bluuebunny/crossref_metadata_2025_split huggingface dataset:
Down-hole switching-mode power supply using a remote CA start up pulse
Authors: Mijarez Rito , Gomez Angel , Pascacio David , Martinez Ivan , Guevara Ricardo 
Published: May 2016

Abstract
The hydrocarbon industry leans heavily upon advanced technologies to extract oil and gas from greater depths and in harsher environments. The challenge to electronics manufacturers and designers is to make complex electronics work at the high temperatures, vibration, and extreme pressures encountered in these locations. Among the more critical electronic systems required for high temperature down-hole operations is high efficiency switching mode power supplies (SMPS). The use of high frequency switching permits not only decreasing the size of inductors and capacitors in the circuit design, but also obtaining typical power efficiencies up to 90%. Generally a SMPS is composed of a controller, a converter and silicon carbide (SiC) power switches. High temperature down-hole gauges operate with low voltages either 3.3V or 5.0V; however, wire-line surface power equipment utilizes higher voltages above 250 V CD. Hence, SMPS requires efficient power dissipation circuits to reduce the DC input voltage. This work describes a high temperature SMPS that has a DC input range from 150 V CD to 300 V CD, ± 6 V CD output voltages and 12 W total power. The SMPS design uses a CA start up pulse provided by a programmable surface power supply via a mono-conductor wire-line cable; subsequently, the SMPS sustains its operation by powering itself using one of the voltage outputs. The obtained laboratory tests results of the down-hole SMPS, using changes in temperature from 25 °C – 200 °C, provide a firm basis for testing and evaluating the DC-CD power supply in high temperature gauges in the field.
Silicon-Carbide Power MOSFET Performance in High Efficiency Boost Power Processing Unit for Extreme Environments
Authors: Ikpe Stanley A. , Lauenstein Jean-Marie , Carr Gregory A. , Hunter Don , Ludwig Lawrence L. , Wood William , Del Castillo Linda Y. , Mojarradi Mohammad M. , Fitzpatrick Fred , Chen Yuan 
Published: May 2016

Abstract
Silicon-Carbide (SiC) device technology has generated much interest in recent years. With superior thermal performance, power ratings and potential switching frequencies over its Silicon (Si) counterpart, SiC offers a greater possibility for high powered switching applications in extreme environment. In particular, SiC Metal-Oxide-Semiconductor Field-Effect Transistors' (MOSFETs) maturing process technology has produced a plethora of commercially available power dense, low on-state resistance devices capable of switching at high frequencies. A novel hard-switched power processing unit (PPU) is implemented utilizing SiC power devices. Accelerated life data is captured and assessed in conjunction with a damage accumulation model of gate oxide and drain-source junction lifetime to evaluate potential system performance at high temperature environments.
Toward Interpreting Failure in Sintered-Silver Interconnection Systems†
Authors: Modugno M. C. , Wereszczak A. A. , Waters S. B. 
Published: May 2016

Abstract
The mechanical strength and subsequent reliability of a sintered-silver interconnection “system” is a function of numerous independent parameters, and that “system” is still undergoing process development. Most of those parameters (e.g., choice of plating) are arguably and unfortunately often taken for granted and are independent of the silver's cohesive strength. To explore such effects, shear strength testing and failure analyses were completed on a simple, mock sintered-silver interconnection system consisting of bonding two DBC ceramic substrates. Silver and gold platings were part of the test matrix, as were drying strategies, and the consideration of stencil-printing vs. screen-printing. Shear strength of sintered-silver interconnect systems was found to be insensitive to the choice of plating, drying practice, and printing method provided careful and consistent processing of the sintered-silver are practiced. Lastly, with the examined interconnection systems, it was observed that a maximum shear failure stress of ~ 60 MPa is achievable.
Nanocomposite Film Dielectrics for High Temperature Power Conditioning Capacitors
Authors: Slenes Kirk , Perry Dale , Bragg Lew 
Published: May 2016

Abstract
Emerging power electronics in a broad range of military, aerospace, hybrid vehicle, renewable energy and drilling applications rely on advances in dielectric materials for capacitors. Compact capacitors possessing low dielectric loss and high operating temperature capability are needed for power conditioning in advanced converter and inverter designs for these applications. Wound film capacitors represent the preferred capacitor technology but are limited by low operating temperature capabilities, &lt; 150°C, and low volumetric efficiency, capacitance per unit volume less than 1.0 μF/cc.
TPL is developing processes and manufacturing techniques for fabrication of advanced capacitor films comprised of high temperature polymers modified with ceramic nanoparticles. The selected polymers enable high temperature operation and the ceramic nanoparticles enhance volumetric efficiency by increasing the dielectric constant. The fabricated films are adaptable to conventional wound film capacitor construction methodologies.
This paper provides an overview of TPL's experience to-date with a film dielectric material system comprised of fluorenone polyester polymer and titanate nanoparticle filler. The fluorenone polyester polymer was selected to provide a stable operating temperature of at least 200°C, while the addition of the titanate powder increases the dielectric constant and, in turn, the volumetric efficiency of wound film capacitors constructed with this film system. Status and ongoing capacitor development issues are provided relative to the intended high temperature power conditioning applications.
Design of High Temperature Combline Band-pass Filters for Downhole Communications
Authors: Ehteshamuddin Mohammed , Salem Jebreel M. , Ha Dong Sam 
Published: May 2016

Abstract
The decline of easily accessible reserves pushes the oil and gas industry to drill deeper to explore previously untapped wells. Temperatures in these wells can exceed 210 °C. Cooling and conventional heat extraction techniques are impractical in such a harsh environment. Reliable electronic designs that can sustain high temperature become necessary. This paper presents RF and IF microstrip combline band-pass filters for downhole communications, which can reliably operate up to 250 °C. Both filters are prototyped on a Rogers RO4003C substrate. Measured results at 250 °C show that the RF and IF filters have insertion losses of 4.53 dB and 3.45 dB, respectively. Both filters have stable performance at high temperatures. The maximum insertion loss variation with temperature for the RF filter is 1.88 dB, and bandwidth variation is 1.3 MHz. The maximum insertion loss variation with temperature for the IF filter is 1.48 dB, and bandwidth variation is 0.4 MHz. Return loss for the RF filter is more than 12 dB, and for the IF filter more than 10 dB in the passband. This paper also describes a simple method to find spacing between coupled symmetrical microstrip lines of a combline filter.
High Precision Analog Multiplexers Enable Multi-Channel Data Acquisition in High Temperature Environments
Authors: Watson Jeff , Kavanagh Stephen , Nugent Stephen 
Published: May 2016

Abstract
A growing number of industries are calling for low power electronics that operate reliably at temperatures of 175C and higher. Many of these applications require a precision data acquisition signal chain in order to digitize analog data so that it can be collected and processed. We previously presented a characterized signal chain for a single channel of analog to digital conversion designed around a 600ks ps SAR ADC. However, many systems have a multitude of sensor signals that must be acquired at varying sample rates. In this work we discuss two new analog multiplexers rated for 175°C/210°C that allow multiple analog signals to be connected to the ADC input, enabling the design of a precision multi-channel data acquisition system. One multiplexer is designed on a robust dielectrically isolated process for high performance and low leakage over temperature, and one multiplexer is optimized for low power, low voltage applications. We will examine the architecture of these two integrated circuits, review the characterization over temperature and discuss example application signal chains.
Improving Efficiency in Downhole Power Converters using GaN Technology
Authors: Hanington Gary 
Published: May 2016

Abstract
In downhole applications, the ability to convert wildly varying wireline voltages standard +/− 15 VDC stretches the limit on switching converters whose components have to be rugged, compact, and offer low thermal paths to surrounding metal housings. Many times the incoming voltages exceed 200V with spikes above 500 quite common. Functioning in extreme environments up to 200 degrees Celsius requires the designer to squeeze out the highest power efficiency possible and every percent increase is an important milestone. Over the past three decades silicon devices were the only technology available that could be made to work at such temperatures, almost always bypassing the manufacturer's maximum specifications. In the past several years wide bandgap semiconductors have become available that offer new possibilities for operation at elevated temperatures. This paper discusses the efficiency improvements when silicon power devices are replaced with gallium nitride based components. By utilizing GaN High Electron Mobility Transistors (HEMTs) in an existing H bridge phase shifted converter, efficiency improvements of up to 9% have been achieved at 175 °C operation. Advantages of HEMT devices compared to silicon are discussed and associated loss mechanisms of both are compared.
Targeted temperature management in neurocritical care: Boon or bust
Authors: Bindra Ashish , Gupta Deepak 
Published: May 2016

AbstractTemperature management in neurocritical care is important and has gained due importance in recent years. Targeted temperature management (TTM) includes deliberate reduction of core body temperature to a range of 32–34°C in comatose survivors of cardiac arrest after return of spontaneous circulation and also therapeutic hypothermia (33–35°C) in normothermic patients or controlled normothermia (cooling patients to 37°C) in hyperthermic patients. This review focuses on the practical aspects of cooling and temperature management in neurocritical care. An electronic search of Google Scholar, MEDLINE (OVID), EMBASE and the Cochrane library was performed. The physiological changes, potential side effects along with significant research and clinical applications in the field of temperature management are main highlights. Currently, the research evidence is available for TTM in adults following cardiac arrest, neonatal hypoxic ischaemic encephalopathy and raised intracranial pressure. Controlled normothermia in neurocritical care population is rapidly gaining popularity. However, data on disease specific therapeutic markers, therapeutic depth and duration and prognostication of this modality are limited. Overall in experienced hands, the technique is safe to execute without the major morbidity and a potential to improve the outcome. Though over the years, clinical applications are unable to consistently demonstrate its benefits, but TTM in neurological insult has become an established and promising concept.
Artin Approximation Compatible with a Change of Variables
Authors: Fichou Goulwen , Quarez Ronan , Shiota Masahiro 
Published: May 2016

AbstractWe propose a version of the classical Artin approximation that allows us to perturb the variables of the approximated solution. Namely, it is possible to approximate a formal solution of a Nash equation by a Nash solution in a compatible way with a given Nash change of variables. This result is closely related to the so-called nested Artin approximation and becomes false in the analytic setting. We provide local and global versions of this approximation in real and complex geometry together with an application to the Right-Left equivalence of Nash maps.
Effect of adipose tissue-derived stem cell injection in a rat model of urethral fibrosis
Authors: Sangkum Premsant , Yafi Faysal A. , Kim Hogyoung , Bouljihad Mostafa , Ranjan Manish , Datta Amrita , Mandava Sree Harsha , Sikka Suresh C. , Abdel-Mageed Asim B. , Hellstrom Wayne J.G. 
Published: May 2016

Introduction: We sought to evaluate the therapeutic effect of adipose tissue-derived stem cells (ADSCs) in a rat model of urethral fibrosis.Methods: Eighteen (18) male Sprague-Dawley rats (300‒350 g) were divided into three groups: (1) sham (saline injection); (2) urethral fibrosis group (10 μg transforming growth factor beta 1 (TGF-β1) injection); and (3) ADSCs group (10 μg TGF-β1 injection plus 2 x 105 ADSCs). Rat ADSCs were harvested from rat inguinal fat pads. All study animals were euthanized at two weeks afterurethral injection. Following euthanasia, rat urethral tissue was were quantitated by Western blot analysis. Results: TGF-β1 injection induced significant urethral fibrosis and increased collagen type I and III expression (p<0.05). Significant decrease in submucosal fibrosis and collagen type I and III expression were noted in the ADSCs group compared with the urethral fibrosis group (p<0.05). TGF-β1 induced fibrotic changes were ameliorated by injection of ADSCs.Conclusions: Local injection of ADSCs in a rat model of urethral fibrosis significantly decreased collagen type I and III. These findings suggest that ADSC injection may prevent scar formation and potentially serve as an adjunct treatment to increase the success rate of primary treatment for urethral stricture disease. Further animal and clinical studies are needed to confirm these results.
A survey of superthermal electron flux depressions, or “electron holes,” within the illuminated Martian induced magnetosphere
Authors: Hall B. E. S. , Lester M. , Nichols J. D. , Sánchez‐Cano B. , Andrews D. J. , Opgenoorth H. J. , Fränz M. 
Published: May 2016

AbstractSince Mars lacks a global intrinsic magnetic field, the solar wind interacts directly with the Martian upper atmosphere and ionosphere. The presence of localized intense remnant crustal magnetic fields adds to this interaction, making the Martian plasma system a unique environment within the solar system. Rapid reductions in the electron flux, referred to as “electron holes,” occur within the Martian induced magnetosphere (IM). We present a statistical analysis of this phenomenon identified from proxy measurements of the electron flux derived from measurements by the Analyser of Space Plasmas and Energetic Neutral Atoms Electron Spectrometer experiment on board the Mars Express (MEX) spacecraft. The study is completed for the period of 9 February 2004 to 9 May 2014. Electron holes are observed within the IM in more than 56% of MEX orbits during this study period, occurring predominantly at altitudes less than 1300 km, with the majority in the negative X Mars‐Centric Solar Orbital direction. The spatial distribution above the surface of Mars is observed to bear close resemblance to that of the crustal magnetic fields as predicted by the Cain et al. [] magnetic field model, suggesting that they play an important role in the formation of these phenomena.
Automated determination of electron density from electric field measurements on the Van Allen Probes spacecraft
Authors: Zhelavskaya I. S. , Spasojevic M. , Shprits Y. Y. , Kurth W. S. 
Published: May 2016

AbstractWe present the Neural‐network‐based Upper hybrid Resonance Determination (NURD) algorithm for automatic inference of the electron number density from plasma wave measurements made on board NASA's Van Allen Probes mission. A feedforward neural network is developed to determine the upper hybrid resonance frequency, fuhr, from electric field measurements, which is then used to calculate the electron number density. In previous missions, the plasma resonance bands were manually identified, and there have been few attempts to do robust, routine automated detections. We describe the design and implementation of the algorithm and perform an initial analysis of the resulting electron number density distribution obtained by applying NURD to 2.5 years of data collected with the Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) instrumentation suite of the Van Allen Probes mission. Densities obtained by NURD are compared to those obtained by another recently developed automated technique and also to an existing empirical plasmasphere and trough density model.
Compression of a multiphase mantle assemblage: Effects of undesirable stress and stress annealing on the iron spin state crossover in ferropericlase
Authors: Glazyrin Konstantin , Miyajima Nobuyoshi , Smith Jesse S. , Lee Kanani K. M. 
Published: May 2016

AbstractUsing synchrotron‐based X‐ray diffraction, we explore characteristic signatures for nonhydrostatic stresses and their effect on the spin state crossover of ferrous iron in (Mg, Fe)O ferropericlase (Fp) upon compression in a two‐phase mixture which includes an Al‐ and Fe‐bearing bridgmanite (Bm). We observe an influence of nonhydrostatic stresses on the spin state crossover starting pressure and width. The undesirable stresses discussed here include uniaxial deviatoric stress evolving in the diamond anvil cell and effects of intergrain interaction. While the former leads to a pressure overestimation, the latter one lowers the pressure of the onset for the high‐spin to low‐spin electronic transition in Fe2+ in ferropericlase (Mg, Fe)O with respect to hydrostatic conditions.
Estimation of global black carbon direct radiative forcing and its uncertainty constrained by observations
Authors: Wang Rong , Balkanski Yves , Boucher Olivier , Ciais Philippe , Schuster Gregory L. , Chevallier Frédéric , Samset Bjørn H. , Liu Junfeng , Piao Shilong , Valari Myrto , Tao Shu 
Published: May 2016

AbstractBlack carbon (BC) contributes to global warming by absorbing sunlight. However, the size of this contribution, namely, the direct radiative forcing (RF), ranges from +0.1 to +1.0 W m−2, largely due to differences between bottom‐up and observation‐based estimates. Current global models systematically underestimate BC radiation absorption relative to observations, which is often attributed to the underestimation of BC emissions. Several studies that adjusted emissions to correct biases of global aerosol models resulted in a revised upward estimate of the BC RF. However, the BC RF was never optimized against observations in a rigorous mathematical manner. Here we simulated the absorption of solar radiation by BC from all sources at the 10 km resolution by combining a highly disaggregated emission inventory with a nested aerosol climate model and a downscaling method. As a result, the normalized mean bias in BC radiation absorption was reduced from −51% to −24% in Asia and from −57% to −50% elsewhere. We applied a Bayesian method that makes the best account of all model, representativeness and observational uncertainties to estimate the BC RF and its uncertainty. Using the new emission inventory and high‐resolution model reduces uncertainty in BC RF from −101%/+152% to −70%/+71% over Asia and from −83%/+108% to −64%/+68% over other continental regions. Finally we derived an observationally constrained BC RF of 0.61 Wm−2 (0.16 to 1.40 as 90% confidence) as our best estimate. Our estimate implies that reduction in BC emissions would contribute to slow down global warming, but the contribution could be less than previously thought.
On the choice of analogue fluids in CO2 convective dissolution experiments
Authors: Jafari Raad Seyed Mostafa , Emami‐Meybodi Hamid , Hassanzadeh Hassan 
Published: May 2016

AbstractMixtures of ethylene glycol and methanol (EG‐MeOH) have been used as an analogue system (i.e., EG‐MeOH/water) in recent experiments in the context of convective dissolution of CO2 in deep saline aquifers. We have conducted a linear stability analysis of a gravitationally unstable diffusive boundary layer as well as direct numerical simulation of convective mixing involved in dissolution of EG‐MeOH species in water. We provide new evidences that EG‐MeOH does not resemble the dynamics of convective instabilities and subsequent mixing associated with dissolution of CO2 in water. It is found that there are fundamental differences in the evolution of the buoyancy‐driven instability and dynamics of convective mixing between CO2/water and a typical EG‐MeOH/water analogue system. Our results show that for a constant Rayleigh number, the onset of convective instabilities for EG‐MeOH/water can be different by an order of magnitude as compared with CO2/water. In addition, EG‐MeOH/water system reveals different dynamics associated with the convective mixing as compared to CO2/water system. This study improves our understanding of the instability behavior of analogue systems, their proper selection, and motivates further experiments.
Deliquescence‐induced wetting and RSL‐like darkening of a Mars analogue soil containing various perchlorate and chloride salts
Authors: Heinz Jacob , Schulze‐Makuch Dirk , Kounaves Samuel P. 
Published: May 2016

AbstractRecurring slope lineae (RSL) are flow‐like features on Mars characterized by a local darkening of the soil thought to be generated by the formation and flow of liquid brines. One possible mechanism responsible for forming these brines could be the deliquescence of salts present in the Martian soil. We show that the JSC Mars‐1a analogue soil undergoes a darkening process when salts dispersed in the soil deliquesce, but forming continuous liquid films and larger droplets takes much longer than previously assumed. Thus, RSL may not necessarily require concurrent flowing liquid water/brine or a salt‐recharge mechanism, and their association with gullies may be the result of previously flowing water and deposited salts during an earlier warmer and wetter period. In addition, our results show that electrical conductivity measurements correlate well with the deliquescence rates and provide better overall characterization than either Raman spectroscopy or estimates based on deliquescence relative humidity.
MAVEN observations of magnetic flux ropes with a strong field amplitude in the Martian magnetosheath during the ICME passage on 8 March 2015
Authors: Hara Takuya , Luhmann Janet G. , Halekas Jasper S. , Espley Jared R. , Seki Kanako , Brain David A. , Hasegawa Hiroshi , McFadden James P. , Mitchell David L. , Mazelle Christian , Harada Yuki , Livi Roberto , DiBraccio Gina A. , Connerney John E. P. , Andersson Lailla , Jakosky Bruce M. 
Published: May 2016

AbstractWe present initial results of strong field amplitude flux ropes observed by Mars Atmosphere and Volatile EvolutioN (MAVEN) mission around Mars during the interplanetary coronal mass ejection (ICME) passage on 8 March 2015. The observed durations were shorter than 5 s and the magnetic field magnitudes peaked above 80 nT, which is a few times stronger than those usually seen in the magnetosheath barrier. These are the first unique observations that MAVEN detected such flux ropes with a strong field at high altitudes (>5000 km). Across these structures, MAVEN coincidentally measured planetary heavy ions with energies higher than a few keV. The spatial properties inferred from the Grad‐Shafranov equation suggest that the speed of the structure can be estimated at least an order of magnitude faster than those previously reported quiet‐time counterparts. Hence, the space weather event like the ICME passage can be responsible for generating the observed strong field, fast‐traveling flux ropes.