Executive function moderates the role of muscular fitness in determining functional mobility in older adults.

PubMed

Forte, Roberta; Pesce, Caterina; Leite, Joao Costa; De Vito, Giuseppe; Gibney, Eileen R; Tomporowski, Phillip D; Boreham, Colin A G

2013-06-01

Both physical and cognitive factors are known to independently predict functional mobility in older people. However, the combined predictive value of both physical fitness and cognitive factors on functional mobility has been less investigated. The aim of the present study was to assess if cognitive executive functions moderate the role of physical fitness in determining functional mobility of older individuals. Fifty-seven 65- to 75-year-old healthy participants performed tests of functional mobility (habitual and maximal walking speed, maximal walking speed while picking up objects/stepping over obstacles), physical fitness (peak power, knee extensors torque, back/lower limb flexibility, aerobic fitness), and executive function (inhibition and cognitive flexibility). Maximal walking speeds were predicted by physical fitness parameters and their interaction with cognitive factors. Knee extensor torque emerged as the main predictor of all tested locomotor performances at maximal speed. The effect of peak power and back/lower limb flexibility was moderated by executive functions. In particular, inhibition and cognitive flexibility differed in the way in which they moderate the role of fitness. High levels of cognitive flexibility seem necessary to take advantage of leg power for walking at maximal speed. In contrast, high levels of inhibitory capacity seem to compensate for low levels of back/lower limb flexibility when picking up movements are added to a locomotor task. These findings may have important practical implications for the design and implementation of multi-component training programs aimed at optimizing functional abilities in older adults.

[Design and Analysis of CT High-speed Data Transmission Rotating Connector Ring System Retaining Ring].

PubMed

Pan, Li; Cao, Jujiang; Liu, Min; Fu, Weiwei

2017-11-30

High speed data transmission rotating connector system for signal high-speed transmission used in the fixed end and rotating end, it is one of the core component in the CT system. This paper involves structure design and analysis of the retaining ring in the CT high speed data transmission rotating connector system based on the principle of off-axis free space optical transmission. According to the problem of the actual engineering application of space limitations, optical fiber fixed and collimator installation location, we designed the structure of the retaining ring. Using the static analysis function of ANSYS Workbench, it verifies rationality and safety of the strength of retaining ring structure. And based on modal analysis function of ANSYS Workbench, it evaluates the effect of the retaining ring on the stability of the system date transmission, and provides theoretical basis for the feasibility of the structure in practical application.

A rough set-based measurement model study on high-speed railway safety operation.

PubMed

Hu, Qizhou; Tan, Minjia; Lu, Huapu; Zhu, Yun

2018-01-01

Aiming to solve the safety problems of high-speed railway operation and management, one new method is urgently needed to construct on the basis of the rough set theory and the uncertainty measurement theory. The method should carefully consider every factor of high-speed railway operation that realizes the measurement indexes of its safety operation. After analyzing the factors that influence high-speed railway safety operation in detail, a rough measurement model is finally constructed to describe the operation process. Based on the above considerations, this paper redistricts the safety influence factors of high-speed railway operation as 16 measurement indexes which include staff index, vehicle index, equipment index and environment. And the paper also provides another reasonable and effective theoretical method to solve the safety problems of multiple attribute measurement in high-speed railway operation. As while as analyzing the operation data of 10 pivotal railway lines in China, this paper respectively uses the rough set-based measurement model and value function model (one model for calculating the safety value) for calculating the operation safety value. The calculation result shows that the curve of safety value with the proposed method has smaller error and greater stability than the value function method's, which verifies the feasibility and effectiveness.

Comparison Between Oil-mist and Oil-jet Lubrication of High-speed, Small-bore, Angular-contact Ball Bearings

NASA Technical Reports Server (NTRS)

Pinel, Stanley I.; Signer, Hans R.; Zaretsky, Erwin V.

2001-01-01

Parametric tests were conducted with an optimized 35-mm-bore-angular-contact ball bearing on a high-speed, high-temperature bearing tester. Results from both air-oil mist lubrication and oil-jet lubrication systems used to lubricate the bearing were compared to speeds of 2.5 x 10(exp 6) DN. The maximum obtainable speed with air-oil mist lubrication is 2.5 x 10(exp 6) DN. Lower bearing temperatures and higher power losses are obtained with oil-jet lubrication than with air-oil mist lubrication. Bearing power loss is a direct function of oil flow to the bearing and independent of oil delivery system. For a given oil-flow rate, bearing temperature and power loss increase with increases in speed. Bearing life is an inverse function of temperature, the difference in temperature between the individual bearing ring components, and the resultant elastohydrodynamic (EHD) film thicknesses. Bearing life is independent of the oil delivery system except as it affects temperature. Cage slip increased with increases in speed. Cage slip as high as 7 percent was measured and was generally higher with air-oil mist lubrication than with oil-jet lubrication.

World's first telepathology experiments employing WINDS ultra-high-speed internet satellite, nicknamed “KIZUNA”

PubMed Central

Sawai, Takashi; Uzuki, Miwa; Miura, Yasuhiro; Kamataki, Akihisa; Matsumura, Tsubasa; Saito, Kenji; Kurose, Akira; Osamura, Yoshiyuki R.; Yoshimi, Naoki; Kanno, Hiroyuki; Moriya, Takuya; Ishida, Yoji; Satoh, Yohichi; Nakao, Masahiro; Ogawa, Emiko; Matsuo, Satoshi; Kasai, Hiroyuki; Kumagai, Kazuhiro; Motoda, Toshihiro; Hopson, Nathan

2013-01-01

Background: Recent advances in information technology have allowed the development of a telepathology system involving high-speed transfer of high-volume histological figures via fiber optic landlines. However, at present there are geographical limits to landlines. The Japan Aerospace Exploration Agency (JAXA) has developed the “Kizuna” ultra-high speed internet satellite and has pursued its various applications. In this study we experimented with telepathology in collaboration with JAXA using Kizuna. To measure the functionality of the Wideband InterNet working engineering test and Demonstration Satellite (WINDS) ultra-high speed internet satellite in remote pathological diagnosis and consultation, we examined the adequate data transfer speed and stability to conduct telepathology (both diagnosis and conferencing) with functionality, and ease similar or equal to telepathology using fiber-optic landlines. Materials and Methods: We performed experiments for 2 years. In year 1, we tested the usability of the WINDS for telepathology with real-time video and virtual slide systems. These are state-of-the-art technologies requiring massive volumes of data transfer. In year 2, we tested the usability of the WINDS for three-way teleconferencing with virtual slides. Facilities in Iwate (northern Japan), Tokyo, and Okinawa were connected via the WINDS and voice conferenced while remotely examining and manipulating virtual slides. Results: Network function parameters measured using ping and Iperf were within acceptable limits. However; stage movement, zoom, and conversation suffered a lag of approximately 0.8 s when using real-time video, and a delay of 60-90 s was experienced when accessing the first virtual slide in a session. No significant lag or inconvenience was experienced during diagnosis and conferencing, and the results were satisfactory. Our hypothesis was confirmed for both remote diagnosis using real-time video and virtual slide systems, and also for teleconferencing using virtual slide systems with voice functionality. Conclusions: Our results demonstrate the feasibility of ultra-high-speed internet satellite networks for use in telepathology. Because communications satellites have less geographical and infrastructural requirements than landlines, ultra-high-speed internet satellite telepathology represents a major step toward alleviating regional disparity in the quality of medical care. PMID:24244882

Functional and Structural Correlates of Motor Speed in the Cerebellar Anterior Lobe

PubMed Central

Wenzel, Uwe; Taubert, Marco; Ragert, Patrick; Krug, Jürgen; Villringer, Arno

2014-01-01

In athletics, motor performance is determined by different abilities such as technique, endurance, strength and speed. Based on animal studies, motor speed is thought to be encoded in the basal ganglia, sensorimotor cortex and the cerebellum. The question arises whether there is a unique structural feature in the human brain, which allows “power athletes” to perform a simple foot movement significantly faster than “endurance athletes”. We acquired structural and functional brain imaging data from 32 track-and-field athletes. The study comprised of 16 “power athletes” requiring high speed foot movements (sprinters, jumpers, throwers) and 16 endurance athletes (distance runners) which in contrast do not require as high speed foot movements. Functional magnetic resonance imaging (fMRI) was used to identify speed specific regions of interest in the brain during fast and slow foot movements. Anatomical MRI scans were performed to assess structural grey matter volume differences between athletes groups (voxel based morphometry). We tested maximum movement velocity of plantarflexion (PF-Vmax) and acquired electromyographical activity of the lateral and medial gastrocnemius muscle. Behaviourally, a significant difference between the two groups of athletes was noted in PF-Vmax and fMRI indicates that fast plantarflexions are accompanied by increased activity in the cerebellar anterior lobe. The same region indicates increased grey matter volume for the power athletes compared to the endurance counterparts. Our results suggest that speed-specific neuro-functional and -structural differences exist between power and endurance athletes in the peripheral and central nervous system. PMID:24800742

Predictors of older drivers' involvement in high-range speeding behavior.

PubMed

Chevalier, Anna; Coxon, Kristy; Rogers, Kris; Chevalier, Aran John; Wall, John; Brown, Julie; Clarke, Elizabeth; Ivers, Rebecca; Keay, Lisa

2017-02-17

Even small increases in vehicle speed raise crash risk and resulting injury severity. Older drivers are at increased risk of involvement in casualty crashes and injury compared to younger drivers. However, there is little objective evidence about older drivers' speeding. This study investigates the nature and predictors of high-range speeding among drivers aged 75-94 years. Speed per second was estimated using Global Positioning System devices installed in participants' vehicles. High-range speeding events were defined as traveling an average 10+km/h above the speed limit over 30 seconds. Descriptive analysis examined speeding events by participant characteristics and mileage driven. Regression analyses were used to examine the association between involvement in high-range speeding events and possible predictive factors. Most (96%, 182/190) participants agreed to have their vehicle instrumented, and speeding events were accurately recorded for 97% (177/182) of participants. While 77% (136/177) of participants were involved in one or more high-range events, 42% (75/177) were involved in greater than five events during 12-months of data collection. Participants involved in high-range events drove approximately twice as many kilometres as those not involved. High-range events tended to be infrequent (median = 6 per 10,000 km; IQR = 2-18). The rate of high-range speeding was associated with better cognitive function and attention to the driving environment. This suggests those older drivers with poorer cognition and visual attention may drive more cautiously, thereby reducing their high-range speeding behavior.

An extended heterogeneous car-following model accounting for anticipation driving behavior and mixed maximum speeds

NASA Astrophysics Data System (ADS)

Sun, Fengxin; Wang, Jufeng; Cheng, Rongjun; Ge, Hongxia

2018-02-01

The optimal driving speeds of the different vehicles may be different for the same headway. In the optimal velocity function of the optimal velocity (OV) model, the maximum speed vmax is an important parameter determining the optimal driving speed. A vehicle with higher maximum speed is more willing to drive faster than that with lower maximum speed in similar situation. By incorporating the anticipation driving behavior of relative velocity and mixed maximum speeds of different percentages into optimal velocity function, an extended heterogeneous car-following model is presented in this paper. The analytical linear stable condition for this extended heterogeneous traffic model is obtained by using linear stability theory. Numerical simulations are carried out to explore the complex phenomenon resulted from the cooperation between anticipation driving behavior and heterogeneous maximum speeds in the optimal velocity function. The analytical and numerical results all demonstrate that strengthening driver's anticipation effect can improve the stability of heterogeneous traffic flow, and increasing the lowest value in the mixed maximum speeds will result in more instability, but increasing the value or proportion of the part already having higher maximum speed will cause different stabilities at high or low traffic densities.

High-speed resistance training is more effective than low-speed resistance training to increase functional capacity and muscle performance in older women.

PubMed

Ramírez-Campillo, Rodrigo; Castillo, Angélica; de la Fuente, Carlos I; Campos-Jara, Christian; Andrade, David C; Álvarez, Cristian; Martínez, Cristian; Castro-Sepúlveda, Mauricio; Pereira, Ana; Marques, Mário C; Izquierdo, Mikel

2014-10-01

To examine the effects of 12 weeks of high-speed resistance training (RT) versus low-speed RT on muscle strength [one repetition of maximum leg-press (1RMLP) and bench-press (1RMBP), plus dominant (HGd) and non-dominant maximum isometric handgrip], power [counter-movement jump (CMJ), ball throwing (BT) and 10-m walking sprint (S10)], functional performance [8-foot up-and-go test (UG) and sit-to-stand test (STS)], and perceived quality of life in older women. 45 older women were divided into a high-speed RT group [EG, n=15, age=66.3±3.7y], a low-speed RT group [SG, n=15, age=68.7±6.4y] and a control group [CG, n=15, age=66.7±4.9y]. The SG and EG were submitted to a similar 12-week RT program [3 sets of 8 reps at 40-75% of the one-repetition maximum (1

Safety of High Speed Ground Transportation Systems : Analytical Methodology for Safety Validation of Computer Controlled Subsystems : Volume 2. Development of a Safety Validation Methodology

DOT National Transportation Integrated Search

1995-01-01

This report describes the development of a methodology designed to assure that a sufficiently high level of safety is achieved and maintained in computer-based systems which perform safety cortical functions in high-speed rail or magnetic levitation ...

SPLASSH: Open source software for camera-based high-speed, multispectral in-vivo optical image acquisition

PubMed Central

Sun, Ryan; Bouchard, Matthew B.; Hillman, Elizabeth M. C.

2010-01-01

Camera-based in-vivo optical imaging can provide detailed images of living tissue that reveal structure, function, and disease. High-speed, high resolution imaging can reveal dynamic events such as changes in blood flow and responses to stimulation. Despite these benefits, commercially available scientific cameras rarely include software that is suitable for in-vivo imaging applications, making this highly versatile form of optical imaging challenging and time-consuming to implement. To address this issue, we have developed a novel, open-source software package to control high-speed, multispectral optical imaging systems. The software integrates a number of modular functions through a custom graphical user interface (GUI) and provides extensive control over a wide range of inexpensive IEEE 1394 Firewire cameras. Multispectral illumination can be incorporated through the use of off-the-shelf light emitting diodes which the software synchronizes to image acquisition via a programmed microcontroller, allowing arbitrary high-speed illumination sequences. The complete software suite is available for free download. Here we describe the software’s framework and provide details to guide users with development of this and similar software. PMID:21258475

A high speed, portable, multi-function, weigh-in-motion (WIM) sensing system and a high performance optical fiber Bragg grating (FBG) demodulator

NASA Astrophysics Data System (ADS)

Zhang, Hongtao; Wei, Zhanxiong; Fan, Lingling; Yang, Shangming; Wang, Pengfei; Cui, Hong-Liang

2010-04-01

A high speed, portable, multi-function WIM sensing system based on Fiber Bragg Grating (FBG) technology is reported in this paper. This system is developed to measure the total weight, the distribution of weight of vehicle in motion, the distance of wheel axles and the distance between left and right wheels. In this system, a temperature control system and a real-time compensation system are employed to eliminate the drifts of optical fiber Fabry-Pérot tunable filter. Carbon Fiber Laminated Composites are used in the sensor heads to obtain high reliability and sensitivity. The speed of tested vehicles is up to 20 mph, the full scope of measurement is 4000 lbs, and the static resolution of sensor head is 20 lbs. The demodulator has high speed (500 Hz) data collection, and high stability. The demodulator and the light source are packed into a 17'' rack style enclosure. The prototype has been tested respectively at Stevens' campus and Army base. Some experiences of avoiding the pitfalls in developing this system are also presented in this paper.

An integrated optimum design approach for high speed prop-rotors including acoustic constraints

NASA Technical Reports Server (NTRS)

Chattopadhyay, Aditi; Wells, Valana; Mccarthy, Thomas; Han, Arris

1993-01-01

The objective of this research is to develop optimization procedures to provide design trends in high speed prop-rotors. The necessary disciplinary couplings are all considered within a closed loop multilevel decomposition optimization process. The procedures involve the consideration of blade-aeroelastic aerodynamic performance, structural-dynamic design requirements, and acoustics. Further, since the design involves consideration of several different objective functions, multiobjective function formulation techniques are developed.

Pedestrian injury risk functions based on contour lines of equal injury severity using real world pedestrian/passenger-car accident data

PubMed Central

Niebuhr, Tobias; Junge, Mirko; Achmus, Stefanie

2013-01-01

Injury risk assessment plays a pivotal role in the assessment of the effectiveness of Advanced Driver Assistance Systems (ADAS) as they specify the injury reduction potential of the system. The usual way to describe injury risks is by use of injury risk functions, i.e. specifying the probability of an injury of a given severity occurring at a specific technical accident severity (collision speed). A method for the generation of a family of risk functions for different levels of injury severity is developed. The injury severity levels are determined by use of a rescaled version of the Injury Severity Score (ISS) namely the ISSx. The injury risk curves for each collision speed is then obtained by fixing the boundary conditions and use of a case-by-case validated GIDAS subset of pedestrian-car accidents (N=852). The resultant functions are of exponential form as opposed to the frequently used logistic regression form. The exponential approach in combination with the critical speed value creates a new injury risk pattern better fitting for high speed/high energy crashes. Presented is a family of pedestrian injury risk functions for an arbitrary injury severity. Thus, the effectiveness of an ADAS can be assessed for mitigation of different injury severities using the same injury risk function and relying on the internal soundness of the risk function with regard to different injury severity levels. For the assessment of emergency braking ADAS, a Zone of Effective Endangerment Increase (ZEEI), the speed interval in which a one percent speed increase results at least in a one percent of injury risk increase, is defined. The methodology presented is kept in such general terms that a direct adaption to other accident configurations is easily done. PMID:24406954

Modern rotor balancing - Emerging technologies

NASA Technical Reports Server (NTRS)

Zorzi, E. S.; Von Pragenau, G. L.

1985-01-01

Modern balancing methods for flexible and rigid rotors are explored. Rigid rotor balancing is performed at several hundred rpm, well below the first bending mode of the shaft. High speed balancing is necessary when the nominal rotational speed is higher than the first bending mode. Both methods introduce weights which will produce rotor responses at given speeds that will be exactly out of phase with the responses of an unbalanced rotor. Modal balancing seeks to add weights which will leave other rotor modes unaffected. Also, influence coefficients can be determined by trial and error addition of weights and recording of their effects on vibration at speeds of interest. The latter method is useful for balancing rotors at other than critical speeds and for performing unified balancing beginning with the first critical speed. Finally, low-speed flexible balancing permits low-speed tests and adjustments of rotor assemblies which will not be accessible when operating in their high-speed functional configuration. The method was developed for the high pressure liquid oxygen turbopumps for the Shuttle.

Digital holographic interferometry for characterizing deformable mirrors in aero-optics

NASA Astrophysics Data System (ADS)

Trolinger, James D.; Hess, Cecil F.; Razavi, Payam; Furlong, Cosme

2016-08-01

Measuring and understanding the transient behavior of a surface with high spatial and temporal resolution are required in many areas of science. This paper describes the development and application of a high-speed, high-dynamic range, digital holographic interferometer for high-speed surface contouring with fractional wavelength precision and high-spatial resolution. The specific application under investigation here is to characterize deformable mirrors (DM) employed in aero-optics. The developed instrument was shown capable of contouring a deformable mirror with extremely high-resolution at frequencies exceeding 40 kHz. We demonstrated two different procedures for characterizing the mechanical response of a surface to a wide variety of input forces, one that employs a high-speed digital camera and a second that employs a low-speed, low-cost digital camera. The latter is achieved by cycling the DM actuators with a step input, producing a transient that typically lasts up to a millisecond before reaching equilibrium. Recordings are made at increasing times after the DM initiation from zero to equilibrium to analyze the transient. Because the wave functions are stored and reconstructable, they can be compared with each other to produce contours including absolute, difference, and velocity. High-speed digital cameras recorded the wave functions during a single transient at rates exceeding 40 kHz. We concluded that either method is fully capable of characterizing a typical DM to the extent required by aero-optical engineers.

High-speed atomic force microscopy coming of age

NASA Astrophysics Data System (ADS)

Ando, Toshio

2012-02-01

High-speed atomic force microscopy (HS-AFM) is now materialized. It allows direct visualization of dynamic structural changes and dynamic processes of functioning biological molecules in physiological solutions, at high spatiotemporal resolution. Dynamic molecular events unselectively appear in detail in an AFM movie, facilitating our understanding of how biological molecules operate to function. This review describes a historical overview of technical development towards HS-AFM, summarizes elementary devices and techniques used in the current HS-AFM, and then highlights recent imaging studies. Finally, future challenges of HS-AFM studies are briefly discussed.

Noise isolation system for high-speed circuits

DOEpatents

McNeilly, D.R.

1983-12-29

A noise isolation circuit is provided that consists of a dual function bypass which confines high-speed switching noise to the component or circuit which generates it and isolates the component or circuit from high-frequency noise transients which may be present on the ground and power supply busses. A local circuit ground is provided which is coupled to the system ground by sufficient impedance to force the dissipation of the noise signal in the local circuit or component generating the noise. The dual function bypass network couples high-frequency noise signals generated in the local component or circuit through a capacitor to the local ground while isolating the component or circuit from noise signals which may be present on the power supply busses or system ground. The network is an effective noise isolating system and is applicable to both high-speed analog and digital circuits.

Noise isolation system for high-speed circuits

DOEpatents

McNeilly, David R.

1986-01-01

A noise isolation circuit is provided that consists of a dual function bypass which confines high-speed switching noise to the component or circuit which generates it and isolates the component or circuit from high-frequency noise transients which may be present on the ground and power supply busses. A local circuit ground is provided which is coupled to the system ground by sufficient impedance to force the dissipation of the noise signal in the local circuit or component generating the noise. The dual function bypass network couples high-frequency noise signals generated in the local component or circuit through a capacitor to the local ground while isolating the component or circuit from noise signals which may be present on the power supply busses or system ground. The network is an effective noise isolating system and is applicable to both high-speed analog and digital circuits.

Role of processing speed and depressed mood on encoding, storage, and retrieval memory functions in patients diagnosed with schizophrenia.

PubMed

Brébion, Gildas; David, Anthony S; Bressan, Rodrigo A; Pilowsky, Lyn S

2007-01-01

The role of various types of slowing of processing speed, as well as the role of depressed mood, on each stage of verbal memory functioning in patients diagnosed with schizophrenia was investigated. Mixed lists of high- and low-frequency words were presented, and immediate and delayed free recall and recognition were required. Two levels of encoding were studied by contrasting the relatively automatic encoding of the high-frequency words and the more effortful encoding of the low-frequency words. Storage was studied by contrasting immediate and delayed recall. Retrieval was studied by contrasting free recall and recognition. Three tests of motor and cognitive processing speed were administered as well. Regression analyses involving the three processing speed measures revealed that cognitive speed was the only predictor of the recall and recognition of the low-frequency words. Furthermore, slowing in cognitive speed accounted for the deficit in recall and recognition of the low-frequency words relative to a healthy control group. Depressed mood was significantly associated with recognition of the low-frequency words. Neither processing speed nor depressed mood was associated with storage efficiency. It is concluded that both cognitive speed slowing and depressed mood impact on effortful encoding processes.

75 FR 36071 - Framework for Broadband Internet Service

Federal Register 2010, 2011, 2012, 2013, 2014

2010-06-24

... contractor, Best Copy and Printing, Inc. (BCPI), Portals II, 445 12th Street, SW., Room CY-B402, Washington...-leading high-speed broadband networks--both wired and wireless--lies at the very core of the FCC's mission... subscribers with high-speed Internet access, as well as many applications or functions that can be used with...

Ultra-wideband directional sampler

DOEpatents

McEwan, Thomas E.

1996-01-01

The Ultra-Wideband (UWB) Directional Sampler is a four port device that combines the function of a directional coupler with a high speed sampler. Two of the four ports operate at a high sub-nanosecond speed, in "real time", and the other two ports operate at a slow millisecond-speed, in "equivalent time". A signal flowing inbound to either of the high speed ports is sampled and coupled, in equivalent time, to the adjacent equivalent time port while being isolated from the opposite equivalent time port. A primary application is for a time domain reflectometry (TDR) situation where the reflected pulse returns while the outbound pulse is still being transmitted, such as when the reflecting discontinuity is very close to the TDR apparatus.

Abnormal gait pattern emerges during curved trajectories in high-functioning Parkinsonian patients walking in line at normal speed

PubMed Central

Godi, Marco; Giardini, Marica; Arcolin, Ilaria; Nardone, Antonio; Giordano, Andrea; Schieppati, Marco

2018-01-01

Background Several patients with Parkinson´s disease (PD) can walk normally along straight trajectories, and impairment in their stride length and cadence may not be easily discernible. Do obvious abnormalities occur in these high-functioning patients when more challenging trajectories are travelled, such as circular paths, which normally implicate a graded modulation in the duration of the interlimb gait cycle phases? Methods We compared a cohort of well-treated mildly to moderately affected PD patients to a group of age-matched healthy subjects (HS), by deliberately including HS spontaneously walking at the same speed of the patients with PD. All participants performed, in random order: linear and circular walking (clockwise and counter-clockwise) at self-selected speed. By means of pressure-sensitive insoles, we recorded walking speed, cadence, duration of single support, double support, swing phase, and stride time. Stride length-cadence relationships were built for linear and curved walking. Stride-to-stride variability of temporal gait parameters was also estimated. Results Walking speed, cadence or stride length were not different between PD and HS during linear walking. Speed, cadence and stride length diminished during curved walking in both groups, stride length more in PD than HS. In PD compared to HS, the stride length-cadence relationship was altered during curved walking. Duration of the double-support phase was also increased during curved walking, as was variability of the single support, swing phase and double support phase. Conclusion The spatio-temporal gait pattern and variability are significantly modified in well-treated, high-functioning patients with PD walking along circular trajectories, even when they exhibit no changes in speed in straight-line walking. The increased variability of the gait phases during curved walking is an identifying characteristic of PD. We discuss our findings in term of interplay between control of balance and of locomotor progression: the former is challenged by curved trajectories even in high-functioning patients, while the latter may not be critically affected. PMID:29750815

Optimized Signaling Method for High-Speed Transmission Channels with Higher Order Transfer Function

NASA Astrophysics Data System (ADS)

Ševčík, Břetislav; Brančík, Lubomír; Kubíček, Michal

2017-08-01

In this paper, the selected results from testing of optimized CMOS friendly signaling method for high-speed communications over cables and printed circuit boards (PCBs) are presented and discussed. The proposed signaling scheme uses modified concept of pulse width modulated (PWM) signal which enables to better equalize significant channel losses during data high-speed transmission. Thus, the very effective signaling method to overcome losses in transmission channels with higher order transfer function, typical for long cables and multilayer PCBs, is clearly analyzed in the time and frequency domain. Experimental results of the measurements include the performance comparison of conventional PWM scheme and clearly show the great potential of the modified signaling method for use in low power CMOS friendly equalization circuits, commonly considered in modern communication standards as PCI-Express, SATA or in Multi-gigabit SerDes interconnects.

Variable Delay Element For Jitter Control In High Speed Data Links

DOEpatents

Livolsi, Robert R.

2002-06-11

A circuit and method for decreasing the amount of jitter present at the receiver input of high speed data links which uses a driver circuit for input from a high speed data link which comprises a logic circuit having a first section (1) which provides data latches, a second section (2) which provides a circuit generates a pre-destorted output and for compensating for level dependent jitter having an OR function element and a NOR function element each of which is coupled to two inputs and to a variable delay element as an input which provides a bi-modal delay for pulse width pre-distortion, a third section (3) which provides a muxing circuit, and a forth section (4) for clock distribution in the driver circuit. A fifth section is used for logic testing the driver circuit.

Fault tolerant computer control for a Maglev transportation system

NASA Technical Reports Server (NTRS)

Lala, Jaynarayan H.; Nagle, Gail A.; Anagnostopoulos, George

1994-01-01

Magnetically levitated (Maglev) vehicles operating on dedicated guideways at speeds of 500 km/hr are an emerging transportation alternative to short-haul air and high-speed rail. They have the potential to offer a service significantly more dependable than air and with less operating cost than both air and high-speed rail. Maglev transportation derives these benefits by using magnetic forces to suspend a vehicle 8 to 200 mm above the guideway. Magnetic forces are also used for propulsion and guidance. The combination of high speed, short headways, stringent ride quality requirements, and a distributed offboard propulsion system necessitates high levels of automation for the Maglev control and operation. Very high levels of safety and availability will be required for the Maglev control system. This paper describes the mission scenario, functional requirements, and dependability and performance requirements of the Maglev command, control, and communications system. A distributed hierarchical architecture consisting of vehicle on-board computers, wayside zone computers, a central computer facility, and communication links between these entities was synthesized to meet the functional and dependability requirements on the maglev. Two variations of the basic architecture are described: the Smart Vehicle Architecture (SVA) and the Zone Control Architecture (ZCA). Preliminary dependability modeling results are also presented.

High speed reaction wheels for satellite attitude control and energy storage

NASA Technical Reports Server (NTRS)

Studer, P.; Rodriguez, E.

1985-01-01

The combination of spacecraft attitude control and energy storage (ACES) functions in common hardware, to synergistically maintain three-axis attitude control while supplying electrical power during earth orbital eclipses, allows the generation of control torques by high rotating speed wheels that react against the spacecraft structure via a high efficiency bidirectional energy conversion motor/generator. An ACES system encompasses a minimum of four wheels, controlling power and the three torque vectors. Attention is given to the realization of such a system with composite flywheel rotors that yield high energy density, magnetic suspension technology yielding low losses at high rotational speeds, and an ironless armature permanent magnet motor/generator yielding high energy conversion efficiency.

Sampling optimization for high-speed weigh-in-motion measurements using in-pavement strain-based sensors

NASA Astrophysics Data System (ADS)

Zhang, Zhiming; Huang, Ying; Bridgelall, Raj; Palek, Leonard; Strommen, Robert

2015-06-01

Weigh-in-motion (WIM) measurement has been widely used for weight enforcement, pavement design, freight management, and intelligent transportation systems to monitor traffic in real-time. However, to use such sensors effectively, vehicles must exit the traffic stream and slow down to match their current capabilities. Hence, agencies need devices with higher vehicle passing speed capabilities to enable continuous weight measurements at mainline speeds. The current practices for data acquisition at such high speeds are fragmented. Deployment configurations and settings depend mainly on the experiences of operation engineers. To assure adequate data, most practitioners use very high frequency measurements that result in redundant samples, thereby diminishing the potential for real-time processing. The larger data memory requirements from higher sample rates also increase storage and processing costs. The field lacks a sampling design or standard to guide appropriate data acquisition of high-speed WIM measurements. This study develops the appropriate sample rate requirements as a function of the vehicle speed. Simulations and field experiments validate the methods developed. The results will serve as guidelines for future high-speed WIM measurements using in-pavement strain-based sensors.

Silicon photonic transceiver circuit for high-speed polarization-based discrete variable quantum key distribution

DOE PAGES

Cai, Hong; Long, Christopher M.; DeRose, Christopher T.; ...

2017-01-01

We demonstrate a silicon photonic transceiver circuit for high-speed discrete variable quantum key distribution that employs a common structure for transmit and receive functions. The device is intended for use in polarization-based quantum cryptographic protocols, such as BB84. Our characterization indicates that the circuit can generate the four BB84 states (TE/TM/45°/135° linear polarizations) with >30 dB polarization extinction ratios and gigabit per second modulation speed, and is capable of decoding any polarization bases differing by 90° with high extinction ratios.

Silicon photonic transceiver circuit for high-speed polarization-based discrete variable quantum key distribution.

PubMed

Cai, Hong; Long, Christopher M; DeRose, Christopher T; Boynton, Nicholas; Urayama, Junji; Camacho, Ryan; Pomerene, Andrew; Starbuck, Andrew L; Trotter, Douglas C; Davids, Paul S; Lentine, Anthony L

2017-05-29

We demonstrate a silicon photonic transceiver circuit for high-speed discrete variable quantum key distribution that employs a common structure for transmit and receive functions. The device is intended for use in polarization-based quantum cryptographic protocols, such as BB84. Our characterization indicates that the circuit can generate the four BB84 states (TE/TM/45°/135° linear polarizations) with >30 dB polarization extinction ratios and gigabit per second modulation speed, and is capable of decoding any polarization bases differing by 90° with high extinction ratios.

Silicon photonic transceiver circuit for high-speed polarization-based discrete variable quantum key distribution

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

Cai, Hong; Long, Christopher M.; DeRose, Christopher T.

We demonstrate a silicon photonic transceiver circuit for high-speed discrete variable quantum key distribution that employs a common structure for transmit and receive functions. The device is intended for use in polarization-based quantum cryptographic protocols, such as BB84. Our characterization indicates that the circuit can generate the four BB84 states (TE/TM/45°/135° linear polarizations) with >30 dB polarization extinction ratios and gigabit per second modulation speed, and is capable of decoding any polarization bases differing by 90° with high extinction ratios.

ACE I/D and ACTN3 R/X polymorphisms as potential factors in modulating exercise-related phenotypes in older women in response to a muscle power training stimuli.

PubMed

Pereira, Ana; Costa, Aldo M; Izquierdo, Mikel; Silva, António J; Bastos, Estela; Marques, Mário C

2013-10-01

Genetic variation of the human ACE I/D and ACTN3 R577X polymorphisms subsequent to 12 weeks of high-speed power training on maximal strength (1RM) of the arm and leg muscles, muscle power performance (counter-movement jump), and functional capacity (sit-to-stand test) was examined in older Caucasian women [n = 139; mean age 65.5 (8.2) years; 67.0 (10.0) kg and 1.57 (0.06) m]. Chelex 100 was used for DNA extraction, and genotype was determined by PCR-RFLP methods. Muscular strength, power, and functional testing were conducted at baseline (T1) and after 12 weeks (T2) of high-speed power training. At baseline, the ACE I/D and ACTN3 R/X polymorphisms were not associated with muscle function or muscularity phenotypes in older Caucasian women. After the 12-week high-speed training program, subjects significantly increased their muscular and functional capacity performance (p < 0.05). For both polymorphisms, significant genotype-training interaction (p < 0.05) was found in all muscular performance indices, except for 1RM leg extension in the ACE I/D (p = 0.187). Analyses of the combined effects between genotypes showed significant differences in all parameters (p < 0.05) in response to high-speed power training between the power (ACTN3 RR + RX & ACE DD) versus "non-power" muscularity-oriented genotypes (ACTN3 XX & ACE II + ID)]. Our data suggest that the ACE and ACTN3 genotypes (single or combined) exert a significant influence in the muscle phenotypes of older Caucasian women in response to high-speed power training. Thus, the ACE I/D and ACTN3 R/X polymorphisms are likely factors in modulating exercise-related phenotypes in older women, particularly in response to a resistance training stimuli.

Ultra-wideband directional sampler

DOEpatents

McEwan, T.E.

1996-05-14

The Ultra-Wideband (UWB) Directional Sampler is a four port device that combines the function of a directional coupler with a high speed sampler. Two of the four ports operate at a high sub-nanosecond speed, in ``real time``, and the other two ports operate at a slow millisecond-speed, in ``equivalent time``. A signal flowing inbound to either of the high speed ports is sampled and coupled, in equivalent time, to the adjacent equivalent time port while being isolated from the opposite equivalent time port. A primary application is for a time domain reflectometry (TDR) situation where the reflected pulse returns while the outbound pulse is still being transmitted, such as when the reflecting discontinuity is very close to the TDR apparatus. 3 figs.

Impact of left ventricular assist device speed adjustment on exercise tolerance and markers of wall stress.

PubMed

Hayward, Christopher S; Salamonsen, Robert; Keogh, Anne M; Woodard, John; Ayre, Peter; Prichard, Roslyn; Kotlyar, Eugene; Macdonald, Peter S; Jansz, Paul; Spratt, Phillip

2015-09-01

Left ventricular assist devices are crucial in rehabilitation of patients with end-stage heart failure. Whether cardiopulmonary function is enhanced with higher pump output is unknown. 10 patients (aged 39±16 years, mean±SD) underwent monitored adjustment of pump speed to determine minimum safe low speed and maximum safe high speed at rest. Patients were then randomized to these speed settings and underwent three 6-minute walk tests (6MWT) and symptom-limited cardiopulmonary stress tests (CPX) on separate days. Pump speed settings (low, normal and high) resulted in significantly different resting pump flows of 4.43±0.6, 5.03±0.94, and 5.72±1.2 l/min (P<.001). There was a significant enhancement of pump flows (greater at higher speed settings) with exercise (P<0.05). Increased pump speed was associated with a trend to increased 6MWT distance (P=.10); and CPX exercise time (p=.27). Maximum workload achieved and peak oxygen consumption were significantly different comparing low to high pump speed settings only (P<.05). N-terminal-pro-B-type natriuretic peptide release was significantly reduced at higher pump speed with exercise (P<.01). We have found that alteration of pump speed setting resulted in significant variation in estimated pump flow. The high-speed setting was associated with lower natriuretic hormone release consistent with lower myocardial wall stress. This did not, however, improve exercise tolerance.

The contributions of balance to gait capacity and motor function in chronic stroke.

PubMed

Lee, Kyoung Bo; Lim, Seong Hoon; Kim, Young Dong; Yang, Byung Il; Kim, Kyung Hoon; Lee, Kang Sung; Kim, Eun Ja; Hwang, Byong Yong

2016-06-01

[Purpose] The aim of this study was to identify the contributions of balance to gait and motor function in chronic stroke. [Subjects and Methods] Twenty-three outpatients participated in a cross-sectional assessment. Gait ability was assessed using the functional ambulation category, self-paced 10-m walking speed, and fastest 10-m walking speed. Standing balance and trunk control measures included the Berg Balance Scale and the Trunk Impairment Scale. Univariate and multivariate regression analyses were performed. [Results] Balance was the best predictor of the FAC, self-paced walking speed, and fastest walking speed, accounting for 57% to 61% of the variances. Additionally, the total score of TIS was the only predictor of the motor function of the lower limbs and the dynamic balance of TIS was a predictor of the motor function of the upper limbs, accounting for 41% and 29% of the variance, respectively. [Conclusion] This study demonstrated the relative contribution of standing balance and trunk balance to gait ability and motor function. They show that balance has a high power of explanation of gait ability and that trunk balance is a determinant of motor function rather than gait ability.

The contributions of balance to gait capacity and motor function in chronic stroke

PubMed Central

Lee, Kyoung Bo; Lim, Seong Hoon; Kim, Young Dong; Yang, Byung Il; Kim, Kyung Hoon; Lee, Kang Sung; Kim, Eun Ja; Hwang, Byong Yong

2016-01-01

[Purpose] The aim of this study was to identify the contributions of balance to gait and motor function in chronic stroke. [Subjects and Methods] Twenty-three outpatients participated in a cross-sectional assessment. Gait ability was assessed using the functional ambulation category, self-paced 10-m walking speed, and fastest 10-m walking speed. Standing balance and trunk control measures included the Berg Balance Scale and the Trunk Impairment Scale. Univariate and multivariate regression analyses were performed. [Results] Balance was the best predictor of the FAC, self-paced walking speed, and fastest walking speed, accounting for 57% to 61% of the variances. Additionally, the total score of TIS was the only predictor of the motor function of the lower limbs and the dynamic balance of TIS was a predictor of the motor function of the upper limbs, accounting for 41% and 29% of the variance, respectively. [Conclusion] This study demonstrated the relative contribution of standing balance and trunk balance to gait ability and motor function. They show that balance has a high power of explanation of gait ability and that trunk balance is a determinant of motor function rather than gait ability. PMID:27390395

Optimum Design of High Speed Prop-Rotors

NASA Technical Reports Server (NTRS)

Chattopadhyay, Aditi

1992-01-01

The objective of this research is to develop optimization procedures to provide design trends in high speed prop-rotors. The necessary disciplinary couplings are all considered within a closed loop optimization process. The procedures involve the consideration of blade aeroelastic, aerodynamic performance, structural and dynamic design requirements. Further, since the design involves consideration of several different objectives, multiobjective function formulation techniques are developed.

Resveratrol Prevents High Fluence Red Light-Emitting Diode Reactive Oxygen Species-Mediated Photoinhibition of Human Skin Fibroblast Migration.

PubMed

Mamalis, Andrew; Koo, Eugene; Isseroff, R Rivkah; Murphy, William; Jagdeo, Jared

2015-01-01

Skin fibrosis is a significant medical problem that leads to a functional, aesthetic, and psychosocial impact on quality-of-life. Light-emitting diode-generated 633-nm red light (LED-RL) is part of the visible light spectrum that is not known to cause DNA damage and is considered a safe, non-invasive, inexpensive, and portable potential alternative to ultraviolet phototherapy that may change the treatment paradigm of fibrotic skin disease. The goal of our study was to investigate the how reactive oxygen species (ROS) free radicals generated by high fluence LED-RL inhibit the migration of skin fibroblasts, the main cell type involved in skin fibrosis. Fibroblast migration speed is increased in skin fibrosis, and we studied cellular migration speed of cultured human skin fibroblasts as a surrogate measure of high fluence LED-RL effect on fibroblast function. To ascertain the inhibitory role of LED-RL generated ROS on migration speed, we hypothesized that resveratrol, a potent antioxidant, could prevent the photoinhibitory effects of high fluence LED-RL on fibroblast migration speed. High fluence LED-RL generated ROS were measured by flow cytometry analysis using dihydrorhodamine (DHR). For purposes of comparison, we assessed the effects of ROS generated by hydrogen peroxide (H2O2) on fibroblast migration speed and the ability of resveratrol, a well known antioxidant, to prevent LED-RL and H2O2 generated ROS-associated changes in fibroblast migration speed. To determine whether resveratrol could prevent the high fluence LED-RL ROS-mediated photoinhibition of human skin fibroblast migration, treated cells were incubated with resveratrol at concentrations of 0.0001% and 0.001% for 24 hours, irradiated with high fluences LED-RL of 480, 640, and 800 J/cm2. High fluence LED-RL increases intracellular fibroblast ROS and decreases fibroblast migration speed. LED-RL at 480, 640 and 800 J/cm2 increased ROS levels to 132.8%, 151.0%, and 158.4% relative to matched controls, respectively. These LED-RL associated increases in ROS were prevented by pretreating cells with 0.0001% or 0.001% resveratrol. Next, we quantified the effect of hydrogen peroxide (H2O2)-associated ROS on fibroblast migration speed, and found that while H2O2-associated ROS significantly decreased relative fibroblast migration speed, pretreatment with 0.0001% or 0.001% resveratrol significantly prevented the decreases in migration speed. Furthermore, we found that LED-RL at 480, 640 and 800 J/cm2 decreased fibroblast migration speed to 83.0%, 74.4%, and 68.6% relative to matched controls, respectively. We hypothesized that these decreases in fibroblast migration speed were due to associated increases in ROS generation. Pretreatment with 0.0001% and 0.001% resveratrol prevented the LED-RL associated decreases in migration speed. High fluence LED-RL increases ROS and is associated with decreased fibroblast migration speed. We provide mechanistic support that the decreased migration speed associated with high fluence LED-RL is mediated by ROS, by demonstrating that resveratrol prevents high fluence LED-RL associated migration speed change. These data lend support to an increasing scientific body of evidence that high fluence LED-RL has anti-fibrotic properties. We hypothesize that our findings may result in a greater understanding of the fundamental mechanisms underlying visible light interaction with skin and we anticipate clinicians and other researchers may utilize these pathways for patient benefit.

Effect of elastic band-based high-speed power training on cognitive function, physical performance and muscle strength in older women with mild cognitive impairment.

PubMed

Yoon, Dong Hyun; Kang, Dongheon; Kim, Hee-Jae; Kim, Jin-Soo; Song, Han Sol; Song, Wook

2017-05-01

The effectiveness of resistance training in improving cognitive function in older adults is well demonstrated. In particular, unconventional high-speed resistance training can improve muscle power development. In the present study, the effectiveness of 12 weeks of elastic band-based high-speed power training (HSPT) was examined. Participants were randomly assigned into a HSPT group (n = 14, age 75.0 ± 0.9 years), a low-speed strength training (LSST) group (n = 9, age 76.0 ± 1.3 years) and a control group (CON; n = 7, age 78.0 ± 1.0 years). A 1-h exercise program was provided twice a week for 12 weeks for the HSPT and LSST groups, and balance and tone exercises were carried out by the CON group. Significant increases in levels of cognitive function, physical function, and muscle strength were observed in both the HSPT and LSST groups. In cognitive function, significant improvements in the Mini-Mental State Examination and Montreal Cognitive Assessment were seen in both the HSPT and LSST groups compared with the CON group. In physical functions, Short Physical Performance Battery scores were increased significantly in the HSPT and LSST groups compared with the CON group. In the 12 weeks of elastic band-based training, the HSPT group showed greater improvements in older women with mild cognitive impairment than the LSST group, although both regimens were effective in improving cognitive function, physical function and muscle strength. We conclude that elastic band-based HSPT, as compared with LSST, is more efficient in helping older women with mild cognitive impairment to improve cognitive function, physical performance and muscle strength. Geriatr Gerontol Int 2017; 17: 765-772. © 2016 Japan Geriatrics Society.

[The Performance Analysis for Lighting Sources in Highway Tunnel Based on Visual Function].

PubMed

Yang, Yong; Han, Wen-yuan; Yan, Ming; Jiang, Hai-feng; Zhu, Li-wei

2015-10-01

Under the condition of mesopic vision, the spectral luminous efficiency function is shown as a series of curves. Its peak wavelength and intensity are affected by light spectrum, background brightness and other aspects. The impact of light source to lighting visibility could not be carried out via a single optical parametric characterization. The reaction time of visual cognition is regard as evaluating indexes in this experiment. Under the condition of different speed and luminous environment, testing visual cognition based on vision function method. The light sources include high pressure sodium, electrodeless fluorescent lamp and white LED with three kinds of color temperature (the range of color temperature is from 1 958 to 5 537 K). The background brightness value is used for basic section of highway tunnel illumination and general outdoor illumination, its range is between 1 and 5 cd x m(-)2. All values are in the scope of mesopic vision. Test results show that: under the same condition of speed and luminance, the reaction time of visual cognition that corresponding to high color temperature of light source is shorter than it corresponding to low color temperature; the reaction time corresponding to visual target in high speed is shorter than it in low speed. At the end moment, however, the visual angle of target in observer's visual field that corresponding to low speed was larger than it corresponding to high speed. Based on MOVE model, calculating the equivalent luminance of human mesopic vision, which is on condition of different emission spectrum and background brightness that formed by test lighting sources. Compared with photopic vision result, the standard deviation (CV) of time-reaction curve corresponding to equivalent brightness of mesopic vision is smaller. Under the condition of mesopic vision, the discrepancy between equivalent brightness of different lighting source and photopic vision, that is one of the main reasons for causing the discrepancy of visual recognition. The emission spectrum peak of GaN chip is approximate to the wave length peak of efficiency function in photopic vision. The lighting visual effect of write LED in high color temperature is better than it in low color temperature and electrodeless fluorescent lamp. The lighting visual effect of high pressure sodium is weak. Because of its peak value is around the Na+ characteristic spectra.

Real-time color measurement using active illuminant

NASA Astrophysics Data System (ADS)

Tominaga, Shoji; Horiuchi, Takahiko; Yoshimura, Akihiko

2010-01-01

This paper proposes a method for real-time color measurement using active illuminant. A synchronous measurement system is constructed by combining a high-speed active spectral light source and a high-speed monochrome camera. The light source is a programmable spectral source which is capable of emitting arbitrary spectrum in high speed. This system is the essential advantage of capturing spectral images without using filters in high frame rates. The new method of real-time colorimetry is different from the traditional method based on the colorimeter or the spectrometers. We project the color-matching functions onto an object surface as spectral illuminants. Then we can obtain the CIE-XYZ tristimulus values directly from the camera outputs at every point on the surface. We describe the principle of our colorimetric technique based on projection of the color-matching functions and the procedure for realizing a real-time measurement system of a moving object. In an experiment, we examine the performance of real-time color measurement for a static object and a moving object.

Determination of the geophysical model function of NSCAT and its corresponding variance by the use of neural networks

NASA Astrophysics Data System (ADS)

Mejia, C.; Badran, F.; Bentamy, A.; Crepon, M.; Thiria, S.; Tran, N.

1999-05-01

We have computed two geophysical model functions (one for the vertical and one for the horizontal polarization) for the NASA scatterometer (NSCAT) by using neural networks. These neural network geophysical model functions (NNGMFs) were estimated with NSCAT scatterometer σO measurements collocated with European Centre for Medium-Range Weather Forecasts analyzed wind vectors during the period January 15 to April 15, 1997. We performed a student t test showing that the NNGMFs estimate the NSCAT σO with a confidence level of 95%. Analysis of the results shows that the mean NSCAT signal depends on the incidence angle and the wind speed and presents the classical biharmonic modulation with respect to the wind azimuth. NSCAT σO increases with respect to the wind speed and presents a well-marked change at around 7 m s-1. The upwind-downwind amplitude is higher for the horizontal polarization signal than for vertical polarization, indicating that the use of horizontal polarization can give additional information for wind retrieval. Comparison of the σO computed by the NNGMFs against the NSCAT-measured σO show a quite low rms, except at low wind speeds. We also computed two specific neural networks for estimating the variance associated to these GMFs. The variances are analyzed with respect to geophysical parameters. This led us to compute the geophysical signal-to-noise ratio, i.e., Kp. The Kp values are quite high at low wind speed and decrease at high wind speed. At constant wind speed the highest Kp are at crosswind directions, showing that the crosswind values are the most difficult to estimate. These neural networks can be expressed as analytical functions, and FORTRAN subroutines can be provided.

Progress Toward Affordable High Fidelity Combustion Simulations Using Filtered Density Functions for Hypersonic Flows in Complex Geometries

NASA Technical Reports Server (NTRS)

Drozda, Tomasz G.; Quinlan, Jesse R.; Pisciuneri, Patrick H.; Yilmaz, S. Levent

2012-01-01

Significant progress has been made in the development of subgrid scale (SGS) closures based on a filtered density function (FDF) for large eddy simulations (LES) of turbulent reacting flows. The FDF is the counterpart of the probability density function (PDF) method, which has proven effective in Reynolds averaged simulations (RAS). However, while systematic progress is being made advancing the FDF models for relatively simple flows and lab-scale flames, the application of these methods in complex geometries and high speed, wall-bounded flows with shocks remains a challenge. The key difficulties are the significant computational cost associated with solving the FDF transport equation and numerically stiff finite rate chemistry. For LES/FDF methods to make a more significant impact in practical applications a pragmatic approach must be taken that significantly reduces the computational cost while maintaining high modeling fidelity. An example of one such ongoing effort is at the NASA Langley Research Center, where the first generation FDF models, namely the scalar filtered mass density function (SFMDF) are being implemented into VULCAN, a production-quality RAS and LES solver widely used for design of high speed propulsion flowpaths. This effort leverages internal and external collaborations to reduce the overall computational cost of high fidelity simulations in VULCAN by: implementing high order methods that allow reduction in the total number of computational cells without loss in accuracy; implementing first generation of high fidelity scalar PDF/FDF models applicable to high-speed compressible flows; coupling RAS/PDF and LES/FDF into a hybrid framework to efficiently and accurately model the effects of combustion in the vicinity of the walls; developing efficient Lagrangian particle tracking algorithms to support robust solutions of the FDF equations for high speed flows; and utilizing finite rate chemistry parametrization, such as flamelet models, to reduce the number of transported reactive species and remove numerical stiffness. This paper briefly introduces the SFMDF model (highlighting key benefits and challenges), and discusses particle tracking for flows with shocks, the hybrid coupled RAS/PDF and LES/FDF model, flamelet generated manifolds (FGM) model, and the Irregularly Portioned Lagrangian Monte Carlo Finite Difference (IPLMCFD) methodology for scalable simulation of high-speed reacting compressible flows.

An arc tangent function demodulation method of fiber-optic Fabry-Perot high-temperature pressure sensor

NASA Astrophysics Data System (ADS)

Ren, Qianyu; Li, Junhong; Hong, Yingping; Jia, Pinggang; Xiong, Jijun

2017-09-01

A new demodulation algorithm of the fiber-optic Fabry-Perot cavity length based on the phase generated carrier (PGC) is proposed in this paper, which can be applied in the high-temperature pressure sensor. This new algorithm based on arc tangent function outputs two orthogonal signals by utilizing an optical system, which is designed based on the field-programmable gate array (FPGA) to overcome the range limit of the original PGC arc tangent function demodulation algorithm. The simulation and analysis are also carried on. According to the analysis of demodulation speed and precision, the simulation of different numbers of sampling points, and measurement results of the pressure sensor, the arc tangent function demodulation method has good demodulation results: 1 MHz processing speed of single data and less than 1% error showing practical feasibility in the fiber-optic Fabry-Perot cavity length demodulation of the Fabry-Perot high-temperature pressure sensor.

Machine Learning EEG to Predict Cognitive Functioning and Processing Speed Over a 2-Year Period in Multiple Sclerosis Patients and Controls.

PubMed

Kiiski, Hanni; Jollans, Lee; Donnchadha, Seán Ó; Nolan, Hugh; Lonergan, Róisín; Kelly, Siobhán; O'Brien, Marie Claire; Kinsella, Katie; Bramham, Jessica; Burke, Teresa; Hutchinson, Michael; Tubridy, Niall; Reilly, Richard B; Whelan, Robert

2018-05-01

Event-related potentials (ERPs) show promise to be objective indicators of cognitive functioning. The aim of the study was to examine if ERPs recorded during an oddball task would predict cognitive functioning and information processing speed in Multiple Sclerosis (MS) patients and controls at the individual level. Seventy-eight participants (35 MS patients, 43 healthy age-matched controls) completed visual and auditory 2- and 3-stimulus oddball tasks with 128-channel EEG, and a neuropsychological battery, at baseline (month 0) and at Months 13 and 26. ERPs from 0 to 700 ms and across the whole scalp were transformed into 1728 individual spatio-temporal datapoints per participant. A machine learning method that included penalized linear regression used the entire spatio-temporal ERP to predict composite scores of both cognitive functioning and processing speed at baseline (month 0), and months 13 and 26. The results showed ERPs during the visual oddball tasks could predict cognitive functioning and information processing speed at baseline and a year later in a sample of MS patients and healthy controls. In contrast, ERPs during auditory tasks were not predictive of cognitive performance. These objective neurophysiological indicators of cognitive functioning and processing speed, and machine learning methods that can interrogate high-dimensional data, show promise in outcome prediction.

Modelling storm development and the impact when introducing waves, sea spray and heat fluxes

NASA Astrophysics Data System (ADS)

Wu, Lichuan; Rutgersson, Anna; Sahlée, Erik

2015-04-01

In high wind speed conditions, sea spray generated due to intensity breaking waves have big influence on the wind stress and heat fluxes. Measurements show that drag coefficient will decrease in high wind speed. Sea spray generation function (SSGF), an important term of wind stress parameterization in high wind speed, usually treated as a function of wind speed/friction velocity. In this study, we introduce a wave state depended SSGG and wave age depended Charnock number into a high wind speed wind stress parameterization (Kudryavtsev et al., 2011; 2012). The proposed wind stress parameterization and sea spray heat fluxes parameterization from Andreas et al., (2014) were applied to an atmosphere-wave coupled model to test on four storm cases. Compared with measurements from the FINO1 platform in the North Sea, the new wind stress parameterization can reduce the forecast errors of wind in high wind speed range, but not in low wind speed. Only sea spray impacted on wind stress, it will intensify the storms (minimum sea level pressure and maximum wind speed) and lower the air temperature (increase the errors). Only the sea spray impacted on the heat fluxes, it can improve the model performance on storm tracks and the air temperature, but not change much in the storm intensity. If both of sea spray impacted on the wind stress and heat fluxes are taken into account, it has the best performance in all the experiment for minimum sea level pressure and maximum wind speed and air temperature. Andreas, E. L., Mahrt, L., and Vickers, D. (2014). An improved bulk air-sea surface flux algorithm, including spray-mediated transfer. Quarterly Journal of the Royal Meteorological Society. Kudryavtsev, V. and Makin, V. (2011). Impact of ocean spray on the dynamics of the marine atmospheric boundary layer. Boundary-layer meteorology, 140(3):383-410. Kudryavtsev, V., Makin, V., and S, Z. (2012). On the sea-surface drag and heat/mass transfer at strong winds. Technical report, Royal Netherlands Meteorological Institute.

Reaction wheels for kinetic energy storage

NASA Astrophysics Data System (ADS)

Studer, P. A.

1984-11-01

In contrast to all existing reaction wheel implementations, an order of magnitude increase in speed can be obtained efficiently if power to the actuators can be recovered. This allows a combined attitude control-energy storage system to be developed with structure mounted reaction wheels. The feasibility of combining reaction wheels with energy storage wwheels is demonstrated. The power required for control torques is a function of wheel speed but this energy is not dissipated; it is stored in the wheel. The I(2)R loss resulting from a given torque is shown to be constant, independent of the design speed of the motor. What remains, in order to efficiently use high speed wheels (essential for energy storage) for control purposes, is to reduce rotational losses to acceptable levels. Progress was made in permanent magnet motor design for high speed operation. Variable field motors offer more control flexibility and efficiency over a broader speed range.

Reaction wheels for kinetic energy storage

NASA Technical Reports Server (NTRS)

Studer, P. A.

1984-01-01

In contrast to all existing reaction wheel implementations, an order of magnitude increase in speed can be obtained efficiently if power to the actuators can be recovered. This allows a combined attitude control-energy storage system to be developed with structure mounted reaction wheels. The feasibility of combining reaction wheels with energy storage wwheels is demonstrated. The power required for control torques is a function of wheel speed but this energy is not dissipated; it is stored in the wheel. The I(2)R loss resulting from a given torque is shown to be constant, independent of the design speed of the motor. What remains, in order to efficiently use high speed wheels (essential for energy storage) for control purposes, is to reduce rotational losses to acceptable levels. Progress was made in permanent magnet motor design for high speed operation. Variable field motors offer more control flexibility and efficiency over a broader speed range.

SPED light sheet microscopy: fast mapping of biological system structure and function

PubMed Central

Tomer, Raju; Lovett-Barron, Matthew; Kauvar, Isaac; Andalman, Aaron; Burns, Vanessa M.; Sankaran, Sethuraman; Grosenick, Logan; Broxton, Michael; Yang, Samuel; Deisseroth, Karl

2016-01-01

The goal of understanding living nervous systems has driven interest in high-speed and large field-of-view volumetric imaging at cellular resolution. Light-sheet microscopy approaches have emerged for cellular-resolution functional brain imaging in small organisms such as larval zebrafish, but remain fundamentally limited in speed. Here we have developed SPED light sheet microscopy, which combines large volumetric field-of-view via an extended depth of field with the optical sectioning of light sheet microscopy, thereby eliminating the need to physically scan detection objectives for volumetric imaging. SPED enables scanning of thousands of volumes-per-second, limited only by camera acquisition rate, through the harnessing of optical mechanisms that normally result in unwanted spherical aberrations. We demonstrate capabilities of SPED microscopy by performing fast sub-cellular resolution imaging of CLARITY mouse brains and cellular-resolution volumetric Ca2+ imaging of entire zebrafish nervous systems. Together, SPED light sheet methods enable high-speed cellular-resolution volumetric mapping of biological system structure and function. PMID:26687363

Safety of High Speed Guided Ground Transportation Systems: Human Factors Phase I: Function Analyses and Theoretical Considerations

DOT National Transportation Integrated Search

1994-10-01

Although the speed of guided ground transportation continues to increase, the reaction : time as well as the sensory and information processing capacities of on- and off-board : operators remain constant. This report, the first of two examining criti...

High-Speed 3D Printing of High-Performance Thermosetting Polymers via Two-Stage Curing.

PubMed

Kuang, Xiao; Zhao, Zeang; Chen, Kaijuan; Fang, Daining; Kang, Guozheng; Qi, Hang Jerry

2018-04-01

Design and direct fabrication of high-performance thermosets and composites via 3D printing are highly desirable in engineering applications. Most 3D printed thermosetting polymers to date suffer from poor mechanical properties and low printing speed. Here, a novel ink for high-speed 3D printing of high-performance epoxy thermosets via a two-stage curing approach is presented. The ink containing photocurable resin and thermally curable epoxy resin is used for the digital light processing (DLP) 3D printing. After printing, the part is thermally cured at elevated temperature to yield an interpenetrating polymer network epoxy composite, whose mechanical properties are comparable to engineering epoxy. The printing speed is accelerated by the continuous liquid interface production assisted DLP 3D printing method, achieving a printing speed as high as 216 mm h -1 . It is also demonstrated that 3D printing structural electronics can be achieved by combining the 3D printed epoxy composites with infilled silver ink in the hollow channels. The new 3D printing method via two-stage curing combines the attributes of outstanding printing speed, high resolution, low volume shrinkage, and excellent mechanical properties, and provides a new avenue to fabricate 3D thermosetting composites with excellent mechanical properties and high efficiency toward high-performance and functional applications. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The influence of ACE ID and ACTN3 R577X polymorphisms on lower-extremity function in older women in response to high-speed power training.

PubMed

Pereira, Ana; Costa, Aldo M; Leitão, José C; Monteiro, António M; Izquierdo, Mikel; Silva, António J; Bastos, Estela; Marques, Mário C

2013-12-06

We studied the influence of the ACE I/D and ACTN3 R577X polymorphisms (single or combined) on lower-extremity function in older women in response to high-speed power training. One hundred and thirty-nine healthy older Caucasian women participated in this study (age: 65.5 ± 8.2 years, body mass: 67.0 ± 10.0 kg and height: 1.57 ± 0.06 m). Walking speed (S10) performance and functional capacity assessed by the "get-up and go" (GUG) mobility test were measured at baseline (T1) and after a consecutive 12-week period of high-speed power training (40-75% of one repetition maximum in arm and leg extensor exercises; 3 sets 4-12 reps, and two power exercises for upper and lower extremity). Genomic DNA was extracted from blood samples, and genotyping analyses were performed by PCR methods. Genotype distributions between groups were compared by Chi-Square test and the gains in physical performance were analyzed by two-way, repeated-measures ANOVA. There were no significant differences between genotype groups in men or women for adjusted baseline phenotypes (P > 0.05). ACE I/D and ACTN3 polymorphisms showed a significant interaction genotype-training only in S10 (P = 0.012 and P = 0.044, respectively) and not in the GUG test (P = 0.311 and P = 0.477, respectively). Analyses of the combined effects between genotypes showed no other significant differences in all phenotypes (P < 0.05) at baseline. However, in response to high-speed power training, a significant interaction on walking speed (P = 0.048) was observed between the "power" (ACTN3 RR + RX & ACE DD) versus "non-power" muscularity-oriented genotypes (ACTN3 XX & ACE II + ID)]. Thus, ACE I/D and ACTN3 R577X polymorphisms are likely candidates in the modulation of exercise-related gait speed phenotype in older women but not a significant influence in mobility traits.

High-speed ethanol micro-droplet impact on a solid surface

NASA Astrophysics Data System (ADS)

Fujita, Yuta; Kiyama, Akihito; Tagawa, Yoshiyuki

2016-11-01

Recently, droplet impact draws great attention in the fluid mechanics. In previous work, micro-droplet impact on a solid surface at velocities up to 100 m s-1 was studied. However the study was only on water micro-droplets. In this study, we experimentally investigate high-speed impact of ethanol micro-droplets in order to confirm the feature about maximum spreading radius with another liquid. A droplet is generated from a laser-induced high-speed liquid jet. The diameter of droplets is around 80 μm and the velocity is larger than 30 m s-1. The surface tension of ethanol is 22.4 mNm-1 and density is 789 kgm-3. Weber number ranges We >1000. By using a high-speed camera, we investigate the deformation of droplets as a function of Weber number. This work was supported by JSPS KAKENHI Grant Number JP26709007.

Investigations of Section Speed on Rural Roads in Podlaskie Voivodeship

NASA Astrophysics Data System (ADS)

Ziolkowski, Robert

2017-10-01

Excessive speed is one of the most important factors considered in road safety and not only affects the severity of a crash but is also related to the risk of being involved in a crash. In Poland the problem of speeding drivers is widely common. Properly recognized and defined drivers behaviour is the base for any effective activities taken towards road safety improvements. Effective enforcement of speed limits especially on rural road plays an important role but conducted speed investigations basically focus on spot speed omitting travel speed on longer sections of roads which can better reflect driver’s behaviour. Possible solutions for rural roads are limited to administrative means of speed limitations, installations of speed cameras and police enforcement. However due to their limited proved effectiveness new solutions are still being sought. High expectations are associated with the sectional speed system that has recently been introduced in Poland and covered a number of national road sections. The aim of this paper is to investigate section speed on chosen regional and district roads located in Podlaskie Voivodeship. Test sections included 19 road segments varied in terms of functional and geometric characteristics. Speed measurements on regional and district roads were performed with the use of a set of two ANPR (Automatic Number Plate Recognition) cameras. Conducted research allowed to compare driver’s behaviour in terms of travel speed depending on roads’ functional classification as well as to evaluate the influence of chosen geometric parameters on average section speed.

WISC-IV and WIAT-II profiles in children with high-functioning autism.

PubMed

Mayes, Susan Dickerson; Calhoun, Susan L

2008-03-01

Children with high-functioning autism earned above normal scores on the Wechsler Intelligence Scale for Children-Fourth Edition (WISC-IV) Perceptual Reasoning and Verbal Comprehension Indexes and below normal scores on the Working Memory and Processing Speed Indexes and Wechsler Individual Achievement Test-Second Edition (WIAT-II) Written Expression. Full Scale IQ (FSIQ) and reading and math scores were similar to the norm. Profiles were consistent with previous WISC-III research, except that the new WISC-IV motor-free visual reasoning subtests (Matrix Reasoning and Picture Concepts) were the highest of the nonverbal subtests. The WISC-IV may be an improvement over the WISC-III for children with high-functioning autism because it captures their visual reasoning strength, while identifying their attention, graphomotor, and processing speed weaknesses. FSIQ was the best single predictor of academic achievement.

High speed all optical logic gates based on quantum dot semiconductor optical amplifiers.

PubMed

Ma, Shaozhen; Chen, Zhe; Sun, Hongzhi; Dutta, Niloy K

2010-03-29

A scheme to realize all-optical Boolean logic functions AND, XOR and NOT using semiconductor optical amplifiers with quantum-dot active layers is studied. nonlinear dynamics including carrier heating and spectral hole-burning are taken into account together with the rate equations scheme. Results show with QD excited state and wetting layer serving as dual-reservoir of carriers, as well as the ultra fast carrier relaxation of the QD device, this scheme is suitable for high speed Boolean logic operations. Logic operation can be carried out up to speed of 250 Gb/s.

Numerical investigation on an array of Helmholtz resonators for the reduction of micro-pressure waves in modern and future high-speed rail tunnel systems

NASA Astrophysics Data System (ADS)

Tebbutt, J. A.; Vahdati, M.; Carolan, D.; Dear, J. P.

2017-07-01

Previous research has proposed that an array of Helmholtz resonators may be an effective method for suppressing the propagation of pressure and sound waves, generated by a high-speed train entering and moving in a tunnel. The array can be used to counteract environmental noise from tunnel portals and also the emergence of a shock wave in the tunnel. The implementation of an array of Helmholtz resonators in current and future high-speed train-tunnel systems is studied. Wave propagation in the tunnel is modelled using a quasi-one-dimensional formulation, accounting for non-linear effects, wall friction and the diffusivity of sound. A multi-objective genetic algorithm is then used to optimise the design of the array, subject to the geometric constraints of a demonstrative tunnel system and the incident wavefront in order to attenuate the propagation of pressure waves. It is shown that an array of Helmholtz resonators can be an effective countermeasure for various tunnel lengths. In addition, the array can be designed to function effectively over a wide operating envelope, ensuring it will still function effectively as train speeds increase into the future.

[The evaluation of physical development of students].

PubMed

2012-01-01

The article demonstrates that physical health of university students is conditioned by the aggregate of morpho-functional indices and depends on the development of physical qualities of students. The evaluation of mass/height indicators of female students demonstrates the increase of total body size and weakness of body build. The testing of physical readiness testified the ambiguity of high-speed and high-speed/power qualities and results of stamina evaluation.

Magnetically-focusing biochip structures for high-speed active biosensing with improved selectivity.

PubMed

Yoo, Haneul; Lee, Dong Jun; Kim, Daesan; Park, Juhun; Chen, Xing; Hong, Seunghun

2018-06-29

We report a magnetically-focusing biochip structure enabling a single layered magnetic trap-and-release cycle for biosensors with an improved detection speed and selectivity. Here, magnetic beads functionalized with specific receptor molecules were utilized to trap target molecules in a solution and transport actively to and away from the sensor surfaces to enhance the detection speed and reduce the non-specific bindings, respectively. Using our method, we demonstrated the high speed detection of IL-13 antigens with the improved detection speed by more than an order of magnitude. Furthermore, the release step in our method was found to reduce the non-specific bindings and improve the selectivity and sensitivity of biosensors. This method is a simple but powerful strategy and should open up various applications such as ultra-fast biosensors for point-of-care services.

Magnetically-focusing biochip structures for high-speed active biosensing with improved selectivity

NASA Astrophysics Data System (ADS)

Yoo, Haneul; Lee, Dong Jun; Kim, Daesan; Park, Juhun; Chen, Xing; Hong, Seunghun

2018-06-01

We report a magnetically-focusing biochip structure enabling a single layered magnetic trap-and-release cycle for biosensors with an improved detection speed and selectivity. Here, magnetic beads functionalized with specific receptor molecules were utilized to trap target molecules in a solution and transport actively to and away from the sensor surfaces to enhance the detection speed and reduce the non-specific bindings, respectively. Using our method, we demonstrated the high speed detection of IL-13 antigens with the improved detection speed by more than an order of magnitude. Furthermore, the release step in our method was found to reduce the non-specific bindings and improve the selectivity and sensitivity of biosensors. This method is a simple but powerful strategy and should open up various applications such as ultra-fast biosensors for point-of-care services.

A Synchronization Algorithm and Implementation for High-Speed Block Codes Applications. Part 4

NASA Technical Reports Server (NTRS)

Lin, Shu; Zhang, Yu; Nakamura, Eric B.; Uehara, Gregory T.

1998-01-01

Block codes have trellis structures and decoders amenable to high speed CMOS VLSI implementation. For a given CMOS technology, these structures enable operating speeds higher than those achievable using convolutional codes for only modest reductions in coding gain. As a result, block codes have tremendous potential for satellite trunk and other future high-speed communication applications. This paper describes a new approach for implementation of the synchronization function for block codes. The approach utilizes the output of the Viterbi decoder and therefore employs the strength of the decoder. Its operation requires no knowledge of the signal-to-noise ratio of the received signal, has a simple implementation, adds no overhead to the transmitted data, and has been shown to be effective in simulation for received SNR greater than 2 dB.

High-Lift Systems on Commercial Subsonic Airliners

NASA Technical Reports Server (NTRS)

Rudolph, Peter K. C.

1996-01-01

The early breed of slow commercial airliners did not require high-lift systems because their wing loadings were low and their speed ratios between cruise and low speed (takeoff and landing) were about 2:1. However, even in those days the benefit of high-lift devices was recognized. Simple trailing-edge flaps were in use, not so much to reduce landing speeds, but to provide better glide-slope control without sideslipping the airplane and to improve pilot vision over the nose by reducing attitude during low-speed flight. As commercial-airplane cruise speeds increased with the development of more powerful engines, wing loadings increased and a real need for high-lift devices emerged to keep takeoff and landing speeds within reasonable limits. The high-lift devices of that era were generally trailing-edge flaps. When jet engines matured sufficiently in military service and were introduced commercially, airplane speed capability had to be increased to best take advantage of jet engine characteristics. This speed increase was accomplished by introducing the wing sweep and by further increasing wing loading. Whereas increased wing loading called for higher lift coefficients at low speeds, wing sweep actually decreased wing lift at low speeds. Takeoff and landing speeds increased on early jet airplanes, and, as a consequence, runways worldwide had to be lengthened. There are economical limits to the length of runways; there are safety limits to takeoff and landing speeds; and there are speed limits for tires. So, in order to hold takeoff and landing speeds within reasonable limits, more powerful high-lift devices were required. Wing trailing-edge devices evolved from plain flaps to Fowler flaps with single, double, and even triple slots. Wing leading edges evolved from fixed leading edges to a simple Krueger flap, and from fixed, slotted leading edges to two- and three-position slats and variable-camber (VC) Krueger flaps. The complexity of high-lift systems probably peaked on the Boeing 747, which has a VC Krueger flap and triple-slotted, inboard and outboard trailing-edge flaps. Since then, the tendency in high-lift system development has been to achieve high levels of lift with simpler devices in order to reduce fleet acquisition and maintenance costs. The intent of this paper is to: (1) review available high-lift devices, their functions, and design criteria; (2) appraise high-lift systems presently in service on commercial air liners; (3) present personal study results on high-lift systems; (4) develop a weight and cost model for high-lift systems; and (5) discuss the development tendencies of future high-lift systems.

Social strain and executive function across the lifespan: The dark (and light) sides of social engagement

PubMed Central

Tun, Patricia A.; Miller-Martinez, Dana; Lachman, Margie E.; Seeman, Teresa

2012-01-01

We investigated how the association between social strain and cognitive efficiency varies with task demands across adulthood, from latencies on simpler speeded tasks to tests involving executive function. Participants (N= 3280) were drawn from the MIDUS survey, a large, diverse national sample of adults who completed cognitive tests including speeded task-switching (Tun & Lachman, 2008). After controlling for demographic and health variables, we found that higher levels of reported social strain were associated with slower processing speed, particularly for the complex task-switching test relative to simpler speeded tests. Effects of strain were greatest for those with the lowest general cognitive ability. Moreover, those with very high levels of social strain but low levels of social support gave the poorest task-switching performance. These findings provide further evidence for the complex relationship between the social environment and cognition across adulthood, particularly the association between efficiency of executive functions and negative social interactions. PMID:22873285

Strouhal number for free swimming

NASA Astrophysics Data System (ADS)

Saadat, Mehdi; van Buren, Tyler; Floryan, Daniel; Smits, Alexander; Haj-Hariri, Hossein

2015-11-01

In this work, we present experimental results to explore the implications of free swimming for Strouhal number (as an outcome) in the context of a simple model for a fish that consists of a 2D virtual body (source of drag) and a 2D pitching foil (source of thrust) representing cruising with thunniform locomotion. The results validate the findings of Saadat and Haj-Hariri (2012): for pitching foils thrust coefficient is a function of Strouhal number for all gaits having amplitude less than a certain critical value. Equivalently, given the balance of thrust and drag forces at cruise, Strouhal number is only a function of the shape, i.e. drag coefficient and area, and essentially a constant for high enough swimming speeds for which the mild dependence of drag coefficient on the speed vanishes. Furthermore, a dimensional analysis generalizes the findings. A scaling analysis shows that the variation of Strouhal number with cruising speed is functionally related to the variation of body drag coefficient with speed. Supported by ONR MURI Grant N00014-14-1-0533.

Modeling pedestrian crossing speed profiles considering speed change behavior for the safety assessment of signalized intersections.

PubMed

Iryo-Asano, Miho; Alhajyaseen, Wael K M

2017-11-01

Pedestrian safety is one of the most challenging issues in road networks. Understanding how pedestrians maneuver across an intersection is the key to applying countermeasures against traffic crashes. It is known that the behaviors of pedestrians at signalized crosswalks are significantly different from those in ordinary walking spaces, and they are highly influenced by signal indication, potential conflicts with vehicles, and intersection geometries. One of the most important characteristics of pedestrian behavior at crosswalks is the possible sudden speed change while crossing. Such sudden behavioral change may not be expected by conflicting vehicles, which may lead to hazardous situations. This study aims to quantitatively model the sudden speed changes of pedestrians as they cross signalized crosswalks under uncongested conditions. Pedestrian speed profiles are collected from empirical data and speed change events are extracted assuming that the speed profiles are stepwise functions. The occurrence of speed change events is described by a discrete choice model as a function of the necessary walking speed to complete crossing before the red interval ends, current speed, and the presence of turning vehicles in the conflict area. The amount of speed change before and after the event is modeled using regression analysis. A Monte Carlo simulation is applied for the entire speed profile of the pedestrians. The results show that the model can represent the pedestrian travel time distribution more accurately than the constant speed model. Copyright © 2017 Elsevier Ltd. All rights reserved.

High-speed optical links for UAV applications

NASA Astrophysics Data System (ADS)

Chen, C.; Grier, A.; Malfa, M.; Booen, E.; Harding, H.; Xia, C.; Hunwardsen, M.; Demers, J.; Kudinov, K.; Mak, G.; Smith, B.; Sahasrabudhe, A.; Patawaran, F.; Wang, T.; Wang, A.; Zhao, C.; Leang, D.; Gin, J.; Lewis, M.; Nguyen, D.; Quirk, K.

2017-02-01

High speed optical backbone links between a fleet of UAVs is an integral part of the Facebook connectivity architecture. To support the architecture, the optical terminals need to provide high throughput rates (in excess of tens of Gbps) while achieving low weight and power consumption. The initial effort is to develop and demonstrate an optical terminal capable of meeting the data rate requirements and demonstrate its functions for both air-air and air-ground engagements. This paper is a summary of the effort to date.

Conceptual design of a high-speed electromagnetic switch for a modified flux-coupling-type SFCL and its application in renewable energy system.

PubMed

Chen, Lei; Chen, Hongkun; Yang, Jun; Shu, Zhengyu; He, Huiwen; Shu, Xin

2016-01-01

The modified flux-coupling-type superconducting fault current (SFCL) is a high-efficient electrical auxiliary device, whose basic function is to suppress the short-circuit current by controlling the magnetic path through a high-speed switch. In this paper, the high-speed switch is based on electromagnetic repulsion mechanism, and its conceptual design is carried out to promote the application of the modified SFCL. Regarding that the switch which is consisting of a mobile copper disc, two fixed opening and closing coils, the computational method for the electromagnetic force is discussed, and also the dynamic mathematical model including circuit equation, magnetic field equation as well as mechanical motion equation is theoretically deduced. According to the mathematical modeling and calculation of characteristic parameters, a feasible design scheme is presented, and the high-speed switch's response time can be less than 0.5 ms. For that the modified SFCL is equipped with this high-speed switch, the SFCL's application in a 10 kV micro-grid system with multiple renewable energy sources are assessed in the MATLAB software. The simulations are well able to affirm the SFCL's performance behaviors.

A functional language approach in high-speed digital simulation

NASA Technical Reports Server (NTRS)

Ercegovac, M. D.; Lu, S.-L.

1983-01-01

A functional programming approach for a multi-microprocessor architecture is presented. The language, based on Backus FP, its intermediate form and the translation process are discussed and illustrated with an example. The approach allows performance analysis to be performed at a high level as an aid in program partitioning.

Embedded function methods for compressible high speed turbulent flow

NASA Technical Reports Server (NTRS)

Walker, J. D. A.

1989-01-01

Fundamental issues relating to compressible turbulent flow are addressed. The focus has been on developing methods and testing concepts for attached flows rather than trying to force a conventional law of the wall into a zone of backflow. Although the dynamics of the near-wall flow in an attached turbulent boundary layer are relatively well documented, the dynamical features of a zone of reversed turbulent flow are not, nor are they well understood. Incompressibility introduces effects and issues that have been dealt with only marginally in the literature, therefore, the present work has been focussed on attached high-speed flows. The wall function method has been extended up through the supersonic to hypersonic speeds. Algorithms have been successfully introduced into the code that calculates the flow all the way to the wall, and testing is being carried out for progressively more complex flow situations.

Impact of high-κ dielectric and metal nanoparticles in simultaneous enhancement of programming speed and retention time of nano-flash memory

NASA Astrophysics Data System (ADS)

Pavel, Akeed A.; Khan, Mehjabeen A.; Kirawanich, Phumin; Islam, N. E.

2008-10-01

A methodology to simulate memory structures with metal nanocrystal islands embedded as floating gate in a high-κ dielectric material for simultaneous enhancement of programming speed and retention time is presented. The computational concept is based on a model for charge transport in nano-scaled structures presented earlier, where quantum mechanical tunneling is defined through the wave impedance that is analogous to the transmission line theory. The effects of substrate-tunnel dielectric conduction band offset and metal work function on the tunneling current that determines the programming speed and retention time is demonstrated. Simulation results confirm that a high-κ dielectric material can increase programming current due to its lower conduction band offset with the substrate and also can be effectively integrated with suitable embedded metal nanocrystals having high work function for efficient data retention. A nano-memory cell designed with silver (Ag) nanocrystals embedded in Al 2O 3 has been compared with similar structure consisting of Si nanocrystals in SiO 2 to validate the concept.

Locomotor training with body weight support in SCI: EMG improvement is more optimally expressed at a low testing speed.

PubMed

Meyns, P; Van de Crommert, H W A A; Rijken, H; van Kuppevelt, D H J M; Duysens, J

2014-12-01

Case series. To determine the optimal testing speed at which the recovery of the EMG (electromyographic) activity should be assessed during and after body weight supported (BWS) locomotor training. Tertiary hospital, Sint Maartenskliniek, Nijmegen, The Netherlands. Four participants with incomplete chronic SCI were included for BWS locomotor training; one AIS-C and three AIS-D (according to the ASIA (American Spinal Injury Association) Impairment Scale or AIS). All were at least 5 years after injury. The SCI participants were trained three times a week for a period of 6 weeks. They improved their locomotor function in terms of higher walking speed, less BWS and less assistance needed. To investigate which treadmill speed for EMG assessment reflects the functional improvement most adequately, all participants were assessed weekly using the same two speeds (0.5 and 1.5 km h(-1), referred to as low and high speed, respectively) for 6 weeks. The change in root mean square EMG (RMS EMG) was assessed in four leg muscles; biceps femoris, rectus femoris, gastrocnemius medialis and tibialis anterior. The changes in RMS EMG occurred at similar phases of the step cycle for both walking conditions, but these changes were larger when the treadmill was set at a low speed (0.5 km h(-1)). Improvement in gait is feasible with BWS treadmill training even long after injury. The EMG changes after treadmill training are more optimally expressed using a low rather than a high testing treadmill speed.

High speed machinability of the aerospace alloy AA7075 T6 under different cooling conditions

NASA Astrophysics Data System (ADS)

Imbrogno, Stano; Rinaldi, Sergio; Suarez, Asier Gurruchaga; Arrazola, Pedro J.; Umbrello, Domenico

2018-05-01

This paper describes the results of an experimental investigation aimed to st udy the machinability of AA7075 T6 (160 HV) for aerospace industry at high cutting speeds. The paper investigates the effects of different lubri-cooling strategies (cryogenic, M QL and dry) during high speed turning process on cutting forces, tool wear, chip morphology and cutting temperatures. The cutting speeds selected were 1000m/min, 1250m/min and 1500 m/min, while the feed rate values used were 0.1mm/rev and 0.3 mm/rev. The results of cryogenic and M QL application is compared with dry application. It was found that the cryogenic and M QL lubri-cooling techniques could represent a functional alternative to the common dry cutting application in order to implement a more effect ive high speed turning process. Higher cuttingparameters would be able to increase the productivity and reduce the production costs. The effects of the cutting parameters and on the variables object of study were investigated and the role of the different lubri-cooling conditions was assessed.

FMS: A Format Manipulation System for Automatic Production of Natural Language Documents, Second Edition. Final Report.

ERIC Educational Resources Information Center

Silver, Steven S.

FMS/3 is a system for producing hard copy documentation at high speed from free format text and command input. The system was originally written in assembler language for a 12K IBM 360 model 20 using a high speed 1403 printer with the UCS-TN chain option (upper and lower case). Input was from an IBM 2560 Multi-function Card Machine. The model 20…

Moderators of noise-induced cognitive change in healthy adults.

PubMed

Wright, Bernice Al; Peters, Emmanuelle R; Ettinger, Ulrich; Kuipers, Elizabeth; Kumari, Veena

2016-01-01

Environmental noise causes cognitive impairment, particularly in executive function and episodic memory domains, in healthy populations. However, the possible moderating influences on this relationship are less clear. This study assessed 54 healthy participants (24 men) on a cognitive battery (measuring psychomotor speed, attention, executive function, working memory, and verbal learning and memory) under three (quiet, urban, and social) noise conditions. IQ, subjective noise sensitivity, sleep, personality, paranoia, depression, anxiety, stress, and schizotypy were assessed on a single occasion. We found significantly slower psychomotor speed (urban), reduced working memory and episodic memory (urban and social), and more cautious decision-making (executive function, urban) under noise conditions. There was no effect of sex. Variance in urban noise-induced changes in psychomotor speed, attention, Trail Making B-A (executive function), and immediate recall and social noise-induced changes in verbal fluency (executive function) and immediate recall were explained by a combination of baseline cognition and paranoia, noise sensitivity, sleep, or cognitive disorganization. Higher baseline cognition (but not IQ) predicted greater impairment under urban and social noise for most cognitive variables. Paranoia predicted psychomotor speed, attention, and executive function impairment. Subjective noise sensitivity predicted executive function and memory impairment. Poor sleep quality predicted less memory impairment. Finally, lower levels of cognitive disorganization predicted slower psychomotor speed and greater memory impairment. The identified moderators should be considered in studies aiming to reduce the detrimental effects of occupational and residential noise. These results highlight the importance of studying noise effects in clinical populations characterized by high levels of the paranoia, sleep disturbances, noise sensitivity, and cognitive disorganization.

Moderators of noise-induced cognitive change in healthy adults

PubMed Central

Wright, Bernice AL; Peters, Emmanuelle R; Ettinger, Ulrich; Kuipers, Elizabeth; Kumari, Veena

2016-01-01

Environmental noise causes cognitive impairment, particularly in executive function and episodic memory domains, in healthy populations. However, the possible moderating influences on this relationship are less clear. This study assessed 54 healthy participants (24 men) on a cognitive battery (measuring psychomotor speed, attention, executive function, working memory, and verbal learning and memory) under three (quiet, urban, and social) noise conditions. IQ, subjective noise sensitivity, sleep, personality, paranoia, depression, anxiety, stress, and schizotypy were assessed on a single occasion. We found significantly slower psychomotor speed (urban), reduced working memory and episodic memory (urban and social), and more cautious decision-making (executive function, urban) under noise conditions. There was no effect of sex. Variance in urban noise-induced changes in psychomotor speed, attention, Trail Making B-A (executive function), and immediate recall and social noise-induced changes in verbal fluency (executive function) and immediate recall were explained by a combination of baseline cognition and paranoia, noise sensitivity, sleep, or cognitive disorganization. Higher baseline cognition (but not IQ) predicted greater impairment under urban and social noise for most cognitive variables. Paranoia predicted psychomotor speed, attention, and executive function impairment. Subjective noise sensitivity predicted executive function and memory impairment. Poor sleep quality predicted less memory impairment. Finally, lower levels of cognitive disorganization predicted slower psychomotor speed and greater memory impairment. The identified moderators should be considered in studies aiming to reduce the detrimental effects of occupational and residential noise. These results highlight the importance of studying noise effects in clinical populations characterized by high levels of the paranoia, sleep disturbances, noise sensitivity, and cognitive disorganization. PMID:27157685

High-speed recovery of germanium in a convection-aided mode using functional porous hollow-fiber membranes.

PubMed

Ozawa, I; Saito, K; Sugita, K; Sato, K; Akiba, M; Sugo, T

2000-08-04

A porous hollow-fiber membrane capable of recovery of germanium from a liquid stream was prepared by radiation-induced graft polymerization of an epoxy-group-containing vinyl monomer, glycidyl methacrylate, and subsequent functionalization with 2,2'-iminodiethanol, di-2-propanolamine, N-methylglucamine, and 3-amino-1,2-propanediol. The functional group density was as high as 1.4 mol per kg of the resultant hollow fiber. The polymer chains containing functional groups surrounding the pores enabled a high-speed recovery of germanium during permeation of a germanium oxide (GeO2) solution through the pores of the hollow fiber. Because of a negligible diffusional mass-transfer resistance, germanium concentration changes with the effluent volume, i.e., breakthrough curves, overlapped irrespective of the residence time of the solution, which ranged from 0.37 to 3.7 s across the hollow fiber. After repeated use of adsorption and elution, the adsorption capacity did not deteriorate.

High speed color imaging through scattering media with a large field of view

NASA Astrophysics Data System (ADS)

Zhuang, Huichang; He, Hexiang; Xie, Xiangsheng; Zhou, Jianying

2016-09-01

Optical imaging through complex media has many important applications. Although research progresses have been made to recover optical image through various turbid media, the widespread application of the technology is hampered by the recovery speed, requirement on specific illumination, poor image quality and limited field of view. Here we demonstrate that above-mentioned drawbacks can be essentially overcome. The realization of high speed color imaging through turbid media is successfully carried out by taking into account the media memory effect, the point spread function, the exit pupil of the optical system, and the optimized signal to noise ratio. By retrieving selected speckles with enlarged field of view, high quality image is recovered with a responding speed only determined by the frame rates of the image capturing devices. The immediate application of the technique is expected to register static and dynamic imaging under human skin to recover information with a wearable device.

System architecture of a gallium arsenide one-gigahertz digital IC tester

NASA Technical Reports Server (NTRS)

Fouts, Douglas J.; Johnson, John M.; Butner, Steven E.; Long, Stephen I.

1987-01-01

The design for a 1-GHz digital integrated circuit tester for the evaluation of custom GaAs chips and subsystems is discussed. Technology-related problems affecting the design of a GaAs computer are discussed, with emphasis on the problems introduced by long printed-circuit-board interconnect. High-speed interface modules provide a link between the low-speed microprocessor and the chip under test. Memory-multiplexer and memory-shift register architectures for the storage of test vectors are described in addition to an architecture for local data storage consisting of a long chain of GaAs shift registers. The tester is constructed around a VME system card cage and backplane, and very little high-speed interconnect exists between boards. The tester has a three part self-test consisting of a CPU board confidence test, a main memory confidence test, and a high-speed interface module functional test.

Higher Fasting Plasma Glucose Levels, within the Normal Range, are Associated with Decreased Processing Speed in High Functioning Young Elderly.

PubMed

Raizes, Meytal; Elkana, Odelia; Franko, Motty; Ravona Springer, Ramit; Segev, Shlomo; Beeri, Michal Schnaider

2016-01-01

We explored the association of plasma glucose levels within the normal range with processing speed in high functioning young elderly, free of type 2 diabetes mellitus (T2DM). A sample of 41 participants (mean age = 64.7, SD = 10; glucose 94.5 mg/dL, SD = 9.3), were examined with a computerized cognitive battery. Hierarchical linear regression analysis showed that higher plasma glucose levels, albeit within the normal range (<110 mg/dL), were associated with longer reaction times (p <  0.01). These findings suggest that even in the subclinical range and in the absence of T2DM, monitoring plasma glucose levels may have an impact on cognitive function.

High-Speed Numeric Function Generator Using Piecewise Quadratic Approximations

DTIC Science & Technology

2007-09-01

application; User specifies the fuction to approxiamte. % % This programs turns the function provided into an inline function... PRIMARY = < primary file 1> < primary file 2> #SECONDARY = <secondary file 1> <secondary file 2> #CHIP2 = <file to compile to user chip

High-speed atomic force microscopy for observing protein molecules in dynamic action

NASA Astrophysics Data System (ADS)

Ando, T.

2017-02-01

Directly observing protein molecules in dynamic action at high spatiotemporal resolution has long been a holy grail for biological science. To materialize this long quested dream, I have been developing high-speed atomic force microscopy (HS-AFM) since 1993. Tremendous strides were recently accomplished in its high-speed and low-invasive performances. Consequently, various dynamic molecular actions, including bipedal walking of myosin V and rotary propagation of structural changes in F1-ATPase, were successfully captured on video. The visualized dynamic images not only provided irrefutable evidence for speculated actions of the protein molecules but also brought new discoveries inaccessible with other approaches, thus giving great mechanistic insights into how the molecules function. HS-AFM is now transforming "static" structural biology into dynamic structural bioscience.

MRI and Neuropsychological Correlates in African Americans with Hypertension and left vEntricular Hypertrophy.

PubMed

Waldron-Perrine, B; Kisser, J E; Brody, A; Haacke, E M; Dawood, R; Millis, S; Levy, P

2018-04-17

African Americans (AA) are at high risk for hypertension (HTN) and poor blood pressure (BP) control. Persistently elevated BP contributes to cardiovascular morbidity. White matter hyperintensities (WMH) are a definable magnetic resonance imaging (MRI) marker of cerebrovascular injury linked to impairments in higher level thinking (i.e., executive functions), memory formation and speed of perceptual-motor processing. This sub-investigation evaluated neuropsychological functioning in association with WMH on brain MRIs in 23 otherwise healthy hypertensive AAs participating in an NIH-funded study of the effects of Vitamin D on BP and cardiac remodeling in AA patients 30-74 years of age with HTN and left ventricular hypertrophy. Neuropsychological assessment included psychomotor processing speed [(Symbol Digit Modality Test (SDMT) and Trail Making Test], executive functioning (Controlled Oral Word Association Test and Trail Making Test Part B), memory (Rey Auditory Verbal Learning Test), and fine motor functioning (Finger Tapping). Significant correlations (p< .05) were found between volume of periventricular lesions and Trails A (r = .51) and dominant hand finger tapping speed (r = -.69) and between subcortical lesion volume and Trails A (r = .60), both dominant (r = -.62) and non-dominant hand finger tapping speed (r = -.76) and oral SDMT (r = -.60); higher lesion volumes correlated to worse neuropsychological performance. Psychomotor tests including the Trail Making Test and finger tapping speed are sensitive indicators of subclinical deficits in mental processing speed and could serve as early markers of deep subcortical cerebrovascular injury in otherwise-healthy individuals with uncontrolled chronic HTN.

A portable high-speed camera system for vocal fold examinations.

PubMed

Hertegård, Stellan; Larsson, Hans

2014-11-01

In this article, we present a new portable low-cost system for high-speed examinations of the vocal folds. Analysis of glottal vibratory parameters from the high-speed recordings is compared with videostroboscopic recordings. The high-speed system is built around a Fastec 1 monochrome camera, which is used with newly developed software, High-Speed Studio (HSS). The HSS has options for video/image recording, contains a database, and has a set of analysis options. The Fastec/HSS system has been used clinically since 2011 in more than 2000 patient examinations and recordings. The Fastec 1 camera has sufficient time resolution (≥4000 frames/s) and light sensitivity (ISO 3200) to produce images for detailed analyses of parameters pertinent to vocal fold function. The camera can be used with both rigid and flexible endoscopes. The HSS software includes options for analyses of glottal vibrations, such as kymogram, phase asymmetry, glottal area variation, open and closed phase, and angle of vocal fold abduction. It can also be used for separate analysis of the left and vocal fold movements, including maximum speed during opening and closing, a parameter possibly related to vocal fold elasticity. A blinded analysis of 32 patients with various voice disorders examined with both the Fastec/HSS system and videostroboscopy showed that the high-speed recordings were significantly better for the analysis of glottal parameters (eg, mucosal wave and vibration asymmetry). The monochrome high-speed system can be used in daily clinical work within normal clinical time limits for patient examinations. A detailed analysis can be made of voice disorders and laryngeal pathology at a relatively low cost. Copyright © 2014 The Voice Foundation. Published by Elsevier Inc. All rights reserved.

Domains of cognitive function in early old age: which ones are predicted by pre-retirement psychosocial work characteristics?

PubMed Central

Sabbath, Erika; Andel, Ross; Zins, Marie; Goldberg, Marcel; Berr, Claudine

2016-01-01

Background Psychosocial work characteristics may predict cognitive functioning after retirement. However, little research has explored specific cognitive domains associated with psychosocial work environments. Our study tested whether exposure to job demands, job control, and their combination during working life predicted post-retirement performance on eight cognitive tests. Methods We used data from French GAZEL cohort members who had undergone post-retirement cognitive testing (n=2,149). Psychosocial job characteristics were measured on average four years before retirement using Karasek’s Job Content Questionnaire (job demands, job control, demand-control combinations). We tested associations between these exposures and post-retirement performance on tests of executive function, visual-motor speed, psycho-motor speed, verbal memory, and verbal fluency using OLS regression. Results Low job control during working life was negatively associated with executive function, psychomotor speed, phonemic fluency, and semantic fluency after retirement (p’s<.05) even after adjustment for demographics, socioeconomic status, health and social behaviours, and vascular risk factors. Both passive (low-demand, low-control) and high-strain (high-demand, low-control) jobs were associated with lower scores on phonemic and semantic fluency when compared to low-strain (low-demand, high-control) jobs. Conclusions Low job control, in combination with both high and low job demands, is associated with post-retirement deficits in some, but not all, cognitive domains. In addition to work stress, associations between passive work and subsequent cognitive function may implicate lack of cognitive engagement at work as a risk factor for future cognitive difficulties. PMID:27188277

Electronic differential control of 2WD electric vehicle considering steering stability

NASA Astrophysics Data System (ADS)

Hua, Yiding; Jiang, Haobin; Geng, Guoqing

2017-03-01

Aiming at the steering wheel differential steering control technology of rear wheel independent driving electric wheel, considering the assisting effect of electronic differential control on vehicle steering, based on the high speed steering characteristic of electric wheel car, the electronic differential speed of auxiliary wheel steering is also studied. A yaw moment control strategy is applied to the vehicle at high speed. Based on the vehicle stability reference value, yaw rate is used to design the fuzzy controller to distribute the driving wheel torque. The simulation results show that the basic electronic differential speed function is realized based on the yaw moment control strategy, while the vehicle stability control is improved and the driving safety is enhanced. On the other hand, the torque control strategy can also assist steering of vehicle.

Controller and interface module for the High-Speed Data Acquisition System correlator/accumulator

NASA Technical Reports Server (NTRS)

Brokl, S. S.

1985-01-01

One complex channel of the High-Speed Data Acquisition System (a subsystem used in the Goldstone solar system radar), consisting of two correlator modules and one accumulator module, is operated by the controller and interface module interfaces are provided to the VAX UNIBUS for computer control, monitor, and test of the controller and correlator/accumulator. The correlator and accumulator modules controlled by this module are the key digital signal processing elements of the Goldstone High-Speed Data Acquisition System. This fully programmable unit provides for a wide variety of correlation and filtering functions operating on a three megaword/second data flow. Data flow is to the VAX by way of the I/O port of a FPS 5210 array processor.

Acoustic Source Modeling for High Speed Air Jets

NASA Technical Reports Server (NTRS)

Goldstein, Marvin E.; Khavaran, Abbas

2005-01-01

The far field acoustic spectra at 90deg to the downstream axis of some typical high speed jets are calculated from two different forms of Lilley s equation combined with some recent measurements of the relevant turbulent source function. These measurements, which were limited to a single point in a low Mach number flow, were extended to other conditions with the aid of a highly developed RANS calculation. The results are compared with experimental data over a range of Mach numbers. Both forms of the analogy lead to predictions that are in excellent agreement with the experimental data at subsonic Mach numbers. The agreement is also fairly good at supersonic speeds, but the data appears to be slightly contaminated by shock-associated noise in this case.

Effect of surface tension on the dynamical behavior of bubble in rotating fluids under low gravity environment

NASA Technical Reports Server (NTRS)

Hung, R. J.; Tsao, Y. D.; Leslie, Fred W.; Hong, B. B.

1988-01-01

Time dependent evolutions of the profile of free surface (bubble shapes) for a cylindrical container partially filled with a Newtonian fluid of constant density, rotating about its axis of symmetry, have been studied. Numerical computations of the dynamics of bubble shapes have been carried out with the following situations: (1) linear functions of spin-up and spin-down in low and microgravity environments, (2) linear functions of increasing and decreasing gravity enviroment in high and low rotating cylidner speeds, (3) step functions of spin-up and spin-down in a low gravity environment, and (4) sinusoidal function oscillation of gravity environment in high and low rotating cylinder speeds. The initial condition of bubble profiles was adopted from the steady-state formulations in which the computer algorithms have been developed by Hung and Leslie (1988), and Hung et al. (1988).

Dynamical behavior of surface tension on rotating fluids in low and microgravity environments

NASA Technical Reports Server (NTRS)

Hung, R. J.; Tsao, Y. D.; Hong, B. B.; Leslie, F. W.

1989-01-01

Consideration is given to the time-dependent evolutions of the free surface profile (bubble shapes) of a cylindrical container, partially filled with a Newtonian fluid of constant density, rotating about its axis of symmetry in low and microgravity environments. The dynamics of the bubble shapes are calculated for four cases: linear time-dependent functions of spin-up and spin-down in low and microgravity, linear time-dependent functions of increasing and decreasing gravity at high and low rotating cylinder speeds, time-dependent step functions of spin-up and spin-down in low gravity, and sinusoidal function oscillation of the gravity environment in high and low rotating cylinder speeds. It is shown that the computer algorithms developed by Hung et al. (1988) may be used to simulate the profile of time-dependent bubble shapes under variations of centrifugal, capillary, and gravity forces.

The Influence of Spatial Resolutions on the Retrieval Accuracy of Sea Surface Wind Speed with Cross-polarized C-band SAR images

NASA Astrophysics Data System (ADS)

Zhang, K.; Han, B.; Mansaray, L. R.; Xu, X.; Guo, Q.; Jingfeng, H.

2017-12-01

Synthetic aperture radar (SAR) instruments on board satellites are valuable for high-resolution wind field mapping, especially for coastal studies. Since the launch of Sentinel-1A on April 3, 2014, followed by Sentinel-1B on April 25, 2016, large amount of C-band SAR data have been added to a growing accumulation of SAR datasets (ERS-1/2, RADARSAT-1/2, ENVISAT). These new developments are of great significance for a wide range of applications in coastal sea areas, especially for high spatial resolution wind resource assessment, in which the accuracy of retrieved wind fields is extremely crucial. Recently, it is reported that wind speeds can also be retrieved from C-band cross-polarized SAR images, which is an important complement to wind speed retrieval from co-polarization. However, there is no consensus on the optimal resolution for wind speed retrieval from cross-polarized SAR images. This paper presents a comparison strategy for investigating the influence of spatial resolutions on sea surface wind speed retrieval accuracy with cross-polarized SAR images. Firstly, for wind speeds retrieved from VV-polarized images, the optimal geophysical C-band model (CMOD) function was selected among four CMOD functions. Secondly, the most suitable C-band cross-polarized ocean (C-2PO) model was selected between two C-2POs for the VH-polarized image dataset. Then, the VH-wind speeds retrieved by the selected C-2PO were compared with the VV-polarized sea surface wind speeds retrieved using the optimal CMOD, which served as reference, at different spatial resolutions. Results show that the VH-polarized wind speed retrieval accuracy increases rapidly with the decrease in spatial resolutions from 100 m to 1000 m, with a drop in RMSE of 42%. However, the improvement in wind speed retrieval accuracy levels off with spatial resolutions decreasing from 1000 m to 5000 m. This demonstrates that the pixel spacing of 1 km may be the compromising choice for the tradeoff between the spatial resolution and wind speed retrieval accuracy with cross-polarized images obtained from RADASAT-2 fine quad polarization mode. Figs. 1 illustrate the variation of the following statistical parameters: Bias, Corr, R2, RMSE and STD as a function of spatial resolution.

WISC-IV and WIAT-II Profiles in Children with High-Functioning Autism

ERIC Educational Resources Information Center

Mayes, Susan Dickerson; Calhoun, Susan L.

2008-01-01

Children with high-functioning autism earned above normal scores on the Wechsler Intelligence Scale for Children-Fourth Edition (WISC-IV) Perceptual Reasoning and Verbal Comprehension Indexes and below normal scores on the Working Memory and Processing Speed Indexes and Wechsler Individual Achievement Test-Second Edition (WIAT-II) Written…

The effect of stimulus strength on the speed and accuracy of a perceptual decision.

PubMed

Palmer, John; Huk, Alexander C; Shadlen, Michael N

2005-05-02

Both the speed and the accuracy of a perceptual judgment depend on the strength of the sensory stimulation. When stimulus strength is high, accuracy is high and response time is fast; when stimulus strength is low, accuracy is low and response time is slow. Although the psychometric function is well established as a tool for analyzing the relationship between accuracy and stimulus strength, the corresponding chronometric function for the relationship between response time and stimulus strength has not received as much consideration. In this article, we describe a theory of perceptual decision making based on a diffusion model. In it, a decision is based on the additive accumulation of sensory evidence over time to a bound. Combined with simple scaling assumptions, the proportional-rate and power-rate diffusion models predict simple analytic expressions for both the chronometric and psychometric functions. In a series of psychophysical experiments, we show that this theory accounts for response time and accuracy as a function of both stimulus strength and speed-accuracy instructions. In particular, the results demonstrate a close coupling between response time and accuracy. The theory is also shown to subsume the predictions of Piéron's Law, a power function dependence of response time on stimulus strength. The theory's analytic chronometric function allows one to extend theories of accuracy to response time.

Analysis of base fuze functioning of HESH ammunitions through high-speed photographic technique

NASA Astrophysics Data System (ADS)

Biswal, T. K.

2007-01-01

High-speed photography plays a major role in a Test Range where the direct access is possible through imaging in order to understand a dynamic process thoroughly and both qualitative and quantitative data are obtained thereafter through image processing and analysis. In one of the trials it was difficult to understand the performance of HESH ammunitions on rolled homogeneous armour. There was no consistency in scab formation even though all other parameters like propellant charge mass, charge temperature, impact velocity etc are maintained constant. To understand the event thoroughly high-speed photography was deployed to have a frontal view of the total process. Clear information of shell impact, embedding of HE propellant on armour and base fuze initiation are obtained. In case of scab forming rounds these three processes are clearly observed in sequence. However in non-scab ones base fuze is initiated before the completion of the embedding process resulting non-availability of threshold thrust on to the armour to cause scab. This has been revealed in two rounds where there was a failure of scab formation. As a quantitative measure, fuze delay was calculated for each round and there after premature functioning of base fuze was ascertained in case of non-scab rounds. Such potency of high-speed photography has been depicted in details in this paper.

Using a high-speed movie camera to evaluate slice dropping in clinical image interpretation with stack mode viewers.

PubMed

Yakami, Masahiro; Yamamoto, Akira; Yanagisawa, Morio; Sekiguchi, Hiroyuki; Kubo, Takeshi; Togashi, Kaori

2013-06-01

The purpose of this study is to verify objectively the rate of slice omission during paging on picture archiving and communication system (PACS) viewers by recording the images shown on the computer displays of these viewers with a high-speed movie camera. This study was approved by the institutional review board. A sequential number from 1 to 250 was superimposed on each slice of a series of clinical Digital Imaging and Communication in Medicine (DICOM) data. The slices were displayed using several DICOM viewers, including in-house developed freeware and clinical PACS viewers. The freeware viewer and one of the clinical PACS viewers included functions to prevent slice dropping. The series was displayed in stack mode and paged in both automatic and manual paging modes. The display was recorded with a high-speed movie camera and played back at a slow speed to check whether slices were dropped. The paging speeds were also measured. With a paging speed faster than half the refresh rate of the display, some viewers dropped up to 52.4 % of the slices, while other well-designed viewers did not, if used with the correct settings. Slice dropping during paging was objectively confirmed using a high-speed movie camera. To prevent slice dropping, the viewer must be specially designed for the purpose and must be used with the correct settings, or the paging speed must be slower than half of the display refresh rate.

A parabolic model of drag coefficient for storm surge simulation in the South China Sea

PubMed Central

Peng, Shiqiu; Li, Yineng

2015-01-01

Drag coefficient (Cd) is an essential metric in the calculation of momentum exchange over the air-sea interface and thus has large impacts on the simulation or forecast of the upper ocean state associated with sea surface winds such as storm surges. Generally, Cd is a function of wind speed. However, the exact relationship between Cd and wind speed is still in dispute, and the widely-used formula that is a linear function of wind speed in an ocean model could lead to large bias at high wind speed. Here we establish a parabolic model of Cd based on storm surge observations and simulation in the South China Sea (SCS) through a number of tropical cyclone cases. Simulation of storm surges for independent Tropical cyclones (TCs) cases indicates that the new parabolic model of Cd outperforms traditional linear models. PMID:26499262

A parabolic model of drag coefficient for storm surge simulation in the South China Sea.

PubMed

Peng, Shiqiu; Li, Yineng

2015-10-26

Drag coefficient (Cd) is an essential metric in the calculation of momentum exchange over the air-sea interface and thus has large impacts on the simulation or forecast of the upper ocean state associated with sea surface winds such as storm surges. Generally, Cd is a function of wind speed. However, the exact relationship between Cd and wind speed is still in dispute, and the widely-used formula that is a linear function of wind speed in an ocean model could lead to large bias at high wind speed. Here we establish a parabolic model of Cd based on storm surge observations and simulation in the South China Sea (SCS) through a number of tropical cyclone cases. Simulation of storm surges for independent Tropical cyclones (TCs) cases indicates that the new parabolic model of Cd outperforms traditional linear models.

A parabolic model of drag coefficient for storm surge simulation in the South China Sea

NASA Astrophysics Data System (ADS)

Peng, Shiqiu; Li, Yineng

2015-10-01

Drag coefficient (Cd) is an essential metric in the calculation of momentum exchange over the air-sea interface and thus has large impacts on the simulation or forecast of the upper ocean state associated with sea surface winds such as storm surges. Generally, Cd is a function of wind speed. However, the exact relationship between Cd and wind speed is still in dispute, and the widely-used formula that is a linear function of wind speed in an ocean model could lead to large bias at high wind speed. Here we establish a parabolic model of Cd based on storm surge observations and simulation in the South China Sea (SCS) through a number of tropical cyclone cases. Simulation of storm surges for independent Tropical cyclones (TCs) cases indicates that the new parabolic model of Cd outperforms traditional linear models.

The influence of ACE ID and ACTN3 R577X polymorphisms on lower-extremity function in older women in response to high-speed power training

PubMed Central

2013-01-01

Background We studied the influence of the ACE I/D and ACTN3 R577X polymorphisms (single or combined) on lower-extremity function in older women in response to high-speed power training. Methods One hundred and thirty-nine healthy older Caucasian women participated in this study (age: 65.5 ± 8.2 years, body mass: 67.0 ± 10.0 kg and height: 1.57 ± 0.06 m). Walking speed (S10) performance and functional capacity assessed by the “get-up and go” (GUG) mobility test were measured at baseline (T1) and after a consecutive 12-week period of high-speed power training (40-75% of one repetition maximum in arm and leg extensor exercises; 3 sets 4–12 reps, and two power exercises for upper and lower extremity). Genomic DNA was extracted from blood samples, and genotyping analyses were performed by PCR methods. Genotype distributions between groups were compared by Chi-Square test and the gains in physical performance were analyzed by two-way, repeated-measures ANOVA. Results There were no significant differences between genotype groups in men or women for adjusted baseline phenotypes (P > 0.05). ACE I/D and ACTN3 polymorphisms showed a significant interaction genotype-training only in S10 (P = 0.012 and P = 0.044, respectively) and not in the GUG test (P = 0.311 and P = 0.477, respectively). Analyses of the combined effects between genotypes showed no other significant differences in all phenotypes (P < 0.05) at baseline. However, in response to high-speed power training, a significant interaction on walking speed (P = 0.048) was observed between the “power” (ACTN3 RR + RX & ACE DD) versus “non-power” muscularity-oriented genotypes (ACTN3 XX & ACE II + ID)]. Conclusions Thus, ACE I/D and ACTN3 R577X polymorphisms are likely candidates in the modulation of exercise-related gait speed phenotype in older women but not a significant influence in mobility traits. PMID:24313907

Field-based high-speed imaging of explosive eruptions

NASA Astrophysics Data System (ADS)

Taddeucci, J.; Scarlato, P.; Freda, C.; Moroni, M.

2012-12-01

Explosive eruptions involve, by definition, physical processes that are highly dynamic over short time scales. Capturing and parameterizing such processes is a major task in eruption understanding and forecasting, and a task that necessarily requires observational systems capable of high sampling rates. Seismic and acoustic networks are a prime tool for high-frequency observation of eruption, recently joined by Doppler radar and electric sensors. In comparison with the above monitoring systems, imaging techniques provide more complete and direct information of surface processes, but usually at a lower sampling rate. However, recent developments in high-speed imaging systems now allow such information to be obtained with a spatial and temporal resolution suitable for the analysis of several key eruption processes. Our most recent set up for high-speed imaging of explosive eruptions (FAMoUS - FAst, MUltiparametric Set-up,) includes: 1) a monochrome high speed camera, capable of 500 frames per second (fps) at high-definition (1280x1024 pixel) resolution and up to 200000 fps at reduced resolution; 2) a thermal camera capable of 50-200 fps at 480-120x640 pixel resolution; and 3) two acoustic to infrasonic sensors. All instruments are time-synchronized via a data logging system, a hand- or software-operated trigger, and via GPS, allowing signals from other instruments or networks to be directly recorded by the same logging unit or to be readily synchronized for comparison. FAMoUS weights less than 20 kg, easily fits into four, hand-luggage-sized backpacks, and can be deployed in less than 20' (and removed in less than 2', if needed). So far, explosive eruptions have been recorded in high-speed at several active volcanoes, including Fuego and Santiaguito (Guatemala), Stromboli (Italy), Yasur (Vanuatu), and Eyjafiallajokull (Iceland). Image processing and analysis from these eruptions helped illuminate several eruptive processes, including: 1) Pyroclasts ejection. High-speed videos reveal multiple, discrete ejection pulses within a single Strombolian explosion, with ejection velocities twice as high as previously recorded. Video-derived information on ejection velocity and ejecta mass can be combined with analytical and experimental models to constrain the physical parameters of the gas driving individual pulses. 2) Jet development. The ejection trajectory of pyroclasts can also be used to outline the spatial and temporal development of the eruptive jet and the dynamics of gas-pyroclast coupling within the jet, while high-speed thermal images add information on the temperature evolution in the jet itself as a function of the pyroclast size and content. 2) Pyroclasts settling. High-speed videos can be used to investigate the aerodynamic settling behavior of pyroclasts from bomb to ash in size and including ash aggregates, providing key parameters such as drag coefficient as a function of Re, and particle density. 3) The generation and propagation of acoustic and shock waves. Phase condensation in volcanic and atmospheric aerosol is triggered by the transit of pressure waves and can be recorded in high-speed videos, allowing the speed and wavelength of the waves to be measured and compared with the corresponding infrasonic signals and theoretical predictions.

Low-level inorganic arsenic exposure and neuropsychological functioning in American Indian elders.

PubMed

Carroll, Clint R; Noonan, Carolyn; Garroutte, Eva M; Navas-Acien, Ana; Verney, Steven P; Buchwald, Dedra

2017-07-01

Inorganic arsenic at high and prolonged doses is highly neurotoxic. Few studies have evaluated whether long-term, low-level arsenic exposure is associated with neuropsychological functioning in adults. To investigate the association between long-term, low-level inorganic arsenic exposure and neuropsychological functioning among American Indians aged 64-95. We assessed 928 participants in the Strong Heart Study by using data on arsenic species in urine samples collected at baseline (1989-1991) and results of standardized tests of global cognition, executive functioning, verbal learning and memory, fine motor functioning, and speed of mental processing administered during comprehensive follow-up evaluations in 2009-2013. We calculated the difference in neuropsychological functioning for a 10% increase in urinary arsenic with adjustment for sex, age, education, and study site. The sum of inorganic and methylated arsenic species (∑As) in urine was associated with limited fine motor functioning and processing speed. A 10% increase in ∑As was associated with a .10 (95% CI -.20, -.01) decrease on the Finger Tapping Test for the dominant hand and a .13 decrease (95% CI -.21, -.04) for the non-dominant hand. Similarly, a 10% increase in ∑As was associated with a .15 (95% CI -.29, .00) decrease on the Wechsler Adult Intelligence Scale-Fourth Edition Coding Subtest. ∑As was not associated with other neuropsychological functions. Findings indicate an adverse association between increased urinary arsenic fine motor functioning and processing speed, but not with other neuropsychological functioning, among elderly American Indians. Copyright © 2017 Elsevier Inc. All rights reserved.

Self-calibrated correlation imaging with k-space variant correlation functions.

PubMed

Li, Yu; Edalati, Masoud; Du, Xingfu; Wang, Hui; Cao, Jie J

2018-03-01

Correlation imaging is a previously developed high-speed MRI framework that converts parallel imaging reconstruction into the estimate of correlation functions. The presented work aims to demonstrate this framework can provide a speed gain over parallel imaging by estimating k-space variant correlation functions. Because of Fourier encoding with gradients, outer k-space data contain higher spatial-frequency image components arising primarily from tissue boundaries. As a result of tissue-boundary sparsity in the human anatomy, neighboring k-space data correlation varies from the central to the outer k-space. By estimating k-space variant correlation functions with an iterative self-calibration method, correlation imaging can benefit from neighboring k-space data correlation associated with both coil sensitivity encoding and tissue-boundary sparsity, thereby providing a speed gain over parallel imaging that relies only on coil sensitivity encoding. This new approach is investigated in brain imaging and free-breathing neonatal cardiac imaging. Correlation imaging performs better than existing parallel imaging techniques in simulated brain imaging acceleration experiments. The higher speed enables real-time data acquisition for neonatal cardiac imaging in which physiological motion is fast and non-periodic. With k-space variant correlation functions, correlation imaging gives a higher speed than parallel imaging and offers the potential to image physiological motion in real-time. Magn Reson Med 79:1483-1494, 2018. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

Embodied linearity of speed control in Drosophila melanogaster.

PubMed

Medici, V; Fry, S N

2012-12-07

Fruitflies regulate flight speed by adjusting their body angle. To understand how low-level posture control serves an overall linear visual speed control strategy, we visually induced free-flight acceleration responses in a wind tunnel and measured the body kinematics using high-speed videography. Subsequently, we reverse engineered the transfer function mapping body pitch angle onto flight speed. A linear model is able to reproduce the behavioural data with good accuracy. Our results show that linearity in speed control is realized already at the level of body posture-mediated speed control and is therefore embodied at the level of the complex aerodynamic mechanisms of body and wings. Together with previous results, this study reveals the existence of a linear hierarchical control strategy, which can provide relevant control principles for biomimetic implementations, such as autonomous flying micro air vehicles.

Embodied linearity of speed control in Drosophila melanogaster

PubMed Central

Medici, V.; Fry, S. N.

2012-01-01

Fruitflies regulate flight speed by adjusting their body angle. To understand how low-level posture control serves an overall linear visual speed control strategy, we visually induced free-flight acceleration responses in a wind tunnel and measured the body kinematics using high-speed videography. Subsequently, we reverse engineered the transfer function mapping body pitch angle onto flight speed. A linear model is able to reproduce the behavioural data with good accuracy. Our results show that linearity in speed control is realized already at the level of body posture-mediated speed control and is therefore embodied at the level of the complex aerodynamic mechanisms of body and wings. Together with previous results, this study reveals the existence of a linear hierarchical control strategy, which can provide relevant control principles for biomimetic implementations, such as autonomous flying micro air vehicles. PMID:22933185

Effectiveness of functional electrical stimulation on walking speed, functional walking category, and clinically meaningful changes for people with multiple sclerosis.

PubMed

Street, Tamsyn; Taylor, Paul; Swain, Ian

2015-04-01

To determine the effectiveness of functional electrical stimulation (FES) on drop foot in patients with multiple sclerosis (MS), using data from standard clinical practice. Case series with a consecutive sample of FES users collected between 2008 and 2013. Specialist FES center at a district general hospital. Patients with MS who have drop foot (N=187) (117 women, 70 men; mean age, 55y [range, 27-80y]; mean duration since diagnosis, 11.7y [range, 1-56y]). A total of 166 patients were still using FES after 20 weeks, with 153 patients completing the follow-up measures. FES of the common peroneal nerve (178 unilateral, 9 bilateral FES users). Clinically meaningful changes (ie, >.05m/s and >0.1m/s) and functional walking category derived from 10-m walking speed. An increase in walking speed was found to be highly significant (P<.001), both initially where a minimum clinically meaningful change was observed (.07m/s) and after 20 weeks with a substantial clinically meaningful change (.11m/s). After 20 weeks, treatment responders displayed a 27% average improvement in their walking speed. No significant training effect was found. Overall functional walking category was maintained or improved in 95% of treatment responders. FES of the dorsiflexors is a well-accepted intervention that enables clinically meaningful changes in walking speed, leading to a preserved or an increased functional walking category. Copyright © 2015 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

A Reconfigurable Real-Time Compressive-Sampling Camera for Biological Applications

PubMed Central

Fu, Bo; Pitter, Mark C.; Russell, Noah A.

2011-01-01

Many applications in biology, such as long-term functional imaging of neural and cardiac systems, require continuous high-speed imaging. This is typically not possible, however, using commercially available systems. The frame rate and the recording time of high-speed cameras are limited by the digitization rate and the capacity of on-camera memory. Further restrictions are often imposed by the limited bandwidth of the data link to the host computer. Even if the system bandwidth is not a limiting factor, continuous high-speed acquisition results in very large volumes of data that are difficult to handle, particularly when real-time analysis is required. In response to this issue many cameras allow a predetermined, rectangular region of interest (ROI) to be sampled, however this approach lacks flexibility and is blind to the image region outside of the ROI. We have addressed this problem by building a camera system using a randomly-addressable CMOS sensor. The camera has a low bandwidth, but is able to capture continuous high-speed images of an arbitrarily defined ROI, using most of the available bandwidth, while simultaneously acquiring low-speed, full frame images using the remaining bandwidth. In addition, the camera is able to use the full-frame information to recalculate the positions of targets and update the high-speed ROIs without interrupting acquisition. In this way the camera is capable of imaging moving targets at high-speed while simultaneously imaging the whole frame at a lower speed. We have used this camera system to monitor the heartbeat and blood cell flow of a water flea (Daphnia) at frame rates in excess of 1500 fps. PMID:22028852

Large-Scale Advanced Prop-Fan (LAP) pitch change actuator and control design report

NASA Technical Reports Server (NTRS)

Schwartz, R. A.; Carvalho, P.; Cutler, M. J.

1986-01-01

In recent years, considerable attention has been directed toward improving aircraft fuel consumption. Studies have shown that the high inherent efficiency previously demonstrated by low speed turboprop propulsion systems may now be extended to today's higher speed aircraft if advanced high-speed propeller blades having thin airfoils and aerodynamic sweep are utilized. Hamilton Standard has designed a 9-foot diameter single-rotation Large-Scale Advanced Prop-Fan (LAP) which will be tested on a static test stand, in a high speed wind tunnel and on a research aircraft. The major objective of this testing is to establish the structural integrity of large-scale Prop-Fans of advanced construction in addition to the evaluation of aerodynamic performance and aeroacoustic design. This report describes the operation, design features and actual hardware of the (LAP) Prop-Fan pitch control system. The pitch control system which controls blade angle and propeller speed consists of two separate assemblies. The first is the control unit which provides the hydraulic supply, speed governing and feather function for the system. The second unit is the hydro-mechanical pitch change actuator which directly changes blade angle (pitch) as scheduled by the control.

High speed turbogenerator for power recovery from fluid flow within conduit

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

Irvine, M. D.

1985-11-26

A high speed turbogenerator functionally combining, in one machine, an electrical generator and an expansion turbine. The electrical generator itself has a shaft supported on two bearings and the expansion turbine comprises an expander wheel overhung on the generator shaft and which rotates as a high pressure gas is let down in the expansion turbine to a lower pressure at a minimum predetermined flow rate and pressure drop. The shaft operates at speeds of about 6,000 rpm to 32,000 rpm, preferably at the higher end of such range, i.e. 20,000 to 24,000 rpm. The unit is sufficiently compact that amore » new use for the electrical generator is to modify the same such that the entire high speed turbogenerator is contained within the conduit carrying the gas to be let down in pressure and only electrical wires need be led through the conduit. The integrity of the conduit is thus retained to the extent possible and only a high pressure cable fitting extends through the conduit. In the preferred embodiment, the high speed turbogenerator is entirely fitted within a natural gas conduit in a gas distribution station, thereby achieving the pressure letdown and also obtaining useful electrical power.« less

Is there really an eccentric action of the hamstrings during the swing phase of high-speed running? Part II: Implications for exercise.

PubMed

Van Hooren, Bas; Bosch, Frans

2017-12-01

We have previously argued that there may actually be no significant eccentric, but rather predominantly an isometric action of the hamstring muscle fibres during the swing phase of high-speed running when the attachment points of the hamstrings are moving apart. Based on this we suggested that isometric rather than eccentric exercises are a more specific way of conditioning the hamstrings for high-speed running. In this review we argue that some of the presumed beneficial adaptations following eccentric training may actually not be related to the eccentric muscle fibre action, but to other factors such as exercise intensity. Furthermore, we discuss several disadvantages associated with commonly used eccentric hamstring exercises. Subsequently, we argue that high-intensity isometric exercises in which the series elastic element stretches and recoils may be equally or even more effective at conditioning the hamstrings for high-speed running, since they also avoid some of the negative side effects associated with eccentric training. We provide several criteria that exercises should fulfil to effectively condition the hamstrings for high-speed running. Adherence to these criteria will guarantee specificity with regards to hamstrings functioning during running. Practical examples of isometric exercises that likely meet several criteria are provided.

PCIE interface design for high-speed image storage system based on SSD

NASA Astrophysics Data System (ADS)

Wang, Shiming

2015-02-01

This paper proposes and implements a standard interface of miniaturized high-speed image storage system, which combines PowerPC with FPGA and utilizes PCIE bus as the high speed switching channel. Attached to the PowerPC, mSATA interface SSD(Solid State Drive) realizes RAID3 array storage. At the same time, a high-speed real-time image compression patent IP core also can be embedded in FPGA, which is in the leading domestic level with compression rate and image quality, making that the system can record higher image data rate or achieve longer recording time. The notebook memory card buckle type design is used in the mSATA interface SSD, which make it possible to complete the replacement in 5 seconds just using single hand, thus the total length of repeated recordings is increased. MSI (Message Signaled Interrupts) interruption guarantees the stability and reliability of continuous DMA transmission. Furthermore, only through the gigabit network, the remote display, control and upload to backup function can be realized. According to an optional 25 frame/s or 30 frame/s, upload speeds can be up to more than 84 MB/s. Compared with the existing FLASH array high-speed memory systems, it has higher degree of modularity, better stability and higher efficiency on development, maintenance and upgrading. Its data access rate is up to 300MB/s, realizing the high speed image storage system miniaturization, standardization and modularization, thus it is fit for image acquisition, storage and real-time transmission to server on mobile equipment.

Physical Function, Hyperuricemia, and Gout in Older Adults.

PubMed

Burke, Bridget Teevan; Köttgen, Anna; Law, Andrew; Windham, Beverly Gwen; Segev, Dorry; Baer, Alan N; Coresh, Josef; McAdams-DeMarco, Mara A

2015-12-01

Gout prevalence is high in older adults and those affected are at risk of physical disability, yet it is unclear whether they have worse physical function. We studied gout, hyperuricemia, and physical function in 5,819 older adults (age ≥65 years) attending the 2011-2013 Atherosclerosis Risk in Communities Study visit, a prospective US population-based cohort. Differences in lower extremity function (Short Physical Performance Battery [SPPB] and 4-meter walking speed) and upper extremity function (grip strength) by gout status and by hyperuricemia prevalence were estimated in adjusted ordinal logistic regression (SPPB) and linear regression (walking speed and grip strength) models. Lower scores or times signify worse function. The prevalence of poor physical performance (first quartile) by gout and hyperuricemia was estimated using adjusted modified Poisson regression. Ten percent of participants reported a history of gout and 21% had hyperuricemia. There was no difference in grip strength by history of gout (P = 0.77). Participants with gout performed worse on the SPPB test; they had 0.77 times (95% confidence interval [95% CI] 0.65, 0.90, P = 0.001) the prevalence odds of a 1-unit increase in SPPB score and were 1.18 times (95% CI 1.07, 1.32, P = 0.002) more likely to have poor SPPB performance. Participants with a history of gout had slower walking speed (mean difference -0.03; 95% CI -0.05, -0.01, P < 0.001) and were 1.19 times (95% CI 1.06, 1.34, P = 0.003) more likely to have poor walking speed. Similarly, SPPB score and walking speed, but not grip strength, were worse in participants with hyperuricemia. Older adults with gout and hyperuricemia are more likely to have worse lower extremity, but not upper extremity, function. © 2015, American College of Rheumatology.

Low Temperature Performance of High-Speed Neural Network Circuits

NASA Technical Reports Server (NTRS)

Duong, T.; Tran, M.; Daud, T.; Thakoor, A.

1995-01-01

Artificial neural networks, derived from their biological counterparts, offer a new and enabling computing paradigm specially suitable for such tasks as image and signal processing with feature classification/object recognition, global optimization, and adaptive control. When implemented in fully parallel electronic hardware, it offers orders of magnitude speed advantage. Basic building blocks of the new architecture are the processing elements called neurons implemented as nonlinear operational amplifiers with sigmoidal transfer function, interconnected through weighted connections called synapses implemented using circuitry for weight storage and multiply functions either in an analog, digital, or hybrid scheme.

Temperature Prediction in High Speed Bone Grinding using Motor PWM Signal

PubMed Central

Tai, Bruce L.; Zhang, Lihui; Wang, Anthony C.; Sullivan, Stephen; Wang, Guangjun; Shih, Albert J.

2013-01-01

This research explores the feasibility of using motor electrical feedback to estimate temperature rise during a surgical bone grinding procedure. High-speed bone grinding is often used during skull base neurosurgery to remove cranial bone and approach skull base tumors through the nasal corridor. Grinding-induced heat could propagate and potentially injure surrounding nerves and arteries, and therefore, predicting the temperature in the grinding region would benefit neurosurgeons during the operation. High-speed electric motors are controlled by pulse-width-modulation (PWM) to alter the current input and thus maintain the rotational speed. Assuming full mechanical to thermal power conversion in the grinding process, PWM can be used as feedback for heat generation and temperature prediction. In this study, the conversion model was established from experiments under a variety of grinding conditions and an inverse heat transfer method to determine heat flux. Given a constant rotational speed, the heat conversion was represented by a linear function, and could predict temperature from the experimental data with less than 20% errors. Such results support the advance of this technology for practical application. PMID:23806419

Modeling corneal surfaces with rational functions for high-speed videokeratoscopy data compression.

PubMed

Schneider, Martin; Iskander, D Robert; Collins, Michael J

2009-02-01

High-speed videokeratoscopy is an emerging technique that enables study of the corneal surface and tear-film dynamics. Unlike its static predecessor, this new technique results in a very large amount of digital data for which storage needs become significant. We aimed to design a compression technique that would use mathematical functions to parsimoniously fit corneal surface data with a minimum number of coefficients. Since the Zernike polynomial functions that have been traditionally used for modeling corneal surfaces may not necessarily correctly represent given corneal surface data in terms of its optical performance, we introduced the concept of Zernike polynomial-based rational functions. Modeling optimality criteria were employed in terms of both the rms surface error as well as the point spread function cross-correlation. The parameters of approximations were estimated using a nonlinear least-squares procedure based on the Levenberg-Marquardt algorithm. A large number of retrospective videokeratoscopic measurements were used to evaluate the performance of the proposed rational-function-based modeling approach. The results indicate that the rational functions almost always outperform the traditional Zernike polynomial approximations with the same number of coefficients.

Label-free chemical imaging of live Euglena gracilis by high-speed SRS spectral microscopy (Conference Presentation)

NASA Astrophysics Data System (ADS)

Wakisaka, Yoshifumi; Suzuki, Yuta; Tokunaga, Kyoya; Hirose, Misa; Domon, Ryota; Akaho, Rina; Kuroshima, Mai; Tsumura, Norimichi; Shimobaba, Tomoyoshi; Iwata, Osamu; Suzuki, Kengo; Nakashima, Ayaka; Goda, Keisuke; Ozeki, Yasuyuki

2016-03-01

Microbes, especially microalgae, have recently been of great interest for developing novel biofuels, drugs, and biomaterials. Imaging-based screening of live cells can provide high selectivity and is attractive for efficient bio-production from microalgae. Although conventional cellular screening techniques use cell labeling, labeling of microbes is still under development and can interfere with their cellular functions. Furthermore, since live microbes move and change their shapes rapidly, a high-speed imaging technique is required to suppress motion artifacts. Stimulated Raman scattering (SRS) microscopy allows for label-free and high-speed spectral imaging, which helps us visualize chemical components inside biological cells and tissues. Here we demonstrate high-speed SRS imaging, with temporal resolution of 0.14 seconds, of intracellular distributions of lipid, polysaccharide, and chlorophyll concentrations in rapidly moving Euglena gracilis, a unicellular phytoflagellate. Furthermore, we show that our method allows us to analyze the amount of chemical components inside each living cell. Our results indicate that SRS imaging may be applied to label-free screening of living microbes based on chemical information.

Three-component access to pyrroles promoted by the CAN-silver nitrate system under high-speed vibration milling conditions: a generalization of the Hantzsch pyrrole synthesis.

PubMed

Estévez, Verónica; Villacampa, Mercedes; Menéndez, J Carlos

2013-01-21

A sequential multicomponent process involving the high-speed vibration milling of ketones with N-iodosuccinimide and p-toluenesulfonic acid, followed by addition of a mixture of primary amines, β-dicarbonyl compounds, cerium(IV) ammonium nitrate and silver nitrate afforded polysubstituted, functionalized pyrroles. This one-pot, solid-state process can be considered as the coupling of an α-iodoketone preparation with a general version of the classical Hantzsch pyrrole synthesis.

Effect of outboard vertical-fin position and orientation on the low-speed aerodynamic performance of highly swept wings. [supersonic cruise aircraft research

NASA Technical Reports Server (NTRS)

Johnson, V. S.; Coe, P. L., Jr.

1979-01-01

A theoretical study was conducted to determine the potential low-speed performance improvements which can be achieved by altering the position and orientation of the outboard vertical fins of low-aspect-ratio highly swept wings. Results show that the magnitude of the performance improvements is solely a function of the span-load distribution. Both the vertical-fin-chordwise position and toe angle provided effective means for adjusting the overall span-load distribution.

Solvent-free cross-dehydrogenative coupling reactions under high speed ball-milling conditions applied to the synthesis of functionalized tetrahydroisoquinolines.

PubMed

Su, Weike; Yu, Jingbo; Li, Zhenhua; Jiang, Zhijiang

2011-11-04

Solvent-free reaction using a high-speed ball milling technique has been first applied to cross-dehydrogenative coupling (CDC) reactions between tetrahydroisoquinolines and three types of pronucleophiles such as nitroalkanes, alkynes, and indoles. All coupling products were obtained in good yields at short reaction times (no more than 40 min). When alkynes and indoles were used as pronucleophile, the reactions can be catalyzed efficiently by recoverable copper balls without any additional metal catalyst.

Multi-functional micromotor: microfluidic fabrication and water treatment application.

PubMed

Chen, Anqi; Ge, Xue-Hui; Chen, Jian; Zhang, Liyuan; Xu, Jian-Hong

2017-12-05

Micromotors are important for a wide variety of applications. Here, we develop a microfluidic approach for one-step fabrication of a Janus self-propelled micromotor with multiple functions. By fine tuning the fabrication parameters and loading functional nanoparticles, our micromotor reaches a high speed and achieves an oriented function to promote the water purification efficiency and recycling process.

Optical frequency switching scheme for a high-speed broadband THz measurement system based on the photomixing technique.

PubMed

Song, Hajun; Hwang, Sejin; Song, Jong-In

2017-05-15

This study presents an optical frequency switching scheme for a high-speed broadband terahertz (THz) measurement system based on the photomixing technique. The proposed system can achieve high-speed broadband THz measurements using narrow optical frequency scanning of a tunable laser source combined with a wavelength-switchable laser source. In addition, this scheme can provide a larger output power of an individual THz signal compared with that of a multi-mode THz signal generated by multiple CW laser sources. A swept-source THz tomography system implemented with a two-channel wavelength-switchable laser source achieves a reduced time for acquisition of a point spread function and a higher depth resolution in the same amount of measurement time compared with a system with a single optical source.

Optimization design of wind turbine drive train based on Matlab genetic algorithm toolbox

NASA Astrophysics Data System (ADS)

Li, R. N.; Liu, X.; Liu, S. J.

2013-12-01

In order to ensure the high efficiency of the whole flexible drive train of the front-end speed adjusting wind turbine, the working principle of the main part of the drive train is analyzed. As critical parameters, rotating speed ratios of three planetary gear trains are selected as the research subject. The mathematical model of the torque converter speed ratio is established based on these three critical variable quantity, and the effect of key parameters on the efficiency of hydraulic mechanical transmission is analyzed. Based on the torque balance and the energy balance, refer to hydraulic mechanical transmission characteristics, the transmission efficiency expression of the whole drive train is established. The fitness function and constraint functions are established respectively based on the drive train transmission efficiency and the torque converter rotating speed ratio range. And the optimization calculation is carried out by using MATLAB genetic algorithm toolbox. The optimization method and results provide an optimization program for exact match of wind turbine rotor, gearbox, hydraulic mechanical transmission, hydraulic torque converter and synchronous generator, ensure that the drive train work with a high efficiency, and give a reference for the selection of the torque converter and hydraulic mechanical transmission.

High Speed and High Functional Inverter Power Supplies for Plasma Generation and Control, and their Performance

NASA Astrophysics Data System (ADS)

Uesugi, Yoshihiko; Razzak, Mohammad A.; Kondo, Kenji; Kikuchi, Yusuke; Takamura, Shuichi; Imai, Takahiro; Toyoda, Mitsuhiro

The Rapid development of high power and high speed semiconductor switching devices has led to their various applications in related plasma fields. Especially, a high speed inverter power supply can be used as an RF power source instead of conventional linear amplifiers and a power supply to control the magnetic field in a fusion plasma device. In this paper, RF thermal plasma production and plasma heating experiments are described emphasis placed on using a static induction transistor inverter at a frequency range between 200 kHz and 2.5 MHz as an RF power supply. Efficient thermal plasma production is achieved experimentally by using a flexible and easily operated high power semiconductor inverter power supply. Insulated gate bipolar transistor (IGBT) inverter power supplies driven by a high speed digital signal processor are applied as tokamak joule coil and vertical coil power supplies to control plasma current waveform and plasma equilibrium. Output characteristics, such as the arbitrary bipolar waveform generation of a pulse width modulation (PWM) inverter using digital signal processor (DSP) can be successfully applied to tokamak power supplies for flexible plasma current operation and fast position control of a small tokamak.

Domains of cognitive function in early old age: which ones are predicted by pre-retirement psychosocial work characteristics?

PubMed

Sabbath, Erika L; Andel, Ross; Zins, Marie; Goldberg, Marcel; Berr, Claudine

2016-10-01

Psychosocial work characteristics may predict cognitive functioning after retirement. However, little research has explored specific cognitive domains associated with psychosocial work environments. Our study tested whether exposure to job demands, job control and their combination during working life predicted post-retirement performance on eight cognitive tests. We used data from French GAZEL cohort members who had undergone post-retirement cognitive testing (n=2149). Psychosocial job characteristics were measured on average for 4 years before retirement using Karasek's Job Content Questionnaire (job demands, job control and demand-control combinations). We tested associations between these exposures and post-retirement performance on tests for executive function, visual-motor speed, psychomotor speed, verbal memory, and verbal fluency using ordinary least squares regression. Low job control during working life was negatively associated with executive function, psychomotor speed, phonemic fluency and semantic fluency after retirement (p's<0.05), even after adjustment for demographics, socioeconomic status, health and social behaviours and vascular risk factors. Both passive (low-demand, low-control) and high-strain (high-demand, low-control) jobs were associated with lower scores on phonemic and semantic fluency when compared to low-strain (low-demand, high-control) jobs. Low job control, in combination with both high and low-job demands, is associated with post-retirement deficits in some, but not all, cognitive domains. In addition to work stress, associations between passive work and subsequent cognitive function may implicate lack of cognitive engagement at work as a risk factor for future cognitive difficulties. 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/

High-throughput microscopy must re-invent the microscope rather than speed up its functions

PubMed Central

Oheim, M

2007-01-01

Knowledge gained from the revolutions in genomics and proteomics has helped to identify many of the key molecules involved in cellular signalling. Researchers, both in academia and in the pharmaceutical industry, now screen, at a sub-cellular level, where and when these proteins interact. Fluorescence imaging and molecular labelling combine to provide a powerful tool for real-time functional biochemistry with molecular resolution. However, they traditionally have been work-intensive, required trained personnel, and suffered from low through-put due to sample preparation, loading and handling. The need for speeding up microscopy is apparent from the tremendous complexity of cellular signalling pathways, the inherent biological variability, as well as the possibility that the same molecule plays different roles in different sub-cellular compartments. Research institutes and companies have teamed up to develop imaging cytometers of ever-increasing complexity. However, to truly go high-speed, sub-cellular imaging must free itself from the rigid framework of current microscopes. PMID:17603553

Study on typhoon characteristic based on bridge health monitoring system.

PubMed

Wang, Xu; Chen, Bin; Sun, Dezhang; Wu, Yinqiang

2014-01-01

Through the wind velocity and direction monitoring system installed on Jiubao Bridge of Qiantang River, Hangzhou city, Zhejiang province, China, a full range of wind velocity and direction data was collected during typhoon HAIKUI in 2012. Based on these data, it was found that, at higher observed elevation, turbulence intensity is lower, and the variation tendency of longitudinal and lateral turbulence intensities with mean wind speeds is basically the same. Gust factor goes higher with increasing mean wind speed, and the change rate obviously decreases as wind speed goes down and an inconspicuous increase occurs when wind speed is high. The change of peak factor is inconspicuous with increasing time and mean wind speed. The probability density function (PDF) of fluctuating wind speed follows Gaussian distribution. Turbulence integral scale increases with mean wind speed, and its PDF does not follow Gaussian distribution. The power spectrum of observation fluctuating velocity is in accordance with Von Karman spectrum.

Performance of large-bore tapered-roller bearings under combined radial and thrust load at shaft speeds to 15,000 rpm

NASA Technical Reports Server (NTRS)

Parker, R. J.; Signer, H. R.

1977-01-01

The performance of 120.65-mm bore tapered roller bearings was investigated at shaft speeds up to 15,000 rpm. Temperature distribution and bearing heat generation were determined as a function of shaft speed, radial and thrust loads, lubricant flow rate, and lubricant inlet temperature. Lubricant was supplied by either jets or by a combination of holes through the cone directly to the cone-rib contact and jets at the roller small-end side. Cone-rib lubrication significantly improved high-speed tapered-roller bearing performance, yielding lower cone-face temperatures and lower power loss and allowing lower lubricant flow rates for a given speed condition. Bearing temperatures increased with increased shaft speed and decreased with increased lubricant flow rate. Bearing power loss increased with increased shaft speed and increased lubricant flow rate.

Providing a parallel and distributed capability for JMASS using SPEEDES

NASA Astrophysics Data System (ADS)

Valinski, Maria; Driscoll, Jonathan; McGraw, Robert M.; Meyer, Bob

2002-07-01

The Joint Modeling And Simulation System (JMASS) is a Tri-Service simulation environment that supports engineering and engagement-level simulations. As JMASS is expanded to support other Tri-Service domains, the current set of modeling services must be expanded for High Performance Computing (HPC) applications by adding support for advanced time-management algorithms, parallel and distributed topologies, and high speed communications. By providing support for these services, JMASS can better address modeling domains requiring parallel computationally intense calculations such clutter, vulnerability and lethality calculations, and underwater-based scenarios. A risk reduction effort implementing some HPC services for JMASS using the SPEEDES (Synchronous Parallel Environment for Emulation and Discrete Event Simulation) Simulation Framework has recently concluded. As an artifact of the JMASS-SPEEDES integration, not only can HPC functionality be brought to the JMASS program through SPEEDES, but an additional HLA-based capability can be demonstrated that further addresses interoperability issues. The JMASS-SPEEDES integration provided a means of adding HLA capability to preexisting JMASS scenarios through an implementation of the standard JMASS port communication mechanism that allows players to communicate.

Comparative atmosphere structure experiment

NASA Technical Reports Server (NTRS)

Sommer, S.

1974-01-01

Atmospheric structure of outer planets as determined by pressure, temperature, and accelerometers is reviewed and results obtained from the PAET earth entry are given. In order to describe atmospheric structure, entry is divided into two regimes, high and low speed. Acceleration is then measured: from these measurements density is determined as a function of time. The equations of motion are integrated to determine velocity, flight path angle, and altitude as a function of time. Density is then determined as a function of altitude from the previous determinations of density and altitude as a function of time. Hydrostatic equilibrium was assumed to determine pressure as a function of altitude. Finally the equation of space applied to determine temperature as a function of altitude, if the mean molecular weight is known. The mean molecular weight is obtained independently from either the low speed experiment or from the composition experiments.

Mobility stress test approach to predicting frailty, disability, and mortality in high-functioning older adults.

PubMed

Verghese, Joe; Holtzer, Roee; Lipton, Richard B; Wang, Cuiling

2012-10-01

To examine the validity of the Walking While Talking Test (WWT), a mobility stress test, to predict frailty, disability, and death in high-functioning older adults. Prospective cohort study. Community sample. Six hundred thirty-one community-residing adults aged 70 and older participating in the Einstein Aging Study (mean follow-up 32 months). High-functioning status at baseline was defined as absence of disability and dementia and normal walking speeds. Hazard ratios (HRs) for frailty, disability, and all-cause mortality. Frailty was defined as presence of three out of the following five attributes: weight loss, weakness, exhaustion, low physical activity, and slow gait. The predictive validity of the WWT was also compared with that of the Short Physical Performance Battery (SPPB) for study outcomes. Two hundred eighteen participants developed frailty, 88 developed disability, and 49 died. Each 10-cm/s decrease in WWT speed was associated with greater risk of frailty (HR = 1.12, 95% confidence interval (CI) = 1.06-1.18), disability (HR = 1.13, 95% CI = 1.03-1.23), and mortality (HR = 1.13, 95% CI = 1.01-1.27). Most associations remained robust even after accounting for potential confounders and gait speed. Comparisons of HRs and model fit suggest that the WWT may better predict frailty whereas SPPB may better predict disability. Mobility stress tests such as the WWT are robust predictors of risk of frailty, disability, and mortality in high-functioning older adults. © 2012, Copyright the Authors Journal compilation © 2012, The American Geriatrics Society.

Socioeconomic status, non-communicable disease risk factors, and walking speed in older adults: multi-cohort population based study

PubMed Central

Carmeli, Cristian; Jokela, Markus; Avendaño, Mauricio; McCrory, Cathal; d’Errico, Angelo; Bochud, Murielle; Barros, Henrique; Costa, Giuseppe; Chadeau-Hyam, Marc; Delpierre, Cyrille; Gandini, Martina; Fraga, Silvia; Goldberg, Marcel; Giles, Graham G; Lassale, Camille; Kenny, Rose Anne; Kelly-Irving, Michelle; Paccaud, Fred; Layte, Richard; Muennig, Peter; Marmot, Michael G; Ribeiro, Ana Isabel; Severi, Gianluca; Steptoe, Andrew; Shipley, Martin J; Zins, Marie; Mackenbach, Johan P; Vineis, Paolo; Kivimäki, Mika

2018-01-01

Abstract Objective To assess the association of low socioeconomic status and risk factors for non-communicable diseases (diabetes, high alcohol intake, high blood pressure, obesity, physical inactivity, smoking) with loss of physical functioning at older ages. Design Multi-cohort population based study. Setting 37 cohort studies from 24 countries in Europe, the United States, Latin America, Africa, and Asia, 1990-2017. Participants 109 107 men and women aged 45-90 years. Main outcome measure Physical functioning assessed using the walking speed test, a valid index of overall functional capacity. Years of functioning lost was computed as a metric to quantify the difference in walking speed between those exposed and unexposed to low socioeconomic status and risk factors. Results According to mixed model estimations, men aged 60 and of low socioeconomic status had the same walking speed as men aged 66.6 of high socioeconomic status (years of functioning lost 6.6 years, 95% confidence interval 5.0 to 9.4). The years of functioning lost for women were 4.6 (3.6 to 6.2). In men and women, respectively, 5.7 (4.4 to 8.1) and 5.4 (4.3 to 7.3) years of functioning were lost by age 60 due to insufficient physical activity, 5.1 (3.9 to 7.0) and 7.5 (6.1 to 9.5) due to obesity, 2.3 (1.6 to 3.4) and 3.0 (2.3 to 4.0) due to hypertension, 5.6 (4.2 to 8.0) and 6.3 (4.9 to 8.4) due to diabetes, and 3.0 (2.2 to 4.3) and 0.7 (0.1 to 1.5) due to tobacco use. In analyses restricted to high income countries, the number of years of functioning lost attributable to low socioeconomic status by age 60 was 8.0 (5.7 to 13.1) for men and 5.4 (4.0 to 8.0) for women, whereas in low and middle income countries it was 2.6 (0.2 to 6.8) for men and 2.7 (1.0 to 5.5) for women. Within high income countries, the number of years of functioning lost attributable to low socioeconomic status by age 60 was greater in the United States than in Europe. Physical functioning continued to decline as a function of unfavourable risk factors between ages 60 and 85. Years of functioning lost were greater than years of life lost due to low socioeconomic status and non-communicable disease risk factors. Conclusions The independent association between socioeconomic status and physical functioning in old age is comparable in strength and consistency with those for established non-communicable disease risk factors. The results of this study suggest that tackling all these risk factors might substantially increase life years spent in good physical functioning. PMID:29572376

Modeling the High Speed Research Cycle 2B Longitudinal Aerodynamic Database Using Multivariate Orthogonal Functions

NASA Technical Reports Server (NTRS)

Morelli, E. A.; Proffitt, M. S.

1999-01-01

The data for longitudinal non-dimensional, aerodynamic coefficients in the High Speed Research Cycle 2B aerodynamic database were modeled using polynomial expressions identified with an orthogonal function modeling technique. The discrepancy between the tabular aerodynamic data and the polynomial models was tested and shown to be less than 15 percent for drag, lift, and pitching moment coefficients over the entire flight envelope. Most of this discrepancy was traced to smoothing local measurement noise and to the omission of mass case 5 data in the modeling process. A simulation check case showed that the polynomial models provided a compact and accurate representation of the nonlinear aerodynamic dependencies contained in the HSR Cycle 2B tabular aerodynamic database.

Re-designing a mechanism for higher speed: A case history from textile machinery

NASA Astrophysics Data System (ADS)

Douglas, S. S.; Rooney, G. T.

The generation of general mechanism design software which is the formulation of suitable objective functions is discussed. There is a consistent drive towards higher speeds in the development of industrial sewing machines. This led to experimental analyses of dynamic performance and to a search for improved design methods. The experimental work highlighted the need for smoothness of motion at high speed, component inertias, and frame structural stiffness. Smoothness is associated with transmission properties and harmonic analysis. These are added to other design requirements of synchronization, mechanism size, and function. Some of the mechanism trains in overedte sewing machines are shown. All these trains are designed by digital optimization. The design software combines analysis of the sewing machine mechanisms, formulation of objectives innumerical terms, and suitable mathematical optimization ttechniques.

Processors for wavelet analysis and synthesis: NIFS and TI-C80 MVP

NASA Astrophysics Data System (ADS)

Brooks, Geoffrey W.

1996-03-01

Two processors are considered for image quadrature mirror filtering (QMF). The neuromorphic infrared focal-plane sensor (NIFS) is an existing prototype analog processor offering high speed spatio-temporal Gaussian filtering, which could be used for the QMF low- pass function, and difference of Gaussian filtering, which could be used for the QMF high- pass function. Although not designed specifically for wavelet analysis, the biologically- inspired system accomplishes the most computationally intensive part of QMF processing. The Texas Instruments (TI) TMS320C80 Multimedia Video Processor (MVP) is a 32-bit RISC master processor with four advanced digital signal processors (DSPs) on a single chip. Algorithm partitioning, memory management and other issues are considered for optimal performance. This paper presents these considerations with simulated results leading to processor implementation of high-speed QMF analysis and synthesis.

Free Thyroxine and Functional Mobility, Fitness, and Fatigue in Euthyroid Older Men and Women in the Baltimore Longitudinal Study of Aging.

PubMed

Simonsick, Eleanor M; Chia, Chee W; Mammen, Jennifer S; Egan, Josephine M; Ferrucci, Luigi

2016-07-01

Emerging evidence suggests that mildly down-regulated thyroid function in older persons may protect and/or reflect maintained health. Using observational data collected between January 2006 and March 2014 on a volunteer sample of 602 men and women aged 68-97 years with normal thyroid function participating in the Baltimore Longitudinal Study of Aging, this study examines the concurrent relationship between reported walking ability, usual and rapid gait speed, endurance walk performance, fatigability, and reported energy level with respect to free thyroxine (FT4) within the normal range (0.76-1.50ng/dL) as a continuous variable and categorized as low (lower quartile), medium (interquartile), or high (upper quartile). Adjusting for sex, age, race, height, weight, exercise and smoking, reported walking ability, usual and rapid gait speed, 400-m time, fatigability, and reported energy level were less favorable with increasing FT4 (p = .013 to <.001). In sex-strata, similar associations were observed except for walking ability in men and energy level in women. Categorical analyses revealed that persons with low FT4 exhibited better functional mobility, fitness, and reported energy than persons with intermediate or high levels (p < .05 for all). Persons with high-normal versus medium FT4 had slower usual and rapid gait speed (p < .05) only. Older adults with low-normal FT4 exhibit better mobility, fitness, and fatigue profiles. Mildly down-regulated thyroid function appears to align with better function in old age and may serve as a biomarker of healthy longevity. Published by Oxford University Press on behalf of the Gerontological Society of America 2016.

Relationship Between Head-Turn Gait Speed and Lateral Balance Function in Community-Dwelling Older Adults.

PubMed

Singh, Harshvardhan; Sanders, Ozell; McCombe Waller, Sandy; Bair, Woei-Nan; Beamer, Brock; Creath, Robert A; Rogers, Mark W

2017-10-01

To determine and compare gait speed during head-forward and side-to-side head-turn walking in individuals with lower versus greater lateral balance. Cross-sectional study. University research laboratory. Older adults (N=93; 42 men, 51 women; mean age ± SD, 73 ± 6.08y) who could walk independently. (1) Balance tolerance limit (BTL), defined as the lowest perturbation intensity where a multistep balance recovery pattern was first evoked in response to randomized lateral waist-pull perturbations of standing balance to the left and right sides, at 6 different intensities (range from level 2: 4.5-cm displacement at 180cm/s 2 acceleration, to level 7: 22.5-cm displacement at 900cm/s 2 acceleration); (2) gait speed, determined using an instrumented gait mat; (3) balance, evaluated with the Activities-specific Balance Confidence Scale; and (4) mobility, determined with the Timed Up and Go (TUG). Individuals with low versus high BTL had a slower self-selected head-forward gait speed and head-turn gait speed (P=.002 and P<.001, respectively); the magnitude of difference was greater in head-turn gait speed than head-forward gait speed (Cohen's d=1.0 vs 0.6). Head-turn gait speed best predicted BTL. BTL was moderately and positively related (P=.003) to the ABC Scale and negatively related (P=.017) to TUG. Head-turn gait speed is affected to a greater extent than head-forward gait speed in older individuals with poorer lateral balance and at greater risk of falls. Moreover, head-turn gait speed can be used to assess the interactions of limitations in lateral balance function and gait speed in relation to fall risk in older adults. Copyright © 2017 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

Motor and Tactile-Perceptual Skill Differences between Individuals with High-Functioning Autism and Typically Developing Individuals Ages 5-21

ERIC Educational Resources Information Center

Abu-Dahab, Sana M. N.; Skidmore, Elizabeth R.; Holm, Margo B.; Rogers, Joan C.; Minshew, Nancy J.

2013-01-01

We examined motor and tactile-perceptual skills in individuals with high-functioning autism (IHFA) and matched typically developing individuals (TDI) ages 5-21 years. Grip strength, motor speed and coordination were impaired in IHFA compared to matched TDI, and the differences between groups varied with age. Although tactile-perceptual skills of…

An Ultra-High Speed Whole Slide Image Viewing System

PubMed Central

Yagi, Yukako; Yoshioka, Shigeatsu; Kyusojin, Hiroshi; Onozato, Maristela; Mizutani, Yoichi; Osato, Kiyoshi; Yada, Hiroaki; Mark, Eugene J.; Frosch, Matthew P.; Louis, David N.

2012-01-01

Background: One of the goals for a Whole Slide Imaging (WSI) system is implementation in the clinical practice of pathology. One of the unresolved problems in accomplishing this goal is the speed of the entire process, i.e., from viewing the slides through making the final diagnosis. Most users are not satisfied with the correct viewing speeds of available systems. We have evaluated a new WSI viewing station and tool that focuses on speed. Method: A prototype WSI viewer based on PlayStation®3 with wireless controllers was evaluated at the Department of Pathology at MGH for the following reasons: 1. For the simulation of signing-out cases; 2. Enabling discussion at a consensus conference; and 3. Use at slide seminars during a Continuing Medical Education course. Results: Pathologists were being able to use the system comfortably after 0–15 min training. There were no complaints regarding speed. Most pathologists were satisfied with the functionality, usability and speed of the system. The most difficult situation was simulating diagnostic sign-out. Conclusion: The preliminary results of adapting the Sony PlayStation®3 (PS3®) as an ultra-high speed WSI viewing system were promising. The achieved speed is consistent with what would be needed to use WSI in daily practice. PMID:22063731

An ultra-high speed Whole Slide Image viewing system.

PubMed

Yagi, Yukako; Yoshioka, Shigeatsu; Kyusojin, Hiroshi; Onozato, Maristela; Mizutani, Yoichi; Osato, Kiyoshi; Yada, Hiroaki; Mark, Eugene J; Frosch, Matthew P; Louis, David N

2012-01-01

One of the goals for a Whole Slide Imaging (WSI) system is implementation in the clinical practice of pathology. One of the unresolved problems in accomplishing this goal is the speed of the entire process, i.e., from viewing the slides through making the final diagnosis. Most users are not satisfied with the correct viewing speeds of available systems. We have evaluated a new WSI viewing station and tool that focuses on speed. A prototype WSI viewer based on PlayStation®3 with wireless controllers was evaluated at the Department of Pathology at MGH for the following reasons: 1. For the simulation of signing-out cases; 2. Enabling discussion at a consensus conference; and 3. Use at slide seminars during a Continuing Medical Education course. Pathologists were being able to use the system comfortably after 0-15 min training. There were no complaints regarding speed. Most pathologists were satisfied with the functionality, usability and speed of the system. The most difficult situation was simulating diagnostic sign-out. The preliminary results of adapting the Sony PlayStation®3 (PS3®) as an ultra-high speed WSI viewing system were promising. The achieved speed is consistent with what would be needed to use WSI in daily practice.

An ultra-high speed whole slide image viewing system.

PubMed

Yagi, Yukako; Yoshioka, Shigeatsu; Kyusojin, Hiroshi; Onozato, Maristela; Mizutani, Yoichi; Osato, Kiyoshi; Yada, Hiroaki; Mark, Eugene J; Frosch, Matthew P; Louis, David N

2012-01-01

One of the goals for a Whole Slide Imaging (WSI) system is implementation in the clinical practice of pathology. One of the unresolved problems in accomplishing this goal is the speed of the entire process, i.e., from viewing the slides through making the final diagnosis. Most users are not satisfied with the correct viewing speeds of available systems. We have evaluated a new WSI viewing station and tool that focuses on speed. A prototype WSI viewer based on PlayStation®3 with wireless controllers was evaluated at the Department of Pathology at MGH for the following reasons: 1. For the simulation of signing-out cases; 2. Enabling discussion at a consensus conference; and 3. Use at slide seminars during a Continuing Medical Education course. Pathologists were being able to use the system comfortably after 0-15 min training. There were no complaints regarding speed. Most pathologists were satisfied with the functionality, usability and speed of the system. The most difficult situation was simulating diagnostic sign-out. The preliminary results of adapting the Sony PlayStation®3 (PS3®) as an ultra-high speed WSI viewing system were promising. The achieved speed is consistent with what would be needed to use WSI in daily practice.

Integration and test of high-speed transmitter electronics for free-space laser communications

NASA Technical Reports Server (NTRS)

Soni, Nitin J.; Lizanich, Paul J.

1994-01-01

The NASA Lewis Research Center in Cleveland, Ohio, has developed the electronics for a free-space, direct-detection laser communications system demonstration. Under the High-Speed Laser Integrated Terminal Electronics (Hi-LITE) Project, NASA Lewis has built a prototype full-duplex, dual-channel electronics transmitter and receiver operating at 325 megabit S per second (Mbps) per channel and using quaternary pulse-position modulation (QPPM). This paper describes the integration and testing of the transmitter portion for future application in free-space, direct-detection laser communications. A companion paper reviews the receiver portion of the prototype electronics. Minor modifications to the transmitter were made since the initial report on the entire system, and this paper addresses them. The digital electronics are implemented in gallium arsenide integrated circuits mounted on prototype boards. The fabrication and implementation issues related to these high-speed devices are discussed. The transmitter's test results are documented, and its functionality is verified by exercising all modes of operation. Various testing issues pertaining to high-speed circuits are addressed. A description of the transmitter electronics packaging concludes the paper.

A Novel Strategy for Numerical Simulation of High-speed Turbulent Reacting Flows

NASA Technical Reports Server (NTRS)

Sheikhi, M. R. H.; Drozda, T. G.; Givi, P.

2003-01-01

The objective of this research is to improve and implement the filtered mass density function (FDF) methodology for large eddy simulation (LES) of high-speed reacting turbulent flows. We have just completed Year 1 of this research. This is the Final Report on our activities during the period: January 1, 2003 to December 31, 2003. 2002. In the efforts during the past year, LES is conducted of the Sandia Flame D, which is a turbulent piloted nonpremixed methane jet flame. The subgrid scale (SGS) closure is based on the scalar filtered mass density function (SFMDF) methodology. The SFMDF is basically the mass weighted probability density function (PDF) of the SGS scalar quantities. For this flame (which exhibits little local extinction), a simple flamelet model is used to relate the instantaneous composition to the mixture fraction. The modelled SFMDF transport equation is solved by a hybrid finite-difference/Monte Carlo scheme.

Scalable maskless patterning of nanostructures using high-speed scanning probe arrays

NASA Astrophysics Data System (ADS)

Chen, Chen; Akella, Meghana; Du, Zhidong; Pan, Liang

2017-08-01

Nanoscale patterning is the key process to manufacture important products such as semiconductor microprocessors and data storage devices. Many studies have shown that it has the potential to revolutionize the functions of a broad range of products for a wide variety of applications in energy, healthcare, civil, defense and security. However, tools for mass production of these devices usually cost tens of million dollars each and are only affordable to the established semiconductor industry. A new method, nominally known as "pattern-on-the- y", that involves scanning an array of optical or electrical probes at high speed to form nanostructures and offers a new low-cost approach for nanoscale additive patterning. In this paper, we report some progress on using this method to pattern self-assembled monolayers (SAMs) on silicon substrate. We also functionalize the substrate with gold nanoparticle based on the SAM to show the feasibility of preparing amphiphilic and multi-functional surfaces.

Movement amplitude and tempo change in piano performance

NASA Astrophysics Data System (ADS)

Palmer, Caroline

2004-05-01

Music performance places stringent temporal and cognitive demands on individuals that should yield large speed/accuracy tradeoffs. Skilled piano performance, however, shows consistently high accuracy across a wide variety of rates. Movement amplitude may affect the speed/accuracy tradeoff, so that high accuracy can be obtained even at very fast tempi. The contribution of movement amplitude changes in rate (tempo) is investigated with motion capture. Cameras recorded pianists with passive markers on hands and fingers, who performed on an electronic (MIDI) keyboard. Pianists performed short melodies at faster and faster tempi until they made errors (altering the speed/accuracy function). Variability of finger movements in the three motion planes indicated most change in the plane perpendicular to the keyboard across tempi. Surprisingly, peak amplitudes of motion before striking the keys increased as tempo increased. Increased movement amplitudes at faster rates may reduce or compensate for speed/accuracy tradeoffs. [Work supported by Canada Research Chairs program, HIMH R01 45764.

Do Effort and Reward at Work Predict Changes in Cognitive Function? First Longitudinal Results from the Representative German Socio-Economic Panel.

PubMed

Riedel, Natalie; Siegrist, Johannes; Wege, Natalia; Loerbroks, Adrian; Angerer, Peter; Li, Jian

2017-11-15

It has been suggested that work characteristics, such as mental demands, job control, and occupational complexity, are prospectively related to cognitive function. However, current evidence on links between psychosocial working conditions and cognitive change over time is inconsistent. In this study, we applied the effort-reward imbalance model that allows to build on previous research on mental demands and to introduce reward-based learning as a principle with beneficial effect on cognitive function. We aimed to investigate whether high effort, high reward, and low over-commitment in 2006 were associated with positive changes in cognitive function in terms of perceptual speed and word fluency (2006-2012), and whether the co-manifestation of high effort and high reward would yield the strongest association. To this end, we used data on 1031 employees who participated in a large and representative study. Multivariate linear regression analyses supported our main hypotheses (separate and combined effects of effort and reward), particularly on changes in perceptual speed, whereas the effects of over-commitment did not reach the level of statistical significance. Our findings extend available knowledge by examining the course of cognitive function over time. If corroborated by further evidence, organization-based measures in the workplace can enrich efforts towards preventing cognitive decline in ageing workforces.

Improvement of automatic control systems of high-power turbines of PAO tubroatom for nuclear power plants

NASA Astrophysics Data System (ADS)

Shvetsov, V. L.; Babaev, I. N.

2017-09-01

The main technical solutions applied by PAO Turboatom used as the compensatory measures at the increase of the period of nonstop operation of nuclear power plants' (NPP) turbines with VVER-1000 type reactors up to 18 months are (1) replacing the standard hydraulic speed controller with an electronic one, (2) introduction of overclocking protection, (3) modernization of units of stop-control valves of high pressures, (4) installation of locking dampers on the receiver tubes of turbines of the first and second modification, and (5) improving the quality of repairs by reviewing the requirements for their implementation. The introduction of complex diagnostics of a control system on the basis of automatic treatment of results of registration of working parameters of the turbine is allocated as a separate prospective direction. Using an electronic controller of speed makes it possible to simplify the procedure of its inclusion in work at the failure of an electro-hydraulic system of control and vice versa. The regimes of maintaining the turbine rotor speed, steam pressure on the outlet of turbine, and the positions of main servomotors were introduced into the functions of the electronic controller. An electronic controller of speed includes its own electro-hydraulic transducer, turbine rotor speed sensor, and sensors of the position of main servomotors. Into the functions of electro- hydraulic control system and electronic speed controller, the function of overclocking protection, which determines the formation of commands for stopping the turbine at the exceeding of both the defined level of rotation speed and the defined combination of achieved rotation speed and angular acceleration of rotor, was introduced. To simplify the correction of forces acting on the control valve cups, the design of the cups was changed, and it has the profiled inserts. The solutions proposed were implemented on K-1100-60/1500-2M turbines of Rostov NPP. From the composition of control system of already made turbines, the devices of speed switching of moving of control flaps for opening and hydraulic damper in the servomotors of regulating flaps were excluded; the fists of the control valves providing the increased valve stroke for opening and the construction of filters for regulation, electro-hydraulic converters, oil draining device, etc. was changed.

Optimization of the High-speed On-off Valve of an Automatic Transmission

NASA Astrophysics Data System (ADS)

Li-mei, ZHAO; Huai-chao, WU; Lei, ZHAO; Yun-xiang, LONG; Guo-qiao, LI; Shi-hao, TANG

2018-03-01

The response time of the high-speed on-off solenoid valve has a great influence on the performance of the automatic transmission. In order to reduce the response time of the high-speed on-off valve, the simulation model of the valve was built by use of AMESim and Ansoft Maxwell softwares. To reduce the response time, an objective function based on ITAE criterion was built and the Genetic Algorithms was used to optimize five parameters including circle number, working air gap, et al. The comparison between experiment and simulation shows that the model is verified. After optimization, the response time of the valve is reduced by 38.16%, the valve can meet the demands of the automatic transmission well. The results can provide theoretical reference for the improvement of automatic transmission performance.

The high speed interconnect system architecture and operation

NASA Astrophysics Data System (ADS)

Anderson, Steven C.

The design and operation of a fiber-optic high-speed interconnect system (HSIS) being developed to meet the requirements of future avionics and flight-control hardware with distributed-system architectures are discussed. The HSIS is intended for 100-Mb/s operation of a local-area network with up to 256 stations. It comprises a bus transmission system (passive star couplers and linear media linked by active elements) and network interface units (NIUs). Each NIU is designed to perform the physical, data link, network, and transport functions defined by the ISO OSI Basic Reference Model (1982 and 1983) and incorporates a fiber-optic transceiver, a high-speed protocol based on the SAE AE-9B linear token-passing data bus (1986), and a specialized application interface unit. The operating modes and capabilities of HSIS are described in detail and illustrated with diagrams.

[Construction of DICOM-WWW gateway by open source, and application to PDAs using the high-speed mobile communications network].

PubMed

Yokohama, Noriya

2003-09-01

The author constructed a medical image network system using open source software that took security into consideration. This system was enabled for search and browse with a WWW browser, and images were stored in a DICOM server. In order to realize this function, software was developed to fill in the gap between the DICOM protocol and HTTP using PHP language. The transmission speed was evaluated by the difference in protocols between DICOM and HTTP. Furthermore, an attempt was made to evaluate the convenience of medical image access with a personal information terminal via the Internet through the high-speed mobile communication terminal. Results suggested the feasibility of remote diagnosis and application to emergency care.

High-speed schlieren imaging of rocket exhaust plumes

NASA Astrophysics Data System (ADS)

Coultas-McKenney, Caralyn; Winter, Kyle; Hargather, Michael

2016-11-01

Experiments are conducted to examine the exhaust of a variety of rocket engines. The rocket engines are mounted in a schlieren system to allow high-speed imaging of the engine exhaust during startup, steady state, and shutdown. A variety of rocket engines are explored including a research-scale liquid rocket engine, consumer/amateur solid rocket motors, and water bottle rockets. Comparisons of the exhaust characteristics, thrust and cost for this range of rockets is presented. The variety of nozzle designs, target functions, and propellant type provides unique variations in the schlieren imaging.

A functional video-based anthropometric measuring system

NASA Technical Reports Server (NTRS)

Nixon, J. H.; Cater, J. P.

1982-01-01

A high-speed anthropometric three dimensional measurement system using the Selcom Selspot motion tracking instrument for visual data acquisition is discussed. A three-dimensional scanning system was created which collects video, audio, and performance data on a single standard video cassette recorder. Recording rates of 1 megabit per second for periods of up to two hours are possible with the system design. A high-speed off-the-shelf motion analysis system for collecting optical information as used. The video recording adapter (VRA) is interfaced to the Selspot data acquisition system.

Nearly Interactive Parabolized Navier-Stokes Solver for High Speed Forebody and Inlet Flows

NASA Technical Reports Server (NTRS)

Benson, Thomas J.; Liou, May-Fun; Jones, William H.; Trefny, Charles J.

2009-01-01

A system of computer programs is being developed for the preliminary design of high speed inlets and forebodies. The system comprises four functions: geometry definition, flow grid generation, flow solver, and graphics post-processor. The system runs on a dedicated personal computer using the Windows operating system and is controlled by graphical user interfaces written in MATLAB (The Mathworks, Inc.). The flow solver uses the Parabolized Navier-Stokes equations to compute millions of mesh points in several minutes. Sample two-dimensional and three-dimensional calculations are demonstrated in the paper.

Imaging visible light with Medipix2.

PubMed

Mac Raighne, Aaron; Brownlee, Colin; Gebert, Ulrike; Maneuski, Dzmitry; Milnes, James; O'Shea, Val; Rügheimer, Tilman K

2010-11-01

A need exists for high-speed single-photon counting optical imaging detectors. Single-photon counting high-speed detection of x rays is possible by using Medipix2 with pixelated silicon photodiodes. In this article, we report on a device that exploits the Medipix2 chip for optical imaging. The fabricated device is capable of imaging at >3000 frames/s over a 256×256 pixel matrix. The imaging performance of the detector device via the modulation transfer function is measured, and the presence of ion feedback and its degradation of the imaging properties are discussed.

Impact of one HF-rTMS session on fine motor function in right-handed healthy female subjects: a comparison of stimulation over the left versus the right dorsolateral prefrontal cortex.

PubMed

Baeken, C; Schrijvers, D L; Sabbe, B G C; Vanderhasselt, M A; De Raedt, R

2012-01-01

Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive tool to investigate neural conduction in motor processes. Most rTMS research has been conducted by targeting the primary motor cortex. Several studies have also found increased psychomotor speed after rTMS of the dorsolateral prefrontal cortex (DLPFC). However, these studies were mainly performed in psychiatric patients, only targeting the left DLPFC, and often without sham control. Moreover, psychomotor speed is mostly measured based on tasks that also require higher executive functions. Here, we examined the lateralized effect of one sham-controlled high-frequency rTMS session applied to the left or right DLPFC on fine motor function in 36 healthy right-handed females, using the Fitts' paradigm. We found a significant improvement in psychomotor speed only after actively stimulating the right DLPFC. Our results support the assumption of a right prefrontal neural network implicated in visuomotor behavior and performance processes, and that the improvement in psychomotor speed is not a secondary effect of decreased mood. Copyright © 2012 S. Karger AG, Basel.

Effects of a progressive resistance exercise program with high-speed component on the physical function of older women with sarcopenic obesity: a randomized controlled trial.

PubMed

Vasconcelos, Karina S S; Dias, João M D; Araújo, Marília C; Pinheiro, Ana C; Moreira, Bruno S; Dias, Rosângela C

2016-07-11

Sarcopenic obesity is associated with disability in older people, especially in women. Resistance exercises are recommended for this population, but their efficacy is not clear. To evaluate the effects of a progressive resistance exercise program with high-speed component on the physical function of older women with sarcopenic obesity. Twenty-eight women 65 to 80 years old, with a body mass index ≥30kg/m2 and handgrip strength ≤21kg were randomly allocated to two groups. The experimental group underwent a 10-week resistance exercise program designed to improve strength, power, and endurance of lower-limb muscles, with open chain and closed chain exercises. The control group had their health status monitored through telephone calls. The primary outcomes were lower limb muscle performance measured by knee extensor strength, power and fatigue by isokinetic dynamometry, and mobility measured by the Short Physical Performance Battery and by gait velocity. The secondary outcome was health-related quality of life assessed by the SF-36 Questionnaire. The average rate of adherence was 85%, with few mild adverse effects. There were no significant between-group differences for any of the outcomes. In this study, a progressive resistance exercise program with high-speed component was not effective for improving the physical function of older women with sarcopenic obesity.

The response of a high-speed train wheel to a harmonic wheel-rail force

NASA Astrophysics Data System (ADS)

Sheng, Xiaozhen; Liu, Yuxia; Zhou, Xin

2016-09-01

The maximum speed of China's high-speed trains currently is 300km/h and expected to increase to 350-400km/h. As a wheel travels along the rail at such a high speed, it is subject to a force rotating at the same speed along its periphery. This fast moving force contains not only the axle load component, but also many components of high frequencies generated from wheel-rail interactions. Rotation of the wheel also introduces centrifugal and gyroscopic effects. How the wheel responds is fundamental to many issues, including wheel-rail contact, traction, wear and noise. In this paper, by making use of its axial symmetry, a special finite element scheme is developed for responses of a train wheel subject to a vertical and harmonic wheel-rail force. This FE scheme only requires a 2D mesh over a cross-section containing the wheel axis but includes all the effects induced by wheel rotation. Nodal displacements, as a periodic function of the cross-section angle 6, can be decomposed, using Fourier series, into a number of components at different circumferential orders. The derived FE equation is solved for each circumferential order. The sum of responses at all circumferential orders gives the actual response of the wheel.

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.

Temperature prediction in high speed bone grinding using motor PWM signal.

PubMed

Tai, Bruce L; Zhang, Lihui; Wang, Anthony C; Sullivan, Stephen; Wang, Guangjun; Shih, Albert J

2013-10-01

This research explores the feasibility of using motor electrical feedback to estimate temperature rise during a surgical bone grinding procedure. High-speed bone grinding is often used during skull base neurosurgery to remove cranial bone and approach skull base tumors through the nasal corridor. Grinding-induced heat could propagate and potentially injure surrounding nerves and arteries, and therefore, predicting the temperature in the grinding region would benefit neurosurgeons during the operation. High-speed electric motors are controlled by pulse-width-modulation (PWM) to alter the current input and thus maintain the rotational speed. Assuming full mechanical to thermal power conversion in the grinding process, PWM can be used as feedback for heat generation and temperature prediction. In this study, the conversion model was established from experiments under a variety of grinding conditions and an inverse heat transfer method to determine heat flux. Given a constant rotational speed, the heat conversion was represented by a linear function, and could predict temperature from the experimental data with less than 20% errors. Such results support the advance of this technology for practical application. Copyright © 2013 IPEM. Published by Elsevier Ltd. All rights reserved.

The Involvement of Speed-of-Processing in Story Listening in Preschool Children: A Functional and Structural Connectivity Study.

PubMed

Horowitz-Kraus, Tzipi; Farah, Rola; DiFrancesco, Mark; Vannest, Jennifer

2017-02-01

Story listening in children relies on brain regions supporting speech perception, auditory word recognition, syntax, semantics, and discourse abilities, along with the ability to attend and process information (part of executive functions). Speed-of-processing is an early-developed executive function. We used functional and structural magnetic resonance imaging (MRI) to demonstrate the relationship between story listening and speed-of-processing in preschool-age children. Eighteen participants performed story-listening tasks during MRI scans. Functional and structural connectivity analysis was performed using the speed-of-processing scores as regressors. Activation in the superior frontal gyrus during story listening positively correlated with speed-of-processing scores. This region was functionally connected with the superior temporal gyrus, insula, and hippocampus. Fractional anisotropy in the inferior frontooccipital fasciculus, which connects the superior frontal and temporal gyri, was positively correlated with speed-of-processing scores. Our results suggest that speed-of-processing skills in preschool-age children are reflected in functional activation and connectivity during story listening and may act as a biomarker for future academic abilities. Georg Thieme Verlag KG Stuttgart · New York.

A hardware-oriented algorithm for floating-point function generation

NASA Technical Reports Server (NTRS)

O'Grady, E. Pearse; Young, Baek-Kyu

1991-01-01

An algorithm is presented for performing accurate, high-speed, floating-point function generation for univariate functions defined at arbitrary breakpoints. Rapid identification of the breakpoint interval, which includes the input argument, is shown to be the key operation in the algorithm. A hardware implementation which makes extensive use of read/write memories is used to illustrate the algorithm.

Low-cost, high-speed back-end processing system for high-frequency ultrasound B-mode imaging.

PubMed

Chang, Jin Ho; Sun, Lei; Yen, Jesse T; Shung, K Kirk

2009-07-01

For real-time visualization of the mouse heart (6 to 13 beats per second), a back-end processing system involving high-speed signal processing functions to form and display images has been developed. This back-end system was designed with new signal processing algorithms to achieve a frame rate of more than 400 images per second. These algorithms were implemented in a simple and cost-effective manner with a single field-programmable gate array (FPGA) and software programs written in C++. The operating speed of the back-end system was investigated by recording the time required for transferring an image to a personal computer. Experimental results showed that the back-end system is capable of producing 433 images per second. To evaluate the imaging performance of the back-end system, a complete imaging system was built. This imaging system, which consisted of a recently reported high-speed mechanical sector scanner assembled with the back-end system, was tested by imaging a wire phantom, a pig eye (in vitro), and a mouse heart (in vivo). It was shown that this system is capable of providing high spatial resolution images with fast temporal resolution.

Low-Cost, High-Speed Back-End Processing System for High-Frequency Ultrasound B-Mode Imaging

PubMed Central

Chang, Jin Ho; Sun, Lei; Yen, Jesse T.; Shung, K. Kirk

2009-01-01

For real-time visualization of the mouse heart (6 to 13 beats per second), a back-end processing system involving high-speed signal processing functions to form and display images has been developed. This back-end system was designed with new signal processing algorithms to achieve a frame rate of more than 400 images per second. These algorithms were implemented in a simple and cost-effective manner with a single field-programmable gate array (FPGA) and software programs written in C++. The operating speed of the back-end system was investigated by recording the time required for transferring an image to a personal computer. Experimental results showed that the back-end system is capable of producing 433 images per second. To evaluate the imaging performance of the back-end system, a complete imaging system was built. This imaging system, which consisted of a recently reported high-speed mechanical sector scanner assembled with the back-end system, was tested by imaging a wire phantom, a pig eye (in vitro), and a mouse heart (in vivo). It was shown that this system is capable of providing high spatial resolution images with fast temporal resolution. PMID:19574160

A novel method of freeform surface grinding with a soft wheel based on industrial robots

NASA Astrophysics Data System (ADS)

Sha, Sheng-chun; Guo, Xiao-ling

2011-08-01

In order to meet the growing demand for high-quality images, optical elements of freeform surface are more and more applied to imaging system. However the fabrication of freeform surface optical elements is much more difficult than that of traditional spherical ones. Recent research on freeform surface manufacture often deals with precision machine tools which have limitations on dimensions and are always expensive. Little has been researched on industrial robots. In this paper, a new method of freeform surface grinding based on industrial robots was found. This method could be applied to both whole surface grinding as well as partial surface grinding. The diameter of lenses to be ground would not be restricted to the machine tool's size. In this method a high-speed-rotating soft wheel was used. The relation between removing amount and grinding time which could be called removing function was established and measured. The machining precision was achieved by means of controlling the grinding time instead of the machine tool or industrial robot itself. There are two main factors affecting the removing function: i).rotating speed of the soft wheel; ii).pressure between the wheel and the work piece. In this paper, two groups of experiments have been conducted. One is the removing function tested at constant rotating speed while under different pressure. The other is that tested under a certain pressure with variable speed. Tables and curves which can show the effect of speed and pressure on the removing efficiency have been obtained. Cause for inaccuracy between experiment data and calculated result according to the theory and the non-linearity in the curves was analyzed. Through these analyses the removing function could be concluded under certain condition including rotating speed and pressure. Finally several experiments were performed to verify the appropriateness of the removing function. It could also be concluded that this method was more efficient in comparison with traditional grinding technology particularly in the aspect of partial surface grinding. This paper also brought up a new idea that this method could be combined with other freeform surface grinding technics to realize a more flexible, efficient, reliable and economical type of optical fabrication. It would become a potential technic especially for partial optical surface grinding and repair.

A nonlinear model predictive control formulation for obstacle avoidance in high-speed autonomous ground vehicles in unstructured environments

NASA Astrophysics Data System (ADS)

Liu, Jiechao; Jayakumar, Paramsothy; Stein, Jeffrey L.; Ersal, Tulga

2018-06-01

This paper presents a nonlinear model predictive control (MPC) formulation for obstacle avoidance in high-speed, large-size autono-mous ground vehicles (AGVs) with high centre of gravity (CoG) that operate in unstructured environments, such as military vehicles. The term 'unstructured' in this context denotes that there are no lanes or traffic rules to follow. Existing MPC formulations for passenger vehicles in structured environments do not readily apply to this context. Thus, a new nonlinear MPC formulation is developed to navigate an AGV from its initial position to a target position at high-speed safely. First, a new cost function formulation is used that aims to find the shortest path to the target position, since no reference trajectory exists in unstructured environments. Second, a region partitioning approach is used in conjunction with a multi-phase optimal control formulation to accommodate the complicated forms the obstacle-free region can assume due to the presence of multiple obstacles in the prediction horizon in an unstructured environment. Third, the no-wheel-lift-off condition, which is the major dynamical safety concern for high-speed, high-CoG AGVs, is ensured by limiting the steering angle within a range obtained offline using a 14 degrees-of-freedom vehicle dynamics model. Thus, a safe, high-speed navigation is enabled in an unstructured environment. Simulations of an AGV approaching multiple obstacles are provided to demonstrate the effectiveness of the algorithm.

Monitoring and analysis of thermal deformation waves with a high-speed phase measurement system.

PubMed

Taylor, Lucas; Talghader, Joseph

2015-10-20

Thermal effects in optical substrates are vitally important in determining laser damage resistance in long-pulse and continuous-wave laser systems. Thermal deformation waves in a soda-lime-silica glass substrate have been measured using high-speed interferometry during a series of laser pulses incident on the surface. Two-dimensional images of the thermal waves were captured at a rate of up to six frames per thermal event using a quantitative phase measurement method. The system comprised a Mach-Zehnder interferometer, along with a high-speed camera capable of up to 20,000 frames-per-second. The sample was placed in the interferometer and irradiated with 100 ns, 2 kHz Q-switched pulses from a high-power Nd:YAG laser operating at 1064 nm. Phase measurements were converted to temperature using known values of thermal expansion and temperature-dependent refractive index for glass. The thermal decay at the center of the thermal wave was fit to a function derived from first principles with excellent agreement. Additionally, the spread of the thermal distribution over time was fit to the same function. Both the temporal decay fit and the spatial fit produced a thermal diffusivity of 5×10^-7  m²/s.

Tough Hydrogel Robots: High-Speed, High-Force and Opto-sonically Invisible in Water

NASA Astrophysics Data System (ADS)

Zhao, Xuanhe

Sea animals such as leptocephali develop tissues and organs composed of active transparent hydrogels to achieve agile motions and natural camouflage in water. Hydrogel-based actuators that can imitate the capabilities of leptocephali will enable new applications in diverse fields. However, existing hydrogel actuators, mostly osmotic-driven, are intrinsically low-speed and/or low-force; and their camouflage capabilities have not been explored. Here we show that hydraulic actuations of tough hydrogels with designed structures and properties can give soft actuators and robots that are high-speed, high-force, and optically and sonically camouflaged in water. We invent a simple method capable of assembling physically-crosslinked hydrogel parts followed by covalent crosslinking to fabricate large-scale hydraulic hydrogel actuators and robots with robust bodies and interfaces. The hydrogel actuators and robots can maintain their robustness and functionality over multiple cycles of actuations, owning to the anti-fatigue property of the hydrogel under moderate stresses. A multiscale theoretical framework has been developed to guide the design and optimization of the hydrogel robots. We further demonstrate that the agile and transparent hydrogel actuators and robots perform extraordinary functions including swimming, kicking rubber-balls and catching a live fish in water. The work was supported by NSF(No. CMMI- 1253495) and ONR (No. N00014-14-1-0528).

Propositions for the Analysis of Commutation Phenomena and Modeling of Universal Motors Using the State Function Method

NASA Astrophysics Data System (ADS)

Niwa, Yuta; Akiyama, Yuji; Naruta, Tomokazu

We carried out FEM simulations for modeling ultra-high-speed universal motors by using the state function method and analyzed the phenomenon of commutator sparking, the characteristics of the air gap surface, and the contact condition or contact resistance of the brushes and commutator bars. Thus, we could quantitatively analyze commutator sparking and investigate the configuration of the iron core. The results of FEM analysis were used to develop a model for predicting the configuration of the iron core and for estimating the electromotive force generated by the transformer, armature reaction field, spark voltage, contact resistance between the rotating brushes, and changes in the gap permeance. The results of our simulation were experimental results. This confirmed the validity of our analysis method. Thus, an ultra-high-speed, high-capacity of 1.5kw motor rotating at 30,000rpm can be designed for use in vacuum cleaners.

High-speed wavelength switching of tunable MEMS vertical cavity surface emitting laser by ringing suppression

NASA Astrophysics Data System (ADS)

Inoue, Shunya; Nishimura, Shun; Nakahama, Masanori; Matsutani, Akihiro; Sakaguchi, Takahiro; Koyama, Fumio

2018-04-01

For use in wavelength division multiplexing (WDM) with high-speed wavelength routing functions, the fast wavelength switching of tunable lasers is a key function. A tunable MEMS vertical cavity surface emitting laser (VCSEL) is a good candidate as a light source for this purpose. The cantilever in MEMS VCSELs has a high mechanical resonance frequency thanks to its small size, but the switching time is limited by the ringing of the cantilever structure. In this paper, we analyzed the mechanical behavior of a cantilever MEMS mirror and demonstrated ringing-free operation with an engineered voltage signal. The applied voltage waveform was optimized in a two-step format and we experimentally obtained ringing free wavelength switching. We measured the transient response of the wavelength by inserting a tunable filter, exhibiting the settling time of less than 2.5 µs, which corresponds to a half period of the cantilever resonance frequency.

Safety performance functions incorporating design consistency variables.

PubMed

Montella, Alfonso; Imbriani, Lella Liana

2015-01-01

Highway design which ensures that successive elements are coordinated in such a way as to produce harmonious and homogeneous driver performances along the road is considered consistent and safe. On the other hand, an alignment which requires drivers to handle high speed gradients and does not meet drivers' expectancy is considered inconsistent and produces higher crash frequency. To increase the usefulness and the reliability of existing safety performance functions and contribute to solve inconsistencies of existing highways as well as inconsistencies arising in the design phase, we developed safety performance functions for rural motorways that incorporate design consistency measures. Since the design consistency variables were used only for curves, two different sets of models were fitted for tangents and curves. Models for the following crash characteristics were fitted: total, single-vehicle run-off-the-road, other single vehicle, multi vehicle, daytime, nighttime, non-rainy weather, rainy weather, dry pavement, wet pavement, property damage only, slight injury, and severe injury (including fatal). The design consistency parameters in this study are based on operating speed models developed through an instrumented vehicle equipped with a GPS continuous speed tracking from a field experiment conducted on the same motorway where the safety performance functions were fitted (motorway A16 in Italy). Study results show that geometric design consistency has a significant effect on safety of rural motorways. Previous studies on the relationship between geometric design consistency and crash frequency focused on two-lane rural highways since these highways have the higher crash rates and are generally characterized by considerable inconsistencies. Our study clearly highlights that the achievement of proper geometric design consistency is a key design element also on motorways because of the safety consequences of design inconsistencies. The design consistency measures which are significant explanatory variables of the safety performance functions developed in this study are: (1) consistency in driving dynamics, i.e., difference between side friction assumed with respect to the design speed and side friction demanded at the 85th percentile speed; (2) operating speed consistency, i.e., absolute value of the 85th percentile speed reduction through successive elements of the road; (3) inertial speed consistency, i.e., difference between the operating speed in the curve and the average operating speed along the 5 km preceding the beginning of the curve; and (4) length of tangent preceding the curve (only for run-off-the-road crashes). Copyright © 2014 Elsevier Ltd. All rights reserved.

High-Speed and Scalable Whole-Brain Imaging in Rodents and Primates.

PubMed

Seiriki, Kaoru; Kasai, Atsushi; Hashimoto, Takeshi; Schulze, Wiebke; Niu, Misaki; Yamaguchi, Shun; Nakazawa, Takanobu; Inoue, Ken-Ichi; Uezono, Shiori; Takada, Masahiko; Naka, Yuichiro; Igarashi, Hisato; Tanuma, Masato; Waschek, James A; Ago, Yukio; Tanaka, Kenji F; Hayata-Takano, Atsuko; Nagayasu, Kazuki; Shintani, Norihito; Hashimoto, Ryota; Kunii, Yasuto; Hino, Mizuki; Matsumoto, Junya; Yabe, Hirooki; Nagai, Takeharu; Fujita, Katsumasa; Matsuda, Toshio; Takuma, Kazuhiro; Baba, Akemichi; Hashimoto, Hitoshi

2017-06-21

Subcellular resolution imaging of the whole brain and subsequent image analysis are prerequisites for understanding anatomical and functional brain networks. Here, we have developed a very high-speed serial-sectioning imaging system named FAST (block-face serial microscopy tomography), which acquires high-resolution images of a whole mouse brain in a speed range comparable to that of light-sheet fluorescence microscopy. FAST enables complete visualization of the brain at a resolution sufficient to resolve all cells and their subcellular structures. FAST renders unbiased quantitative group comparisons of normal and disease model brain cells for the whole brain at a high spatial resolution. Furthermore, FAST is highly scalable to non-human primate brains and human postmortem brain tissues, and can visualize neuronal projections in a whole adult marmoset brain. Thus, FAST provides new opportunities for global approaches that will allow for a better understanding of brain systems in multiple animal models and in human diseases. Copyright © 2017 Elsevier Inc. All rights reserved.

Per-Pixel Coded Exposure for High-Speed and High-Resolution Imaging Using a Digital Micromirror Device Camera

PubMed Central

Feng, Wei; Zhang, Fumin; Qu, Xinghua; Zheng, Shiwei

2016-01-01

High-speed photography is an important tool for studying rapid physical phenomena. However, low-frame-rate CCD (charge coupled device) or CMOS (complementary metal oxide semiconductor) camera cannot effectively capture the rapid phenomena with high-speed and high-resolution. In this paper, we incorporate the hardware restrictions of existing image sensors, design the sampling functions, and implement a hardware prototype with a digital micromirror device (DMD) camera in which spatial and temporal information can be flexibly modulated. Combined with the optical model of DMD camera, we theoretically analyze the per-pixel coded exposure and propose a three-element median quicksort method to increase the temporal resolution of the imaging system. Theoretically, this approach can rapidly increase the temporal resolution several, or even hundreds, of times without increasing bandwidth requirements of the camera. We demonstrate the effectiveness of our method via extensive examples and achieve 100 fps (frames per second) gain in temporal resolution by using a 25 fps camera. PMID:26959023

Per-Pixel Coded Exposure for High-Speed and High-Resolution Imaging Using a Digital Micromirror Device Camera.

PubMed

Feng, Wei; Zhang, Fumin; Qu, Xinghua; Zheng, Shiwei

2016-03-04

High-speed photography is an important tool for studying rapid physical phenomena. However, low-frame-rate CCD (charge coupled device) or CMOS (complementary metal oxide semiconductor) camera cannot effectively capture the rapid phenomena with high-speed and high-resolution. In this paper, we incorporate the hardware restrictions of existing image sensors, design the sampling functions, and implement a hardware prototype with a digital micromirror device (DMD) camera in which spatial and temporal information can be flexibly modulated. Combined with the optical model of DMD camera, we theoretically analyze the per-pixel coded exposure and propose a three-element median quicksort method to increase the temporal resolution of the imaging system. Theoretically, this approach can rapidly increase the temporal resolution several, or even hundreds, of times without increasing bandwidth requirements of the camera. We demonstrate the effectiveness of our method via extensive examples and achieve 100 fps (frames per second) gain in temporal resolution by using a 25 fps camera.

Ultrahigh phase-stable swept-source optical coherence tomography as a cardiac imaging platform (Conference Presentation)

NASA Astrophysics Data System (ADS)

Ling, Yuye; Hendon, Christine P.

2016-02-01

Functional extensions to optical coherence tomography (OCT) provide useful imaging contrasts that are complementary to conventional OCT. Our goal is to characterize tissue types within the myocardial due to remodeling and therapy. High-speed imaging is necessary to extract mechanical properties and dynamics of fiber orientation changes in a beating heart. Functional extensions of OCT such as polarization sensitive and optical coherence elastography (OCE) require high phase stability of the system, which is a drawback of current mechanically tuned swept source OCT systems. Here we present a high-speed functional imaging platform, which includes an ultrahigh-phase-stable swept source equipped with KTN deflector from NTT-AT. The swept source does not require mechanical movements during the wavelength sweeping; it is electrically tuned. The inter-sweep phase variance of the system was measured to be less than 300 ps at a path length difference of ~2 mm. The axial resolution of the system is 20 µm and the -10 dB fall-off depth is about 3.2 mm. The sample arm has an 8 mmx8 mm field of view with a lateral resolution of approximately 18 µm. The sample arm uses a two-axis MEMS mirror, which is programmable and capable of scanning arbitrary patterns at a sampling rate of 50 kHz. Preliminary imaging results showed differences in polarization properties and image penetration in ablated and normal myocardium. In the future, we will conduct dynamic stretching experiments with strips of human myocardial tissue to characterize mechanical properties using OCE. With high speed imaging of 200 kHz and an all-fiber design, we will work towards catheter-based functional imaging.

Walking smoothness is associated with self-reported function after accounting for gait speed.

PubMed

Lowry, Kristin A; Vanswearingen, Jessie M; Perera, Subashan; Studenski, Stephanie A; Brach, Jennifer S

2013-10-01

Gait speed has shown to be an indicator of functional status in older adults; however, there may be aspects of physical function not represented by speed but by the quality of movement. The purpose of this study was to determine the relations between walking smoothness, an indicator of the quality of movement based on trunk accelerations, and physical function. Thirty older adults (mean age, 77.7±5.1 years) participated. Usual gait speed was measured using an instrumented walkway. Walking smoothness was quantified by harmonic ratios derived from anteroposterior, vertical, and mediolateral trunk accelerations recorded during overground walking. Self-reported physical function was recorded using the function subscales of the Late-Life Function and Disability Instrument. Anteroposterior smoothness was positively associated with all function components of the Late-Life Function and Disability Instrument, whereas mediolateral smoothness exhibited negative associations. Adjusting for gait speed, anteroposterior smoothness remained associated with the overall and lower extremity function subscales, whereas mediolateral smoothness remained associated with only the advanced lower extremity subscale. These findings indicate that walking smoothness, particularly the smoothness of forward progression, represents aspects of the motor control of walking important for physical function not represented by gait speed alone.

The direct, not V1-mediated, functional influence between the thalamus and middle temporal complex in the human brain is modulated by the speed of visual motion.

PubMed

Gaglianese, A; Costagli, M; Ueno, K; Ricciardi, E; Bernardi, G; Pietrini, P; Cheng, K

2015-01-22

The main visual pathway that conveys motion information to the middle temporal complex (hMT+) originates from the primary visual cortex (V1), which, in turn, receives spatial and temporal features of the perceived stimuli from the lateral geniculate nucleus (LGN). In addition, visual motion information reaches hMT+ directly from the thalamus, bypassing the V1, through a direct pathway. We aimed at elucidating whether this direct route between LGN and hMT+ represents a 'fast lane' reserved to high-speed motion, as proposed previously, or it is merely involved in processing motion information irrespective of speeds. We evaluated functional magnetic resonance imaging (fMRI) responses elicited by moving visual stimuli and applied connectivity analyses to investigate the effect of motion speed on the causal influence between LGN and hMT+, independent of V1, using the Conditional Granger Causality (CGC) in the presence of slow and fast visual stimuli. Our results showed that at least part of the visual motion information from LGN reaches hMT+, bypassing V1, in response to both slow and fast motion speeds of the perceived stimuli. We also investigated whether motion speeds have different effects on the connections between LGN and functional subdivisions within hMT+: direct connections between LGN and MT-proper carry mainly slow motion information, while connections between LGN and MST carry mainly fast motion information. The existence of a parallel pathway that connects the LGN directly to hMT+ in response to both slow and fast speeds may explain why MT and MST can still respond in the presence of V1 lesions. Copyright © 2014 IBRO. Published by Elsevier Ltd. All rights reserved.

Effects of the dietary approaches to stop hypertension diet, exercise, and caloric restriction on neurocognition in overweight adults with high blood pressure.

PubMed

Smith, Patrick J; Blumenthal, James A; Babyak, Michael A; Craighead, Linda; Welsh-Bohmer, Kathleen A; Browndyke, Jeffrey N; Strauman, Timothy A; Sherwood, Andrew

2010-06-01

High blood pressure increases the risks of stroke, dementia, and neurocognitive dysfunction. Although aerobic exercise and dietary modifications have been shown to reduce blood pressure, no randomized trials have examined the effects of aerobic exercise combined with dietary modification on neurocognitive functioning in individuals with high blood pressure (ie, prehypertension and stage 1 hypertension). As part of a larger investigation, 124 participants with elevated blood pressure (systolic blood pressure 130 to 159 mm Hg or diastolic blood pressure 85 to 99 mm Hg) who were sedentary and overweight or obese (body mass index: 25 to 40 kg/m(2)) were randomized to the Dietary Approaches to Stop Hypertension (DASH) diet alone, DASH combined with a behavioral weight management program including exercise and caloric restriction, or a usual diet control group. Participants completed a battery of neurocognitive tests of executive function-memory-learning and psychomotor speed at baseline and again after the 4-month intervention. Participants on the DASH diet combined with a behavioral weight management program exhibited greater improvements in executive function-memory-learning (Cohen's D=0.562; P=0.008) and psychomotor speed (Cohen's D=0.480; P=0.023), and DASH diet alone participants exhibited better psychomotor speed (Cohen's D=0.440; P=0.036) compared with the usual diet control. Neurocognitive improvements appeared to be mediated by increased aerobic fitness and weight loss. Also, participants with greater intima-medial thickness and higher systolic blood pressure showed greater improvements in executive function-memory-learning in the group on the DASH diet combined with a behavioral weight management program. In conclusion, combining aerobic exercise with the DASH diet and caloric restriction improves neurocognitive function among sedentary and overweight/obese individuals with prehypertension and hypertension.

Reaction time, processing speed and sustained attention in schizophrenia: impact on social functioning.

PubMed

Lahera, Guillermo; Ruiz, Alicia; Brañas, Antía; Vicens, María; Orozco, Arantxa

Previous studies have linked processing speed with social cognition and functioning of patients with schizophrenia. A discriminant analysis is needed to determine the different components of this neuropsychological construct. This paper analyzes the impact of processing speed, reaction time and sustained attention on social functioning. 98 outpatients between 18 and 65 with DSM-5 diagnosis of schizophrenia, with a period of 3 months of clinical stability, were recruited. Sociodemographic and clinical data were collected, and the following variables were measured: processing speed (Trail Making Test [TMT], symbol coding [BACS], verbal fluency), simple and elective reaction time, sustained attention, recognition of facial emotions and global functioning. Processing speed (measured only through the BACS), sustained attention (CPT) and elective reaction time (but not simple) were associated with functioning. Recognizing facial emotions (FEIT) correlated significantly with scores on measures of processing speed (BACS, Animals, TMT), sustained attention (CPT) and reaction time. The linear regression model showed a significant relationship between functioning, emotion recognition (P=.015) and processing speed (P=.029). A deficit in processing speed and facial emotion recognition are associated with worse global functioning in patients with schizophrenia. Copyright © 2017 SEP y SEPB. Publicado por Elsevier España, S.L.U. All rights reserved.

Endothelial Progenitor Cell Levels Predict Future Physical Function: An Exploratory Analysis From the VA Enhanced Fitness Study.

PubMed

Povsic, Thomas J; Sloane, Richard; Pieper, Carl F; Pearson, Megan P; Peterson, Eric D; Cohen, Harvey J; Morey, Miriam C

2016-03-01

Levels of circulating progenitor cells (CPCs) are depleted with aging and chronic injury and are associated with level of physical functioning; however, little is known about the correlation of CPCs with longer-term measures of physical capabilities. We sought to determine the association of CPCs with future levels of physical function and with changes in physical function over time. CPCs were measured in 117 participants with impaired glucose tolerance in the Enhanced Fitness clinical trial based on the cell surface markers CD34 and CD133 and aldehyde dehydrogenase (ALDH) activity at baseline, 3 months, and 12 months. Physical function was assessed using usual and rapid gait speed, 6-minute walk distance, chair stand time, and SF-36 physical functioning score and reassessed at 3 and 12 months after clinical intervention. Higher baseline levels of CD133(+), CD34(+), CD133(+)CD34(+), and ALDH(br) were each highly predictive of faster gait speed and longer distance walked in 6 minutes at both 3 and 12 months. These associations remained robust after adjustment for age, body mass index, baseline covariates, and inflammation and were independent of interventions to improve physical fitness. Further, higher CPC levels predicted greater improvements in usual and rapid gait speed over 1 year. Baseline CPC levels are associated not only with baseline mobility but also with future physical function, including changes in gait speed. These findings suggest that CPC measurement may be useful as a marker of both current and future physiologic aging and functional decline. © The Author 2015. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Causal electric charge diffusion and balance functions in relativistic heavy-ion collisions

NASA Astrophysics Data System (ADS)

Kapusta, Joseph I.; Plumberg, Christopher

2018-01-01

We study the propagation and diffusion of electric charge fluctuations in high-energy heavy-ion collisions using the Cattaneo form for the dissipative part of the electric current. As opposed to the ordinary diffusion equation this form limits the speed at which charge can propagate. Including the noise term in the current, which arises uniquely from the fluctuation-dissipation theorem, we calculate the balance functions for charged hadrons in a simple 1+1-dimensional Bjorken hydrodynamical model. Limiting the speed of propagation of charge fluctuations increases the height and reduces the width of these balance functions when plotted versus rapidity. We also estimate the numerical value of the associated diffusion time constant from anti-de Sitter-space/conformal-field theory.

Low visual information-processing speed and attention are predictors of fatigue in elementary and junior high school students

PubMed Central

2011-01-01

Background Fatigue is a common complaint among elementary and junior high school students, and is known to be associated with reduced academic performance. Recently, we demonstrated that fatigue was correlated with decreased cognitive function in these students. However, no studies have identified cognitive predictors of fatigue. Therefore, we attempted to determine independent cognitive predictors of fatigue in these students. Methods We performed a prospective cohort study. One hundred and forty-two elementary and junior high school students without fatigue participated. They completed a variety of paper-and-pencil tests, including list learning and list recall tests, kana pick-out test, semantic fluency test, figure copying test, digit span forward test, and symbol digit modalities test. The participants also completed computerized cognitive tests (tasks A to E on the modified advanced trail making test). These cognitive tests were used to evaluate motor- and information-processing speed, immediate and delayed memory function, auditory and visual attention, divided and switching attention, retrieval of learned material, and spatial construction. One year after the tests, a questionnaire about fatigue (Japanese version of the Chalder Fatigue Scale) was administered to all the participants. Results After the follow-up period, we confirmed 40 cases of fatigue among 118 students. In multivariate logistic regression analyses adjusted for grades and gender, poorer performance on visual information-processing speed and attention tasks was associated with increased risk of fatigue. Conclusions Reduced visual information-processing speed and poor attention are independent predictors of fatigue in elementary and junior high school students. PMID:21672212

Low visual information-processing speed and attention are predictors of fatigue in elementary and junior high school students.

PubMed

Mizuno, Kei; Tanaka, Masaaki; Fukuda, Sanae; Yamano, Emi; Shigihara, Yoshihito; Imai-Matsumura, Kyoko; Watanabe, Yasuyoshi

2011-06-14

Fatigue is a common complaint among elementary and junior high school students, and is known to be associated with reduced academic performance. Recently, we demonstrated that fatigue was correlated with decreased cognitive function in these students. However, no studies have identified cognitive predictors of fatigue. Therefore, we attempted to determine independent cognitive predictors of fatigue in these students. We performed a prospective cohort study. One hundred and forty-two elementary and junior high school students without fatigue participated. They completed a variety of paper-and-pencil tests, including list learning and list recall tests, kana pick-out test, semantic fluency test, figure copying test, digit span forward test, and symbol digit modalities test. The participants also completed computerized cognitive tests (tasks A to E on the modified advanced trail making test). These cognitive tests were used to evaluate motor- and information-processing speed, immediate and delayed memory function, auditory and visual attention, divided and switching attention, retrieval of learned material, and spatial construction. One year after the tests, a questionnaire about fatigue (Japanese version of the Chalder Fatigue Scale) was administered to all the participants. After the follow-up period, we confirmed 40 cases of fatigue among 118 students. In multivariate logistic regression analyses adjusted for grades and gender, poorer performance on visual information-processing speed and attention tasks was associated with increased risk of fatigue. Reduced visual information-processing speed and poor attention are independent predictors of fatigue in elementary and junior high school students. © 2011 Mizuno et al; licensee BioMed Central Ltd.

Clinically important improvement in function is common in people with or at high risk of knee OA: the MOST study

PubMed Central

White, Daniel K.; Keysor, Julie J.; LaValley, Michael P.; Lewis, Cora E.; Torner, James C.; Nevitt, Michael C.; Felson, David T.

2010-01-01

To calculate the frequency of clinically important improvement in function over 30 months and identify risk factors in people who have or are at risk of knee OA. Subjects were from MOST, a longitudinal study of persons with or at high risk of knee OA. We defined Minimal Clinically Important Improvement (MCII) with WOMAC physical function using three different methods. Baseline risk factors tested for improvement included age, gender, educational attainment, presence of radiographic knee OA (ROA), the number of comorbidities, Body Mass Index (BMI), knee pain, walking speed, isokinetic knee extensor strength, depressive symptoms, physical activity, and medication usage. We used logistic regression to evaluate the association of baseline risk factors with MCII. Of the 1801 subjects (age= 63, BMI= 31, 63% female), most had mild limitations in baseline function (WOMAC = 19 +/− 11). Regardless how defined, a substantial percentage of subjects (24%–39%) reached MCII at 30 months. Compared to their counterparts, people with MCII were less likely to have ROA and to use medications, and were more likely to have a lower BMI, less knee pain, a faster walking speed, more knee strength, and fewer depressive symptoms. After adjustment, MCII was 40% to 50% less likely in those with ROA, and 1.9 to 2.0 times more likely in those walking 1.0 m/s faster than counterparts. Clinically important improvement is frequent in people with or at high risk of knee OA. The absence of ROA and a faster walking speed appear to be associated with clinically important improvements. PMID:20395640

Socioeconomic status, non-communicable disease risk factors, and walking speed in older adults: multi-cohort population based study.

PubMed

Stringhini, Silvia; Carmeli, Cristian; Jokela, Markus; Avendaño, Mauricio; McCrory, Cathal; d'Errico, Angelo; Bochud, Murielle; Barros, Henrique; Costa, Giuseppe; Chadeau-Hyam, Marc; Delpierre, Cyrille; Gandini, Martina; Fraga, Silvia; Goldberg, Marcel; Giles, Graham G; Lassale, Camille; Kenny, Rose Anne; Kelly-Irving, Michelle; Paccaud, Fred; Layte, Richard; Muennig, Peter; Marmot, Michael G; Ribeiro, Ana Isabel; Severi, Gianluca; Steptoe, Andrew; Shipley, Martin J; Zins, Marie; Mackenbach, Johan P; Vineis, Paolo; Kivimäki, Mika

2018-03-23

To assess the association of low socioeconomic status and risk factors for non-communicable diseases (diabetes, high alcohol intake, high blood pressure, obesity, physical inactivity, smoking) with loss of physical functioning at older ages. Multi-cohort population based study. 37 cohort studies from 24 countries in Europe, the United States, Latin America, Africa, and Asia, 1990-2017. 109 107 men and women aged 45-90 years. Physical functioning assessed using the walking speed test, a valid index of overall functional capacity. Years of functioning lost was computed as a metric to quantify the difference in walking speed between those exposed and unexposed to low socioeconomic status and risk factors. According to mixed model estimations, men aged 60 and of low socioeconomic status had the same walking speed as men aged 66.6 of high socioeconomic status (years of functioning lost 6.6 years, 95% confidence interval 5.0 to 9.4). The years of functioning lost for women were 4.6 (3.6 to 6.2). In men and women, respectively, 5.7 (4.4 to 8.1) and 5.4 (4.3 to 7.3) years of functioning were lost by age 60 due to insufficient physical activity, 5.1 (3.9 to 7.0) and 7.5 (6.1 to 9.5) due to obesity, 2.3 (1.6 to 3.4) and 3.0 (2.3 to 4.0) due to hypertension, 5.6 (4.2 to 8.0) and 6.3 (4.9 to 8.4) due to diabetes, and 3.0 (2.2 to 4.3) and 0.7 (0.1 to 1.5) due to tobacco use. In analyses restricted to high income countries, the number of years of functioning lost attributable to low socioeconomic status by age 60 was 8.0 (5.7 to 13.1) for men and 5.4 (4.0 to 8.0) for women, whereas in low and middle income countries it was 2.6 (0.2 to 6.8) for men and 2.7 (1.0 to 5.5) for women. Within high income countries, the number of years of functioning lost attributable to low socioeconomic status by age 60 was greater in the United States than in Europe. Physical functioning continued to decline as a function of unfavourable risk factors between ages 60 and 85. Years of functioning lost were greater than years of life lost due to low socioeconomic status and non-communicable disease risk factors. The independent association between socioeconomic status and physical functioning in old age is comparable in strength and consistency with those for established non-communicable disease risk factors. The results of this study suggest that tackling all these risk factors might substantially increase life years spent in good physical functioning. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Advanced techniques and technology for efficient data storage, access, and transfer

NASA Technical Reports Server (NTRS)

Rice, Robert F.; Miller, Warner

1991-01-01

Advanced techniques for efficiently representing most forms of data are being implemented in practical hardware and software form through the joint efforts of three NASA centers. These techniques adapt to local statistical variations to continually provide near optimum code efficiency when representing data without error. Demonstrated in several earlier space applications, these techniques are the basis of initial NASA data compression standards specifications. Since the techniques clearly apply to most NASA science data, NASA invested in the development of both hardware and software implementations for general use. This investment includes high-speed single-chip very large scale integration (VLSI) coding and decoding modules as well as machine-transferrable software routines. The hardware chips were tested in the laboratory at data rates as high as 700 Mbits/s. A coding module's definition includes a predictive preprocessing stage and a powerful adaptive coding stage. The function of the preprocessor is to optimally process incoming data into a standard form data source that the second stage can handle.The built-in preprocessor of the VLSI coder chips is ideal for high-speed sampled data applications such as imaging and high-quality audio, but additionally, the second stage adaptive coder can be used separately with any source that can be externally preprocessed into the 'standard form'. This generic functionality assures that the applicability of these techniques and their recent high-speed implementations should be equally broad outside of NASA.

Proton-driven electromagnetic instabilities in high-speed solar wind streams

NASA Technical Reports Server (NTRS)

Abraham-Shrauner, B.; Asbridge, J. R.; Bame, S. J.; Feldman, W. C.

1979-01-01

Electromagnetic instabilities of the field-aligned, right-hand circularly polarized magnetosonic wave and the left-hand circularly polarized Alfven wave driven by two drifted proton components are analyzed for model parameters determined from Imp 7 solar wind proton data measured during high-speed flow conditions. Growth rates calculated using bi-Lorentzian forms for the main and beam proton as well as core and halo electron velocity distributions do not differ significantly from those calculated using bi-Maxwellian forms. Using distribution parameters determined from 17 measured proton spectra, we show that considering the uncertainties the magnetosonic wave may be linearly stable and the Alfven wave is linearly unstable. Because proton velocity distribution function shapes are observed to persist for times long compared to the proton gyroperiod, the latter result suggests that linear stability theory fails for proton-driven ion cyclotron waves in the high-speed solar wind.

High-Speed Videography Overview

NASA Astrophysics Data System (ADS)

Miller, C. E.

1989-02-01

The field of high-speed videography (HSV) has continued to mature in recent years, due to the introduction of a mixture of new technology and extensions of existing technology. Recent low frame-rate innovations have the potential to dramatically expand the areas of information gathering and motion analysis at all frame-rates. Progress at the 0 - rate is bringing the battle of film versus video to the field of still photography. The pressure to push intermediate frame rates higher continues, although the maximum achievable frame rate has remained stable for several years. Higher maximum recording rates appear technologically practical, but economic factors impose severe limitations to development. The application of diverse photographic techniques to video-based systems is under-exploited. The basics of HSV apply to other fields, such as machine vision and robotics. Present motion analysis systems continue to function mainly as an instant replay replacement for high-speed movie film cameras. The interrelationship among lighting, shuttering and spatial resolution is examined.

High-speed rupture during the initiation of the 2015 Bonin Islands deep earthquake

NASA Astrophysics Data System (ADS)

Zhan, Z.; Ye, L.; Shearer, P. M.; Lay, T.; Kanamori, H.

2015-12-01

Among the long-standing questions on how deep earthquakes rupture, the nucleation phase of large deep events is one of the most puzzling parts. Resolving the rupture properties of the initiation phase is difficult to achieve with far-field data because of the need for accurate corrections for structural effects on the waveforms (e.g., attenuation, scattering, and site effects) and alignment errors. Here, taking the 2015 Mw 7.9 Bonin Islands earthquake (depth = 678 km) as an example, we jointly invert its far-field P waves at multiple stations for the average rupture speed during the first second of the event. We use waveforms from a closely located aftershock as empirical Green's functions, and correct for possible differences in focal mechanisms and waveform misalignments with an iterative approach. We find that the average initial rupture speed is over 5 km/s, significantly higher than the average rupture speed of 3 km/s later in the event. This contrast suggests that rupture speeds of deep earthquakes can be highly variable during individual events and may define different stages of rupture, potentially with different mechanisms.

Modeling the enhancement of the swimming speed of flagellated bacteria in polymer solutions

NASA Astrophysics Data System (ADS)

Tang, Jay X.; Zhang, Xuejun; Ye, Fangfu; Klimpert, William; Pelcovits, Robert

The swimming speed of many species of flagellated bacteria initially increases and then decreases as a function of the viscosity of the medium, which is varied by the addition of high molecular weight polymers. An earlier model accounts for such a peaked distribution, but it was recently shown to give rise to incorrect predictions for the cell body rotation rate. The authors of the latter work suggested that low-molecular weight impurities from the added polymers account for the peaked speed-viscosity curves in some cases. We measured the swimming speed of a uni-flagellated bacterium, caulobacter crescentus, in solutions of a number of polymers of several different sizes. Our findings confirm the peaked speed-viscosity curve for each of several distinct polymers added, suggesting that the general behavior is highly unlikely due to impurities. We propose a modification of the models used by the previous investigators in order to better explain our new experimental results. We have also performed numerical calculations based on the modified model to show that it properly accounts for the experimental results. NSF CBET 1438033 and Institute of Theoretical Physics, CAS.

Modeling and analysis of a flywheel microvibration isolation system for spacecrafts

NASA Astrophysics Data System (ADS)

Wei, Zhanji; Li, Dongxu; Luo, Qing; Jiang, Jianping

2015-01-01

The microvibrations generated by flywheels running at full speed onboard high precision spacecrafts will affect stability of the spacecraft bus and further degrade pointing accuracy of the payload. A passive vibration isolation platform comprised of multi-segment zig-zag beams is proposed to isolate disturbances of the flywheel. By considering the flywheel and the platform as an integral system with gyroscopic effects, an equivalent dynamic model is developed and verified through eigenvalue and frequency response analysis. The critical speeds of the system are deduced and expressed as functions of system parameters. The vibration isolation performance of the platform under synchronal and high-order harmonic disturbances caused by the flywheel is investigated. It is found that the speed range within which the passive platform is effective and the disturbance decay rate of the system are greatly influenced by the locations of the critical speeds. Structure optimization of the platform is carried out to enhance its performance. Simulation results show that a properly designed vibration isolation platform can effectively reduce disturbances emitted by the flywheel operating above the critical speeds of the system.

[Character and speed of recovery of psychophysiological functions after application of various kinds of anesthesia in conditions of a "one-day" stationary].

PubMed

Polinchuk, I S

2009-09-01

The frequency of operative interventions, performed according to the "one-day" stationary technology is raising every day. The patients are choosed in accordance with conventional methods, while somatic state of a patient and the further operation volume playing the leading role. But in 30% of patients in the early postoperative period and in 10.4% in the late postopeartive period the high psychic functions disorders occur, which are called postoperative cognitive dysfunction. The investigation is devoted to studying of character and speed of restoration of psychophysiologic functions after application of various general anaesthesy in conditions of the "one-day" stationary. There was proved, that apart of general anaesthesy scheme applied, in all the patients the cognitive functions defect was noted in postoperative period. These functions are restored most quickly in application of propofol in the scheme and most slower in mononarcosis with ketamin.

Characterization of the CEBAF 100 kV DC GaAs Photoelectron Gun Vacuum System

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

Stutzman, M L; Adderley, P; Brittian, J

A vacuum system with pressure in the low ultra-high vacuum (UHV) range is essential for long photocathode lifetimes in DC high voltage GaAs photoguns. A discrepancy between predicted and measured base pressure in the CEBAF photoguns motivated this study of outgassing rates of three 304 stainless steel chambers with different pretreatments and pump speed measurements of non-evaporable getter (NEG) pumps. Outgassing rates were measured using two independent techniques. Lower outgassing rates were achieved by electropolishing and vacuum firing the chamber. The second part of the paper describes NEG pump speed measurements as a function of pressure through the lower partmore » of the UHV range. Measured NEG pump speed is high at pressures above 5×10 -11 Torr, but may decrease at lower pressures depending on the interpretation of the data. The final section investigates the pump speed of a locally produced NEG coating applied to the vacuum chamber walls. These studies represent the first detailed vacuum measurements of CEBAF photogun vacuum chambers.« less

Interrelations Between Mitochondrial DNA Copy Number and Inflammation in Older Adults.

PubMed

Wu, I-Chien; Lin, Cheng-Chieh; Liu, Chin-San; Hsu, Chih-Cheng; Chen, Ching-Yu; Hsiung, Chao A

2017-07-01

Interplays between inflammation and mitochondrial biology are reported. Here, we examined the cross-sectional interrelationships of mitochondrial DNA copy number (mtDNACN) and inflammation and their interaction with physical functioning. A total of 1990 community-dwelling adults aged 65 years and older who were participating in the Healthy Aging Longitudinal Study in Taiwan underwent measurements of peripheral-blood leukocytes MtDNACN, multiple inflammatory markers, grip strength, and gait speed. Principal components analysis revealed two inflammatory factors: factor 1 (high-sensitivity C-reactive protein [hs-CRP], white blood cell count, fibrinogen and interleukin-6 [IL-6]); factor 2 (tumor necrosis factor receptor 1, D-dimer and soluble interleukin-6 receptor). Participants with severe physical functioning impairment (low grip strength and gait speed) had higher (p < .05) levels of factor 1 and 2, but not mtDNACN, than did those with moderately impaired (low grip strength or gait speed) and normal physical functioning. MtDNACN was negatively related to factor 1 (r = -.221, p < .001) but not factor 2 (r = -.002, p = .938). Increased factor 1 was strongly associated with higher odds of physical functioning impairment in those with a low mtDNACN (adjusted odds ratios [OR] of moderate physical function impairment 1.21, 95% CI 1.01-1.44; adjusted OR of severe physical function impairment 1.52, 95% CI 1.25-1.85) but not in those with a high mtDNACN (p for interaction = .016). A low mtDNACN was associated with an inflammation exhibiting elevated hs-CRP, IL-6, fibrinogen, and white blood cell count, and strengthened the association of this inflammation with physical functioning impairment. © The Author 2017. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Deep versus periventricular white matter lesions and cognitive function in a community sample of middle-aged participants.

PubMed

Soriano-Raya, Juan José; Miralbell, Júlia; López-Cancio, Elena; Bargalló, Núria; Arenillas, Juan Francisco; Barrios, Maite; Cáceres, Cynthia; Toran, Pere; Alzamora, Maite; Dávalos, Antoni; Mataró, Maria

2012-09-01

The association of cerebral white matter lesions (WMLs) with cognitive status is not well understood in middle-aged individuals. Our aim was to determine the specific contribution of periventricular hyperintensities (PVHs) and deep white matter hyperintensities (DWMHs) to cognitive function in a community sample of asymptomatic participants aged 50 to 65 years. One hundred stroke- and dementia-free adults completed a comprehensive neuropsychological battery and brain MRI protocol. Participants were classified according to PVH and DWMH scores (Fazekas scale). We dichotomized our sample into low grade WMLs (participants without or with mild lesions) and high grade WMLs (participants with moderate or severe lesions). Analyses were performed separately in PVH and DWMH groups. High grade DWMHs were associated with significantly lower scores in executive functioning (-0.45 standard deviations [SD]), attention (-0.42 SD), verbal fluency (-0.68 SD), visual memory (-0.52 SD), visuospatial skills (-0.79 SD), and psychomotor speed (-0.46 SD). Further analyses revealed that high grade DWMHs were also associated with a three- to fourfold increased risk of impaired scores (i.e.,<1.5 SD) in executive functioning, verbal fluency, visuospatial skills, and psychomotor speed. Our findings suggest that only DWMHs, not PVHs, are related to diminished cognitive function in middle-aged individuals. (JINS, 2012, 18, 1-12).

Do Effort and Reward at Work Predict Changes in Cognitive Function? First Longitudinal Results from the Representative German Socio-Economic Panel

PubMed Central

Riedel, Natalie; Siegrist, Johannes; Wege, Natalia; Loerbroks, Adrian; Angerer, Peter; Li, Jian

2017-01-01

It has been suggested that work characteristics, such as mental demands, job control, and occupational complexity, are prospectively related to cognitive function. However, current evidence on links between psychosocial working conditions and cognitive change over time is inconsistent. In this study, we applied the effort–reward imbalance model that allows to build on previous research on mental demands and to introduce reward-based learning as a principle with beneficial effect on cognitive function. We aimed to investigate whether high effort, high reward, and low over-commitment in 2006 were associated with positive changes in cognitive function in terms of perceptual speed and word fluency (2006–2012), and whether the co-manifestation of high effort and high reward would yield the strongest association. To this end, we used data on 1031 employees who participated in a large and representative study. Multivariate linear regression analyses supported our main hypotheses (separate and combined effects of effort and reward), particularly on changes in perceptual speed, whereas the effects of over-commitment did not reach the level of statistical significance. Our findings extend available knowledge by examining the course of cognitive function over time. If corroborated by further evidence, organization-based measures in the workplace can enrich efforts towards preventing cognitive decline in ageing workforces. PMID:29140258

Generation and characterization of field-emitting surface dielectric barrier discharges in liquids

NASA Astrophysics Data System (ADS)

Kawamura, Tomohisa; Kanno, Moriyuki; Stauss, Sven; Kuribara, Koichi; Pai, David Z.; Ito, Tsuyohito; Terashima, Kazuo

2018-01-01

Field-emitting surface dielectric barrier discharges (FESDBDs), previously generated in CO2 from high pressures up to supercritical conditions using 10 kHz ac excitation, were investigated in non-aqueous liquid CO2 and liquid silicone oil. In both liquids, the maximum amount of negative charge Q-deposited as a function of the applied voltage amplitude was consistent with the Fowler-Nordheim equation, which demonstrated the presence of field emission. Furthermore, purely continuum optical emission spectra attributable to electron-neutral bremsstrahlung were confirmed. The fact that these characteristics were identical to those in high-pressure CO2 reported from previous research shows that FESDBDs can be generated independently of the medium type and that they are low-power (on the order of 10 mW) discharges. To investigate the charging function of FESDBDs, the motion of fine particles suspended above the FESDBDs was studied by high-speed imaging. It revealed that the speed of fine particles affected by the FESDBDs depends on the particle size, the FESDBDs' function being to charge fine particles.

Kinematics of fast cervical rotations in persons with chronic neck pain: a cross-sectional and reliability study.

PubMed

Röijezon, Ulrik; Djupsjöbacka, Mats; Björklund, Martin; Häger-Ross, Charlotte; Grip, Helena; Liebermann, Dario G

2010-09-27

Assessment of sensorimotor function is useful for classification and treatment evaluation of neck pain disorders. Several studies have investigated various aspects of cervical motor functions. Most of these have involved slow or self-paced movements, while few have investigated fast cervical movements. Moreover, the reliability of assessment of fast cervical axial rotation has, to our knowledge, not been evaluated before. Cervical kinematics was assessed during fast axial head rotations in 118 women with chronic nonspecific neck pain (NS) and compared to 49 healthy controls (CON). The relationship between cervical kinematics and symptoms, self-rated functioning and fear of movement was evaluated in the NS group. A sub-sample of 16 NS and 16 CON was re-tested after one week to assess the reliability of kinematic variables. Six cervical kinematic variables were calculated: peak speed, range of movement, conjunct movements and three variables related to the shape of the speed profile. Together, peak speed and conjunct movements had a sensitivity of 76% and a specificity of 78% in discriminating between NS and CON, of which the major part could be attributed to peak speed (NS: 226 ± 88°/s and CON: 348 ± 92°/s, p < 0.01). Peak speed was slower in NS compared to healthy controls and even slower in NS with comorbidity of low-back pain. Associations were found between reduced peak speed and self-rated difficulties with running, performing head movements, car driving, sleeping and pain. Peak speed showed reasonably high reliability, while the reliability for conjunct movements was poor. Peak speed of fast cervical axial rotations is reduced in people with chronic neck pain, and even further reduced in subjects with concomitant low back pain. Fast cervical rotation test seems to be a reliable and valid tool for assessment of neck pain disorders on group level, while a rather large between subject variation and overlap between groups calls for caution in the interpretation of individual assessments.

[High-contrast resolution of film-screen systems in oral and maxillofacial radiology].

PubMed

Kaeppler, G; Reinert, S

2007-11-01

The aim was to determine differences in high-contrast resolution of film-screen systems used in dental panoramic and cephalometric radiography by calculating the modulation transfer function (MTF). The radiographs used to determine the MTF should be taken by the same x-ray units as those used for patient radiographs. The MTF was determined using a lead grid and according to DIN 6867-2 for 11 film-screen systems (speed 250, speed class 200 and 400) used in dental radiographic diagnostics. The optical density was measured using a microdensitometer developed by PTB. With 10% of the modulation transfer factor, newly developed film-screen systems (speed class 200 and 400) demonstrated a resolution of 4.9 to 6 line pairs per mm (panoramic radiography). In cephalometric radiography a film-screen system (speed class 400 and green-sensitive film) had a resolution of 4.2 line pairs per mm and surpassed two film-screen systems (speed class 400, resolution of 3 line pairs per mm, blue-sensitive films). The relevance of this study is underlined by the diagnostic reference doses defined in the German X-ray Ordinance (RöV) which are also intended for dentistry. Film-screen systems (speed 250, speed class 200) previously used in dental panoramic and cephalometric radiography can be replaced by newly developed film-screen systems (speed class 400). In dental radiography dose reductions are possible with film-screen systems (speed class 400) without impairing diagnostic accuracy. The introduction of newly developed film-screen systems (speed class 400) requires lower milliampere-seconds and therefore an adjustment of the x-ray units to lower milliampere settings.

High-speed transport-of-intensity phase microscopy with an electrically tunable lens.

PubMed

Zuo, Chao; Chen, Qian; Qu, Weijuan; Asundi, Anand

2013-10-07

We present a high-speed transport-of-intensity equation (TIE) quantitative phase microscopy technique, named TL-TIE, by combining an electrically tunable lens with a conventional transmission microscope. This permits the specimen at different focus position to be imaged in rapid succession, with constant magnification and no physically moving parts. The simplified image stack collection significantly reduces the acquisition time, allows for the diffraction-limited through-focus intensity stack collection at 15 frames per second, making dynamic TIE phase imaging possible. The technique is demonstrated by profiling of microlens array using optimal frequency selection scheme, and time-lapse imaging of live breast cancer cells by inversion the defocused phase optical transfer function to correct the phase blurring in traditional TIE. Experimental results illustrate its outstanding capability of the technique for quantitative phase imaging, through a simple, non-interferometric, high-speed, high-resolution, and unwrapping-free approach with prosperous applications in micro-optics, life sciences and bio-photonics.

Mechanical diagnosis of human erythrocytes by ultra-high speed manipulation unraveled critical time window for global cytoskeletal remodeling

NASA Astrophysics Data System (ADS)

Ito, Hiroaki; Murakami, Ryo; Sakuma, Shinya; Tsai, Chia-Hung Dylan; Gutsmann, Thomas; Brandenburg, Klaus; Pöschl, Johannes M. B.; Arai, Fumihito; Kaneko, Makoto; Tanaka, Motomu

2017-02-01

Large deformability of erythrocytes in microvasculature is a prerequisite to realize smooth circulation. We develop a novel tool for the three-step “Catch-Load-Launch” manipulation of a human erythrocyte based on an ultra-high speed position control by a microfluidic “robotic pump”. Quantification of the erythrocyte shape recovery as a function of loading time uncovered the critical time window for the transition between fast and slow recoveries. The comparison with erythrocytes under depletion of adenosine triphosphate revealed that the cytoskeletal remodeling over a whole cell occurs in 3 orders of magnitude longer timescale than the local dissociation-reassociation of a single spectrin node. Finally, we modeled septic conditions by incubating erythrocytes with endotoxin, and found that the exposure to endotoxin results in a significant delay in the characteristic transition time for cytoskeletal remodeling. The high speed manipulation of erythrocytes with a robotic pump technique allows for high throughput mechanical diagnosis of blood-related diseases.

A high-speed on-chip pseudo-random binary sequence generator for multi-tone phase calibration

NASA Astrophysics Data System (ADS)

Gommé, Liesbeth; Vandersteen, Gerd; Rolain, Yves

2011-07-01

An on-chip reference generator is conceived by adopting the technique of decimating a pseudo-random binary sequence (PRBS) signal in parallel sequences. This is of great benefit when high-speed generation of PRBS and PRBS-derived signals is the objective. The design implemented standard CMOS logic is available in commercial libraries to provide the logic functions for the generator. The design allows the user to select the periodicity of the PRBS and the PRBS-derived signals. The characterization of the on-chip generator marks its performance and reveals promising specifications.

BRDF-dependent accuracy of array-projection-based 3D sensors.

PubMed

Heist, Stefan; Kühmstedt, Peter; Tünnermann, Andreas; Notni, Gunther

2017-03-10

In order to perform high-speed three-dimensional (3D) shape measurements with structured light systems, high-speed projectors are required. One possibility is an array projector, which allows pattern projection at several tens of kilohertz by switching on and off the LEDs of various slide projectors. The different projection centers require a separate analysis, as the intensity received by the cameras depends on the projection direction and the object's bidirectional reflectance distribution function (BRDF). In this contribution, we investigate the BRDF-dependent errors of array-projection-based 3D sensors and propose an error compensation process.

High speed capacitor-inverter based carbon nanotube full adder.

PubMed

Navi, K; Rashtian, M; Khatir, A; Keshavarzian, P; Hashemipour, O

2010-03-18

Carbon Nanotube filed-effect transistor (CNFET) is one of the promising alternatives to the MOS transistors. The geometry-dependent threshold voltage is one of the CNFET characteristics, which is used in the proposed Full Adder cell. In this paper, we present a high speed Full Adder cell using CNFETs based on majority-not (Minority) function. Presented design uses eight transistors and eight capacitors. Simulation results show significant improvement in terms of delay and power-delay product in comparison to contemporary CNFET Adder Cells. Simulations were carried out using HSPICE based on CNFET model with 0.6 V VDD.

High-speed Fourier ptychographic microscopy based on programmable annular illuminations.

PubMed

Sun, Jiasong; Zuo, Chao; Zhang, Jialin; Fan, Yao; Chen, Qian

2018-05-16

High-throughput quantitative phase imaging (QPI) is essential to cellular phenotypes characterization as it allows high-content cell analysis and avoids adverse effects of staining reagents on cellular viability and cell signaling. Among different approaches, Fourier ptychographic microscopy (FPM) is probably the most promising technique to realize high-throughput QPI by synthesizing a wide-field, high-resolution complex image from multiple angle-variably illuminated, low-resolution images. However, the large dataset requirement in conventional FPM significantly limits its imaging speed, resulting in low temporal throughput. Moreover, the underlying theoretical mechanism as well as optimum illumination scheme for high-accuracy phase imaging in FPM remains unclear. Herein, we report a high-speed FPM technique based on programmable annular illuminations (AIFPM). The optical-transfer-function (OTF) analysis of FPM reveals that the low-frequency phase information can only be correctly recovered if the LEDs are precisely located at the edge of the objective numerical aperture (NA) in the frequency space. By using only 4 low-resolution images corresponding to 4 tilted illuminations matching a 10×, 0.4 NA objective, we present the high-speed imaging results of in vitro Hela cells mitosis and apoptosis at a frame rate of 25 Hz with a full-pitch resolution of 655 nm at a wavelength of 525 nm (effective NA = 0.8) across a wide field-of-view (FOV) of 1.77 mm 2 , corresponding to a space-bandwidth-time product of 411 megapixels per second. Our work reveals an important capability of FPM towards high-speed high-throughput imaging of in vitro live cells, achieving video-rate QPI performance across a wide range of scales, both spatial and temporal.

Unified aeroacoustics analysis for high speed turboprop aerodynamics and noise. Volume 5: Propagation of propeller tone noise through a fuselage boundary layer

NASA Technical Reports Server (NTRS)

Magliozzi, B.; Hanson, D. B.

1991-01-01

An analysis of tone noise propagation through a boundary layer and fuselage scattering effects was derived. This analysis is a three dimensional and the complete wave field is solved by matching analytical expressions for the incident and scattered waves in the outer flow to a numerical solution in the boundary layer flow. The outer wave field is constructed analytically from an incident wave appropriate to the source and a scattered wave in the standard Hankel function form. For the incident wave, an existing function - domain propeller noise radiation theory is used. In the boundary layer region, the wave equation is solved by numerical methods. The theoretical analysis is embodied in a computer program which allows the calculation of correction factors for the fuselage scattering and boundary layer refraction effects. The effects are dependent on boundary layer profile, flight speed, and frequency. Corrections can be derived for any point on the fuselage, including those on the opposite side from the source. The theory was verified using limited cases and by comparing calculations with available measurements from JetStar tests of model prop-fans. For the JetStar model scale, the boundary layer refraction effects produce moderate fuselage pressure reinforcements aft of and near the plane of rotation and significant attenuation forward of the plane of rotation at high flight speeds. At lower flight speeds, the calculated boundary layer effects result in moderate amplification over the fuselage area of interest. Apparent amplification forward of the plane of rotation is a result of effective changes in the source directivity due to boundary layer refraction effects. Full scale effects are calculated to be moderate, providing fuselage pressure amplification of about 5 dB at the peak noise location. Evaluation using available noise measurements was made under high-speed, high-altitude flight conditions. Comparisons of calculations made of free field noise, using a current frequency-domain propeller noise prediction method, and fuselage effects using this new procedure show good agreement with fuselage measurements over a wide range of flight speeds and frequencies. Correction factors for the JetStar measurements made on the fuselage are provided in an Appendix.

Hardware Neural Network for a Visual Inspection System

NASA Astrophysics Data System (ADS)

Chun, Seungwoo; Hayakawa, Yoshihiro; Nakajima, Koji

The visual inspection of defects in products is heavily dependent on human experience and instinct. In this situation, it is difficult to reduce the production costs and to shorten the inspection time and hence the total process time. Consequently people involved in this area desire an automatic inspection system. In this paper, we propose a hardware neural network, which is expected to provide high-speed operation for automatic inspection of products. Since neural networks can learn, this is a suitable method for self-adjustment of criteria for classification. To achieve high-speed operation, we use parallel and pipelining techniques. Furthermore, we use a piecewise linear function instead of a conventional activation function in order to save hardware resources. Consequently, our proposed hardware neural network achieved 6GCPS and 2GCUPS, which in our test sample proved to be sufficiently fast.

From “Comprehensive Transportation Hub” to “City New Sitting Room”---Overall the design about Jinan East district comprehensive transportation hub

NASA Astrophysics Data System (ADS)

Lv, Jie; Guo, Jianmin; Li, Jin

2017-08-01

integrated transport hub or high-speed rail station often talked about, often known as the “city portal” and the title of “city window”, so the comprehensive transportation hub or the high-speed rail station of a city is very important to a region or a provincial. At the same time, it reflects that the managers and users of a city only focus on the comprehensive transportation hub of transportation service function and ignore her cities attributes and functions. Jinan east district comprehensive transportation hub in the beginning of design is given a feature that it has to serve both the traffic and city. We are trying to build a new center for Jinan east new town, the window to welcome people, the city hall of hospitality.

Effects of a progressive resistance exercise program with high-speed component on the physical function of older women with sarcopenic obesity: a randomized controlled trial

PubMed Central

Vasconcelos, Karina S. S.; Dias, João M. D.; Araújo, Marília C.; Pinheiro, Ana C.; Moreira, Bruno S.; Dias, Rosângela C.

2016-01-01

ABSTRACT Background Sarcopenic obesity is associated with disability in older people, especially in women. Resistance exercises are recommended for this population, but their efficacy is not clear. Objective To evaluate the effects of a progressive resistance exercise program with high-speed component on the physical function of older women with sarcopenic obesity. Method Twenty-eight women 65 to 80 years old, with a body mass index ≥30kg/m2 and handgrip strength ≤21kg were randomly allocated to two groups. The experimental group underwent a 10-week resistance exercise program designed to improve strength, power, and endurance of lower-limb muscles, with open chain and closed chain exercises. The control group had their health status monitored through telephone calls. The primary outcomes were lower limb muscle performance measured by knee extensor strength, power and fatigue by isokinetic dynamometry, and mobility measured by the Short Physical Performance Battery and by gait velocity. The secondary outcome was health-related quality of life assessed by the SF-36 Questionnaire. Results The average rate of adherence was 85%, with few mild adverse effects. There were no significant between-group differences for any of the outcomes. Conclusion In this study, a progressive resistance exercise program with high-speed component was not effective for improving the physical function of older women with sarcopenic obesity. PMID:27410162

Property-driven functional verification technique for high-speed vision system-on-chip processor

NASA Astrophysics Data System (ADS)

Nshunguyimfura, Victor; Yang, Jie; Liu, Liyuan; Wu, Nanjian

2017-04-01

The implementation of functional verification in a fast, reliable, and effective manner is a challenging task in a vision chip verification process. The main reason for this challenge is the stepwise nature of existing functional verification techniques. This vision chip verification complexity is also related to the fact that in most vision chip design cycles, extensive efforts are focused on how to optimize chip metrics such as performance, power, and area. Design functional verification is not explicitly considered at an earlier stage at which the most sound decisions are made. In this paper, we propose a semi-automatic property-driven verification technique. The implementation of all verification components is based on design properties. We introduce a low-dimension property space between the specification space and the implementation space. The aim of this technique is to speed up the verification process for high-performance parallel processing vision chips. Our experimentation results show that the proposed technique can effectively improve the verification effort up to 20% for the complex vision chip design while reducing the simulation and debugging overheads.

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

Cognitive impairment and antiretroviral treatment in a Peruvian population of patients with human immunodeficiency virus.

PubMed

Guevara-Silva, E A

2014-05-01

HIV-associated cognitive impairment occurs even in the early stages of infection. Short-term memory, psychomotor speed, attention, and executive functioning are the main capacities affected. Controversy exists regarding whether highly active antiretroviral therapy (HAART) is helpful in combating this process. The objective of the present study is to determine the association between cognitive impairment and HAART in HIV-infected patients from Hospital Regional de Huacho. Prospective study of HIV patients meeting criteria to start HAART. Twenty-one HIV-positive patients were recruited between April and July 2011. Researchers administered a standardised neuropsychological test battery before and 4 weeks after onset of HAART. Psychomotor speed, executive function, short term memory (visual and verbal), attention, and visuospatial performance were evaluated. Nineteen patients completed the study (14 males and 5 females). In the pre-HAART evaluation, most patients scored below average on the executive function and psychomotor speed subtests. Psychomotor speed and immediate visual memory improved significantly after four months of treatment with HAART. Some degree of cognitive decline may present even in the early and asymptomatic stages of HIV infection. The benefits of antiretroviral treatment for cognitive performance can be detected after only a few weeks of follow-up. Copyright © 2013 Sociedad Española de Neurología. Published by Elsevier Espana. All rights reserved.

Validation of High Speed Earth Atmospheric Entry Radiative Heating from 9.5 to 15.5 km/s

NASA Technical Reports Server (NTRS)

Brandis, A. M.; Johnston, C. O.; Cruden, B. A.; Prabhu, D. K.

2016-01-01

This paper presents an overview of the analysis and measurements of equilibrium radiation obtained in the NASA Ames Research Center's Electric Arc Shock Tube (EAST) facility as a part of recent testing aimed at reaching shock velocities up to 15.5 km/s. The goal of these experiments was to measure the level of radiation encountered during high speed Earth entry conditions, such as would be relevant for an asteroid, inter-planetary or lunar return mission. These experiments provide the first spectrally and spatially resolved data for high speed Earth entry and cover conditions ranging from 9.5 to 15.5 km/s at 13.3 and 26.6 Pa (0.1 and 0.2 Torr). The present analysis endeavors to provide a validation of shock tube radiation measurements and simulations at high speed conditions. A comprehensive comparison between the spectrally resolved absolute equilibrium radiance measured in EAST and the predictive tools, NEQAIR and HARA, is presented. In order to provide a more accurate representation of the agreement between the experimental and simulation results, the integrated value of radiance has been compared across four spectral regions (VUV, UV/Vis, Vis/NIR and IR) as a function of velocity. Results have generally shown excellent agreement between the two codes and EAST data for the Vis through IR spectral regions, however, discrepancies have been identified in the VUV and parts of the UV spectral regions. As a result of the analysis presented in this paper, an updated parametric uncertainty for high speed radiation in air has been evaluated to be [9.0%, -6.3%]. Furthermore, due to the nature of the radiating environment at these high shock speeds, initial calculations aimed at modeling phenomena that become more significant with increasing shock speed have been performed. These phenomena include analyzing the radiating species emitting ahead of the shock and the increased significance of radiative cooling mechanisms.

Longitudinal Study of a Novel Performance-based Measure of Daily Function

DTIC Science & Technology

2015-04-01

measures of cognition (e.g., episodic memory , semantic memory , executive function, speed). We found that patients with MCI had compromises in...UPSA, as well as measures of cognition (e.g., episodic memory , semantic memory , executive function, speed). We found that patients with MCI had... memory , semantic memory , executive function, speed). We found that patients with MCI had compromises in everyday functional competence and that the

A high-speed network for cardiac image review.

PubMed

Elion, J L; Petrocelli, R R

1994-01-01

A high-speed fiber-based network for the transmission and display of digitized full-motion cardiac images has been developed. Based on Asynchronous Transfer Mode (ATM), the network is scaleable, meaning that the same software and hardware is used for a small local area network or for a large multi-institutional network. The system can handle uncompressed digital angiographic images, considered to be at the "high-end" of the bandwidth requirements. Along with the networking, a general-purpose multi-modality review station has been implemented without specialized hardware. This station can store a full injection sequence in "loop RAM" in a 512 x 512 format, then interpolate to 1024 x 1024 while displaying at 30 frames per second. The network and review stations connect to a central file server that uses a virtual file system to make a large high-speed RAID storage disk and associated off-line storage tapes and cartridges all appear as a single large file system to the software. In addition to supporting archival storage and review, the system can also digitize live video using high-speed Direct Memory Access (DMA) from the frame grabber to present uncompressed data to the network. Fully functional prototypes have provided the proof of concept, with full deployment in the institution planned as the next stage.

A high-speed network for cardiac image review.

PubMed Central

Elion, J. L.; Petrocelli, R. R.

1994-01-01

A high-speed fiber-based network for the transmission and display of digitized full-motion cardiac images has been developed. Based on Asynchronous Transfer Mode (ATM), the network is scaleable, meaning that the same software and hardware is used for a small local area network or for a large multi-institutional network. The system can handle uncompressed digital angiographic images, considered to be at the "high-end" of the bandwidth requirements. Along with the networking, a general-purpose multi-modality review station has been implemented without specialized hardware. This station can store a full injection sequence in "loop RAM" in a 512 x 512 format, then interpolate to 1024 x 1024 while displaying at 30 frames per second. The network and review stations connect to a central file server that uses a virtual file system to make a large high-speed RAID storage disk and associated off-line storage tapes and cartridges all appear as a single large file system to the software. In addition to supporting archival storage and review, the system can also digitize live video using high-speed Direct Memory Access (DMA) from the frame grabber to present uncompressed data to the network. Fully functional prototypes have provided the proof of concept, with full deployment in the institution planned as the next stage. PMID:7949964

23 CFR Appendix A to Part 772 - National Reference Energy Mean Emission Levels as a Function of Speed

Code of Federal Regulations, 2010 CFR

2010-04-01

... 23 Highways 1 2010-04-01 2010-04-01 false National Reference Energy Mean Emission Levels as a Function of Speed A Appendix A to Part 772 Highways FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF... Function of Speed EC14OC91.013 ...

EFFECTS OF THE GENIUM MICROPROCESSOR KNEE SYSTEM ON KNEE MOMENT SYMMETRY DURING HILL WALKING.

PubMed

Highsmith, M Jason; Klenow, Tyler D; Kahle, Jason T; Wernke, Matthew M; Carey, Stephanie L; Miro, Rebecca M; Lura, Derek J

2016-09-01

Use of the Genium microprocessor knee (MPK) system reportedly improves knee kinematics during walking and other functional tasks compared to other MPK systems. This improved kinematic pattern was observed when walking on different hill conditions and at different speeds. Given the improved kinematics associated with hill walking while using the Genium, a similar improvement in the symmetry of knee kinetics is also feasible. The purpose of this study was to determine if Genium MPK use would reduce the degree of asymmetry (DoA) of peak stance knee flexion moment compared to the C-Leg MPK in transfemoral amputation (TFA) patients. This study used a randomized experimental crossover of TFA patients using Genium and C-Leg MPKs ( n = 20). Biomechanical gait analysis by 3D motion tracking with floor mounted force plates of TFA patients ambulating at different speeds on 5° ramps was completed. Knee moment DoA was significantly different between MPK conditions in the slow and fast uphill as well as the slow and self-selected downhill conditions. In a sample of high-functioning TFA patients, Genium knee system accommodation and use improved knee moment symmetry in slow speed walking up and down a five degree ramp compared with C-Leg. Additionally, the Genium improved knee moment symmetry when walking downhill at comfortable speed. These results likely have application in other patients who could benefit from more consistent knee function, such as older patients and others who have slower walking speeds.

Brain training game boosts executive functions, working memory and processing speed in the young adults: a randomized controlled trial.

PubMed

Nouchi, Rui; Taki, Yasuyuki; Takeuchi, Hikaru; Hashizume, Hiroshi; Nozawa, Takayuki; Kambara, Toshimune; Sekiguchi, Atsushi; Miyauchi, Carlos Makoto; Kotozaki, Yuka; Nouchi, Haruka; Kawashima, Ryuta

2013-01-01

Do brain training games work? The beneficial effects of brain training games are expected to transfer to other cognitive functions. Yet in all honesty, beneficial transfer effects of the commercial brain training games in young adults have little scientific basis. Here we investigated the impact of the brain training game (Brain Age) on a wide range of cognitive functions in young adults. We conducted a double-blind (de facto masking) randomized controlled trial using a popular brain training game (Brain Age) and a popular puzzle game (Tetris). Thirty-two volunteers were recruited through an advertisement in the local newspaper and randomly assigned to either of two game groups (Brain Age, Tetris). Participants in both the Brain Age and the Tetris groups played their game for about 15 minutes per day, at least 5 days per week, for 4 weeks. Measures of the cognitive functions were conducted before and after training. Measures of the cognitive functions fell into eight categories (fluid intelligence, executive function, working memory, short-term memory, attention, processing speed, visual ability, and reading ability). Our results showed that commercial brain training game improves executive functions, working memory, and processing speed in young adults. Moreover, the popular puzzle game can engender improvement attention and visuo-spatial ability compared to playing the brain training game. The present study showed the scientific evidence which the brain training game had the beneficial effects on cognitive functions (executive functions, working memory and processing speed) in the healthy young adults. Our results do not indicate that everyone should play brain training games. However, the commercial brain training game might be a simple and convenient means to improve some cognitive functions. We believe that our findings are highly relevant to applications in educational and clinical fields. UMIN Clinical Trial Registry 000005618.

Brain Training Game Boosts Executive Functions, Working Memory and Processing Speed in the Young Adults: A Randomized Controlled Trial

PubMed Central

Nouchi, Rui; Taki, Yasuyuki; Takeuchi, Hikaru; Hashizume, Hiroshi; Nozawa, Takayuki; Kambara, Toshimune; Sekiguchi, Atsushi; Miyauchi, Carlos Makoto; Kotozaki, Yuka; Nouchi, Haruka; Kawashima, Ryuta

2013-01-01

Background Do brain training games work? The beneficial effects of brain training games are expected to transfer to other cognitive functions. Yet in all honesty, beneficial transfer effects of the commercial brain training games in young adults have little scientific basis. Here we investigated the impact of the brain training game (Brain Age) on a wide range of cognitive functions in young adults. Methods We conducted a double-blind (de facto masking) randomized controlled trial using a popular brain training game (Brain Age) and a popular puzzle game (Tetris). Thirty-two volunteers were recruited through an advertisement in the local newspaper and randomly assigned to either of two game groups (Brain Age, Tetris). Participants in both the Brain Age and the Tetris groups played their game for about 15 minutes per day, at least 5 days per week, for 4 weeks. Measures of the cognitive functions were conducted before and after training. Measures of the cognitive functions fell into eight categories (fluid intelligence, executive function, working memory, short-term memory, attention, processing speed, visual ability, and reading ability). Results and Discussion Our results showed that commercial brain training game improves executive functions, working memory, and processing speed in young adults. Moreover, the popular puzzle game can engender improvement attention and visuo-spatial ability compared to playing the brain training game. The present study showed the scientific evidence which the brain training game had the beneficial effects on cognitive functions (executive functions, working memory and processing speed) in the healthy young adults. Conclusions Our results do not indicate that everyone should play brain training games. However, the commercial brain training game might be a simple and convenient means to improve some cognitive functions. We believe that our findings are highly relevant to applications in educational and clinical fields. Trial Registration UMIN Clinical Trial Registry 000005618. PMID:23405164

An implementation of the SNR high speed network communication protocol (Receiver part)

NASA Astrophysics Data System (ADS)

Wan, Wen-Jyh

1995-03-01

This thesis work is to implement the receiver pan of the SNR high speed network transport protocol. The approach was to use the Systems of Communicating Machines (SCM) as the formal definition of the protocol. Programs were developed on top of the Unix system using C programming language. The Unix system features that were adopted for this implementation were multitasking, signals, shared memory, semaphores, sockets, timers and process control. The problems encountered, and solved, were signal loss, shared memory conflicts, process synchronization, scheduling, data alignment and errors in the SCM specification itself. The result was a correctly functioning program which implemented the SNR protocol. The system was tested using different connection modes, lost packets, duplicate packets and large data transfers. The contributions of this thesis are: (1) implementation of the receiver part of the SNR high speed transport protocol; (2) testing and integration with the transmitter part of the SNR transport protocol on an FDDI data link layered network; (3) demonstration of the functions of the SNR transport protocol such as connection management, sequenced delivery, flow control and error recovery using selective repeat methods of retransmission; and (4) modifications to the SNR transport protocol specification such as corrections for incorrect predicate conditions, defining of additional packet types formats, solutions for signal lost and processes contention problems etc.

Cognitive function and unsafe driving acts during an on-road test among community-dwelling older adults with cognitive impairments.

PubMed

Hotta, Ryo; Makizako, Hyuma; Doi, Takehiko; Tsutsumimoto, Kota; Nakakubo, Sho; Makino, Keitaro; Shimada, Hiroyuki

2018-02-19

To examine the relationship between cognitive function and unsafe driving acts among community-dwelling older adults with cognitive impairments. Participants (n = 160) were older residents of Obu, Japan, aged ≥65 years with cognitive impairments. They regularly drove and were assessed for the number of unsafe driving acts without adequate verification during an on-road test. We also evaluated cognitive function (attention, executive function and processing speed). Other examined variables included demographics, driving characteristics and visual condition. Participants were classified into two groups according to the number of unsafe driving acts as follows: high group (≥4 unsafe driving acts) and low group (≤3 unsafe driving acts). The high group participants were older in age (P < 0.001) and obtained a lower score on the symbol digit substitution task (P = 0.002) than the low group. The number of unsafe driving acts showed modest significant positive correlations with age (r = 0.396, P < 0.001). The symbol digit substitution task score was significantly associated with the number of unsafe driving acts (β = -0.196, P < 0.05) after adjusting for age group. Processing speed was associated with unsafe driving acts that became worse with increasing age. Future study will be required to longitudinally examine the influence of processing speed on traffic accidents for those with cognitive impairments. Geriatr Gerontol Int 2018; ••: ••-••. © 2018 Japan Geriatrics Society.

Cost-effective data storage/archival subsystem for functional PACS

NASA Astrophysics Data System (ADS)

Chen, Y. P.; Kim, Yongmin

1993-09-01

Not the least of the requirements of a workable PACS is the ability to store and archive vast amounts of information. A medium-size hospital will generate between 1 and 2 TBytes of data annually on a fully functional PACS. A high-speed image transmission network coupled with a comparably high-speed central data storage unit can make local memory and magnetic disks in the PACS workstations less critical and, in an extreme case, unnecessary. Under these circumstances, the capacity and performance of the central data storage subsystem and database is critical in determining the response time at the workstations, thus significantly affecting clinical acceptability. The central data storage subsystem not only needs to provide sufficient capacity to store about ten days worth of images (five days worth of new studies, and on the average, about one comparison study for each new study), but also supplies images to the requesting workstation in a timely fashion. The database must provide fast retrieval responses upon users' requests for images. This paper analyzes both advantages and disadvantages of multiple parallel transfer disks versus RAID disks for short-term central data storage subsystem, as well as optical disk jukebox versus digital recorder tape subsystem for long-term archive. Furthermore, an example high-performance cost-effective storage subsystem which integrates both the RAID disks and high-speed digital tape subsystem as a cost-effective PACS data storage/archival unit are presented.

Power-efficient dual-rate optical transceiver.

PubMed

Zuo, Yongrong; Kiamiley, Fouad E; Wang, Xiaoqing; Gui, Ping; Ekman, Jeremy; Wang, Xingle; McFadden, Michael J; Haney, Michael W

2005-11-20

A dual-rate (2 Gbit/s and 100 Mbit/s) optical transceiver designed for power-efficient connections within and between modern high-speed digital systems is described. The transceiver can dynamically adjust its data rate according to performance requirements, allowing for power-on-demand operation. Dynamic power management permits energy saving and lowers device operating temperatures, improving the reliability and lifetime of optoelectronic-devices such as vertical-cavity surface-emitting lasers (VCSELs). To implement dual-rate functionality, we include in the transmitter and receiver circuits separate high-speed and low-power data path modules. The high-speed module is designed for gigabit operation to achieve high bandwidth. A simpler low-power module is designed for megabit data transmission with low power consumption. The transceiver is fabricated in a 0.5 microm silicon-on-sapphire complementary metal-oxide semiconductor. The VCSEL and photodetector devices are attached to the transceiver's integrated circuit by flip-chip bonding. A free-space optical link system is constructed to demonstrate correct dual-rate functionality. Experimental results show reliable link operation at 2 Gbit/s and 100 Mbit/s data transfer rates with approximately 104 and approximately 9 mW power consumption, respectively. The transceiver's switching time between these two data rates is demonstrated as 10 micros, which is limited by on-chip register reconfiguration time. Improvement of this switching time can be obtained by use of dedicated input-output pads for dual-rate control signals.

Displacement monitoring of switch track and its slab on a bridge of high speed railway by FBG

NASA Astrophysics Data System (ADS)

Li, Weilai; Li, He; Cheng, Jian; Huang, Xiaomei; Pan, Jianjun; Zhou, Ciming; Yang, Minghong

2011-05-01

In a 350km/h high speed railway line, there is a seamless switch with ballastless slabs built on a bridge. 54 Fiber Bragg Grating detecting cells are employed to monitor the displacement of track and slab. The cell is of extending function of measurement range, up to 50mm displacement, and is of good linearity. Protecting methods for cells and fiber are adopted to keep them surviving from the harsh conditions. The results show that in 75 days, the displacement of the track and sleeper slab was 8-9mm, and the displacement is of high correlation with daily environmental temperature change.

Stars with relativistic speeds in the Hills scenario

NASA Astrophysics Data System (ADS)

Dremova, G. N.; Dremov, V. V.; Tutukov, A. V.

2017-07-01

The dynamical capture of a binary system consisting of a supermassive black hole (SMBH) and an ordinary star in the gravitational field of a central (more massive) SMBH is considered in the three-body problem in the framework of a modified Hills scenario. The results of numerical simulations predict the existence of objects whose spatial speeds are comparable to the speed of light. The conditions for and constraints imposed on the ejection speeds realized in a classical scenario and the modified Hills scenario are analyzed. The star is modeled using an N-body approach, making it possible to treat it as a structured object, enabling estimation of the probability that the object survives when it is ejected with relativistic speed as a function of the mass of the star, the masses of both SMBHs, and the pericenter distance. It is possible that the modern kinematic classification for stars with anomalously high spatial velocities will be augmented with a new class—stars with relativistic speeds.

Use of the Azimuth Wavelength Cut-Off to Retrieve the Sea Surface Wind Speed from Sentinel 1 and COSMO-SkyMed SAR Data

NASA Astrophysics Data System (ADS)

Grieco, G.; Nirchio, F.; Montuori, A.; Migliaccio, M.; Lin, W.; Portabella, M.

2016-08-01

The dependency of the azimuth wavelength cut-off on the wind speed has been studied through a dataset of Sentinel-1 multi look SAR images co-located with wind speed measurements, significant wave height and mean wave direction from ECMWF operational output.A Geophysical Model Function (GMF) has been fitted and a retrieval exercise has been done comparing the results to a set of independent wind speed scatterometer measurements of the Chinese mission HY-2A. The preliminary results show that the dependency of the azimuth cut-off on the wind speed is linear only for fully developed sea states and that the agreement between the retrieved values and the measurements is good especially for high wind speed.A similar approach has been used to assess the dependency of the azimuth cut-off also for X-band COSMO-SkyMed data. The dataset is still incomplete but the preliminary results show a similar trend.

High wind speeds prevent formation of a distinct bacterioneuston community in the sea-surface microlayer

PubMed Central

Stolle, Christian; Giebel, Helge-Ansgar; Brinkhoff, Thorsten; Ribas-Ribas, Mariana; Hodapp, Dorothee; Wurl, Oliver

2017-01-01

Abstract The sea-surface microlayer (SML) at the boundary between atmosphere and hydrosphere represents a demanding habitat for bacteria. Wind speed is a crucial but poorly studied factor for its physical integrity. Increasing atmospheric burden of CO2, as suggested for future climate scenarios, may particularly act on this habitat at the air–sea interface. We investigated the effect of increasing wind speeds and different pCO2 levels on SML microbial communities in a wind-wave tunnel, which offered the advantage of low spatial and temporal variability. We found that enrichment of bacteria in the SML occurred solely at a U10 wind speed of ≤5.6 m s−1 in the tunnel and ≤4.1 m s−1 in the Baltic Sea. High pCO2 levels further intensified the bacterial enrichment in the SML during low wind speed. In addition, low wind speed and pCO2 induced the formation of a distinctive bacterial community as revealed by 16S rRNA gene fingerprints and influenced the presence or absence of individual taxonomic units within the SML. We conclude that physical stability of the SML below a system-specific wind speed threshold induces specific bacterial communities in the SML entailing strong implications for ecosystem functioning by wind-driven impacts on habitat properties, gas exchange and matter cycling processes. PMID:28369320

High wind speeds prevent formation of a distinct bacterioneuston community in the sea-surface microlayer.

PubMed

Rahlff, Janina; Stolle, Christian; Giebel, Helge-Ansgar; Brinkhoff, Thorsten; Ribas-Ribas, Mariana; Hodapp, Dorothee; Wurl, Oliver

2017-05-01

The sea-surface microlayer (SML) at the boundary between atmosphere and hydrosphere represents a demanding habitat for bacteria. Wind speed is a crucial but poorly studied factor for its physical integrity. Increasing atmospheric burden of CO2, as suggested for future climate scenarios, may particularly act on this habitat at the air-sea interface. We investigated the effect of increasing wind speeds and different pCO2 levels on SML microbial communities in a wind-wave tunnel, which offered the advantage of low spatial and temporal variability. We found that enrichment of bacteria in the SML occurred solely at a U10 wind speed of ≤5.6 m s-1 in the tunnel and ≤4.1 m s-1 in the Baltic Sea. High pCO2 levels further intensified the bacterial enrichment in the SML during low wind speed. In addition, low wind speed and pCO2 induced the formation of a distinctive bacterial community as revealed by 16S rRNA gene fingerprints and influenced the presence or absence of individual taxonomic units within the SML. We conclude that physical stability of the SML below a system-specific wind speed threshold induces specific bacterial communities in the SML entailing strong implications for ecosystem functioning by wind-driven impacts on habitat properties, gas exchange and matter cycling processes. © FEMS 2017.

High-speed photoacoustic imaging using an LED-based photoacoustic imaging system

NASA Astrophysics Data System (ADS)

Sato, Naoto; Kuniyil Ajith Singh, Mithun; Shigeta, Yusuke; Hanaoka, Takamitsu; Agano, Toshitaka

2018-02-01

Recently we developed a multispectral LED-based photoacoustic/ultrasound imaging system (AcousticX) and have been continuously working on its technical/functional improvements. AcousticX is a linear array ultrasound transducer (128 elements, 10 MHz)-based system in which LED arrays (selectable wavelengths, pulse repetition frequency: 4 kHz, pulse width: tunable from 40 - 100 ns) are fixed on both sides of the transducer to illuminate the tissue for photoacoustic imaging. The ultrasound/photoacoustic data from all 128 elements can be simultaneously acquired, processed and displayed. We already demonstrated our system's capability to perform photoacoustic/ultrasound imaging for dynamic imaging of the tissue at a frame rate of 10 Hz (for example to visualize the pulsation of arteries in vivo in human subjects). In this work, we present the development of a new high-speed imaging mode in AcousticX. In this mode, instead of toggling between ultrasound and photoacoustic measurements, it is possible to continuously acquire only photoacoustic data for 1.5 seconds with a time interval of 1 ms. With this improvement, we can record photoacoustic signals from the whole aperture (38 mm) at fast rate and can be reviewed later at different speeds for analyzing dynamic changes in the photoacoustic signals. We believe that AcousticX with this new high-speed mode opens up a feasible technical path for multiple dynamic studies, for example one which focus on imaging the response of voltage sensitive dyes. We envisage to improve the acquisition speed further in future for exploring ultra-high-speed applications.

A Study on the Effects of Alternatives to Speed Humps Using a Driving Simulator

NASA Astrophysics Data System (ADS)

Kim, Jong-Min; Noh, Kwan-Sub

A road alignment which has a long straight section followed by sharp curve is dangerous, because drivers have the habit to accelerate on the long straight section and then accidents occur on the short curve as the result of speeding. This study evaluated the alternatives to speed humps in order to reduce speed safely and comfortably on roads with this incorrect road alignment. There are several speed control facilities to reduce speed on roads with wrong road alignment. The speed hump is dangerous at high speeds because drivers must reduce speed rapidly and because of the physical impact. The image hump provides less effect for drivers who already know of its presence. So, to resolve these matters, we propose a new type of speed control facility. An image hump with transverse grooving will be effective in reducing speed because the transverse grooving gives vibration and noise to drivers who are already aware of the presence of the image hump, but it does not give the hard physical impact to vehicles. The study on the effect of the alternatives to speed humps was carried out using the K-ROADS (KICT-Road Analysis Driving Simulator) which has been developed to analyze and evaluate road safety at the project HuRoSAS (Human & Road Safety Analysis System) since 2003. K-ROADS has two distinct functions. One is the visual system which has a 360 degree F. O. V. to reduce dead angles on black spots such as at-grade intersections. The other is the motion system which has high frequency vibration to reproduce vibrations made in irregular road surfaces. This study found out that the image hump with transverse grooving is a safe speed control facility in order to reduce driving speed safely and comfortably on a straight section followed by a sharp curve, even if drivers are known the existence of image hump.

High speed high dynamic range high accuracy measurement system

DOEpatents

Deibele, Craig E.; Curry, Douglas E.; Dickson, Richard W.; Xie, Zaipeng

2016-11-29

A measuring system includes an input that emulates a bandpass filter with no signal reflections. A directional coupler connected to the input passes the filtered input to electrically isolated measuring circuits. Each of the measuring circuits includes an amplifier that amplifies the signal through logarithmic functions. The output of the measuring system is an accurate high dynamic range measurement.

75 FR 28465 - Airworthiness Directives; Dassault-Aviation Model FALCON 2000 and FALCON 2000EX Airplanes

Federal Register 2010, 2011, 2012, 2013, 2014

2010-05-21

... function of the shock absorber is lost and high loads may be transmitted to the aircraft structure during... domain particularly in combination of high landing weight and high vertical speed. Failure of the..., and broken or loose screws] and, if necessary, repair of the shock absorber per Dassault Aviation...

Light sheet theta microscopy for rapid high-resolution imaging of large biological samples.

PubMed

Migliori, Bianca; Datta, Malika S; Dupre, Christophe; Apak, Mehmet C; Asano, Shoh; Gao, Ruixuan; Boyden, Edward S; Hermanson, Ola; Yuste, Rafael; Tomer, Raju

2018-05-29

Advances in tissue clearing and molecular labeling methods are enabling unprecedented optical access to large intact biological systems. These developments fuel the need for high-speed microscopy approaches to image large samples quantitatively and at high resolution. While light sheet microscopy (LSM), with its high planar imaging speed and low photo-bleaching, can be effective, scaling up to larger imaging volumes has been hindered by the use of orthogonal light sheet illumination. To address this fundamental limitation, we have developed light sheet theta microscopy (LSTM), which uniformly illuminates samples from the same side as the detection objective, thereby eliminating limits on lateral dimensions without sacrificing the imaging resolution, depth, and speed. We present a detailed characterization of LSTM, and demonstrate its complementary advantages over LSM for rapid high-resolution quantitative imaging of large intact samples with high uniform quality. The reported LSTM approach is a significant step for the rapid high-resolution quantitative mapping of the structure and function of very large biological systems, such as a clarified thick coronal slab of human brain and uniformly expanded tissues, and also for rapid volumetric calcium imaging of highly motile animals, such as Hydra, undergoing non-isomorphic body shape changes.

High frequency signal acquisition and control system based on DSP+FPGA

NASA Astrophysics Data System (ADS)

Liu, Xiao-qi; Zhang, Da-zhi; Yin, Ya-dong

2017-10-01

This paper introduces a design and implementation of high frequency signal acquisition and control system based on DSP + FPGA. The system supports internal/external clock and internal/external trigger sampling. It has a maximum sampling rate of 400MBPS and has a 1.4GHz input bandwidth for the ADC. Data can be collected continuously or periodically in systems and they are stored in DDR2. At the same time, the system also supports real-time acquisition, the collected data after digital frequency conversion and Cascaded Integrator-Comb (CIC) filtering, which then be sent to the CPCI bus through the high-speed DSP, can be assigned to the fiber board for subsequent processing. The system integrates signal acquisition and pre-processing functions, which uses high-speed A/D, high-speed DSP and FPGA mixed technology and has a wide range of uses in data acquisition and recording. In the signal processing, the system can be seamlessly connected to the dedicated processor board. The system has the advantages of multi-selectivity, good scalability and so on, which satisfies the different requirements of different signals in different projects.

Profile parameters of wheelset detection for high speed freight train

NASA Astrophysics Data System (ADS)

Yang, Kai; Ma, Li; Gao, Xiaorong; Wang, Li

2012-04-01

Because of freight train, in China, transports goods on railway freight line throughout the country, it does not depart from or return to engine shed during a long phase, thus we cannot monitor the quality of wheel set effectively. This paper provides a system which uses leaser and high speed camera, applies no-contact light section technology to get precise wheel set profile parameters. The paper employs clamping-track method to avoid complex railway ballast modification project. And detailed descript an improved image-tracking algorithm to extract central line from profile curve. For getting one pixel width and continuous line of the profile curve, uses local gray maximum points as direction control points to direct tracking direction. The results based on practical experiment show the system adapted to detection environment of high speed and high vibration, and it can effectively detect the wheelset geometric parameters with high accuracy. The system fills the gaps in wheel set detection for freight train in main line and has an enlightening function on monitoring the quality of wheel set.

Fixed-speed and Variable-speed Pumped Storage Dispatch Model in Power Systems with High Renewable Penetration

NASA Astrophysics Data System (ADS)

Yuan, Bo; Zong, Jin; Xu, Zhicheng

2018-06-01

According to different operating characteristics of pumped storage fixed speed unit and variable speed unit, a joint dispatching model of pumped storage unit and other types of units based on mixed integer linear optimization is constructed. The model takes into account the operating conditions, reservoir capacity, cycle type and other pumped storage unit constraints, but also consider the frequent start and stop and the stability of the operation of the unit caused by the loss. Using the Cplex solver to solve the model, the empirical example of the provincial power grid shows that the model can effectively arrange the pumping storage speed and the dispatching operation of the variable speed unit under the precondition of economic life of the unit, and give full play to the function of peak shaving and accommodating new energy. Because of its more flexible regulation characteristics of power generation and pumping conditions, the variable speed unit can better improve the operating conditions of other units in the system and promote the new energy dissipation.

Speed of recovery after arthroscopic rotator cuff repair.

PubMed

Kurowicki, Jennifer; Berglund, Derek D; Momoh, Enesi; Disla, Shanell; Horn, Brandon; Giveans, M Russell; Levy, Jonathan C

2017-07-01

The purpose of this study was to delineate the time taken to achieve maximum improvement (plateau of recovery) and the degree of recovery observed at various time points (speed of recovery) for pain and function after arthroscopic rotator cuff repair. An institutional shoulder surgery registry query identified 627 patients who underwent arthroscopic rotator cuff repair between 2006 and 2015. Measured range of motion, patient satisfaction, and patient-reported outcome measures were analyzed for preoperative, 3-month, 6-month, 1-year, and 2-year intervals. Subgroup analysis was performed on the basis of tear size by retraction grade and number of anchors used. As an entire group, the plateau of maximum recovery for pain, function, and motion occurred at 1 year. Satisfaction with surgery was >96% at all time points. At 3 months, 74% of improvement in pain and 45% to 58% of functional improvement were realized. However, only 22% of elevation improvement was achieved (P < .001). At 6 months, 89% of improvement in pain, 81% to 88% of functional improvement, and 78% of elevation improvement were achieved (P < .001). Larger tears had a slower speed of recovery for Single Assessment Numeric Evaluation scores, forward elevation, and external rotation. Smaller tears had higher motion and functional scores across all time points. Tear size did not influence pain levels. The plateau of maximum recovery after rotator cuff repair occurred at 1 year with high satisfaction rates at all time points. At 3 months, approximately 75% of pain relief and 50% of functional recovery can be expected. Larger tears have a slower speed of recovery. Copyright © 2016 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.

Interindividual variation in thermal sensitivity of maximal sprint speed, thermal behavior, and resting metabolic rate in a lizard.

PubMed

Artacho, Paulina; Jouanneau, Isabelle; Le Galliard, Jean-François

2013-01-01

Studies of the relationship of performance and behavioral traits with environmental factors have tended to neglect interindividual variation even though quantification of this variation is fundamental to understanding how phenotypic traits can evolve. In ectotherms, functional integration of locomotor performance, thermal behavior, and energy metabolism is of special interest because of the potential for coadaptation among these traits. For this reason, we analyzed interindividual variation, covariation, and repeatability of the thermal sensitivity of maximal sprint speed, preferred body temperature, thermal precision, and resting metabolic rate measured in ca. 200 common lizards (Zootoca vivipara) that varied by sex, age, and body size. We found significant interindividual variation in selected body temperatures and in the thermal performance curve of maximal sprint speed for both the intercept (expected trait value at the average temperature) and the slope (measure of thermal sensitivity). Interindividual differences in maximal sprint speed across temperatures, preferred body temperature, and thermal precision were significantly repeatable. A positive relationship existed between preferred body temperature and thermal precision, implying that individuals selecting higher temperatures were more precise. The resting metabolic rate was highly variable but was not related to thermal sensitivity of maximal sprint speed or thermal behavior. Thus, locomotor performance, thermal behavior, and energy metabolism were not directly functionally linked in the common lizard.

Optimization of Angular-Momentum Biases of Reaction Wheels

NASA Technical Reports Server (NTRS)

Lee, Clifford; Lee, Allan

2008-01-01

RBOT [RWA Bias Optimization Tool (wherein RWA signifies Reaction Wheel Assembly )] is a computer program designed for computing angular momentum biases for reaction wheels used for providing spacecraft pointing in various directions as required for scientific observations. RBOT is currently deployed to support the Cassini mission to prevent operation of reaction wheels at unsafely high speeds while minimizing time in undesirable low-speed range, where elasto-hydrodynamic lubrication films in bearings become ineffective, leading to premature bearing failure. The problem is formulated as a constrained optimization problem in which maximum wheel speed limit is a hard constraint and a cost functional that increases as speed decreases below a low-speed threshold. The optimization problem is solved using a parametric search routine known as the Nelder-Mead simplex algorithm. To increase computational efficiency for extended operation involving large quantity of data, the algorithm is designed to (1) use large time increments during intervals when spacecraft attitudes or rates of rotation are nearly stationary, (2) use sinusoidal-approximation sampling to model repeated long periods of Earth-point rolling maneuvers to reduce computational loads, and (3) utilize an efficient equation to obtain wheel-rate profiles as functions of initial wheel biases based on conservation of angular momentum (in an inertial frame) using pre-computed terms.

Ultrahigh-speed Si-integrated on-chip laser with tailored dynamic characteristics

NASA Astrophysics Data System (ADS)

Park, Gyeong Cheol; Xue, Weiqi; Piels, Molly; Zibar, Darko; Mørk, Jesper; Semenova, Elizaveta; Chung, Il-Sug

2016-12-01

For on-chip interconnects, an ideal light source should have an ultralow energy consumption per bandwidth (operating en-ergy) as well as sufficient output power for error-free detection. Nanocavity lasers have been considered the most ideal for smaller operating energy. However, they have a challenge in obtaining a sufficient output power. Here, as an alternative, we propose an ultrahigh-speed microcavity laser structure, based on a vertical cavity with a high-contrast grating (HCG) mirror for transverse magnetic (TM) polarisation. By using the TM HCG, a very small mode volume and an un-pumped compact optical feedback structure can be realised, which together tailor the frequency response function for achieving a very high speed at low injection currents. Furthermore, light can be emitted laterally into a Si waveguide. From an 1.54-μm optically-pumped laser, a 3-dB frequency of 27 GHz was obtained at a pumping level corresponding to sub-mA. Using measured 3-dB frequen-cies and calculated equivalent currents, the modulation current efficiency factor (MCEF) is estimated to be 42.1 GHz/mA1/2, which is superior among microcavity lasers. This shows a high potential for a very high speed at low injection currents or avery small heat generation at high bitrates, which are highly desirable for both on-chip and off-chip applications.

A spherical harmonic approach for the determination of HCP texture from ultrasound: A solution to the inverse problem

NASA Astrophysics Data System (ADS)

Lan, Bo; Lowe, Michael J. S.; Dunne, Fionn P. E.

2015-10-01

A new spherical convolution approach has been presented which couples HCP single crystal wave speed (the kernel function) with polycrystal c-axis pole distribution function to give the resultant polycrystal wave speed response. The three functions have been expressed as spherical harmonic expansions thus enabling application of the de-convolution technique to enable any one of the three to be determined from knowledge of the other two. Hence, the forward problem of determination of polycrystal wave speed from knowledge of single crystal wave speed response and the polycrystal pole distribution has been solved for a broad range of experimentally representative HCP polycrystal textures. The technique provides near-perfect representation of the sensitivity of wave speed to polycrystal texture as well as quantitative prediction of polycrystal wave speed. More importantly, a solution to the inverse problem is presented in which texture, as a c-axis distribution function, is determined from knowledge of the kernel function and the polycrystal wave speed response. It has also been explained why it has been widely reported in the literature that only texture coefficients up to 4th degree may be obtained from ultrasonic measurements. Finally, the de-convolution approach presented provides the potential for the measurement of polycrystal texture from ultrasonic wave speed measurements.

An investigation of lower-extremity functional asymmetry for non-preferred able-bodied walking speeds

PubMed Central

RICE, JOHN; SEELEY, MATTHEW K.

2010-01-01

Functional asymmetry is an idea that is often used to explain documented bilateral asymmetries during able-bodied gait. Within this context, this idea suggests that the non-dominant and dominant legs, considered as whole entities, contribute asymmetrically to support and propulsion during walking. The degree of functional asymmetry may depend upon walking speed. The purpose of this study was to better understand the potential relationship between functional asymmetry and walking speed. Bilateral ground reaction forces (GRF) were measured for 20 healthy subjects who walked at nine different speeds: preferred, +10%, +20%, +30%, +40, −10%, −20%, −30%, and −40%. Contribution to support was determined to be the support impulse: the time integral of the vertical GRF during stance. Contribution to propulsion was determined to be the propulsion impulse: the time integral of the anterior-posterior GRF, while this force was directed forward. Repeated measures ANOVA (α = 0.05) revealed leg × speed interactions for normalized support (p = 0.001) and propulsion (p = 0.001) impulse, indicating that speed does affect the degree of functional asymmetry during gait. Post hoc comparisons (α = 0.05) showed that support impulse was approximately 2% greater for the dominant leg, relative to the non-dominant leg, for the −10%, −20%, and −40% speeds. Propulsion impulse was 12% greater for the dominant leg than for the non-dominant leg at the +20% speed. Speed does appear to affect the magnitude of bilateral asymmetry during walking, however, only the bilateral difference for propulsion impulse at one fast speed (+20%) was supportive of the functional asymmetry idea. PMID:27182346

Cognitive functioning in healthy aging: the role of reserve and lifestyle factors early in life.

PubMed

Fritsch, Thomas; McClendon, McKee J; Smyth, Kathleen A; Lerner, Alan J; Friedland, Robert P; Larsen, Janet D

2007-06-01

According to the reserve perspective on cognitive aging, individuals are born with or can develop resources that help them resist normal and disease-related cognitive changes that occur in aging. The reserve perspective is becoming more sophisticated, but gaps in knowledge persist. In the present research, we considered three understudied questions about reserve: Is reserve primarily static (unchangeable) throughout the life course or dynamic (changeable, in terms of increases or decreases)? Can reserve be increased at any point in life, or are there optimal time periods--such as early life, midlife, or late life--to increase it? Does participation in different types of leisure and occupational activities in early life and midlife have different effects depending on specific domains of late-life cognitive functioning? Here we link early cognitive and activity data--gathered from archival sources--with cognitive data from older adults to examine these issues. 349 participants, all mid-1940s graduates of the same high school, underwent telephone cognitive screening. All participants provided access to adolescent IQ scores; we determined activity levels from yearbooks. We used path analysis to evaluate the complex relationships between early life, midlife, and late-life variables. Adolescent IQ had strong direct effects on global cognitive functioning, episodic memory, verbal fluency, and processing speed. Participants' high school mental activities had direct effects on verbal fluency, but physical and social activities did not predict any cognitive measure. Education had direct effects on global cognitive functioning, episodic memory, and, most strongly, processing speed, but other midlife factors (notably, occupational demands) were not significant predictors of late-life cognition. There were weak indirect effects of adolescent IQ on global cognitive functioning, episodic memory, and processing speed, working through high school mental activities and education. Verbal fluency, in contrast, was affected by adolescent IQ through links with high school mental activities, but not education. Our study suggests that reserve is dynamic, but it is most amenable to change in early life. We conclude that an active, engaged lifestyle, emphasizing mental activity and educational pursuits in early life, can have a positive impact on cognitive functioning in late life.

Linking molecular level chemistry to macroscopic combustion behavior for nano-energetic materials with halogen containing oxides.

PubMed

Farley, Cory W; Pantoya, Michelle L; Losada, Martin; Chaudhuri, Santanu

2013-08-21

Coupling molecular scale reaction kinetics with macroscopic combustion behavior is critical to understanding the influences of intermediate chemistry on energy propagation, yet bridging this multi-scale gap is challenging. This study integrates ab initio quantum chemical calculations and condensed phase density functional theory to elucidate factors contributing to experimentally measured high flame speeds (i.e., >900 m∕s) associated with halogen based energetic composites, such as aluminum (Al) and iodine pentoxide (I2O5). Experiments show a direct correlation between apparent activation energy and flame speed suggesting that flame speed is directly influenced by chemical kinetics. Toward this end, the first principle simulations resolve key exothermic surface and intermediate chemistries contributing toward the kinetics that promote high flame speeds. Linking molecular level exothermicity to macroscopic experimental investigations provides insight into the unique role of the alumina oxide shell passivating aluminum particles. In the case of Al reacting with I2O5, the alumina shell promotes exothermic surface chemistries that reduce activation energy and increase flame speed. This finding is in contrast to Al reaction with metal oxides that show the alumina shell does not participate exothermically in the reaction.

Experimental study of sound propagation in a flexible duct

PubMed

Huang; Choy; So; Chong

2000-08-01

Propagation of sound in a flexible duct is investigated both theoretically and experimentally. Strong coupling of sound and flexural waves on the duct wall is found when the wall-to-air mass ratio is of the order of unity. The axial phase speed of sound approaches the in vacuo speed of flexural waves (subsonic in this case) at low frequencies. However, a speed higher than the isentropic sound speed in free space (340 m/s) is found beyond a critical frequency which is a function of the mass ratio. Experiments using a duct with a finite section of tensioned membrane are compared with the propagating modes pertaining to the infinite membrane model. Satisfactory quantitative agreement is obtained and the measured phase speed ranges from 8.3 to 1348 m/s. In the moderate frequency range, the theory predicts high spatial damping rate for the subsonic waves, which is consistent with the experimental observation that subsonic waves become increasingly undetectable as the frequency increases. Substantial sound reflection is observed at the interface between the rigid and the flexible segments of the duct without cross-section discontinuity, which, together with the high spatial damping, could form a basis for passive control of low-frequency duct noise.

Highball: A high speed, reserved-access, wide area network

NASA Technical Reports Server (NTRS)

Mills, David L.; Boncelet, Charles G.; Elias, John G.; Schragger, Paul A.; Jackson, Alden W.

1990-01-01

A network architecture called Highball and a preliminary design for a prototype, wide-area data network designed to operate at speeds of 1 Gbps and beyond are described. It is intended for applications requiring high speed burst transmissions where some latency between requesting a transmission and granting the request can be anticipated and tolerated. Examples include real-time video and disk-disk transfers, national filestore access, remote sensing, and similar applications. The network nodes include an intelligent crossbar switch, but have no buffering capabilities; thus, data must be queued at the end nodes. There are no restrictions on the network topology, link speeds, or end-end protocols. The end system, nodes, and links can operate at any speed up to the limits imposed by the physical facilities. An overview of an initial design approach is presented and is intended as a benchmark upon which a detailed design can be developed. It describes the network architecture and proposed access protocols, as well as functional descriptions of the hardware and software components that could be used in a prototype implementation. It concludes with a discussion of additional issues to be resolved in continuing stages of this project.

Attention, processing speed, and executive functioning in pediatric brain tumor survivors treated with proton beam radiation therapy.

PubMed

Antonini, Tanya N; Ris, M Douglas; Grosshans, David R; Mahajan, Anita; Okcu, M Fatih; Chintagumpala, Murali; Paulino, Arnold; Child, Amanda E; Orobio, Jessica; Stancel, Heather H; Kahalley, Lisa S

2017-07-01

This study examines attention, processing speed, and executive functioning in pediatric brain tumor survivors treated with proton beam radiation therapy (PBRT). We examined 39 survivors (age 6-19years) who were 3.61years post-PBRT on average. Craniospinal (CSI; n=21) and focal (n=18) subgroups were analyzed. Attention, processing speed, and executive functioning scores were compared to population norms, and clinical/demographic risk factors were examined. As a group, survivors treated with focal PBRT exhibited attention, processing speed, and executive functioning that did not differ from population norms (all p>0.05). Performance in the CSI group across attention scales was normative (all p>0.05), but areas of relative weakness were identified on one executive functioning subtest and several processing speed subtests (all p<0.01). Survivors treated with PBRT may exhibit relative resilience in cognitive domains traditionally associated with radiation late effects. Attention, processing speed, and executive functioning remained intact and within normal limits for survivors treated with focal PBRT. Among survivors treated with CSI, a score pattern emerged that was suggestive of difficulties in underlying component skills (i.e., processing speed) rather than true executive dysfunction. No evidence of profound cognitive impairment was found in either group. Copyright © 2017 Elsevier B.V. All rights reserved.

Verbal Processing Speed and Executive Functioning in Long-Term Cochlear Implant Users

ERIC Educational Resources Information Center

AuBuchon, Angela M.; Pisoni, David B.; Kronenberger, William G.

2015-01-01

Purpose: The purpose of this study was to report how "verbal rehearsal speed" (VRS), a form of covert speech used to maintain verbal information in working memory, and another verbal processing speed measure, perceptual encoding speed, are related to 3 domains of executive function (EF) at risk in cochlear implant (CI) users: verbal…

Rapid and label-free microfluidic neutrophil purification and phenotyping in diabetes mellitus

NASA Astrophysics Data System (ADS)

Hou, Han Wei; Petchakup, Chayakorn; Tay, Hui Min; Tam, Zhi Yang; Dalan, Rinkoo; Chew, Daniel Ek Kwang; Li, King Ho Holden; Boehm, Bernhard O.

2016-07-01

Advanced management of dysmetabolic syndromes such as diabetes will benefit from a timely mechanistic insight enabling personalized medicine approaches. Herein, we present a rapid microfluidic neutrophil sorting and functional phenotyping strategy for type 2 diabetes mellitus (T2DM) patients using small blood volumes (fingerprick ~100 μL). The developed inertial microfluidics technology enables single-step neutrophil isolation (>90% purity) without immuno-labeling and sorted neutrophils are used to characterize their rolling behavior on E-selectin, a critical step in leukocyte recruitment during inflammation. The integrated microfluidics testing methodology facilitates high throughput single-cell quantification of neutrophil rolling to detect subtle differences in speed distribution. Higher rolling speed was observed in T2DM patients (P < 0.01) which strongly correlated with neutrophil activation, rolling ligand P-selectin glycoprotein ligand 1 (PSGL-1) expression, as well as established cardiovascular risk factors (cholesterol, high-sensitive C-reactive protein (CRP) and HbA1c). Rolling phenotype can be modulated by common disease risk modifiers (metformin and pravastatin). Receiver operating characteristics (ROC) and principal component analysis (PCA) revealed neutrophil rolling as an important functional phenotype in T2DM diagnostics. These results suggest a new point-of-care testing methodology, and neutrophil rolling speed as a functional biomarker for rapid profiling of dysmetabolic subjects in clinical and patient-oriented settings.

Changes in apparent duration follow shifts in perceptual timing

PubMed Central

Bruno, Aurelio; Ayhan, Inci; Johnston, Alan

2015-01-01

It is well established that the apparent duration of moving visual objects is greater at higher as compared to slower speeds. Here we report the effects of acceleration and deceleration on the perceived duration of a drifting grating with average speed kept constant (10°/s).For acceleration, increasing the speed range progressively reduced perceived duration. The magnitude of apparent duration compression was determined by speed rather than temporal frequency and was proportional to speed range (independent of standard duration) rather than acceleration. The perceived duration reduction was also proportional to the standard length. The effects of increases and decreases in speed were highly asymmetric. Reducing speed through the interval induced a moderate increase in perceived duration. These results could not be explained by changes in apparent onset or offset or differences in perceived average speed between intervals containing increasing speed and intervals containing decreasing speed. Paradoxically, for intervals combining increasing speed and decreasing speed, compression only occurred when increasing speed occurred in the second half of the interval. We show that this pattern of results in the duration domain was concomitant with changes in the reported direction of apparent motion of Gaussian blobs, embedded in intervals of increasing or decreasing speed, that could be predicted from adaptive changes in the temporal impulse response function. We detected similar changes after flicker adaptation, suggesting that the two effects might be linked through changes in the temporal tuning of visual filters. PMID:26024450

Integrated diversification of locomotion and feeding in labrid fishes.

PubMed

Collar, David C; Wainwright, Peter C; Alfaro, Michael E

2008-02-23

An organism's performance of any ecological task involves coordination of multiple functional systems. Feeding performance is influenced by locomotor abilities which are used during search and capture of prey, as well as cranial mechanics, which affect prey capture and processing. But, does this integration of functional systems manifest itself during evolution? We asked whether the locomotor and feeding systems evolved in association in one of the most prominent and diverse reef fish radiations, the Labridae. We examined features of the pectoral fins that affect swimming performance and aspects of the skull that describe force and motion of the jaws. We applied a recent phylogeny, calculated independent contrasts for 60 nodes and performed principal components analyses separately on contrasts for fin and skull traits. The major axes of fin and skull diversification are highly correlated; modifications of the skull to amplify the speed of jaw movements are correlated with changes in the pectoral fins that increase swimming speed, and increases in force capacity of the skull are associated with changes towards fins that produce high thrust at slow speeds. These results indicate that the labrid radiation involved a strong connection between locomotion and feeding abilities.

Hydraulic hydrogel actuators and robots optically and sonically camouflaged in water

PubMed Central

Yuk, Hyunwoo; Lin, Shaoting; Ma, Chu; Takaffoli, Mahdi; Fang, Nicolas X.; Zhao, Xuanhe

2017-01-01

Sea animals such as leptocephali develop tissues and organs composed of active transparent hydrogels to achieve agile motions and natural camouflage in water. Hydrogel-based actuators that can imitate the capabilities of leptocephali will enable new applications in diverse fields. However, existing hydrogel actuators, mostly osmotic-driven, are intrinsically low-speed and/or low-force; and their camouflage capabilities have not been explored. Here we show that hydraulic actuations of hydrogels with designed structures and properties can give soft actuators and robots that are high-speed, high-force, and optically and sonically camouflaged in water. The hydrogel actuators and robots can maintain their robustness and functionality over multiple cycles of actuations, owing to the anti-fatigue property of the hydrogel under moderate stresses. We further demonstrate that the agile and transparent hydrogel actuators and robots perform extraordinary functions including swimming, kicking rubber-balls and even catching a live fish in water. PMID:28145412

Modified complementary ensemble empirical mode decomposition and intrinsic mode functions evaluation index for high-speed train gearbox fault diagnosis

NASA Astrophysics Data System (ADS)

Chen, Dongyue; Lin, Jianhui; Li, Yanping

2018-06-01

Complementary ensemble empirical mode decomposition (CEEMD) has been developed for the mode-mixing problem in Empirical Mode Decomposition (EMD) method. Compared to the ensemble empirical mode decomposition (EEMD), the CEEMD method reduces residue noise in the signal reconstruction. Both CEEMD and EEMD need enough ensemble number to reduce the residue noise, and hence it would be too much computation cost. Moreover, the selection of intrinsic mode functions (IMFs) for further analysis usually depends on experience. A modified CEEMD method and IMFs evaluation index are proposed with the aim of reducing the computational cost and select IMFs automatically. A simulated signal and in-service high-speed train gearbox vibration signals are employed to validate the proposed method in this paper. The results demonstrate that the modified CEEMD can decompose the signal efficiently with less computation cost, and the IMFs evaluation index can select the meaningful IMFs automatically.

Intermediate photovoltaic system application experiment operational performance report. Volume 6: Beverly High School, Beverly, Mass.

NASA Astrophysics Data System (ADS)

1982-03-01

Performance data are given for the month of February, 1982 for a photovoltaic power supply at a Massachusetts high school. Data given include: monthly and daily electrical energy yield; monthly and daily insolation; monthly and daily array efficiency; energy production as a function of power level, voltage, cell temperature, and hour of day; insolation as a function of hour of the day; input, output and efficiency for each of two power conditioning units and for the total power conditioning system; energy supplied to the load by the photovoltaic system and by the grid; photovoltaic system efficiency; dollar value of the energy supplied by the photovoltaic system; capacity factor; daily photovoltaic energy to load; daily system availability and hours of daylight; heating and cooling degree days; hourly cell temperature, ambient temperature, wind speed, and insolation; average monthly wind speed; wind direction distribution; and daily data acquisition mode and recording interval plot.

Hydraulic hydrogel actuators and robots optically and sonically camouflaged in water.

PubMed

Yuk, Hyunwoo; Lin, Shaoting; Ma, Chu; Takaffoli, Mahdi; Fang, Nicolas X; Zhao, Xuanhe

2017-02-01

Sea animals such as leptocephali develop tissues and organs composed of active transparent hydrogels to achieve agile motions and natural camouflage in water. Hydrogel-based actuators that can imitate the capabilities of leptocephali will enable new applications in diverse fields. However, existing hydrogel actuators, mostly osmotic-driven, are intrinsically low-speed and/or low-force; and their camouflage capabilities have not been explored. Here we show that hydraulic actuations of hydrogels with designed structures and properties can give soft actuators and robots that are high-speed, high-force, and optically and sonically camouflaged in water. The hydrogel actuators and robots can maintain their robustness and functionality over multiple cycles of actuations, owing to the anti-fatigue property of the hydrogel under moderate stresses. We further demonstrate that the agile and transparent hydrogel actuators and robots perform extraordinary functions including swimming, kicking rubber-balls and even catching a live fish in water.

Hydraulic hydrogel actuators and robots optically and sonically camouflaged in water

NASA Astrophysics Data System (ADS)

Yuk, Hyunwoo; Lin, Shaoting; Ma, Chu; Takaffoli, Mahdi; Fang, Nicolas X.; Zhao, Xuanhe

2017-02-01

Sea animals such as leptocephali develop tissues and organs composed of active transparent hydrogels to achieve agile motions and natural camouflage in water. Hydrogel-based actuators that can imitate the capabilities of leptocephali will enable new applications in diverse fields. However, existing hydrogel actuators, mostly osmotic-driven, are intrinsically low-speed and/or low-force; and their camouflage capabilities have not been explored. Here we show that hydraulic actuations of hydrogels with designed structures and properties can give soft actuators and robots that are high-speed, high-force, and optically and sonically camouflaged in water. The hydrogel actuators and robots can maintain their robustness and functionality over multiple cycles of actuations, owing to the anti-fatigue property of the hydrogel under moderate stresses. We further demonstrate that the agile and transparent hydrogel actuators and robots perform extraordinary functions including swimming, kicking rubber-balls and even catching a live fish in water.

[Gait speed, grip strength and self-rated health among the elderly: data from the FIBRA Campinas network, São Paulo, Brazil].

PubMed

Bez, Joelita Pessoa de Oliveira; Neri, Anita Liberalesso

2014-08-01

The article seeks to investigate patterns of performance and relationships between grip strength, gait speed and self-rated health, and investigate the relationships between them, considering the variables of gender, age and family income. This was conducted in a probabilistic sample of community-dwelling elderly aged 65 and over, members of a population study on frailty. A total of 689 elderly people without cognitive deficit suggestive of dementia underwent tests of gait speed and grip strength. Comparisons between groups were based on low, medium and high speed and strength. Self-related health was assessed using a 5-point scale. The males and the younger elderly individuals scored significantly higher on grip strength and gait speed than the female and oldest did; the richest scored higher than the poorest on grip strength and gait speed; females and men aged over 80 had weaker grip strength and lower gait speed; slow gait speed and low income arose as risk factors for a worse health evaluation. Lower muscular strength affects the self-rated assessment of health because it results in a reduction in functional capacity, especially in the presence of poverty and a lack of compensatory factors.

Galvanometer scanning technology for laser additive manufacturing

NASA Astrophysics Data System (ADS)

Luo, Xi; Li, Jin; Lucas, Mark

2017-02-01

A galvanometer laser beam scanning system is an essential element in many laser additive manufacturing (LAM) technologies including Stereolithography (SLA), Selective Laser Sintering (SLS) and Selective Laser Melting (SLM). Understanding the laser beam scanning techniques and recent innovations in this field will greatly benefit the 3D laser printing system integration and technology advance. One of the challenges to achieve high quality 3D printed parts is due to the non-uniform laser power density delivered on the materials caused by the acceleration and deceleration movements of the galvanometer at ends of the hatching and outlining patterns. One way to solve this problem is to modulate the laser power as the function of the scanning speed during the acceleration or deceleration periods. Another strategy is to maintain the constant scanning speed while accurately coordinating the laser on and off operation throughout the job. In this paper, we demonstrate the high speed, high accuracy and low drift digital scanning technology that incorporates both techniques to achieve uniform laser density with minimal additional process development. With the constant scanning speed method, the scanner not only delivers high quality and uniform results, but also a throughput increase of 23% on a typical LAM job, compared to that of the conventional control method that requires galvanometer acceleration and deceleration movements.

High speed turbulent reacting flows: DNS and LES

NASA Technical Reports Server (NTRS)

Givi, Peyman

1990-01-01

Work on understanding the mechanisms of mixing and reaction in high speed turbulent reacting flows was continued. Efforts, in particular, were concentrated on taking advantage of modern computational methods to simulate high speed turbulent flows. In doing so, two methodologies were used: large eddy simulations (LES) and direct numerical simulations (DNS). In the work related with LES the objective is to study the behavior of the probability density functions (pdfs) of scalar properties within the subgrid in reacting turbulent flows. The data base obtained by DNS for a detailed study of the pdf characteristics within the subgrid was used. Simulations are performed for flows under various initializations to include the effects of compressibility on mixing and chemical reactions. In the work related with DNS, a two-dimensional temporally developing high speed mixing layer under the influence of a second-order non-equilibrium chemical reaction of the type A + B yields products + heat was considered. Simulations were performed with different magnitudes of the convective Mach numbers and with different chemical kinetic parameters for the purpose of examining the isolated effects of the compressibility and the heat released by the chemical reactions on the structure of the layer. A full compressible code was developed and utilized, so that the coupling between mixing and chemical reactions is captured in a realistic manner.

Automated Shirt Collar Manufacturing. Volume 3. Sewing Head Control for High Speed Stitch Contour Tracking.

DTIC Science & Technology

1993-06-23

mal control scheme sums the cost function for all data points from time zero to infinity; however, the preview case sums only through the preview step...shaft speed that is generated by the monitor port on the servo amplifiers. Therefore, the zero frequency gain shown in the figure contains the gain...Delivery Order 0014 SAOORESS (City, State, and ZIP Code ) 10. SOURCE OF FUNDING NUMBERS Rom415CmrnSainPROGRAM IPROJECT TASK WORK UNITAlexandriaR VA 22304-6100

Why hospitals adopt patient engagement functionalities at different speeds? A moderated trend analysis.

PubMed

Asagbra, O Elijah; Burke, Darrell; Liang, Huigang

2018-03-01

To investigate acute care hospitals' adoption speed of patient engagement health information technology (HIT) functionalities from 2008 to 2013 and how this speed is contingent on environmental factors and hospital characteristics. Data on non-government acute care hospitals located in the United States was obtained from merging three databases: the American Hospital Association's (AHA) annual survey information technology supplement, AHA annual survey, and the Area Health Resource File (AHRF). The variables obtained from these datasets were the amount of annually adopted patient engagement HIT functionalities and environmental and organizational characteristics. Environmental factors included were uncertainty, munificence, and complexity. Hospital characteristics included size, system membership, ownership, and teaching status. A regression analysis of 4176 hospital-year observations revealed a positive trend in the adoption of HIT functionalities for patient engagement (β= 1.109, p < 0.05). Moreover, the study showed that large, system-affiliated, not-for-profit, teaching hospitals adopt patient engagement HIT functionalities at a faster speed than their counterparts. Environmental munificence and uncertainty were also associated with an accelerating speed of adoption. Environmental complexity however did not show a significant impact on the speed of adoption. From 2008 to 2013, there was a significant acceleration in the speed of adopting patient engagement HIT functionalities. Further efforts should be made to ensure proper adoption and consistent use by patients in order to reap the benefits of these IT investments. Hospitals adopted at least one HIT functionality for patient engagement per year. The adoption speed varied across hospitals, depending on both environmental and organizational factors. Copyright © 2017 Elsevier B.V. All rights reserved.

Full-field modal analysis during base motion excitation using high-speed 3D digital image correlation

NASA Astrophysics Data System (ADS)

Molina-Viedma, Ángel J.; López-Alba, Elías; Felipe-Sesé, Luis; Díaz, Francisco A.

2017-10-01

In recent years, many efforts have been made to exploit full-field measurement optical techniques for modal identification. Three-dimensional digital image correlation using high-speed cameras has been extensively employed for this purpose. Modal identification algorithms are applied to process the frequency response functions (FRF), which relate the displacement response of the structure to the excitation force. However, one of the most common tests for modal analysis involves the base motion excitation of a structural element instead of force excitation. In this case, the relationship between response and excitation is typically based on displacements, which are known as transmissibility functions. In this study, a methodology for experimental modal analysis using high-speed 3D digital image correlation and base motion excitation tests is proposed. In particular, a cantilever beam was excited from its base with a random signal, using a clamped edge join. Full-field transmissibility functions were obtained through the beam and converted into FRF for proper identification, considering a single degree-of-freedom theoretical conversion. Subsequently, modal identification was performed using a circle-fit approach. The proposed methodology facilitates the management of the typically large amounts of data points involved in the DIC measurement during modal identification. Moreover, it was possible to determine the natural frequencies, damping ratios and full-field mode shapes without requiring any additional tests. Finally, the results were experimentally validated by comparing them with those obtained by employing traditional accelerometers, analytical models and finite element method analyses. The comparison was performed by using the quantitative indicator modal assurance criterion. The results showed a high level of correspondence, consolidating the proposed experimental methodology.

Adaptive functioning following pediatric traumatic brain injury: Relationship to executive function and processing speed.

PubMed

Shultz, Emily L; Hoskinson, Kristen R; Keim, Madelaine C; Dennis, Maureen; Taylor, H Gerry; Bigler, Erin D; Rubin, Kenneth H; Vannatta, Kathryn; Gerhardt, Cynthia A; Stancin, Terry; Yeates, Keith Owen

2016-10-01

Pediatric traumatic brain injury (TBI) may affect children's ability to perform everyday tasks (i.e., adaptive functioning). Guided by the American Association for Intellectual and Developmental Disabilities (AAIDD) model, we explored the association between TBI and adaptive functioning at increasing levels of specificity (global, AAIDD domains, and subscales). We also examined the contributions of executive function and processing speed as mediators of TBI's effects on adaptive functioning. Children (ages 8-13) with severe TBI (STBI; n = 19), mild-moderate TBI (MTBI; n = 50), or orthopedic injury (OI; n = 60) completed measures of executive function (TEA-Ch) and processing speed (WISC-IV) an average of 2.7 years postinjury (SD = 1.2; range: 1-5.3). Parents rated children's adaptive functioning (ABAS-II, BASC-2, CASP). STBI had lower global adaptive functioning (η2 = .04-.08) than the MTBI and OI groups, which typically did not differ. Deficits in the STBI group were particularly evident in the social domain, with specific deficits in social participation, leisure, and social adjustment (η2 = .06-.09). Jointly, executive function and processing speed were mediators of STBI's effects on global adaptive functioning and in conceptual and social domains. In the STBI group, executive function mediated social functioning, and processing speed mediated social participation. Children with STBI experience deficits in adaptive functioning, particularly in social adjustment, with less pronounced deficits in conceptual and practical skills. Executive function and processing speed may mediate the effects of STBI on adaptive functioning. Targeting adaptive functioning and associated cognitive deficits for intervention may enhance quality of life for pediatric TBI survivors. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Adaptive functioning following pediatric traumatic brain injury: Relationship to executive function and processing speed

PubMed Central

Shultz, Emily; Robinson, Kristen E.; Keim, Madelaine; Dennis, Maureen; Taylor, H. Gerry; Bigler, Erin D.; Rubin, Kenneth H.; Vannatta, Kathryn; Gerhardt, Cynthia A.; Stancin, Terry; Yeates, Keith Owen

2016-01-01

Objective Pediatric traumatic brain injury (TBI) may affect children’s ability to perform everyday tasks (i.e., adaptive functioning). Guided by the American Association for Intellectual and Developmental Disabilities (AAIDD) model, we explored the association between TBI and adaptive functioning at increasing levels of specificity (global, AAIDD domains, and subscales). We also examined the contributions of executive function and processing speed as mediators of TBI’s effects on adaptive functioning. Method Children (ages 8–13) with severe TBI (STBI; n=19), mild-moderate TBI (MTBI; n=50), or orthopedic injury (OI; n=60) completed measures of executive function (TEA-Ch) and processing speed (WISC-IV) an average of 2.7 years post-injury (SD = 1.2; range: 1–5.3). Parents rated children’s adaptive functioning (ABAS-II, BASC-2, CASP). Results STBI had lower global adaptive functioning (η2 = .04–.08) than the MTBI and OI groups, which typically did not differ. Deficits in the STBI group were particularly evident in the social domain, with specific deficits in social participation, leisure, and social adjustment (η2 = .06–.09). Jointly, executive function and processing speed were mediators of STBI’s effects on global adaptive functioning and in conceptual and social domains. In the STBI group, executive function mediated social functioning, and processing speed mediated social participation. Conclusions Children with STBI experience deficits in adaptive functioning, particularly in social adjustment, with less pronounced deficits in conceptual and practical skills. Executive function and processing speed may mediate the effects of STBI on adaptive functioning. Targeting adaptive functioning and associated cognitive deficits for intervention may enhance quality of life for pediatric TBI survivors. PMID:27182708

Large eddy simulations and direct numerical simulations of high speed turbulent reacting flows

NASA Technical Reports Server (NTRS)

Givi, P.; Madnia, C. K.; Steinberger, C. J.; Frankel, S. H.

1992-01-01

The basic objective of this research is to extend the capabilities of Large Eddy Simulations (LES) and Direct Numerical Simulations (DNS) for the computational analyses of high speed reacting flows. In the efforts related to LES, we were primarily involved with assessing the performance of the various modern methods based on the Probability Density Function (PDF) methods for providing closures for treating the subgrid fluctuation correlations of scalar quantities in reacting turbulent flows. In the work on DNS, we concentrated on understanding some of the relevant physics of compressible reacting flows by means of statistical analysis of the data generated by DNS of such flows. In the research conducted in the second year of this program, our efforts focused on the modeling of homogeneous compressible turbulent flows by PDF methods, and on DNS of non-equilibrium reacting high speed mixing layers. Some preliminary work is also in progress on PDF modeling of shear flows, and also on LES of such flows.

The Application of Virtex-II Pro FPGA in High-Speed Image Processing Technology of Robot Vision Sensor

NASA Astrophysics Data System (ADS)

Ren, Y. J.; Zhu, J. G.; Yang, X. Y.; Ye, S. H.

2006-10-01

The Virtex-II Pro FPGA is applied to the vision sensor tracking system of IRB2400 robot. The hardware platform, which undertakes the task of improving SNR and compressing data, is constructed by using the high-speed image processing of FPGA. The lower level image-processing algorithm is realized by combining the FPGA frame and the embedded CPU. The velocity of image processing is accelerated due to the introduction of FPGA and CPU. The usage of the embedded CPU makes it easily to realize the logic design of interface. Some key techniques are presented in the text, such as read-write process, template matching, convolution, and some modules are simulated too. In the end, the compare among the modules using this design, using the PC computer and using the DSP, is carried out. Because the high-speed image processing system core is a chip of FPGA, the function of which can renew conveniently, therefore, to a degree, the measure system is intelligent.

A Fuzzy-Based Control Method for Smoothing Power Fluctuations in Substations along High-Speed Railways

NASA Astrophysics Data System (ADS)

Sugio, Tetsuya; Yamamoto, Masayoshi; Funabiki, Shigeyuki

The use of an SMES (Superconducting Magnetic Energy Storage) for smoothing power fluctuations in a railway substation has been discussed. This paper proposes a smoothing control method based on fuzzy reasoning for reducing the SMES capacity at substations along high-speed railways. The proposed smoothing control method comprises three countermeasures for reduction of the SMES capacity. The first countermeasure involves modification of rule 1 for smoothing out the fluctuating electric power to its average value. The other countermeasures involve the modification of the central value of the stored energy control in the SMES and revision of the membership function in rule 2 for reduction of the SMES capacity. The SMES capacity in the proposed smoothing control method is reduced by 49.5% when compared to that in the nonrevised control method. It is confirmed by computer simulations that the proposed control method is suitable for smoothing out power fluctuations in substations along high-speed railways and for reducing the SMES capacity.

Optimized design on condensing tubes high-speed TIG welding technology magnetic control based on genetic algorithm

NASA Astrophysics Data System (ADS)

Lu, Lin; Chang, Yunlong; Li, Yingmin; Lu, Ming

2013-05-01

An orthogonal experiment was conducted by the means of multivariate nonlinear regression equation to adjust the influence of external transverse magnetic field and Ar flow rate on welding quality in the process of welding condenser pipe by high-speed argon tungsten-arc welding (TIG for short). The magnetic induction and flow rate of Ar gas were used as optimum variables, and tensile strength of weld was set to objective function on the base of genetic algorithm theory, and then an optimal design was conducted. According to the request of physical production, the optimum variables were restrained. The genetic algorithm in the MATLAB was used for computing. A comparison between optimum results and experiment parameters was made. The results showed that the optimum technologic parameters could be chosen by the means of genetic algorithm with the conditions of excessive optimum variables in the process of high-speed welding. And optimum technologic parameters of welding coincided with experiment results.

Glycan-functionalized graphene-FETs toward selective detection of human-infectious avian influenza virus

NASA Astrophysics Data System (ADS)

Ono, Takao; Oe, Takeshi; Kanai, Yasushi; Ikuta, Takashi; Ohno, Yasuhide; Maehashi, Kenzo; Inoue, Koichi; Watanabe, Yohei; Nakakita, Shin-ichi; Suzuki, Yasuo; Kawahara, Toshio; Matsumoto, Kazuhiko

2017-03-01

There are global concerns about threat of pandemic caused by the human-infectious avian influenza virus. To prevent the oncoming pandemic, it is crucial to analyze the viral affinity to human-type or avian-type sialoglycans with high sensitivity at high speed. Graphene-FET (G-FET) realizes such high-sensitive electrical detection of the targets, owing to graphene’s high carrier mobility. In the present study, G-FET was functionalized using sialoglycans and employed for the selective detection of lectins from Sambucus sieboldiana and Maackia amurensis as alternatives of the human and avian influenza viruses. Glycan-functionalized G-FET selectively monitored the sialoglycan-specific binding reactions at subnanomolar sensitivity.

Revised ocean backscatter models at C and Ku band under high-wind conditions

NASA Astrophysics Data System (ADS)

Donnelly, William J.; Carswell, James R.; McIntosh, Robert E.; Chang, Paul S.; Wilkerson, John; Marks, Frank; Black, Peter G.

1999-05-01

A series of airborne scatterometer experiments designed to collect C and Ku band ocean backscatter data in regions of high ocean surface winds has recently been completed. More than 100 hours of data were collected using the University of Massachusetts C and Ku band scatterometers, CSCAT and KUSCAT. These instruments measure the full azimuthal normalized radar cross section (NRCS) of a common surface area of the ocean simultaneously at four incidence angles. Our results demonstrate limitations of the current empirical models, C band geophysical model function 4 (CMOD4), SeaSat scatterometer 2 (SASS 2), and NASA scatterometer 1 (NSCAT) 1, that relate ocean backscatter to the near-surface wind at high wind speeds. The discussion focuses on winds in excess of 15 m s-1 in clear atmospheric conditions. The scatterometer data are collocated with measurements from ocean data buoys and Global Positioning System dropsondes, and a Fourier analysis is performed as a function of wind regime. A three-term Fourier series is fit to the backscatter data, and a revised set of coefficients is tabulated. These revised models, CMOD4HW and KUSCAT 1, are the basis for a discussion of the NRCS at high wind speeds. Our scatterometer data show a clear overprediction of the derived NRCS response to high winds based on the CMOD4, SASS 2, and NSCAT 1 models. Furthermore, saturation of the NRCS response begins to occur above 15 m s-1. Sensitivity of the upwind and crosswind response is discussed with implications toward high wind speed retrieval.

Apathy and Reduced Speed of Processing Underlie Decline in Verbal Fluency following DBS.

PubMed

Foley, Jennifer A; Foltynie, Tom; Zrinzo, Ludvic; Hyam, Jonathan A; Limousin, Patricia; Cipolotti, Lisa

2017-01-01

Objective . Reduced verbal fluency is a strikingly uniform finding following deep brain stimulation (DBS) for Parkinson's disease (PD). The precise cognitive mechanism underlying this reduction remains unclear, but theories have suggested reduced motivation, linguistic skill, and/or executive function. It is of note, however, that previous reports have failed to consider the potential role of any changes in speed of processing. Thus, the aim of this study was to examine verbal fluency changes with a particular focus on the role of cognitive speed. Method . In this study, 28 patients with PD completed measures of verbal fluency, motivation, language, executive functioning, and speed of processing, before and after DBS. Results . As expected, there was a marked decline in verbal fluency but also in a timed test of executive functions and two measures of speed of processing. Verbal fluency decline was associated with markers of linguistic and executive functioning, but not after speed of processing was statistically controlled for. In contrast, greater decline in verbal fluency was associated with higher levels of apathy at baseline, which was not associated with changes in cognitive speed. Discussion . Reduced generativity and processing speed may account for the marked reduction in verbal fluency commonly observed following DBS.

Analytical methodology for safety validation of computer controlled subsystems. Volume 1 : state-of-the-art and assessment of safety verification/validation methodologies

DOT National Transportation Integrated Search

1995-09-01

This report describes the development of a methodology designed to assure that a sufficiently high level of safety is achieved and maintained in computer-based systems which perform safety critical functions in high-speed rail or magnetic levitation ...

[Use of high frequency cinematography in diagnosis of globus sensation].

PubMed

Alberty, J; Oelerich, M

1996-09-01

Globus pharyngis is a frequent symptom in patients who consult an otolaryngologist. In many cases, routine diagnostic work-up including history, clinical examination, and barium swallow fail to revealing the underlying pathogenesis. In a retrospective study, we present 51 selected patients suffering from globus pharyngis of unknown origin who were investigated by high-speed cineradiography in a standardized manner. Twenty-four of the patients enrolled in the study (47.1%) showed functional and/or structural swallowing disorders. In 13 cases (25.5%) dyskinesias of the superior esophagus sphincter muscle were found. Five of these patients (9.8%) also had an inconstant hypopharyngeal diverticulum. Six cases (11.8%) showed laryngeal penetration or tracheal aspiration. In four cases (7.8%) functional disorders of pharyngeal, and in three cases (5.9%) functional disorders of oral bolus transport were found. Furthermore one hypopharyngeal web (1.9%) and two benign tumors (3.9%) were detected. In many cases, varying combinations of these findings occurred. Using high-speed cineradiography for evaluation of globus pharyngis results in an increased incidence of pathologic findings, and thus is an important method for interdisciplinary diagnostic work up of patients suffering from this symptom.

Unified gas-kinetic scheme with multigrid convergence for rarefied flow study

NASA Astrophysics Data System (ADS)

Zhu, Yajun; Zhong, Chengwen; Xu, Kun

2017-09-01

The unified gas kinetic scheme (UGKS) is based on direct modeling of gas dynamics on the mesh size and time step scales. With the modeling of particle transport and collision in a time-dependent flux function in a finite volume framework, the UGKS can connect the flow physics smoothly from the kinetic particle transport to the hydrodynamic wave propagation. In comparison with the direct simulation Monte Carlo (DSMC) method, the current equation-based UGKS can implement implicit techniques in the updates of macroscopic conservative variables and microscopic distribution functions. The implicit UGKS significantly increases the convergence speed for steady flow computations, especially in the highly rarefied and near continuum regimes. In order to further improve the computational efficiency, for the first time, a geometric multigrid technique is introduced into the implicit UGKS, where the prediction step for the equilibrium state and the evolution step for the distribution function are both treated with multigrid acceleration. More specifically, a full approximate nonlinear system is employed in the prediction step for fast evaluation of the equilibrium state, and a correction linear equation is solved in the evolution step for the update of the gas distribution function. As a result, convergent speed has been greatly improved in all flow regimes from rarefied to the continuum ones. The multigrid implicit UGKS (MIUGKS) is used in the non-equilibrium flow study, which includes microflow, such as lid-driven cavity flow and the flow passing through a finite-length flat plate, and high speed one, such as supersonic flow over a square cylinder. The MIUGKS shows 5-9 times efficiency increase over the previous implicit scheme. For the low speed microflow, the efficiency of MIUGKS is several orders of magnitude higher than the DSMC. Even for the hypersonic flow at Mach number 5 and Knudsen number 0.1, the MIUGKS is still more than 100 times faster than the DSMC method for obtaining a convergent steady state solution.

The basic mechanics of bipedal walking lead to asymmetric behavior.

PubMed

Gregg, Robert D; Degani, Amir; Dhaher, Yasin; Lynch, Kevin M

2011-01-01

This paper computationally investigates whether gait asymmetries can be attributed in part to basic bipedal mechanics independent of motor control. Using a symmetrical rigid-body model known as the compass-gait biped, we show that changes in environmental or physiological parameters can facilitate asymmetry in gait kinetics at fast walking speeds. In the environmental case, the asymmetric family of high-speed gaits is in fact more stable than the symmetric family of low-speed gaits. These simulations suggest that lower extremity mechanics might play a direct role in functional and pathological asymmetries reported in human walking, where velocity may be a common variable in the emergence and growth of asymmetry. © 2011 IEEE

Aircraft engine-mounted camera system for long wavelength infrared imaging of in-service thermal barrier coated turbine blades

NASA Astrophysics Data System (ADS)

Markham, James; Cosgrove, Joseph; Scire, James; Haldeman, Charles; Agoos, Ian

2014-12-01

This paper announces the implementation of a long wavelength infrared camera to obtain high-speed thermal images of an aircraft engine's in-service thermal barrier coated turbine blades. Long wavelength thermal images were captured of first-stage blades. The achieved temporal and spatial resolutions allowed for the identification of cooling-hole locations. The software and synchronization components of the system allowed for the selection of any blade on the turbine wheel, with tuning capability to image from leading edge to trailing edge. Its first application delivered calibrated thermal images as a function of turbine rotational speed at both steady state conditions and during engine transients. In advance of presenting these data for the purpose of understanding engine operation, this paper focuses on the components of the system, verification of high-speed synchronized operation, and the integration of the system with the commercial jet engine test bed.

Sensorless FOC Performance Improved with On-Line Speed and Rotor Resistance Estimator Based on an Artificial Neural Network for an Induction Motor Drive

PubMed Central

Gutierrez-Villalobos, Jose M.; Rodriguez-Resendiz, Juvenal; Rivas-Araiza, Edgar A.; Martínez-Hernández, Moisés A.

2015-01-01

Three-phase induction motor drive requires high accuracy in high performance processes in industrial applications. Field oriented control, which is one of the most employed control schemes for induction motors, bases its function on the electrical parameter estimation coming from the motor. These parameters make an electrical machine driver work improperly, since these electrical parameter values change at low speeds, temperature changes, and especially with load and duty changes. The focus of this paper is the real-time and on-line electrical parameters with a CMAC-ADALINE block added in the standard FOC scheme to improve the IM driver performance and endure the driver and the induction motor lifetime. Two kinds of neural network structures are used; one to estimate rotor speed and the other one to estimate rotor resistance of an induction motor. PMID:26131677

Sensorless FOC Performance Improved with On-Line Speed and Rotor Resistance Estimator Based on an Artificial Neural Network for an Induction Motor Drive.

PubMed

Gutierrez-Villalobos, Jose M; Rodriguez-Resendiz, Juvenal; Rivas-Araiza, Edgar A; Martínez-Hernández, Moisés A

2015-06-29

Three-phase induction motor drive requires high accuracy in high performance processes in industrial applications. Field oriented control, which is one of the most employed control schemes for induction motors, bases its function on the electrical parameter estimation coming from the motor. These parameters make an electrical machine driver work improperly, since these electrical parameter values change at low speeds, temperature changes, and especially with load and duty changes. The focus of this paper is the real-time and on-line electrical parameters with a CMAC-ADALINE block added in the standard FOC scheme to improve the IM driver performance and endure the driver and the induction motor lifetime. Two kinds of neural network structures are used; one to estimate rotor speed and the other one to estimate rotor resistance of an induction motor.

Aircraft engine-mounted camera system for long wavelength infrared imaging of in-service thermal barrier coated turbine blades.

PubMed

Markham, James; Cosgrove, Joseph; Scire, James; Haldeman, Charles; Agoos, Ian

2014-12-01

This paper announces the implementation of a long wavelength infrared camera to obtain high-speed thermal images of an aircraft engine's in-service thermal barrier coated turbine blades. Long wavelength thermal images were captured of first-stage blades. The achieved temporal and spatial resolutions allowed for the identification of cooling-hole locations. The software and synchronization components of the system allowed for the selection of any blade on the turbine wheel, with tuning capability to image from leading edge to trailing edge. Its first application delivered calibrated thermal images as a function of turbine rotational speed at both steady state conditions and during engine transients. In advance of presenting these data for the purpose of understanding engine operation, this paper focuses on the components of the system, verification of high-speed synchronized operation, and the integration of the system with the commercial jet engine test bed.

Modal identification of spindle-tool unit in high-speed machining

NASA Astrophysics Data System (ADS)

Gagnol, Vincent; Le, Thien-Phu; Ray, Pascal

2011-10-01

The accurate knowledge of high-speed motorised spindle dynamic behaviour during machining is important in order to ensure the reliability of machine tools in service and the quality of machined parts. More specifically, the prediction of stable cutting regions, which is a critical requirement for high-speed milling operations, requires the accurate estimation of tool/holder/spindle set dynamic modal parameters. These estimations are generally obtained through Frequency Response Function (FRF) measurements of the non-rotating spindle. However, significant changes in modal parameters are expected to occur during operation, due to high-speed spindle rotation. The spindle's modal variations are highlighted through an integrated finite element model of the dynamic high-speed spindle-bearing system, taking into account rotor dynamics effects. The dependency of dynamic behaviour on speed range is then investigated and determined with accuracy. The objective of the proposed paper is to validate these numerical results through an experiment-based approach. Hence, an experimental setup is elaborated to measure rotating tool vibration during the machining operation in order to determine the spindle's modal frequency variation with respect to spindle speed in an industrial environment. The identification of natural frequencies of the spindle under rotating conditions is challenging, due to the low number of sensors and the presence of many harmonics in the measured signals. In order to overcome these issues and to extract the characteristics of the system, the spindle modes are determined through a 3-step procedure. First, spindle modes are highlighted using the Frequency Domain Decomposition (FDD) technique, with a new formulation at the considered rotating speed. These extracted modes are then analysed through the value of their respective damping ratios in order to separate the harmonics component from structural spindle natural frequencies. Finally, the stochastic properties of the modes are also investigated by considering the probability density of the retained modes. Results show a good correlation between numerical and experiment-based identified frequencies. The identified spindle-tool modal properties during machining allow the numerical model to be considered as representative of the real dynamic properties of the system.

Stabilizing skateboard speed-wobble with reflex delay.

PubMed

Varszegi, Balazs; Takacs, Denes; Stepan, Gabor; Hogan, S John

2016-08-01

A simple mechanical model of the skateboard-skater system is analysed, in which the effect of human control is considered by means of a linear proportional-derivative (PD) controller with delay. The equations of motion of this non-holonomic system are neutral delay-differential equations. A linear stability analysis of the rectilinear motion is carried out analytically. It is shown how to vary the control gains with respect to the speed of the skateboard to stabilize the uniform motion. The critical reflex delay of the skater is determined as the function of the speed. Based on this analysis, we present an explanation for the linear instability of the skateboard-skater system at high speed. Moreover, the advantages of standing ahead of the centre of the board are demonstrated from the viewpoint of reflex delay and control gain sensitivity. © 2016 The Author(s).

Nonparametric Stochastic Model for Uncertainty Quantifi cation of Short-term Wind Speed Forecasts

NASA Astrophysics Data System (ADS)

AL-Shehhi, A. M.; Chaouch, M.; Ouarda, T.

2014-12-01

Wind energy is increasing in importance as a renewable energy source due to its potential role in reducing carbon emissions. It is a safe, clean, and inexhaustible source of energy. The amount of wind energy generated by wind turbines is closely related to the wind speed. Wind speed forecasting plays a vital role in the wind energy sector in terms of wind turbine optimal operation, wind energy dispatch and scheduling, efficient energy harvesting etc. It is also considered during planning, design, and assessment of any proposed wind project. Therefore, accurate prediction of wind speed carries a particular importance and plays significant roles in the wind industry. Many methods have been proposed in the literature for short-term wind speed forecasting. These methods are usually based on modeling historical fixed time intervals of the wind speed data and using it for future prediction. The methods mainly include statistical models such as ARMA, ARIMA model, physical models for instance numerical weather prediction and artificial Intelligence techniques for example support vector machine and neural networks. In this paper, we are interested in estimating hourly wind speed measures in United Arab Emirates (UAE). More precisely, we predict hourly wind speed using a nonparametric kernel estimation of the regression and volatility functions pertaining to nonlinear autoregressive model with ARCH model, which includes unknown nonlinear regression function and volatility function already discussed in the literature. The unknown nonlinear regression function describe the dependence between the value of the wind speed at time t and its historical data at time t -1, t - 2, … , t - d. This function plays a key role to predict hourly wind speed process. The volatility function, i.e., the conditional variance given the past, measures the risk associated to this prediction. Since the regression and the volatility functions are supposed to be unknown, they are estimated using nonparametric kernel methods. In addition, to the pointwise hourly wind speed forecasts, a confidence interval is also provided which allows to quantify the uncertainty around the forecasts.

Plasma Oscillation Characterization of NASA's HERMeS Hall Thruster via High Speed Imaging

NASA Technical Reports Server (NTRS)

Huang, Wensheng; Kamhawi, Hani; Haag, Thomas W.

2016-01-01

The performance and facility effect characterization tests of NASA's 12.5-kW Hall Effect Rocket with Magnetic Shielding had been completed. As a part of these tests, three plasma oscillation characterization studies were performed to help determine operation settings and quantify margins. The studies included the magnetic field strength variation study, background pressure effect study, and cathode flow fraction study. Separate high-speed videos of the thruster including the cathode and of only the cathode were recorded. Breathing mode at 10-15 kHz and cathode gradient-driven mode at 60-75 kHz were observed. An additional high frequency (40-70 kHz) global oscillation mode with sinusoidal probability distribution function was identified.

Towards a Narrowband Photonic Sigma-Delta Digital Antenna

DTIC Science & Technology

2012-02-01

High Speed Photodiode/ Amplifier 26 G no amplifier 50 k transimpedance amplifier N/A 12 ps rise time 50 Ω output impedance HP 8447A Amplifier ......Response for the optical amplifier as a function of input drive current

Efficient space-time sampling with pixel-wise coded exposure for high-speed imaging.

PubMed

Liu, Dengyu; Gu, Jinwei; Hitomi, Yasunobu; Gupta, Mohit; Mitsunaga, Tomoo; Nayar, Shree K

2014-02-01

Cameras face a fundamental trade-off between spatial and temporal resolution. Digital still cameras can capture images with high spatial resolution, but most high-speed video cameras have relatively low spatial resolution. It is hard to overcome this trade-off without incurring a significant increase in hardware costs. In this paper, we propose techniques for sampling, representing, and reconstructing the space-time volume to overcome this trade-off. Our approach has two important distinctions compared to previous works: 1) We achieve sparse representation of videos by learning an overcomplete dictionary on video patches, and 2) we adhere to practical hardware constraints on sampling schemes imposed by architectures of current image sensors, which means that our sampling function can be implemented on CMOS image sensors with modified control units in the future. We evaluate components of our approach, sampling function and sparse representation, by comparing them to several existing approaches. We also implement a prototype imaging system with pixel-wise coded exposure control using a liquid crystal on silicon device. System characteristics such as field of view and modulation transfer function are evaluated for our imaging system. Both simulations and experiments on a wide range of scenes show that our method can effectively reconstruct a video from a single coded image while maintaining high spatial resolution.

High-speed resistance training and balance training for people with knee osteoarthritis to reduce falls risk: study protocol for a pilot randomized controlled trial.

PubMed

Levinger, Pazit; Dunn, Jeremy; Bifera, Nancy; Butson, Michael; Elias, George; Hill, Keith D

2017-08-18

The number of falls experienced by people with knee osteoarthritis (OA) is almost double the number experienced by people with no OA. The neuromuscular elements required to arrest a fall are more impaired in people with knee OA compared to their asymptomatic counterparts. Therefore, these elements may need to be incorporated into an exercise intervention to reduce the risk of falling. The aim of this study will be to examine the feasibility, safety and patient satisfaction of a high-speed resistance-training program, with and without balance exercises, in people with knee OA compared to a control group. The effect of these exercise programs on lower-limb muscle strength and physiological and functional risk factors for falls will also be examined. This study will be a pilot randomized controlled trial with a pre- and post-intervention design (outcome assessments at baseline and 8 weeks after participation commencement) comparing three groups: a control group (no intervention), a high-speed resistance-training group and a high-speed resistance-training plus balance exercises group. Thirty people with knee osteoarthritis aged 60-90 years will be recruited and randomized to one of the three groups. Feasibility and safety will be assessed by examining adherence to the exercise program, dropout rate, pain level during and following exercise, number of exercises stopped due to pain, and any adverse event or any incident that prevents the participant from completing the prescribed exercise. Secondary measures of lower-limb strength, physical function, self-reported pain and function, fear of falls, and executive function and quality of life will also be assessed. To determine statistical trends of effectiveness and hence to inform sample size for a fully powered study, analyses of the secondary outcomes will be performed to assess the changes within and between groups over time (pre-post) using repeated measure ANOVA. The results of this study will improve understanding of what type of exercise is safe and beneficial for people with knee OA to reduce their risk of falling, and hence will inform the development of a future large research trial. Australian New Zealand Clinical Trials Registry, ID: ACTRN12616001382460 . Registered on 6 October 2016.

Experimental settlement and dynamic behavior of a portion of ballasted railway track under high speed trains

NASA Astrophysics Data System (ADS)

Al Shaer, A.; Duhamel, D.; Sab, K.; Foret, G.; Schmitt, L.

2008-09-01

The study of railway tracks under high speed trains is one of the most important researches in the domain of transport. A reduced scale experiment with three sleepers is presented to study the dynamic behavior and the settlement of ballasted tracks. A large number of trains passing at high speeds are simulated by signals, applied with the help of hydraulic jacks, having the shape of the letter M and representing the passages of bogies on sleepers. This experiment offers results such as displacements, accelerations, pressures and settlements that allow to better understand the dynamic behavior of a portion of a ballasted railway track at reduced scale and to estimate the settlement versus the number of load cycles. It was found that mechanical properties such as the global stiffness of the track can have important variations during the experiment. The settlement was also found to be a function of the acceleration of sleepers and above all it was observed, for accelerations above a critical value, that the increase of settlement per cycle was very high.

Efficient hash tables for network applications.

PubMed

Zink, Thomas; Waldvogel, Marcel

2015-01-01

Hashing has yet to be widely accepted as a component of hard real-time systems and hardware implementations, due to still existing prejudices concerning the unpredictability of space and time requirements resulting from collisions. While in theory perfect hashing can provide optimal mapping, in practice, finding a perfect hash function is too expensive, especially in the context of high-speed applications. The introduction of hashing with multiple choices, d-left hashing and probabilistic table summaries, has caused a shift towards deterministic DRAM access. However, high amounts of rare and expensive high-speed SRAM need to be traded off for predictability, which is infeasible for many applications. In this paper we show that previous suggestions suffer from the false precondition of full generality. Our approach exploits four individual degrees of freedom available in many practical applications, especially hardware and high-speed lookups. This reduces the requirement of on-chip memory up to an order of magnitude and guarantees constant lookup and update time at the cost of only minute amounts of additional hardware. Our design makes efficient hash table implementations cheaper, more predictable, and more practical.

Speed of sound as a function of temperature for ultrasonic propagation in soybean oil

NASA Astrophysics Data System (ADS)

Oliveira, P. A.; Silva, R. M. B.; Morais, G. C.; Alvarenga, A. V.; Costa-Félix, R. P. B.

2016-07-01

Ultrasound has been used for characterization of liquid in several productive sectors and research. This work presents the studied about the behavior of the speed of sound in soybean oil with increasing temperature. The pulse echo technique allowed observing that the speed of sound decreases linearly with increasing temperature in the range 20 to 50 °C at 1 MHz. As result, a characteristic function capable to reproduce the speed of sound behavior in soybean oil, as a function of temperature was established, with the respective measurement uncertainty.

Test-retest reliability and minimal detectable change scores for the timed "up & go" test, the six-minute walk test, and gait speed in people with Alzheimer disease.

PubMed

Ries, Julie D; Echternach, John L; Nof, Leah; Gagnon Blodgett, Michelle

2009-06-01

With the increasing incidence of Alzheimer disease (AD), determining the validity and reliability of outcome measures for people with this disease is necessary. The goals of this study were to assess test-retest reliability of data for the Timed "Up & Go" Test (TUG), the Six-Minute Walk Test (6MWT), and gait speed and to calculate minimal detectable change (MDC) scores for each outcome measure. Performance differences between groups with mild to moderate AD and moderately severe to severe AD (as determined by the Functional Assessment Staging [FAST] scale) were studied. This was a prospective, nonexperimental, descriptive methodological study. Background data collected for 51 people with AD included: use of an assistive device, Mini-Mental Status Examination scores, and FAST scale scores. Each participant engaged in 2 test sessions, separated by a 30- to 60-minute rest period, which included 2 TUG trials, 1 6MWT trial, and 2 gait speed trials using a computerized gait assessment system. A specific cuing protocol was followed to achieve optimal performance during test sessions. Test-retest reliability values for the TUG, the 6MWT, and gait speed were high for all participants together and for the mild to moderate AD and moderately severe to severe AD groups separately (intraclass correlation coefficients > or = .973); however, individual variability of performance also was high. Calculated MDC scores at the 90% confidence interval were: TUG=4.09 seconds, 6MWT=33.5 m (110 ft), and gait speed=9.4 cm/s. The 2 groups were significantly different in performance of clinical tests, with the participants who were more cognitively impaired being more physically and functionally impaired. A single researcher for data collection limited sample numbers and prohibited blinding to dementia level. The TUG, the 6MWT, and gait speed are reliable outcome measures for use with people with AD, recognizing that individual variability of performance is high. Minimal detectable change scores at the 90% confidence interval can be used to assess change in performance over time and the impact of treatment.

Locomotor Recovery in Spinal Cord Injury: Insights Beyond Walking Speed and Distance.

PubMed

Awai, Lea; Curt, Armin

2016-08-01

Recovery of locomotor function after incomplete spinal cord injury (iSCI) is clinically assessed through walking speed and distance, while improvements in these measures might not be in line with a normalization of gait quality and are, on their own, insensitive at revealing potential mechanisms underlying recovery. The objective of this study was to relate changes of gait parameters to the recovery of walking speed while distinguishing between parameters that rather reflect speed improvements from factors contributing to overall recovery. Kinematic data of 16 iSCI subjects were repeatedly recorded during in-patient rehabilitation. The responsiveness of gait parameters to walking speed was assessed by linear regression. Principal component analysis (PCA) was applied on the multivariate data across time to identify factors that contribute to recovery after iSCI. Parameters of gait cycle and movement dynamics were both responsive and closely related to the recovery of walking speed, which increased by 96%. Multivariate analysis revealed specific gait parameters (intralimb shape normality and consistency) that, although less related to speed increments, loaded highly on principal component one (PC1) (58.6%) explaining the highest proportion of variance (i.e., recovery of outcome over time). Interestingly, measures of hip, knee, and ankle range of motion showed varying degrees of responsiveness (from very high to very low) while not contributing to gait recovery as revealed by PCA. The conjunct application of two analysis methods distinguishes gait parameters that simply reflect increased walking speed from parameters that actually contribute to gait recovery in iSCI. This distinction may be of value for the evaluation of interventions for locomotor recovery.

Visual control of flight speed in Drosophila melanogaster.

PubMed

Fry, Steven N; Rohrseitz, Nicola; Straw, Andrew D; Dickinson, Michael H

2009-04-01

Flight control in insects depends on self-induced image motion (optic flow), which the visual system must process to generate appropriate corrective steering maneuvers. Classic experiments in tethered insects applied rigorous system identification techniques for the analysis of turning reactions in the presence of rotating pattern stimuli delivered in open-loop. However, the functional relevance of these measurements for visual free-flight control remains equivocal due to the largely unknown effects of the highly constrained experimental conditions. To perform a systems analysis of the visual flight speed response under free-flight conditions, we implemented a 'one-parameter open-loop' paradigm using 'TrackFly' in a wind tunnel equipped with real-time tracking and virtual reality display technology. Upwind flying flies were stimulated with sine gratings of varying temporal and spatial frequencies, and the resulting speed responses were measured from the resulting flight speed reactions. To control flight speed, the visual system of the fruit fly extracts linear pattern velocity robustly over a broad range of spatio-temporal frequencies. The speed signal is used for a proportional control of flight speed within locomotor limits. The extraction of pattern velocity over a broad spatio-temporal frequency range may require more sophisticated motion processing mechanisms than those identified in flies so far. In Drosophila, the neuromotor pathways underlying flight speed control may be suitably explored by applying advanced genetic techniques, for which our data can serve as a baseline. Finally, the high-level control principles identified in the fly can be meaningfully transferred into a robotic context, such as for the robust and efficient control of autonomous flying micro air vehicles.

On the Decrease of the Oceanic Drag Coefficient in High Winds

NASA Astrophysics Data System (ADS)

Donelan, Mark A.

2018-02-01

The sheltering coefficient - prefixing Jeffreys' concept of the exponential wave growth rate at a gas-liquid interface - is shown to be Reynolds number dependent from laboratory measurements of waves and Reynolds stresses. There are two turbulent flow regimes: wind speed range of 2.5 to 30 m/s where the drag coefficients increase with wind speed, and wind speed range of 30 to 50 m/s where sheltering/drag coefficients decrease/saturate with wind speed. By comparing model calculations of drag coefficients - using a fixed sheltering coefficient - with ocean observations over a wind speed range of 1 to 50 m/s a similar Reynolds number dependence of the oceanic sheltering coefficient is revealed. In consequence the drag coefficient is a function of Reynolds number and wave age, and not just wind speed as frequently assumed. The resulting decreasing drag coefficient above 30 m/s is shown to be critical in explaining the rapid intensification so prominent in the climatology of Atlantic hurricanes. The Reynolds number dependence of the sheltering coefficient, when employed in coupled models, should lead to significant improvements in the prediction of intensification and decay of tropical cyclones. A calculation of curvature at the wave crest suggests that at wind speeds above 56.15 m/s all waves-breaking or not-induce steady flow separation leading to a minimum in the drag coefficient. This is further evidence of the veracity of the observations of the oceanic drag coefficient at high winds.

WISC-IV Profile in High-Functioning Autism Spectrum Disorders: Impaired Processing Speed Is Associated with Increased Autism Communication Symptoms and Decreased Adaptive Communication Abilities

ERIC Educational Resources Information Center

Oliveras-Rentas, Rafael E.; Kenworthy, Lauren; Roberson, Richard B.; Martin, Alex; Wallace, Gregory L.

2012-01-01

Changes in the Wechsler Intelligence Scales for Children-IV (WISC-IV) may affect the IQ profile characteristic of autism spectrum disorders (ASD). Moreover, the association of particular component cognitive abilities (unlike overall IQ) with symptomatology and adaptive functioning in ASD remains unclear. This archival study characterizes the…

Effect of speed matching on fundamental diagram of pedestrian flow

NASA Astrophysics Data System (ADS)

Fu, Zhijian; Luo, Lin; Yang, Yue; Zhuang, Yifan; Zhang, Peitong; Yang, Lizhong; Yang, Hongtai; Ma, Jian; Zhu, Kongjin; Li, Yanlai

2016-09-01

Properties of pedestrian may change along their moving path, for example, as a result of fatigue or injury, which has never been properly investigated in the past research. The paper attempts to study the speed matching effect (a pedestrian adjusts his velocity constantly to the average velocity of his neighbors) and its influence on the density-velocity relationship (a pedestrian adjust his velocity to the surrounding density), known as the fundamental diagram of the pedestrian flow. By the means of the cellular automaton, the simulation results fit well with the empirical data, indicating the great advance of the discrete model for pedestrian dynamics. The results suggest that the system velocity and flow rate increase obviously under a big noise, i.e., a diverse composition of pedestrian crowd, especially in the region of middle or high density. Because of the temporary effect, the speed matching has little influence on the fundamental diagram. Along the entire density, the relationship between the step length and the average pedestrian velocity is a piecewise function combined two linear functions. The number of conflicts reaches the maximum with the pedestrian density of 2.5 m-2, while decreases by 5.1% with the speed matching.

Timeframe for return to driving for patients with minimally invasive knee arthroplasty is associated with knee performance on functional tests

PubMed Central

2014-01-01

Background This study hopes to establish the timeframe for a safe return to driving under different speed conditions for patients after minimally invasive total knee arthroplasty and further explores how well various kinds of functional tests on knee performance can predict the patients’ braking ability. Methods 14 patients with right knee osteoarthritis were included in the present study and instructed to perform three simulated driving tasks at preoperative, 2 weeks postoperative and 4 weeks postoperative. Results The results showed that the total braking time at 4 week postoperative has attained the preoperative level at the driving speed 50 and 70 km/hr but not at the driving speed 90 km/hr. It had significantly improving in knee reaction time and maximum isometric force at 4 weeks postoperative. Besides, there was a moderate to high correlation between the scores of the step counts and the total braking time. Conclusions Summary, it is recommended that driving may be resumed 4 weeks after a right knee replacement but had to drive at low or moderate speed and the best predictor of safety driving is step counts. PMID:24913312

Cognitive inconsistency in bipolar patients is determined by increased intra-individual variability in initial phase of task performance.

PubMed

Krukow, Paweł; Szaniawska, Ola; Harciarek, Michał; Plechawska-Wójcik, Małgorzata; Jonak, Kamil

2017-03-01

Bipolar patients show high intra-individual variability during cognitive processing. However, it is not known whether there are a specific fluctuations of variability contributing to the overall high cognitive inconsistency. The objective was to compare dynamic profiles of patients and healthy controls to identify hypothetical differences and their associations with overall variability and processing speed. Changes of reaction times iSD during processing speed test performance over time was measured by dividing the iSD for whole task into four consecutive parts. Motor speed and cognitive effort were controlled. Patients with BD exhibited significantly lower results regarding processing speed and higher intra-individual variability comparing with HC. The profile of intra-individual variability changes over time of performance was significantly different in BD versus HC groups: F(3, 207)=8.60, p<0.0001, η p 2 =0.11. iSD of BD patients in the initial phase of performance was three times higher than in the last. There was no significant differences between four intervals in HC group. Inter-group difference in the initial part of the profiles was significant also after controlling for several cognitive and clinical variables. Applied computer version of Cognitive Speed Test was relatively new and, thus, replication studies are needed. Effect seen in the present study is driven mainly by the BD type I. Patients with BD exhibits problems with setting a stimulus-response association in starting phase of cognitive processing. This deficit may negatively interfere with the other cognitive functions, decreasing level of psychosocial functioning, therefore should be explored in future studies. Copyright © 2017 Elsevier B.V. All rights reserved.

Kinematics of fast cervical rotations in persons with chronic neck pain: a cross-sectional and reliability study

PubMed Central

2010-01-01

Background Assessment of sensorimotor function is useful for classification and treatment evaluation of neck pain disorders. Several studies have investigated various aspects of cervical motor functions. Most of these have involved slow or self-paced movements, while few have investigated fast cervical movements. Moreover, the reliability of assessment of fast cervical axial rotation has, to our knowledge, not been evaluated before. Methods Cervical kinematics was assessed during fast axial head rotations in 118 women with chronic nonspecific neck pain (NS) and compared to 49 healthy controls (CON). The relationship between cervical kinematics and symptoms, self-rated functioning and fear of movement was evaluated in the NS group. A sub-sample of 16 NS and 16 CON was re-tested after one week to assess the reliability of kinematic variables. Six cervical kinematic variables were calculated: peak speed, range of movement, conjunct movements and three variables related to the shape of the speed profile. Results Together, peak speed and conjunct movements had a sensitivity of 76% and a specificity of 78% in discriminating between NS and CON, of which the major part could be attributed to peak speed (NS: 226 ± 88 °/s and CON: 348 ± 92 °/s, p < 0.01). Peak speed was slower in NS compared to healthy controls and even slower in NS with comorbidity of low-back pain. Associations were found between reduced peak speed and self-rated difficulties with running, performing head movements, car driving, sleeping and pain. Peak speed showed reasonably high reliability, while the reliability for conjunct movements was poor. Conclusions Peak speed of fast cervical axial rotations is reduced in people with chronic neck pain, and even further reduced in subjects with concomitant low back pain. Fast cervical rotation test seems to be a reliable and valid tool for assessment of neck pain disorders on group level, while a rather large between subject variation and overlap between groups calls for caution in the interpretation of individual assessments. PMID:20875135

Kyphosis and Decline in Physical Function Over 15 Years in Older Community-Dwelling Women: The Study of Osteoporotic Fractures

PubMed Central

2013-01-01

Background Maintaining physical function is an important prerequisite for preserving independence in later life. Greater degrees of kyphosis in the thoracic spine are prevalent in older persons and accompanied by reduced physical function in multiple cross-sectional studies. It is unknown whether kyphosis predicts worse physical function over time. Methods. We retrospectively assessed whether greater magnitude of kyphosis is associated with decline in self-reported and objectively measured physical function over 15 years. Digitized Cobb angle kyphosis (T4–T12) was derived from supine lateral thoracic spine radiographs in a cohort of 1,196 women aged 65 and older (mean = 69.3 years [SD = 4.0]). Using regression models, we evaluated associations of baseline kyphosis with both self-reported functional status and objectively measured gait speed, grip strength, and timed chair stands cross-sectionally and as change assessed over 15 years. Results. In cross-sectional multivariate analyses, with each 10-degree increment of kyphosis, grip strength was 0.24kg lower (p = .02), but there were no significant associations between kyphosis and functional status, gait speed, or timed chair stand, likely reflecting the high functioning study participants. In multivariate longitudinal analysis, with each 10-degree increment in baseline kyphosis, there was 0.07 point additional decline in functional status (p = .09), 0.01 m/s more decline in gait speed (p = .07), and 0.32 s greater decline in time to complete five chair stands (p = .004), but no association with decline in grip strength. Conclusions. Greater magnitude of kyphosis may predict worsening lower extremity function over time in older women. Early recognition and preventative measures against kyphosis progression may help preserve physical function over the long term. PMID:23633167

Kyphosis and decline in physical function over 15 years in older community-dwelling women: the Study of Osteoporotic Fractures.

PubMed

Katzman, Wendy B; Huang, Mei-Hua; Lane, Nancy E; Ensrud, Kristine E; Kado, Deborah M

2013-08-01

Maintaining physical function is an important prerequisite for preserving independence in later life. Greater degrees of kyphosis in the thoracic spine are prevalent in older persons and accompanied by reduced physical function in multiple cross-sectional studies. It is unknown whether kyphosis predicts worse physical function over time. We retrospectively assessed whether greater magnitude of kyphosis is associated with decline in self-reported and objectively measured physical function over 15 years. Digitized Cobb angle kyphosis (T4-T12) was derived from supine lateral thoracic spine radiographs in a cohort of 1,196 women aged 65 and older (mean = 69.3 years [SD = 4.0]). Using regression models, we evaluated associations of baseline kyphosis with both self-reported functional status and objectively measured gait speed, grip strength, and timed chair stands cross-sectionally and as change assessed over 15 years. In cross-sectional multivariate analyses, with each 10-degree increment of kyphosis, grip strength was 0.24 kg lower (p = .02), but there were no significant associations between kyphosis and functional status, gait speed, or timed chair stand, likely reflecting the high functioning study participants. In multivariate longitudinal analysis, with each 10-degree increment in baseline kyphosis, there was 0.07 point additional decline in functional status (p = .09), 0.01 m/s more decline in gait speed (p = .07), and 0.32 s greater decline in time to complete five chair stands (p = .004), but no association with decline in grip strength. Greater magnitude of kyphosis may predict worsening lower extremity function over time in older women. Early recognition and preventative measures against kyphosis progression may help preserve physical function over the long term.

Executive functioning and processing speed in age-related differences in memory: contribution of a coding task.

PubMed

Baudouin, Alexia; Clarys, David; Vanneste, Sandrine; Isingrini, Michel

2009-12-01

The aim of the present study was to examine executive dysfunctioning and decreased processing speed as potential mediators of age-related differences in episodic memory. We compared the performances of young and elderly adults in a free-recall task. Participants were also given tests to measure executive functions and perceptual processing speed and a coding task (the Digit Symbol Substitution Test, DSST). More precisely, we tested the hypothesis that executive functions would mediate the age-related differences observed in the free-recall task better than perceptual speed. We also tested the assumption that a coding task, assumed to involve both executive processes and perceptual speed, would be the best mediator of age-related differences in memory. Findings first confirmed that the DSST combines executive processes and perceptual speed. Secondly, they showed that executive functions are a significant mediator of age-related differences in memory, and that DSST performance is the best predictor.

Spume Drops: Their Potential Role in Air-Sea Gas Exchange

NASA Astrophysics Data System (ADS)

Monahan, Edward C.; Staniec, Allison; Vlahos, Penny

2017-12-01

After summarizing the time scales defining the change of the physical properties of spume and other droplets cast up from the sea surface, the time scales governing drop-atmosphere gas exchange are compared. Following a broad review of the spume drop production functions described in the literature, a subset of these functions is selected via objective criteria, to represent typical, upper bound, and lower bound production functions. Three complementary mechanisms driving spume-atmosphere gas exchange are described, and one is then used to estimate the relative importance, over a broad range of wind speeds, of this spume drop mechanism compared to the conventional, diffusional, sea surface mechanism in air-sea gas exchange. While remaining uncertainties in the wind dependence of the spume drop production flux, and in the immediate sea surface gas flux, preclude a definitive conclusion, the findings of this study strongly suggest that, at high wind speeds (>20 m s-1 for dimethyl sulfide and >30 m s-1 for gases such a carbon dioxide), spume drops do make a significant contribution to air-sea gas exchange.