF) boundary conduction mode (BCM)-based electronic ballast for a T8, 36 W fluorescent lamp. In low power applications, BCMbased boost converter is widely used because of the low inductor value, however, because of zero crossover distortion, achieving a total harmonic distortion of <10% is difficult for universal AC mains. In proposed electronic ballast, UPF has been achieved at universal AC mains by using a boost power factor corrected converter operating in BCM with constant on time control. The achieved constant DC-link voltage is converted into high frequency AC voltage using a quasi-half bridge series resonant inverter to initiate the discharge and also to drive the fluorescent lamp with constant current. The modelling and simulation of the proposed topology have been performed using sim power system tool-boxes in MATLAB-Simulink environment. The switching losses have been reduced by achieving zero voltage switching at an operating switching frequency of 46 kHz. Different evaluated parameters have been found as per the international standard IEC61000-3-2 of class C regulations. [ABSTRACT FROM AUTHOR]

Field emission (FE) electron sources based on carbon nanotubes (CNTs) have the potential to serve as cold cathodes for various vacuum microelectronic and nanoelectronic devices. Emission currents are extremely sensitive to variation in emitter geometry and local surface states, both of which are difficult to synthesize uniformly when fabricating a CNT field emission array (FEA). Such non-uniformities cause unstable emission, limiting the current output. Here, we propose a method for simulating and fabricating a high performance CNT-FEA with emission units that are individually connected to a single crystalline silicon pillar (SP), which acts as an non-linear ballast resistor. Results showed that the driving field for this CNT-FEA was greatly reduced relative to CNT-FEAs on a flat silicon substrate. This improvement was due to the high aspect ratio of the CNT clusters combined with SPs. The FE behavior demonstrated that the emission current was limited by the non-linear resistors (NLRs). Emitted currents density over 1.65 A/cm 2 at a low extraction field of 5.8 V/μm were produced by a 1 mm 2 emmiting area. The proposed technology may be used to fabricate cathodes capable of reliable, uniform, and high current emission. [ABSTRACT FROM AUTHOR]

Lighting is one of the major energy end uses, which accounts for approximately 20–30% of electricity consumption in buildings. In fact, the fluorescent lamp is the most employed lamp in a lighting system for both inside and outside the building. The ballast is one of the major components of fluorescent lamps; it exists commercially as an electromagnetic ballast, a low loss ballast and an electronic ballast. To reduce energy consumption in a lighting system, the electronic ballast has already been introduced for profit in terms of its peak demand reduction and energy conservation in the building. However, when the electronic ballast functions, harmonics will be generated. Hence, this paper investigates energy savings and the generation of harmonics when using a fluorescent T5 lamp with electronic ballast in a building. The efficiency indices in terms of illumination, energy savings, and harmonics are also evaluated and compared with the fluorescent T8 lamp operating with a low watt loss electromagnetic ballast, which is also widely used. The obtained results are useful for the design and decision to install a fluorescent T5 lamp with electronic ballast in building lighting system to conserve energy and/or reduce energy consumption for the future of the country. [ABSTRACT FROM AUTHOR]

A three-stage inrush-current suppression circuit is proposed for the boundary conduction mode boost circuit, which not only can suppress the first inrush current when powered on in the boost topology but also can suppress the secondary inrush current caused by the working of the boost circuit; the inrush current caused by the electromagnetic interference filter can also be suppressed. The simulations are performed to prove the rightness and feasibility of the circuit, and the circuit is used in a 1000-W two-stage electronic ballast for the metal halide lamp. In the experiment, the first inrush current is nearly 0 A, and the second inrush current is less than 12 A. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This paper presents a comparative investigation, design and development issues about six different single-stage topologies, applied as electronic ballasts, for electrodeless fluorescent lamps. The ballast is intended to feed a 100 W lamp at 250 kHz, with dimming feature. The proposed topologies use different converters for the power factor correction (PFC) stage: Buck-Boost, SEPIC, Zeta, Cúk, Flyback, and Boost. All of them operate in discontinuous conduction mode. A resonant half-bridge inverter is used as lamp power control (PC) stage. The integration of both stages (PFC and PC) is proposed in this paper. In this way, it is possible to reduce the number of active switches, as well as simplify the required driving and control circuitry. Experimental results demonstrate the feasibility of the proposed dimming technique that achieved around 56% lamp power dimming, from 100 W down to 44 W. The implemented topologies attained high average power factor (>0.98), and low line current average total harmonic distortion (<;15.3%). A comparison among all the proposed topologies in terms of power factor, harmonic distortion, efficiency and number of components is presented. Finally, a comparison between an integrated and a nonintegrated SEPIC half-bridge converter is also performed. [ABSTRACT FROM AUTHOR]

A detailed controller design for indirect constant power regulation of high intensity discharge (HID) electronic ballast and the experimental implementation of an adaptive passivity-based constant power (PBC) controller has been extensively studied through simulation and the findings are reported in this paper. An indirect method to regulate the inductor current to ensure the lamp constant output power is proposed in order to overcome the difficulties in measuring the output power of the HID ballast. The controller is derived using passivity theory which guarantees global stability and asymptotic convergence of all state errors. The simulation and controller design are based on an average model using the Euler-Lagrange (EL) equations of the system. As the lamp resistance will inevitably change with ageing, an adaptive method is used to compensate for the lamp performance as the lamp ages. This equips the controller the power to adapt to load variations and there is no need to tune the design parameters values each time manually. Another interconnection and damping assignment (IDA)-PBC method is analyzed and simulation results are provided for comparison. Computer simulation and hardware implementation are carried out to verify the system model and to demonstrate the controller is robust. [ABSTRACT FROM AUTHOR]

Ballasted track is the most common form of construction used in railway transportation due to a number of benefits in comparison with other solutions such as slab track. However, the degradation of the ballast particles and the layer settlement lead to important maintenance costs. Thus, diverse research has been carried out to develop new materials with the aim of increasing the service life of the track. To this end, the present paper focuses on the use of crumb rubber (from end-of-life tires) as elastic aggregates mixed with ballast particles, which could reduce ballast degradation and consumption of natural aggregates. At the same time, an abundant waste source is reused and the use of raw binders (proposed technique employed to bond elastic particles to ballast particles) is not necessary, which potentially reduces costs and consumption of raw materials. For this reason, the influence of different percentages of crumb rubber was studied in the laboratory using a ballast box. In addition, once the optimal quantity of rubber had been determined, its effect on ballast behaviour under high stress level was analysed. Results show that the use of 10% of crumb rubber (by volume) could reduce ballast degradation and at the same time as the capacity of the ballast layer to dissipate energy is increased and its stiffness is reduced. Additionally, based on the present laboratory study, the track settlement could be reduced with 10% rubber particles used as elastic aggregates. [ABSTRACT FROM AUTHOR]

This paper presents a comparative analysis of the performance characteristics among different dimming methods for electronic ballasts using the self-oscillating half-bridge (HB) inverter with a power factor correction (PFC) stage. Initially, a review of common dimming methods presented in the literature is presented, and a general analysis of each dimming method is carried out. Furthermore, the operation of the dimmable self-oscillating electronic ballast with a PFC stage is analyzed in order to evaluate the performance of each different dimming methods used. Finally, a comparison among the different dimming methods implemented with the self-oscillating HB inverter and PFC stage is carried out. [ABSTRACT FROM AUTHOR]