Inverted light-sheet microscope for imaging mouse pre-implantation development.

Science.gov (United States)

Strnad, Petr; Gunther, Stefan; Reichmann, Judith; Krzic, Uros; Balazs, Balint; de Medeiros, Gustavo; Norlin, Nils; Hiiragi, Takashi; Hufnagel, Lars; Ellenberg, Jan

2016-02-01

Despite its importance for understanding human infertility and congenital diseases, early mammalian development has remained inaccessible to in toto imaging. We developed an inverted light-sheet microscope that enabled us to image mouse embryos from zygote to blastocyst, computationally track all cells and reconstruct a complete lineage tree of mouse pre-implantation development. We used this unique data set to show that the first cell fate specification occurs at the 16-cell stage.

Open-dish incubator for live cell imaging with an inverted microscope.

Science.gov (United States)

Heidemann, Steven R; Lamoureux, Phillip; Ngo, Kha; Reynolds, Matthew; Buxbaum, Robert E

2003-10-01

Here we describe the design and fabrication of an inexpensive cell culture incubator for the stage of an inverted light microscope for use in live cell imaging. This device maintains the temperature of the cell culture at 37 degrees C with great stability and, after reaching equilibrium, provides focal stability of an image for 20-25 min with oil-immersion lenses. We describe two versions of the incubator: one for use with standard 60-mm plastic culture dishes, and the other version for imaging of cells on glass coverslips. Either can be made for less than $400. Most components are widely available commercially, and it requires only simple wiring and 3 h to assemble. Although the device is generally useful for live cell imaging on an inverted microscope, it is particularly suitable for work in which instruments are introduced into the culture, such as electrophysiology or micromanipulation. The design is based on the principle that control performance is limited by the lag time between detection and response. The key element of the design is a heated, temperature-controlled aluminum ring serving as a mini-incubator surrounding the culture vessel. For this reason, we call our design a "ringcubator."

Speckle-free and halo-free low coherent Mach-Zehnder quantitative-phase-imaging module as a replacement of objective lens in conventional inverted microscopes

Science.gov (United States)

Yamauchi, Toyohiko; Yamada, Hidenao; Matsui, Hisayuki; Yasuhiko, Osamu; Ueda, Yukio

2018-02-01

We developed a compact Mach-Zehnder interferometer module to be used as a replacement of the objective lens in a conventional inverted microscope (Nikon, TS100-F) in order to make them quantitative phase microscopes. The module has a 90-degree-flipped U-shape; the dimensions of the module are 160 mm by 120 mm by 40 mm and the weight is 380 grams. The Mach-Zehnder interferometer equipped with the separate reference and sample arms was implemented in this U-shaped housing and the path-length difference between the two arms was manually adjustable. The sample under test was put on the stage of the microscope and a sample light went through it. Both arms had identical achromatic lenses for image formation and the lateral positions of them were also manually adjustable. Therefore, temporally and spatially low coherent illumination was applicable because the users were able to balance precisely the path length of the two arms and to overlap the two wavefronts. In the experiment, spectrally filtered LED light for illumination (wavelength = 633 nm and bandwidth = 3 nm) was input to the interferometer module via a 50 micrometer core optical fiber. We have successfully captured full-field interference images by a camera put on the trinocular tube of the microscope and constructed quantitative phase images of the cultured cells by means of the quarter-wavelength phase shifting algorithm. The resultant quantitative phase images were speckle-free and halo-free due to spectrally and spatially low coherent illumination.

Versatile microfluidic total internal reflection (TIR)-based devices: application to microbeads velocity measurement and single molecule detection with upright and inverted microscope.

Science.gov (United States)

Le, Nam Cao Hoai; Yokokawa, Ryuji; Dao, Dzung Viet; Nguyen, Thien Duy; Wells, John C; Sugiyama, Susumu

2009-01-21

A poly(dimethylsiloxane) (PDMS) chip for Total Internal Reflection (TIR)-based imaging and detection has been developed using Si bulk micromachining and PDMS casting. In this paper, we report the applications of the chip on both inverted and upright fluorescent microscopes and confirm that two types of sample delivery platforms, PDMS microchannel and glass microchannel, can be easily integrated depending on the magnification of an objective lens needed to visualize a sample. Although any device configuration can be achievable, here we performed two experiments to demonstrate the versatility of the microfluidic TIR-based devices. The first experiment was velocity measurement of Nile red microbeads with nominal diameter of 500 nm in a pressure-driven flow. The time-sequenced fluorescent images of microbeads, illuminated by an evanescent field, were cross-correlated by a Particle Image Velocimetry (PIV) program to obtain near-wall velocity field of the microbeads at various flow rates from 500 nl/min to 3000 nl/min. We then evaluated the capabilities of the device for Single Molecule Detection (SMD) of fluorescently labeled DNA molecules from 30 bp to 48.5 kbp and confirm that DNA molecules as short as 1105 bp were detectable. Our versatile, integrated device could provide low-cost and fast accessibility to Total Internal Reflection Fluorescent Microscopy (TIRFM) on both conventional upright and inverted microscopes. It could also be a useful component in a Micro-Total Analysis System (micro-TAS) to analyze nanoparticles or biomolecules near-wall transport or motion.

Using machine-learning to optimize phase contrast in a low-cost cellphone microscope

Science.gov (United States)

Wartmann, Rolf; Schadwinkel, Harald; Heintzmann, Rainer

2018-01-01

Cellphones equipped with high-quality cameras and powerful CPUs as well as GPUs are widespread. This opens new prospects to use such existing computational and imaging resources to perform medical diagnosis in developing countries at a very low cost. Many relevant samples, like biological cells or waterborn parasites, are almost fully transparent. As they do not exhibit absorption, but alter the light’s phase only, they are almost invisible in brightfield microscopy. Expensive equipment and procedures for microscopic contrasting or sample staining often are not available. Dedicated illumination approaches, tailored to the sample under investigation help to boost the contrast. This is achieved by a programmable illumination source, which also allows to measure the phase gradient using the differential phase contrast (DPC) [1, 2] or even the quantitative phase using the derived qDPC approach [3]. By applying machine-learning techniques, such as a convolutional neural network (CNN), it is possible to learn a relationship between samples to be examined and its optimal light source shapes, in order to increase e.g. phase contrast, from a given dataset to enable real-time applications. For the experimental setup, we developed a 3D-printed smartphone microscope for less than 100 $ using off-the-shelf components only such as a low-cost video projector. The fully automated system assures true Koehler illumination with an LCD as the condenser aperture and a reversed smartphone lens as the microscope objective. We show that the effect of a varied light source shape, using the pre-trained CNN, does not only improve the phase contrast, but also the impression of an improvement in optical resolution without adding any special optics, as demonstrated by measurements. PMID:29494620

Combined reflection and transmission microscope for telemedicine applications in field settings

OpenAIRE

Biener, Gabriel; Greenbaum, Alon; Isikman, Serhan O.; Lee, Kelvin; Tseng, Derek; Ozcan, Aydogan

2011-01-01

We demonstrate a field-portable upright and inverted microscope that can image specimens in both reflection and transmission modes. This compact and cost-effective dual-mode microscope weighs only ~135 grams (

Observing Fluorescent Probes in Living Cells using a Low-Cost LED Flashlight Retrofitted to a Common Vintage Light Microscope

Directory of Open Access Journals (Sweden)

G. A. Babbitt

2013-03-01

Full Text Available While the application of molecular biological techniques based upon fluorescent probes has rapidly expanded over recent decades, the equipment cost of fluorescent microscopy has largely prevented its adoption in the college and high school classroom. We offer a simple solution to this problem by describing in detail how to build with simple tools, a fluorescent microscope using a common brand of colored LED flashlights and second-hand components of vintage Nikon microscopes. This extremely low cost solution is qualitatively compared to an expensive modern Zeiss system.

Review of PV Inverter Technology Cost and Performance Projections

Energy Technology Data Exchange (ETDEWEB)

Navigant Consulting Inc.

2006-01-01

The National Renewable Energy Laboratory (NREL) has a major responsibility in the implementation of the U.S. Department of Energy's (DOE's) Solar Energy Technologies Program. Sandia National Laboratories (SNL) has a major role in supporting inverter development, characterization, standards, certifications, and verifications. The Solar Energy Technologies Program recently published a Multiyear Technical Plan, which establishes a goal of reducing the Levelized Energy Cost (LEC) for photovoltaic (PV) systems to $0.06/kWh by 2020. The Multiyear Technical Plan estimates that, in order to meet the PV system goal, PV inverter prices will need to decline to $0.25-0.30 Wp by 2020. DOE determined the need to conduct a rigorous review of the PV Program's technical and economic targets, including the target set for PV inverters. NREL requested that Navigant Consulting Inc.(NCI) conduct a review of historical and projected cost and performance improvements for PV inverters, including identification of critical barriers identified and the approaches government might use to address them.

Apertureless near-field/far-field CW two-photon microscope for biological and material imaging and spectroscopic applications.

Science.gov (United States)

Nowak, Derek B; Lawrence, A J; Sánchez, Erik J

2010-12-10

We present the development of a versatile spectroscopic imaging tool to allow for imaging with single-molecule sensitivity and high spatial resolution. The microscope allows for near-field and subdiffraction-limited far-field imaging by integrating a shear-force microscope on top of a custom inverted microscope design. The instrument has the ability to image in ambient conditions with optical resolutions on the order of tens of nanometers in the near field. A single low-cost computer controls the microscope with a field programmable gate array data acquisition card. High spatial resolution imaging is achieved with an inexpensive CW multiphoton excitation source, using an apertureless probe and simplified optical pathways. The high-resolution, combined with high collection efficiency and single-molecule sensitive optical capabilities of the microscope, are demonstrated with a low-cost CW laser source as well as a mode-locked laser source.

Application of differential interference contrast with inverted microscopes to the in vitro perfused nephron.

Science.gov (United States)

Horster, M; Gundlach, H

1979-12-01

The study of in vitro perfused individual nephron segments requires a microscope which provides: (1) easy access to the specimen for measurement of cellular solute flux and voltage; (2) an image with high resolution and contrast; (3) optical sectioning of the object at different levels; and (4) rapid recording of the morphological phenomena. This paper describes an example of commercially available apparatus meeting the above requirements, and illustrates its efficiency. The microscope is of the inverted type (Zeiss IM 35) equipped with differential-interference-contrast (DIC) with a long working distance, and an automatically controlled camera system. The microscopic image exhibits cellular and intercellular details in the unstained transporting mammalian nephron segments despite their tubular structure and great thickness and makes obvious function-structure correlations (e.g. cell volume changes); luminal and contraluminal cell borders are well resolved for controlled microelectrode impalement.

An Assemblable, Multi-Angle Fluorescence and Ellipsometric Microscope

Science.gov (United States)

Nguyen, Victoria; Rizzo, John

2016-01-01

We introduce a multi-functional microscope for research laboratories that have significant cost and space limitations. The microscope pivots around the sample, operating in upright, inverted, side-on and oblique geometries. At these geometries it is able to perform bright-field, fluorescence and qualitative ellipsometric imaging. It is the first single instrument in the literature to be able to perform all of these functionalities. The system can be assembled by two undergraduate students from a provided manual in less than a day, from off-the-shelf and 3D printed components, which together cost approximately $16k at 2016 market prices. We include a highly specified assembly manual, a summary of design methodologies, and all associated 3D-printing files in hopes that the utility of the design outlives the current component market. This open design approach prepares readers to customize the instrument to specific needs and applications. We also discuss how to select household LEDs as low-cost light sources for fluorescence microscopy. We demonstrate the utility of the microscope in varied geometries and functionalities, with particular emphasis on studying hydrated, solid-supported lipid films and wet biological samples. PMID:27907008

An Assemblable, Multi-Angle Fluorescence and Ellipsometric Microscope.

Directory of Open Access Journals (Sweden)

Victoria Nguyen

Full Text Available We introduce a multi-functional microscope for research laboratories that have significant cost and space limitations. The microscope pivots around the sample, operating in upright, inverted, side-on and oblique geometries. At these geometries it is able to perform bright-field, fluorescence and qualitative ellipsometric imaging. It is the first single instrument in the literature to be able to perform all of these functionalities. The system can be assembled by two undergraduate students from a provided manual in less than a day, from off-the-shelf and 3D printed components, which together cost approximately $16k at 2016 market prices. We include a highly specified assembly manual, a summary of design methodologies, and all associated 3D-printing files in hopes that the utility of the design outlives the current component market. This open design approach prepares readers to customize the instrument to specific needs and applications. We also discuss how to select household LEDs as low-cost light sources for fluorescence microscopy. We demonstrate the utility of the microscope in varied geometries and functionalities, with particular emphasis on studying hydrated, solid-supported lipid films and wet biological samples.

Design And Implementation Of Cost Effective Inverter

Directory of Open Access Journals (Sweden)

Niaz Morshedul Haque

2017-10-01

Full Text Available This paper deals with the design and construct of a 100 Watt 220 Volt and 50 Hz Inverter. The system is designed without any microcontroller and it has a cost-effective design architecture. The elementary purpose of this device is to transmute 12 V DC to 220 V AC. Snubber technology is used to diminish the reverse potential transients and excessive heat of transformer winding and transistor switches. Switching pulse generated by NE 555 timer circuit and comparator circuit was used to take signal strength input from its rear as well as from both sides for triggering the MOSFET switches. Another switch is used to invert pulse between two switching circuitries. A 5 volts regulator IC 7805 was used to supply fixed 5V for biasing the switching and amplifying circuitry.

In-Situ Microprobe Observations of Dispersed Oil with Low-Temperature Low-Vacuum Scanning Electron Microscope

International Nuclear Information System (INIS)

Mohsen, H.T.

2010-01-01

A low cost cryostat stage from high heat capacity material is designed and constructed, in attempt to apply size distribution techniques for examination of oil dispersions. Different materials were tested according to their heat capacity to keep the liquid under investigation in frozen state as long as possible during the introduction of the cryostat stage to the low-vacuum scanning electron microscope. Different concentrations of non ionic surfactant were added to artificially contaminated with 10000 ppm Balayeam base oil in 3.5 % saline water, where oil and dispersing liquid have been added and shacked well to be investigated under the microscope as fine frozen droplets. The efficiency of dispersion was examined using low temperature low-vacuum scanning electron microscope. The shape and size distributions of freeze oil droplets were studied by digital imaging processing technique in conjunction with scanning electron microscope counting method. Also elemental concentration of oil droplets was analyzed.

Extreme Cost Reductions with Multi-Megawatt Centralized Inverter Systems

Energy Technology Data Exchange (ETDEWEB)

Schwabe, Ulrich [Alencon LLC; Fishman, Oleg [Alencon LLC

2015-03-20

The objective of this project was to fully develop, demonstrate, and commercialize a new type of utility scale PV system. Based on patented technology, this includes the development of a truly centralized inverter system with capacities up to 100MW, and a high voltage, distributed harvesting approach. This system promises to greatly impact both the energy yield from large scale PV systems by reducing losses and increasing yield from mismatched arrays, as well as reduce overall system costs through very cost effective conversion and BOS cost reductions enabled by higher voltage operation.

Inverter circuits on freestanding flexible substrate using ZnO nanoparticles for cost-efficient electronics

Science.gov (United States)

Vidor, Fábio F.; Meyers, Thorsten; Müller, Kathrin; Wirth, Gilson I.; Hilleringmann, Ulrich

2017-11-01

Driven by the Internet of Things (IoT), flexible and transparent smart systems have been intensively researched by the scientific community and by several companies. This technology is already available for consumers in a wide range of innovative products, e.g., flexible displays, radio-frequency identification tags and wearable electronic skins which, for instance, collect and analyze data for medical applications. For these systems, thin-film transistors (TFTs) are the key elements responsible for the driving currents. Solution-based materials such as nanoparticle dispersions avail the fabrication on large-area substrates with high throughput processes. In this study, we discuss the integration of ZnO nanoparticle thin-film transistors and inverter circuits on freestanding polymeric substrates enclosing the main issues concerning the transfer of the integration process from a rigid substrate to a flexible one. The TFTs depict VON between -0.2 and 1 V, ION/IOFF > 104 and field-effect mobility >0.5 cm2 V-1 s-1. Additionally, in order to enhance the transistors and inverters performance, an adaptation on the device configuration, from an inverted coplanar to an inverted staggered setup, was conducted and analyzed. By employing the inverted staggered setup a considerable increase in the contact quality between the semiconductor and the drain and source electrodes was observed. As the integrated devices depict electrical characteristics which enable the fabrication of electronic circuits for the low-cost sector, inverters were fabricated and characterized, evaluating the circuit's gain as function of the applied supply voltage and circuit's geometric ratio.

Status and Needs of Power Electronics for Photovoltaic Inverters

Science.gov (United States)

Qin, Y. C.; Mohan, N.; West, R.; Bonn, R.

2002-06-01

Photovoltaics is the utility connected distributed energy resource (DER) that is in widespread use today. It has one element, the inverter, which is common with all DER sources except rotating generators. The inverter is required to transfer dc energy to ac energy. With all the DER technologies, (solar, wind, fuel cells, and microturbines) the inverter is still an immature product that will result in reliability problems in fielded systems. Today, the PV inverter is a costly and complex component of PV systems that produce ac power. Inverter MTFF (mean time to first failure) is currently unacceptable. Low inverter reliability contributes to unreliable fielded systems and a loss of confidence in renewable technology. The low volume of PV inverters produced restricts the manufacturing to small suppliers without sophisticated research and reliability programs or manufacturing methods. Thus, the present approach to PV inverter supply has low probability of meeting DOE reliability goals.

Tapping mode imaging and measurements with an inverted atomic force microscope.

Science.gov (United States)

Chan, Sandra S F; Green, John-Bruce D

2006-07-18

This report demonstrates the successful use of the inverted atomic force microscope (i-AFM) for tapping mode AFM imaging of cantilever-supported samples. i-AFM is a mode of AFM operation in which a sample supported on a tipless cantilever is imaged by one of many tips in a microfabricated tip array. Tapping mode is an intermittent contact mode whereby the cantilever is oscillated at or near its resonance frequency, and the amplitude and/or phase are used to image the sample. In the process of demonstrating that tapping mode images could be obtained in the i-AFM design, it was observed that the amplitude of the cantilever oscillation decreased markedly as the cantilever and tip array were approached. The source of this damping of the cantilever oscillations was identified to be the well-known "squeeze film damping", and the extent of damping was a direct consequence of the relatively shorter tip heights for the tip arrays, as compared to those of commercially available tapping mode cantilevers with integrated tips. The functional form for the distance dependence of the damping coefficient is in excellent agreement with previously published models for squeeze film damping, and the values for the fitting parameters make physical sense. Although the severe damping reduces the cantilever free amplitude substantially, we found that we were still able to access the low-amplitude regime of oscillation necessary for attractive tapping mode imaging of fragile molecules.

Dual-mode optical microscope based on single-pixel imaging

Science.gov (United States)

Rodríguez, A. D.; Clemente, P.; Tajahuerce, E.; Lancis, J.

2016-07-01

We demonstrate an inverted microscope that can image specimens in both reflection and transmission modes simultaneously with a single light source. The microscope utilizes a digital micromirror device (DMD) for patterned illumination altogether with two single-pixel photosensors for efficient light detection. The system, a scan-less device with no moving parts, works by sequential projection of a set of binary intensity patterns onto the sample that are codified onto a modified commercial DMD. Data to be displayed are geometrically transformed before written into a memory cell to cancel optical artifacts coming from the diamond-like shaped structure of the micromirror array. The 24-bit color depth of the display is fully exploited to increase the frame rate by a factor of 24, which makes the technique practicable for real samples. Our commercial DMD-based LED-illumination is cost effective and can be easily coupled as an add-on module for already existing inverted microscopes. The reflection and transmission information provided by our dual microscope complement each other and can be useful for imaging non-uniform samples and to prevent self-shadowing effects.

Power Inverter Topologies for Photovoltaic Modules - A Review

DEFF Research Database (Denmark)

Kjær, Søren Bækhøj; Pedersen, John Kim; Blaabjerg, Frede

2002-01-01

This review-paper focuses on the latest development of inverters for photovoltaic AC-Modules. The power range for these inverters is usually within 90 Watt to 500 Watt, which covers the most commercial photovoltaic-modules. Self-commutated inverters have replaced the grid-commutated ones. The same...... is true for the bulky low-frequency transformers versus the high-frequency transformers, which are used to adapt the voltage level. The AC-Module provides a modular design and a flexible behaviour in various grid conditions. It hereby opens the market for photovoltaic-power for everyone at a low cost due...

Atmospheric scanning electron microscope for correlative microscopy.

Science.gov (United States)

Morrison, Ian E G; Dennison, Clare L; Nishiyama, Hidetoshi; Suga, Mitsuo; Sato, Chikara; Yarwood, Andrew; O'Toole, Peter J

2012-01-01

The JEOL ClairScope is the first truly correlative scanning electron and optical microscope. An inverted scanning electron microscope (SEM) column allows electron images of wet samples to be obtained in ambient conditions in a biological culture dish, via a silicon nitride film window in the base. A standard inverted optical microscope positioned above the dish holder can be used to take reflected light and epifluorescence images of the same sample, under atmospheric conditions that permit biochemical modifications. For SEM, the open dish allows successive staining operations to be performed without moving the holder. The standard optical color camera used for fluorescence imaging can be exchanged for a high-sensitivity monochrome camera to detect low-intensity fluorescence signals, and also cathodoluminescence emission from nanophosphor particles. If these particles are applied to the sample at a suitable density, they can greatly assist the task of perfecting the correlation between the optical and electron images. Copyright © 2012 Elsevier Inc. All rights reserved.

Advances in PV Inverters

DEFF Research Database (Denmark)

Anthon, Alexander

and preferably low complexity leads to new research demands. This is especially true in the field of low cost residential PV inverters where efficiencies are used as major selling arguments. Traditional converter topologies equipped with conventional Silicon based semiconductors to date reach their limitations......, a replacement of only two switching devices per phase leg can greatly reduce the semiconductor losses. The Hybrid-NPC converter can be seen as an attractive and cost competitive alternative to the Silicon Carbide based converter, also allowing to overcome the major drawbacks with the conventional Silicon IGBT...

Stable Inverted Low-Bandgap Polymer Solar Cells with Aqueous Solution Processed Low-Temperature ZnO Buffer Layers

Directory of Open Access Journals (Sweden)

Chunfu Zhang

2016-01-01

Full Text Available Efficient inverted low-bandgap polymer solar cells with an aqueous solution processed low-temperature ZnO buffer layer have been investigated. The low-bandgap material PTB-7 is employed so that more solar light can be efficiently harvested, and the aqueous solution processed ZnO electron transport buffer layer is prepared at 150°C so that it can be compatible with the roll-to-roll process. Power conversion efficiency (PCE of the inverted device reaches 7.12%, which is near the control conventional device. More importantly, the inverted device shows a better stability, keeping more than 90% of its original PCE after being stored for 625 hours, while PCE of the conventional device is only 75% of what it was. In addition, it is found that the ZnO thin film annealed in N2 can obviously increase PCE of the inverted device further to 7.26%.

Low-cost capacitor voltage inverter for outstanding performance in piezoelectric energy harvesting.

Science.gov (United States)

Lallart, Mickaël; Garbuio, Lauric; Richard, Claude; Guyomar, Daniel

2010-01-01

The purpose of this paper is to propose a new scheme for piezoelectric energy harvesting optimization. The proposed enhancement relies on a new topology for inverting the voltage across a single capacitor with reduced losses. The increase of the inversion quality allows a much more effective energy harvesting process using the so-called synchronized switch harvesting on inductor (SSHI) nonlinear technique. It is shown that the proposed architecture, based on a 2-step inversion, increases the harvested power by a theoretical factor up to square root of 2 (i.e., 40% gain) compared with classical SSHI, allowing an increase of the harvested power by a factor greater than 1000% compared with the standard energy harvesting technique for realistic values of inversion components. The proposed circuit, using only 4 digital switches and an intermediate capacitor, is also ultra-low power, because the inversion circuit does not require any external energy and the command signals are very simple.

A "two-objective, one-area" procedure in absorption microphotometry and its application using an inverted microscope.

Science.gov (United States)

Chaubal, K A

1988-08-01

A 'two-objective, one-area' method and related equations are suggested to measure absorbance of microscopic stained objects. In such work, the measuring field invariably includes an image of the object and some clear area surrounding the image. The total intensity in the two areas is measured photometrically, using two different objectives, and substituted in the equation for absorbance. The equation is independent of the term representing intensity from the clear area and hence the error in the measurement of absorbance is reduced. The limitations of the 'two-objective, one-area' method are discussed and its pragmatic operation described with an experimental setup involving an inverted microscope. The method permits measurement of intensity in a part of a stained cell while the rest of the cell remains in the field of view. The method is applied to measure absorbance in Giemsa stained ascites cells and Feulgen stained liver and Human Amnion cells.

Inverted base pavements: construction and performance

KAUST Repository

Papadopoulos, Efthymios

2017-05-11

Inverted base pavements involve a well-compacted granular aggregate base built between a thin asphalt concrete layer and a cement-treated base. Inverted base pavements can be constructed using conventional equipment and procedures but require proper quality control. This study reviews the extensive South African experience and case histories in the USA. Accumulating evidence suggests that inverted base pavements are a viable alternative and can outperform conventional pavements at a lower cost. Inverted base pavements rely on the complementary interaction between layers. The cement-treated base provides a stiff foundation for efficient compaction and constrains the deformation of the stress-sensitive granular aggregate base. The thin asphalt surface layer deforms as a membrane and develops low tensile stress. Additional large-scale field tests should be conducted to assess the performance of inverted base pavement designs in a wide range of conditions relevant to the USA.

Low axial drift stage and temperature controlled liquid cell for z-scan fluorescence correlation spectroscopy in an inverted confocal geometry

International Nuclear Information System (INIS)

Allgeyer, Edward S.; Sterling, Sarah M.; Neivandt, David J.; Mason, Michael D.

2011-01-01

A recent iteration of fluorescence correlation spectroscopy (FCS), z-scan FCS, has drawn attention for its elegant solution to the problem of quantitative sample positioning when investigating two-dimensional systems while simultaneously providing an excellent method for extracting calibration-free diffusion coefficients. Unfortunately, the measurement of planar systems using (FCS and) z-scan FCS still requires extremely mechanically stable sample positioning, relative to a microscope objective. As axial sample position serves as the inherent length calibration, instabilities in sample position will affect measured diffusion coefficients. Here, we detail the design and function of a highly stable and mechanically simple inverted microscope stage that includes a temperature controlled liquid cell. The stage and sample cell are ideally suited to planar membrane investigations, but generally amenable to any quantitative microscopy that requires low drift and excellent axial and lateral stability. In the present work we evaluate the performance of our custom stage system and compare it with the stock microscope stage and typical sample sealing and holding methods.

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...

A low voltage programmable unipolar inverter with a gold nanoparticle monolayer on plastic.

Science.gov (United States)

Zhou, Ye; Han, Su-Ting; Huang, Long-Biao; Huang, Jing; Yan, Yan; Zhou, Li; Roy, V A L

2013-05-24

A programmable low voltage unipolar inverter with saturated-load configuration has been demonstrated on a plastic substrate. A self-assembled monolayer of gold (Au) nanoparticles was inserted into the dielectric layer acting as a charge trapping layer. The inverter operated well with supply voltages of inverter. Furthermore, the programmable behavior was maintained well at various bending states, demonstrating the adequate flexibility of our devices.

A new inverter topology using GTO commutation. [Gate Turn Off thyristor

Science.gov (United States)

Rippel, W. E.

1983-01-01

A new N-phase, forced commutated bridge inverter topology has been developed wherein a single Gate Turn Off Thyristor (GTO) is used to commutate each of 2N main Thyristors (SCRs). Since, for most applications, the primary loss mechanism is the SCR forward drop, very high efficiencies are possible. Compared with conventional pure SCR and pure GTO inverters, cost per kW is lower - in the former case due to the large cost differential between GTOs and SCRs. Other advantages of the new inverter include high power density, low switching losses and stresses, modulation flexibility and amenability to high voltage and high frequency operation.

Multilevel DC Link Inverter for Brushless Permanent Magnet Motors with Very Low Inductance

International Nuclear Information System (INIS)

Su, G.J.

2001-01-01

Due to their long effective air gaps, permanent magnet motors tend to have low inductance. The use of ironless stator structure in present high power PM motors (several tens of kWs) reduces the inductance even further ( and lt; 100(micro)H). This low inductance imposes stringent current regulation demands for the inverter to obtain acceptable current ripple. An analysis of the current ripple for these low inductance brushless PM motors shows that a standard inverter with the most commonly used IGBT switching devices cannot meet the current regulation demands and will produce unacceptable current ripples due to the IGBT's limited switching frequency. This paper introduces a new multilevel dc link inverter, which can dramatically reduce the current ripple for brushless PM motor drives. The operating principle and design guidelines are included

Low-cost motility tracking system (LOCOMOTIS for time-lapse microscopy applications and cell visualisation.

Directory of Open Access Journals (Sweden)

Adam E Lynch

Full Text Available Direct visualisation of cells for the purpose of studying their motility has typically required expensive microscopy equipment. However, recent advances in digital sensors mean that it is now possible to image cells for a fraction of the price of a standard microscope. Along with low-cost imaging there has also been a large increase in the availability of high quality, open-source analysis programs. In this study we describe the development and performance of an expandable cell motility system employing inexpensive, commercially available digital USB microscopes to image various cell types using time-lapse and perform tracking assays in proof-of-concept experiments. With this system we were able to measure and record three separate assays simultaneously on one personal computer using identical microscopes, and obtained tracking results comparable in quality to those from other studies that used standard, more expensive, equipment. The microscopes used in our system were capable of a maximum magnification of 413.6×. Although resolution was lower than that of a standard inverted microscope we found this difference to be indistinguishable at the magnification chosen for cell tracking experiments (206.8×. In preliminary cell culture experiments using our system, velocities (mean µm/min ± SE of 0.81 ± 0.01 (Biomphalaria glabrata hemocytes on uncoated plates, 1.17 ± 0.004 (MDA-MB-231 breast cancer cells, 1.24 ± 0.006 (SC5 mouse Sertoli cells and 2.21 ± 0.01 (B. glabrata hemocytes on Poly-L-Lysine coated plates, were measured and are consistent with previous reports. We believe that this system, coupled with open-source analysis software, demonstrates that higher throughput time-lapse imaging of cells for the purpose of studying motility can be an affordable option for all researchers.

Low-cost motility tracking system (LOCOMOTIS) for time-lapse microscopy applications and cell visualisation.

Science.gov (United States)

Lynch, Adam E; Triajianto, Junian; Routledge, Edwin

2014-01-01

Direct visualisation of cells for the purpose of studying their motility has typically required expensive microscopy equipment. However, recent advances in digital sensors mean that it is now possible to image cells for a fraction of the price of a standard microscope. Along with low-cost imaging there has also been a large increase in the availability of high quality, open-source analysis programs. In this study we describe the development and performance of an expandable cell motility system employing inexpensive, commercially available digital USB microscopes to image various cell types using time-lapse and perform tracking assays in proof-of-concept experiments. With this system we were able to measure and record three separate assays simultaneously on one personal computer using identical microscopes, and obtained tracking results comparable in quality to those from other studies that used standard, more expensive, equipment. The microscopes used in our system were capable of a maximum magnification of 413.6×. Although resolution was lower than that of a standard inverted microscope we found this difference to be indistinguishable at the magnification chosen for cell tracking experiments (206.8×). In preliminary cell culture experiments using our system, velocities (mean µm/min ± SE) of 0.81 ± 0.01 (Biomphalaria glabrata hemocytes on uncoated plates), 1.17 ± 0.004 (MDA-MB-231 breast cancer cells), 1.24 ± 0.006 (SC5 mouse Sertoli cells) and 2.21 ± 0.01 (B. glabrata hemocytes on Poly-L-Lysine coated plates), were measured and are consistent with previous reports. We believe that this system, coupled with open-source analysis software, demonstrates that higher throughput time-lapse imaging of cells for the purpose of studying motility can be an affordable option for all researchers.

Low-Cost Motility Tracking System (LOCOMOTIS) for Time-Lapse Microscopy Applications and Cell Visualisation

Science.gov (United States)

Lynch, Adam E.; Triajianto, Junian; Routledge, Edwin

2014-01-01

Direct visualisation of cells for the purpose of studying their motility has typically required expensive microscopy equipment. However, recent advances in digital sensors mean that it is now possible to image cells for a fraction of the price of a standard microscope. Along with low-cost imaging there has also been a large increase in the availability of high quality, open-source analysis programs. In this study we describe the development and performance of an expandable cell motility system employing inexpensive, commercially available digital USB microscopes to image various cell types using time-lapse and perform tracking assays in proof-of-concept experiments. With this system we were able to measure and record three separate assays simultaneously on one personal computer using identical microscopes, and obtained tracking results comparable in quality to those from other studies that used standard, more expensive, equipment. The microscopes used in our system were capable of a maximum magnification of 413.6×. Although resolution was lower than that of a standard inverted microscope we found this difference to be indistinguishable at the magnification chosen for cell tracking experiments (206.8×). In preliminary cell culture experiments using our system, velocities (mean µm/min ± SE) of 0.81±0.01 (Biomphalaria glabrata hemocytes on uncoated plates), 1.17±0.004 (MDA-MB-231 breast cancer cells), 1.24±0.006 (SC5 mouse Sertoli cells) and 2.21±0.01 (B. glabrata hemocytes on Poly-L-Lysine coated plates), were measured and are consistent with previous reports. We believe that this system, coupled with open-source analysis software, demonstrates that higher throughput time-lapse imaging of cells for the purpose of studying motility can be an affordable option for all researchers. PMID:25121722

Active Damping Techniques for LCL-Filtered Inverters-Based Microgrids

DEFF Research Database (Denmark)

Lorzadeh, Iman; Firoozabadi, Mehdi Savaghebi; Askarian Abyaneh, Hossein

2015-01-01

LCL-type filters are widely used in gridconnected voltage source inverters, since it provides switching ripples reduction with lower cost and weight than the L-type counterpart. However, the inclusion of LCL-filters in voltage source inverters complicates the current control design regarding system...... the different active damping approaches for grid-connected inverters with LCL filters, which are based on high-order filters and additional feedbacks methods. These techniques are analyzed and discussed in detail....... stability issues; because an inherent resonance peak appears due to zero impedance at that resonance frequency. Moreover, in grid-interactive low-voltage microgrids, the interactions among the LCL-filtered-based parallel inverters may result in a more complex multiresonance issue which may compromise...

Regenerative Snubber For GTO-Commutated SCR Inverter

Science.gov (United States)

Rippel, Wally E.; Edwards, Dean B.

1992-01-01

Proposed regenerative snubbing circuit substituted for dissipative snubbing circuit in inverter based on silicon controlled rectifiers (SCR's) commutated by gate-turn-off thyristor (GTO). Intended to reduce loss of power that occurs in dissipative snubber. Principal criteria in design: low cost, simplicity, and reliability.

Shunt Active-Power-Filter Topology Based on Parallel Interleaved Inverters

DEFF Research Database (Denmark)

Blaabjerg, Frede; Asiminoaei, Lucian; Aeloiza, E.

2008-01-01

In this paper, an interleaved active-power-filter concept with reduced size of passive components is discussed. The topology is composed of two pulsewidth-modulation interleaved voltage-source inverters connected together on the ac line and sharing the same dc-link capacitor. The advantages......, because the power sharing allows one to use a higher switching frequency in each inverter. This paper analyzes the design of the passive components and gives a practical and low-cost solution for the minimization of the circulation currents between the inverters, by using common-mode coils. Several...

Impacts of PV Array Sizing on PV Inverter Lifetime and Reliability

OpenAIRE

Sangwongwanich, Ariya; Yang, Yongheng; Sera, Dezso; Blaabjerg, Frede

2017-01-01

In order to enable a more wide-scale utilization of PV systems, the cost of PV energy has to be comparable with other energy sources. Oversizing the PV array is one common approach to reduce the cost of PV energy, since it increases the PV energy yield during low solar irradiance conditions. However, oversizing the PV array will increase the loading of PV inverters, which may have undesired influence on the PV inverter lifetime and reliability. In that case, it may result in a negative impact...

Combined reflection and transmission microscope for telemedicine applications in field settings.

Science.gov (United States)

Biener, Gabriel; Greenbaum, Alon; Isikman, Serhan O; Lee, Kelvin; Tseng, Derek; Ozcan, Aydogan

2011-08-21

We demonstrate a field-portable upright and inverted microscope that can image specimens in both reflection and transmission modes. This compact and cost-effective dual-mode microscope weighs only ∼135 grams (image of the specimen onto an opto-electronic sensor-array that is positioned above the beam-splitter cube. In addition to this, the illumination beam is also partially transmitted through the same specimen, which then casts lensfree in-line holograms of the same objects onto a second opto-electronic sensor-array that is positioned underneath the beam-splitter cube. By rapid digital reconstruction of the acquired lensfree holograms, transmission images (both phase and amplitude) of the same specimen are also created. We tested the performance of this field-portable microscope by imaging various micro-particles, blood smears as well as a histopathology slide corresponding to skin tissue. Being compact, light-weight and cost-effective, this combined reflection and transmission microscope might especially be useful for telemedicine applications in resource limited settings. This journal is © The Royal Society of Chemistry 2011

Control Strategy of Three-Phase Photovoltaic Inverter under Low-Voltage Ride-Through Condition

Directory of Open Access Journals (Sweden)

Xianbo Wang

2015-01-01

Full Text Available The new energy promoting community has recently witnessed a surge of developments in photovoltaic power generation technologies. To fulfill the grid code requirement of photovoltaic inverter under low-voltage ride-through (LVRT condition, by utilizing the asymmetry feature of grid voltage, this paper aims to control both restraining negative sequence current and reactive power fluctuation on grid side to maintain balanced output of inverter. Two mathematical inverter models of grid-connected inverter containing LCL grid-side filter under both symmetrical and asymmetric grid are proposed. PR controller method is put forward based on inverter model under asymmetric grid. To ensure the stable operation of the inverter, grid voltage feedforward method is introduced to restrain current shock at the moment of voltage drop. Stable grid-connected operation and LVRT ability at grid drop have been achieved via a combination of rapid positive and negative sequence component extraction of accurate grid voltage synchronizing signals. Simulation and experimental results have verified the superior effectiveness of our proposed control strategy.

21 CFR 864.3600 - Microscopes and accessories.

Science.gov (United States)

2010-04-01

... enlarge images of specimens, preparations, and cultures for medical purposes. Variations of microscopes... light. (3) Inverted stage microscopes, which permit examination of tissue cultures or other biological... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Microscopes and accessories. 864.3600 Section 864...

27-Level DC–AC inverter with single energy source

International Nuclear Information System (INIS)

Tsang, K.M.; Chan, W.L.

2012-01-01

Highlights: ► This paper reports a novel 27-level DC–AC inverter using only single renewable energy source. ► The efficiency of the inverter is very high. The output waveform is almost sinusoidal. ► The cost is low as the number of power switches required is only 12. - Abstract: A novel design of multilevel DC–AC inverter using only single renewable energy source is presented in this paper. The proposed approach enables multilevel output to be realised by a few cascaded H-bridges and a single energy source. As an illustration, a 27-level inverter has been implemented based on three cascaded H-bridges with a single energy source and two capacitors. Using the proposed novel switching strategy, 27 levels can be realized and the two virtual energy sources can be well regulated. Experimental results are included to demonstrate the effectiveness of the proposed inverter.

Ultra-low-loss inverted taper coupler for silicon-on-insulator ridge waveguide

DEFF Research Database (Denmark)

Pu, Minhao; Liu, Liu; Ou, Haiyan

2010-01-01

An ultra-low-loss coupler for interfacing a silicon-on-insulator ridge waveguide and a single-mode fiber in both polarizations is presented. The inverted taper coupler, embedded in a polymer waveguide, is optimized for both the transverse-magnetic and transverse-electric modes through tapering...... the width of the silicon-on-insulator waveguide from 450 nm down to less than 15 nm applying a thermal oxidation process. Two inverted taper couplers are integrated with a 3-mm long silicon-on-insulator ridge waveguide in the fabricated sample. The measured coupling losses of the inverted taper coupler...... for transverse-magnetic and transverse-electric modes are ~0.36 dB and ~0.66 dB per connection, respectively....

Design optimization of transformerless grid-connected PV inverters including reliability

DEFF Research Database (Denmark)

Koutroulis, Eftichios; Blaabjerg, Frede

2012-01-01

Of the Electricity (LCOE) generated during the PV system lifetime period is minimized. The LCOE is calculated also considering the failure rates of the components, which affect the reliability performance and lifetime maintenance cost of the PV inverter. A design example is presented, demonstrating that compared...... to the non-optimized PV inverter structures, the PV inverters designed using the proposed optimization methodology exhibit lower total manufacturing and lifetime maintenance cost and inject more energy into the electric-grid and by that minimizing LCOE.......This paper presents a new methodology for optimal design of transformerless Photovoltaic (PV) inverters targeting a cost-effective deployment of grid-connected PV systems. The optimal values and types of the PV inverter components are calculated such that the PV inverter Levelized Cost...

Computer-controlled impalement of cells in retinal wholemounts visualized by infrared CCD imaging on an inverted microscope.

Science.gov (United States)

Reitsamer, H; Groiss, H P; Franz, M; Pflug, R

2000-01-31

We present a computer-guided microelectrode positioning system that is routinely used in our laboratory for intracellular electrophysiology and functional staining of retinal neurons. Wholemount preparations of isolated retina are kept in a superfusion chamber on the stage of an inverted microscope. Cells and layers of the retina are visualized by Nomarski interference contrast using infrared light in combination with a CCD camera system. After five-point calibration has been performed the electrode can be guided to any point inside the calibrated volume without moving the retina. Electrode deviations from target cells can be corrected by the software further improving the precision of this system. The good visibility of cells avoids prelabeling with fluorescent dyes and makes it possible to work under completely dark adapted conditions.

Coupled-Inductor-Based Aalborg Inverter With Input DC Energy Regulation

DEFF Research Database (Denmark)

Wang, Houqing; Wu, Weimin; Chung, Henry Shu-hung

2018-01-01

Due to the global environmental issues and energy crisis, the injection of renewable energy sources (RESs) into the power system is continuously increasing. As the interface between RESs and power grid, grid-tied inverters using MOSFET switches, without traditional line frequency transformers, show...... some potential advantages, in terms of low cost, high efficiency, and lightweight and small size. Among several proposed configurations, the Aalborg inverter was proposed as a new family of high efficiency MOSFET-switch-based hybrid source inverters. For a conventional “half bridge” type Aalborg...... inverter, due to the imbalance of two independent dc sources, the input dc energies may not be fully utilized, which may reduce the efficiency of whole system. In order to extract the maximum energy from two independent dc sources, a coupled-inductor-based “half bridge” type Aalborg inverter is proposed...

A Cost-Effective Atomic Force Microscope for Undergraduate Control Laboratories

Science.gov (United States)

Jones, C. N.; Goncalves, J.

2010-01-01

This paper presents a simple, cost-effective and robust atomic force microscope (AFM), which has been purposely designed and built for use as a teaching aid in undergraduate controls labs. The guiding design principle is to have all components be open and visible to the students, so the inner functioning of the microscope has been made clear to…

Inverted follicular keratosis: dermoscopic and reflectance confocal microscopic features.

Science.gov (United States)

Armengot-Carbo, M; Abrego, A; Gonzalez, T; Alarcon, I; Alos, L; Carrera, C; Malvehy, J; Puig, S

2013-01-01

Inverted follicular keratosis (IFK) is a rare benign tumor which usually appears as a firm papule on the face. The diagnosis is generally made by histopathology because the clinical appearance is difficult to differentiate from other lesions. Dermoscopic features of IFK have not been established to date. Herein we describe the dermoscopic findings of 4 cases of IFK. Radial peripheral hairpin vessels surrounded by a whitish halo arranged around a central white-yellowish amorphous area were observed in 3 cases, and glomerular vessels were present in the central area of one of them. The fourth case also presented a central white amorphous area but showed arborizing vessels. Reflectance confocal microscopy (available in 1 case) revealed a broadened honeycomb pattern, epidermal projections and hairpin and glomerular vessels. To our knowledge this is the first case series describing the dermoscopic features of inverted follicular keratosis and the first confocal microscopy description of this entity.

Atomic force microscope with integrated optical microscope for biological applications

OpenAIRE

Putman, Constant A.J.; Putman, C.A.J.; van der Werf, Kees; de Grooth, B.G.; van Hulst, N.F.; Segerink, Franciscus B.; Greve, Jan

1992-01-01

Since atomic force microscopy (AFM) is capable of imaging nonconducting surfaces, the technique holds great promises for high‐resolution imaging of biological specimens. A disadvantage of most AFMs is the fact that the relatively large sample surface has to be scanned multiple times to pinpoint a specific biological object of interest. Here an AFM is presented which has an incorporated inverted optical microscope. The optical image from the optical microscope is not obscured by the cantilever...

Real-time imaging of nitric oxide production in living cells with 1,3,5,7-tetramethyl-2,6-dicarbethoxy-8-(3',4'-diaminophenyl)-difluoroboradiaza-s-indacence by invert fluorescence microscope.

Science.gov (United States)

Huang, Ke-Jing; Wang, Hong; Ma, Ming; Zhang, Xian; Zhang, Hua-Shan

2007-02-01

Although the importance of nitric oxide (NO) as a signalling molecule in many biological processes is becoming increasingly evident, many proposed and potential biological functions of NO still remain unclear. Bioimaging is a good technique to visualize observation of nitric oxide in biological samples. In this report, a fluorescent probe, 1,3,5,7-tetramethyl-2,6-dicarbethoxy-8-(3',4'-diaminophenyl)-difluoroboradiaza-s-indacence (TMDCDABODIPY), has been first applied to real-time image NO produced in PC12 cells, Sf9 cells and human vascular endothelial cells at the presence of l-arginine with inverted fluorescence microscope. NO production in the cells is successfully captured and imaged with fine temporal and spatial resolution. The results prove that the probe combined with inverted fluorescence microscope can be developed into a sensitive and selective method for further study of NO release from cells.

Selective Harmonic Elimination in Asymmetric Cascaded Multilevel Inverters Using a New Low-frequency Strategy for Photovoltaic Applications

DEFF Research Database (Denmark)

Dowlatabadi, Mohammadkazem Bakhshizadeh; Iman-Eini, Hossein; Blaabjerg, Frede

2015-01-01

Asymmetric multilevel inverters with a main and auxiliary power circuit can yield maximum number of voltage levels against the number of semiconductor devices. Most of the output power will be produced by the main inverter, which works at low frequency and the auxiliary inverters only improve the...

Chromosome structure investigated with the atomic force microscope

NARCIS (Netherlands)

de Grooth, B.G.; Putman, C.A.J.; Putman, Constant A.; van der Werf, Kees; van Hulst, N.F.; van Oort, G.; van Oort, Geeske; Greve, Jan; Manne, Srinivas

1992-01-01

We have developed an atomic force microscope (AFM) with an integrated optical microscope. The optical microscope consists of an inverted epi-illumination system that yields images in reflection or fluorescence of the sample. With this system it is possible to quickly locate an object of interest. A

Foldscope: origami-based paper microscope.

Directory of Open Access Journals (Sweden)

James S Cybulski

Full Text Available Here we describe an ultra-low-cost origami-based approach for large-scale manufacturing of microscopes, specifically demonstrating brightfield, darkfield, and fluorescence microscopes. Merging principles of optical design with origami enables high-volume fabrication of microscopes from 2D media. Flexure mechanisms created via folding enable a flat compact design. Structural loops in folded paper provide kinematic constraints as a means for passive self-alignment. This light, rugged instrument can survive harsh field conditions while providing a diversity of imaging capabilities, thus serving wide-ranging applications for cost-effective, portable microscopes in science and education.

Optimal Design of Modern Transformerless PV Inverter Topologies

DEFF Research Database (Denmark)

Saridakis, Stefanos; Koutroulis, Eftichios; Blaabjerg, Frede

2013-01-01

the operational lifetime period of the PV installation, is also considered in the optimization process. According to the results of the proposed design method, different optimal values of the PV inverter design variables are derived for each PV inverter topology and installation site. The H5, H6, neutral point...... clamped, active-neutral point clamped and conergy-NPC PV inverters designed using the proposed optimization process feature lower levelized cost of generated electricity and lifetime cost, longer mean time between failures and inject more PV-generated energy into the electric grid than their nonoptimized......The design optimization of H5, H6, neutral point clamped, active-neutral point clamped, and conergy-NPC transformerless photovoltaic (PV) inverters is presented in this paper. The components reliability in terms of the corresponding malfunctions, affecting the PV inverter maintenance cost during...

Design Optimization of Transformerless Grid-Connected PV Inverters Including Reliability

DEFF Research Database (Denmark)

Koutroulis, Eftichios; Blaabjerg, Frede

2013-01-01

such that the PV inverter LCOE generated during the PV system lifetime period is minimized. The LCOE is also calculated considering the failure rates of the components, which affect the reliability performance and lifetime maintenance cost of the PV inverter. A design example is presented, demonstrating...... that compared to the nonoptimized PV inverter structures, the PV inverters designed using the proposed optimization methodology exhibit lower total manufacturing and lifetime maintenance cost and inject more energy into the electric-grid and by that minimizing LCOE.......This paper presents a new methodology for optimal design of transformerless photovoltaic (PV) inverters targeting a cost-effective deployment of grid-connected PV systems. The optimal switching frequency as well as the optimal values and types of the PV inverter components is calculated...

Electron microscopic observation at low temperature on superconductors

International Nuclear Information System (INIS)

Yokota, Yasuhiro; Hashimoto, Hatsujiro; Yoshida, Hiroyuki.

1991-01-01

The authors have observed superconducting materials with a high resolution electron microscope at liquid helium temperature. First, observation was carried out on Nb system intermetallic compounds such as Nb 3 Al and Nb 3 Sn of Al 5 type and Nb 3 Ge of 11 type at extremely low temperature. Next, the observation of high temperature superconductive ceramics in the state of superconductivity was attempted. In this paper, first the development of the liquid helium sample holder for a 400 kV electron microscope to realize the observation is reported. Besides, the sample holder of Gatan Co. and an extremely low temperature, high resolution electron microscope with a superconducting lens are described. The purpose of carrying out the electron microscope observation of superconductors at low temperature is the direct observation of the crystalline lattice image in the state of superconductivity. Also the structural transformation from tetragonal crystals to rhombic crystals in Al 5 type superconductors can be observed. The results of observation are reported. (K.I.)

Simplified High-Power Inverter

Science.gov (United States)

Edwards, D. B.; Rippel, W. E.

1984-01-01

Solid-state inverter simplified by use of single gate-turnoff device (GTO) to commutate multiple silicon controlled rectifiers (SCR's). By eliminating conventional commutation circuitry, GTO reduces cost, size and weight. GTO commutation applicable to inverters of greater than 1-kilowatt capacity. Applications include emergency power, load leveling, drives for traction and stationary polyphase motors, and photovoltaic-power conditioning.

Microscopical advances in assisted reproduction.

Science.gov (United States)

Baccetti, B

2004-01-01

In a series of papers carried out by this laboratory it was demonstrated that the quality of sterile males sperm, assessed submicroscopically and mathematically, is closely correlated with the success of the various procedures of assisted reproduction. If we attempt to select hypothetically optimal spermatozoa destined to the ICSI by light inverted microscopy, a considerable amount of ultrastructural information is lost and our selection is merely based on the motility. In this study we apply polarization microscopy to the ICSI technique, introducing polarizing and analyzing lenses in an inverted microscope model, operating in a transparent container. The retardation of the birefringence in the various organelles is evaluated by compensators, and the images are transmitted to a video system, and stored in a computer. Spermatozoa are maintained alive and perfectly motile in this polarizing inverted microscope, and the character of the birefringence is the same as in fixed and sectioned biological material examined by polarization microscopy. The birefringence of the sperm structures allows a sperm analysis closer to TEM than to phase contrast light microscopy analysis.

Control of Grid Interactive PV Inverters for High Penetration in Low Voltage Distribution Networks

DEFF Research Database (Denmark)

Demirok, Erhan

Regarding of high density deployment of PV installations in electricity grids, new technical challenges such as voltage rise, thermal loading of network components, voltage unbalance, harmonic interaction and fault current contributions are being added to tasks list of distribution system operators...... of these inverters may depend on grid connection rules which are forced by DSOs. Minimum requirement expected from PV inverters is to transfer maximum power by taking direct current (DC) form from PV modules and release it into AC grid and also continuously keep the inverters synchronized to the grid even under...... for this problem but PV inverters connected to highly capacitive networks are able to employ extra current and voltage harmonics compensation to avoid triggering network resonances at low order frequencies. The barriers such as harmonics interaction, flicker, fault current contribution and dc current injections...

Low voltage ride-through of single-phase transformerless photovoltaic inverters

DEFF Research Database (Denmark)

Yang, Yongheng; Blaabjerg, Frede; Wang, Huai

2013-01-01

Transformerless photovoltaic (PV) inverters are going to be more widely adopted in order to achieve high efficiency, as the penetration level of PV systems is continuously booming. However, problems may arise in highly PV-integrated distribution systems. For example, a sudden stoppage of all PV...... discussed. The selected inverters are the full-bridge inverter with bipolar modulation, full-bridge inverter with DC bypass and the Highly Efficient and Reliable Inverter Concept (HERIC). A 1 kW single-phase grid-connected PV system is analyzed to verify the discussions. The tests confirmed that, although...

Low Voltage Ride-Through of Single-Phase Transformerless Photovoltaic Inverters

DEFF Research Database (Denmark)

Yang, Yongheng; Blaabjerg, Frede; Wang, Huai

2014-01-01

Transformerless photovoltaic (PV) inverters are going to be more widely adopted in order to achieve high efficiency, as the penetration level of PV systems is continuously booming. However, problems may arise in highly PV-integrated distribution systems. For example, a sudden stoppage of all PV...... are also discussed. The selected inverters are the full-bridge inverter with bipolar modulation, full-bridge inverter with DC bypass and the Highly Efficient and Reliable Inverter Concept (HERIC). A 1 kW singlephase grid-connected PV system is analyzed to verify the discussions. The tests confirmed that...

S4 Grid-Connected Single-Phase Transformerless Inverter for PV Application

DEFF Research Database (Denmark)

Ardashir, Jaber Fallah; Siwakoti, Yam Prasad; Sabahi, Mehran

2016-01-01

This paper introduces a new single-phase transformerless inverter for grid-connected photovoltaic systems with low leakage current. It consists of four power switches, two diodes, two capacitors and a filter at the output stage. The neutral of the grid is directly connected to the negative terminal...... size, low cost, flexible grounding configuration and higher efficiency. The operating principle and analysis of the proposed circuit are presented in details. Experimental results of a 500 W prototype are demonstrated to validate the proposed topology and the overall concept. The results obtained...... clearly verify the performance of the proposed inverter and its practical application for grid-connected PV systems....

FahamecV1:A Low Cost Automated Metaphase Detection System

Directory of Open Access Journals (Sweden)

H. Yilmaz

2017-12-01

Full Text Available In this study, FahamecV1 is introduced and investigated as a low cost and high accuracy solution for metaphase detection. Chromosome analysis is performed at the metaphase stage and high accuracy and automated detection of the metaphase stage plays an active role in decreasing analysis time. FahamecV1 includes an optic microscope, a motorized microscope stage, an electronic control unit, a camera, a computer and a software application. Printing components of the motorized microscope stage (using a 3D printer is of the main reasons for cost reduction. Operations such as stepper motor calibration, are detection, focusing, scanning, metaphase detection and saving of coordinates into a database are automatically performed. To detect metaphases, a filter named Metafilter is developed and applied. Average scanning time per preparate is 77 sec/cm2. True positive rate is calculated as 95.1%, true negative rate is calculated as 99.0% and accuracy is calculated as 98.8%.

Low-cost mobile phone microscopy with a reversed mobile phone camera lens.

Directory of Open Access Journals (Sweden)

Neil A Switz

Full Text Available The increasing capabilities and ubiquity of mobile phones and their associated digital cameras offer the possibility of extending low-cost, portable diagnostic microscopy to underserved and low-resource areas. However, mobile phone microscopes created by adding magnifying optics to the phone's camera module have been unable to make use of the full image sensor due to the specialized design of the embedded camera lens, exacerbating the tradeoff between resolution and field of view inherent to optical systems. This tradeoff is acutely felt for diagnostic applications, where the speed and cost of image-based diagnosis is related to the area of the sample that can be viewed at sufficient resolution. Here we present a simple and low-cost approach to mobile phone microscopy that uses a reversed mobile phone camera lens added to an intact mobile phone to enable high quality imaging over a significantly larger field of view than standard microscopy. We demonstrate use of the reversed lens mobile phone microscope to identify red and white blood cells in blood smears and soil-transmitted helminth eggs in stool samples.

Low-cost mobile phone microscopy with a reversed mobile phone camera lens.

Science.gov (United States)

Switz, Neil A; D'Ambrosio, Michael V; Fletcher, Daniel A

2014-01-01

The increasing capabilities and ubiquity of mobile phones and their associated digital cameras offer the possibility of extending low-cost, portable diagnostic microscopy to underserved and low-resource areas. However, mobile phone microscopes created by adding magnifying optics to the phone's camera module have been unable to make use of the full image sensor due to the specialized design of the embedded camera lens, exacerbating the tradeoff between resolution and field of view inherent to optical systems. This tradeoff is acutely felt for diagnostic applications, where the speed and cost of image-based diagnosis is related to the area of the sample that can be viewed at sufficient resolution. Here we present a simple and low-cost approach to mobile phone microscopy that uses a reversed mobile phone camera lens added to an intact mobile phone to enable high quality imaging over a significantly larger field of view than standard microscopy. We demonstrate use of the reversed lens mobile phone microscope to identify red and white blood cells in blood smears and soil-transmitted helminth eggs in stool samples.

Toward the development of a low-cost laser Doppler module for ophthalmic microscopes

Science.gov (United States)

Cattini, Stefano; Rovati, Luigi

2012-03-01

A laser Doppler module easily integrated into a commercial ophthalmic microscope is proposed. Such setup adds flow measurement capability to standard visual inspection of the fundus. The proposed instrument may provide important clinical information such as the detection of vessel occlusion provided by surgical treatments (i.e. photocoagulation). The measuring system is based on a self-mixing laser diode Doppler flowmeter (SM-DF). Reduced costs, easy implementation and small size represent the main features of SM-DF. Moreover, this technique offers the advantage to have the excitation and measurement beams spatially overlapped, thus both overcoming the alignment difficulty of traditional laser Doppler flowmeter and, well fitting with to limited optical aperture of the pupil. Thanks to an on-board DSP-microcontroller, the optoelectronic module directly estimates the blood flow; USB connection and an ad-hoc developed user-friendly software interface allow displaying the result on a personal computer. Preliminary test demonstrates the applicability of the proposed measuring system.

A Family of Cost-Effective Magnetically-Coupled Impedance Source Inverters

DEFF Research Database (Denmark)

Li, Kerui; Yang, Yongheng; Qin, Zian

2017-01-01

of required semiconductor switches is reduced. More important, the elimination of leakage currents makes it particularly suitable for high-efficiency photovoltaic (PV) applications. A comparison among prior-art PV inverters is then performed. The Performances of the inverters are evaluated analytically...

Fast Self-Synchronization between LowVoltage Microgrid and Inverter using Virtual Synchronous Converter

Directory of Open Access Journals (Sweden)

Md Ruhul Amin

2017-12-01

Full Text Available In this paper, a fast self-synchronization known as virtual synchronous converter (VSCon between single-phase microgrid and inverter in low-voltage microgrid, has been developed in Matlab/Simulink. The idea is to any phase locked loop (PLL circuit for inverter-microgrid synchronization in order to improve the synchronization time. As known, it is difficult and lengthy process to tune the PLL gain parameters to reach suitable performance for synchronizing among the voltage, phase-angle and frequency between them. Due to this problem, a fast self synchronization technique is needed in order to minimize the time losses at the microgrid connection. Therefore, the VSCon has been developed which is based on the synchronous generator mathematical model but in virtual environment representation. It has been applied in the inverter control for generating switching pattern to the inverter switches in order to respond to the grid voltage for improve the synchronization. For a prove of concept, several simulation tests in MATLAB models have been conducted, in order to see the effectiveness of this VSCon. First test has been conducted, when a 240V, 50Hz frequency grid source is used for observing the self-synchronization the system with the power flows output. Furthermore, the next test is conducted when the grid frequency is changed from the rated frequency at 50Hz to 51Hz and the result shows the VSCon in inverter control takes nearly 40ms to synchronize to this new frequency value. The test on grid phase-angle delay also been tested when ac grid voltage has 150 phase delay. As from all the results, the improved inverter control with VSCon structure is able to have fast and self-synchronized between the invertergrid connection before the power from the inverter can be transferred.

Improvements in EMC performance of inverter-fed motor drives

International Nuclear Information System (INIS)

Zhong, E.; Lipo, T.A.

1995-01-01

An experimental investigation of conducted radio-noise emission from a conventional pulse width modulated (PWM) inverter of medium power feeding an induction motor is described. It is determined that the inverter system generates considerable impulse currents through the power leads feeding the system resulting in serious conducted electromagnetic interference (EMI) problems and significant voltage waveform distortion in the power system. The dominant emission sources in the system are identified. A proposed model of the drive system for the purpose of evaluation of EMI are developed. Several low-cost strategies for improvement in EMC performance of the PWM inverter are then proposed. Experimental results demonstrate that disturbance from the modified system can be dramatically reduced and that the EMC performance of the system has come very close to meeting the IEC CISPR and FCC limits on conducted emissions for digital devices

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...

Optimal design of NPC and Active-NPC transformerless PV inverters

DEFF Research Database (Denmark)

Saridakis, Stefanos; Koutroulis, Eftichios; Blaabjerg, Frede

2012-01-01

Targeting at a cost-effective deployment of grid-connected PhotoVoltaic (PV) systems, this paper presents a new methodology for the optimal design of transformerless PV inverters, which are based on the Neutral Point Clamped (NPC) and the Active-Neutral Point Clamped (ANPC) topologies. The design...... optimization results demonstrate that a different set of optimal values of the PV inverter switching frequency and output filter components are derived for the NPC and ANPC topologies, respectively, as well as for each of the PV inverter installation sites under study. The NPC and ANPC PV inverter structures......, which are derived using the proposed design optimization methodology exhibit lower Levelized Cost Of generated Electricity (LCOE) and manufacturing cost and they are simultaneously capable to inject more energy into the electric grid than the corresponding non-optimized PV inverters. Thus, the proposed...

Low-Cost Digital Implementation of Proportional-Resonant Current Controllers for PV Inverter Applications Using Delta Operator

DEFF Research Database (Denmark)

Sera, Dezso; Kerekes, Tamas; Lungeanu, Marian

2005-01-01

the possibility of selective harmonic compensation. However, in case of digital implementation on a low-cost fixedpoint DSP, the limited computational power and the limited numerical representation precision can restrict the utilization of it. The present paper proposes a different way of digital implementation...... of the P+Resonant controller with selective harmonic compensation on a low-cost fixed-point DSP. The resonant part of the P+R has been implemented as a second order filter based on Delta operator. The current controller, together with harmonic compensation for the 3rd, 5th, and 7th harmonics has been...

Fully patterned and low temperature transparent ZnO-based inverters

Energy Technology Data Exchange (ETDEWEB)

Gutierrez-Heredia, G. [Centro de Investigación en Materiales Avanzados, Unidad Monterrey, México (Mexico); Department of Materials Science and Engineering, University of Texas at Dallas (United States); Mejia, I.; Rivas-Aguilar, M.E.; Hernandez-Como, N. [Department of Materials Science and Engineering, University of Texas at Dallas (United States); Martinez-Landeros, V.H. [Centro de Investigación en Materiales Avanzados, Unidad Monterrey, México (Mexico); Department of Materials Science and Engineering, University of Texas at Dallas (United States); Aguirre-Tostado, F.S. [Centro de Investigación en Materiales Avanzados, Unidad Monterrey, México (Mexico); Quevedo-Lopez, M.A., E-mail: mquevedo@utdallas.edu [Department of Materials Science and Engineering, University of Texas at Dallas (United States)

2013-10-31

The fabrication and characterization of transparent logic inverters based on zinc oxide (ZnO) thin film transistors (TFTs) is reported. The inverters are fabricated using standard photolithographic techniques on glass substrates, and the entire fabrication process temperature is maintained < 100 °C, which render the devices suitable for flexible and transparent electronics applications. Pulsed laser deposition is used to deposit aluminum-doped zinc oxide and ZnO as electrode and active semiconductor materials, respectively. Electrical characterization for individual TFTs demonstrate mobilities of ∼ 10 cm{sup 2}/V-s, threshold voltages of 6 V, sub-threshold slopes of 630 mV/decade and I{sub ON}/I{sub OFF} ratios of 5 × 10{sup 6}. Films characterized by UV-Vis showed optical transmission > 80% in the visible spectrum. The inverters are analyzed with AC input signals at frequencies of 100 and 500 Hz. The AC response shows an average rise and fall time transitions of 0.65 and 0.44 ms, respectively. Measured inverters delay is in the order of 0.21 ms. - Highlights: • Logic inverters based on zinc oxide thin film transistors. • Inverters fabricated using temperatures below 100 °C and standard photolithography. • Transparent aluminum-doped zinc oxide as gate, drain and source electrodes. • Devices with total transmittance in the visible range above 80%. • AC inverter response up to 500 Hz.

Fully patterned and low temperature transparent ZnO-based inverters

International Nuclear Information System (INIS)

Gutierrez-Heredia, G.; Mejia, I.; Rivas-Aguilar, M.E.; Hernandez-Como, N.; Martinez-Landeros, V.H.; Aguirre-Tostado, F.S.; Quevedo-Lopez, M.A.

2013-01-01

The fabrication and characterization of transparent logic inverters based on zinc oxide (ZnO) thin film transistors (TFTs) is reported. The inverters are fabricated using standard photolithographic techniques on glass substrates, and the entire fabrication process temperature is maintained < 100 °C, which render the devices suitable for flexible and transparent electronics applications. Pulsed laser deposition is used to deposit aluminum-doped zinc oxide and ZnO as electrode and active semiconductor materials, respectively. Electrical characterization for individual TFTs demonstrate mobilities of ∼ 10 cm 2 /V-s, threshold voltages of 6 V, sub-threshold slopes of 630 mV/decade and I ON /I OFF ratios of 5 × 10 6 . Films characterized by UV-Vis showed optical transmission > 80% in the visible spectrum. The inverters are analyzed with AC input signals at frequencies of 100 and 500 Hz. The AC response shows an average rise and fall time transitions of 0.65 and 0.44 ms, respectively. Measured inverters delay is in the order of 0.21 ms. - Highlights: • Logic inverters based on zinc oxide thin film transistors. • Inverters fabricated using temperatures below 100 °C and standard photolithography. • Transparent aluminum-doped zinc oxide as gate, drain and source electrodes. • Devices with total transmittance in the visible range above 80%. • AC inverter response up to 500 Hz

Efficient inverted bulk-heterojunction solar cells from low-temperature processing of amorphous ZnO buffer layers

KAUST Repository

Jagadamma, Lethy Krishnan; Abdelsamie, Maged; El Labban, Abdulrahman; Aresu, Emanuele; Ngongang Ndjawa, Guy Olivier; Anjum, Dalaver H.; Cha, Dong Kyu; Beaujuge, Pierre; Amassian, Aram

2014-01-01

In this report, we demonstrate that solution-processed amorphous zinc oxide (a-ZnO) interlayers prepared at low temperatures (∼100 °C) can yield inverted bulk-heterojunction (BHJ) solar cells that are as efficient as nanoparticle-based ZnO requiring comparably more complex synthesis or polycrystalline ZnO films prepared at substantially higher temperatures (150-400 °C). Low-temperature, facile solution-processing approaches are required in the fabrication of BHJ solar cells on flexible plastic substrates, such as PET. Here, we achieve efficient inverted solar cells with a-ZnO buffer layers by carefully examining the correlations between the thin film morphology and the figures of merit of optimized BHJ devices with various polymer donors and PCBM as the fullerene acceptor. We find that the most effective a-ZnO morphology consists of a compact, thin layer with continuous substrate coverage. In parallel, we emphasize the detrimental effect of forming rippled surface morphologies of a-ZnO, an observation which contrasts with results obtained in polycrystalline ZnO thin films, where rippled morphologies have been reported to improve efficiency. After optimizing the a-ZnO morphology at low processing temperature for inverted P3HT:PCBM devices, achieving a power conversion efficiency (PCE) of ca. 4.1%, we demonstrate inverted solar cells with low bandgap polymer donors on glass/flexible PET substrates: PTB7:PC71BM (PCE: 6.5% (glass)/5.6% (PET)) and PBDTTPD:PC71BM (PCE: 6.7% (glass)/5.9% (PET)). Finally, we show that a-ZnO based inverted P3HT:PCBM BHJ solar cells maintain ca. 90-95% of their initial PCE even after a full year without encapsulation in a nitrogen dry box, thus demonstrating excellent shelf stability. The insight we have gained into the importance of surface morphology in amorphous zinc oxide buffer layers should help in the development of other low-temperature solution-processed metal oxide interlayers for efficient flexible solar cells. This journal is

Linear polarization-discriminatory state inverter fabricated by oblique angle deposition.

Science.gov (United States)

Park, Yong Jun; Sobahan, K M A; Kim, Jin Joo; Hwangbo, Chang Kwon

2009-06-22

In this paper, we report a linear polarization-discriminatory state inverter made of three-layer sculpture thin film fabricated by oblique angle deposition technique. The first and third layers are quarter-wave plates of zigzag structure and the middle of them is a circular Bragg reflector of left-handed helical structure. It is found that the normal incidence of P-polarized light on this polarization-discriminatory state inverter becomes the S-polarized light at output, while the incident S-polarized light of wavelength lying in the Bragg regime is reflected. The microstructure of the linear polarization-discriminatory state inverter is also investigated by using a scanning electron microscope.

Power control flexibilities for grid-connected multi-functional photovoltaic inverters

DEFF Research Database (Denmark)

Yang, Yongheng; Blaabjerg, Frede; Wang, Huai

2014-01-01

to reduced cost of energy. To implement the advanced features, a flexible power controller is developed in this paper, which can be configured in the PV inverter and flexibly be changed from one to another. This power control strategy is based on the single-phase PQ theory, and it offers the possibilities...... of ancillary and intelligent services, like Low Voltage Ride-Through (LVRT), reactive power compensation, and reliability-oriented thermal management/control by PV systems is a key to attain higher utilization of solar energy. Those essential functionalities for the future PV inverters can contribute...... to generate appropriate references for the inner current control loop. The references depend on the system conditions and also specific demands from both system operators and customers. Besides, this power control strategy can be implemented in a commercial PV inverter as standardized functions, and also...

Overload protection system for power inverter

Science.gov (United States)

Nagano, S. (Inventor)

1977-01-01

An overload protection system for a power inverter utilized a first circuit for monitoring current to the load from the power inverter to detect an overload and a control circuit to shut off the power inverter, when an overload condition was detected. At the same time, a monitoring current inverter was turned on to deliver current to the load at a very low power level. A second circuit monitored current to the load, from the monitoring current inverter, to hold the power inverter off through the control circuit, until the overload condition was cleared so that the control circuit may be deactivated in order for the power inverter to be restored after the monitoring current inverter is turned off completely.

A New Method of On-line Grid Impedance Estimation for PV Inverter

DEFF Research Database (Denmark)

Teodorescu, Remus; Asiminoaei, Lucian; Blaabjerg, Frede

2004-01-01

for on-line measuring the grid impedance is presented. The presented method requires no extra hardware being accommodated by typical PV inverters, sensors and CPU, to provide a fast and low cost approach of on-line impedance measurement. By injecting a non-characteristic harmonic current and measuring...

Nanowire NMOS Logic Inverter Characterization.

Science.gov (United States)

Hashim, Yasir

2016-06-01

This study is the first to demonstrate characteristics optimization of nanowire N-Channel Metal Oxide Semiconductor (NW-MOS) logic inverter. Noise margins and inflection voltage of transfer characteristics are used as limiting factors in this optimization. A computer-based model used to produce static characteristics of NW-NMOS logic inverter. In this research two circuit configuration of NW-NMOS inverter was studied, in first NW-NMOS circuit, the noise margin for (low input-high output) condition was very low. For second NMOS circuit gives excellent noise margins, and results indicate that optimization depends on applied voltage to the inverter. Increasing gate to source voltage with (2/1) nanowires ratio results better noise margins. Increasing of applied DC load transistor voltage tends to increasing in decreasing noise margins; decreasing this voltage will improve noise margins significantly.

Implementation and Test of On-line Embedded Grid Impedance Estimation for PV-inverters

DEFF Research Database (Denmark)

Asiminoaei, Lucian; Teodorescu, Remus; Blaabjerg, Frede

2004-01-01

to evaluate the grid impedance directly by the PV-inverter, providing a fast and low cost implementation. This principle theoretically provides a correct result of the grid impedance but when using it into the context of PV integration, different implementation issues strongly affect the quality...... of the results. This paper presents a new impedance estimation method including typical implementation problems encountered and it also presents adopted solutions for on-line grid impedance measurement. Practical tests on an existing PV-inverter validate the chosen solutions....

Single InAs/GaSb nanowire low-power CMOS inverter.

Science.gov (United States)

Dey, Anil W; Svensson, Johannes; Borg, B Mattias; Ek, Martin; Wernersson, Lars-Erik

2012-11-14

III-V semiconductors have so far predominately been employed for n-type transistors in high-frequency applications. This development is based on the advantageous transport properties and the large variety of heterostructure combinations in the family of III-V semiconductors. In contrast, reports on p-type devices with high hole mobility suitable for complementary metal-oxide-semiconductor (CMOS) circuits for low-power operation are scarce. In addition, the difficulty to integrate both n- and p-type devices on the same substrate without the use of complex buffer layers has hampered the development of III-V based digital logic. Here, inverters fabricated from single n-InAs/p-GaSb heterostructure nanowires are demonstrated in a simple processing scheme. Using undoped segments and aggressively scaled high-κ dielectric, enhancement mode operation suitable for digital logic is obtained for both types of transistors. State-of-the-art on- and off-state characteristics are obtained and the individual long-channel n- and p-type transistors exhibit minimum subthreshold swings of SS = 98 mV/dec and SS = 400 mV/dec, respectively, at V(ds) = 0.5 V. Inverter characteristics display a full signal swing and maximum gain of 10.5 with a small device-to-device variability. Complete inversion is measured at low frequencies although large parasitic capacitances deform the waveform at higher frequencies.

Asymmetrical and symmetrical embedded Z-source inverters

DEFF Research Database (Denmark)

Gao, F.; Loh, P.C.; Li, D.

2011-01-01

ends, which indirectly translates to a lowering of overall system cost. These noted advantages are indeed appropriate for applications like photovoltaic and fuel cell energy harnessing, and have already been confirmed in simulation and experimentally using a laboratory-implemented inverter prototype.......This study presents two types of embedded Z-source inverters with each type further divided into asymmetrical and symmetrical realisations. Being different from their traditional counterparts, the presented inverters have their dc sources inserted within their X-shaped impedance networks so...

Inverted papilloma of the cervix and vagina: report of 2 cases of a rare lesion associated with human papillomavirus 42.

Science.gov (United States)

Hennell, Claire; Jamison, Jackie; Wells, Michael; McCluggage, W Glenn

2012-03-01

We report 2 cases of a lesion that we term inverted papilloma of the lower female genital tract, occurring in the cervix and upper vagina of 60- and 50-year-old women, respectively. Microscopically, the features were similar to those of inverted transitional papilloma of the urinary bladder with interconnecting islands, trabeculae, and solid sheets of bland transitional epithelium with an inverted growth pattern. There were small foci of squamous and glandular differentiation in the cervical case. Linear array human papillomavirus genotyping revealed human papillomavirus type 42 in both cases. Inverted papilloma in the lower female genital tract is extremely rare with, as far as we are aware, only 3 previously reported similar cases in the cervix and none in the vagina. Our results suggest that these neoplasms when occurring in the lower female genital tract may be associated with low-risk human papillomavirus, perhaps specifically human papillomavirus 42. Copyright © 2012 Elsevier Inc. All rights reserved.

Characterization of the Ecosole HCPV tracker and single module inverter

Science.gov (United States)

Carpanelli, Maurizio; Borelli, Gianni; Verdilio, Daniele; De Nardis, Davide; Migali, Fabrizio; Cancro, Carmine; Graditi, Giorgio

2015-09-01

BECAR, the Beghelli group's R&D company, is leading ECOSOLE (Elevated COncentration SOlar Energy), one of the largest European Demonstration projects in solar photovoltaic. ECOSOLE, started in 2012, is focused on the study, design, and realization of new HCPV generator made of high efficiency PV modules equipped with SoG (Silicone on Glass) fresnel lenses and III-V solar cells, and a low cost matched solar tracker with distributed inverters approach. The project also regards the study and demonstration of new high throughput methods for the industrial large scale productions, at very low manufacturing costs. This work reports the description of the characterization of the tracker and single module.

Module Embedded Micro-inverter Smart Grid Ready Residential Solar Electric System

Energy Technology Data Exchange (ETDEWEB)

Agamy, Mohammed [GE Global Research Center, Niskayuna, NY (United States)

2015-10-27

The “Module Embedded Micro-inverter Smart Grid Ready Residential Solar Electric System” program is focused on developing innovative concepts for residential photovoltaic (PV) systems with the following objectives: to create an Innovative micro-inverter topology that reduces the cost from the best in class micro-inverter and provides high efficiency (>96% CEC - California Energy Commission), and 25+ year warranty, as well as reactive power support; integrate micro-inverter and PV module to reduce system price by at least $0.25/W through a) accentuating dual use of the module metal frame as a large area heat spreader reducing operating temperature, and b) eliminating redundant wiring and connectors; and create micro-inverter controller handles smart grid and safety functions to simplify implementation and reduce cost.

Multilevel DC link inverter

Science.gov (United States)

Su, Gui-Jia

2003-06-10

A multilevel DC link inverter and method for improving torque response and current regulation in permanent magnet motors and switched reluctance motors having a low inductance includes a plurality of voltage controlled cells connected in series for applying a resulting dc voltage comprised of one or more incremental dc voltages. The cells are provided with switches for increasing the resulting applied dc voltage as speed and back EMF increase, while limiting the voltage that is applied to the commutation switches to perform PWM or dc voltage stepping functions, so as to limit current ripple in the stator windings below an acceptable level, typically 5%. Several embodiments are disclosed including inverters using IGBT's, inverters using thyristors. All of the inverters are operable in both motoring and regenerating modes.

Study on model current predictive control method of PV grid- connected inverters systems with voltage sag

Science.gov (United States)

Jin, N.; Yang, F.; Shang, S. Y.; Tao, T.; Liu, J. S.

2016-08-01

According to the limitations of the LVRT technology of traditional photovoltaic inverter existed, this paper proposes a low voltage ride through (LVRT) control method based on model current predictive control (MCPC). This method can effectively improve the photovoltaic inverter output characteristics and response speed. The MCPC method of photovoltaic grid-connected inverter designed, the sum of the absolute value of the predictive current and the given current error is adopted as the cost function with the model predictive control method. According to the MCPC, the optimal space voltage vector is selected. Photovoltaic inverter has achieved automatically switches of priority active or reactive power control of two control modes according to the different operating states, which effectively improve the inverter capability of LVRT. The simulation and experimental results proves that the proposed method is correct and effective.

ZnO 1-D nanostructures: Low temperature synthesis and ...

Indian Academy of Sciences (India)

Wintec

high-resolution transmission electron microscope (HRTEM;. JEOL 2010). ... low magnification image of the ZnO nanorod arrays show- ing uniformity of the .... in inverted nail like shape. .... where E (local) is the local electric field at the emitting.

A complementary organic inverter of porphyrazine thin films: low-voltage operation using ionic liquid gate dielectrics.

Science.gov (United States)

Fujimoto, Takuya; Miyoshi, Yasuhito; Matsushita, Michio M; Awaga, Kunio

2011-05-28

We studied a complementary organic inverter consisting of a p-type semiconductor, metal-free phthalocyanine (H(2)Pc), and an n-type semiconductor, tetrakis(thiadiazole)porphyrazine (H(2)TTDPz), operated through the ionic-liquid gate dielectrics of N,N-diethyl-N-methyl(2-methoxyethyl)ammonium bis(trifluoromethylsulfonyl)imide (DEME-TFSI). This organic inverter exhibits high performance with a very low operation voltage below 1.0 V and a dynamic response up to 20 Hz. © The Royal Society of Chemistry 2011

Finishing report for the 'SolcelleInverter' project

Energy Technology Data Exchange (ETDEWEB)

Boekhoej Kjaer, S.

2005-03-01

The main objective for this research project was to develop an inverter for the AC module, where one PV module is equipped with its own dedicated inverter, and connected to the grid. A topology, among many different candidates, has been selected, based on analysis's. The inverter has been optimized in respect to cost, reliability, and efficiency, and a prototype has been build. (au)

Efficient/reliable dc-to-dc inverter circuit

Science.gov (United States)

Pasciutti, E. R.

1970-01-01

Feedback loop, which contains an inductor in series with a saturable reactor, is added to a standard inverter circuit to permit the inverter power transistors to be switched in a controlled and efficient manner. This inverter is applicable where the power source has either high or low impedance properties.

A variable-temperature nanostencil compatible with a low-temperature scanning tunneling microscope/atomic force microscope

International Nuclear Information System (INIS)

Steurer, Wolfram; Gross, Leo; Schlittler, Reto R.; Meyer, Gerhard

2014-01-01

We describe a nanostencil lithography tool capable of operating at variable temperatures down to 30 K. The setup is compatible with a combined low-temperature scanning tunneling microscope/atomic force microscope located within the same ultra-high-vacuum apparatus. The lateral movement capability of the mask allows the patterning of complex structures. To demonstrate operational functionality of the tool and estimate temperature drift and blurring, we fabricated LiF and NaCl nanostructures on Cu(111) at 77 K

A variable-temperature nanostencil compatible with a low-temperature scanning tunneling microscope/atomic force microscope

Energy Technology Data Exchange (ETDEWEB)

Steurer, Wolfram, E-mail: wst@zurich.ibm.com; Gross, Leo; Schlittler, Reto R.; Meyer, Gerhard [IBM Research-Zurich, 8803 Rüschlikon (Switzerland)

2014-02-15

We describe a nanostencil lithography tool capable of operating at variable temperatures down to 30 K. The setup is compatible with a combined low-temperature scanning tunneling microscope/atomic force microscope located within the same ultra-high-vacuum apparatus. The lateral movement capability of the mask allows the patterning of complex structures. To demonstrate operational functionality of the tool and estimate temperature drift and blurring, we fabricated LiF and NaCl nanostructures on Cu(111) at 77 K.

A variable-temperature nanostencil compatible with a low-temperature scanning tunneling microscope/atomic force microscope.

Science.gov (United States)

Steurer, Wolfram; Gross, Leo; Schlittler, Reto R; Meyer, Gerhard

2014-02-01

We describe a nanostencil lithography tool capable of operating at variable temperatures down to 30 K. The setup is compatible with a combined low-temperature scanning tunneling microscope/atomic force microscope located within the same ultra-high-vacuum apparatus. The lateral movement capability of the mask allows the patterning of complex structures. To demonstrate operational functionality of the tool and estimate temperature drift and blurring, we fabricated LiF and NaCl nanostructures on Cu(111) at 77 K.

Transformerless PV inverters. Final report

Energy Technology Data Exchange (ETDEWEB)

Borup, U.

2009-12-15

Since the start of the project the market for grid connected PV inverters have developed further. When the project started three - phase inverter were only available in high power systems. The technology developed within this project will enable three phase technology also to be implemented in string inverters for system down to 10 kW. We expect this to be very attractive due to the increased demand for symmetrical feed-in to the grid. The project relevance is therefore high and the sector continues to develop very much driven by technology. Especially the inverter technology is getting a lot of focus. The inverter systems are expected to take a much larger role in supporting the electrical grid in the future. The technology platform developed within the project is prepared to be extended with these utility functionalities. The main results of the project were: 1) A new technology concept for transformer-less inverters has been demonstrated with a number of prototypes. 2) Efficiency above 97,7% has been proven. 3) Efficiency and Maximum power point tracking has been optimized to ensure that almost all energy produced of the panels is transferred to the grid. 4) The platform is developed with a very fast control board, which enables extended functionality as demanding grid supporting functions in the future. Details about cost price and details about the control loop implementation is excluded from the report due to the competitive situation for Danfoss Solar Inverters A/S. (LN)

Optimized Pulse Width Modulation for transformerless active-NPC inverters

DEFF Research Database (Denmark)

Achilladelis, Nikolaos; Koutroulis, Eftichios; Blaabjerg, Frede

2014-01-01

The transformerless DC/AC inverter topologies are employed in Photovoltaic systems in order to improve the power conversion efficiency, power density and cost. The Active-Neutral Point Clamped (Active-NPC) transformerless inverters have the advantage of achieving better thermal balance among thei...

A Single-Phase Transformerless Inverter With Charge Pump Circuit Concept for Grid-Tied PV Applications

DEFF Research Database (Denmark)

Ardashir, Jaber Fallah; Sabahi, Mehran; Hosseini, Seyed Hossein

2017-01-01

This paper proposes a new single-phase transformerless photovoltaic (PV) inverter for grid-tied PV systems. The topology is derived from the concept of a charge pump circuit in order to eliminate the leakage current. It is composed of four power switches, two diodes, two capacitors, and an LCL...... resonant control strategy is used to control the injected current. The main benefits of the proposed inverter are: the neutral of the grid is directly connected to the negative terminal of the PV panel, so the leakage current is eliminated; its compact size; low cost; the used dc voltage of the proposed...... are presented. Experimental results are presented to confirm both the theoretical analysis and the concept of the proposed inverter. The obtained results clearly validate the performance of the proposed inverter and its practical application in grid-tied PV systems....

Reliability consideration of low-power-grid-tied inverter for photovoltaic application

OpenAIRE

Liu, J.; Henze, N.

2009-01-01

In recent years PV modules have been improved evidently. An excellent reliability has been validated corresponding to Mean Time between Failure (MTBF) between 500 and 6000 years respectively in commercial utility power systems. Manufactures can provide performance guarantees for PV modules at least for 20 years. If an average inverter lifetime of 5 years is assumed, it is evident that the overall reliability of PV systems [PVSs] with integrated inverter is determined chiefly by the inverter i...

Harmonic Analysis and Mitigation of Low- Frequency Switching Voltage Source Inverter with Auxiliary VSI

DEFF Research Database (Denmark)

Bai, Haofeng; Wang, Xiongfei; Blaabjerg, Frede

2018-01-01

The output currents of high-power Voltage Source Inverters (VSIs) are distorted by the switching harmonics and the background harmonics in the grid voltage. This paper presents an active harmonic filtering scheme for high-power, low-frequency switching VSIs with an additional auxiliary VSI. In th...

On the Impacts of PV Array Sizing on the Inverter Reliability and Lifetime

OpenAIRE

Sangwongwanich, Ariya; Yang, Yongheng; Sera, Dezso; Blaabjerg, Frede; Zhou, Dao

2018-01-01

To enable a more wide scale utilization of PV systems, the cost of PV energy should be comparable to or even lower than other energy sources. Due to the relatively low cost of PV modules, oversizing PV arrays becomes a common approach to reduce the cost of PV energy in practice. By doing so, the total energy yield can be increased under weak solar irradiance conditions. However, oversizing the PV array will increase the loading of PV inverters, which may have undesired influence on the PV inv...

Three-Level Z-Source Inverters Using a Single LC Impedance Network

DEFF Research Database (Denmark)

Loh, Poh Chiang; Lim, Sok Wei; Gao, Feng

2007-01-01

two LC impedance networks and two isolated dc sources, which can significantly increase the overall system cost and require a more complex modulator for balancing the network inductive voltage boosting. Offering a number of less costly alternatives, this letter presents the design and control of two...... three-level Z-source inverters, whose output voltage can be stepped down or up using only a single LC impedance network connected between the dc input source and either a neutral-point-clamped (NPC) or dc-link cascaded inverter circuitry. Through careful design of their modulation scheme, both inverters...

Integration of a high-NA light microscope in a scanning electron microscope.

Science.gov (United States)

Zonnevylle, A C; Van Tol, R F C; Liv, N; Narvaez, A C; Effting, A P J; Kruit, P; Hoogenboom, J P

2013-10-01

We present an integrated light-electron microscope in which an inverted high-NA objective lens is positioned inside a scanning electron microscope (SEM). The SEM objective lens and the light objective lens have a common axis and focal plane, allowing high-resolution optical microscopy and scanning electron microscopy on the same area of a sample simultaneously. Components for light illumination and detection can be mounted outside the vacuum, enabling flexibility in the construction of the light microscope. The light objective lens can be positioned underneath the SEM objective lens during operation for sub-10 μm alignment of the fields of view of the light and electron microscopes. We demonstrate in situ epifluorescence microscopy in the SEM with a numerical aperture of 1.4 using vacuum-compatible immersion oil. For a 40-nm-diameter fluorescent polymer nanoparticle, an intensity profile with a FWHM of 380 nm is measured whereas the SEM performance is uncompromised. The integrated instrument may offer new possibilities for correlative light and electron microscopy in the life sciences as well as in physics and chemistry. © 2013 The Authors Journal of Microscopy © 2013 Royal Microscopical Society.

Transparent and Flexible Zinc Tin Oxide Thin Film Transistors and Inverters using Low-pressure Oxygen Annealing Process

Science.gov (United States)

Lee, Kimoon; Kim, Yong-Hoon; Kim, Jiwan; Oh, Min Suk

2018-05-01

We report on the transparent and flexible enhancement-load inverters which consist of zinc tin oxide (ZTO) thin film transistors (TFTs) fabricated at low process temperature. To control the electrical characteristics of oxide TFTs by oxygen vacancies, we applied low-pressure oxygen rapid thermal annealing (RTA) process to our devices. When we annealed the ZTO TFTs in oxygen ambient of 2 Torr, they showed better electrical characteristics than those of the devices annealed in the air ambient of 760 Torr. To realize oxide thin film transistor and simple inverter circuits on flexible substrate, we annealed the devices in O2 of 2 Torr at 150° C and could achieve the decent electrical properties. When we used transparent conductive oxide electrodes such as indium zinc oxide (IZO) and indium tin oxide (ITO), our transparent and flexible inverter showed the total transmittance of 68% in the visible range and the voltage gain of 5. And the transition voltage in voltage transfer curve was located well within the range of operation voltage.

Development of a fluorescent microscope combined with a real-time autoradiography system

International Nuclear Information System (INIS)

Rai, Hiroki; Kanno, Satomi; Hayashi, Yoshitake; Nihei, Naoto; Nakanishi, Tomoko M.

2008-01-01

For combination with microscope, we developed real-time autoradiography system for micro-scale analysis with adjustment of the CsI(Ti) scintillator thickness for higher resolution and applying tapered fiber optic plate for magnification of autoradiograph image. We combined real-time autoradiography system with an inverted fluorescent microscope so that an autoradiograph image as well as fluorescent image, bright-field image can be acquired at the same time. In the case of observation of sliced soybean stalk traced 45 CaCl, the fluorescent and bright-field image was acquired which magnified to 50 times, the autoradiograph image of 45 Ca distribution in the tissue was acquired in almost same scale. The new microscopic system which can acquire autoradiograph image of labeled signals (low molecular weight) is expected to develop the signal transduction study and gene expression, combined with fluorescent protein techniques such as GFP etc. (author)

An Optimized Reactive Power Control of Distributed Solar Inverters in Low Voltage Networks

DEFF Research Database (Denmark)

Demirok, Erhan; Sera, Dezso; Teodorescu, Remus

2011-01-01

This study examines the reactive power ancillary services of solar inverters which are connected to low voltage (LV) distribution networks by giving attention to the grid voltage support service and grid losses. Two typical reference LV distribution network models as suburban and farm...... are introduced from the literature in order to evaluate contribution of two static droop strategies cosφ(P) and Q(U) on the grid voltage. Photovoltaic (PV) hosting capacities of the suburban and farm networks are estimated and the most predominant limitations of connecting more solar inverters are emphasized...... for each network type. Regarding the overloading of MV/LV distribution transformers, overloading of lines and the grid overvoltage limitations, new local grid voltage support methods (cosφ(P,U) and Q(U,P)) are also proposed. Resulting maximum allowable penetration levels with different reactive power...

Development of an ultrasound microscope combined with optical microscope for multiparametric characterization of a single cell.

Science.gov (United States)

Arakawa, Mototaka; Shikama, Joe; Yoshida, Koki; Nagaoka, Ryo; Kobayashi, Kazuto; Saijo, Yoshifumi

2015-09-01

Biomechanics of the cell has been gathering much attention because it affects the pathological status in atherosclerosis and cancer. In the present study, an ultrasound microscope system combined with optical microscope for characterization of a single cell with multiple ultrasound parameters was developed. The central frequency of the transducer was 375 MHz and the scan area was 80 × 80 μm with up to 200 × 200 sampling points. An inverted optical microscope was incorporated in the design of the system, allowing for simultaneous optical observations of cultured cells. Two-dimensional mapping of multiple ultrasound parameters, such as sound speed, attenuation, and acoustic impedance, as well as the thickness, density, and bulk modulus of specimen/cell under investigation, etc., was realized by the system. Sound speed and thickness of a 3T3-L1 fibroblast cell were successfully obtained by the system. The ultrasound microscope system combined with optical microscope further enhances our understanding of cellular biomechanics.

Inverter Circuits Using ZnO Nanoparticle Based Thin-Film Transistors for Flexible Electronic Applications.

Science.gov (United States)

Vidor, Fábio F; Meyers, Thorsten; Hilleringmann, Ulrich

2016-08-23

Innovative systems exploring the flexibility and the transparency of modern semiconducting materials are being widely researched by the scientific community and by several companies. For a low-cost production and large surface area applications, thin-film transistors (TFTs) are the key elements driving the system currents. In order to maintain a cost efficient integration process, solution based materials are used as they show an outstanding tradeoff between cost and system complexity. In this paper, we discuss the integration process of ZnO nanoparticle TFTs using a high- k resin as gate dielectric. The performance in dependence on the transistor structure has been investigated, and inverted staggered setups depict an improved performance over the coplanar device increasing both the field-effect mobility and the I ON / I OFF ratio. Aiming at the evaluation of the TFT characteristics for digital circuit applications, inverter circuits using a load TFT in the pull-up network and an active TFT in the pull-down network were integrated. The inverters show reasonable switching characteristics and V / V gains. Conjointly, the influence of the geometry ratio and the supply voltage on the devices have been analyzed. Moreover, as all integration steps are suitable to polymeric templates, the fabrication process is fully compatible to flexible substrates.

Inverter Circuits Using ZnO Nanoparticle Based Thin-Film Transistors for Flexible Electronic Applications

Directory of Open Access Journals (Sweden)

Fábio F. Vidor

2016-08-01

Full Text Available Innovative systems exploring the flexibility and the transparency of modern semiconducting materials are being widely researched by the scientific community and by several companies. For a low-cost production and large surface area applications, thin-film transistors (TFTs are the key elements driving the system currents. In order to maintain a cost efficient integration process, solution based materials are used as they show an outstanding tradeoff between cost and system complexity. In this paper, we discuss the integration process of ZnO nanoparticle TFTs using a high-k resin as gate dielectric. The performance in dependence on the transistor structure has been investigated, and inverted staggered setups depict an improved performance over the coplanar device increasing both the field-effect mobility and the ION/IOFF ratio. Aiming at the evaluation of the TFT characteristics for digital circuit applications, inverter circuits using a load TFT in the pull-up network and an active TFT in the pull-down network were integrated. The inverters show reasonable switching characteristics and V/V gains. Conjointly, the influence of the geometry ratio and the supply voltage on the devices have been analyzed. Moreover, as all integration steps are suitable to polymeric templates, the fabrication process is fully compatible to flexible substrates.

Multilevel Inverter by Cascading Industrial VSI

DEFF Research Database (Denmark)

Teodorescu, Remus; Blaabjerg, Frede; Pedersen, John Kim

2002-01-01

In this paper the modularity concept applied to medium-voltage adjustable speed drives is addressed. First, the single-phase cascaded voltage-source inverter that uses series connection of IGBT H-bridge modules with isolated dc-buses is presented. Next, a novel three-phase cascaded voltage......-source inverter that uses three IGBT triphase inverter modules along with an output transformer to obtain a 3 p.u. multilevel output voltage is introduced. The system yields in high-quality multistep voltage with up to 4 levels and low dv/dt, balanced operation of the inverter modules, each supplying a third...... of the motor rated kVA. The concept of using cascaded inverters is further extended to a new modular motor-modular inverter system where the motor winding connections are reconnected into several three-phase groups, either six-lead or 12-lead connection according to the voltage level, each powered...

An All-Solution-Based Hybrid CMOS-Like Quantum Dot/Carbon Nanotube Inverter.

Science.gov (United States)

Shulga, Artem G; Derenskyi, Vladimir; Salazar-Rios, Jorge Mario; Dirin, Dmitry N; Fritsch, Martin; Kovalenko, Maksym V; Scherf, Ullrich; Loi, Maria A

2017-09-01

The development of low-cost, flexible electronic devices is subordinated to the advancement in solution-based and low-temperature-processable semiconducting materials, such as colloidal quantum dots (QDs) and single-walled carbon nanotubes (SWCNTs). Here, excellent compatibility of QDs and SWCNTs as a complementary pair of semiconducting materials for fabrication of high-performance complementary metal-oxide-semiconductor (CMOS)-like inverters is demonstrated. The n-type field effect transistors (FETs) based on I - capped PbS QDs (V th = 0.2 V, on/off = 10 5 , S S-th = 114 mV dec -1 , µ e = 0.22 cm 2 V -1 s -1 ) and the p-type FETs with tailored parameters based on low-density random network of SWCNTs (V th = -0.2 V, on/off > 10 5 , S S-th = 63 mV dec -1 , µ h = 0.04 cm 2 V -1 s -1 ) are integrated on the same substrate in order to obtain high-performance hybrid inverters. The inverters operate in the sub-1 V range (0.9 V) and have high gain (76 V/V), large maximum-equal-criteria noise margins (80%), and peak power consumption of 3 nW, in combination with low hysteresis (10 mV). © 2017 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Tuning Range Optimization of a Planar Inverted F Antenna for LTE Low Frequency Bands

DEFF Research Database (Denmark)

Barrio, Samantha Caporal Del; Pelosi, Mauro; Franek, Ondrej

2011-01-01

This paper presents a Planar Inverted F Antenna (PIFA) tuned with a fixed capacitor to the low frequency bands supported by the Long Term Evolution (LTE) technology. The tuning range is investigated and optimized with respect to the bandwidth and the efficiency of the resulting antenna. Simulatio...... and mock-ups are presented....

Free and open-source automated 3-D microscope.

Science.gov (United States)

Wijnen, Bas; Petersen, Emily E; Hunt, Emily J; Pearce, Joshua M

2016-11-01

Open-source technology not only has facilitated the expansion of the greater research community, but by lowering costs it has encouraged innovation and customizable design. The field of automated microscopy has continued to be a challenge in accessibility due the expense and inflexible, noninterchangeable stages. This paper presents a low-cost, open-source microscope 3-D stage. A RepRap 3-D printer was converted to an optical microscope equipped with a customized, 3-D printed holder for a USB microscope. Precision measurements were determined to have an average error of 10 μm at the maximum speed and 27 μm at the minimum recorded speed. Accuracy tests yielded an error of 0.15%. The machine is a true 3-D stage and thus able to operate with USB microscopes or conventional desktop microscopes. It is larger than all commercial alternatives, and is thus capable of high-depth images over unprecedented areas and complex geometries. The repeatability is below 2-D microscope stages, but testing shows that it is adequate for the majority of scientific applications. The open-source microscope stage costs less than 3-9% of the closest proprietary commercial stages. This extreme affordability vastly improves accessibility for 3-D microscopy throughout the world. © 2016 The Authors Journal of Microscopy © 2016 Royal Microscopical Society.

Two-motor single-inverter field-oriented induction machine drive ...

Indian Academy of Sciences (India)

Multi-machine, single-inverter induction motor drives are attractive in situations in which all machines are of similar ratings, and operate at approximately the same load torques. The advantages include small size compared to multi-inverter system, lower weight and overall cost. However, field oriented control of such drives ...

Development of confocal laser microscope system for examination of microscopic characteristics of radiophotoluminescence glass dosemeters

International Nuclear Information System (INIS)

Maki, D.; Ishii, T.; Sato, F.; Kato, Y.; Yamamoto, T.; Iida, T.

2011-01-01

A confocal laser microscope system was developed for the measurement of radiophotoluminescence (RPL) photons emitted from a minute alpha-ray-irradiated area in an RPL glass dosemeter. The system was composed mainly of an inverted-type microscope, an ultraviolet laser, an XY movable stage and photon-counting circuits. The photon-counting circuits were effective in the reduction of the background noise level in the measurement of RPL photons. The performance of this microscope system was examined by the observation of standard RPL glass samples irradiated using 241 Am alpha rays. The spatial resolution of this system was ∼3 μm, and with regard to the sensitivity of this system, a hit of more than four to five alpha rays in unit area produced enough amount of RPL photons to construct the image. (authors)

Development of confocal laser microscope system for examination of microscopic characteristics of radiophotoluminescence glass dosemeters.

Science.gov (United States)

Maki, Daisuke; Ishii, Tetsuya; Sato, Fuminobu; Kato, Yushi; Yamamoto, Takayoshi; Iida, Toshiyuki

2011-03-01

A confocal laser microscope system was developed for the measurement of radiophotoluminescence (RPL) photons emitted from a minute alpha-ray-irradiated area in an RPL glass dosemeter. The system was composed mainly of an inverted-type microscope, an ultraviolet laser, an XY movable stage and photon-counting circuits. The photon-counting circuits were effective in the reduction of the background noise level in the measurement of RPL photons. The performance of this microscope system was examined by the observation of standard RPL glass samples irradiated using (241)Am alpha rays. The spatial resolution of this system was ∼ 3 μm, and with regard to the sensitivity of this system, a hit of more than four to five alpha rays in unit area produced enough amount of RPL photons to construct the image.

High efficiency H6 single-phase transformerless grid-tied PV inverter with proposed modulation for reactive power generation

Science.gov (United States)

Almasoudi, Fahad M.; Alatawi, Khaled S.; Matin, Mohammad

2017-08-01

Implementation of transformerless inverters in PV grid-tied system offer great benefits such as high efficiency, light weight, low cost, etc. Most of the proposed transformerless inverters in literature are verified for only real power application. Currently, international standards such as VDE-AR-N 4105 has demanded that PV grid-tied inverters should have the ability of controlling a specific amount of reactive power. Generation of reactive power cannot be accomplished in single phase transformerless inverter topologies because the existing modulation techniques are not adopted for a freewheeling path in the negative power region. This paper enhances a previous high efficiency proposed H6 trnasformerless inverter with SiC MOSFETs and demonstrates new operating modes for the generation of reactive power. A proposed pulse width modulation (PWM) technique is applied to achieve bidirectional current flow through freewheeling state. A comparison of the proposed H6 transformerless inverter using SiC MOSFETs and Si MOSFTEs is presented in terms of power losses and efficiency. The results show that reactive power control is attained without adding any additional active devices or modification to the inverter structure. Also, the proposed modulation maintains a constant common mode voltage (CM) during every operating mode and has low leakage current. The performance of the proposed system verifies its effectiveness in the next generation PV system.

PLTS Transformerless Tegangan 20 kV menggunakan Cascaded H-Bridge Multilevel Inverter

Directory of Open Access Journals (Sweden)

ANGGARA BRAJAMUSTHI

2018-03-01

Full Text Available ABSTRAK Aplikasi dari inverter multilevel pada sistem Pusat Listrik Tenaga Surya (PLTS dapat menghilangkan kebutuhan terhadap transformator, sehingga dapat mengurangi biaya investasi, mengurangi kompleksitas instalasi dan menghilangkan rugi-rugi daya transformator. Pada penelitian ini, sebuah inverter dengan topologi Cascaded H-Bridge Multilevel Inverter dirancang agar mampu mengubah tegangan rendah DC dari beberapa Photovoltaic (PV array menjadi tegangan fasa-fasa 20 kV AC. Perancangan menghasilkan sebuah inverter 3 fasa 27-level dimana setiap level masing-masing memiliki PV array, DC-DC boost converter, H-bridge inverter, dan keluaran 3 fasa terhubung dengan filter LCL. Setiap komponen dari inverter dan sistem tersebut kemudian dimodelkan pada MATLAB Simulink untuk mensimulasikan kinerja dari setiap komponen dan sistem pada Standard Test Condition (STC dari modul PV. Pada keadaan STC, daya 3 fasa maksimum yang dapat dihasilkan adalah 1,716 MW atau 68,54% dari daya DC maksimum sebesar 2,5 MWp. Sistem dapat menghasilkan tegangan fasa-fasa keluaran sebesar 20 kV dengan Total Harmonic Distortion (THD di bawah 5%. Kata kunci: Pusat Listrik Tenaga Surya (PLTS, photovoltaic, Cascaded H-Bridge Multilevel Inverter ABSTRACT The application of Multilevel Inverter in a Photovoltaic Solar Power Plant system could eliminate the needs of step-up transformer, which will reduce the system investment cost, simplify the system installation and also eliminate power losses of the transformer. In this paper, an inverter design was proposed with Cascaded H-Bridge Multilevel Inverter topology that is capable of converting low voltage DC power from several PV arrays into 20 kV AC power. The design resulted a 3 phase 27-level inverter where each level in the inverter has its own photovoltaic array, DC-DC boost converter, H-bridge inverter, and the 3 phase output is connected to LCL filter. Each component of the Inverter and the system were then modelled in MATLAB

Stability of low aspect ratio inverted flags and rods in a uniform flow

Science.gov (United States)

Huertas-Cerdeira, Cecilia; Sader, John E.; Gharib, Morteza

2016-11-01

Cantilevered elastic plates and rods in an inverted configuration, where the leading edge is free to move and the trailing edge is clamped, undergo complex dynamics when subjected to a uniform flow. The stability of low aspect ratio inverted plates and rods is theoretically examined, showing that it is markedly different from that of their large aspect ratio counterpart. In the limit of zero aspect ratio, the undeflected equilibrium position is found to be stable for all wind speeds. A saddle-node bifurcation emerges at finite wind speed, giving rise to a strongly deflected stable and a weakly deflected unstable equilibria. This theory is compared to experimental measurements, where good agreement is found. This research was supported by a Grant of the Gordon and Betty Moore Foundation, the Australian Research Council Grants scheme and a "la Caixa" Fellowship Grant for Post-Graduate Studies of "la Caixa" Banking Foundation.

Fully low voltage and large area searching scanning tunneling microscope

International Nuclear Information System (INIS)

Pang, Zongqiang; Wang, Jihui; Lu, Qingyou

2009-01-01

We present a novel scanning tunneling microscope (STM), which allows the tip to travel a large distance (millimeters) on the sample and take images (to find microscopic targets) anywhere it reaches without losing atomic resolution. This broad range searching capability, together with the coarse approach and scan motion, is all done with only one single piezoelectric tube scanner as well as with only low voltages (<15 V). Simple structure, low interference and high precision are thus achieved. To this end, a pillar and a tube scanner are mounted in parallel on a base with one ball glued on the pillar top and two balls glued on the scanner top. These three balls form a narrow triangle, which supports a triangular slider piece. By inertial stepping, the scanner can move the slider toward the pillar (coarse approach) or rotate the slider about the pillar (travel along sample surface). Since all the stepping motions are driven by the scanner's lateral bending which is large per unit voltage, high voltages are unnecessary. The technology is also applicable to scanning force microscopes (SFM) such as atomic force microscopes (AFM), etc

Impacts of PV Array Sizing on PV Inverter Lifetime and Reliability

DEFF Research Database (Denmark)

Sangwongwanich, Ariya; Yang, Yongheng; Sera, Dezso

2017-01-01

. However, oversizing the PV array will increase the loading of PV inverters, which may have undesired influence on the PV inverter lifetime and reliability. In that case, it may result in a negative impact on the overall PV energy cost, due to the increased maintenance for the PV inverters. This paper...... evaluates the lifetime of PV inverters considering the PV array sizing and installation sites, e.g., Denmark and Arizona. The results reveal that the PV array sizing has a considerable impact on the PV inverter lifetime and reliability, especially in Denmark, where the average solar irradiance level...

Laser-based microstructuring of materials surfaces using low-cost microlens arrays

Science.gov (United States)

Nieto, Daniel; Vara, G.; Diez, J. A.; O`Connor, Gerard M.; Arines, Justo; Gómez-Reino, C.; Flores-Arias, M.

2012-03-01

Since frictional interactions in microscopically small components are becoming increasingly important for the development of new products for all modern technology, we present a laser-based technique for micro-patterning surfaces of materials using low-cost microlens arrays. The microlens used were fabricated on soda-lime glass using a laser direct-write technique, followed by a thermal treatment into an oven. By combining laser direct-write and the thermal treatment it was possible to obtain high quality elements using a low cost infrared laser widely implemented in industry which makes this technique attractive in comparison with other more expensive methods. The main advantage of using microlens arrays for micropatterning surfaces is the possibility of fabricating a large number of identical structures simultaneously, leading to a highly efficient process. In order to study the capabilities of the microlens fabricated for microstructuring materials, identical structures and arrays of holes were fabricated over a variety of materials, such us, stainless steel, polymer and ceramic. The minimum diameter of the individual microstructure generated at surface is 5 μm. Different nanosecond lasers operating at Infrared, Green and UV were used. The topography and morphology of the elements obtained were determined using a confocal microscope SENSOFAR 2300 Plμ.

Evidence that human papillomavirus causes inverted papilloma is sparse.

Science.gov (United States)

Justice, Jeb M; Davis, Kern M; Saenz, Daniel A; Lanza, Donald C

2014-12-01

Controversy exists regarding the pathogenesis of inverted papilloma as it relates to the involvement of human papillomavirus (HPV). The purpose of this report is to describe the prevalence of HPV in nondysplastic, "early inverted papilloma" and to summarize HPV detection rates in the general population and in other HPV related neoplasia. This case series report characterizes consecutive inverted papilloma patients from January 2005 to August 2012 with regard to smoking history, dysplasia, and HPV detection rates. Presence or absence of low/high risk HPV was determined by standardized in situ hybridization DNA probes. Medline literature review was performed to determine the prevalence of HPV in inverted papilloma without moderate or severe dysplasia. Thirty-six consecutive patients were identified with an average age of 63.6 (range, 40-84) years; gender: 23 men, 13 women. More than half (55%) were active or former smokers (14% active and 41% former). High/low risk HPV was present in 1 in 36 (2.7%) patients and 1 in 36 (2.7%) had mild dysplasia. In the literature review: (1) HPV was detected in 16.4% of inverted papilloma without dysplasia; (2) oral cavity HPV detection was 4.2% to 11.4% in the normal population; and (3) HPV was normally detected in 85% to 95% of HPV-related neoplasia. Given histological features of inverted papilloma and comparatively low detection rates of HPV in inverted papilloma without dysplasia (2.7%), as well as the summary of the world literature, HPV is not related to the initial pathogenesis of inverted papilloma or inverted papilloma's tendency to persist or recur. It is postulated that since inverted papilloma is more an inflammatory polyp, it is susceptible to secondary HPV infection because of its metaplasia. Tobacco and other causes of respiratory epithelium remodeling are more plausible explanations for the initial tissue transformation to inverted papilloma. © 2014 ARS-AAOA, LLC.

Design Optimization of Transformerless Grid-Connected PV Inverters Including Reliability

OpenAIRE

Koutroulis, Eftichios; Blaabjerg, Frede

2013-01-01

This paper presents a new methodology for optimal design of transformerless photovoltaic (PV) inverters targeting a cost-effective deployment of grid-connected PV systems. The optimal switching frequency as well as the optimal values and types of the PV inverter components is calculated such that the PV inverter LCOE generated during the PV system lifetime period is minimized. The LCOE is also calculated considering the failure rates of the components, which affect the reliability performance...

Dual-mode optical microscope based on single-pixel imaging

OpenAIRE

Rodríguez Jiménez, Angel David; Clemente Pesudo, Pedro Javier; Tajahuerce, Enrique; Lancis Sáez, Jesús

2016-01-01

We demonstrate an inverted microscope that can image specimens in both reflection and transmission modes simultaneously with a single light source. The microscope utilizes a digital micromirror device (DMD) for patterned illumination altogether with two single-pixel photosensors for efficient light detection. The system, a scan-less device with no moving parts, works by sequential projection of a set of binary intensity patterns onto the sample that are codified onto a modified commercial DMD...

Design of inverters for the PHOTONERGY project

Energy Technology Data Exchange (ETDEWEB)

NONE

2003-08-01

The PHOTONERGY project (the former SolcelleInverter project) was initiated on the 1st of September 2001, with a state-of-the-art analysis, which concluded into specifications. Based on this 23 topologies were analyzed in for efficiencies. The results from this analysis was five candidates which all showed a somewhat good efficiency. These five topologies were in further investigated by means of an initial design-iteration and simulations. Two different solutions were picked up in due to their high efficiency and low cost. 1. The standard full-bridge phase shifted DC/DC converter together with a standard DC/AC inverter, 2. A modified version of the novel Shimizu topology. A patent is pending on this modified version. These two inverters are in this document developed and made ready for prototyping. This includes design and selection of reactive- and switching-components, e.g. filter- and bulk-capacitors, low- and high-frequency inductors, high frequency transformers, MOSFETs and diodes. The design of auxiliary circuits is also included, e.g. gate drivers for the MOSFETs, measuring circuits for the grid-current and -voltage, PV-module-current and voltage, protection circuits, hardware near controllers and finally a switch mode power supply. However, the design of the various controllers, except the hardware near PV-current controller for the full bridge phase shifted converter, is not documented in this report but will come later on. This includes all controllers, e.g. maximum power point tracking for the PV-module, utility grid current controller, DC-link voltage controller, phase locked loops, and detection of islanding operation. All of these control loops are to be implemented in a micro-controller. (au)

The CMOS Integration of a Power Inverter

OpenAIRE

Mannarino, Eric Francis

2016-01-01

Due to their falling costs, the use of renewable energy systems is expanding around the world. These systems require the conversion of DC power into grid-synchronous AC power. Currently, the inverters that carry out this task are built using discrete transistors. TowerJazz Semiconductor Corp. has created a commercial CMOS process that allows for blocking voltages of up to 700 V, effectively removing the barrier to integrating power inverters onto a single chip. This thesis explores this proce...

Inverted base pavements: construction and performance

KAUST Repository

Papadopoulos, Efthymios; Santamarina, Carlos

2017-01-01

quality control. This study reviews the extensive South African experience and case histories in the USA. Accumulating evidence suggests that inverted base pavements are a viable alternative and can outperform conventional pavements at a lower cost

Modulation of Current Source Inverter

Directory of Open Access Journals (Sweden)

Golam Reza Arab Markadeh

2011-04-01

Full Text Available Direct torque control with Current Source Inverter (CSI instead of voltage source inverter is so appropriate because of determining the torque of induction motor with machine current and air gap flux. In addition, Space-Vector Modulation (SVM is a more proper method for CSI because of low order harmonics reduction, lower switching frequency and easier implementation. This paper introduces the SVM method for CSI and uses the proposed inverter for vector control of an induction motor. The simulation results illustrate fast dynamic response and desirable torque and speed output. Fast and accurate response to changes of speed and load torque reference completely proves the prominence of this method.

Detecting and mitigating inverter aging

International Nuclear Information System (INIS)

Gunther, W.E.; Taylor, J.H.; Aggarwal, S.K.

1988-01-01

Nuclear power plants use inverters to supply power to safety-related equipment, instrumentation, and controls. They convert direct current (dc) to alternating current (ac) power, thereby making low voltage ac power available even under a station blackout condition. As part of the U.S. NRC's nuclear plant aging research (NPAR) program, the operating experience of this equipment has been analyzed to determine the dominant failure modes and causes. This paper summarizes that data, and then describes methods which can be employed to detect inverter degradation prior to failure, as well as methods to minimize the failure effects. In both cases, the mitigation of inverter aging is emphasized

Techniques for the optimal design of photovoltaic inverters interconnected with the electric grid

DEFF Research Database (Denmark)

Koutroulis, Eftichios; Blaabjerg, Frede

2011-01-01

the Genetic Algorithm-based optimization procedure is the PV inverter Levelized Cost Of the Electricity generated (LCOE). The proposed method has been applied for the optimal design of PV inverters installed at various sites in Europe. The simulation results indicate that the optimal values of the PV inverter...

Low cost label-free live cell imaging for biological samples

Science.gov (United States)

Seniya, C.; Towers, C. E.; Towers, D. P.

2017-02-01

This paper reports the progress to develop a practical phase measuring microscope offering new capabilities in terms of phase measurement accuracy and quantification of cell:cell interactions over the longer term. A novel, low cost phase interference microscope for imaging live cells (label-free) is described. The method combines the Zernike phase contrast approach with a dual mirror design to enable phase modulation between the scattered and un-scattered optical fields. Two designs are proposed and demonstrated, one of which retains the common path nature of Zernike's original microscopy concept. In both setups the phase shift is simple to control via a piezoelectric driven mirror in the back focal plane of the imaging system. The approach is significantly cheaper to implement than those based on spatial light modulators (SLM) at approximately 20% of the cost. A quantitative assessment of the performance of a set of phase shifting algorithms is also presented, specifically with regard to broad bandwidth illumination in phase contrast microscopy. The simulation results show that the phase measurement accuracy is strongly dependent on the algorithm selected and the optical path difference in the sample.

Direct model-based predictive control scheme without cost function for voltage source inverters with reduced common-mode voltage

Science.gov (United States)

Kim, Jae-Chang; Moon, Sung-Ki; Kwak, Sangshin

2018-04-01

This paper presents a direct model-based predictive control scheme for voltage source inverters (VSIs) with reduced common-mode voltages (CMVs). The developed method directly finds optimal vectors without using repetitive calculation of a cost function. To adjust output currents with the CMVs in the range of -Vdc/6 to +Vdc/6, the developed method uses voltage vectors, as finite control resources, excluding zero voltage vectors which produce the CMVs in the VSI within ±Vdc/2. In a model-based predictive control (MPC), not using zero voltage vectors increases the output current ripples and the current errors. To alleviate these problems, the developed method uses two non-zero voltage vectors in one sampling step. In addition, the voltage vectors scheduled to be used are directly selected at every sampling step once the developed method calculates the future reference voltage vector, saving the efforts of repeatedly calculating the cost function. And the two non-zero voltage vectors are optimally allocated to make the output current approach the reference current as close as possible. Thus, low CMV, rapid current-following capability and sufficient output current ripple performance are attained by the developed method. The results of a simulation and an experiment verify the effectiveness of the developed method.

Compact, Light-weight and Cost-effective Microscope based on Lensless Incoherent Holography for Telemedicine Applications

Science.gov (United States)

Mudanyali, Onur; Tseng, Derek; Oh, Chulwoo; Isikman, Serhan O.; Sencan, Ikbal; Bishara, Waheb; Oztoprak, Cetin; Seo, Sungkyu; Khademhosseini, Bahar; Ozcan, Aydogan

2010-01-01

Despite the rapid progress in optical imaging, most of the advanced microscopy modalities still require complex and costly set-ups that unfortunately limit their use beyond well equipped laboratories. In the meantime, microscopy in resource-limited settings has requirements significantly different from those encountered in advanced laboratories, and such imaging devices should be cost-effective, compact, light-weight and appropriately accurate and simple to be usable by minimally trained personnel. Furthermore, these portable microscopes should ideally be digitally integrated as part of a telemedicine network that connects various mobile health-care providers to a central laboratory or hospital. Toward this end, here we demonstrate a lensless on-chip microscope weighing ~46 grams with dimensions smaller than 4.2cm × 4.2cm × 5.8cm that achieves sub-cellular resolution over a large field of view of ~24 mm2. This compact and light-weight microscope is based on digital in-line holography and does not need any lenses, bulky optical/mechanical components or coherent sources such as lasers. Instead, it utilizes a simple light-emitting-diode (LED) and a compact opto-electronic sensor-array to record lensless holograms of the objects, which then permits rapid digital reconstruction of regular transmission or differential interference contrast (DIC) images of the objects. Because this lensless incoherent holographic microscope has orders-of-magnitude improved light collection efficiency and is very robust to mechanical misalignments it may offer a cost-effective tool especially for telemedicine applications involving various global health problems in resource limited settings. PMID:20401422

Power inverter design for ASDEX Upgrade saddle coils

Energy Technology Data Exchange (ETDEWEB)

Teschke, M., E-mail: teschke@ipp.mpg.de [Max Planck Institute for Plasma Physics, EURATOM Association, Boltzmannstr. 2, 85748 Garching (Germany); Suttrop, W.; Rott, M. [Max Planck Institute for Plasma Physics, EURATOM Association, Boltzmannstr. 2, 85748 Garching (Germany)

2013-10-15

Highlights: ► A cost effective inverter topology for AUG's 16 in-vessel saddle coils has been found. ► Use of commercially available power modules is possible. ► Exchange of reactive power between multiple inverters is possible. ► Influence of electromagnetic noise to AUG's diagnostics was measured. ► Gas insulation of electric feed through significantly depends on magnetic fields. It is protected by fast turn-off circuit. -- Abstract: A set of 16 in-vessel saddle coils has been installed in the ASDEX Upgrade (AUG) experiment since the end of 2011 [1]. To achieve full performance, it is necessary to operate them with alternating current (AC) of arbitrary waveforms. To generate spatially resolved magnetic fields, it is required to allocate separate power inverters to every single coil. Therefore, different topologies are analyzed and compared. Studies of the commutation behavior of power stages, different pulse width modulation (PWM) schemes and single-phase-to-earth fault detection are executed. Experiments to evaluate the electromagnetic interference (EMI) of possible inverter topologies on the AUG diagnostics are done as well. A special focus is put on the feasibility of analyzed topologies using industrially available and fully assembled “power modules” to minimize development effort and costs.

A Simplified, Low-Cost Method for Polarized Light Microscopy

Science.gov (United States)

Maude, Richard J.; Buapetch, Wanchana; Silamut, Kamolrat

2009-01-01

Malaria pigment is an intracellular inclusion body that appears in blood and tissue specimens on microscopic examination and can help in establishing the diagnosis of malaria. In simple light microscopy, it can be difficult to discern from cellular background and artifacts. It has long been known that if polarized light microscopy is used, malaria pigment can be much easier to distinguish. However, this technique is rarely used because of the need for a relatively costly polarization microscope. We describe a simple and economical technique to convert any standard light microscope suitable for examination of malaria films into a polarization microscope. PMID:19861611

Optimal Design of Modern Transformerless PV Inverter Topologies

OpenAIRE

Saridakis, Stefanos; Koutroulis, Eftichios; Blaabjerg, Frede

2013-01-01

The design optimization of H5, H6, neutral point clamped, active-neutral point clamped, and conergy-NPC transformerless photovoltaic (PV) inverters is presented in this paper. The components reliability in terms of the corresponding malfunctions, affecting the PV inverter maintenance cost during the operational lifetime period of the PV installation, is also considered in the optimization process. According to the results of the proposed design method, different optimal values of the PV inver...

Flyback CCM inverter for AC module applications: iterative learning control and convergence analysis

Science.gov (United States)

Lee, Sung-Ho; Kim, Minsung

2017-12-01

This paper presents an iterative learning controller (ILC) for an interleaved flyback inverter operating in continuous conduction mode (CCM). The flyback CCM inverter features small output ripple current, high efficiency, and low cost, and hence it is well suited for photovoltaic power applications. However, it exhibits the non-minimum phase behaviour, because its transfer function from control duty to output current has the right-half-plane (RHP) zero. Moreover, the flyback CCM inverter suffers from the time-varying grid voltage disturbance. Thus, conventional control scheme results in inaccurate output tracking. To overcome these problems, the ILC is first developed and applied to the flyback inverter operating in CCM. The ILC makes use of both predictive and current learning terms which help the system output to converge to the reference trajectory. We take into account the nonlinear averaged model and use it to construct the proposed controller. It is proven that the system output globally converges to the reference trajectory in the absence of state disturbances, output noises, or initial state errors. Numerical simulations are performed to validate the proposed control scheme, and experiments using 400-W AC module prototype are carried out to demonstrate its practical feasibility.

Inverted Lymphoglandular Polyp in Descending Colon

Directory of Open Access Journals (Sweden)

Shengmei Zhou

2015-01-01

Full Text Available A 47-year-old male with a history of left colon cancer, status post left colon resection for 12 years, presented with rectal bleeding. Colonoscopic examination revealed an 8 mm sessile polyp in the proximal descending colon. Microscopic examination showed that the surface of this polyp was covered with a layer of normal colonic mucosa with focal surface erosion. In the submucosal layer, an intimate admixture of multiple cystically dilated glands and prominent lymphoid aggregates with germinal centers was seen. The glands were lined by columnar epithelium. Immunohistochemical staining showed the glands were positive for CK20 and CDX2 and negative for CK7, with a low proliferative index, mostly consistent with reactive colonic glands. The patient remained asymptomatic after one-year follow-up. A review of the literature shows very rare descriptions of similar lesions, but none fits exactly this pattern. We would designate this inverted lymphoglandular polyp and present this case to raise the awareness of recognizing this unusual histological entity.

Synthesis and characterization of low cost magnetorheological (MR) fluids

Science.gov (United States)

Sukhwani, V. K.; Hirani, H.

2007-04-01

Magnetorheological fluids have great potential for engineering applications due to their variable rheological behavior. These fluids find applications in dampers, brakes, shock absorbers, and engine mounts. However their relatively high cost (approximately US600 per liter) limits their wide usage. Most commonly used magnetic material "Carbonyl iron" cost more than 90% of the MR fluid cost. Therefore for commercial viability of these fluids there is need of alternative economical magnetic material. In the present work synthesis of MR fluid has been attempted with objective to produce low cost MR fluid with high sedimentation stability and greater yield stress. In order to reduce the cost, economical electrolytic Iron powder (US 10 per Kg) has been used. Iron powder of relatively larger size (300 Mesh) has been ball milled to reduce their size to few microns (1 to 10 microns). Three different compositions have been prepared and compared for MR effect produced and stability. All have same base fluid (Synthetic oil) and same magnetic phase i.e. Iron particles but they have different additives. First preparation involves organic additives Polydimethylsiloxane (PDMS) and Stearic acid. Other two preparations involve use of two environmental friendly low-priced green additives guar gum (US 2 per Kg) and xanthan gum (US 12 per Kg) respectively. Magnetic properties of Iron particles have been measured by Vibrating Sample Magnetometer (VSM). Morphology of Iron particles and additives guar gum and xanthan gum has been examined by Scanning Electron Microscopy (SEM) and Particles Size Distribution (PSD) has been determined using Particle size analyzer. Microscopic images of particles, MH plots and stability of synthesized MR fluids have been reported. The prepared low cost MR fluids showed promising performance and can be effectively used for engineering applications demanding controllability in operations.

Electric machine and current source inverter drive system

Science.gov (United States)

Hsu, John S

2014-06-24

A drive system includes an electric machine and a current source inverter (CSI). This integration of an electric machine and an inverter uses the machine's field excitation coil for not only flux generation in the machine but also for the CSI inductor. This integration of the two technologies, namely the U machine motor and the CSI, opens a new chapter for the component function integration instead of the traditional integration by simply placing separate machine and inverter components in the same housing. Elimination of the CSI inductor adds to the CSI volumetric reduction of the capacitors and the elimination of PMs for the motor further improve the drive system cost, weight, and volume.

Power Control Flexibilities for Grid-Connected Multi-Functional Photovoltaic Inverters

DEFF Research Database (Denmark)

Yang, Yongheng; Blaabjerg, Frede; Wang, Huai

2016-01-01

and intelligent services, such as fault ride-through and reactive power compensation, is the key to attain higher utilisation of solar PV energy. Such functionalities for the future PV inverters can contribute to reduced cost of energy, and thus enable more cost-effective PV installations. To implement...... the advanced features, a flexible power controller is developed in this study, which can be configured in the PV inverter and flexibly change from one to another mode during operation. Based on the single-phase PQ theory, the control strategy offers the possibilities to generate appropriate references...... for the inner current control loop. The references depend on system conditions and also specific demands from both system operators and prosumers. Besides, this power control strategy can be implemented in commercial PV inverters as a standardised function, and also the operation modes can be achieved online...

A modular, open-source, slide-scanning microscope for diagnostic applications in resource-constrained settings.

Directory of Open Access Journals (Sweden)

Qiang Lu

Full Text Available In this paper we report the development of a cost-effective, modular, open source, and fully automated slide-scanning microscope, composed entirely of easily available off-the-shelf parts, and capable of bright field and fluorescence modes. The automated X-Y stage is composed of two low-cost micrometer stages coupled to stepper motors operated in open-loop mode. The microscope is composed of a low-cost CMOS sensor and low-cost board lenses placed in a 4f configuration. The system has approximately 1 micron resolution, limited by the f/# of available board lenses. The microscope is compact, measuring just 25×25×30 cm, and has an absolute positioning accuracy of ±1 μm in the X and Y directions. A Z-stage enables autofocusing and imaging over large fields of view even on non-planar samples, and custom software enables automatic determination of sample boundaries and image mosaicking. We demonstrate the utility of our device through imaging of fluorescent- and transmission-dye stained blood and fecal smears containing human and animal parasites, as well as several prepared tissue samples. These results demonstrate image quality comparable to high-end commercial microscopes at a cost of less than US$400 for a bright-field system, with an extra US$100 needed for the fluorescence module.

Single-Phase LLCL-Filter-based Grid-Tied Inverter with Low-Pass Filter Based Capacitor Current Feedback Active damper

DEFF Research Database (Denmark)

Liu, Yuan; Wu, Weimin; Li, Yun

2016-01-01

The capacitor-current-feedback active damping method is attractive for high-order-filter-based high power grid-tied inverter when the grid impedance varies within a wide range. In order to improve the system control bandwidth and attenuate the high order grid background harmonics by using the quasi....... In this paper, a low pass filter is proposed to be inserted in the capacitor current feedback loop op LLCL-filter based grid-tied inverter together with a digital proportional and differential compensator. The detailed theoretical analysis is given. For verification, simulations on a 2kW/220V/10kHz LLCL...

Denture hyperplasia with areas simulating oral inverted ductal papilloma.

Science.gov (United States)

Vargas, Pablo Agustin; Perez, Danyel Elias da Cruz; Jorge, Jacks; Rangel, Ana Lúcia Carrinho Ayrosa; León, Jorge Esquiche; Almeida, Oslei Paes de

2005-07-01

Denture hyperplasia is a reactive lesion of the oral mucosa, usually associated to an ill-fitting denture. This lesion is easily diagnosed and in some cases distinct microscopic variations such as osseous, oncocytic and squamous metaplasia may be found. These metaplastic alterations probably are associated with the lymphocytic infiltrate usually present in denture hyperplasia. We present a case of denture hyperplasia containing salivary gland tissue with ductal alterations mimicking an oral inverted ductal papilloma.

PC-based digital feedback control for scanning force microscope

International Nuclear Information System (INIS)

Mohd Ashhar Khalid

2002-01-01

In the past, most digital feedback implementation for scanned-probe microscope were based on a digital signal processor (DSP). At present DSP plug-in card with the input-output interface module is still expensive compared to a fast pentium PC motherboard. For a magnetic force microscope (MFM) digital feedback has an advantage where the magnetic signal can be easily separated from the topographic signal. In this paper, a simple low-cost PC-based digital feedback and imaging system for Scanning Force Microscope (SFM) is presented. (Author)

Magnetically coupled impedance-source inverters

DEFF Research Database (Denmark)

Loh, Poh Chiang; Blaabjerg, Frede

2012-01-01

input-to-output gain, and the presence of an impedance network. The former means a high dc-link voltage, which can stress the semiconductor switches unnecessarily. The latter leads to increases in cost and size, which similarly are undesirable. To lessen these concerns, an interesting approach is to use...... magnetically coupled transformers or inductors to raise the gain and modulation ratio simultaneously, while reducing the number of passive components needed. A study of the approach is now presented to show how various existing magnetically coupled inverters can be derived by applying a generic methodology....... The same methodology is then applied to develop more magnetically coupled Z-source inverters with advantages that have not been identified in the literature. These findings have already been proven in experiments....

Mitigation of grid-current distortion for LCL-filtered grid-connected voltage-source inverter with inverter-side current control

DEFF Research Database (Denmark)

Xin, Zhen; Mattavelli, Paolo; Yao, WenLi

2017-01-01

Due to the low inductance of an LCL-filter, the grid current generated by an LCL-filtered Voltage Source Inverter (VSI) is sensitive to low-order grid-voltage harmonics. This issue is especially tough for the control system with Inverter Current Feedback (ICF), because the grid-current harmonics...... can freely flow into the filter capacitor without control. To cope with this issue, this paper develops an approach for the ICF control system to suppress the grid-current harmonics without adding extra sensors. The proposed method applies harmonic controllers and feedforward scheme simultaneously...

Novel, Four-Switch, Z-Source Three-Phase Inverter

DEFF Research Database (Denmark)

Antal, Robert; Muntean, Nicolae; Boldea, Ion

2010-01-01

This paper presents a new z-source three phase inverter topology. The proposed topology combines the advantages of a traditional four-switch three-phase inverter with the advantages of the z impedance network (one front-end diode, two inductors and two X connected capacitors). This new topology......, besides the self-boost property, has low switch count and it can operate as a buck-boost inverter. In contrast to standard four-switch three-phase inverter which operates at half dc input voltage the proposed four-switch z-source inverter, by self boosting, brings the output voltage at same (or higher......) value as in six switch standard three-phase inverter. The article presents the derivation of the equations describing the operation of the converter based on space vector analysis, validation through digital simulations in PSIM and preliminary experimental results on a laboratory setup with a dsPIC30F...

All solution-processed micro-structured flexible electrodes for low-cost light-emitting pressure sensors fabrication.

Science.gov (United States)

Shimotsu, Rie; Takumi, Takahiro; Vohra, Varun

2017-07-31

Recent studies have demonstrated the advantage of developing pressure-sensitive devices with light-emitting properties for direct visualization of pressure distribution, potential application to next generation touch panels and human-machine interfaces. To ensure that this technology is available to everyone, its production cost should be kept as low as possible. Here, simple device concepts, namely, pressure sensitive flexible hybrid electrodes and OLED architecture, are used to produce low-cost resistive or light-emitting pressure sensors. Additionally, integrating solution-processed self-assembled micro-structures into the flexible hybrid electrodes composed of an elastomer and conductive materials results in enhanced device performances either in terms of pressure or spatial distribution sensitivity. For instance, based on the pressure applied, the measured values for the resistances of pressure sensors range from a few MΩ down to 500 Ω. On the other hand, unlike their evaporated equivalents, the combination of solution-processed flexible electrodes with an inverted OLED architectures display bright green emission when a pressure over 200 kPa is applied. At a bias of 3 V, their luminance can be tuned by applying a higher pressure of 500 kPa. Consequently, features such as fingernails and fingertips can be clearly distinguished from one another in these long-lasting low-cost devices.

Protonic/electronic hybrid oxide transistor gated by chitosan and its full-swing low voltage inverter applications

Energy Technology Data Exchange (ETDEWEB)

Chao, Jin Yu [Shanxi Province Key Laboratory High Gravity Chemical Engineering, North University of China, Taiyuan 030051 (China); Ningbo Institute of Material Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Zhu, Li Qiang, E-mail: lqzhu@nimte.ac.cn; Xiao, Hui [Ningbo Institute of Material Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Yuan, Zhi Guo, E-mail: ncityzg@163.com [Shanxi Province Key Laboratory High Gravity Chemical Engineering, North University of China, Taiyuan 030051 (China)

2015-12-21

Modulation of charge carrier density in condensed materials based on ionic/electronic interaction has attracted much attention. Here, protonic/electronic hybrid indium-zinc-oxide (IZO) transistors gated by chitosan based electrolyte were obtained. The chitosan-based electrolyte illustrates a high proton conductivity and an extremely strong proton gating behavior. The transistor illustrates good electrical performances at a low operating voltage of ∼1.0 V such as on/off ratio of ∼3 × 10{sup 7}, subthreshold swing of ∼65 mV/dec, threshold voltage of ∼0.3 V, and mobility of ∼7 cm{sup 2}/V s. Good positive gate bias stress stabilities are obtained. Furthermore, a low voltage driven resistor-loaded inverter was built by using an IZO transistor in series with a load resistor, exhibiting a linear relationship between the voltage gain and the supplied voltage. The inverter is also used for decreasing noises of input signals. The protonic/electronic hybrid IZO transistors have potential applications in biochemical sensors and portable electronics.

Small-size low-temperature scanning tunnel microscope

International Nuclear Information System (INIS)

Al'tfeder, I.B.; Khajkin, M.S.

1989-01-01

A small-size scanning tunnel microscope, designed for operation in transport helium-filled Dewar flasks is described. The microscope design contains a device moving the pin to the tested sample surface and a piezoelectric fine positioning device. High vibration protection of the microscope is provided by its suspension using silk threads. The small-size scanning tunnel microscope provides for atomic resolution

A monochromatic, aberration-corrected, dual-beam low energy electron microscope.

Science.gov (United States)

Mankos, Marian; Shadman, Khashayar

2013-07-01

The monochromatic, aberration-corrected, dual-beam low energy electron microscope (MAD-LEEM) is a novel instrument aimed at imaging of nanostructures and surfaces at sub-nanometer resolution that includes a monochromator, aberration corrector and dual beam illumination. The monochromator reduces the energy spread of the illuminating electron beam, which significantly improves spectroscopic and spatial resolution. The aberration corrector utilizes an electron mirror with negative aberrations that can be used to compensate the aberrations of the LEEM objective lens for a range of electron energies. Dual flood illumination eliminates charging generated when a conventional LEEM is used to image insulating specimens. MAD-LEEM is designed for the purpose of imaging biological and insulating specimens, which are difficult to image with conventional LEEM, Low-Voltage SEM, and TEM instruments. The MAD-LEEM instrument can also be used as a general purpose LEEM with significantly improved resolution. The low impact energy of the electrons is critical for avoiding beam damage, as high energy electrons with keV kinetic energies used in SEMs and TEMs cause irreversible change to many specimens, in particular biological materials. A potential application for MAD-LEEM is in DNA sequencing, which demands imaging techniques that enable DNA sequencing at high resolution and speed, and at low cost. The key advantages of the MAD-LEEM approach for this application are the low electron impact energies, the long read lengths, and the absence of heavy-atom DNA labeling. Image contrast simulations of the detectability of individual nucleotides in a DNA strand have been developed in order to refine the optics blur and DNA base contrast requirements for this application. Copyright © 2013 Elsevier B.V. All rights reserved.

A Grid Connected Transformerless Inverter and its Model Predictive Control Strategy with Leakage Current Elimination Capability

Directory of Open Access Journals (Sweden)

J. Fallah Ardashir

2017-06-01

Full Text Available This paper proposes a new single phase transformerless Photovoltaic (PV inverter for grid connected systems. It consists of six power switches, two diodes, one capacitor and filter at the output stage. The neutral of the grid is directly connected to the negative terminal of the source. This results in constant common mode voltage and zero leakage current. Model Predictive Controller (MPC technique is used to modulate the converter to reduce the output current ripple and filter requirements. The main advantages of this inverter are compact size, low cost, flexible grounding configuration. Due to brevity, the operating principle and analysis of the proposed circuit are presented in brief. Simulation and experimental results of 200W prototype are shown at the end to validate the proposed topology and concept. The results obtained clearly verifies the performance of the proposed inverter and its practical application for grid connected PV systems.

A review of single-phase grid-connected inverters for photovoltaic modules

DEFF Research Database (Denmark)

Kjaer, Soren Baekhoej; Pedersen, John Kim; Blaabjerg, Frede

2005-01-01

-phase grid; 3) whether they utilizes a transformer (either line or high frequency) or not; and 4) the type of grid-connected power stage. Various inverter topologies are presented, compared, and evaluated against demands, lifetime, component ratings, and cost. Finally, some of the topologies are pointed out......This review focuses on inverter technologies for connecting photovoltaic (PV) modules to a single-phase grid. The inverters are categorized into four classifications: 1) the number of power processing stages in cascade; 2) the type of power decoupling between the PV module(s) and the single...

Designing an Inverter-based Operational Transconductance Amplifier-capacitor Filter with Low Power Consumption for Biomedical Applications.

Science.gov (United States)

Yousefinezhad, Sajad; Kermani, Saeed; Hosseinnia, Saeed

2018-01-01

The operational transconductance amplifier-capacitor (OTA-C) filter is one of the best structures for implementing continuous-time filters. It is particularly important to design a universal OTA-C filter capable of generating the desired filter response via a single structure, thus reducing the filter circuit power consumption as well as noise and the occupied space on the electronic chip. In this study, an inverter-based universal OTA-C filter with very low power consumption and acceptable noise was designed with applications in bioelectric and biomedical equipment for recording biomedical signals. The very low power consumption of the proposed filter was achieved through introducing bias in subthreshold MOSFET transistors. The proposed filter is also capable of simultaneously receiving favorable low-, band-, and high-pass filter responses. The performance of the proposed filter was simulated and analyzed via HSPICE software (level 49) and 180 nm complementary metal-oxide-semiconductor technology. The rate of power consumption and noise obtained from simulations are 7.1 nW and 10.18 nA, respectively, so this filter has reduced noise as well as power consumption. The proposed universal OTA-C filter was designed based on the minimum number of transconductance blocks and an inverter circuit by three transconductance blocks (OTA).

An analysis of the technical exigencies and CE marking relative to low voltage (less than 5 kW) photovoltaic inverters marketed in Spain

International Nuclear Information System (INIS)

Salas, V.; Olias, E.

2009-01-01

The objective of this article is to analyse the standards relative to technical exigencies and CE marking that correspond to photovoltaic inverters of low voltage (less than 5 kW) as marketed in Spain. For this study, around 400 different models of inverters from the European market were compiled. Twelve of them, 50 Hz single phase, were chosen, made up of different brands and options of transformer below 5 kW. For these inverters, regulations for each model were examined according to their data sheet specifications, manual and EC Declarations of Conformity. Heterogeneity in compliance to the standards was found. In addition, in view of results obtained it is possible to conclude that it would be wise to establish a common set of standards for every country in the world (or at least a common European normalization) according to PV grid inverters. It would enable all grid inverters to be commercialised in compliance with the same standards everywhere. (author)

Thermal Optimized Operation of the Single-Phase Full-Bridge PV Inverter under Low Voltage Ride-Through Mode

DEFF Research Database (Denmark)

Wang, Huai; Yang, Yongheng; Blaabjerg, Frede

2013-01-01

The efficiency of 98% has been reported on transformer-less photovoltaic (PV) inverters and the penetration of grid-connected PV systems is booming as well. In the future, the PV systems are expected to contribute to the grid stability by means of low voltage ride-through operation and grid suppo...

High-speed elevators controlled by inverters

Energy Technology Data Exchange (ETDEWEB)

Sakai, Yoshio; Takahashi, Hideaki; Nakamura, Kiyoshi; Kinoshita, Hiroshi

1988-10-25

The super-high-speed elevator with superiority to 300m/min of speed, requires both the large capacity power and wide range speed controls. Therefore, in order to materialize the smooth and quiet operation characteristics, by applying the inverter control, the low torque ripple control in the low frequency range and high frequency large capacity inverting for lowering the motor in noise are necessary with their being assured of reliability. To satisfy the above necessary items, together with the development of a sine wave pulse width and frequency modulation (PWM/PFM) control system, to more precisely enable the sine wave electric current control, and 3kHz switching power converter, using a 800A power transistor module, a supervoltage control circuit under the extraordinary condition was designed. As a result of commercializing a 360m/min super-high speed inverter elevator, the power source unit, due to the effect of high power factor, could be reduced by 30% in capacity and also the higher harmonic wave including ratio could be considerably lowered to the inferiority to 5%. 2 references, 7 figures, 1 table.

Thin type inverter for machine-room-less elevator; Machine roomless elevator yo usugata inverter

Energy Technology Data Exchange (ETDEWEB)

NONE

2000-01-10

In the elevator industry, a machine-room-less elevator, which does not necessitate a machine room usually installed on the roof, has come into the spotlight in the domain of low and intermediate speed elevators. The lack of a machine room, however, will necessarily limit the space for the installation of the traction motor and control panel. Fuji Electric Co., Ltd., in order to properly cope with the situation, has developed in cooperation with Fujitec Co., Ltd., a very thin type inverter installable on an elevator hall floor. The inverter, based on Fuji Electric's high-performance vector control inverter FRENIC5000VG5, is as thin as 100mm, and is available in three series up to 11kW. For the embodiment of such a thin structure, a cooling structure of Fuji Electric's own is employed, and prudence is exercised as required at many locations so that maintainability will not be impaired throughout the very thin control panel design. (translated by NEDO)

Simulation of push-pull inverter using wide bandgap devices

Science.gov (United States)

Al-badri, Mustafa; Matin, Mohammed A.

2016-09-01

This paper discusses the use of wide bandgap devices (SiC-MOSFET) in the design of a push-pull inverter which provides inexpensive low power dc-ac inverters. The parameters used were 1200V SiC MOSFET(C2M0040120D) made by power company ROHM. This modeling was created using parameters that were provided from a device datasheet. The spice model is provided by this company to study the effect of adding this component on push-pull inverter ordinary circuit and compared results between SiC MOSFET and silicon MOSFET (IRFP260M). The results focused on Vout and Vmos stability as well as on output power and MOSFET power loss because it is a very crucial aspect on DC-AC inverter design. These results are done using the National Instrument simulation program (Multisim 14). It was found that power loss is better in the 12 and 15 vdc inverter. The Vout in the SIC MOSFET circuit shows more stability in the high current low resistance load in comparison to the Silicon MOSFET circuit and this will improve the overall performance of the circuit.

A single-phase embedded Z-source DC-AC inverter.

Science.gov (United States)

Kim, Se-Jin; Lim, Young-Cheol

2014-01-01

In the conventional DC-AC inverter consisting of two DC-DC converters with unipolar output capacitors, the output capacitor voltages of the DC-DC converters must be higher than the DC input voltage. To overcome this weakness, this paper proposes a single-phase DC-AC inverter consisting of two embedded Z-source converters with bipolar output capacitors. The proposed inverter is composed of two embedded Z-source converters with a common DC source and output AC load. Though the output capacitor voltages of the converters are relatively low compared to those of a conventional inverter, an equivalent level of AC output voltages can be obtained. Moreover, by controlling the output capacitor voltages asymmetrically, the AC output voltage of the proposed inverter can be higher than the DC input voltage. To verify the validity of the proposed inverter, experiments were performed with a DC source voltage of 38 V. By controlling the output capacitor voltages of the converters symmetrically or asymmetrically, the proposed inverter can produce sinusoidal AC output voltages. The experiments show that efficiencies of up to 95% and 97% can be achieved with the proposed inverter using symmetric and asymmetric control, respectively.

Cost-Effectiveness of Endoscopic Versus Microscopic Transsphenoidal Surgery for Pituitary Adenoma.

Science.gov (United States)

Ament, Jared D; Yang, Zhuo; Khatchadourian, Vic; Strong, Edward B; Shahlaie, Kiarash

2018-02-01

Endoscopic transsphenoidal surgery (ETPS) has become increasingly popular for resection of pituitary tumors, whereas microscopic transsphenoidal surgery (MTPS) also remains a commonly used approach. The economic sustainability of new techniques and technologies is rarely evaluated in the neurosurgical skull base literature. The aim of this study was to determine the cost-effectiveness of ETPS compared with MTPS. A Markov model was constructed to conduct a cost-utility analysis of ETPS versus MTPS from a single-payer health care perspective. Data were obtained from previously published outcomes studies. Costs were based on Medicare reimbursement rates, considering covariates such as complications, length of stay, and operative time. The base case adopted a 2-year follow-up period. Univariate and multivariate sensitivity analyses were conducted. On average, ETPS costs $143 less and generates 0.014 quality-adjusted life years (QALYs) compared with MTPS over 2 years. The incremental cost-effectiveness ratio (ICER) is -$10,214 per QALY, suggesting economic dominance. The QALY benefit increased to 0.105 when modeled to 10 years, suggesting that ETPS becomes even more favorable over time. ETPS appears to be cost-effective when compared with MTPS because the ICER falls below the commonly accepted $50,000 per QALY benchmark. Model limitations and assumptions affect the generalizability of the conclusion; however, ongoing efforts to improve rhinologic morbidity related to ETPS would appear to further augment the marginal cost savings and QALYs gained. Further research on the cost-effectiveness of ETPS using prospective data is warranted. Copyright © 2017 Elsevier Inc. All rights reserved.

Mitigation of Grid Current Distortion for LCL-Filtered Voltage Source Inverter with Inverter Current Feedback Control

DEFF Research Database (Denmark)

Xin, Zhen; Mattavelli, Paolo; Yao, WenLi

2018-01-01

LCL filters feature low inductance; thus, the injected grid current from an LCL-filtered Voltage Source Inverter (VSI) can be easily distorted by grid voltage harmonics. This problem is especially tough for the control system with Inverter-side Current Feedback (ICF), since the grid current...... harmonics can freely flow into the filter capacitor. In this case, because of the loss of harmonic information, traditional harmonic controllers fail to mitigate the grid current distortion. Although this problem may be avoided using the grid voltage feedforward scheme, the required differentiators may...

SIMULTANEOUS SPACE VECTOR MODULATION DIRECT TORQUE CONTROL OF TWO INDUCTION MOTORS USED IN ELECTRIC VEHICLES BY A NINE-SWITCH INVERTER

Directory of Open Access Journals (Sweden)

A. R. SHAMLOU

2017-12-01

Full Text Available In this paper, a novel two output nine switch-inverter is proposed in order to increase the synchronization speed of induction motors used in electric vehicles (EVs while improving the efficiency and controllability of the system. The number of switches in the proposed inverter is reduced by 25% compared to double six-switch inverters which conventionally used in EVs. The main characteristics of the considered inverter can be noted as follows: sinusoidal input and outputs, unity output power factor, and specifically, low construction cost due to active switch number reduction. The classical direct torque control method causes torque ripple and speed fluctuations. Therefore, in order to increase accuracy and dynamics of drive system, the SVM-DTC method is proposed, leading to less torque ripple and constant switching frequency. The obtained torque ripple is 2% which is less than the existing structures In order to illustrate advantages of the proposed approach, performance of the EVs in the standard cycles is evaluated.

Proper alignment of the microscope.

Science.gov (United States)

Rottenfusser, Rudi

2013-01-01

The light microscope is merely the first element of an imaging system in a research facility. Such a system may include high-speed and/or high-resolution image acquisition capabilities, confocal technologies, and super-resolution methods of various types. Yet more than ever, the proverb "garbage in-garbage out" remains a fact. Image manipulations may be used to conceal a suboptimal microscope setup, but an artifact-free image can only be obtained when the microscope is optimally aligned, both mechanically and optically. Something else is often overlooked in the quest to get the best image out of the microscope: Proper sample preparation! The microscope optics can only do its job when its design criteria are matched to the specimen or vice versa. The specimen itself, the mounting medium, the cover slip, and the type of immersion medium (if applicable) are all part of the total optical makeup. To get the best results out of a microscope, understanding the functions of all of its variable components is important. Only then one knows how to optimize these components for the intended application. Different approaches might be chosen to discuss all of the microscope's components. We decided to follow the light path which starts with the light source and ends at the camera or the eyepieces. To add more transparency to this sequence, the section up to the microscope stage was called the "Illuminating Section", to be followed by the "Imaging Section" which starts with the microscope objective. After understanding the various components, we can start "working with the microscope." To get the best resolution and contrast from the microscope, the practice of "Koehler Illumination" should be understood and followed by every serious microscopist. Step-by-step instructions as well as illustrations of the beam path in an upright and inverted microscope are included in this chapter. A few practical considerations are listed in Section 3. Copyright © 2013 Elsevier Inc. All rights

Low cost light-sheet microscopy for whole brain imaging

Science.gov (United States)

Kumar, Manish; Nasenbeny, Jordan; Kozorovitskiy, Yevgenia

2018-02-01

Light-sheet microscopy has evolved as an indispensable tool in imaging biological samples. It can image 3D samples at fast speed, with high-resolution optical sectioning, and with reduced photobleaching effects. These properties make light-sheet microscopy ideal for imaging fluorophores in a variety of biological samples and organisms, e.g. zebrafish, drosophila, cleared mouse brains, etc. While most commercial turnkey light-sheet systems are expensive, the existing lower cost implementations, e.g. OpenSPIM, are focused on achieving high-resolution imaging of small samples or organisms like zebrafish. In this work, we substantially reduce the cost of light-sheet microscope system while targeting to image much larger samples, i.e. cleared mouse brains, at single-cell resolution. The expensive components of a lightsheet system - excitation laser, water-immersion objectives, and translation stage - are replaced with an incoherent laser diode, dry objectives, and a custom-built Arduino-controlled translation stage. A low-cost CUBIC protocol is used to clear fixed mouse brain samples. The open-source platforms of μManager and Fiji support image acquisition, processing, and visualization. Our system can easily be extended to multi-color light-sheet microscopy.

A low cost high resolution pattern generator for electron-beam lithography

International Nuclear Information System (INIS)

Pennelli, G.; D'Angelo, F.; Piotto, M.; Barillaro, G.; Pellegrini, B.

2003-01-01

A simple, very low cost pattern generator for electron-beam lithography is presented. When it is applied to a scanning electron microscope, the system allows a high precision positioning of the beam for lithography of very small structures. Patterns are generated by a suitable software implemented on a personal computer, by using very simple functions, allowing an easy development of new writing strategies for a great adaptability to different user necessities. Hardware solutions, as optocouplers and battery supply, have been implemented for reduction of noise and disturbs on the voltages controlling the positioning of the beam

Microscopic study of low-lying yrast spectra and deformation ...

Indian Academy of Sciences (India)

73, No. 4. — journal of. October 2009 physics pp. 657–668. Microscopic study of low-lying yrast spectra and deformation systematics in neutron-rich. 98−106Sr isotopes ... with a large and rigid moment of inertia. 98Sr is predicted to have a ... 2 energy as neutron number N changes from 58 to 60. The onset of deformation in ...

Inverter for Interchangeable Use as Current Source Inverter and Voltage Source Inverter for Interconnecting to Grid

Science.gov (United States)

Teruya, Daisuke; Masukawa, Shigeo; Iida, Shoji

We propose a novel inverter that can be operated either as a Current Source Inverter (CSI) or as a Voltage Source Inverter (VSI) by changing only the control signals. It is proper to apply it to the interconnecting system with renewal energy, such as photovoltaic cells or wind generation systems, to a grid. This inverter is usually operated as the CSI connected to the grid. Even if the energy source has a lower voltage than the grid, the energy can be supplied to the grid through the proposed inverter. The power factor can be briefly maintained at almost unity. When power supply from the grid is interrupted, the proposed circuit should be operated as the VSI in the stand-alone operation mode. In this way, the circuit can maintain a constant output voltage to the loads. In this paper, the proposed circuit configuration and the control schemes for both the CSI and the VSI are described. Further, the circuit characteristics for both are discussed experimentally.

Integrated Inverter And Battery Charger

Science.gov (United States)

Rippel, Wally E.

1988-01-01

Circuit combines functions of dc-to-ac inversion (for driving ac motor in battery-powered vehicle) and ac-to-dc conversion (for charging battery from ac line when vehicle not in use). Automatically adapts to either mode. Design of integrated inverter/charger eliminates need for duplicate components, saves space, reduces weight and cost of vehicle. Advantages in other applications : load-leveling systems, standby ac power systems, and uninterruptible power supplies.

Solution-processed p-type copper(I) thiocyanate (CuSCN) for low-voltage flexible thin-film transistors and integrated inverter circuits

KAUST Repository

Petti, Luisa

2017-03-17

We report on low operating voltage thin-film transistors (TFTs) and integrated inverters based on copper(I) thiocyanate (CuSCN) layers processed from solution at low temperature on free-standing plastic foils. As-fabricated coplanar bottom-gate and staggered top-gate TFTs exhibit hole-transporting characteristics with average mobility values of 0.0016 cm2 V−1 s−1 and 0.013 cm2 V−1 s−1, respectively, current on/off ratio in the range 102–104, and maximum operating voltages between −3.5 and −10 V, depending on the gate dielectric employed. The promising TFT characteristics enable fabrication of unipolar NOT gates on flexible free-standing plastic substrates with voltage gain of 3.4 at voltages as low as −3.5 V. Importantly, discrete CuSCN transistors and integrated logic inverters remain fully functional even when mechanically bent to a tensile radius of 4 mm, demonstrating the potential of the technology for flexible electronics.

Proposed Novel Multiphase-Multilevel Inverter Configuration for Open-End Winding Loads

DEFF Research Database (Denmark)

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

2016-01-01

This paper presents a new multiphase-multilevel inverter configuration for open-winding loads and suitable for medium power (low-voltage/high-current) applications such as `More Electric Aircraft'. Modular structure comprised of standard dual three-phase voltage source inverter (VSI) along with one...... is developed in this work and overcomes the complexity of standard space vector modulations, easy for real implementation purposes in digital processors. Proposed six-phase multilevel inverter configuration generates multilevel outputs with benefit in comprises with standard multilevel inverter topologies...

Low-cost inertial measurement unit.

Energy Technology Data Exchange (ETDEWEB)

Deyle, Travis Jay

2005-03-01

Sandia National Laboratories performs many expensive tests using inertial measurement units (IMUs)--systems that use accelerometers, gyroscopes, and other sensors to measure flight dynamics in three dimensions. For the purpose of this report, the metrics used to evaluate an IMU are cost, size, performance, resolution, upgradeability and testing. The cost of a precision IMU is very high and can cost hundreds of thousands of dollars. Thus the goals and results of this project are as follows: (1) Examine the data flow in an IMU and determine a generic IMU design. (2) Discuss a high cost IMU implementation and its theoretically achievable results. (3) Discuss design modifications that would save money for suited applications. (4) Design and implement a low cost IMU and discuss its theoretically achievable results. (5) Test the low cost IMU and compare theoretical results with empirical results. (6) Construct a more streamlined printed circuit board design reducing noise, increasing capabilities, and constructing a self-contained unit. Using these results, we can compare a high cost IMU versus a low cost IMU using the metrics from above. Further, we can examine and suggest situations where a low cost IMU could be used instead of a high cost IMU for saving cost, size, or both.

Optimization of SiC-based H5 and Conergy-NPC transformerless PV inverters

DEFF Research Database (Denmark)

Saridakis, Stefanos; Koutroulis, Eftichios; Blaabjerg, Frede

2013-01-01

effective in terms of energy production than their non-optimized and Si-based counterparts. Reducing the market price of SiC-type power semiconductors enables to design optimized PV inverters with a lower cost of energy than that of PV inverters employing Si technology, thus maximizing the economic...... profitability of the PV system....

An inverter/controller subsystem optimized for photovoltaic applications

Science.gov (United States)

Pickrell, R. L.; Merrill, W. C.; Osullivan, G.

1978-01-01

Conversion of solar array dc power to ac power stimulated the specification, design, and simulation testing of an inverter/controller subsystem tailored to the photovoltaic power source characteristics. This paper discusses the optimization of the inverter/controller design as part of an overall Photovoltaic Power System (PPS) designed for maximum energy extraction from the solar array. The special design requirements for the inverter/controller include: (1) a power system controller (PSC) to control continuously the solar array operating point at the maximum power level based on variable solar insolation and cell temperatures; and (2) an inverter designed for high efficiency at rated load and low losses at light loadings to conserve energy. It must be capable of operating connected to the utility line at a level set by an external controller (PSC).

Control Aspects of a LCL Grid-Connected Green Power Inverter

DEFF Research Database (Denmark)

Kjær, Søren Bækhøj; Andersen, Gert Karmisholt; Klumpner, Christian

2002-01-01

A full-bridge inverter for interfacing the utility grid is developed for using in a Green Power Inverter application. The inverter is feed from an arbitrary green power source (fuel cell, photovoltaic, small wind turbine etc.) through a rectifier into the dc-link. In order to maintain a sinusoidal...... grid current with low harmonic distortion and a high power factor, the inverter is controlled to emulate a negative resistance towards the grid. The size of the emulated resistor is determined by the dc-link voltage controller, which tries to maintain a constant dc-link voltage. This is however...

The performance of Dutch photovoltaic inverters in areas with low grid voltage. A preliminary study

International Nuclear Information System (INIS)

Van Twisk, J.; Van der Borg, N.J.C.M.; Groeman, J.F.

2000-08-01

An important component of grid-connected photovoltaic (PV) systems is the inverter. The inverter must be suitable for the expected characteristics of the input of the photovoltaic panels and for the expected characteristics of the output of the electricity network. The characteristics of the electric grid in potential markets for Dutch inverter manufacturers can differ from the characteristics of Dutch electric grids. A preliminary study has been carried out to determine the characteristics of relevant power distribution systems and the expected effects of those networks on PV-inverters. It is concluded that the following characteristics need further study: voltage level (nominal voltage and long-lasting deviations of that level); transient overvoltages, harmonic components in the voltage, and direct current component. 5 refs

[Ultrastructural organization of cytoplasmatic membrane of Anaerobacter polyendosporus studied by electron microscopic cryofractography].

Science.gov (United States)

Duda, V I; Suzina, N E; Dmitriev, V V

2001-01-01

Anaerobacter polyendosporus cells do not have typical mesosomes. However, the analysis of this anaerobic multispore bacterium by electron microscopic cryofractography showed that its cytoplasmic membrane contains specific intramembrane structures in the form of flat lamellar inverted lipid membranes tenths of nanometers to several microns in size. It was found that these structures are located in the hydrophobic interior between the outer and inner leaflets of the cytoplasmic membrane and do not contain intramembrane particles that are commonly present on freeze-fracture replicas. The flat inverted lipid membranes were revealed in bacterial cells cultivated under normal growth conditions, indicating the existence of a complex-type compartmentalization in biological membranes, which manifests itself in the formation of intramembrane compartments having the appearance of vesicles and inverted lipid membranes.

Y-source inverter

DEFF Research Database (Denmark)

Siwakoti, Yam P.; Town, Graham; Loh, Poh Chiang

2014-01-01

This paper introduces a new 3-phase Y-source inverter whose gain is presently not matched by classical impedance-network-based inverters operating at the same duty ratio. The proposed network uses a tightly coupled transformer with three windings. By squeezing the shoot-through range while keeping...... higher boost, the inverter can operate at a higher modulation index, thereby minimizing switching device stress and providing better output power quality. In addition, the inverter has more degrees of freedom for setting the voltage gain and modulation index than other classical impedance-source networks...

Low temperature ultrahigh vacuum cross-sectional scanning tunneling microscope for luminescence measurements

International Nuclear Information System (INIS)

Khang, Yoonho; Park, Yeonjoon; Salmeron, Miquel; Weber, Eicke R.

1999-01-01

We have constructed a scanning tunneling microscope with simultaneous light collection capabilities in order to investigate the opto-electronic properties of semiconductors. The microscope has in situ sample cleavage mechanism for cross-sectional sample. In order to reach low temperature (4 K), we used a specially designed cryostat. The efficiency of light collection generated in the tip-surface junction was greatly improved by use of a small parabolic mirror with the tip located at its focal point. (c) 1999 American Institute of Physics

Current Harmonics from Single-Phase Grid-Connected Inverters

DEFF Research Database (Denmark)

Yang, Yongheng; Zhou, Keliang; Blaabjerg, Frede

2016-01-01

Environmental conditions and operational modes may significantly impact the distortion level of the injected current from single-phase grid-connected inverter systems, such as photovoltaic (PV) inverters, which may operate in cloudy days with a maximum power point tracking, in a non-unity power...... factor, or in the low voltage ride through mode with reactive current injection. In this paper, the mechanism of the harmonic current injection from grid-connected single-phase inverter systems is thus explored, and the analysis is conducted on single-phase PV systems. In particular, the analysis...... is focused on the impacts of the power factor and the feed-in grid current level on the quality of the feed-in grid current from single-phase inverters. As a consequence, an internal model principle based high performance current control solution is tailor-made and developed for single-phase grid-connected...

New Switched-Dual-Source Multilevel Inverter for Symmetrical and Asymmetrical Operation

Directory of Open Access Journals (Sweden)

Kennedy Adinbo Aganah

2018-04-01

Full Text Available The increasing integration of large solar PV and wind farms into the power grid has fueled, over the past two decades, growing demands for high-power, high-voltage, utility-scale inverters. Multilevel inverters have emerged as the industry’s choice for megawatt-range inverters because of their reduced voltage stress, capability for generating an almost-sinusoidal voltage, built-in redundancy and other benefits. This paper presents a novel switched-source multilevel inverter (SS MLI architecture. This new inverter shows superior capabilities when compared to existing topologies. It has reduced voltage stress on the semiconductor, uses fewer switches (i.e., reduced size/weight/cost and exhibits increased efficiency. The proposed SS MLI is comprised of two voltage sources ( V 1 , V 2 and six switches. It is capable of generating five-level output voltage in symmetric mode (i.e., V 1 = V 2 and seven-level output voltage in asymmetric mode (i.e., V 1 ≠ V 2 . We present simulations results (using MATLAB®/Simulink® for five- and seven-level output voltages, and they strongly support the validity of the proposed inverter. These positive results are further supported experimentally using a laboratory prototype.

Comparative Study of Modulation-Based Individual Inverter Techniques for Direct and Inverse by using Star-Connection Induction Motor in Extra Low Voltage Application

Directory of Open Access Journals (Sweden)

Ardhia Wishnuprakasa

2016-12-01

Full Text Available In this study, the IEEE 519 Standard as a basis benchmarking for voltage (THDV and current (THDI in draft performance. Comparative Study based onthree-techniques of 2-Level Converter (2LC by using a Star-Connection Induction Motor (Y-CIM in ExtraLow Voltage (ELV Configuration.For the detail explanation, a primary inverter as Direct-Inverterby PWMdirect (PWM degreesand asecondary inverter as Inverse-Inverterby PWMinverse(PWM + PI degrees. It tends a modified algorithm,for eachof SPWM in six rules, and FHIPWM in 5th harmonics Injectedin standard modulation as the purpose for the Open-Ends of Pre-Dual Inverter in Decoupled SPWM for twelve rules, and Decoupled FHIPWM in combination of 5th harmonics Injectedin combination of two-standard-modulation. Those techniques are the purpose of two-inverter combination, which namelythe Equal Direct-Inverse (EDI algorithmproduct of prototyping in similarities. The observation is restricted in voltage scope between Simulation by using Power Simulator (PSIMand Application by using Microcontroller ARM STM32F4 Discovery.

A single molecule DNA flow stretching microscope for undergraduates

NARCIS (Netherlands)

Williams, Kelly; Grafe, Brendan; Burke, Kathryn M.; Tanner, Nathan; van Oijen, Antoine M.; Loparo, Joseph; Price, Allen C.

2011-01-01

The design of a simple, safe, and inexpensive single molecule flow stretching instrument is presented. The instrument uses a low cost upright microscope coupled to a webcam for imaging single DNA molecules that are tethered in an easy to construct microfluidic flow cell. The system requires no

Atmospheric scanning electron microscope observes cells and tissues in open medium through silicon nitride film.

Science.gov (United States)

Nishiyama, Hidetoshi; Suga, Mitsuo; Ogura, Toshihiko; Maruyama, Yuusuke; Koizumi, Mitsuru; Mio, Kazuhiro; Kitamura, Shinichi; Sato, Chikara

2010-03-01

Direct observation of subcellular structures and their characterization is essential for understanding their physiological functions. To observe them in open environment, we have developed an inverted scanning electron microscope with a detachable, open-culture dish, capable of 8 nm resolution, and combined with a fluorescence microscope quasi-simultaneously observing the same area from the top. For scanning electron microscopy from the bottom, a silicon nitride film window in the base of the dish maintains a vacuum between electron gun and open sample dish while allowing electrons to pass through. Electrons are backscattered from the sample and captured by a detector under the dish. Cells cultured on the open dish can be externally manipulated under optical microscopy, fixed, and observed using scanning electron microscopy. Once fine structures have been revealed by scanning electron microscopy, their component proteins may be identified by comparison with separately prepared fluorescence-labeled optical microscopic images of the candidate proteins, with their heavy-metal-labeled or stained ASEM images. Furthermore, cell nuclei in a tissue block stained with platinum-blue were successfully observed without thin-sectioning, which suggests the applicability of this inverted scanning electron microscope to cancer diagnosis. This microscope visualizes mesoscopic-scale structures, and is also applicable to non-bioscience fields including polymer chemistry. (c) 2010 Elsevier Inc. All rights reserved.

Single stage buck-boost DC-AC neutral point clamped inverter

DEFF Research Database (Denmark)

Mo, Wei; Loh, Poh Chiang; Andrew, A.

2012-01-01

This paper proposes a new single stage buck-boost DC-AC neutral point clamped inverter topology which integrates the cascaded configurations of recently introduced inductor-capacitor-capacitor-transformer impedance source network (by Adamowicz) and classic NPC configuration. As a consequence......, it has enhanced buck-boost functionality and low output voltage distortions compared to the traditional Z-source inverter; it has continuous input current which reduces the source stress and inverter noise; it also contains two built-in capacitors which can block the DC current in the transformer...... windings thus preventing the core from saturation; lowers the voltage stresses and power losses of inverter switches and reduces the sizes of filtering devices and as well as obtains better output performance compared to the original two-level Z-source inverters. A phase disposition pulse width modulation...

On the Impacts of PV Array Sizing on the Inverter Reliability and Lifetime

DEFF Research Database (Denmark)

Sangwongwanich, Ariya; Yang, Yongheng; Sera, Dezso

2018-01-01

, the total energy yield can be increased under weak solar irradiance conditions. However, oversizing the PV array will increase the loading of PV inverters, which may have undesired influence on the PV inverter reliability and lifetime. In that case, it may result in a negative impact on the overall PV...... energy cost, due to the increased maintenance for the PV inverters. With the above concern, this paper evaluates the reliability and lifetime of PV inverters considering the PV array sizing. The evaluation is based on the mission profile of the installation sites in Denmark and Arizona, where...... the reliability-critical components such as power devices and capacitors are considered. The results reveal that the variation in the PV array sizing can considerably deviate the reliability performance and lifetime expectation of PV inverters, especially for those installed in Denmark, where the average solar...

Dynamic Low-Vacuum Scanning Electron Microscope Freeze Drying Observation for Fresh Water Algae

International Nuclear Information System (INIS)

Mohsen, H.T.; Ghaly, W.A.; Zahran, N.F.; Helal, A.I.

2010-01-01

A new perpetration method for serving in dynamic examinations of the fresh water algae is developed in connection with the Low-Vacuum Scanning Electron Microscope (LV-SEM) freeze drying technique. Specimens are collected from fresh water of Ismailia channel then transferred directly to freeze by liquid nitrogen and dried in the chamber of the scanning electron microscope in the low vacuum mode. Scanning electron micrographs revealed that the drying method presented the microstructure of algae. Dehydration in a graded ethanol series is not necessary in the new method. Dried algae specimen is observed in SEM high vacuum mode after conductive coating at higher resolution. Low-vacuum SEM freeze drying technique is a simple, time-saving and reproducible method for scanning electron microscopy that is applicable to various aquatic microorganisms covered with soft tissues.

Asymmetrical Grid Fault Ride-Through Strategy of Three-phase Grid-connected Inverter Considering Network Impedance Impact in Low Voltage Grid

DEFF Research Database (Denmark)

Guo, Xiaoqiang; Zhang, Xue; Wang, Baocheng

2014-01-01

This letter presents a new control strategy of threephase grid-connected inverter for the positive sequence voltage recovery and negative sequence voltage reduction under asymmetrical grid faults. Unlike the conventional control strategy based on an assumption that the network impedance is mainly...... of the proposed solution for the flexible voltage support in a low-voltage grid, where thenetwork impedance is mainly resistive.......This letter presents a new control strategy of threephase grid-connected inverter for the positive sequence voltage recovery and negative sequence voltage reduction under asymmetrical grid faults. Unlike the conventional control strategy based on an assumption that the network impedance is mainly...... inductive, the proposed control strategy is more flexible and effective by considering the network impedance impact, which is of great importance for the high penetration of grid-connected renewable energy systems into low-voltage grids. The experimental tests are carried out to validate the effectiveness...

Hidden costs of low-cost screening mammography

International Nuclear Information System (INIS)

Cyrlak, D.

1987-01-01

Twenty-two hundred women in Orange County, California, took part in a low-cost mammography screening project sponsored by the American Cancer Society and the KCBS-TV. Patients were followed up by telephone and questioned about actual costs incurred as a result of screening mammography, including costs of repeated and follow-up mammograms, US examinations and surgical consultations. The total number of biopsies, cancers found, and the costs involved were investigated. The authors' results suggest that particularly in centers with a high positive call rate, the cost of screening mammograms accounts for only a small proportion of the medical costs

Solution processable inverted structure ZnO-organic hybrid heterojuction white LEDs

Science.gov (United States)

Bano, N.; Hussain, I.; Soomro, M. Y.; EL-Naggar, A. M.; Albassam, A. A.

2018-05-01

Improving luminance efficiency and colour purity are the most important challenges for zinc oxide (ZnO)-organic hybrid heterojunction light emitting diodes (LEDs), affecting their large area applications. If ZnO-organic hybrid heterojunction white LEDs are fabricated by a hydrothermal method, it is difficult to obtain pure and stable blue emission from PFO due to the presence of an undesirable green emission. In this paper, we present an inverted-structure ZnO-organic hybrid heterojunction LED to avoid green emission from PFO, which mainly originates during device processing. With this configuration, each ZnO nanorod (NR) forms a discrete p-n junction; therefore, large-area white LEDs can be designed without compromising the junction area. The configuration used for this novel structure is glass/ZnO NRs/PFO/PEDOT:PSS/L-ITO, which enables the development of efficient, large-area and low-cost hybrid heterojunction LEDs. Inverted-structure ZnO-organic hybrid heterojunction white LEDs offer several improvements in terms of brightness, size, colour, external quantum efficiency and a wider applicability as compared to normal architecture LEDs.

Inverted oscillator

Energy Technology Data Exchange (ETDEWEB)

Yuce, C [Physics Department, Anadolu University, Eskisehir (Turkey); Kilic, A [Physics Department, Anadolu University, Eskisehir (Turkey); Coruh, A [Physics Department, Sakarya University, Sakarya (Turkey)

2006-07-15

The inverted harmonic oscillator problem is investigated quantum mechanically. The exact wavefunction for the confined inverted oscillator is obtained and it is shown that the associated energy eigenvalues are discrete, and the energy is given as a linear function of the quantum number n.

Membrane fusion and inverted phases

International Nuclear Information System (INIS)

Ellens, H.; Siegel, D.P.; Alford, D.; Yeagle, P.L.; Boni, L.; Lis, L.J.; Quinn, P.J.; Bentz, J.

1989-01-01

We have found a correlation between liposome fusion kinetics and lipid phase behavior for several inverted phase forming lipids. N-Methylated dioleoylphosphatidylethanolamine (DOPE-Me), or mixtures of dioleoylphosphatidylethanolamine (DOPE) and dioleoylphosphatidylcholine (DOPC), will form an inverted hexagonal phase (HII) at high temperatures (above TH), a lamellar phase (L alpha) at low temperatures, and an isotropic/inverted cubic phase at intermediate temperatures, which is defined by the appearance of narrow isotropic 31 P NMR resonances. The phase behavior has been verified by using high-sensitivity DSC, 31 P NMR, freeze-fracture electron microscopy, and X-ray diffraction. The temperature range over which the narrow isotropic resonances occur is defined as delta TI, and the range ends at TH. Extruded liposomes (approximately 0.2 microns in diameter) composed of these lipids show fusion and leakage kinetics which are strongly correlated with the temperatures of these phase transitions. At temperatures below delta TI, where the lipid phase is L alpha, there is little or no fusion, i.e., mixing of aqueous contents, or leakage. However, as the temperature reaches delta TI, there is a rapid increase in both fusion and leakage rates. At temperatures above TH, the liposomes show aggregation-dependent lysis, as the rapid formation of HII phase precursors disrupts the membranes. We show that the correspondence between the fusion and leakage kinetics and the observed phase behavior is easily rationalized in terms of a recent kinetic theory of L alpha/inverted phase transitions. In particular, it is likely that membrane fusion and the L alpha/inverted cubic phase transition proceed via a common set of intermembrane intermediates

Modular inverter system

Science.gov (United States)

Ma, Mingyao; Hu, Haibing; Kutkut, Nasser; Batarseh, Issa; Shen, John; , Bkayrat, Raed

2017-08-01

A system connected to an AC power grid having an AC phase signal includes an inverter module including a first inverter coupled to a DC voltage, actuated based on the AC phase signal. The first inverter provides a first voltage signal having predetermined harmonic components. A second inverter includes second switch elements coupled to the DC voltage and actuated by a second set of control signals phase delayed with respect to the first control signals. A transformer module has first and second primary windings coupled to the first and second inverters. The transformer module further includes a secondary winding coupled to first primary winding, the second primary winding, and the AC power grid. The secondary winding is configured to provide a secondary output voltage to the AC power grid by combining the first voltage signal and the second voltage signal such that the predetermined harmonic components are substantially cancelled.

Performance analysis of new type grid-tied inverter-Aalborg Inverter

DEFF Research Database (Denmark)

Wu, Weimin; Wang, Zhen; Ji, Junhao

2014-01-01

Aalborg Inverter is a grid-tied DC/AC inverter. In order to optimize the design, its power losses are analyzed in detail, combined with a description of the single-phase operating principle and the modulation strategy. A 2 kW / 220 V experimental prototype is constructed to verify the theoretical...... analysis. It is concluded that a minimize inductance in the power loop does help the inverter to achieve the high efficiency with the good dynamic performance....

Waveform control method for mitigating harmonics of inverter systems with nonlinear load

DEFF Research Database (Denmark)

Wang, Haoran; Zhu, Guorong; Fu, Xiaobin

2015-01-01

instability in the DC power system, lower its efficiency, and shorten the lifetime of the DC source. This paper presents a general waveform control method that can mitigate the injection of the low-frequency ripple current by the single-phase DC/AC inverter into the DC source. It also discusses the inhibiting......DC power systems connecting to single-phase DC/AC inverters with nonlinear loads will have their DC sources being injected with AC ripple currents containing a low-frequency component at twice the output voltage frequency of the inverter and also other current harmonics. Such a current may create...

Use of an axisymmetric microscope with electronic readout for collecting soft X-ray images

International Nuclear Information System (INIS)

Cavailler, C.; Henry, P.; Launspach, J.; De Mascureau, J.; Millerioux, M.; Rostaing, M.; Sauneuf, R.

1984-08-01

The axisymmetric microscope, first discussed by Wolter, provides high resolution and sensitivity for investigating the soft X-ray emission of laser-driven plasmas. Such a device having a 10 X magnification has been constructed. We present a comparison between the images of laser-driven plasmas given by this microscope and by a 10 X pinhole camera. Until now these images were recorded on X-ray film. We have shown that film could be replaced by C.C.D. in a pinhole camera when the photon energy lies within the 1-10 keV range. Below 1 keV the quantum yield is too low so we have used an image converter tube made by RTC. It is a diode-inverter tube with a soft X-ray photocathode and a P20 phosphor deposited on an optic fiber plate. The electronic image appearing on the screen is read by a C.C.D. working in the visible spectral fields. An electronic image readout chain, which is identical to those associated with streak cameras, then processes automatically and immediately the images given by the microscope [fr

Smartphone Magnification Attachment: Microscope or Magnifying Glass

Science.gov (United States)

Hergemöller, Timo; Laumann, Daniel

2017-09-01

Today smartphones and tablets do not merely pervade our daily life, but also play a major role in STEM education in general, and in experimental investigations in particular. Enabling teachers and students to make use of these new techniques in physics lessons requires supplying capable and affordable applications. Our article presents the improvement of a low-cost technique turning smartphones into powerful magnifying glasses or microscopes. Adding only a 3D-printed clip attached to the smartphone's camera and inserting a small glass bead in this clip enables smartphones to take pictures with up to 780x magnification (see Fig. 1). In addition, the construction of the smartphone attachments helps to explain and examine the differences between magnifying glasses and microscopes, and shows that the widespread term "smartphone microscope" for this technique is inaccurate from a physics educational perspective.

Application of piezoceramic materials in low temperature scanning tunnel microscope

International Nuclear Information System (INIS)

Volodin, A.P.; Panich, A.E.

1989-01-01

Temperature dependences of the voltage-to-movement conversion coefficients for piezoceramic domestic materials PKR and TsTS-19 are measured using a capacitance dilatometer in the 0.4< T<300K temperature range. Anisotropy of thermal expansion of materials determined by the polarization vector is observed. Some recommendations concerning the use of the given materials in low-temperature scanning tunnel microscopes are given

Quasi-Y-source inverter

DEFF Research Database (Denmark)

Siwakoti, Yam Prasad; Blaabjerg, Frede; Loh, Poh Chiang

2015-01-01

This paper introduces a new inverter topology called a “quasi-Y-source inverter”. The proposed inverter inherits all the advantages of the original Y-source inverter. In addition, the new topology draws continuous current from the source which is required for many renewable sources. It also has dc......-current-blocking capacitors, which avoids saturation in the transformer core. Simulations and experimental results have proved the validity of the proposed inverter....

Development of a SEM-based low-energy in-line electron holography microscope for individual particle imaging.

Science.gov (United States)

Adaniya, Hidehito; Cheung, Martin; Cassidy, Cathal; Yamashita, Masao; Shintake, Tsumoru

2018-05-01

A new SEM-based in-line electron holography microscope has been under development. The microscope utilizes conventional SEM and BF-STEM functionality to allow for rapid searching of the specimen of interest, seamless interchange between SEM, BF-STEM and holographic imaging modes, and makes use of coherent low-energy in-line electron holography to obtain low-dose, high-contrast images of light element materials. We report here an overview of the instrumentation and first experimental results on gold nano-particles and carbon nano-fibers for system performance tests. Reconstructed images obtained from the holographic imaging mode of the new microscope show substantial image contrast and resolution compared to those acquired by SEM and BF-STEM modes, demonstrating the feasibility of high-contrast imaging via low-energy in-line electron holography. The prospect of utilizing the new microscope to image purified biological specimens at the individual particle level is discussed and electron optical issues and challenges to further improve resolution and contrast are considered. Copyright © 2018 Elsevier B.V. All rights reserved.

A cost-effective fluorescence mini-microscope for biomedical applications.

Science.gov (United States)

Zhang, Yu Shrike; Ribas, João; Nadhman, Akhtar; Aleman, Julio; Selimović, Šeila; Lesher-Perez, Sasha Cai; Wang, Ting; Manoharan, Vijayan; Shin, Su-Ryon; Damilano, Alessia; Annabi, Nasim; Dokmeci, Mehmet Remzi; Takayama, Shuichi; Khademhosseini, Ali

2015-01-01

We have designed and fabricated a miniature microscope from off-the-shelf components and a webcam, with built-in fluorescence capability for biomedical applications. The mini-microscope was able to detect both biochemical parameters, such as cell/tissue viability (e.g. live/dead assay), and biophysical properties of the microenvironment such as oxygen levels in microfabricated tissues based on an oxygen-sensitive fluorescent dye. This mini-microscope has adjustable magnifications from 8-60×, achieves a resolution as high as microscope was able to chronologically monitor cell migration and analyze beating of microfluidic liver and cardiac bioreactors in real time, respectively. The mini-microscope system is cheap, and its modularity allows convenient integration with a wide variety of pre-existing platforms including, but not limited to, cell culture plates, microfluidic devices, and organs-on-a-chip systems. Therefore, we envision its widespread application in cell biology, tissue engineering, biosensing, microfluidics, and organs-on-chips, which can potentially replace conventional bench-top microscopy where long-term in situ and large-scale imaging/analysis is required.

Low-cost high purity production

Science.gov (United States)

Kapur, V. K.

1978-01-01

Economical process produces high-purity silicon crystals suitable for use in solar cells. Reaction is strongly exothermic and can be initiated at relatively low temperature, making it potentially suitable for development into low-cost commercial process. Important advantages include exothermic character and comparatively low process temperatures. These could lead to significant savings in equipment and energy costs.

A multipurpose hybrid conventional/scanning near-field optical microscope for applications in materials science and biology

International Nuclear Information System (INIS)

Longo, G; Girasole, M; Pompeo, G; Generosi, R; Luce, M; Cricenti, A

2010-01-01

A hybrid conventional/scanning near-field optical microscope is presented. The instrument is obtained coupling an Olympus IX-70 inverted optical microscope with a SNOM head, to combine the versatility and ease of use of the conventional microscope with the high-resolution and three-dimensional reconstruction achieved by the SNOM. The head can be run in shear or tapping mode and is optimized to characterize soft, biological samples including living cells in physiological environment by including the SNOM in a cylindrical chamber that insulates it from external noise, while maintaining a controlled temperature and atmosphere

A molybdenum disulfide/carbon nanotube heterogeneous complementary inverter.

Science.gov (United States)

Huang, Jun; Somu, Sivasubramanian; Busnaina, Ahmed

2012-08-24

We report a simple, bottom-up/top-down approach for integrating drastically different nanoscale building blocks to form a heterogeneous complementary inverter circuit based on layered molybdenum disulfide and carbon nanotube (CNT) bundles. The fabricated CNT/MoS(2) inverter is composed of n-type molybdenum disulfide (MOS(2)) and p-type CNT transistors, with a high voltage gain of 1.3. The CNT channels are fabricated using directed assembly while the layered molybdenum disulfide channels are fabricated by mechanical exfoliation. This bottom-up fabrication approach for integrating various nanoscale elements with unique characteristics provides an alternative cost-effective methodology to complementary metal-oxide-semiconductors, laying the foundation for the realization of high performance logic circuits.

A mini-microscope for in situ monitoring of cells.

Science.gov (United States)

Kim, Sang Bok; Koo, Kyo-in; Bae, Hojae; Dokmeci, Mehmet R; Hamilton, Geraldine A; Bahinski, Anthony; Kim, Sun Min; Ingber, Donald E; Khademhosseini, Ali

2012-10-21

A mini-microscope was developed for in situ monitoring of cells by modifying off-the-shelf components of a commercial webcam. The mini-microscope consists of a CMOS imaging module, a small plastic lens and a white LED illumination source. The CMOS imaging module was connected to a laptop computer through a USB port for image acquisition and analysis. Due to its compact size, 8 × 10 × 9 cm, the present microscope is portable and can easily fit inside a conventional incubator, and enables real-time monitoring of cellular behaviour. Moreover, the mini-microscope can be used for imaging cells in conventional cell culture flasks, such as Petri dishes and multi-well plates. To demonstrate the operation of the mini-microscope, we monitored the cellular migration of mouse 3T3 fibroblasts in a scratch assay in medium containing three different concentrations of fetal bovine serum (5, 10, and 20%) and demonstrated differential responses depending on serum levels. In addition, we seeded embryonic stem cells inside poly(ethylene glycol) microwells and monitored the formation of stem cell aggregates in real time using the mini-microscope. Furthermore, we also combined a lab-on-a-chip microfluidic device for microdroplet generation and analysis with the mini-microscope and observed the formation of droplets under different flow conditions. Given its cost effectiveness, robust imaging and portability, the presented platform may be useful for a range of applications for real-time cellular imaging using lab-on-a-chip devices at low cost.

A New Green Power Inverter for Fuel Cells

DEFF Research Database (Denmark)

Andersen, Gert Karmisholt; Klumpner, Christian; Kjær, Søren Bækhøj

2002-01-01

This paper presents a new grid connected inverter for fuel cells. It consists of a two stage power conversion topology. Since the fuel cell operates with a low voltage in a wide voltage range (25 V-45 V) this volt- age must be transformed to around 350-400 V in order to invert this dc power into ac...... power to the grid. The proposed converter consists of an isolated dc-dc converter cascaded with a single phase H-bridge inverter. The dc-dc converter is a current-fed push-pull converter. A new dedicated voltage mode startup procedure has been developed in order to limit the inrush current during...... startup. The inverter is controlled as a power factor controller with resistor emulation.Experimental results of converter efficiency, grid performance and fuel cell response are shown for a 1 kW prototype. The proposed converter exhibits a high efficiency in a wide power range (higher than 92...

Excitation of propagating surface plasmons with a scanning tunnelling microscope.

Science.gov (United States)

Wang, T; Boer-Duchemin, E; Zhang, Y; Comtet, G; Dujardin, G

2011-04-29

Inelastic electron tunnelling excitation of propagating surface plasmon polaritons (SPPs) on a thin gold film is demonstrated. This is done by combining a scanning tunnelling microscope (STM) with an inverted optical microscope. Analysis of the leakage radiation in both the image and Fourier planes unambiguously shows that the majority (up to 99.5%) of the detected photons originate from propagating SPPs with propagation lengths of the order of 10  µm. The remaining photon emission is localized under the STM tip and is attributed to a tip-gold film coupled plasmon resonance as evidenced by the bimodal spectral distribution and enhanced emission intensity observed using a silver STM tip for excitation.

Excitation of propagating surface plasmons with a scanning tunnelling microscope

International Nuclear Information System (INIS)

Wang, T; Boer-Duchemin, E; Zhang, Y; Comtet, G; Dujardin, G

2011-01-01

Inelastic electron tunnelling excitation of propagating surface plasmon polaritons (SPPs) on a thin gold film is demonstrated. This is done by combining a scanning tunnelling microscope (STM) with an inverted optical microscope. Analysis of the leakage radiation in both the image and Fourier planes unambiguously shows that the majority (up to 99.5%) of the detected photons originate from propagating SPPs with propagation lengths of the order of 10 μm. The remaining photon emission is localized under the STM tip and is attributed to a tip-gold film coupled plasmon resonance as evidenced by the bimodal spectral distribution and enhanced emission intensity observed using a silver STM tip for excitation.

Excitation of propagating surface plasmons with a scanning tunnelling microscope

Energy Technology Data Exchange (ETDEWEB)

Wang, T; Boer-Duchemin, E; Zhang, Y; Comtet, G; Dujardin, G, E-mail: Elizabeth.Boer-Duchemin@u-psud.fr [Institut des Sciences Moleculaire d' Orsay (ISMO), CNRS Universite Paris-Sud, 91405 Orsay (France)

2011-04-29

Inelastic electron tunnelling excitation of propagating surface plasmon polaritons (SPPs) on a thin gold film is demonstrated. This is done by combining a scanning tunnelling microscope (STM) with an inverted optical microscope. Analysis of the leakage radiation in both the image and Fourier planes unambiguously shows that the majority (up to 99.5%) of the detected photons originate from propagating SPPs with propagation lengths of the order of 10 {mu}m. The remaining photon emission is localized under the STM tip and is attributed to a tip-gold film coupled plasmon resonance as evidenced by the bimodal spectral distribution and enhanced emission intensity observed using a silver STM tip for excitation.

A new on-chip all-digital three-phase full-bridge dc/ac power inverter with feedforward and frequency control techniques.

Science.gov (United States)

Chen, Jiann-Jong; Kung, Che-Min

2010-09-01

The communication speed between components is far from satisfactory. To achieve high speed, simple control system configuration, and low cost, a new on-chip all-digital three-phase dc/ac power inverter using feedforward and frequency control techniques is proposed. The controller of the proposed power inverter, called the shift register, consists of six-stage D-latch flip-flops with a goal of achieving low-power consumption and area efficiency. Variable frequency is achieved by controlling the clocks of the shift register. One advantage regarding the data signal (D) and the common clock (CK) is that, regardless of the phase difference between the two, all of the D-latch flip-flops are capable of delaying data by one CK period. To ensure stability, the frequency of CK must be six times higher than that of D. The operation frequency of the proposed power inverter ranges from 10 Hz to 2 MHz, and the maximum output loading current is 0.8 A. The prototype of the proposed circuit has been fabricated with TSMC 0.35 μm 2P4M CMOS processes. The total chip area is 2.333 x 1.698 mm2. The three-phase dc/ac power inverter is applicable in uninterrupted power supplies, cold cathode fluorescent lamps, and motors, because of its ability to convert the dc supply voltage into the three-phase ac power sources.

Analysis and Design of Solar Photo voltaic Grid Connected Inverter

Directory of Open Access Journals (Sweden)

Muddasani Satyanarayana

2015-08-01

Full Text Available This paper presents common mode voltage analysis of single phase grid connected photovoltaic inverter. Many researchers proposed different grid tie inverters for applications like domestic powering, street lighting, water pumping, cooling and heating applications, however traditional grid tie PV inverter uses either a line frequency or a high frequency transformer between the inverter and grid but losses will increase in the network leading to reduced efficiency of the system. In order to increase the efficiency, with reduced size and cost of the system, the effective solution is to remove the isolation transformer. But common mode (CM ground leakage current due to parasitic capacitance between the PV panels and the ground making the system unreliable. The common mode current reduces the efficiency of power conversion stage, affects the quality of grid current, deteriorate the electric magnetic compatibility and give rise to the safety threats. In order to eliminate the common mode leakage current in Transformerless PV systm two control algorithms of multi-carrier pwm are implemented and compared for performance analysis.The shoot-through issue that is encountered by traditional voltage source inverter is analyzed for enhanced system reliability. These control algorithms are compared for common mode voltage and THD comparisons. The proposed system is designed using MATLAB/SIMULINK software for analysis.

Inverted pendulum as low-frequency pre-isolation for advanced gravitational wave detectors

International Nuclear Information System (INIS)

Takamori, A.; Raffai, P.; Marka, S.; DeSalvo, R.; Sannibale, V.; Tariq, H.; Bertolini, A.; Cella, G.; Viboud, N.; Numata, K.; Takahashi, R.; Fukushima, M.

2007-01-01

We have developed advanced seismic attenuation systems for Gravitational Wave (GW) detectors. The design consists of an Inverted Pendulum (IP) holding stages of Geometrical Anti-Spring Filters (GASF) and pendula, which isolate the test mass suspension from ground noise. The ultra-low-frequency IP suppresses the horizontal seismic noise, while the GASF suppresses the vertical ground vibrations. The three legs of the IP are supported by cylindrical maraging steel flexural joints. The IP can be tuned to very low frequencies by carefully adjusting its load. As a best result, we have achieved an ultra low, ∼12 mHz pendulum frequency for the system prototype made for Advanced LIGO (Laser Interferometer Gravitational Wave Observatory). The measured quality factor, Q, of this IP, ranging from Q∼2500 (at 0.45 Hz) to Q∼2 (at 12 mHz), is compatible with structural damping, and is proportional to the square of the pendulum frequency. Tunable counterweights allow for precise center-of-percussion tuning to achieve the required attenuation up to the first leg internal resonance (∼60 Hz for advanced LIGO prototype). All measurements are in good agreement with our analytical models. We therefore expect good attenuation in the low-frequency region, from ∼0.1to ∼50 Hz, covering the micro-seismic peak. The extremely soft IP requires minimal control force, which simplifies any needed actuation

Low temperature behavior of magnetic domains observed using a magnetic force microscope

International Nuclear Information System (INIS)

Chung, S. H.; Shinde, S. R.; Ogale, S. B.; Venkatesan, T.; Greene, R. L.; Dreyer, M.; Gomez, R. D.

2001-01-01

A commercial atomic force microscope/magnetic force microscope (MFM) was modified to cool magnetic samples down to around 100 K under a high vacuum while maintaining its routine imaging functionality. MFM images of a 120 nm thick La 0.7 Ca 0.3 MnO 3 film on a LaAlO 3 substrate at low temperature show the paramagnetic-to-ferromagnetic phase transition. Evolution of magnetic domains and magnetic ripples with decreasing temperature are also observed near the edge of a 20 nm thick patterned Co film on a Si substrate. [copyright] 2001 American Institute of Physics

Control of Grid Connected Photovoltaic System Using Three-Level T-Type Inverter

Science.gov (United States)

Zorig, Abdelmalik; Belkeiri, Mohammed; Barkat, Said; Rabhi, Abdelhamid

2016-08-01

Three-level T-Type inverter (3LT2I) topology has numerous advantageous compared to three-level neutral-point-clamped (NPC) inverter. The main benefits of 3LT2I inverter are the efficiency, inverter cost, switching losses, and the quality of output voltage waveforms. In this paper, a photovoltaic distributed generation system based on dual-stage topology of DC-DC boost converter and 3LT2I is introduced. To that end, a decoupling control strategy of 3LT2I is proposed to control the current injected into the grid, reactive power compensation, and DC-link voltage. The resulting system is able to extract the maximum power from photovoltaic generator, to achieve sinusoidal grid currents, and to ensure reactive power compensation. The voltage-balancing control of two split DC capacitors of the 3LT2I is achieved using three-level space vector modulation with balancing strategy based on the effective use of the redundant switching states of the inverter voltage vectors. The proposed system performance is investigated at different operating conditions.

Origin-Dependent Inverted-Repeat Amplification: Tests of a Model for Inverted DNA Amplification.

Directory of Open Access Journals (Sweden)

Bonita J Brewer

2015-12-01

Full Text Available DNA replication errors are a major driver of evolution--from single nucleotide polymorphisms to large-scale copy number variations (CNVs. Here we test a specific replication-based model to explain the generation of interstitial, inverted triplications. While no genetic information is lost, the novel inversion junctions and increased copy number of the included sequences create the potential for adaptive phenotypes. The model--Origin-Dependent Inverted-Repeat Amplification (ODIRA-proposes that a replication error at pre-existing short, interrupted, inverted repeats in genomic sequences generates an extrachromosomal, inverted dimeric, autonomously replicating intermediate; subsequent genomic integration of the dimer yields this class of CNV without loss of distal chromosomal sequences. We used a combination of in vitro and in vivo approaches to test the feasibility of the proposed replication error and its downstream consequences on chromosome structure in the yeast Saccharomyces cerevisiae. We show that the proposed replication error-the ligation of leading and lagging nascent strands to create "closed" forks-can occur in vitro at short, interrupted inverted repeats. The removal of molecules with two closed forks results in a hairpin-capped linear duplex that we show replicates in vivo to create an inverted, dimeric plasmid that subsequently integrates into the genome by homologous recombination, creating an inverted triplication. While other models have been proposed to explain inverted triplications and their derivatives, our model can also explain the generation of human, de novo, inverted amplicons that have a 2:1 mixture of sequences from both homologues of a single parent--a feature readily explained by a plasmid intermediate that arises from one homologue and integrates into the other homologue prior to meiosis. Our tests of key features of ODIRA lend support to this mechanism and suggest further avenues of enquiry to unravel the origins

Origin-Dependent Inverted-Repeat Amplification: Tests of a Model for Inverted DNA Amplification.

Science.gov (United States)

Brewer, Bonita J; Payen, Celia; Di Rienzi, Sara C; Higgins, Megan M; Ong, Giang; Dunham, Maitreya J; Raghuraman, M K

2015-12-01

DNA replication errors are a major driver of evolution--from single nucleotide polymorphisms to large-scale copy number variations (CNVs). Here we test a specific replication-based model to explain the generation of interstitial, inverted triplications. While no genetic information is lost, the novel inversion junctions and increased copy number of the included sequences create the potential for adaptive phenotypes. The model--Origin-Dependent Inverted-Repeat Amplification (ODIRA)-proposes that a replication error at pre-existing short, interrupted, inverted repeats in genomic sequences generates an extrachromosomal, inverted dimeric, autonomously replicating intermediate; subsequent genomic integration of the dimer yields this class of CNV without loss of distal chromosomal sequences. We used a combination of in vitro and in vivo approaches to test the feasibility of the proposed replication error and its downstream consequences on chromosome structure in the yeast Saccharomyces cerevisiae. We show that the proposed replication error-the ligation of leading and lagging nascent strands to create "closed" forks-can occur in vitro at short, interrupted inverted repeats. The removal of molecules with two closed forks results in a hairpin-capped linear duplex that we show replicates in vivo to create an inverted, dimeric plasmid that subsequently integrates into the genome by homologous recombination, creating an inverted triplication. While other models have been proposed to explain inverted triplications and their derivatives, our model can also explain the generation of human, de novo, inverted amplicons that have a 2:1 mixture of sequences from both homologues of a single parent--a feature readily explained by a plasmid intermediate that arises from one homologue and integrates into the other homologue prior to meiosis. Our tests of key features of ODIRA lend support to this mechanism and suggest further avenues of enquiry to unravel the origins of interstitial

High performance Si nanowire field-effect-transistors based on a CMOS inverter with tunable threshold voltage.

Science.gov (United States)

Van, Ngoc Huynh; Lee, Jae-Hyun; Sohn, Jung Inn; Cha, Seung Nam; Whang, Dongmok; Kim, Jong Min; Kang, Dae Joon

2014-05-21

We successfully fabricated nanowire-based complementary metal-oxide semiconductor (NWCMOS) inverter devices by utilizing n- and p-type Si nanowire field-effect-transistors (NWFETs) via a low-temperature fabrication processing technique. We demonstrate that NWCMOS inverter devices can be operated at less than 1 V, a significantly lower voltage than that of typical thin-film based complementary metal-oxide semiconductor (CMOS) inverter devices. This low-voltage operation was accomplished by controlling the threshold voltage of the n-type Si NWFETs through effective management of the nanowire (NW) doping concentration, while realizing high voltage gain (>10) and ultra-low static power dissipation (≤3 pW) for high-performance digital inverter devices. This result offers a viable means of fabricating high-performance, low-operation voltage, and high-density digital logic circuits using a low-temperature fabrication processing technique suitable for next-generation flexible electronics.

Dynamic Evaluation of LCL-type Grid-Connected Inverters with Different Current Feedback Control Schemes

DEFF Research Database (Denmark)

Han, Yang; Li, Zipeng; Guerrero, Josep M.

2015-01-01

typical current feedback control schemes in LCL grid-connected system are analyzed and compared systematically. Analysis in s-domain take the effect of the digital computation and modulation delay into account. The stability analysis is presented by root locus in the discrete domain, the optimal values......Proportional-resonant (PR) compensator and LCL filter becomes a better choice in grid-connected inverter system with high performance and low costs. However, the resonance phenomenon caused by LCL filter affect the system stability significantly. In this paper, the stability problem of three...

Inverted annular flow experimental study

International Nuclear Information System (INIS)

De Jarlais, G.; Ishii, M.

1985-04-01

Steady-state inverted annular flow of Freon 113 in up flow was established in a transparent test section. Using a special inlet configuration consisting of long aspect-ratio liquid nozzles coaxially centered within a heated quartz tube, idealized inverted annular flow initial geometry (cylindrical liquid core surrounded by coaxial annulus of gas) could be established. Inlet liquid and gas flowrates, liquid subcooling, and gas density (using various gas species) were measured and varied systematically. The hydrodynamic behavior of the liquid core, and the subsequent downstream break-up of this core into slugs, ligaments and/or droplets of various sizes, was observed. In general, for low inlet liquid velocities it was observed that after the initial formation of roll waves on the liquid core surface, an agitated region of high surface area, with attendant high momentum and energy transfers, occurs. This agitated region appears to propagate downsteam in a quasi-periodic pattern. Increased inlet liquid flow rates, and high gas annulus flow rates tend to diminish the significance of this agitated region. Observed inverted annular flow (and subsequent downstream flow pattern) hydrodynamic behavior is reported, and comparisons are drawn to data generated by previous experimenters studying post-CHF flow

The Development of Standardized, Low-Cost AC PV Systems; TOPICAL; Final Technical Report; 8 September 1995-30 June 1998

International Nuclear Information System (INIS)

Strong, S.

1999-01-01

Solar Design Associates, Inc. (SDA), of Harvard, Massachusetts, and Solarex Corporation, of Frederick, Maryland, teamed with Advanced Energy Systems (AES) of Wilton, New Hampshire, to pursue a multi-level program under a Photovoltaic Manufacturing Technology (PVMaT) solicitation. This program was targeted at design innovation, standardization, and modularity, with the goal to deliver low-cost AC PV systems to the utility-interactive market. One significant result of this program is that Solarex filed a U.S. patent application on the new module frame and mounting system that was developed with support from PVMaT. Solarex has already started to manufacture this new combination framing and array mounting system, and a number of residential-scale installations are already in place in the field. The major AES accomplishment under this program was the development of a reliable, FCC-compliant AC module inverter fully listed by Underwriters Laboratories (UL). The inverter passed various environmental tests, including those required by UL (the same temperature and humidity cycling tests that PV modules require), and is now in commercial production

Reprint of: Atmospheric scanning electron microscope observes cells and tissues in open medium through silicon nitride film.

Science.gov (United States)

Nishiyama, Hidetoshi; Suga, Mitsuo; Ogura, Toshihiko; Maruyama, Yuusuke; Koizumi, Mitsuru; Mio, Kazuhiro; Kitamura, Shinichi; Sato, Chikara

2010-11-01

Direct observation of subcellular structures and their characterization is essential for understanding their physiological functions. To observe them in open environment, we have developed an inverted scanning electron microscope with a detachable, open-culture dish, capable of 8 nm resolution, and combined with a fluorescence microscope quasi-simultaneously observing the same area from the top. For scanning electron microscopy from the bottom, a silicon nitride film window in the base of the dish maintains a vacuum between electron gun and open sample dish while allowing electrons to pass through. Electrons are backscattered from the sample and captured by a detector under the dish. Cells cultured on the open dish can be externally manipulated under optical microscopy, fixed, and observed using scanning electron microscopy. Once fine structures have been revealed by scanning electron microscopy, their component proteins may be identified by comparison with separately prepared fluorescence-labeled optical microscopic images of the candidate proteins, with their heavy-metal-labeled or stained ASEM images. Furthermore, cell nuclei in a tissue block stained with platinum-blue were successfully observed without thin-sectioning, which suggests the applicability of this inverted scanning electron microscope to cancer diagnosis. This microscope visualizes mesoscopic-scale structures, and is also applicable to non-bioscience fields including polymer chemistry. Copyright © 2010 Elsevier Inc. All rights reserved.

A multi-modal stereo microscope based on a spatial light modulator.

Science.gov (United States)

Lee, M P; Gibson, G M; Bowman, R; Bernet, S; Ritsch-Marte, M; Phillips, D B; Padgett, M J

2013-07-15

Spatial Light Modulators (SLMs) can emulate the classic microscopy techniques, including differential interference (DIC) contrast and (spiral) phase contrast. Their programmability entails the benefit of flexibility or the option to multiplex images, for single-shot quantitative imaging or for simultaneous multi-plane imaging (depth-of-field multiplexing). We report the development of a microscope sharing many of the previously demonstrated capabilities, within a holographic implementation of a stereo microscope. Furthermore, we use the SLM to combine stereo microscopy with a refocusing filter and with a darkfield filter. The instrument is built around a custom inverted microscope and equipped with an SLM which gives various imaging modes laterally displaced on the same camera chip. In addition, there is a wide angle camera for visualisation of a larger region of the sample.

Local Reactive Power Control Methods for Overvoltage Prevention of Distributed Solar Inverters in Low-Voltage Grids

DEFF Research Database (Denmark)

Demirok, Erhan; Gonzalez, Pablo Casado; Frederiksen, Kenn H. B.

2011-01-01

on sensitivity analysis. The sensitivity analysis shows that the same amount of reactive power becomes more effective for grid voltage support if the solar inverter is located at the end of a feeder. Based on this fundamental knowledge, a location-dependent power factor set value can be assigned to each inverter......voltage (LV) grids by means of solar inverters with reactive power control capability. This paper underlines weak points of standard reactive power strategies which are already imposed by certain grid codes, and then, the study introduces a new reactive power control method that is based......, and the grid voltage support can be achieved with less total reactive power consumption. In order to prevent unnecessary reactive power absorption from the grid during admissible voltage range or to increase reactive power contribution from the inverters that are closest to the transformer during grid...

Fault-tolerant three-level inverter

Science.gov (United States)

Edwards, John; Xu, Longya; Bhargava, Brij B.

2006-12-05

A method for driving a neutral point clamped three-level inverter is provided. In one exemplary embodiment, DC current is received at a neutral point-clamped three-level inverter. The inverter has a plurality of nodes including first, second and third output nodes. The inverter also has a plurality of switches. Faults are checked for in the inverter and predetermined switches are automatically activated responsive to a detected fault such that three-phase electrical power is provided at the output nodes.

Final Report Report: Smart Grid Ready PV Inverters with Utility Communication

Energy Technology Data Exchange (ETDEWEB)

Seal, Brian [Electric Power Research Inst. (EPRI), Knovville, TN (United States); Huque, Aminul [Electric Power Research Inst. (EPRI), Knovville, TN (United States); Rogers, Lindsey [Electric Power Research Inst. (EPRI), Knovville, TN (United States); Key, Tom [Electric Power Research Inst. (EPRI), Knovville, TN (United States); Riley, Cameron [Electric Power Research Inst. (EPRI), Knovville, TN (United States); Li, Huijuan [Electric Power Research Inst. (EPRI), Knovville, TN (United States); York, Ben [Electric Power Research Inst. (EPRI), Knovville, TN (United States); Purcell, Chris [BPL Global, Inc., Canonsburg, PA (United States); Pacific, Oliver [Spirae, Inc., Fort Collins, CO (United States); Ropp, Michael [Northern Plains Power Technologies, Brookings, SD (United States); Tran, Teresa [DTE Energy, Detroit, MI (United States); Asgeirsson, Hawk [DTE Energy, Detroit, MI (United States); Woodard, Justin [National Grid, Warwick (United Kingdom); Steffel, Steve [Pepco Holdings, Inc., Washington, DC (United States)

2016-03-30

In 2011, EPRI began a four-year effort under the Department of Energy (DOE) SunShot Initiative Solar Energy Grid Integration Systems - Advanced Concepts (SEGIS-AC) to demonstrate smart grid ready inverters with utility communication. The objective of the project was to successfully implement and demonstrate effective utilization of inverters with grid support functionality to capture the full value of distributed photovoltaic (PV). The project leveraged ongoing investments and expanded PV inverter capabilities, to enable grid operators to better utilize these grid assets. Developing and implementing key elements of PV inverter grid support capabilities will increase the distribution system’s capacity for higher penetration levels of PV, while reducing the cost. The project team included EPRI, Yaskawa-Solectria Solar, Spirae, BPL Global, DTE Energy, National Grid, Pepco, EDD, NPPT and NREL. The project was divided into three phases: development, deployment, and demonstration. Within each phase, the key areas included: head-end communications for Distributed Energy Resources (DER) at the utility operations center; methods for coordinating DER with existing distribution equipment; back-end PV plant master controller; and inverters with smart-grid functionality. Four demonstration sites were chosen in three regions of the United States with different types of utility operating systems and implementations of utility-scale PV inverters. This report summarizes the project and findings from field demonstration at three utility sites.

Analisis Harmonisa Inverter PWM Satu Fasa

OpenAIRE

Rejeki Simanjorang

2008-01-01

Pada tesis ini dianalisis harmonisa inverter PWM satu fasa. Inverter PWM satu fasa yang akan ditinjau adalah inverter satu fasa jembatan penuh (konvensional) dan inverter komposit. Analisis difokuskan pada penentuan pola penyaklaran yang optimum agar pembangkitan harmonisa dan switching losses inverter rendah. Untuk menentukan pola penyaklaran optimum maka dilakukan analisis yang berbasis pada rangkaian ekivalen harmonisa inverter satu fasa. Dengan menggunakan pola penyaklaran optimum, kedua ...

2015 Inverter Workshop | Photovoltaic Research | NREL

Science.gov (United States)

Inverter Workshop 2015 Inverter Workshop Wednesday, February 25, 2015 Chair: Jack Flicker In about inverters. This workshop represented a follow-on to the inverter workshops that Sandia National conversations between module and inverter experts. Agenda For a detailed schedule of the day's events, access

Cost-Effectiveness Analysis of Microscopic and Endoscopic Transsphenoidal Surgery Versus Medical Therapy in the Management of Microprolactinoma in the United States.

Science.gov (United States)

Jethwa, Pinakin R; Patel, Tapan D; Hajart, Aaron F; Eloy, Jean Anderson; Couldwell, William T; Liu, James K

2016-03-01

Although prolactinomas are treated effectively with dopamine agonists, some have proposed curative surgical resection for select cases of microprolactinomas to avoid life-long medical therapy. We performed a cost-effectiveness analysis comparing transsphenoidal surgery (either microsurgical or endoscopic) and medical therapy (either bromocriptine or cabergoline) with decision analysis modeling. A 2-armed decision tree was created with TreeAge Pro Suite 2012 to compare upfront transsphenoidal surgery versus medical therapy. The economic perspective was that of the health care third-party payer. On the basis of a literature review, we assigned plausible distributions for costs and utilities to each potential outcome, taking into account medical and surgical costs and complications. Base-case analysis, sensitivity analysis, and Monte Carlo simulations were performed to determine the cost-effectiveness of each strategy at 5-year and 10-year time horizons. In the base-case scenario, microscopic transsphenoidal surgery was the most cost-effective option at 5 years from the time of diagnosis; however, by the 10-year time horizon, endoscopic transsphenoidal surgery became the most cost-effective option. At both time horizons, medical therapy (both bromocriptine and cabergoline) were found to be more costly and less effective than transsphenoidal surgery (i.e., the medical arm was dominated by the surgical arm in this model). Two-way sensitivity analysis demonstrated that endoscopic resection would be the most cost-effective strategy if the cure rate from endoscopic surgery was greater than 90% and the complication rate was less than 1%. Monte Carlo simulation was performed for endoscopic surgery versus microscopic surgery at both time horizons. This analysis produced an incremental cost-effectiveness ratio of $80,235 per quality-adjusted life years at 5 years and $40,737 per quality-adjusted life years at 10 years, implying that with increasing time intervals, endoscopic

DC-DC Type High-Frequency Link DC for Improved Power Quality of Cascaded Multilevel Inverter

Science.gov (United States)

Sadikin, Muhammad; Senjyu, Tomonobu; Yona, Atsushi

2013-06-01

Multilevel inverters are emerging as a new breed of power converter options for power system applications. Recent advances in power switching devices enabled the suitability of multilevel inverters for high voltage and high power applications because they are connecting several devices in series without the need of component matching. Usually, a transformerless battery energy storage system, based on a cascaded multilevel inverter, is used as a measure for voltage and frequency deviations. System can be reduced in size, weight, and cost of energy storage system. High-frequency link circuit topology is advantageous in realizing compact and light-weight power converters for uninterruptible power supply systems, new energy systems using photovoltaic-cells, fuel-cells and so on. This paper presents a DC-DC type high-frequency link DC (HFLDC) cascaded multilevel inverter. Each converter cell is implemented a control strategy for two H-bridge inverters that are controlled with the same multicarrier pulse width modulation (PWM) technique. The proposed cascaded multilevel inverter generates lower voltage total harmonic distortion (THD) in comparison with conventional cascaded multilevel inverter. Digital simulations are carried out using PSCAD/EMTDC to validate the performance of the proposed cascaded multilevel inverter.

Milliwatt dc/dc Inverter

Science.gov (United States)

Mclyman, C. W.

1983-01-01

Compact dc/dc inverter uses single integrated-circuit package containing six inverter gates that generate and amplify 100-kHz square-wave switching signal. Square-wave switching inverts 10-volt local power to isolated voltage at another desired level. Relatively high operating frequency reduces size of filter capacitors required, resulting in small package unit.

Magnetic lens apparatus for a low-voltage high-resolution electron microscope

Science.gov (United States)

Crewe, Albert V.

1996-01-01

A lens apparatus in which a beam of charged particles of low accelerating voltage is brought to a focus by a magnetic field, the lens being situated behind the target position. The lens comprises an electrically-conducting coil arranged around the axis of the beam and a magnetic pole piece extending along the axis of the beam at least within the space surrounded by the coil. The lens apparatus comprises the sole focusing lens for high-resolution imaging in a low-voltage scanning electron microscope.

Printed 2 V-operating organic inverter arrays employing a small-molecule/polymer blend.

Science.gov (United States)

Shiwaku, Rei; Takeda, Yasunori; Fukuda, Takashi; Fukuda, Kenjiro; Matsui, Hiroyuki; Kumaki, Daisuke; Tokito, Shizuo

2016-10-04

Printed organic thin-film transistors (OTFTs) are well suited for low-cost electronic applications, such as radio frequency identification (RFID) tags and sensors. Achieving both high carrier mobility and uniform electrical characteristics in printed OTFT devices is essential in these applications. Here, we report on printed high-performance OTFTs and circuits using silver nanoparticle inks for the source/drain electrodes and a blend of dithieno[2,3-d;2',3'-d']benzo[1,2-b;4,5-b']dithiophene (DTBDT-C 6 ) and polystyrene for the organic semiconducting layer. A high saturation region mobility of 1.0 cm 2  V -1  s -1 at low operation voltage of -5 V was obtained for relatively short channel lengths of 9 μm. All fifteen of the printed pseudo-CMOS inverter circuits were formed on a common substrate and operated at low operation voltage of 2 V with the total variation in threshold voltage of 0.35 V. Consequently, the printed OTFT devices can be used in more complex integrated circuit applications requiring low manufacturing cost over large areas.

Printed 2 V-operating organic inverter arrays employing a small-molecule/polymer blend

Science.gov (United States)

Shiwaku, Rei; Takeda, Yasunori; Fukuda, Takashi; Fukuda, Kenjiro; Matsui, Hiroyuki; Kumaki, Daisuke; Tokito, Shizuo

2016-10-01

Printed organic thin-film transistors (OTFTs) are well suited for low-cost electronic applications, such as radio frequency identification (RFID) tags and sensors. Achieving both high carrier mobility and uniform electrical characteristics in printed OTFT devices is essential in these applications. Here, we report on printed high-performance OTFTs and circuits using silver nanoparticle inks for the source/drain electrodes and a blend of dithieno[2,3-d2‧,3‧-d‧]benzo[1,2-b4,5-b‧]dithiophene (DTBDT-C6) and polystyrene for the organic semiconducting layer. A high saturation region mobility of 1.0 cm2 V-1 s-1 at low operation voltage of -5 V was obtained for relatively short channel lengths of 9 μm. All fifteen of the printed pseudo-CMOS inverter circuits were formed on a common substrate and operated at low operation voltage of 2 V with the total variation in threshold voltage of 0.35 V. Consequently, the printed OTFT devices can be used in more complex integrated circuit applications requiring low manufacturing cost over large areas.

Mission profile based multi-disciplinary analysis of power modules in single-phase transformerless photovoltaic inverters

DEFF Research Database (Denmark)

Yang, Yongheng; Wang, Huai; Blaabjerg, Frede

2013-01-01

years) has been set as a main target and an emerging demand from the customers, which imposes a new challenge on grid-connected transformerless inverters. In order to reduce maintenance cost, it is essential to predict the lifetime of the transformerless PV inverter and its components based......The popularity of transformerless photovoltaic (PV) inverters in Europe proves that these topologies can achieve higher efficiency (e.g., ≥ 98% has been reported). Along with the advanced power electronics technology and the booming development of PV power systems, a long service time (e.g. 25...... on the mission profiles — solar irradiance and ambient temperature. In this paper, a mission profile based analysis approach is proposed and it is demonstrated by three main single-phase transformerless PV inverters — Full-Bridge (FB) with bipolar modulation scheme, the FB inverter with DC bypass (FB...

Real-time digital simulation of power electronics systems with Neutral Point Piloted multilevel inverter using FPGA

Energy Technology Data Exchange (ETDEWEB)

Rakotozafy, Mamianja [Groupe de Recherches en Electrotechnique et Electronique de Nancy (GREEN), Faculte des Sciences et Techniques, BP 70239, 54506 Vandoeuvre Cedex (France); CONVERTEAM SAS, Parc d' activites Techn' hom, 24 avenue du Marechal Juin, BP 40437, 90008 Belfort Cedex (France); Poure, Philippe [Laboratoire d' Instrumentation Electronique de Nancy (LIEN), Faculte des Sciences et Techniques, BP 70239, 54506 Vandoeuvre Cedex (France); Saadate, Shahrokh [Groupe de Recherches en Electrotechnique et Electronique de Nancy (GREEN), Faculte des Sciences et Techniques, BP 70239, 54506 Vandoeuvre Cedex (France); Bordas, Cedric; Leclere, Loic [CONVERTEAM SAS, Parc d' activites Techn' hom, 24 avenue du Marechal Juin, BP 40437, 90008 Belfort Cedex (France)

2011-02-15

Most of actual real time simulation platforms have practically about ten microseconds as minimum calculation time step, mainly due to computation limits such as processing speed, architecture adequacy and modeling complexities. Therefore, simulation of fast switching converters' instantaneous models requires smaller computing time step. The approach presented in this paper proposes an answer to such limited modeling accuracies and computational bandwidth of the currently available digital simulators.As an example, the authors present a low cost, flexible and high performance FPGA-based real-time digital simulator for a complete complex power system with Neutral Point Piloted (NPP) three-level inverter. The proposed real-time simulator can model accurately and efficiently the complete power system, reducing costs, physical space and avoiding any damage to the actual equipment in the case of any dysfunction of the digital controller prototype. The converter model is computed at a small fixed time step as low as 100 ns. Such a computation time step allows high precision account of the gating signals and thus avoids averaging methods and event compensations. Moreover, a novel high performance model of the NPP three-level inverter has also been proposed for FPGA implementation. The proposed FPGA-based simulator models the environment of the NPP converter: the dc link, the RLE load and the digital controller and gating signals. FPGA-based real time simulation results are presented and compared with offline results obtained using PLECS software. They validate the efficiency and accuracy of the modeling for the proposed high performance FPGA-based real-time simulation approach. This paper also introduces new potential FPGA-based applications such as low cost real time simulator for power systems by developing a library of flexible and portable models for power converters, electrical machines and drives. (author)

A mini-microscope for in situ monitoring of cells†‡

Science.gov (United States)

Kim, Sang Bok; Koo, Kyo-in; Bae, Hojae; Dokmeci, Mehmet R.; Hamilton, Geraldine A.; Bahinski, Anthony; Kim, Sun Min; Ingber, Donald E.

2013-01-01

A mini-microscope was developed for in situ monitoring of cells by modifying off-the-shelf components of a commercial webcam. The mini-microscope consists of a CMOS imaging module, a small plastic lens and a white LED illumination source. The CMOS imaging module was connected to a laptop computer through a USB port for image acquisition and analysis. Due to its compact size, 8 × 10 × 9 cm, the present microscope is portable and can easily fit inside a conventional incubator, and enables real-time monitoring of cellular behaviour. Moreover, the mini-microscope can be used for imaging cells in conventional cell culture flasks, such as Petri dishes and multi-well plates. To demonstrate the operation of the mini-microscope, we monitored the cellular migration of mouse 3T3 fibroblasts in a scratch assay in medium containing three different concentrations of fetal bovine serum (5, 10, and 20%) and demonstrated differential responses depending on serum levels. In addition, we seeded embryonic stem cells inside poly(ethylene glycol) microwells and monitored the formation of stem cell aggregates in real time using the mini-microscope. Furthermore, we also combined a lab-on-a-chip microfluidic device for microdroplet generation and analysis with the mini-microscope and observed the formation of droplets under different flow conditions. Given its cost effectiveness, robust imaging and portability, the presented platform may be useful for a range of applications for real-time cellular imaging using lab-on-a-chip devices at low cost. PMID:22911426

Low cost solar air heater

International Nuclear Information System (INIS)

Gill, R.S.; Singh, Sukhmeet; Singh, Parm Pal

2012-01-01

Highlights: ► Single glazed low cost solar air heater is more efficient during summer while double glazed is better in winter. ► For the same initial investment, low cost solar air heaters collect more energy than packed bed solar air heater. ► During off season low cost solar air heater can be stored inside as it is light in weight. - Abstract: Two low cost solar air heaters viz. single glazed and double glazed were designed, fabricated and tested. Thermocole, ultraviolet stabilised plastic sheet, etc. were used for fabrication to reduce the fabrication cost. These were tested simultaneously at no load and with load both in summer and winter seasons along with packed bed solar air heater using iron chips for absorption of radiation. The initial costs of single glazed and double glazed are 22.8% and 26.8% of the initial cost of packed bed solar air heater of the same aperture area. It was found that on a given day at no load, the maximum stagnation temperatures of single glazed and double glazed solar air heater were 43.5 °C and 62.5 °C respectively. The efficiencies of single glazed, double glazed and packed bed solar air heaters corresponding to flow rate of 0.02 m 3 /s-m 2 were 30.29%, 45.05% and 71.68% respectively in winter season. The collector efficiency factor, heat removal factor based on air outlet temperature and air inlet temperature for three solar air heaters were also determined.

Single DV-DXCCII Based Voltage Controlled First Order All-pass Filter with Inverting and Non-inverting responses

Directory of Open Access Journals (Sweden)

B Chaturvedi

2015-12-01

Full Text Available In this paper, a new voltage controlled first order all-pass filter is presented. The proposed circuit employs a single differential voltage dual-X second generation current conveyor (DV-DXCCII and a grounded capacitor only. The proposed all-pass filter provides both inverting and non inverting voltage-mode outputs from the same configuration simultaneously without any matching condition. Non-ideal analysis along with sensitivity analysis is also investigated. The proposed circuit has low active and passive sensitivities. As an application the proposed all-pass filter is connected in cascade to get higher order filter. The theoretical results are validated thorough PSPICE simulations using TSMC 0.18µm CMOS process parameters.

Ultra low-K shrinkage behavior when under electron beam in a scanning electron microscope

Energy Technology Data Exchange (ETDEWEB)

Lorut, F.; Imbert, G. [ST Microelectronics, 850 rue Jean Monnet, 38926 Crolles Cedex (France); Roggero, A. [Centre National d' Etudes Spatiales, 18 Avenue Edouard Belin, 31400 Toulouse (France)

2013-08-28

In this paper, we investigate the tendency of porous low-K dielectrics (also named Ultra Low-K, ULK) behavior to shrink when exposed to the electron beam of a scanning electron microscope. Various experimental electron beam conditions have been used for irradiating ULK thin films, and the resulting shrinkage has been measured through use of an atomic force microscope tool. We report the shrinkage to be a fast, cumulative, and dose dependent effect. Correlation of the shrinkage with incident electron beam energy loss has also been evidenced. The chemical modification of the ULK films within the interaction volume has been demonstrated, with a densification of the layer and a loss of carbon and hydrogen elements being observed.

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...

Inverted end-Hall-type low-energy high-current gaseous ion source

International Nuclear Information System (INIS)

Oks, E. M.; Vizir, A. V.; Shandrikov, M. V.; Yushkov, G. Yu.; Grishin, D. M.; Anders, A.; Baldwin, D. A.

2008-01-01

A novel approach to low-energy, high-current, gaseous ion beam generation was explored and an ion source based on this technique has been developed. The source utilizes a dc high-current (up to 20 A) gaseous discharge with electron injection into the region of ion generation. Compared to the conventional end-Hall ion source, the locations of the discharge anode and cathode are inverted: the cathode is placed inside the source and the anode outside, and correspondingly, the discharge current is in the opposite direction. The discharge operates in a diverging axial magnetic field, similar to the end-Hall source. Electron generation and injection is accomplished by using an additional arc discharge with a ''cold'' (filamentless) hollow cathode. Low plasma contamination is achieved by using a low discharge voltage (avoidance of sputtering), as well as by a special geometric configuration of the emitter discharge electrodes, thereby filtering (removing) the erosion products stemming from the emitter cathode. The device produces a dc ion flow with energy below 20 eV and current up to 2.5 A onto a collector of 500 cm 2 at 25 cm from the source edge, at a pressure ≥0.02 Pa and gas flow rate ≥14 SCCM. The ion energy spread is 2 to 3 eV (rms). The source is characterized by high reliability, low maintenance, and long lifetime. The beam contains less than 0.1% of metallic ions. The specific electric energy consumption is 400 eV per ion registered at the collector. The source operates with noble gases, nitrogen, oxygen, and hydrocarbons. Utilizing biasing, it can be used for plasma sputtering, etching, and other ion technologies

Controlling An Inverter-Driven Three-Phase Motor

Science.gov (United States)

Dolland, C.

1984-01-01

Control system for three-phase permanent-magnet motor driven by linecommutated inverter uses signals generated by integrating back emf of each phase of motor. High-pass filter network eliminates low-frequency components from control loop while maintaining desired power factor.

Three-Phase Cascaded Multilevel Inverter Using Power Cells With Two Inverter Legs in Series

NARCIS (Netherlands)

Waltrich, G.; Barbi, I.

2010-01-01

In this paper, a modular three-phase multilevel inverter specially suited for electrical drive applications is proposed. Unlike the cascaded H-bridge inverter, this topology is based on power cells connected in cascade using two inverter legs in series. A detailed analysis of the structure and the

Modification of the Highly Conductive PEDOT:PSS Layer for Use in Silver Nanogrid Electrodes for Flexible Inverted Polymer Solar Cells.

Science.gov (United States)

Wang, Jie; Fei, Fei; Luo, Qun; Nie, Shuhong; Wu, Na; Chen, Xiaolian; Su, Wenming; Li, Yuanjie; Ma, Chang-Qi

2017-03-01

Silver nanogrid based flexible transparent electrode is recognized as the most promising alternative to ITO electrode for organic electronics, owing to its low production cost and excellent flexibility. Typically, a highly conductive thin film coating layer, such as highly conductive PEDOT:PSS (HC-PEDOT:PSS) is usually deposited onto the Ag-grid electrode to smooth the surface and to minimize the sheet resistance. In this paper, we found that inverted flexible polymer solar cells with structure of Ag-grid/HC-PEDOT:PSS/ZnO/photoactive layer/MoO 3 /Al generally exhibits strong S-shaped J-V curves, which could be eliminated by light-soaking treatment. Kelvin probe force microscope (KPFM) measurement proved that a large work function (WF) difference (0.70 eV) between HC-PEDOT:PSS and ZnO is the main reason for the formation of S-shape. White light soaking of the Ag-grid/HC-PEDOT:PSS gradually decreased the WF of HC-PEDOT:PSS from 5.10 to 4.60 eV, leading to a reduced WF difference between HC-PEDOT:PSS and ZnO from 0.70 to 0.38 eV. Such a WF difference decrease was believed to be the working mechanism for the light-soaking effect in this flexible device. Based on this finding, the HC-PEDOT:PSS solution was then modified by doping with polyethylenimine (PEI) and aqueous ammonia. The modified PEDOT:PSS film is characteristic of adjusting WF through varying PEI doping concentrations. By using such a modified PEDOT:PSS layer, light-soaking-free flexible inverted polymer solar cell with a power conversion efficiency of 6.58% was achieved for PTB7-Th:PC 71 BM cells. The current work provides a useful guideline for interfacial modification for Ag-grid based flexible electrode.

Topological Design and Modulation Strategy for Buck-Boost Three-Level Inverters

DEFF Research Database (Denmark)

Gao, Feng; Loh, Poh Chiang; Teodorescu, Remus

2009-01-01

To date, designed topologies for dc-ac inversion with both voltage buck and boost capabilities are mainly focused on two-level circuitries with extensions to three-level possibilities left nearly unexplored. Contributing to this area of research, this paper presents the design of a number of viable...... can perform distinct five-level line voltage and three-level phase voltage switching by simply controlling the active switches located in the designed voltage boost section of the circuits. As a cost saving option, one active switch can further be removed from the voltage boost section of the circuits...... buck-boost threelevel inverters that can also support bidirectional power conversion. The proposed front-end circuitry is developed from the C´ ukderived buck-boost two-level inverter, and by using the "alternative phase opposition disposition" modulation scheme, the buck-boost three-level inverters...

Solar Power Station Output Inverter Control Design

Directory of Open Access Journals (Sweden)

J. Bauer

2011-04-01

Full Text Available The photovoltaic applications spreads in these days fast, therefore they also undergo great development. Because the amount of the energy obtained from the panel depends on the surrounding conditions, as intensity of the sun exposure or the temperature of the solar array, the converter must be connected to the panel output. The Solar system equipped with inverter can supply small loads like notebooks, mobile chargers etc. in the places where the supplying network is not present. Or the system can be used as a generator and it shall deliver energy to the supply network. Each type of the application has different requirements on the converter and its control algorithm. But for all of them the one thing is common – the maximal efficiency. The paper focuses on design and simulation of the low power inverter that acts as output part of the whole converter. In the paper the design of the control algorithm of the inverter for both types of inverter application – for islanding mode and for operation on the supply grid – is discussed. Attention is also paid to the design of the output filter that should reduce negative side effects of the converter on the supply network.

Evaluation of a Mobile Phone-Based Microscope for Screening of Schistosoma haematobium Infection in Rural Ghana.

Science.gov (United States)

Bogoch, Isaac I; Koydemir, Hatice C; Tseng, Derek; Ephraim, Richard K D; Duah, Evans; Tee, Joseph; Andrews, Jason R; Ozcan, Aydogan

2017-06-01

AbstractSchistosomiasis affects over 170 million people in Africa. Here we compare a novel, low-cost mobile phone microscope to a conventional light microscope for the label-free diagnosis of Schistosoma haematobium infections in a rural Ghanaian school setting. We tested the performance of our handheld microscope using 60 slides that were randomly chosen from an ongoing epidemiologic study in school-aged children. The mobile phone microscope had a sensitivity of 72.1% (95% confidence interval [CI]: 56.1-84.2), specificity of 100% (95% CI: 75.9-100), positive predictive value of 100% (95% CI: 86.3-100), and a negative predictive value of 57.1% (95% CI: 37.4-75.0). With its modest sensitivity and high specificity, this handheld and cost-effective mobile phone-based microscope is a stepping-stone toward developing a powerful tool in clinical and public health settings where there is limited access to conventional laboratory diagnostic support.

A New Design Method for the Passive Damped LCL and LLCL Filter-Based Single-Phase Grid-Tied Inverter

DEFF Research Database (Denmark)

Wu, Weimin; He, Yuanbin; Tang, Tianhao

2013-01-01

A higher order passive power filter (LLCL filter) for the grid-tied inverter is becoming attractive for industrial applications due to the possibility to reduce the cost of the copper and the magnetic material. However, similar to the conventional LCL filter, the grid-tied inverter is facing...

The CMOS integration of a power inverter

Science.gov (United States)

Mannarino, Eric Francis

Due to their falling costs, the use of renewable energy systems is expanding around the world. These systems require the conversion of DC power into grid-synchronous AC power. Currently, the inverters that carry out this task are built using discrete transistors. TowerJazz Semiconductor Corp. has created a commercial CMOS process that allows for blocking voltages of up to 700 V, effectively removing the barrier to integrating power inverters onto a single chip. This thesis explores this process using two topologies. The first is a cell-based switched-capacitor topology first presented by Ke Zou. The second is a novel topology that explores the advantage of using a bused input-output system, as in digital electronics. Simulations run on both topologies confirm the high-efficiency demonstrated in Zou’s process as well as the advantage the bus-based system has in output voltage levels.

Reliability-Oriented Design and Analysis of Input Capacitors in Single-Phase Transformer-less Photovoltaic Inverters

DEFF Research Database (Denmark)

Wang, Huai; Yang, Yongheng; Blaabjerg, Frede

2013-01-01

While 99% efficiency has been reported, the target of 20 years of service time imposes new challenge to cost-effective solutions for grid-connected photovoltaic (PV) inverters. Aluminum electrolytic capacitors are the weak-link in terms of reliability and lifetime in single-phase PV systems....... A reliability-oriented design guideline is proposed in this paper for the input capacitors in single-phase transformer-less PV inverters. The guideline ensures that the service time requirement is to be accomplished under different power levels and ambient temperature profiles. The theoretical analysis has been...... demonstrated by a 1 kW single-phase PV inverter....

Experimental study of inverted-annular-flow hydrodynamics utilizing an adiabatic simulation

International Nuclear Information System (INIS)

De Jarlais, G.

1983-03-01

In experiments, inverted annular flow was simulated adiabatically with turbulent water jets, issuing downward from long aspect nozzles, enclosed in gas annuli. Velocities, diameters, and gas species were varied, and core jet length, shape, break-up mode, and dispersed-core droplet sizes were recorded at approximately 750 data points. Inverted annular flow was observed to develop into inverted slug flow at low relative velocities, and into dispersed droplet flow at high relative velocities. For both of the above transitions from inverted annular flow, correlations for core jet length were developed by extending work done on free liquid jets to include this new, coaxial, jet disintegration phenomenon. Jet break-up length is correlated as a function of jet diameter, jet Reynolds number, jet Weber number, void fraction, and gas Weber number. Correlations for core shape, break-up mechanisms and dispersed core droplet size for the case of transition to inverted slug flow were developed

Γ-source Neutral Point Clamped Inverter

DEFF Research Database (Denmark)

Mo, Wei; Loh, Poh Chiang; Blaabjerg, Frede

Transformer based Z-source inverters are recently proposed to achieve promising buck-boost capability. They have improved higher buck-boost capability, smaller size and less components count over Z-source inverters. On the other hand, neutral point clamped inverters have less switching stress...... and better output performance comparing with traditional two-level inverters. Integrating these two types of configurations can help neutral point inverters achieve enhanced votlage buck-boost capability....

High Quality Model Predictive Control for Single Phase Grid Connected Photovoltaic Inverters

DEFF Research Database (Denmark)

Zangeneh Bighash, Esmaeil; Sadeghzadeh, Seyed Mohammad; Ebrahimzadeh, Esmaeil

2018-01-01

Single phase grid-connected inverters with LCL filter are widely used to connect the photovoltaic systems to the utility grid. Among the presented control schemes, predictive control methods are faster and more accurate but are more complex to implement. Recently, the model-predictive control...... algorithm for single-phase inverter has been presented, where the algorithm implementation is straightforward. In the proposed approach, all switching states are tested in each switching period to achieve the control objectives. However, since the number of the switching states in single-phase inverter...... is low, the inverter output current has a high total harmonic distortions. In order to reduce the total harmonic distortions of the injected current, this paper presents a high-quality model-predictive control for one of the newest structure of the grid connected photovoltaic inverter, i.e., HERIC...

SEEPAGE/INVERT INTERACTIONS

International Nuclear Information System (INIS)

P.S. Domski

2000-01-01

As directed by a written development plan (CRWMS M andO 1999a), a conceptual model for water entering the drift and reacting with the invert materials is to be developed. The purpose of this conceptual model is to assist Performance Assessment Operations (PAO) and its Engineered Barrier Performance Department in modeling the geochemical environment within a repository drift, thus allowing PAO to provide a more detailed and complete in-drift geochemical model abstraction, and to answer the key technical issues (KTI) raised in the NRC Issue Resolution Status Report (IRSR) for the Evolution of the Near-Field Environment (NFE), Revision 2 (NRC 1999). This AMR also seeks to: (1) Develop a logical conceptual model for physical/chemical interactions between seepage and the invert materials; (2) screen potential processes and reactions that may occur between seepage and invert to evaluate the potential consequences of the interactions; and (3) outline how seepage/invert processes may be quantified. This document provides the conceptual framework for screening out insignificant processes and for identifying and evaluating those seepage/invert interactions that have the potential to be important to subsequent PAO analyses including the Engineered Barrier System (EBS) physical and chemical model abstraction effort. This model has been developed to serve as a basis for the in-drift geochemical analyses performed by PAO. Additionally, the concepts discussed within this report may also apply to certain near and far-field geochemical processes and may have conceptual application within the unsaturated zone (UZ) and saturated zone (SZ) transport modeling efforts. The seepage/invert interactions will not directly affect any principal factors

A Highly Robust Single-Loop Current Control Scheme for Grid-Connected Inverter with an Improved LCCL Filter Configuration

DEFF Research Database (Denmark)

Pan, Donghua; Ruan, Xinbo; Wang, Xiongfei

2018-01-01

Single-loop current control is an attractive scheme for the LCL-type grid-connected inverter due to its simplicity and low cost. However, conventional single-loop control schemes, which command either the inverter current or the grid current, are subject to the specific resonance frequency regions....... The weighted average current control, which splits the filter capacitor into two parts (in form of an LCCL filter) and commands the current flowing between these two parts, is independent of the resonance frequency, but on the other hand, it is limited by the poor sensitivity to the grid impedance variation...... and weak stability in the grid current. These limitations are comprehensively explained in this paper and then addressed by identifying that the single-loop weighted average current control is equivalent to the dual-loop grid current control with an inherent capacitor current active damping. By tuning...

Three-dimensional motion-picture imaging of dynamic object by parallel-phase-shifting digital holographic microscopy using an inverted magnification optical system

Science.gov (United States)

Fukuda, Takahito; Shinomura, Masato; Xia, Peng; Awatsuji, Yasuhiro; Nishio, Kenzo; Matoba, Osamu

2017-04-01

We constructed a parallel-phase-shifting digital holographic microscopy (PPSDHM) system using an inverted magnification optical system, and succeeded in three-dimensional (3D) motion-picture imaging for 3D displacement of a microscopic object. In the PPSDHM system, the inverted and afocal magnification optical system consisted of a microscope objective (16.56 mm focal length and 0.25 numerical aperture) and a convex lens (300 mm focal length and 82 mm aperture diameter). A polarization-imaging camera was used to record multiple phase-shifted holograms with a single-shot exposure. We recorded an alum crystal, sinking down in aqueous solution of alum, by the constructed PPSDHM system at 60 frames/s for about 20 s and reconstructed high-quality 3D motion-picture image of the crystal. Then, we calculated amounts of displacement of the crystal from the amounts in the focus plane and the magnifications of the magnification optical system, and obtained the 3D trajectory of the crystal by that amounts.

Modeling and control of LCL-filtered grid-tied inverters with wide inductance variation

DEFF Research Database (Denmark)

Xie, Chuan; Li, Kai; Zhang, Gang

2017-01-01

with the changing of the inductor current in one cycle of the grid, which challenges the system stability and power quality. In this paper, the current-dependent small-signal model of a three-phase LCL-filtered inverter is derived for designing the corresponding controller. Based on the developed small-signal model......Because of the low power losses and moderate cost, the magnetic powder cores are popular in producing the filtering inductors for the high efficient and cost-effective power converters. However, the soft magnetic property of the powder cores leads to the wide variation of inductance along......, a capacitor current feedback based active damping loop and a fractional order repetitive control based compound current control loop are designed to stabilize the system and enhance the control accuracy in steady-state, respectively. The controller design procedure is given in detail. Finally, all...

Low energy, low cost, efficient CO{sub 2} capture

Energy Technology Data Exchange (ETDEWEB)

Michael C. Trachtenberg; Lihong Bao; David A. Smith; Remy Dumortier [Carbozyme, Inc., Monmouth Junction, NJ (United States)

2006-07-01

This paper discusses the development and some characteristics of a new, enzyme-based, contained liquid membrane contactor to capture CO{sub 2}. The enzyme carbonic anhydrase catalyzes the removal of CO{sub 2} while the membrane contactor increases the surface area to allow the reduction of the size of the system. The modular system design is easily scaled to any required size reducing the investment costs. The system captures CO{sub 2} at a low energy and low cost promising to be a cost effective technology for CO{sub 2} capture. 5 refs., 7 figs.

Filter optimization of Si and SiC semiconductor-based H5 and Conergy-NPC transformerless PV inverters

DEFF Research Database (Denmark)

Saridakis, Stefanos; Koutroulis, Eftichios; Blaabjerg, Frede

2013-01-01

Single-phase transformerless Photovoltaic (PV) inverters are synthesized by combining available solutions in terms of the power section topology, power semiconductors manufacturing technology and structure of the output filter. A design method is presented in this paper for optimizing the power......C-based PV inverters will inject more energy into the electric grid, compared to the Si-based structures and enable the reduction of the output filter size, weight and cost. Employing an LLCL-type output filter and simultaneously reducing the cost of SiC power semiconductors to the level of their Si...

Inverter communications using output signal

Science.gov (United States)

Chapman, Patrick L.

2017-02-07

Technologies for communicating information from an inverter configured for the conversion of direct current (DC) power generated from an alternative source to alternating current (AC) power are disclosed. The technologies include determining information to be transmitted from the inverter over a power line cable connected to the inverter and controlling the operation of an output converter of the inverter as a function of the information to be transmitted to cause the output converter to generate an output waveform having the information modulated thereon.

A cryogen-free low temperature scanning tunneling microscope capable of inelastic electron tunneling spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Zhang, Shuai; Huang, Di [State Key Laboratory of Surface Physics, Key Laboratory of Micro and Nano Photonic Structures (MOE), and Department of Physics, Fudan University, Shanghai 200433 (China); Wu, Shiwei, E-mail: swwu@fudan.edu.cn [State Key Laboratory of Surface Physics, Key Laboratory of Micro and Nano Photonic Structures (MOE), and Department of Physics, Fudan University, Shanghai 200433 (China); Collaborative Innovation Center of Advanced Microstructures, Fudan University, Shanghai 200433 (China)

2016-06-15

The design and performance of a cryogen-free low temperature scanning tunneling microscope (STM) housed in ultrahigh vacuum (UHV) are reported. The cryogen-free design was done by directly integrating a Gifford-McMahon cycle cryocooler to a Besocke-type STM, and the vibration isolation was achieved by using a two-stage rubber bellow between the cryocooler and a UHV-STM interface with helium exchange gas cooling. A base temperature of 15 K at the STM was achieved, with a possibility to further decrease by using a cryocooler with higher cooling power and adding additional low temperature stage under the exchange gas interface. Atomically sharp STM images and high resolution dI/dV spectra on various samples were demonstrated. Furthermore, we reported the inelastic tunneling spectroscopy on a single carbon monoxide molecule adsorbed on Ag(110) surface with a cryogen-free STM for the first time. Being totally cryogen-free, the system not only saves the running cost significantly but also enables uninterrupted data acquisitions and variable temperature measurements with much ease. In addition, the system is capable of coupling light to the STM junction by a pair of lens inside the UHV chamber. We expect that these enhanced capabilities could further broaden our views to the atomic-scale world.

A cryogen-free low temperature scanning tunneling microscope capable of inelastic electron tunneling spectroscopy.

Science.gov (United States)

Zhang, Shuai; Huang, Di; Wu, Shiwei

2016-06-01

The design and performance of a cryogen-free low temperature scanning tunneling microscope (STM) housed in ultrahigh vacuum (UHV) are reported. The cryogen-free design was done by directly integrating a Gifford-McMahon cycle cryocooler to a Besocke-type STM, and the vibration isolation was achieved by using a two-stage rubber bellow between the cryocooler and a UHV-STM interface with helium exchange gas cooling. A base temperature of 15 K at the STM was achieved, with a possibility to further decrease by using a cryocooler with higher cooling power and adding additional low temperature stage under the exchange gas interface. Atomically sharp STM images and high resolution dI/dV spectra on various samples were demonstrated. Furthermore, we reported the inelastic tunneling spectroscopy on a single carbon monoxide molecule adsorbed on Ag(110) surface with a cryogen-free STM for the first time. Being totally cryogen-free, the system not only saves the running cost significantly but also enables uninterrupted data acquisitions and variable temperature measurements with much ease. In addition, the system is capable of coupling light to the STM junction by a pair of lens inside the UHV chamber. We expect that these enhanced capabilities could further broaden our views to the atomic-scale world.

High Resolution Higher Energy X-ray Microscope for Mesoscopic Materials

International Nuclear Information System (INIS)

Snigireva, I; Snigirev, A

2013-01-01

We developed a novel X-ray microscopy technique to study mesoscopically structured materials, employing compound refractive lenses. The easily seen advantage of lens-based methodology is the possibility to retrieve high resolution diffraction pattern and real-space images in the same experimental setup. Methodologically the proposed approach is similar to the studies of crystals by high resolution transmission electron microscopy. The proposed microscope was applied for studying of mesoscopic materials such as natural and synthetic opals, inverted photonic crystals

40 khz/40 kVA ZVS resonant inverter for 750 keV DC accelerator

International Nuclear Information System (INIS)

Kasliwal, Apollo; Tripathi, Alok; Pandit, T.G.; Banwari, R.; Kotaiah, S.

2003-01-01

This paper presents the analysis and design of a high order Leucal resonant inverter for application in the 750 keV DC Accelerator machine being commissioned at CAT, Indore. High frequency resonant inverters are replacing the conventional Pm counterparts due to high efficiency, reduced size, weight and cost. The operating characteristics and analysis of series resonant (SRC), parallel resonant (PRC) and series parallel (SPRC) resonant converters have been reported for fixed frequency operation. It has been shown that SPRC takes the advantage of both SRC and PRC curtailing their disadvantages. The inverter configuration used has boost characteristics (capacitive voltage multiplication) with High Frequency Transformer isolation and is suitable for DC to DC high voltage application. (author)

Design of High Efficient MPPT Solar Inverter

Directory of Open Access Journals (Sweden)

Sunitha K. A.

2017-01-01

Full Text Available This work aims to design a High Efficient Maximum Power Point Tracking (MPPT Solar Inverter. A boost converter is designed in the system to boost the power from the photovoltaic panel. By this experimental setup a room consisting of 500 Watts load (eight fluorescent tubes is completely controlled. It is aimed to decrease the maintenance cost. A microcontroller is introduced for tracking the P&O (Perturb and Observe algorithm used for tracking the maximum power point. The duty cycle for the operation of the boost convertor is optimally adjusted by using MPPT controller. There is a MPPT charge controller to charge the battery as well as fed to inverter which runs the load. Both the P&O scheme with the fixed variation for the reference current and the intelligent MPPT algorithm were able to identify the global Maximum power point, however the performance of the MPPT algorithm was better.

Resonant snubber inverter

Science.gov (United States)

Lai, Jih-Sheng; Young, Sr., Robert W.; Chen, Daoshen; Scudiere, Matthew B.; Ott, Jr., George W.; White, Clifford P.; McKeever, John W.

1997-01-01

A resonant, snubber-based, soft switching, inverter circuit achieves lossless switching during dc-to-ac power conversion and power conditioning with minimum component count and size. Current is supplied to the resonant snubber branches solely by the main inverter switches. Component count and size are reduced by use of a single semiconductor switch in the resonant snubber branches. Component count is also reduced by maximizing the use of stray capacitances of the main switches as parallel resonant capacitors. Resonance charging and discharging of the parallel capacitances allows lossless, zero voltage switching. In one embodiment, circuit component size and count are minimized while achieving lossless, zero voltage switching within a three-phase inverter.

Power losses in bilayer inverted small molecule organic solar cells

KAUST Repository

Trinh, Cong

2012-01-01

Inverted bilayer organic solar cells using copper phthalocyanine (CuPc) as a donor and C60 as an acceptor with the structure: glass/indium tin oxide (ITO)/ZnO/C60/CuPc/MoO3/Al, in which the zinc oxide (ZnO) was deposited by atomic layer deposition, are compared with a conventional device: glass/ITO/CuPc/C60/bathocuproine/Al. These inverted and conventional devices give short circuit currents of 3.7 and 4.8 mA/cm 2, respectively. However, the inverted device gives a reduced photoresponse from the CuPc donor compared to that of the conventional device. Optical field models show that the arrangement of organic layers in the inverted devices leads to lower absorption of long wavelengths by the CuPc donor; the low energy portion of the spectrum is concentrated near the metal oxide electrode in both devices. © 2012 American Institute of Physics.

Superconducting phonon spectroscopy using a low-temperature scanning tunneling microscope

Science.gov (United States)

Leduc, H. G.; Kaiser, W. J.; Hunt, B. D.; Bell, L. D.; Jaklevic, R. C.

1989-01-01

The low-temperature scanning tunneling microscope (STM) system described by LeDuc et al. (1987) was used to observe the phonon density of states effects in a superconductor. Using techniques based on those employed in macroscopic tunneling spectroscopy, electron tunneling current-voltage (I-V) spectra were measured for NbN and Pb, and dI/dV vs V spectra were measured using standard analog derivative techniques. I-V measurements on NbN and Pb samples under typical STM conditions showed no evidence for multiparticle tunneling effects.

A hybrid scanning force and light microscope for surface imaging and three-dimensional optical sectioning in differential interference contrast.

Science.gov (United States)

Stemmer, A

1995-04-01

The design of a scanned-cantilever-type force microscope is presented which is fully integrated into an inverted high-resolution video-enhanced light microscope. This set-up allows us to acquire thin optical sections in differential interference contrast (DIC) or polarization while the force microscope is in place. Such a hybrid microscope provides a unique platform to study how cell surface properties determine, or are affected by, the three-dimensional dynamic organization inside the living cell. The hybrid microscope presented in this paper has proven reliable and versatile for biological applications. It is the only instrument that can image a specimen by force microscopy and high-power DIC without having either to translate the specimen or to remove the force microscope. Adaptation of the design features could greatly enhance the suitability of other force microscopes for biological work.

Analysis and Modeling of Circulating Current in Two Parallel-Connected Inverters

DEFF Research Database (Denmark)

Maheshwari, Ram Krishan; Gohil, Ghanshyamsinh Vijaysinh; Bede, Lorand

2015-01-01

Parallel-connected inverters are gaining attention for high power applications because of the limited power handling capability of the power modules. Moreover, the parallel-connected inverters may have low total harmonic distortion of the ac current if they are operated with the interleaved pulse...... this model, the circulating current between two parallel-connected inverters is analysed in this study. The peak and root mean square (rms) values of the normalised circulating current are calculated for different PWM methods, which makes this analysis a valuable tool to design a filter for the circulating......-width modulation (PWM). However, the interleaved PWM causes a circulating current between the inverters, which in turn causes additional losses. A model describing the dynamics of the circulating current is presented in this study which shows that the circulating current depends on the common-mode voltage. Using...

Next Generation Inverter

Energy Technology Data Exchange (ETDEWEB)

Zhao, Zilai [General Motors LLC, Detroit, MI (United States); Gough, Charles [General Motors LLC, Detroit, MI (United States)

2016-04-22

The goal of this Cooperative Agreement was the development of a Next Generation Inverter for General Motors’ electrified vehicles, including battery electric vehicles, range extended electric vehicles, plug-in hybrid electric vehicles and hybrid electric vehicles. The inverter is a critical electronics component that converts battery power (DC) to and from the electric power for the motor (AC).

Low-cost carriers fare competition effect

NARCIS (Netherlands)

Carmona Benitez, R.B.; Lodewijks, G.

2010-01-01

This paper examines the effects that low-cost carriers (LCC’s) produce when entering new routes operated only by full-service carriers (FSC’s) and routes operated by low-cost carriers in competition with full-service carriers. A mathematical model has been developed to determine what routes should

Inverting the Linear Algebra Classroom

Science.gov (United States)

Talbert, Robert

2014-01-01

The inverted classroom is a course design model in which students' initial contact with new information takes place outside of class meetings, and students spend class time on high-level sense-making activities. The inverted classroom model is so called because it inverts or "flips" the usual classroom design where typically class…

Low-Cost Spectral Sensor Development Description.

Energy Technology Data Exchange (ETDEWEB)

Armijo, Kenneth Miguel; Yellowhair, Julius

2014-11-01

Solar spectral data for all parts of the US is limited due in part to the high cost of commercial spectrometers. Solar spectral information is necessary for accurate photovoltaic (PV) performance forecasting, especially for large utility-scale PV installations. A low-cost solar spectral sensor would address the obstacles and needs. In this report, a novel low-cost, discrete- band sensor device, comprised of five narrow-band sensors, is described. The hardware is comprised of commercial-off-the-shelf components to keep the cost low. Data processing algorithms were developed and are being refined for robustness. PV module short-circuit current ( I sc ) prediction methods were developed based on interaction-terms regression methodology and spectrum reconstruction methodology for computing I sc . The results suggest the computed spectrum using the reconstruction method agreed well with the measured spectrum from the wide-band spectrometer (RMS error of 38.2 W/m 2 -nm). Further analysis of computed I sc found a close correspondence of 0.05 A RMS error. The goal is for ubiquitous adoption of the low-cost spectral sensor in solar PV and other applications such as weather forecasting.

Effect of Asymmetric Layout of IGBT Modules on Reliability of Power Inverters in Motor Drive System

DEFF Research Database (Denmark)

Choi, Uimin; Vernica, Ionut; Blaabjerg, Frede

2018-01-01

An IGBT module has typically multiple power devices for some technical and cost advantages. This kind of configurations could have an asymmetric layout, which may lead to different thermal loadings and thereby lifetime difference of the power devices. Therefore, both the power rating and lifetime...... of inverters are limited by the most stressed devices. However, generally common data is provided for all devices and this may cause improper design of the inverters in terms of power rating and lifetime. In this paper, the effect of an asymmetric layout of IGBT modules on the reliability of power inverters...

Effective switching frequency multiplier inverter

Science.gov (United States)

Su, Gui-Jia [Oak Ridge, TN; Peng, Fang Z [Okemos, MI

2007-08-07

A switching frequency multiplier inverter for low inductance machines that uses parallel connection of switches and each switch is independently controlled according to a pulse width modulation scheme. The effective switching frequency is multiplied by the number of switches connected in parallel while each individual switch operates within its limit of switching frequency. This technique can also be used for other power converters such as DC/DC, AC/DC converters.

Smart Inverter Control and Operation for Distributed Energy Resources

Science.gov (United States)

Tazay, Ahmad F.

The motivation of this research is to carry out the control and operation of smart inverters and voltage source converters (VSC) for distributed energy resources (DERs) such as photovoltaic (PV), battery, and plug-in hybrid electric vehicles (PHEV). The main contribution of the research includes solving a couple of issues for smart grids by controlling and implementing multifunctions of VSC and smart inverter as well as improving the operational scheme of the microgrid. The work is mainly focused on controlling and operating of smart inverter since it promises a new technology for the future microgrid. Two major applications of the smart inverter will be investigated in this work based on the connection modes: microgrid at grid-tied mode and autonomous mode. In grid-tied connection, the smart inverter and VSC are used to integrate DER such as Photovoltaic (PV) and battery to provide suitable power to the system by controlling the supplied real and reactive power. The role of a smart inverter at autonomous mode includes supplying a sufficient voltage and frequency, mitigate abnormal condition of the load as well as equally sharing the total load's power. However, the operational control of the microgrid still has a major issue on the operation of the microgrid. The dissertation is divided into two main sections which are: 1. Low-level control of a single smart Inverter. 2. High-level control of the microgrid. The first part investigates a comprehensive research for a smart inverter and VSC technology at the two major connections of the microgrid. This involves controlling and modeling single smart inverter and VSC to solve specific issues of microgrid as well as improve the operation of the system. The research provides developed features for smart inverter comparing with a conventional voltage sourced converter (VSC). The two main connections for a microgrid have been deeply investigated to analyze a better way to develop and improve the operational procedure of

Experimental Evaluation of PV Inverter Anti-Islanding with Grid Support Functions in Multi-Inverter Island Scenarios

Energy Technology Data Exchange (ETDEWEB)

Hoke, Anderson [National Renewable Energy Lab. (NREL), Golden, CO (United States); Nelson, Austin [National Renewable Energy Lab. (NREL), Golden, CO (United States); Miller, Brian [National Renewable Energy Lab. (NREL), Golden, CO (United States); Chakraborty, Sudipta [National Renewable Energy Lab. (NREL), Golden, CO (United States); Bell, Frances [SolarCity, San Mateo, CA (United States); McCarty, Michael [SolarCity, San Mateo, CA (United States)

2016-07-01

As PV and other DER systems are connected to the grid at increased penetration levels, island detection may become more challenging for two reasons: 1.) In islands containing many DERs, active inverter-based anti-islanding methods may have more difficulty detecting islands because each individual inverter's efforts to detect the island may be interfered with by the other inverters in the island. 2.) The increasing numbers of DERs are leading to new requirements that DERs ride through grid disturbances and even actively try to regulate grid voltage and frequency back towards nominal operating conditions. These new grid support requirements may directly or indirectly interfere with anti-islanding controls. This report describes a series of tests designed to examine the impacts of both grid support functions and multi-inverter islands on anti-islanding effectiveness. Crucially, the multi-inverter anti-islanding tests described in this report examine scenarios with multiple inverters connected to multiple different points on the grid. While this so-called 'solar subdivision' scenario has been examined to some extent through simulation, this is the first known work to test it using hardware inverters. This was accomplished through the use of power hardware-in-the-loop (PHIL) simulation, which allows the hardware inverters to be connected to a real-time transient simulation of an electric power system that can be easily reconfigured to test various distribution circuit scenarios. The anti-islanding test design was a modified version of the unintentional islanding test in IEEE Standard 1547.1, which creates a balanced, resonant island with the intent of creating a highly challenging condition for island detection. Three common, commercially available single-phase PV inverters from three different manufacturers were tested. The first part of this work examined each inverter individually using a series of pure hardware resistive-inductive-capacitive (RLC

Lagrangian 3D tracking of fluorescent microscopic objects in motion

OpenAIRE

Darnige, T.; Figueroa-Morales, N.; Bohec, P.; Lindner, A.; Clément, E.

2016-01-01

We describe the development of a tracking device, mounted on an epi-fluorescent inverted microscope, suited to obtain time resolved 3D Lagrangian tracks of fluorescent passive or active micro-objects in micro-fluidic devices. The system is based on real-time image processing, determining the displacement of a x,y mechanical stage to keep the chosen object at a fixed position in the observation frame. The z displacement is based on the refocusing of the fluorescent object determining the displ...

A design for a subminiature, low energy scanning electron microscope with atomic resolution

International Nuclear Information System (INIS)

Eastham, D. A.; Edmondson, P.; Greene, S.; Donnelly, S.; Olsson, E.; Svensson, K.; Bleloch, A.

2009-01-01

We describe a type of scanning electron microscope that works by directly imaging the electron field-emission sites on a nanotip. Electrons are extracted from the nanotip through a nanoscale aperture, accelerated in a high electric field, and focused to a spot using a microscale Einzel lens. If the whole microscope (accelerating section and lens) and the focal length are both restricted in size to below 10 μm, then computer simulations show that the effects of aberration are extremely small and it is possible to have a system with approximately unit magnification at electron energies as low as 300 eV. Thus a typical emission site of 1 nm diameter will produce an image of the same size, and an atomic emission site will give a resolution of 0.1-0.2 nm (1-2 A). Also, because the beam is not allowed to expand beyond 100 nm in diameter, the depth of field is large and the contribution to the beam spot size from chromatic aberrations is less than 0.02 nm (0.2 A) for 500 eV electrons. Since it is now entirely possible to make stable atomic sized emitters (nanopyramids), it is expected that this instrument will have atomic resolution. Furthermore the brightness of the beam is determined only by the field emission and can be up to 1x10 6 times larger than in a typical (high energy) electron microscope. The advantages of this low energy, bright-beam electron microscope with atomic resolution are described and include the possibility of it being used to rapidly sequence the human genome from a single strand of DNA as well as being able to identify atomic species directly from the elastic scattering of electrons

Inverter-based successive approximation capacitance-to-digital converter

KAUST Repository

Omran, Hesham

2017-03-23

An energy-efficient capacitance-to-digital converter (CDC) is provided that utilizes a capacitance-domain successive approximation (SAR) technique. Unlike SAR analog- to-digital converters (ADCs), analysis shows that for SAR CDCs, the comparator offset voltage will result in signal-dependent and parasitic-dependent conversion errors, which necessitates an op-amp-based implementation. The inverter-based SAR CDC contemplated herein provides robust, energy-efficient, and fast operation. The inverter- based SAR CDC may include a hybrid coarse-fine programmable capacitor array. The design of example embodiments is insensitive to analog references, and thus achieves very low temperature sensitivity without the need for calibration. Moreover, this design achieves improved energy efficiency.

Present status of the microscopic study of low-lying collective states in spherical and transitional nuclei

International Nuclear Information System (INIS)

Marumori, Toshio; Takada, Kenjiro; Sakata, Fumihiko.

1981-12-01

The history and the present status of the microscopic study of the low-lying collective excited states in spherical and transitional nuclei are discussed by putting emphasis on explaining the rather modern microscopic investigations of the concept of collective subspace. Importance of the dynamical interplay between the pairing and the quadrupole correlations is emphasized as a crucial element to mediate coupling between the collective and non-collective subspace. (author)

Strategies to fight low-cost rivals.

Science.gov (United States)

Kumar, Nirmalya

2006-12-01

Companies find it challenging and yet strangely reassuring to take on opponents whose strategies, strengths, and weaknesses resemble their own. Their obsession with familiar rivals, however, has blinded them to threats from disruptive, low-cost competitors. Successful price warriors, such as the German retailer Aldi, are changing the nature of competition by employing several tactics: focusing on just one or a few consumer segments, delivering the basic product or providing one benefit better than rivals do, and backing low prices with superefficient operations. Ignoring cutprice rivals is a mistake because they eventually force companies to vacate entire market segments. Price wars are not the answer, either: Slashing prices usually lowers profits for incumbents without driving the low-cost entrants out of business. Companies take various approaches to competing against cut-price players. Some differentiate their products--a strategy that works only in certain circumstances. Others launch low-cost businesses of their own, as many airlines did in the 1990s--a so-called dual strategy that succeeds only if companies can generate synergies between the existing businesses and the new ventures, as the financial service providers HSBC and ING did. Without synergies, corporations are better off trying to transform themselves into low-cost players, a difficult feat that Ryanair accomplished in the 1990s, or into solution providers. There will always be room for both low-cost and value-added players. How much room each will have depends not only on the industry and customers' preferences, but also on the strategies traditional businesses deploy.

low-cost apparatus from locally available materials for teaching

African Journals Online (AJOL)

unesco

twofold: i) to design and produce appropriate low cost apparatus from locally .... How are the low-cost and manufactured apparatus compared in terms of cost and efficiency? ... BASIC TOOLS FOR THE LOW COST APPARATUS PRODUCTION.

A single-phase multi-level D-STATCOM inverter using modular multi-level converter (MMC) topology for renewable energy sources

Science.gov (United States)

Sotoodeh, Pedram

This dissertation presents the design of a novel multi-level inverter with FACTS capability for small to mid-size (10-20kW) permanent-magnet wind installations using modular multi-level converter (MMC) topology. The aim of the work is to design a new type of inverter with D-STATCOM option to provide utilities with more control on active and reactive power transfer of distribution lines. The inverter is placed between the renewable energy source, specifically a wind turbine, and the distribution grid in order to fix the power factor of the grid at a target value, regardless of wind speed, by regulating active and reactive power required by the grid. The inverter is capable of controlling active and reactive power by controlling the phase angle and modulation index, respectively. The unique contribution of the proposed work is to combine the two concepts of inverter and D-STATCOM using a novel voltage source converter (VSC) multi-level topology in a single unit without additional cost. Simulations of the proposed inverter, with 5 and 11 levels, have been conducted in MATLAB/Simulink for two systems including 20 kW/kVAR and 250 W/VAR. To validate the simulation results, a scaled version (250 kW/kVAR) of the proposed inverter with 5 and 11 levels has been built and tested in the laboratory. Experimental results show that the reduced-scale 5- and 11-level inverter is able to fix PF of the grid as well as being compatible with IEEE standards. Furthermore, total cost of the prototype models, which is one of the major objectives of this research, is comparable with market prices.

An Improved Fuzzy Logic Controller Design for PV Inverters Utilizing Differential Search Optimization

Directory of Open Access Journals (Sweden)

Ammar Hussein Mutlag

2014-01-01

Full Text Available This paper presents an adaptive fuzzy logic controller (FLC design technique for photovoltaic (PV inverters using differential search algorithm (DSA. This technique avoids the exhaustive traditional trial and error procedure in obtaining membership functions (MFs used in conventional FLCs. This technique is implemented during the inverter design phase by generating adaptive MFs based on the evaluation results of the objective function formulated by the DSA. In this work, the mean square error (MSE of the inverter output voltage is used as an objective function. The DSA optimizes the MFs such that the inverter provides the lowest MSE for output voltage and improves the performance of the PV inverter output in terms of amplitude and frequency. The design procedure and accuracy of the optimum FLC are illustrated and investigated using simulations conducted for a 3 kW three-phase inverter in a MATLAB/Simulink environment. Results show that the proposed controller can successfully obtain the desired output when different linear and nonlinear loads are connected to the system. Furthermore, the inverter has reasonably low steady state error and fast response to reference variation.

Reliable inverter systems

Science.gov (United States)

Nagano, S.

1979-01-01

Base driver with common-load-current feedback protects paralleled inverter systems from open or short circuits. Circuit eliminates total system oscillation that can occur in conventional inverters because of open circuit in primary transformer winding. Common feedback signal produced by functioning modules forces operating frequency of failed module to coincide with clock drive so module resumes normal operating frequency in spite of open circuit.

Design and development of compact multiphoton microscopes

Science.gov (United States)

Mehravar, SeyedSoroush

A compact multi-photon microscope (MPM) was designed and developed with the use of low-cost mode-locked fiber lasers operating at 1040nm and 1560nm. The MPM was assembled in-house and the system aberration was investigated using the optical design software: Zemax. A novel characterization methodology based on 'nonlinear knife-edge' technique was also introduced to measure the axial, lateral resolution, and the field curvature of the multi-photon microscope's image plane. The field curvature was then post-corrected using data processing in MATLAB. A customized laser scanning software based on LabVIEW was developed for data acquisition, image display and controlling peripheral electronics. Finally, different modalities of multi-photon excitation such as second- and third harmonic generation, two- and three-photon fluorescence were utilized to study a wide variety of samples from cancerous cells to 2D-layered materials.

Closed-looped in situ nano processing on a culturing cell using an inverted electron beam lithography system

International Nuclear Information System (INIS)

Hoshino, Takayuki; Mabuchi, Kunihiko

2013-01-01

Highlights: ► An electron beam lithography (EBL) was used as an in situ nano processing for a living cell. ► A synchronized optics was containing an inverted EBL and an optical microscope. ► This system visualized real-time images of the EB-induced nano processing. ► We demonstrated the nano processing for a culturing cell with 200–300 nm resolution. ► Our system would be able to provide high resolution display of virtual environments. -- Abstract: The beam profile of an electron beam (EB) can be focused onto less than a nanometer spot and scanned over a wide field with extremely high speed sweeping. Thus, EB is employed for nano scale lithography in applied physics research studies and in fabrication of semiconductors. We applied a scanning EB as a control system for a living cell membrane which is representative of large scale complex systems containing nanometer size components. First, we designed the opposed co-axial dual optics containing inverted electron beam lithography (I-EBL) system and a fluorescent optical microscope. This system could provide in situ nano processing for a culturing living cell on a 100-nm-thick SiN nanomembrane, which was placed between the I-EBL and the fluorescent optical microscope. Then we demonstrated the EB-induced chemical direct nano processing for a culturing cell with hundreds of nanometer resolution and visualized real-time images of the scanning spot of the EB-induced luminescent emission and chemical processing using a high sensitive camera mounted on the optical microscope. We concluded that our closed-loop in situ nano processing would be able to provide a nanometer resolution display of virtual molecule environments to study functional changes of bio-molecule systems

Addressable inverter matrix for process and device characterization

Science.gov (United States)

Buehler, M. G.; Sayah, H. R.

1985-01-01

The addressable inverter matrix consists of 222 inverters each accessible with the aid of a shift register. The structure has proven useful in characterizing the variability of inverter transfer curves and in diagnosing processing faults. For good 3-micron CMOS bulk inverters investigated, the percent standard deviation of the inverter threshold voltage was less than one percent and the inverter gain (the slope of the inverter transfer curve at the inverter threshold vltage) was less than 3 percent. The average noise margin for the inverters was near 2 volts for a power supply voltage of 5 volts. The specific faults studied included undersize pull-down transistor widths and various open contacts in the matrix.

Recent Advances in the Inverted Planar Structure of Perovskite Solar Cells.

Science.gov (United States)

Meng, Lei; You, Jingbi; Guo, Tzung-Fang; Yang, Yang

2016-01-19

Inorganic-organic hybrid perovskite solar cells research could be traced back to 2009, and initially showed 3.8% efficiency. After 6 years of efforts, the efficiency has been pushed to 20.1%. The pace of development was much faster than that of any type of solar cell technology. In addition to high efficiency, the device fabrication is a low-cost solution process. Due to these advantages, a large number of scientists have been immersed into this promising area. In the past 6 years, much of the research on perovskite solar cells has been focused on planar and mesoporous device structures employing an n-type TiO2 layer as the bottom electron transport layer. These architectures have achieved champion device efficiencies. However, they still possess unwanted features. Mesoporous structures require a high temperature (>450 °C) sintering process for the TiO2 scaffold, which will increase the cost and also not be compatible with flexible substrates. While the planar structures based on TiO2 (regular structure) usually suffer from a large degree of J-V hysteresis. Recently, another emerging structure, referred to as an "inverted" planar device structure (i.e., p-i-n), uses p-type and n-type materials as bottom and top charge transport layers, respectively. This structure derived from organic solar cells, and the charge transport layers used in organic photovoltaics were successfully transferred into perovskite solar cells. The p-i-n structure of perovskite solar cells has shown efficiencies as high as 18%, lower temperature processing, flexibility, and, furthermore, negligible J-V hysteresis effects. In this Account, we will provide a comprehensive comparison of the mesoporous and planar structures, and also the regular and inverted of planar structures. Later, we will focus the discussion on the development of the inverted planar structure of perovskite solar cells, including film growth, band alignment, stability, and hysteresis. In the film growth part, several

Inverter design for high frequency power distribution

Science.gov (United States)

King, R. J.

1985-01-01

A class of simple resonantly commutated inverters are investigated for use in a high power (100 KW - 1000 KW) high frequency (10 KHz - 20 KHz) AC power distribution system. The Mapham inverter is found to provide a unique combination of large thyristor turn-off angle and good utilization factor, much better than an alternate 'current-fed' inverter. The effects of loading the Mapham inverter entirely with rectifier loads are investigated by simulation and with an experimental 3 KW 20 KHz inverter. This inverter is found to be well suited to a power system with heavy rectifier loading.

Low Cost Benefit Suggestions.

Science.gov (United States)

Doyel, Hoyt W.; McMillan, John D.

1980-01-01

Outlines eight low-cost employee benefits and summarizes their relative advantages. The eight include a stock ownership program, a sick leave pool, flexible working hours, production incentives, and group purchase plans. (IRT)

Pursuing Photovoltaic Cost-Effectiveness

DEFF Research Database (Denmark)

Yang, Yongheng; Koutroulis, Eftichios; Sangwongwanich, Ariya

2017-01-01

loading of the power devices. However, its feasibility is challenged by the associated energy losses. An increase of the inverter lifetime and a reduction of the energy yield can alter the cost of energy, demanding an optimization of the power limitation. Therefore, aiming at minimizing the Levelized Cost...... be flexibly performed. As an advanced control strategy, the Absolute Active Power Control (AAPC) can effectively solve the overloading issues by limiting the maximum possible PV power to a certain level (i.e., the power limitation), and also benefit the inverter reliability due to the reduction in the thermal...... performance in terms of LCOE and energy production can be obtained by enabling the AAPC strategy, compared to the conventional PV inverter operating only in the maximum power point tracking mode. In the presented case study, the minimum of the LCOE is achieved for the PV system when the power limit...

Low Cost, Low Power, High Sensitivity Magnetometer

Science.gov (United States)

2008-12-01

which are used to measure the small magnetic signals from brain. Other types of vector magnetometers are fluxgate , coil based, and magnetoresistance...concentrator with the magnetometer currently used in Army multimodal sensor systems, the Brown fluxgate . One sees the MEMS fluxgate magnetometer is...Guedes, A.; et al., 2008: Hybrid - LOW COST, LOW POWER, HIGH SENSITIVITY MAGNETOMETER A.S. Edelstein*, James E. Burnette, Greg A. Fischer, M.G

Gas cooled traction drive inverter

Science.gov (United States)

Chinthavali, Madhu Sudhan

2013-10-08

The present invention provides a modular circuit card configuration for distributing heat among a plurality of circuit cards. Each circuit card includes a housing adapted to dissipate heat in response to gas flow over the housing. In one aspect, a gas-cooled inverter includes a plurality of inverter circuit cards, and a plurality of circuit card housings, each of which encloses one of the plurality of inverter cards.

Embedded EZ-Source Inverters

DEFF Research Database (Denmark)

Chiang Loh, Poh; Gao, Feng; Blaabjerg, Frede

2010-01-01

overvoltage oscillations to the system. Therefore, Z-source inverters are, in effect, safer and less complex and can be implemented using only passive elements with no additional active semiconductor needed. Believing in the prospects of Z-source inverters, this paper contributes by introducing a new family...

Low voltage ride-through capability control for single-stage inverter-based grid-connected photovoltaic power plant

DEFF Research Database (Denmark)

Al-Shetwi, Ali Q.; Sujod, Muhamad Zahim; Blaabjerg, Frede

2018-01-01

to enhance the LVRT capability based on the Malaysian standards and modern grid codes connection requirements. The proposed control overcomes the problems of dc-link over-voltage and ac over-current that may cause disconnection or damage to the inverter. For this purpose, dc-chopper brake controller...... to improve the capability of ride-through fault safely and keep the inverter connected, but also to provide grid support through active and reactive power control at different type of faults....

Cost-effectiveness analysis of endoscopic tympanoplasty versus microscopic tympanoplasty for chronic otitis media in Taiwan.

Science.gov (United States)

Tseng, Chih-Chieh; Lai, Ming-Tang; Wu, Chia-Che; Yuan, Sheng-Po; Ding, Yi-Fang

2018-03-01

Health care systems and physicians need to conform to budgets and streamline resources to provide cost-effective quality care. Although endoscopic tympanoplasty (ET) has been performed for decades, no studies on the cost-effectiveness of ET and microscopic tympanoplasty (MT) for treating chronic otitis media have been published. The present study aimed to compare the cost-effectiveness of ET and MT for treating chronic otitis media. This study was performed using a Cohort-style Markov decision-tree economic model with a 30-year time horizon. The economic perspective was that of a third-party payer (Taiwan National Health Insurance System). Two treatment strategies were compared, namely ET and MT. The primary outcome was the incremental cost per quality-adjusted life year (QALY). Probabilities were obtained from meta-analyses. Costs were obtained from the published literature and Taiwan National Health Insurance System database. Multiple sensitivity analyses were performed to account for data uncertainty. The reference case revealed that the total cost of ET was $NT 20,901 for 17.08 QALY per patient. By contrast, the total cost of MT was $NT 21,171 for 17.15 QALY per patient. The incremental cost effectiveness ratio for ET versus that of MT was $NT 3703 per QALY. The cost-effectiveness acceptability curve indicated that ET was comparable to MT at a willingness-to-pay threshold of larger than $NT 35,000 per QALY. This cost-effectiveness analysis indicates that ET is comparable to MT for treating chronic otitis media in Taiwan. This result provides the latest information for physicians, the government, and third-party payers to select proper clinical practice. Copyright © 2017. Published by Elsevier Taiwan LLC.

Embedded EZ-Source Inverters

DEFF Research Database (Denmark)

Blaabjerg, Frede; Loh, Poh Chiang; Gao, F.

2008-01-01

-voltage oscillations to the system. Therefore, Z-source inverters are in effect safer and less complex, and can be implemented using only passive elements with no additional active semiconductor needed. Believing in the prospects of Z-source inverters, this paper contributes by introducing a new family of embedded EZ...

Trans-Z-source Neutral Point Clamped inverter

DEFF Research Database (Denmark)

Mo, W.; Loh, P. C.; Li, D.

2012-01-01

Transformer based Z-source (trans-Z-source) inverters are recently proposed by extending the traditional Z-source inverter with higher buck-boost capability as well as reducing the passive components at the same time. Multi-Level Z-source inverters are single-stage topological solutions used...... for buck-boost energy conversion with all the favourable advantages of multi-level switching retained. This paper presents three-level trans-Z-source Neutral Point Clamped (NPC) inverter topology, which achieves both the advantages of trans-Z-source and three-level NPC inverter configuration. With proper...... modulation scheme, the three-level trans-Z-source inverter can function with minimum of six device commutations per half carrier cycle (same as the traditional buck NPC inverter), while maintaining to produce the designed volt-sec average and inductive voltage boosting at ac output terminals. The designed...

Monolithically Integrated Flexible Black Phosphorus Complementary Inverter Circuits.

Science.gov (United States)

Liu, Yuanda; Ang, Kah-Wee

2017-07-25

Two-dimensional (2D) inverters are a fundamental building block for flexible logic circuits which have previously been realized by heterogeneously wiring transistors with two discrete channel materials. Here, we demonstrate a monolithically integrated complementary inverter made using a homogeneous black phosphorus (BP) nanosheet on flexible substrates. The digital logic inverter circuit is demonstrated via effective threshold voltage tuning within a single BP material, which offers both electron and hole dominated conducting channels with nearly symmetric pinch-off and current saturation. Controllable electron concentration is achieved by accurately modulating the aluminum (Al) donor doping, which realizes BP n-FET with a room-temperature on/off ratio >10 3 . Simultaneously, work function engineering is employed to obtain a low Schottky barrier contact electrode that facilities hole injection, thus enhancing the current density of the BP p-FET by 9.4 times. The flexible inverter circuit shows a clear digital logic voltage inversion operation along with a larger-than-unity direct current voltage gain, while exhibits alternating current dynamic signal switching at a record high frequency up to 100 kHz and remarkable electrical stability upon mechanical bending with a radii as small as 4 mm. Our study demonstrates a practical monolithic integration strategy for achieving functional logic circuits on one material platform, paving the way for future high-density flexible electronic applications.

New method for thickness determination and microscopic imaging of graphene-like two-dimensional materials

International Nuclear Information System (INIS)

Qin Xudong; Chen Yonghai; Liu Yu; Zhu Laipan; Li Yuan; Wu Qing; Huang Wei

2016-01-01

We employed the microscopic reflectance difference spectroscopy (micro-RDS) to determine the layer-number and microscopically image the surface topography of graphene and MoS 2 samples. The contrast image shows the efficiency and reliability of this new clipping technique. As a low-cost, quantifiable, no-contact and non-destructive method, it is not concerned with the characteristic signal of certain materials and can be applied to arbitrary substrates. Therefore it is a perfect candidate for characterizing the thickness of graphene-like two-dimensional materials. (paper)

Stability Assessment of a System Comprising a Single Machine and Inverter with Scalable Ratings

Energy Technology Data Exchange (ETDEWEB)

Johnson, Brian B [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Lin, Yashen [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Gevorgian, Vahan [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Purba, Victor [University of Minnesota; Dhople, Sairaj [University of Minnesota

2017-09-28

From the inception of power systems, synchronous machines have acted as the foundation of large-scale electrical infrastructures and their physical properties have formed the cornerstone of system operations. However, power electronics interfaces are playing a growing role as they are the primary interface for several types of renewable energy sources and storage technologies. As the role of power electronics in systems continues to grow, it is crucial to investigate the properties of bulk power systems in low inertia settings. In this paper, we assess the properties of coupled machine-inverter systems by studying an elementary system comprised of a synchronous generator, three-phase inverter, and a load. Furthermore, the inverter model is formulated such that its power rating can be scaled continuously across power levels while preserving its closed-loop response. Accordingly, the properties of the machine-inverter system can be assessed for varying ratios of machine-to-inverter power ratings and, hence, differing levels of inertia. After linearizing the model and assessing its eigenvalues, we show that system stability is highly dependent on the interaction between the inverter current controller and machine exciter, thus uncovering a key concern with mixed machine-inverter systems and motivating the need for next-generation grid-stabilizing inverter controls.

Low-cost satellite mechanical design and construction

Science.gov (United States)

Boisjolie-Gair, Nathaniel; Straub, Jeremy

2017-05-01

This paper presents a discussion of techniques for low-cost design and construction of a CubeSat mechanical structure that can serve as a basis for academic programs and a starting point for government, military and commercial large-scale sensing networks, where the cost of each node must be minimized to facilitate system affordability and lower the cost and associated risk of losing any node. Spacecraft Design plays a large role in manufacturability. An intentionally simplified mechanical design is presented which reduces machining costs, as compared to more intricate designs that were considered. Several fabrication approaches are evaluated relative to the low-cost goal.

Hydrodynamic stability of inverted annular flow in an adiabatic simulation

International Nuclear Information System (INIS)

De Jarlais, G.; Ishii, M.; Linehan, J.

1986-01-01

Inverted annular flow was simulated adiabatically with turbulent water jets, issuing downward from large aspect ratio nozzles, enclosed in gas annuli. Velocities, diameters, and gas species were varied, and core jet length, shape, breakup mode, and dispersed core droplet sizes were recorded at approximately 750 data points. Inverted annular flow destabilization led to inverted slug flow at low relative velocities, and to dispersed droplet flow, core breakup length correlations were developed by extending work on free liquid jets to include this coaxial, jet disintegration phenomenon. The results show length dependence upon D/sub J/, Re/sub J/, We/sub J/, α, and We/sub G/,rel. Correlations for core shape, breakup mechanisms, and dispersed core droplet size were also developed, by extending the results of free jet stability, roll wave entrainment, and churn turbulent droplet stability studies

Five-level Z-source diode-clamped inverter

DEFF Research Database (Denmark)

Gao, F.; Loh, Poh Chiang; Blaabjerg, Frede

2010-01-01

This study proposes a five-level Z-source diode-clamped inverter designed with two intermediate Z-source networks connected between the dc input sources and rear-end inverter circuitry. By partially shorting the Z-source networks, new operating states not previously reported for two-level Z......-source inverter are introduced here for operating the proposed inverter with voltage buck–boost energy conversion ability and five-level phase voltage switching. These characteristic features are in fact always ensured at the inverter terminal output by simply adopting a properly designed carrier modulation...

Component-Minimized Buck-Boost Voltage Source Inverters

DEFF Research Database (Denmark)

Gao, F.; Loh, P.C.; Blaabjerg, Frede

2007-01-01

This paper presents the design of buck-boost B4 inverters that can be derived from either Ćuk- or SEPIC-derived buck-boost B6 inverters. Unlike traditional inverters, the integration of front-end voltage boost circuitry and inverter circuitry allows it to perform buck-boost voltage inversion...... between capacitors. Modulation wise, the proposed buck-boost B4 inverters can be controlled using a carefully designed carrier-based pulse-width modulation (PWM) scheme that will always ensure balanced threephase outputs as desired, while simultaneously achieving minimal voltage stress across...

Hexuple-Inverter Configuration for Multilevel Nine-Phase Symmetrical Open-Winding Converter

DEFF Research Database (Denmark)

Padmanaban, Sanjeevi Kumar; Bhaskar, Mahajan Sagar; Maroti, Pandav Kiran

2016-01-01

Hexuple-inverter configuration for multilevel nine-phase symmetrical open-winding ac converter is articulated in this work. Power modular unit consists of six classical three-phase voltage source inverters (VSI). Each VSI includes one bi-directional device (MOSFET/IGBT) per each phase and link...... software’s (Matlab/PLECS). Results always showed good conformity with the developed theoretical background under working conditions. The proposed converter found suit for (low-voltage/high current) electric vehicles, ac tractions and ‘More-Electric Aircraft’ applications....

On Invertible Sampling and Adaptive Security

DEFF Research Database (Denmark)

Ishai, Yuval; Kumarasubramanian, Abishek; Orlandi, Claudio

2011-01-01

functionalities was left open. We provide the first convincing evidence that the answer to this question is negative, namely that some (randomized) functionalities cannot be realized with adaptive security. We obtain this result by studying the following related invertible sampling problem: given an efficient...... sampling algorithm A, obtain another sampling algorithm B such that the output of B is computationally indistinguishable from the output of A, but B can be efficiently inverted (even if A cannot). This invertible sampling problem is independently motivated by other cryptographic applications. We show......, under strong but well studied assumptions, that there exist efficient sampling algorithms A for which invertible sampling as above is impossible. At the same time, we show that a general feasibility result for adaptively secure MPC implies that invertible sampling is possible for every A, thereby...

Preparation of inverted medium and processing in the inverted medium

International Nuclear Information System (INIS)

Zafarullah, Ijaz; Tian Minghzen; Chang Tiejun; Randall Babbitt, W.

2007-01-01

The processing of weak optical signals in spatial-spectral holographic (SSH) materials coherently inverted with optical frequency chirped pulses were investigated. Simulations and experimental studies in Tm 3+ :YAG were conducted to characterize the parameters of the frequency chirped laser pulse used to invert the SSH material in order to obtain high photon echo efficiency for SSH lidar processing. Collinear and angled beam geometries and single shot and accumulated processes were investigated. Echo efficiencies as high as 450% were measured, significantly higher than the typical stimulated photon echo efficiency of 10%

Preparation of inverted medium and processing in the inverted medium

Energy Technology Data Exchange (ETDEWEB)

Zafarullah, Ijaz [Department of Physics, Montana State University, Bozeman, MT 59717 (United States)]. E-mail: ijaz@montana.edu; Tian Minghzen [Department of Physics, Montana State University, Bozeman, MT 59717 (United States); Chang Tiejun [The Spectrum Laboratory, Montana State University, Bozeman, MT 59717 (United States); Randall Babbitt, W. [Department of Physics, Montana State University, Bozeman, MT 59717 (United States)

2007-11-15

The processing of weak optical signals in spatial-spectral holographic (SSH) materials coherently inverted with optical frequency chirped pulses were investigated. Simulations and experimental studies in Tm{sup 3+}:YAG were conducted to characterize the parameters of the frequency chirped laser pulse used to invert the SSH material in order to obtain high photon echo efficiency for SSH lidar processing. Collinear and angled beam geometries and single shot and accumulated processes were investigated. Echo efficiencies as high as 450% were measured, significantly higher than the typical stimulated photon echo efficiency of 10%.

Open-top selective plane illumination microscope for conventionally mounted specimens.

Science.gov (United States)

McGorty, Ryan; Liu, Harrison; Kamiyama, Daichi; Dong, Zhiqiang; Guo, Su; Huang, Bo

2015-06-15

We have developed a new open-top selective plane illumination microscope (SPIM) compatible with microfluidic devices, multi-well plates, and other sample formats used in conventional inverted microscopy. Its key element is a water prism that compensates for the aberrations introduced when imaging at 45 degrees through a coverglass. We have demonstrated its unique high-content imaging capability by recording Drosophila embryo development in environmentally-controlled microfluidic channels and imaging zebrafish embryos in 96-well plates. We have also shown the imaging of C. elegans and moving Drosophila larvae on coverslips.

Solar Charged Stand Alone Inverter

OpenAIRE

M.Vasugi; Prof R.Jayaraman

2014-01-01

This paper deals with solar powered stand alone inverter which converts the variable dc output of a photovoltaic solar panel into ac that can be fed to loads. Stand alone inverters are used in systems where the inverter get its energy from batteries charged by photo voltaic arrays. A charge controller limits the rate at which electric current is added to or drawn from electric batteries. This charge discharge controller is needed to prevent the battery from being overcharged o...

Ultrastructure and Light Microscope Analysis of Intact Skin after a Varying Number of Low Level Laser Irradiations in Mice

Directory of Open Access Journals (Sweden)

Mamie Mizusaki Iyomasa

2014-01-01

Full Text Available Low level laser therapy (LLLT has been used to relieve pain, inflammation, and wound healing processes. Thus, the skin is overexposed to laser and this effect is not completely understood. This study analyzed the effects of the number of laser applications (three, six, and 10 on the intact skin of the masseteric region in mice of strain HRS/J. The animals (n=30 were equally divided into control (0 J/cm2 and irradiated (20 J/cm2, and each of these groups was further equally divided according to the number of laser applications (three, six, and 10 and underwent LLLT on alternate days. Samples were analyzed by light microscopy and transmission electron microscope (TEM. The animals receiving applications exhibited open channels more dilated between the keratinocytes and photobiomodulation effect on endothelial cells and fibroblasts by TEM. Under the light microscope after 10 laser applications, the type I collagen decreased (P<0.05 compared to the three and six applications. Under these experimental conditions, all numbers of applications provided photobiomodulatory effect on the epidermis and dermis, without damage. More studies are needed to standardize the energy density and number of applications recommended for laser therapy to have a better cost-benefit ratio associated with treatment.

Low Cost Integrated Navigation System for Unmanned Vessel

Directory of Open Access Journals (Sweden)

Yang Changsong

2017-11-01

Full Text Available Large errors of low-cost MEMS inertial measurement unit (MIMU lead to huge navigation errors, even wrong navigation information. An integrated navigation system for unmanned vessel is proposed. It consists of a low-cost MIMU and Doppler velocity sonar (DVS. This paper presents an integrated navigation method, to improve the performance of navigation system. The integrated navigation system is tested using simulation and semi-physical simulation experiments, whose results show that attitude, velocity and position accuracy has improved awfully, giving exactly accurate navigation results. By means of the combination of low-cost MIMU and DVS, the proposed system is able to overcome fast drift problems of the low cost IMU.

Interior tomography in microscopic CT with image reconstruction constrained by full field of view scan at low spatial resolution

Science.gov (United States)

Luo, Shouhua; Shen, Tao; Sun, Yi; Li, Jing; Li, Guang; Tang, Xiangyang

2018-04-01

In high resolution (microscopic) CT applications, the scan field of view should cover the entire specimen or sample to allow complete data acquisition and image reconstruction. However, truncation may occur in projection data and results in artifacts in reconstructed images. In this study, we propose a low resolution image constrained reconstruction algorithm (LRICR) for interior tomography in microscopic CT at high resolution. In general, the multi-resolution acquisition based methods can be employed to solve the data truncation problem if the project data acquired at low resolution are utilized to fill up the truncated projection data acquired at high resolution. However, most existing methods place quite strict restrictions on the data acquisition geometry, which greatly limits their utility in practice. In the proposed LRICR algorithm, full and partial data acquisition (scan) at low and high resolutions, respectively, are carried out. Using the image reconstructed from sparse projection data acquired at low resolution as the prior, a microscopic image at high resolution is reconstructed from the truncated projection data acquired at high resolution. Two synthesized digital phantoms, a raw bamboo culm and a specimen of mouse femur, were utilized to evaluate and verify performance of the proposed LRICR algorithm. Compared with the conventional TV minimization based algorithm and the multi-resolution scout-reconstruction algorithm, the proposed LRICR algorithm shows significant improvement in reduction of the artifacts caused by data truncation, providing a practical solution for high quality and reliable interior tomography in microscopic CT applications. The proposed LRICR algorithm outperforms the multi-resolution scout-reconstruction method and the TV minimization based reconstruction for interior tomography in microscopic CT.

21 CFR 184.1859 - Invert sugar.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Invert sugar. 184.1859 Section 184.1859 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN... Substances Affirmed as GRAS § 184.1859 Invert sugar. (a) Invert sugar (CAS Reg. No. 8013-17-0) is an aqueous...

A video-amplifier device for the transmission-type electron microscope ELMISCOP I of Siemens

International Nuclear Information System (INIS)

Groboth, G.; Hoerl, E.M.

1975-01-01

In order to get a visual image of the sample at the final screen of a transmission-type electron microscope and to keep at the same time the sample at low temperature a video-amplifier device has been developed by the authors. Details about its design and the necessary reconstruction of the electron microscope equipment are given. The beam current density at the transparent screen is reduced to 10 -12 -10 -13 A.cm -2 . Moreover the costs of this video-amplifier device are lower than those available. (CR)

Visible-to-visible four-photon ultrahigh resolution microscopic imaging with 730-nm diode laser excited nanocrystals.

Science.gov (United States)

Wang, Baoju; Zhan, Qiuqiang; Zhao, Yuxiang; Wu, Ruitao; Liu, Jing; He, Sailing

2016-01-25

Further development of multiphoton microscopic imaging is confronted with a number of limitations, including high-cost, high complexity and relatively low spatial resolution due to the long excitation wavelength. To overcome these problems, for the first time, we propose visible-to-visible four-photon ultrahigh resolution microscopic imaging by using a common cost-effective 730-nm laser diode to excite the prepared Nd(3+)-sensitized upconversion nanoparticles (Nd(3+)-UCNPs). An ordinary multiphoton scanning microscope system was built using a visible CW diode laser and the lateral imaging resolution as high as 161-nm was achieved via the four-photon upconversion process. The demonstrated large saturation excitation power for Nd(3+)-UCNPs would be more practical and facilitate the four-photon imaging in the application. A sample with fine structure was imaged to demonstrate the advantages of visible-to-visible four-photon ultrahigh resolution microscopic imaging with 730-nm diode laser excited nanocrystals. Combining the uniqueness of UCNPs, the proposed visible-to-visible four-photon imaging would be highly promising and attractive in the field of multiphoton imaging.

Multi-technology Integration Based on Low-contrast Microscopic Image Enhancement

Directory of Open Access Journals (Sweden)

Haoge Ma

2014-01-01

Full Text Available Microscopic image enhancement is an important issue of image processing technique, which is used to improve the visual quality of image. This paper describes a novel multi resolution image segmentation algorithm for low DOF images. The algorithm is designed to separate a sharply focused object of interest from other foreground or background objects. The algorithm is fully automatic in that all parameters are image in dependent. A multiscale-approach based on high frequency wavelet coefficients and their statistics is used to perform context dependent classification of individual blocks of the image. Compared with the state of the art algorithms, this new algorithm provides better accuracy at higher speed.

Aalborg Inverter - A New Type of “Buck in Buck, Boost in Boost” Grid-Tied Inverter

DEFF Research Database (Denmark)

Wu, Weimin; Ji, Junhao; Blaabjerg, Frede

2015-01-01

This paper presents a new family of high efficiency dc/ac grid-tied inverter with a wide variation of input dc voltage. It is a “boost in boost, buck in buck” inverter, meaning that only one power stage works at high frequency in order to achieve minimum switching loss. The minimum voltage drop...... of the filtering inductor in the power loop is achieved to reduce the conduction power loss in both “boost” and “buck” mode. The principle of operation is demonstrated through the analysis on the equivalent circuits of a “half-bridge” single-phase inverter. The theoretical analysis shows that when input dc voltage...... is larger than the magnitude of the ac voltage, it is a voltage-source inverter, and on the contrary it is current-source inverter in the other mode. A 220 V/50 Hz/ 2000 W prototype has been constructed. Simulations and experiments show that it has a good control and system performance....

Lower-Temperature Invert Design For Diffusion Barrier

International Nuclear Information System (INIS)

Bruce Stanley

2001-01-01

The objective of this analysis is to advance the state of the subsurface facilities design to primarily support the ''Yucca Mountain Science and Engineering Report'' (DOE 2001) and to also support the preparation and revision of System Description Document's Section 2 system descriptions (CRWMS M and O 2001, pp. 9 and 11). The results may also eventually support the License Application (CRWMS M and O 2001, p. 3). The Performance Assessment Department will be the primary user of the information generated and will be used in abstraction modeling for the lower-temperature scenario (CRWMS M and O 200 1, p. 27). This analysis will evaluate the invert relative to the lower- and higher-temperature conditions in accordance with the primary tasks below. Invert design is a major factor in allowing water entering the drift to pass freely and enter the drift floor without surface ponding and in limiting diffusive transport into the host rock. Specific cost effective designs will be conceptualized under the new lower-temperature conditions in this analysis. Interfacing activities and all aspects of Integrated Safety Management and Nuclear Culture principles are included in this work scope by adhering to the respective principles during this design activity and by incorporating safety into the design analysis (CRWMS M and O 2001, p. 8). Primary tasks of this analysis include identifying available design information from existing sources on the invert as a diffusive barrier, developing concepts that reduce the amount steel, and developing other design features that accommodate both lower- and higher-temperature operating modes (CRWMS M and O 2001, p.16)

Miniaturized microscope for high throughput screening of tumor spheroids in microfluidic devices

Science.gov (United States)

Uranga, Javier; Rodríguez-Pena, Alejandro; Gahigiro, Desiré; Ortiz-de-Solorzano, Carlos

2018-02-01

High-throughput in vitro screening of highly physiological three-dimensional cell cultures (3D-HTS) is rapidly gaining importance in preclinical studies, to study the effect of the microenvironment in tumor development, and to evaluate the efficacy of new anticancer drugs. Furthermore, it could also be envisioned the use of 3D-HTS systems in personalized anti-cancer treatment planning, based on tumor organoids or spheroids grown from tumor biopsies or isolated tumor circulating cells. Most commercial, multi-well plate based 3D-HTS systems are large, expensive, and are based on the use of multi-well plates that hardly provide a physiological environment and require the use of large amounts of biological material and reagents. In this paper we present a novel, miniaturized inverted microscope (hereinafter miniscospe), made up of low-cost, mass producible parts, that can be used to monitor the growth of living tumor cell spheroids within customized three-dimensional microfluidic platforms. Our 3D-HTS miniscope combines phase contrast imaging based on oblique back illumination technique with traditional widefield epi-fluorescence imaging, implemented using miniaturized electro-optical parts and gradient-index refraction lenses. This small (3x6x2cm), lightweight device can effectively image overtime the growth of (>200) tumor spheroids in a controlled and reproducible environment. Our miniscope can be used to acquire time-lapse images of cellular living spheroids over the course of several hours and captures their growth before and after drug treatment, to evaluate the effectiveness of the drug.

Low-Cost Bio-Based Phase Change Materials as an Energy Storage Medium in Building Envelopes

Energy Technology Data Exchange (ETDEWEB)

Biswas, Kaushik [ORNL; Abhari, Mr. Ramin [Renewable Energy Group, Inc.; Shukla, Dr. Nitin [Fraunhofer USA, Center for Sustainable Energy Systems (CSE), Boston; Kosny, Dr. Jan [Fraunhofer USA, Center for Sustainable Energy Systems (CSE), Boston

2015-01-01

A promising approach to increasing the energy efficiency of buildings is the implementation of phase change material (PCM) in building envelope systems. Several studies have reported the energy saving potential of PCM in building envelopes. However, wide application of PCMs in building applications has been inhibited, in part, by their high cost. This article describes a novel paraffin product made of naturally occurring fatty acids/glycerides trapped into high density polyethylene (HDPE) pellets and its performance in a building envelope application, with the ultimate goal of commercializing a low-cost PCM platform. The low-cost PCM pellets were mixed with cellulose insulation, installed in external walls and field-tested under natural weatherization conditions for a period of several months. In addition, several PCM samples and PCM-cellulose samples were prepared under controlled conditions for laboratory-scale testing. The laboratory tests were performed to determine the phase change properties of PCM-enhanced cellulose insulation both at microscopic and macroscopic levels. This article presents the data and analysis from the exterior test wall and the laboratory-scale test data. PCM behavior is influenced by the weather and interior conditions, PCM phase change temperature and PCM distribution within the wall cavity, among other factors. Under optimal conditions, the field data showed up to 20% reduction in weekly heat transfer through an external wall due to the PCM compared to cellulose-only insulation.

Online Variable Topology-Type Photovoltaic Grid-Connected Inverter

DEFF Research Database (Denmark)

Wu, Fengjiang; Sun, Bo; Duan, Jiandong

2015-01-01

In photovoltaic (PV) grid-connected generation system, the key focus is how to expand the generation range of the PV array and enhance the total efficiency of the system. This paper originally derived expressions of the total loss and grid current total harmonics distortions of cascaded inverter...... and H-bridge inverter under the conditions of variable output voltage and power of the PV array. It is proved that, compared with the H-bridge inverter, the operation range of the cascaded inverter is wider, whereas the total loss is larger. Furthermore, a novel online variable topology-type grid......-connected inverter is proposed. A bidirectional power switch is introduced into the conventional cascaded inverter to connect the negative terminals of the PV arrays. When the output voltages of the PV arrays are lower, the proposed inverter works under cascaded inverter mode to obtain wider generation range. When...

A compact light-sheet microscope for the study of the mammalian central nervous system

Science.gov (United States)

Yang, Zhengyi; Haslehurst, Peter; Scott, Suzanne; Emptage, Nigel; Dholakia, Kishan

2016-01-01

Investigation of the transient processes integral to neuronal function demands rapid and high-resolution imaging techniques over a large field of view, which cannot be achieved with conventional scanning microscopes. Here we describe a compact light sheet fluorescence microscope, featuring a 45° inverted geometry and an integrated photolysis laser, that is optimized for applications in neuroscience, in particular fast imaging of sub-neuronal structures in mammalian brain slices. We demonstrate the utility of this design for three-dimensional morphological reconstruction, activation of a single synapse with localized photolysis, and fast imaging of neuronal Ca2+ signalling across a large field of view. The developed system opens up a host of novel applications for the neuroscience community. PMID:27215692

High-speed atomic force microscopy combined with inverted optical microscopy for studying cellular events.

Science.gov (United States)

Suzuki, Yuki; Sakai, Nobuaki; Yoshida, Aiko; Uekusa, Yoshitsugu; Yagi, Akira; Imaoka, Yuka; Ito, Shuichi; Karaki, Koichi; Takeyasu, Kunio

2013-01-01

A hybrid atomic force microscopy (AFM)-optical fluorescence microscopy is a powerful tool for investigating cellular morphologies and events. However, the slow data acquisition rates of the conventional AFM unit of the hybrid system limit the visualization of structural changes during cellular events. Therefore, high-speed AFM units equipped with an optical/fluorescence detection device have been a long-standing wish. Here we describe the implementation of high-speed AFM coupled with an optical fluorescence microscope. This was accomplished by developing a tip-scanning system, instead of a sample-scanning system, which operates on an inverted optical microscope. This novel device enabled the acquisition of high-speed AFM images of morphological changes in individual cells. Using this instrument, we conducted structural studies of living HeLa and 3T3 fibroblast cell surfaces. The improved time resolution allowed us to image dynamic cellular events.

Inverted Organic Solar Cells with Low-Temperature Al-Doped-ZnO Electron Transport Layer Processed from Aqueous Solution

Directory of Open Access Journals (Sweden)

Qianni Zhang

2018-01-01

Full Text Available The aqueous-based Zn-ammine complex solutions represent one of the most promising routes to obtain the ZnO electron transport layer (ETL at a low temperature in inverted organic solar cells (OSCs. However, to dope the ZnO film processed from the Zn-ammine complex solutions is difficult since the introduction of metal ions into the Zn-ammine complex is a nontrivial process as ammonium hydroxide tends to precipitate metal salts due to acid-base neutralization reactions. In this paper, we investigate the inverted OSCs with Al-doped-ZnO ETL made by immersion of metallic Al into the Zn-ammine precursor solution. The effects of ZnO layer with different immersion time of Al on film properties and solar cell performance have been studied. The results show that, with the Al-doped-ZnO ETL, an improvement of the device performance could be obtained compared with the device with the un-doped ZnO ETL. The improved device performance is attributed to the enhancement of charge carrier mobility leading to a decreased charge carrier recombination and improved charge collection efficiency. The fabricated thin film transistors with the same ZnO or AZO films confirm the improved electrical characteristics of the Al doped ZnO film.

Implementation of floating gate MOSFET in inverter for threshold voltage tunability

Directory of Open Access Journals (Sweden)

Musa F.A.S.

2017-01-01

Full Text Available This paper presents the ability of floating gate MOSFET (FGMOS threshold voltage to be programmed or tuned which is exploited to improve the performance of electronic circuit design. This special characteristic owns by FGMOS is definitely contributes towards low voltage and low power circuit design. The comparison of threshold voltage between FGMOS and conventional NMOS is done in order to prove that FGMOS is able to produce a lower threshold voltage compared to conventional NMOS. In addition, in this paper, an implementation of FGMOS into inverter circuit is also done to show the programmability of FGMOS threshold voltage. The operations of the inverter circuits are verified using Sypnopsys simulation in 0.1μm CMOS technology with supply voltage of 1.8V.

Optimized Carrier Based Multilevel Generated Modified Dual Three-Phase Open-Winding Inverter for Medium Power Applications

DEFF Research Database (Denmark)

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

2016-01-01

This paper presents a novel carrier based multilevel modulation for modified dual three-phase open-winding inverter applicable for low-voltage/high-current applications. A standard three-phase voltage source inverter (VSI) is connected across the open-winding of both ends of the motor. Each VSI i...

An Optimal Current Controller Design for a Grid Connected Inverter to Improve Power Quality and Test Commercial PV Inverters.

Science.gov (United States)

Algaddafi, Ali; Altuwayjiri, Saud A; Ahmed, Oday A; Daho, Ibrahim

2017-01-01

Grid connected inverters play a crucial role in generating energy to be fed to the grid. A filter is commonly used to suppress the switching frequency harmonics produced by the inverter, this being passive, and either an L- or LCL-filter. The latter is smaller in size compared to the L-filter. But choosing the optimal values of the LCL-filter is challenging due to resonance, which can affect stability. This paper presents a simple inverter controller design with an L-filter. The control topology is simple and applied easily using traditional control theory. Fast Fourier Transform analysis is used to compare different grid connected inverter control topologies. The modelled grid connected inverter with the proposed controller complies with the IEEE-1547 standard, and total harmonic distortion of the output current of the modelled inverter has been just 0.25% with an improved output waveform. Experimental work on a commercial PV inverter is then presented, including the effect of strong and weak grid connection. Inverter effects on the resistive load connected at the point of common coupling are presented. Results show that the voltage and current of resistive load, when the grid is interrupted, are increased, which may cause failure or damage for connecting appliances.

Automated digital image analysis of islet cell mass using Nikon's inverted eclipse Ti microscope and software to improve engraftment may help to advance the therapeutic efficacy and accessibility of islet transplantation across centers.

Science.gov (United States)

Gmyr, Valery; Bonner, Caroline; Lukowiak, Bruno; Pawlowski, Valerie; Dellaleau, Nathalie; Belaich, Sandrine; Aluka, Isanga; Moermann, Ericka; Thevenet, Julien; Ezzouaoui, Rimed; Queniat, Gurvan; Pattou, Francois; Kerr-Conte, Julie

2015-01-01

Reliable assessment of islet viability, mass, and purity must be met prior to transplanting an islet preparation into patients with type 1 diabetes. The standard method for quantifying human islet preparations is by direct microscopic analysis of dithizone-stained islet samples, but this technique may be susceptible to inter-/intraobserver variability, which may induce false positive/negative islet counts. Here we describe a simple, reliable, automated digital image analysis (ADIA) technique for accurately quantifying islets into total islet number, islet equivalent number (IEQ), and islet purity before islet transplantation. Islets were isolated and purified from n = 42 human pancreata according to the automated method of Ricordi et al. For each preparation, three islet samples were stained with dithizone and expressed as IEQ number. Islets were analyzed manually by microscopy or automatically quantified using Nikon's inverted Eclipse Ti microscope with built-in NIS-Elements Advanced Research (AR) software. The AIDA method significantly enhanced the number of islet preparations eligible for engraftment compared to the standard manual method (p image analysis utilizing the Nikon Instruments software is an unbiased, simple, and reliable teaching tool to comprehensively assess the individual size of each islet cell preparation prior to transplantation. Implementation of this technology to improve engraftment may help to advance the therapeutic efficacy and accessibility of islet transplantation across centers.

Aalborg Inverter - A new type of “Buck in Buck, Boost in Boost” Grid-tied Inverter

DEFF Research Database (Denmark)

Wu, Weimin; Blaabjerg, Frede

2013-01-01

This paper presents a new family of high efficiency DC/AC grid-tied inverter with a wide variation of input DC voltage. It is a kind of “Boost in Boost, Buck in Buck” inverter, meaning that only one power stage works at the high frequency to achieve the minimum switching loss. Furthermore......, the minimum filtering inductance in the power loop is achieved to reduce the conduction power loss whether in “Boost” or “Buck” mode. In theory, it can achieve higher efficiency than other inverters under the same condition of input DC voltage. The principle of operation is fully illustrated through...... the analysis on the equivalent circuits of a “three-level” single-phase inverter. Simulations show it has good control performance....

A low-cost colorimeter.

Science.gov (United States)

Jones, N B; Riley, C; Sheya, M S; Hosseinmardi, M M

1984-01-01

A need for a colorimeter with low capital and maintenance costs has been suggested for countries with foreign exchange problems and no local medical instrumentation industry. This paper puts forward a design for such a device based on a domestic light-bulb, photographic filters and photovoltaic cells. The principle of the design is the use of a balancing technique involving twin light paths for test solution and reference solution and an electronic bridge circuit. It is shown that proper selection of the components will allow the cost objectives to be met and also provide acceptable linearity, precision, accuracy and repeatability.

A Cost-Effective Fluorescence Mini-Microscope with Adjustable Magnifications for Biomedical Applications

Science.gov (United States)

Zhang, Yu Shrike; Ribas, João; Nadhman, Akhtar; Aleman, Julio; Selimović, Šeila; Lesher-Perez, Sasha Cai; Wang, Ting; Manoharan, Vijayan; Shin, Su-Ryon; Damilano, Alessia; Annabi, Nasim; Dokmeci, Mehmet Remzi; Takayama, Shuichi; Khademhosseini, Ali

2015-01-01

We have designed and fabricated a miniature microscope from off-the-shelf components and webcam, with built-in fluorescence capability for biomedical applications. The mini-microscope was able to detect both biochemical parameters such as cell/tissue viability (e.g. Live/Dead assay), and biophysical properties of the microenvironment such as oxygen levels in microfabricated tissues based on an oxygen-sensitive fluorescent dye. This mini-microscope has adjustable magnifications from 8-60X, achieves a resolution as high as microscope was able to chronologically monitor cell migration and analyze beating of microfluidic liver and cardiac bioreactors in real time, respectively. The mini-microscope system is cheap, and its modularity allows convenient integration with a wide variety of pre-existing platforms including but not limited to, cell culture plates, microfluidic devices, and organs-on-a-chip systems. Therefore, we envision its widespread applications in cell biology, tissue engineering, biosensing, microfluidics, and organs-on-chips, which can potentially replace conventional bench-top microscopy where long-term in situ and large-scale imaging/analysis is required. PMID:26282117

Diamond logic inverter with enhancement-mode metal-insulator-semiconductor field effect transistor

Energy Technology Data Exchange (ETDEWEB)

Liu, J. W., E-mail: liu.jiangwei@nims.go.jp [International Center for Young Scientists (ICYS), National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan); Liao, M. Y.; Imura, M. [Optical and Electronic Materials Unit, NIMS, 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan); Watanabe, E.; Oosato, H. [Nanofabrication Platform, NIMS, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan); Koide, Y., E-mail: koide.yasuo@nims.go.jp [Optical and Electronic Materials Unit, NIMS, 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan); Nanofabrication Platform, NIMS, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan); Center of Materials Research for Low Carbon Emission, NIMS, 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan)

2014-08-25

A diamond logic inverter is demonstrated using an enhancement-mode hydrogenated-diamond metal-insulator-semiconductor field effect transistor (MISFET) coupled with a load resistor. The gate insulator has a bilayer structure of a sputtering-deposited LaAlO{sub 3} layer and a thin atomic-layer-deposited Al{sub 2}O{sub 3} buffer layer. The source-drain current maximum, extrinsic transconductance, and threshold voltage of the MISFET are measured to be −40.7 mA·mm{sup −1}, 13.2 ± 0.1 mS·mm{sup −1}, and −3.1 ± 0.1 V, respectively. The logic inverters show distinct inversion (NOT-gate) characteristics for input voltages ranging from 4.0 to −10.0 V. With increasing the load resistance, the gain of the logic inverter increases from 5.6 to as large as 19.4. The pulse response against the high and low input voltages shows the inversion response with the low and high output voltages.

Low Cost/Low Noise Variable Pitch Ducted Fan, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — ACI proposes a design for a Propulsor (Low Cost/Low Noise Variable Pitch Ducted Fan) that has wide application in all sectors of Aviation. Propulsor hardware of this...

Design of Solar PV Cell Based Inverter for Unbalanced and Distorted Industrial Loads

Directory of Open Access Journals (Sweden)

Naga Ananth D

2015-04-01

Full Text Available PV cell is getting importance in low and medium power generation due to easy installation, low maintenance and subsidies in price from respective nation. Most of the loads in distribution system are unbalanced and distorted, due to which there will be unbalanced voltage and current occur at load and may disturb its overall performance. Due to these loads voltage unbalance, distorted voltage and current and variable power factors in each phase can be observed. An efficient algorithm to mitigate unbalanced and distorted load and source voltage and current in solar photo voltaic (PV inverter for isolated load system was considered. This solar PV system can be applicable to remote located industrial loads like heating, welding and small arc furnace type distorted loads and also for unbalanced loads. The PV inverter is designed such that it will maintain nearly constant voltage magnitude and can mitigate harmonics in voltage and current near the load terminals. A MATLAB/ SIMULINK based solar PV inverter was simulated and results are compared with standard AC three phase grid connected system. The proposed shows that the inverter is having very less voltage and current harmonic content and can maintain nearly constant voltage profile for highly unbalanced system.

Cost-Effectiveness and Validity Assessment of Cyscope Microscope, Quantitative Buffy Coat Microscope, and Rapid Diagnostic Kit for Malaria Diagnosis among Clinic Attendees in Ibadan, Nigeria

Directory of Open Access Journals (Sweden)

Abiodun Ogunniyi

2016-01-01

Full Text Available Background. Unavailability of accurate, rapid, reliable, and cost-effective malaria diagnostic instruments constitutes major a challenge to malaria elimination. We validated alternative malaria diagnostic instruments and assessed their comparative cost-effectiveness. Method. Using a cross-sectional study design, 502 patients with malaria symptoms at selected health facilities in Ibadan between January and April 2014 were recruited consecutively. We examined malaria parasites using Cyscope®, QBC, and CareStart™ and results were compared to light microscopy (LM. Validity was determined by assessing sensitivity, specificity, positive predictive value (PPV, and negative predictive value (NPV. Costs per hour of use for instruments and turnaround time were determined. Result. Sensitivity of the instruments was 76.0% (CareStart, 95.0% (Cyscope, and 98.1% (QBC. Specificity was 96.0% (CareStart, 87.3% (Cyscope, and 85.5% (QBC. PPV were 65.2%, 67.5%, and 84.7%, while NPV were 93.6%, 98.6%, and 99.4% for CareStart, Cyscope, and QBC with Kappa values of 0.75 (CI = 0.68–0.82 for CareStart, 0.72 (CI = 0.65–0.78 for Cyscope, and 0.71 (CI = 0.64–0.77 for QBC. Average cost per hour of use was the lowest ($2.04 with the Cyscope. Turnaround time was the fastest with Cyscope (5 minutes. Conclusion. Cyscope fluorescent microscope had the shortest turnaround time and is the most cost-effective of all the malaria diagnostic instruments evaluated.

Power Hardware-in-the-Loop Evaluation of PV Inverter Grid Support on Hawaiian Electric Feeders

Energy Technology Data Exchange (ETDEWEB)

Nelson, Austin A [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Prabakar, Kumaraguru [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Nagarajan, Adarsh [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Nepal, Shaili [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Hoke, Anderson F [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Asano, Marc [Hawaiian Electric Company; Ueda, Reid [Hawaiian Electric Company; Ifuku, Earle [Hawaiian Electric Company

2017-10-03

As more grid-connected photovoltaic (PV) inverters become compliant with evolving interconnections requirements, there is increased interest from utilities in understanding how to best deploy advanced grid-support functions (GSF) in the field. One efficient and cost-effective method to examine such deployment options is to leverage power hardware-in-the-loop (PHIL) testing methods, which combine the fidelity of hardware tests with the flexibility of computer simulation. This paper summarizes a study wherein two Hawaiian Electric feeder models were converted to real-time models using an OPAL-RT real-time digital testing platform, and integrated with models of GSF capable PV inverters based on characterization test data. The integrated model was subsequently used in PHIL testing to evaluate the effects of different fixed power factor and volt-watt control settings on voltage regulation of the selected feeders using physical inverters. Selected results are presented in this paper, and complete results of this study were provided as inputs for field deployment and technical interconnection requirements for grid-connected PV inverters on the Hawaiian Islands.

A New Family of Multilevel Grid Connected Inverters Based on Packed U Cell Topology.

Science.gov (United States)

Pakdel, Majid; Jalilzadeh, Saeid

2017-09-29

In this paper a novel packed U cell (PUC) based multilevel grid connected inverter is proposed. Unlike the U cell arrangement which consists of two power switches and one capacitor, in the proposed converter topology a lower DC power supply from renewable energy resources such as photovoltaic arrays (PV) is used as a base power source. The proposed topology offers higher efficiency and lower cost using a small number of power switches and a lower DC power source which is supplied from renewable energy resources. Other capacitor voltages are extracted from the base lower DC power source using isolated DC-DC power converters. The operation principle of proposed transformerless multilevel grid connected inverter is analyzed theoretically. Operation of the proposed multilevel grid connected inverter is verified through simulation studies. An experimental prototype using STM32F407 discovery controller board is performed to verify the simulation results.

A point of application study to determine the accuracy, precision and reliability of a low-cost balance plate for center of pressure measurement.

Science.gov (United States)

Goble, Daniel J; Khan, Ehran; Baweja, Harsimran S; O'Connor, Shawn M

2018-04-11

Changes in postural sway measured via force plate center of pressure have been associated with many aspects of human motor ability. A previous study validated the accuracy and precision of a relatively new, low-cost and portable force plate called the Balance Tracking System (BTrackS). This work compared a laboratory-grade force plate versus BTrackS during human-like dynamic sway conditions generated by an inverted pendulum device. The present study sought to extend previous validation attempts for BTrackS using a more traditional point of application (POA) approach. Computer numerical control (CNC) guided application of ∼155 N of force was applied five times to each of 21 points on five different BTrackS Balance Plate (BBP) devices with a hex-nose plunger. Results showed excellent agreement (ICC > 0.999) between the POAs and measured COP by the BBP devices, as well as high accuracy ( 0.999) providing evidence of almost perfect inter-device reliability. Taken together, these results provide an important, static corollary to the previously obtained dynamic COP results from inverted pendulum testing of the BBP. Copyright © 2018 Elsevier Ltd. All rights reserved.

Design and Implementation of nine level multilevel Inverter

Science.gov (United States)

Dhineshkumar, K.; Subramani, C.

2018-04-01

In this paper the solar based boost converter integrated Nine level multilevel inverter presented. It uses 7 switches to produce nine level output stepped waveform. The aim of the work to produce 9 level wave form using solar and boost converter. The conventional inverter has multiple sources and has 16 switches are required and also more number of voltage sources required. The proposed inverter required single solar panel and reduced number of switches and integrated boost converter which increase the input voltage of the inverter. The proposed inverter simulated and compared with R load using Mat lab and prototype model experimentally verified. The proposed inverter can be used in n number of solar applications.

Switched capacitor charge pump used for low-distortion imaging in atomic force microscope.

Science.gov (United States)

Zhang, Jie; Zhang, Lian Sheng; Feng, Zhi Hua

2015-01-01

The switched capacitor charge pump (SCCP) is an effective method of linearizing charges on piezoelectric actuators and therefore constitute a significant approach to nano-positioning. In this work, it was for the first time implemented in an atomic force microscope for low-distortion imaging. Experimental results showed that the image quality was improved evidently under the SCCP drive compared with that under traditional linear voltage drive. © Wiley Periodicals, Inc.

Low-Cost Servomotor Driver for PFM Control.

Science.gov (United States)

Aragon-Jurado, David; Morgado-Estevez, Arturo; Perez-Peña, Fernando

2017-12-31

Servomotors have already been around for some decades and they are extremely popular among roboticists due to their simple control technique, reliability and low-cost. They are usually controlled by using Pulse Width Modulation (PWM) and this paper aims to keep the idea of simplicity and low-cost, while introducing a new control technique: Pulse Frequency Modulation (PFM). The objective of this paper is to focus on our development of a low-cost servomotor controller which will allow the research community to use them with PFM. A low-cost commercial servomotor is used as the base system for the development: a small PCB that fits inside the case and allocates all the electronic components to control the motor has been designed to replace the original. The potentiometer is retained as the feedback sensor and a microcontroller is responsible for controlling the position of the motor. The paper compares the performance of a PWM and a PFM controlled servomotor. The comparison shows that the servomotor with our controller achieves a faster mechanism for switching targets and a lower latency. This controller can be used with neuromorphic systems to remove the conversion from events to PWM.

Low profile, low cost, new geometry integrated inductors

DEFF Research Database (Denmark)

Ouyang, Ziwei; Thomsen, Ole Cornelius; Andersen, Michael A. E.

2011-01-01

windings with well-defined thickness. Many advantages and disadvantages are described in depth. In this work, inverse coupling and direct coupling in the new geometry integrated inductors have been analyzed. Coupling characteristic caused by a special saturation behavior has been emphasis. And also...... variable inductors caused by the special saturation behavior may be utilized in some applications. The new integrated inductors make it possible to build low-profile, low-cost, flexibility DC/DC converters, and it can be extensively designed for the low-voltage and high-current required by the modern...

Pathway to 50% Efficient Inverted Metamorphic Concentrator Solar Cells

Energy Technology Data Exchange (ETDEWEB)

Geisz, John F [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Steiner, Myles A [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Jain, Nikhil [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Schulte, Kevin L [National Renewable Energy Laboratory (NREL), Golden, CO (United States); France, Ryan M [National Renewable Energy Laboratory (NREL), Golden, CO (United States); McMahon, William E [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Perl, Emmett [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Horowitz, Kelsey A [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Friedman, Daniel J [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

2017-09-06

Series-connected five (5J) and six junction (6J) concentrator solar cell strategies have the realistic potential to exceed 50% efficiency to enable low-cost CPV systems. We propose three strategies for developing a practical 6J device. We have overcome many of the challenges required to build such concentrator solar cell devices: We have developed 2.1 eV AlGaInP, 1.7 eV AlGaAs, and 1.7 eV GaInAsP junctions with external radiative efficiency greater than 0.1%. We have developed a transparent tunnel junction that absorbs minimal light intended for the second junction yet resists degradation under thermal load. We have developed metamorphic grades from the GaAs to the InP lattice constant that are transparent to sub-GaAs bandgap light. We have grown and compared low bandgap junctions (0.7eV - 1.2 eV) using metamorphic GaInAs, metamorphic GaInAsP, and GaInAsP lattice-matched to InP. And finally, we have demonstrated excellent performance in a high voltage, low current 4 junction inverted metamorphic device using 2.1, 1.7, 1.4, and 1.1 eV junctions with over 8.7 mA/cm2 one-sun current density that operates up to 1000 suns without tunnel junction failure.

The inverted cup device for blood transfer on malaria RDTs: ease of use, acceptability and safety in routine use by health workers in Nigeria.

Science.gov (United States)

Incardona, Sandra; Mwancha-Kwasa, Magoma; Rees-Channer, Roxanne R; Albertini, Audrey; Havumaki, Joshua; Chiodini, Peter; Oyibo, Wellington; Gonzalez, Iveth J

2018-01-15

Malaria rapid diagnostic tests (RDTs) are becoming widely adopted for case management at community level. However, reports and anecdotal observations indicate that the blood transfer step poses a significant challenge to many users. This study sought to evaluate the inverted cup device in the hands of health workers in everyday clinical practice, in comparison with the plastic pipette, and to determine the volume accuracy of the device made of a lower-cost plastic. The volume accuracy of inverted cup devices made of two plastics, PMMA and SBC, was compared by transferring blood 150 times onto filter paper and comparing the blood spot areas with those produced by 20 reference transfers with a calibrated micropipette. The ease of use, safety and acceptability of the inverted cup device and the pipette were evaluated by 50 health workers in Nigeria. Observations were recorded on pre-designed questionnaires, by the health workers themselves and by trained observers. Focus group discussions were also conducted. The volume accuracy assessment showed that the device made from the low-cost material (SBC) delivered a more accurate volume (mean 5.4 μL, SD 0.48 μL, range 4.5-7.0 μL) than the PMMA device (mean 5.9 μL, SD 0.48 μL, range 4.9-7.2 μL). The observational evaluation demonstrated that the inverted cup device performed better than the pipette in all aspects, e.g. higher proportions of health workers achieved successful blood collection (96%, vs. 66%), transfer of the required blood volume (90%, vs. 58%), and blood deposit without any loss (95%, vs. 50%). Majority of health workers also considered it' very easy' to use (81%),'very appropriate' for everyday use (78%), and 50% of them reported that it was their preferred BTD. The good volume accuracy and high acceptability of the inverted cup device shown in this study, along with observed ease of use and safety in hands of health workers, further strengthens prior findings which demonstrated its higher

The high cost of low-acuity ICU outliers.

Science.gov (United States)

Dahl, Deborah; Wojtal, Greg G; Breslow, Michael J; Holl, Randy; Huguez, Debra; Stone, David; Korpi, Gloria

2012-01-01

Direct variable costs were determined on each hospital day for all patients with an intensive care unit (ICU) stay in four Phoenix-area hospital ICUs. Average daily direct variable cost in the four ICUs ranged from $1,436 to $1,759 and represented 69.4 percent and 45.7 percent of total hospital stay cost for medical and surgical patients, respectively. Daily ICU cost and length of stay (LOS) were higher in patients with higher ICU admission acuity of illness as measured by the APACHE risk prediction methodology; 16.2 percent of patients had an ICU stay in excess of six days, and these LOS outliers accounted for 56.7 percent of total ICU cost. While higher-acuity patients were more likely to be ICU LOS outliers, 11.1 percent of low-risk patients were outliers. The low-risk group included 69.4 percent of the ICU population and accounted for 47 percent of all LOS outliers. Low-risk LOS outliers accounted for 25.3 percent of ICU cost and incurred fivefold higher hospital stay costs and mortality rates. These data suggest that severity of illness is an important determinant of daily resource consumption and LOS, regardless of whether the patient arrives in the ICU with high acuity or develops complications that increase acuity. The finding that a substantial number of long-stay patients come into the ICU with low acuity and deteriorate after ICU admission is not widely recognized and represents an important opportunity to improve patient outcomes and lower costs. ICUs should consider adding low-risk LOS data to their quality and financial performance reports.

High voltage series resonant inverter ion engine screen supply. [SCR series resonant inverter for space applications

Science.gov (United States)

Biess, J. J.; Inouye, L. Y.; Shank, J. H.

1974-01-01

A high-voltage, high-power LC series resonant inverter using SCRs has been developed for an Ion Engine Power Processor. The inverter operates within 200-400Vdc with a maximum output power of 2.5kW. The inverter control logic, the screen supply electrical and mechanical characteristics, the efficiency and losses in power components, regulation on the dual feedback principle, the SCR waveforms and the component weight are analyzed. Efficiency of 90.5% and weight density of 4.1kg/kW are obtained.

Low-cost in vitro fertilization: current insights

Directory of Open Access Journals (Sweden)

Teoh PJ

2014-08-01

Full Text Available Pek Joo Teoh, Abha MaheshwariAberdeen Fertility Centre, Aberdeen Maternity Hospital, University of Aberdeen, Aberdeen, UKAbstract: Despite the development of in vitro fertilization (IVF more than 30 years ago, the cost of treatment remains high. Furthermore, over the years, more sophisticated technologies and expensive medications have been introduced, making IVF increasingly inaccessible despite the increasing need. Globally, the option to undergo IVF is only available to a privileged few. In recent years, there has been growing interest in exploring strategies to reduce the cost of IVF treatment, which would allow the service to be provided in low-resource settings. In this review, we explore the various ways in which the cost of this treatment can be reduced.Keywords: IVF, low-cost, accessible, developing world

Thales: an instrument to measure the low field magnetophoretic mobility of microscopic objects

International Nuclear Information System (INIS)

Hackett, S L; St Pierre, T G

2005-01-01

An instrument, Thales, was designed and constructed to measure the induce motion of magnetic microspheres in a low magnetic field strength environment. Results show that Thales can be used to precisely measure the speed of microspheres (± 0.08 μm.s -1 ). We evaluated the motion of magnetic microspheres induced by an inhomogeneous magnetic field, and developed models for the microsphere magnetophoretic mobility, a parameter determining the speed attained by the microsphere in a given static low strength magnetic field environment. The data suggested that the magnetic material was located at the surfaces of the microspheres rather than being distributed evenly through the microspheres. With suitable calibration microspheres, Thales will be capable of directly measuring the low field magnetophoretic mobility of microscopic objects

A digital output accelerometer using MEMS-based piezoelectric accelerometers and arrayed CMOS inverters with satellite capacitors

International Nuclear Information System (INIS)

Kobayashi, T; Okada, H; Maeda, R; Itoh, T; Masuda, T

2011-01-01

The present paper describes the development of a digital output accelerometer composed of microelectromechanical systems (MEMS)-based piezoelectric accelerometers and arrayed complementary metal–oxide–semiconductor (CMOS) inverters accompanied by capacitors. The piezoelectric accelerometers were fabricated from multilayers of Pt/Ti/PZT/Pt/Ti/SiO 2 deposited on silicon-on-insulator (SOI) wafers. The fabricated piezoelectric accelerometers were connected to arrayed CMOS inverters. Each of the CMOS inverters was accompanied by a capacitor with a different capacitance called a 'satellite capacitor'. We have confirmed that the output voltage generated from the piezoelectric accelerometers can vary the output of the CMOS inverters from a high to a low level; the state of the CMOS inverters has turned from the 'off-state' into the 'on-state' when the output voltage of the piezoelectric accelerometers is larger than the threshold voltage of the CMOS inverters. We have also confirmed that the CMOS inverters accompanied by the larger satellite capacitor have become 'on-state' at a lower acceleration. On increasing the acceleration, the number of on-state CMOS inverters has increased. Assuming that the on-state and off-state of CMOS inverters correspond to logic '0' and '1', the present digital output accelerometers have expressed the accelerations of 2.0, 3.0, 5.0, and 5.5 m s −2 as digital outputs of 111, 110, 100, and 000, respectively

Key issues for low-cost FGD installations

Energy Technology Data Exchange (ETDEWEB)

DePriest, W.; Mazurek, J.M. [Sargent & Lundy LLC, Chicago, IL (United States)

1995-12-01

This paper will discuss various methods for installing low-cost FGD systems. The paper will include a discussion of various types of FGD systems available, both wet and dry, and will compare the relative cost of each type. Important design issues, such as use of spare equipment, materials of construction, etc. will be presented. An overview of various low-cost construction techniques (i.e., modularization) will be included. This paper will draw heavily from Sargent & Lundy`s database of past and current FGD projects together with information we gathered for several Electric Power Research Institute (EPRI) studies on the subject.

Inverter Output Filter Effect on PWM Motor Drives of a Flywheel Energy Storage System

Science.gov (United States)

Santiago, Walter

2004-01-01

NASA Glenn Research Center (GRC) has been involved in the research and development of high speed flywheel systems for small satellite energy storage and attitude control applications. One research and development area has been the minimization of the switching noise produced by the pulsed width modulated (PWM) inverter that drives the flywheel permanent magnet motor/generator (PM M/G). This noise can interfere with the flywheel M/G hardware and the system avionics hampering the full speed performance of the flywheel system. One way to attenuate the inverter switching noise is by placing an AC filter at the three phase output terminals of the inverter with the filter neutral point connected to the DC link (DC bus) midpoint capacitors. The main benefit of using an AC filter in this fashion is the significant reduction of the inverter s high dv/dt switching and its harmonics components. Additionally, common mode (CM) and differential mode (DM) voltages caused by the inverter s high dv/dt switching are also reduced. Several topologies of AC filters have been implemented and compared. One AC filter topology consists of a two-stage R-L-C low pass filter. The other topology consists of the same two-stage R-L-C low pass filter with a series connected trap filter (an inductor and capacitor connected in parallel). This paper presents the analysis, design and experimental results of these AC filter topologies and the comparison between the no filter case and conventional AC filter.

Diode-Assisted Buck-Boost Current Source Inverters

DEFF Research Database (Denmark)

Gao, F.; Cai, Liang; Loh, P.C.

2007-01-01

This paper presents a couple of novel current source inverters (CSIs) with the enhanced current buckboost capability. With the unique diode-inductor network added between current source inverter circuitry and current boost elements, the proposed buck-boost current source inverters demonstrate...... uninfluenced. Lastly, all theoretical findings were verified experimentally using constructed laboratory prototypes....

A facile route to inverted polymer solar cells using a precursor based zinc oxide electron transport layer

NARCIS (Netherlands)

Bruyn, P. de; Moet, D.J.D.; Blom, P.W.M.

2010-01-01

Inverted polymer:fullerene solar cells with ZnO and MoO3 transport layers are demonstrated. ZnO films are prepared through spin casting of a zinc acetylacetonate hydrate solution, followed by low temperature annealing under ambient conditions. The performance of solar cells with an inverted

A facile route to inverted polymer solar cells using a precursor based zinc oxide electron transport layer

NARCIS (Netherlands)

de Bruyn, P.; Moet, D. J. D.; Blom, P. W. M.

Inverted polymer: fullerene solar cells with ZnO and MoO(3) transport layers are demonstrated. ZnO films are prepared through spin casting of a zinc acetylacetonate hydrate solution, followed by low temperature annealing under ambient conditions. The performance of solar cells with an inverted

Low Power Consumption Complementary Inverters with n-MoS2 and p-WSe2 Dichalcogenide Nanosheets on Glass for Logic and Light-Emitting Diode Circuits.

Science.gov (United States)

Jeon, Pyo Jin; Kim, Jin Sung; Lim, June Yeong; Cho, Youngsuk; Pezeshki, Atiye; Lee, Hee Sung; Yu, Sanghyuck; Min, Sung-Wook; Im, Seongil

2015-10-14

Two-dimensional (2D) semiconductor materials with discrete bandgap become important because of their interesting physical properties and potentials toward future nanoscale electronics. Many 2D-based field effect transistors (FETs) have thus been reported. Several attempts to fabricate 2D complementary (CMOS) logic inverters have been made too. However, those CMOS devices seldom showed the most important advantage of typical CMOS: low power consumption. Here, we adopted p-WSe2 and n-MoS2 nanosheets separately for the channels of bottom-gate-patterned FETs, to fabricate 2D dichalcogenide-based hetero-CMOS inverters on the same glass substrate. Our hetero-CMOS inverters with electrically isolated FETs demonstrate novel and superior device performances of a maximum voltage gain as ∼27, sub-nanowatt power consumption, almost ideal noise margin approaching 0.5VDD (supply voltage, VDD=5 V) with a transition voltage of 2.3 V, and ∼800 μs for switching delay. Moreover, our glass-substrate CMOS device nicely performed digital logic (NOT, OR, and AND) and push-pull circuits for organic light-emitting diode switching, directly displaying the prospective of practical applications.

Sine-wave three phase resonance inverter for operation of ...

African Journals Online (AJOL)

This paper proposes a high performance single-stage three phase inverter topology for the autonomous operation of renewable energy systems. The proposed configuration can boost the low voltage of renewable energy systems such as photo voltaic systems, fuel cells, and etc can also convert the output dc power, into ...

Low cost design of microprocessor EDAC circuit

International Nuclear Information System (INIS)

Hao Li; Yu Lixin; Peng Heping; Zhuang Wei

2015-01-01

An optimization method of error detection and correction (EDAC) circuit design is proposed. The method involves selecting or constructing EDAC codes of low cost hardware, associated with operation scheduling implementation based on 2-input XOR gates structure, and two actions for reducing hardware cells, which can reduce the delay penalties and area costs of the EDAC circuit effectively. The 32-bit EDAC circuit hardware implementation is selected to make a prototype, based on the 180 nm process. The delay penalties and area costs of the EDAC circuit are evaluated. Results show that the time penalty and area cost of the EDAC circuitries are affected with different parity-check matrices and different hardware implementation for the EDAC codes with the same capability of correction and detection code. This method can be used as a guide for low-cost radiation-hardened microprocessor EDAC circuit design and for more advanced technologies. (paper)

Efficiency Evaluation on a CoolMos Switching and IGBT Conducting Multilevel Inverter

DEFF Research Database (Denmark)

Anthon, Alexander; Zhang, Zhe; Andersen, Michael A. E.

2015-01-01

This paper deals with a three-level inverter topology in the 3 kW range as an alternative to commonly used three-level topologies. The topology is attractive for having low switching losses due to the utilization of CoolMos switching devices while keeping conduction losses low due to the utilizat......This paper deals with a three-level inverter topology in the 3 kW range as an alternative to commonly used three-level topologies. The topology is attractive for having low switching losses due to the utilization of CoolMos switching devices while keeping conduction losses low due...... to the utilization of IGBTs. A proper time delay between the CoolMos and IGBT devices increases the efficiency by 0.2%. Maximum efficiencies of 97.7 % are achieved and less than 0.2 % efficiency degradation is possible with doubled switching frequency. The case temperatures of the switching devices are below 60 ◦C...

DC-to-AC inverter ratio failure detector

Science.gov (United States)

Ebersole, T. J.; Andrews, R. E.

1975-01-01

Failure detection technique is based upon input-output ratios, which is independent of inverter loading. Since inverter has fixed relationship between V-in/V-out and I-in/I-out, failure detection criteria are based on this ratio, which is simply inverter transformer turns ratio, K, equal to primary turns divided by secondary turns.

Computational sensing of herpes simplex virus using a cost-effective on-chip microscope

KAUST Repository

Ray, Aniruddha

2017-07-03

Caused by the herpes simplex virus (HSV), herpes is a viral infection that is one of the most widespread diseases worldwide. Here we present a computational sensing technique for specific detection of HSV using both viral immuno-specificity and the physical size range of the viruses. This label-free approach involves a compact and cost-effective holographic on-chip microscope and a surface-functionalized glass substrate prepared to specifically capture the target viruses. To enhance the optical signatures of individual viruses and increase their signal-to-noise ratio, self-assembled polyethylene glycol based nanolenses are rapidly formed around each virus particle captured on the substrate using a portable interface. Holographic shadows of specifically captured viruses that are surrounded by these self-assembled nanolenses are then reconstructed, and the phase image is used for automated quantification of the size of each particle within our large field-of-view, ~30 mm2. The combination of viral immuno-specificity due to surface functionalization and the physical size measurements enabled by holographic imaging is used to sensitively detect and enumerate HSV particles using our compact and cost-effective platform. This computational sensing technique can find numerous uses in global health related applications in resource-limited environments.

Highly Flexible and High-Performance Complementary Inverters of Large-Area Transition Metal Dichalcogenide Monolayers

KAUST Repository

Pu, Jiang

2016-03-23

Complementary inverters constructed from large-area monolayers of WSe2 and MoS2 achieve excellent logic swings and yield an extremely high gain, large total noise margin, low power consumption, and good switching speed. Moreover, the WSe2 complementary-like inverters built on plastic substrates exhibit high mechanical stability. The results provide a path toward large-area flexible electronics. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Practical Implementation for the interval type-2 fuzzy PID controller using a low cost microcontroller

Directory of Open Access Journals (Sweden)

Ahmad M. El-Nagar

2014-06-01

Full Text Available In this study, we propose an embedded real-time interval type-2 fuzzy proportional – integral – derivative (IT2F-PID controller which is a parallel combination of the interval type-2 fuzzy proportional – integral (IT2F-PI controller and the interval type-2 fuzzy proportional – derivative (IT2F-PD controller. The proposed IT2F-PID controller is able to handle the effect of the system uncertainties due to the structure of the interval type-2 fuzzy logic controller. The proposed IT2F-PID controller is implemented practically using a low cost PIC microcontroller for controlling the uncertain nonlinear inverted pendulum to minimize the effect of the system uncertainties due to the uncertainty in the mass of the pendulum, the measurement error in the rotation angle of the pendulum and the structural uncertainty. The test is carried out using the hardware-in-the-loop (HIL simulation. The experimental results show that the performance of the IT2F-PID controller improves significantly the performance over a wide range of system uncertainties.

Inverting reflections using full-waveform inversion with inaccurate starting models

KAUST Repository

AlTheyab, Abdullah

2015-08-19

We present a method for inverting seismic reflections using full-waveform inversion (FWI) with inaccurate starting models. For a layered medium, near-offset reflections (with zero angle of incidence) are unlikely to be cycle-skipped regardless of the low-wavenumber velocity error in the initial models. Therefore, we use them as a starting point for FWI, and the subsurface velocity model is then updated during the FWI iterations using reflection wavepaths from varying offsets that are not cycle-skipped. To enhance low-wavenumber updates and accelerate the convergence, we take several passes through the non-linear Gauss-Seidel iterations, where we invert traces from a narrow range of near offsets and finally end at the far offsets. Every pass is followed by applying smoothing to the cumulative slowness update. The smoothing is strong at the early stages and relaxed at later iterations to allow for a gradual reconstruction of the subsurface model in a multiscale manner. Applications to synthetic and field data, starting from inaccurate models, show significant low-wavenumber updates and flattening of common-image gathers after many iterations.

Enhanced Buck-Boost Three-Level Neutral-Point-Clamped Inverters

DEFF Research Database (Denmark)

Tan, K. K.; Gao, F.; Chiang Loh, Poh

2009-01-01

In traditional three-level neutral-point-clamped (NPC) inverters, a major issue is capacitor voltage imbalance, which results in low order harmonics. The compensation of the capacitor voltages often require additional control complexity, which cannot be conveniently implemented. The "alternative...... phase opposition disposition" (APOD) modulation method used in traditional NPC topologies also has lower harmonics performance as compared to the "phase disposition" (PD) modulation method.In this paper, we introduce a new three-level NPC topology that utilises the harmonically superior PD modulation...... method, with the ability to easily adjust for capacitor voltage imbalances. To further improve the boost capability of the three-level NPC inverters, another new topology introduces 2 additional diodes,achieving higher boost performance while totally eliminating thepossibility of capacitor voltage...

NREL Evaluates Advanced Solar Inverter Performance for Hawaiian Electric

Science.gov (United States)

Companies | Energy Systems Integration Facility | NREL NREL Evaluates Advanced Solar Inverter Performance for Hawaiian Electric Companies NREL Evaluates Advanced Solar Inverter Performance for Hawaiian performance and impacts of today's advanced solar inverters, as well as proprietary feedback to the inverter

Utilizing social media and video games to control #DIY microscopes

Directory of Open Access Journals (Sweden)

Maxime Leblanc-Latour

2017-12-01

Full Text Available Open-source lab equipment is becoming more widespread with the popularization of fabrication tools such as 3D printers, laser cutters, CNC machines, open source microcontrollers and open source software. Although many pieces of common laboratory equipment have been developed, software control of these items is sometimes lacking. Specifically, control software that can be easily implemented and enable user-input and control over multiple platforms (PC, smartphone, web, etc.. The aim of this proof-of principle study was to develop and implement software for the control of a low-cost, 3D printed microscope. Here, we present two approaches which enable microscope control by exploiting the functionality of the social media platform Twitter or player actions inside of the videogame Minecraft. The microscope was constructed from a modified web-camera and implemented on a Raspberry Pi computer. Three aspects of microscope control were tested, including single image capture, focus control and time-lapse imaging. The Twitter embodiment enabled users to send ‘tweets’ directly to the microscope. Image data acquired by the microscope was then returned to the user through a Twitter reply and stored permanently on the photo-sharing platform Flickr, along with any relevant metadata. Local control of the microscope was also implemented by utilizing the video game Minecraft, in situations where Internet connectivity is not present or stable. A virtual laboratory was constructed inside the Minecraft world and player actions inside the laboratory were linked to specific microscope functions. Here, we present the methodology and results of these experiments and discuss possible limitations and future extensions of this work.

Characterization of process-induced damage in Cu/low-k interconnect structure by microscopic infrared spectroscopy with polarized infrared light

Energy Technology Data Exchange (ETDEWEB)

Seki, Hirofumi, E-mail: Hirofumi-Seki@trc.toray.co.jp; Hashimoto, Hideki [Toray Research Center, Inc., 3-3-7 Sonoyama, Otsu, Shiga 520-8567 (Japan); Ozaki, Yukihiro [Department of Chemistry, School of Science and Technology, Kwansei Gakuin University, 2-1, Gakuen, Sanda, Hyogo 669-1337 (Japan)

2016-09-07

Microscopic Fourier-transform infrared (FT-IR) spectra are measured for a Cu/low-k interconnect structure using polarized IR light for different widths of low-k spaces and Cu lines, and for different heights of Cu lines, on Si substrates. Although the widths of the Cu line and the low-k space are 70 nm each, considerably smaller than the wavelength of the IR light, the FT-IR spectra of the low-k film were obtained for the Cu/low-k interconnect structure. A suitable method was established for measuring the process-induced damage in a low-k film that was not detected by the TEM-EELS (Transmission Electron Microscope-Electron Energy-Loss Spectroscopy) using microscopic IR polarized light. Based on the IR results, it was presumed that the FT-IR spectra mainly reflect the structural changes in the sidewalls of the low-k films for Cu/low-k interconnect structures, and the mechanism of generating process-induced damage involves the generation of Si-OH groups in the low-k film when the Si-CH{sub 3} bonds break during the fabrication processes. The Si-OH groups attract moisture and the OH peak intensity increases. It was concluded that the increase in the OH groups in the low-k film is a sensitive indicator of low-k damage. We achieved the characterization of the process-induced damage that was not detected by the TEM-EELS and speculated that the proposed method is applicable to interconnects with line and space widths of 70 nm/70 nm and on shorter scales of leading edge devices. The location of process-induced damage and its mechanism for the Cu/low-k interconnect structure were revealed via the measurement method.

Pulsewidth-modulated 2-source neutral-point-clamped inverter

DEFF Research Database (Denmark)

Blaabjerg, Frede; Loh, Poh Chang; Gao, Feng

2007-01-01

This paper presents the careful integration of a newly proposed Z-source topological concept to the basic neutral-point-clamped (NPC) inverter topology for designing a three-level inverter with both voltage-buck and voltage-boost capabilities. The designed Z-source NPC inverter uses two unique X......-shaped inductance-capacitance (LC) impedance networks that are connected between two isolated dc input power sources and its inverter circuitry for boosting its AC output voltage. Through the design of an appropriate pulsewidth-modulation (PWM) algorithm, the two impedance networks can be short......-circuited sequentially (without shooting through the inverter full DC link) for implementing the ldquonearest-three-vectorrdquo modulation principle with minimized harmonic distortion and device commutations per half carrier cycle while performing voltage boosting. With only a slight modification to the inverter PWM...

Inverters for photovoltaics: quality assurance

International Nuclear Information System (INIS)

Graf, J.D.; Haeberlin, H.

2000-01-01

This project-overview published by the University of Applied Science in Burgdorf, Switzerland, looks back at the history of the university's testing laboratory for inverters for use in photovoltaic installations and discusses the work done there. After its move from Oberburg to Burgdorf in the early nineties, the laboratory was equipped to provide testing facilities for inverters up to 60 kW. Additions have been made to the infrastructure since then to facilitate the testing of various types of inverter produced in Switzerland and other countries. The measurements that can be carried out, including DC-AC conversion efficiency, harmonics, RF interference, islanding, sensitivity to tele-control signals, turn-on power and operating voltage range are described. The improvement in the quality of the inverters tested is discussed and the importance of continued testing as new manufacturers come onto the market is emphasised. The installation of further testing equipment, such as a 25 kW solar generator simulator and apparatus for the testing of maximum-power-tracking efficiency is discussed

Spray-deposited PEDOT:PSS for inverted organic solar cells

Energy Technology Data Exchange (ETDEWEB)

Weickert, Jonas; Sun, Haiyan; Palumbiny, Claudia; Hesse, Holger Christian; Schmidt-Mende, Lukas [Ludwig-Maximilians-University Munich, Department of Physics and Center for NanoScience (CeNS), Amalienstr. 54, 80799 Munich (Germany)

2010-12-15

The method of spray-depositing PEDOT:PSS allows the fabrication of thin films with controlled thickness on polymer layers. PEDOT:PSS is used in inverted ITO/TiO{sub 2}/P3HT:PCBM/PEDOT:PSS/Ag solar cells to optimize the work function of the hole-collecting electrode. The interlayer is also found to protect the organic layer during metal top deposition and improve the contact between P3HT-PCBM and the Ag electrode, which is confirmed using two different metal-deposition techniques; thermal evaporation and sputtering. Cells with PEDOT:PSS show full V{sub OC} and efficiency immediately after fabrication, whereas devices without PEDOT:PSS exhibit low performance in the beginning and improve significantly during the first 10 days after production. Devices are long-term stable if stored in the dark and in ambient air and show no significant performance decrease after 80 days. No inert nitrogen atmosphere is needed for any fabrication step, thus reducing the potential production costs since no glove box has to be used. (author)

Miniaturized Printed Inverted-F Antenna for Internet of Things: A Design on PCB with a Meandering Line and Shorting Strip

Directory of Open Access Journals (Sweden)

Cheuk Yin Cheung

2018-01-01

Full Text Available This paper focuses on a printed inverted-F antenna (PIFA with meandering line and meandering shorting strip under 2.4 GHz industrial, scientific, and medical (ISM band for Internet of things (IoT applications. Bluetooth Low Energy (BLE technology is one of potential platforms and technologies for IoT applications under ISM band. Printed circuit board (PCB antenna commonly used in commercial and medical applications because of its small size, low profile, and low cost compared to low temperature cofired ceramic (LTCC technology. The proposed structure of PIFA is implemented on PCB to gain all these advantages. Replacing conventional PCB line in PIFA by the meandering line and meandering shorting strip improves the efficiency of the PIFA as well as the bandwidth. As a case study, design and measurement results of the proposed PIFA are presented.

A hybrid damping method for LLCL-filter based grid-tied inverter with a digital filter and an RC parallel passive damper

DEFF Research Database (Denmark)

Wu, Weimin; Lin, Zhe; Sun, Yunjie

2013-01-01

Grid-tied inverters have been widely used to inject the renewable energies into the distributed power generation systems. However, a large variation of the grid impedance challenges the stability of the high-order power filter based grid-tied inverter. Many passive and active damping methods have...... been proposed to overcome this issue. Recently, a composite passive damping method for a high-order power filter based grid-tied inverter with an RC parallel damper and an RL series damper was presented to eliminate this problem, but at the cost of more material and power losses. In this paper...

On Stability of Voltage Source Inverters in Weak Grids

DEFF Research Database (Denmark)

Adib, Aswad; Mirafza, Behrooz; Wang, Xiongfei

2018-01-01

As the number of inverters increases in the power grid, the stability of grid-tied inverters becomes an important concern for the power industry. In particular, a weak grid can lead to voltage fluctuations at the inverter terminals and consequently cause inverter instability. In this paper, impac...

Hardness of deriving invertible sequences from finite state machines

DEFF Research Database (Denmark)

Hierons, Robert M.; Mousavi, Mohammad Reza; Thomsen, Michael Kirkedal

2017-01-01

invertible sequences; these allow one to construct additional UIOs once a UIO has been found. We consider three optimisation problems associated with invertible sequences: deciding whether there is a (proper) invertible sequence of length at least K; deciding whether there is a set of invertible sequences...

A Low-Cost Data Acquisition System for Automobile Dynamics Applications.

Science.gov (United States)

González, Alejandro; Olazagoitia, José Luis; Vinolas, Jordi

2018-01-27

This project addresses the need for the implementation of low-cost acquisition technology in the field of vehicle engineering: the design, development, manufacture, and verification of a low-cost Arduino-based data acquisition platform to be used in <80 Hz data acquisition in vehicle dynamics, using low-cost accelerometers. In addition to this, a comparative study is carried out of professional vibration acquisition technologies and low-cost systems, obtaining optimum results for low- and medium-frequency operations with an error of 2.19% on road tests. It is therefore concluded that these technologies are applicable to the automobile industry, thereby allowing the project costs to be reduced and thus facilitating access to this kind of research that requires limited resources.

A novel double quad-inverter configuration for multilevel twelve-phase open-winding converter

DEFF Research Database (Denmark)

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

2016-01-01

This paper describes a novel proposal of double quad-inverter configuration for multilevel twelve-phase open-winding ac converter. Modular power units are developed from reconfigured eight classical three-phase voltage source inverters (VSIs). Each VSI has one additional bi-directional switching...... numerical simulation software's (Matlab/PLECS) developments. Further, the results confirm the good agreement to the developed theoretical background. Proposed converter suits the need of low-voltage/high-current applications such as ac tractions and `More-Electric Aircraft' propulsion systems....

Spherical aberration correction in a scanning transmission electron microscope using a sculpted thin film.

Science.gov (United States)

Shiloh, Roy; Remez, Roei; Lu, Peng-Han; Jin, Lei; Lereah, Yossi; Tavabi, Amir H; Dunin-Borkowski, Rafal E; Arie, Ady

2018-06-01

Nearly eighty years ago, Scherzer showed that rotationally symmetric, charge-free, static electron lenses are limited by an unavoidable, positive spherical aberration. Following a long struggle, a major breakthrough in the spatial resolution of electron microscopes was reached two decades ago by abandoning the first of these conditions, with the successful development of multipole aberration correctors. Here, we use a refractive silicon nitride thin film to tackle the second of Scherzer's constraints and demonstrate an alternative method for correcting spherical aberration in a scanning transmission electron microscope. We reveal features in Si and Cu samples that cannot be resolved in an uncorrected microscope. Our thin film corrector can be implemented as an immediate low cost upgrade to existing electron microscopes without re-engineering of the electron column or complicated operation protocols and can be extended to the correction of additional aberrations. Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.

Towards Efficient Positional Inverted Index †

Directory of Open Access Journals (Sweden)

Petr Procházka

2017-02-01

Full Text Available We address the problem of positional indexing in the natural language domain. The positional inverted index contains the information of the word positions. Thus, it is able to recover the original text file, which implies that it is not necessary to store the original file. Our Positional Inverted Self-Index (PISI stores the word position gaps encoded by variable byte code. Inverted lists of single terms are combined into one inverted list that represents the backbone of the text file since it stores the sequence of the indexed words of the original file. The inverted list is synchronized with a presentation layer that stores separators, stop words, as well as variants of the indexed words. The Huffman coding is used to encode the presentation layer. The space complexity of the PISI inverted list is O ( ( N − n ⌈ log 2 b N ⌉ + ( ⌊ N − n α ⌋ + n × ( ⌈ log 2 b n ⌉ + 1 where N is a number of stems, n is a number of unique stems, α is a step/period of the back pointers in the inverted list and b is the size of the word of computer memory given in bits. The space complexity of the presentation layer is O ( − ∑ i = 1 N ⌈ log 2 p i n ( i ⌉ − ∑ j = 1 N ′ ⌈ log 2 p j ′ ⌉ + N with respect to p i n ( i as a probability of a stem variant at position i, p j ′ as the probability of separator or stop word at position j and N ′ as the number of separators and stop words.

A Hybrid, Current-Source/Voltage-Source Power Inverter Circuit

DEFF Research Database (Denmark)

Trzynadlowski, Andrzej M.; Patriciu, Niculina; Blaabjerg, Frede

2001-01-01

A combination of a large current-source inverter and a small voltage-source inverter circuits is analyzed. The resultant hybrid inverter inherits certain operating advantages from both the constituent converters. In comparison with the popular voltage-source inverter, these advantages include...... reduced switching losses, improved quality of output current waveforms, and faster dynamic response to current control commands. Description of operating principles and characteristics of the hybrid inverter is illustrated with results of experimental investigation of a laboratory model....

Switching Characteristics of Ferroelectric Transistor Inverters

Science.gov (United States)

Laws, Crystal; Mitchell, Coey; MacLeod, Todd C.; Ho, Fat D.

2010-01-01

This paper presents the switching characteristics of an inverter circuit using a ferroelectric field effect transistor, FeFET. The propagation delay time characteristics, phl and plh are presented along with the output voltage rise and fall times, rise and fall. The propagation delay is the time-delay between the V50% transitions of the input and output voltages. The rise and fall times are the times required for the output voltages to transition between the voltage levels V10% and V90%. Comparisons are made between the MOSFET inverter and the ferroelectric transistor inverter.

High-Efficient Low-Cost Photovoltaics Recent Developments

CERN Document Server

Petrova-Koch, Vesselinka; Goetzberger, Adolf

2009-01-01

A bird's-eye view of the development and problems of recent photovoltaic cells and systems and prospects for Si feedstock is presented. High-efficient low-cost PV modules, making use of novel efficient solar cells (based on c-Si or III-V materials), and low cost solar concentrators are in the focus of this book. Recent developments of organic photovoltaics, which is expected to overcome its difficulties and to enter the market soon, are also included.

Reverse or inverted apical ballooning in a case of refeeding syndrome.

Science.gov (United States)

Robles, Pablo; Monedero, Isabel; Rubio, Amador; Botas, Javier

2015-06-26

Takotsubo cardiomyopathy is characterized by the development of transient left ventricular regional wall motion abnormalities, in the absence of significant coronary artery obstruction. This syndrome usually occurs in women and is frequently associated with an intense emotional or physical stress. It usually involves apical segments, but in the recent years atypical forms have been described. Inverted or reverse Takotsubo is a variant in which the basal and midventricular segments are hypokinetic, sparing contractile function of the apex. In this report we describe the case of a 54-year-old woman, with chronic malnutrition, initially admitted because of hypoglycemia and severe electrolyte disturbance due to a refeeding syndrome. Within the next hours she experienced acute cardiac symptoms and developed heart failure with low cardiac output. Electrocardiogram (ECG), elevation of troponin and echocardiographic findings were consistent with inverted Takotsubo cardiomyopathy. To the best of our knowledge, this is the first incidence reported of inverted Takotsubo triggered by refeeding syndrome.

An extended dual input dual output three level Z source inverter with improved switch loss reduction technique

Directory of Open Access Journals (Sweden)

N.B. Deshmukh

2016-12-01

Full Text Available Multilevel inverter (MLI is a proven technology used for industrial applications due to low output total harmonic distortion (THD, high power handling capability and low active device rating. Dual output inverter is a recent trend associated with inverter topologies for specialized applications. This paper deals with three phase three level dual input dual output inverter topology with minimum active device count. Reduction in switch count leads to reduction in losses and improves reliability. Both the input sources share power equally as neutral point current ripple is maintained low. For further reduction in switching losses at higher switching frequencies, the concept of “no switching zone” or discontinuous pulse width modulation (DPWM has been put forth recently. This paper proposes modification in the placement of “no switching zone” in order to optimize switching losses and output THD (output filtering requirements for low power factor load. This study also proposes novel graphical approach to analyze the loss reduction along with its effect on output THD. The sinusoidal PWM (SPWM is used which gives satisfactory switching loss reduction without complex calculations. Moreover, the proposed topology is generalized to provide dual output at higher voltage levels. It is seen that the components reduction phenomenon becomes more pronounced as number of levels goes on increasing. The proposed converter is simulated in MATLAB software environment and results are obtained.

An easily accessible carbon material derived from carbonization of polyacrylonitrile ultrathin films: ambipolar transport properties and application in a CMOS-like inverter.

Science.gov (United States)

Jiao, Fei; Zhang, Fengjiao; Zang, Yaping; Zou, Ye; Di, Chong'an; Xu, Wei; Zhu, Daoben

2014-03-04

Ultrathin carbon films were prepared by carbonization of a solution processed polyacrylonitrile (PAN) film in a moderate temperature range (500-700 °C). The films displayed balanced hole (0.50 cm(2) V(-1) s(-1)) and electron mobilities (0.20 cm(2) V(-1) s(-1)) under ambient conditions. Spectral characterization revealed that the electrical transport is due to the formation of sp(2) hybridized carbon during the carbonization process. A CMOS-like inverter demonstrated the potential application of this material in the area of carbon electronics, considering its processability and low-cost.

Optical incremental rotary encoder in low-cost-design; Optischer inkrementaler Drehgeber in Low-Cost-Bauweise

Energy Technology Data Exchange (ETDEWEB)

Hopp, David; Pruss, Christof; Osten, Wolfgang [Stuttgart Univ. (Germany). Inst. fuer Technische Optik; Seybold, Jonathan; Mayer, Volker [Hans-Schickard-Gesellschaft, Stuttgart (DE). Inst. fuer Mikroaufbautechnik (IMAT); Kueck, Heinz [Hans-Schickard-Gesellschaft, Stuttgart (DE). Inst. fuer Mikroaufbautechnik (IMAT); Stuttgart Univ. (Germany). Inst. fuer Zeitmesstechnik, Fein- und Mikrotechnik

2010-07-01

We have developed a new concept for low-cost optical encoders to come up to meet the increasing demand for inexpensive rotary sensors. The principal idea is to use a micro patterned plastic disc with metal coating, as it is used for Compact Discs or DVDs. Such encoder discs can be manufactured by an efficient injection compression moulding process. With this well established technique it is possible to achieve highly precise micro patterns while running a cost effective process for high volume production. (orig.)

Evaluating Moisture Control of Variable-Capacity Heat Pumps in Mechanically Ventilated, Low-Load Homes in Climate Zone 2A

Energy Technology Data Exchange (ETDEWEB)

Eric Martin, Chuck Withers, Janet McIlvaine, Dave Chasar, and David Beal

2018-03-29

Low-load homes can present a challenge when selecting appropriate space-conditioning equipment. Conventional, fixed-capacity heating and cooling equipment is often oversized for small homes, causing increased first costs and operating costs. This report evaluates the performance of variable-capacity comfort systems, with a focus on inverter-driven, variable-capacity systems, as well as proposed system enhancements.

On-state voltage drop based power limit detection of IGBT inverters

DEFF Research Database (Denmark)

Trintis, Ionut; Ghimire, Pramod; Munk-Nielsen, Stig

2015-01-01

Power density is a key performance factor in order to reduce the cost and size of a power converter. Because of the unknown junction temperature, today’s design margins are relatively high to ensure safe and a reliable operation. In this paper, the on-state voltage drop is measured online for all...... insulated gate bipolar transistors (IGBTs) in the inverter, using advanced gate driver. The die temperature is estimated and monitored on each device during power converter operation. Based on the monitored temperature in real time, the maximum power capability is detected. The output power is increased...... until a safe operating temperature of power modules. This enable a power density is increased by 11.16 kW/litre to 19.13 kW/litre in a low voltage power stack which is typically used in wind power converters. Experiment results are shown for safe operation of converter at around 1.2 MW, which is built...

Development of low-cost digital subtraction angiography system

International Nuclear Information System (INIS)

Ando, Yutaka; Kobayashi, Takeshi; Imai, Yutaka; Yagishita, Akira; Kunieda, Etsuo.

1983-01-01

We developed a simple and low-cost DSA system. This system consists of a conventional fluoroscopic equipment for the GI tract and a mini-computer (GAMMA-11) which are connected each other with a video-disc recorder. The uniqueness of our system are 1. low-cost, 2. low-radiation dose, 3. off-line processing, 4. flexibility of software. The analysis of the time-density curve and image processing will bring us a more usefull information than DSA alone. (author)

Transistorized PWM inverter-induction motor drive system

Science.gov (United States)

Peak, S. C.; Plunkett, A. B.

1982-01-01

This paper describes the development of a transistorized PWM inverter-induction motor traction drive system. A vehicle performance analysis was performed to establish the vehicle tractive effort-speed requirements. These requirements were then converted into a set of inverter and motor specifications. The inverter was a transistorized three-phase bridge using General Electric power Darlington transistors. The description of the design and development of this inverter is the principal object of this paper. The high-speed induction motor is a design which is optimized for use with an inverter power source. The primary feedback control is a torque angle control with voltage and torque outer loop controls. A current-controlled PWM technique is used to control the motor voltage. The drive has a constant torque output with PWM operation to base motor speed and a constant horsepower output with square wave operation to maximum speed. The drive system was dynamometer tested and the results are presented.

THD Minimization from H-Bridge Cascaded Multilevel Inverter Using Particle Swarm Optimization Technique

Directory of Open Access Journals (Sweden)

MUDASIR AHMED MEMON

2017-01-01

Full Text Available In this paper, PSO (Particle Swarm Optimization based technique is proposed to derive optimized switching angles that minimizes the THD (Total Harmonic Distortion and reduces the effect of selected low order non-triple harmonics from the output of the multilevel inverter. Conventional harmonic elimination techniques have plenty of limitations, and other heuristic techniques also not provide the satisfactory results. In this paper, single phase symmetrical cascaded H-Bridge 11-Level multilevel inverter is considered, and proposed algorithm is utilized to obtain the optimized switching angles that reduced the effect of 5th, 7th, 11th and 13th non-triplen harmonics from the output voltage of the multilevel inverter. A simulation result indicates that this technique outperforms other methods in terms of minimizing THD and provides high-quality output voltage waveform.

THD minimization from h-bridge cascaded multilevel inverter using particle swarm optimization technique

International Nuclear Information System (INIS)

Memon, M.A.; Memon, S.; Khan, S.

2017-01-01

In this paper, PSO (Particle Swarm Optimization) based technique is proposed to derive optimized switching angles that minimizes the THD (Total Harmonic Distortion) and reduces the effect of selected low order non-triple harmonics from the output of the multilevel inverter. Conventional harmonic elimination techniques have plenty of limitations, and other heuristic techniques also not provide the satisfactory results. In this paper, single phase symmetrical cascaded H-Bridge 11-Level multilevel inverter is considered, and proposed algorithm is utilized to obtain the optimized switching angles that reduced the effect of 5th, 7th, 11th and 13th non-triplen harmonics from the output voltage of the multilevel inverter. A simulation result indicates that this technique outperforms other methods in terms of minimizing THD and provides high-quality output voltage waveform. (author)

A Soft-Switching Inverter for High-Temperature Advanced Hybrid Electric Vehicle Traction Motor Drives

Energy Technology Data Exchange (ETDEWEB)

Lai, Jason [Virginia Polytechnic Inst. and State Univ. (Virginia Tech), Blacksburg, VA (United States); Yu, Wensong [Virginia Polytechnic Inst. and State Univ. (Virginia Tech), Blacksburg, VA (United States); Sun, Pengwei [Virginia Polytechnic Inst. and State Univ. (Virginia Tech), Blacksburg, VA (United States); Leslie, Scott [Powerex, Inc., Harrison, OH (United States); Prusia, Duane [Powerex, Inc., Harrison, OH (United States); Arnet, Beat [Azure Dynamics, Oak Park, MI (United States); Smith, Chris [Azure Dynamics, Oak Park, MI (United States); Cogan, Art [Azure Dynamics, Oak Park, MI (United States)

2012-03-31

The state-of-the-art hybrid electric vehicles (HEVs) require the inverter cooling system to have a separate loop to avoid power semiconductor junction over temperatures because the engine coolant temperature of 105°C does not allow for much temperature rise in silicon devices. The proposed work is to develop an advanced soft-switching inverter that will eliminate the device switching loss and cut down the power loss so that the inverter can operate at high-temperature conditions while operating at high switching frequencies with small current ripple in low inductance based permanent magnet motors. The proposed tasks also include high-temperature packaging and thermal modeling and simulation to ensure the packaged module can operate at the desired temperature. The developed module will be integrated with the motor and vehicle controller for dynamometer and in-vehicle testing to prove its superiority. This report will describe the detailed technical design of the soft-switching inverters and their test results. The experiments were conducted both in module level for the module conduction and switching characteristics and in inverter level for its efficiency under inductive and dynamometer load conditions. The performance will be compared with the DOE original specification.

A new high-efficiency single-phase transformerless PV inverter topology

DEFF Research Database (Denmark)

Kerekes, Tamas; Teodorescu, Remus; Rodriguez, Pedro

2011-01-01

There is a strong trend in the photovoltaic (PV) inverter technology to use transformerless topologies in order to acquire higher efficiencies combining with very low ground leakage current. In this paper a new topology, based on the H-Bridge with a new AC bypass circuit consisting in a diode...

Improved Droop Control Strategy for Grid-Connected Inverters

DEFF Research Database (Denmark)

Abusara, Mohammad; Sharkh, Suleiman; Guerrero, Josep M.

2015-01-01

An improved control strategy for grid-connected inverters within microgrids is presented in this paper. The strategy is based on the classical P-ω and Q-V droop method. The improvement in the proposed control strategy is twofold: Firstly, the transient response of the droop controller is improved...... by replacing the traditional method of measuring average power, which is based on using a first order low pass filter, by a real time integration filter. This is shown to reduce the imported transient energy when connecting to the grid. Secondly, the steady state output current quality is improved by utilising...... a virtual inductance, which is shown to reject grid voltage harmonics disturbance and thus improve the output current THD. A small signal model of the inverter based on the transfer function approach is developed to analyse is stability and determine droop gains. Simulation and experimental results...

Integral inverter/battery charger for use in electric vehicles

Science.gov (United States)

Thimmesch, D.

1983-01-01

The design and test results of a thyristor based inverter/charger are discussed. A battery charger is included integral to the inverter by using a subset of the inverter power circuit components. The resulting charger provides electrical isolation between the vehicle propulsion battery and ac line and is capable of charging a 25 kWh propulsion battery in 8 hours from a 220 volt ac line. The integral charger employs the inverter commutation components at a resonant ac/dc isolated converter rated at 3.6 kW. Charger efficiency and power factor at an output power of 3.6 kW are 86% and 95% respectively. The inverter, when operated with a matching polyphase ac induction motor and nominal 132 volt propulsion battery, can provide a peak shaft power of 34 kW (45 ph) during motoring operation and 45 kW (60 hp) during regeneration. Thyristors are employed for the inverter power switching devices and are arranged in an input-commutated topology. This configuration requires only two thyristors to commutate the six main inverter thyristors. Inverter efficiency during motoring operation at motor shaft speeds above 450 rad/sec (4300 rpm) is 92-94% for output power levels above 11 KW (15 hp). The combined ac inverter/charger package weighs 47 kg (103 lbs).

Design optimization of grid-connected PV inverters

DEFF Research Database (Denmark)

Koutroulis, Eftichios; Blaabjerg, Frede

2011-01-01

The DC/AC inverters are the key elements in grid-connected PV energy production systems. In this paper, new design optimization techniques focused on transformerless (very high efficiency) PV inverters are proposed. They have been developed based on an analysis of the deficiencies of the current......, state-of-the-art PV inverters design technology, which limits the amount of PV energy supplied into the electric grid. The influences of the electric grid regulations and standards and the PV array operational characteristics on the design of grid-connected PV inverters have also been considered....... The simulation results verify that the proposed optimization techniques enable the maximization of the PV energy injected into the electric grid by the optimized PV installation....

Advanced DC/AC inverters applications in renewable energy

CERN Document Server

Luo, Fang Lin

2013-01-01

DC/AC inversion technology is of vital importance for industrial applications, including electrical vehicles and renewable energy systems, which require a large number of inverters. In recent years, inversion technology has developed rapidly, with new topologies improving the power factor and increasing power efficiency. Proposing many novel approaches, Advanced DC/AC Inverters: Applications in Renewable Energy describes advanced DC/AC inverters that can be used for renewable energy systems. The book introduces more than 100 topologies of advanced inverters originally developed by the authors,

The Benefits of SiC MOSFETs in a T-Type Inverter for Grid-Tie Applications

DEFF Research Database (Denmark)

Anthon, Alexander; Zhang, Zhe; Andersen, Michael A. E.

2016-01-01

at the expense of increased switching losses since these outer switches must now block the full DC link voltage. Silicon Carbide (SiC) MOSFET devices potentially offer substantial advantage in this context with their lower switching losses, but the benefit of replacing all switching devices in a T-Type inverter...... with SiC MOSFETs is not so clear-cut. This paper now explores this issue by presenting a detailed comparison of the use of Si and SiC devices for a three-level T-Type inverter operating in grid-tie applications. The study uses datasheet values, switching loss measurements and calibrated heat sink thermal...... power level or the switching frequency to be significantly increased for the same device losses. Hence the use of SiC MOSFETS for T-Type inverters can be seen to be an attractive and potentially cost effective alternative, since only two switching devices per phase leg need to be upgraded....

Five-Level Z-Source Neutral Point-Clamped Inverter

DEFF Research Database (Denmark)

Gao, F.; Loh, P.C.; Blaabjerg, Frede

2007-01-01

This paper proposes a five-level Z-source neutralpoint- clamped (NPC) inverter with two Z-source networks functioning as intermediate energy storages coupled between dc sources and NPC inverter circuitry. Analyzing the operational principles of Z-source network with partial dclink shoot......-through scheme reveals the hidden theories in the five-level Z-source NPC inverter unlike the operational principle appeared in the general two-level Z-source inverter, so that the five-level Z-source NPC inverter can be designed with the modulation of carrier-based phase disposition (PD) or alternative phase...

Large-Signal Lyapunov-Based Stability Analysis of DC/AC Inverters and Inverter-Based Microgrids

Science.gov (United States)

Kabalan, Mahmoud

Microgrid stability studies have been largely based on small-signal linearization techniques. However, the validity and magnitude of the linearization domain is limited to small perturbations. Thus, there is a need to examine microgrids with large-signal nonlinear techniques to fully understand and examine their stability. Large-signal stability analysis can be accomplished by Lyapunov-based mathematical methods. These Lyapunov methods estimate the domain of asymptotic stability of the studied system. A survey of Lyapunov-based large-signal stability studies showed that few large-signal studies have been completed on either individual systems (dc/ac inverters, dc/dc rectifiers, etc.) or microgrids. The research presented in this thesis addresses the large-signal stability of droop-controlled dc/ac inverters and inverter-based microgrids. Dc/ac power electronic inverters allow microgrids to be technically feasible. Thus, as a prelude to examining the stability of microgrids, the research presented in Chapter 3 analyzes the stability of inverters. First, the 13 th order large-signal nonlinear model of a droop-controlled dc/ac inverter connected to an infinite bus is presented. The singular perturbation method is used to decompose the nonlinear model into 11th, 9th, 7th, 5th, 3rd and 1st order models. Each model ignores certain control or structural components of the full order model. The aim of the study is to understand the accuracy and validity of the reduced order models in replicating the performance of the full order nonlinear model. The performance of each model is studied in three different areas: time domain simulations, Lyapunov's indirect method and domain of attraction estimation. The work aims to present the best model to use in each of the three domains of study. Results show that certain reduced order models are capable of accurately reproducing the performance of the full order model while others can be used to gain insights into those three areas of

Analysis of Magnetically-Coupled Impedance Source Three-Phase Four-Switch Inverters

DEFF Research Database (Denmark)

Li, Kerui; Abdelhakim, Ahmed; Yang, Yongheng

2017-01-01

In this paper, magnetically-coupled impedance source (MCIS) three-phase four-switch inverters are introduced for renewable energy applications. This inverter utilizes two single-phase MCIS inverters to obtain a three-phase output, where less component-count is achieved in order to reduce the inve......In this paper, magnetically-coupled impedance source (MCIS) three-phase four-switch inverters are introduced for renewable energy applications. This inverter utilizes two single-phase MCIS inverters to obtain a three-phase output, where less component-count is achieved in order to reduce...... the inverter volume. On the other hand, as a result of the reduced number of switches, the proposed inverter suffers from higher voltage stresses. The MCIS inverters are first reviewed. Then, the modulation and operation principle of the MCIS three-phase inverter topology are introduced before sizing...

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

Directory of Open Access Journals (Sweden)

Shan Yang

2016-01-01

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

Organizing for low cost space operations - Status and plans

Science.gov (United States)

Lee, C.

1976-01-01

Design features of the Space Transportation System (vehicle reuse, low cost expendable components, simple payload interfaces, standard support systems) must be matched by economical operational methods to achieve low operating and payload costs. Users will be responsible for their own payloads and will be charged according to the services they require. Efficient use of manpower, simple documentation, simplified test, checkout, and flight planning are firm goals, together with flexibility for quick response to varying user needs. Status of the Shuttle hardware, plans for establishing low cost procedures, and the policy for user charges are discussed.

Comparative study of SiC- and Si-based photovoltaic inverters

Science.gov (United States)

Ando, Yuji; Oku, Takeo; Yasuda, Masashi; Shirahata, Yasuhiro; Ushijima, Kazufumi; Murozono, Mikio

2017-01-01

This article reports comparative study of 150-300 W class photovoltaic inverters (Si inverter, SiC inverter 1, and SiC inverter 2). In these sub-kW class inverters, the ON-resistance was considered to have little influence on the efficiency. The developed SiC inverters, however, have exhibited an approximately 3% higher direct current (DC)-alternating current (AC) conversion efficiency as compared to the Si inverter. Power loss analysis indicated a reduction in the switching and reverse recovery losses of SiC metal-oxide-semiconductor field-effect transistors used for the DC-AC converter is responsible for this improvement. In the SiC inverter 2, an increase of the switching frequency up to 100 kHz achieved a state-of-the-art combination of the weight (1.25 kg) and the volume (1260 cm3) as a 150-250 W class inverter. Even though the increased switching frequency should cause the increase of the switching losses, the SiC inverter 2 exhibited an efficiency comparable to the SiC inverter 1 with a switching frequency of 20 kHz. The power loss analysis also indicated a decreased loss of the DC-DC converter built with SiC Schottky barrier diodes led to the high efficiency for its increased switching frequency. These results clearly indicated feasibility of SiC devices even for sub-kW photovoltaic inverters, which will be available for the applications where compactness and efficiency are of tremendous importance.

Effect of Asymmetric Layout of IGBT Modules on Reliability of Power Inverters in Motor Drive System

DEFF Research Database (Denmark)

Choi, Uimin; Vernica, Ionut; Blaabjerg, Frede

2018-01-01

of inverters are limited by the most stressed devices. However, generally common data is provided for all devices and this may cause improper design of the inverters in terms of power rating and lifetime. In this paper, the effect of an asymmetric layout of IGBT modules on the reliability of power inverters......An IGBT module has typically multiple power devices for some technical and cost advantages. This kind of configurations could have an asymmetric layout, which may lead to different thermal loadings and thereby lifetime difference of the power devices. Therefore, both the power rating and lifetime...... is studied based on a 3-phase motor drive application with a 600 V, 30 A, 3-phase transfer molded IGBT module. The thermal impedances of 6 IGBTs are investigated and its effect on the thermal loadings of power devices is studied under the given mission profile. Finally, their lifetimes are estimated...

Power Hardware-in-the-Loop Evaluation of PV Inverter Grid Support on Hawaiian Electric Feeders: Preprint

Energy Technology Data Exchange (ETDEWEB)

Nelson, Austin; Prabakar, Kumaraguru; Nagarajan, Adarsh; Nepal, Shaili; Hoke, Anderson; Asano, Marc; Ueda, Reid; Ifuku, Earle

2017-05-08

As more grid-connected photovoltaic (PV) inverters become compliant with evolving interconnections requirements, there is increased interest from utilities in understanding how to best deploy advanced grid-support functions (GSF) in the field. One efficient and cost-effective method to examine such deployment options is to leverage power hardware-in-the-loop (PHIL) testing methods. Two Hawaiian Electric feeder models were converted to real-time models in the OPAL-RT real-time digital testing platform, and integrated with models of GSF capable PV inverters that were modeled from characterization test data. The integrated model was subsequently used in PHIL testing to evaluate the effects of different fixed power factor and volt-watt control settings on voltage regulation of the selected feeders. The results of this study were provided as inputs for field deployment and technical interconnection requirements for grid-connected PV inverters on the Hawaiian Islands.

Low-cost, low-weight CNG cylinder development. Final report

Energy Technology Data Exchange (ETDEWEB)

Richards, Mark E.; Melford, K.; Wong, J.; Gambone, L.

1999-09-01

This program was established to develop and commercialize new high-strength steel-lined, composite hoop-wrapped compressed natural gas (CNG) cylinders for vehicular applications. As much as 70% of the cost of natural gas vehicles can be related to on-board natural gas storage costs. The cost and weight targets for this program represent significant savings in each characteristic when compared to comparable containers available at the initiation of the program. The program objectives were to optimize specific weight and cost goals, yielding CNG cylinders with dimensions that should, allowing for minor modifications, satisfy several vehicle market segments. The optimization process encompassed material, design, and process improvement. In optimizing the CNG cylinder design, due consideration was given to safety aspects relative to national, international, and vehicle manufacturer cylinder standards and requirements. The report details the design and development effort, encompassing plant modifications, material selection, design issues, tooling development, prototype development, and prototype testing. Extenuating circumstances prevented the immediate commercialization of the cylinder designs, though significant progress was made towards improving the cost and performance of CNG cylinders. A new low-cost fiber was successfully employed while the weight target was met and the cost target was missed by less than seven percent.

Distribution Grid Integration Unit Cost Database | Solar Research | NREL

Science.gov (United States)

consulting companies, IEEE Some data is provided to give a sense of the order of magnitude of the lifetime , as O&M and component lifetime data is sparse, the effects of PV on device O&M and lifetimes Inverter manufacturers, PV developers The cost of advanced inverters depends on whether the capability of

Low-cost uncooled VOx infrared camera development

Science.gov (United States)

Li, Chuan; Han, C. J.; Skidmore, George D.; Cook, Grady; Kubala, Kenny; Bates, Robert; Temple, Dorota; Lannon, John; Hilton, Allan; Glukh, Konstantin; Hardy, Busbee

2013-06-01

The DRS Tamarisk® 320 camera, introduced in 2011, is a low cost commercial camera based on the 17 µm pixel pitch 320×240 VOx microbolometer technology. A higher resolution 17 µm pixel pitch 640×480 Tamarisk®640 has also been developed and is now in production serving the commercial markets. Recently, under the DARPA sponsored Low Cost Thermal Imager-Manufacturing (LCTI-M) program and internal project, DRS is leading a team of industrial experts from FiveFocal, RTI International and MEMSCAP to develop a small form factor uncooled infrared camera for the military and commercial markets. The objective of the DARPA LCTI-M program is to develop a low SWaP camera (costs less than US $500 based on a 10,000 units per month production rate. To meet this challenge, DRS is developing several innovative technologies including a small pixel pitch 640×512 VOx uncooled detector, an advanced digital ROIC and low power miniature camera electronics. In addition, DRS and its partners are developing innovative manufacturing processes to reduce production cycle time and costs including wafer scale optic and vacuum packaging manufacturing and a 3-dimensional integrated camera assembly. This paper provides an overview of the DRS Tamarisk® project and LCTI-M related uncooled technology development activities. Highlights of recent progress and challenges will also be discussed. It should be noted that BAE Systems and Raytheon Vision Systems are also participants of the DARPA LCTI-M program.

Arsenic removal from groundwater using low-cost carbon composite electrodes for capacitive deionization.

Science.gov (United States)

Lee, Ju-Young; Chaimongkalayon, Nantanee; Lim, Jinho; Ha, Heung Yong; Moon, Seung-Hyeon

2016-01-01

Affordable carbon composite electrodes were developed to treat low-concentrated groundwater using capacitive deionization (CDI). A carbon slurry prepared using activated carbon powder (ACP), poly(vinylidene fluoride), and N-methyl-2-pyrrolidone was employed as a casting solution to soak in a low-cost porous substrate. The surface morphology of the carbon composite electrodes was investigated using a video microscope and scanning electron microscopy. The capacitance and electrical conductivity of the carbon composite electrodes were then examined using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), respectively. According to the CV and EIS measurements, the capacitances and electrical conductivities of the carbon composite electrodes were in the range of 8.35-63.41 F g(-1) and 0.298-0.401 S cm(-1), respectively, depending on ACP contents. A CDI cell was assembled with the carbon composite electrodes instead of with electrodes and current collectors. The arsenate removal test included an investigation of the optimization of several important operating parameters, such as applied voltage and solution pH, and it achieved 98.8% removal efficiency using a 1 mg L(-1) arsenate solution at a voltage of 2 V and under a pH 9 condition.

Harmonic mitigation in islanded microgrids by inverter-interfaced distributed energy resource

Energy Technology Data Exchange (ETDEWEB)

Xiongfei Wang

2012-10-15

An exciting growth of microgrids market has been witnessed around the world, driven on one hand by the increasing deployment of Distributed Energy Resource (DER) and on the other hand by the ongoing transformations of electric power systems towards more decentralized, intelligent, and resilient networks. The ability of dynamic islanding furnishes microgrids a prominent feature, which not only contributes to a more reliable electricity supply but also provides a systematic way to maximize the benefits of DER units for both customers and utilities. However, during islanded operations, microgrids are more sensitive to power quality disturbances, owing to the low short circuit ratio and limited capacity of DER units. As a consequence, harmonic distortion caused by the proliferation of nonlinear electronic equipment becomes more apparent. The recently released IEEE 1547 series standards have outlined the acceptable harmonic voltage and current distortion limits for islanded operations of microgrids. This thesis concentrates on developing advanced control algorithms for DER inverters in order to provide active harmonic conditioning services, including harmonic voltage reduction, harmonic current filtering and resonance damping in islanded microgrids. The research work is composed of two main parts. The first part is concerned with building a stable islanded microgrid, where the reduction of circulating current in the parallel DER inverters is studied. The second part addresses the harmonic distortion resulting from nonlinear loads and shunt-connected capacitors via the different control algorithms of DER inverters. Furthermore, to establish the basic control aspects for the islanded microgrid built in this project, a wide variety of control schemes for DER inverters within an islanded microgrid environment are evaluated. The merits and demerits of the different control methods are discussed. In light of this, the hierarchical control system is adopted, including the

Variable speed wind turbine generator system with current controlled voltage source inverter

International Nuclear Information System (INIS)

Muyeen, S.M.; Al-Durra, Ahmed; Tamura, J.

2011-01-01

highlights: → Current controlled voltage source inverter scheme for wind power application. → Low voltage ride through of wind farm. → Variable speed wind turbine driven permanent magnet synchronous generator-operation and control. -- Abstract: The present popular trend of wind power generation is to use variable speed wind turbine (VSWT) driving a doubly fed induction generator (DFIG), wound field synchronous generator (WFSG) or permanent magnet synchronous generator (PMSG). Among them, stability analyses of DFIG type of VSWT have already been reported in many literatures. However, transient stability and low voltage ride through (LVRT) characteristics analyses for synchronous generator type of VSWT is not sufficient enough. This paper focuses on detailed LVRT characteristic analysis of variable speed wind turbine driving a PMSG (VSWT-PMSG) with current controlled voltage source inverter (CC-VSI). Modeling and suitable control strategies for overall system are developed to augment the low voltage ride through capability of variable speed wind generator, considering recent wind farm grid code. Both symmetrical and unsymmetrical faults are analyzed as network disturbances in this paper. The permanent fault due to unsuccessful reclosing of circuit breakers is taken into consideration, which is a salient feature of this study. Moreover, the dynamic characteristic is analyzed using real wind speed data measured in Hokkaido Island, Japan. The proposed control scheme is simulated by using the standard power system simulation package PSCAD/EMTDC and results are verified by comparing that of voltage controlled voltage source inverter scheme available in power system literature.

Variable speed wind turbine generator system with current controlled voltage source inverter

Energy Technology Data Exchange (ETDEWEB)

Muyeen, S.M., E-mail: muyeen0809@yahoo.co [Dept. of Electrical Engineering, Petroleum Institute, P.O. Box 2533, Abu Dhabi (United Arab Emirates); Al-Durra, Ahmed [Dept. of Electrical Engineering, The Petroleum Institute, P.O. Box 2533, Abu Dhabi (United Arab Emirates); Tamura, J. [Dept. of EEE, Kitami Institute of Technology, 165 Koen-cho, Kitami 090-8507 (Japan)

2011-07-15

highlights: {yields} Current controlled voltage source inverter scheme for wind power application. {yields} Low voltage ride through of wind farm. {yields} Variable speed wind turbine driven permanent magnet synchronous generator-operation and control. -- Abstract: The present popular trend of wind power generation is to use variable speed wind turbine (VSWT) driving a doubly fed induction generator (DFIG), wound field synchronous generator (WFSG) or permanent magnet synchronous generator (PMSG). Among them, stability analyses of DFIG type of VSWT have already been reported in many literatures. However, transient stability and low voltage ride through (LVRT) characteristics analyses for synchronous generator type of VSWT is not sufficient enough. This paper focuses on detailed LVRT characteristic analysis of variable speed wind turbine driving a PMSG (VSWT-PMSG) with current controlled voltage source inverter (CC-VSI). Modeling and suitable control strategies for overall system are developed to augment the low voltage ride through capability of variable speed wind generator, considering recent wind farm grid code. Both symmetrical and unsymmetrical faults are analyzed as network disturbances in this paper. The permanent fault due to unsuccessful reclosing of circuit breakers is taken into consideration, which is a salient feature of this study. Moreover, the dynamic characteristic is analyzed using real wind speed data measured in Hokkaido Island, Japan. The proposed control scheme is simulated by using the standard power system simulation package PSCAD/EMTDC and results are verified by comparing that of voltage controlled voltage source inverter scheme available in power system literature.

Experimental studies and microscopic analysis of the elastic scattering of low energy nucleons

International Nuclear Information System (INIS)

Tarrats-Saugnac, Annie.

1982-05-01

Data on the elastic scattering of low energy nucleons (between 20 and 40 MeV) by nuclei distributed throughout the entire mass table are examined in the framework of a microscopic approach. Two major problems occur at these low energies which do not occur at higher energies: the Pauli principle limits the interaction possibilities of projectiles with bound nucleons in the nucleus; it is not possible to neglect the antisymmetrization between projectiles and nucleon targets resulting in the addition of a nonlocal term to the potential. A quadratic moment approximation is used. As regards the inhibition of reactions inside the nucleus by the Pauli principle, an effective interaction with a relatively simple analytical form and easy to use for systematic analyses was determined [fr

Transient Monitoring Function–Based Fault Detection for Inverter-Interfaced Microgrids

DEFF Research Database (Denmark)

Sadeghkhani, Iman; Esmail Hamedani Golshan, Mohamad; Mehrizi-Sani, Ali

2018-01-01

One of the major challenges in protection of the inverter-interfaced islanded microgrids is their limited fault current level. This degrades the performance of traditional overcurrent protection schemes. This paper proposes a fault detection strategy based on monitoring the transient response......-domain simulation case studies using the CIGRE benchmark low voltage microgrid network....

Costs of mixed low-level waste stabilization options

International Nuclear Information System (INIS)

Schwinkendorf, W.E.; Cooley, C.R.

1998-01-01

Selection of final waste forms to be used for disposal of DOE's mixed low-level waste (MLLW) depends on the waste form characteristics and total life cycle cost. In this paper the various cost factors associated with production and disposal of the final waste form are discussed and combined to develop life-cycle costs associated with several waste stabilization options. Cost factors used in this paper are based on a series of treatment system studies in which cost and mass balance analyses were performed for several mixed low-level waste treatment systems and various waste stabilization methods including vitrification, grout, phosphate bonded ceramic and polymer. Major cost elements include waste form production, final waste form volume, unit disposal cost, and system availability. Production of grout costs less than the production of a vitrified waste form if each treatment process has equal operating time (availability) each year; however, because of the lower volume of a high temperature slag, certification and handling costs and disposal costs of the final waste form are less. Both the total treatment cost and life cycle costs are higher for a system producing grout than for a system producing high temperature slag, assuming equal system availability. The treatment costs decrease with increasing availability regardless of the waste form produced. If the availability of a system producing grout is sufficiently greater than a system producing slag, then the cost of treatment for the grout system will be less than the cost for the slag system, and the life cycle cost (including disposal) may be less depending on the unit disposal cost. Treatment and disposal costs will determine the return on investment in improved system availability

High gain, low noise, fully complementary logic inverter based on bi-layer WSe{sub 2} field effect transistors

Energy Technology Data Exchange (ETDEWEB)

Das, Saptarshi; Roelofs, Andreas [Center for Nanoscale Material, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Dubey, Madan [U.S. Army Research Laboratory, Adelphi, Maryland 20783 (United States)

2014-08-25

In this article, first, we show that by contact work function engineering, electrostatic doping and proper scaling of both the oxide thickness and the flake thickness, high performance p- and n-type WSe{sub 2} field effect transistors (FETs) can be realized. We report record high drive current of 98 μA/μm for the electron conduction and 110 μA/μm for the hole conduction in Schottky barrier WSe{sub 2} FETs. Then, we combine high performance WSe{sub 2} PFET with WSe{sub 2} NFET in double gated transistor geometry to demonstrate a fully complementary logic inverter. We also show that by adjusting the threshold voltages for the NFET and the PFET, the gain and the noise margin of the inverter can be significantly enhanced. The maximum gain of our chemical doping free WSe{sub 2} inverter was found to be ∼25 and the noise margin was close to its ideal value of ∼2.5 V for a supply voltage of V{sub DD} = 5.0 V.

Novel Solvent-free Perovskite Deposition in Fabrication of Normal and Inverted Architectures of Perovskite Solar Cells

Science.gov (United States)

Nejand, Bahram Abdollahi; Gharibzadeh, Saba; Ahmadi, Vahid; Shahverdi, H. Reza

2016-01-01

We introduced a new approach to deposit perovskite layer with no need for dissolving perovskite precursors. Deposition of Solution-free perovskite (SFP) layer is a key method for deposition of perovskite layer on the hole or electron transport layers that are strongly sensitive to perovskite precursors. Using deposition of SFP layer in the perovskite solar cells would extend possibility of using many electron and hole transport materials in both normal and invert architectures of perovskite solar cells. In the present work, we synthesized crystalline perovskite powder followed by successful deposition on TiO2 and cuprous iodide as the non-sensitve and sensitive charge transport layers to PbI2 and CH3NH3I solution in DMF. The post compressing step enhanced the efficiency of the devices by increasing the interface area between perovskite and charge transport layers. The 9.07% and 7.71% cell efficiencies of the device prepared by SFP layer was achieved in respective normal (using TiO2 as a deposition substrate) and inverted structure (using CuI as deposition substrate) of perovskite solar cell. This method can be efficient in large-scale and low cost fabrication of new generation perovskite solar cells. PMID:27640991

Investigation of the sideband effect for the LCL-type grid-connected inverter with high LCL resonance frequency

DEFF Research Database (Denmark)

Yang, Dongsheng; Wang, Xiongfei; Blaabjerg, Frede

2017-01-01

The LCL-type grid connected inverter has been widely used as the intelligent power interface between the distributed generation unit and the power grid. To reduce the cost and volume of the filter, it is desirable to design the LCL filter with higher resonance frequency provided that the quality...... of injected grid current is not compromised. Actually, it is the typical case for the T-type or NPC three-level inverter to design its LCL resonance frequency close to half of the switching frequency. In this case, however, the sideband effect of SPWM modulation can impose a significant impact on the system...

Effects of silicon carbide MOSFETs on the efficiency and power quality of a microgrid-connected inverter

International Nuclear Information System (INIS)

Ding, Xiaofeng; Chen, Feida; Du, Min; Guo, Hong; Ren, Suping

2017-01-01

Highlights: •The characteristics comparison between SiC-inverter and Si-inverter is implemented, considering thermal effects. •The voltage distortion of inverters is modeling from the perspective of the behaviors of the device. •The efficiency of the microgrid-connected inverter has been greatly increased by replacing Si with SiC. •The SiC microgrid-connected inverter has smaller voltage distortion and less harmonic current than those of Si-inverter. •The proposed analytical model has been validated by the experimental test. -- Abstract: With the expanding power demands and increasing use of renewable energy resources, microgrids have been widely supported. Wide bandgap semiconductor devices with higher blocking voltage capabilities and higher switching speeds, such as silicon carbide (SiC) devices, will become a critical component in building microgrids. This paper describes a comprehensive investigation of the effects of SiC Metal-Oxide-Semiconductor Field-Effect Transistors (MOSFETs) on the efficiency and power quality of the inverters used in low voltage microgrids compared with conventional inverters based on silicon (Si) Insulated-gate Bipolar Transistors (IGBTs). First, the characteristics of both SiC and Si are measured by a double pulse test (DPT), considering thermal effects. Then, conduction and switching losses under different temperatures are calculated based on DPT results. Second, phase voltage distortions are modeled and calculated according to the tested switching and conduction characteristics of SiC, resulting in harmonic components in the phase current. Finally, an experiment is implemented. The experimental results show that the SiC-inverter greatly increases the energy efficiency and improves the power quality in the microgrid; these results are consistent with the analytical results.

Simple and versatile modifications allowing time gated spectral acquisition, imaging and lifetime profiling on conventional wide-field microscopes

International Nuclear Information System (INIS)

Pal, Robert; Beeby, Andrew

2014-01-01

An inverted microscope has been adapted to allow time-gated imaging and spectroscopy to be carried out on samples containing responsive lanthanide probes. The adaptation employs readily available components, including a pulsed light source, time-gated camera, spectrometer and photon counting detector, allowing imaging, emission spectroscopy and lifetime measurements. Each component is controlled by a suite of software written in LabVIEW and is powered via conventional USB ports. (technical note)

The overview of damping methods for three-phase grid-tied inverter with LLCL-filter

DEFF Research Database (Denmark)

Huang, Min; Blaabjerg, Frede; Loh, Poh Chiang

2014-01-01

Compared with LCL filter, an LLCL-filter is characterized with smaller size and lower cost for grid-connected inverters. But this high order filter may also have resonant problem which will affect the system stability. Many methods can be used to alleviate the resonant problem including active da...... and shows the advantages as well as disadvantages of these methods....

Diode-Assisted Buck-Boost Voltage-Source Inverters

DEFF Research Database (Denmark)

Gao, Feng; Loh, Poh Chiang; Teodorescu, Remus

2009-01-01

, a number of diode-assisted inverter variants can be designed with each having its own operational principle and voltage gain expression. For controlling them, a generic modulation scheme that can be used for controlling all diode-assisted variants with minimized harmonic distortion and component stress......This paper proposes a number of diode-assisted buck-boost voltage-source inverters with a unique X-shaped diode-capacitor network inserted between the inverter circuitry and dc source for producing a voltage gain that is comparatively higher than those of other buck-boost conversion techniques....... Using the diode-assisted network, the proposed inverters can naturally configure themselves to perform capacitive charging in parallel and discharging in series to give a higher voltage multiplication factor without compromising waveform quality. In addition, by adopting different front-end circuitries...

Development of inverter for elevator door control

Energy Technology Data Exchange (ETDEWEB)

Kim, J.K.; Choi, U.D.; Jung, M.K.; Choi, S.K. [HHI R and D Center (Korea, Republic of); Yun, J.H.; Han, S.B. [HELCO R and D Center (Korea, Republic of)

1995-07-01

Most of the elevator door controllers have been controlled by DC Motors as an actuator. Recently, The control system using AC induction motor and general purpose inverter has been applied to control of elevator door. But there are some difficulties in making use of this system, such as adjustment of door speed pattern, door open-close time, and security of passenger safety. In order to solve these problems, a special inverter has been developed with an encoder feedback. From the result of field-test, we proved that a special inverter with encoder feedback device has come to considerable effect. Until now about 1,200 sets of these inverters are operated in Korea and about 100 sets are operated in South-east Asia. (author). 3 refs., 10 figs., 3 tabs.

Operational analysis and comparative evaluation of embedded Z-Source inverters

DEFF Research Database (Denmark)

Blaabjerg, Frede; Gao, F.; Loh, P.C.

2008-01-01

) circuitry connected instead of the generic voltage source inverter (VSI) circuitry. Further proceeding on to the topological variation, parallel embedded Z-source inverters are presented with the detailed analysis of topological configuration and operational principles showing that they are the superior......This paper presents various embedded Z-source (EZ-source) inverters broadly classified as shunt or parallel embedded Z-source inverter. Being different from the traditional Z-source inverter, EZ-source inverters are constructed by inserting dc sources into the X-shaped impedance network so...... that the dc input current flows smoothly during the whole switching period unlike the traditional Z-source inverter. This feature is interesting when PV panels or fuel cells are assumed to power load since the continuous input current flow reduces control complexity of dc source and system design burden...

Advanced Power Electronics and Smart Inverters | Grid Modernization | NREL

Science.gov (United States)

Advanced Power Electronics and Smart Inverters Advanced Power Electronics and Smart Inverters , into the electric distribution system requires advanced power electronics, or smart inverters, that . Contact Sudipta Chakraborty Power Electronics Team Lead sudipta.chakraborty@nrel.gov | 303-384-7093

Human Mobile Inverted Pendulum Transporter - a Mechatronic System Case Study

DEFF Research Database (Denmark)

Bech, Michael Møller; Hansen, Anders Hedegaard; Pedersen, Henrik C.

2011-01-01

procedure combined with the formulation and the solution of an optimization problem involving a number of constraints related to performance, costs, geometry, availability of components etc. In this paper, we present a case-study of a more traditional design procedure for a highly multi-disciplinary device......, which nevertheless illustrates the potentials of unifying classical engineering technologies (mechanics, electronics, control systems) with modern high-efficient inverter-fed permanent magnet AC motors and the latest MEMS sensor technology. A full-scale fully operational prototype of a two-wheel mobile...

Highly efficient fully transparent inverted OLEDs

Science.gov (United States)

Meyer, J.; Winkler, T.; Hamwi, S.; Schmale, S.; Kröger, M.; Görrn, P.; Johannes, H.-H.; Riedl, T.; Lang, E.; Becker, D.; Dobbertin, T.; Kowalsky, W.

2007-09-01

One of the unique selling propositions of OLEDs is their potential to realize highly transparent devices over the visible spectrum. This is because organic semiconductors provide a large Stokes-Shift and low intrinsic absorption losses. Hence, new areas of applications for displays and ambient lighting become accessible, for instance, the integration of OLEDs into the windshield or the ceiling of automobiles. The main challenge in the realization of fully transparent devices is the deposition of the top electrode. ITO is commonly used as transparent bottom anode in a conventional OLED. To obtain uniform light emission over the entire viewing angle and a low series resistance, a TCO such as ITO is desirable as top contact as well. However, sputter deposition of ITO on top of organic layers causes damage induced by high energetic particles and UV radiation. We have found an efficient process to protect the organic layers against the ITO rf magnetron deposition process of ITO for an inverted OLED (IOLED). The inverted structure allows the integration of OLEDs in more powerful n-channel transistors used in active matrix backplanes. Employing the green electrophosphorescent material Ir(ppy) 3 lead to IOLED with a current efficiency of 50 cd/A and power efficiency of 24 lm/W at 100 cd/m2. The average transmittance exceeds 80 % in the visible region. The on-set voltage for light emission is lower than 3 V. In addition, by vertical stacking we achieved a very high current efficiency of more than 70 cd/A for transparent IOLED.

LCCT-derived three-level three-phase inverters

DEFF Research Database (Denmark)

Shults, Tatiana; Husev, Oleksandr; Blaabjerg, Frede

2017-01-01

Solutions for a family of the novel three-level neutral-point-clamped (NPC) inductor-capacitor-capacitor-transformer (LCCT)-derived three-phase inverters are described and compared. Component design guidelines and steady state analysis, current and voltage waveforms are given. The authors......' simulation results confirm the theoretical predictions. It was found that an asymmetrical three-level NPC LCCT-derived inverter with a single diode in the impedance source network is the most promising solution. Experimental results for an asymmetrical three-level NPC LCCT-derived inverter with a single...

Efficacy of Low-Cost PC-Based Aviation Training Devices

Directory of Open Access Journals (Sweden)

Savern l Reweti

2017-03-01

Full Text Available Aim/Purpose: The aim of this study was to explore whether a full cost flight training device (FTD was significantly better for simulator training than a low cost PC-Based Aviation Training Device (PCATD. Background: A quasi-transfer study was undertaken to ascertain whether a Civil Aviation Authority certified Flight Training Device (FTD was more effective at improving pilot proficiency in the performance of a standard VFR traffic pattern (Overhead Rejoin Procedure than a customised low cost PCATD. Methodology: In this quasi-transfer study, a high fidelity FTD rather than an aircraft was used to test both training and transfer tasks. Ninety-three pilots were recruited to participate in the study. Contribution: The use of PCATDs is now well established for pilot training, especially for Instrument Flight Rules (IFR skills training. However, little substantive research has been undertaken to examine their efficacy for VFR training. Findings: There was no evidence of a pre-test/post-test difference in VFR task perfor-mance between participants trained on the PCATD and the FTD, when post tested on the FTD. The use of both PCATD and FTD demonstrated signifi-cant improvements in VFR task performance compared to a control group that received no PCATD or FTD training. Recommendations for Practitioners\t: We discuss the possibility that low cost PCATDs may be a viable alternative for flight schools wishing to use a flight simulator but not able to afford a FTD. Recommendation for Researchers: We discuss the introduction of improved low cost technologies that allow PCATDs to be used more effectively for training in VFR procedures. The development and testing of new technologies requires more research. Impact on Society: Flight training schools operate in a difficult economic environment with continued increases in the cost of aircraft maintenance, compliance costs, and aviation fuel. The increased utilisation of low cost PCATD’s especially for VFR

Fabrication of 20.19% Efficient Single-Crystalline Silicon Solar Cell with Inverted Pyramid Microstructure.

Science.gov (United States)

Zhang, Chunyang; Chen, Lingzhi; Zhu, Yingjie; Guan, Zisheng

2018-04-03

This paper reports inverted pyramid microstructure-based single-crystalline silicon (sc-Si) solar cell with a conversion efficiency up to 20.19% in standard size of 156.75 × 156.75 mm 2 . The inverted pyramid microstructures were fabricated jointly by metal-assisted chemical etching process (MACE) with ultra-low concentration of silver ions and optimized alkaline anisotropic texturing process. And the inverted pyramid sizes were controlled by changing the parameters in both MACE and alkaline anisotropic texturing. Regarding passivation efficiency, the textured sc-Si with normal reflectivity of 9.2% and inverted pyramid size of 1 μm was used to fabricate solar cells. The best batch of solar cells showed a 0.19% higher of conversion efficiency and a 0.22 mA cm -2 improvement in short-circuit current density, and the excellent photoelectric property surpasses that of the same structure solar cell reported before. This technology shows great potential to be an alternative for large-scale production of high efficient sc-Si solar cells in the future.

Advanced Energy Validated Photovoltaic Inverter Technology at NREL | Energy

Science.gov (United States)

Inverter Technology at NREL Advanced Energy Industries-NREL's first partner at the Energy Systems Integration Facility (ESIF)-validated its advanced photovoltaic (PV) inverter technology using the ESIF's computer screen in a laboratory, with power inverter hardware in the background Photo by Dennis Schroeder

Photovoltaic power generating system; Sanso zetsuengata taiyoko inverter

Energy Technology Data Exchange (ETDEWEB)

Nojima, T; Nakashima, T; Muta, Y; Takase, K; Hirayama, K [Nishimu Electronics Industries Co. Ltd., Saga (Japan)

1996-10-27

Nishimu Electronics Industries Co., Ltd. has developed a new series of inverters of three phase photovoltaic power generating system with the output ranging from 10 kVA to 50 kVA. For these inverters, the inverter and the system interconnection protector were integrated to make them smaller, lighter and cheaper. Stand-alone operation function was also added. The DC input voltage ranges were between 240 and 400 V for the crystalline solar cell, and between 170 and 400 V for the amorphous one. From the viewpoint of control of inverters, the inverters are generally controlled by the voltage-type current control method during the interconnection operation, while they must be controlled by the voltage-type voltage control method during the stand-alone operation which is the same as the UPS usually operated alone. For the present inverters, two control circuits for the interconnection operation and for the stand-alone operation were prepared. The control circuits for interconnection and stand-alone operations were switched using a cam-operation switch for change-over of operation. The results of the system interconnection verification tests satisfied the criteria of Japan`s Electronic Products Test Center. 3 refs., 4 figs., 2 tabs.