Low-Voltage High-Performance UV Photodetectors: An Interplay between Grain Boundaries and Debye Length.

PubMed

Bo, Renheng; Nasiri, Noushin; Chen, Hongjun; Caputo, Domenico; Fu, Lan; Tricoli, Antonio

2017-01-25

Accurate detection of UV light by wearable low-power devices has many important applications including environmental monitoring, space to space communication, and defense. Here, we report the structural engineering of ultraporous ZnO nanoparticle networks for fabrication of very low-voltage high-performance UV photodetectors. A record high photo- to dark-current ratio of 3.3 × 10 5 and detectivity of 3.2 × 10 12 Jones at an ultralow operation bias of 2 mV and low UV-light intensity of 86 μW·cm -2 are achieved by controlling the interplay between grain boundaries and surface depletion depth of ZnO nanoscale semiconductors. An optimal window of structural properties is determined by varying the particle size of ultraporous nanoparticle networks from 10 to 42 nm. We find that small electron-depleted nanoparticles (≤40 nm) are necessary to minimize the dark-current; however, the rise in photocurrent is tampered with decreasing particle size due to the increasing density of grain boundaries. These findings reveal that nanoparticles with a size close to twice their Debye length are required for high photo- to dark-current ratio and detectivity, while further decreasing their size decreases the photodetector performance.

The correlation between tonsil size and academic performance is not a direct one, but the results of various factors.

PubMed

Kargoshaie, A A; Najafi, M; Akhlaghi, M; Khazraie, H R; Hekmatdoost, A

2009-10-01

Chronic upper airway obstruction most often occurs when both tonsils and adenoid are enlarged but may occur when either is enlarged. Obstructive sleep syndrome in young children has been reported to be associated with an adverse effect on learning and academic performance. The aim of this study was to evaluate the effect of relative size of the tonsil on academic performance in 4th grade school children. In 320 children, physical examination to determine the size of tonsils was performed by the otorhinolaryngologist. A questionnaire was developed to assess sleep patterns and problems, and socio-demographic data for the student participants. Furthermore, their school performance was assessed using their grade in mathematics, science, reading, spelling, and handwriting. No association between tonsil size and academic performance was found. Snoring frequency, body mass index and body weight showed a positive relation with tonsil size. There was no association between tonsil size and sleepiness during the day, sleeping habits, hyperactivity, enuresis, history of tonsillectomy in children and parental cigarette smoking and education. In conclusion, this study did not show any significant relationship between tonsil size and academic performance in 4th grade students. Further studies are recommended with a larger sample size, cognitive exams for evaluation of attention, and follow-up of the students until high school, when the discrepancy of the students' academic performance is more obvious.

Investigation into the Manufacture and Properties of Inhalable High-Dose Dry Powders Produced by Comilling API and Lactose with Magnesium Stearate.

PubMed

Lau, Michael; Young, Paul M; Traini, Daniela

2017-08-01

The aim of the study was to understand the impact of different concentrations of the additive material, magnesium stearate (MGST), and the active pharmaceutical ingredient (API), respectively, on the physicochemical properties and aerosol performance of comilled formulations for high-dose delivery. Initially, blends of API/lactose with different concentrations of MGST (1-7.5% w/w) were prepared and comilled by the jet-mill apparatus. The optimal concentration of MGST in comilled formulations was investigated, specifically for agglomerate structure and strength, particle size, uniformity of content, surface coverage, and aerosol performance. Secondly, comilled formulations with different API (1-40% w/w) concentrations were prepared and similarly analyzed. Comilled 5% MGST (w/w) formulation resulted in a significant improvement in in vitro aerosol performance due to the reduction in agglomerate size and strength compared to the formulation comilled without MGST. Higher concentrations of MGST (7.5% w/w) led to reduction in aerosol performance likely due to excessive surface coverage of the micronized particles by MGST, which led to failure in uniformity of content and an increase in agglomerate strength and size. Generally, comilled formulations with higher concentrations of API increased the agglomerate strength and size, which subsequently caused a reduction in aerosol performance. High-dose delivery was achieved at API concentration of >20% (w/w). The study provided a platform for the investigation of aerosol performance and physicochemical properties of other API and additive materials in comilled formulations for the emerging field of high-dose delivery by dry powder inhalation.

Separation of both fibrous and globular proteins on the basis of molecular weight using high-performance size exclusion chromatography.

PubMed

Barden, J A

1983-11-01

A high-performance size exclusion liquid chromatographic system has been used to separate proteins with different shapes solely on the basis of their molecular weights. After the effects of ionic and hydrophobic interactions with the stationary phase have been overcome, protein elution is normally governed by their effective size in solution. Conditions are described under which proteins, with isoelectric points within the normal operating pH range of the columns, are eluted independent of their Stokes' radii. Even fibrous proteins with axial ratios of 50 elute according to their known molecular weights over the range 2000-2,000,000.

Room temperature solvent-free reduction of SiCl4 to nano-Si for high-performance Li-ion batteries.

PubMed

Liu, Zhiliang; Chang, Xinghua; Sun, Bingxue; Yang, Sungjin; Zheng, Jie; Li, Xingguo

2017-06-06

SiCl 4 can be directly reduced to nano-Si with commercial Na metal under solvent-free conditions by mechanical milling. Crystalline nano-Si with an average size of 25 nm and quite uniform size distribution can be obtained, which shows excellent lithium storage performance, for a high reversible capacity of 1600 mA h g -1 after 500 cycles at 2.1 A g -1 .

Retention of nucleic acids in ion-pair reversed-phase high-performance liquid chromatography depends not only on base composition but also on base sequence.

PubMed

Qiao, Jun-Qin; Liang, Chao; Wei, Lan-Chun; Cao, Zhao-Ming; Lian, Hong-Zhen

2016-12-01

The study on nucleic acid retention in ion-pair reversed-phase high-performance liquid chromatography mainly focuses on size-dependence, however, other factors influencing retention behaviors have not been comprehensively clarified up to date. In this present work, the retention behaviors of oligonucleotides and double-stranded DNAs were investigated on silica-based C 18 stationary phase by ion-pair reversed-phase high-performance liquid chromatography. It is found that the retention of oligonucleotides was influenced by base composition and base sequence as well as size, and oligonucleotides prone to self-dimerization have weaker retention than those not prone to self-dimerization but with the same base composition. However, homo-oligonucleotides are suitable for the size-dependent separation as a special case of oligonucleotides. For double-stranded DNAs, the retention is also influenced by base composition and base sequence, as well as size. This may be attributed to the interaction of exposed bases in major or minor grooves with the hydrophobic alky chains of stationary phase. In addition, no specific influence of guanine and cytosine content was confirmed on retention of double-stranded DNAs. Notably, the space effect resulted from the stereostructure of nucleic acids also influences the retention behavior in ion-pair reversed-phase high-performance liquid chromatography. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Communication Studies of DMP and SMP Machines

NASA Technical Reports Server (NTRS)

Sohn, Andrew; Biswas, Rupak; Chancellor, Marisa K. (Technical Monitor)

1997-01-01

Understanding the interplay between machines and problems is key to obtaining high performance on parallel machines. This paper investigates the interplay between programming paradigms and communication capabilities of parallel machines. In particular, we explicate the communication capabilities of the IBM SP-2 distributed-memory multiprocessor and the SGI PowerCHALLENGEarray symmetric multiprocessor. Two benchmark problems of bitonic sorting and Fast Fourier Transform are selected for experiments. Communication-efficient algorithms are developed to exploit the overlapping capabilities of the machines. Programs are written in Message-Passing Interface for portability and identical codes are used for both machines. Various data sizes and message sizes are used to test the machines' communication capabilities. Experimental results indicate that the communication performance of the multiprocessors are consistent with the size of messages. The SP-2 is sensitive to message size but yields a much higher communication overlapping because of the communication co-processor. The PowerCHALLENGEarray is not highly sensitive to message size and yields a low communication overlapping. Bitonic sorting yields lower performance compared to FFT due to a smaller computation-to-communication ratio.

Research on the Influence of Size Effect for the mechanical Performance of GFRP tube concrete steel tube composite column under axial compression

NASA Astrophysics Data System (ADS)

Li, Wen; Wang, Tong; Na, Yu

2017-08-01

FRP tube-concrete-steel tube composite column (DSTC) was a new type of composite structures. The column consists of FRP outer tube and steel tube and concrete. Concrete was filled between FRP outer tube and steel tube. This column has the character of light and high strength and corrosion resistance. In this paper, properties of DSTC axial compression were studied in depth. The properties were studied by two groups DSTC short columns under axial compression performance experiment. The different size of DSTC short columns was importantly considered. According to results of the experiment, we can conclude that with the size of the column increases the ability of it to resist deformation drops. On the other hand, the size effect influences on properties of different concrete strength DSTC was different. The influence of size effect on high concrete strength was less than that of low concrete.

Photodiode area effect on performance of X-ray CMOS active pixel sensors

NASA Astrophysics Data System (ADS)

Kim, M. S.; Kim, Y.; Kim, G.; Lim, K. T.; Cho, G.; Kim, D.

2018-02-01

Compared to conventional TFT-based X-ray imaging devices, CMOS-based X-ray imaging sensors are considered next generation because they can be manufactured in very small pixel pitches and can acquire high-speed images. In addition, CMOS-based sensors have the advantage of integration of various functional circuits within the sensor. The image quality can also be improved by the high fill-factor in large pixels. If the size of the subject is small, the size of the pixel must be reduced as a consequence. In addition, the fill factor must be reduced to aggregate various functional circuits within the pixel. In this study, 3T-APS (active pixel sensor) with photodiodes of four different sizes were fabricated and evaluated. It is well known that a larger photodiode leads to improved overall performance. Nonetheless, if the size of the photodiode is > 1000 μm2, the degree to which the sensor performance increases as the photodiode size increases, is reduced. As a result, considering the fill factor, pixel-pitch > 32 μm is not necessary to achieve high-efficiency image quality. In addition, poor image quality is to be expected unless special sensor-design techniques are included for sensors with a pixel pitch of 25 μm or less.

Twinning to slip transition in ultrathin BCC Fe nanowires

NASA Astrophysics Data System (ADS)

Sainath, G.; Choudhary, B. K.

2018-04-01

We report twinning to slip transition with decreasing size and increasing temperature in ultrathin <100> BCC Fe nanowires. Molecular dynamics simulations have been performed on different nanowire size in the range 0.404-3.634 nm at temperatures ranging from 10 to 900 K. The results indicate that slip mode dominates at low sizes and high temperatures, while deformation twinning is promoted at high sizes and low temperatures. The temperature, at which the nanowires show twinning to slip transition, increases with increasing size. The different modes of deformation are also reflected appropriately in the respective stress-strain behaviour of the nanowires.

Size, Accumulation and Performance for Research Grants: Examining the Role of Size for Centres of Excellence

PubMed Central

Bloch, Carter; Schneider, Jesper W.; Sinkjær, Thomas

2016-01-01

The present paper examines the relation between size, accumulation and performance for research grants, where we examine the relation between grant size for Centres of Excellence (CoE) funded by the Danish National Research Foundation (DNRF) and various ex post research performance measures, including impact and shares of highly cited articles. We examine both the relation between size and performance and also how performance for CoEs evolves over the course of grant periods. In terms of dynamics, it appears that performance over the grant period (i.e. 10 years) is falling for the largest CoEs, while it is increasing for those among the smallest half. Overall, multivariate econometric analysis finds evidence that performance is increasing in grant size and over time. In both cases, the relation appears to be non-linear, suggesting that there is a point at which performance peaks. The CoEs have also been very successful in securing additional funding, which can be viewed as a ‘cumulative effect’ of center grants. In terms of new personnel, the far majority of additional funding is spent on early career researchers, hence, this accumulation would appear to have a ‘generational’ dimension, allowing for scientific expertise to be passed on to an increasing number of younger researchers. PMID:26862907

High Schools and High Stakes Testing in California: Size and Income Do Matter

ERIC Educational Resources Information Center

Rector, L. D.

2011-01-01

The purpose of this study was to examine the relationship between the size of high schools, their percentage of SED (socio-economic disadvantaged) students, and API (academic performance index) scores in California, and determine if teacher preparation is a contributing factor. The 2010 API scores and median income of all 52 counties, and the 2010…

An ultrasensitive bio-surrogate for nanoporous filter membrane performance metrology directed towards contamination control in microlithography applications

NASA Astrophysics Data System (ADS)

Ahmad, Farhan; Mish, Barbara; Qiu, Jian; Singh, Amarnauth; Varanasi, Rao; Bedford, Eilidh; Smith, Martin

2016-03-01

Contamination tolerances in semiconductor manufacturing processes have changed dramatically in the past two decades, reaching below 20 nm according to the guidelines of the International Technology Roadmap for Semiconductors. The move to narrower line widths drives the need for innovative filtration technologies that can achieve higher particle/contaminant removal performance resulting in cleaner process fluids. Nanoporous filter membrane metrology tools that have been the workhorse over the past decade are also now reaching limits. For example, nanoparticle (NP) challenge testing is commonly applied for assessing particle retention performance of filter membranes. Factors such as high NP size dispersity, low NP detection sensitivity, and high NP particle-filter affinity impose challenges in characterizing the next generation of nanoporous filter membranes. We report a novel bio-surrogate, 5 nm DNA-dendrimer conjugate for evaluating particle retention performance of nanoporous filter membranes. A technique capable of single molecule detection is employed to detect sparse concentration of conjugate in filter permeate, providing >1000- fold higher detection sensitivity than any existing 5 nm-sized particle enumeration technique. This bio-surrogate also offers narrow size distribution, high stability and chemical tunability. This bio-surrogate can discriminate various sub-15 nm pore-rated nanoporous filter membranes based on their particle retention performance. Due to high bio-surrogate detection sensitivity, a lower challenge concentration of bio-surrogate (as compared to other NPs of this size) can be used for filter testing, providing a better representation of customer applications. This new method should provide better understanding of the next generation filter membranes for removing defect-causing contaminants from lithography processes.

Preliminary test results for Li-SOCl2 high-rate D cells

NASA Technical Reports Server (NTRS)

Bragg, Bobby J.; Johnson, Paul

1992-01-01

The performance and abuse characteristics of 55 D-size lithium-thionyl chloride (Li-SOCl2) cells are evaluated at relatively high rates. Results from the following tests are presented: shock test, vibration test, capacity performance, uninsulated short circuit, high temperature exposure, and overdischarge.

Preliminary test results for Li-SOCl2 high-rate D cells

NASA Astrophysics Data System (ADS)

Bragg, Bobby J.; Johnson, Paul

1992-02-01

The performance and abuse characteristics of 55 D-size lithium-thionyl chloride (Li-SOCl2) cells are evaluated at relatively high rates. Results from the following tests are presented: shock test, vibration test, capacity performance, uninsulated short circuit, high temperature exposure, and overdischarge.

Friends With Performance Benefits: A Meta-Analysis on the Relationship Between Friendship and Group Performance.

PubMed

Chung, Seunghoo; Lount, Robert B; Park, Hee Man; Park, Ernest S

2018-01-01

The current article examines if, and under which conditions, there exists a positive relationship between working with friends and group performance. To do so, using data from 1,016 groups obtained from 26 studies, we meta-analyzed comparisons of the performance of friendship groups versus acquaintance groups. Results show that friendship has a significant positive effect on group task performance (Cohen's d = 0.31). Furthermore, this relationship was moderated by group size (i.e., the positive effect of friendship on performance increased with group size) and task focus (i.e., friendship groups performed better than acquaintance groups on tasks requiring a high quantity of output, whereas there was no performance benefit on tasks requiring a single or high-quality output). These results help to reconcile mixed findings and illustrate when friendship groups are more likely to perform better than acquaintance groups.

Large-area high-performance SERS substrates with deep controllable sub-10-nm gap structure fabricated by depositing Au film on the cicada wing

NASA Astrophysics Data System (ADS)

Jiwei, Qi; Yudong, Li; Ming, Yang; Qiang, Wu; Zongqiang, Chen; Wudeng, Wang; Wenqiang, Lu; Xuanyi, Yu; Jingjun, Xu; Qian, Sun

2013-10-01

Noble metal nanogap structure supports strong surface-enhanced Raman scattering (SERS) which can be used to detect single molecules. However, the lack of reproducible fabrication techniques with nanometer-level control over the gap size has limited practical applications. In this letter, by depositing the Au film onto the cicada wing, we engineer the ordered array of nanopillar structures on the wing to form large-area high-performance SERS substrates. Through the control of the thickness of the Au film deposited onto the cicada wing, the gap sizes between neighboring nanopillars are fine defined. SERS substrates with sub-10-nm gap sizes are obtained, which have the highest average Raman enhancement factor (EF) larger than 2 × 108, about 40 times as large as that of commercial Klarite® substrates. The cicada wings used as templates are natural and environment-friendly. The depositing method is low cost and high throughput so that our large-area high-performance SERS substrates have great advantage for chemical/biological sensing applications.

Effect of Sizings on the Durability of High Temperature Polymer Composites

NASA Technical Reports Server (NTRS)

Allred, Ronald E.; Shin, E. Eugene; Inghram, Linda; McCorkle, Linda; Papadopoulos, Demetrios; Wheeler, Donald; Sutter, James K.

2003-01-01

To increase performance and durability of high-temperature composite for potential rocket engine components, it is necessary to optimize wetting and interfacial bonding between high modulus carbon fibers and high-temperature polyimide resins. Sizing commercially supplied on most carbon fiber are not compatible with polyimides. In this study, the chemistry of sizing on two high modulus carbon fiber (M40J and M60J, Tiray) was characterized. A continuous desizling system that uses an environmentally friendly chemical-mechanical process was developed for tow level fiber. Composites were fabricated with fibers containing the manufacturer's sizing, desized, and further treated with a reactive finish. Results of room-temperature tests after thermal aging show that the reactive finish produces a higher strength and more durable interface compared to the manufacturer's sizing. When exposed to moisture blistering tests, however, the butter bonded composite displayed a tendency to delaminate, presumably due to trapping of volatiles.

Particle size and surface area effects on the thin-pulse shock initiation of Diaminoazoxyfurazan (DAAF)

NASA Astrophysics Data System (ADS)

Burritt, Rosemary; Francois, Elizabeth; Windler, Gary; Chavez, David

2017-06-01

Diaminoazoxyfurazan (DAAF) has many of the safety characteristics of an insensitive high explosive (IHE): it is extremely insensitive to impact and friction and is comparable to triaminotrinitrobezene (TATB) in this way. Conversely, it demonstrates many performance characteristics of a Conventional High Explosive (CHE). DAAF has a small failure diameter of about 1.25 mm and can be sensitive to shock under the right conditions. Large particle sized DAAF will not initiate in a typical exploding foil initiator (EFI) configuration but smaller particle sizes will. Large particle sized DAAF, of 40 μm, was crash precipitated and ball milled into six distinct samples and pressed into pellets with a density of 1.60 g/cc (91% TMD). To investigate the effect of particle size and surface area on the direct initiation on DAAF multiple threshold tests were preformed on each sample of DAAF in different EFI configurations, which varied in flyer thickness and/or bridge size. Comparative tests were performed examining threshold voltage and correlated to Photon Doppler Velocimetry (PDV) results. The samples with larger particle sizes and surface area required more energy to initiate while the smaller particle sizes required less energy and could be initiated with smaller diameter flyers.

Body size, performance and fitness in galapagos marine iguanas.

PubMed

Wikelski, Martin; Romero, L Michael

2003-07-01

Complex organismal traits such as body size are influenced by innumerable selective pressures, making the prediction of evolutionary trajectories for those traits difficult. A potentially powerful way to predict fitness in natural systems is to study the composite response of individuals in terms of performance measures, such as foraging or reproductive performance. Once key performance measures are identified in this top-down approach, we can determine the underlying physiological mechanisms and gain predictive power over long-term evolutionary processes. Here we use marine iguanas as a model system where body size differs by more than one order of magnitude between island populations. We identified foraging efficiency as the main performance measure that constrains body size. Mechanistically, foraging performance is determined by food pasture height and the thermal environment, influencing intake and digestion. Stress hormones may be a flexible way of influencing an individual's response to low-food situations that may be caused by high population density, famines, or anthropogenic disturbances like oil spills. Reproductive performance, on the other hand, increases with body size and is mediated by higher survival of larger hatchlings from larger females and increased mating success of larger males. Reproductive performance of males may be adjusted via plastic hormonal feedback mechanisms that allow individuals to assess their social rank annually within the current population size structure. When integrated, these data suggest that reproductive performance favors increased body size (influenced by reproductive hormones), with an overall limit imposed by foraging performance (influenced by stress hormones). Based on our mechanistic understanding of individual performances we predicted an evolutionary increase in maximum body size caused by global warming trends. We support this prediction using specimens collected during 1905. We also show in a common-garden experiment that body size may have a genetic component in iguanids. This 'performance paradigm' allows predictions about adaptive evolution in natural populations.

Facile synthesis and high-frequency performance of CoFe2O4 nanocubes with different size

NASA Astrophysics Data System (ADS)

Song, Ningning; Gu, Shangzhi; Wu, Qiong; Li, Chenglin; Zhou, Jun; Zhang, Panpan; Wang, Wei; Yue, Ming

2018-04-01

Magnetic materials with significant permeability and high resonance frequency are a challenge due to the Snoek limit, but it is possible to achieve breakthroughs by inducing superparamagnetism in magnetic nanoparticles. Here, size-controlled monodisperse CoFe2O4 nanocubes (NCs) were successfully synthesized via a facile high-temperature organic-phase method. The superparamagnetic/ferrimagnetic relaxation induced high frequency properties of CoFe2O4 NCs controlled by particle size has been investigated. The resonance frequency of CoFe2O4 NCs increases from 6.0 GHz to 6.3 GHz with decreasing particle size from 40 to 19 nm. With further decreasing particle size to 13 nm, no resonance peak can be observed in the measured frequencies from 4 GHz to 10 GHz, which can be attributed to the superparamagnetic/ferromagnetic relaxation tuned by particle sizes. This finding opens up a straightforward avenue for optimizing high frequency properties of magnetic nanomaterials.

A surfactant free preparation of ultradispersed surface-clean Pt catalyst with highly stable electrocatalytic performance

NASA Astrophysics Data System (ADS)

Tao, Lu; Zhao, Yueping; Zhao, Yufeng; Huang, Shifei; Yang, Yunxia; Tong, Qi; Gao, Faming

2018-02-01

High efficiency platinum-based catalyst demands the ultrafine size and well dispersion of Pt nanoparticles (NPs), with clean surface and strong interactions between the supports. In this work, we demonstrate a simple strategy for the preparation of ultra-dispersed surface-clean Pt catalyst with high stability, in which the Pt nanoparticles (NPs) with 1.8 ± 0.6 nm in size are anchored tightly on a 3D hierarchical porous graphitized carbon (3D-HPG) through galvanic replacement reaction. The as-obtained catalyst can undergo 2000 voltage cycles with negligible activity decay and no apparent structure and size changes for MOR during the durability test, and its mass activity for ORR only reduce 18.3% after 5000 cycles. The excellent performance is attributed to strong anchoring effect between carbon support and Pt nanoparticles.

Behavior of high-performance concrete in structural applications.

DOT National Transportation Integrated Search

2007-10-01

High Performance Concrete (HPC) with improved properties has been developed by obtaining the maximum density of the matrix. Mathematical models developed by J.E. Funk and D.R. Dinger, are used to determine the particle size distribution to achieve th...

Breaking Free of Sample Size Dogma to Perform Innovative Translational Research

PubMed Central

Bacchetti, Peter; Deeks, Steven G.; McCune, Joseph M.

2011-01-01

Innovative clinical and translational research is often delayed or prevented by reviewers’ expectations that any study performed in humans must be shown in advance to have high statistical power. This supposed requirement is not justifiable and is contradicted by the reality that increasing sample size produces diminishing marginal returns. Studies of new ideas often must start small (sometimes even with an N of 1) because of cost and feasibility concerns, and recent statistical work shows that small sample sizes for such research can produce more projected scientific value per dollar spent than larger sample sizes. Renouncing false dogma about sample size would remove a serious barrier to innovation and translation. PMID:21677197

Solvent evaporation induced graphene powder with high volumetric capacitance and outstanding rate capability for supercapacitors

NASA Astrophysics Data System (ADS)

Zhang, Xiaozhe; Raj, Devaraj Vasanth; Zhou, Xufeng; Liu, Zhaoping

2018-04-01

Graphene-based electrode materials for supercapacitors usually suffer from poor volumetric performance due to the low density. The enhancement of volumetric capacitance by densification of graphene materials, however, is usually accompanied by deterioration of rate capability, as the huge contraction of pore size hinders rapid diffusion of electrolytes. Thus, it is important to develop suitable pore size in graphene materials, which can sustain fast ion diffusion and avoid excessive voids to acquire high density simultaneously for supercapacitor applications. Accordingly, we propose a simple solvent evaporation method to control the pore size of graphene powders by adjusting the surface tension of solvents. Ethanol is used instead of water to reduce the shrinkage degree of graphene powder during solvent evaporation process, due to its lower surface tension comparing with water. Followed by the assistance of mechanical compression, graphene powder having high compaction density of 1.30 g cm-3 and a large proportion of mesopores in the pore size range of 2-30 nm is obtained, which delivers high volumetric capacitance of 162 F cm-3 and exhibits outstanding rate performance of 76% capacity retention at a high current density of 100 A g-1 simultaneously.

Evaluation of high-energy-efficiency powertrain approaches: the 1996 futurecar challenge

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sluder, S.; Duoba, M.; Larsen, R.

Twelve colleges and universities were selected to design, build, and develop a mid-size vehicle that could achieve high energy economy while maintaining the performance characteristics of today`s mid-size vehicle. Many of the teams were able to increase the fuel economy of their vehicles, but most of these increases came at the expense of decreased performance or worsened emissions. This paper evaluates and summarizes the high-energy-efficiency powertrain technology approaches that were utilized in the 1996 FutureCar Challenge, which was the first evaluation of these vehicles in a two-year program. Of the 11 vehicles evaluated in the competition, nine utilized hybrid electricmore » vehicle approaches. This paper discusses the design trade- offs made by the teams to achieve high efficiency while trying to maintain stock performance.« less

Coordinates for a High Performance 4:1 Pressure Ratio Centrifugal Compressor

NASA Technical Reports Server (NTRS)

McKain, Ted F.; Holbrook, Greg J.

1997-01-01

The objective of this program was to define the aerodynamic design and manufacturing coordinates for an advanced 4:1 pressure ratio, single stage centrifugal compressor at a 10 lbm/sec flow size. The approach taken was to perform an exact scale of an existing DDA compressor originally designed at a flow size of 3.655 lbm/sec.

Development of a magnetic solid-phase extraction coupled with high-performance liquid chromatography method for the analysis of polyaromatic hydrocarbons.

PubMed

Ma, Yan; Xie, Jiawen; Jin, Jing; Wang, Wei; Yao, Zhijian; Zhou, Qing; Li, Aimin; Liang, Ying

2015-07-01

A novel magnetic solid phase extraction coupled with high-performance liquid chromatography method was established to analyze polyaromatic hydrocarbons in environmental water samples. The extraction conditions, including the amount of extraction agent, extraction time, pH and the surface structure of the magnetic extraction agent, were optimized. The results showed that the amount of extraction agent and extraction time significantly influenced the extraction performance. The increase in the specific surface area, the enlargement of pore size, and the reduction of particle size could enhance the extraction performance of the magnetic microsphere. The optimized magnetic extraction agent possessed a high surface area of 1311 m(2) /g, a large pore size of 6-9 nm, and a small particle size of 6-9 μm. The limit of detection for phenanthrene and benzo[g,h,i]perylene in the developed analysis method was 3.2 and 10.5 ng/L, respectively. When applied to river water samples, the spiked recovery of phenanthrene and benzo[g,h,i]perylene ranged from 89.5-98.6% and 82.9-89.1%, respectively. Phenanthrene was detected over a concentration range of 89-117 ng/L in three water samples withdrawn from the midstream of the Huai River, and benzo[g,h,i]perylene was below the detection limit. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Resolution performance of a 0.60-NA, 364-nm laser direct writer

NASA Astrophysics Data System (ADS)

Allen, Paul C.; Buck, Peter D.

1990-06-01

ATEQ has developed a high resolution laser scanning printing engine based on the 8 beam architecture of the CORE- 2000. This printing engine has been incorporated into two systems: the CORE-2500 for the production of advanced masks and reticles and a prototype system for direct write on wafers. The laser direct writer incorporates a through-the-lens alignment system and a rotary chuck for theta alignment. Its resolution performance is delivered by a 0. 60 NA laser scan lens and a novel air-jet focus system. The short focal length high resolution lens also reduces beam position errors thereby improving overall pattern accuracy. In order to take advantage of the high NA optics a high performance focus servo was developed capable of dynamic focus with a maximum error of 0. 15 tm. The focus system uses a hot wire anemometer to measure air flow through an orifice abutting the wafer providing a direct measurement to the top surface of resist independent of substrate properties. Lens specifications are presented and compared with the previous design. Bench data of spot size vs. entrance pupil filling show spot size performance down to 0. 35 m FWHM. The lens has a linearity specification of 0. 05 m system measurements of lens linearity indicate system performance substantially below this. The aerial image of the scanned beams is measured using resist as a threshold detector. An effective spot size is

Why does offspring size affect performance? Integrating metabolic scaling with life-history theory

PubMed Central

Pettersen, Amanda K.; White, Craig R.; Marshall, Dustin J.

2015-01-01

Within species, larger offspring typically outperform smaller offspring. While the relationship between offspring size and performance is ubiquitous, the cause of this relationship remains elusive. By linking metabolic and life-history theory, we provide a general explanation for why larger offspring perform better than smaller offspring. Using high-throughput respirometry arrays, we link metabolic rate to offspring size in two species of marine bryozoan. We found that metabolism scales allometrically with offspring size in both species: while larger offspring use absolutely more energy than smaller offspring, larger offspring use proportionally less of their maternally derived energy throughout the dependent, non-feeding phase. The increased metabolic efficiency of larger offspring while dependent on maternal investment may explain offspring size effects—larger offspring reach nutritional independence (feed for themselves) with a higher proportion of energy relative to structure than smaller offspring. These findings offer a potentially universal explanation for why larger offspring tend to perform better than smaller offspring but studies on other taxa are needed. PMID:26559952

Complex life cycles and offspring provisioning in marine invertebrates.

PubMed

Marshall, Dustin J; Keough, Michael J

2006-10-01

Offspring size can have pervasive effects throughout an organism's life history. Mothers can make either a few large or many small offspring, and the balance between these extremes is determined by the relationship between offspring size and performance. This relationship in turn is thought to be determined by the offspring's environment. Recently, it has become clear that events in one life-history stage can strongly affect performance in another. Given these strong carryover effects, we asked whether events in the larval phase can change the relationship between offspring size and performance in the adult phase. We manipulated the length of the larval period in the bryozoan Bugula neritina and then examined the relationship between offspring size and various parameters of adult performance under field conditions. We found that despite the adult stage being outplanted into identical conditions, different offspring sizes were predicted to be optimal, depending on the experience of those adults as larvae. This work highlights the fact that the strong phenotypic links between life-history stages may result in optimal offspring size being highly unpredictable for organisms with complex life cycles.

Integrated Flight Performance Analysis of a Launch Abort System Concept

NASA Technical Reports Server (NTRS)

Tartabini, Paul V.

2007-01-01

This paper describes initial flight performance analyses conducted early in the Orion Project to support concept feasibility studies for the Crew Exploration Vehicle s Launch Abort System (LAS). Key performance requirements that significantly affect abort capability are presented. These requirements have implications on sizing the Abort Motor, tailoring its thrust profile to meet escape requirements for both launch pad and high drag/high dynamic pressure ascent aborts. Additional performance considerations are provided for the Attitude Control Motor, a key element of the Orion LAS design that eliminates the need for ballast and provides performance robustness over a passive control approach. Finally, performance of the LAS jettison function is discussed, along with implications on Jettison Motor sizing and the timing of the jettison event during a nominal mission. These studies provide an initial understanding of LAS performance that will continue to evolve as the Orion design is matured.

Fingerprinting profile of polysaccharides from Lycium barbarum using multiplex approaches and chemometrics

USDA-ARS?s Scientific Manuscript database

Techniques including ultraviolet-visible spectra (UV), high performance size-exclusion chromatography (HPSEC), fourier-transform infrared spectroscopy (FT-IR) and pre-column derivatization high-performance liquid chromatography (PCD-HPLC) were used in the fingerprinting analysis of Lycium barbarum p...

Biodegradable sizing agents from soy protein via controlled hydrolysis and dis-entanglement for remediation of textile effluents.

PubMed

Yang, Maiping; Xu, Helan; Hou, Xiuliang; Zhang, Jie; Yang, Yiqi

2017-03-01

Fully biodegradable textile sizes with satisfactory performance properties were developed from soy protein with controlled hydrolysis and dis-entanglement to tackle the intractable environmental issues associated with the non-biodegradable polyvinyl alcohol (PVA) in textile effluents. PVA derived from petroleum is the primary sizing agent due to its excellent sizing performance on polyester-containing yarns, especially in increasingly prevailing high-speed weaving. However, due to the poor biodegradability, PVA causes serious environmental pollution, and thus, should be substituted with more environmentally friendly polymers. Soy protein treated with high amount of triethanolamine was found with acceptable sizing properties. However, triethanolamine is also non-biodegradable and originated from petroleum, therefore, is not an ideal additive. In this research, soy sizes were developed from soy protein treated with glycerol, the biodegradable triol that could also be obtained from soy. The soy sizes had good film properties, adhesion to polyester and abrasion resistance close to PVA, rendering them qualified for sizing applications. Regarding desizing, consumption of water and energy for removal of soy size could be remarkably decreased, comparing to removal of PVA. Moreover, with satisfactory degradability, the wastewater containing soy sizes was readily dischargeable after treated in activated sludge for two days. In summary, the fully biodegradable soy sizes had potential to substitute PVA for sustainable textile processing. Copyright © 2016 Elsevier Ltd. All rights reserved.

High School Size, Participation in Activities, and Young Adult Social Participation: Some Enduring Effects of Schooling.

ERIC Educational Resources Information Center

Lindsay, Paul

1984-01-01

This study evaluates a model predicting that school size affects student participation in extracurricular activities and that these leisure interests will continue in young adult life. High school social participation, it is hypothesized, also is influenced by curriculum track placement and academic performance, which are affected by student…

Key to enhance thermoelectric performance by controlling crystal size of strontium titanate

NASA Astrophysics Data System (ADS)

Wang, Jun; Ye, Xinxin; Yaer, Xinba; Wu, Yin; Zhang, Boyu; Miao, Lei

2015-09-01

One-step molten salt synthesis process was introduced to fabricate nano to micrometer sized SrTiO3 powders in which effects of synthesis temperature, oxide-to-flux ratios and raw materials on the generation of SrTiO3 powders were examined. 100 nm or above sized pure SrTiO3 particles were obtained at relatively lower temperature of 900∘C. Micro-sized rhombohedral crystals with a maximum size of approximately 12 μm were obtained from SrCO3 or Sr(NO3)2 strontium source with 1:1 O/S ratio. Controlled crystal size and morphology of Nb-doped SrTiO3 particles are prepared by using this method to confirm the performance of thermoelectric properties. The Seebeck coefficient obtained is significantly high when compared with the reported data, and the high ratio of nano particles in the sample has a positive effect on the increase of Seebeck coefficient too, which is likely due to the energy filtering effect at large numbers of grain boundaries resulting from largely distributed structure.

Study of TiO2 particles size, dyes, and catalyst to improve the performance of DSSC

NASA Astrophysics Data System (ADS)

Saehana, Sahrul; Darsikin, Muslimin

2016-02-01

This study reports effort to improve performance of solar cells by using various natural dyes in dye-sensitized solar cell (DSSC). We applied three kind of natural dye, i.e, black rice dye, cactus dye and dragon fruit dye. We found that performance of DSSC which employ black rice dye was higher than other natural dyes. It is because the wider spectrum wavelength of black rice dyes. Its performance also compared with rhutenium dye (N719). Effect of TiO2 particle to DSSC performance was also investigated. It was concluded that smaller TiO2 particle size will increase the performance of DSSC solar cells. It was because the smaller particle size (high surface area) will load more dye. In addition, we also demonstrated the use of graphite from lead pencil as counter electrode.

A 65 Ah rechargeable lithium molybdenum disulfide battery

NASA Technical Reports Server (NTRS)

Brandt, K.

1986-01-01

A rechargeable lithium molybdenum disulfide battery which has a number of superior performance characteristics which includes a high energy density, a high power density, and a long charge retention time was developed. The first cell sizes developed included a C size cell and an AA size cell. Over the last two years, a project to demonstrate the feasibility of the scale up to this technology to a BC size cell with 65 Ah capacity was undertaken. The objective was to develop, build, and test a .6 kWh storage battery consisting of 6 BC cells in series.

Numerical studies on sizing/ rating of plate fin heat exchangers for a modified Claude cycle based helium liquefier/ refrigerator

NASA Astrophysics Data System (ADS)

Goyal, M.; Chakravarty, A.; Atrey, M. D.

2017-02-01

Performance of modern helium refrigeration/ liquefaction systems depends significantly on the effectiveness of heat exchangers. Generally, compact plate fin heat exchangers (PFHE) having very high effectiveness (>0.95) are used in such systems. Apart from basic fluid film resistances, various secondary parameters influence the sizing/ rating of these heat exchangers. In the present paper, sizing calculations are performed, using in-house developed numerical models/ codes, for a set of high effectiveness PFHE for a modified Claude cycle based helium liquefier/ refrigerator operating in the refrigeration mode without liquid nitrogen (LN2) pre-cooling. The combined effects of secondary parameters like axial heat conduction through the heat exchanger metal matrix, parasitic heat in-leak from surroundings and variation in the fluid/ metal properties are taken care of in the sizing calculation. Numerical studies are carried out to predict the off-design performance of the PFHEs in the refrigeration mode with LN2 pre-cooling. Iterative process cycle calculations are also carried out to obtain the inlet/ exit state points of the heat exchangers.

TiO2 Nanotube Arrays: Fabricated by Soft-Hard Template and the Grain Size Dependence of Field Emission Performance

NASA Astrophysics Data System (ADS)

Yang, Xuxin; Ma, Pei; Qi, Hui; Zhao, Jingxin; Wu, Qiang; You, Jichun; Li, Yongjin

2017-11-01

Highly ordered TiO2 nanotube (TNT) arrays were successfully synthesized by the combination of soft and hard templates. In the fabrication of them, anodic aluminum oxide membranes act as the hard template while the self-assembly of polystyrene-block-poly(ethylene oxide) (PS-b-PEO) complexed with titanium-tetraisopropoxide (TTIP, the precursor of TiO2) provides the soft template to control the grain size of TiO2 nanotubes. Our results indicate that the field emission (FE) performance depends crucially on the grain size of the calcinated TiO2 which is dominated by the PS-b-PEO and its blending ratio with TTIP. The optimized sample (with the TTIP/PEO ratio of 3.87) exhibits excellent FE performances involving both a low turn-on field of 3.3 V/um and a high current density of 7.6 mA/cm2 at 12.7 V/μm. The enhanced FE properties can be attributed to the low effective work function (1.2 eV) resulted from the smaller grain size of TiO2.

Research on droplet size measurement of impulse antiriots water cannon based on sheet laser

NASA Astrophysics Data System (ADS)

Fa-dong, Zhao; Hong-wei, Zhuang; Ren-jun, Zhan

2014-04-01

As a new-style counter-personnel non-lethal weapon, it is the non-steady characteristic and large water mist field that increase the difficulty of measuring the droplet size distribution of impulse anti-riots water cannon which is the most important index to examine its tactical and technology performance. A method based on the technologies of particle scattering, sheet laser imaging and high speed handling was proposed and an universal droplet size measuring algorithm was designed and verified. According to this method, the droplet size distribution was measured. The measuring results of the size distribution under the same position with different timescale, the same axial distance with different radial distance, the same radial distance with different axial distance were analyzed qualitatively and some rational cause was presented. The droplet size measuring method proposed in this article provides a scientific and effective experiment method to ascertain the technical and tactical performance and optimize the relative system performance.

Large-scale three-dimensional phase-field simulations for phase coarsening at ultrahigh volume fraction on high-performance architectures

NASA Astrophysics Data System (ADS)

Yan, Hui; Wang, K. G.; Jones, Jim E.

2016-06-01

A parallel algorithm for large-scale three-dimensional phase-field simulations of phase coarsening is developed and implemented on high-performance architectures. From the large-scale simulations, a new kinetics in phase coarsening in the region of ultrahigh volume fraction is found. The parallel implementation is capable of harnessing the greater computer power available from high-performance architectures. The parallelized code enables increase in three-dimensional simulation system size up to a 5123 grid cube. Through the parallelized code, practical runtime can be achieved for three-dimensional large-scale simulations, and the statistical significance of the results from these high resolution parallel simulations are greatly improved over those obtainable from serial simulations. A detailed performance analysis on speed-up and scalability is presented, showing good scalability which improves with increasing problem size. In addition, a model for prediction of runtime is developed, which shows a good agreement with actual run time from numerical tests.

Self-assembled asymmetric membrane containing micron-size germanium for high capacity lithium ion batteries

DOE PAGES

Byrd, Ian; Chen, Hao; Webber, Theron; ...

2015-10-23

We report the formation of novel asymmetric membrane electrode containing micron-size (~5 μm) germanium powders through a self-assembly phase inversion method for high capacity lithium ion battery anode. 850 mA h g -1 capacity (70%) can be retained at a current density of 600 mA g -1 after 100 cycles with excellent rate performance. Such a high retention rate has rarely been seen for pristine micron-size germanium anodes. Moreover, scanning electron microscope studies reveal that germanium powders are uniformly embedded in a networking porous structure consisting of both nanopores and macropores. It is believed that such a unique porous structuremore » can efficiently accommodate the ~260% volume change during germanium alloying and de-alloying process, resulting in an enhanced cycling performance. Finally, these porous membrane electrodes can be manufactured in large scale using a roll-to-roll processing method.« less

Extended Range Intercept Technology

DTIC Science & Technology

1991-09-01

particle size other than Freon class fluids. The requirements for a solvent used in grinding ammonium perchlorate to a one micron particle size are high...demonstrate a preprototype missile and launch control systems technology for tactical missile defense applications, including performance ...these two flights would be to verify flight performance and stability of the basic air frame and control system design (LTV Missiles and 1 -2 wp«-2a

The effect of plate position and size on tibial slope in high tibial osteotomy: a cadaveric study.

PubMed

Rubino, L Joseph; Schoderbek, Robert J; Golish, S Raymond; Baumfeld, Joshua; Miller, Mark D

2008-01-01

Opening wedge high tibial osteotomies are performed for degenerative changes and varus. Opening wedge osteotomies can change proximal tibial slope in the sagittal plane, possibly imparting stability in the ACL-deficient knee. The aim of this study was to assess the effect of plate position and size on change in tibial slope. Eight cadaveric knees underwent opening wedge high tibial osteotomy with Puddu plates of each different size. Plates were placed anterior, central, and posterior for each size used. Lateral radiographs were obtained. Tibial slope was measured and compared with baseline slope. Tibial slope was affected by plate position (P < 0.05) and size (P < 0.001). Smaller, posterior plates had less effect on tibial slope. However, anterior and central plates increased tibial slope over all plate sizes (P < 0.05). This study found that tibial slope increases with opening wedge high tibial osteotomy. Larger corrections and anterior placement of the plate are associated with larger increases in slope.

Simple size control of TiO2 nanoparticles and their electrochemical performance: emphasizing the contribution of the surface area to lithium storage at high-rates

NASA Astrophysics Data System (ADS)

Lim, Joohyun; Um, Ji Hyun; Lee, Kyung Jae; Yu, Seung-Ho; Kim, Young-Jae; Sung, Yung-Eun; Lee, Jin-Kyu

2016-03-01

The particle size effects of TiO2 nanoparticles (TNPs), which are composed of small crystallites, on Li ion storage are a very fundamental and important subject. However, size control of TNPs under 200 nm using a sol-gel method has been limited due to the highly reactive precursor, titanium alkoxide. In this study, TNPs with various sizes even under 100 nm are obtained by controlling the reactant concentrations in a mixed solvent of ethanol and acetonitrile. Among them, three different sizes of TNPs are prepared to compare the Li ion storage capacity, and 60 nm TNPs are found to have the best reversible capacity of 182 mA h g-1 after 50 cycles at 1 C and a remarkable rate performance of 120 mA h g-1 at 10 C. Capacity increase upon cycling is observed in the size-controlled TNPs, and the explanation of this phenomenon is proposed to the lattice volume expansion of TiO2 upon intercalation for enabling further penetration of the electrolyte into the particles' interior. Moreover, the capacity at high rates is more closely related to the surface area from Hg porosimetry analysis than from typical N2 adsorption/desorption analysis.The particle size effects of TiO2 nanoparticles (TNPs), which are composed of small crystallites, on Li ion storage are a very fundamental and important subject. However, size control of TNPs under 200 nm using a sol-gel method has been limited due to the highly reactive precursor, titanium alkoxide. In this study, TNPs with various sizes even under 100 nm are obtained by controlling the reactant concentrations in a mixed solvent of ethanol and acetonitrile. Among them, three different sizes of TNPs are prepared to compare the Li ion storage capacity, and 60 nm TNPs are found to have the best reversible capacity of 182 mA h g-1 after 50 cycles at 1 C and a remarkable rate performance of 120 mA h g-1 at 10 C. Capacity increase upon cycling is observed in the size-controlled TNPs, and the explanation of this phenomenon is proposed to the lattice volume expansion of TiO2 upon intercalation for enabling further penetration of the electrolyte into the particles' interior. Moreover, the capacity at high rates is more closely related to the surface area from Hg porosimetry analysis than from typical N2 adsorption/desorption analysis. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr00104a

COTS Ceramic Chip Capacitors: An Evaluation of the Parts and Assurance Methodologies

NASA Technical Reports Server (NTRS)

Brusse, Jay A.; Sampson, Michael J.

2004-01-01

Commercial-Off-The-Shelf (COTS) multilayer ceramic chip capacitors (MLCCs) are continually evolving to reduce physical size and increase volumetric efficiency. Designers of high reliability aerospace and military systems are attracted to these attributes of COTS MLCCs and would like to take advantage of them while maintaining the high standards for long-term reliable operation they are accustomed io when selecting military qualified established reliability (MIL-ER) MLCCs. However, MIL-ER MLCCs are not available in the full range of small chip sizes with high capacitance as found in today's COTS MLCCs. The objectives for this evaluation were to assess the long-term performance of small case size COTS MLCCs and to identify effective, lower-cost product assurance methodologies. Fifteen (15) lots of COTS X7R dielectric MLCCs from four (4) different manufacturers and two (2) MIL-ER BX dielectric MLCCs from two (2) of the same manufacturers were evaluated. Both 0805 and 0402 chip sizes were included. Several voltage ratings were tested ranging from a high of 50 volts to a low of 6.3 volts. The evaluation consisted of a comprehensive screening and qualification test program based upon MIL-PRF-55681 (i.e., voltage conditioning, thermal shock, moisture resistance, 2000-hour life test, etc.). In addition, several lot characterization tests were performed including Destructive Physical Analysis (DPA), Highly Accelerated Life Test (HALT) and Dielectric Voltage Breakdown Strength. The data analysis included a comparison of the 2000-hour life test results (used as a metric for long-term performance) relative to the screening and characterization test results. Results of this analysis indicate that the long-term life performance of COTS MLCCs is variable -- some lots perform well, some lots perform poorly. DPA and HALT were found to be promising lot characterization tests to identify substandard COTS MLCC lots prior to conducting more expensive screening and qualification tests. The results indicate that lot- specific screening and qualification are still recommended for high reliability applications. One significant and concerning observation is that MIL- type voltage conditioning (100 hours at twice rated voltage, 125 C) was not an effective screen in removing infant mortality parts for the particular lots of COTS MLCCs evaluated.

Space Vehicle Power System Comprised of Battery/Capacitor Combinations

NASA Technical Reports Server (NTRS)

Camarotte, C.; Lancaster, G. S.; Eichenberg, D.; Butler, S. M.; Miller, J. R.

2002-01-01

Recent improvements in energy densities of batteries open the possibility of using electric rather that hydraulic actuators in space vehicle systems. However, the systems usually require short-duration, high-power pulses. This power profile requires the battery system to be sized to meet the power requirements rather than stored energy requirements, often resulting in a large and inefficient energy storage system. Similar transient power applications have used a combination of two or more disparate energy storage technologies. For instance, placing a capacitor and a battery side-by-side combines the high energy density of a battery with the high power performance of a capacitor and thus can create a lighter and more compact system. A parametric study was performed to identify favorable scenarios for using capacitors. System designs were then carried out using equivalent circuit models developed for five commercial electrochemical capacitor products. Capacitors were sized to satisfy peak power levels and consequently "leveled" the power requirement of the battery, which can then be sized to meet system energy requirements. Simulation results clearly differentiate the performance offered by available capacitor products for the space vehicle applications.

Effects of turbine cooling assumptions on performance and sizing of high-speed civil transport

NASA Technical Reports Server (NTRS)

Senick, Paul F.

1992-01-01

The analytical study presented examines the effects of varying turbine cooling assumptions on the performance of a high speed civil transport propulsion system as well as the sizing sensitivity of this aircraft to these performance variations. The propulsion concept employed in this study was a two spool, variable cycle engine with a sea level thrust of 55,000 lbf. The aircraft used for this study was a 250 passenger vehicle with a cruise Mach number of 2.4 and 5000 nautical mile range. The differences in turbine cooling assumptions were represented by varying the amount of high pressure compressor bleed air used to cool the turbines. It was found that as this cooling amount increased, engine size and weight increased, but specific fuel consumption (SFC) decreased at takeoff and climb only. Because most time is spent at cruise, the SFC advantage of the higher bleed engines seen during subsonic flight was minimized and the lower bleed, lighter engines led to the lowest takeoff gross weight vehicles. Finally, the change in aircraft takeoff gross weight versus turbine cooling level is presented.

Size Matters. The Relevance and Hicksian Surplus of Preferred College Class Size

ERIC Educational Resources Information Center

Mandel, Philipp; Susmuth, Bernd

2011-01-01

The contribution of this paper is twofold. First, we examine the impact of class size on student evaluations of instructor performance using a sample of approximately 1400 economics classes held at the University of Munich from Fall 1998 to Summer 2007. We offer confirmatory evidence for the recent finding of a large, highly significant, and…

Effect of Particle Size and Operating Conditions on Pt 3Co PEMFC Cathode Catalyst Durability

DOE PAGES

Gummalla, Mallika; Ball, Sarah; Condit, David; ...

2015-05-29

The initial performance and decay trends of polymer electrolyte membrane fuel cells (PEMFC) cathodes with Pt 3Co catalysts of three mean particle sizes (4.9 nm, 8.1 nm, and 14.8 nm) with identical Pt loadings are compared. Even though the cathode based on 4.9 nm catalyst exhibited the highest initial electrochemical surface area (ECA) and mass activity, the cathode based on 8.1 nm catalyst showed better initial performance at high currents. Owing to the low mass activity of the large particles, the initial performance of the 14.8 nm Pt3Co-based electrode was the lowest. The performance decay rate of the electrodes withmore » the smallest Pt 3Co particle size was the highest and that of the largest Pt 3Co particle size was lowest. Interestingly, with increasing number of decay cycles (0.6 to 1.0 V, 50 mV/s), the relative improvement in performance of the cathode based on 8.1 nm Pt 3Co over the 4.9 nm Pt 3Co increased, owing to better stability of the 8.1 nm catalyst. The electron microprobe analysis (EMPA) of the decayed membrane-electrode assembly (MEA) showed that the amount of Co in the membrane was lower for the larger particles, and the platinum loss into the membrane also decreased with increasing particle size. This suggests that the higher initial performance at high currents with 8.1 nm Pt 3Co could be due to lower contamination of the ionomer in the electrode. Furthermore, lower loss of Co from the catalyst with increased particle size could be one of the factors contributing to the stability of ECA and mass activity of electrodes with larger cathode catalyst particles. To delineate the impact of particle size and alloy effects, these results are compared with prior work from our research group on size effects of pure platinum catalysts. The impact of PEMFC operating conditions, including upper potential, relative humidity, and temperature on the alloy catalyst decay trends, along with the EMPA analysis of the decayed MEAs, are reported.« less

Generating high-quality single droplets for optical particle characterization with an easy setup

NASA Astrophysics Data System (ADS)

Xu, Jie; Ge, Baozhen; Meng, Rui

2018-06-01

The high-performance and micro-sized single droplet is significant for optical particle characterization. We develop a single-droplet generator (SDG) based on a piezoelectric inkjet technique with advantages of low cost and easy setup. By optimizing the pulse parameters, we achieve various size single droplets. Further investigations reveal that SDG generates single droplets of high quality, demonstrating good sphericity, monodispersity and a stable length of several millimeters.

Femoral stem size mismatch in women undergoing total hip arthroplasty.

PubMed

Dundon, John M; Felberbaum, Dvorah Leah; Long, William J

2018-06-01

Total hip arthroplasty (THA) is a highly successful surgery with a high prevalence in women. Women have been noted to have smaller proximal femoral anatomy and decreased bone strength compared to males. The goal of our study was to define the size discrepancy in femoral stem implants between men and women using a metaphyseal fitting single taper stem. We retrospectively reviewed the THA's performed by a single surgeon over the previous two years. Data was extracted from operative reports regarding stem size, neck length and offset, and conversion to a different type of stem. This data was reviewed with confidence intervals and a t -test was performed for independent samples with a p < 0.05 being determined significant. We analyzed the data from 276 THA's performed (129 in men, and 147 in women). Women were noted to be associated with smaller stem sizes compared to men (37.67% in women, 6.11% in men), with 7.48% of women requiring conversion to a different type of implant. There was a significant difference in mean stem size (9.21 in men, 6.70 in women, p < 0.0001). Women also required reduced neck options significantly more often than men (38.97% in women, 9.29% in men, p < 0.0001). Review of femoral stem sizes reveals that current femoral stem sizing may not appropriately account for women and alternative stem options should be available if using a metaphyseal fitting single tapered stems. Future consideration should be given to more anatomic female sized femoral stems or alternative options should be available.

Effect of a trade between boattail angle and wedge size on the performance of a nonaxisymmetric wedge nozzle

NASA Technical Reports Server (NTRS)

Carson, George T., Jr.; Bare, E. Ann; Burley, James R., II

1987-01-01

An investigation was conducted in the Langley 16-Foot Transonic Tunnel to determine the effect of a boattail angle and wedge-size trade on the performance of nonaxisymmetric wedge nozzles installed on a generic twin-engine fighter aircraft model. Test data were obtained at static conditions and at Mach numbers from 0.60 to 1.25. Angle of attack was held constant at 0 deg. High-pressure air was used to simulate jet exhaust, and the nozzle pressure ratio was varied from 1.0 (jet off) to slightly over 15.0. For the configurations studied, the results indicate that wedge size can be reduced without affecting aeropropulsive performance.

Computational study of 3-D hot-spot initiation in shocked insensitive high-explosive

NASA Astrophysics Data System (ADS)

Najjar, F. M.; Howard, W. M.; Fried, L. E.; Manaa, M. R.; Nichols, A., III; Levesque, G.

2012-03-01

High-explosive (HE) material consists of large-sized grains with micron-sized embedded impurities and pores. Under various mechanical/thermal insults, these pores collapse generating hightemperature regions leading to ignition. A hydrodynamic study has been performed to investigate the mechanisms of pore collapse and hot spot initiation in TATB crystals, employing a multiphysics code, ALE3D, coupled to the chemistry module, Cheetah. This computational study includes reactive dynamics. Two-dimensional high-resolution large-scale meso-scale simulations have been performed. The parameter space is systematically studied by considering various shock strengths, pore diameters and multiple pore configurations. Preliminary 3-D simulations are undertaken to quantify the 3-D dynamics.

A 16K-bit static IIL RAM with 25-ns access time

NASA Astrophysics Data System (ADS)

Inabe, Y.; Hayashi, T.; Kawarada, K.; Miwa, H.; Ogiue, K.

1982-04-01

A 16,384 x 1-bit RAM with 25-ns access time, 600-mW power dissipation, and 33 sq mm chip size has been developed. Excellent speed-power performance with high packing density has been achieved by an oxide isolation technology in conjunction with novel ECL circuit techniques and IIL flip-flop memory cells, 980 sq microns (35 x 28 microns) in cell size. Development results have shown that IIL flip-flop memory cell is a trump card for assuring achievement of a high-performance large-capacity bipolar RAM, in the above 16K-bit/chip area.

Too big or too narrow? Disturbance characteristics determine the functional resilience in virtual microbial ecosystems

NASA Astrophysics Data System (ADS)

König, Sara; Firle, Anouk-Letizia; Koehnke, Merlin; Banitz, Thomas; Frank, Karin

2017-04-01

In general ecology, there is an ongoing debate about the influence of fragmentation on extinction thresholds. Whether this influence is positive or negative depends on the considered type of fragmentation: whereas habitat fragmentation often has a negative influence on population extinction thresholds, spatially fragmented disturbances are observed to have mostly positive effects on the extinction probability. Besides preventing population extinction, in soil systems ecology we are interested in analyzing how ecosystem functions are maintained despite disturbance events. Here, we analyzed the influence of disturbance size and fragmentation on the functional resilience of a microbial soil ecosystem. As soil is a highly heterogeneous environment exposed to disturbances of different spatial configurations, the identification of critical disturbance characteristics for maintaining its functions is crucial. We used the numerical simulation model eColony considering bacterial growth, degradation and dispersal for analyzing the dynamic response of biodegradation examplary for an important microbial ecosystem service to disturbance events of different spatial configurations. We systematically varied the size and the degree of fragmentation of the affected area (disturbance pattern). We found that the influence of the disturbance size on functional recovery and biodegradation performance highly depends on the spatial fragmentation of the disturbance. Generally, biodegradation performance decreases with increasing clumpedness and increasing size of the affected area. After spatially correlated disturbance events, biodegradation performance decreases linear with increasing disturbance size. After spatially fragmented disturbance events, on the other hand, an increase in disturbance size has no influence on the biodegradation performance until a critical disturbance size is reached. Is the affected area bigger than this critical size, the functional performance decreases dramatically. Under recurrent disturbance events, this threshold is shifted to lower disturbance sizes. The more frequent disturbances are recurring, the lower is the critical disturbance size. Our simulation results indicate the importance of spatial characteristics of disturbance events for the functional resilience of microbial ecosystems. Critical values for disturbance size and fragmentation emerge from an interplay between both characteristics. In consequence, a precise definition of the specific disturbance regime is necessary for analysing functional resilience. With this study, we show that we need to consider the influence of fragmentation in terrestrial environments not only on population extincions but also on the resilience of ecosystem functions. Moreover, spatial disturbance characteristics - which are widely discussed on landscape scale - are an important factor on smaller scales, too.

The use of synthetic blended fibers to reduce cracking risk in high performance concrete.

DOT National Transportation Integrated Search

2014-09-01

The aim of this project was to investigate a relatively new technique to control early-age cracking; the : use of blended size polypropylene fibers in high performance concrete mixtures. The key findings : from this work were that the use of drying s...

An insight into the influence of crystallite size on the performances of microsized spherical Li(Ni0.5Co0.2Mn0.3)O2 cathode material composed of aggregated nanosized particles

NASA Astrophysics Data System (ADS)

Fan, Guangxin; Wen, Yin; Liu, Baozhong; Yang, Wenpeng

2018-02-01

Relationships between the performance and the crystallite size of the microsized spherical Li(Ni0.5Co0.2Mn0.3)O2 cathode material composed of aggregated nanosized primary particles have been comprehensively studied. The cathode material was synthesized by a high-temperature solid-state method. The results obtained by XRD, Rietveld refinement, SEM, HR-TEM, DSC, and galvanostatic test show that the crystallite size (XS) of Li(Ni0.5Co0.2Mn0.3)O2 is greatly affected by the temperature in the range of 750 to 820 °C. Most of all, the crystallite size plays a unique role in the performance of the material. That is, the electrochemical characteristics of Li(Ni0.5Co0.2Mn0.3)O2, such as discharge capacity, rate performance, and thermal stability, are closely related to the crystallite size. Furthermore, the retention of discharge capacity is determined by that of crystallite size in Li(Ni0.5Co0.2Mn0.3)O2 after 100 cycles.

Grain-Size-Dependent Thermoelectric Properties of SrTiO3 3D Superlattice Ceramics

NASA Astrophysics Data System (ADS)

Zhang, Rui-zhi; Koumoto, Kunihito

2013-07-01

The thermoelectric (TE) performance of SrTiO3 (STO) 3D superlattice ceramics with 2D electron gas grain boundaries (GBs) was theoretically investigated. The grain size dependence of the power factor, lattice thermal conductivity, and ZT value were calculated by using Boltzmann transport equations. It was found that nanostructured STO ceramics with smaller grain size have larger ZT value. This is because the quantum confinement effect, energy filtering effect, and interfacial phonon scattering at GBs all become stronger with decreasing grain size, resulting in higher power factor and lower lattice thermal conductivity. These findings will aid the design of nanostructured oxide ceramics with high TE performance.

Ultra-compact high-performance MCT MWIR engine

NASA Astrophysics Data System (ADS)

Lutz, H.; Breiter, R.; Eich, D.; Figgemeier, H.; Oelmaier, R.; Rutzinger, S.; Schenk, H.; Wendler, J.

2017-02-01

Size, weight and power (SWaP) reduction is highly desired by applications such as sights for the dismounted soldier or small gimbals for UAVs. But why have high performance and small size of IR systems inevitably exclude each other? Namely, recent development progress in the fields of miniature cryocoolers, short dewars and high operating temperature (HOT) FPAs combined with pitch size reduction opens the door for very compact MWIR-modules while keeping high electro-optical performance. Now, AIM has realized first prototypes of an ultra-compact high-performance MWIR engine in a total volume of only 18cl (60mm length x 60mm height x 50mm width). Impressive SWaP characteristics are completed by a total weight below 400g and a power consumption < 4W in basic imaging mode. The engine consists of a XGA-format (1024x768) MCT detector array with 10μm pitch and a low power consuming ROIC. It is cooled down to a typical operating temperature of 160K by the miniature linear cryocooler SX020. The dewar uses a short coldfinger and is designed to reduce the heat load as much as possible. The cooler drive electronics is implemented in the CCE layout in order to reduce the required space of the printed boards and to save power. Uncorrected 14bit video data is provided via Camera Link. Optionally, a small image processing board can be stacked on top of the CCE to gain access to basic functions such as BPR, 2- point NUC and dynamic reduction. This paper will present the design, functionalities and performance data of the ultra-compact MCT MWIR engine operated at HOT.

Interface-designed Membranes with Shape-controlled Patterns for High-performance Polymer Electrolyte Membrane Fuel Cells

NASA Astrophysics Data System (ADS)

Jeon, Yukwon; Kim, Dong Jun; Koh, Jong Kwan; Ji, Yunseong; Kim, Jong Hak; Shul, Yong-Gun

2015-11-01

Polymer electrolyte membrane fuel cell is a promising zero-emission power generator for stationary/automotive applications. However, key issues, such as performance and costs, are still remained for an economical commercialization. Here, we fabricated a high-performance membrane electrode assembly (MEA) using an interfacial design based on well-arrayed micro-patterned membranes including circles, squares and hexagons with different sizes, which are produced by a facile elastomeric mold method. The best MEA performance is achieved using patterned Nafion membrane with a circle 2 μm in size, which exhibited a very high power density of 1906 mW/cm2 at 75 °C and Pt loading of 0.4 mg/cm2 with 73% improvement compared to the commercial membrane. The improved performance are attributed to the decreased MEA resistances and increased surface area for higher Pt utilization of over 80%. From these enhanced properties, it is possible to operate at lower Pt loading of 0.2 mg/cm2 with an outstanding performance of 1555 mW/cm2 and even at air/low humidity operations.

Creating Cost-Effective DNA Size Standards for Use in Teaching and Research Laboratories

ERIC Educational Resources Information Center

Shultz, Jeff

2011-01-01

I have devised a method with which a molecular size standard can be readily manufactured using Lambda DNA and PCR. This method allows the production of specific sized DNA fragments and is easily performed in a standard molecular biology laboratory. The material required to create these markers can also be used to provide a highly robust and…

Interference and problem size effect in multiplication fact solving: Individual differences in brain activations and arithmetic performance.

PubMed

De Visscher, Alice; Vogel, Stephan E; Reishofer, Gernot; Hassler, Eva; Koschutnig, Karl; De Smedt, Bert; Grabner, Roland H

2018-05-15

In the development of math ability, a large variability of performance in solving simple arithmetic problems is observed and has not found a compelling explanation yet. One robust effect in simple multiplication facts is the problem size effect, indicating better performance for small problems compared to large ones. Recently, behavioral studies brought to light another effect in multiplication facts, the interference effect. That is, high interfering problems (receiving more proactive interference from previously learned problems) are more difficult to retrieve than low interfering problems (in terms of physical feature overlap, namely the digits, De Visscher and Noël, 2014). At the behavioral level, the sensitivity to the interference effect is shown to explain individual differences in the performance of solving multiplications in children as well as in adults. The aim of the present study was to investigate the individual differences in multiplication ability in relation to the neural interference effect and the neural problem size effect. To that end, we used a paradigm developed by De Visscher, Berens, et al. (2015) that contrasts the interference effect and the problem size effect in a multiplication verification task, during functional magnetic resonance imaging (fMRI) acquisition. Forty-two healthy adults, who showed high variability in an arithmetic fluency test, participated in our fMRI study. In order to control for the general reasoning level, the IQ was taken into account in the individual differences analyses. Our findings revealed a neural interference effect linked to individual differences in multiplication in the left inferior frontal gyrus, while controlling for the IQ. This interference effect in the left inferior frontal gyrus showed a negative relation with individual differences in arithmetic fluency, indicating a higher interference effect for low performers compared to high performers. This region is suggested in the literature to be involved in resolution of proactive interference. Besides, no correlation between the neural problem size effect and multiplication performance was found. This study supports the idea that the interference due to similarities/overlap of physical traits (the digits) is crucial in memorizing arithmetic facts and in determining individual differences in arithmetic. Copyright © 2018 Elsevier Inc. All rights reserved.

Ultra high-performance liquid chromatography of porphyrins in clinical materials: column and mobile phase selection and optimisation.

PubMed

Benton, Christopher M; Lim, Chang Kee; Moniz, Caje; Jones, Donald J L

2012-06-01

Ultra high-performance liquid chromatographic (UHPLC) systems on columns packed with materials ranging from 1.9 to 2.7 µm average particle size were assessed for the fast and sensitive analysis of porphyrins in clinical materials. The fastest separation was achieved on an Agilent Poroshell C(18) column (2.7 µm particle size, 50 × 4.6 mm i.d.), followed by a Thermo Hypersil Gold C(18) column (1.9 µm particle size, 50 × 2.1 mm i.d.) and the Thermo Hypersil BDS C(18) column (2.4 µm particle size, 100 × 2.1 mm i.d.). All columns required a mobile phase containing 1 m ammonium acetate buffer, pH 5.16, with a mixture of acetonitrile and methanol as the organic modifiers for optimum resolution of the type I and III isomers, particularly for uroporphyrin I and III isomers. All UHPLC columns were suitable and superior to conventional HPLC columns packed with 5 µm average particle size materials for clinical sample analysis. Copyright © 2011 John Wiley & Sons, Ltd.

Preliminary structural sizing of a Mach 3.0 high-speed civil transport model

NASA Technical Reports Server (NTRS)

Blackburn, Charles L.

1992-01-01

An analysis has been performed pertaining to the structural resizing of a candidate Mach 3.0 High Speed Civil Transport (HSCT) conceptual design using a computer program called EZDESIT. EZDESIT is a computer program which integrates the PATRAN finite element modeling program to the COMET finite element analysis program for the purpose of calculating element sizes or cross sectional dimensions. The purpose of the present report is to document the procedure used in accomplishing the preliminary structural sizing and to present the corresponding results.

Performance of external and internal coil configurations for prostate investigations at 7 Tesla

PubMed Central

Metzger, Gregory J.; van de Moortele, Pierre-Francois; Akgun, Can; Snyder, Carl J.; Moeller, Steen; Strupp, John; Andersen, Peter; Shrivastava, Devashish; Vaughan, Tommy; Ugurbil, Kamil; Adriany, Gregor

2010-01-01

Three different coil configurations were evaluated through simulation and experimentally to determine safe operating limits and evaluate subject size dependent performance for prostate imaging at 7 Tesla. The coils included a transceiver endorectal coil (trERC), a 16 channel transceiver external surface array (trESA) and a trESA combined with a receive-only ERC (trESA+roERC). While the transmit B1 (B1+) homogeneity was far superior for the trESA, the maximum achievable B1+ is subject size dependent and limited by transmit chain losses and amplifier performance. For the trERC, limitations in transmit homogeneity greatly compromised image quality and limited coverage of the prostate. Despite these challenges, the high peak B1+ close to the trERC and subject size independent performance provides potential advantages especially for spectroscopic localization where high bandwidth RF pulses are required. On the receive side, the combined trESA+roERC provided the highest SNR and improved homogeneity over the trERC resulting in better visualization of the prostate and surrounding anatomy. In addition, the parallel imaging performance of the trESA+roERC holds strong promise for diffusion weighted imaging and dynamic contrast enhanced MRI. PMID:20740657

Metal-Organic Framework-Derived Hollow Hierarchical Co3O4 Nanocages with Tunable Size and Morphology: Ultrasensitive and Highly Selective Detection of Methylbenzenes.

PubMed

Jo, Young-Moo; Kim, Tae-Hyung; Lee, Chul-Soon; Lim, Kyeorei; Na, Chan Woong; Abdel-Hady, Faissal; Wazzan, Abdulaziz A; Lee, Jong-Heun

2018-03-14

Nearly monodisperse hollow hierarchical Co 3 O 4 nanocages of four different sizes (∼0.3, 1.0, 2.0, and 4.0 μm) consisting of nanosheets were prepared by controlled precipitation of zeolitic imidazolate framework-67 (ZIF-67) rhombic dodecahedra, followed by solvothermal synthesis of Co 3 O 4 nanocages using ZIF-67 self-sacrificial templates, and subsequent heat treatment for the development of high-performance methylbenzene sensors. The sensor based on hollow hierarchical Co 3 O 4 nanocages with the size of ∼1.0 μm exhibited not only ultrahigh responses (resistance ratios) to 5 ppm p-xylene (78.6) and toluene (43.8) but also a remarkably high selectivity to methylbenzene over the interference of ubiquitous ethanol at 225 °C. The unprecedented and high response and selectivity to methylbenzenes are attributed to the highly gas-accessible hollow hierarchical morphology with thin shells, abundant mesopores, and high surface area per unit volume as well as the high catalytic activity of Co 3 O 4 . Moreover, the size, shell thickness, mesopores, and hollow/hierarchical morphology of the nanocages, the key parameters determining the gas response and selectivity, could be well-controlled by tuning the precipitation of ZIF-67 rhombic dodecahedra and solvothermal reaction. This method can pave a new pathway for the design of high-performance methylbenzene sensors for monitoring the quality of indoor air.

Understanding the Size-Dependent Sodium Storage Properties of Na2C6O6-Based Organic Electrodes for Sodium-Ion Batteries.

PubMed

Wang, Yaqun; Ding, Yu; Pan, Lijia; Shi, Ye; Yue, Zhuanghao; Shi, Yi; Yu, Guihua

2016-05-11

Organic electroactive materials represent a new generation of sustainable energy storage technology due to their unique features including environmental benignity, material sustainability, and highly tailorable properties. Here a carbonyl-based organic salt Na2C6O6, sodium rhodizonate (SR) dibasic, is systematically investigated for high-performance sodium-ion batteries. A combination of structural control, electrochemical analysis, and computational simulation show that rational morphological control can lead to significantly improved sodium storage performance. A facile antisolvent method was developed to synthesize microbulk, microrod, and nanorod structured SRs, which exhibit strong size-dependent sodium ion storage properties. The SR nanorod exhibited the best performance to deliver a reversible capacity of ∼190 mA h g(-1) at 0.1 C with over 90% retention after 100 cycles. At a high rate of 10 C, 50% of the capacity can be obtained due to enhanced reaction kinetics, and such high electrochemical activity maintains even at 80 °C. These results demonstrate a generic design route toward high-performance organic-based electrode materials for beyond Li-ion batteries. Using such a biomass-derived organic electrode material enables access to sustainable energy storage devices with low cost, high electrochemical performance and thermal stability.

Comparisons of auction mechanisms in a multiple unit setting: A consideration for restructuring electric power markets

NASA Astrophysics Data System (ADS)

Bernard, John Charles

The objective of this study was to compare the performance of five single sided auctions that could be used in restructured electric power markets across different market sizes in a multiple unit setting. Auction selection would profoundly influence an industry over $200 billion in size in the United States, and the consequences of implementing an inappropriate mechanism would be great. Experimental methods were selected to analyze the auctions. Two rounds of experiments were conducted, the first testing the sealed offer last accepted offer (LAO) and first rejected offer (FRO), and the clock English (ENG) and sealed offer English (SOE) in markets of sizes two and six. The FRO, SOE, and ENG used the same pricing rule. Second round testing was on the LAO, FRO, and the nonuniform price multiple unit Vickrey (MUV) in markets of sizes two, four, and six. Experiments lasted 23 and 75 periods for rounds 1 and 2 respectively. Analysis of variance and contrast analysis were used to examine the data. The four performance measures used were price, efficiency, profits per unit, and supply revelation. Five basic principles were also assessed: no sales at losses, all low cost capacity should be offered and sold, no high cost capacity should sell, and the market should clear. It was expected group size and auction type would affect performance. For all performance measures, group size was a significant variable, with smaller groups showing poorer performance. Auction type was significant only for the efficiency performance measure, where clock auctions outperformed the others. Clock auctions also proved superior for the first four principles. The FRO performed poorly in almost all situations, and should not be a preferred mechanism in any market. The ENG was highly efficient, but expensive for the buyer. The SOE appeared superior to the FRO and ENG. The clock improves efficiency over the FRO while less information kept prices under the ENG. The MUV was superior in revealing costs, but performed less well in other categories. While concerns existed for all the mechanisms investigated, the commonly proposed LAO was the best option for restructured electric power markets.

Selection on male size, leg length and condition during mate search in a sexually highly dimorphic orb-weaving spider.

PubMed

Foellmer, Matthias W; Fairbairn, Daphne J

2005-02-01

Mate search plays a central role in hypotheses for the adaptive significance of extreme female-biased sexual size dimorphism (SSD) in animals. Spiders (Araneae) are the only free-living terrestrial taxon where extreme SSD is common. The "gravity hypothesis" states that small body size in males is favoured during mate search in species where males have to climb to reach females, because body length is inversely proportional to achievable speed on vertical structures. However, locomotive performance of males may also depend on relative leg length. Here we examine selection on male body size and leg length during mate search in the highly dimorphic orb-weaving spider Argiope aurantia, using a multivariate approach to distinguish selection targeted at different components of size. Further, we investigate the scaling relationships between male size and energy reserves, and the differential loss of reserves. Adult males do not feed while roving, and a size-dependent differential energy storage capacity may thus affect male performance during mate search. Contrary to predictions, large body size was favoured in one of two populations, and this was due to selection for longer legs. Male size was not under selection in the second population, but we detected direct selection for longer third legs. Males lost energy reserves during mate search, but this was independent of male size and storage capacity scaled isometrically with size. Thus, mate search is unlikely to lead to selection for small male size, but the hypothesis that relatively longer legs in male spiders reflect a search-adapted morphology is supported.

The Effects of Transient Emotional State and Workload on Size Scaling in Perspective Displays

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tuan Q. Tran; Kimberly R. Raddatz

2006-10-01

Previous research has been devoted to the study of perceptual (e.g., number of depth cues) and cognitive (e.g., instructional set) factors that influence veridical size perception in perspective displays. However, considering that perspective displays have utility in high workload environments that often induce high arousal (e.g., aircraft cockpits), the present study sought to examine the effect of observers’ emotional state on the ability to perceive and judge veridical size. Within a dual-task paradigm, observers’ ability to make accurate size judgments was examined under conditions of induced emotional state (positive, negative, neutral) and high and low workload. Results showed that participantsmore » in both positive and negative induced emotional states were slower to make accurate size judgments than those not under induced emotional arousal. Results suggest that emotional state is an important factor that influences visual performance on perspective displays and is worthy of further study.« less

Does size matter - What other factors are limiting the rate performance of Na3V2(PO4)3 cathode in sodium-ion batteries

NASA Astrophysics Data System (ADS)

Jiang, Xi; Zhang, Tianran; Lee, Jim Yang

2017-12-01

Na3V2(PO4)3 (NVP) is an extensively researched cathode material for the sodium-ion batteries (NIBs). Size reduction and nanocarbon coating are often used to improve its rate performance. These are strategies that have been proven highly effective for LiFePO4 (LFP), a phosphate-based cathode material which is nowadays popular with the lithium-ion batteries. Nanocarbon coating is undoubtedly useful since NVP encounters similar external electron transport barriers as LFP. The effect of size reduction, however, remains debatable since in theory, the 3D NASICON framework of NVP is more efficient for solid state ionic diffusion than is LFP. We have undertaken the measurements of the electrochemical performance of NVP particles of different sizes, electrode compositions, active material loadings and processing conditions, for the purpose of identifying the most significant factors which determine the rate performance of NVP as a NIB cathode material.

Positive focal shift of gallium nitride high contrast grating focusing reflectors

NASA Astrophysics Data System (ADS)

He, Shumin; Wang, Zhenhai; Liu, Qifa

2016-09-01

We design a type of metasurfaces capable of serving as a visible-light focusing reflector based on gallium nitride (GaN) high contrast gratings (HCGs). The wavefront of the reflected light is precisely manipulated by spatial variation of the grating periods along the subwavelength ridge array to achieve light focusing. Different from conventional negative focal shift effect, a positive focal shift is observed in such focusing reflectors. Detailed investigations of the influence of device size on the focusing performance, especially the focal length, are preformed via a finite element method . The results show that all performance parameters are greatly affected by the reflector size. A more concentrated focal point, or a better focusing capability, can be achieved by larger size. With increasing reflector size, the achieved focal length decreases and gradually approaches to the design, thus the corresponding positive focal shift decreases. Our results are helpful for understanding the visible-light control of the planar HCG-based focusing reflectors.

Block-based scalable wavelet image codec

NASA Astrophysics Data System (ADS)

Bao, Yiliang; Kuo, C.-C. Jay

1999-10-01

This paper presents a high performance block-based wavelet image coder which is designed to be of very low implementational complexity yet with rich features. In this image coder, the Dual-Sliding Wavelet Transform (DSWT) is first applied to image data to generate wavelet coefficients in fixed-size blocks. Here, a block only consists of wavelet coefficients from a single subband. The coefficient blocks are directly coded with the Low Complexity Binary Description (LCBiD) coefficient coding algorithm. Each block is encoded using binary context-based bitplane coding. No parent-child correlation is exploited in the coding process. There is also no intermediate buffering needed in between DSWT and LCBiD. The compressed bit stream generated by the proposed coder is both SNR and resolution scalable, as well as highly resilient to transmission errors. Both DSWT and LCBiD process the data in blocks whose size is independent of the size of the original image. This gives more flexibility in the implementation. The codec has a very good coding performance even the block size is (16,16).

Studies of the Effects of Control Bandwidth and Dark-Hole Size on the HCIT Contrast Performance

NASA Technical Reports Server (NTRS)

Sidick, Erkin; Shaklan, Stuart; Balasubramanian, Kunjithapatha; Cady, Eric

2015-01-01

We have carried out both theoretical and experimental studies of the sensitivity of dark hole contrast to the control bandwidth and dark-hole dimensions in high-contrast broadband stellar coronagraphy. We have evaluated the performance of DM actuator solutions in the presence of occulting mask defects using one to five 2% -wide bands spanning a 10% bandpass. We have also investigated the dependence of the HCIT contrast performance on the size of dark -hole area including large dark holes formed at the Nyquist limit of the DM.

Studies of the effects of control bandwidth and dark-hole size on the HCIT contrast performance

NASA Astrophysics Data System (ADS)

Sidick, Erkin; Shaklan, Stuart; Balasubramanian, Kunjithapatham; Cady, Eric

2015-09-01

We have carried out both theoretical and experimental studies of the sensitivity of dark hole contrast to the control bandwidth and dark-hole dimensions in high-contrast broadband stellar coronagraphy. We have evaluated the performance of DM actuator solutions in the presence of occulting mask defects using one to five 2%-wide bands spanning a 10% bandpass. We have also investigated the dependence of the HCIT contrast performance on the size of dark-hole area including large dark holes formed at the Nyquist limit of the DM.

Expanding the Scope of High-Performance Computing Facilities

DOE Office of Scientific and Technical Information (OSTI.GOV)

Uram, Thomas D.; Papka, Michael E.

The high-performance computing centers of the future will expand their roles as service providers, and as the machines scale up, so should the sizes of the communities they serve. National facilities must cultivate their users as much as they focus on operating machines reliably. The authors present five interrelated topic areas that are essential to expanding the value provided to those performing computational science.

Size-selective separation of submicron particles in suspensions with ultrasonic atomization.

PubMed

Nii, Susumu; Oka, Naoyoshi

2014-11-01

Aqueous suspensions containing silica or polystyrene latex were ultrasonically atomized for separating particles of a specific size. With the help of a fog involving fine liquid droplets with a narrow size distribution, submicron particles in a limited size-range were successfully separated from suspensions. Performance of the separation was characterized by analyzing the size and the concentration of collected particles with a high resolution method. Irradiation of 2.4MHz ultrasound to sample suspensions allowed the separation of particles of specific size from 90 to 320nm without regarding the type of material. Addition of a small amount of nonionic surfactant, PONPE20 to SiO2 suspensions enhanced the collection of finer particles, and achieved a remarkable increase in the number of collected particles. Degassing of the sample suspension resulted in eliminating the separation performance. Dissolved air in suspensions plays an important role in this separation. Copyright © 2014 Elsevier B.V. All rights reserved.

Factors Distinguishing Exceptional Performance on the Uniform CPA Exam.

ERIC Educational Resources Information Center

Ashbaugh, Donald L.; Thompson, A. Frank

1993-01-01

Analysis of data from 234 Certified Public Accountant (CPA) candidates (98 of whom failed at least 1 part of the exam) showed that higher grades in the CPA review course correlated with passing the first time. Higher high school class rank and larger high school class size influenced exceptional test performance. (SK)

Case Study: Wallace-Rose Hill High School, Teachey, N.C.

ERIC Educational Resources Information Center

Southern Regional Education Board, Atlanta, GA.

In 1992, school leaders and teachers at Wallace-Rose High School in Teachey, North Carolina, began a multi-year whole-school improvement initiative that included the following actions: (1) identify low-performing students; (2) develop a team of faculty and administrators to work with low-performing students; (3) reduce class size for…

Knobology in use: an experimental evaluation of ergonomics recommendations.

PubMed

Overgård, Kjell Ivar; Fostervold, Knut Inge; Bjelland, Hans Vanhauwaert; Hoff, Thomas

2007-05-01

The scientific basis for ergonomics recommendations for controls has usually not been related to active goal-directed use. The present experiment tests how different knob sizes and torques affect operator performance. The task employed is to control a pointer by the use of a control knob, and is as such an experimentally defined goal-directed task relevant to machine systems in general. Duration of use, error associated with use (overshooting of the goal area) and movement reproduction were used as performance measures. Significant differences between knob sizes were found for movement reproduction. High torques led to less overshooting as opposed to low torques. The results from duration of use showed a tendency that the differences between knob sizes were reduced from the first iteration to the second iteration. The present results indicate that the ergonomically recommended ranges of knob sizes might differently affect operator performance.

A direct and fast method to monitor lipid oxidation progress in model fatty acid methyl esters by high-performance size-exclusion chromatography.

PubMed

Márquez-Ruiz, G; Holgado, F; García-Martínez, M C; Dobarganes, M C

2007-09-21

A new method based on high-performance size-exclusion chromatography (HPSEC) is proposed to quantitate primary and secondary oxidation compounds in model fatty acid methyl esters (FAMEs). The method consists on simply injecting an aliquot sample in HPSEC, without preliminary isolation procedures neither addition of standard internal. Four groups of compounds can be quantified, namely, unoxidised FAME, oxidised FAME monomers including hydroperoxides, FAME dimers and FAME polymers. Results showed high repeatability and sensitivity, and substantial advantages versus determination of residual substrate by gas-liquid chromatography. Applicability of the method is shown through selected data obtained by numerous oxidation experiments on pure FAME, mainly methyl linoleate, at ambient and moderate temperatures.

Accommodation in Astigmatic Children During Visual Task Performance

PubMed Central

Harvey, Erin M.; Miller, Joseph M.; Apple, Howard P.; Parashar, Pavan; Twelker, J. Daniel; Crescioni, Mabel; Davis, Amy L.; Leonard-Green, Tina K.; Campus, Irene; Sherrill, Duane L.

2014-01-01

Purpose. To determine the accuracy and stability of accommodation in uncorrected children during visual task performance. Methods. Subjects were second- to seventh-grade children from a highly astigmatic population. Measurements of noncycloplegic right eye spherical equivalent (Mnc) were obtained while uncorrected subjects performed three visual tasks at near (40 cm) and distance (2 m). Tasks included reading sentences with stimulus letter size near acuity threshold and an age-appropriate letter size (high task demands) and viewing a video (low task demand). Repeated measures ANOVA assessed the influence of astigmatism, task demand, and accommodative demand on accuracy (mean Mnc) and variability (mean SD of Mnc) of accommodation. Results. For near and distance analyses, respectively, sample size was 321 and 247, mean age was 10.37 (SD 1.77) and 10.30 (SD 1.74) years, mean cycloplegic M was 0.48 (SD 1.10) and 0.79 diopters (D) (SD 1.00), and mean astigmatism was 0.99 (SD 1.15) and 0.75 D (SD 0.96). Poor accommodative accuracy was associated with high astigmatism, low task demand (video viewing), and high accommodative demand. The negative effect of accommodative demand on accuracy increased with increasing astigmatism, with the poorest accommodative accuracy observed in high astigmats (≥3.00 D) with high accommodative demand/high hyperopia (1.53 D and 2.05 D of underaccommodation for near and distant stimuli, respectively). Accommodative variability was greatest in high astigmats and was uniformly high across task condition. No/low and moderate astigmats showed higher variability for the video task than the reading tasks. Conclusions. Accuracy of accommodation is reduced in uncorrected children with high astigmatism and high accommodative demand/high hyperopia, but improves with increased visual task demand (reading). High astigmats showed the greatest variability in accommodation. PMID:25103265

3D Structural Model of High-Performance Non-Fullerene Polymer Solar Cells as Revealed by High-Resolution AFM.

PubMed

Shi, Shaowei; Chen, Xiaofeng; Liu, Xubo; Wu, Xuefei; Liu, Feng; Zhang, Zhi-Guo; Li, Yongfang; Russell, Thomas P; Wang, Dong

2017-07-26

Rapid improvements in nonfullerene polymer solar cells (PSCs) have brought power conversion efficiencies to greater than 12%. To further improve device performance, a fundamental understanding of the correlations between structure and performance is essential. In this paper, based on a typical high-performance system consisting of J61(one donor-acceptor (D-A) copolymer of benzodithiophene and fluorine substituted benzotriazole) and ITIC (3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone)-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3-d:2',3'-d']-s-indaceno[1,2-b:5,6-b']-dithiophene), a 3D structural model is directly imaged by employing high-resolution atomic force microscopy (AFM). Hierarchical morphologies ranging from fiberlike crystallites, several nanometers in size, to a bicontinuous morphology, having domains tens of nanometers in size, are observed. A fibrillar interpenetrating networks of J61-rich domains embedded in a matrix comprised of a J61/ITIC is seen, reflecting the partial miscibility of J61 with ITIC. These hierarchical nanostructural characteristics are coupled to significantly enhanced exciton dissociation, and further contribute to photocurrent and final device performance.

Multilayered nano-architecture of variable sized graphene nanosheets for enhanced supercapacitor electrode performance.

PubMed

Biswas, Sanjib; Drzal, Lawrence T

2010-08-01

The diverse physical and chemical aspects of graphene nanosheets such as particle size surface area and edge chemistry were combined to fabricate a new supercapacitor electrode architecture consisting of a highly aligned network of large-sized nanosheets as a series of current collectors within a multilayer configuration of bulk electrode. Capillary driven self-assembly of monolayers of graphene nanosheets was employed to create a flexible, multilayer, free-standing film of highly hydrophobic nanosheets over large macroscopic areas. This nanoarchitecture exhibits a high-frequency capacitative response and a nearly rectangular cyclic voltammogram at 1000 mV/s scanning rate and possesses a rapid current response, small equivalent series resistance (ESR), and fast ionic diffusion for high-power electrical double-layer capacitor (EDLC) application.

Using learning automata to determine proper subset size in high-dimensional spaces

NASA Astrophysics Data System (ADS)

Seyyedi, Seyyed Hossein; Minaei-Bidgoli, Behrouz

2017-03-01

In this paper, we offer a new method called FSLA (Finding the best candidate Subset using Learning Automata), which combines the filter and wrapper approaches for feature selection in high-dimensional spaces. Considering the difficulties of dimension reduction in high-dimensional spaces, FSLA's multi-objective functionality is to determine, in an efficient manner, a feature subset that leads to an appropriate tradeoff between the learning algorithm's accuracy and efficiency. First, using an existing weighting function, the feature list is sorted and selected subsets of the list of different sizes are considered. Then, a learning automaton verifies the performance of each subset when it is used as the input space of the learning algorithm and estimates its fitness upon the algorithm's accuracy and the subset size, which determines the algorithm's efficiency. Finally, FSLA introduces the fittest subset as the best choice. We tested FSLA in the framework of text classification. The results confirm its promising performance of attaining the identified goal.

Robust gene selection methods using weighting schemes for microarray data analysis.

PubMed

Kang, Suyeon; Song, Jongwoo

2017-09-02

A common task in microarray data analysis is to identify informative genes that are differentially expressed between two different states. Owing to the high-dimensional nature of microarray data, identification of significant genes has been essential in analyzing the data. However, the performances of many gene selection techniques are highly dependent on the experimental conditions, such as the presence of measurement error or a limited number of sample replicates. We have proposed new filter-based gene selection techniques, by applying a simple modification to significance analysis of microarrays (SAM). To prove the effectiveness of the proposed method, we considered a series of synthetic datasets with different noise levels and sample sizes along with two real datasets. The following findings were made. First, our proposed methods outperform conventional methods for all simulation set-ups. In particular, our methods are much better when the given data are noisy and sample size is small. They showed relatively robust performance regardless of noise level and sample size, whereas the performance of SAM became significantly worse as the noise level became high or sample size decreased. When sufficient sample replicates were available, SAM and our methods showed similar performance. Finally, our proposed methods are competitive with traditional methods in classification tasks for microarrays. The results of simulation study and real data analysis have demonstrated that our proposed methods are effective for detecting significant genes and classification tasks, especially when the given data are noisy or have few sample replicates. By employing weighting schemes, we can obtain robust and reliable results for microarray data analysis.

Nitrogen-enriched carbon with extremely high mesoporosity and tunable mesopore size for high-performance supercapacitors

NASA Astrophysics Data System (ADS)

Yang, Xiaoqing; Li, Chengfei; Fu, Ruowen

2016-07-01

As one of the most potential electrode materials for supercapacitors, nitrogen-enriched nanocarbons are still facing challenge of constructing developed mesoporosity for rapid mass transportation and tailoring their pore size for performance optimization and expanding their application scopes. Herein we develop a series of nitrogen-enriched mesoporous carbon (NMC) with extremely high mesoporosity and tunable mesopore size by a two-step method using silica gel as template. In our approach, mesopore size can be easily tailored from 4.7 to 35 nm by increasing the HF/TEOS volume ratio from 1/100 to 1/4. The NMC with mesopores of 6.2 nm presents the largest mesopore volume, surface area and mesopore ratio of 2.56 cm3 g-1, 1003 m2 g-1 and 97.7%, respectively. As a result, the highest specific capacitance of 325 F g-1 can be obtained at the current density of 0.1 A g-1, which can stay over 88% (286 F g-1) as the current density increases by 100 times (10 A g-1). This approach may open the doors for preparation of nitrogen-enriched nanocarbons with desired nanostructure for numerous applications.

Effect of time step size and turbulence model on the open water hydrodynamic performance prediction of contra-rotating propellers

NASA Astrophysics Data System (ADS)

Wang, Zhan-zhi; Xiong, Ying

2013-04-01

A growing interest has been devoted to the contra-rotating propellers (CRPs) due to their high propulsive efficiency, torque balance, low fuel consumption, low cavitations, low noise performance and low hull vibration. Compared with the single-screw system, it is more difficult for the open water performance prediction because forward and aft propellers interact with each other and generate a more complicated flow field around the CRPs system. The current work focuses on the open water performance prediction of contra-rotating propellers by RANS and sliding mesh method considering the effect of computational time step size and turbulence model. The validation study has been performed on two sets of contra-rotating propellers developed by David W Taylor Naval Ship R & D center. Compared with the experimental data, it shows that RANS with sliding mesh method and SST k-ω turbulence model has a good precision in the open water performance prediction of contra-rotating propellers, and small time step size can improve the level of accuracy for CRPs with the same blade number of forward and aft propellers, while a relatively large time step size is a better choice for CRPs with different blade numbers.

Renewable-juglone-based high-performance sodium-ion batteries.

PubMed

Wang, Hua; Hu, Pengfei; Yang, Jie; Gong, Guangming; Guo, Lin; Chen, Xiaodong

2015-04-08

A renewable-biomolecule-based electrode is developed through a facile synchronous reduction and self-assembly process, without any binder or additional conductive agent. The hybridized electrodes can be fabricated with arbitrary size and shape and exhibit superior capacity and cycle performance. The renewable-biomaterial-based high-performance electrodes will hold a place in future energy-storage devices. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Comparison of Random Forest, k-Nearest Neighbor, and Support Vector Machine Classifiers for Land Cover Classification Using Sentinel-2 Imagery

PubMed Central

Thanh Noi, Phan; Kappas, Martin

2017-01-01

In previous classification studies, three non-parametric classifiers, Random Forest (RF), k-Nearest Neighbor (kNN), and Support Vector Machine (SVM), were reported as the foremost classifiers at producing high accuracies. However, only a few studies have compared the performances of these classifiers with different training sample sizes for the same remote sensing images, particularly the Sentinel-2 Multispectral Imager (MSI). In this study, we examined and compared the performances of the RF, kNN, and SVM classifiers for land use/cover classification using Sentinel-2 image data. An area of 30 × 30 km2 within the Red River Delta of Vietnam with six land use/cover types was classified using 14 different training sample sizes, including balanced and imbalanced, from 50 to over 1250 pixels/class. All classification results showed a high overall accuracy (OA) ranging from 90% to 95%. Among the three classifiers and 14 sub-datasets, SVM produced the highest OA with the least sensitivity to the training sample sizes, followed consecutively by RF and kNN. In relation to the sample size, all three classifiers showed a similar and high OA (over 93.85%) when the training sample size was large enough, i.e., greater than 750 pixels/class or representing an area of approximately 0.25% of the total study area. The high accuracy was achieved with both imbalanced and balanced datasets. PMID:29271909

Comparison of Random Forest, k-Nearest Neighbor, and Support Vector Machine Classifiers for Land Cover Classification Using Sentinel-2 Imagery.

PubMed

Thanh Noi, Phan; Kappas, Martin

2017-12-22

In previous classification studies, three non-parametric classifiers, Random Forest (RF), k-Nearest Neighbor (kNN), and Support Vector Machine (SVM), were reported as the foremost classifiers at producing high accuracies. However, only a few studies have compared the performances of these classifiers with different training sample sizes for the same remote sensing images, particularly the Sentinel-2 Multispectral Imager (MSI). In this study, we examined and compared the performances of the RF, kNN, and SVM classifiers for land use/cover classification using Sentinel-2 image data. An area of 30 × 30 km² within the Red River Delta of Vietnam with six land use/cover types was classified using 14 different training sample sizes, including balanced and imbalanced, from 50 to over 1250 pixels/class. All classification results showed a high overall accuracy (OA) ranging from 90% to 95%. Among the three classifiers and 14 sub-datasets, SVM produced the highest OA with the least sensitivity to the training sample sizes, followed consecutively by RF and kNN. In relation to the sample size, all three classifiers showed a similar and high OA (over 93.85%) when the training sample size was large enough, i.e., greater than 750 pixels/class or representing an area of approximately 0.25% of the total study area. The high accuracy was achieved with both imbalanced and balanced datasets.

CHARACTERIZATION OF HUMIC ACID SIZE FRACTIONS BY SEC AND MALS (R822832)

EPA Science Inventory

Latahco silt-loam humic acid was separated on a preparatory scale by size exclusion chromatography (SEC) on a gravity-fed Sepharose column. Four fractions from this separation were collected and further analyzed, along with whole humic acid, by high-performance SEC coupled with a...

Interface-designed Membranes with Shape-controlled Patterns for High-performance Polymer Electrolyte Membrane Fuel Cells

PubMed Central

Jeon, Yukwon; Kim, Dong Jun; Koh, Jong Kwan; Ji, Yunseong; Kim, Jong Hak; Shul, Yong-Gun

2015-01-01

Polymer electrolyte membrane fuel cell is a promising zero-emission power generator for stationary/automotive applications. However, key issues, such as performance and costs, are still remained for an economical commercialization. Here, we fabricated a high-performance membrane electrode assembly (MEA) using an interfacial design based on well-arrayed micro-patterned membranes including circles, squares and hexagons with different sizes, which are produced by a facile elastomeric mold method. The best MEA performance is achieved using patterned Nafion membrane with a circle 2 μm in size, which exhibited a very high power density of 1906 mW/cm2 at 75 °C and Pt loading of 0.4 mg/cm2 with 73% improvement compared to the commercial membrane. The improved performance are attributed to the decreased MEA resistances and increased surface area for higher Pt utilization of over 80%. From these enhanced properties, it is possible to operate at lower Pt loading of 0.2 mg/cm2 with an outstanding performance of 1555 mW/cm2 and even at air/low humidity operations. PMID:26552839

High performance 3D adaptive filtering for DSP based portable medical imaging systems

NASA Astrophysics Data System (ADS)

Bockenbach, Olivier; Ali, Murtaza; Wainwright, Ian; Nadeski, Mark

2015-03-01

Portable medical imaging devices have proven valuable for emergency medical services both in the field and hospital environments and are becoming more prevalent in clinical settings where the use of larger imaging machines is impractical. Despite their constraints on power, size and cost, portable imaging devices must still deliver high quality images. 3D adaptive filtering is one of the most advanced techniques aimed at noise reduction and feature enhancement, but is computationally very demanding and hence often cannot be run with sufficient performance on a portable platform. In recent years, advanced multicore digital signal processors (DSP) have been developed that attain high processing performance while maintaining low levels of power dissipation. These processors enable the implementation of complex algorithms on a portable platform. In this study, the performance of a 3D adaptive filtering algorithm on a DSP is investigated. The performance is assessed by filtering a volume of size 512x256x128 voxels sampled at a pace of 10 MVoxels/sec with an Ultrasound 3D probe. Relative performance and power is addressed between a reference PC (Quad Core CPU) and a TMS320C6678 DSP from Texas Instruments.

The evolution of vertebrate eye size across an environmental gradient: phenotype does not predict genotype in a Trinidadian killifish.

PubMed

Beston, Shannon M; Wostl, Elijah; Walsh, Matthew R

2017-08-01

Vertebrates exhibit substantial variation in eye size. Eye size correlates positively with visual capacity and behaviors that enhance fitness, such as predator avoidance. This foreshadows a connection between predation and eye size evolution. Yet, the conditions that favor evolutionary shifts in eye size, besides the well-known role for light availability, are unclear. We tested the influence of predation on the evolution of eye size in Trinidadian killifish, Rivulus hartii. Rivulus are located across a series of communities where they coexist with visually oriented piscivores ("high predation" sites), and no predators ("Rivulus-only" sites). Wild-caught Rivulus from high predation sites generally exhibited a smaller relative eye size than communities that lack predators. Yet, such differences were inconsistent across rivers. Second-generation common garden reared fish revealed repeatable decreases in eye size in Rivulus from high predation sites. We performed additional experiments that tested the importance of light and resources on eye size evolution. Sites that differ in light or resource availability did not differ in eye size. Our results argue that differences in predator-induced mortality underlie genetically-based shifts in vertebrate eye size. We discuss the drivers of eye size evolution in light of the nonparallel trends between the phenotypic and common garden results. © 2017 The Author(s). Evolution © 2017 The Society for the Study of Evolution.

Preparation of α-alumina nanoparticles with various shapes via hydrothermal phase transformation under supercritical water conditions

NASA Astrophysics Data System (ADS)

Hakuta, Y.; Nagai, N.; Suzuki, Y.-H.; Kodaira, T.; Bando, K. K.; Takashima, H.; Mizukami, F.

2013-12-01

Alumina (Al2O3) fine particles are widely used as industrial materials including fillers for metal or plastics, paints, polisher, cosmetics and electric substrates, due to its high hardness, chemical stability, and high thermal conductivity. The performance of those industrial products is closely related to the particle size or shape of the alumina particles used, and thus a new synthetic method to control size, shape, and crystal structure of the aluminum oxide is desired for the improvement of the performance. Hydrothermal phase transformation using various aluminum compounds such as oxide, hydroxide, and salt as a staring material, is known as one of the synthetic methods for producing alumina fine particles; however, the influence about the size and shape of the starting aluminum compounds has been little mentioned, although they strongly affect the size and shape of the final products. In this study, we investigated the influence of the shape, size and crystal structure of the starting aluminum compounds on those of the products, and newly succeeded in the production of rod-like α-Al2O3 nanoparticles from fibrous boehmite nanoparticles using hydrothermal phase transformation under supercritical water conditions.

Relative dosimetrical verification in high dose rate brachytherapy using two-dimensional detector array IMatriXX

PubMed Central

Manikandan, A.; Biplab, Sarkar; David, Perianayagam A.; Holla, R.; Vivek, T. R.; Sujatha, N.

2011-01-01

For high dose rate (HDR) brachytherapy, independent treatment verification is needed to ensure that the treatment is performed as per prescription. This study demonstrates dosimetric quality assurance of the HDR brachytherapy using a commercially available two-dimensional ion chamber array called IMatriXX, which has a detector separation of 0.7619 cm. The reference isodose length, step size, and source dwell positional accuracy were verified. A total of 24 dwell positions, which were verified for positional accuracy gave a total error (systematic and random) of –0.45 mm, with a standard deviation of 1.01 mm and maximum error of 1.8 mm. Using a step size of 5 mm, reference isodose length (the length of 100% isodose line) was verified for single and multiple catheters of same and different source loadings. An error ≤1 mm was measured in 57% of tests analyzed. Step size verification for 2, 3, 4, and 5 cm was performed and 70% of the step size errors were below 1 mm, with maximum of 1.2 mm. The step size ≤1 cm could not be verified by the IMatriXX as it could not resolve the peaks in dose profile. PMID:21897562

Sensitivity of storage field performance to geologic and cavern design parameters in salt domes.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ehgartner, Brian L.; Park, Byoung Yoon

2009-03-01

A sensitivity study was performed utilizing a three dimensional finite element model to assess allowable cavern field sizes for strategic petroleum reserve salt domes. A potential exists for tensile fracturing and dilatancy damage to salt that can compromise the integrity of a cavern field in situations where high extraction ratios exist. The effects of salt creep rate, depth of salt dome top, dome size, caprock thickness, elastic moduli of caprock and surrounding rock, lateral stress ratio of surrounding rock, cavern size, depth of cavern, and number of caverns are examined numerically. As a result, a correlation table between the parametersmore » and the impact on the performance of storage field was established. In general, slower salt creep rates, deeper depth of salt dome top, larger elastic moduli of caprock and surrounding rock, and a smaller radius of cavern are better for structural performance of the salt dome.« less

A meta-analysis of country differences in the high-performance work system-business performance relationship: the roles of national culture and managerial discretion.

PubMed

Rabl, Tanja; Jayasinghe, Mevan; Gerhart, Barry; Kühlmann, Torsten M

2014-11-01

Our article develops a conceptual framework based primarily on national culture perspectives but also incorporating the role of managerial discretion (cultural tightness-looseness, institutional flexibility), which is aimed at achieving a better understanding of how the effectiveness of high-performance work systems (HPWSs) may vary across countries. Based on a meta-analysis of 156 HPWS-business performance effect sizes from 35,767 firms and establishments in 29 countries, we found that the mean HPWS-business performance effect size was positive overall (corrected r = .28) and positive in each country, regardless of its national culture or degree of institutional flexibility. In the case of national culture, the HPWS-business performance relationship was, on average, actually more strongly positive in countries where the degree of a priori hypothesized consistency or fit between an HPWS and national culture (according to national culture perspectives) was lower, except in the case of tight national cultures, where greater a priori fit of an HPWS with national culture was associated with a more positive HPWS-business performance effect size. However, in loose cultures (and in cultures that were neither tight nor loose), less a priori hypothesized consistency between an HPWS and national culture was associated with higher HPWS effectiveness. As such, our findings suggest the importance of not only national culture but also managerial discretion in understanding the HPWS-business performance relationship. (PsycINFO Database Record (c) 2014 APA, all rights reserved).

Resonant mode controllers for launch vehicle applications

NASA Technical Reports Server (NTRS)

Schreiner, Ken E.; Roth, Mary Ellen

1992-01-01

Electro-mechanical actuator (EMA) systems are currently being investigated for the National Launch System (NLS) as a replacement for hydraulic actuators due to the large amount of manpower and support hardware required to maintain the hydraulic systems. EMA systems in weight sensitive applications, such as launch vehicles, have been limited to around 5 hp due to system size, controller efficiency, thermal management, and battery size. Presented here are design and test data for an EMA system that competes favorably in weight and is superior in maintainability to the hydraulic system. An EMA system uses dc power provided by a high energy density bipolar lithium thionyl chloride battery, with power conversion performed by low loss resonant topologies, and a high efficiency induction motor controlled with a high performance field oriented controller to drive a linear actuator.

Grain-size considerations for optoelectronic multistage interconnection networks.

PubMed

Krishnamoorthy, A V; Marchand, P J; Kiamilev, F E; Esener, S C

1992-09-10

This paper investigates, at the system level, the performance-cost trade-off between optical and electronic interconnects in an optoelectronic interconnection network. The specific system considered is a packet-switched, free-space optoelectronic shuffle-exchange multistage interconnection network (MIN). System bandwidth is used as the performance measure, while system area, system power, and system volume constitute the cost measures. A detailed design and analysis of a two-dimensional (2-D) optoelectronic shuffle-exchange routing network with variable grain size K is presented. The architecture permits the conventional 2 x 2 switches or grains to be generalized to larger K x K grain sizes by replacing optical interconnects with electronic wires without affecting the functionality of the system. Thus the system consists of log(k) N optoelectronic stages interconnected with free-space K-shuffles. When K = N, the MIN consists of a single electronic stage with optical input-output. The system design use an effi ient 2-D VLSI layout and a single diffractive optical element between stages to provide the 2-D K-shuffle interconnection. Results indicate that there is an optimum range of grain sizes that provides the best performance per cost. For the specific VLSI/GaAs multiple quantum well technology and system architecture considered, grain sizes larger than 256 x 256 result in a reduced performance, while grain sizes smaller than 16 x 16 have a high cost. For a network with 4096 channels, the useful range of grain sizes corresponds to approximately 250-400 electronic transistors per optical input-output channel. The effect of varying certain technology parameters such as the number of hologram phase levels, the modulator driving voltage, the minimum detectable power, and VLSI minimum feature size on the optimum grain-size system is studied. For instance, results show that using four phase levels for the interconnection hologram is a good compromise for the cost functions mentioned above. As VLSI minimum feature sizes decrease, the optimum grain size increases, whereas, if optical interconnect performance in terms of the detector power or modulator driving voltage requirements improves, the optimum grain size may be reduced. Finally, several architectural modifications to the system, such as K x K contention-free switches and sorting networks, are investigated and optimized for grain size. Results indicate that system bandwidth can be increased, but at the price of reduced performance/cost. The optoelectronic MIN architectures considered thus provide a broad range of performance/cost alternatives and offer a superior performance over purely electronic MIN's.

The Top Ten Trends.

ERIC Educational Resources Information Center

Bassi, Laurie J.; And Others

1996-01-01

Trends shaping the workplace are increased skill requirements; more educated, diverse work force; continued corporate restructuring; change in size and composition of training departments; instructional technology advances; new training delivery methods; focus on performance improvement; integrated high-performance work systems; companies becoming…

Limits to sustained energy intake. XVII. Lactation performance in MF1 mice is not programmed by fetal number during pregnancy.

PubMed

Duah, Osei A; Monney, Kweku A; Hambly, Catherine; Król, Elzbieta; Speakman, John R

2013-06-15

Several studies have suggested that lactation performance may be programmed by the number of fetuses during pregnancy, whereas other studies indicate that processes during lactation are more important. As gestation litter size and litter size in lactation are usually strongly correlated, separating the roles of pregnancy and lactation in lactation performance is difficult. To break this link, we experimentally manipulated litter size of MF1 mice to five or 16 pups per litter by cross-fostering. Litter size and mass at birth were recorded on day 1 of lactation prior to litter size manipulation. Maternal body mass and food intake, litter size and litter mass were measured daily throughout. After weaning, the potential differential utilisation of body tissues of the mothers was investigated. Relationships between maternal mass and food intake, including asymptotic daily food intake at peak lactation, offspring traits and other maternal parameters suggested that the number of fetuses the females had carried during pregnancy had no effect on lactation performance. Litter mass increases depended only on maternal food intake, which was highly variable between individuals, but was independent of fetal litter size. The sizes of key organs and tissues like the liver and alimentary tract were not related to maximal food intake at peak lactation or to fetal litter size, but the masses of the pelage, mammary glands and retroperitoneal fat pad were. These data suggest that while growth of the mammary glands and associated structures may be initiated in gestation, and vary in relation to the number of placentas, the ultimate sizes and activities of the tissues depends primarily on factors during lactation.

A Variable Step-Size Proportionate Affine Projection Algorithm for Identification of Sparse Impulse Response

NASA Astrophysics Data System (ADS)

Liu, Ligang; Fukumoto, Masahiro; Saiki, Sachio; Zhang, Shiyong

2009-12-01

Proportionate adaptive algorithms have been proposed recently to accelerate convergence for the identification of sparse impulse response. When the excitation signal is colored, especially the speech, the convergence performance of proportionate NLMS algorithms demonstrate slow convergence speed. The proportionate affine projection algorithm (PAPA) is expected to solve this problem by using more information in the input signals. However, its steady-state performance is limited by the constant step-size parameter. In this article we propose a variable step-size PAPA by canceling the a posteriori estimation error. This can result in high convergence speed using a large step size when the identification error is large, and can then considerably decrease the steady-state misalignment using a small step size after the adaptive filter has converged. Simulation results show that the proposed approach can greatly improve the steady-state misalignment without sacrificing the fast convergence of PAPA.

Effect of gold nanoparticle size and coating on labeling monocytes for CT tracking

PubMed Central

Chhour, Peter; Kim, Johoon; Benardo, Barbara; Tovar, Alfredo; Mian, Shaameen; Litt, Harold I.; Ferrari, Victor A.; Cormode, David P.

2017-01-01

With advances in cell therapies, interest in cell tracking techniques to monitor the migration, localization and viability of these cells continues to grow. X-ray computed tomography (CT) is a cornerstone of medical imaging but has been limited in cell tracking applications due to its low sensitivity towards contrast media. In this study, we investigate the role of size and surface functionality of gold nanoparticles for monocyte uptake to optimize the labeling of these cells for tracking in CT. We synthesized gold nanoparticles (AuNP) that range from 15 to 150 nm in diameter and examined several capping ligands, generating 44 distinct AuNP formulations. In vitro cytotoxicity and uptake experiments were performed with the RAW 264.7 monocyte cell line. The majority of formulations at each size were found to be biocompatible, with only certain 150 nm PEG functionalized particles reducing viability at high concentrations. High uptake of AuNP was found using small capping ligands with distal carboxylic acids (11-MUA and 16-MHA). Similar uptake values were found with intermediate sizes (50 and 75 nm) of AuNP when coated with 2000 MW poly(ethylene-glycol) carboxylic acid ligands (PCOOH). Low uptake values were observed with 15, 25, 100, and 150 nm PCOOH AuNP, revealing interplay between size and surface functionality. TEM and CT performed on cells revealed similar patterns of high gold uptake for 50 nm PCOOH and 75 nm PCOOH AuNP. These results demonstrate that highly negatively charged carboxylic acid coatings for AuNP provide the greatest internalization of AuNP in monocytes, with a complex dependency on size. PMID:28095688

User's manual for COAST 4: a code for costing and sizing tokamaks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sink, D. A.; Iwinski, E. M.

1979-09-01

The purpose of this report is to document the computer program COAST 4 for the user/analyst. COAST, COst And Size Tokamak reactors, provides complete and self-consistent size models for the engineering features of D-T burning tokamak reactors and associated facilities involving a continuum of performance including highly beam driven through ignited plasma devices. TNS (The Next Step) devices with no tritium breeding or electrical power production are handled as well as power producing and fissile producing fusion-fission hybrid reactors. The code has been normalized with a TFTR calculation which is consistent with cost, size, and performance data published in themore » conceptual design report for that device. Information on code development, computer implementation and detailed user instructions are included in the text.« less

A Simulation Study of Paced TCP

NASA Technical Reports Server (NTRS)

Kulik, Joanna; Coulter, Robert; Rockwell, Dennis; Partridge, Craig

2000-01-01

In this paper, we study the performance of paced TCP, a modified version of TCP designed especially for high delay- bandwidth networks. In typical networks, TCP optimizes its send-rate by transmitting increasingly large bursts, or windows, of packets, one burst per round-trip time, until it reaches a maximum window-size, which corresponds to the full capacity of the network. In a network with a high delay-bandwidth product, however, Transmission Control Protocol's (TCPs) maximum window-size may be larger than the queue size of the intermediate routers, and routers will begin to drop packets as soon as the windows become too large for the router queues. The TCP sender then concludes that the bottleneck capacity of the network has been reached, and it limits its send-rate accordingly. Partridge proposed paced TCP as a means of solving the problem of queueing bottlenecks. A sender using paced TCP would release packets in multiple, small bursts during a round-trip time in which ordinary TCP would release a single, large burst of packets. This approach allows the sender to increase its send-rate to the maximum window size without encountering queueing bottlenecks. This paper describes the performance of paced TCP in a simulated network and discusses implementation details that can affect the performance of paced TCP.

Formulation and process factors influencing product quality and in vitro performance of ophthalmic ointments.

PubMed

Xu, Xiaoming; Al-Ghabeish, Manar; Rahman, Ziyaur; Krishnaiah, Yellela S R; Yerlikaya, Firat; Yang, Yang; Manda, Prashanth; Hunt, Robert L; Khan, Mansoor A

2015-09-30

Owing to its unique anatomical and physiological functions, ocular surface presents special challenges for both design and performance evaluation of the ophthalmic ointment drug products formulated with a variety of bases. The current investigation was carried out to understand and identify the appropriate in vitro methods suitable for quality and performance evaluation of ophthalmic ointment, and to study the effect of formulation and process variables on its critical quality attributes (CQA). The evaluated critical formulation variables include API initial size, drug percentage, and mineral oil percentage while the critical process parameters include mixing rate, temperature, time and cooling rate. The investigated quality and performance attributes include drug assay, content uniformity, API particle size in ointment, rheological characteristics, in vitro drug release and in vitro transcorneal drug permeation. Using design of experiments (DoE) as well as a novel principle component analysis approach, five of the quality and performance attributes (API particle size, storage modulus of ointment, high shear viscosity of ointment, in vitro drug release constant and in vitro transcorneal drug permeation rate constant) were found to be highly influenced by the formulation, in particular the strength of API, and to a lesser degree by processing variables. Correlating the ocular physiology with the physicochemical characteristics of acyclovir ophthalmic ointment suggested that in vitro quality metrics could be a valuable predictor of its in vivo performance. Published by Elsevier B.V.

Performances of Different Fragment Sizes for Reduced Representation Bisulfite Sequencing in Pigs.

PubMed

Yuan, Xiao-Long; Zhang, Zhe; Pan, Rong-Yang; Gao, Ning; Deng, Xi; Li, Bin; Zhang, Hao; Sangild, Per Torp; Li, Jia-Qi

2017-01-01

Reduced representation bisulfite sequencing (RRBS) has been widely used to profile genome-scale DNA methylation in mammalian genomes. However, the applications and technical performances of RRBS with different fragment sizes have not been systematically reported in pigs, which serve as one of the important biomedical models for humans. The aims of this study were to evaluate capacities of RRBS libraries with different fragment sizes to characterize the porcine genome. We found that the Msp I-digested segments between 40 and 220 bp harbored a high distribution peak at 74 bp, which were highly overlapped with the repetitive elements and might reduce the unique mapping alignment. The RRBS library of 110-220 bp fragment size had the highest unique mapping alignment and the lowest multiple alignment. The cost-effectiveness of the 40-110 bp, 110-220 bp and 40-220 bp fragment sizes might decrease when the dataset size was more than 70, 50 and 110 million reads for these three fragment sizes, respectively. Given a 50-million dataset size, the average sequencing depth of the detected CpG sites in the 110-220 bp fragment size appeared to be deeper than in the 40-110 bp and 40-220 bp fragment sizes, and these detected CpG sties differently located in gene- and CpG island-related regions. In this study, our results demonstrated that selections of fragment sizes could affect the numbers and sequencing depth of detected CpG sites as well as the cost-efficiency. No single solution of RRBS is optimal in all circumstances for investigating genome-scale DNA methylation. This work provides the useful knowledge on designing and executing RRBS for investigating the genome-wide DNA methylation in tissues from pigs.

Design considerations for high-altitude, long-endurance, microwave-powered aircraft. M.S. Thesis - George Washington Univ., Washington, D.C.

NASA Technical Reports Server (NTRS)

Nguyen, H. Q.

1985-01-01

The sizing and performance analyses have been conducted in the design of long-endurance, high-altitude airplanes. These airplanes receive power either continuously beamed from a phased array transmitter or intermittently beamed from a dish transmitter. Results are presented for the cases of flight in zero wind speed and nonzero wind speed. Sensitivity studies indicate that the vehicle size is relatively insensitive to changes in the transmitter size. Cost estimates were made using models that excluded the airplane cost. Using a reference payload, results obtained from array and dish configurations were compared. Comparisons showed savings in cost as well as smaller vehicle sizes when an array transmitter was used.

Preparation of fluorescent mesoporous hollow silica-fullerene nanoparticles via selective etching for combined chemotherapy and photodynamic therapy

NASA Astrophysics Data System (ADS)

Yang, Yannan; Yu, Meihua; Song, Hao; Wang, Yue; Yu, Chengzhong

2015-07-01

Well-dispersed mesoporous hollow silica-fullerene nanoparticles with particle sizes of ~50 nm have been successfully prepared by incorporating fullerene molecules into the silica framework followed by a selective etching method. The fabricated fluorescent silica-fullerene composite with high porosity demonstrates excellent performance in combined chemo/photodynamic therapy.Well-dispersed mesoporous hollow silica-fullerene nanoparticles with particle sizes of ~50 nm have been successfully prepared by incorporating fullerene molecules into the silica framework followed by a selective etching method. The fabricated fluorescent silica-fullerene composite with high porosity demonstrates excellent performance in combined chemo/photodynamic therapy. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr02769a

Monodispersed ZIF-8 particles with enhanced performance for CO2 adsorption and heterogeneous catalysis

NASA Astrophysics Data System (ADS)

Guan, Yebin; Shi, Juanjuan; Xia, Ming; Zhang, Jun; Pang, Zhenfeng; Marchetti, Alessandro; Wang, Xiaohong; Cai, Jingsong; Kong, Xueqian

2017-11-01

Monodispersed zeolitic imidazolate frameworks (ZIFs) were prepared with a simple method using dimethylsulfoxide (DMSO) as solvent. This method yields ZIF-8 nanoparticles with a narrow particle size distribution of 90-110 nm and the dispersion is highly stable against agglomeration. These particles have larger nanosized porosity and enhanced CO2 adsorption capability compared to ZIF-8 prepared with different solvents such as methanol or N, N-dimethyl formamide. Their uniform size and surface chemistry also lead to superior performance in the Knoevenagel condensation reactions. The ZIF-8 nanoparticles possess high thermal stability up to 550 °C and the preparation steps are easy for scaling up which are favorable for industrial applications.

Tailored interphase structure for improved strength and energy absorption of composites

NASA Astrophysics Data System (ADS)

Gao, Xiao

Fiber reinforced polymeric composites are lightweight, high-strength and high impact-resistant materials used widely for various applications. It has been shown that the mechanical performance of composites are dependent on the interphase, a three-dimensional region of nanometer size in the vicinity of the fiber-matrix boundary that possesses properties different from those of either the fiber reinforcement or the matrix resin and governs the load transfer from matrix to fiber. This research conducts a systematic study on glass fiber-epoxy interphase structure by tailoring adhesion between constituents and the creation of textures to control strength and energy absorption through mechanical interlocking between glass fiber and epoxy matrix. Our objective is to establish the foundation for microstructural design and optimization of the composite's structural and impact performance. Two ways of roughening the glass fiber surface have been studied to create the mechanical interlocking between fiber and resin; the first technique involves forming in-situ islands on the glass fiber surface by using silane blends of Glycidoxypropyltrimethoxy silane (GPS) and Tetraethoxy silane (TEOS); the second technique applies a silane coupling agents based sizing with the incorporation of silica nanoparticles (Ludox TMA, 22 nm) onto the fiber surface. The microdroplet test was selected to characterize the influence of adhesion and mechanical interlocking effects on interphase properties of different sizing sized glass fiber reinforced epoxy systems. A suitable data reduction scheme enables the strength and specified energy absorbed due to debonding, dynamic sliding, and quasi-static sliding to be quantified. In order to validate the effect of tailored interphase structure, which is induced by creating mechanical interlocking between fiber and resin, on macroscopic composite properties, composite panels were made from these four different sizing sized glass fibers and tested using the punch shear test. The composite panel made from the hybrid sizing sized glass fiber exhibited improved strength and energy absorption consistent with the trends in micromechanical measurements. Through all failure stages under macromechanical testing, hybrid sizing sized glass fiber/epoxyamine composite panel shows an increase in the strength and total energy absorption by 13% and 26%, respectively, compared to the compatible sizing sized baseline. Both micromechanical and macromechanical tests demonstrate the significant influence of tailoring the interphase structure on improving the impact performance of the composites. The hybrid sizing with the incorporation of nanoparticles, in particular, can greatly improve the impact resistance (i.e. energy absorption) of composites without sacrificing its structural performance (i.e. strength).

Pin-Hole Free Perovskite Film for Solar Cells Application Prepared by Controlled Two-Step Spin-Coating Method

NASA Astrophysics Data System (ADS)

Bahtiar, A.; Rahmanita, S.; Inayatie, Y. D.

2017-05-01

Morphology of perovskite film is a key important for achieving high performance perovskite solar cells. Perovskite films are commonly prepared by two-step spin-coating method. However, pin-holes are frequently formed in perovskite films due to incomplete conversion of lead-iodide (PbI2) into perovskite CH3NH3PbI3. Pin-holes in perovskite film cause large hysteresis in current-voltage curve of solar cells due to large series resistance between perovskite layer-hole transport material. Moreover, crystal structure and grain size of perovskite crystal are also other important parameters for achieving high performance solar cells, which are significantly affected by preparation of perovskite film. We studied the effect of preparation of perovskite film using controlled spin-coating parameters on crystal structure and morphological properties of perovskite film. We used two-step spin-coating method for preparation of perovskite film with varied spinning speed, spinning time and temperature of spin-coating process to control growth of perovskite crystal aimed to produce high quality perovskite crystal with pin-hole free and large grain size. All experiment was performed in air with high humidity (larger than 80%). The best crystal structure, pin-hole free with large grain crystal size of perovskite film was obtained from film prepared at room temperature with spinning speed 1000 rpm for 20 seconds and annealed at 100°C for 300 seconds.

Wide-pore silica-based ether-bonded phases for separation of proteins by high-performance hydrophobic-interaction and size-exclusion chromatography.

PubMed

Miller, N T; Feibush, B; Karger, B L

1984-12-21

This paper examines the use of wide-pore silica-based hydrophilic ether-bonded phases for the chromatographic separation of proteins under mild elution conditions. In particular, ether phases of the following structure identical to Si-(CH2)3-O-(CH2-CH2-O)n-R, where n = 1, 2, 3 and R = methyl, ethyl or n-butyl, have been prepared. These phases can be employed either in high-performance hydrophobic-interaction or size-exclusion chromatography, depending on mobile phase conditions. In the hydrophobic-interaction mode, a gradient of decreasing salt concentration, e.g., from 3 M ammonium sulfate (pH 6.0, 25 degrees C), yields sharp peaks with high mass recovery of active proteins. In this mode, retention can be controlled by salt type and concentration, as well as by column temperature. In the size-exclusion mode, use of medium ionic strength, e.g., 0.5 M ammonium acetate (pH 6.0) yields linear calibration of log (MW[eta]) vs. retention volume. Even at 0.05 M salt concentration, no stationary phase charge effects on protein elution are observed. These bonded-phase columns exhibit good column-to-column reproducibility and constant retention for at least five months of continual use. Examples of the high-performance separation of proteins in both modes are illustrated.

A comparison of machine learning methods for classification using simulation with multiple real data examples from mental health studies.

PubMed

Khondoker, Mizanur; Dobson, Richard; Skirrow, Caroline; Simmons, Andrew; Stahl, Daniel

2016-10-01

Recent literature on the comparison of machine learning methods has raised questions about the neutrality, unbiasedness and utility of many comparative studies. Reporting of results on favourable datasets and sampling error in the estimated performance measures based on single samples are thought to be the major sources of bias in such comparisons. Better performance in one or a few instances does not necessarily imply so on an average or on a population level and simulation studies may be a better alternative for objectively comparing the performances of machine learning algorithms. We compare the classification performance of a number of important and widely used machine learning algorithms, namely the Random Forests (RF), Support Vector Machines (SVM), Linear Discriminant Analysis (LDA) and k-Nearest Neighbour (kNN). Using massively parallel processing on high-performance supercomputers, we compare the generalisation errors at various combinations of levels of several factors: number of features, training sample size, biological variation, experimental variation, effect size, replication and correlation between features. For smaller number of correlated features, number of features not exceeding approximately half the sample size, LDA was found to be the method of choice in terms of average generalisation errors as well as stability (precision) of error estimates. SVM (with RBF kernel) outperforms LDA as well as RF and kNN by a clear margin as the feature set gets larger provided the sample size is not too small (at least 20). The performance of kNN also improves as the number of features grows and outplays that of LDA and RF unless the data variability is too high and/or effect sizes are too small. RF was found to outperform only kNN in some instances where the data are more variable and have smaller effect sizes, in which cases it also provide more stable error estimates than kNN and LDA. Applications to a number of real datasets supported the findings from the simulation study. © The Author(s) 2013.

Utilizing a Segmented Fuel Cell to Study the Effects of Electrode Coating Irregularities on PEM Fuel Cell Initial Performance

DOE PAGES

Phillips, Adam; Ulsh, Michael; Porter, Jason; ...

2017-04-27

An understanding of the impact of coating irregularities on beginning of life polymer electrolyte fuel cell (PEMFC) performance is essential to develop and establish manufacturing tolerances for its components. Coating irregularities occurring in the fuel cell electrode can either possess acceptable process variations or potentially harmful defects. A segmented fuel cell (SFC) is employed to understand how 100% catalyst reduction irregularities ranging from 0.125 to 1 cm 2 in the cathode electrode of a 50 cm 2 sized cell impact spatial and total cell performance at dry and wet humidification conditions. Here, by analyzing the data in a differential formatmore » the local performance effects of irregularity sizes down to 0.25 cm 2 were detected in the current distribution of the cell. Slight total cell performance impacts, due to irregularity sizes of 0.5 and 1 cm 2, were observed under dry operation and high current densities.« less

Utilizing a Segmented Fuel Cell to Study the Effects of Electrode Coating Irregularities on PEM Fuel Cell Initial Performance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Phillips, Adam; Ulsh, Michael; Porter, Jason

An understanding of the impact of coating irregularities on beginning of life polymer electrolyte fuel cell (PEMFC) performance is essential to develop and establish manufacturing tolerances for its components. Coating irregularities occurring in the fuel cell electrode can either possess acceptable process variations or potentially harmful defects. A segmented fuel cell (SFC) is employed to understand how 100% catalyst reduction irregularities ranging from 0.125 to 1 cm 2 in the cathode electrode of a 50 cm 2 sized cell impact spatial and total cell performance at dry and wet humidification conditions. Here, by analyzing the data in a differential formatmore » the local performance effects of irregularity sizes down to 0.25 cm 2 were detected in the current distribution of the cell. Slight total cell performance impacts, due to irregularity sizes of 0.5 and 1 cm 2, were observed under dry operation and high current densities.« less

Fire performance, microstructure and thermal degradation of an epoxy based nano intumescent fire retardant coating for structural applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aziz, Hammad, E-mail: engr.hammad.aziz03@gmail.com; Ahmad, Faiz, E-mail: faizahmad@petronas.com.my; Yusoff, P. S. M. Megat

Intumescent fire retardant coating (IFRC) is a passive fire protection system which swells upon heating to form expanded multi-cellular char layer that protects the substrate from fire. In this research work, IFRC’s were developed using different flame retardants such as ammonium polyphosphate, expandable graphite, melamine and boric acid. These flame retardants were bound together with the help of epoxy binder and cured together using curing agent. IFRC was then reinforced with nano magnesium oxide and nano alumina as inorganic fillers to study their effect towards fire performance, microstructure and thermal degradation. Small scale fire test was conducted to investigate themore » thermal insulation of coating whereas fire performance was calculated using thermal margin value. Field emission scanning electron microscopy was used to examine the microstructure of char obtained after fire test. Thermogravimetric analysis was conducted to investigate the residual weight of coating. Results showed that the performance of the coating was enhanced by reinforcement with nano size fillers as compared to non-filler based coating. Comparing both nano size magnesium oxide and nano size alumina; nano size alumina gave better fire performance with improved microstructure of char and high residual weight.« less

Fire performance, microstructure and thermal degradation of an epoxy based nano intumescent fire retardant coating for structural applications

NASA Astrophysics Data System (ADS)

Aziz, Hammad; Ahmad, Faiz; Yusoff, P. S. M. Megat; Zia-ul-Mustafa, M.

2015-07-01

Intumescent fire retardant coating (IFRC) is a passive fire protection system which swells upon heating to form expanded multi-cellular char layer that protects the substrate from fire. In this research work, IFRC's were developed using different flame retardants such as ammonium polyphosphate, expandable graphite, melamine and boric acid. These flame retardants were bound together with the help of epoxy binder and cured together using curing agent. IFRC was then reinforced with nano magnesium oxide and nano alumina as inorganic fillers to study their effect towards fire performance, microstructure and thermal degradation. Small scale fire test was conducted to investigate the thermal insulation of coating whereas fire performance was calculated using thermal margin value. Field emission scanning electron microscopy was used to examine the microstructure of char obtained after fire test. Thermogravimetric analysis was conducted to investigate the residual weight of coating. Results showed that the performance of the coating was enhanced by reinforcement with nano size fillers as compared to non-filler based coating. Comparing both nano size magnesium oxide and nano size alumina; nano size alumina gave better fire performance with improved microstructure of char and high residual weight.

Preparation of non-aggregating aqueous fullerenes in highly saline solutions with a biocompatible non-ionic polymer

NASA Astrophysics Data System (ADS)

Aich, Nirupam; Boateng, Linkel K.; Flora, Joseph R. V.; Saleh, Navid B.

2013-10-01

Size-tunable stable aqueous fullerenes were prepared with different concentrations of biocompatible block-copolymer pluronic (PA) F-127, ranging from 0.001% to 1% (w/v). Size uniformity increased with the increase in PA concentration, yielding optimum 58.8 ± 5.6 and 61.8 ± 5.6 nm nC60s and nC70s, respectively (0.10%w/v PA), as observed using a dynamic light scattering technique. Fullerene aqueous suspensions also manifested enhanced stability in saline solution, Dulbecco’s modified Eagle medium (DMEM), and Roswell Park Memorial Institute (RPMI) culture medium. Transmission electron microscopy was performed to elaborate on the morphology and size specificity of fullerene clusters. Physicochemical characterizations of the suspended fullerenes were performed through UV-vis spectroscopy and electrophoretic mobility measurements. PA molecules showed size restriction by encasement, as observed via molecular dynamics simulations. Such solubilization with controllable size and non-aggregating behavior can facilitate application enhancement and mechanistic environmental and toxicological studies of size-specific fullerenes.

Experimental investigation of optimum beam size for FSO uplink

NASA Astrophysics Data System (ADS)

Kaushal, Hemani; Kaddoum, Georges; Jain, Virander Kumar; Kar, Subrat

2017-10-01

In this paper, the effect of transmitter beam size on the performance of free space optical (FSO) communication has been determined experimentally. Irradiance profile for varying turbulence strength is obtained using optical turbulence generating (OTG) chamber inside laboratory environment. Based on the results, an optimum beam size is investigated using the semi-analytical method. Moreover, the combined effects of atmospheric scintillation and beam wander induced pointing errors are considered in order to determine the optimum beam size that minimizes the bit error rate (BER) of the system for a fixed transmitter power and link length. The results show that the optimum beam size for FSO uplink depends upon Fried parameter and outer scale of the turbulence. Further, it is observed that the optimum beam size increases with the increase in zenith angle but has negligible effect with the increase in fade threshold level at low turbulence levels and has a marginal effect at high turbulence levels. Finally, the obtained outcome is useful for FSO system design and BER performance analysis.

High-performance liquid chromatographic method for the determination of dansyl-polyamines

Treesearch

Subhash C. Minocha; Rakesh Minocha; Cheryl A. Robie

1990-01-01

This paper describes a fast reliable, and a sensitive technique for the separation and quantification of dansylated polyamines by high-performance liquid chromatography. Using a small 33 x 4.6 mm I.D., 3 ?m particle size, C18 reversed-phase cartridge column and a linear gradient of acetonitrile-heptanesulfonate (10 mM, pH 3.4...

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chuang, Chihpin; Singh, Dileep; Kenesei, Peter

The size and morphology of the graphite particles play a crucial role in determining various mechanical and thermal properties of cast iron. In the present study, we utilized high-energy synchrotron X-ray tomography to perform quantitative 3D-characterization of the distribution of graphite particles in high-strength compacted graphite iron (CGI). The size, shape, and spatial connectivity of graphite were examined. The analysis reveals that the compacted graphite can grow with a coral-tree-like morphology and span several hundred microns in the iron matrix.

Efficient Purification and Release of Circulating Tumor Cells by Synergistic Effect of Biomarker and SiO2 @Gel-Microbead-Based Size Difference Amplification.

PubMed

Huang, Qinqin; Cai, Bo; Chen, Bolei; Rao, Lang; He, Zhaobo; He, Rongxiang; Guo, Feng; Zhao, Libo; Kondamareddy, Kiran Kumar; Liu, Wei; Guo, Shishang; Zhao, Xing-Zhong

2016-07-01

Microfluidics-based circulating tumor cell (CTC) isolation is achieved by using gelatin-coated silica microbeads conjugated to CTC-specific antibodies. Bead-binding selectively enlarges target cell size, providing efficient high-purity capture. CTCs captured can be further released non-invasively. This stratagem enables high-performance CTC isolation for subsequent studies. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ultra-high performance size-exclusion chromatography in polar solvents.

PubMed

Vancoillie, Gertjan; Vergaelen, Maarten; Hoogenboom, Richard

2016-12-23

Size-exclusion chromatography (SEC) is amongst the most widely used polymer characterization methods in both academic and industrial polymer research allowing the determination of molecular weight and distribution parameters, i.e. the dispersity (Ɖ), of unknown polymers. The many advantages, including accuracy, reproducibility and low sample consumption, have contributed to the worldwide success of this analytical technique. The current generation of SEC systems have a stationary phase mostly containing highly porous, styrene-divinylbenzene particles allowing for a size-based separation of various polymers in solution but limiting the flow rate and solvent compatibility. Recently, sub-2μm ethylene-bridged hybrid (BEH) packing materials have become available for SEC analysis. These packing materials can not only withstand much higher pressures up to 15000psi but also show high spatial stability towards different solvents. Combining these BEH columns with the ultra-high performance LC (UHPLC) technology opens up UHP-SEC analysis, showing strongly reduced runtimes and unprecedented solvent compatibility. In this work, this novel characterization technique was compared to conventional SEC using both highly viscous and highly polar solvents as eluent, namely N,N-dimethylacetamide (DMAc), N,N-dimethylformamide (DMF) and methanol, focusing on the suitability of the BEH-columns for analysis of highly functional polymers. The results show a high functional group compatibility comparable with conventional SEC with remarkably short runtimes and enhanced resolution in methanol. Copyright © 2016 Elsevier B.V. All rights reserved.

Highly crystallized nanometer-sized zeolite a with large Cs adsorption capability for the decontamination of water.

PubMed

Torad, Nagy L; Naito, Masanobu; Tatami, Junichi; Endo, Akira; Leo, Sin-Yen; Ishihara, Shinsuke; Wu, Kevin C-W; Wakihara, Toru; Yamauchi, Yusuke

2014-03-01

Nanometer-sized zeolite A with a large cesium (Cs) uptake capability is prepared through a simple post-milling recrystallization method. This method is suitable for producing nanometer-sized zeolite in large scale, as additional organic compounds are not needed to control zeolite nucleation and crystal growth. Herein, we perform a quartz crystal microbalance (QCM) study to evaluate the uptake ability of Cs ions by zeolite, to the best of our knowledge, for the first time. In comparison to micrometer-sized zeolite A, nanometer-sized zeolite A can rapidly accommodate a larger amount of Cs ions into the zeolite crystal structure, owing to its high external surface area. Nanometer-sized zeolite is a promising candidate for the removal of radioactive Cs ions from polluted water. Our QCM study on Cs adsorption uptake behavior provides the information of adsorption kinetics (e.g., adsorption amounts and rates). This technique is applicable to other zeolites, which will be highly valuable for further consideration of radioactive Cs removal in the future. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

In situ formed Si nanoparticle network with micron-sized Si particles for lithium-ion battery anodes.

PubMed

Wu, Mingyan; Sabisch, Julian E C; Song, Xiangyun; Minor, Andrew M; Battaglia, Vincent S; Liu, Gao

2013-01-01

To address the significant challenges associated with large volume change of micrometer-sized Si particles as high-capacity anode materials for lithium-ion batteries, we demonstrated a simple but effective strategy: using Si nanoparticles as a structural and conductive additive, with micrometer-sized Si as the main lithium-ion storage material. The Si nanoparticles connected into the network structure in situ during the charge process, to provide electronic connectivity and structure stability for the electrode. The resulting electrode showed a high specific capacity of 2500 mAh/g after 30 cycles with high initial Coulombic efficiency (73%) and good rate performance during electrochemical lithiation and delithiation: between 0.01 and 1 V vs Li/Li(+).

Development and Validation of High Precision Thermal, Mechanical, and Optical Models for the Space Interferometry Mission

NASA Technical Reports Server (NTRS)

Lindensmith, Chris A.; Briggs, H. Clark; Beregovski, Yuri; Feria, V. Alfonso; Goullioud, Renaud; Gursel, Yekta; Hahn, Inseob; Kinsella, Gary; Orzewalla, Matthew; Phillips, Charles

2006-01-01

SIM Planetquest (SIM) is a large optical interferometer for making microarcsecond measurements of the positions of stars, and to detect Earth-sized planets around nearby stars. To achieve this precision, SIM requires stability of optical components to tens of picometers per hour. The combination of SIM s large size (9 meter baseline) and the high stability requirement makes it difficult and costly to measure all aspects of system performance on the ground. To reduce risks, costs and to allow for a design with fewer intermediate testing stages, the SIM project is developing an integrated thermal, mechanical and optical modeling process that will allow predictions of the system performance to be made at the required high precision. This modeling process uses commercial, off-the-shelf tools and has been validated against experimental results at the precision of the SIM performance requirements. This paper presents the description of the model development, some of the models, and their validation in the Thermo-Opto-Mechanical (TOM3) testbed which includes full scale brassboard optical components and the metrology to test them at the SIM performance requirement levels.

Improved IR detectors to swap heavy systems for SWaP

NASA Astrophysics Data System (ADS)

Manissadjian, Alain; Rubaldo, Laurent; Rebeil, Yann; Kerlain, Alexandre; Brellier, Delphine; Mollard, Laurent

2012-06-01

Cooled IR technologies are challenged for answering new system needs like the compactness and the reduction of cryopower which is a key feature for the SWaP (Size, Weight and Power) requirements. Over the last years, SOFRADIR has improved its HgCdTe technology, with effect on dark current reduction, opening the way for High Operating Temperature (HOT) systems that can get rid of the 80K temperature constraint, and therefore releases the Stirling cooler engine power consumption. Performances of the 640×512 15μm pitch LW detector working above 100K will be presented. A compact 640×512 15μm pitch MW detector presenting high EO performance above 130K with cut-off wavelength above 5.0μm has been developed. Its different performances with respect to the market requirements for SWaP will be discussed. High performance compact systems will make no compromise on detector resolution. The pixel pitch reduction is the answer for resolution enhancement with size reduction. We will therefore also discuss the ongoing developments and market needs for SWaP systems.

Dry minor mergers and size evolution of high-z compact massive early-type galaxies

NASA Astrophysics Data System (ADS)

Oogi, Taira; Habe, Asao

2012-09-01

Recent observations show evidence that high-z (z ~ 2 - 3) early-type galaxies (ETGs) are quite compact than that with comparable mass at z ~ 0. Dry merger scenario is one of the most probable one that can explain such size evolution. However, previous studies based on this scenario do not succeed to explain both properties of high-z compact massive ETGs and local ETGs, consistently. We investigate effects of sequential, multiple dry minor (stellar mass ratio M2/M1<1/4) mergers on the size evolution of compact massive ETGs. We perform N-body simulations of the sequential minor mergers with parabolic and head-on orbits, including a dark matter component and a stellar component. We show that the sequential minor mergers of compact satellite galaxies are the most efficient in the size growth and in decrease of the velocity dispersion of the compact massive ETGs. The change of stellar size and density of the merger remnant is consistent with the recent observations. Furthermore, we construct the merger histories of candidates of high-z compact massive ETGs using the Millennium Simulation Database, and estimate the size growth of the galaxies by dry minor mergers. We can reproduce the mean size growth factor between z = 2 and z = 0, assuming the most efficient size growth obtained in the case of the sequential minor mergers in our simulations.

Small gas turbine engine technology

NASA Technical Reports Server (NTRS)

Niedzwiecki, Richard W.; Meitner, Peter L.

1988-01-01

Performance of small gas turbine engines in the 250 to 1,000 horsepower size range is significantly lower than that of large engines. Engines of this size are typically used in rotorcraft, commutercraft, general aviation, and cruise missile applications. Principal reasons for the lower efficiencies of a smaller engine are well known: component efficients are lower by as much as 8 to 10 percentage points because of size effects. Small engines are designed for lower cycle pressures and temperatures because of smaller blading and cooling limitations. The highly developed analytical and manufacturing techniques evolved for large engines are not directly transferrable to small engines. Thus, it was recognized that a focused effort addressing technologies for small engies was needed and could significantly impact their performance. Recently, in-house and contract studies were undertaken at the NASA Lewis Research Center to identify advanced engine cycle and component requirements for substantial performance improvement of small gas turbines for projected year 2000 applications. The results of both in-house research and contract studies are presented. In summary, projected fuel savings of 22 to 42 percent could be obtained. Accompanying direct operating cost reductions of 11 to 17 percent, depending on fuel cost, were also estimated. High payoff technologies are identified for all engine applications, and recent results of experimental research to evolve the high payoff technologies are described.

Facile synthesis of perfect ZnSn(OH)6 octahedral microcrystallines with controlled size and high sensing performance towards ethanol

NASA Astrophysics Data System (ADS)

Shu, Shaoming; Wang, Chao; Liu, Shantang

2018-05-01

Uniform and monodisperse ZnSn(OH)6 perfect octahedrons have been synthesized by a facile coprecipitation reaction process. The particle size of the asprepared ZnSn(OH)6 octahedral structure can be readily controlled by adjusting the reaction temperature (T), and the side length of ZnSn(OH)6 octahedrons was tailored from 3 μm (40°C) to 4 μm (60°C) and 5 μm (80°C). The ethanol sensing properties of ZnSn(OH)6 octahedrons were carefully investigated. The gas sensing experimental data show that the sensor based on ZnSn(OH)6 (40°C) has good selectivity, fast response/recovery time and the highest response (R a/R g = 23.8) to 200 ppm ethanol at relatively low optimum operating temperature (200°C) compared to sensors based on ZnSn(OH)6 (60°C) and ZnSn(OH)6 (80°C), which might result from different specific surface areas. The study demonstrated that perfect octahedral ZnSn(OH)6 with controlled crystalline size and desirable sensing performance can be synthesized by a simple fabrication procedure, and the octahedral ZnSn(OH)6 could be a highly promising material for high-performance sensors.

Facile synthesis of perfect ZnSn(OH)6 octahedral microcrystallines with controlled size and high sensing performance towards ethanol

NASA Astrophysics Data System (ADS)

Shu, Shaoming; Wang, Chao; Liu, Shantang

2018-06-01

Uniform and monodisperse ZnSn(OH)6 perfect octahedrons have been synthesized by a facile coprecipitation reaction process. The particle size of the as-prepared ZnSn(OH)6 octahedral structure can be readily controlled by adjusting the reaction temperature ( T), and the side length of ZnSn(OH)6 octahedrons was tailored from 3 μm (40°C) to 4 μm (60°C) and 5 μm (80°C). The ethanol sensing properties of ZnSn(OH)6 octahedrons were carefully investigated. The gas sensing experimental data show that the sensor based on ZnSn(OH)6 (40°C) has good selectivity, fast response/recovery time and the highest response ( R a/ R g = 23.8) to 200 ppm ethanol at relatively low optimum operating temperature (200°C) compared to sensors based on ZnSn(OH)6 (60°C) and ZnSn(OH)6 (80°C), which might result from different specific surface areas. The study demonstrated that perfect octahedral ZnSn(OH)6 with controlled crystalline size and desirable sensing performance can be synthesized by a simple fabrication procedure, and the octahedral ZnSn(OH)6 could be a highly promising material for high-performance sensors.

Relations between conspecific density and effects of ultraviolet-b radiation on tadpole size in the striped marsh frog.

PubMed

Mitchell, Toby; Alton, Lesley A; White, Craig R; Franklin, Craig E

2012-12-01

Global increases in ultraviolet-B radiation (UVBR) associated with stratospheric ozone depletion are potentially contributing to the decline of numerous amphibian species around the world. Exposure to UVBR alone reduces survival and induces a range of sublethal effects in embryonic and larval amphibians. When additional environmental stressors are present, UVBR can have compounding negative effects. Thus, examination of the effects of UVBR in the absence of other stressors may substantially underestimate its potential to affect amphibians in natural habitats. We examined the independent and interactive effects of increased UVBR and high conspecific density would have embryonic and larval striped marsh frogs (Limnodynastes peronii). We exposed individuals to a factorial combination of low and high UVBR levels and low, medium, and high densities of striped marsh frog tadpoles. The response variables were time to hatching, hatching success, posthatch survival, burst-swimming performance of tadpoles (maximum instantaneous swim speed following an escape response), and size and morphology of tadpoles. Consistent with results of previous studies, we found that exposure to UVBR alone increased the time to hatching of embryos and reduced the burst-swimming performance and size of tadpoles. Similarly, increasing conspecific density increased the time to hatching of embryos and reduced the size of tadpoles, but had no effect on burst-swimming performance. The negative effect of UVBR on tadpole size was not apparent at high densities of tadpoles. This result suggests that tadpoles living at higher densities may invest relatively less energy in growth and thus have more energy to repair UVBR-induced damage. Lower densities of conspecifics increased the negative effects of UVBR on developing amphibians. Thus, low-density populations, which may include declining populations, may be particularly susceptible to the detrimental effects of increased UVBR and thus may be driven toward extinction faster than might be expected on the basis of results from single-factor studies. ©2012 Society for Conservation Biology.

A study of the effect of selected material properties on the ablation performance of artificial graphite

NASA Technical Reports Server (NTRS)

Maahs, H. G.

1972-01-01

Eighteen material properties were measured on 45 different, commercially available, artificial graphites. Ablation performance of these same graphites were also measured in a Mach 2 airstream at a stagnation pressure of 5.6 atm. Correlations were developed, where possible, between pairs of the material properties. Multiple regression equations were then formulated relating ablation performance to the various material properties, thus identifying those material properties having the strongest effect on ablation performance. These regression equations reveal that ablation performance in the present test environment depends primarily on maximum grain size, density, ash content, thermal conductivity, and mean pore radius. For optimization of ablation performance, grain size should be small, ash content low, density and thermal conductivity high, and mean pore radius large.

Micro-sized microbial fuel cell: a mini-review.

PubMed

Wang, Hsiang-Yu; Bernarda, Angela; Huang, Chih-Yung; Lee, Duu-Jong; Chang, Jo-Shu

2011-01-01

This review presents the development of micro-sized microbial fuel cells (including mL-scale and μL-scale setups), with summarization of their advantageous characteristics, fabrication methods, performances, potential applications and possible future directions. The performance of microbial fuel cells (MFCs) is affected by issues such as mass transport, reaction kinetics and ohmic resistance. These factors are manipulated in micro-sized MFCs using specially allocated electrodes constructed with specified materials having physically or chemically modified surfaces. Both two-chamber and air-breathing cathodes are promising configurations for mL-scale MFCs. However, most of the existing μL-scale MFCs generate significantly lower volumetric power density compared with their mL-counterparts because of the high internal resistance. Although μL-scale MFCs have not yet to provide sufficient power for operating conventional equipment, they show great potential in rapid screening of electrochemically microbes and electrode performance. Additional possible applications and future directions are also provided for the development of micro-sized MFCs. Copyright © 2010 Elsevier Ltd. All rights reserved.

Particle size-controllable microwave-assisted solvothermal synthesis of the high-voltage cathode material LiCoPO4 using water/ethylene glycol solvent blends

NASA Astrophysics Data System (ADS)

Ludwig, Jennifer; Haering, Dominik; Doeff, Marca M.; Nilges, Tom

2017-03-01

Particle size-tuned platelets of the high-voltage cathode material LiCoPO4 for Li-ion batteries have been synthesized by a simple one-step microwave-assisted solvothermal process using an array of water/ethylene glycol (EG) solvent mixtures. Particle size control was achieved by altering the concentration of the EG co-solvent in the mixture between 0 and 100 vol%, with amounts of 0-80 vol% EG producing single phase, olivine-type LiCoPO4. The particle sizes of the olivine materials were significantly reduced from about 1.2 μm × 1.2 μm × 500 nm (0 vol% EG) to 200 nm × 100 nm × 50 nm (80 vol% EG) with increasing EG content, while specific surface areas increased from 2 to 13 m2 g-1. The particle size reduction could mainly be attributed to the modified viscosities of the solvent blends. Owing to the soft template effect of EG, the crystals exhibited the smallest dimensions along the [010] direction of the Li diffusion pathways in the olivine crystal structure, resulting in enhanced lithium diffusion properties. The relationship between the synthesis, crystal properties and electrochemical performance was further elucidated, indicating that the electrochemical performances of the as-prepared materials mainly depend on the solvent composition and the respective particle size range. LiCoPO4 products obtained from reaction media with low and high EG contents exhibited good electrochemical performances (initial discharge capacities of 87-124 mAh g-1 at 0.1 C), whereas materials made from medium EG concentrations (40-60 vol% EG) showed the highest capacities and gravimetric energy densities (up to 137 mAh g-1 and 658 Wh kg-1 at 0.1 C), excellent rate capabilities, and cycle life.

Ultrahigh-power supercapacitors based on highly conductive graphene nanosheet/nanometer-sized carbide-derived carbon frameworks.

PubMed

Yan, Pengtao; Zhang, Xuesha; Hou, Meiling; Liu, Yanyan; Liu, Ting; Liu, Kang; Zhang, Ruijun

2018-06-22

In order to develop energy storage devices with high power performance, electrodes should hold well-defined pathways for efficient ionic and electronic transport. Herein, we demonstrate a highly conductive graphene nanosheet/nanometer-sized carbide-derived carbon framework (hcGNS/nCDC). In this architecture, nCDC possesses short transport paths for electrolyte ions, thus ensuring the rapid ions transportation. The excellent electrical conductivity of hcGNS can reduce the electrode internal resistance for the supercapacitor and thus endows the hcGNS/nCDC composite electrodes with excellent electronic transportation performance. Electrochemical measurements show that the cyclic voltammogram of hcGNS/nCDC can maintain a rectangular-like shape with the increase of the scan rate from 5 mV s -1 to 20 V s -1 , and the specific capacitance retention is up to 51% even at a high scan rate of 20 V s -1 , suggesting ultrahigh power performance, which, to the best of our knowledge, is among the best power performances reported so far for the carbon materials. Furthermore, the hcGNS/nCDC composite also shows an excellent cycling stability (no drop in its capacitance occurs even after 10000 cycles). This work demonstrates the advantage in the ultrahigh power performance for the framework having both short transport pathways for electrolyte ions and high electrical conductivity.

Ultrahigh-power supercapacitors based on highly conductive graphene nanosheet/nanometer-sized carbide-derived carbon frameworks

NASA Astrophysics Data System (ADS)

Yan, Pengtao; Zhang, Xuesha; Hou, Meiling; Liu, Yanyan; Liu, Ting; Liu, Kang; Zhang, Ruijun

2018-06-01

In order to develop energy storage devices with high power performance, electrodes should hold well-defined pathways for efficient ionic and electronic transport. Herein, we demonstrate a highly conductive graphene nanosheet/nanometer-sized carbide-derived carbon framework (hcGNS/nCDC). In this architecture, nCDC possesses short transport paths for electrolyte ions, thus ensuring the rapid ions transportation. The excellent electrical conductivity of hcGNS can reduce the electrode internal resistance for the supercapacitor and thus endows the hcGNS/nCDC composite electrodes with excellent electronic transportation performance. Electrochemical measurements show that the cyclic voltammogram of hcGNS/nCDC can maintain a rectangular-like shape with the increase of the scan rate from 5 mV s‑1 to 20 V s‑1, and the specific capacitance retention is up to 51% even at a high scan rate of 20 V s‑1, suggesting ultrahigh power performance, which, to the best of our knowledge, is among the best power performances reported so far for the carbon materials. Furthermore, the hcGNS/nCDC composite also shows an excellent cycling stability (no drop in its capacitance occurs even after 10000 cycles). This work demonstrates the advantage in the ultrahigh power performance for the framework having both short transport pathways for electrolyte ions and high electrical conductivity.

Effect of group size and maize silage dietary levels on behaviour, health, carcass and meat quality of Mediterranean buffaloes.

PubMed

Masucci, F; De Rosa, G; Barone, C M A; Napolitano, F; Grasso, F; Uzun, P; Di Francia, A

2016-03-01

The effects of different dietary levels of maize silage (10% v. 36% DM) and group size (7 v. 14 animals) were assessed on growth performance and in vivo digestibility of 28 male fattening buffaloes. In addition, the effects of diet on meat quality and group size on behaviour and immune response were separately evaluated. Animals were weighed and assigned to three groups. The high silage - low size group (HL) was fed a total mixed ration (TMR) containing 36% DM of maize silage and consisted of seven animals (age 12.7±2.6 months; BW 382.2±67.7 kg at the start of the study). The low silage - low size group (LL) was fed a TMR containing 10% DM of maize silage and consisted of seven animals (age 13.0±2.7 months; BW 389.4±72.3 kg). The high silage - high size group (HH) was fed the 36% maize silage DM diet and consisted of 14 animals (age 13.9±3.25 months; BW 416.5±73.9 kg). Total space allowance (3.2 indoor+3.2 outdoor m2/animal) was kept constant in the three groups, as well as the ratio of animals to drinkers (seven animals per water bowl) and the manger space (70 cm per animal). Growth performance, carcass characteristics and digestibility were influenced neither by dietary treatment nor by group size, even if the group fed 36% maize silage diet showed a higher fibre digestibility. No effect of diet was found on meat quality. Group size did not affect the behavioural activities with the exception of drinking (1.04±0.35% v. 2.60±0.35%; P<0.01 for groups HL and HH, respectively) and vigilance (2.58±0.46% v. 1.20±0.46%; P<0.05 for groups HL and HH, respectively). Immune responses were not affected by group size.

Aerocapture Guidance and Performance at Mars for High-Mass Systems

NASA Technical Reports Server (NTRS)

Zumwalt, Carlie H.; Sostaric, Ronald r.; Westhelle, Carlos H.; Cianciolo, Alicia Dwyer

2010-01-01

The objective of this study is to understand the performance associated with using the aerocapture maneuver to slow high-mass systems from an Earth-approach trajectory into orbit around Mars. This work is done in conjunction with the Mars Entry Descent and Landing Systems Analysis (EDL-SA) task to explore candidate technologies necessary for development in order to land large-scale payloads on the surface of Mars. Among the technologies considered include hypersonic inflatable aerodynamic decelerators (HIADs) and rigid mid-lift to drag (L/D) aeroshells. Nominal aerocapture trajectories were developed for the mid-L/D aeroshell and two sizes of HIADs, and Monte Carlo analysis was completed to understand sensitivities to dispersions. Additionally, a study was completed in order to determine the size of the larger of the two HIADs which would maintain design constraints on peak heat rate and diameter. Results show that each of the three aeroshell designs studied is a viable option for landing high-mass payloads as none of the three exceed performance requirements.

Elimination of Bimodal Size in InAs/GaAs Quantum Dots for Preparation of 1.3-μm Quantum Dot Lasers

NASA Astrophysics Data System (ADS)

Su, Xiang-Bin; Ding, Ying; Ma, Ben; Zhang, Ke-Lu; Chen, Ze-Sheng; Li, Jing-Lun; Cui, Xiao-Ran; Xu, Ying-Qiang; Ni, Hai-Qiao; Niu, Zhi-Chuan

2018-02-01

The device characteristics of semiconductor quantum dot lasers have been improved with progress in active layer structures. Self-assembly formed InAs quantum dots grown on GaAs had been intensively promoted in order to achieve quantum dot lasers with superior device performances. In the process of growing high-density InAs/GaAs quantum dots, bimodal size occurs due to large mismatch and other factors. The bimodal size in the InAs/GaAs quantum dot system is eliminated by the method of high-temperature annealing and optimized the in situ annealing temperature. The annealing temperature is taken as the key optimization parameters, and the optimal annealing temperature of 680 °C was obtained. In this process, quantum dot growth temperature, InAs deposition, and arsenic (As) pressure are optimized to improve quantum dot quality and emission wavelength. A 1.3-μm high-performance F-P quantum dot laser with a threshold current density of 110 A/cm2 was demonstrated.

Supercapacitor electrode materials with hierarchically structured pores from carbonization of MWCNTs and ZIF-8 composites.

PubMed

Li, Xueqin; Hao, Changlong; Tang, Bochong; Wang, Yue; Liu, Mei; Wang, Yuanwei; Zhu, Yihua; Lu, Chenguang; Tang, Zhiyong

2017-02-09

Due to their high specific surface area and good electric conductivity, nitrogen-doped porous carbons (NPCs) and carbon nanotubes (CNTs) have attracted much attention for electrochemical energy storage applications. In the present work, we firstly prepared MWCNT/ZIF-8 composites by decoration of zeolitic imidazolate frameworks (ZIF-8) onto the surface of multi-walled CNTs (MWCNTs), then obtained MWCNT/NPCs by the direct carbonization of MWCNT/ZIF-8. By controlling the reaction conditions, MWCNT/ZIF-8 with three different particle sizes were synthesized. The effect of NPCs size on capacitance performance has been evaluated in detail. The MWCNT/NPC with large-sized NPC (MWCNT/NPC-L) displayed the highest specific capacitance of 293.4 F g -1 at the scan rate of 5 mV s -1 and only lost 4.2% of capacitance after 10 000 cyclic voltammetry cycles, which was attributed to the hierarchically structured pores, N-doping and high electrical conductivity. The studies of symmetric two-electrode supercapacitor cells also confirmed MWCNT/NPC-L as efficient electrode materials that have good electrochemical performance, especially for high-rate applications.

Elimination of Bimodal Size in InAs/GaAs Quantum Dots for Preparation of 1.3-μm Quantum Dot Lasers.

PubMed

Su, Xiang-Bin; Ding, Ying; Ma, Ben; Zhang, Ke-Lu; Chen, Ze-Sheng; Li, Jing-Lun; Cui, Xiao-Ran; Xu, Ying-Qiang; Ni, Hai-Qiao; Niu, Zhi-Chuan

2018-02-21

The device characteristics of semiconductor quantum dot lasers have been improved with progress in active layer structures. Self-assembly formed InAs quantum dots grown on GaAs had been intensively promoted in order to achieve quantum dot lasers with superior device performances. In the process of growing high-density InAs/GaAs quantum dots, bimodal size occurs due to large mismatch and other factors. The bimodal size in the InAs/GaAs quantum dot system is eliminated by the method of high-temperature annealing and optimized the in situ annealing temperature. The annealing temperature is taken as the key optimization parameters, and the optimal annealing temperature of 680 °C was obtained. In this process, quantum dot growth temperature, InAs deposition, and arsenic (As) pressure are optimized to improve quantum dot quality and emission wavelength. A 1.3-μm high-performance F-P quantum dot laser with a threshold current density of 110 A/cm 2 was demonstrated.

Micro-size spherical TiO2(B) secondary particles as anode materials for high-power and long-life lithium-ion batteries

NASA Astrophysics Data System (ADS)

Takami, Norio; Harada, Yasuhiro; Iwasaki, Takuya; Hoshina, Keigo; Yoshida, Yorikazu

2015-01-01

Electrochemical properties of micro-size spherical TiO2(B) secondary particles have been investigated in order to develop TiO2(B) anodes for lithium-ion batteries with high-power and long-life performance. The spherical TiO2(B) electrodes with a small amount of a carbon conductor additive had a high electrode density of 2.2 g cm-3 and a volumetric reversible capacity of 475 mAh cm-3 comparable to that of graphite electrodes. Compared with nano-size needle-like TiO2(B) electrodes, the spherical TiO2(B) electrodes exhibited higher-rate discharge capability and longer-cycle life performance. The impedance of the TiO2(B)/electrolyte interface model indicated that the charge transfer resistance Rc and the passivating film resistance Rf of the spherical TiO2(B) were much smaller than those of the needle-like one. The high-rate discharge and the long-cycle performance of the spherical TiO2(B) electrode are attributed to the superior electronic connective property and Rc and Rf values smaller than those of the needle-like one. Lithium-ion cells using the spherical TiO2(B) anodes and LiNi0.8Co0.1Mn0.1O2 cathode with a capacity of 2.8 Ah exhibited a high energy density of 100 Wh kg-1, a high output power density of 1800 W kg-1 for 10 s pulse, and a long cycle life of more than 3000 cycles.

Noise impact of advanced high lift systems

NASA Technical Reports Server (NTRS)

Elmer, Kevin R.; Joshi, Mahendra C.

1995-01-01

The impact of advanced high lift systems on aircraft size, performance, direct operating cost and noise were evaluated for short-to-medium and medium-to-long range aircraft with high bypass ratio and very high bypass ratio engines. The benefit of advanced high lift systems in reducing noise was found to be less than 1 effective-perceived-noise decibel level (EPNdB) when the aircraft were sized to minimize takeoff gross weight. These aircraft did, however, have smaller wings and lower engine thrusts for the same mission than aircraft with conventional high lift systems. When the advanced high lift system was implemented without reducing wing size and simultaneously using lower flap angles that provide higher L/D at approach a cumulative noise reduction of as much as 4 EPNdB was obtained. Comparison of aircraft configurations that have similar approach speeds showed cumulative noise reduction of 2.6 EPNdB that is purely the result of incorporating advanced high lift system in the aircraft design.

Si@SiOx/Graphene nanosheet anode materials for lithium-ion batteries synthesized by ball milling process

NASA Astrophysics Data System (ADS)

Tie, Xiaoyong; Han, Qianyan; Liang, Chunyan; Li, Bo; Zai, Jiantao; Qian, Xuefeng

2017-12-01

Si@SiOx/Graphene nanosheet (GNS) nanocomposites as high performance anode materials for lithium-ion batteries are synthesized by mechanically blending the mixture of expanded graphite with Si nanoparticles, and characterized by X-ray diffraction, Raman spectrum, field emission scanning electron microscopy and transmission electron microscopy. During the ball milling process, the size of Si nanoparticles will decrease, and the layer of expanded graphite can be peeled off to thin multilayers. Electrochemical performances reveal that the obtained Si@SiOx/GNS nanocomposites exhibit improved cycling stability, high reversible lithium storage capacity and superior rate capability, e.g. the discharge capacity is kept as high as 1055 mAh g-1 within 50 cycles at a current density of 200 mA g-1, retaining 63.6% of the initial value. The high performance of the obtained nanocomposites can be ascribed to GNS prepared through heat-treat and ball-milling methods, the decrease in the size of Si nanoparticles and SiOx layer on Si surface, which enhance the interactions between Si and GNS.

Hybrid approach combining multiple characterization techniques and simulations for microstructural analysis of proton exchange membrane fuel cell electrodes

NASA Astrophysics Data System (ADS)

Cetinbas, Firat C.; Ahluwalia, Rajesh K.; Kariuki, Nancy; De Andrade, Vincent; Fongalland, Dash; Smith, Linda; Sharman, Jonathan; Ferreira, Paulo; Rasouli, Somaye; Myers, Deborah J.

2017-03-01

The cost and performance of proton exchange membrane fuel cells strongly depend on the cathode electrode due to usage of expensive platinum (Pt) group metal catalyst and sluggish reaction kinetics. Development of low Pt content high performance cathodes requires comprehensive understanding of the electrode microstructure. In this study, a new approach is presented to characterize the detailed cathode electrode microstructure from nm to μm length scales by combining information from different experimental techniques. In this context, nano-scale X-ray computed tomography (nano-CT) is performed to extract the secondary pore space of the electrode. Transmission electron microscopy (TEM) is employed to determine primary C particle and Pt particle size distributions. X-ray scattering, with its ability to provide size distributions of orders of magnitude more particles than TEM, is used to confirm the TEM-determined size distributions. The number of primary pores that cannot be resolved by nano-CT is approximated using mercury intrusion porosimetry. An algorithm is developed to incorporate all these experimental data in one geometric representation. Upon validation of pore size distribution against gas adsorption and mercury intrusion porosimetry data, reconstructed ionomer size distribution is reported. In addition, transport related characteristics and effective properties are computed by performing simulations on the hybrid microstructure.

Sample size requirements for estimating effective dose from computed tomography using solid-state metal-oxide-semiconductor field-effect transistor dosimetry

PubMed Central

Trattner, Sigal; Cheng, Bin; Pieniazek, Radoslaw L.; Hoffmann, Udo; Douglas, Pamela S.; Einstein, Andrew J.

2014-01-01

Purpose: Effective dose (ED) is a widely used metric for comparing ionizing radiation burden between different imaging modalities, scanners, and scan protocols. In computed tomography (CT), ED can be estimated by performing scans on an anthropomorphic phantom in which metal-oxide-semiconductor field-effect transistor (MOSFET) solid-state dosimeters have been placed to enable organ dose measurements. Here a statistical framework is established to determine the sample size (number of scans) needed for estimating ED to a desired precision and confidence, for a particular scanner and scan protocol, subject to practical limitations. Methods: The statistical scheme involves solving equations which minimize the sample size required for estimating ED to desired precision and confidence. It is subject to a constrained variation of the estimated ED and solved using the Lagrange multiplier method. The scheme incorporates measurement variation introduced both by MOSFET calibration, and by variation in MOSFET readings between repeated CT scans. Sample size requirements are illustrated on cardiac, chest, and abdomen–pelvis CT scans performed on a 320-row scanner and chest CT performed on a 16-row scanner. Results: Sample sizes for estimating ED vary considerably between scanners and protocols. Sample size increases as the required precision or confidence is higher and also as the anticipated ED is lower. For example, for a helical chest protocol, for 95% confidence and 5% precision for the ED, 30 measurements are required on the 320-row scanner and 11 on the 16-row scanner when the anticipated ED is 4 mSv; these sample sizes are 5 and 2, respectively, when the anticipated ED is 10 mSv. Conclusions: Applying the suggested scheme, it was found that even at modest sample sizes, it is feasible to estimate ED with high precision and a high degree of confidence. As CT technology develops enabling ED to be lowered, more MOSFET measurements are needed to estimate ED with the same precision and confidence. PMID:24694150

Effect of Boundary Conditions on the Back Face Deformations of Flat UHMWPE Panels

DTIC Science & Technology

2014-12-01

Zhang [2] carried out a numerical study of the effects of clamping type and clamping pressure on the ballistic performance of woven Kevlar , and found...effects of composite size were also studied. Singletary [5] studied the effects of boundary conditions and panel sizes on V50 for Kevlar KM2 fabric. The...on the BFD in flat UHMWPE panels. UHMWPE possesses high tenacity and high strength compared to Kevlar , as a result of which it is the material of

Lab on a Chip Packing of Submicron Particles for High Performance EOF Pumping

DTIC Science & Technology

2010-08-26

and wet etching techniques, using a soda lime glass substrate coated with chromium and photoresist (Nanofilm, Westlake Village, CA). A weir structure...observed previously for these soda lime glass microchips [8]. Images of the three segments of different sized particles con- tainedwithin the packed... Silica beads High pressure Lab on a chip a b s t r a c t The packing of submicrometer sized silica beads inside a microchannel was enabled by a novel

Silicon as anode for high-energy lithium ion batteries: From molten ingot to nanoparticles

NASA Astrophysics Data System (ADS)

Leblanc, Dominic; Hovington, Pierre; Kim, Chisu; Guerfi, Abdelbast; Bélanger, Daniel; Zaghib, Karim

2015-12-01

In this work, we demonstrate that a new mechanical attrition process can be used to prepare nanosilicon powder from metallurgical grade silicon lumps. Composite Li-ion anode made from this nanometer-size powder was found to have a high reversible capacity of 2400 mAh g-1 and an improved cycling stability compared to micrometer-sized powder. It is proposed that improved battery cycling performance is ascribed to the nanoscale silicon particles which supresses the volume expansion owing to its superplasticity.

Semiquantitative analysis of gaps in microbiological performance of fish processing sector implementing current food safety management systems: a case study.

PubMed

Onjong, Hillary Adawo; Wangoh, John; Njage, Patrick Murigu Kamau

2014-08-01

Fish processing plants still face microbial food safety-related product rejections and the associated economic losses, although they implement legislation, with well-established quality assurance guidelines and standards. We assessed the microbial performance of core control and assurance activities of fish exporting processors to offer suggestions for improvement using a case study. A microbiological assessment scheme was used to systematically analyze microbial counts in six selected critical sampling locations (CSLs). Nine small-, medium- and large-sized companies implementing current food safety management systems (FSMS) were studied. Samples were collected three times on each occasion (n = 324). Microbial indicators representing food safety, plant and personnel hygiene, and overall microbiological performance were analyzed. Microbiological distribution and safety profile levels for the CSLs were calculated. Performance of core control and assurance activities of the FSMS was also diagnosed using an FSMS diagnostic instrument. Final fish products from 67% of the companies were within the legally accepted microbiological limits. Salmonella was absent in all CSLs. Hands or gloves of workers from the majority of companies were highly contaminated with Staphylococcus aureus at levels above the recommended limits. Large-sized companies performed better in Enterobacteriaceae, Escherichia coli, and S. aureus than medium- and small-sized ones in a majority of the CSLs, including receipt of raw fish material, heading and gutting, and the condition of the fish processing tables and facilities before cleaning and sanitation. Fish products of 33% (3 of 9) of the companies and handling surfaces of 22% (2 of 9) of the companies showed high variability in Enterobacteriaceae counts. High variability in total viable counts and Enterobacteriaceae was noted on fish products and handling surfaces. Specific recommendations were made in core control and assurance activities associated with sampling locations showing poor performance.

The New Century High Schools Initiative. What Works Clearinghouse Intervention Report

ERIC Educational Resources Information Center

What Works Clearinghouse, 2008

2008-01-01

The "New Century High Schools Initiative" is a program designed to improve large, under-performing high schools by transforming them into small schools with links to community organizations. "New Century High Schools" each have about 400 students; the small size is intended to foster strong relationships between students and…

Small and Medium-Sized Information Technology Firms: Assessment of Non-Local Partnership Facilitators

ERIC Educational Resources Information Center

Findikoglu, Melike Nur

2012-01-01

A two-phased qualitative study was conducted to explore the facilitators of non-local (i.e. domestic or international) partnerships formed by small- and medium-sized firms (SME). Rooted in trust, proximity and dynamic capabilities lenses, the study focused on behaviors of SMEs performing in dynamic, competitive and highly interlinked industry, the…

Postpartum Maternal Moods and Infant Size Predict Performance on a National High School Entrance Examination

ERIC Educational Resources Information Center

Galler, Janina R.; Ramsey, Frank C.; Harrison, Robert H.; Taylor, John; Cumberbatch, Glenroy; Forde, Victor

2004-01-01

Background: In an earlier series of studies, we documented the effects of feeding practices and postnatal maternal mood on the growth and development of 226 Barbadian children during the first few months of life. In this report, we extend our earlier studies by examining predictive relationships between infant size, feeding practices and…

POLYCYCLIC AROMATIC HYDROCARBON (PAH) SIZE DISTRIBUTIONS IN AEROSOLS FROM APPLIANCES OF RESIDENTIAL WOOD COMBUSTION AS DETERMINED BY DIRECT THERMAL DESORPTION - GC/MS

EPA Science Inventory

The paper describesd a direct thermal desorption (TDS) approach to determine the PAH composition (MW = 202-302 amu) in size-segregated aerosols from residential wood combustion (RWC). Six combustion tests are performed with two highly available wood fuel varieties, Douglas-fir (P...

A Performance Assessment of Eight Low-Boom High-Speed Civil Transport Concepts

NASA Technical Reports Server (NTRS)

Baize, Daniel G.; McElroy, Marcus O.; Fenbert, James A.; Coen, Peter G.; Ozoroski, Lori P.; Domack, Chris S.; Needleman, Kathy E.; Geiselhart, Karl A.

1999-01-01

A performance assessment of eight low-boom high speed civil transport (HSCT) configurations and a reference HSCT configuration has been performed. Although each of the configurations was designed with different engine concepts, for consistency, a year 2005 technology, 0.4 bypass ratio mixed-flow turbofan (MFTF) engine was used for all of the performance assessments. Therefore, all original configuration nacelles were replaced by a year 2005 MFRF nacelle design which corresponds to the engine deck utilized. The engine thrust level was optimized to minimize vehicle takeoff gross weight. To preserve the configuration's sonic-boom shaping, wing area was not optimized or altered from its original design value. Performance sizings were completed when possible for takeoff balanced field lengths of 11,000 ft and 12,000 ft, not considering FAR Part 36 Stage III noise compliance. Additionally, an arbitrary sizing with thrust-to-weight ratio equal to 0.25 was performed, enabling performance levels to be compared independent of takeoff characteristics. The low-boom configurations analyzed included designs from the Boeing Commercial Airplane Group, Douglas Aircraft Company, Ames Research Center, and Langley Research Center. This paper discusses the technology level assumptions, mission profile, analysis methodologies, and the results of the assessment. The results include maximum lift-to-drag ratios, total fuel consumption, number of passengers, optimum engine sizing plots, takeoff performance, mission block time, and takeoff gross weight for all configurations. Results from the low-boom configurations are also compared with a non-low-boom reference configuration. Configuration dependent advantages or deficiencies are discussed as warranted.

Compact fiber optic gyroscopes for platform stabilization

NASA Astrophysics Data System (ADS)

Dickson, William C.; Yee, Ting K.; Coward, James F.; McClaren, Andrew; Pechner, David A.

2013-09-01

SA Photonics has developed a family of compact Fiber Optic Gyroscopes (FOGs) for platform stabilization applications. The use of short fiber coils enables the high update rates required for stabilization applications but presents challenges to maintain high performance. We are able to match the performance of much larger FOGs by utilizing several innovative technologies. These technologies include source noise reduction to minimize Angular Random Walk (ARW), advanced digital signal processing that minimizes bias drift at high update rates, and advanced passive thermal packaging that minimizes temperature induced bias drift while not significantly affecting size, weight, or power. In addition, SA Photonics has developed unique distributed FOG packaging technologies allowing the FOG electronics and photonics to be packaged remotely from the sensor head or independent axis heads to minimize size, weight, and power at the sensing location(s). The use of these technologies has resulted in high performance, including ARW less than 0.001 deg/rt-hr and bias drift less than 0.004 deg/hr at an update rate of 10 kHz, and total packaged volume less than 30 cu. in. for a 6 degree of freedom FOG-based IMU. Specific applications include optical beam stabilization for LIDAR and LADAR, beam stabilization for long-range free-space optical communication, Optical Inertial Reference Units for HEL stabilization, and Ka band antenna pedestal pointing and stabilization. The high performance of our FOGs also enables their use in traditional navigation and positioning applications. This paper will review the technologies enabling our high-performance compact FOGs, and will provide performance test results.

Modeling ductile metals under large strain, pressure and high strain rate incorporating damage and microstructure evolution

NASA Astrophysics Data System (ADS)

Iannitti, Gianluca; Bonora, Nicola; Ruggiero, Andrew; Dichiaro, Simone

2012-03-01

In this work, a constitutive modeling that couples plasticity, grain size evolution (due to plastic deformation and dynamic recrystallization) and ductile damage has been developed. The effect of grain size on the material yield stress (Hall-Petch) and on the melting temperature has been considered. The model has been used to investigate computationally the behavior of high purity copper in dynamic tensile extrusion test (DTE). An extensive numerical simulation work, using implicit finite element code with direct integration, has been performed and the results have been compared with available experimental data. The major finding is that the proposed model is capable to predict most of the observed features such as the increase of material ductility with the decreasing average grain size, the overall number and size of fragments and the average grain size distribution in the fragment trapped into the dime.

Modeling ductile metals under large strain, pressure and high strain rates incorporating damage and microstructure evolution

NASA Astrophysics Data System (ADS)

Iannitti, Gianluca; Bonora, Nicola; Ruggiero, Andrew; Dichiaro, Simone

2011-06-01

In this work, a constitutive modeling that couples plasticity, grain size evolution (due to plastic deformation and dynamic recrystallization) and ductile damage has been developed. The effect of grain size on the material yield stress (Hall-Petch) and on the melting temperature has been considered. The model has been used to investigate computationally the behaviour of high purity copper in dynamic tensile extrusion test (DTE). An extensive numerical simulation work, using implicit finite element code with direct integration, has been performed and the results have been compared with available experimental data. The major finding is that the proposed model is capable to predict most of the observed features such as the increase of material ductility with the decreasing average grain size, the overall number and size of fragments and the average grain size distribution in the fragment trapped into the dime.

The importance of “going nano” for high power battery materials

NASA Astrophysics Data System (ADS)

Bresser, Dominic; Paillard, Elie; Copley, Mark; Bishop, Peter; Winter, Martin; Passerini, Stefano

2012-12-01

The electrochemical performance of spinel Li4Ti5O12 (LTO) nanoparticles synthesized by flame spray pyrolysis with an average diameter of approximately 20-30 nm is reported in this manuscript and compared with that of micro-sized LTO particles (1-2 μm) formed by a thermal post-treatment of the nanoparticles. The significantly advanced high rate capability of nano-sized LTO is evidenced by the results from the galvanostatic tests with applied current densities of up to 17.5 A g-1, corresponding to a full (dis-)charge of the cell within less than 40 s. For nano-sized LTO, specific capacities of 115 and 70 mAh g-1 were obtained for applied rates of 10 C and 100 C, respectively, thus confirming the essential influence of particle size of lithium titanate on its high rate capability and practical power density. Moreover, a capacity retention of around 94.8% was observed after 1000 cycles at 10 C, presenting LTO nanoparticles synthesized by FSP as highly promising anode material for high power lithium-ion battery applications.

A quantitative assessment of the Hadoop framework for analyzing massively parallel DNA sequencing data.

PubMed

Siretskiy, Alexey; Sundqvist, Tore; Voznesenskiy, Mikhail; Spjuth, Ola

2015-01-01

New high-throughput technologies, such as massively parallel sequencing, have transformed the life sciences into a data-intensive field. The most common e-infrastructure for analyzing this data consists of batch systems that are based on high-performance computing resources; however, the bioinformatics software that is built on this platform does not scale well in the general case. Recently, the Hadoop platform has emerged as an interesting option to address the challenges of increasingly large datasets with distributed storage, distributed processing, built-in data locality, fault tolerance, and an appealing programming methodology. In this work we introduce metrics and report on a quantitative comparison between Hadoop and a single node of conventional high-performance computing resources for the tasks of short read mapping and variant calling. We calculate efficiency as a function of data size and observe that the Hadoop platform is more efficient for biologically relevant data sizes in terms of computing hours for both split and un-split data files. We also quantify the advantages of the data locality provided by Hadoop for NGS problems, and show that a classical architecture with network-attached storage will not scale when computing resources increase in numbers. Measurements were performed using ten datasets of different sizes, up to 100 gigabases, using the pipeline implemented in Crossbow. To make a fair comparison, we implemented an improved preprocessor for Hadoop with better performance for splittable data files. For improved usability, we implemented a graphical user interface for Crossbow in a private cloud environment using the CloudGene platform. All of the code and data in this study are freely available as open source in public repositories. From our experiments we can conclude that the improved Hadoop pipeline scales better than the same pipeline on high-performance computing resources, we also conclude that Hadoop is an economically viable option for the common data sizes that are currently used in massively parallel sequencing. Given that datasets are expected to increase over time, Hadoop is a framework that we envision will have an increasingly important role in future biological data analysis.

Automatic rocks detection and classification on high resolution images of planetary surfaces

NASA Astrophysics Data System (ADS)

Aboudan, A.; Pacifici, A.; Murana, A.; Cannarsa, F.; Ori, G. G.; Dell'Arciprete, I.; Allemand, P.; Grandjean, P.; Portigliotti, S.; Marcer, A.; Lorenzoni, L.

2013-12-01

High-resolution images can be used to obtain rocks location and size on planetary surfaces. In particular rock size-frequency distribution is a key parameter to evaluate the surface roughness, to investigate the geologic processes that formed the surface and to assess the hazards related with spacecraft landing. The manual search for rocks on high-resolution images (even for small areas) can be a very intensive work. An automatic or semi-automatic algorithm to identify rocks is mandatory to enable further processing as determining the rocks presence, size, height (by means of shadows) and spatial distribution over an area of interest. Accurate rocks and shadows contours localization are the key steps for rock detection. An approach to contour detection based on morphological operators and statistical thresholding is presented in this work. The identified contours are then fitted using a proper geometric model of the rocks or shadows and used to estimate salient rocks parameters (position, size, area, height). The performances of this approach have been evaluated both on images of Martian analogue area of Morocco desert and on HiRISE images. Results have been compared with ground truth obtained by means of manual rock mapping and proved the effectiveness of the algorithm. The rock abundance and rocks size-frequency distribution derived on selected HiRISE images have been compared with the results of similar analyses performed for the landing site certification of Mars landers (Viking, Pathfinder, MER, MSL) and with the available thermal data from IRTM and TES.

Strengthening materials specifications

NASA Astrophysics Data System (ADS)

Sampath, K.

2005-10-01

Continuing efforts to strengthen materials specifications readily recognize that a mere compliance with a materials specification only assures a material meeting or exceeding the minimum expectations explicitly detailed in the specification. Implicitly, such efforts also recognize that additional and specific client needs must be addressed as supplementary requirements and introduced during material procurement to reduce risks and assure enhanced performance. This article describes two U.S. Navy-related case studies that allowed further strengthening of the materials specification process, using newer methods and renewed understanding. The first case demonstrates the use of a constraints-based modeling approach to specify the chemical composition of high-performance welding electrodes for critical U.S. Navy applications. This approach helps to distinguish high-performance welding electrode chemical compositions from rich and lean welding electrode chemical compositions that might limit the operational envelope, reduce performance, or both, while increasing overall cost of fabrication but otherwise meet electrode specification requirements. The second case identifies that the size of an ingot could be an important factor while specifying the aluminum and sulfur contents of very large-size, heavy-gauge plates. Renewed understanding of melt fluidity issues associated with the solidification of very large-size ingots shows that deficiencies in through-thickness ductility of heavy-gauge plates are related to controlling aluminum and sulfur contents of the voluminous melt, notwithstanding explicit compliance with specification requirements.

The effects of shift work and time of day on fine motor control during handwriting.

PubMed

Hölzle, Patricia; Hermsdörfer, Joachim; Vetter, Céline

2014-01-01

Handwriting is an elaborate and highly automatised skill relying on fine motor control. In laboratory conditions handwriting kinematics are modulated by the time of day. This study investigated handwriting kinematics in a rotational shift system and assessed whether similar time of day fluctuations at the work place can be observed. Handwriting performance was measured in two tasks of different levels of complexity in 34 shift workers across morning (6:00-14:00), evening (14:00-22:00) and night shifts (22:00-6:00). Participants were tested during all three shifts in 2-h intervals with mobile testing devices. We calculated average velocity, script size and writing frequency to quantify handwriting kinematics and fluency. Average velocity and script size were significantly affected by the shift work schedule with the worst performance during morning shifts and the best performance during evening shifts. Our data are of high economic relevance as fine motor skills are indispensable for accurate and effective production at the work place. Handwriting is one of the most complex fine motor skills in humans, which is frequently performed in daily life. In this study, we tested handwriting repeatedly at the work place in a rotational shift system. We found slower handwriting velocity and reduced script size during morning shifts.

Oxygen hypothesis of polar gigantism not supported by performance of Antarctic pycnogonids in hypoxia

PubMed Central

Woods, H. Arthur; Moran, Amy L.; Arango, Claudia P.; Mullen, Lindy; Shields, Chris

2008-01-01

Compared to temperate and tropical relatives, some high-latitude marine species are large-bodied, a phenomenon known as polar gigantism. A leading hypothesis on the physiological basis of gigantism posits that, in polar water, high oxygen availability coupled to low metabolic rates relieves constraints on oxygen transport and allows the evolution of large body size. Here, we test the oxygen hypothesis using Antarctic pycnogonids, which have been evolving in very cold conditions (−1.8–0°C) for several million years and contain spectacular examples of gigantism. Pycnogonids from 12 species, spanning three orders of magnitude in body mass, were collected from McMurdo Sound, Antarctica. Individual sea spiders were forced into activity and their performance was measured at different experimental levels of dissolved oxygen (DO). The oxygen hypothesis predicts that, all else being equal, large pycnogonids should perform disproportionately poorly in hypoxia, an outcome that would appear as a statistically significant interaction between body size and oxygen level. In fact, although we found large effects of DO on performance, and substantial interspecific variability in oxygen sensitivity, there was no evidence for size×DO interactions. These data do not support the oxygen hypothesis of Antarctic pycnogonid gigantism and suggest that explanations must be sought in other ecological or evolutionary processes. PMID:19129117

High-Temperature-Short-Time Annealing Process for High-Performance Large-Area Perovskite Solar Cells.

PubMed

Kim, Minjin; Kim, Gi-Hwan; Oh, Kyoung Suk; Jo, Yimhyun; Yoon, Hyun; Kim, Ka-Hyun; Lee, Heon; Kim, Jin Young; Kim, Dong Suk

2017-06-27

Organic-inorganic hybrid metal halide perovskite solar cells (PSCs) are attracting tremendous research interest due to their high solar-to-electric power conversion efficiency with a high possibility of cost-effective fabrication and certified power conversion efficiency now exceeding 22%. Although many effective methods for their application have been developed over the past decade, their practical transition to large-size devices has been restricted by difficulties in achieving high performance. Here we report on the development of a simple and cost-effective production method with high-temperature and short-time annealing processing to obtain uniform, smooth, and large-size grain domains of perovskite films over large areas. With high-temperature short-time annealing at 400 °C for 4 s, the perovskite film with an average domain size of 1 μm was obtained, which resulted in fast solvent evaporation. Solar cells fabricated using this processing technique had a maximum power conversion efficiency exceeding 20% over a 0.1 cm 2 active area and 18% over a 1 cm 2 active area. We believe our approach will enable the realization of highly efficient large-area PCSs for practical development with a very simple and short-time procedure. This simple method should lead the field toward the fabrication of uniform large-scale perovskite films, which are necessary for the production of high-efficiency solar cells that may also be applicable to several other material systems for more widespread practical deployment.

The Physics of Protoplanetary Dust Agglomerates. X. High-velocity Collisions between Small and Large Dust Agglomerates as a Growth Barrier

NASA Astrophysics Data System (ADS)

Schräpler, Rainer; Blum, Jürgen; Krijt, Sebastiaan; Raabe, Jan-Hendrik

2018-01-01

In a protoplanetary disk, dust aggregates in the μm to mm size range possess mean collision velocities of 10–60 m s‑1 with respect to dm- to m-sized bodies. We performed laboratory collision experiments to explore this parameter regime and found a size- and velocity-dependent threshold between erosion and growth. By using a local Monte Carlo coagulation calculation and along with a simple semi-analytical timescale approach, we show that erosion considerably limits particle growth in protoplanetary disks and leads to a steady-state dust-size distribution from μm- to dm-sized particles.

High-purity silica reflecting heat shield development

NASA Technical Reports Server (NTRS)

Congdon, W. M.

1974-01-01

A high-purity, fused-silica reflecting heat shield for the thermal protection of outer-planet probes was developed. Factors that strongly influence the performance of a silica heat shield were studied. Silica-bonded silica configurations, each prepared by a different technique, were investigated and rated according to its relative merits. Slip-casting was selected as the preferred fabrication method because it produced good reflectivity and good strength, and is relatively easy to scale up for a full-size outer-planet probe. The slips were cast using a variety of different particle sizes: continuous particle-size slips; monodisperse particle-size slips; and blends of monodisperse particle-size slips were studied. In general, smaller particles gave the highest reflectance. The monodisperse slips as well as the blend slips gave a higher reflectance than the continuous particle-size slips. An upgraded and fused natural quartz was used to study the effects of microstructure on reflectance and as the baseline to ascertain the increase in reflectance obtained from using a higher-purity synthetic material.

Systematic Evaluation of Molecular Networks for Discovery of Disease Genes.

PubMed

Huang, Justin K; Carlin, Daniel E; Yu, Michael Ku; Zhang, Wei; Kreisberg, Jason F; Tamayo, Pablo; Ideker, Trey

2018-04-25

Gene networks are rapidly growing in size and number, raising the question of which networks are most appropriate for particular applications. Here, we evaluate 21 human genome-wide interaction networks for their ability to recover 446 disease gene sets identified through literature curation, gene expression profiling, or genome-wide association studies. While all networks have some ability to recover disease genes, we observe a wide range of performance with STRING, ConsensusPathDB, and GIANT networks having the best performance overall. A general tendency is that performance scales with network size, suggesting that new interaction discovery currently outweighs the detrimental effects of false positives. Correcting for size, we find that the DIP network provides the highest efficiency (value per interaction). Based on these results, we create a parsimonious composite network with both high efficiency and performance. This work provides a benchmark for selection of molecular networks in human disease research. Copyright © 2018 Elsevier Inc. All rights reserved.

JPARSS: A Java Parallel Network Package for Grid Computing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Jie; Akers, Walter; Chen, Ying

2002-03-01

The emergence of high speed wide area networks makes grid computinga reality. However grid applications that need reliable data transfer still have difficulties to achieve optimal TCP performance due to network tuning of TCP window size to improve bandwidth and to reduce latency on a high speed wide area network. This paper presents a Java package called JPARSS (Java Parallel Secure Stream (Socket)) that divides data into partitions that are sent over several parallel Java streams simultaneously and allows Java or Web applications to achieve optimal TCP performance in a grid environment without the necessity of tuning TCP window size.more » This package enables single sign-on, certificate delegation and secure or plain-text data transfer using several security components based on X.509 certificate and SSL. Several experiments will be presented to show that using Java parallelstreams is more effective than tuning TCP window size. In addition a simple architecture using Web services« less

Performance of an electron gun for a high-brightness X-ray generator.

PubMed

Sugimura, Takashi; Ohsawa, Satoshi; Ikeda, Mitsuo

2008-05-01

A prototype thermionic electron gun for a high-brightness X-ray generator has been developed. Its extraction voltage and design current are 60 kV and 100 mA (DC), respectively. The X-ray generator aims towards a maximum brilliance of 60 kW mm(-2). The beam sizes at the rotating anticathode must therefore be within 1.0 mm x 0.1 mm and a small beam emittance is required. The fabricated electron gun optimizes an aperture grid and a Whenelt electrode. The performance of the prototype electron gun measured using pulsed-beam tests is as follows: maximum beam current, 85.7 mA; beam focus size at the rotating anticathode, 0.79 mm x 0.13 mm. In DC beam tests, FWHM beam sizes were measured to be 0.65 mm x 0.08 mm at the rotating anticathode with a beam current of 45 mA. The beam current recently reached approximately 60 mA with some thermal problems.

Meso-oblate spheroids of thermal-stabile linker-free aggregates with size-tunable subunits for reversible lithium storage.

PubMed

Deng, Da; Lee, Jim Yang

2014-01-22

The organization of nanoscale materials as building units into extended structures with specific geometry and functional properties is a challenging endeavor. Hereby, an environmentally benign, simple, and scalable method for preparation of stable, linker-free, self-supported, high-order 3D meso-oblate spheroids of CuO nanoparticle aggregates with size-tunable building nanounits for reversible lithium-ion storage is reported. In contrast to traditional spherical nanoparticle aggregation, a unique oblate spheroid morphology is achieved. The formation mechanism of the unusual oblate spheroid of aggregated nanoparticles is proposed. When tested for reversible lithium ion storage, the unique 3D meso-oblate spheroids of CuO nanoparticle aggregate demonstrated highly improved electrochemical performance (around ∼600 mAh/g over 20 cycles), which could be ascribed to the nanoporous aggregated mesostructure with abundant crystalline imperfection. Furthermore, the size of building units can be controlled (12 and 21 nm were tested) to further improve their electrochemical performance.

Effect of font size, italics, and colour count on web usability.

PubMed

Bhatia, Sanjiv K; Samal, Ashok; Rajan, Nithin; Kiviniemi, Marc T

2011-04-01

Web usability measures the ease of use of a website. This study attempts to find the effect of three factors - font size, italics, and colour count - on web usability. The study was performed using a set of tasks and developing a survey questionnaire. We performed the study using a set of human subjects, selected from the undergraduate students taking courses in psychology. The data computed from the tasks and survey questionnaire were statistically analysed to find if there was any effect of font size, italics, and colour count on the three web usability dimensions. We found that for the student population considered, there was no significant effect of font size on usability. However, the manipulation of italics and colour count did influence some aspects of usability. The subjects performed better for pages with no italics and high italics compared to moderate italics. The subjects rated the pages that contained only one colour higher than the web pages with four or six colours. This research will help web developers better understand the effect of font size, italics, and colour count on web usability in general, and for young adults, in particular.

Effect of font size, italics, and colour count on web usability

PubMed Central

Samal, Ashok; Rajan, Nithin; Kiviniemi, Marc T.

2013-01-01

Web usability measures the ease of use of a website. This study attempts to find the effect of three factors – font size, italics, and colour count – on web usability. The study was performed using a set of tasks and developing a survey questionnaire. We performed the study using a set of human subjects, selected from the undergraduate students taking courses in psychology. The data computed from the tasks and survey questionnaire were statistically analysed to find if there was any effect of font size, italics, and colour count on the three web usability dimensions. We found that for the student population considered, there was no significant effect of font size on usability. However, the manipulation of italics and colour count did influence some aspects of usability. The subjects performed better for pages with no italics and high italics compared to moderate italics. The subjects rated the pages that contained only one colour higher than the web pages with four or six colours. This research will help web developers better understand the effect of font size, italics, and colour count on web usability in general, and for young adults, in particular. PMID:24358055

Nano-Sized Structurally Disordered Metal Oxide Composite Aerogels as High-Power Anodes in Hybrid Supercapacitors.

PubMed

Huang, Haijian; Wang, Xing; Tervoort, Elena; Zeng, Guobo; Liu, Tian; Chen, Xi; Sologubenko, Alla; Niederberger, Markus

2018-03-27

A general method for preparing nano-sized metal oxide nanoparticles with highly disordered crystal structure and their processing into stable aqueous dispersions is presented. With these nanoparticles as building blocks, a series of nanoparticles@reduced graphene oxide (rGO) composite aerogels are fabricated and directly used as high-power anodes for lithium-ion hybrid supercapacitors (Li-HSCs). To clarify the effect of the degree of disorder, control samples of crystalline nanoparticles with similar particle size are prepared. The results indicate that the structurally disordered samples show a significantly enhanced electrochemical performance compared to the crystalline counterparts. In particular, structurally disordered Ni x Fe y O z @rGO delivers a capacity of 388 mAh g -1 at 5 A g -1 , which is 6 times that of the crystalline sample. Disordered Ni x Fe y O z @rGO is taken as an example to study the reasons for the enhanced performance. Compared with the crystalline sample, density functional theory calculations reveal a smaller volume expansion during Li + insertion for the structurally disordered Ni x Fe y O z nanoparticles, and they are found to exhibit larger pseudocapacitive effects. Combined with an activated carbon (AC) cathode, full-cell tests of the lithium-ion hybrid supercapacitors are performed, demonstrating that the structurally disordered metal oxide nanoparticles@rGO||AC hybrid systems deliver high energy and power densities within the voltage range of 1.0-4.0 V. These results indicate that structurally disordered nanomaterials might be interesting candidates for exploring high-power anodes for Li-HSCs.

Primary lithium batteries, some consumer considerations

NASA Technical Reports Server (NTRS)

Bro, P.

1983-01-01

In order to determine whether larger size lithium batteries would be commercially marketable, the performance of several D size lithium batteries was compared with that of an equivalent alkaline manganese battery, and the relative costs of the different systems were compared. It is concluded that opportunities exist in the consumer market for the larger sizes of the low rate and moderate rate lithium batteries, and that the high rate lithium batteries need further improvements before they can be recommended for consumer applications.

Computational Investigation of Effects of Grain Size on Ballistic Performance of Copper

NASA Astrophysics Data System (ADS)

He, Ge; Dou, Yangqing; Guo, Xiang; Liu, Yucheng

2018-01-01

Numerical simulations were conducted to compare ballistic performance and penetration mechanism of copper (Cu) with four representative grain sizes. Ballistic limit velocities for coarse-grained (CG) copper (grain size ≈ 90 µm), regular copper (grain size ≈ 30 µm), fine-grained (FG) copper (grain size ≈ 890 nm), and ultrafine-grained (UG) copper (grain size ≈ 200 nm) were determined for the first time through the simulations. It was found that the copper with reduced grain size would offer higher strength and better ductility, and therefore renders improved ballistic performance than the CG and regular copper. High speed impact and penetration behavior of the FG and UG copper was also compared with the CG coppers strengthened by nanotwinned (NT) regions. The comparison results showed the impact and penetration resistance of UG copper is comparable to the CG copper strengthened by NT regions with the minimum twin spacing. Therefore, besides the NT-strengthened copper, the single phase copper with nanoscale grain size could also be a strong candidate material for better ballistic protection. A computational modeling and simulation framework was proposed for this study, in which Johnson-Cook (JC) constitutive model is used to predict the plastic deformation of Cu; the JC damage model is to capture the penetration and fragmentation behavior of Cu; Bao-Wierzbicki (B-W) failure criterion defines the material's failure mechanisms; and temperature increase during this adiabatic penetration process is given by the Taylor-Quinney method.

Macular Ganglion Cell Imaging Study: Covariate Effects on the Spectral Domain Optical Coherence Tomography for Glaucoma Diagnosis.

PubMed

Jeong, Jae Hoon; Choi, Yun Jeong; Park, Ki Ho; Kim, Dong Myung; Jeoung, Jin Wook

2016-01-01

To evaluate the effect of multiple covariates on the diagnostic performance of the Cirrus high-definition optical coherence tomography (HD-OCT) for glaucoma detection. A prospective case-control study was performed and included 173 recently diagnosed glaucoma patients and 63 unaffected individuals from the Macular Ganglion Cell Imaging Study. Regression analysis of receiver operating characteristic were conducted to evaluate the influence of age, spherical equivalent, axial length, optic disc size, and visual field index on the macular ganglion cell-inner plexiform layer (GCIPL) and peripapillary retinal nerve fiber layer (RNFL) measurements. Disease severity, as measured by visual field index, had a significant effect on the diagnostic performance of all Cirrus HD-OCT parameters. Age, axial length and optic disc size were significantly associated with diagnostic accuracy of average peripapillary RNFL thickness, whereas axial length had a significant effect on the diagnostic accuracy of average GCIPL thickness. Diagnostic performance of the Cirrus HD-OCT may be more accurate in the advanced stages of glaucoma than at earlier stages. A smaller optic disc size was significantly associated with improved the diagnostic ability of average RNFL thickness measurements; however, GCIPL thickness may be less affected by age and optic disc size.

Battery energy storage sizing when time of use pricing is applied.

PubMed

Carpinelli, Guido; Khormali, Shahab; Mottola, Fabio; Proto, Daniela

2014-01-01

Battery energy storage systems (BESSs) are considered a key device to be introduced to actuate the smart grid paradigm. However, the most critical aspect related to the use of such device is its economic feasibility as it is a still developing technology characterized by high costs and limited life duration. Particularly, the sizing of BESSs must be performed in an optimized way in order to maximize the benefits related to their use. This paper presents a simple and quick closed form procedure for the sizing of BESSs in residential and industrial applications when time-of-use tariff schemes are applied. A sensitivity analysis is also performed to consider different perspectives in terms of life span and future costs.

Battery Energy Storage Sizing When Time of Use Pricing Is Applied

PubMed Central

Khormali, Shahab

2014-01-01

Battery energy storage systems (BESSs) are considered a key device to be introduced to actuate the smart grid paradigm. However, the most critical aspect related to the use of such device is its economic feasibility as it is a still developing technology characterized by high costs and limited life duration. Particularly, the sizing of BESSs must be performed in an optimized way in order to maximize the benefits related to their use. This paper presents a simple and quick closed form procedure for the sizing of BESSs in residential and industrial applications when time-of-use tariff schemes are applied. A sensitivity analysis is also performed to consider different perspectives in terms of life span and future costs. PMID:25295309

The role of the domain size and titanium dopant in nanocrystalline hematite thin films for water photolysis

DOE PAGES

Yan, Danhua; Tao, Jing; Kisslinger, Kim; ...

2015-10-13

Here we develop a novel technique for preparing high quality Ti-doped hematite thin films for photoelectrochemical (PEC) water splitting, through sputtering deposition of metallic iron films from an iron target embedded with titanium (dopants) pellets, followed by a thermal oxidation step that turns the metal films into doped hematite. It is found that the hematite domain size can be tuned from ~10 nm to over 100 nm by adjusting the sputtering atmosphere from more oxidative to mostly inert. The better crystallinity at a larger domain size ensures excellent PEC water splitting performance, leading to record high photocurrent from pure planarmore » hematite thin films on FTO substrates. Titanium doping further enhances the PEC performance of hematite photoanodes. The photocurrent is improved by 50%, with a titanium dopant concentration as low as 0.5 atom%. As a result, it is also found that the role of the titanium dopant in improving the PEC performance is not apparently related to the films’ electrical conductivity which had been widely believed, but is more likely due to the passivation of surface defects by the titanium dopants.« less

Design and performance verification of advanced multistage depressed collectors. [traveling wave tubes for ECM

NASA Technical Reports Server (NTRS)

Kosmahl, H.; Ramins, P.

1975-01-01

Design and performance of a small size, 4-stage depressed collector are discussed. The collector and a spent beam refocusing section preceding it are intended for efficiency enhancement of octave bandwidth, high CW power traveling wave tubes for use in ECM.

Particle size effect in porous film electrodes of ligand-modified graphene for enhanced supercapacitor performance

DOE PAGES

Jang, Gyoung Gug; Song, Bo; Moon, Kyoung-sik; ...

2017-04-17

Graphene-based electrodes for high performance supercapacitors are developed by taking advantage of particle size control, large mass loading, and surface functionalization of reduced graphene oxide (rGO) sheets. Two controlled sizes of graphene sheets (100 nm vs. 45 μm average lateral dimensions) were prepared to study two-electrode system performance. The nano-size graphenes led to the formation of mesoporous films, resulting in higher capacitance, better capacitance retension and lower equivalent series resistance (ESR), indicating better surface usability for diffusion and accessibility of electrolyte ions by shortening transport paths (compared with horizontally stacked films from micro-sized graphenes). For studies using an aqueous electrolyte,more » the maximum specific capacitance of nano-rGO film was 302 F/g (at 1 A/g with 4.3 mg/cm 2 of mass loading), which was ~2.4 times higher than micro-rGO film, and achieved a ~67% reduced ESR. With an organic electrolyte, the nano-rGO delivered ~4.2 times higher capacitance (115 F/g at 2 A/g with 4.3 mg/cm 2), 4.0 times lower IR drops, and an order-of-magnitude lower charge-transfer resistance with an energy density of 18.7 Wh/kg. Finally, the results of this work indicate that the size control of graphene sheet particles for film deposit electrodes can be a simple but effective approach to improve supercapacitor performance.« less

Particle size effect in porous film electrodes of ligand-modified graphene for enhanced supercapacitor performance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jang, Gyoung Gug; Song, Bo; Moon, Kyoung-sik

Graphene-based electrodes for high performance supercapacitors are developed by taking advantage of particle size control, large mass loading, and surface functionalization of reduced graphene oxide (rGO) sheets. Two controlled sizes of graphene sheets (100 nm vs. 45 μm average lateral dimensions) were prepared to study two-electrode system performance. The nano-size graphenes led to the formation of mesoporous films, resulting in higher capacitance, better capacitance retension and lower equivalent series resistance (ESR), indicating better surface usability for diffusion and accessibility of electrolyte ions by shortening transport paths (compared with horizontally stacked films from micro-sized graphenes). For studies using an aqueous electrolyte,more » the maximum specific capacitance of nano-rGO film was 302 F/g (at 1 A/g with 4.3 mg/cm 2 of mass loading), which was ~2.4 times higher than micro-rGO film, and achieved a ~67% reduced ESR. With an organic electrolyte, the nano-rGO delivered ~4.2 times higher capacitance (115 F/g at 2 A/g with 4.3 mg/cm 2), 4.0 times lower IR drops, and an order-of-magnitude lower charge-transfer resistance with an energy density of 18.7 Wh/kg. Finally, the results of this work indicate that the size control of graphene sheet particles for film deposit electrodes can be a simple but effective approach to improve supercapacitor performance.« less

Optimizing abdominal CT dose and image quality with respect to x-ray tube voltage

NASA Astrophysics Data System (ADS)

Huda, Walter; Ogden, Kent M.

2004-05-01

The objective of this study was to identify the x-ray tube voltage that results in optimum performance for abdominal CT imaging for a range of imaging tasks and patient sizes. Theoretical calculations were performed of the contrast to noise ratio (CNR) for disk shaped lesions of muscle, fat, bone and iodine embedded in a uniform water background. Lesion contrast was the mean Hounsfield Unit value at the effective photon energy, and image noise was determined from the total radiation intensity incident on the CT x-ray detector. Patient size ranging from young infants (10 kg) to oversized adults (120 kg), with CNR values obtained for x-ray tube voltages ranging from 80 to 140 kV. Patients of varying sizes were modeled as an equivalent cylinder of water, and the mean section dose (D) was determined for each selected x-ray tube kV value at a constant mAs. For each patient size and lesion type, we identified an optimal kV as the x-ray tube voltage that yields a maximum value of the figure of merit (CNR2/D). Increasing the x-ray tube voltage from 80 to 140 kV reduced lesion contrast by 11% for muscle, 21% for fat, 35% for bone and 52% for iodine, and these reductions were approximately independent of patient size. Increasing the x-ray tube voltage from 80 to 140 kV increased a muscle lesion CNR relative to a uniform water background by a factor of 2.6, with similar trends observed for fat (2.3), bone (1.9) and iodine (1.4). The improvement in lesion CNR with increasing x-ray tube voltage was highest for the largest sized patients. Increasing the x-ray tube voltage from 80 to 140 kV increased the patient dose by a factor of between 5.0 and 6.2 depending on the patient size. For small sized patients (10 and 30 kg) and muscle lesions, best performance is obtained at 80 kV; however, for adults (70 kg) and oversized adults (120 kg), the best performance would be obtained at 140 kV. Imaging fat lesions was best performed at 80 kV for all patients except for oversized adults, where 140 kV offers the best imaging performance. For high Z lesions of bone and iodine, imaging performance generally degrades with increasing kV for all patient sizes, with the degree of degradation largest for the smallest patients. We conclude that 80 kV is optimal with respect to radiation dose in abdominal CT for all pediatric patients. For adults, 80 kV is the x-ray voltage of choice for high Z lesions, whereas 140 kV would generally be the voltage of choice of lesions that have an atomic number similar to that of water.

Fine-grained versus categorical: Pupil size differentiates between strategies for spatial working memory performance.

PubMed

Starc, Martina; Anticevic, Alan; Repovš, Grega

2017-05-01

Pupillometry provides an accessible option to track working memory processes with high temporal resolution. Several studies showed that pupil size increases with the number of items held in working memory; however, no study has explored whether pupil size also reflects the quality of working memory representations. To address this question, we used a spatial working memory task to investigate the relationship of pupil size with spatial precision of responses and indicators of reliance on generalized spatial categories. We asked 30 participants (15 female, aged 19-31) to remember the position of targets presented at various locations along a hidden radial grid. After a delay, participants indicated the remembered location with a high-precision joystick providing a parametric measure of trial-to-trial accuracy. We recorded participants' pupil dilations continuously during task performance. Results showed a significant relation between pupil dilation during preparation/early encoding and the precision of responses, possibly reflecting the attentional resources devoted to memory encoding. In contrast, pupil dilation at late maintenance and response predicted larger shifts of responses toward prototypical locations, possibly reflecting larger reliance on categorical representation. On an intraindividual level, smaller pupil dilations during encoding predicted larger dilations during late maintenance and response. On an interindividual level, participants relying more on categorical representation also produced larger precision errors. The results confirm the link between pupil size and the quality of spatial working memory representation. They suggest compensatory strategies of spatial working memory performance-loss of precise spatial representation likely increases reliance on generalized spatial categories. © 2017 Society for Psychophysiological Research.

Characterization of micron-size hydrogen clusters using Mie scattering.

PubMed

Jinno, S; Tanaka, H; Matsui, R; Kanasaki, M; Sakaki, H; Kando, M; Kondo, K; Sugiyama, A; Uesaka, M; Kishimoto, Y; Fukuda, Y

2017-08-07

Hydrogen clusters with diameters of a few micrometer range, composed of 10 8-10 hydrogen molecules, have been produced for the first time in an expansion of supercooled, high-pressure hydrogen gas into a vacuum through a conical nozzle connected to a cryogenic pulsed solenoid valve. The size distribution of the clusters has been evaluated by measuring the angular distribution of laser light scattered from the clusters. The data were analyzed based on the Mie scattering theory combined with the Tikhonov regularization method including the instrumental functions, the validity of which was assessed by performing a calibration study using a reference target consisting of standard micro-particles with two different sizes. The size distribution of the clusters was found discrete peaked at 0.33 ± 0.03, 0.65 ± 0.05, 0.81 ± 0.06, 1.40 ± 0.06 and 2.00 ± 0.13 µm in diameter. The highly reproducible and impurity-free nature of the micron-size hydrogen clusters can be a promising target for laser-driven multi-MeV proton sources with the currently available high power lasers.

Fueling strategies to optimize performance: training high or training low?

PubMed

Burke, L M

2010-10-01

Availability of carbohydrate as a substrate for the muscle and central nervous system is critical for the performance of both intermittent high-intensity work and prolonged aerobic exercise. Therefore, strategies that promote carbohydrate availability, such as ingesting carbohydrate before, during and after exercise, are critical for the performance of many sports and a key component of current sports nutrition guidelines. Guidelines for daily carbohydrate intakes have evolved from the "one size fits all" recommendation for a high-carbohydrate diets to an individualized approach to fuel needs based on the athlete's body size and exercise program. More recently, it has been suggested that athletes should train with low carbohydrate stores but restore fuel availability for competition ("train low, compete high"), based on observations that the intracellular signaling pathways underpinning adaptations to training are enhanced when exercise is undertaken with low glycogen stores. The present literature is limited to studies of "twice a day" training (low glycogen for the second session) or withholding carbohydrate intake during training sessions. Despite increasing the muscle adaptive response and reducing the reliance on carbohydrate utilization during exercise, there is no clear evidence that these strategies enhance exercise performance. Further studies on dietary periodization strategies, especially those mimicking real-life athletic practices, are needed. © 2010 John Wiley & Sons A/S.

Challenge for lowering concentration polarization in solid oxide fuel cells

NASA Astrophysics Data System (ADS)

Shimada, Hiroyuki; Suzuki, Toshio; Yamaguchi, Toshiaki; Sumi, Hirofumi; Hamamoto, Koichi; Fujishiro, Yoshinobu

2016-01-01

In the scope of electrochemical phenomena, concentration polarization at electrodes is theoretically inevitable, and lowering the concentration overpotential to improve the performance of electrochemical cells has been a continuing challenge. Electrodes with highly controlled microstructure, i.e., high porosity and uniform large pores are therefore essential to achieve high performance electrochemical cells. In this study, state-of-the-art technology for controlling the microstructure of electrodes has been developed for realizing high performance support electrodes of solid oxide fuel cells (SOFCs). The key is controlling the porosity and pore size distribution to improve gas diffusion, while maintaining the integrity of the electrolyte and the structural strength of actual sized electrode supports needed for the target application. Planar anode-supported SOFCs developed in this study realize 5 μm thick dense electrolyte (yttria-stabilized zirconia: YSZ) and the anode substrate (Ni-YSZ) of 53.6 vol.% porosity with a large median pore diameter of 0.911 μm. Electrochemical measurements reveal that the performance of the anode-supported SOFCs improves with increasing anode porosity. This Ni-YSZ anode minimizes the concentration polarization, resulting in a maximum power density of 3.09 W cm-2 at 800 °C using humidified hydrogen fuel without any electrode functional layers.

Size-Sensitive Perceptual Representations Underlie Visual and Haptic Object Recognition

PubMed Central

Craddock, Matt; Lawson, Rebecca

2009-01-01

A variety of similarities between visual and haptic object recognition suggests that the two modalities may share common representations. However, it is unclear whether such common representations preserve low-level perceptual features or whether transfer between vision and haptics is mediated by high-level, abstract representations. Two experiments used a sequential shape-matching task to examine the effects of size changes on unimodal and crossmodal visual and haptic object recognition. Participants felt or saw 3D plastic models of familiar objects. The two objects presented on a trial were either the same size or different sizes and were the same shape or different but similar shapes. Participants were told to ignore size changes and to match on shape alone. In Experiment 1, size changes on same-shape trials impaired performance similarly for both visual-to-visual and haptic-to-haptic shape matching. In Experiment 2, size changes impaired performance on both visual-to-haptic and haptic-to-visual shape matching and there was no interaction between the cost of size changes and direction of transfer. Together the unimodal and crossmodal matching results suggest that the same, size-specific perceptual representations underlie both visual and haptic object recognition, and indicate that crossmodal memory for objects must be at least partly based on common perceptual representations. PMID:19956685

The Influence of Sizings on the Durability of High-Temperature Polymer Composites

NASA Technical Reports Server (NTRS)

Allred, Ronald E.; Wesson, Sheldon P.; Shin, E. Eugene; Inghram, Linda; McCorkle, Linda; Papadopoulos, Demetrios; Wheeler, Donald; Sutter, James K.

2004-01-01

To increase performance and durability of high-temperature composites for potential rocket engine components, it is necessary to optimize wetting and interfacial bonding between high modulus carbon fibers and high-temperature polyimide resins. Sizings commercially supplied on most carbon fibers are not compatible with polyimides. In this study, the chemistry of sizings on two high-modulus carbon fibers (M40J and M60J, Toray) was characterized as was the chemistry of PMR-II-50 fluorinated polyimide resin. The carbon fibers were characterized using single filament wetting, scanning electron microscopy, fourier transform infrared spectroscopy, and x-ray photoelectron spectroscopic measurements. The polyimide matrix resins were coated onto glass filaments for characterization by wetting measurements. Surface energy components were obtained by wetting with nondispersive (methylene iodide), acidic (ethylene glycol), and basic (formamide) probes. A continuous desizing system that uses an environmentally friendly chemical-mechanical process was developed for tow level fiber. Composites were fabricated with fibers containing the manufacturer's sizing, desized, and further treated with a reactive finish. Results of room-temperature tests after thermal aging show that the reactive finish produces a higher strength and more durable interface compared to the manufacturer's sizing. When exposed to moisture blistering tests, however, the better bonded composite displayed a tendency to delaminate, presumably due to trapping of volatiles.

Evaluation of Dewatering Performance and Fractal Characteristics of Alum Sludge

PubMed Central

Sun, Yongjun; Fan, Wei; Zheng, Huaili; Zhang, Yuxin; Li, Fengting; Chen, Wei

2015-01-01

The dewatering performance and fractal characteristics of alum sludge from a drinking-water treatment plant were investigated in this study. Variations in residual turbidity of supernatant, dry solid content (DS), specific resistance to filtration (SRF), floc size, fractal dimension, and zeta potential were analyzed. Sludge dewatering efficiency was evaluated by measuring both DS and SRF. Results showed that the optimum sludge dewatering efficiency was achieved at 16 mg∙L-1 flocculant dosage and pH 7. Under these conditions, the maximum DS was 54.6%, and the minimum SRF was 0.61 × 1010 m∙kg-1. Floc-size measurements demonstrated that high flocculant dosage significantly improved floc size. Correlation analysis further revealed a strong correlation between fractal dimension and floc size after flocculation. A strong correlation also existed between floc size and zeta potential, and flocculants with a higher cationic degree had a larger correlation coefficient between floc size and zeta potential. In the flocculation process, the main flocculation mechanisms involved adsorption bridging under an acidic condition, and a combination between charge neutralization and adsorption-bridging interaction under neutral and alkaline conditions. PMID:26121132

Selected properties of particleboard panels manufactured from rice straws of different geometries

Treesearch

Xianjun Li; Zhiyong Cai; Jerrold E. Winandy; Altaf H. Basta

2010-01-01

The objective is to evaluate the primary mechanical and physical properties of particleboard made from hammer-milled rice straw particles of six different categories and two types of resins. The results show the performance of straw particleboards is highly dependent upon the straw particle size controlled by the opening size of the perforated plate inside the hammer-...

A Comparison of Mission Statements of National Blue Ribbon Schools and Unacceptable Texas High Schools

ERIC Educational Resources Information Center

Perfetto, John Charles; Holland, Glenda; Davis, Rebecca; Fedynich, La Vonne

2013-01-01

This study was conducted to determine the themes present in the context of high schools, to determine any significant differences in themes for high and low performing high schools, and to determine if significant differences were present for the same sample of high schools based on school size. An analysis of the content of mission statements…

Concept development of a Mach 3.0 high-speed civil transport

NASA Technical Reports Server (NTRS)

Robins, A. Warner; Dollyhigh, Samuel M.; Beissner, Fred L., Jr.; Geiselhart, Karl; Martin, Glenn L.; Shields, E. W.; Swanson, E. E.; Coen, Peter G.; Morris, Shelby J., Jr.

1988-01-01

A baseline concept for a Mach 3.0 high-speed civil transport concept was developed as part of a national program with the goal that concepts and technologies be developed which will enable an effective long-range high-speed civil transport system. The Mach 3.0 concept reported represents an aggressive application of advanced technology to achieve the design goals. The level of technology is generally considered to be that which could have a demonstrated availability date of 1995 to 2000. The results indicate that aircraft are technically feasible that could carry 250 passengers at Mach 3.0 cruise for a 6500 nautical mile range at a size, weight and performance level that allows it to fit into the existing world airport structure. The details of the configuration development, aerodynamic design, propulsion system design and integration, mass properties, mission performance, and sizing are presented.

A semi-empirical model for the formation and depletion of the high burnup structure in UO 2

DOE PAGES

Pizzocri, D.; Cappia, F.; Luzzi, L.; ...

2017-01-31

In the rim zone of UO 2 nuclear fuel pellets, the combination of high burnup and low temperature drives a microstructural change, leading to the formation of the high burnup structure (HBS). In this work, we propose a semi-empirical model to describe the formation of the HBS, which embraces the polygonisation/recrystallization process and the depletion of intra-granular fission gas, describing them as inherently related. To this end, we per-formed grain-size measurements on samples at radial positions in which the restructuring was incomplete. Moreover, based on these new experimental data, we assume an exponential reduction of the average grain size withmore » local effective burnup, paired with a simultaneous depletion of intra-granular fission gas driven by diffusion. The comparison with currently used models indicates the applicability of the herein developed model within integral fuel performance codes.« less

Size effect in thermoelectric materials

NASA Astrophysics Data System (ADS)

Mao, Jun; Liu, Zihang; Ren, Zhifeng

2016-12-01

Thermoelectric applications have attracted increasing interest recently due to its capability of converting waste heat into electricity without hazardous emissions. Materials with enhanced thermoelectric performance have been reported in recent two decades. The revival of research for thermoelectric materials began in early 1990s when the size effect is considered. Low-dimensional materials with exceptionally high thermoelectric figure of merit (ZT) have been presented, which broke the limit of ZT around unity. The idea of size effect in thermoelectric materials even inspired the later nanostructuring and band engineering strategies, which effectively enhanced the thermoelectric performance of bulk materials. In this overview, the size effect in low-dimensional thermoelectric materials is reviewed. We first discuss the quantum confinement effect on carriers, including the enhancement of electronic density of states, semimetal to semiconductor transition and carrier pocket engineering. Then, the effect of assumptions on theoretical calculations is presented. Finally, the effect of phonon confinement and interface scattering on lattice thermal conductivity is discussed.

Self-assembled Ag nanoparticle network passivated by a nano-sized ZnO layer for transparent and flexible film heaters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Seo, Ki-Won; Kim, Han-Ki, E-mail: imdlhkkim@khu.ac.kr; Kim, Min-Yi

2015-12-15

We investigated a self-assembled Ag nanoparticle network electrode passivated by a nano-sized ZnO layer for use in high-performance transparent and flexible film heaters (TFFHs). The low temperature atomic layer deposition of a nano-sized ZnO layer effectively filled the uncovered area of Ag network and improved the current spreading in the self-assembled Ag network without a change in the sheet resistance and optical transmittance as well as mechanical flexibility. The time-temperature profiles and heat distribution analysis demonstrate that the performance of the TFTH with the ZnO/Ag network is superior to that of a TFFH with Ag nanowire electrodes. In addition, themore » TFTHs with ZnO/Ag network exhibited better stability than the TFFH with a bare Ag network due to the effective current spreading through the nano-sized ZnO layer.« less

Aerosol size distribution at Nansen Ice Sheet Antarctica

NASA Astrophysics Data System (ADS)

Belosi, F.; Contini, D.; Donateo, A.; Santachiara, G.; Prodi, F.

2012-04-01

During austral summer 2006, in the framework of the XXII Italian Antarctic expedition of PNRA (Italian National Program for Research in Antarctica), aerosol particle number size distribution measurements were performed in the 10-500 range nm over the Nansen Ice Sheet glacier (NIS, 74°30' S, 163°27' E; 85 m a.s.l), a permanently iced branch of the Ross Sea. Observed total particle number concentrations varied between 169 and 1385 cm- 3. A monomodal number size distribution, peaking at about 70 nm with no variation during the day, was observed for continental air mass, high wind speed and low relative humidity. Trimodal number size distributions were also observed, in agreement with measurements performed at Aboa station, which is located on the opposite side of the Antarctic continent to the NIS. In this case new particle formation, with subsequent particle growth up to about 30 nm, was observed even if not associated with maritime air masses.

The high intensity solar cell: Key to low cost photovoltaic power

NASA Technical Reports Server (NTRS)

Sater, B. L.; Goradia, C.

1975-01-01

The design considerations and performance characteristics of the 'high intensity' (HI) solar cell are presented. A high intensity solar system was analyzed to determine its cost effectiveness and to assess the benefits of further improving HI cell efficiency. It is shown that residential sized systems can be produced at less than $1000/kW peak electric power. Due to their superior high intensity performance characteristics compared to the conventional and VMJ cells, HI cells and light concentrators may be the key to low cost photovoltaic power.

Non-planar pad-printed thick-film focused high-frequency ultrasonic transducers for imaging and therapeutic applications.

PubMed

Lethiecq, Marc; Lou-Moeller, Rasmus; Ketterling, Jeffrey; Levassort, Franck; Tran-Huu-Hue, Louis Pascal; Filoux, Erwan; Silverman, Ronald H; Wolny, Wanda W

2012-09-01

Pad-printed thick-film transducers have been shown to be an interesting alternative to lapped bulk piezoceramics, because the film is deposited with the required thickness, size, and geometry, thus avoiding any subsequent machining to achieve geometrical focusing. Their electromechanical properties are close to those of bulk ceramics with similar composition despite having a higher porosity. In this paper, padprinted high-frequency transducers based on a low-loss piezoceramic composition are designed and fabricated. High-porosity ceramic cylinders with a spherical top surface are used as the backing substrate. The transducers are characterized in view of imaging applications and their imaging capabilities are evaluated with phantoms containing spherical inclusions and in different biological tissues. In addition, the transducers are evaluated for their capability to produce high-acoustic intensities at frequencies around 20 MHz. High-intensity measurements, obtained with a calibrated hydrophone, show that transducer performance is promising for applications that would require the same device to be used for imaging and for therapy. Nevertheless, the transducer design can be improved, and simulation studies are performed to find a better compromise between low-power and high-power performance. The size, geometry, and constitutive materials of optimized configurations are proposed and their feasibility is discussed.

Effect of four different size reduction methods on the particle size, solubility enhancement and physical stability of nicergoline nanocrystals.

PubMed

Martena, Valentina; Shegokar, Ranjita; Di Martino, Piera; Müller, Rainer H

2014-09-01

Nicergoline, a poorly soluble active pharmaceutical ingredient, possesses vaso-active properties which causes peripheral and central vasodilatation. In this study, nanocrystals of nicergoline were prepared in an aqueous solution of polysorbate 80 (nanosuspension) by using four different laboratory scale size reduction techniques: high pressure homogenization (HPH), bead milling (BM) and combination techniques (high pressure homogenization followed by bead milling HPH + BM, and bead milling followed by high pressure homogenization BM + HPH). Nanocrystals were investigated regarding to their mean particles size, zeta potential and particle dissolution. A short term physical stability study on nanocrystals stored at three different temperatures (4, 20 and 40 °C) was performed to evaluate the tendency to change in particle size, aggregation and zeta potential. The size reduction technique and the process parameters like milling time, number of homogenization cycles and pressure greatly affected the size of nanocrystals. Among the techniques used, the combination techniques showed superior and consistent particle size reduction compared to the other two methods, HPH + BM and BM + HPH giving nanocrystals of a mean particle size of 260 and 353 nm, respectively. The particle dissolution was increased for any nanocrystals samples, but it was particularly increased by HPH and combination techniques. Independently to the production method, nicergoline nanocrystals showed slight increase in particle size over the time, but remained below 500 nm at 20 °C and refrigeration conditions.

Body size, swimming speed, or thermal sensitivity? Predator-imposed selection on amphibian larvae.

PubMed

Gvoždík, Lumír; Smolinský, Radovan

2015-11-02

Many animals rely on their escape performance during predator encounters. Because of its dependence on body size and temperature, escape velocity is fully characterized by three measures, absolute value, size-corrected value, and its response to temperature (thermal sensitivity). The primary target of the selection imposed by predators is poorly understood. We examined predator (dragonfly larva)-imposed selection on prey (newt larvae) body size and characteristics of escape velocity using replicated and controlled predation experiments under seminatural conditions. Specifically, because these species experience a wide range of temperatures throughout their larval phases, we predict that larvae achieving high swimming velocities across temperatures will have a selective advantage over more thermally sensitive individuals. Nonzero selection differentials indicated that predators selected for prey body size and both absolute and size-corrected maximum swimming velocity. Comparison of selection differentials with control confirmed selection only on body size, i.e., dragonfly larvae preferably preyed on small newt larvae. Maximum swimming velocity and its thermal sensitivity showed low group repeatability, which contributed to non-detectable selection on both characteristics of escape performance. In the newt-dragonfly larvae interaction, body size plays a more important role than maximum values and thermal sensitivity of swimming velocity during predator escape. This corroborates the general importance of body size in predator-prey interactions. The absence of an appropriate control in predation experiments may lead to potentially misleading conclusions about the primary target of predator-imposed selection. Insights from predation experiments contribute to our understanding of the link between performance and fitness, and further improve mechanistic models of predator-prey interactions and food web dynamics.

The Influence of Intrinsic Framework Flexibility on Adsorption in Nanoporous Materials

DOE PAGES

Witman, Matthew; Ling, Sanliang; Jawahery, Sudi; ...

2017-03-30

For applications of metal–organic frameworks (MOFs) such as gas storage and separation, flexibility is often seen as a parameter that can tune material performance. In this work we aim to determine the optimal flexibility for the shape selective separation of similarly sized molecules (e.g., Xe/Kr mixtures). To obtain systematic insight into how the flexibility impacts this type of separation, we develop a simple analytical model that predicts a material’s Henry regime adsorption and selectivity as a function of flexibility. We elucidate the complex dependence of selectivity on a framework’s intrinsic flexibility whereby performance is either improved or reduced with increasingmore » flexibility, depending on the material’s pore size characteristics. However, the selectivity of a material with the pore size and chemistry that already maximizes selectivity in the rigid approximation is continuously diminished with increasing flexibility, demonstrating that the globally optimal separation exists within an entirely rigid pore. Molecular simulations show that our simple model predicts performance trends that are observed when screening the adsorption behavior of flexible MOFs. These flexible simulations provide better agreement with experimental adsorption data in a high-performance material that is not captured when modeling this framework as rigid, an approximation typically made in high-throughput screening studies. We conclude that, for shape selective adsorption applications, the globally optimal material will have the optimal pore size/chemistry and minimal intrinsic flexibility even though other nonoptimal materials’ selectivity can actually be improved by flexibility. In conclusion, equally important, we find that flexible simulations can be critical for correctly modeling adsorption in these types of systems.« less

Are normative sonographic values of kidney size in children valid and reliable? A systematic review of the methodological quality of ultrasound studies using the Anatomical Quality Assessment (AQUA) tool.

PubMed

Chhapola, Viswas; Tiwari, Soumya; Deepthi, Bobbity; Henry, Brandon Michael; Brar, Rekha; Kanwal, Sandeep Kumar

2018-06-01

A plethora of research is available on ultrasonographic kidney size standards. We performed a systematic review of methodological quality of ultrasound studies aimed at developing normative renal parameters in healthy children, by evaluating the risk of bias (ROB) using the 'Anatomical Quality Assessment (AQUA)' tool. We searched Medline, Scopus, CINAHL, and Google Scholar on June 04 2018, and observational studies measuring kidney size by ultrasonography in healthy children (0-18 years) were included. The ROB of each study was evaluated in five domains using a 20 item coding scheme based on AQUA tool framework. Fifty-four studies were included. Domain 1 (subject characteristics) had a high ROB in 63% of studies due to the unclear description of age, sex, and ethnicity. The performance in Domain 2 (study design) was the best with 85% of studies having a prospective design. Methodological characterization (Domain 3) was poor across the studies (< 10% compliance), with suboptimal performance in the description of patient positioning, operator experience, and assessment of intra/inter-observer reliability. About three-fourth of the studies had a low ROB in Domain 4 (descriptive anatomy). Domain 5 (reporting of results) had a high ROB in approximately half of the studies, the majority reporting results in the form of central tendency measures. Significant deficiencies and heterogeneity were observed in the methodological quality of USG studies performed to-date for measurement of kidney size in children. We hereby provide a framework for the conducting such studies in future. PROSPERO (CRD42017071601).

The Influence of Intrinsic Framework Flexibility on Adsorption in Nanoporous Materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Witman, Matthew; Ling, Sanliang; Jawahery, Sudi

For applications of metal–organic frameworks (MOFs) such as gas storage and separation, flexibility is often seen as a parameter that can tune material performance. In this work we aim to determine the optimal flexibility for the shape selective separation of similarly sized molecules (e.g., Xe/Kr mixtures). To obtain systematic insight into how the flexibility impacts this type of separation, we develop a simple analytical model that predicts a material’s Henry regime adsorption and selectivity as a function of flexibility. We elucidate the complex dependence of selectivity on a framework’s intrinsic flexibility whereby performance is either improved or reduced with increasingmore » flexibility, depending on the material’s pore size characteristics. However, the selectivity of a material with the pore size and chemistry that already maximizes selectivity in the rigid approximation is continuously diminished with increasing flexibility, demonstrating that the globally optimal separation exists within an entirely rigid pore. Molecular simulations show that our simple model predicts performance trends that are observed when screening the adsorption behavior of flexible MOFs. These flexible simulations provide better agreement with experimental adsorption data in a high-performance material that is not captured when modeling this framework as rigid, an approximation typically made in high-throughput screening studies. We conclude that, for shape selective adsorption applications, the globally optimal material will have the optimal pore size/chemistry and minimal intrinsic flexibility even though other nonoptimal materials’ selectivity can actually be improved by flexibility. In conclusion, equally important, we find that flexible simulations can be critical for correctly modeling adsorption in these types of systems.« less

Match-derived relative pitch area changes the physical and team tactical performance of elite soccer players in small-sided soccer games.

PubMed

Olthof, Sigrid B H; Frencken, Wouter G P; Lemmink, Koen A P M

2018-07-01

Small-sided games (SSGs) are used in training sessions to prepare for full-sized matches. For the same number of players, smaller pitch sizes result in decreased physical performance and shorter interpersonal distances. A relative pitch area derived from the full-sized match results in larger pitch sizes and this may increase the fit between SSGs and full-sized matches. This study aimed to investigate SSGs with a traditional small pitch and a match-derived relative pitch area in youth elite soccer players. Four age categories (under-13, under-15, under-17 and under-19) played 4 vs. 4 plus goalkeepers on a small (40x30m, 120m 2 relative pitch area) and large pitch (68x47m, 320m 2 relative pitch area). The number of games per age category ranged 15-30. Positional data (LPM-system) were collected to determine physical (total distance covered, high intensity distance and number of sprints) and team tactical (inter-team distance, LPW-ratio, surface area, stretch indices, goalkeeper-defender distance) performance measures and tactical variability. On a large pitch, physical performance significantly increased, inter-team and intra-team distances were significantly larger and tactical variability of intra-team distance measures significantly increased. The match-derived relative pitch area is an important training manipulation and leads to changes in physical and tactical performance 4 vs. 4 plus goalkeepers.

A study of the depth and size of concave cube Au nanoparticles as highly sensitive SERS probes

NASA Astrophysics Data System (ADS)

Romo-Herrera, J. M.; González, A. L.; Guerrini, L.; Castiello, F. R.; Alonso-Nuñez, G.; Contreras, O. E.; Alvarez-Puebla, R. A.

2016-03-01

High and uniform near fields are localized at the eight similar sharp corners of cubic gold nanoparticles. Moreover, by introducing concavity in the particle lateral planes, such field intensities can be further increased and tuned in the near infrared region without altering the overall size of the nanoparticles. Herein, we perform a thorough investigation of the morphological, crystallographic and plasmonic properties of concave gold nanocubes (GNCs) in the sub-70 nm size range, for their potential application as highly efficient SERS substrates in size-limiting cases. Theoretical calculations indicate that the highest increment of the near-field is located at the eight sharp tips and, interestingly, a medium near-field increment is also activated over the volume next to the concave surface. Remarkably, the plasmonic response of the concave cubic morphology showed great sensitivity to the concavity degree. Experimental SERS analysis nicely matches the outcome of the theoretical model, confirming that medium-sized concave GNCs (35 nm side length) possess the highest SERS activity upon excitation with a 633 nm laser, whereas larger 61 nm side concave GNCs dominate the optical response at 785 nm. Due to their size-intensity trade off, we envision that such small concave gold nanocubes can provide a highly active and efficient SERS platform for size-limiting applications, especially when near infrared excitations are required.High and uniform near fields are localized at the eight similar sharp corners of cubic gold nanoparticles. Moreover, by introducing concavity in the particle lateral planes, such field intensities can be further increased and tuned in the near infrared region without altering the overall size of the nanoparticles. Herein, we perform a thorough investigation of the morphological, crystallographic and plasmonic properties of concave gold nanocubes (GNCs) in the sub-70 nm size range, for their potential application as highly efficient SERS substrates in size-limiting cases. Theoretical calculations indicate that the highest increment of the near-field is located at the eight sharp tips and, interestingly, a medium near-field increment is also activated over the volume next to the concave surface. Remarkably, the plasmonic response of the concave cubic morphology showed great sensitivity to the concavity degree. Experimental SERS analysis nicely matches the outcome of the theoretical model, confirming that medium-sized concave GNCs (35 nm side length) possess the highest SERS activity upon excitation with a 633 nm laser, whereas larger 61 nm side concave GNCs dominate the optical response at 785 nm. Due to their size-intensity trade off, we envision that such small concave gold nanocubes can provide a highly active and efficient SERS platform for size-limiting applications, especially when near infrared excitations are required. Electronic supplementary information (ESI) available: Nanoparticle size distribution analysis (Fig. SI-1); extended TEM analysis on nanocubes morphology (Fig. SI-2, SI-3 and SI-4); comparison of GNCs size and concavity degree (Fig. SI-4); optical response calculations using the curved edges model (Fig. SI-5); simulated optical absorption spectra as a function of the concavity depth (Fig. SI-6); background SERS spectrum (Fig. SI-8) and details on the calculation of the SERS enhancement factors. See DOI: 10.1039/c6nr01155a

A Novel Approach to Synthesize Micrometer-Sized Porous Silicon as a High Performance Anode for Lithium-Ion Batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jia, Haiping; Zheng, Jianming; Song, Junhua

Porous structured silicon (p-Si) has been recognized as one of the most promising anodes for Li-ion batteries. However, many available methods to synthesize p-Si are difficult to scale up due to their high production cost. Here we introduce a new approach to obtain spherical micrometer-sized silicon with unique porous structure by using a microemulsion of the cost-effective of silica nanoparticles and magnesiothermic reduction method. The spherical micron-sized p-Si particles prepared by this approach consist of highly aligned nano-sized silicon and exhibit a tap density close to that of bulk Si particles. They have demonstrated significantly improved electrochemical stability compared tomore » nano-Si. Well controlled void space and a highly graphitic carbon coating on the p-Si particles enable good stability of the structure and low overall resistance, thus resulting in a Si-based anode with high capacity (~1467 mAh g –1 at 1 C), enhanced cycle life (370 cycles with 83% capacity retention), and high rate capability (~650 mAh g –1 at 5 C). Furthermore, this approach may also be generalized to prepare other hierarchical structured high capacity anode materials for constructing high energy density lithium ion batteries.« less

A Novel Approach to Synthesize Micrometer-Sized Porous Silicon as a High Performance Anode for Lithium-Ion Batteries

DOE PAGES

Jia, Haiping; Zheng, Jianming; Song, Junhua; ...

2018-05-21

Porous structured silicon (p-Si) has been recognized as one of the most promising anodes for Li-ion batteries. However, many available methods to synthesize p-Si are difficult to scale up due to their high production cost. Here we introduce a new approach to obtain spherical micrometer-sized silicon with unique porous structure by using a microemulsion of the cost-effective of silica nanoparticles and magnesiothermic reduction method. The spherical micron-sized p-Si particles prepared by this approach consist of highly aligned nano-sized silicon and exhibit a tap density close to that of bulk Si particles. They have demonstrated significantly improved electrochemical stability compared tomore » nano-Si. Well controlled void space and a highly graphitic carbon coating on the p-Si particles enable good stability of the structure and low overall resistance, thus resulting in a Si-based anode with high capacity (~1467 mAh g –1 at 1 C), enhanced cycle life (370 cycles with 83% capacity retention), and high rate capability (~650 mAh g –1 at 5 C). Furthermore, this approach may also be generalized to prepare other hierarchical structured high capacity anode materials for constructing high energy density lithium ion batteries.« less

Sample size requirements for estimating effective dose from computed tomography using solid-state metal-oxide-semiconductor field-effect transistor dosimetry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Trattner, Sigal; Cheng, Bin; Pieniazek, Radoslaw L.

2014-04-15

Purpose: Effective dose (ED) is a widely used metric for comparing ionizing radiation burden between different imaging modalities, scanners, and scan protocols. In computed tomography (CT), ED can be estimated by performing scans on an anthropomorphic phantom in which metal-oxide-semiconductor field-effect transistor (MOSFET) solid-state dosimeters have been placed to enable organ dose measurements. Here a statistical framework is established to determine the sample size (number of scans) needed for estimating ED to a desired precision and confidence, for a particular scanner and scan protocol, subject to practical limitations. Methods: The statistical scheme involves solving equations which minimize the sample sizemore » required for estimating ED to desired precision and confidence. It is subject to a constrained variation of the estimated ED and solved using the Lagrange multiplier method. The scheme incorporates measurement variation introduced both by MOSFET calibration, and by variation in MOSFET readings between repeated CT scans. Sample size requirements are illustrated on cardiac, chest, and abdomen–pelvis CT scans performed on a 320-row scanner and chest CT performed on a 16-row scanner. Results: Sample sizes for estimating ED vary considerably between scanners and protocols. Sample size increases as the required precision or confidence is higher and also as the anticipated ED is lower. For example, for a helical chest protocol, for 95% confidence and 5% precision for the ED, 30 measurements are required on the 320-row scanner and 11 on the 16-row scanner when the anticipated ED is 4 mSv; these sample sizes are 5 and 2, respectively, when the anticipated ED is 10 mSv. Conclusions: Applying the suggested scheme, it was found that even at modest sample sizes, it is feasible to estimate ED with high precision and a high degree of confidence. As CT technology develops enabling ED to be lowered, more MOSFET measurements are needed to estimate ED with the same precision and confidence.« less

Analysis of YBCO high temperature superconductor doped with silver nanoparticles and carbon nanotubes using Williamson-Hall and size-strain plot

NASA Astrophysics Data System (ADS)

Dadras, Sedigheh; Davoudiniya, Masoumeh

2018-05-01

This paper sets out to investigate and compare the effects of Ag nanoparticles and carbon nanotubes (CNTs) doping on the mechanical properties of Y1Ba2Cu3O7-δ (YBCO) high temperature superconductor. For this purpose, the pure and doped YBCO samples were synthesized by sol-gel method. The microstructural analysis of the samples is performed using X-ray diffraction (XRD). The crystalline size, lattice strain and stress of the pure and doped YBCO samples were estimated by modified forms of Williamson-Hall analysis (W-H), namely, uniform deformation model (UDM), uniform deformation stress model (UDSM) and the size-strain plot method (SSP). These results show that the crystalline size, lattice strain and stress of the YBCO samples declined by Ag nanoparticles and CNTs doping.

All You Can Eat: High Performance Capacity and Plasticity in the Common Big-Eared Bat, Micronycteris microtis (Chiroptera: Phyllostomidae)

PubMed Central

Santana, Sharlene E.; Geipel, Inga; Dumont, Elizabeth R.; Kalka, Margareta B.; Kalko, Elisabeth K. V.

2011-01-01

Ecological specialization and resource partitioning are expected to be particularly high in the species-rich communities of tropical vertebrates, yet many species have broader ecological niches than expected. In Neotropical ecosystems, Neotropical leaf-nosed bats (Phyllostomidae) are one of the most ecologically and functionally diverse vertebrate clades. Resource partitioning in phyllostomids might be achieved through differences in the ability to find and process food. We selected Micronycteris microtis, a very small (5–7 g) animalivorous phyllostomid, to explore whether broad resource use is associated with specific morphological, behavioral and performance traits within the phyllostomid radiation. We documented processing of natural prey and measured bite force in free-ranging M. microtis and other sympatric phyllostomids. We found that M. microtis had a remarkably broad diet for prey size and hardness. For the first time, we also report the consumption of vertebrates (lizards), which makes M. microtis the smallest carnivorous bat reported to date. Compared to other phyllostomids, M. microtis had the highest bite force for its size and cranial shape and high performance plasticity. Bite force and cranial shape appear to have evolved rapidly in the M. microtis lineage. High performance capacity and high efficiency in finding motionless prey might be key traits that allow M. microtis, and perhaps other species, to successfully co-exist with other gleaning bats. PMID:22164308

MCP-PMT studies at the High-B test facility at Jefferson Lab

DOE PAGES

Ilieva, Yordanka; Allison, Lee; Cao, Tongtong; ...

2016-03-30

Here we present preliminary results for the gain performance of commercially available 3- mum and 6- mum pore-size single-anode microchannel-plate photomultipliers (MCP PMTs) in magnetic fields up to 5 T and for various orientations of the sensor relative to the field direction. The measurements were performed at Thomas Jefferson National Accelerator Facility in Newport News, VA. Our results show that smaller-pore-size PMTs have better gain performance in magnetic fields. At various angles, the shape of the gain dependence on the strength of the magnetic field strongly depends on the type of the sensor. Also, for each sensor, the azimuthal dependencemore » is strongly correlated with the polar angle. Overall, the sensors exhibit a reasonable performance up to 2 T, although that upper limit depends on the sensor, the applied high voltage, and the orientation of the sensor relative to the field. To optimize the operational and design parameters of MCP PMTs for performance in high magnetic fields, further measurements and simulation studies will be pursued. Furthermore, our studies are part of an R&D for development of a Detector of Internally Reflected Cherenkov Light for the central detector of a future U.S. Electron Ion Collider.« less

An Approximate Ablative Thermal Protection System Sizing Tool for Entry System Design

NASA Technical Reports Server (NTRS)

Dec, John A.; Braun, Robert D.

2005-01-01

A computer tool to perform entry vehicle ablative thermal protection systems sizing has been developed. Two options for calculating the thermal response are incorporated into the tool. One, an industry-standard, high-fidelity ablation and thermal response program was integrated into the tool, making use of simulated trajectory data to calculate its boundary conditions at the ablating surface. Second, an approximate method that uses heat of ablation data to estimate heat shield recession during entry has been coupled to a one-dimensional finite-difference calculation that calculates the in-depth thermal response. The in-depth solution accounts for material decomposition, but does not account for pyrolysis gas energy absorption through the material. Engineering correlations are used to estimate stagnation point convective and radiative heating as a function of time. The sizing tool calculates recovery enthalpy, wall enthalpy, surface pressure, and heat transfer coefficient. Verification of this tool is performed by comparison to past thermal protection system sizings for the Mars Pathfinder and Stardust entry systems and calculations are performed for an Apollo capsule entering the atmosphere at lunar and Mars return speeds.

An Approximate Ablative Thermal Protection System Sizing Tool for Entry System Design

NASA Technical Reports Server (NTRS)

Dec, John A.; Braun, Robert D.

2006-01-01

A computer tool to perform entry vehicle ablative thermal protection systems sizing has been developed. Two options for calculating the thermal response are incorporated into the tool. One, an industry-standard, high-fidelity ablation and thermal response program was integrated into the tool, making use of simulated trajectory data to calculate its boundary conditions at the ablating surface. Second, an approximate method that uses heat of ablation data to estimate heat shield recession during entry has been coupled to a one-dimensional finite-difference calculation that calculates the in-depth thermal response. The in-depth solution accounts for material decomposition, but does not account for pyrolysis gas energy absorption through the material. Engineering correlations are used to estimate stagnation point convective and radiative heating as a function of time. The sizing tool calculates recovery enthalpy, wall enthalpy, surface pressure, and heat transfer coefficient. Verification of this tool is performed by comparison to past thermal protection system sizings for the Mars Pathfinder and Stardust entry systems and calculations are performed for an Apollo capsule entering the atmosphere at lunar and Mars return speeds.

Dynamic Failure and Fragmentation of a Hot-Pressed Boron Carbide

NASA Astrophysics Data System (ADS)

Sano, Tomoko; Vargas-Gonzalez, Lionel; LaSalvia, Jerry; Hogan, James David

2017-12-01

This study investigates the failure and fragmentation of a hot-pressed boron carbide during high rate impact experiments. Four impact experiments are performed using a composite-backed target configuration at similar velocities, where two of the impact experiments resulted in complete target penetration and two resulted in partial penetration. This paper seeks to evaluate and understand the dynamic behavior of the ceramic that led to either the complete or partial penetration cases, focusing on: (1) surface and internal failure features of fragments using optical, scanning electron, and transmission electron microscopy, and (2) fragment size analysis using state-of-the-art particle-sizing technology that informs about the consequences of failure. Detailed characterization of the mechanical properties and the microstructure is also performed. Results indicate that transgranular fracture was the primary mode of failure in this boron carbide material, and no stress-induced amorphization features were observed. Analysis of the fragment sizes for the partial and completely penetrated experiments revealed a possible correlation between larger fragment sizes and impact performance. The results will add insight into designing improved advanced ceramics for impact protection applications.

Company Training. A Key Strategy for Success. Workforce Brief #2.

ERIC Educational Resources Information Center

Bergman, Terri

General research and anecdotal reports have confirmed that both technical and basic skills training offer many benefits to companies of all sizes. Company training can improve employee performance, firm productivity, product quality, and company profitability. Training supports "high-performance" work practices such as the following: total quality…

The Effects of Vocabulary Knowledge and Dictionary Use on EFL Reading Performance

ERIC Educational Resources Information Center

Shen, Zhifa

2013-01-01

The present study mainly investigated the effects of vocabulary knowledge and dictionary use on EFL reading performance. The results show that scores on vocabulary size, specific vocabulary knowledge, and reading comprehension are highly and positively correlated. Scores on specific vocabulary knowledge are more closely correlated with reading…

Endoscopic Stone Measurement During Ureteroscopy.

PubMed

Ludwig, Wesley W; Lim, Sunghwan; Stoianovici, Dan; Matlaga, Brian R

2018-01-01

Currently, stone size cannot be accurately measured while performing flexible ureteroscopy (URS). We developed novel software for ureteroscopic, stone size measurement, and then evaluated its performance. A novel application capable of measuring stone fragment size, based on the known distance of the basket tip in the ureteroscope's visual field, was designed and calibrated in a laboratory setting. Complete URS procedures were recorded and 30 stone fragments were extracted and measured using digital calipers. The novel software program was applied to the recorded URS footage to obtain ureteroscope-derived stone size measurements. These ureteroscope-derived measurements were then compared with the actual-measured fragment size. The median longitudinal and transversal errors were 0.14 mm (95% confidence interval [CI] 0.1, 0.18) and 0.09 mm (95% CI 0.02, 0.15), respectively. The overall software accuracy and precision were 0.17 and 0.15 mm, respectively. The longitudinal and transversal measurements obtained by the software and digital calipers were highly correlated (r = 0.97 and 0.93). Neither stone size nor stone type was correlated with error measurements. This novel method and software reliably measured stone fragment size during URS. The software ultimately has the potential to make URS safer and more efficient.

Analysis of Cereal Starches by High Performance Size Exclusion Chromatography

USDA-ARS?s Scientific Manuscript database

Starch has unique physicochemical characteristics among carbohydrates. Most starch granules are a mixture of two sugar polymers: a highly branched polysaccharide named amylopectin, and a basically linear polysaccharide named amylose. The objective of this study was to develop a simple, one-step and ...

Sharks modulate their escape behavior in response to predator size, speed and approach orientation.

PubMed

Seamone, Scott; Blaine, Tristan; Higham, Timothy E

2014-12-01

Escape responses are often critical for surviving predator-prey interactions. Nevertheless, little is known about how predator size, speed and approach orientation impact escape performance, especially in larger prey that are primarily viewed as predators. We used realistic shark models to examine how altering predatory behavior and morphology (size, speed and approach orientation) influences escape behavior and performance in Squalus acanthias, a shark that is preyed upon by apex marine predators. Predator models induced C-start escape responses, and increasing the size and speed of the models triggered a more intense response (increased escape turning rate and acceleration). In addition, increased predator size resulted in greater responsiveness from the sharks. Among the responses, predator approach orientation had the most significant impact on escapes, such that the head-on approach, as compared to the tail-on approach, induced greater reaction distances and increased escape turning rate, speed and acceleration. Thus, the anterior binocular vision in sharks renders them less effective at detecting predators approaching from behind. However, it appears that sharks compensate by performing high-intensity escapes, likely induced by the lateral line system, or by a sudden visual flash of the predator entering their field of view. Our study reveals key aspects of escape behavior in sharks, highlighting the modulation of performance in response to predator approach. Copyright © 2014 Elsevier GmbH. All rights reserved.

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

PubMed

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

2011-12-01

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

Doping and controllable pore size enhanced electrochemical performance of free-standing 3D graphene films

NASA Astrophysics Data System (ADS)

Wang, Liping; Qin, Kaiqiang; Li, Jiajun; Zhao, Naiqin; Shi, Chunsheng; Ma, Liying; He, Chunnian; He, Fang; Liu, Enzuo

2018-01-01

High quality free-standing 3D nanoporous graphene (3DNG) films were fabricated using nanoporous nickel as template and catalyst. The effect of heteroatom doping and pore size on the electrochemical performance of the 3D graphene films as supercapacitor electrodes are systematically studied. Compared with macroporous graphene films, nanoporous graphene films exhibit an extraordinarily large operational window in neutral, acidic and alkaline aqueous electrolytes, as well as high packing density. Nitrogen and oxygen doping play different roles in different aqueous electrolytes on the electrical conductivity and pseudocapacitance of 3DNG. The realization of both high packing density, 3.65 mg/cm2, and the maximum working window, as well as the synergistic effect between N and O doping, gives rise to a high areal capacitance of 435 mF/cm2 in neutral electrolyte and excellent cycle stability up to 5000 cycles. The results provide a potential strategy to further increase the volumetric or areal energy density of carbon-based aqueous supercapacitor.

The Relationship Between the Permeability and the Performance of Carrier-Based Dry Powder Inhalation Mixtures: New Insights and Practical Guidance.

PubMed

Shalash, Ahmed O; Khalafallah, Nawal M; Molokhia, Abdulla M; Elsayed, Mustafa M A

2018-02-01

The permeability of a powder bed reflects its particle size distribution, shape, packing, porosity, cohesivity, and tensile strength in a manner relevant to powder fluidization. The relationship between the permeability and the performance of carrier-based dry powder inhalation (DPI) mixtures has, however, aroused controversy. The current study sought to gain new insights into the relationship and to explore its potential applications. We studied eight lactose materials as DPI carriers. The carriers covered a broad permeability range of 0.42-13.53 D and moreover differed in particle size distribution, particle shape, crystal form, and/or porosity. We evaluated the performance of inhalation mixtures of each of these carriers and fluticasone propionate after aerosolization from an Aerolizer®, a model turbulent-shear inhaler, at a flow rate of 60 L/min. Starting from the high permeability side, the inhalation mixture performance increased as the carrier permeability decreased until optimum performance was reached at permeability of ~ 3.2 D. Increased resistance to air flow strengthens aerodynamic dispersion forces. The inhalation mixture performance then decreased as the carrier permeability further decreased. Very high resistance to air flow restricts powder dispersion. The permeability accounted for effects of carrier size, shape, and macroporosity on the performance. We confirmed the relationship by analysis of two literature permeability-performance datasets, representing measurements that differ from ours in terms of carrier grades, drug, technique used to determine permeability, turbulent-shear inhaler, and/or aerosolization flow rate. Permeability provides useful information that can aid development of DPI mixtures for turbulent-shear inhalers. A practical guidance is provided.

Point of impact: the effect of size and speed on puncture mechanics.

PubMed

Anderson, P S L; LaCosse, J; Pankow, M

2016-06-06

The use of high-speed puncture mechanics for prey capture has been documented across a wide range of organisms, including vertebrates, arthropods, molluscs and cnidarians. These examples span four phyla and seven orders of magnitude difference in size. The commonality of these puncture systems offers an opportunity to explore how organisms at different scales and with different materials, morphologies and kinematics perform the same basic function. However, there is currently no framework for combining kinematic performance with cutting mechanics in biological puncture systems. Our aim here is to establish this framework by examining the effects of size and velocity in a series of controlled ballistic puncture experiments. Arrows of identical shape but varying in mass and speed were shot into cubes of ballistic gelatine. Results from high-speed videography show that projectile velocity can alter how the target gel responds to cutting. Mixed models comparing kinematic variables and puncture patterns indicate that the kinetic energy of a projectile is a better predictor of penetration than either momentum or velocity. These results form a foundation for studying the effects of impact on biological puncture, opening the door for future work to explore the influence of morphology and material organization on high-speed cutting dynamics.

High capacity demonstration of honeycomb panel heat pipes

NASA Technical Reports Server (NTRS)

Tanzer, H. J.

1989-01-01

The feasibility of performance enhancing the sandwich panel heat pipe was investigated for moderate temperature range heat rejection radiators on future-high-power spacecraft. The hardware development program consisted of performance prediction modeling, fabrication, ground test, and data correlation. Using available sandwich panel materials, a series of subscale test panels were augumented with high-capacity sideflow and temperature control variable conductance features, and test evaluated for correlation with performance prediction codes. Using the correlated prediction model, a 50-kW full size radiator was defined using methanol working fluid and closely spaced sideflows. A new concept called the hybrid radiator individually optimizes heat pipe components. A 2.44-m long hybrid test vehicle demonstrated proof-of-principle performance.

Efficiently passing messages in distributed spiking neural network simulation.

PubMed

Thibeault, Corey M; Minkovich, Kirill; O'Brien, Michael J; Harris, Frederick C; Srinivasa, Narayan

2013-01-01

Efficiently passing spiking messages in a neural model is an important aspect of high-performance simulation. As the scale of networks has increased so has the size of the computing systems required to simulate them. In addition, the information exchange of these resources has become more of an impediment to performance. In this paper we explore spike message passing using different mechanisms provided by the Message Passing Interface (MPI). A specific implementation, MVAPICH, designed for high-performance clusters with Infiniband hardware is employed. The focus is on providing information about these mechanisms for users of commodity high-performance spiking simulators. In addition, a novel hybrid method for spike exchange was implemented and benchmarked.

Simulation and performance analysis of a novel high-accuracy sheathless microfluidic impedance cytometer with coplanar electrode layout.

PubMed

Caselli, Federica; Bisegna, Paolo

2017-10-01

The performance of a novel microfluidic impedance cytometer (MIC) with coplanar configuration is investigated in silico. The main feature of the device is the ability to provide accurate particle-sizing despite the well-known measurement sensitivity to particle trajectory. The working principle of the device is presented and validated by means of an original virtual laboratory providing close-to-experimental synthetic data streams. It is shown that a metric correlating with particle trajectory can be extracted from the signal traces and used to compensate the trajectory-induced error in the estimated particle size, thus reaching high-accuracy. An analysis of relevant parameters of the experimental setup is also presented. Copyright © 2017 IPEM. Published by Elsevier Ltd. All rights reserved.

Effects of Rotor Blade Scaling on High-Pressure Turbine Unsteady Loading

NASA Astrophysics Data System (ADS)

Lastiwka, Derek; Chang, Dongil; Tavoularis, Stavros

2013-03-01

The present work is a study of the effects of rotor blade scaling of a single-stage high pressure turbine on the time-averaged turbine performance and on parameters that influence vibratory stresses on the rotor blades and stator vanes. Three configurations have been considered: a reference case with 36 rotor blades and 24 stator vanes, a case with blades upscaled by 12.5%, and a case with blades downscaled by 10%. The present results demonstrate that blade scaling effects were essentially negligible on the time-averaged turbine performance, but measurable on the unsteady surface pressure fluctuations, which were intensified as blade size was increased. In contrast, blade torque fluctuations increased significantly as blade size decreased. Blade scaling effects were also measurable on the vanes.

Investigation of the effect of Anodized Duration toward Photocatalytic Performance of Nb2O5

NASA Astrophysics Data System (ADS)

Sabirin Zoolfakar, Ahmad; Atiqah Mokhtar, Nurul; Rani, Rozina Abdul; Samihah Khairir, Nur; Aqma Abu Talip, Mahzaton; Hafiz Mamat, Mohamad; Kadir, Rosmalini Abdul; Rusop, M.

2018-03-01

Highly oriented Nb2O5 nanoporous network produced via anodization for photocatalytic activity of methyl orange (MO) is presented. The anodization duration was varies from 0.5 to 2 hours and the photocatalytic performance is observed by degradation of MO solution. The Nb2O5 nanoparticles were added in MO solution and were exposed to the solar simulator for 3 hours. The morphology of Nb2O5 nanoporous and the photocatalytic performance are characterized in Field Emission Scanning Electron Microscopy (FESEM) and UV-Vis spectrophotometer, respectively. The result shows that different duration of anodized produce different sizes of nanoporous diameter that will significantly affect the photocatalytic performance. The 1.5 hours of anodized has the largest diameter size of nanoporous and exhibited the best photocatalytic performance

Spacecraft configuration study for second generation mobile satellite system

NASA Technical Reports Server (NTRS)

Louie, M.; Vonstentzsch, W.; Zanella, F.; Hayes, R.; Mcgovern, F.; Tyner, R.

1985-01-01

A high power, high performance communicatons satellite bus being developed is designed to satisfy a broad range of multimission payload requirements in a cost effective manner and is compatible with both STS and expendable launchers. Results are presented of tradeoff studies conducted to optimize the second generation mobile satellite system for its mass, power, and physical size. Investigations of the 20-meter antenna configuration, transponder linearization techniques, needed spacecraft modifications, and spacecraft power, dissipation, mass, and physical size indicate that the advanced spacecraft bus is capable of supporting the required payload for the satellite.

Simulation of the Focal Spot of the Accelerator Bremsstrahlung Radiation

NASA Astrophysics Data System (ADS)

Sorokin, V.; Bespalov, V.

2016-06-01

Testing of thick-walled objects by bremsstrahlung radiation (BR) is primarily performed via high-energy quanta. The testing parameters are specified by the focal spot size of the high-energy bremsstrahlung radiation. In determining the focal spot size, the high- energy BR portion cannot be experimentally separated from the low-energy BR to use high- energy quanta only. The patterns of BR focal spot formation have been investigated via statistical modeling of the radiation transfer in the target material. The distributions of BR quanta emitted by the target for different energies and emission angles under normal distribution of the accelerated electrons bombarding the target have been obtained, and the ratio of the distribution parameters has been determined.

Experiments in structural dynamics and control using a grid

NASA Technical Reports Server (NTRS)

Montgomery, R. C.

1985-01-01

Future spacecraft are being conceived that are highly flexible and of extreme size. The two features of flexibility and size pose new problems in control system design. Since large scale structures are not testable in ground based facilities, the decision on component placement must be made prior to full-scale tests on the spacecraft. Control law research is directed at solving problems of inadequate modelling knowledge prior to operation required to achieve peak performance. Another crucial problem addressed is accommodating failures in systems with smart components that are physically distributed on highly flexible structures. Parameter adaptive control is a method of promise that provides on-orbit tuning of the control system to improve performance by upgrading the mathematical model of the spacecraft during operation. Two specific questions are answered in this work. They are: What limits does on-line parameter identification with realistic sensors and actuators place on the ultimate achievable performance of a system in the highly flexible environment? Also, how well must the mathematical model used in on-board analytic redundancy be known and what are the reasonable expectations for advanced redundancy management schemes in the highly flexible and distributed component environment?

Control performances of a piezoactuator direct drive valve system at high temperatures with thermal insulation

NASA Astrophysics Data System (ADS)

Han, Yung-Min; Han, Chulhee; Kim, Wan Ho; Seong, Ho Yong; Choi, Seung-Bok

2016-09-01

This technical note presents control performances of a piezoactuator direct drive valve (PDDV) operated at high temperature environment. After briefly discussing operating principle and mechanical dimensions of the proposed PDDV, an appropriate size of the PDDV is manufactured. As a first step, the temperature effect on the valve performance is experimentally investigated by measuring the spool displacement at various temperatures. Subsequently, the PDDV is thermally insulated using aerogel and installed in a large-size heat chamber in which the pneumatic-hydraulic cylinders and sensors are equipped. A proportional-integral-derivative feedback controller is then designed and implemented to control the spool displacement of the valve system. In this work, the spool displacement is chosen as a control variable since it is directly related to the flow rate of the valve system. Three different sinusoidal displacements with different frequencies of 1, 10 and 50 Hz are used as reference spool displacement and tracking controls are undertaken up to 150 °C. It is shown that the proposed PDDV with the thermal insulation can provide favorable control responses without significant tracking errors at high temperatures.

The architecture of the High Performance Storage System (HPSS)

NASA Technical Reports Server (NTRS)

Teaff, Danny; Watson, Dick; Coyne, Bob

1994-01-01

The rapid growth in the size of datasets has caused a serious imbalance in I/O and storage system performance and functionality relative to application requirements and the capabilities of other system components. The High Performance Storage System (HPSS) is a scalable, next-generation storage system that will meet the functionality and performance requirements or large-scale scientific and commercial computing environments. Our goal is to improve the performance and capacity of storage by two orders of magnitude or more over what is available in the general or mass marketplace today. We are also providing corresponding improvements in architecture and functionality. This paper describes the architecture and functionality of HPSS.

Highly Efficient Catalytic Hydrogen Evolution from Ammonia Borane Using the Synergistic Effect of Crystallinity and Size of Noble-Metal-Free Nanoparticles Supported by Porous Metal-Organic Frameworks.

PubMed

Liu, Penglong; Gu, Xiaojun; Kang, Kai; Zhang, Hao; Cheng, Jia; Su, Haiquan

2017-03-29

A series of nonprecious metal nanoparticles (NPs) supported by metal-organic framework MIL-101 were synthesized using four methods and their catalytic performance on hydrogen evolution from ammonia borane (NH 3 BH 3 ) was studied. The results showed that the crystalline Co NPs with size of 4.5-8.5 and 14.5-24.5 nm had low activities featuring the total turnover frequency (TOF) values of 9.9 and 4.5 mol H2 mol cat -1 min -1 , respectively. In contrast, the amorphous Co NPs with size of 1.6-2.6 and 13.5-24.5 nm exhibited high activities featuring the total TOF values of 51.4 and 22.3 mol H2 mol cat -1 min -1 , respectively. The remarkably different activities could be ascribed to the different crystallinity and size of Co NPs in the catalysts. Moreover, the ultrasound-assisted in situ method was also successfully applied to bimetallic systems, and MIL-101-supported amorphous CuCo, FeCo and NiCo NPs had the catalytic activities with total TOF values of 51.7, 50.8, and 44.3 mol H2 mol cat -1 min -1 , respectively, which were the highest in the values of the reported non-noble metal Co-based catalysts. The present approach, namely, using the synergistic effect of crystallinity and size of metal NPs, may offer a new prospect for high-performance and low-cost nanocatalysts.

Investigation of thin/well-tunable liquid/gas diffusion layers exhibiting superior multifunctional performance in low-temperature electrolytic water splitting

DOE PAGES

Kang, Zhenye; Mo, Jingke; Yang, Gaoqiang; ...

2016-10-11

Liquid/gas diffusion layers (LGDLs), which are located between the catalyst layer (CL) and bipolar plate (BP), play an important role in enhancing the performance of water splitting in proton exchange membrane electrolyzer cells (PEMECs). They are expected to transport electrons, heat, and reactants/products simultaneously with minimum voltage, current, thermal, interfacial, and fluidic losses. Here in this study, the thin titanium-based LGDLs with straight-through pores and well-defined pore morphologies are comprehensively investigated for the first time. The novel LGDL with a 400 μm pore size and 0.7 porosity achieved a best-ever performance of 1.66 V at 2 A cm -2 andmore » 80 °C, as compared to the published literature. The thin/well-tunable titanium based LGDLs remarkably reduce ohmic and activation losses, and it was found that porosity has a more significant impact on performance than pore size. In addition, an appropriate equivalent electrical circuit model has been established to quantify the effects of pore morphologies. The rapid electrochemical reaction phenomena at the center of the PEMEC are observed by coupling with high-speed and micro-scale visualization systems. Lastly, the observed reactions contribute reasonable and pioneering data that elucidate the effects of porosity and pore size on the PEMEC performance. This study can be a new guide for future research and development towards high-efficiency and low-cost hydrogen energy.« less

Size-exclusion chromatography for the determination of the boiling point distribution of high-boiling petroleum fractions.

PubMed

Boczkaj, Grzegorz; Przyjazny, Andrzej; Kamiński, Marian

2015-03-01

The paper describes a new procedure for the determination of boiling point distribution of high-boiling petroleum fractions using size-exclusion chromatography with refractive index detection. Thus far, the determination of boiling range distribution by chromatography has been accomplished using simulated distillation with gas chromatography with flame ionization detection. This study revealed that in spite of substantial differences in the separation mechanism and the detection mode, the size-exclusion chromatography technique yields similar results for the determination of boiling point distribution compared with simulated distillation and novel empty column gas chromatography. The developed procedure using size-exclusion chromatography has a substantial applicability, especially for the determination of exact final boiling point values for high-boiling mixtures, for which a standard high-temperature simulated distillation would have to be used. In this case, the precision of final boiling point determination is low due to the high final temperatures of the gas chromatograph oven and an insufficient thermal stability of both the gas chromatography stationary phase and the sample. Additionally, the use of high-performance liquid chromatography detectors more sensitive than refractive index detection allows a lower detection limit for high-molar-mass aromatic compounds, and thus increases the sensitivity of final boiling point determination. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Small feature sizes and high aperture ratio organic light-emitting diodes by using laser-patterned polyimide shadow masks

NASA Astrophysics Data System (ADS)

Kajiyama, Yoshitaka; Joseph, Kevin; Kajiyama, Koichi; Kudo, Shuji; Aziz, Hany

2014-02-01

A shadow mask technique capable of realizing high resolution (>330 pixel-per-inch) and ˜100% aperture ratio Organic Light-Emitting Diode (OLED) full color displays is demonstrated. The technique utilizes polyimide contact shadow masks, patterned by laser ablation. Red, green, and blue OLEDs with very small feature sizes (<25 μm) are fabricated side by side on one substrate. OLEDs fabricated via this technique have the same performance as those made by established technology. This technique has a strong potential to achieve high resolution OLED displays via standard vacuum deposition processes even on flexible substrates.

Study on optimum length of raw material in stainless steel high-lock nuts forging

NASA Astrophysics Data System (ADS)

Cheng, Meiwen; Liu, Fenglei; Zhao, Qingyun; Wang, Lidong

2018-04-01

Taking 302 stainless steel (1Cr18Ni9) high-lock nuts for research objects, adjusting the length of raw material, then using DEFORM software to simulate the isothermal forging process of each station and conducting the corresponding field tests to study the effects of raw material size on the stainless steel high-lock nuts forming performance. The tests show that the samples of each raw material length is basically the same as the results of the DEFORM software. When the length of the raw material is 10mm, the appearance size of the parts can meet the design requirements.

Nonlinear absorption enhancement of AuNPs based polymer nanocomposites

NASA Astrophysics Data System (ADS)

Zulina, Natalia A.; Baranov, Mikhail A.; Kniazev, Kirill I.; Kaliabin, Viacheslav O.; Denisyuk, Igor Yu.; Achor, Susan U.; Sitnikova, Vera E.

2018-07-01

Au nanoparticles (AuNPs) based polymer nanocomposites with high nonlinear absorption coefficient were synthesized by UV-photocuring. AuNPs were synthesized by laser ablation method in liquid monomer isodecyl acrylate (IDA). In this research, two colloids with 70 nm and 20 nm nanoparticles average sizes were studied. Size control was performed with SEM and STEM. Prepared nanomaterials exhibit strong third-order nonlinear optical responses under CW laser irradiation at 532 nm, which was estimated by using z-scan technique performed with open aperture. It was found experimentally that nonlinear absorption β is almost twice higher for nanocomposites with smaller AuNPs.

75 FR 38156 - Small Business Size Standards: Waiver of the Nonmanufacturer Rule

Federal Register 2010, 2011, 2012, 2013, 2014

2010-07-01

... Systems (CS-MS), High Performance Liquid Chromatography (HPLC) Systems, Gas Chromatography Mass... Chromatography (HPLC) Systems, Gas Chromatography Mass Spectrometry (GC-MS) Systems, and, Inductively Coupled...

Assessment of diesel-contaminated domestic wastewater treated by constructed wetlands for irrigation of chillies grown in a greenhouse.

PubMed

Al-Isawi, Rawaa H K; Scholz, Miklas; Al-Faraj, Furat A M

2016-12-01

In order to avoid environmental pollution and eliminate the need for using fertiliser, this study assessed for the first time the optimum performance of mature (in operation since 2011) vertical flow constructed wetlands in treating domestic wastewater (with and without hydrocarbon) and the subsequent recycling of the outflow to irrigate chillies (De Cayenne; Capsicum annuum (Linnaeus) Longum Group 'De Cayenne') grown in a greenhouse. Various variables were investigated to assess the treatment performance. Concerning chilli fruit numbers, findings showed that the highest fruit yields for all wetland filters were associated with those that received inflow wastewater with a high loading rate, reflecting the high nutrient availability in treated wastewater, which is of obvious importance for yield production. Findings also indicated that wetlands without hydrocarbon, small aggregate size, low contact time and low inflow loading rate provided high marketable yields (expressed in economic return). In comparison, chillies irrigated by filters with hydrocarbon contamination, small aggregate size, high contact time and high loading rate also resulted in high marketable yields of chillies, which pointed out the role of high contact time and high inflow load for better diesel degradation rates.

Scale Comparability between Nonaccommodated and Accommodated Forms of a Statewide High School Assessment: Assessment Using "l[subscript z]" Person-Fit

ERIC Educational Resources Information Center

Seo, Dong Gi; Hao, Shiqi

2016-01-01

Differential item/test functioning (DIF/DTF) are routine procedures to detect item/test unfairness as an explanation for group performance difference. However, unequal sample sizes and small sample sizes have an impact on the statistical power of the DIF/DTF detection procedures. Furthermore, DIF/DTF cannot be used for two test forms without…

Identifying Effective Characteristics for Teaching in Urban and Suburban Settings

ERIC Educational Resources Information Center

Jones, Shawn Cecil

2017-01-01

Classroom size, curriculum, and student attendance are all important factors that affect student outcomes, but these factors cannot compare to the classroom teacher's influence on student academic performance. Unfortunately, highly qualified teachers are not equally effective in different school settings. Findings associated with highly effective…

Identifying Characteristics for Effective Teaching in Urban and Suburban Settings.

ERIC Educational Resources Information Center

Jones, Shawn Cecil

2017-01-01

Classroom size, curriculum, and student attendance are all important factors that affect student outcomes, but these factors cannot compare to the classroom teacher's influence on student academic performance. Unfortunately, highly qualified teachers are not equally effective in different school settings. Findings associated with highly effective…

High-performance computing on GPUs for resistivity logging of oil and gas wells

NASA Astrophysics Data System (ADS)

Glinskikh, V.; Dudaev, A.; Nechaev, O.; Surodina, I.

2017-10-01

We developed and implemented into software an algorithm for high-performance simulation of electrical logs from oil and gas wells using high-performance heterogeneous computing. The numerical solution of the 2D forward problem is based on the finite-element method and the Cholesky decomposition for solving a system of linear algebraic equations (SLAE). Software implementations of the algorithm used the NVIDIA CUDA technology and computing libraries are made, allowing us to perform decomposition of SLAE and find its solution on central processor unit (CPU) and graphics processor unit (GPU). The calculation time is analyzed depending on the matrix size and number of its non-zero elements. We estimated the computing speed on CPU and GPU, including high-performance heterogeneous CPU-GPU computing. Using the developed algorithm, we simulated resistivity data in realistic models.

High efficiency low cost monolithic module for SARSAT distress beacons

NASA Technical Reports Server (NTRS)

Petersen, Wendell C.; Siu, Daniel P.

1992-01-01

The program objectives were to develop a highly efficient, low cost RF module for SARSAT beacons; achieve significantly lower battery current drain, amount of heat generated, and size of battery required; utilize MMIC technology to improve efficiency, reliability, packaging, and cost; and provide a technology database for GaAs based UHF RF circuit architectures. Presented in viewgraph form are functional block diagrams of the SARSAT distress beacon and beacon RF module as well as performance goals, schematic diagrams, predicted performances, and measured performances for the phase modulator and power amplifier.

Whole-Genome Resequencing of Experimental Populations Reveals Polygenic Basis of Egg-Size Variation in Drosophila melanogaster

PubMed Central

Jha, Aashish R.; Miles, Cecelia M.; Lippert, Nodia R.; Brown, Christopher D.; White, Kevin P.; Kreitman, Martin

2015-01-01

Complete genome resequencing of populations holds great promise in deconstructing complex polygenic traits to elucidate molecular and developmental mechanisms of adaptation. Egg size is a classic adaptive trait in insects, birds, and other taxa, but its highly polygenic architecture has prevented high-resolution genetic analysis. We used replicated experimental evolution in Drosophila melanogaster and whole-genome sequencing to identify consistent signatures of polygenic egg-size adaptation. A generalized linear-mixed model revealed reproducible allele frequency differences between replicated experimental populations selected for large and small egg volumes at approximately 4,000 single nucleotide polymorphisms (SNPs). Several hundred distinct genomic regions contain clusters of these SNPs and have lower heterozygosity than the genomic background, consistent with selection acting on polymorphisms in these regions. These SNPs are also enriched among genes expressed in Drosophila ovaries and many of these genes have well-defined functions in Drosophila oogenesis. Additional genes regulating egg development, growth, and cell size show evidence of directional selection as genes regulating these biological processes are enriched for highly differentiated SNPs. Genetic crosses performed with a subset of candidate genes demonstrated that these genes influence egg size, at least in the large genetic background. These findings confirm the highly polygenic architecture of this adaptive trait, and suggest the involvement of many novel candidate genes in regulating egg size. PMID:26044351

The evolution of structural and chemical heterogeneity during rapid solidification at gas atomization

NASA Astrophysics Data System (ADS)

Golod, V. M.; Sufiiarov, V. Sh

2017-04-01

Gas atomization is a high-performance process for manufacturing superfine metal powders. Formation of the powder particles takes place primarily through the fragmentation of alloy melt flow with high-pressure inert gas, which leads to the formation of non-uniform sized micron-scale particles and subsequent their rapid solidification due to heat exchange with gas environment. The article presents results of computer modeling of crystallization process, simulation and experimental studies of the cellular-dendrite structure formation and microsegregation in different size particles. It presents results of adaptation of the approach for local nonequilibrium solidification to conditions of crystallization at gas atomization, detected border values of the particle size at which it is possible a manifestation of diffusionless crystallization.

Grain size mapping in shallow rivers using spectral information: a lab spectroradiometry perspective

NASA Astrophysics Data System (ADS)

Niroumand-Jadidi, Milad; Vitti, Alfonso

2017-10-01

Every individual attribute of a riverine environment defines the overall spectral signature to be observed by an optical sensor. The spectral characteristic of riverbed is influenced not only by the type but also the roughness of substrates. Motivated by this assumption, potential of optical imagery for mapping grain size of shallow rivers (< 1 m deep) is examined in this research. The previous studies concerned with grain size mapping are all built upon the texture analysis of exposed bed material using very high resolution (i.e. cm resolution) imagery. However, the application of texturebased techniques is limited to very low altitude sensors (e.g. UAVs) to ensure the sufficient spatial resolution. Moreover, these techniques are applicable only in the presence of exposed substrates along the river channel. To address these drawbacks, this study examines the effectiveness of spectral information to make distinction among grain sizes for submerged substrates. Spectroscopic experiments are performed in controlled condition of a hydraulic lab. The spectra are collected over a water flume in a range of water depths and bottoms with several grain sizes. A spectral convolution is performed to match the spectra to WorldView-2 spectral bands. The material type of substrates is considered the same for all the experiments with only variable roughness/size of grains. The spectra observed over dry beds revealed that the brightness/reflectance increases with the grain size across all the spectral bands. Based on this finding, the above-water spectra over a river channel are simulated considering different grain sizes in the bottom. A water column correction method is then used to retrieve the bottom reflectances. Then the inferred bottom reflectances are clustered to segregate among grain sizes. The results indicate high potential of the spectral approach for clustering grain sizes (overall accuracy of 92%) which opens up some horizons for mapping this valuable attribute of rivers using remotely sensed data.

Fiber optic sensor for measurement of pressure fluctuations at high temperatures

NASA Technical Reports Server (NTRS)

Zuckerwar, Allan J.; Cuomo, Frank W.

1989-01-01

A fiber-optic sensor, based on the principle of the fiber-optic lever, is described which features small size, extended bandwidth, and capability to operate at high temeratures, as required for measurements in hypersonic flow. The principle of operation, design features peculiar to the intended application, and expected performance at high temperatures are described.

The Academic Ethic and the Transition to College

ERIC Educational Resources Information Center

Smith, William L.; Zhang, Pidi

2009-01-01

This paper investigates one aspect of the transition of students from high school to college. It assesses whether students who had an academic ethic in high school performed better in their first semester of college than students who did not possess an academic ethic in high school. Survey data were collected from students at a medium-sized state…

Development of a small-sized generator of ozonated water using an electro-conductive diamond electrode.

PubMed

Sekido, Kota; Kitaori, Noriyuki

2008-12-01

A small-sized generator of ozonated water was developed using an electro-conductive diamond. We studied the optimum conditions for producing ozonated water. As a result, we developed a small-sized generator of ozonated water driven by a dry-cell for use in the average household. This generator was easily able to produce ozonated water with an ozone concentration (over 4 mg/L) sufficient for disinfection. In addition, we verified the high disinfecting performance of the water produced in an actual hospital.

Can common measures of core stability distinguish performance in a shoulder pressing task under stable and unstable conditions?

PubMed

Keogh, Justin W L; Aickin, Sam E; Oldham, Anthony R H

2010-02-01

The primary purpose of this study was to determine whether a range of static core stability (CS) measures could distinguish shoulder press performance in unstable vs. stable conditions. Thirty resistance-trained men gave informed consent to participate in this study. One-repetition maximum strength (from < 6 repetitions) was predicted in the seated shoulder dumbbell press performed in unstable (Swiss ball[SB]) and stable (back-support bench) environments. Three CS muscle endurance tests were performed, with 4 CS ratios also calculated. The degree of strength decrement, referred to as the instability strength level (ISL), was calculated by dividing the predicted 1RM Unstable score by the 1RM Stable score. All subjects were categorized as high (ISL > 0.90), moderate (0.85 < or = ISL < or = 0.90), or low (ISL < 0.85). Between-group differences for the high- and low-ISL groups were assessed using analysis of variance and effect sizes. Pearson product moment correlations were then performed to examine the relationships between the CS measures and the ISL for the entire group. No significant between-group differences (p = 0.132-0.999) or large effect sizes were observed for any of the CS measures. Trunk flexion endurance was the only CS measure significantly correlated to the ISL (r = 0.477). In line with muscular strength research, these results suggest that CS exhibits relatively high levels of task specificity and that CS performance in static single-joint exercises may not be highly related to that in more dynamic multijoint activities. Core stability training (with or without a SB) may therefore only lead to significant improvements in functional dynamic performance if the postures, mode and velocity of contraction performed in training, are similar to the competitive tasks.

Synthesis and Biological Response of Size-Specific, Monodisperse Drug-Silica Nanoconjugates

PubMed Central

Tang, Li; Fan, Timothy M.; Borst, Luke B.; Cheng, Jianjun

2012-01-01

Drug-containing nanoparticles (NPs) with monodisperse, controlled particle sizes are highly desirable for drug delivery. Accumulating evidence suggests that NPs with sizes less than 50 nm demonstrate superior performance in vitro and in vivo. However, it is difficult to fabricate monodisperse, drug-containing NPs with discrete and incremental difference in sizes required for studying and characterizing existing relationships among particle size, biologic processing, and therapeutic functionality. Here, we report a scalable process of fabricating drug-silica conjugated nanoparticles, termed drug-silica nanoconjugates (drug-NCs), which possess monodisperse size distributions and desirable particle sizes as small as 20 nm. We found that 20-nm NCs are superior to their 50-nm and 200-nm NC analogues by 2–5 and 10–20 folds, respectively, with regard to tumor accumulation and penetration, and cellular internalization. These fundamental findings underscore the importance and necessity of further miniaturizing nanomedicine size for optimized drug delivery applications. PMID:22494403

"V-junction": a novel structure for high-speed generation of bespoke droplet flows.

PubMed

Ding, Yun; Casadevall i Solvas, Xavier; deMello, Andrew

2015-01-21

We present the use of microfluidic "V-junctions" as a droplet generation strategy that incorporates enhanced performance characteristics when compared to more traditional "T-junction" formats. This includes the ability to generate target-sized droplets from the very first one, efficient switching between multiple input samples, the production of a wide range of droplet sizes (and size gradients) and the facile generation of droplets with residence time gradients. Additionally, the use of V-junction droplet generators enables the suspension and subsequent resumption of droplet flows at times defined by the user. The high degree of operational flexibility allows a wide range of droplet sizes, payloads, spacings and generation frequencies to be obtained, which in turn provides for an enhanced design space for droplet-based experimentation. We show that the V-junction retains the simplicity of operation associated with T-junction formats, whilst offering functionalities normally associated with droplet-on-demand technologies.

Large size crystalline vs. co-sintered ceramic Yb(3+):YAG disk performance in diode pumped amplifiers.

PubMed

Albach, Daniel; Chanteloup, Jean-Christophe

2015-01-12

A comprehensive experimental benchmarking of Yb(3+):YAG crystalline and co-sintered ceramic disks of similar thickness and doping level is presented in the context of high average power laser amplifier operation. Comparison is performed considering gain, depolarization and wave front deformation quantitative measurements and analysis.

Does Performance-Based Pay Improve Teaching? PISA in Focus. No. 16

ERIC Educational Resources Information Center

OECD Publishing (NJ1), 2012

2012-01-01

The Programme for International Student Assessment (PISA) has long established that high-performing education systems tend to pay their teachers more. They also often prioritise the quality of teaching over other choices, including class size. But in the current budgetary climate, paying everybody more may not be a viable alternative. So many…

High-throughput analysis of sub-visible mAb aggregate particles using automated fluorescence microscopy imaging.

PubMed

Paul, Albert Jesuran; Bickel, Fabian; Röhm, Martina; Hospach, Lisa; Halder, Bettina; Rettich, Nina; Handrick, René; Herold, Eva Maria; Kiefer, Hans; Hesse, Friedemann

2017-07-01

Aggregation of therapeutic proteins is a major concern as aggregates lower the yield and can impact the efficacy of the drug as well as the patient's safety. It can occur in all production stages; thus, it is essential to perform a detailed analysis for protein aggregates. Several methods such as size exclusion high-performance liquid chromatography (SE-HPLC), light scattering, turbidity, light obscuration, and microscopy-based approaches are used to analyze aggregates. None of these methods allows determination of all types of higher molecular weight (HMW) species due to a limited size range. Furthermore, quantification and specification of different HMW species are often not possible. Moreover, automation is a perspective challenge coming up with automated robotic laboratory systems. Hence, there is a need for a fast, high-throughput-compatible method, which can detect a broad size range and enable quantification and classification. We describe a novel approach for the detection of aggregates in the size range 1 to 1000 μm combining fluorescent dyes for protein aggregate labelling and automated fluorescence microscope imaging (aFMI). After appropriate selection of the dye and method optimization, our method enabled us to detect various types of HMW species of monoclonal antibodies (mAbs). Using 10 μmol L -1 4,4'-dianilino-1,1'-binaphthyl-5,5'-disulfonate (Bis-ANS) in combination with aFMI allowed the analysis of mAb aggregates induced by different stresses occurring during downstream processing, storage, and administration. Validation of our results was performed by SE-HPLC, UV-Vis spectroscopy, and dynamic light scattering. With this new approach, we could not only reliably detect different HMW species but also quantify and classify them in an automated approach. Our method achieves high-throughput requirements and the selection of various fluorescent dyes enables a broad range of applications.

Automated packaging platform for low-cost high-performance optical components manufacturing

NASA Astrophysics Data System (ADS)

Ku, Robert T.

2004-05-01

Delivering high performance integrated optical components at low cost is critical to the continuing recovery and growth of the optical communications industry. In today's market, network equipment vendors need to provide their customers with new solutions that reduce operating expenses and enable new revenue generating IP services. They must depend on the availability of highly integrated optical modules exhibiting high performance, small package size, low power consumption, and most importantly, low cost. The cost of typical optical system hardware is dominated by linecards that are in turn cost-dominated by transmitters and receivers or transceivers and transponders. Cost effective packaging of optical components in these small size modules is becoming the biggest challenge to be addressed. For many traditional component suppliers in our industry, the combination of small size, high performance, and low cost appears to be in conflict and not feasible with conventional product design concepts and labor intensive manual assembly and test. With the advent of photonic integration, there are a variety of materials, optics, substrates, active/passive devices, and mechanical/RF piece parts to manage in manufacturing to achieve high performance at low cost. The use of automation has been demonstrated to surpass manual operation in cost (even with very low labor cost) as well as product uniformity and quality. In this paper, we will discuss the value of using an automated packaging platform.for the assembly and test of high performance active components, such as 2.5Gb/s and 10 Gb/s sources and receivers. Low cost, high performance manufacturing can best be achieved by leveraging a flexible packaging platform to address a multitude of laser and detector devices, integration of electronics and handle various package bodies and fiber configurations. This paper describes the operation and results of working robotic assemblers in the manufacture of a Laser Optical Subassembly (LOS), its subsequent automated testing and burn/in process; and the placement of the LOS into a package body and hermetically sealing the package. The LOS and Package automated assembler robots have achieved a metrics of less than 1 um accuracy and 0.1 um resolution. The paper also discusses a method for the critical alignment of a single-mode fiber as the last step of the manufacturing process. This approach is in contrast to the conventional manual assembly where sub-micron fiber alignment and fixation steps are performed much earlier during the assembly process. Finally the paper discusses the value of this automated platform manufacturing approach as a key enabler for low cost small form factor optical components for the new XFP MSA class of transceiver modules.

Manufacture and performance of full size structural flakeboards from Douglas-fir forest residues

Treesearch

J. Dobbin McNatt

1978-01-01

The Forest Products Laboratory manufactured and assessed the performance of 4- by 8-foot structural flakeboard panels from Douglas-fir forest residues after target performance goals were developed. The 42 pcf, three- layer boards were 1/2 inch thick with high quality disk cut flakes for the faces and lower quality flakes processed through a ring flaker in the core....

(How) Does Obesity Harm Academic Performance? Stratification at the Intersection of Race, Sex, and Body Size in Elementary and High School

ERIC Educational Resources Information Center

Branigan, Amelia R.

2017-01-01

In this study I hypothesize a larger penalty of obesity on teacher-assessed academic performance for white girls in English, where femininity is privileged, than in math, where stereotypical femininity is perceived to be a detriment. This pattern of associations would be expected if obesity largely influences academic performance through social…

Reprint of “Performance analysis of a model-sized superconducting DC transmission system based VSC-HVDC transmission technologies using RTDS”

NASA Astrophysics Data System (ADS)

Dinh, Minh-Chau; Ju, Chang-Hyeon; Kim, Sung-Kyu; Kim, Jin-Geun; Park, Minwon; Yu, In-Keun

2013-01-01

The combination of a high temperature superconducting DC power cable and a voltage source converter based HVDC (VSC-HVDC) creates a new option for transmitting power with multiple collection and distribution points for long distance and bulk power transmissions. It offers some greater advantages compared with HVAC or conventional HVDC transmission systems, and it is well suited for the grid integration of renewable energy sources in existing distribution or transmission systems. For this reason, a superconducting DC transmission system based HVDC transmission technologies is planned to be set up in the Jeju power system, Korea. Before applying this system to a real power system on Jeju Island, system analysis should be performed through a real time test. In this paper, a model-sized superconducting VSC-HVDC system, which consists of a small model-sized VSC-HVDC connected to a 2 m YBCO HTS DC model cable, is implemented. The authors have performed the real-time simulation method that incorporates the model-sized superconducting VSC-HVDC system into the simulated Jeju power system using Real Time Digital Simulator (RTDS). The performance analysis of the superconducting VSC-HVDC systems has been verified by the proposed test platform and the results were discussed in detail.

Performance analysis of a model-sized superconducting DC transmission system based VSC-HVDC transmission technologies using RTDS

NASA Astrophysics Data System (ADS)

Dinh, Minh-Chau; Ju, Chang-Hyeon; Kim, Sung-Kyu; Kim, Jin-Geun; Park, Minwon; Yu, In-Keun

2012-08-01

The combination of a high temperature superconducting DC power cable and a voltage source converter based HVDC (VSC-HVDC) creates a new option for transmitting power with multiple collection and distribution points for long distance and bulk power transmissions. It offers some greater advantages compared with HVAC or conventional HVDC transmission systems, and it is well suited for the grid integration of renewable energy sources in existing distribution or transmission systems. For this reason, a superconducting DC transmission system based HVDC transmission technologies is planned to be set up in the Jeju power system, Korea. Before applying this system to a real power system on Jeju Island, system analysis should be performed through a real time test. In this paper, a model-sized superconducting VSC-HVDC system, which consists of a small model-sized VSC-HVDC connected to a 2 m YBCO HTS DC model cable, is implemented. The authors have performed the real-time simulation method that incorporates the model-sized superconducting VSC-HVDC system into the simulated Jeju power system using Real Time Digital Simulator (RTDS). The performance analysis of the superconducting VSC-HVDC systems has been verified by the proposed test platform and the results were discussed in detail.

Macular Ganglion Cell Imaging Study: Covariate Effects on the Spectral Domain Optical Coherence Tomography for Glaucoma Diagnosis

PubMed Central

Jeong, Jae Hoon; Choi, Yun Jeong; Park, Ki Ho; Kim, Dong Myung

2016-01-01

Purpose To evaluate the effect of multiple covariates on the diagnostic performance of the Cirrus high-definition optical coherence tomography (HD-OCT) for glaucoma detection. Methods A prospective case-control study was performed and included 173 recently diagnosed glaucoma patients and 63 unaffected individuals from the Macular Ganglion Cell Imaging Study. Regression analysis of receiver operating characteristic were conducted to evaluate the influence of age, spherical equivalent, axial length, optic disc size, and visual field index on the macular ganglion cell-inner plexiform layer (GCIPL) and peripapillary retinal nerve fiber layer (RNFL) measurements. Results Disease severity, as measured by visual field index, had a significant effect on the diagnostic performance of all Cirrus HD-OCT parameters. Age, axial length and optic disc size were significantly associated with diagnostic accuracy of average peripapillary RNFL thickness, whereas axial length had a significant effect on the diagnostic accuracy of average GCIPL thickness. Conclusions Diagnostic performance of the Cirrus HD-OCT may be more accurate in the advanced stages of glaucoma than at earlier stages. A smaller optic disc size was significantly associated with improved the diagnostic ability of average RNFL thickness measurements; however, GCIPL thickness may be less affected by age and optic disc size. PMID:27490718

Pt nanocatalysts supported on reduced graphene oxide for selective conversion of cellulose or cellobiose to sorbitol.

PubMed

Wang, Ding; Niu, Wenqi; Tan, Minghui; Wu, Mingbo; Zheng, Xuejun; Li, Yanpeng; Tsubaki, Noritatsu

2014-05-01

Pt nanocatalysts loaded on reduced graphene oxide (Pt/RGO) were prepared by means of a convenient microwave-assisted reduction approach with ethylene glycol as reductant. The conversion of cellulose or cellobiose into sorbitol was used as an application reaction to investigate their catalytic performance. Various metal nanocatalysts loaded on RGO were compared and RGO-supported Pt exhibited the highest catalytic activity with 91.5 % of sorbitol yield from cellobiose. The catalytic performances of Pt nanocatalysts supported on different carbon materials or on silica support were also compared. The results showed that RGO was the best catalyst support, and the yield of sorbitol was as high as 91.5 % from cellobiose and 58.9 % from cellulose, respectively. The improvement of catalytic activity was attributed to the appropriate Pt particle size and hydrogen spillover effect of Pt/RGO catalyst. Interestingly, the size and dispersion of supported Pt particles could be easily regulated by convenient adjustment of the microwave heating temperature. The catalytic performance was found to initially increase and then decrease with increasing particle size. The optimum Pt particle size was 3.6 nm. These findings may offer useful guidelines for designing novel catalysts with beneficial catalytic performance for biomass conversion. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Austenitizing Temperature Effects on the Martensitic Transformation, Microstructural Characteristics, and Mechanical Performance of Modified Ferritic Heat-Resistant Steel

NASA Astrophysics Data System (ADS)

Zhou, Xiaosheng; Liu, Yongchang; Liu, Chenxi; Yu, Liming; Li, Huijun

2018-06-01

The martensitic transformation, microstructural characteristics, and mechanical performance of modified ferritic heat-resistant steels under various austenitizing conditions were investigated by differential scanning calorimetry, microstructural examination, and mechanical tests. When the austenitizing temperature was as high as 1200 °C, a considerable amount of δ-ferrite formed, and the austenite grain size was seen to decrease. Higher austenitizing temperatures were found to promote martensite formation, but retard martensite growth, and the lath width increased as the austenitizing temperature increased. After tempering, rod-like and granular M23C6 carbides appeared within the tempered martensite, the average size and composition of which were dependent on the austenitizing conditions. When the austenitizing temperature was 1050 °C, granular MX with sizes less than 6 nm were identified in the δ-ferrite, while for other austenitizing temperatures, plate MX was inside the δ-ferrite. At 1200 °C, the length of the plate MX was as high as 100 nm, and the number density of plate MX decreased. The steel austenitized at 1150 °C exhibited the best tensile performance. It was found that the presence of a large amount of δ-ferrite would initiate cracking, thereby impeding the tensile strength.

High Performance Visualization using Query-Driven Visualizationand Analytics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bethel, E. Wes; Campbell, Scott; Dart, Eli

2006-06-15

Query-driven visualization and analytics is a unique approach for high-performance visualization that offers new capabilities for knowledge discovery and hypothesis testing. The new capabilities akin to finding needles in haystacks are the result of combining technologies from the fields of scientific visualization and scientific data management. This approach is crucial for rapid data analysis and visualization in the petascale regime. This article describes how query-driven visualization is applied to a hero-sized network traffic analysis problem.

Low Voltage, Low Power Organic Light Emitting Transistors for AMOLED Displays

DOE Office of Scientific and Technical Information (OSTI.GOV)

McCarthy, M. A.; Liu, B.; Donoghue, E. P.

2011-01-01

Low voltage, low power dissipation, high aperture ratio organic light emitting transistors are demonstrated. The high level of performance is enabled by a carbon nanotube source electrode that permits integration of the drive transistor and the organic light emitting diode into an efficient single stacked device. Given the demonstrated performance, this technology could break the technical logjam holding back widespread deployment of active matrix organic light emitting displays at flat panel screen sizes.

KENIS: a high-performance thermal imager developed using the OSPREY IR detector

NASA Astrophysics Data System (ADS)

Goss, Tristan M.; Baker, Ian M.

2000-07-01

`KENIS', a complete, high performance, compact and lightweight thermal imager, is built around the `OSPREY' infrared detector from BAE systems Infrared Ltd. The `OSPREY' detector uses a 384 X 288 element CMT array with a 20 micrometers pixel size and cooled to 120 K. The relatively small pixel size results in very compact cryogenics and optics, and the relatively high operating temperature provides fast start-up time, low power consumption and long operating life. Requiring single input supply voltage and consuming less than 30 watts of power, the thermal imager generates both analogue and digital format outputs. The `KENIS' lens assembly features a near diffraction limited dual field-of-view optical system that has been designed to be athermalized and switches between fields in less than one second. The `OSPREY' detector produces near background limited performance with few defects and has special, pixel level circuitry to eliminate crosstalk and blooming effects. This, together with signal processing based on an effective two-point fixed pattern noise correction algorithm, results in high quality imagery and a thermal imager that is suitable for most traditional thermal imaging applications. This paper describes the rationale used in the development of the `KENIS' thermal imager, and highlights the potential performance benefits to the user's system, primarily gained by selecting the `OSPREY' infra-red detector within the core of the thermal imager.

Effects of age, maturity and body dimensions on match running performance in highly trained under-15 soccer players.

PubMed

Buchheit, Martin; Mendez-Villanueva, Alberto

2014-01-01

The aim of the present study was to compare, in 36 highly trained under-15 soccer players, the respective effects of age, maturity and body dimensions on match running performance. Maximal sprinting (MSS) and aerobic speeds were estimated. Match running performance was analysed with GPS (GPSport, 1 Hz) during 19 international friendly games (n = 115 player-files). Total distance and distance covered >16 km h(-1) (D > 16 km h(-1)) were collected. Players advanced in age and/or maturation, or having larger body dimensions presented greater locomotor (Cohen's d for MSS: 0.5-1.0, likely to almost certain) and match running performances (D > 16 km h(-1): 0.2-0.5, possibly to likely) than their younger, less mature and/or smaller teammates. These age-, maturation- and body size-related differences were of larger magnitude for field test measures versus match running performance. Compared with age and body size (unclear to likely), maturation (likely to almost certainly for all match variables) had the greatest impact on match running performance. The magnitude of the relationships between age, maturation and body dimensions and match running performance were position-dependent. Within a single age-group in the present player sample, maturation had a substantial impact on match running performance, especially in attacking players. Coaches may need to consider players' maturity status when assessing their on-field playing performance.

Hot-spot contributions in shocked high explosives from mesoscale ignition models

NASA Astrophysics Data System (ADS)

Levesque, G.; Vitello, P.; Howard, W. M.

2013-06-01

High explosive performance and sensitivity is strongly related to the mesoscale defect densities. Bracketing the population of mesoscale hot spots that are active in the shocked ignition of explosives is important for the development of predictive reactive flow models. By coupling a multiphysics-capable hydrodynamics code (ale3d) with a chemical kinetics solver (cheetah), we can parametrically analyze different pore sizes undergoing collapse in high pressure shock conditions with evolving physical parameter fields. Implementing first-principles based decomposition kinetics, burning hot spots are monitored, and the regimes of pore sizes that contribute significantly to burnt mass faction and those that survive thermal conduction on the time scales of ignition are elucidated. Comparisons are drawn between the thermal explosion theory and the multiphysics models for the determination of nominal pore sizes that burn significantly during ignition for the explosive 1,3,5-triamino-2,4,6-trinitrobenzene.

Performance of an electron gun for a high-brightness X-ray generator

PubMed Central

Sugimura, Takashi; Ohsawa, Satoshi; Ikeda, Mitsuo

2008-01-01

A prototype thermionic electron gun for a high-brightness X-ray generator has been developed. Its extraction voltage and design current are 60 kV and 100 mA (DC), respectively. The X-ray generator aims towards a maximum brilliance of 60 kW mm−2. The beam sizes at the rotating anticathode must therefore be within 1.0 mm × 0.1 mm and a small beam emittance is required. The fabricated electron gun optimizes an aperture grid and a Whenelt electrode. The performance of the prototype electron gun measured using pulsed-beam tests is as follows: maximum beam current, 85.7 mA; beam focus size at the rotating anticathode, 0.79 mm × 0.13 mm. In DC beam tests, FWHM beam sizes were measured to be 0.65 mm × 0.08 mm at the rotating anticathode with a beam current of 45 mA. The beam current recently reached ∼60 mA with some thermal problems. PMID:18421153

Characteristic analysis of diaphragm-type transducer that is thick relative to its size

NASA Astrophysics Data System (ADS)

Ishiguro, Yuya; Zhu, Jing; Tagawa, Norio; Okubo, Tsuyoshi; Okubo, Kan

2017-07-01

In recent years, high-performance piezoelectric micromachined ultrasonic transducers (PMUTs) have been fabricated by micro electro mechanical systems (MEMS) technology. For high-resolution imaging, it is important to broaden the frequency bandwidth. By reducing the diaphragm size to increase the resonance frequency, the film thickness becomes relatively larger and hence the transmitting and receiving characteristics may different from those of a usual thin diaphragm. In this study, we examine the performance of a square-diaphragm-type lead zirconate titanate (PZT) transducer through simulations. To realize the desired resonance frequency of 20 MHz, firstly, the diaphragm size and the thickness of the layers of PZT and Si constituting a PMUT are examined, and then, three PZT/Si models with different thicknesses are selected. Subsequently, using the models, we analyze the transmitting efficiency, transmitting bandwidth, receiving sensitivity (piezoelectric voltage/electric charge), and receiving bandwidth using an FEM simulator. It is found that the proposed models can transmit ultrasound independently of the diaphragm vibration and have wide bandwidth of the receiving frequency as compared with that of a typical PMUT.

Planar-Structure Perovskite Solar Cells with Efficiency beyond 21.

PubMed

Jiang, Qi; Chu, Zema; Wang, Pengyang; Yang, Xiaolei; Liu, Heng; Wang, Ye; Yin, Zhigang; Wu, Jinliang; Zhang, Xingwang; You, Jingbi

2017-12-01

Low temperature solution processed planar-structure perovskite solar cells gain great attention recently, while their power conversions are still lower than that of high temperature mesoporous counterpart. Previous reports are mainly focused on perovskite morphology control and interface engineering to improve performance. Here, this study systematically investigates the effect of precise stoichiometry, especially the PbI 2 contents on device performance including efficiency, hysteresis and stability. This study finds that a moderate residual of PbI 2 can deliver stable and high efficiency of solar cells without hysteresis, while too much residual PbI 2 will lead to serious hysteresis and poor transit stability. Solar cells with the efficiencies of 21.6% in small size (0.0737 cm 2 ) and 20.1% in large size (1 cm 2 ) with moderate residual PbI 2 in perovskite layer are obtained. The certificated efficiency for small size shows the efficiency of 20.9%, which is the highest efficiency ever recorded in planar-structure perovskite solar cells, showing the planar-structure perovskite solar cells are very promising. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ilieva, Yordanka; Allison, Lee; Cao, Tongtong

Here we present preliminary results for the gain performance of commercially available 3- mum and 6- mum pore-size single-anode microchannel-plate photomultipliers (MCP PMTs) in magnetic fields up to 5 T and for various orientations of the sensor relative to the field direction. The measurements were performed at Thomas Jefferson National Accelerator Facility in Newport News, VA. Our results show that smaller-pore-size PMTs have better gain performance in magnetic fields. At various angles, the shape of the gain dependence on the strength of the magnetic field strongly depends on the type of the sensor. Also, for each sensor, the azimuthal dependencemore » is strongly correlated with the polar angle. Overall, the sensors exhibit a reasonable performance up to 2 T, although that upper limit depends on the sensor, the applied high voltage, and the orientation of the sensor relative to the field. To optimize the operational and design parameters of MCP PMTs for performance in high magnetic fields, further measurements and simulation studies will be pursued. Furthermore, our studies are part of an R&D for development of a Detector of Internally Reflected Cherenkov Light for the central detector of a future U.S. Electron Ion Collider.« less

Linear variable narrow bandpass optical filters in the far infrared (Conference Presentation)

NASA Astrophysics Data System (ADS)

Rahmlow, Thomas D.

2017-06-01

We are currently developing linear variable filters (LVF) with very high wavelength gradients. In the visible, these filters have a wavelength gradient of 50 to 100 nm/mm. In the infrared, the wavelength gradient covers the range of 500 to 900 microns/mm. Filter designs include band pass, long pass and ulta-high performance anti-reflection coatings. The active area of the filters is on the order of 5 to 30 mm along the wavelength gradient and up to 30 mm in the orthogonal, constant wavelength direction. Variation in performance along the constant direction is less than 1%. Repeatable performance from filter to filter, absolute placement of the filter relative to a substrate fiducial and, high in-band transmission across the full spectral band is demonstrated. Applications include order sorting filters, direct replacement of the spectrometer and hyper-spectral imaging. Off-band rejection with an optical density of greater than 3 allows use of the filter as an order sorting filter. The linear variable order sorting filters replaces other filter types such as block filters. The disadvantage of block filters is the loss of pixels due to the transition between filter blocks. The LVF is a continuous gradient without a discrete transition between filter wavelength regions. If the LVF is designed as a narrow band pass filter, it can be used in place of a spectrometer thus reducing overall sensor weight and cost while improving the robustness of the sensor. By controlling the orthogonal performance (smile) the LVF can be sized to the dimensions of the detector. When imaging on to a 2 dimensional array and operating the sensor in a push broom configuration, the LVF spectrometer performs as a hyper-spectral imager. This paper presents performance of LVF fabricated in the far infrared on substrates sized to available detectors. The impact of spot size, F-number and filter characterization are presented. Results are also compared to extended visible LVF filters.

Maintenance and supply options

NASA Technical Reports Server (NTRS)

1988-01-01

The object of the Maintenance and Supply Option was to develop a high level operational philosophy related to maintenance and supply operations and incorporate these concepts into the Lunar Base Study. Specific products to be generated during this task were three trade studies and a conceptual design of the Logistic Supply Module. The crew size study was performed to evaluate crew sizes from the baseline size of four to a crew size of eight and determine the preferred crew size. The second trade study was to determine the impact of extending surface stay times and recommend a preferred duration of stay time as a function of crew, consumables, and equipment support capabilities. The third trade study was an evaluation of packaging and storage methods to determine the preferred logistics approach to support the lunar base. A modified scenario was developed and served as the basis of the individual trade studies. Assumptions and guidelines were also developed from experience with Apollo programs, Space Shuttle operations, and Space Station studies. With this information, the trade studies were performed and a conceptual design for the Logistic Supply Module was developed.

Effect of particle size distribution on the hydrodynamics of dense CFB risers

NASA Astrophysics Data System (ADS)

Bakshi, Akhilesh; Khanna, Samir; Venuturumilli, Raj; Altantzis, Christos; Ghoniem, Ahmed

2015-11-01

Circulating Fluidized Beds (CFB) are favorable in the energy and chemical industries, due to their high efficiency. While accurate hydrodynamic modeling is essential for optimizing performance, most CFB riser simulations are performed assuming equally-sized solid particles, owing to limited computational resources. Even though this approach yields reasonable predictions, it neglects commonly observed experimental findings suggesting the strong effect of particle size distribution (psd) on the hydrodynamics and chemical conversion. Thus, this study is focused on the inclusion of discrete particle sizes to represent the psd and its effect on fluidization via 2D numerical simulations. The particle sizes and corresponding mass fluxes are obtained using experimental data in dense CFB riser while the modeling framework is described in Bakshi et al 2015. Simulations are conducted at two scales: (a) fine grid to resolve heterogeneous structures and (b) coarse grid using EMMS sub-grid modifications. Using suitable metrics which capture bed dynamics, this study provides insights into segregation and mixing of particles as well as highlights need for improved sub-grid models.

Conjunction Assessment Screening Volume Sizing and Event Filtering in Light of Natural Conjunction Event Development Behaviors

NASA Technical Reports Server (NTRS)

Hejduk, M. D.; Pachura, D. A.

2017-01-01

Conjunction Assessment screening volumes used in the protection of NASA satellites are constructed as geometric volumes about these satellites, of a size expected to capture a certain percentage of the serious conjunction events by a certain time before closest approach. However, the analyses that established these sizes were grounded on covariance-based projections rather than empirical screening results, did not tailor the volume sizes to ensure operational actionability of those results, and did not consider the adjunct ability to produce data that could provide prevenient assistance for maneuver planning. The present study effort seeks to reconsider these questions based on a six-month dataset of empirical screening results using an extremely large screening volume. The results, pursued here for a highly-populated orbit regime near 700 km altitude, identify theoretical limits of screening volume performance, explore volume configuration to facilitate both maneuver remediation planning as well as basic asset protection, and recommend sizing principles that maximize volume performance while minimizing the capture of "chaff" conjunctions that are unlikely ever to become serious events.

[Size structure, selectivity and specific composition of the catch in traps for marine fish in the Gulf of California].

PubMed

Nevárez-Martínez, Manuel O; Balmori-Ramírez, Alejandro; Miranda-Mier, Everardo; Santos-Molina, J Pablo; Méndez-Tenorio, Francisco J; Cervantes-Valle, Celio

2008-09-01

We analyzed the performance of three traps for marine fish between October 2005 and August 2006 in the Gulf of California, Mexico. The performance was measured as difference in selectivity, fish diversity, size structure and yield. The samples were collected with quadrangular traps 90 cm wide, 120 cm long and 50 cm high. Trap type 1 had a 5 x 5 cm mesh (type 2: 5 x 5 cm including a rear panel of 5 x 10 cm; trap 3: 5 x 10 cm). Most abundant in our traps were: Goldspotted sand bass (Paralabrax auroguttatus), Ocean whitefish (Caulolatilus princeps), Spotted sand bass (P. maculatofaciatus) and Bighead tilefish (C. affinis); there was no bycatch. The number offish per trap per haul decreased when mesh size was increased. We also observed a direct relationship between mesh size and average fish length. By comparing our traps with the authorized fishing gear (hooks-and-line) we found that the size structure is larger in traps. Traps with larger mesh size were more selective. Consequently, we recommend adding traps to hooks-and-line as authorized fishing gear in the small scale fisheries of the Sonora coast, Mexico.

Perspective: Size selected clusters for catalysis and electrochemistry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Halder, Avik; Curtiss, Larry A.; Fortunelli, Alessandro

We report that size-selected clusters containing a handful of atoms may possess noble catalytic properties different from nano-sized or bulk catalysts. Size- and composition-selected clusters can also serve as models of the catalytic active site, where an addition or removal of a single atom can have a dramatic effect on their activity and selectivity. In this Perspective, we provide an overview of studies performed under both ultra-high vacuum and realistic reaction conditions aimed at the interrogation, characterization and understanding of the performance of supported size-selected clusters in heterogeneous and electrochemical reactions, which address the effects of cluster size, cluster composition,more » cluster-support interactions and reaction conditions, the key parameters for the understanding and control of catalyst functionality. Computational modelling based on density functional theory sampling of local minima and energy barriers or ab initio Molecular Dynamics simulations is an integral part of this research by providing fundamental understanding of the catalytic processes at the atomic level, as well as by predicting new materials compositions which can be validated in experiments. Lastly, we discuss approaches which aim at the scale up of the production of well-defined clusters for use in real world applications.« less

Perspective: Size selected clusters for catalysis and electrochemistry

DOE PAGES

Halder, Avik; Curtiss, Larry A.; Fortunelli, Alessandro; ...

2018-03-15

We report that size-selected clusters containing a handful of atoms may possess noble catalytic properties different from nano-sized or bulk catalysts. Size- and composition-selected clusters can also serve as models of the catalytic active site, where an addition or removal of a single atom can have a dramatic effect on their activity and selectivity. In this Perspective, we provide an overview of studies performed under both ultra-high vacuum and realistic reaction conditions aimed at the interrogation, characterization and understanding of the performance of supported size-selected clusters in heterogeneous and electrochemical reactions, which address the effects of cluster size, cluster composition,more » cluster-support interactions and reaction conditions, the key parameters for the understanding and control of catalyst functionality. Computational modelling based on density functional theory sampling of local minima and energy barriers or ab initio Molecular Dynamics simulations is an integral part of this research by providing fundamental understanding of the catalytic processes at the atomic level, as well as by predicting new materials compositions which can be validated in experiments. Lastly, we discuss approaches which aim at the scale up of the production of well-defined clusters for use in real world applications.« less

Perspective: Size selected clusters for catalysis and electrochemistry

NASA Astrophysics Data System (ADS)

Halder, Avik; Curtiss, Larry A.; Fortunelli, Alessandro; Vajda, Stefan

2018-03-01

Size-selected clusters containing a handful of atoms may possess noble catalytic properties different from nano-sized or bulk catalysts. Size- and composition-selected clusters can also serve as models of the catalytic active site, where an addition or removal of a single atom can have a dramatic effect on their activity and selectivity. In this perspective, we provide an overview of studies performed under both ultra-high vacuum and realistic reaction conditions aimed at the interrogation, characterization, and understanding of the performance of supported size-selected clusters in heterogeneous and electrochemical reactions, which address the effects of cluster size, cluster composition, cluster-support interactions, and reaction conditions, the key parameters for the understanding and control of catalyst functionality. Computational modeling based on density functional theory sampling of local minima and energy barriers or ab initio molecular dynamics simulations is an integral part of this research by providing fundamental understanding of the catalytic processes at the atomic level, as well as by predicting new materials compositions which can be validated in experiments. Finally, we discuss approaches which aim at the scale up of the production of well-defined clusters for use in real world applications.

Brayton heat exchange unit development program

NASA Technical Reports Server (NTRS)

Morse, C. J.; Richard, C. E.; Duncan, J. D.

1971-01-01

A Brayton Heat Exchanger Unit (BHXU), consisting of a recuperator, a heat sink heat exchanger and a gas ducting system, was designed, fabricated, and tested. The design was formulated to provide a high performance unit suitable for use in a long-life Brayton-cycle powerplant. A parametric analysis and design study was performed to establish the optimum component configurations to achieve low weight and size and high reliability, while meeting the requirements of high effectiveness and low pressure drop. Layout studies and detailed mechanical and structural design were performed to obtain a flight-type packaging arrangement. Evaluation testing was conducted from which it is estimated that near-design performance can be expected with the use of He-Xe as the working fluid.

Effect of size distribution on magnetic properties in cobalt nanowires

NASA Astrophysics Data System (ADS)

Xu, Huanhuan; Wu, Qiong; Yue, Ming; Li, Chenglin; Li, Hongjian; Palaka, Subhashini

2018-05-01

Cobalt nanowires were synthesized by reduction of carboxylate salts of Co in 1, 2-butanediol using a solvothermal chemical process. These nanowires crystallize with the hcp structure and the growth axis is parallel to the crystallographic c-axis. The morphology of the nanowires that prepared with mechanical stirring during earlier stage of the reaction process exhibits a smaller averaged aspect ratio but narrow size distribution. The assembly of the nanowires that prepared with mechanical stirring shows almost same coercivity and remanent magnetization but 59% increase of magnetic energy product. This remarkable improvement of energy product has been further understood by micromagnetic simulations. The magnetic performance at variant temperatures of Co nanowires has also been presented. These ferromagnetic nanowires could be new ideal building blocks for permanent magnets with high performance and high thermal stability.

High-volume manufacturing device overlay process control

NASA Astrophysics Data System (ADS)

Lee, Honggoo; Han, Sangjun; Woo, Jaeson; Lee, DongYoung; Song, ChangRock; Heo, Hoyoung; Brinster, Irina; Choi, DongSub; Robinson, John C.

2017-03-01

Overlay control based on DI metrology of optical targets has been the primary basis for run-to-run process control for many years. In previous work we described a scenario where optical overlay metrology is performed on metrology targets on a high frequency basis including every lot (or most lots) at DI. SEM based FI metrology is performed ondevice in-die as-etched on an infrequent basis. Hybrid control schemes of this type have been in use for many process nodes. What is new is the relative size of the NZO as compared to the overlay spec, and the need to find more comprehensive solutions to characterize and control the size and variability of NZO at the 1x nm node: sampling, modeling, temporal frequency and control aspects, as well as trade-offs between SEM throughput and accuracy.

High definition in vivo retinal volumetric video rate OCT at 0.6 Giga-voxels per second

NASA Astrophysics Data System (ADS)

Kolb, Jan Philip; Klein, Thomas; Wieser, Wolfgang; Draxinger, Wolfgang; Huber, Robert

2015-07-01

We present full volumetric high speed OCT imaging of the retina with multiple settings varying in volume size and volume rate. The volume size ranges from 255x255 A-scans to 160x40 A-scans with 450 samples per depth scan with volume rates varying between 20.8 V/s for the largest volumes to 195.2 V/s for the smallest. The system is based on a 1060nm Fourier domain mode locked (FDML) laser with 1.6MHz line rate. Scanning along the fast axis is performed with a 2.7 kHz or 4.3 kHz resonant scanner operated in bidirectional scanning mode, while a standard galvo scanner is used for the slow axis. The performance is analyzed with respect to various potential applications, like intraoperative OCT.

Simulation of reaction diffusion processes over biologically relevant size and time scales using multi-GPU workstations

PubMed Central

Hallock, Michael J.; Stone, John E.; Roberts, Elijah; Fry, Corey; Luthey-Schulten, Zaida

2014-01-01

Simulation of in vivo cellular processes with the reaction-diffusion master equation (RDME) is a computationally expensive task. Our previous software enabled simulation of inhomogeneous biochemical systems for small bacteria over long time scales using the MPD-RDME method on a single GPU. Simulations of larger eukaryotic systems exceed the on-board memory capacity of individual GPUs, and long time simulations of modest-sized cells such as yeast are impractical on a single GPU. We present a new multi-GPU parallel implementation of the MPD-RDME method based on a spatial decomposition approach that supports dynamic load balancing for workstations containing GPUs of varying performance and memory capacity. We take advantage of high-performance features of CUDA for peer-to-peer GPU memory transfers and evaluate the performance of our algorithms on state-of-the-art GPU devices. We present parallel e ciency and performance results for simulations using multiple GPUs as system size, particle counts, and number of reactions grow. We also demonstrate multi-GPU performance in simulations of the Min protein system in E. coli. Moreover, our multi-GPU decomposition and load balancing approach can be generalized to other lattice-based problems. PMID:24882911

Simulation of reaction diffusion processes over biologically relevant size and time scales using multi-GPU workstations.

PubMed

Hallock, Michael J; Stone, John E; Roberts, Elijah; Fry, Corey; Luthey-Schulten, Zaida

2014-05-01

Simulation of in vivo cellular processes with the reaction-diffusion master equation (RDME) is a computationally expensive task. Our previous software enabled simulation of inhomogeneous biochemical systems for small bacteria over long time scales using the MPD-RDME method on a single GPU. Simulations of larger eukaryotic systems exceed the on-board memory capacity of individual GPUs, and long time simulations of modest-sized cells such as yeast are impractical on a single GPU. We present a new multi-GPU parallel implementation of the MPD-RDME method based on a spatial decomposition approach that supports dynamic load balancing for workstations containing GPUs of varying performance and memory capacity. We take advantage of high-performance features of CUDA for peer-to-peer GPU memory transfers and evaluate the performance of our algorithms on state-of-the-art GPU devices. We present parallel e ciency and performance results for simulations using multiple GPUs as system size, particle counts, and number of reactions grow. We also demonstrate multi-GPU performance in simulations of the Min protein system in E. coli . Moreover, our multi-GPU decomposition and load balancing approach can be generalized to other lattice-based problems.

Investigating the effect of pixel size of high spatial resolution FTIR imaging for detection of colorectal cancer

NASA Astrophysics Data System (ADS)

Lloyd, G. R.; Nallala, J.; Stone, N.

2016-03-01

FTIR is a well-established technique and there is significant interest in applying this technique to medical diagnostics e.g. to detect cancer. The introduction of focal plane array (FPA) detectors means that FTIR is particularly suited to rapid imaging of biopsy sections as an adjunct to digital pathology. Until recently however each pixel in the image has been limited to a minimum of 5.5 µm which results in a comparatively low magnification image or histology applications and potentially the loss of important diagnostic information. The recent introduction of higher magnification optics gives image pixels that cover approx. 1.1 µm. This reduction in image pixel size gives images of higher magnification and improved spatial detail can be observed. However, the effect of increasing the magnification on spectral quality and the ability to discriminate between disease states is not well studied. In this work we test the discriminatory performance of FTIR imaging using both standard (5.5 µm) and high (1.1 µm) magnification for the detection of colorectal cancer and explore the effect of binning to degrade high resolution images to determine whether similar diagnostic information and performance can be obtained using both magnifications. Results indicate that diagnostic performance using high magnification may be reduced as compared to standard magnification when using existing multivariate approaches. Reduction of the high magnification data to standard magnification via binning can potentially recover some of the lost performance.

Substrate milling pretreatment as a key parameter for Solid-State Anaerobic Digestion optimization.

PubMed

Motte, J-C; Escudié, R; Hamelin, J; Steyer, J-P; Bernet, N; Delgenes, J-P; Dumas, C

2014-12-01

The effect of milling pretreatment on performances of Solid-State Anaerobic Digestion (SS-AD) of raw lignocellulosic residue is still controverted. Three batch reactors treating different straw particle sizes (milled 0.25 mm, 1 mm and 10 mm) were followed during 62 days (6 sampling dates). Although a fine milling improves substrate accessibility and conversion rate (up to 30% compared to coarse milling), it also increases the risk of media acidification because of rapid and high acids production during fermentation of the substrate soluble fraction. Meanwhile, a gradual adaptation of microbial communities, were observed according to both reaction progress and methanogenic performances. The study concluded that particle size reduction affected strongly the performances of the reaction due to an increase of substrate bioaccessibility. An optimization of SS-AD processes thanks to particle size reduction could therefore be applied at farm or industrial scale only if a specific management of the soluble compounds is established. Copyright © 2014 Elsevier Ltd. All rights reserved.

Low cost Ku-band earth terminals for voice/data/facsimile

NASA Technical Reports Server (NTRS)

Kelley, R. L.

1977-01-01

A Ku-band satellite earth terminal capable of providing two way voice/facsimile teleconferencing, 128 Kbps data, telephone, and high-speed imagery services is proposed. Optimized terminal cost and configuration are presented as a function of FDMA and TDMA approaches to multiple access. The entire terminal from the antenna to microphones, speakers and facsimile equipment is considered. Component cost versus performance has been projected as a function of size of the procurement and predicted hardware innovations and production techniques through 1985. The lowest cost combinations of components has been determined in a computer optimization algorithm. The system requirements including terminal EIRP and G/T, satellite size, power per spacecraft transponder, satellite antenna characteristics, and link propagation outage were selected using a computerized system cost/performance optimization algorithm. System cost and terminal cost and performance requirements are presented as a function of the size of a nationwide U.S. network. Service costs are compared with typical conference travel costs to show the viability of the proposed terminal.

High Speed Size Sorting of Subcellular Organelles by Flow Field-Flow Fractionation.

PubMed

Yang, Joon Seon; Lee, Ju Yong; Moon, Myeong Hee

2015-06-16

Separation/isolation of subcellular species, such as mitochondria, lysosomes, peroxisomes, Golgi apparatus, and others, from cells is important for gaining an understanding of the cellular functions performed by specific organelles. This study introduces a high speed, semipreparative scale, biocompatible size sorting method for the isolation of subcellular organelle species from homogenate mixtures of HEK 293T cells using flow field-flow fractionation (FlFFF). Separation of organelles was achieved using asymmetrical FlFFF (AF4) channel system at the steric/hyperlayer mode in which nuclei, lysosomes, mitochondria, and peroxisomes were separated in a decreasing order of hydrodynamic diameter without complicated preprocessing steps. Fractions in which organelles were not clearly separated were reinjected to AF4 for a finer separation using the normal mode, in which smaller sized species can be well fractionated by an increasing order of diameter. The subcellular species contained in collected AF4 fractions were examined with scanning electron microscopy to evaluate their size and morphology, Western blot analysis using organelle specific markers was used for organelle confirmation, and proteomic analysis was performed with nanoflow liquid chromatography-tandem mass spectrometry (nLC-ESI-MS/MS). Since FlFFF operates with biocompatible buffer solutions, it offers great flexibility in handling subcellular components without relying on a high concentration sucrose solution for centrifugation or affinity- or fluorescence tag-based sorting methods. Consequently, the current study provides an alternative, competitive method for the isolation/purification of subcellular organelle species in their intact states.

High-efficiency particulate air filter test stand and aerosol generator for particle loading studies

NASA Astrophysics Data System (ADS)

Arunkumar, R.; Hogancamp, Kristina U.; Parsons, Michael S.; Rogers, Donna M.; Norton, Olin P.; Nagel, Brian A.; Alderman, Steven L.; Waggoner, Charles A.

2007-08-01

This manuscript describes the design, characterization, and operational range of a test stand and high-output aerosol generator developed to evaluate the performance of 30×30×29cm3 nuclear grade high-efficiency particulate air (HEPA) filters under variable, highly controlled conditions. The test stand system is operable at volumetric flow rates ranging from 1.5to12standardm3/min. Relative humidity levels are controllable from 5%-90% and the temperature of the aerosol stream is variable from ambient to 150°C. Test aerosols are produced through spray drying source material solutions that are introduced into a heated stainless steel evaporation chamber through an air-atomizing nozzle. Regulation of the particle size distribution of the aerosol challenge is achieved by varying source solution concentrations and through the use of a postgeneration cyclone. The aerosol generation system is unique in that it facilitates the testing of standard HEPA filters at and beyond rated media velocities by consistently providing, into a nominal flow of 7standardm3/min, high mass concentrations (˜25mg/m3) of dry aerosol streams having count mean diameters centered near the most penetrating particle size for HEPA filters (120-160nm). Aerosol streams that have been generated and characterized include those derived from various concentrations of KCl, NaCl, and sucrose solutions. Additionally, a water insoluble aerosol stream in which the solid component is predominantly iron (III) has been produced. Multiple ports are available on the test stand for making simultaneous aerosol measurements upstream and downstream of the test filter. Types of filter performance related studies that can be performed using this test stand system include filter lifetime studies, filtering efficiency testing, media velocity testing, evaluations under high mass loading and high humidity conditions, and determination of the downstream particle size distributions.

High-efficiency particulate air filter test stand and aerosol generator for particle loading studies.

PubMed

Arunkumar, R; Hogancamp, Kristina U; Parsons, Michael S; Rogers, Donna M; Norton, Olin P; Nagel, Brian A; Alderman, Steven L; Waggoner, Charles A

2007-08-01

This manuscript describes the design, characterization, and operational range of a test stand and high-output aerosol generator developed to evaluate the performance of 30 x 30 x 29 cm(3) nuclear grade high-efficiency particulate air (HEPA) filters under variable, highly controlled conditions. The test stand system is operable at volumetric flow rates ranging from 1.5 to 12 standard m(3)/min. Relative humidity levels are controllable from 5%-90% and the temperature of the aerosol stream is variable from ambient to 150 degrees C. Test aerosols are produced through spray drying source material solutions that are introduced into a heated stainless steel evaporation chamber through an air-atomizing nozzle. Regulation of the particle size distribution of the aerosol challenge is achieved by varying source solution concentrations and through the use of a postgeneration cyclone. The aerosol generation system is unique in that it facilitates the testing of standard HEPA filters at and beyond rated media velocities by consistently providing, into a nominal flow of 7 standard m(3)/min, high mass concentrations (approximately 25 mg/m(3)) of dry aerosol streams having count mean diameters centered near the most penetrating particle size for HEPA filters (120-160 nm). Aerosol streams that have been generated and characterized include those derived from various concentrations of KCl, NaCl, and sucrose solutions. Additionally, a water insoluble aerosol stream in which the solid component is predominantly iron (III) has been produced. Multiple ports are available on the test stand for making simultaneous aerosol measurements upstream and downstream of the test filter. Types of filter performance related studies that can be performed using this test stand system include filter lifetime studies, filtering efficiency testing, media velocity testing, evaluations under high mass loading and high humidity conditions, and determination of the downstream particle size distributions.

Assessment of a membrane drinking water filter in an emergency setting.

PubMed

Ensink, Jeroen H J; Bastable, Andy; Cairncross, Sandy

2015-06-01

The performance and acceptability of the Nerox(TM) membrane drinking water filter were evaluated among an internally displaced population in Pakistan. The membrane filter and a control ceramic candle filter were distributed to over 3,000 households. Following a 6-month period, 230 households were visited and filter performance and use were assessed. Only 6% of the visited households still had a functioning filter, and the removal performance ranged from 80 to 93%. High turbidity in source water (irrigation canals), together with high temperatures and large family size were likely to have contributed to poor performance and uptake of the filters.

Numerical investigation of tip clearance effects on the performance of ducted propeller

NASA Astrophysics Data System (ADS)

Ding, Yongle; Song, Baowei; Wang, Peng

2015-09-01

Tip clearance loss is a limitation of the improvement of turbomachine performance. Previous studies show the Tip clearance loss is generated by the leakage flow through the tip clearance, and is roughly linearly proportional to the gap size. This study investigates the tip clearance effects on the performance of ducted propeller. The investigation was carried out by solving the Navier-Stokes equations with the commercial Computational Fluid Dynamic (CFD) code CFX14.5. These simulations were carried out to determine the underlying mechanisms of the tip clearance effects. The calculations were performed at three different chosen advance ratios. Simulation results showed that the tip loss slope was not linearly at high advance due to the reversed pressure at the leading edge. Three type of vortical structures were observed in the tip clearance at different clearance size.

Evaluation and comparison of statistical methods for early temporal detection of outbreaks: A simulation-based study

PubMed Central

Le Strat, Yann

2017-01-01

The objective of this paper is to evaluate a panel of statistical algorithms for temporal outbreak detection. Based on a large dataset of simulated weekly surveillance time series, we performed a systematic assessment of 21 statistical algorithms, 19 implemented in the R package surveillance and two other methods. We estimated false positive rate (FPR), probability of detection (POD), probability of detection during the first week, sensitivity, specificity, negative and positive predictive values and F1-measure for each detection method. Then, to identify the factors associated with these performance measures, we ran multivariate Poisson regression models adjusted for the characteristics of the simulated time series (trend, seasonality, dispersion, outbreak sizes, etc.). The FPR ranged from 0.7% to 59.9% and the POD from 43.3% to 88.7%. Some methods had a very high specificity, up to 99.4%, but a low sensitivity. Methods with a high sensitivity (up to 79.5%) had a low specificity. All methods had a high negative predictive value, over 94%, while positive predictive values ranged from 6.5% to 68.4%. Multivariate Poisson regression models showed that performance measures were strongly influenced by the characteristics of time series. Past or current outbreak size and duration strongly influenced detection performances. PMID:28715489

Performance analysis and kernel size study of the Lynx real-time operating system

NASA Technical Reports Server (NTRS)

Liu, Yuan-Kwei; Gibson, James S.; Fernquist, Alan R.

1993-01-01

This paper analyzes the Lynx real-time operating system (LynxOS), which has been selected as the operating system for the Space Station Freedom Data Management System (DMS). The features of LynxOS are compared to other Unix-based operating system (OS). The tools for measuring the performance of LynxOS, which include a high-speed digital timer/counter board, a device driver program, and an application program, are analyzed. The timings for interrupt response, process creation and deletion, threads, semaphores, shared memory, and signals are measured. The memory size of the DMS Embedded Data Processor (EDP) is limited. Besides, virtual memory is not suitable for real-time applications because page swap timing may not be deterministic. Therefore, the DMS software, including LynxOS, has to fit in the main memory of an EDP. To reduce the LynxOS kernel size, the following steps are taken: analyzing the factors that influence the kernel size; identifying the modules of LynxOS that may not be needed in an EDP; adjusting the system parameters of LynxOS; reconfiguring the device drivers used in the LynxOS; and analyzing the symbol table. The reductions in kernel disk size, kernel memory size and total kernel size reduction from each step mentioned above are listed and analyzed.

Regulating Surface Facets of Metallic Aerogel Electrocatalysts by Size-dependent Localized Ostwald Ripening.

PubMed

Wenchao, Duan; Zhang, Peina; Xiahou, Yujiao; Song, Yahui; Bi, Cuixia; Zhan, Jie; Du, Wei; Huang, Lihui; Möhwald, Helmuth; Xia, Haibing

2018-06-21

It is well known that the activity and stability of electrocatalysts are largely dependent on their surface facets. In this work, we have successfully regulated surface facets of three-dimensional (3D) metallic Au m-n aerogels by salt-induced assembly of citrate-stabilized gold nanoparticles (Au NPs) of two different sizes and further size-dependent localized Ostwald ripening at controlled particle-number ratios, where m and n represent the size of Au NPs, respectively. In addition, 3D Au m-n @Pd aerogels were further synthesized on the basis of Au m-n aerogels and also bear controlled surface facets due to the formation of ultrathin Pd layers on Au m-n aerogels. Taking the electrooxidation of small organic molecules (such as methanol and ethanol) by the resulting Au m-n and Au m-n @Pd aerogels as examples, it is found that surface facets of metallic aerogels with excellent performance can be regulated to realize preferential surface facets for methanol oxidation and ethanol oxidation, respectively. Moreover, they also indeed simultaneously bear high activity and excellent stability. Furthermore, their activities and stability are also highly dependent on the area ratio of active facets and inactive facets on their surfaces, respectively, and these ratios are varied via the mismatch of sizes of adjacent nanoparticles. Thus, this work not only demonstrates the realization of the regulation of the surface facets of metallic aerogels by size-dependent localized Ostwald ripening, but also will open up a new way to improve electrocatalytic performance of three-dimensional metallic aerogels by surface regulation.

Analysis of point source size on measurement accuracy of lateral point-spread function of confocal Raman microscopy

NASA Astrophysics Data System (ADS)

Fu, Shihang; Zhang, Li; Hu, Yao; Ding, Xiang

2018-01-01

Confocal Raman Microscopy (CRM) has matured to become one of the most powerful instruments in analytical science because of its molecular sensitivity and high spatial resolution. Compared with conventional Raman Microscopy, CRM can perform three dimensions mapping of tiny samples and has the advantage of high spatial resolution thanking to the unique pinhole. With the wide application of the instrument, there is a growing requirement for the evaluation of the imaging performance of the system. Point-spread function (PSF) is an important approach to the evaluation of imaging capability of an optical instrument. Among a variety of measurement methods of PSF, the point source method has been widely used because it is easy to operate and the measurement results are approximate to the true PSF. In the point source method, the point source size has a significant impact on the final measurement accuracy. In this paper, the influence of the point source sizes on the measurement accuracy of PSF is analyzed and verified experimentally. A theoretical model of the lateral PSF for CRM is established and the effect of point source size on full-width at half maximum of lateral PSF is simulated. For long-term preservation and measurement convenience, PSF measurement phantom using polydimethylsiloxane resin, doped with different sizes of polystyrene microspheres is designed. The PSF of CRM with different sizes of microspheres are measured and the results are compared with the simulation results. The results provide a guide for measuring the PSF of the CRM.

HAIC/HIWC field campaign - investigating ice microphysics in high ice water content regions of mesoscale convective systems

NASA Astrophysics Data System (ADS)

Leroy, Delphine; Fontaine, Emmanuel; Schwarzenboeck, Alfons; Strapp, J. Walter; Lilie, Lyle; Dezitter, Fabien; Grandin, Alice

2015-04-01

Despite existing research programs focusing on tropical convection, high ice water content (IWC) regions in Mesoscale Convective Systems (MCS) - potentially encountered by commercial aircraft and related to reported in-service events - remain poorly documented either because investigation of such high IWC regions was not of highest priority or because utilized instrumentation was not capable of providing accurate cloud microphysical measurements. To gather quantitative data in high IWC regions, a multi-year international HAIC/HIWC (High Altitude Ice Crystals / High Ice Water Content) field project has been designed including a first field campaign conducted out of Darwin (Australia) in 2014. The French Falcon 20 research aircraft had been equipped among others with a state-of-the-art in situ microphysics package including the IKP (isokinetic evaporator probe which provides a reference measurement of IWC and TWC), the CDP (cloud droplet spectrometer probe measuring particles in the range 2-50 µm), the 2D-S (2D-Stereo, 10-1280 µm) and PIP (precipitation imaging probe, 100-6400 µm) optical array probes. Microphysical data collection has been performed mainly at -40°C and -30°C levels, whereas little data could be sampled at -50°C and at -15C/-10°C. The study presented here focuses on ice crystal size properties, thereby analyzing in detail the 2D image data from 2D-S and PIP optical array imaging probes. 2D images recorded with 2D-S and PIP were processed in order to extract a large variety of geometrical parameters, such as maximum diameter (Dmax), 2D surface equivalent diameter (Deq), and the corresponding number particle size distribution (PSD). Using the PSD information from both probes, a composite size distribution was then built, with sizes ranging from few tens of µm to roughly 10 mm. Finally, mass-size relationships for ice crystals in tropical convection were established in terms of power laws in order to compute median mass diameters MMDmax and MMDeq. The preliminary analysis of all HAIC/HIWC flights, performed during the first flight campaign out of Darwin, demonstrate that various flights include high IWC regions mostly produced by high concentrations of small crystals while other flights with similar peak IWCs show high IWC regions nevertheless composed of primarily larger particles. This interesting result indicates that high IWC can be produced and or maintained in various environments, preferentially high concentrations of small crystals, however sometimes by smaller concentrations of larger sized crystal populations. These variations in crystal sizes producing comparable high IWC values are reflected by respective variations in MMDmax and MMDeq. Acknowledgements: The research leading to these results has received funding from the European Union's Seventh Framework Program in research, technological development and demonstration under grant agreement n°ACP2-GA-2012-314314. The research leading to these results has received funding from the European Aviation Safety Agency Research Program under service contract n° EASA.2013.FC27.

Bioinformatics analysis of disordered proteins in prokaryotes.

PubMed

Pavlović-Lažetić, Gordana M; Mitić, Nenad S; Kovačević, Jovana J; Obradović, Zoran; Malkov, Saša N; Beljanski, Miloš V

2011-03-02

A significant number of proteins have been shown to be intrinsically disordered, meaning that they lack a fixed 3 D structure or contain regions that do not posses a well defined 3 D structure. It has also been proven that a protein's disorder content is related to its function. We have performed an exhaustive analysis and comparison of the disorder content of proteins from prokaryotic organisms (i.e., superkingdoms Archaea and Bacteria) with respect to functional categories they belong to, i.e., Clusters of Orthologous Groups of proteins (COGs) and groups of COGs-Cellular processes (Cp), Information storage and processing (Isp), Metabolism (Me) and Poorly characterized (Pc). We also analyzed the disorder content of proteins with respect to various genomic, metabolic and ecological characteristics of the organism they belong to. We used correlations and association rule mining in order to identify the most confident associations between specific modalities of the characteristics considered and disorder content. Bacteria are shown to have a somewhat higher level of protein disorder than archaea, except for proteins in the Me functional group. It is demonstrated that the Isp and Cp functional groups in particular (L-repair function and N-cell motility and secretion COGs of proteins in specific) possess the highest disorder content, while Me proteins, in general, posses the lowest. Disorder fractions have been confirmed to have the lowest level for the so-called order-promoting amino acids and the highest level for the so-called disorder promoters. For each pair of organism characteristics, specific modalities are identified with the maximum disorder proteins in the corresponding organisms, e.g., high genome size-high GC content organisms, facultative anaerobic-low GC content organisms, aerobic-high genome size organisms, etc. Maximum disorder in archaea is observed for high GC content-low genome size organisms, high GC content-facultative anaerobic or aquatic or mesophilic organisms, etc. Maximum disorder in bacteria is observed for high GC content-high genome size organisms, high genome size-aerobic organisms, etc. Some of the most reliable association rules mined establish relationships between high GC content and high protein disorder, medium GC content and both medium and low protein disorder, anaerobic organisms and medium protein disorder, Gammaproteobacteria and low protein disorder, etc. A web site Prokaryote Disorder Database has been designed and implemented at the address http://bioinfo.matf.bg.ac.rs/disorder, which contains complete results of the analysis of protein disorder performed for 296 prokaryotic completely sequenced genomes. Exhaustive disorder analysis has been performed by functional classes of proteins, for a larger dataset of prokaryotic organisms than previously done. Results obtained are well correlated to those previously published, with some extension in the range of disorder level and clear distinction between functional classes of proteins. Wide correlation and association analysis between protein disorder and genomic and ecological characteristics has been performed for the first time. The results obtained give insight into multi-relationships among the characteristics and protein disorder. Such analysis provides for better understanding of the evolutionary process and may be useful for taxon determination. The main drawback of the approach is the fact that the disorder considered has been predicted and not experimentally established.

Large-size porous ZnO flakes with superior gas-sensing performance

NASA Astrophysics Data System (ADS)

Wen, Wei; Wu, Jin-Ming; Wang, Yu-De

2012-06-01

A simple top-down route is developed to fabricate large size porous ZnO flakes via solution combustion synthesis followed by a subsequent calcination in air, which is template-free and can be easily enlarged to an industrial scale. The achieved porous ZnO flakes, which are tens to hundreds of micrometers in flat and tens of nanometers in thickness, exhibit high response for detecting acetone and ethanol, because the unique two-dimensional architecture shortens effectively the gas diffusion distance and provides highly accessible open channels and active surfaces for the target gas.

Fully Integrated, Miniature, High-Frequency Flow Probe Utilizing MEMS Leadless SOI Technology

NASA Technical Reports Server (NTRS)

Ned, Alex; Kurtz, Anthony; Shang, Tonghuo; Goodman, Scott; Giemette. Gera (d)

2013-01-01

This work focused on developing, fabricating, and fully calibrating a flowangle probe for aeronautics research by utilizing the latest microelectromechanical systems (MEMS), leadless silicon on insulator (SOI) sensor technology. While the concept of angle probes is not new, traditional devices had been relatively large due to fabrication constraints; often too large to resolve flow structures necessary for modern aeropropulsion measurements such as inlet flow distortions and vortices, secondary flows, etc. Mea surements of this kind demanded a new approach to probe design to achieve sizes on the order of 0.1 in. (.3 mm) diameter or smaller, and capable of meeting demanding requirements for accuracy and ruggedness. This approach invoked the use of stateof- the-art processing techniques to install SOI sensor chips directly onto the probe body, thus eliminating redundancy in sensor packaging and probe installation that have historically forced larger probe size. This also facilitated a better thermal match between the chip and its mount, improving stability and accuracy. Further, the leadless sensor technology with which the SOI sensing element is fabricated allows direct mounting and electrical interconnecting of the sensor to the probe body. This leadless technology allowed a rugged wire-out approach that is performed at the sensor length scale, thus achieving substantial sensor size reductions. The technology is inherently capable of high-frequency and high-accuracy performance in high temperatures and harsh environments.

Isolation and purification of monosialotetrahexosylgangliosides from pig brain by extraction and liquid chromatography.

PubMed

Bian, Liujiao; Yang, Jianting; Sun, Yu

2015-10-01

Monosialotetrahexosylganglioside (GM1), one of glycosphingolipids containing sialic acid, plays particularly important role in fighting against paralysis, dementia and other diseases caused by brain and nerve damage. In this work, a simple and highly efficient method with high yield was developed for isolation and purification of GM1 from pig brain. The method consisted of an extraction by chloroform-methanol-water and a two-step chromatographic separation by DEAE-Sepharose Fast Flow anion-exchange medium and Sephacryl S-100 HR size-exclusion medium. The purified GM1 was proved to be homogeneous and had a purity of >98.0% by high-performance anion-exchange and size-exclusion chromatography. The molecular weight was 30.0 kDa by high-performance size-exclusion chromatography and 1546.9 Da by electrospray ionization mass spectrometry. The chromogenic reaction by resorcinol-hydrochloric acid solution indicated that the purified GM1 showed a specific chromogenic reaction of sialic acid. Through this isolation and purification program, ~1.0 mg of pure GM1 could be captured from 500 g wet pig brain tissue and the yield of GM1 was around 0.022%, which was higher than the yields by other methods. The method may provide an alternative for isolation and purification of GM1 in other biological tissues. Copyright © 2015 John Wiley & Sons, Ltd.

Modeling and evaluation of a high-resolution CMOS detector for cone-beam CT of the extremities.

PubMed

Cao, Qian; Sisniega, Alejandro; Brehler, Michael; Stayman, J Webster; Yorkston, John; Siewerdsen, Jeffrey H; Zbijewski, Wojciech

2018-01-01

Quantitative assessment of trabecular bone microarchitecture in extremity cone-beam CT (CBCT) would benefit from the high spatial resolution, low electronic noise, and fast scan time provided by complementary metal-oxide semiconductor (CMOS) x-ray detectors. We investigate the performance of CMOS sensors in extremity CBCT, in particular with respect to potential advantages of thin (<0.7 mm) scintillators offering higher spatial resolution. A cascaded systems model of a CMOS x-ray detector incorporating the effects of CsI:Tl scintillator thickness was developed. Simulation studies were performed using nominal extremity CBCT acquisition protocols (90 kVp, 0.126 mAs/projection). A range of scintillator thickness (0.35-0.75 mm), pixel size (0.05-0.4 mm), focal spot size (0.05-0.7 mm), magnification (1.1-2.1), and dose (15-40 mGy) was considered. The detectability index was evaluated for both CMOS and a-Si:H flat-panel detector (FPD) configurations for a range of imaging tasks emphasizing spatial frequencies associated with feature size aobj. Experimental validation was performed on a CBCT test bench in the geometry of a compact orthopedic CBCT system (SAD = 43.1 cm, SDD = 56.0 cm, matching that of the Carestream OnSight 3D system). The test-bench studies involved a 0.3 mm focal spot x-ray source and two CMOS detectors (Dalsa Xineos-3030HR, 0.099 mm pixel pitch) - one with the standard CsI:Tl thickness of 0.7 mm (C700) and one with a custom 0.4 mm thick scintillator (C400). Measurements of modulation transfer function (MTF), detective quantum efficiency (DQE), and CBCT scans of a cadaveric knee (15 mGy) were obtained for each detector. Optimal detectability for high-frequency tasks (feature size of ~0.06 mm, consistent with the size of trabeculae) was ~4× for the C700 CMOS detector compared to the a-Si:H FPD at nominal system geometry of extremity CBCT. This is due to ~5× lower electronic noise of a CMOS sensor, which enables input quantum-limited imaging at smaller pixel size. Optimal pixel size for high-frequency tasks was <0.1 mm for a CMOS, compared to ~0.14 mm for an a-Si:H FPD. For this fine pixel pitch, detectability of fine features could be improved by using a thinner scintillator to reduce light spread blur. A 22% increase in detectability of 0.06 mm features was found for the C400 configuration compared to C700. An improvement in the frequency at 50% modulation (f 50 ) of MTF was measured, increasing from 1.8 lp/mm for C700 to 2.5 lp/mm for C400. The C400 configuration also achieved equivalent or better DQE as C700 for frequencies above ~2 mm -1 . Images of cadaver specimens confirmed improved visualization of trabeculae with the C400 sensor. The small pixel size of CMOS detectors yields improved performance in high-resolution extremity CBCT compared to a-Si:H FPDs, particularly when coupled with a custom 0.4 mm thick scintillator. The results indicate that adoption of a CMOS detector in extremity CBCT can benefit applications in quantitative imaging of trabecular microstructure in humans. © 2017 American Association of Physicists in Medicine.

Molecular size and molecular size distribution affecting traditional balsamic vinegar aging.

PubMed

Falcone, Pasquale Massimiliano; Giudici, Paolo

2008-08-27

A first attempt at a semiquantitative study of molecular weight (MW) and molecular weight distribution (MWD) in cooked grape must and traditional balsamic vinegar (TBV) with increasing well-defined age was performed by high-performance liquid size exclusion chromatography (SEC) using dual detection, that is, differential refractive index (DRI) and absorbance (UV-vis) based detectors. With this aim, MW and MWD, including number- and weight-average MW and polydispersity, were determined with respect to a secondary standard and then analyzed. All investigated vinegar samples were recognized as compositionally and structurally heterogeneous blends of copolymers (melanoidins) spreading over a wide range of molecular sizes: the relative MW ranged from 2 to >2000 kDa. The extent of the polymerization reactions was in agreement with the TBV browning kinetics. MWD parameters varied asymptotically toward either upper or lower limits during aging, reflecting a nonequilibrium status of the balance between polymerization and depolymerization reactions in TBV. MWD parameters were proposed as potential aging markers of TBV.

[Association between productivity, list size, patient and practice characteristics in general practice].

PubMed

Olsen, Kim Rose; Sørensen, Torben Højmark; Gyrd-Hansen, Dorte

2010-04-19

Due to shortage of general practitioners, it may be necessary to improve productivity. We assess the association between productivity, list size and patient- and practice characteristics. A regression approach is used to perform productivity analysis based on national register data and survey data for 1,758 practices. Practices are divided into four groups according to list size and productivity. Statistical tests are used to assess differences in patient- and practice characteristics. There is a significant, positive correlation between list size and productivity (p < 0.01). Nevertheless, 19% of the practices have a list size below and a productivity above mean sample values. These practices have relatively demanding patients (older, low socioeconomic status, high use of pharmaceuticals) and they are frequently located in areas with limited access to specialized care and have a low use of assisting personnel. 13% of the practices have a list size above and a productivity below mean sample values. These practices have relatively less demanding patients, are located in areas with good access to specialized care, and have a high use of assisting personnel. Lists and practice characteristics have substantial influence on both productivity and list size. Adjusting list size to external factors seems to be an effective tool to increase productivity in general practice.

Fracturing mechanics before valve-in-valve therapy of small aortic bioprosthetic heart valves.

PubMed

Johansen, Peter; Engholt, Henrik; Tang, Mariann; Nybo, Rasmus F; Rasmussen, Per D; Nielsen-Kudsk, Jens Erik

2017-10-13

Patients with degraded bioprosthetic heart valves (BHV) who are not candidates for valve replacement may benefit from transcatheter valve-in-valve (VIV) therapy. However, in smaller-sized surgical BHV the resultant orifice may become too narrow. To overcome this, the valve frame can be fractured by a high-pressure balloon prior to VIV. However, knowledge on fracture pressures and mechanics are prerequisites. The aim of this study was to identify the fracture pressures needed in BHV, and to describe the fracture mechanics. Commonly used BHV of small sizes were mounted on a high-pressure balloon situated in a biplane fluoroscopic system with a high-speed camera. The instant of fracture was captured along with the balloon pressure. The valves were inspected for material protrusion and later dissected for fracture zone investigation and description. The valves with a polymer frame fractured at a lower pressure (8-10 atm) than those with a metal stent (19-26 atm). None of the fractured valves had elements protruding. VIV procedures in small-sized BHV may be performed after prior fracture of the valve frame by high-pressure balloon dilatation. This study provides tentative guidelines for expected balloon sizes and pressures for valve fracturing.

Mesoporous carbon synthesized from different pore sizes of SBA-15 for high density electrode supercapacitor application

NASA Astrophysics Data System (ADS)

Jamil, Farinaa Md; Sulaiman, Mohd Ali; Ibrahim, Suhaina Mohd; Masrom, Abdul Kadir; Yahya, Muhd Zu Azhan

2017-12-01

A series of mesoporous carbon sample was synthesized using silica template, SBA-15 with two different pore sizes. Impregnation method was applied using glucose as a precursor for converting it into carbon. An appropriate carbonization and silica removal process were carried out to produce a series of mesoporous carbon with different pore sizes and surface areas. Mesoporous carbon sample was then assembled as electrode and its performance was tested using cyclic voltammetry and impedance spectroscopy to study the effect of ion transportation into several pore sizes on electric double layer capacitor (EDLC) system. 6M KOH was used as electrolyte at various scan rates of 10, 20, 30 and 50 mVs-1. The results showed that the pore size of carbon increased as the pore size of template increased and the specific capacitance improved as the increasing of the pore size of carbon.

Microwave ablation versus radiofrequency ablation in the kidney: high-power triaxial antennas create larger ablation zones than similarly sized internally cooled electrodes.

PubMed

Laeseke, Paul F; Lee, Fred T; Sampson, Lisa A; van der Weide, Daniel W; Brace, Christopher L

2009-09-01

To determine whether microwave ablation with high-power triaxial antennas creates significantly larger ablation zones than radiofrequency (RF) ablation with similarly sized internally cooled electrodes. Twenty-eight 12-minute ablations were performed in an in vivo porcine kidney model. RF ablations were performed with a 200-W pulsed generator and either a single 17-gauge cooled electrode (n = 9) or three switched electrodes spaced 1.5 cm apart (n = 7). Microwave ablations were performed with one (n = 7), two (n = 3), or three (n = 2) 17-gauge triaxial antennas to deliver 90 W continuous power per antenna. Multiple antennas were powered simultaneously. Temperatures 1 cm from the applicator were measured during two RF and microwave ablations each. Animals were euthanized after ablation and ablation zone diameter, cross-sectional area, and circularity were measured. Comparisons between groups were performed with use of a mixed-effects model with P values less than .05 indicating statistical significance. No adverse events occurred during the procedures. Three-electrode RF (mean area, 14.7 cm(2)) and single-antenna microwave (mean area, 10.9 cm(2)) ablation zones were significantly larger than single-electrode RF zones (mean area, 5.6 cm(2); P = .001 and P = .0355, respectively). No significant differences were detected between single-antenna microwave and multiple-electrode RF. Ablation zone circularity was similar across groups (P > .05). Tissue temperatures were higher during microwave ablation (maximum temperature of 123 degrees C vs 100 degrees C for RF). Microwave ablation with high-power triaxial antennas created larger ablation zones in normal porcine kidneys than RF ablation with similarly sized applicators.

Challenges in analysis of high-molar mass dextrans: comparison of HPSEC, AsFlFFF and DOSY NMR spectroscopy.

PubMed

Maina, Ndegwa Henry; Pitkänen, Leena; Heikkinen, Sami; Tuomainen, Päivi; Virkki, Liisa; Tenkanen, Maija

2014-01-01

Dilute solutions of various dextran standards, a high-molar mass (HMM) commercial dextran from Leuconostoc spp., and HMM dextrans isolated from Weissella confusa and Leuconostoc citreum were analyzed with high-performance size-exclusion chromatography (HPSEC), asymmetric flow field-flow fractionation (AsFlFFF), and diffusion-ordered NMR spectroscopy (DOSY). HPSEC analyses were performed in aqueous and dimethyl sulfoxide (DMSO) solutions, while only aqueous solutions were utilized in AsFlFFF and DOSY. The study showed that all methods were applicable to dextran analysis, but differences between the aqueous and DMSO-based solutions were obtained for HMM samples. These differences were attributed to the presence of aggregates in aqueous solution that were less prevalent in DMSO. The study showed that DOSY provides an estimate of the size of HMM dextrans, though calibration standards may be required for each experimental set-up. To our knowledge, this is the first study utilizing these three methods in analyzing HMM dextrans. Copyright © 2013 Elsevier Ltd. All rights reserved.

The relationship between surface tension and the industrial performance of water-soluble polymers prepared from acid hydrolysis lignin, a saccharification by-product from woody materials.

PubMed

Matsushita, Yasuyuki; Imai, Masanori; Iwatsuki, Ayuko; Fukushima, Kazuhiko

2008-05-01

In this study, water-soluble anionic and cationic polymers were prepared from sulfuric acid lignin (SAL), an acid hydrolysis lignin, and the relationship between the surface tension of these polymers and industrial performance was examined. The SAL was phenolized (P-SAL) to enhance its solubility and reactivity. Sulfonation and the Mannich reaction with aminocarboxylic acids produced water-soluble anionic polymers and high-dispersibility gypsum paste. The dispersing efficiency increased as the surface tension decreased, suggesting that the fluidity of the gypsum paste increased with the polymer adsorption on the gypsum particle surface. Water-soluble cationic polymers were prepared using the Mannich reaction with dimethylamine. The cationic polymers showed high sizing efficiency under neutral papermaking conditions; the sizing efficiency increased with the surface tension. This suggests that the polymer with high hydrophilicity spread in the water and readily adhered to the pulp surface and the rosin, showing good retention.

The influence of high heat input and inclusions control for rare earth on welding in low alloy high strength steel

NASA Astrophysics Data System (ADS)

Chu, Rensheng; Mu, Shukun; Liu, Jingang; Li, Zhanjun

2017-09-01

In the current paper, it is analyzed for the influence of high heat input and inclusions control for rare earth on welding in low alloy high strength steel. It is observed for the structure for different heat input of the coarse-grained area. It is finest for the coarse grain with the high heat input of 200 kJ / cm and the coarse grain area with 400 kJ / cm is the largest. The performance with the heat input of 200 kJ / cm for -20 °C V-shaped notch oscillatory power is better than the heat input of 400 kJ / cm. The grain structure is the ferrite and bainite for different holding time. The grain structure for 5s holding time has a grain size of 82.9 μm with heat input of 200 kJ/cm and grain size of 97.9 μm for 10s holding time. For the inclusions for HSLA steel with adding rare earth, they are Al2O3-CaS inclusions in the Al2O3-CaS-CaO ternary phase diagram. At the same time, it can not be found for low melting calcium aluminate inclusions compared to the inclusions for the HSLA steel without rare earth. Most of the size for the inclusions is between 1 ~ 10μm. The overall grain structure is smaller and the welding performance is more excellent for adding rare earth.

High-performance Li-ion Sn anodes with enhanced electrochemical properties using highly conductive TiN nanotubes array as a 3D multifunctional support

NASA Astrophysics Data System (ADS)

Pu, Jun; Du, Hongxiu; Wang, Jian; Wu, Wenlu; Shen, Zihan; Liu, Jinyun; Zhang, Huigang

2017-08-01

High capacity electrodes are demanded to increase the energy and power density of lithium ion batteries. However, the cycling and rate properties are severely affected by the large volume changes caused by the lithium insertion and extraction. Structured electrodes with mechanically stable scaffolds are widely developed to mitigate the adverse effects of volume changes. Tin, as a promising anode material, receives great attentions because of its high theoretic capacity. There is a critical value of tin particle size above which tin anodes readily crack, leading to low cyclability. The electrode design using mechanical scaffolds must retain tin particles below the critical size and concurrently enable high volumetric capacity. It is a challenge to guarantee the critical size for high cyclability and space utilization for high volumetric capacity. This study provides a highly conductive TiN nanotubes array with submicron diameters, which enable thin tin coating without sacrificing the volumetric capacity. Such a structured electrode delivers a capacity of 795 mAh gSn-1 (Sn basis) and 1812 mAh cmel-3 (electrode basis). The long-term cycling shows only 0.04% capacity decay per cycle.

MOSFET detectors in quality assurance of tomotherapy treatments.

PubMed

Cherpak, Amanda; Studinski, Ryan C N; Cygler, Joanna E

2008-02-01

The purpose of this work was to characterize metal oxide semiconductor field-effect transistors (MOSFETs) in a 6 MV conventional linac and investigate their use for quality assurance of radiotherapy treatments with a tomotherapy Hi-Art unit. High sensitivity and standard sensitivity MOSFETs were first calibrated and then tested for reproducibility, field size dependence, and accuracy of measuring surface dose in a 6 MV beam as well as in a tomotherapy Hi-Art unit. In vivo measurements were performed on both a RANDO phantom and several head and neck cancer patients treated with tomotherapy and compared to TLD measurements and treatment plan doses to evaluate the performance of MOSFETs in a high gradient radiation field. The average calibration factor found was 0.345+/-2.5%cGy/mV for the high sensitivity MOSFETs tested and 0.901+/-2.4%cGy/mV for the standard sensitivity MOSFETs. MOSFET measured surface doses had an average agreement with ion chamber measurements of 1.55% for the high sensitivity MOSFET and 5.23% for the standard sensitivity MOSFET when averaged over all trials and field sizes tested. No significant dependence on field size was found for the standard sensitivity MOSFETs, however a maximum difference of 5.34% was found for the high sensitivity MOSFET calibration factors in the field sizes tested. Measurements made with MOSFETS on head and neck patients treated on a tomotherapy Hi-Art unit had an average agreement of (3.26+/-0.03)% with TLD measurements, however the average of the absolute difference between the MOSFET measurements and the treatment plan skin doses was (12.2+/-7.5)%. The MOSFET measured patient skin doses also had good reproducibility, with inter-fraction deviations ranging from 1.4% to 6.6%. Similar results were found from trials using a RANDO phantom. The MOSFETs performed well when used in the tomotherapy Hi-Art unit and did not increase the overall treatment set-up time when used for patient measurements. It was found that MOSFETs are suitable detectors for surface dose measurements in both conventional beam and tomotherapy treatments and they can provide valuable skin dose information in areas where the treatment planning system may not be accurate.

Point of impact: the effect of size and speed on puncture mechanics

PubMed Central

Anderson, P. S. L.; LaCosse, J.; Pankow, M.

2016-01-01

The use of high-speed puncture mechanics for prey capture has been documented across a wide range of organisms, including vertebrates, arthropods, molluscs and cnidarians. These examples span four phyla and seven orders of magnitude difference in size. The commonality of these puncture systems offers an opportunity to explore how organisms at different scales and with different materials, morphologies and kinematics perform the same basic function. However, there is currently no framework for combining kinematic performance with cutting mechanics in biological puncture systems. Our aim here is to establish this framework by examining the effects of size and velocity in a series of controlled ballistic puncture experiments. Arrows of identical shape but varying in mass and speed were shot into cubes of ballistic gelatine. Results from high-speed videography show that projectile velocity can alter how the target gel responds to cutting. Mixed models comparing kinematic variables and puncture patterns indicate that the kinetic energy of a projectile is a better predictor of penetration than either momentum or velocity. These results form a foundation for studying the effects of impact on biological puncture, opening the door for future work to explore the influence of morphology and material organization on high-speed cutting dynamics. PMID:27274801

Online virtual isocenter based radiation field targeting for high performance small animal microirradiation

NASA Astrophysics Data System (ADS)

Stewart, James M. P.; Ansell, Steve; Lindsay, Patricia E.; Jaffray, David A.

2015-12-01

Advances in precision microirradiators for small animal radiation oncology studies have provided the framework for novel translational radiobiological studies. Such systems target radiation fields at the scale required for small animal investigations, typically through a combination of on-board computed tomography image guidance and fixed, interchangeable collimators. Robust targeting accuracy of these radiation fields remains challenging, particularly at the millimetre scale field sizes achievable by the majority of microirradiators. Consistent and reproducible targeting accuracy is further hindered as collimators are removed and inserted during a typical experimental workflow. This investigation quantified this targeting uncertainty and developed an online method based on a virtual treatment isocenter to actively ensure high performance targeting accuracy for all radiation field sizes. The results indicated that the two-dimensional field placement uncertainty was as high as 1.16 mm at isocenter, with simulations suggesting this error could be reduced to 0.20 mm using the online correction method. End-to-end targeting analysis of a ball bearing target on radiochromic film sections showed an improved targeting accuracy with the three-dimensional vector targeting error across six different collimators reduced from 0.56+/- 0.05 mm (mean  ±  SD) to 0.05+/- 0.05 mm for an isotropic imaging voxel size of 0.1 mm.

Size-dependent physicochemical and mechanical interactions in battery paste anodes of Si-microwires revealed by Fast-Fourier-Transform Impedance Spectroscopy

NASA Astrophysics Data System (ADS)

Hansen, Sandra; Quiroga-González, Enrique; Carstensen, Jürgen; Adelung, Rainer; Föll, Helmut

2017-05-01

Perfectly aligned silicon microwire arrays show exceptionally high cycling stability with record setting (high) areal capacities of 4.25 mAh cm-2. Those wires have a special, modified length and thickness in order to perform this good. Geometry and sizes are the most important parameters of an anode to obtain batteries with high cycling stability without irreversible losses. The wires are prepared with a unique etching fabrication method, which allows to fabricate wires of very precise sizes. In order to investigate how good randomly oriented silicon wires perform in contrast to the perfect order of the array, the wires are embedded in a paste. This study reveals the fundamental correlation between geometry, mechanics and charge transfer kinetics of silicon electrodes. Using a suitable RC equivalent circuit allows to evaluate data from cyclic voltammetry and simultaneous FFT-Impedance Spectroscopy (FFT-IS), yielding in time-resolved resistances, time constants, and their direct correlation to the phase transformations. The change of the resistances during lithiation and delithiation correlates to kinetics and charge transfer mechanisms. This study demonstrates how the mechanical and physiochemical interactions at the silicon/paste interface inside the paste electrodes lead to void formation around silicon and with it to material loss and capacity fading.

Dense, Efficient Chip-to-Chip Communication at the Extremes of Computing

ERIC Educational Resources Information Center

Loh, Matthew

2013-01-01

The scalability of CMOS technology has driven computation into a diverse range of applications across the power consumption, performance and size spectra. Communication is a necessary adjunct to computation, and whether this is to push data from node-to-node in a high-performance computing cluster or from the receiver of wireless link to a neural…

Performance of container and bareroot loblolly pine seedlings on bottomlands in South Carolina

Treesearch

James P. Barnett; John M. McGilvray

1993-01-01

The performance of container and bareroot loblolly pine (Pinus taeda L.) seedlings from the same improved seedlot was compared on highly productive bottomland sites in South Carolina. At the time of planting, size and quality of the open-grown container stock were equal to or better than bareroot material. When outplanting conditions were ideal,...

Soft-template construction of three-dimensionally ordered inverse opal structure from Li2FeSiO4/C composite nanofibers for high-rate lithium-ion batteries

NASA Astrophysics Data System (ADS)

Li, Donglin; Zhang, Wei; Sun, Ru; Yong, Hong-Tuan-Hua; Chen, Guangqi; Fan, Xiaoyong; Gou, Lei; Mao, Yiyang; Zhao, Kun; Tian, Miao

2016-06-01

Exploring a new method to fabricate small-sized nanofibers is essential to achieve superior performances for energy conversion and storage devices. Here, a novel soft-template strategy is developed to synthesize a three-dimensionally ordered macroporous (3DOM) architecture constructed from small-sized nanofibers. The effectiveness of a nanofiber-assembled three-dimensional inverse opal material as an electrode for high-rate lithium-ion batteries is demonstrated. The small-sized Li2FeSiO4/C composite nanofibers with a diameter of 20-30 nm are grown by employing a tri-block copolymer P123 as a structure directing agent. Accordingly, the macro-mesoporous hierarchical 3DOM architecture constructed from Li2FeSiO4/C nanofibers is further templated from P123 for the nanofibers and a polystyrene colloidal crystal array for the 3DOM architecture. We find that the thermal stability of the nanofiber morphology depends on the self-limited growth of Li2FeSiO4 nanocrystals in a crystalline-amorphous hybrid. As a cathode for a lithium-ion battery, the 3D hierarchical macro-mesoporous cathodes exhibit outstanding high-rate and ultralong-life performances with a capacity retention of 84% after 1500 cycles at 5 C in the voltage window of 1.5-4.5 V, which is greatly improved compared with a simple 3DOM Li2FeSiO4/C nanocomposite.Exploring a new method to fabricate small-sized nanofibers is essential to achieve superior performances for energy conversion and storage devices. Here, a novel soft-template strategy is developed to synthesize a three-dimensionally ordered macroporous (3DOM) architecture constructed from small-sized nanofibers. The effectiveness of a nanofiber-assembled three-dimensional inverse opal material as an electrode for high-rate lithium-ion batteries is demonstrated. The small-sized Li2FeSiO4/C composite nanofibers with a diameter of 20-30 nm are grown by employing a tri-block copolymer P123 as a structure directing agent. Accordingly, the macro-mesoporous hierarchical 3DOM architecture constructed from Li2FeSiO4/C nanofibers is further templated from P123 for the nanofibers and a polystyrene colloidal crystal array for the 3DOM architecture. We find that the thermal stability of the nanofiber morphology depends on the self-limited growth of Li2FeSiO4 nanocrystals in a crystalline-amorphous hybrid. As a cathode for a lithium-ion battery, the 3D hierarchical macro-mesoporous cathodes exhibit outstanding high-rate and ultralong-life performances with a capacity retention of 84% after 1500 cycles at 5 C in the voltage window of 1.5-4.5 V, which is greatly improved compared with a simple 3DOM Li2FeSiO4/C nanocomposite. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr07783d

Performance of an Achromatic Focal Plane Mask for Exoplanet Imaging Coronagraphy

NASA Technical Reports Server (NTRS)

Newman, Kevin; Belikov, Ruslan; Pluzhnik, Eugene; Balasubramanian, Kunjithapatham; Wilson, Dan

2014-01-01

Coronagraph technology combined with wavefront control is close to achieving the contrast and inner working angle requirements in the lab necessary to observe the faint signal of an Earth-like exoplanet in monochromatic light. An important remaining technological challenge is to achieve high contrast in broadband light. Coronagraph bandwidth is largely limited by chromaticity of the focal plane mask, which is responsible for blocking the stellar PSF. The size of a stellar PSF scales linearly with wavelength; ideally, the size of the focal plane mask would also scale with wavelength. A conventional hard-edge focal plane mask has a fixed size, normally sized for the longest wavelength in the observational band to avoid starlight leakage. The conventional mask is oversized for shorter wavelengths and blocks useful discovery space. Recently we presented a solution to the size chromaticity challenge with a focal plane mask designed to scale its effective size with wavelength. In this paper, we analyze performance of the achromatic size-scaling focal plane mask within a Phase Induced Amplitude Apodization (PIAA) coronagraph. We present results from wavefront control around the achromatic focal plane mask, and demonstrate the size-scaling effect of the mask with wavelength. The edge of the dark zone, and therefore the inner working angle of the coronagraph, scale with wavelength. The achromatic mask enables operation in a wider band of wavelengths compared with a conventional hard-edge occulter.

Size-dependent physiological responses of the branching coral Pocillopora verrucosa to elevated temperature and PCO2.

PubMed

Edmunds, Peter J; Burgess, Scott C

2016-12-15

Body size has large effects on organism physiology, but these effects remain poorly understood in modular animals with complex morphologies. Using two trials of a ∼24 day experiment conducted in 2014 and 2015, we tested the hypothesis that colony size of the coral Pocillopora verrucosa affects the response of calcification, aerobic respiration and gross photosynthesis to temperature (∼26.5 and ∼29.7°C) and P CO 2  (∼40 and ∼1000 µatm). Large corals calcified more than small corals, but at a slower size-specific rate; area-normalized calcification declined with size. Whole-colony and area-normalized calcification were unaffected by temperature, P CO 2 , or the interaction between the two. Whole-colony respiration increased with colony size, but the slopes of these relationships differed between treatments. Area-normalized gross photosynthesis declined with colony size, but whole-colony photosynthesis was unaffected by P CO 2 , and showed a weak response to temperature. When scaled up to predict the response of large corals, area-normalized metrics of physiological performance measured using small corals provide inaccurate estimates of the physiological performance of large colonies. Together, these results demonstrate the importance of colony size in modulating the response of branching corals to elevated temperature and high P CO 2 . © 2016. Published by The Company of Biologists Ltd.

Quantitative comparison using Generalized Relative Object Detectability (G-ROD) metrics of an amorphous selenium detector with high resolution Microangiographic Fluoroscopes (MAF) and standard flat panel detectors (FPD).

PubMed

Russ, M; Shankar, A; Jain, A; Setlur Nagesh, S V; Ionita, C N; Scott, C; Karim, K S; Bednarek, D R; Rudin, S

2016-02-27

A novel amorphous selenium (a-Se) direct detector with CMOS readout has been designed, and relative detector performance investigated. The detector features include a 25 μ m pixel pitch, and 1000 μ m thick a-Se layer operating at 10V/ μ m bias field. A simulated detector DQE was determined, and used in comparative calculations of the Relative Object Detectability (ROD) family of prewhitening matched-filter (PWMF) observer and non-prewhitening matched filter (NPWMF) observer model metrics to gauge a-Se detector performance against existing high resolution micro-angiographic fluoroscopic (MAF) detectors and a standard flat panel detector (FPD). The PWMF-ROD or ROD metric compares two x-ray imaging detectors in their relative abilities in imaging a given object by taking the integral over spatial frequencies of the Fourier transform of the detector DQE weighted by an object function, divided by the comparable integral for a different detector. The generalized-ROD (G-ROD) metric incorporates clinically relevant parameters (focal-spot size, magnification, and scatter) to show the degradation in imaging performance for detectors that are part of an imaging chain. Preliminary ROD calculations using simulated spheres as the object predicted superior imaging performance by the a-Se detector as compared to existing detectors. New PWMF-G-ROD and NPWMF-G-ROD results still indicate better performance by the a-Se detector in an imaging chain over all sphere sizes for various focal spot sizes and magnifications, although a-Se performance advantages were degraded by focal spot blurring. Nevertheless, the a-Se technology has great potential to provide breakthrough abilities such as visualization of fine details including of neuro-vascular perforator vessels and of small vascular devices.

NEMA NU 2-2007 performance measurements of the Siemens Inveon™ preclinical small animal PET system

PubMed Central

Kemp, Brad J; Hruska, Carrie B; McFarland, Aaron R; Lenox, Mark W; Lowe, Val J

2010-01-01

National Electrical Manufacturers Association (NEMA) NU 2-2007 performance measurements were conducted on the Inveon™ preclinical small animal PET system developed by Siemens Medical Solutions. The scanner uses 1.51 × 1.51 × 10 mm LSO crystals grouped in 20 × 20 blocks; a tapered light guide couples the LSO crystals of a block to a position-sensitive photomultiplier tube. There are 80 rings with 320 crystals per ring and the ring diameter is 161 mm. The transaxial and axial fields of view (FOVs) are 100 and 127 mm, respectively. The scanner can be docked to a CT scanner; the performance characteristics of the CT component are not included herein. Performance measurements of spatial resolution, sensitivity, scatter fraction and count rate performance were obtained for different energy windows and coincidence timing window widths. For brevity, the results described here are for an energy window of 350–650 keV and a coincidence timing window of 3.43 ns. The spatial resolution at the center of the transaxial and axial FOVs was 1.56, 1.62 and 2.12 mm in the tangential, radial and axial directions, respectively, and the system sensitivity was 36.2 cps kBq−1 for a line source (7.2% for a point source). For mouse- and rat-sized phantoms, the scatter fraction was 5.7% and 14.6%, respectively. The peak noise equivalent count rate with a noisy randoms estimate was 1475 kcps at 130 MBq for the mouse-sized phantom and 583 kcps at 74 MBq for the rat-sized phantom. The performance measurements indicate that the Inveon™ PET scanner is a high-resolution tomograph with excellent sensitivity that is capable of imaging at a high count rate. PMID:19321924

Quantitative comparison using generalized relative object detectability (G-ROD) metrics of an amorphous selenium detector with high resolution microangiographic fluoroscopes (MAF) and standard flat panel detectors (FPD)

NASA Astrophysics Data System (ADS)

Russ, M.; Shankar, A.; Jain, A.; Setlur Nagesh, S. V.; Ionita, C. N.; Scott, C.; Karim, K. S.; Bednarek, D. R.; Rudin, S.

2016-03-01

A novel amorphous selenium (a-Se) direct detector with CMOS readout has been designed, and relative detector performance investigated. The detector features include a 25μm pixel pitch, and 1000μm thick a-Se layer operating at 10V/μm bias field. A simulated detector DQE was determined, and used in comparative calculations of the Relative Object Detectability (ROD) family of prewhitening matched-filter (PWMF) observer and non-pre-whitening matched filter (NPWMF) observer model metrics to gauge a-Se detector performance against existing high resolution micro-angiographic fluoroscopic (MAF) detectors and a standard flat panel detector (FPD). The PWMF-ROD or ROD metric compares two x-ray imaging detectors in their relative abilities in imaging a given object by taking the integral over spatial frequencies of the Fourier transform of the detector DQE weighted by an object function, divided by the comparable integral for a different detector. The generalized-ROD (G-ROD) metric incorporates clinically relevant parameters (focal- spot size, magnification, and scatter) to show the degradation in imaging performance for detectors that are part of an imaging chain. Preliminary ROD calculations using simulated spheres as the object predicted superior imaging performance by the a-Se detector as compared to existing detectors. New PWMF-G-ROD and NPWMF-G-ROD results still indicate better performance by the a-Se detector in an imaging chain over all sphere sizes for various focal spot sizes and magnifications, although a-Se performance advantages were degraded by focal spot blurring. Nevertheless, the a-Se technology has great potential to provide break- through abilities such as visualization of fine details including of neuro-vascular perforator vessels and of small vascular devices.

Extreme Postnatal Scaling in Bat Feeding Performance: A View of Ecomorphology from Ontogenetic and Macroevolutionary Perspectives.

PubMed

Santana, Sharlene E; Miller, Kimberly E

2016-09-01

Ecomorphology studies focus on understanding how anatomical and behavioral diversity result in differences in performance, ecology, and fitness. In mammals, the determinate growth of the skeleton entails that bite performance should change throughout ontogeny until the feeding apparatus attains its adult size and morphology. Then, interspecific differences in adult phenotypes are expected to drive food resource partitioning and patterns of lineage diversification. However, Formal tests of these predictions are lacking for the majority of mammal groups, and thus our understanding of mammalian ecomorphology remains incomplete. By focusing on a fundamental measure of feeding performance, bite force, and capitalizing on the extraordinary morphological and dietary diversity of bats, we discuss how the intersection of ontogenetic and macroevolutionary changes in feeding performance may impact ecological diversity in these mammals. We integrate data on cranial morphology and bite force gathered through longitudinal studies of captive animals and comparative studies of free-ranging individuals. We demonstrate that ontogenetic trajectories and evolutionary changes in bite force are highly dependent on changes in body and head size, and that bats exhibit dramatic, allometric increases in bite force during ontogeny. Interspecific variation in bite force is highly dependent on differences in cranial morphology and function, highlighting selection for ecological specialization. While more research is needed to determine how ontogenetic changes in size and bite force specifically impact food resource use and fitness in bats, interspecific diversity in cranial morphology and bite performance seem to closely match functional differences in diet. Altogether, these results suggest direct ecomorphological relationships at ontogenetic and macroevolutionary scales in bats. © The Author 2016. Published by Oxford University Press on behalf of the Society for Integrative and Comparative Biology. All rights reserved. For permissions please email: journals.permissions@oup.com.

NEMA NU 2-2007 performance measurements of the Siemens Inveon™ preclinical small animal PET system

NASA Astrophysics Data System (ADS)

Kemp, Brad J.; Hruska, Carrie B.; McFarland, Aaron R.; Lenox, Mark W.; Lowe, Val J.

2009-04-01

National Electrical Manufacturers Association (NEMA) NU 2-2007 performance measurements were conducted on the Inveon™ preclinical small animal PET system developed by Siemens Medical Solutions. The scanner uses 1.51 × 1.51 × 10 mm LSO crystals grouped in 20 × 20 blocks; a tapered light guide couples the LSO crystals of a block to a position-sensitive photomultiplier tube. There are 80 rings with 320 crystals per ring and the ring diameter is 161 mm. The transaxial and axial fields of view (FOVs) are 100 and 127 mm, respectively. The scanner can be docked to a CT scanner; the performance characteristics of the CT component are not included herein. Performance measurements of spatial resolution, sensitivity, scatter fraction and count rate performance were obtained for different energy windows and coincidence timing window widths. For brevity, the results described here are for an energy window of 350-650 keV and a coincidence timing window of 3.43 ns. The spatial resolution at the center of the transaxial and axial FOVs was 1.56, 1.62 and 2.12 mm in the tangential, radial and axial directions, respectively, and the system sensitivity was 36.2 cps kBq-1 for a line source (7.2% for a point source). For mouse- and rat-sized phantoms, the scatter fraction was 5.7% and 14.6%, respectively. The peak noise equivalent count rate with a noisy randoms estimate was 1475 kcps at 130 MBq for the mouse-sized phantom and 583 kcps at 74 MBq for the rat-sized phantom. The performance measurements indicate that the Inveon™ PET scanner is a high-resolution tomograph with excellent sensitivity that is capable of imaging at a high count rate.

Quantitative comparison using Generalized Relative Object Detectability (G-ROD) metrics of an amorphous selenium detector with high resolution Microangiographic Fluoroscopes (MAF) and standard flat panel detectors (FPD)

PubMed Central

Russ, M.; Shankar, A.; Jain, A.; Setlur Nagesh, S. V.; Ionita, C. N.; Scott, C.; Karim, K. S.; Bednarek, D. R.; Rudin, S.

2017-01-01

A novel amorphous selenium (a-Se) direct detector with CMOS readout has been designed, and relative detector performance investigated. The detector features include a 25μm pixel pitch, and 1000μm thick a-Se layer operating at 10V/μm bias field. A simulated detector DQE was determined, and used in comparative calculations of the Relative Object Detectability (ROD) family of prewhitening matched-filter (PWMF) observer and non-prewhitening matched filter (NPWMF) observer model metrics to gauge a-Se detector performance against existing high resolution micro-angiographic fluoroscopic (MAF) detectors and a standard flat panel detector (FPD). The PWMF-ROD or ROD metric compares two x-ray imaging detectors in their relative abilities in imaging a given object by taking the integral over spatial frequencies of the Fourier transform of the detector DQE weighted by an object function, divided by the comparable integral for a different detector. The generalized-ROD (G-ROD) metric incorporates clinically relevant parameters (focal-spot size, magnification, and scatter) to show the degradation in imaging performance for detectors that are part of an imaging chain. Preliminary ROD calculations using simulated spheres as the object predicted superior imaging performance by the a-Se detector as compared to existing detectors. New PWMF-G-ROD and NPWMF-G-ROD results still indicate better performance by the a-Se detector in an imaging chain over all sphere sizes for various focal spot sizes and magnifications, although a-Se performance advantages were degraded by focal spot blurring. Nevertheless, the a-Se technology has great potential to provide breakthrough abilities such as visualization of fine details including of neuro-vascular perforator vessels and of small vascular devices. PMID:28615795

Role of Computer Aided Diagnosis (CAD) in the detection of pulmonary nodules on 64 row multi detector computed tomography.

PubMed

Prakashini, K; Babu, Satish; Rajgopal, K V; Kokila, K Raja

2016-01-01

To determine the overall performance of an existing CAD algorithm with thin-section computed tomography (CT) in the detection of pulmonary nodules and to evaluate detection sensitivity at a varying range of nodule density, size, and location. A cross-sectional prospective study was conducted on 20 patients with 322 suspected nodules who underwent diagnostic chest imaging using 64-row multi-detector CT. The examinations were evaluated on reconstructed images of 1.4 mm thickness and 0.7 mm interval. Detection of pulmonary nodules, initially by a radiologist of 2 years experience (RAD) and later by CAD lung nodule software was assessed. Then, CAD nodule candidates were accepted or rejected accordingly. Detected nodules were classified based on their size, density, and location. The performance of the RAD and CAD system was compared with the gold standard that is true nodules confirmed by consensus of senior RAD and CAD together. The overall sensitivity and false-positive (FP) rate of CAD software was calculated. Of the 322 suspected nodules, 221 were classified as true nodules on the consensus of senior RAD and CAD together. Of the true nodules, the RAD detected 206 (93.2%) and 202 (91.4%) by the CAD. CAD and RAD together picked up more number of nodules than either CAD or RAD alone. Overall sensitivity for nodule detection with the CAD program was 91.4%, and FP detection per patient was 5.5%. The CAD showed comparatively higher sensitivity for nodules of size 4-10 mm (93.4%) and nodules in hilar (100%) and central (96.5%) location when compared to RAD's performance. CAD performance was high in detecting pulmonary nodules including the small size and low-density nodules. CAD even with relatively high FP rate, assists and improves RAD's performance as a second reader, especially for nodules located in the central and hilar region and for small nodules by saving RADs time.

High-speed spectral nanocytology for early cancer screening

PubMed Central

Subramanian, Hariharan; Maneval, Charles D.; White, Craig A.; Levenson, Richard M.; Backman, Vadim

2013-01-01

Abstract. High-throughput partial wave spectroscopy (HTPWS) is introduced as a high-speed spectral nanocytology technique that utilizes the field effect of carcinogenesis to perform minimally invasive cancer screening on at-risk populations. HTPWS uses fully automated hardware and an acousto-optic tunable filter to scan slides at low magnification, to select cells, and to rapidly acquire spectra at each spatial pixel in a cell between 450 and 700 nm, completing measurements of 30 cells in 40 min. Statistical quantitative analysis on the size and density of intracellular nanostructures extracted from the spectra at each pixel in a cell yields the diagnostic biomarker, disorder strength (Ld). Linear correlation between Ld and the length scale of nanostructures was measured in phantoms with R2=0.93. Diagnostic sensitivity was demonstrated by measuring significantly higher Ld from a human colon cancer cell line (HT29 control vector) than a less aggressive variant (epidermal growth factor receptor knockdown). Clinical diagnostic performance for lung cancer screening was tested on 23 patients, yielding a significant difference in Ld between smokers and cancer patients, p=0.02 and effect size=1.00. The high-throughput performance, nanoscale sensitivity, and diagnostic sensitivity make HTPWS a potentially clinically relevant modality for risk stratification of the large populations at risk of developing cancer. PMID:24193949

Whole-Genome Resequencing of Experimental Populations Reveals Polygenic Basis of Egg-Size Variation in Drosophila melanogaster.

PubMed

Jha, Aashish R; Miles, Cecelia M; Lippert, Nodia R; Brown, Christopher D; White, Kevin P; Kreitman, Martin

2015-10-01

Complete genome resequencing of populations holds great promise in deconstructing complex polygenic traits to elucidate molecular and developmental mechanisms of adaptation. Egg size is a classic adaptive trait in insects, birds, and other taxa, but its highly polygenic architecture has prevented high-resolution genetic analysis. We used replicated experimental evolution in Drosophila melanogaster and whole-genome sequencing to identify consistent signatures of polygenic egg-size adaptation. A generalized linear-mixed model revealed reproducible allele frequency differences between replicated experimental populations selected for large and small egg volumes at approximately 4,000 single nucleotide polymorphisms (SNPs). Several hundred distinct genomic regions contain clusters of these SNPs and have lower heterozygosity than the genomic background, consistent with selection acting on polymorphisms in these regions. These SNPs are also enriched among genes expressed in Drosophila ovaries and many of these genes have well-defined functions in Drosophila oogenesis. Additional genes regulating egg development, growth, and cell size show evidence of directional selection as genes regulating these biological processes are enriched for highly differentiated SNPs. Genetic crosses performed with a subset of candidate genes demonstrated that these genes influence egg size, at least in the large genetic background. These findings confirm the highly polygenic architecture of this adaptive trait, and suggest the involvement of many novel candidate genes in regulating egg size. © The Author 2015. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

Gallium Arsenide Pilot Line for High Performance Components

DTIC Science & Technology

1992-05-28

two transistors’ characteristics were a close enough match to use as pull -up, high resistance loads in the cell. FET Data Unfortunately, data obtained...length transistors in 4K SRAM II, we can predict the performance of the memory chip. Since there is essentially no active pull up capability in the c a...Second, the 2/2 Am DFET’s threshold and "ON" current could be adjusted. Or third, a different size DFET pull -up transistor could be used which more

Production, characterisation, and in vitro nebulisation performance of budesonide-loaded PLA nanoparticles.

PubMed

Amini, Mohammad Ali; Faramarzi, Mohammad Ali; Gilani, Kambiz; Moazeni, Esmaeil; Esmaeilzadeh-Gharehdaghi, Elina; Amani, Amir

2014-01-01

The aim of this study is to prepare a nanosuspension of budesonide for respiratory delivery using nebuliser by optimising its particle size and characterising its in vitro deposition behaviour. PLA (poly lactic acid)-budesonide nanosuspension (BNS) was prepared using high-pressure emulsification/solvent evaporation method. To optimise particle size, different parameters such as PLA concentration, sonication time, and amplitude were investigated. Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and scanning electron microscope (SEM) analyses were performed to characterise the prepared PLA-budesonide nanoparticles. The in vitro aerodynamic characteristics of the PLA-BNS using a jet nebuliser were estimated and compared with that of commercially available suspension formulation of budesonide. Budesonide-loaded PLA nanoparticles with fine particle size (an average size of 224-360 nm), narrow size distribution, and spherical and smooth surface were prepared. The optimum condition for preparation of fine particle size for aerosolisation was found to be at PLA concentration of 1.2 mg/ml and amplitude of 70 for 75 s sonication time. The in vitro aerosolisation performance of PLA-BNS compared to that of commercial budesonide indicated that it has significantly (p < 0.05) smaller mass median aerodynamic diameter (MMAD) value with an enhancement in fine particle fraction (FPF) value. Improving the in vitro deposition of budesonide, PLA-BNS could be considered as a promising alternative suspension formulation for deep lung delivery of the drug using nebuliser.

Sensitivity studies of beam directionality, beam size, and neutron spectrum for a fission converter-based epithermal neutron beam for boron neutron capture therapy.

PubMed

Sakamoto, S; Kiger, W S; Harling, O K

1999-09-01

Sensitivity studies of epithermal neutron beam performance in boron neutron capture therapy are presented for realistic neutron beams with varying filter/moderator and collimator/delimiter designs to examine the relative importance of neutron beam spectrum, directionality, and size. Figures of merit for in-air and in-phantom beam performance are calculated via the Monte Carlo technique for different well-optimized designs of a fission converter-based epithermal neutron beam with head phantoms as the irradiation target. It is shown that increasing J/phi, a measure of beam directionality, does not always lead to corresponding monotonic improvements in beam performance. Due to the relatively low significance, for most configurations, of its effect on in-phantom performance and the large intensity losses required to produce beams with very high J/phi, beam directionality should not be considered an important figure of merit in epithermal neutron beam design except in terms of its consequences on patient positioning and collateral dose. Hardening the epithermal beam spectrum, while maintaining the specific fast neutron dose well below the inherent hydrogen capture dose, improves beam penetration and advantage depth and, as a desirable by-product, significantly increases beam intensity. Beam figures of merit are shown to be strongly dependent on beam size relative to target size. Beam designs with J/phi approximately 0.65-0.7, specific fast neutron doses of 2-2.6x10(-13) Gy cm2/n and beam sizes equal to or larger than the size of the head target produced the deepest useful penetration, highest therapeutic ratios, and highest intensities.

Technology of Performance Improvement Brushless DC Motors and Inverter for Air conditioning

NASA Astrophysics Data System (ADS)

Baba, Kazuhiko; Matsuoka, Atsushi; Shinomoto, Yosuke; Arisawa, Koichi

High efficiency motors are demanded because of the viewpoint of environmental preservation. It is necessary to develop the technology of the energy conservation that can be achieved at low cost so that we may expand high efficiency motors onto the world. In this paper, the current status of the brushless DC motors and invertors to satisfy high efficiency, small size, high power and low cost is reviewed.

Modeling the Space Debris Environment with MASTER-2009 and ORDEM2010

NASA Technical Reports Server (NTRS)

Flegel, S.; Gelhaus, J.; Wiedemann, C.; Mockel, M.; Vorsmann, P.; Krisko, P.; Xu, Y. -L.; Horstman, M. F.; Opiela, J. N.; Matney, M.;

Harnessing the damping properties of materials for high-speed atomic force microscopy.

PubMed

Adams, Jonathan D; Erickson, Blake W; Grossenbacher, Jonas; Brugger, Juergen; Nievergelt, Adrian; Fantner, Georg E

2016-02-01

The success of high-speed atomic force microscopy in imaging molecular motors, enzymes and microbes in liquid environments suggests that the technique could be of significant value in a variety of areas of nanotechnology. However, the majority of atomic force microscopy experiments are performed in air, and the tapping-mode detection speed of current high-speed cantilevers is an order of magnitude lower in air than in liquids. Traditional approaches to increasing the imaging rate of atomic force microscopy have involved reducing the size of the cantilever, but further reductions in size will require a fundamental change in the detection method of the microscope. Here, we show that high-speed imaging in air can instead be achieved by changing the cantilever material. We use cantilevers fabricated from polymers, which can mimic the high damping environment of liquids. With this approach, SU-8 polymer cantilevers are developed that have an imaging-in-air detection bandwidth that is 19 times faster than those of conventional cantilevers of similar size, resonance frequency and spring constant.

Performance and Aging of Mn/MnO2 as an Environmentally Friendly Energetic Time Delay Composition

DTIC Science & Technology

2014-04-16

for the powders used in these experiments are summarized in Table 1. Particle size distributions for Mn and MnO2 were obtained using a Malvern... particle size data. Mn/MnO2 compositions were dry mixed in 30 mL HDPE bottles using a Resodyn LabRAM mixer at 80% intensity in 2 min intervals for a...predicted. Due to the high heat losses of the small Table 1. Vendor Information of Reactant Powders powder nominal particle size vendor Bi2O3 15.4 μm Alfa

One-click scanning of large-size documents using mobile phone camera

NASA Astrophysics Data System (ADS)

Liu, Sijiang; Jiang, Bo; Yang, Yuanjie

2016-07-01

Currently mobile apps for document scanning do not provide convenient operations to tackle large-size documents. In this paper, we present a one-click scanning approach for large-size documents using mobile phone camera. After capturing a continuous video of documents, our approach automatically extracts several key frames by optical flow analysis. Then based on key frames, a mobile GPU based image stitching method is adopted to generate a completed document image with high details. There are no extra manual intervention in the process and experimental results show that our app performs well, showing convenience and practicability for daily life.

Submicron Protein Particle Characterization using Resistive Pulse Sensing and Conventional Light Scattering Based Approaches.

PubMed

Barnett, Gregory V; Perhacs, Julia M; Das, Tapan K; Kar, Sambit R

2018-02-08

Characterizing submicron protein particles (approximately 0.1-1μm) is challenging due to a limited number of suitable instruments capable of monitoring a relatively large continuum of particle size and concentration. In this work, we report for the first time the characterization of submicron protein particles using the high size resolution technique of resistive pulse sensing (RPS). Resistive pulse sensing, dynamic light scattering and size-exclusion chromatography with in-line multi-angle light scattering (SEC-MALS) are performed on protein and placebo formulations, polystyrene size standards, placebo formulations spiked with silicone oil, and protein formulations stressed via freeze-thaw cycling, thermal incubation, and acid treatment. A method is developed for monitoring submicron protein particles using RPS. The suitable particle concentration range for RPS is found to be approximately 4 × 10 7 -1 × 10 11 particles/mL using polystyrene size standards. Particle size distributions by RPS are consistent with hydrodynamic diameter distributions from batch DLS and to radius of gyration profiles from SEC-MALS. RPS particle size distributions provide an estimate of particle counts and better size resolution compared to light scattering. RPS is applicable for characterizing submicron particles in protein formulations with a high degree of size polydispersity. Data on submicron particle distributions provide insights into particles formation under different stresses encountered during biologics drug development.

Experimental determination of the effect of detector size on profile measurements in narrow photon beams.

PubMed

Pappas, E; Maris, T G; Papadakis, A; Zacharopoulou, F; Damilakis, J; Papanikolaou, N; Gourtsoyiannis, N

2006-10-01

The aim of this work is to investigate experimentally the detector size effect on narrow beam profile measurements. Polymer gel and magnetic resonance imaging dosimetry was used for this purpose. Profile measurements (Pm(s)) of a 5 mm diameter 6 MV stereotactic beam were performed using polymer gels. Eight measurements of the profile of this narrow beam were performed using correspondingly eight different detector sizes. This was achieved using high spatial resolution (0.25 mm) two-dimensional measurements and eight different signal integration volumes A X A X slice thickness, simulating detectors of different size. "A" ranged from 0.25 to 7.5 mm, representing the detector size. The gel-derived profiles exhibited increased penumbra width with increasing detector size, for sizes >0.5 mm. By extrapolating the gel-derived profiles to zero detector size, the true profile (Pt) of the studied beam was derived. The same polymer gel data were also used to simulate a small-volume ion chamber profile measurement of the same beam, in terms of volume averaging. The comparison between these results and actual corresponding small-volume chamber profile measurements performed in this study, reveal that the penumbra broadening caused by both volume averaging and electron transport alterations (present in actual ion chamber profile measurements) is a lot more intense than that resulted by volume averaging effects alone (present in gel-derived profiles simulating ion chamber profile measurements). Therefore, not only the detector size, but also its composition and tissue equivalency is proved to be an important factor for correct narrow beam profile measurements. Additionally, the convolution kernels related to each detector size and to the air ion chamber were calculated using the corresponding profile measurements (Pm(s)), the gel-derived true profile (Pt), and convolution theory. The response kernels of any desired detector can be derived, allowing the elimination of the errors associated with narrow beam profile measurements.

The feasibility of using explicit method for linear correction of the particle size variation using NIR Spectroscopy combined with PLS2regression method

NASA Astrophysics Data System (ADS)

Yulia, M.; Suhandy, D.

2018-03-01

NIR spectra obtained from spectral data acquisition system contains both chemical information of samples as well as physical information of the samples, such as particle size and bulk density. Several methods have been established for developing calibration models that can compensate for sample physical information variations. One common approach is to include physical information variation in the calibration model both explicitly and implicitly. The objective of this study was to evaluate the feasibility of using explicit method to compensate the influence of different particle size of coffee powder in NIR calibration model performance. A number of 220 coffee powder samples with two different types of coffee (civet and non-civet) and two different particle sizes (212 and 500 µm) were prepared. Spectral data was acquired using NIR spectrometer equipped with an integrating sphere for diffuse reflectance measurement. A discrimination method based on PLS-DA was conducted and the influence of different particle size on the performance of PLS-DA was investigated. In explicit method, we add directly the particle size as predicted variable results in an X block containing only the NIR spectra and a Y block containing the particle size and type of coffee. The explicit inclusion of the particle size into the calibration model is expected to improve the accuracy of type of coffee determination. The result shows that using explicit method the quality of the developed calibration model for type of coffee determination is a little bit superior with coefficient of determination (R2) = 0.99 and root mean square error of cross-validation (RMSECV) = 0.041. The performance of the PLS2 calibration model for type of coffee determination with particle size compensation was quite good and able to predict the type of coffee in two different particle sizes with relatively high R2 pred values. The prediction also resulted in low bias and RMSEP values.

Locomotor performance in highly-trained young soccer players: does body size always matter?

PubMed

Buchheit, M; Mendez-Villanueva, A; Mayer, N; Jullien, H; Marles, A; Bosquet, L; Maille, P; Morin, J-B; Cazorla, G; Lambert, P

2014-06-01

To examine the effects of body size on locomotor performance, 807 15-year-old French and 64 Qatari soccer players participated in the present study. They performed a 40-m sprint and an incremental running test to assess maximal sprinting (MSS) and aerobic speeds, respectively. French players were advanced in maturity, taller, heavier, faster and fitter than their Qatari counterparts (e.g., Cohen's d=+1.3 and + 0.5 for body mass and MSS). However, when adjusted for body mass (BM), Qatari players had possibly greater MSS than French players (d=+0.2). A relative age effect was observed within both countries, with the players born in the first quarter of the year being taller, heavier and faster that those born during the fourth quarter (e.g., d=+0.2 for MSS in French players). When directly adjusted for BM, these MSS differences remained (d=+0.2). Finally, in both countries, players selected in National teams were taller, heavier, faster and fitter than their non-selected counterparts (e.g., d=+0.6 for MSS in French players), even after adjustments for body size (d=+0.5). Differences in locomotor performances between players with different phenotypes are likely mediated by differences in body size. However, when considering more homogeneous player groups, body dimensions are unlikely to substantially explain the superior locomotor performances of older and/or international players. © Georg Thieme Verlag KG Stuttgart · New York.

The genetics of overwintering performance in two-year old common carp and its relation to performance until market size

PubMed Central

Kause, Antti; Vandeputte, Marc; Gela, David; Allamellou, Jean-Michel; Kumar, Girish; Bestin, Anastasia; Bugeon, Jérôme; Zhao, Jinfeng; Kocour, Martin

2018-01-01

Using farmed common carp, we investigated the genetic background of the second year overwintering performance and its relation to the performance during the third growing season and at market size. The experimental stock was established by partial factorial design with a series of 4 factorial matings of 5 dams and 10 sires each. The families were reared communally and pedigree was re-constructed with 93.6% success using 12 microsatellites on 2008 offspring. Three successive recordings (second autumn, third spring, and third autumn—market size) covering two periods (second overwintering, third growing season) were included. Body weight, Fulton’s condition factor and percent muscle fat content were recorded at all times and headless carcass yield and fillet yield were recorded at market size. Specific growth rate, absolute and relative fat change and overall survival were calculated for each period. Heritability estimates were significantly different from zero and almost all traits were moderately to highly heritable (h2 = 0.36–1.00), except survival in both periods and fat change (both patterns) during overwintering (h2 = 0.12–0.15). Genetic and phenotypic correlations imply that selection against weight loss and fat loss during overwintering is expected to lead to a better winter survival, together with a positive effect on growth in the third growing season. Interestingly, higher muscle fat content was genetically correlated to lower survival in the following period (rg = -0.59; -0.53, respectively for winter and the third summer). On the other hand, higher muscle fat was also genetically linked to better slaughter yields. Moreover, selection for higher condition factor would lead to better performance during winter, growing season and at market size. PMID:29370279

The genetics of overwintering performance in two-year old common carp and its relation to performance until market size.

PubMed

Prchal, Martin; Kause, Antti; Vandeputte, Marc; Gela, David; Allamellou, Jean-Michel; Kumar, Girish; Bestin, Anastasia; Bugeon, Jérôme; Zhao, Jinfeng; Kocour, Martin

2018-01-01

Using farmed common carp, we investigated the genetic background of the second year overwintering performance and its relation to the performance during the third growing season and at market size. The experimental stock was established by partial factorial design with a series of 4 factorial matings of 5 dams and 10 sires each. The families were reared communally and pedigree was re-constructed with 93.6% success using 12 microsatellites on 2008 offspring. Three successive recordings (second autumn, third spring, and third autumn-market size) covering two periods (second overwintering, third growing season) were included. Body weight, Fulton's condition factor and percent muscle fat content were recorded at all times and headless carcass yield and fillet yield were recorded at market size. Specific growth rate, absolute and relative fat change and overall survival were calculated for each period. Heritability estimates were significantly different from zero and almost all traits were moderately to highly heritable (h2 = 0.36-1.00), except survival in both periods and fat change (both patterns) during overwintering (h2 = 0.12-0.15). Genetic and phenotypic correlations imply that selection against weight loss and fat loss during overwintering is expected to lead to a better winter survival, together with a positive effect on growth in the third growing season. Interestingly, higher muscle fat content was genetically correlated to lower survival in the following period (rg = -0.59; -0.53, respectively for winter and the third summer). On the other hand, higher muscle fat was also genetically linked to better slaughter yields. Moreover, selection for higher condition factor would lead to better performance during winter, growing season and at market size.

Karyotyping human chromosomes by optical and x-ray ptychography methods

DOE PAGES

Shemilt, Laura; Verbanis, Ephanielle; Schwenke, Joerg; ...

2015-02-01

Sorting and identifying chromosomes, a process known as karyotyping, is widely used to detect changes in chromosome shapes and gene positions. In a karyotype the chromosomes are identified by their size and therefore this process can be performed by measuring macroscopic structural variables. Chromosomes contain a specific number of basepairs that linearly correlate with their size; therefore, it is possible to perform a karyotype on chromosomes using their mass as an identifying factor. Here, we obtain the first images, to our knowledge, of chromosomes using the novel imaging method of ptychography. We can use the images to measure the massmore » of chromosomes and perform a partial karyotype from the results. Lastly, we also obtain high spatial resolution using this technique with synchrotron source x-rays.« less

Karyotyping human chromosomes by optical and x-ray ptychography methods

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shemilt, Laura; Verbanis, Ephanielle; Schwenke, Joerg

Sorting and identifying chromosomes, a process known as karyotyping, is widely used to detect changes in chromosome shapes and gene positions. In a karyotype the chromosomes are identified by their size and therefore this process can be performed by measuring macroscopic structural variables. Chromosomes contain a specific number of basepairs that linearly correlate with their size; therefore, it is possible to perform a karyotype on chromosomes using their mass as an identifying factor. Here, we obtain the first images, to our knowledge, of chromosomes using the novel imaging method of ptychography. We can use the images to measure the massmore » of chromosomes and perform a partial karyotype from the results. Lastly, we also obtain high spatial resolution using this technique with synchrotron source x-rays.« less

Manufacturing techniques for titanium aluminide based alloys and metal matrix composites

NASA Astrophysics Data System (ADS)

Kothari, Kunal B.

Dual phase titanium aluminides composed vastly of gamma phase (TiAl) with moderate amount of alpha2 phase (Ti3Al) have been considered for several high temperature aerospace and automobile applications. High specific strength coupled with good high temperature performance in the areas of creep and oxidation resistance makes titanium aluminides "materials of choice" for next generation propulsion systems. Titanium alumnides are primarily being considered as potential replacements for Ni-based superalloys in gas turbine engine components with aim of developing more efficient and leaner engines exhibiting high thrust-to-weight ratio. Thermo-mechanical treatments have shown to enhance the mechanical performance of titanium aluminides. Additionally, small additions of interstitial elements have shown further and significant improvement in the mechanical performance of titanium alumnide alloys. However, titanium aluminides lack considerably in room temperature ductility and as a result manufacturing processes of these aluminides have greatly suffered. Traditional ingot metallurgy and investment casting based methods to produce titanium aluminide parts in addition to being expensive, have also been unsuccessful in producing titanium aluminides with the desired mechanical properties. Hence, the manufacturing costs associated with these methods have completely outweighed the benefits offered by titanium aluminides. Over the last two decades, several powder metallurgy based manufacturing techniques have been studied to produce titanium aluminide parts. These techniques have been successful in producing titanium aluminide parts with a homogeneous and refined microstructure. These powder metallurgy techniques also hold the potential of significant cost reduction depending on the wide market acceptance of titanium aluminides. In the present study, a powder metallurgy based rapid consolidation technique has been used to produce near-net shape parts of titanium aluminides. Micron-sized titanium aluminide powders were rapidly consolidated to form near-net shape titanium aluminide parts in form of small discs and tiles. The rapidly consolidated titanium aluminide parts were found to be fully dense. The microstructure morphology was found to vary with consolidation conditions. The mechanical properties were found to be significantly dependent on microstructure morphology and grain size. Due to rapid consolidation, grain growth during consolidation was limited, which in turn led to enhanced mechanical properties. The high temperature mechanical properties for the consolidated titanium aluminide samples were characterized and were found to retain good mechanical performance up to 700°C. Micron-sized titanium aluminide powders with slightly less Aluminum and small Nb, and Cr additions were rapidly consolidated into near-net shape parts. The consolidated parts were found to exhibit enhanced mechanical performance in terms of ductility and yield strength. The negative effect of Oxygen on the flexural strength at high temperatures was found to be reduced with the addition of Nb. In an effort to further reduce the grain size of the consolidated titanium aluminide samples, the as-received titanium aluminide powders were milled in an attrition mill. The average powder particle size of the powders was reduced by 60% after milling. The milled powders were then rapidly consolidated. The grain size of the consolidated parts was found to be in the sub-micrometer range. The mechanical properties were found to be significantly enhanced due to reduction of grain size in the sub-micrometer range. In order to develop a metal matrix composite based on titanium aluminide matrix reinforced with titanium boride, an experiment to study the effect of rapid consolidation on titanium diboride powders was conducted. Micron-sized titanium diboride powders were consolidated and were found to be 93% dense and exhibited minimal grain growth. The low density of the consolidated part was attributed to low consolidation temperature. Titanium aluminide and titanium diboride powders were blended together in an attrition mill and rapidly consolidated. A metal matrix composite with titanium aluminide matrix reinforced with titanium monoboride plates was formed. The titanium diboride in the powder form was found to be transformed to titanium monoboroide plates during consolidation due to the thermodynamic equilibrium between titanium and titanium monoboride. The metal matrix composite was found to be 90% dense. The low density was due to particle size mismatch between the matrix and reinforcement powders and low consolidation temperature. An increase in the volume of titanium monoboride plates in the metal matrix composite was accompanied by an increase in the elastic modulus of the metal matrix composite.

Silica particles encapsulated poly(styrene-divinylbenzene) monolithic stationary phases for micro-high performance liquid chromatography.

PubMed

Bakry, R; Stöggl, W M; Hochleitner, E O; Stecher, G; Huck, C W; Bonn, G K

2006-11-03

In the paper we demonstrate a new approach for the preparation and application of continuous silica bed columns that involve encapsulation (entrapment) of functionalized silica microparticles, which can be used as packing material in micro high performance liquid chromatography (micro-HPLC) and capillary electrochromatography (CEC). Like traditional packed columns, these capillaries possess characterized silica particles that offer high phase ratio and narrow pore size distribution leading to high retention and separation efficiency, respectively. More importantly, immobilization of the microparticles stabilizes the separation bed and eliminates the need for retaining frits. The developed capillary columns were fabricated in exactly the same way as a packed capillary column (slurry packing) but with an additional entrapment step. This immobilization of the packed bed was achieved by in situ polymerization of styrene and divinylbenzene in presence of decanol as a porogen and azobisisobutyronitrile as thermal initiator. Silica particles with different particle sizes and pore sizes ranging from 60 to 4000 A were studied. In addition different modified silica was used, including C-18 reversed phase, anion exchange and chiral stationary phases. Efficient separation of polyphenolic compounds, peptides, proteins and even DNA mutation were achieved using the developed technique depending on the properties of the silica particles used (particles pore size). For example, using 3 microm ProntoSIL C-18 particles with 300 A pore size, separation efficiencies in the range of 120,000-200,000 plates/m were obtained for protein separation, in a 6 cm x 200 microm i.d. capillary column. Using encapsulated silica C-18 with 1000 A pore size, separation of DNA homo and hetero duplexes were achieved under denaturing HPLC conditions for mutation detection. In addition, nucleotides were separated using anion exchange material encapsulated with poly(styrene-divinylbenzene) (PS/DVB), which indicated that the chromatographic properties of the silica packing material were still active after polymerization. The prepared capillary columns were found to be stable and could easily be operated continuously up to a pressure of 350 bar without column damage and capillary can be cut to any desired length.

Monkeys perform as well as apes and humans in a size discrimination task.

PubMed

Schmitt, Vanessa; Kröger, Iris; Zinner, Dietmar; Call, Josep; Fischer, Julia

2013-09-01

Whether the cognitive competences of monkeys and apes are rather similar or whether the larger-brained apes outperform monkeys in cognitive experiments is a highly debated topic. Direct comparative analyses are therefore essential to examine similarities and differences among species. We here compared six primate species, including humans, chimpanzees, bonobos, gorillas (great apes), olive baboons, and long-tailed macaques (Old World monkeys) in a task on fine-grained size discrimination. Except for gorillas, subjects of all taxa (i.e. humans, apes, and monkeys) were able to discriminate three-dimensional cubes with a volume difference of only 10 % (i.e. cubes of 50 and 48 mm side length) and performed only slightly worse when the cubes were presented successively. The minimal size discriminated declined further with increasing time delay between presentations of the cubes, highlighting the difficulty to memorize exact size differences. The results suggest that differences in brain size, as a proxy for general cognitive abilities, did not account for variation in performance, but that differential socio-ecological pressures may better explain species differences. Our study highlights the fact that differences in cognitive abilities do not always map neatly onto phylogenetic relationships and that in a number of cognitive experiments monkeys do not fare significantly worse than apes, casting doubt on the assumption that larger brains per se confer an advantage in such kinds of tests.

Faster than Real-Time Dynamic Simulation for Large-Size Power System with Detailed Dynamic Models using High-Performance Computing Platform

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, Renke; Jin, Shuangshuang; Chen, Yousu

This paper presents a faster-than-real-time dynamic simulation software package that is designed for large-size power system dynamic simulation. It was developed on the GridPACKTM high-performance computing (HPC) framework. The key features of the developed software package include (1) faster-than-real-time dynamic simulation for a WECC system (17,000 buses) with different types of detailed generator, controller, and relay dynamic models, (2) a decoupled parallel dynamic simulation algorithm with optimized computation architecture to better leverage HPC resources and technologies, (3) options for HPC-based linear and iterative solvers, (4) hidden HPC details, such as data communication and distribution, to enable development centered on mathematicalmore » models and algorithms rather than on computational details for power system researchers, and (5) easy integration of new dynamic models and related algorithms into the software package.« less

A large flat panel multifunction display for military and space applications

NASA Astrophysics Data System (ADS)

Pruitt, James S.

1992-09-01

A flat panel multifunction display (MFD) that offers the size and reliability benefits of liquid crystal display technology while achieving near-CRT display quality is presented. Display generation algorithms that provide exceptional display quality are being implemented in custom VLSI components to minimize MFD size. A high-performance processor converts user-specified display lists to graphics commands used by these components, resulting in high-speed updates of two-dimensional and three-dimensional images. The MFD uses the MIL-STD-1553B data bus for compatibility with virtually all avionics systems. The MFD can generate displays directly from display lists received from the MIL-STD-1553B bus. Complex formats can be stored in the MFD and displayed using parameters from the data bus. The MFD also accepts direct video input and performs special processing on this input to enhance image quality.

Synthesis and characterization of MOF-aminated graphite oxide composites for CO2 capture

NASA Astrophysics Data System (ADS)

Zhao, Yunxia; Ding, Huiling; Zhong, Qin

2013-11-01

A kind of metal-organic frameworks (MOF-5) and aminated graphite oxide (AGO) composites were prepared for CO2 capture to mitigate global warming. MOF-5, MOF-5/GO (composite of MOF-5 and graphite oxide) and MOF-5/AGO samples were characterized by X-ray powder diffraction (XRD), infrared spectroscopy (IR), scanning electron microscope (SEM), nitrogen adsorption as well as thermogravimetric analysis to figure out their chemistry and structure information. Three types of samples with suitable specific surface area and pore diameter were chosen to test CO2 adsorption performance and stability under humidity conditions. The results indicate that high surface area and pore volume, pore similar in size to the size of gas adsorbate, and extra reactive sites modified in the composites contributes to the high CO2 capacity. Besides, the composites involved by GO or AGO show better anti-moisture performance than the parent MOF.

Exfoliation of graphene sheets via high energy wet milling of graphite in 2-ethylhexanol and kerosene.

PubMed

Al-Sherbini, Al-Sayed; Bakr, Mona; Ghoneim, Iman; Saad, Mohamed

2017-05-01

Graphene sheets have been exfoliated from bulk graphite using high energy wet milling in two different solvents that were 2-ethylhexanol and kerosene. The milling process was performed for 60 h using a planetary ball mill. Morphological characteristics were investigated using scanning electron microscope (SEM) and transmission electron microscope (TEM). On the other hand, the structural characterization was performed using X-ray diffraction technique (XRD) and Raman spectrometry. The exfoliated graphene sheets have represented good morphological and structural characteristics with a valuable amount of defects and a good graphitic structure. The graphene sheets exfoliated in the presence of 2-ethylhexanol have represented many layers, large crystal size and low level of defects, while the graphene sheets exfoliated in the presence of kerosene have represented fewer number of layers, smaller crystal size and higher level of defects.

Formation of low resistivity titanium silicide gates in semiconductor integrated circuits

DOEpatents

Ishida, Emi [Sunnyvale, CA

1999-08-10

A method of forming a titanium silicide (69) includes the steps of forming a transistor having a source region (58), a drain region (60) and a gate structure (56) and forming a titanium layer (66) over the transistor. A first anneal is performed with a laser anneal at an energy level that causes the titanium layer (66) to react with the gate structure (56) to form a high resistivity titanium silicide phase (68) having substantially small grain sizes. The unreacted portions of the titanium layer (66) are removed and a second anneal is performed, thereby causing the high resistivity titanium silicide phase (68) to convert to a low resistivity titanium silicide phase (69). The small grain sizes obtained by the first anneal allow low resistivity titanium silicide phase (69) to be achieved at device geometries less than about 0.25 micron.

Residual tumor size and IGCCCG risk classification predict additional vascular procedures in patients with germ cell tumors and residual tumor resection: a multicenter analysis of the German Testicular Cancer Study Group.

PubMed

Winter, Christian; Pfister, David; Busch, Jonas; Bingöl, Cigdem; Ranft, Ulrich; Schrader, Mark; Dieckmann, Klaus-Peter; Heidenreich, Axel; Albers, Peter

2012-02-01

Residual tumor resection (RTR) after chemotherapy in patients with advanced germ cell tumors (GCT) is an important part of the multimodal treatment. To provide a complete resection of residual tumor, additional surgical procedures are sometimes necessary. In particular, additional vascular interventions are high-risk procedures that require multidisciplinary planning and adequate resources to optimize outcome. The aim was to identify parameters that predict additional vascular procedures during RTR in GCT patients. A retrospective analysis was performed in 402 GCT patients who underwent 414 RTRs in 9 German Testicular Cancer Study Group (GTCSG) centers. Overall, 339 of 414 RTRs were evaluable with complete perioperative data sets. The RTR database was queried for additional vascular procedures (inferior vena cava [IVC] interventions, aortic prosthesis) and correlated to International Germ Cell Cancer Collaborative Group (IGCCCG) classification and residual tumor volume. In 40 RTRs, major vascular procedures (23 IVC resections with or without prosthesis, 11 partial IVC resections, and 6 aortic prostheses) were performed. In univariate analysis, the necessity of IVC intervention was significantly correlated with IGCCCG (14.1% intermediate/poor vs 4.8% good; p=0.0047) and residual tumor size (3.7% size < 5 cm vs 17.9% size ≥ 5 cm; p < 0.0001). In multivariate analysis, IVC intervention was significantly associated with residual tumor size ≥ 5 cm (odds ratio [OR]: 4.61; p=0.0007). In a predictive model combining residual tumor size and IGCCCG classification, every fifth patient (20.4%) with a residual tumor size ≥ 5 cm and intermediate or poor prognosis needed an IVC intervention during RTR. The need for an aortic prosthesis showed no correlation to either IGCCCG (p=0.1811) or tumor size (p=0.0651). The necessity for IVC intervention during RTR is correlated to residual tumor size and initial IGCCCG classification. Patients with high-volume residual tumors and intermediate or poor risk features must initially be identified as high-risk patients for vascular procedures and therefore should be referred to specialized surgical centers with the ad hoc possibility of vascular interventions. Copyright © 2011 European Association of Urology. Published by Elsevier B.V. All rights reserved.

In Situ Observation of Single-Phase Lithium Intercalation in Sub-25-nm Nanoparticles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhong, Li; Liu, Yang; Han, Wei-Qiang

Although a non-equilibrium single-phase reaction, with the absence of nucleation and growth of a second phase, is believed to be a key factor for high-rate performance of lithium-ion batteries, it is thermodynamically unfavorable and usually proceeds in electrode materials with small particle sizes (tens of nanometers). Unfortunately, the phase evolutions inside such small particles are often shrouded by the macroscopic inhomogeneous reactions of electrodes containing millions of particles, leading to intensive debate over the size-dependent microscopic reaction mechanisms. Here, we provide a generally applicable methodology based on in-situ electron diffraction study on a multi-particle system to track the lithiation pathwaysmore » in individual nanoparticles, and unambiguously reveal that lithiation of anatase TiO 2, previously long believed to be biphasic, converts to a single-phase reaction when the particle size is below ~25 nm. Our results imply the prevalence of such a size-dependent transition in lithiation mechanism among intercalation compounds whose lithium miscibility gaps are associated with a prominent size effect, and therefore provide important guidelines for designing high-power electrodes, especially cathodes.« less

Evaluation of the local homogeneity fluctuation of sinter of the small chip size MLCCs by means of mid-infrared spectroscopy

NASA Astrophysics Data System (ADS)

Tsuzuku, Koichiro; Hagiwara, Tomoya; Takeoka, Shunsuke; Ikemoto, Yuka

2008-05-01

Vibration bands of dielectric ceramics appear at a mid-infrared (MIR) and those position and shape are changed owing to change environment of crystal lattice. Therefore, micro-focus MIR spectroscopy is a one of useful tool to evaluate very small size capacitor (e.g. smaller than 0.5 mm in chip size). Very small size multi-layer capacitor: MLCC are one of very important device to produce high quality electrical products such as cell phone, etc. Quality and reliability of MLCC are corresponding to not only average dielectric properties but also local fluctuation of them. Furthermore, local fluctuation of dielectric properties of MLCC could evaluate with MIR spectroscopy. It is possible to obtain a satisfied MIR spectrum from small size samples performed by a micro-focus spectrometer combined with synchrotron radiation as a high luminance light source at beam line BL43IR of SPring-8. From the above result, it is possible to evaluate the degree of homogeneity by comparing the shape change of Ti-O peak on IR spectra.

In Situ Observation of Single-Phase Lithium Intercalation in Sub-25-nm Nanoparticles

DOE PAGES

Zhong, Li; Liu, Yang; Han, Wei-Qiang; ...

2017-05-05

Although a non-equilibrium single-phase reaction, with the absence of nucleation and growth of a second phase, is believed to be a key factor for high-rate performance of lithium-ion batteries, it is thermodynamically unfavorable and usually proceeds in electrode materials with small particle sizes (tens of nanometers). Unfortunately, the phase evolutions inside such small particles are often shrouded by the macroscopic inhomogeneous reactions of electrodes containing millions of particles, leading to intensive debate over the size-dependent microscopic reaction mechanisms. Here, we provide a generally applicable methodology based on in-situ electron diffraction study on a multi-particle system to track the lithiation pathwaysmore » in individual nanoparticles, and unambiguously reveal that lithiation of anatase TiO 2, previously long believed to be biphasic, converts to a single-phase reaction when the particle size is below ~25 nm. Our results imply the prevalence of such a size-dependent transition in lithiation mechanism among intercalation compounds whose lithium miscibility gaps are associated with a prominent size effect, and therefore provide important guidelines for designing high-power electrodes, especially cathodes.« less

Form features provide a cue to the angular velocity of rotating objects

PubMed Central

Blair, Christopher David; Goold, Jessica; Killebrew, Kyle; Caplovitz, Gideon Paul

2013-01-01

As an object rotates, each location on the object moves with an instantaneous linear velocity dependent upon its distance from the center of rotation, while the object as a whole rotates with a fixed angular velocity. Does the perceived rotational speed of an object correspond to its angular velocity, linear velocities, or some combination of the two? We had observers perform relative speed judgments of different sized objects, as changing the size of an object changes the linear velocity of each location on the object’s surface, while maintaining the object’s angular velocity. We found that the larger a given object is, the faster it is perceived to rotate. However, the observed relationships between size and perceived speed cannot be accounted for simply by size-related changes in linear velocity. Further, the degree to which size influences perceived rotational speed depends on the shape of the object. Specifically, perceived rotational speeds of objects with corners or regions of high contour curvature were less affected by size. The results suggest distinct contour features, such as corners or regions of high or discontinuous contour curvature, provide cues to the angular velocity of a rotating object. PMID:23750970

Form features provide a cue to the angular velocity of rotating objects.

PubMed

Blair, Christopher David; Goold, Jessica; Killebrew, Kyle; Caplovitz, Gideon Paul

2014-02-01

As an object rotates, each location on the object moves with an instantaneous linear velocity, dependent upon its distance from the center of rotation, whereas the object as a whole rotates with a fixed angular velocity. Does the perceived rotational speed of an object correspond to its angular velocity, linear velocities, or some combination of the two? We had observers perform relative speed judgments of different-sized objects, as changing the size of an object changes the linear velocity of each location on the object's surface, while maintaining the object's angular velocity. We found that the larger a given object is, the faster it is perceived to rotate. However, the observed relationships between size and perceived speed cannot be accounted for simply by size-related changes in linear velocity. Further, the degree to which size influences perceived rotational speed depends on the shape of the object. Specifically, perceived rotational speeds of objects with corners or regions of high-contour curvature were less affected by size. The results suggest distinct contour features, such as corners or regions of high or discontinuous contour curvature, provide cues to the angular velocity of a rotating object. PsycINFO Database Record (c) 2014 APA, all rights reserved.

Advanced stratified charge rotary aircraft engine design study

NASA Technical Reports Server (NTRS)

Badgley, P.; Berkowitz, M.; Jones, C.; Myers, D.; Norwood, E.; Pratt, W. B.; Ellis, D. R.; Huggins, G.; Mueller, A.; Hembrey, J. H.

1982-01-01

A technology base of new developments which offered potential benefits to a general aviation engine was compiled and ranked. Using design approaches selected from the ranked list, conceptual design studies were performed of an advanced and a highly advanced engine sized to provide 186/250 shaft Kw/HP under cruise conditions at 7620/25,000 m/ft altitude. These are turbocharged, direct-injected stratified charge engines intended for commercial introduction in the early 1990's. The engine descriptive data includes tables, curves, and drawings depicting configuration, performance, weights and sizes, heat rejection, ignition and fuel injection system descriptions, maintenance requirements, and scaling data for varying power. An engine-airframe integration study of the resulting engines in advanced airframes was performed on a comparative basis with current production type engines. The results show airplane performance, costs, noise & installation factors. The rotary-engined airplanes display substantial improvements over the baseline, including 30 to 35% lower fuel usage.

Computer-aided analysis of star shot films for high-accuracy radiation therapy treatment units

NASA Astrophysics Data System (ADS)

Depuydt, Tom; Penne, Rudi; Verellen, Dirk; Hrbacek, Jan; Lang, Stephanie; Leysen, Katrien; Vandevondel, Iwein; Poels, Kenneth; Reynders, Truus; Gevaert, Thierry; Duchateau, Michael; Tournel, Koen; Boussaer, Marlies; Cosentino, Dorian; Garibaldi, Cristina; Solberg, Timothy; De Ridder, Mark

2012-05-01

As mechanical stability of radiation therapy treatment devices has gone beyond sub-millimeter levels, there is a rising demand for simple yet highly accurate measurement techniques to support the routine quality control of these devices. A combination of using high-resolution radiosensitive film and computer-aided analysis could provide an answer. One generally known technique is the acquisition of star shot films to determine the mechanical stability of rotations of gantries and the therapeutic beam. With computer-aided analysis, mechanical performance can be quantified as a radiation isocenter radius size. In this work, computer-aided analysis of star shot film is further refined by applying an analytical solution for the smallest intersecting circle problem, in contrast to the gradient optimization approaches used until today. An algorithm is presented and subjected to a performance test using two different types of radiosensitive film, the Kodak EDR2 radiographic film and the ISP EBT2 radiochromic film. Artificial star shots with a priori known radiation isocenter size are used to determine the systematic errors introduced by the digitization of the film and the computer analysis. The estimated uncertainty on the isocenter size measurement with the presented technique was 0.04 mm (2σ) and 0.06 mm (2σ) for radiographic and radiochromic films, respectively. As an application of the technique, a study was conducted to compare the mechanical stability of O-ring gantry systems with C-arm-based gantries. In total ten systems of five different institutions were included in this study and star shots were acquired for gantry, collimator, ring, couch rotations and gantry wobble. It was not possible to draw general conclusions about differences in mechanical performance between O-ring and C-arm gantry systems, mainly due to differences in the beam-MLC alignment procedure accuracy. Nevertheless, the best performing O-ring system in this study, a BrainLab/MHI Vero system, and the best performing C-arm system, a Varian Truebeam system, showed comparable mechanical performance: gantry isocenter radius of 0.12 and 0.09 mm, respectively, ring/couch rotation of below 0.10 mm for both systems and a wobble of 0.06 and 0.18 mm, respectively. The methodology described in this work can be used to monitor mechanical performance constancy of high-accuracy treatment devices, with means available in a clinical radiation therapy environment.

Mass and size growth of early-type galaxies by dry mergers in cluster environments

NASA Astrophysics Data System (ADS)

Oogi, Taira; Habe, Asao; Ishiyama, Tomoaki

2016-02-01

We perform dry merger simulations to investigate the role of dry mergers in the size growth of early-type galaxies in high-density environments. We replace the virialized dark matter haloes obtained by a large cosmological N-body simulation with N-body galaxy models consisting of two components, a stellar bulge and a dark matter halo, which have higher mass resolution than the cosmological simulation. We then resimulate nine cluster-forming regions, whose masses range from 1 × 1014 to 5 × 1014 M⊙. Masses and sizes of stellar bulges are also assumed to satisfy the stellar mass-size relation of high-z compact massive early-type galaxies. We find that dry major mergers considerably contribute to the mass and size growth of central massive galaxies. One or two dry major mergers double the average stellar mass and quadruple the average size between z = 2 and 0. These growths favourably agree with observations. Moreover, the density distributions of our simulated central massive galaxies grow from the inside-out, which is consistent with recent observations. The mass-size evolution is approximated as R∝ M_{{ast }}^{α }, with α ˜ 2.24. Most of our simulated galaxies are efficiently grown by dry mergers, and their stellar mass-size relations match the ones observed in the local Universe. Our results show that the central galaxies in the cluster haloes are potential descendants of high-z (z ˜ 2-3) compact massive early-type galaxies. This conclusion is consistent with previous numerical studies which investigate the formation and evolution of compact massive early-type galaxies.

Reduction of Specimen Size for the Full Simultaneous Characterization of Thermoelectric Performance

NASA Astrophysics Data System (ADS)

Vasilevskiy, D.; Simard, J.-M.; Masut, R. A.; Turenne, S.

2017-05-01

The successful implementation of thermoelectric (TE) materials for waste heat recovery depends strongly on our ability to increase their performance. This challenge continues to generate a renewed interest in novel high TE performance compounds. The technological difficulties in producing homogeneous ingots of new compounds or alloys with regular shape and a size sufficiently large to prepare several samples that are usually needed for a separate measurement of all TE parameters are well known. It creates a situation whereby material performance could be critically over- or under-evaluated at the first stages of the research process of a new material. Both cases would equally lead to negative consequences. Thus, minimizing the specimen size yet keeping it adequate for accurate material characterization becomes extremely important. In this work we report the experimental validation of reliable simultaneous measurements of the four most relevant TE parameters on a single bismuth telluride alloy based specimen of 4 mm × 4 mm × 1.4 mm in size. This translates in roughly 140 mg in weight for one of the heaviest TE materials, as was used in this study, and <100 mg for most others. Our validation is based on comparative measurements performed by a Harman apparatus (ZT-Scanner) on a series of differently sized specimens of hot extruded bismuth telluride based alloys. The Seebeck coefficient, electrical resistivity, thermal conductivity and the figure of merit were simultaneously assessed from 300 K to 440 K with increments of 20 K, 15 K, 10 K, 5 K, and 1 K. Our choice of a well-known homogeneous material has been made to increase measurement reliability and accuracy, but the results are expected to be valid for the full TE characterization of any unknown material. These results show a way to significantly decrease specimen sizes which has the potential to accelerate investigation of novel TE materials for large scale waste heat recovery.

Performance of two-stage fan with larger dampers on first-stage rotor

NASA Technical Reports Server (NTRS)

Urasek, D. C.; Cunnan, W. S.; Stevans, W.

1979-01-01

The performance of a two stage, high pressure-ratio fan, having large, part-span vibration dampers on the first stage rotor is presented and compared with an identical aerodynamically designed fan having smaller dampers. Comparisons of the data for the two damper configurations show that with increased damper size: (1) very high losses in the damper region reduced overall efficiency of first stage rotor by approximately 3 points, (2) the overall performance of each blade row, downstream of the damper was not significantly altered, although appreciable differences in the radial distributions of various performance parameters were noted, and (3) the lower performance of the first stage rotor decreased the overall fan efficiency more than 1 percentage point.

Tackle technique and tackle-related injuries in high-level South African Rugby Union under-18 players: real-match video analysis.

PubMed

Burger, Nicholas; Lambert, Michael I; Viljoen, Wayne; Brown, James C; Readhead, Clint; Hendricks, Sharief

2016-08-01

The high injury rate associated with rugby union is primarily due to the tackle, and poor contact technique has been identified as a risk factor for injury. We aimed to determine whether the tackle technique proficiency scores were different in injurious tackles versus tackles that did not result in injury using real-match scenarios in high-level youth rugby union. Injury surveillance was conducted at the under-18 Craven Week tournaments (2011-2013). Tackle-related injury information was used to identify injury events in the match video footage and non-injury events were identified for the injured player cohort. Injury and non-injury events were scored for technique proficiency and Cohen's effect sizes were calculated and the Student t test (p<0.05) was performed to compare injury versus non-injury scores. The overall mean score for front-on ball-carrier proficiency was 7.17±1.90 and 9.02±2.15 for injury and non-injury tackle events, respectively (effect size=moderate; p<0.05). The overall mean score for side/behind ball-carrier proficiency was 4.09±2.12 and 7.68±1.72 for injury and non-injury tackle events, respectively (effect size=large; p<0.01). The overall mean score for front-on tackler proficiency was 7.00±1.95 and 9.35±2.56 for injury and non-injury tackle events, respectively (effect size=moderate; p<0.05). The overall mean score for side/behind tackler proficiency was 5.47±1.60 and 8.14±1.75 for injury and non-injury tackle events, respectively (effect size=large; p<0.01). Higher overall mean and criterion-specific tackle-related technique scores were associated with a non-injury outcome. The ability to perform well during tackle events may decrease the risk of injury and may manifest in superior performance. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

Do team processes really have an effect on clinical performance? A systematic literature review.

PubMed

Schmutz, J; Manser, T

2013-04-01

There is a growing literature on the relationship between team processes and clinical performance. The purpose of this review is to summarize these articles and examine the impact of team process behaviours on clinical performance. We conducted a literature search in five major databases. Inclusion criteria were: English peer-reviewed papers published between January 2001 and May 2012, which showed or tried to show (i) a statistical relationship of a team process variable and clinical performance or (ii) an improvement of a performance variable through a team process intervention. Study quality was assessed using predefined quality indicators. For every study, we calculated the relevant effect sizes. We included 28 studies in the review, seven of which were intervention studies. Every study reported at least one significant relationship between team processes or an intervention and performance. Also, some non-significant effects were reported. Most of the reported effect sizes were large or medium. The study quality ranged from medium to high. The studies are highly diverse regarding the specific team process behaviours investigated and also regarding the methods used. However, they suggest that team process behaviours do influence clinical performance and that training results in increased performance. Future research should rely on existing theoretical frameworks, valid, and reliable methods to assess processes such as teamwork or coordination and focus on the development of adequate tools to assess process performance, linking them with outcomes in the clinical setting.

Airborne fungi in low and high allergic prevalence child care centers

NASA Astrophysics Data System (ADS)

Zuraimi, M. S.; Fang, L.; Tan, T. K.; Chew, F. T.; Tham, K. W.

Fungi exposure has been linked to asthma and allergies among children. To determine the association between fungal exposure and wheeze and rhinitis symptoms, we examined concentrations of culturable indoor and outdoor fungi of various aerodynamic sizes in low and high allergic prevalence child care centers (CCCs) in Singapore. Environmental parameters were also performed for air temperature, relative humidity and ventilation rates, while information on CCC characteristics was collected via an inspection. Most commonly recovered fungi were Penicillium, Aspergillus, Geotrichum, Cladosporium and sterile mycelia with Geotrichum and sterile mycelia amounting to an average of 71.5% of the total airborne culturable fungi studied. Indoor and outdoor total culturable fungi concentrations and those in the size range of 1.1-3.3 μm were significantly higher in high allergic prevalence CCCs. When fungal types/genera were compared, indoor and outdoor Geotrichum and sterile mycelia of aerodynamic sizes 1.1-3.3 μm were found to be significantly elevated in high allergic prevalence CCCs. Indeed, average geometric mean diameters ( Dg, ave) of indoor and outdoor culturable fungi were consistently smaller in CCCs with high prevalence of allergies than those with low prevalence. We found significant associations of higher fungal concentrations, especially those with smaller aerodynamic sizes in CCCs situated near parks. There were no differences in fungal levels between CCCs with respect to their dampness profile mainly due to high CCC ventilation rates. Since particle size is a factor that determines where a fungi particle deposits in the respiratory tract, this study provides useful information in the etiology of wheeze and rhinitis symptoms among the CCC attending children.

Fuel properties effect on the performance of a small high temperature rise combustor

NASA Technical Reports Server (NTRS)

Acosta, Waldo A.; Beckel, Stephen A.

1989-01-01

The performance of an advanced small high temperature rise combustor was experimentally determined at NASA-Lewis. The combustor was designed to meet the requirements of advanced high temperature, high pressure ratio turboshaft engines. The combustor featured an advanced fuel injector and an advanced segmented liner design. The full size combustor was evaluated at power conditions ranging from idle to maximum power. The effect of broad fuel properties was studied by evaluating the combustor with three different fuels. The fuels used were JP-5, a blend of Diesel Fuel Marine/Home Heating Oil, and a blend of Suntec C/Home Heating Oil. The fuel properties effect on the performance of the combustion in terms of pattern factor, liner temperatures, and exhaust emissions are documented.

A performance comparison of ultrasonically aided electric propulsion extractor configurations

NASA Astrophysics Data System (ADS)

Dong, L.; Song, W.; Kang, X. M.; Zhao, W. S.

2012-08-01

As a novel propulsion technology, ultrasonically aided electric propulsion (UAEP) offers a high specific impulse and a high thrust density. In this paper, the effects of extractor grid configuration on performance of a UAEP thruster have been investigated by both experimental studies and numerical simulation. Relationships between spray current and operation parameters, including applied voltage, propellant flow rate, and vibration power and frequency, are explored for different extractor mesh sizes and shapes. Numerical simulation is also carried out for a better understanding of the formation of capillary standing waves as well as the electric field distribution in the acceleration zone. Experimental results show that compared with a circular shaped extractor, a reticular shaped extractor is able to produce a higher spray current. The current density increases with a denser mesh, which agrees well with the numerical simulation results. This phenomenon indicates that optimizing extractors with appropriate shapes and sizes can be an effective way to improve the performance of a UAEP system. A performance evaluation based on hydrodynamic and electrostatic calculations indicates that the present UAEP system can produce a thrust competitive to that of the colloid thruster with an emitter array.

A rapid method for optimization of the rocket propulsion system for single-stage-to-orbit vehicles

NASA Technical Reports Server (NTRS)

Eldred, C. H.; Gordon, S. V.

1976-01-01

A rapid analytical method for the optimization of rocket propulsion systems is presented for a vertical take-off, horizontal landing, single-stage-to-orbit launch vehicle. This method utilizes trade-offs between propulsion characteristics affecting flight performance and engine system mass. The performance results from a point-mass trajectory optimization program are combined with a linearized sizing program to establish vehicle sizing trends caused by propulsion system variations. The linearized sizing technique was developed for the class of vehicle systems studied herein. The specific examples treated are the optimization of nozzle expansion ratio and lift-off thrust-to-weight ratio to achieve either minimum gross mass or minimum dry mass. Assumed propulsion system characteristics are high chamber pressure, liquid oxygen and liquid hydrogen propellants, conventional bell nozzles, and the same fixed nozzle expansion ratio for all engines on a vehicle.

Design of an occulter testbed at flight Fresnel numbers

NASA Astrophysics Data System (ADS)

Sirbu, Dan; Kasdin, N. Jeremy; Kim, Yunjong; Vanderbei, Robert J.

2015-01-01

An external occulter is a spacecraft flown along the line-of-sight of a space telescope to suppress starlight and enable high-contrast direct imaging of exoplanets. Laboratory verification of occulter designs is necessary to validate the optical models used to design and predict occulter performance. At Princeton, we are designing and building a testbed that allows verification of scaled occulter designs whose suppressed shadow is mathematically identical to that of space occulters. Here, we present a sample design operating at a flight Fresnel number and is thus representative of a realistic space mission. We present calculations of experimental limits arising from the finite size and propagation distance available in the testbed, limitations due to manufacturing feature size, and non-ideal input beam. We demonstrate how the testbed is designed to be feature-size limited, and provide an estimation of the expected performance.

Synthesis and electrochemical property of LiCoO 2 thin films composed of nanosize compounds synthesized via nanosheet restacking method

NASA Astrophysics Data System (ADS)

Quan, Zhen; Iwase, Kosuke; Sonoyama, Noriyuki

LiCoO 2 thin films with nanosize particles were synthesized on Au substrates by nanosheet restacking method and subsequent hydrothermal reaction which needs less cost than the vacuum deposition methods. The grain size of LiCoO 2 films estimated by XRD reflection was about 15 nm that was independent of the thickness of precursor cobalt hydroxide film. Comparing the rate performance of the thin films with various thickness, the optimum performance was obtained by the thin film with 5 min deposition time: 62% of the capacity was held at 400 C-rate compared with that at 20 C-rate. The results of AC-impedance analysis of electrode reaction indicate that the high rate capability of the LiCoO 2 film is obtained by the small grain size and large surface area of LiCoO 2 thin film with nano size particles.

Inductive voltage adder advanced hydrodynamic radiographic technology demonstration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mazarakis, M.G.; Poukey, J.W.; Maenchen

This paper presents the design, results, and analysis of a high-brightness electron beam technology demonstration experiment completed at Sandia National Laboratories, performed in collaboration with Los Alamos National Laboratory. The anticipated electron beam parameters were: 12 MeV, 35-40 kA, 0.5-mm rms radius, and 40-ns full width half maximum (FWHM) pulse duration. This beam, on an optimum thickness tantalum converter, should produce a very intense x-ray source of {approximately} 1.5-mm spot size and 1 kR dose @ 1 m. The accelerator utilized was SABRE, a pulsed inductive voltage adder, and the electron source was a magnetically immersed foilless electron diode. Formore » these experiments, SABRE was modified to high-impedance negative-polarity operation. A new 100-ohm magnetically insulated transmission line cathode electrode was designed and constructed; the cavities were rotated 180{degrees} poloidally to invert the central electrode polarity to negative; and only one of the two pulse forming lines per cavity was energized. A twenty- to thirty-Tesla solenoidal magnet insulated the diode and contained the beam at its extremely small size. These experiments were designed to demonstrate high electron currents in submillimeter radius beams resulting in a high-brightness high-intensity flash x-ray source for high-resolution thick-object hydrodynamic radiography. The SABRE facility high-impedance performance was less than what was hoped. The modifications resulted in a lower amplitude (9 MV), narrower-than-anticipated triangular voltage pulse, which limited the dose to {approximately} 20% of the expected value. In addition, halo and ion-hose instabilities increased the electron beam spot size to > 1.5 mm. Subsequent, more detailed calculations explain these reduced output parameters. An accelerator designed (versus retrofit) for this purpose would provide the desired voltage and pulse shape.« less

Feasibility and reliability of pocket-size ultrasound examinations of the pleural cavities and vena cava inferior performed by nurses in an outpatient heart failure clinic.

PubMed

Dalen, Havard; Gundersen, Guri H; Skjetne, Kyrre; Haug, Hilde H; Kleinau, Jens O; Norekval, Tone M; Graven, Torbjorn

2015-08-01

Routine assessment of volume state by ultrasound may improve follow-up of heart failure patients. We aimed to study the feasibility and reliability of focused pocket-size ultrasound examinations of the pleural cavities and the inferior vena cava performed by nurses to assess volume state at an outpatient heart failure clinic. Ultrasound examinations were performed in 62 included heart failure patients by specialized nurses with a pocket-size imaging device (PSID). Patients were then re-examined by a cardiologist with a high-end scanner for reference within 1 h. Specialized nurses were able to obtain and interpret images from both pleural cavities and the inferior vena cava and estimate the volume status in all patients. Time consumption for focused ultrasound examination was median 5 min. In total 26 patients had any kind of pleural effusion (in 39 pleural cavities) by reference. The sensitivity, specificity, positive and negative predictive values were high, all ≥ 92%. The correlations with reference were high for all measurements, all r ≥ 0.79. Coefficients of variation for end-expiratory dimension of inferior vena cava and quantification of pleural effusion were 10.8% and 12.7%, respectively. Specialized nurses were, after a dedicated training protocol, able to obtain reliable recordings of both pleural cavities and the inferior vena cava by PSID and interpret the images in a reliable way. Implementing focused ultrasound examinations to assess volume status by nurses in an outpatient heart failure clinic may improve diagnostics, and thus improve therapy. © The European Society of Cardiology 2014.

On mechanics and material length scales of failure in heterogeneous interfaces using a finite strain high performance solver

NASA Astrophysics Data System (ADS)

Mosby, Matthew; Matouš, Karel

2015-12-01

Three-dimensional simulations capable of resolving the large range of spatial scales, from the failure-zone thickness up to the size of the representative unit cell, in damage mechanics problems of particle reinforced adhesives are presented. We show that resolving this wide range of scales in complex three-dimensional heterogeneous morphologies is essential in order to apprehend fracture characteristics, such as strength, fracture toughness and shape of the softening profile. Moreover, we show that computations that resolve essential physical length scales capture the particle size-effect in fracture toughness, for example. In the vein of image-based computational materials science, we construct statistically optimal unit cells containing hundreds to thousands of particles. We show that these statistically representative unit cells are capable of capturing the first- and second-order probability functions of a given data-source with better accuracy than traditional inclusion packing techniques. In order to accomplish these large computations, we use a parallel multiscale cohesive formulation and extend it to finite strains including damage mechanics. The high-performance parallel computational framework is executed on up to 1024 processing cores. A mesh convergence and a representative unit cell study are performed. Quantifying the complex damage patterns in simulations consisting of tens of millions of computational cells and millions of highly nonlinear equations requires data-mining the parallel simulations, and we propose two damage metrics to quantify the damage patterns. A detailed study of volume fraction and filler size on the macroscopic traction-separation response of heterogeneous adhesives is presented.

High-efficiency single cell encapsulation and size selective capture of cells in picoliter droplets based on hydrodynamic micro-vortices.

PubMed

Kamalakshakurup, Gopakumar; Lee, Abraham P

2017-12-05

Single cell analysis has emerged as a paradigm shift in cell biology to understand the heterogeneity of individual cells in a clone for pathological interrogation. Microfluidic droplet technology is a compelling platform to perform single cell analysis by encapsulating single cells inside picoliter-nanoliter (pL-nL) volume droplets. However, one of the primary challenges for droplet based single cell assays is single cell encapsulation in droplets, currently achieved either randomly, dictated by Poisson statistics, or by hydrodynamic techniques. In this paper, we present an interfacial hydrodynamic technique which initially traps the cells in micro-vortices, and later releases them one-to-one into the droplets, controlled by the width of the outer streamline that separates the vortex from the flow through the streaming passage adjacent to the aqueous-oil interface (d gap ). One-to-one encapsulation is achieved at a d gap equal to the radius of the cell, whereas complete trapping of the cells is realized at a d gap smaller than the radius of the cell. The unique feature of this technique is that it can perform 1. high efficiency single cell encapsulations and 2. size-selective capturing of cells, at low cell loading densities. Here we demonstrate these two capabilities with a 50% single cell encapsulation efficiency and size selective separation of platelets, RBCs and WBCs from a 10× diluted blood sample (WBC capture efficiency at 70%). The results suggest a passive, hydrodynamic micro-vortex based technique capable of performing high-efficiency single cell encapsulation for cell based assays.

High correlations between MRI brain volume measurements based on NeuroQuant® and FreeSurfer.

PubMed

Ross, David E; Ochs, Alfred L; Tate, David F; Tokac, Umit; Seabaugh, John; Abildskov, Tracy J; Bigler, Erin D

2018-05-30

NeuroQuant ® (NQ) and FreeSurfer (FS) are commonly used computer-automated programs for measuring MRI brain volume. Previously they were reported to have high intermethod reliabilities but often large intermethod effect size differences. We hypothesized that linear transformations could be used to reduce the large effect sizes. This study was an extension of our previously reported study. We performed NQ and FS brain volume measurements on 60 subjects (including normal controls, patients with traumatic brain injury, and patients with Alzheimer's disease). We used two statistical approaches in parallel to develop methods for transforming FS volumes into NQ volumes: traditional linear regression, and Bayesian linear regression. For both methods, we used regression analyses to develop linear transformations of the FS volumes to make them more similar to the NQ volumes. The FS-to-NQ transformations based on traditional linear regression resulted in effect sizes which were small to moderate. The transformations based on Bayesian linear regression resulted in all effect sizes being trivially small. To our knowledge, this is the first report describing a method for transforming FS to NQ data so as to achieve high reliability and low effect size differences. Machine learning methods like Bayesian regression may be more useful than traditional methods. Copyright © 2018 Elsevier B.V. All rights reserved.

Effects of device size and material on the bending performance of resistive-switching memory devices fabricated on flexible substrates

NASA Astrophysics Data System (ADS)

Lee, Won-Ho; Yoon, Sung-Min

2017-05-01

The resistive change memory (RCM) devices using amorphous In-Ga-Zn-O (IGZO) and microcrystalline Al-doped ZnO (AZO) thin films were fabricated on plastic substrates and characterized for flexible electronic applications. The device cell sizes were varied to 25 × 25, 50 × 50, 100 × 100, and 200 × 200 μm2 to examine the effects of cell size on the resistive-switching (RS) behaviors at a flat state and under bending conditions. First, it was found that the high-resistance state programmed currents markedly increased with the increase in the cell size. Second, while the AZO RCM devices did not exhibit RESET operations at a curvature radius smaller than 8.0 mm, the IGZO RCM devices showed sound RS behaviors even at a curvature radius of 4.5 mm. Third, for the IGZO RCM devices with the cell size bigger than 100 × 100 μm2, the RESET operation could not be performed at a curvature radius smaller than 6.5 mm. Thus, it was elucidated that the RS characteristics of the flexible RCM devices using oxide semiconductor thin films were closely related to the types of RS materials and the cell size of the device.

FPGA platform for MEMS Disc Resonance Gyroscope (DRG) control

NASA Astrophysics Data System (ADS)

Keymeulen, Didier; Peay, Chris; Foor, David; Trung, Tran; Bakhshi, Alireza; Withington, Phil; Yee, Karl; Terrile, Rich

2008-04-01

Inertial navigation systems based upon optical gyroscopes tend to be expensive, large, power consumptive, and are not long lived. Micro-Electromechanical Systems (MEMS) based gyros do not have these shortcomings; however, until recently, the performance of MEMS based gyros had been below navigation grade. Boeing and JPL have been cooperating since 1997 to develop high performance MEMS gyroscopes for miniature, low power space Inertial Reference Unit applications. The efforts resulted in demonstration of a Post Resonator Gyroscope (PRG). This experience led to the more compact Disc Resonator Gyroscope (DRG) for further reduced size and power with potentially increased performance. Currently, the mass, volume and power of the DRG are dominated by the size of the electronics. This paper will detail the FPGA based digital electronics architecture and its implementation for the DRG which will allow reduction of size and power and will increase performance through a reduction in electronics noise. Using the digital control based on FPGA, we can program and modify in real-time the control loop to adapt to the specificity of each particular gyro and the change of the mechanical characteristic of the gyro during its life time.

Quantitative assessment of joint position sense recovery in subacute stroke patients: a pilot study.

PubMed

Kattenstroth, Jan-Christoph; Kalisch, Tobias; Kowalewski, Rebecca; Tegenthoff, Martin; Dinse, Hubert R

2013-11-01

To assess joint position sense performance in subacute stroke patients using a novel quantitative assessment. Proof-of-principle pilot study with a group of subacute stroke patients. Assessment at baseline and after 2 weeks of intervention. Additional data for a healthy age-matched control group. Ten subacute stroke patients (aged 65.41 years (standard deviation 2.5), 4 females, 2.3 weeks (standard deviation 0.2)) post-stroke receiving in-patient standard rehabilitation and repetitive electrical stimulation of the affected hand. Joint position sense was assessed based on the ability of correctly perceiving the opening angles of the finger joints. Patients had to report size differences of polystyrene balls of various sizes, whilst the balls were enclosed simultaneously by the affected and the non-affected hands. A total of 21 pairwise size comparisons was used to quantify joint position performance. After 2 weeks of therapeutic intervention a significant improvement in joint position sense performance was observed; however, the performance level was still below that of a healthy control group. The results indicate high feasibility and sensitivity of the joint position test in subacute stroke patients. Testing allowed quantification of both the deficit and the rehabilitation outcome.

Particle size analysis of sediments, soils and related particulate materials for forensic purposes using laser granulometry.

PubMed

Pye, Kenneth; Blott, Simon J

2004-08-11

Particle size is a fundamental property of any sediment, soil or dust deposit which can provide important clues to nature and provenance. For forensic work, the particle size distribution of sometimes very small samples requires precise determination using a rapid and reliable method with a high resolution. The Coulter trade mark LS230 laser granulometer offers rapid and accurate sizing of particles in the range 0.04-2000 microm for a variety of sample types, including soils, unconsolidated sediments, dusts, powders and other particulate materials. Reliable results are possible for sample weights of just 50 mg. Discrimination between samples is performed on the basis of the shape of the particle size curves and statistical measures of the size distributions. In routine forensic work laser granulometry data can rarely be used in isolation and should be considered in combination with results from other techniques to reach an overall conclusion.

Intercomparison and Evaluation of Global Aerosol Microphysical Properties Among Aerocom Models of a Range of Complexity

NASA Technical Reports Server (NTRS)

Mann, G. W.; Carslaw, K. S.; Reddington, C. L.; Pringle, K. J.; Schulz, M.; Asmi, A.; Spracklen, D. V.; Ridley, D. A.; Woodhouse, M. T.; Lee, L. A.;

Microstructure and thermal conductivity of surfactant-free NiO nanostructures

NASA Astrophysics Data System (ADS)

Sahoo, Pranati; Misra, Dinesh K.; Salvador, Jim; Makongo, Julien P. A.; Chaubey, Girija S.; Takas, Nathan J.; Wiley, John B.; Poudeu, Pierre F. P.

2012-06-01

High purity, nanometer sized surfactant-free nickel oxide (NiO) particles were produced in gram scale using a solution combustion method and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), gas pycnometry and gas adsorption analysis (BET). The average particle size of the as-synthesized NiO increases significantly with the preheating temperature of the furnace, while the specific surface area decreases. A BET specific surface area of ∼100 m2/g was obtained for NiO nanoparticles with size as small as 3 nm synthesized at 300 °C. The thermal conductivity (κ) of pressed pellets of the synthesized NiO nanoparticles obtained using spark plasma sintering (SPS) and uniaxial hot pressing is drastically decreased (∼60%) compared to that of NiO single crystal. This strong reduction in κ with particle size suggests the suitability of the synthesized surfactant-free NiO nanoparticles for use as nanoinclusions when designing high performance materials for waste heat recovery.

Origin of Capacity Fading in Nano-Sized Co3O4 Electrodes: Electrochemical Impedance Spectroscopy Study

NASA Astrophysics Data System (ADS)

Kang, Jin-Gu; Ko, Young-Dae; Park, Jae-Gwan; Kim, Dong-Wan

2008-10-01

Transition metal oxides have been suggested as innovative, high-energy electrode materials for lithium-ion batteries because their electrochemical conversion reactions can transfer two to six electrons. However, nano-sized transition metal oxides, especially Co3O4, exhibit drastic capacity decay during discharge/charge cycling, which hinders their practical use in lithium-ion batteries. Herein, we prepared nano-sized Co3O4 with high crystallinity using a simple citrate-gel method and used electrochemical impedance spectroscopy method to examine the origin for the drastic capacity fading observed in the nano-sized Co3O4 anode system. During cycling, AC impedance responses were collected at the first discharged state and at every subsequent tenth discharged state until the 100th cycle. By examining the separable relaxation time of each electrochemical reaction and the goodness-of-fit results, a direct relation between the charge transfer process and cycling performance was clearly observed.

Analysis-Preserving Video Microscopy Compression via Correlation and Mathematical Morphology

PubMed Central

Shao, Chong; Zhong, Alfred; Cribb, Jeremy; Osborne, Lukas D.; O’Brien, E. Timothy; Superfine, Richard; Mayer-Patel, Ketan; Taylor, Russell M.

2015-01-01

The large amount video data produced by multi-channel, high-resolution microscopy system drives the need for a new high-performance domain-specific video compression technique. We describe a novel compression method for video microscopy data. The method is based on Pearson's correlation and mathematical morphology. The method makes use of the point-spread function (PSF) in the microscopy video acquisition phase. We compare our method to other lossless compression methods and to lossy JPEG, JPEG2000 and H.264 compression for various kinds of video microscopy data including fluorescence video and brightfield video. We find that for certain data sets, the new method compresses much better than lossless compression with no impact on analysis results. It achieved a best compressed size of 0.77% of the original size, 25× smaller than the best lossless technique (which yields 20% for the same video). The compressed size scales with the video's scientific data content. Further testing showed that existing lossy algorithms greatly impacted data analysis at similar compression sizes. PMID:26435032

Randomised controlled trial to assess the effect of a Just-in-Time training on procedural performance: a proof-of-concept study to address procedural skill decay.

PubMed

Branzetti, Jeremy B; Adedipe, Adeyinka A; Gittinger, Matthew J; Rosenman, Elizabeth D; Brolliar, Sarah; Chipman, Anne K; Grand, James A; Fernandez, Rosemarie

2017-11-01

A subset of high-risk procedures present significant safety threats due to their (1) infrequent occurrence, (2) execution under time constraints and (3) immediate necessity for patient survival. A Just-in-Time (JIT) intervention could provide real-time bedside guidance to improve high-risk procedural performance and address procedural deficits associated with skill decay. To evaluate the impact of a novel JIT intervention on transvenous pacemaker (TVP) placement during a simulated patient event. This was a prospective, randomised controlled study to determine the effect of a JIT intervention on performance of TVP placement. Subjects included board-certified emergency medicine physicians from two hospitals. The JIT intervention consisted of a portable, bedside computer-based procedural adjunct. The primary outcome was performance during a simulated patient encounter requiring TVP placement, as assessed by trained raters using a technical skills checklist. Secondary outcomes included global performance ratings, time to TVP placement, number of critical omissions and System Usability Scale scores (intervention only). Groups were similar at baseline across all outcomes. Compared with the control group, the intervention group demonstrated statistically significant improvement in the technical checklist score (11.45 vs 23.44, p<0.001, Cohen's d effect size 4.64), the global rating scale (2.27 vs 4.54, p<0.001, Cohen's d effect size 3.76), and a statistically significant reduction in critical omissions (2.23 vs 0.68, p<0.001, Cohen's d effect size -1.86). The difference in time to procedural completion was not statistically significant between conditions (11.15 min vs 12.80 min, p=0.12, Cohen's d effect size 0.65). System Usability Scale scores demonstrated excellent usability. A JIT intervention improved procedure perfromance, suggesting a role for JIT interventions in rarely performed procedures. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Optimized light sharing for high-resolution TOF PET detector based on digital silicon photomultipliers.

PubMed

Marcinkowski, R; España, S; Van Holen, R; Vandenberghe, S

2014-12-07

The majority of current whole-body PET scanners are based on pixelated scintillator arrays with a transverse pixel size of 4 mm. However, recent studies have shown that decreasing the pixel size to 2 mm can significantly improve image spatial resolution. In this study, the performance of Digital Photon Counter (DPC) from Philips Digital Photon Counting (PDPC) was evaluated to determine their potential for high-resolution whole-body time of flight (TOF) PET scanners. Two detector configurations were evaluated. First, the DPC3200-44-22 DPC array was coupled to a LYSO block of 15 × 15 2 × 2 × 22 mm(3) pixels through a 1 mm thick light guide. Due to light sharing among the dies neighbour logic of the DPC was used. In a second setup the same DPC was coupled directly to a scalable 4 × 4 LYSO matrix of 1.9 × 1.9 × 22 mm(3) crystals with a dedicated reflector arrangement allowing for controlled light sharing patterns inside the matrix. With the first approach an average energy resolution of 14.5% and an average CRT of 376 ps were achieved. For the second configuration an average energy resolution of 11% and an average CRT of 295 ps were achieved. Our studies show that the DPC is a suitable photosensor for a high-resolution TOF-PET detector. The dedicated reflector arrangement allows one to achieve better performances than the light guide approach. The count loss, caused by dark counts, is overcome by fitting the matrix size to the size of DPC single die.

Chip Scale Ultra-Stable Clocks: Miniaturized Phonon Trap Timing Units for PNT of CubeSats

NASA Technical Reports Server (NTRS)

Rais-Zadeh, Mina; Altunc, Serhat; Hunter, Roger C.; Petro, Andrew

2016-01-01

The Chip Scale Ultra-Stable Clocks (CSUSC) project aims to provide a superior alternative to current solutions for low size, weight, and power timing devices. Currently available quartz-based clocks have problems adjusting to the high temperature and extreme acceleration found in space applications, especially when scaled down to match small spacecraft size, weight, and power requirements. The CSUSC project aims to utilize dual-mode resonators on an ovenized platform to achieve the exceptional temperature stability required for these systems. The dual-mode architecture utilizes a temperature sensitive and temperature stable mode simultaneously driven on the same device volume to eliminate ovenization error while maintaining extremely high performance. Using this technology it is possible to achieve parts-per-billion (ppb) levels of temperature stability with multiple orders of magnitude smaller size, weight, and power.

A Systematic Review of Group Social Skills Interventions, and Meta-analysis of Outcomes, for Children with High Functioning ASD.

PubMed

Wolstencroft, J; Robinson, L; Srinivasan, R; Kerry, E; Mandy, W; Skuse, D

2018-07-01

Group social skills interventions (GSSIs) are a commonly offered treatment for children with high functioning ASD. We critically evaluated GSSI randomised controlled trials for those aged 6-25 years. Our meta-analysis of outcomes emphasised internal validity, thus was restricted to trials that used the parent-report social responsiveness scale (SRS) or the social skills rating system (SSRS). Large positive effect sizes were found for the SRS total score, plus the social communication and restricted interests and repetitive behaviours subscales. The SSRS social skills subscale improved with moderate effect size. Moderator analysis of the SRS showed that GSSIs that include parent-groups, and are of greater duration or intensity, obtained larger effect sizes. We recommend future trials distinguish gains in children's social knowledge from social performance.

Hydraulic limits on tree performance: transpiration, carbon gain and growth of trees

Treesearch

Melvin T. Tyree

2003-01-01

The state of knowledge concerning the influences of tree size, xylem dysfunction, growth conditions, and within-species and between species genetics is reviewed. It is concluded that high plant hydraulic conductance is necessary for high productivity in forest trees, and this being the case, the implications for commercial forestry require further study.

Precise Morphology Control and Continuous Fabrication of Perovskite Solar Cells Using Droplet-Controllable Electrospray Coating System.

PubMed

Hong, Seung Chan; Lee, Gunhee; Ha, Kyungyeon; Yoon, Jungjin; Ahn, Namyoung; Cho, Woohyung; Park, Mincheol; Choi, Mansoo

2017-03-08

Herein, we developed a novel electrospray coating system for continuous fabrication of perovskite solar cells with high performance. Our system can systemically control the size of CH 3 NH 3 PbI 3 precursor droplets by modulating the applied electrical potential, shown to be a crucial factor for the formation of perovskite films. As a result, we have obtained pinhole-free and large grain-sized perovskite solar cells, yielding the best PCE of 13.27% with little photocurrent hysteresis. Furthermore, the average PCE through the continuous coating process was 11.56 ± 0.52%. Our system demonstrates not only the high reproducibility but also a new way to commercialize high-quality perovskite solar cells.

Data for automated, high-throughput microscopy analysis of intracellular bacterial colonies using spot detection.

PubMed

Ernstsen, Christina L; Login, Frédéric H; Jensen, Helene H; Nørregaard, Rikke; Møller-Jensen, Jakob; Nejsum, Lene N

2017-10-01

Quantification of intracellular bacterial colonies is useful in strategies directed against bacterial attachment, subsequent cellular invasion and intracellular proliferation. An automated, high-throughput microscopy-method was established to quantify the number and size of intracellular bacterial colonies in infected host cells (Detection and quantification of intracellular bacterial colonies by automated, high-throughput microscopy, Ernstsen et al., 2017 [1]). The infected cells were imaged with a 10× objective and number of intracellular bacterial colonies, their size distribution and the number of cell nuclei were automatically quantified using a spot detection-tool. The spot detection-output was exported to Excel, where data analysis was performed. In this article, micrographs and spot detection data are made available to facilitate implementation of the method.

Reducing ultrafine particle emissions using air injection in wood-burning cookstoves

DOE PAGES

Rapp, Vi H.; Caubel, Julien J.; Wilson, Daniel L.; ...

2016-06-27

In order to address the health risks and climate impacts associated with pollution from cooking on biomass fires, researchers have focused on designing new cookstoves that improve cooking performance and reduce harmful emissions, specifically particulate matter (PM). One method for improving cooking performance and reducing emissions is using air injection to increase turbulence of unburned gases in the combustion zone. Although air injection reduces total PM mass emissions, the effect on PM size-distribution and number concentration has not been thoroughly investigated. Using two new wood-burning cookstove designs from Lawrence Berkeley National Laboratory, this research explores the effect of air injectionmore » on cooking performance, PM and gaseous emissions, and PM size distribution and number concentration. Both cookstoves were created using the Berkeley-Darfur Stove as the base platform to isolate the effects of air injection. The thermal performance, gaseous emissions, PM mass emissions, and particle concentrations (ranging from 5 nm to 10 μm in diameter) of the cookstoves were measured during multiple high-power cooking tests. Finally, the results indicate that air injection improves cookstove performance and reduces total PM mass but increases total ultrafine (less than 100 nm in diameter) PM concentration over the course of high-power cooking.« less

Reducing ultrafine particle emissions using air injection in wood-burning cookstoves

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rapp, Vi H.; Caubel, Julien J.; Wilson, Daniel L.

In order to address the health risks and climate impacts associated with pollution from cooking on biomass fires, researchers have focused on designing new cookstoves that improve cooking performance and reduce harmful emissions, specifically particulate matter (PM). One method for improving cooking performance and reducing emissions is using air injection to increase turbulence of unburned gases in the combustion zone. Although air injection reduces total PM mass emissions, the effect on PM size-distribution and number concentration has not been thoroughly investigated. Using two new wood-burning cookstove designs from Lawrence Berkeley National Laboratory, this research explores the effect of air injectionmore » on cooking performance, PM and gaseous emissions, and PM size distribution and number concentration. Both cookstoves were created using the Berkeley-Darfur Stove as the base platform to isolate the effects of air injection. The thermal performance, gaseous emissions, PM mass emissions, and particle concentrations (ranging from 5 nm to 10 μm in diameter) of the cookstoves were measured during multiple high-power cooking tests. Finally, the results indicate that air injection improves cookstove performance and reduces total PM mass but increases total ultrafine (less than 100 nm in diameter) PM concentration over the course of high-power cooking.« less

Effect of carbon source on the morphology and electrochemical performances of LiFePO4/C nanocomposites.

PubMed

Liu, Shuxin; Wang, Haibin; Yin, Hengbo; Wang, Hong; He, Jichuan

2014-03-01

The carbon coated LiFePO4 (LiFePO4/C) nanocomposites materials were successfully synthesized by sol-gel method. The microstructure and morphology of LiFePO4/C nanocomposites were characterized by X-ray diffraction, Raman spectroscopy and scanning electron microscopy. The results showed that the carbon layers decomposed by different dispersant and carbon source had different graphitization degree, and the sugar could decompose to form more graphite-like structure carbon. The carbon source and heat-treatment temperature had some effect on the particle size and morphology, the sample LFP-S700 synthesized by adding sugar as carbon source at 700 degrees C had smaller particle size, uniform size distribution and spherical shape. The electrochemical behavior of LiFePO4/C nanocomposites was analyzed using galvanostatic measurements and cyclic voltammetry (CV). The results showed that the sample LFP-S700 had higher discharge specific capacities, higher apparent lithium ion diffusion coefficient and lower charge transfer resistance. The excellent electrochemical performance of sample LFP-S700 could be attributed to its high graphitization degree of carbon, smaller particle size and uniform size distribution.

Assessment of air sampling methods and size distribution of virus-laden aerosols in outbreaks in swine and poultry farms.

PubMed

Alonso, Carmen; Raynor, Peter C; Goyal, Sagar; Olson, Bernard A; Alba, Anna; Davies, Peter R; Torremorell, Montserrat

2017-05-01

Swine and poultry viruses, such as porcine reproductive and respiratory syndrome virus (PRRSV), porcine epidemic diarrhea virus (PEDV), and highly pathogenic avian influenza virus (HPAIV), are economically important pathogens that can spread via aerosols. The reliability of methods for quantifying particle-associated viruses as well as the size distribution of aerosolized particles bearing these viruses under field conditions are not well documented. We compared the performance of 2 size-differentiating air samplers in disease outbreaks that occurred in swine and poultry facilities. Both air samplers allowed quantification of particles by size, and measured concentrations of PRRSV, PEDV, and HPAIV stratified by particle size both within and outside swine and poultry facilities. All 3 viruses were detectable in association with aerosolized particles. Proportions of positive sampling events were 69% for PEDV, 61% for HPAIV, and 8% for PRRSV. The highest virus concentrations were found with PEDV, followed by HPAIV and PRRSV. Both air collectors performed equally for the detection of total virus concentration. For all 3 viruses, higher numbers of RNA copies were associated with larger particles; however, a bimodal distribution of particles was observed in the case of PEDV and HPAIV.

1.9 μm superficially porous packing material with radially oriented pores and tailored pore size for ultra-fast separation of small molecules and biomolecules.

PubMed

Min, Yi; Jiang, Bo; Wu, Ci; Xia, Simin; Zhang, Xiaodan; Liang, Zhen; Zhang, Lihua; Zhang, Yukui

2014-08-22

In this work, 1.9 μm reversed-phase packing materials with superficially porous structure were prepared to achieve the rapid and high efficient separation of peptides and proteins. The silica particles were synthesized via three steps, nonporous silica particle preparation by a modified seeded growth method, mesoporous shell formation by a one pot templated dissolution and redeposition strategy, and pore size expansion via acid-refluxing. By such a method, 1.9 μm superficially porous materials with 0.18 μm shell thickness and tailored pore diameter (10 nm, 15 nm) were obtained. After pore enlargement, the formerly dense arrays of mesoporous structure changed, the radially oriented pores dominated the superficially porous structure. The chromatographic performance of such particles was investigated after C18 derivatization. For packing materials with 1.9 μm diameter and 10 nm pore size, the column efficiency could reach 211,300 plates per m for naphthalene. To achieve the high resolution separation of peptides and proteins, particles with pore diameter of 15 nm were tailored, by which the baseline separation of 5 peptides and 5 intact proteins could be respectively achieved within 1 min, demonstrating the superiority in the high efficiency and high throughput analysis of biomolecules. Furthermore, BSA digests were well separated with peak capacity of 120 in 30 min on a 15 cm-long column. Finally, we compared our columns with a 1.7 μm Kinetex C18 column under the same conditions, our particles with 10nm pore size demonstrated similar performance for separation of the large intact proteins. Moreover, the particles with 15 nm pore size showed more symmetrical peaks for the separation of large proteins (BSA, OVA and IgG) and provided rapid separation of protein extracts from Escherichia coli in 5 min. All these results indicated that the synthesized 1.9 μm superficially porous silica packing materials would be promising in the ultra-fast and high-resolution separation of biomolecules. Copyright © 2014 Elsevier B.V. All rights reserved.

Social Cognition in Individuals at Ultra-High Risk for Psychosis: A Meta-Analysis

PubMed Central

van Donkersgoed, R. J. M.; Wunderink, L.; Nieboer, R.; Aleman, A.; Pijnenborg, G. H. M.

2015-01-01

Objective Treatment in the ultra-high risk stage for a psychotic episode is critical to the course of symptoms. Markers for the development of psychosis have been studied, to optimize the detection of people at risk of psychosis. One possible marker for the transition to psychosis is social cognition. To estimate effect sizes for social cognition based on a quantitative integration of the published evidence, we conducted a meta-analysis of social cognitive performance in people at ultra high risk (UHR). Methods A literature search (1970-July 2015) was performed in PubMed, PsychINFO, Medline, Embase, and ISI Web of Science, using the search terms ‘social cognition’, ‘theory of mind’, ‘emotion recognition’, ‘attributional style’, ‘social knowledge’, ‘social perception’, ‘empathy’, ‘at risk mental state’, ‘clinical high risk’, ‘psychosis prodrome’, and ‘ultra high risk’. The pooled effect size (Cohen’s D) and the effect sizes for each domain of social cognition were calculated. A random effects model with 95% confidence intervals was used. Results Seventeen studies were included in the analysis. The overall significant effect was of medium magnitude (d = 0.52, 95% Cl = 0.38–0.65). No moderator effects were found for age, gender and sample size. Sub-analyses demonstrated that individuals in the UHR phase show significant moderate deficits in affect recognition and affect discrimination in faces as well as in voices and in verbal Theory of Mind (TOM). Due to an insufficient amount of studies, we did not calculate an effect size for attributional bias and social perception/ knowledge. A majority of studies did not find a correlation between social cognition deficits and transition to psychosis, which may suggest that social cognition in general is not a useful marker for the development of psychosis. However some studies suggest the possible predictive value of verbal TOM and the recognition of specific emotions in faces for the transition into psychosis. More research is needed on these subjects. Conclusion The published literature indicates consistent general impairments in social cognition in people in the UHR phase, but only very specific impairments seem to predict transition to psychosis. PMID:26510175

How do changes in parental investment influence development in echinoid echinoderms?

PubMed

Alcorn, Nicholas J; Allen, Jonathan D

2009-01-01

Understanding the relationship between egg size, development time, and juvenile size is critical to explaining patterns of life-history evolution in marine invertebrates. Currently there is conflicting information about the effects of changes in egg size on the life histories of echinoid echinoderms. We sought to resolve this conflict by manipulating egg size and food level during the development of two planktotrophic echinoid echinoderms: the green sea urchin, Strongylocentrotus droebachiensis and the sand dollar, Echinarachnius parma. Based on comparative datasets, we predicted that decreasing food availability and egg size would increase development time and reduce juvenile size. To test our prediction, blastomere separations were performed in both species at the two-cell stage to reduce egg volume by 50%, producing whole- and half-size larvae that were reared to metamorphosis under high or low food levels. Upon settlement, age at metamorphosis, juvenile size, spine number, and spine length were measured. As predicted, reducing egg size and food availability significantly increased age at metamorphosis and reduced juvenile quality. Along with previous egg size manipulations in other echinoids, this study suggests that the relationship between egg size, development time, and juvenile size is strongly dependent upon the initial size of the egg.

Dry minor mergers and size evolution of high-z compact massive early-type galaxies

NASA Astrophysics Data System (ADS)

Oogi, Taira; Habe, Asao

2013-01-01

Recent observations show evidence that high-z (z ˜ 2-3) early-type galaxies (ETGs) are more compact than those with comparable mass at z ˜ 0. Such size evolution is most likely explained by the `dry merger sceanario'. However, previous studies based on this scenario cannot consistently explain the properties of both high-z compact massive ETGs and local ETGs. We investigate the effect of multiple sequential dry minor mergers on the size evolution of compact massive ETGs. From an analysis of the Millennium Simulation Data Base, we show that such minor (stellar mass ratio M2/M1 < 1/4) mergers are extremely common during hierarchical structure formation. We perform N-body simulations of sequential minor mergers with parabolic and head-on orbits, including a dark matter component and a stellar component. Typical mass ratios of these minor mergers are 1/20 < M2/M1 ≤q 1/10. We show that sequential minor mergers of compact satellite galaxies are the most efficient at promoting size growth and decreasing the velocity dispersion of compact massive ETGs in our simulations. The change of stellar size and density of the merger remnants is consistent with recent observations. Furthermore, we construct the merger histories of candidates for high-z compact massive ETGs using the Millennium Simulation Data Base and estimate the size growth of the galaxies through the dry minor merger scenario. We can reproduce the mean size growth factor between z = 2 and z = 0, assuming the most efficient size growth obtained during sequential minor mergers in our simulations. However, we note that our numerical result is only valid for merger histories with typical mass ratios between 1/20 and 1/10 with parabolic and head-on orbits and that our most efficient size-growth efficiency is likely an upper limit.

Effect of high-pressure homogenization preparation on mean globule size and large-diameter tail of oil-in-water injectable emulsions.

PubMed

Peng, Jie; Dong, Wu-Jun; Li, Ling; Xu, Jia-Ming; Jin, Du-Jia; Xia, Xue-Jun; Liu, Yu-Ling

2015-12-01

The effect of different high pressure homogenization energy input parameters on mean diameter droplet size (MDS) and droplets with > 5 μm of lipid injectable emulsions were evaluated. All emulsions were prepared at different water bath temperatures or at different rotation speeds and rotor-stator system times, and using different homogenization pressures and numbers of high-pressure system recirculations. The MDS and polydispersity index (PI) value of the emulsions were determined using the dynamic light scattering (DLS) method, and large-diameter tail assessments were performed using the light-obscuration/single particle optical sensing (LO/SPOS) method. Using 1000 bar homogenization pressure and seven recirculations, the energy input parameters related to the rotor-stator system will not have an effect on the final particle size results. When rotor-stator system energy input parameters are fixed, homogenization pressure and recirculation will affect mean particle size and large diameter droplet. Particle size will decrease with increasing homogenization pressure from 400 bar to 1300 bar when homogenization recirculation is fixed; when the homogenization pressure is fixed at 1000 bar, the particle size of both MDS and percent of fat droplets exceeding 5 μm (PFAT 5 ) will decrease with increasing homogenization recirculations, MDS dropped to 173 nm after five cycles and maintained this level, volume-weighted PFAT 5 will drop to 0.038% after three cycles, so the "plateau" of MDS will come up later than that of PFAT 5 , and the optimal particle size is produced when both of them remained at plateau. Excess homogenization recirculation such as nine times under the 1000 bar may lead to PFAT 5 increase to 0.060% rather than a decrease; therefore, the high-pressure homogenization procedure is the key factor affecting the particle size distribution of emulsions. Varying storage conditions (4-25°C) also influenced particle size, especially the PFAT 5 . Copyright © 2015. Published by Elsevier B.V.

Development of a high-sensitivity and portable cell using Helmholtz resonance for noninvasive blood glucose-level measurement based on photoacoustic spectroscopy.

PubMed

Tachibana, K; Okada, K; Kobayashi, R; Ishihara, Y

2016-08-01

We describe the possibility of high-sensitivity noninvasive blood glucose measurement based on photoacoustic spectroscopy (PAS). The demand for noninvasive blood glucose-level measurement has increased due to the explosive increase in diabetic patients. We have developed a noninvasive blood glucose-level measurement based on PAS. The conventional method uses a straight-type resonant cell. However, the cell volume is large, which results in a low detection sensitivity and difficult portability. In this paper, a small-sized Helmholtz-type resonant cell is proposed to improve detection sensitivity and portability by reducing the cell dead volume. First, the acoustic property of the small-sized Helmholtz-type resonant cell was evaluated by performing an experiment using a silicone rubber. As a result, the detection sensitivity of the small-sized Helmholtz-type resonant cell was approximately two times larger than that of the conventional straight-type resonant cell. In addition, the inside volume was approximately 30 times smaller. Second, the detection limits of glucose concentration were estimated by performing an experiment using glucose solutions. The experimental results showed that a glucose concentration of approximately 1% was detected by the small-sized Helmholtz-type resonant cell. Although these results on the sensitivity of blood glucose-level measurement are currently insufficient, they suggest that miniaturization of a resonance cell is effective in the application of noninvasive blood glucose-level measurement.

High capacitance of coarse-grained carbide derived carbon electrodes

DOE PAGES

Dyatkin, Boris; Gogotsi, Oleksiy; Malinovskiy, Bohdan; ...

2016-01-01

Here, we report exceptional electrochemical properties of supercapacitor electrodes composed of large, granular carbide-derived carbon (CDC) particles. We synthesized 70–250 μm sized particles with high surface area and a narrow pore size distribution, using a titanium carbide (TiC) precursor. Electrochemical cycling of these coarse-grained powders defied conventional wisdom that a small particle size is strictly required for supercapacitor electrodes and allowed high charge storage densities, rapid transport, and good rate handling ability. Moreover, the material showcased capacitance above 100 F g -1 at sweep rates as high as 250 mV s -1 in organic electrolyte. 250–1000 micron thick dense CDCmore » films with up to 80 mg cm -2 loading showed superior areal capacitances. The material significantly outperformed its activated carbon counterpart in organic electrolytes and ionic liquids. Furthermore, large internal/external surface ratio of coarse-grained carbons allowed the resulting electrodes to maintain high electrochemical stability up to 3.1 V in ionic liquid electrolyte. In addition to presenting novel insights into the electrosorption process, these coarse-grained carbons offer a pathway to low-cost, high-performance implementation of supercapacitors in automotive and grid-storage applications.« less

Scalable fabrication of micron-scale graphene nanomeshes for high-performance supercapacitor applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Hyun-Kyung; Bak, Seong-Min; Lee, Suk Woo

Graphene nanomeshes (GNMs) with nanoscale periodic or quasi-periodic nanoholes have attracted considerable interest because of unique features such as their open energy band gap, enlarged specific surface area, and high optical transmittance. These features are useful for applications in semiconducting devices, photocatalysis, sensors, and energy-related systems. We report on the facile and scalable preparation of multifunctional micron-scale GNMs with high-density of nanoperforations by catalytic carbon gasification. The catalytic carbon gasification process induces selective decomposition on the graphene adjacent to the metal catalyst, thus forming nanoperforations. Furthermore, the pore size, pore density distribution, and neck size of the GNMs can bemore » controlled by adjusting the size and fraction of the metal oxide on graphene. The fabricated GNM electrodes exhibit superior electrochemical properties for supercapacitor (ultracapacitor) applications, including exceptionally high capacitance (253 F g -1 at 1 A g -1) and high rate capability (212 F g -1 at 100 A g -1) with excellent cycle stability (91% of the initial capacitance after 50 000 charge/discharge cycles). Moreover, the edge-enriched structure of GNMs plays an important role in achieving edge-selected and high-level nitrogen doping.« less

High capacitance of coarse-grained carbide derived carbon electrodes

NASA Astrophysics Data System (ADS)

Dyatkin, Boris; Gogotsi, Oleksiy; Malinovskiy, Bohdan; Zozulya, Yuliya; Simon, Patrice; Gogotsi, Yury

2016-02-01

We report exceptional electrochemical properties of supercapacitor electrodes composed of large, granular carbide-derived carbon (CDC) particles. Using a titanium carbide (TiC) precursor, we synthesized 70-250 μm sized particles with high surface area and a narrow pore size distribution. Electrochemical cycling of these coarse-grained powders defied conventional wisdom that a small particle size is strictly required for supercapacitor electrodes and allowed high charge storage densities, rapid transport, and good rate handling ability. The material showcased capacitance above 100 F g-1 at sweep rates as high as 250 mV s-1 in organic electrolyte. 250-1000 micron thick dense CDC films with up to 80 mg cm-2 loading showed superior areal capacitances. The material significantly outperformed its activated carbon counterpart in organic electrolytes and ionic liquids. Furthermore, large internal/external surface ratio of coarse-grained carbons allowed the resulting electrodes to maintain high electrochemical stability up to 3.1 V in ionic liquid electrolyte. In addition to presenting novel insights into the electrosorption process, these coarse-grained carbons offer a pathway to low-cost, high-performance implementation of supercapacitors in automotive and grid-storage applications.

Scalable fabrication of micron-scale graphene nanomeshes for high-performance supercapacitor applications

DOE PAGES

Kim, Hyun-Kyung; Bak, Seong-Min; Lee, Suk Woo; ...

2016-01-27

Graphene nanomeshes (GNMs) with nanoscale periodic or quasi-periodic nanoholes have attracted considerable interest because of unique features such as their open energy band gap, enlarged specific surface area, and high optical transmittance. These features are useful for applications in semiconducting devices, photocatalysis, sensors, and energy-related systems. We report on the facile and scalable preparation of multifunctional micron-scale GNMs with high-density of nanoperforations by catalytic carbon gasification. The catalytic carbon gasification process induces selective decomposition on the graphene adjacent to the metal catalyst, thus forming nanoperforations. Furthermore, the pore size, pore density distribution, and neck size of the GNMs can bemore » controlled by adjusting the size and fraction of the metal oxide on graphene. The fabricated GNM electrodes exhibit superior electrochemical properties for supercapacitor (ultracapacitor) applications, including exceptionally high capacitance (253 F g -1 at 1 A g -1) and high rate capability (212 F g -1 at 100 A g -1) with excellent cycle stability (91% of the initial capacitance after 50 000 charge/discharge cycles). Moreover, the edge-enriched structure of GNMs plays an important role in achieving edge-selected and high-level nitrogen doping.« less

{331}-Faceted trisoctahedral gold nanocrystals: synthesis, superior electrocatalytic performance and highly efficient SERS activity

NASA Astrophysics Data System (ADS)

Song, Yahui; Miao, Tingting; Zhang, Peina; Bi, Cuixia; Xia, Haibing; Wang, Dayang; Tao, Xutang

2015-04-01

We investigate the effect of gold (Au) seeds prepared in cetyltrimethylammonium chloride solution (CTAC-Au seeds) on the index facets of trisoctahedral gold nanocrystals (TOH Au NCs). We demonstrate that monodisperse {331}-faceted TOH Au NCs with controllable sizes (from 60 to 255 nm) can be successfully prepared in high yield by using 3.0 nm CTAC-Au seeds or as-prepared 70 nm TOH Au NCs as seeds. We find that the electrocatalytic performance on methanol oxidation and surface enhancement Raman spectroscopy (SERS) activity of {331}-faceted TOH Au NCs is size-dependent. In comparison with well-known nanoporous gold (0.088 mA cm-2), {331}-faceted TOH Au NCs with sizes of 110 nm exhibit fairly high catalytic activity (0.178 mA cm-2) on methanol oxidation (1.0 M) in alkaline media due to the presence of increasing density of atomic steps, ledges, and kinks on the NC surfaces. Their current density is reduced by less than 7% after 500 cycling tests. {331}-Faceted TOH Au NCs with sizes of 175 nm exhibit the highest SERS activity for 4-aminothiophenol (4-ATP) molecules. The enhancement factors of a1 modes of 4-ATP molecules can reach the order of 109 when the 4-ATP concentration is 3 × 10-6 M. Moreover, Raman signals (ag modes) of 4,4'-dimercaptoazobenzene (DMAB) molecules on TOH Au NCs are stronger than those on spherical Au NCs of comparable size due to the enhanced laser-induced transformation of 4-ATP molecules by high-index {331}-facets during SERS measurement. Furthermore, the SERS intensities of 4-methylbenzenethiol (4-MTP) molecules on TOH Au NCs are also higher than those on spherical Au NCs of comparable size due to sharp extremities.We investigate the effect of gold (Au) seeds prepared in cetyltrimethylammonium chloride solution (CTAC-Au seeds) on the index facets of trisoctahedral gold nanocrystals (TOH Au NCs). We demonstrate that monodisperse {331}-faceted TOH Au NCs with controllable sizes (from 60 to 255 nm) can be successfully prepared in high yield by using 3.0 nm CTAC-Au seeds or as-prepared 70 nm TOH Au NCs as seeds. We find that the electrocatalytic performance on methanol oxidation and surface enhancement Raman spectroscopy (SERS) activity of {331}-faceted TOH Au NCs is size-dependent. In comparison with well-known nanoporous gold (0.088 mA cm-2), {331}-faceted TOH Au NCs with sizes of 110 nm exhibit fairly high catalytic activity (0.178 mA cm-2) on methanol oxidation (1.0 M) in alkaline media due to the presence of increasing density of atomic steps, ledges, and kinks on the NC surfaces. Their current density is reduced by less than 7% after 500 cycling tests. {331}-Faceted TOH Au NCs with sizes of 175 nm exhibit the highest SERS activity for 4-aminothiophenol (4-ATP) molecules. The enhancement factors of a1 modes of 4-ATP molecules can reach the order of 109 when the 4-ATP concentration is 3 × 10-6 M. Moreover, Raman signals (ag modes) of 4,4'-dimercaptoazobenzene (DMAB) molecules on TOH Au NCs are stronger than those on spherical Au NCs of comparable size due to the enhanced laser-induced transformation of 4-ATP molecules by high-index {331}-facets during SERS measurement. Furthermore, the SERS intensities of 4-methylbenzenethiol (4-MTP) molecules on TOH Au NCs are also higher than those on spherical Au NCs of comparable size due to sharp extremities. Electronic supplementary information (ESI) available: Extra TEM images and extinction spectra of the corresponding TOH Au NCs obtained with CTAB-Au seeds and CTAC-Au seeds, cyclic voltammograms of the corresponding TOH Au NCs with {221} facets and {331} facets in 0.50 M H2SO4 medium, cyclic voltammograms of TOH Au NCs with different sizes in 0.50 M H2SO4 medium and in 0.50 M KOH medium, the variation of oxidation peak current density of the GCEs modified by the 110 nm TOH Au NCs at different scanning cycle numbers, experimental extinction spectra of TOH Au NCs of different sizes, SERS spectra of 4-ATP molecules on the aggregates of 175 nm TOH Au NCs and 170 nm spherical Au NCs, the normal Raman spectrum of the neat film of the 4-ATP molecule, and summarized data of the Raman intensity and SERS enhancement factors of the TOH Au NCs with different sizes in specific Raman bands. See DOI: 10.1039/c5nr01049g

Preparation and characterization of monodisperse large-porous silica microspheres as the matrix for protein separation.

PubMed

Xia, Hongjun; Wan, Guangping; Zhao, Junlong; Liu, Jiawei; Bai, Quan

2016-11-04

High performance liquid chromatography (HPLC) is a kind of efficient separation technology and has been used widely in many fields. Micro-sized porous silica microspheres as the most popular matrix have been used for fast separation and analysis in HPLC. In this paper, the monodisperse large-porous silica microspheres with controllable size and structure were successfully synthesized with polymer microspheres as the templates and characterized. First, the poly(glycidyl methacrylate-co-ethyleneglycol dimethacrylate) microspheres (P GMA-EDMA ) were functionalized with tetraethylenepentamine (TEPA) to generate amino groups which act as a catalyst in hydrolysis of tetraethyl orthosilicate (TEOS) to form Si-containing low molecular weight species. Then the low molecular weight species diffused into the functionalized P GMA-EDMA microspheres by induction force of the amino groups to form polymer/silica hybrid microspheres. Finally, the organic polymer templates were removed by calcination, and the large-porous silica microspheres were obtained. The compositions, morphology, size distribution, specific surface area and pore size distribution of the porous silica microspheres were characterized by infrared analyzer, scanning-electron microscopy, dynamic laser scattering, the mercury intrusion method and thermal gravimetric analysis, respectively. The results show that the agglomeration of the hybrid microspheres can be overcome when the templates were functionalized with TEPA as amination reagent, and the yield of 95.7% of the monodisperse large-porous silica microspheres can be achieved with high concentration of polymer templates. The resulting large-porous silica microspheres were modified with octadecyltrichlorosilane (ODS) and the chromatographic evaluation was performed by separating the proteins and the digest of BSA. The baseline separation of seven kinds of protein standards was achieved, and the column delivered a better performance when separating BSA digests comparing with the commercial one currently available. The high column efficiency and good reproducibility present that the large-porous silica microspheres obtained can be used as a matrix for peptide and protein separation. Copyright © 2016 Elsevier B.V. All rights reserved.

Palladium nanoparticles decorated on reduced graphene oxide rotating disk electrodes toward ultrasensitive hydrazine detection: effects of particle size and hydrodynamic diffusion.

PubMed

Krittayavathananon, Atiweena; Srimuk, Pattarachai; Luanwuthi, Santamon; Sawangphruk, Montree

2014-12-16

Although metal nanoparticle/graphene composites have been widely used as the electrode in electrochemical sensors, two effects, consisting of the particle size of the nanoparticles and the hydrodynamic diffusion of analytes to the electrodes, are not yet fully understood. In this work, palladium nanoparticles/reduced graphene oxide (PdNPs/rGO) composites were synthesized using an in situ polyol method. Palladium(II) ions and graphene oxide were reduced together with a reducing agent, ethylene glycol. By varying the concentration of palladium(II) nitrate, PdNPs with different sizes were decorated on the surface of rGO sheets. The as-fabricated PdNPs/rGO rotating disk electrodes (RDEs) were investigated toward hydrazine detection. Overall, a 3.7 ± 1.4 nm diameter PdNPs/rGO RDE exhibits high performance with a rather low limit of detection of about 7 nM at a rotation speed of 6000 rpm and provides a wide linear range of 0.1-1000 μM with R(2) = 0.995 at 2000 rpm. This electrode is highly selective to hydrazine without interference from uric acid, glucose, ammonia, caffeine, methylamine, ethylenediamine, hydroxylamine, n-butylamine, adenosine, cytosine, guanine, thymine, and l-arginine. The PdNPs/rGO RDEs with larger sizes show lower detection performance. Interestingly, the detection performance of the electrodes is sensitive to the hydrodynamic diffusion of hydrazine. The as-fabricated electrode can detect trace hydrazine in wastewater with high stability, demonstrating its practical use as an electrochemical sensor. These findings may lead to an awareness of the effect of the hydrodynamic diffusion of analyte that has been previously ignored, and the 3.7 ± 1.4 nm PdNPs/rGO RDE may be useful toward trace hydrazine detection, especially in wastewater from related chemical industries.

Clear microstructure-performance relationships in Mn-containing perovskite and hexaaluminate compounds prepared by activated reactive synthesis.

PubMed

Laassiri, Said; Bion, Nicolas; Duprez, Daniel; Royer, Sébastien; Alamdari, Houshang

2014-03-07

Microstructural properties of mixed oxides play essential roles in their oxygen mobility and consequently in their catalytic performances. Two families of mixed oxides (perovskite and hexaaluminate) with different microstructural features, such as crystal size and specific surface area, were prepared using the activated reactive synthesis (ARS) method. It was shown that ARS is a flexible route to synthesize both mixed oxides with nano-scale crystal size and high specific surface area. Redox properties and oxygen mobility were found to be strongly affected by the material microstructure. Catalytic activities of hexaaluminate and perovskite materials for methane oxidation were discussed in the light of structural, redox and oxygen mobility properties.

Large size MOEMS Fabry-Perot interferometer filter for focal plane array hyperspectral imaging

NASA Astrophysics Data System (ADS)

Chee, J.; Hwu, J.; Kim, T. S.; Kubby, J.; Velicu, S.; Gupta, N.

2015-02-01

Focal plane array (FPA) technology is mature and is widely used for imaging applications. However, FPAs have broadband responses which limit their ability to provide high performance in hyperspectral applications such as detection of buried explosives, and identifying the presence of explosive chemicals and their concentrations. EPIR is currently developing Micro-Opto-Electro-Mechanical System (MOEMS) Fabry-Perot interferometer filter (FPF) devices for FPAs. In this paper, we present our approach to MOEMS FPF design and fabrication that will meet the size requirements for large format FPA hyperspectral imaging. We also report the performance of our FPF resonance cavity, capable of up to 3 μm change gap in tens of nanometer increments.

On-chip photonic particle sensor

NASA Astrophysics Data System (ADS)

Singh, Robin; Ma, Danhao; Agarwal, Anu; Anthony, Brian

2018-02-01

We propose an on-chip photonic particle sensor design that can perform particle sizing and counting for various environmental applications. The sensor is based on micro photonic ring resonators that are able to detect the presence of the free space particles through the interaction with their evanescent electric field tail. The sensor can characterize a wide range of the particle size ranging from a few nano meters to micron ( 1 micron). The photonic platform offers high sensitivity, compactness, fast response of the device. Further, FDTD simulations are performed to analyze different particle-light interactions. Such a compact and portable platform, packaged with integrated photonic circuit provides a useful sensing modality in space shuttle and environmental applications.

Protograph based LDPC codes with minimum distance linearly growing with block size

NASA Technical Reports Server (NTRS)

Divsalar, Dariush; Jones, Christopher; Dolinar, Sam; Thorpe, Jeremy

2005-01-01

We propose several LDPC code constructions that simultaneously achieve good threshold and error floor performance. Minimum distance is shown to grow linearly with block size (similar to regular codes of variable degree at least 3) by considering ensemble average weight enumerators. Our constructions are based on projected graph, or protograph, structures that support high-speed decoder implementations. As with irregular ensembles, our constructions are sensitive to the proportion of degree-2 variable nodes. A code with too few such nodes tends to have an iterative decoding threshold that is far from the capacity threshold. A code with too many such nodes tends to not exhibit a minimum distance that grows linearly in block length. In this paper we also show that precoding can be used to lower the threshold of regular LDPC codes. The decoding thresholds of the proposed codes, which have linearly increasing minimum distance in block size, outperform that of regular LDPC codes. Furthermore, a family of low to high rate codes, with thresholds that adhere closely to their respective channel capacity thresholds, is presented. Simulation results for a few example codes show that the proposed codes have low error floors as well as good threshold SNFt performance.

Photothermal Catalyst Engineering: Hydrogenation of Gaseous CO 2 with High Activity and Tailored Selectivity

DOE PAGES

Jia, Jia; Wang, Hong; Lu, Zhuole; ...

2017-07-25

This study has designed and implemented a library of hetero-nanostructured catalysts, denoted as Pd@Nb 2O 5, comprised of size-controlled Pd nanocrystals interfaced with Nb 2O 5 nanorods. This study also demonstrates that the catalytic activity and selectivity of CO 2 reduction to CO and CH 4 products can be systematically tailored by varying the size of the Pd nanocrystals supported on the Nb 2O 5 nanorods. Using large Pd nanocrystals, this study achieves CO and CH 4 production rates as high as 0.75 and 0.11 mol h –1 gPd –1, respectively. By contrast, using small Pd nanocrystals, a CO productionmore » rate surpassing 18.8 mol h –1 gPd –1 is observed with 99.5% CO selectivity. These performance metrics establish a new milestone in the champion league of catalytic nanomaterials that can enable solar-powered gas-phase heterogeneous CO 2 reduction. In conclusion, the remarkable control over the catalytic performance of Pd@Nb 2O 5 is demonstrated to stem from a combination of photothermal, electronic and size effects, which is rationally tunable through nanochemistry.« less

Simulation and Analysis of Mechanical Properties of Silica Aerogels: From Rationalization to Prediction

PubMed Central

Ma, Hao; Zheng, Xiaoyang; Luo, Xuan; Yang, Fan

2018-01-01

Silica aerogels are highly porous 3D nanostructures and have exhibited excellent physio-chemical properties. Although silica aerogels have broad potential in many fields, the poor mechanical properties greatly limit further applications. In this study, we have applied the finite volume method (FVM) method to calculate the mechanical properties of silica aerogels with different geometric properties such as particle size, pore size, ligament diameter, etc. The FVM simulation results show that a power law correlation existing between relative density and mechanical properties (elastic modulus and yield stress) of silica aerogels, which are consistent with experimental and literature studies. In addition, depending on the relative densities, different strategies are proposed in order to synthesize silica aerogels with better mechanical performance by adjusting the distribution of pore size and ligament diameter of aerogels. Finally, the results suggest that it is possible to synthesize silica aerogels with ultra-low density as well as high strength and stiffness as long as the textural features are well controlled. It is believed that the FVM simulation methodology could be a valuable tool to study mechanical performance of silica aerogel based materials in the future. PMID:29385745

Simulation and Analysis of Mechanical Properties of Silica Aerogels: From Rationalization to Prediction.

PubMed

Ma, Hao; Zheng, Xiaoyang; Luo, Xuan; Yi, Yong; Yang, Fan

2018-01-30

Silica aerogels are highly porous 3D nanostructures and have exhibited excellent physio-chemical properties. Although silica aerogels have broad potential in many fields, the poor mechanical properties greatly limit further applications. In this study, we have applied the finite volume method (FVM) method to calculate the mechanical properties of silica aerogels with different geometric properties such as particle size, pore size, ligament diameter, etc. The FVM simulation results show that a power law correlation existing between relative density and mechanical properties (elastic modulus and yield stress) of silica aerogels, which are consistent with experimental and literature studies. In addition, depending on the relative densities, different strategies are proposed in order to synthesize silica aerogels with better mechanical performance by adjusting the distribution of pore size and ligament diameter of aerogels. Finally, the results suggest that it is possible to synthesize silica aerogels with ultra-low density as well as high strength and stiffness as long as the textural features are well controlled. It is believed that the FVM simulation methodology could be a valuable tool to study mechanical performance of silica aerogel based materials in the future.

Characterization of ions at Alpine waterfalls

NASA Astrophysics Data System (ADS)

Kolarž, P.; Gaisberger, M.; Madl, P.; Hofmann, W.; Ritter, M.; Hartl, A.

2011-09-01

During a three-year field campaign of measuring waterfall generated ions, we monitored five different waterfalls in the Austrian Alps. Most measurements were performed at the Krimml waterfall (Salzburg), which is the biggest and most visited one in Europe and the Gartl waterfall (Mölltal, Carinthia). Smallest ion sizes (0.9-2 nm) were measured with a cylindrical air ion detector (CDI-06) while ion sizes from 5.5 to 350 nm were measured using a modified Grimm SMPS aerosol spectrometer. Measurements showed high negative ion gradients nearby waterfalls whereas positive ions showed only a moderate increase. The most abundant sizes of nano-sized and sub-micrometer ions measured were at 2 nm and of the larger and heavier ones at 120 nm.

N-doped graphene layers encapsulated NiFe alloy nanoparticles derived from MOFs with superior electrochemical performance for oxygen evolution reaction

NASA Astrophysics Data System (ADS)

Feng, Yi; Yu, Xin-Yao; Paik, Ungyu

2016-09-01

Water splitting, an efficient approach for hydrogen production, is often hindered by unfavorable kinetics of oxygen evolution reaction (OER). In order to reduce the overpotential, noble metal oxides-based electrocatalysts like RuO2 and IrO2 are usually utilized. However, due to their scarcity, the development of cost-effective non-precious OER electrocatalysts with high efficiency and good stability is urgently required. Herein, we report a facile one-step annealing of metal-organic frameworks (MOFs) strategy to synthesize N-doped graphene layers encapsulated NiFe alloy nanoparticles (NiFe@C). Through tuning the nanoparticle size and calcination temperature, NiFe@C with an average size of around 16 nm obtained at 700 °C exhibits superior OER performance with an overpotential of only 281 mV at 10 mA cm-2 and high durability. The facile synthesis method and excellent electrochemical performance show great potential of NiFe@C in replacing the precious metal-based electrocatalysts in the OER.

Traditional test administration and proactive interference undermine visual-spatial working memory performance in schizophrenia-spectrum disorders.

PubMed

Girard, Todd A; Wilkins, Leanne K; Lyons, Kathleen M; Yang, Lixia; Christensen, Bruce K

2018-05-31

Introduction Working-memory (WM) is a core cognitive deficit among individuals with Schizophrenia Spectrum Disorders (SSD). However, the underlying cognitive mechanisms of this deficit are less known. This study applies a modified version of the Corsi Block Test to investigate the role of proactive interference in visuospatial WM (VSWM) impairment in SSD. Methods Healthy and SSD participants completed a modified version of the Corsi Block Test involving both high (typical ascending set size from 4 to 7 items) and low (descending set size from 7 to 4 items) proactive interference conditions. Results The results confirmed that the SSD group performed worse overall relative to a healthy comparison group. More importantly, the SSD group demonstrated greater VSWM scores under low (Descending) versus high (Ascending) proactive interference; this pattern is opposite to that of healthy participants. Conclusions This differential pattern of performance supports that proactive interference associated with the traditional administration format contributes to VSWM impairment in SSD. Further research investigating associated neurocognitive mechanisms and the contribution of proactive interference across other domains of cognition in SSD is warranted.

Validation of a high-performance size-exclusion chromatography method to determine and characterize β-glucans in beer wort using a triple-detector array.

PubMed

Tomasi, Ivan; Marconi, Ombretta; Sileoni, Valeria; Perretti, Giuseppe

2017-01-01

Beer wort β-glucans are high-molecular-weight non-starch polysaccharides of that are great interest to the brewing industries. Because glucans can increase the viscosity of the solutions and form gels, hazes, and precipitates, they are often related to poor lautering performance and beer filtration problems. In this work, a simple and suitable method was developed to determine and characterize β-glucans in beer wort using size exclusion chromatography coupled with a triple-detector array, which is composed of a light scatterer, a viscometer, and a refractive-index detector. The method performances are comparable to the commercial reference method as result from the statistical validation and enable one to obtain interesting parameters of β-glucan in beer wort, such as the molecular weight averages, fraction description, hydrodynamic radius, intrinsic viscosity, polydispersity and Mark-Houwink parameters. This characterization can be useful in brewing science to understand filtration problems, which are not always explained through conventional analysis. Copyright © 2016 Elsevier Ltd. All rights reserved.

Investigations on high speed machining of EN-353 steel alloy under different machining environments

NASA Astrophysics Data System (ADS)

Venkata Vishnu, A.; Jamaleswara Kumar, P.

2018-03-01

The addition of Nano Particles into conventional cutting fluids enhances its cooling capabilities; in the present paper an attempt is made by adding nano sized particles into conventional cutting fluids. Taguchi Robust Design Methodology is employed in order to study the performance characteristics of different turning parameters i.e. cutting speed, feed rate, depth of cut and type of tool under different machining environments i.e. dry machining, machining with lubricant - SAE 40 and machining with mixture of nano sized particles of Boric acid and base fluid SAE 40. A series of turning operations were performed using L27 (3)13 orthogonal array, considering high cutting speeds and the other machining parameters to measure hardness. The results are compared among the different machining environments, and it is concluded that there is considerable improvement in the machining performance using lubricant SAE 40 and mixture of SAE 40 + boric acid compared with dry machining. The ANOVA suggests that the selected parameters and the interactions are significant and cutting speed has most significant effect on hardness.

N-doped graphene layers encapsulated NiFe alloy nanoparticles derived from MOFs with superior electrochemical performance for oxygen evolution reaction

PubMed Central

Feng, Yi; Yu, Xin-Yao; Paik, Ungyu

2016-01-01

Water splitting, an efficient approach for hydrogen production, is often hindered by unfavorable kinetics of oxygen evolution reaction (OER). In order to reduce the overpotential, noble metal oxides-based electrocatalysts like RuO2 and IrO2 are usually utilized. However, due to their scarcity, the development of cost-effective non-precious OER electrocatalysts with high efficiency and good stability is urgently required. Herein, we report a facile one-step annealing of metal-organic frameworks (MOFs) strategy to synthesize N-doped graphene layers encapsulated NiFe alloy nanoparticles (NiFe@C). Through tuning the nanoparticle size and calcination temperature, NiFe@C with an average size of around 16 nm obtained at 700 °C exhibits superior OER performance with an overpotential of only 281 mV at 10 mA cm−2 and high durability. The facile synthesis method and excellent electrochemical performance show great potential of NiFe@C in replacing the precious metal-based electrocatalysts in the OER. PMID:27658968

Activated Porous Carbon Spheres with Customized Mesopores through Assembly of Diblock Copolymers for Electrochemical Capacitor.

PubMed

Tang, Jing; Wang, Jie; Shrestha, Lok Kumar; Hossain, Md Shahriar A; Alothman, Zeid Abdullah; Yamauchi, Yusuke; Ariga, Katsuhiko

2017-06-07

A series of porous carbon spheres with precisely adjustable mesopores (4-16 nm), high specific surface area (SSA, ∼2000 m 2 g -1 ), and submicrometer particle size (∼300 nm) was synthesized through a facile coassembly of diblock polymer micelles with a nontoxic dopamine source and a common postactivation process. The mesopore size can be controlled by the diblock polymer, polystyrene-block-poly(ethylene oxide) (PS-b-PEO) templates, and has an almost linear dependence on the square root of the degree of polymerization of the PS blocks. These advantageous structural properties make the product a promising electrode material for electrochemical capacitors. The electrochemical capacitive performance was studied carefully by using symmetrical cells in a typical organic electrolyte of 1 M tetraethylammonium tetrafluoroborate/acetonitrile (TEA BF 4 /AN) or in an ionic liquid electrolyte of 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIMBF 4 ), displaying a high specific capacitance of 111 and 170 F g -1 at 1 A g -1 , respectively. The impacts of pore size distribution on the capacitance performance were thoroughly investigated. It was revealed that large mesopores and a relatively low ratio of micropores are ideal for realizing high SSA-normalized capacitance. These results provide us with a simple and reliable way to screen future porous carbon materials for electrochemical capacitors and encourage researchers to design porous carbon with high specific surface area, large mesopores, and a moderate proportion of micropores.

Planning Risk-Based SQC Schedules for Bracketed Operation of Continuous Production Analyzers.

PubMed

Westgard, James O; Bayat, Hassan; Westgard, Sten A

2018-02-01

To minimize patient risk, "bracketed" statistical quality control (SQC) is recommended in the new CLSI guidelines for SQC (C24-Ed4). Bracketed SQC requires that a QC event both precedes and follows (brackets) a group of patient samples. In optimizing a QC schedule, the frequency of QC or run size becomes an important planning consideration to maintain quality and also facilitate responsive reporting of results from continuous operation of high production analytic systems. Different plans for optimizing a bracketed SQC schedule were investigated on the basis of Parvin's model for patient risk and CLSI C24-Ed4's recommendations for establishing QC schedules. A Sigma-metric run size nomogram was used to evaluate different QC schedules for processes of different sigma performance. For high Sigma performance, an effective SQC approach is to employ a multistage QC procedure utilizing a "startup" design at the beginning of production and a "monitor" design periodically throughout production. Example QC schedules are illustrated for applications with measurement procedures having 6-σ, 5-σ, and 4-σ performance. Continuous production analyzers that demonstrate high σ performance can be effectively controlled with multistage SQC designs that employ a startup QC event followed by periodic monitoring or bracketing QC events. Such designs can be optimized to minimize the risk of harm to patients. © 2017 American Association for Clinical Chemistry.

Evaluation of Basketball-Specific Agility: Applicability of Preplanned and Nonplanned Agility Performances for Differentiating Playing Positions and Playing Levels.

PubMed

Sekulic, Damir; Pehar, Miran; Krolo, Ante; Spasic, Miodrag; Uljevic, Ognjen; Calleja-González, Julio; Sattler, Tine

2017-08-01

Sekulic, D, Pehar, M, Krolo, A, Spasic, M, Uljevic, O, Calleja-González, J, and Sattler, T. Evaluation of basketball-specific agility: applicability of preplanned and nonplanned agility performances for differentiating playing positions and playing levels. J Strength Cond Res 31(8): 2278-2288, 2017-The importance of agility in basketball is well known, but there is an evident lack of studies examining basketball-specific agility performances in high-level players. The aim of this study was to determine the reliability and discriminative validity of 1 standard agility test (test of preplanned agility [change-of-direction speed] over T course, T-TEST), and 4 newly developed basketball-specific agility tests, in defining playing positions and performance levels in basketball. The study comprised 110 high-level male basketball players (height: 194.92 ± 8.09 cm; body mass: 89.33 ± 10.91 kg; age: 21.58 ± 3.92 years). The variables included playing position (Guard, Forward, Center), performance level (first division vs. second division), anthropometrics (body height, body mass, and percentage of body fat), T-TEST, nonplanned basketball agility test performed on dominant (BBAGILdom) and nondominant sides (BBAGILnond), and a preplanned (change-of-direction speed) basketball agility test performed on dominant (BBCODSdom) and nondominant sides (BBCODSnond). The reliability of agility tests was high (intraclass correlation coefficient of 0.81-0.95). Forwards were most successful in the T-TEST (F test: 13.57; p = 0.01). Guards outperformed Centers in BBCODSdom, BBCODSndom, BBAGILdom, and BBAGILnond (F test: 5.06, p = 0.01; 6.57, 0.01; 6.26, 0.01; 3.37, 0.04, respectively). First division Guards achieved better results than second division Guards in BBCODSdom (t: 2.55; p = 0.02; moderate effect size differences), BBAGILdom, and BBAGILnond (t: 3.04 and 3.06, respectively; both p = 0.01 and moderate effect size differences). First division Centers outperformed second division Centers in BBAGILdom (t: 2.50; p = 0.02; moderate effect size differences). The developed basketball-specific agility tests are applicable when defining position-specific agility. Both preplanned and nonplanned agilities are important qualities in differentiating between Guards of 2 performance levels. The results confirmed the importance of testing basketball-specific nonplanned agility when evaluating the performance level of Centers.

Bioinformatics analysis of disordered proteins in prokaryotes

PubMed Central

2011-01-01

Background A significant number of proteins have been shown to be intrinsically disordered, meaning that they lack a fixed 3 D structure or contain regions that do not posses a well defined 3 D structure. It has also been proven that a protein's disorder content is related to its function. We have performed an exhaustive analysis and comparison of the disorder content of proteins from prokaryotic organisms (i.e., superkingdoms Archaea and Bacteria) with respect to functional categories they belong to, i.e., Clusters of Orthologous Groups of proteins (COGs) and groups of COGs-Cellular processes (Cp), Information storage and processing (Isp), Metabolism (Me) and Poorly characterized (Pc). We also analyzed the disorder content of proteins with respect to various genomic, metabolic and ecological characteristics of the organism they belong to. We used correlations and association rule mining in order to identify the most confident associations between specific modalities of the characteristics considered and disorder content. Results Bacteria are shown to have a somewhat higher level of protein disorder than archaea, except for proteins in the Me functional group. It is demonstrated that the Isp and Cp functional groups in particular (L-repair function and N-cell motility and secretion COGs of proteins in specific) possess the highest disorder content, while Me proteins, in general, posses the lowest. Disorder fractions have been confirmed to have the lowest level for the so-called order-promoting amino acids and the highest level for the so-called disorder promoters. For each pair of organism characteristics, specific modalities are identified with the maximum disorder proteins in the corresponding organisms, e.g., high genome size-high GC content organisms, facultative anaerobic-low GC content organisms, aerobic-high genome size organisms, etc. Maximum disorder in archaea is observed for high GC content-low genome size organisms, high GC content-facultative anaerobic or aquatic or mesophilic organisms, etc. Maximum disorder in bacteria is observed for high GC content-high genome size organisms, high genome size-aerobic organisms, etc. Some of the most reliable association rules mined establish relationships between high GC content and high protein disorder, medium GC content and both medium and low protein disorder, anaerobic organisms and medium protein disorder, Gammaproteobacteria and low protein disorder, etc. A web site Prokaryote Disorder Database has been designed and implemented at the address http://bioinfo.matf.bg.ac.rs/disorder, which contains complete results of the analysis of protein disorder performed for 296 prokaryotic completely sequenced genomes. Conclusions Exhaustive disorder analysis has been performed by functional classes of proteins, for a larger dataset of prokaryotic organisms than previously done. Results obtained are well correlated to those previously published, with some extension in the range of disorder level and clear distinction between functional classes of proteins. Wide correlation and association analysis between protein disorder and genomic and ecological characteristics has been performed for the first time. The results obtained give insight into multi-relationships among the characteristics and protein disorder. Such analysis provides for better understanding of the evolutionary process and may be useful for taxon determination. The main drawback of the approach is the fact that the disorder considered has been predicted and not experimentally established. PMID:21366926

The future of RICH detectors through the light of the LHCb RICH

NASA Astrophysics Data System (ADS)

D'Ambrosio, C.; LHCb RICH Collaboration

2017-12-01

The limitations in performance of the present RICH system in the LHCb experiment are given by the natural chromatic dispersion of the gaseous Cherenkov radiator, the aberrations of the optical system and the pixel size of the photon detectors. Moreover, the overall PID performance can be affected by high detector occupancy as the pattern recognition becomes more difficult with high particle multiplicities. This paper shows a way to improve performance by systematically addressing each of the previously mentioned limitations. These ideas are applied in the present and future upgrade phases of the LHCb experiment. Although applied to specific circumstances, they are used as a paradigm on what is achievable in the development and realisation of high precision RICH detectors.

High surface area TiO2/SBA-15 nanocomposites: Synthesis, microstructure and adsorption-enhanced photocatalysis

NASA Astrophysics Data System (ADS)

Wei, J. Q.; Chen, X. J.; Wang, P. F.; Han, Y. B.; Xu, J. C.; Hong, B.; Jin, H. X.; Jin, D. F.; Peng, X. L.; Li, J.; Yang, Y. T.; Ge, H. L.; Wang, X. Q.

2018-06-01

Mesoporous SBA-15 was used to anchor TiO2 nanoparticles into the mesopores to form high surface area TiO2/SBA-15 nanocomposites, and then the influence of mesoporous-structure on the photocatalytic performance was investigated. TiO2/SBA-15 nanocomposites possessed the high specific surface area and appropriate pore size, indicating the excellent adsorption performance. TiO2/SBA-15 nanocomposites exhibited the higher photocatalytic activity to degrade dyes (methylene blue: MB) than TiO2 (removing SBA-15), which should attributed to the excellent adsorption performance of the nanocomposites. MB was absorbed to form the higher concentration near TiO2/SBA-15 photocatalysts, and the photocatalytic degradation for MB was improved.

Empirical study of seven data mining algorithms on different characteristics of datasets for biomedical classification applications.

PubMed

Zhang, Yiyan; Xin, Yi; Li, Qin; Ma, Jianshe; Li, Shuai; Lv, Xiaodan; Lv, Weiqi

2017-11-02

Various kinds of data mining algorithms are continuously raised with the development of related disciplines. The applicable scopes and their performances of these algorithms are different. Hence, finding a suitable algorithm for a dataset is becoming an important emphasis for biomedical researchers to solve practical problems promptly. In this paper, seven kinds of sophisticated active algorithms, namely, C4.5, support vector machine, AdaBoost, k-nearest neighbor, naïve Bayes, random forest, and logistic regression, were selected as the research objects. The seven algorithms were applied to the 12 top-click UCI public datasets with the task of classification, and their performances were compared through induction and analysis. The sample size, number of attributes, number of missing values, and the sample size of each class, correlation coefficients between variables, class entropy of task variable, and the ratio of the sample size of the largest class to the least class were calculated to character the 12 research datasets. The two ensemble algorithms reach high accuracy of classification on most datasets. Moreover, random forest performs better than AdaBoost on the unbalanced dataset of the multi-class task. Simple algorithms, such as the naïve Bayes and logistic regression model are suitable for a small dataset with high correlation between the task and other non-task attribute variables. K-nearest neighbor and C4.5 decision tree algorithms perform well on binary- and multi-class task datasets. Support vector machine is more adept on the balanced small dataset of the binary-class task. No algorithm can maintain the best performance in all datasets. The applicability of the seven data mining algorithms on the datasets with different characteristics was summarized to provide a reference for biomedical researchers or beginners in different fields.

NV-CMOS HD camera for day/night imaging

NASA Astrophysics Data System (ADS)

Vogelsong, T.; Tower, J.; Sudol, Thomas; Senko, T.; Chodelka, D.

2014-06-01

SRI International (SRI) has developed a new multi-purpose day/night video camera with low-light imaging performance comparable to an image intensifier, while offering the size, weight, ruggedness, and cost advantages enabled by the use of SRI's NV-CMOS HD digital image sensor chip. The digital video output is ideal for image enhancement, sharing with others through networking, video capture for data analysis, or fusion with thermal cameras. The camera provides Camera Link output with HD/WUXGA resolution of 1920 x 1200 pixels operating at 60 Hz. Windowing to smaller sizes enables operation at higher frame rates. High sensitivity is achieved through use of backside illumination, providing high Quantum Efficiency (QE) across the visible and near infrared (NIR) bands (peak QE <90%), as well as projected low noise (<2h+) readout. Power consumption is minimized in the camera, which operates from a single 5V supply. The NVCMOS HD camera provides a substantial reduction in size, weight, and power (SWaP) , ideal for SWaP-constrained day/night imaging platforms such as UAVs, ground vehicles, fixed mount surveillance, and may be reconfigured for mobile soldier operations such as night vision goggles and weapon sights. In addition the camera with the NV-CMOS HD imager is suitable for high performance digital cinematography/broadcast systems, biofluorescence/microscopy imaging, day/night security and surveillance, and other high-end applications which require HD video imaging with high sensitivity and wide dynamic range. The camera comes with an array of lens mounts including C-mount and F-mount. The latest test data from the NV-CMOS HD camera will be presented.

Transdermal delivery of forskolin from emulsions differing in droplet size.

PubMed

Sikora, Elżbieta; Llinas, Meritxell; Garcia-Celma, Maria Jose; Escribano, Elvira; Solans, Conxita

2015-02-01

The skin permeation of forskolin, a diterpene isolated from Coleus forsholii, was studied using oil in water (O/W) emulsions as delivery formulations and also an oil solution for comparative purposes. Two forskolin-loaded emulsions of water/Brij 72:Symperonic A7/Miglyol 812:Isohexadecane, at 0.075 wt% forskolin concentration were prepared with the same composition and only differing in droplet size (0.38 μm and 10 μm). The emulsions showed high kinetic stability at 25 °C. In vitro study of forskolin penetration through human skin was carried out using the MicroettePlus(®) system. The concentration of the active in the receptor solution (i.e. ethanol/phosphate buffer 40/60, v/v) was analyzed by high performance liquid chromatography with UV detection. The obtained results showed that forskolin permeation from the emulsions and the oil solution, through human skin, was very high (up to 72.10%), and no effect of droplet size was observed. Copyright © 2015 Elsevier B.V. All rights reserved.

Controlling the Morphology and Oxidation Resistance of Boron Carbide Synthesized Via Carbothermic Reduction Reaction

NASA Astrophysics Data System (ADS)

Ahmed, Yasser M. Z.; El-Sheikh, Said M.; Ewais, Emad M. M.; Abd-Allah, Asmaa A.; Sayed, Said A.

2017-03-01

Boron carbide powder was synthesized from boric acid and lactose mixtures via easy procedure. Boric acid and lactose solution mixtures were roasted in stainless steel pot at 280 °C for 24 h. Boron carbide was obtained by heating the roasted samples under flowing of industrial argon gas at 1500 °C for 3 h. The amount of borate ester compound in the roasted samples was highly influenced by the boron/carbon ratio in the starting mixtures and plays a versatile role in the produced boron carbide. The high-purity boron carbide powder was produced with a sample composed of lowest boron/carbon ratio of 1:1 without calcination step. Particle morphology was changed from nano-needles like structure of 8-10 nm size with highest carbon ratio mixture to spherical shape of >150 nm size with lowest one. The oxidation resistance performance of boron carbide is highly dependent on the morphology and grain size of the synthesized powder.

High Temperature Performance Evaluation of a Compliant Foil Seal

NASA Technical Reports Server (NTRS)

Salehi, Mohsen; Heshmat, Hooshang; Walton, James F., II

2001-01-01

The key points to be gleaned from the effort reported herein are that the CFS (Compliant Foil Seal) has been demonstrated in conjunction with a foil bearing in a small gas turbine simulator at temperatures as high as 1000 F and outperformed a comparable brush seal. Having demonstrated the feasibility of the CFS, it would appear that this new seal design has application potential in a wide range of machines. What remains is to demonstrate performance at higher pressure ratios, consistent performance at large rotor excursions and the ability to manufacture the seal in much larger sizes exceeding by an order of magnitude that which has been tested to date.

Highly accurate adaptive TOF determination method for ultrasonic thickness measurement

NASA Astrophysics Data System (ADS)

Zhou, Lianjie; Liu, Haibo; Lian, Meng; Ying, Yangwei; Li, Te; Wang, Yongqing

2018-04-01

Determining the time of flight (TOF) is very critical for precise ultrasonic thickness measurement. However, the relatively low signal-to-noise ratio (SNR) of the received signals would induce significant TOF determination errors. In this paper, an adaptive time delay estimation method has been developed to improve the TOF determination’s accuracy. An improved variable step size adaptive algorithm with comprehensive step size control function is proposed. Meanwhile, a cubic spline fitting approach is also employed to alleviate the restriction of finite sampling interval. Simulation experiments under different SNR conditions were conducted for performance analysis. Simulation results manifested the performance advantage of proposed TOF determination method over existing TOF determination methods. When comparing with the conventional fixed step size, and Kwong and Aboulnasr algorithms, the steady state mean square deviation of the proposed algorithm was generally lower, which makes the proposed algorithm more suitable for TOF determination. Further, ultrasonic thickness measurement experiments were performed on aluminum alloy plates with various thicknesses. They indicated that the proposed TOF determination method was more robust even under low SNR conditions, and the ultrasonic thickness measurement accuracy could be significantly improved.

Study of advanced rotary combustion engines for commuter aircraft

NASA Technical Reports Server (NTRS)

Berkowitz, M.; Jones, C.; Myers, D.

1983-01-01

Performance, weight, size, and maintenance data for advanced rotary aircraft engines suitable for comparative commuter aircraft system evaluation studies of alternate engine candidates are provided. These are turbocharged, turbocompounded, direct injected, stratified charge rotary engines. Hypothetical engines were defined (an RC4-74 at 895 kW and an RC6-87 at 1490 kW) based on the technologies and design approaches used in the highly advanced engine of a study of advanced general aviation rotary engines. The data covers the size range of shaft power from 597 kW (800 hp) to 1865 kW (2500 hp) and is in the form of drawings, tables, curves and written text. These include data on internal geometry and configuration, installation information, turbocharging and turbocompounding arrangements, design features and technologies, engine cooling, fuels, scaling for weight size BSFC and heat rejection for varying horsepower, engine operating and performance data, and TBO and maintenance requirements. The basic combustion system was developed and demonstrated; however the projected power densities and performance efficiencies require increases in engine internal pressures, thermal loading, and rotative speed.

Quality Control of Trichinella Testing at the Slaughterhouse Laboratory: Evaluation of the Use of a 400-Micrometer-Mesh-Size Sieve in the Magnetic Stirrer Method.

PubMed

Franssen, Frits; van Andel, Esther; Swart, Arno; van der Giessen, Joke

2016-02-01

The performance of a 400-μm-mesh-size sieve (sieve400) has not previously been compared with that of a 180-μm-mesh-size sieve (sieve180). Using pork samples spiked with 0 to 10 Trichinella muscle larvae and an artificial digestion method, sieve performance was evaluated for control of Trichinella in meat-producing animals. The use of a sieve400 resulted in 12% lower larval counts, 147% more debris, and 28% longer counting times compared with the use of a sieve180. Although no false-negative results were obtained, prolonged counting times with the sieve400 may have an impact on performance in a high-throughput environment such as a slaughterhouse laboratory. Based on our results, the sieve180 remains the sieve of choice for Trichinella control in meat in slaughterhouse laboratories, according to the European Union reference method (European Commission regulation 2075/2005). Furthermore, the results of the present study contribute to the discussion of harmonization of meat inspection requirements among countries.

Performance evaluation of bimodal thermite composites : nano- vs miron-scale particles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moore, K. M.; Pantoya, M.; Son, S. F.

2004-01-01

In recent years many studies of metastable interstitial composites (MIC) have shown vast combustion improvements over traditional thermite materials. The main difference between these two materials is the size of the fuel particles in the mixture. Decreasing the fuel size from the micron to nanometer range significantly increases the combustion wave speed and ignition sensitivity. Little is known, however, about the critical level of nano-sized fuel particles needed to enhance the performance of the traditional thermite. Ignition sensitivity experiments were performed using Al/MoO{sub 3} pellets at a theoretical maximum density of 50% (2 g/cm{sup 3}). The Al fuel particles weremore » prepared as bi-modal size distributions with micron (i.e., 4 and 20 {micro}m diameter) and nano-scale Al particles. The micron-scale Al was replaced in 10% increments by 80 nm Al particles until the fuel was 100% 80 nm Al. These bi-modal distributions allow the unique characteristics of nano-scale materials to be better understood. The pellets were ignited using a 50-W CO{sub 2} laser. High speed imaging diagnostics were used to measure ignition delay times, and micro-thermocouples were used to measure ignition temperatures. Combustion wave speeds were also examined.« less

The impact of the luminance, size and location of LED billboards on drivers' visual performance-Laboratory tests.

PubMed

Zalesinska, Malgorzata

2018-08-01

A proper visual performance by drivers can be ensured by, among else, a correct distribution of luminance in their field of view. At night, when the driver's sight is adapted to low luminance levels, high luminance level objects located near the road may be a source of glare, which is not only a nuisance, but it may also blind the driver. For many years, LED billboards (light-emitting diode billboards) have been installed near roads. Such billboards are usually large, have high luminance and show dynamically changing images. These parameters have a significant impact on the drivers' visual performance and, in turn, on road traffic safety. The study on the impact of the luminance, size and location of LED billboards on the drivers' visual performance was conducted on a volunteer group. Testing the impact of LED billboards on the visual performance of drivers in real-life conditions is very difficult. Therefore, the tests have been conducted in laboratory conditions, using a car driving simulator. The paper describes the testing procedure and tests results. The permissible luminance and areas of LED screens in two locations near the road, which significantly reduce the drivers' visual performance in municipal traffic at night, were determined by conducting an analysis of the results. Recommendations on the permissible luminance and areas of LED billboards were formulated. Copyright © 2018 Elsevier Ltd. All rights reserved.

Gelatin Microspheres: Correlation between Embolic Effect/Degradability and Cross-linkage/Particle Size

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ohta, Shinichi, E-mail: junryuhei@yahoo.co.jp; Nitta, Norihisa, E-mail: r34nitta@belle.shiga-med.ac.jp; Watanabe, Shobu, E-mail: swat@belle.shiga-med.ac.jp

2013-08-01

PurposeTo evaluate the embolic effect and degradability of gelatin microspheres (GMS) using various degrees of cross-linkage and particle sizes in rabbit renal artery embolization.MethodsFour types of GMS were used, as follows: 2 types of cross-linkage and 2 types of particle size. Twenty-four rabbits (6 in each group) were used for the renal artery embolization. Renal angiography was performed before and after embolization of right renal artery. Follow-up renal angiography was performed 2 days (n = 2), 5 days (n = 2), and 15 days (n = 2) after embolization in each group, and then kidneys were removed for histopathological evaluation.more » Vascular areas of the angiography were measured by Image J software, and the reperfusion rate was calculated. In renal specimens, residual GMS were checked and the degree of degradation was classified according to a 4-point scale.ResultsThe mean amounts of large- and small-particle-size GMS injected were 15.0 and 34.3 mg, respectively. Tissue necrosis was confirmed in each group; however, no difference was observed among groups. Renal reperfusion was observed more with small GMS than with large GMS. Renal reperfusion was also observed more with low cross-linked GMS than with high cross-linked GMS. In histopathological specimens, large GMS were confirmed in lobar artery, and small GMS were confirmed in lobular artery. Low cross-linked GMS completely degraded 15 days after embolization. In contrast, high cross-linked GMS were persistent 15 days after embolization.ConclusionDegree of cross-linkage and particle size affected degradability and reperfusion.« less

Effective Padding of Multi-Dimensional Arrays to Avoid Cache Conflict Misses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hong, Changwan; Bao, Wenlei; Cohen, Albert

Caches are used to significantly improve performance. Even with high degrees of set-associativity, the number of accessed data elements mapping to the same set in a cache can easily exceed the degree of associativity, causing conflict misses and lowered performance, even if the working set is much smaller than cache capacity. Array padding (increasing the size of array dimensions) is a well known optimization technique that can reduce conflict misses. In this paper, we develop the first algorithms for optimal padding of arrays for a set associative cache for arbitrary tile sizes, In addition, we develop the first solution tomore » padding for nested tiles and multi-level caches. The techniques are in implemented in PAdvisor tool. Experimental results with multiple benchmarks demonstrate significant performance improvement from use of PAdvisor for padding.« less

Turboprop aircraft performance response to various environmental conditions

NASA Astrophysics Data System (ADS)

Ashenden, Russell Allen

1997-10-01

This study evaluated aircraft and airfoil performance response to various environmental conditions. These conditions included clear air, warm rain, ice only, mixed phase and supercooled drops encountered during 19 separate flights. Supercooled droplets consisting of cloud, drizzle and rain sizes were the main focus of this study. Aircraft response was quantified by rates of change in aircraft rate-of-climb capability, lift and drag coefficients and lift over drag ratio. Airfoil degradation due to simulated ice shapes and drizzle ice roughness was measured in a wind tunnel for comparison. The aircraft performance parameters were compared to environmental hydrometeor parameters quantifying the environmental conditions. Results show that encounters with supercooled drizzle drops, or SCDD, resulted in maximum rates of performance degradation. These high rates of degradation forced the pilot to take evasive action within 5 minutes of entering these hazardous conditions. Encounters with supercooled cloud and rain sized drops resulted in minor to low rates of performance degradation whereas encounters with supercooled drops in low ice particle concentrations resulted in only minor rates of degradation. In addition, aircraft response to high ice particle concentrations and low liquid water, following an SCDD encounter, resulted in rapid performance recovery. The airfoil evaluations show similar results where the drizzle drop ice shape and simulated drizzle ice roughness resulted in the highest performance degradation. These evaluations also show that the most sensitive surface location is on the suction side between 6 and at least 11% of airfoil chord. Ice contaminations in this area are beyond the protective de-icing boots of most aircraft and lead to severe degradations in lift and drag characteristics. The results presented herein show a strong relationship between aircraft response and environmental parameters utilizing the larger drops in the hydrometeor distribution. The results suggest that the most severe icing is actually caused by drizzle sized drops as opposed to freezing rain. Furthermore, these results are similar to many twin-turboprop aircraft typically utilized by the commuter fleet.

Performance of a High-Speed Compression-Ignition Engine Using Multiple Orifice Fuel Injection Nozzles

NASA Technical Reports Server (NTRS)

Spanogle, J A; Foster, H H

1930-01-01

This report presents test results obtained at the Langley Memorial Aeronautical Laboratory of the National Advisory Committee for Aeronautics during an investigation to determine the relative performance of a single-cylinder, high-speed, compression-ignition engine when using fuel injection valve nozzles with different numbers, sizes, and directions of round orifices. A spring-loaded, automatic injection valve was used, centrally located at the top of a vertical disk-type combustion chamber formed between horizontally opposed inlet and exhaust valves of a 5 inch by 7 inch engine.

Performance of low resistance microchannel plate stacks

NASA Technical Reports Server (NTRS)

Siegmund, O. H. W.; Stock, J.

1991-01-01

Results are presented from an evaluation of three sets of low resistance microchannel plate (MCP) stacks; the tests encompassed gain, pulse-height distribution, background rate, event rate capacity as a function of illuminated area, and performance changes due to high temperature bakeout and high flux UV scrub. The MCPs are found to heat up, requiring from minutes to hours to reach stabilization. The event rate is strongly dependent on the size of the area being illuminated, with larger areas experiencing a gain drop onset at lower rates than smaller areas.

Micro-sized organometallic compound of ferrocene as high-performance anode material for advanced lithium-ion batteries

NASA Astrophysics Data System (ADS)

Liu, Zhen; Feng, Li; Su, Xiaoru; Qin, Chenyang; Zhao, Kun; Hu, Fang; Zhou, Mingjiong; Xia, Yongyao

2018-01-01

An organometallic compound of ferrocene is first investigated as a promising anode for lithium-ion batteries. The electrochemical properties of ferrocene are conducted by galvanostatic charge and discharge. The ferrocene anode exhibits a high reversible capacity and great cycling stability, as well as superior rate capability. The electrochemical reaction of ferrocene is semi-reversible and some metallic Fe remains in the electrode even after delithiation. The metallic Fe formed in electrode and the stable solid electrolyte interphase should be responsible for its excellent electrochemical performance.

The single mirror small sized telescope for the Cherenkov telescope array

NASA Astrophysics Data System (ADS)

Heller, M.; Schioppa, E., Jr.; Porcelli, A.; Pujadas, I. Troyano; Ziętara, K.; Della Volpe, D.; Montaruli, T.; Cadoux, F.; Favre, Y.; Aguilar, J. A.; Christov, A.; Prandini, E.; Rajda, P.; Rameez, M.; Bilnik, W.; Błocki, J.; Bogacz, L.; Borkowski, J.; Bulik, T.; Frankowski, A.; Grudzińska, M.; Idźkowski, B.; Jamrozy, M.; Janiak, M.; Kasperek, J.; Lalik, K.; Lyard, E.; Mach, E.; Mandat, D.; Marszałek, A.; Miranda, L. D. Medina; Michałowski, J.; Moderski, R.; Neronov, A.; Niemiec, J.; Ostrowski, M.; Paśko, P.; Pech, M.; Schovanek, P.; Seweryn, K.; Sliusar, V.; Skowron, K.; Stawarz, Ł.; Stodulska, M.; Stodulski, M.; Walter, R.; Więcek, M.; Zagdański, A.; CTA Consortium

2017-01-01

The Small Size Telescope with Single Mirror (SST-1M) is one of the proposed types of Small Size Telescopes (SST) for the Cherenkov Telescope Array (CTA). About 70 SST telescopes will be part the CTA southern array which will also include Medium Sized Telescopes (MST) in its threshold configuration. Optimized for the detection of gamma rays in the energy range from 5 TeV to 300 TeV, the SST-1M uses a Davies-Cotton optics with a 4 m dish diameter with a field of view of 9°. The Cherenkov light resulting from the interaction of the gamma-rays in the atmosphere is focused onto a 88 cm side-to-side hexagonal photo-detection plane. The latter is composed of 1296 hollow light guides coupled to large area hexagonal silicon photomultipliers (SiPM). The SiPM readout is fully digital readout as for the trigger system. The compact and lightweight design of the SST-1M camera offiers very high performance ideal for gamma-ray observation requirement. In this contribution, the concept, design, performance and status of the first telescope prototype are presented.

Gap Size Uncertainty Quantification in Advanced Gas Reactor TRISO Fuel Irradiation Experiments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pham, Binh T.; Einerson, Jeffrey J.; Hawkes, Grant L.

The Advanced Gas Reactor (AGR)-3/4 experiment is the combination of the third and fourth tests conducted within the tristructural isotropic fuel development and qualification research program. The AGR-3/4 test consists of twelve independent capsules containing a fuel stack in the center surrounded by three graphite cylinders and shrouded by a stainless steel shell. This capsule design enables temperature control of both the fuel and the graphite rings by varying the neon/helium gas mixture flowing through the four resulting gaps. Knowledge of fuel and graphite temperatures is crucial for establishing the functional relationship between fission product release and irradiation thermal conditions.more » These temperatures are predicted for each capsule using the commercial finite-element heat transfer code ABAQUS. Uncertainty quantification reveals that the gap size uncertainties are among the dominant factors contributing to predicted temperature uncertainty due to high input sensitivity and uncertainty. Gap size uncertainty originates from the fact that all gap sizes vary with time due to dimensional changes of the fuel compacts and three graphite rings caused by extended exposure to high temperatures and fast neutron irradiation. Gap sizes are estimated using as-fabricated dimensional measurements at the start of irradiation and post irradiation examination dimensional measurements at the end of irradiation. Uncertainties in these measurements provide a basis for quantifying gap size uncertainty. However, lack of gap size measurements during irradiation and lack of knowledge about the dimension change rates lead to gap size modeling assumptions, which could increase gap size uncertainty. In addition, the dimensional measurements are performed at room temperature, and must be corrected to account for thermal expansion of the materials at high irradiation temperatures. Uncertainty in the thermal expansion coefficients for the graphite materials used in the AGR-3/4 capsules also increases gap size uncertainty. This study focuses on analysis of modeling assumptions and uncertainty sources to evaluate their impacts on the gap size uncertainty.« less

Detecting Habitats and Ecosystem Functions Considering the Mesozooplankton Size and Diversity Structures and Environmental Conditions in the Gulf of Lion, NW Mediterranean Sea

NASA Astrophysics Data System (ADS)

Carlotti, F.; Espinasse, B.; Zhou, M.; Jean-Luc, D.

2016-02-01

Environmental conditions and zooplankton size structure and taxonomic diversity were investigated in the Gulf of Lion in May 2010 and January 2011. The integrated physical and biological measurements provided a 3D view with high spatial resolution of the physical and biological variables and their correlations over the whole gulf. The effects of physical processes such as freshwater input, coastal upwelling, and water column mixing by winds on phytoplankton and zooplankton distributions were analyzed using these data. Several analytic tests were performed in order to define several ecoregions representing different habitats of plankton communities. Three habitats were distinguished based on statistical analysis performed on biological and physical variables: (1) the coastal area characterized by shallow waters, high chl a concentrations, and a steep slope of the normalized biomass size spectrum (NBSS); (2) the area affected by the Rhône with high stratification and flat NBSS slope; and (3) the continental shelf with a deep mixed layer, relatively low particle concentrations, and moderate NBSS slope. The zooplankton diversity was characterized by spatial differences in community composition among the Rhône plume area, the coastal shelf, and shelf break waters. Defining habitat is a relevant approach to designing new zooplankton sampling strategies, validating distribution models and including the zooplankton compartment in trophodynamic studies.

Effect of severe plastic deformation on microstructure and mechanical properties of magnesium and aluminium alloys in wide range of strain rates

NASA Astrophysics Data System (ADS)

Skripnyak, Vladimir; Skripnyak, Evgeniya; Skripnyak, Vladimir; Vaganova, Irina; Skripnyak, Nataliya

2013-06-01

Results of researches testify that a grain size have a strong influence on the mechanical behavior of metals and alloys. Ultrafine grained HCP and FCC metal alloys present higher values of the spall strength than a corresponding coarse grained counterparts. In the present study we investigate the effect of grain size distribution on the flow stress and strength under dynamic compression and tension of aluminium and magnesium alloys. Microstructure and grain size distribution in alloys were varied by carrying out severe plastic deformation during the multiple-pass equal channel angular pressing, cyclic constrained groove pressing, and surface mechanical attrition treatment. Tests were performed using a VHS-Instron servo-hydraulic machine. Ultra high speed camera Phantom V710 was used for photo registration of deformation and fracture of specimens in range of strain rates from 0,01 to 1000 1/s. In dynamic regime UFG alloys exhibit a stronger decrease in ductility compared to the coarse grained material. The plastic flow of UFG alloys with a bimodal grain size distribution was highly localized. Shear bands and shear crack nucleation and growth were recorded using high speed photography.

Wind tunnel investigation of a high lift system with pneumatic flow control

NASA Astrophysics Data System (ADS)

Victor, Pricop Mihai; Mircea, Boscoianu; Daniel-Eugeniu, Crunteanu

2016-06-01

Next generation passenger aircrafts require more efficient high lift systems under size and mass constraints, to achieve more fuel efficiency. This can be obtained in various ways: to improve/maintain aerodynamic performance while simplifying the mechanical design of the high lift system going to a single slotted flap, to maintain complexity and improve the aerodynamics even more, etc. Laminar wings have less efficient leading edge high lift systems if any, requiring more performance from the trailing edge flap. Pulsed blowing active flow control (AFC) in the gap of single element flap is investigated for a relatively large model. A wind tunnel model, test campaign and results and conclusion are presented.

Single Atomic Iron Catalysts for Oxygen Reduction in Acidic Media: Particle Size Control and Thermal Activation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Hanguang; Hwang, Sooyeon; Wang, Maoyu

To significantly reduce the cost of proton exchange membrane (PEM) fuel cells, current Pt must be replaced by platinum-metal-group (PGM)-free catalysts for the oxygen reduction reaction (ORR) in acid. We report here a new class of high-performance atomic iron dispersed carbon catalysts through controlled chemical doping of iron ions into zinc-zeolitic imidazolate framework (ZIF), a type of metal-organic framework (MOF). The novel synthetic chemistry enables accurate size control of Fe-doped ZIF catalyst particles with a wide range from 20 to 1000 nm without changing chemical properties, which provides a great opportunity to increase the density of active sites that ismore » determined by the particle size. We elucidated the active site formation mechanism by correlating the chemical and structural changes with thermal activation process for the conversion from Fe-N4 complex containing hydrocarbon networks in ZIF to highly active FeNx sites embedded into carbon. A temperature of 800oC was identified as the critical point to start forming pyridinic nitrogen doping at the edge of the graphitized carbon planes. Further increasing heating temperature to 1100oC leads to increase of graphitic nitrogen, generating possible synergistic effect with FeNx sites to promote ORR activity. The best performing catalyst, which has well-defined particle size around 50 nm and abundance of atomic FeNx sites embedded into carbon structures, achieve a new performance milestone for the ORR in acid including a half-wave potential of 0.85 V vs RHE and only 20 mV loss after 10,000 cycles in O2 saturated H2SO4 electrolyte. The new class PGM-free catalyst with approaching activity to Pt holds great promise for future PEM fuel cells.« less

A vacuum flash-assisted solution process for high-efficiency large-area perovskite solar cells

NASA Astrophysics Data System (ADS)

Li, Xiong; Bi, Dongqin; Yi, Chenyi; Décoppet, Jean-David; Luo, Jingshan; Zakeeruddin, Shaik Mohammed; Hagfeldt, Anders; Grätzel, Michael

2016-07-01

Metal halide perovskite solar cells (PSCs) currently attract enormous research interest because of their high solar-to-electric power conversion efficiency (PCE) and low fabrication costs, but their practical development is hampered by difficulties in achieving high performance with large-size devices. We devised a simple vacuum flash-assisted solution processing method to obtain shiny, smooth, crystalline perovskite films of high electronic quality over large areas. This enabled us to fabricate solar cells with an aperture area exceeding 1 square centimeter, a maximum efficiency of 20.5%, and a certified PCE of 19.6%. By contrast, the best certified PCE to date is 15.6% for PSCs of similar size. We demonstrate that the reproducibility of the method is excellent and that the cells show virtually no hysteresis. Our approach enables the realization of highly efficient large-area PSCs for practical deployment.

Examining variation in working memory capacity and retrieval in cued recall.

PubMed

Unsworth, Nash

2009-05-01

Two experiments examined the notion that individual differences in working memory capacity (WMC) are partially due to differences in search set size in cued recall. High and low WMC individuals performed variants of a cued recall task with either unrelated cue words (Experiment 1) or specific cue phrases (Experiment 2). Across both experiments low WMC individuals recalled fewer items, made more errors, and had longer correct recall latencies than high WMC individuals. Cross-experimental analyses suggested that providing participants with more specific cues decreased the size of the search set, leading to better recall overall. However, these effects were equivalent for high and low WMC. It is argued that these results are consistent with a search model framework in which low WMC individuals search through a larger set of items than high WMC individuals.

Preliminary Sizing Completed for Single- Stage-To-Orbit Launch Vehicles Powered By Rocket-Based Combined Cycle Technology

NASA Technical Reports Server (NTRS)

Roche, Joseph M.

2002-01-01

Single-stage-to-orbit (SSTO) propulsion remains an elusive goal for launch vehicles. The physics of the problem is leading developers to a search for higher propulsion performance than is available with all-rocket power. Rocket-based combined cycle (RBCC) technology provides additional propulsion performance that may enable SSTO flight. Structural efficiency is also a major driving force in enabling SSTO flight. Increases in performance with RBCC propulsion are offset with the added size of the propulsion system. Geometrical considerations must be exploited to minimize the weight. Integration of the propulsion system with the vehicle must be carefully planned such that aeroperformance is not degraded and the air-breathing performance is enhanced. Consequently, the vehicle's structural architecture becomes one with the propulsion system architecture. Geometrical considerations applied to the integrated vehicle lead to low drag and high structural and volumetric efficiency. Sizing of the SSTO launch vehicle (GTX) is itself an elusive task. The weight of the vehicle depends strongly on the propellant required to meet the mission requirements. Changes in propellant requirements result in changes in the size of the vehicle, which in turn, affect the weight of the vehicle and change the propellant requirements. An iterative approach is necessary to size the vehicle to meet the flight requirements. GTX Sizer was developed to do exactly this. The governing geometry was built into a spreadsheet model along with scaling relationships. The scaling laws attempt to maintain structural integrity as the vehicle size is changed. Key aerodynamic relationships are maintained as the vehicle size is changed. The closed weight and center of gravity are displayed graphically on a plot of the synthesized vehicle. In addition, comprehensive tabular data of the subsystem weights and centers of gravity are generated. The model has been verified for accuracy with finite element analysis. The final trajectory was rerun using OTIS (Boeing Corporation's trajectory optimization software package), and the sizing output was incorporated into a solid model of the vehicle using PRO/Engineer computer-aided design software (Parametric Technology Corporation, Waltham, MA).

Performance and state-space analyses of systems using Petri nets

NASA Technical Reports Server (NTRS)

Watson, James Francis, III

1992-01-01

The goal of any modeling methodology is to develop a mathematical description of a system that is accurate in its representation and also permits analysis of structural and/or performance properties. Inherently, trade-offs exist between the level detail in the model and the ease with which analysis can be performed. Petri nets (PN's), a highly graphical modeling methodology for Discrete Event Dynamic Systems, permit representation of shared resources, finite capacities, conflict, synchronization, concurrency, and timing between state changes. By restricting the state transition time delays to the family of exponential density functions, Markov chain analysis of performance problems is possible. One major drawback of PN's is the tendency for the state-space to grow rapidly (exponential complexity) compared to increases in the PN constructs. It is the state space, or the Markov chain obtained from it, that is needed in the solution of many problems. The theory of state-space size estimation for PN's is introduced. The problem of state-space size estimation is defined, its complexities are examined, and estimation algorithms are developed. Both top-down and bottom-up approaches are pursued, and the advantages and disadvantages of each are described. Additionally, the author's research in non-exponential transition modeling for PN's is discussed. An algorithm for approximating non-exponential transitions is developed. Since only basic PN constructs are used in the approximation, theory already developed for PN's remains applicable. Comparison to results from entropy theory show the transition performance is close to the theoretic optimum. Inclusion of non-exponential transition approximations improves performance results at the expense of increased state-space size. The state-space size estimation theory provides insight and algorithms for evaluating this trade-off.

Pore space connectivity and porosity using CT scans of tropical soils

NASA Astrophysics Data System (ADS)

Previatello da Silva, Livia; de Jong Van Lier, Quirijn

2015-04-01

Microtomography has been used in soil physics for characterization and allows non-destructive analysis with high-resolution, yielding a three-dimensional representation of pore space and fluid distribution. It also allows quantitative characterization of pore space, including pore size distribution, shape, connectivity, porosity, tortuosity, orientation, preferential pathways and is also possible predict the saturated hydraulic conductivity using Darcy's equation and a modified Poiseuille's equation. Connectivity of pore space is an important topological property of soil. Together with porosity and pore-size distribution, it governs transport of water, solutes and gases. In order to quantify and analyze pore space (quantifying connectivity of pores and porosity) of four tropical soils from Brazil with different texture and land use, undisturbed samples were collected in São Paulo State, Brazil, with PVC ring with 7.5 cm in height and diameter of 7.5 cm, depth of 10 - 30 cm from soil surface. Image acquisition was performed with a CT system Nikon XT H 225, with technical specifications of dual reflection-transmission target system including a 225 kV, 225 W high performance Xray source equipped with a reflection target with pot size of 3 μm combined with a nano-focus transmission module with a spot size of 1 μm. The images were acquired at specific energy level for each soil type, according to soil texture, and external copper filters were used in order to allow the attenuation of low frequency X-ray photons and passage of one monoenergetic beam. This step was performed aiming minimize artifacts such as beam hardening that may occur during the attenuation in the material interface with different densities within the same sample. Images were processed and analyzed using ImageJ/Fiji software. Retention curve (tension table and the pressure chamber methods), saturated hydraulic conductivity (constant head permeameter), granulometry, soil density and particle density were also performed in laboratory and results were compared with images analyzes.

Cluster randomised crossover trials with binary data and unbalanced cluster sizes: application to studies of near-universal interventions in intensive care.

PubMed

Forbes, Andrew B; Akram, Muhammad; Pilcher, David; Cooper, Jamie; Bellomo, Rinaldo

2015-02-01

Cluster randomised crossover trials have been utilised in recent years in the health and social sciences. Methods for analysis have been proposed; however, for binary outcomes, these have received little assessment of their appropriateness. In addition, methods for determination of sample size are currently limited to balanced cluster sizes both between clusters and between periods within clusters. This article aims to extend this work to unbalanced situations and to evaluate the properties of a variety of methods for analysis of binary data, with a particular focus on the setting of potential trials of near-universal interventions in intensive care to reduce in-hospital mortality. We derive a formula for sample size estimation for unbalanced cluster sizes, and apply it to the intensive care setting to demonstrate the utility of the cluster crossover design. We conduct a numerical simulation of the design in the intensive care setting and for more general configurations, and we assess the performance of three cluster summary estimators and an individual-data estimator based on binomial-identity-link regression. For settings similar to the intensive care scenario involving large cluster sizes and small intra-cluster correlations, the sample size formulae developed and analysis methods investigated are found to be appropriate, with the unweighted cluster summary method performing well relative to the more optimal but more complex inverse-variance weighted method. More generally, we find that the unweighted and cluster-size-weighted summary methods perform well, with the relative efficiency of each largely determined systematically from the study design parameters. Performance of individual-data regression is adequate with small cluster sizes but becomes inefficient for large, unbalanced cluster sizes. When outcome prevalences are 6% or less and the within-cluster-within-period correlation is 0.05 or larger, all methods display sub-nominal confidence interval coverage, with the less prevalent the outcome the worse the coverage. As with all simulation studies, conclusions are limited to the configurations studied. We confined attention to detecting intervention effects on an absolute risk scale using marginal models and did not explore properties of binary random effects models. Cluster crossover designs with binary outcomes can be analysed using simple cluster summary methods, and sample size in unbalanced cluster size settings can be determined using relatively straightforward formulae. However, caution needs to be applied in situations with low prevalence outcomes and moderate to high intra-cluster correlations. © The Author(s) 2014.

Smart Hydrogel Particles: Biomarker Harvesting: One-step affinity purification, size exclusion, and protection against degradation

PubMed Central

Luchini, Alessandra; Geho, David H.; Bishop, Barney; Tran, Duy; Xia, Cassandra; Dufour, Robert; Jones, Clint; Espina, Virginia; Patanarut, Alexis; Zhu, Weidong; Ross, Mark; Tessitore, Alessandra; Petricoin, Emanuel; Liotta, Lance A.

2010-01-01

Disease-associated blood biomarkers exist in exceedingly low concentrations within complex mixtures of high-abundance proteins such as albumin. We have introduced an affinity bait molecule into N-isopropylacrylamide to produce a particle that will perform three independent functions within minutes, in one step, in solution: a) molecular size sieving b) affinity capture of all solution phase target molecules, and c) complete protection of harvested proteins from enzymatic degradation. The captured analytes can be readily electroeluted for analysis. PMID:18076201

Department of Defense Review of the Foreign Comparative Testing Program FY2005-FY2006

DTIC Science & Technology

2007-04-01

Kingdom as a potential alternative to an ongoing domestic development program, which was failing to meet the size, weight , and cost objectives. The...Norway, Switzerland NAMMO, Oerlikon Contraves 0.50 USMC 40mm Training Cartridge MK281 Germany Nico Pyrotechnik 13.14 USMC High Rate-of-Fire .50 Cal...late FY 2003 and, although the system performed as advertised, it did not meet stringent weight requirements. In FY 2005, a down-sized version of

Compact and broadband antenna based on a step-shaped metasurface.

PubMed

Li, Ximing; Yang, Jingjing; Feng, Yun; Yang, Meixia; Huang, Ming

2017-08-07

A metasurface (MS) is highly useful for improving the performance of patch antennae and reducing their size due to their inherent and unique electromagnetic properties. In this paper, a compact and broadband antenna based on a step-shaped metasurface (SMS) at an operating frequency of 4.3 GHz is presented, which is fed by a planar monopole and enabled by selecting an SMS with high selectivity. The SMS consists of an array of metallic step-shaped unit cells underneath the monopole, which provide footprint miniaturization and bandwidth expansion. Numerical results show that the SMS-based antenna with a maximum size of 0.42λ02 (where λ 0 is the operating wavelength in free space) exhibits a 22.3% impedance bandwidth (S11 < -10 dB) and a high gain of more than 7.15 dBi within the passband. Experimental results at microwave frequencies verify the performance of the proposed antenna, demonstrating substantial consistency with the simulation results. The compact and broadband antenna therefore predicts numerous potential applications within modern wireless communication systems.

Toward Superior Capacitive Energy Storage: Recent Advances in Pore Engineering for Dense Electrodes.

PubMed

Liu, Congcong; Yan, Xiaojun; Hu, Fei; Gao, Guohua; Wu, Guangming; Yang, Xiaowei

2018-04-01

With the rapid development of mobile electronics and electric vehicles, future electrochemical capacitors (ECs) need to store as much energy as possible in a rather limited space. As the core component of ECs, dense electrodes that have a high volumetric energy density and superior rate capability are the key to achieving improved energy storage. Here, the significance of and recent progress in the high volumetric performance of dense electrodes are presented. Furthermore, dense yet porous electrodes, as the critical precondition for realizing superior electrochemical capacitive energy, have become a scientific challenge and an attractive research focus. From a pore-engineering perspective, insight into the guidelines of engineering the pore size, connectivity, and wettability is provided to design dense electrodes with different porous architectures toward high-performance capacitive energy storage. The current challenges and future opportunities toward dense electrodes are discussed and include the construction of an orderly porous structure with an appropriate gradient, the coupling of pore sizes with the solvated cations and anions, and the design of coupled pores with diverse electrolyte ions. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Optimization of pencil beam f-theta lens for high-accuracy metrology

NASA Astrophysics Data System (ADS)

Peng, Chuanqian; He, Yumei; Wang, Jie

2018-01-01

Pencil beam deflectometric profilers are common instruments for high-accuracy surface slope metrology of x-ray mirrors in synchrotron facilities. An f-theta optical system is a key optical component of the deflectometric profilers and is used to perform the linear angle-to-position conversion. Traditional optimization procedures of the f-theta systems are not directly related to the angle-to-position conversion relation and are performed with stops of large size and a fixed working distance, which means they may not be suitable for the design of f-theta systems working with a small-sized pencil beam within a working distance range for ultra-high-accuracy metrology. If an f-theta system is not well-designed, aberrations of the f-theta system will introduce many systematic errors into the measurement. A least-squares' fitting procedure was used to optimize the configuration parameters of an f-theta system. Simulations using ZEMAX software showed that the optimized f-theta system significantly suppressed the angle-to-position conversion errors caused by aberrations. Any pencil-beam f-theta optical system can be optimized with the help of this optimization method.

Receiver-Assisted Congestion Control to Achieve High Throughput in Lossy Wireless Networks

NASA Astrophysics Data System (ADS)

Shi, Kai; Shu, Yantai; Yang, Oliver; Luo, Jiarong

2010-04-01

Many applications would require fast data transfer in high-speed wireless networks nowadays. However, due to its conservative congestion control algorithm, Transmission Control Protocol (TCP) cannot effectively utilize the network capacity in lossy wireless networks. In this paper, we propose a receiver-assisted congestion control mechanism (RACC) in which the sender performs loss-based control, while the receiver is performing delay-based control. The receiver measures the network bandwidth based on the packet interarrival interval and uses it to compute a congestion window size deemed appropriate for the sender. After receiving the advertised value feedback from the receiver, the sender then uses the additive increase and multiplicative decrease (AIMD) mechanism to compute the correct congestion window size to be used. By integrating the loss-based and the delay-based congestion controls, our mechanism can mitigate the effect of wireless losses, alleviate the timeout effect, and therefore make better use of network bandwidth. Simulation and experiment results in various scenarios show that our mechanism can outperform conventional TCP in high-speed and lossy wireless environments.

Design and interpretation of anthropometric and fitness testing of basketball players.

PubMed

Drinkwater, Eric J; Pyne, David B; McKenna, Michael J

2008-01-01

The volume of literature on fitness testing in court sports such as basketball is considerably less than for field sports or individual sports such as running and cycling. Team sport performance is dependent upon a diverse range of qualities including size, fitness, sport-specific skills, team tactics, and psychological attributes. The game of basketball has evolved to have a high priority on body size and physical fitness by coaches and players. A player's size has a large influence on the position in the team, while the high-intensity, intermittent nature of the physical demands requires players to have a high level of fitness. Basketball coaches and sport scientists often use a battery of sport-specific physical tests to evaluate body size and composition, and aerobic fitness and power. This testing may be used to track changes within athletes over time to evaluate the effectiveness of training programmes or screen players for selection. Sports science research is establishing typical (or 'reference') values for both within-athlete changes and between-athlete differences. Newer statistical approaches such as magnitude-based inferences have emerged that are providing more meaningful interpretation of fitness testing results in the field for coaches and athletes. Careful selection and implementation of tests, and more pertinent interpretation of data, will enhance the value of fitness testing in high-level basketball programmes. This article presents reference values of fitness and body size in basketball players, and identifies practical methods of interpreting changes within players and differences between players beyond the null-hypothesis.

Development of ultrahigh resolution alpha particle imaging detector using 1 mm channel size Si-PM array

NASA Astrophysics Data System (ADS)

Yamamoto, Seiichi; Kawaguchi, Wataru

2018-06-01

For precise distribution measurements of alpha particles, a high-resolution alpha particle imaging detector is required. Although combining a thin scintillator with a silicon photomultiplier (Si-PM) array is a promising method for achieving high resolution, the spatial resolution is limited. Reducing the size of the Si-PM array is a possible approach to improving the spatial resolution of the alpha particle imaging detector. Consequently, we employed a 1 mm channel size Si-PM array combined with a thin ZnS(Ag) sheet to form an alpha particle imaging detector and evaluated the performance. For the developed alpha particle imaging detector, an Si-PM array with 1 mm x 1 mm channel size arranged 8 x 8 was optically coupled to a ZnS(Ag) sheet with a 1-mm-thick light guide between them. The size of the alpha particle imaging detector was 9.5 mm x 9.5 mm. The spatial resolution of the developed alpha particle imaging detector was 0.14 mm FWHM, and the energy resolution was 74% FWHM for 5.5 MeV alpha particles. The uniformity of the imaging detector at the central part of the field of view (FOV) was ±4.7%. The background count rate was 0.06 counts/min. We obtained various high-resolution phantom images for alpha particles with the developed system. We conclude that the developed imaging detector is promising for high-resolution distribution measurements of alpha particles.

Incremental wind tunnel testing of high lift systems

NASA Astrophysics Data System (ADS)

Victor, Pricop Mihai; Mircea, Boscoianu; Daniel-Eugeniu, Crunteanu

2016-06-01

Efficiency of trailing edge high lift systems is essential for long range future transport aircrafts evolving in the direction of laminar wings, because they have to compensate for the low performance of the leading edge devices. Modern high lift systems are subject of high performance requirements and constrained to simple actuation, combined with a reduced number of aerodynamic elements. Passive or active flow control is thus required for the performance enhancement. An experimental investigation of reduced kinematics flap combined with passive flow control took place in a low speed wind tunnel. The most important features of the experimental setup are the relatively large size, corresponding to a Reynolds number of about 2 Million, the sweep angle of 30 degrees corresponding to long range airliners with high sweep angle wings and the large number of flap settings and mechanical vortex generators. The model description, flap settings, methodology and results are presented.

GPU-based High-Performance Computing for Radiation Therapy

PubMed Central

Jia, Xun; Ziegenhein, Peter; Jiang, Steve B.

2014-01-01

Recent developments in radiotherapy therapy demand high computation powers to solve challenging problems in a timely fashion in a clinical environment. Graphics processing unit (GPU), as an emerging high-performance computing platform, has been introduced to radiotherapy. It is particularly attractive due to its high computational power, small size, and low cost for facility deployment and maintenance. Over the past a few years, GPU-based high-performance computing in radiotherapy has experienced rapid developments. A tremendous amount of studies have been conducted, in which large acceleration factors compared with the conventional CPU platform have been observed. In this article, we will first give a brief introduction to the GPU hardware structure and programming model. We will then review the current applications of GPU in major imaging-related and therapy-related problems encountered in radiotherapy. A comparison of GPU with other platforms will also be presented. PMID:24486639

Tailoring nanostructured MnO2 as anodes for lithium ion batteries with high reversible capacity and initial Coulombic efficiency

NASA Astrophysics Data System (ADS)

Zhang, Lifeng; Song, Jiajia; Liu, Yi; Yuan, Xiaoyan; Guo, Shouwu

2018-03-01

Developing high energy storage lithium ion batteries (LIBs) using manganese oxides as anodes is an attractive challenge due to their high theoretical capacity and abundant resources. However, the manganese oxides anodes still suffer from the low initial Coulombic efficiency and poor rate performance. Herein, we demonstrate that nano-sized morphological engineering is a facile and effective strategy to improve the electrochemical performance of the manganese dioxide (MnO2) for LIBs. The tailored MnO2 nanoparticles (NPs) exhibit high reversible capacity (1095 mAh g-1 at 100 mA g-1), high initial Coulombic efficiency (94.5%) and good rate capability (464 mAh g-1 at 2000 mA g-1). The enhanced electrochemical performance of MnO2 NPs can be attributed to the presences of numerous electrochemically active sites and interspaces among the NPs.