Sample records for acceleration measurement method

  1. A new method of measuring gravitational acceleration in an undergraduate laboratory program

    NASA Astrophysics Data System (ADS)

    Wang, Qiaochu; Wang, Chang; Xiao, Yunhuan; Schulte, Jurgen; Shi, Qingfan

    2018-01-01

    This paper presents a high accuracy method to measure gravitational acceleration in an undergraduate laboratory program. The experiment is based on water in a cylindrical vessel rotating about its vertical axis at a constant speed. The water surface forms a paraboloid whose focal length is related to rotational period and gravitational acceleration. This experimental setup avoids classical source errors in determining the local value of gravitational acceleration, so prevalent in the common simple pendulum and inclined plane experiments. The presented method combines multiple physics concepts such as kinematics, classical mechanics and geometric optics, offering the opportunity for lateral as well as project-based learning.

  2. Astronaut mass measurement using linear acceleration method and the effect of body non-rigidity

    NASA Astrophysics Data System (ADS)

    Yan, Hui; Li, LuMing; Hu, ChunHua; Chen, Hao; Hao, HongWei

    2011-04-01

    Astronaut's body mass is an essential factor of health monitoring in space. The latest mass measurement device for the International Space Station (ISS) has employed a linear acceleration method. The principle of this method is that the device generates a constant pulling force, and the astronaut is accelerated on a parallelogram motion guide which rotates at a large radius to achieve a nearly linear trajectory. The acceleration is calculated by regression analysis of the displacement versus time trajectory and the body mass is calculated by using the formula m= F/ a. However, in actual flight, the device is instable that the deviation between runs could be 6-7 kg. This paper considers the body non-rigidity as the major cause of error and instability and analyzes the effects of body non-rigidity from different aspects. Body non-rigidity makes the acceleration of the center of mass (C.M.) oscillate and fall behind the point where force is applied. Actual acceleration curves showed that the overall effect of body non-rigidity is an oscillation at about 7 Hz and a deviation of about 25%. To enhance body rigidity, better body restraints were introduced and a prototype based on linear acceleration method was built. Measurement experiment was carried out on ground on an air table. Three human subjects weighing 60-70 kg were measured. The average variance was 0.04 kg and the average measurement error was 0.4%. This study will provide reference for future development of China's own mass measurement device.

  3. Autogenous accelerated curing of concrete cylinders. Part II, Development of a moisture measuring method.

    DOT National Transportation Integrated Search

    1970-01-01

    Through a literature study, approximately fifty methods of measuring moisture were investigated to ascertain a suitable method for use in measuring moisture changes in 6 inch by 12 inch concrete cylinders cured by the autogenous accelerated curing me...

  4. Method for Direct Measurement of Cosmic Acceleration by 21-cm Absorption Systems

    NASA Astrophysics Data System (ADS)

    Yu, Hao-Ran; Zhang, Tong-Jie; Pen, Ue-Li

    2014-07-01

    So far there is only indirect evidence that the Universe is undergoing an accelerated expansion. The evidence for cosmic acceleration is based on the observation of different objects at different distances and requires invoking the Copernican cosmological principle and Einstein's equations of motion. We examine the direct observability using recession velocity drifts (Sandage-Loeb effect) of 21-cm hydrogen absorption systems in upcoming radio surveys. This measures the change in velocity of the same objects separated by a time interval and is a model-independent measure of acceleration. We forecast that for a CHIME-like survey with a decade time span, we can detect the acceleration of a ΛCDM universe with 5σ confidence. This acceleration test requires modest data analysis and storage changes from the normal processing and cannot be recovered retroactively.

  5. Development of Gravity Acceleration Measurement Using Simple Harmonic Motion Pendulum Method Based on Digital Technology and Photogate Sensor

    NASA Astrophysics Data System (ADS)

    Yulkifli; Afandi, Zurian; Yohandri

    2018-04-01

    Development of gravitation acceleration measurement using simple harmonic motion pendulum method, digital technology and photogate sensor has been done. Digital technology is more practical and optimizes the time of experimentation. The pendulum method is a method of calculating the acceleration of gravity using a solid ball that connected to a rope attached to a stative pole. The pendulum is swung at a small angle resulted a simple harmonic motion. The measurement system consists of a power supply, Photogate sensors, Arduino pro mini and seven segments. The Arduino pro mini receives digital data from the photogate sensor and processes the digital data into the timing data of the pendulum oscillation. The calculation result of the pendulum oscillation time is displayed on seven segments. Based on measured data, the accuracy and precision of the experiment system are 98.76% and 99.81%, respectively. Based on experiment data, the system can be operated in physics experiment especially in determination of the gravity acceleration.

  6. Accelerator system and method of accelerating particles

    NASA Technical Reports Server (NTRS)

    Wirz, Richard E. (Inventor)

    2010-01-01

    An accelerator system and method that utilize dust as the primary mass flux for generating thrust are provided. The accelerator system can include an accelerator capable of operating in a self-neutralizing mode and having a discharge chamber and at least one ionizer capable of charging dust particles. The system can also include a dust particle feeder that is capable of introducing the dust particles into the accelerator. By applying a pulsed positive and negative charge voltage to the accelerator, the charged dust particles can be accelerated thereby generating thrust and neutralizing the accelerator system.

  7. Development of a wireless displacement measurement system using acceleration responses.

    PubMed

    Park, Jong-Woong; Sim, Sung-Han; Jung, Hyung-Jo; Spencer, Billie F

    2013-07-01

    Displacement measurements are useful information for various engineering applications such as structural health monitoring (SHM), earthquake engineering and system identification. Most existing displacement measurement methods are costly, labor-intensive, and have difficulties particularly when applying to full-scale civil structures because the methods require stationary reference points. Indirect estimation methods converting acceleration to displacement can be a good alternative as acceleration transducers are generally cost-effective, easy to install, and have low noise. However, the application of acceleration-based methods to full-scale civil structures such as long span bridges is challenging due to the need to install cables to connect the sensors to a base station. This article proposes a low-cost wireless displacement measurement system using acceleration. Developed with smart sensors that are low-cost, wireless, and capable of on-board computation, the wireless displacement measurement system has significant potential to impact many applications that need displacement information at multiple locations of a structure. The system implements an FIR-filter type displacement estimation algorithm that can remove low frequency drifts typically caused by numerical integration of discrete acceleration signals. To verify the accuracy and feasibility of the proposed system, laboratory tests are carried out using a shaking table and on a three storey shear building model, experimentally confirming the effectiveness of the proposed system.

  8. Development of a Wireless Displacement Measurement System Using Acceleration Responses

    PubMed Central

    Park, Jong-Woong; Sim, Sung-Han; Jung, Hyung-Jo; Spencer, Billie F.

    2013-01-01

    Displacement measurements are useful information for various engineering applications such as structural health monitoring (SHM), earthquake engineering and system identification. Most existing displacement measurement methods are costly, labor-intensive, and have difficulties particularly when applying to full-scale civil structures because the methods require stationary reference points. Indirect estimation methods converting acceleration to displacement can be a good alternative as acceleration transducers are generally cost-effective, easy to install, and have low noise. However, the application of acceleration-based methods to full-scale civil structures such as long span bridges is challenging due to the need to install cables to connect the sensors to a base station. This article proposes a low-cost wireless displacement measurement system using acceleration. Developed with smart sensors that are low-cost, wireless, and capable of on-board computation, the wireless displacement measurement system has significant potential to impact many applications that need displacement information at multiple locations of a structure. The system implements an FIR-filter type displacement estimation algorithm that can remove low frequency drifts typically caused by numerical integration of discrete acceleration signals. To verify the accuracy and feasibility of the proposed system, laboratory tests are carried out using a shaking table and on a three storey shear building model, experimentally confirming the effectiveness of the proposed system. PMID:23881123

  9. The Electrostatic Gavimeter: An Alternative Way of Measuring Gravitational Acceleration

    NASA Astrophysics Data System (ADS)

    Kashinski, David

    2005-03-01

    In the past, Earth’s gravitational acceleration g has been measured in many ways, including the use of a pendulum as well as other models involving the use of a mass and a spring. We have designed a new method incorporating a spring with a capacitor and a voltmeter. This capacitor model still uses a hanging mass on a spring, but alters the method of determining the change in position of the spring due to the gravitational acceleration. We relate the change in position to the potential difference across the capacitor needed to cause a discharge through parallel plates. By relating this voltage directly to the gravitaional acceleration,a new method of measuring g is obtained.

  10. A Novel Method for Vertical Acceleration Noise Suppression of a Thrust-Vectored VTOL UAV.

    PubMed

    Li, Huanyu; Wu, Linfeng; Li, Yingjie; Li, Chunwen; Li, Hangyu

    2016-12-02

    Acceleration is of great importance in motion control for unmanned aerial vehicles (UAVs), especially during the takeoff and landing stages. However, the measured acceleration is inevitably polluted by severe noise. Therefore, a proper noise suppression procedure is required. This paper presents a novel method to reduce the noise in the measured vertical acceleration for a thrust-vectored tail-sitter vertical takeoff and landing (VTOL) UAV. In the new procedure, a Kalman filter is first applied to estimate the UAV mass by using the information in the vertical thrust and measured acceleration. The UAV mass is then used to compute an estimate of UAV vertical acceleration. The estimated acceleration is finally fused with the measured acceleration to obtain the minimum variance estimate of vertical acceleration. By doing this, the new approach incorporates the thrust information into the acceleration estimate. The method is applied to the data measured in a VTOL UAV takeoff experiment. Two other denoising approaches developed by former researchers are also tested for comparison. The results demonstrate that the new method is able to suppress the acceleration noise substantially. It also maintains the real-time performance in the final estimated acceleration, which is not seen in the former denoising approaches. The acceleration treated with the new method can be readily used in the motion control applications for UAVs to achieve improved accuracy.

  11. A Novel Method for Vertical Acceleration Noise Suppression of a Thrust-Vectored VTOL UAV

    PubMed Central

    Li, Huanyu; Wu, Linfeng; Li, Yingjie; Li, Chunwen; Li, Hangyu

    2016-01-01

    Acceleration is of great importance in motion control for unmanned aerial vehicles (UAVs), especially during the takeoff and landing stages. However, the measured acceleration is inevitably polluted by severe noise. Therefore, a proper noise suppression procedure is required. This paper presents a novel method to reduce the noise in the measured vertical acceleration for a thrust-vectored tail-sitter vertical takeoff and landing (VTOL) UAV. In the new procedure, a Kalman filter is first applied to estimate the UAV mass by using the information in the vertical thrust and measured acceleration. The UAV mass is then used to compute an estimate of UAV vertical acceleration. The estimated acceleration is finally fused with the measured acceleration to obtain the minimum variance estimate of vertical acceleration. By doing this, the new approach incorporates the thrust information into the acceleration estimate. The method is applied to the data measured in a VTOL UAV takeoff experiment. Two other denoising approaches developed by former researchers are also tested for comparison. The results demonstrate that the new method is able to suppress the acceleration noise substantially. It also maintains the real-time performance in the final estimated acceleration, which is not seen in the former denoising approaches. The acceleration treated with the new method can be readily used in the motion control applications for UAVs to achieve improved accuracy. PMID:27918422

  12. Influence of tungsten fiber's slow drift on the measurement of G with angular acceleration method.

    PubMed

    Luo, Jie; Wu, Wei-Huang; Xue, Chao; Shao, Cheng-Gang; Zhan, Wen-Ze; Wu, Jun-Fei; Milyukov, Vadim

    2016-08-01

    In the measurement of the gravitational constant G with angular acceleration method, the equilibrium position of torsion pendulum with tungsten fiber undergoes a linear slow drift, which results in a quadratic slow drift on the angular velocity of the torsion balance turntable under feedback control unit. The accurate amplitude determination of the useful angular acceleration signal with known frequency is biased by the linear slow drift and the coupling effect of the drifting equilibrium position and the room fixed gravitational background signal. We calculate the influences of the linear slow drift and the complex coupling effect on the value of G, respectively. The result shows that the bias of the linear slow drift on G is 7 ppm, and the influence of the coupling effect is less than 1 ppm.

  13. Influence of tungsten fiber's slow drift on the measurement of G with angular acceleration method

    NASA Astrophysics Data System (ADS)

    Luo, Jie; Wu, Wei-Huang; Xue, Chao; Shao, Cheng-Gang; Zhan, Wen-Ze; Wu, Jun-Fei; Milyukov, Vadim

    2016-08-01

    In the measurement of the gravitational constant G with angular acceleration method, the equilibrium position of torsion pendulum with tungsten fiber undergoes a linear slow drift, which results in a quadratic slow drift on the angular velocity of the torsion balance turntable under feedback control unit. The accurate amplitude determination of the useful angular acceleration signal with known frequency is biased by the linear slow drift and the coupling effect of the drifting equilibrium position and the room fixed gravitational background signal. We calculate the influences of the linear slow drift and the complex coupling effect on the value of G, respectively. The result shows that the bias of the linear slow drift on G is 7 ppm, and the influence of the coupling effect is less than 1 ppm.

  14. Spatial measurement in rotating magnetic field plasma acceleration method by using two-dimensional scanning instrument and thrust stand

    NASA Astrophysics Data System (ADS)

    Furukawa, T.; Takizawa, K.; Yano, K.; Kuwahara, D.; Shinohara, S.

    2018-04-01

    A two-dimensional scanning probe instrument has been developed to survey spatial plasma characteristics in our electrodeless plasma acceleration schemes. In particular, diagnostics of plasma parameters, e.g., plasma density, temperature, velocity, and excited magnetic field, are essential for elucidating physical phenomena since we have been concentrating on next generation plasma propulsion methods, e.g., Rotating Magnetic Field plasma acceleration method, by characterizing the plasma performance. Moreover, in order to estimate the thrust performance in our experimental scheme, we have also mounted a thrust stand, which has a target type, on this movable instrument, and scanned the axial profile of the thrust performance in the presence of the external magnetic field generated by using permanent magnets, so as to investigate the plasma captured in a stand area, considering the divergent field lines in the downstream region of a generation antenna. In this paper, we will introduce the novel measurement instrument and describe how to measure these parameters.

  15. Measurement of Impact Acceleration: Mouthpiece Accelerometer Versus Helmet Accelerometer

    PubMed Central

    Higgins, Michael; Halstead, P. David; Snyder-Mackler, Lynn; Barlow, David

    2007-01-01

    Context: Instrumented helmets have been used to estimate impact acceleration imparted to the head during helmet impacts. These instrumented helmets may not accurately measure the actual amount of acceleration experienced by the head due to factors such as helmet-to-head fit. Objective: To determine if an accelerometer attached to a mouthpiece (MP) provides a more accurate representation of headform center of gravity (HFCOG) acceleration during impact than does an accelerometer attached to a helmet fitted on the headform. Design: Single-factor research design in which the independent variable was accelerometer position (HFCOG, helmet, MP) and the dependent variables were g and Severity Index (SI). Setting: Independent impact research laboratory. Intervention(s): The helmeted headform was dropped (n = 168) using a National Operating Committee on Standards for Athletic Equipment (NOCSAE) drop system from the standard heights and impact sites according to NOCSAE test standards. Peak g and SI were measured for each accelerometer position during impact. Main Outcome Measures: Upon impact, the peak g and SI were recorded for each accelerometer location. Results: Strong relationships were noted for HFCOG and MP measures, and significant differences were seen between HFCOG and helmet g measures and HFCOG and helmet SI measures. No statistically significant differences were noted between HFCOG and MP g and SI measures. Regression analyses showed a significant relationship between HFCOG and MP measures but not between HFCOG and helmet measures. Conclusions: Upon impact, MP acceleration (g) and SI measurements were closely related to and more accurate in measuring HFCOG g and SI than helmet measurements. The MP accelerometer is a valid method for measuring head acceleration. PMID:17597937

  16. Method and apparatus for measuring gravitational acceleration utilizing a high temperature superconducting bearing

    DOEpatents

    Hull, John R.

    2000-01-01

    Gravitational acceleration is measured in all spatial dimensions with improved sensitivity by utilizing a high temperature superconducting (HTS) gravimeter. The HTS gravimeter is comprised of a permanent magnet suspended in a spaced relationship from a high temperature superconductor, and a cantilever having a mass at its free end is connected to the permanent magnet at its fixed end. The permanent magnet and superconductor combine to form a bearing platform with extremely low frictional losses, and the rotational displacement of the mass is measured to determine gravitational acceleration. Employing a high temperature superconductor component has the significant advantage of having an operating temperature at or below 77K, whereby cooling may be accomplished with liquid nitrogen.

  17. Influence of tungsten fiber’s slow drift on the measurement of G with angular acceleration method

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

    Luo, Jie; Wu, Wei-Huang; Zhan, Wen-Ze

    In the measurement of the gravitational constant G with angular acceleration method, the equilibrium position of torsion pendulum with tungsten fiber undergoes a linear slow drift, which results in a quadratic slow drift on the angular velocity of the torsion balance turntable under feedback control unit. The accurate amplitude determination of the useful angular acceleration signal with known frequency is biased by the linear slow drift and the coupling effect of the drifting equilibrium position and the room fixed gravitational background signal. We calculate the influences of the linear slow drift and the complex coupling effect on the value ofmore » G, respectively. The result shows that the bias of the linear slow drift on G is 7 ppm, and the influence of the coupling effect is less than 1 ppm.« less

  18. Measurement of acceleration while walking as an automated method for gait assessment in dairy cattle.

    PubMed

    Chapinal, N; de Passillé, A M; Pastell, M; Hänninen, L; Munksgaard, L; Rushen, J

    2011-06-01

    The aims were to determine whether measures of acceleration of the legs and back of dairy cows while they walk could help detect changes in gait or locomotion associated with lameness and differences in the walking surface. In 2 experiments, 12 or 24 multiparous dairy cows were fitted with five 3-dimensional accelerometers, 1 attached to each leg and 1 to the back, and acceleration data were collected while cows walked in a straight line on concrete (experiment 1) or on both concrete and rubber (experiment 2). Cows were video-recorded while walking to assess overall gait, asymmetry of the steps, and walking speed. In experiment 1, cows were selected to maximize the range of gait scores, whereas no clinically lame cows were enrolled in experiment 2. For each accelerometer location, overall acceleration was calculated as the magnitude of the 3-dimensional acceleration vector and the variance of overall acceleration, as well as the asymmetry of variance of acceleration within the front and rear pair of legs. In experiment 1, the asymmetry of variance of acceleration in the front and rear legs was positively correlated with overall gait and the visually assessed asymmetry of the steps (r ≥ 0.6). Walking speed was negatively correlated with the asymmetry of variance of the rear legs (r=-0.8) and positively correlated with the acceleration and the variance of acceleration of each leg and back (r ≥ 0.7). In experiment 2, cows had lower gait scores [2.3 vs. 2.6; standard error of the difference (SED)=0.1, measured on a 5-point scale] and lower scores for asymmetry of the steps (18.0 vs. 23.1; SED=2.2, measured on a continuous 100-unit scale) when they walked on rubber compared with concrete, and their walking speed increased (1.28 vs. 1.22 m/s; SED=0.02). The acceleration of the front (1.67 vs. 1.72 g; SED=0.02) and rear (1.62 vs. 1.67 g; SED=0.02) legs and the variance of acceleration of the rear legs (0.88 vs. 0.94 g; SED=0.03) were lower when cows walked on rubber

  19. CME Velocity and Acceleration Error Estimates Using the Bootstrap Method

    NASA Technical Reports Server (NTRS)

    Michalek, Grzegorz; Gopalswamy, Nat; Yashiro, Seiji

    2017-01-01

    The bootstrap method is used to determine errors of basic attributes of coronal mass ejections (CMEs) visually identified in images obtained by the Solar and Heliospheric Observatory (SOHO) mission's Large Angle and Spectrometric Coronagraph (LASCO) instruments. The basic parameters of CMEs are stored, among others, in a database known as the SOHO/LASCO CME catalog and are widely employed for many research studies. The basic attributes of CMEs (e.g. velocity and acceleration) are obtained from manually generated height-time plots. The subjective nature of manual measurements introduces random errors that are difficult to quantify. In many studies the impact of such measurement errors is overlooked. In this study we present a new possibility to estimate measurements errors in the basic attributes of CMEs. This approach is a computer-intensive method because it requires repeating the original data analysis procedure several times using replicate datasets. This is also commonly called the bootstrap method in the literature. We show that the bootstrap approach can be used to estimate the errors of the basic attributes of CMEs having moderately large numbers of height-time measurements. The velocity errors are in the vast majority small and depend mostly on the number of height-time points measured for a particular event. In the case of acceleration, the errors are significant, and for more than half of all CMEs, they are larger than the acceleration itself.

  20. Microgravity acceleration measurement and environment characterization science (17-IML-1)

    NASA Technical Reports Server (NTRS)

    1992-01-01

    The Space Acceleration Measurement System (SAMS) is a general purpose instrumentation system designed to measure the accelerations onboard the Shuttle Orbiter and Shuttle/Spacelab vehicles. These measurements are used to support microgravity experiments and investigation into the microgravity environment of the vehicle. Acceleration measurements can be made at locations remote from the SAMS main instrumentation unit by the use of up to three remote triaxial sensor heads. The prime objective for SAMS on the International Microgravity Lab (IML-1) mission will be to measure the accelerations experienced by the Fluid Experiment System (FES). The SAMS acceleration measurements for FES will be complemented by low level, low frequency acceleration measurements made by the Orbital Acceleration Research Experiment (OARE) installed on the shuttle. Secondary objectives for SAMS will be to measure accelerations at several specific locations to enable the acceleration transfer function of the Spacelab module to be analyzed. This analysis effort will be in conjunction with similar measurements analyses on other Spacelab missions.

  1. Three Component Velocity and Acceleration Measurement Using FLEET

    NASA Technical Reports Server (NTRS)

    Danehy, Paul M.; Bathel, Brett F.; Calvert, Nathan; Dogariu, Arthur; Miles, Richard P.

    2014-01-01

    The femtosecond laser electronic excitation and tagging (FLEET) method has been used to measure three components of velocity and acceleration for the first time. A jet of pure N2 issuing into atmospheric pressure air was probed by the FLEET system. The femtosecond laser was focused down to a point to create a small measurement volume in the flow. The long-lived lifetime of this fluorescence was used to measure the location of the tagged particles at different times. Simultaneous images of the flow were taken from two orthogonal views using a mirror assembly and a single intensified CCD camera, allowing two components of velocity to be measured in each view. These different velocity components were combined to determine three orthogonal velocity components. The differences between subsequent velocity components could be used to measure the acceleration. Velocity accuracy and precision were roughly estimated to be +/-4 m/s and +/-10 m/s respectively. These errors were small compared to the approx. 100 m/s velocity of the subsonic jet studied.

  2. Systems and methods for the magnetic insulation of accelerator electrodes in electrostatic accelerators

    DOEpatents

    Grisham, Larry R

    2013-12-17

    The present invention provides systems and methods for the magnetic insulation of accelerator electrodes in electrostatic accelerators. Advantageously, the systems and methods of the present invention improve the practically obtainable performance of these electrostatic accelerators by addressing, among other things, voltage holding problems and conditioning issues. The problems and issues are addressed by flowing electric currents along these accelerator electrodes to produce magnetic fields that envelope the accelerator electrodes and their support structures, so as to prevent very low energy electrons from leaving the surfaces of the accelerator electrodes and subsequently picking up energy from the surrounding electric field. In various applications, this magnetic insulation must only produce modest gains in voltage holding capability to represent a significant achievement.

  3. SAMS Acceleration Measurements on MIR

    NASA Technical Reports Server (NTRS)

    Moskowitz, Milton E.; Hrovat, Kenneth; Finkelstein, Robert; Reckart, Timothy

    1997-01-01

    During NASA Increment 3 (September 1996 to January 1997), about 5 gigabytes of acceleration data were collected by the Space Acceleration Measurement System (SAMS) onboard the Russian Space Station, Mir. The data were recorded on 11 optical disks and were returned to Earth on STS-81. During this time, SAMS data were collected in the Priroda module to support the following experiments: the Mir Structural Dynamics Experiment (MiSDE) and Binary Colloidal Alloy Tests (BCAT). This report points out some of the salient features of the microgravity environment to which these experiments were exposed. Also documented are mission events of interest such as the docked phase of STS-81 operations, a Progress engine burn, attitude control thruster operation, and crew exercise. Also included are a description of the Mir module orientations, and the panel notations within the modules. This report presents an overview of the SAMS acceleration measurements recorded by 10 Hz and 100 Hz sensor heads. Variations in the acceleration environment caused by unique activities such as crew exercise and life-support fans are presented. The analyses included herein complement those presented in previous mission summary reports published by the Principal Investigator Microgravity Services (PIMS) group.

  4. Measurement of Coriolis Acceleration with a Smartphone

    ERIC Educational Resources Information Center

    Shaku, Asif; Kraft, Jakob

    2016-01-01

    Undergraduate physics laboratories seldom have experiments that measure the Coriolis acceleration. This has traditionally been the case owing to the inherent complexities of making such measurements. Articles on the experimental determination of the Coriolis acceleration are few and far between in the physics literature. However, because modern…

  5. Space Acceleration Measurement System-II

    NASA Technical Reports Server (NTRS)

    Foster, William

    2009-01-01

    Space Acceleration Measurement System (SAMS-II) is an ongoing study of the small forces (vibrations and accelerations) on the ISS that result from the operation of hardware, crew activities, as well as dockings and maneuvering. Results will be used to generalize the types of vibrations affecting vibration-sensitive experiments. Investigators seek to better understand the vibration environment on the space station to enable future research.

  6. Recovering bridge deflections from collocated acceleration and strain measurements

    NASA Astrophysics Data System (ADS)

    Bell, M.; Ma, T. W.; Xu, N. S.

    2015-04-01

    In this research, an internal model based method is proposed to estimate the displacement profile of a bridge subjected to a moving traffic load using a combination of acceleration and strain measurements. The structural response is assumed to be within the linear range. The deflection profile is assumed to be dominated by the fundamental mode of the bridge, therefore only requiring knowledge of the first mode. This still holds true under a multiple vehicle loading situation as the high mode shapes don't impact the over all response of the structure. Using the structural modal parameters and partial knowledge of the moving vehicle load, the internal models of the structure and the moving load can be respectively established, which can be used to form an autonomous state-space representation of the system. The structural displacements, velocities, and accelerations are the states of such a system, and it is fully observable when the measured output contains structural accelerations and strains. Reliable estimates of structural displacements are obtained using the standard Kalman filtering technique. The effectiveness and robustness of the proposed method has been demonstrated and evaluated via numerical simulation of a simply supported single span concrete bridge subjected to a moving traffic load.

  7. Measurement of Coriolis Acceleration with a Smartphone

    NASA Astrophysics Data System (ADS)

    Shakur, Asif; Kraft, Jakob

    2016-05-01

    Undergraduate physics laboratories seldom have experiments that measure the Coriolis acceleration. This has traditionally been the case owing to the inherent complexities of making such measurements. Articles on the experimental determination of the Coriolis acceleration are few and far between in the physics literature. However, because modern smartphones come with a raft of built-in sensors, we have a unique opportunity to experimentally determine the Coriolis acceleration conveniently in a pedagogically enlightening environment at modest cost by using student-owned smartphones. Here we employ the gyroscope and accelerometer in a smartphone to verify the dependence of Coriolis acceleration on the angular velocity of a rotatingtrack and the speed of the sliding smartphone.

  8. Measured emittance dependence on injection method in laser plasma accelerators

    NASA Astrophysics Data System (ADS)

    Barber, Samuel; van Tilborg, Jeroen; Schroeder, Carl; Lehe, Remi; Tsai, Hai-En; Swanson, Kelly; Steinke, Sven; Nakamura, Kei; Geddes, Cameron; Benedetti, Carlo; Esarey, Eric; Leemans, Wim

    2017-10-01

    The success of many laser plasma accelerator (LPA) based applications relies on the ability to produce electron beams with excellent 6D brightness, where brightness is defined as the ratio of charge to the product of the three normalized emittances. As such, parametric studies of the emittance of LPA generated electron beams are essential. Profiting from a stable and tunable LPA setup, combined with a carefully designed single-shot transverse emittance diagnostic, we present a direct comparison of charge dependent emittance measurements of electron beams generated by two different injection mechanisms: ionization injection and shock induced density down-ramp injection. Notably, the measurements reveal that ionization injection results in significantly higher emittance. With the down-ramp injection configuration, emittances less than 1 micron at spectral charge densities up to 2 pC/MeV were measured. This work was supported by the U.S. DOE under Contract No. DE-AC02-05CH11231, by the NSF under Grant No. PHY-1415596, by the U.S. DOE NNSA, DNN R&D (NA22), and by the Gordon and Betty Moore Foundation under Grant ID GBMF4898.

  9. Monte Carlo method for calculating the radiation skyshine produced by electron accelerators

    NASA Astrophysics Data System (ADS)

    Kong, Chaocheng; Li, Quanfeng; Chen, Huaibi; Du, Taibin; Cheng, Cheng; Tang, Chuanxiang; Zhu, Li; Zhang, Hui; Pei, Zhigang; Ming, Shenjin

    2005-06-01

    Using the MCNP4C Monte Carlo code, the X-ray skyshine produced by 9 MeV, 15 MeV and 21 MeV electron linear accelerators were calculated respectively with a new two-step method combined with the split and roulette variance reduction technique. Results of the Monte Carlo simulation, the empirical formulas used for skyshine calculation and the dose measurements were analyzed and compared. In conclusion, the skyshine dose measurements agreed reasonably with the results computed by the Monte Carlo method, but deviated from computational results given by empirical formulas. The effect on skyshine dose caused by different structures of accelerator head is also discussed in this paper.

  10. Atomic References for Measuring Small Accelerations

    NASA Technical Reports Server (NTRS)

    Maleki, Lute; Yu, Nan

    2009-01-01

    Accelerometer systems that would combine the best features of both conventional (e.g., mechanical) accelerometers and atom interferometer accelerometers (AIAs) have been proposed. These systems are intended mainly for use in scientific research aboard spacecraft but may also be useful on Earth in special military, geological, and civil-engineering applications. Conventional accelerometers can be sensitive, can have high dynamic range, and can have high frequency response, but they lack accuracy and long-term stability. AIAs have low frequency response, but they offer high sensitivity, and high accuracy for measuring small accelerations. In a system according to the proposal, a conventional accelerometer would be used to perform short-term measurements of higher-frequency components of acceleration, while an AIA would be used to provide consistent calibration of, and correction of errors in, the measurements of the conventional accelerometer in the lower-frequency range over the long term. A brief description of an AIA is prerequisite to a meaningful description of a system according to the proposal. An AIA includes a retroreflector next to one end of a cell that contains a cold cloud of atoms in an ultrahigh vacuum. The atoms in the cloud are in free fall. The retroreflector is mounted on the object, the acceleration of which is to be measured. Raman laser beams are directed through the cell from the end opposite the retroreflector, then pass back through the cell after striking the retroreflector. The Raman laser beams together with the cold atoms measure the relative acceleration, through the readout of the AIA, between the cold atoms and the retroreflector.

  11. 5 CFR 1315.5 - Accelerated payment methods.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 5 Administrative Personnel 3 2012-01-01 2012-01-01 false Accelerated payment methods. 1315.5 Section 1315.5 Administrative Personnel OFFICE OF MANAGEMENT AND BUDGET OMB DIRECTIVES PROMPT PAYMENT § 1315.5 Accelerated payment methods. (a) A single invoice under $2,500. Payments may be made as soon as...

  12. 5 CFR 1315.5 - Accelerated payment methods.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 5 Administrative Personnel 3 2011-01-01 2011-01-01 false Accelerated payment methods. 1315.5 Section 1315.5 Administrative Personnel OFFICE OF MANAGEMENT AND BUDGET OMB DIRECTIVES PROMPT PAYMENT § 1315.5 Accelerated payment methods. (a) A single invoice under $2,500. Payments may be made as soon as...

  13. 5 CFR 1315.5 - Accelerated payment methods.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 5 Administrative Personnel 3 2010-01-01 2010-01-01 false Accelerated payment methods. 1315.5 Section 1315.5 Administrative Personnel OFFICE OF MANAGEMENT AND BUDGET OMB DIRECTIVES PROMPT PAYMENT § 1315.5 Accelerated payment methods. (a) A single invoice under $2,500. Payments may be made as soon as...

  14. Radionuclide measurements by accelerator mass spectrometry at Arizona

    NASA Technical Reports Server (NTRS)

    Jull, A. J. T.; Donahue, D. J.; Zabel, T. H.

    1986-01-01

    Over the past years, Tandem Accelerator Mass Spectrometry (TAMS) has become established as an important method for radionuclide analysis. In the Arizona system the accelerator is operated at a thermal voltage of 1.8MV for C-14 analysis, and 1.6 to 2MV for Be-10. Samples are inserted into a cesium sputter ion source in solid form. Negative ions sputtered from the target are accelerated to about 25kV, and the injection magnet selects ions of a particular mass. Ions of the 3+ charge state, having an energy of about 9MeV are selected by an electrostatic deflector, surviving ions pass through two magnets, where only ions of the desired mass-energy product are selected. The final detector is a combination ionization chamber to measure energy loss (and hence, Z), and a silicon surface-barrier detector which measures residual energy. After counting the trace iosotope for a fixed time, the injected ions are switched to the major isotope used for normalization. These ions are deflected into a Faraday cup after the first high-energy magnet. Repeated measurements of the isotope ratio of both sample and standards results in a measurement of the concentration of the radionuclide. Recent improvements in sample preparation for C-14 make preparation of high-beam current graphite targets directly from CO2 feasible. Except for some measurements of standards and backgrounds for Be-10 measurements to date have been on C-14. Although most results have been in archaeology and quaternary geology, studies have been expanded to include cosmogenic C-14 in meteorites. The data obtained so far tend to confirm the antiquity of Antarctic meteorites from the Allan Hills site. Data on three samples of Yamato meteorites gave terrestrial ages of between about 3 and 22 thousand years.

  15. Space Acceleration Measurement System (SAMS)/Orbital Acceleration Research Experiment (OARE)

    NASA Technical Reports Server (NTRS)

    Hakimzadeh, Roshanak

    1998-01-01

    The Life and Microgravity Spacelab (LMS) payload flew on the Orbiter Columbia on mission STS-78 from June 20th to July 7th, 1996. The LMS payload on STS-78 was dedicated to life sciences and microgravity experiments. Two accelerometer systems managed by the NASA Lewis Research Center (LERC) flew to support these experiments, namely the Orbital Acceleration Research Experiment (OARE) and the Space Acceleration Measurements System (SAMS). In addition, the Microgravity Measurement Assembly (NOAA), managed by the European Space Research and Technology Center (ESA/ESTEC), and sponsored by NASA, collected acceleration data in support of the experiments on-board the LMS mission. OARE downlinked real-time quasi-steady acceleration data, which was provided to the investigators. The SAMS recorded higher frequency data on-board for post-mission analysis. The MMA downlinked real-time quasi-steady as well as higher frequency acceleration data, which was provided to the investigators. The Principal Investigator Microgravity Services (PIMS) project at NASA LERC supports principal investigators of microgravity experiments as they evaluate the effects of varying acceleration levels on their experiments. A summary report was prepared by PIMS to furnish interested experiment investigators with a guide to evaluate the acceleration environment during STS-78, and as a means of identifying areas which require further study. The summary report provides an overview of the STS-78 mission, describes the accelerometer systems flown on this mission, discusses some specific analyses of the accelerometer data in relation to the various activities which occurred during the mission, and presents plots resulting from these analyses as a snapshot of the environment during the mission. Numerous activities occurred during the STS-78 mission that are of interest to the low-gravity community. Specific activities of interest during this mission were crew exercise, radiator deployment, Vernier Reaction

  16. Noninvasive acceleration measurements to characterize knee arthritis and chondromalacia.

    PubMed

    Reddy, N P; Rothschild, B M; Mandal, M; Gupta, V; Suryanarayanan, S

    1995-01-01

    Devising techniques and instrumentation for early detection of knee arthritis and chondromalacia presents a challenge in the domain of biomedical engineering. The purpose of the present investigation was to characterize normal knees and knees affected by osteoarthritis, rheumatoid arthritis, and chondromalacia using a set of noninvasive acceleration measurements. Ultraminiature accelerometers were placed on the skin over the patella in four groups of subjects, and acceleration measurements were obtained during leg rotation. Acceleration measurements were significantly different in the four groups of subjects in the time and frequency domains. Power spectral analysis revealed that the average power was significantly different for these groups over a 100-500 Hz range. Noninvasive acceleration measurements can characterize the normal, arthritis, and chondromalacia knees. However, a study on a larger group of subjects is indicated.

  17. Evolutionary optimization methods for accelerator design

    NASA Astrophysics Data System (ADS)

    Poklonskiy, Alexey A.

    Many problems from the fields of accelerator physics and beam theory can be formulated as optimization problems and, as such, solved using optimization methods. Despite growing efficiency of the optimization methods, the adoption of modern optimization techniques in these fields is rather limited. Evolutionary Algorithms (EAs) form a relatively new and actively developed optimization methods family. They possess many attractive features such as: ease of the implementation, modest requirements on the objective function, a good tolerance to noise, robustness, and the ability to perform a global search efficiently. In this work we study the application of EAs to problems from accelerator physics and beam theory. We review the most commonly used methods of unconstrained optimization and describe the GATool, evolutionary algorithm and the software package, used in this work, in detail. Then we use a set of test problems to assess its performance in terms of computational resources, quality of the obtained result, and the tradeoff between them. We justify the choice of GATool as a heuristic method to generate cutoff values for the COSY-GO rigorous global optimization package for the COSY Infinity scientific computing package. We design the model of their mutual interaction and demonstrate that the quality of the result obtained by GATool increases as the information about the search domain is refined, which supports the usefulness of this model. We Giscuss GATool's performance on the problems suffering from static and dynamic noise and study useful strategies of GATool parameter tuning for these and other difficult problems. We review the challenges of constrained optimization with EAs and methods commonly used to overcome them. We describe REPA, a new constrained optimization method based on repairing, in exquisite detail, including the properties of its two repairing techniques: REFIND and REPROPT. We assess REPROPT's performance on the standard constrained

  18. Application of real-time digitization techniques in beam measurement for accelerators

    NASA Astrophysics Data System (ADS)

    Zhao, Lei; Zhan, Lin-Song; Gao, Xing-Shun; Liu, Shu-Bin; An, Qi

    2016-04-01

    Beam measurement is very important for accelerators. In this paper, modern digital beam measurement techniques based on IQ (In-phase & Quadrature-phase) analysis are discussed. Based on this method and high-speed high-resolution analog-to-digital conversion, we have completed three beam measurement electronics systems designed for the China Spallation Neutron Source (CSNS), Shanghai Synchrotron Radiation Facility (SSRF), and Accelerator Driven Sub-critical system (ADS). Core techniques of hardware design and real-time system calibration are discussed, and performance test results of these three instruments are also presented. Supported by National Natural Science Foundation of China (11205153, 10875119), Knowledge Innovation Program of the Chinese Academy of Sciences (KJCX2-YW-N27), and the Fundamental Research Funds for the Central Universities (WK2030040029),and the CAS Center for Excellence in Particle Physics (CCEPP).

  19. Absolute acceleration measurements on STS-50 from the Orbital Acceleration Research Experiment (OARE)

    NASA Technical Reports Server (NTRS)

    Blanchard, Robert C.; Nicholson, John Y.; Ritter, James R.

    1994-01-01

    Orbital Acceleration Research Experiment (OARE) data on Space Transportation System (STS)-50 have been examined in detail during a 2-day time period. Absolute acceleration levels have been derived at the OARE location, the orbiter center-of-gravity, and at the STS-50 spacelab Crystal Growth Facility. During the interval, the tri-axial OARE raw telemetered acceleration measurements have been filtered using a sliding trimmed mean filter in order to remove large acceleration spikes (e.g., thrusters) and reduce the noise. Twelve OARE measured biases in each acceleration channel during the 2-day interval have been analyzed and applied to the filtered data. Similarly, the in situ measured x-axis scale factors in the sensor's most sensitive range were also analyzed and applied to the data. Due to equipment problem(s) on this flight, both y- and z-axis sensitive range scale factors were determined in a separate process using orbiter maneuvers and subsequently applied to the data. All known significant low-frequency corrections at the OARE location (i.e., both vertical and horizontal gravity-gradient, and rotational effects) were removed from the filtered data in order to produce the acceleration components at the orbiter center-of-gravity, which are the aerodynamic signals along each body axis. Results indicate that there is a force being applied to the Orbiter in addition to the aerodynamic forces. The OARE instrument and all known gravitational and electromagnetic forces have been reexamined, but none produces the observed effect. Thus, it is tentatively concluded that the orbiter is creating the environment observed. At least part of this force is thought to be due to the Flash Evaporator System.

  20. Improvement of Space Shuttle Main Engine Low Frequency Acceleration Measurements

    NASA Technical Reports Server (NTRS)

    Stec, Robert C.

    1999-01-01

    The noise floor of low frequency acceleration data acquired on the Space Shuttle Main Engines is higher than desirable. Difficulties of acquiring high quality acceleration data on this engine are discussed. The approach presented in this paper for reducing the acceleration noise floor focuses on a search for an accelerometer more capable of measuring low frequency accelerations. An overview is given of the current measurement system used to acquire engine vibratory data. The severity of vibration, temperature, and moisture environments are considered. Vibratory measurements from both laboratory and rocket engine tests are presented.

  1. Electrodeless plasma acceleration system using rotating magnetic field method

    NASA Astrophysics Data System (ADS)

    Furukawa, T.; Takizawa, K.; Kuwahara, D.; Shinohara, S.

    2017-11-01

    We have proposed Rotating Magnetic Field (RMF) acceleration method as one of electrodeless plasma accelerations. In our experimental scheme, plasma generated by an rf (radio frequency) antenna, is accelerated by RMF antennas, which consist of two-pair, opposed, facing coils, and these antennas are outside of a discharge tube. Therefore, there is no wear of electrodes, degrading the propulsion performance. Here, we will introduce our RMF acceleration system developed, including the experimental device, e.g., external antennas, a tapered quartz tube, a vacuum chamber, external magnets, and a pumping system. In addition, we can change RMF operation parameters (RMF applied current IRMF and RMF current phase difference ϕ, focusing on RMF current frequency fRMF) by adjusting matching conditions of RMF, and investigate the dependencies on plasma parameters (electron density ne and ion velocity vi); e.g., higher increases of ne and vi (˜360 % and 55 %, respectively) than previous experimental results were obtained by decreasing fRMF from 5 MHz to 0.7 MHz, whose RMF penetration condition was better according to Milroy's expression. Moreover, time-varying component of RMF has been measured directly to survey the penetration condition experimentally.

  2. Acceleration of boundary element method for linear elasticity

    NASA Astrophysics Data System (ADS)

    Zapletal, Jan; Merta, Michal; Čermák, Martin

    2017-07-01

    In this work we describe the accelerated assembly of system matrices for the boundary element method using the Intel Xeon Phi coprocessors. We present a model problem, provide a brief overview of its discretization and acceleration of the system matrices assembly using the coprocessors, and test the accelerated version using a numerical benchmark.

  3. Measurement of heat load density profile on acceleration grid in MeV-class negative ion accelerator.

    PubMed

    Hiratsuka, Junichi; Hanada, Masaya; Kojima, Atsushi; Umeda, Naotaka; Kashiwagi, Mieko; Miyamoto, Kenji; Yoshida, Masafumi; Nishikiori, Ryo; Ichikawa, Masahiro; Watanabe, Kazuhiro; Tobari, Hiroyuki

    2016-02-01

    To understand the physics of the negative ion extraction/acceleration, the heat load density profile on the acceleration grid has been firstly measured in the ITER prototype accelerator where the negative ions are accelerated to 1 MeV with five acceleration stages. In order to clarify the profile, the peripheries around the apertures on the acceleration grid were separated into thermally insulated 34 blocks with thermocouples. The spatial resolution is as low as 3 mm and small enough to measure the tail of the beam profile with a beam diameter of ∼16 mm. It was found that there were two peaks of heat load density around the aperture. These two peaks were also clarified to be caused by the intercepted negative ions and secondary electrons from detailed investigation by changing the beam optics and gas density profile. This is the first experimental result, which is useful to understand the trajectories of these particles.

  4. Preliminary OARE absolute acceleration measurements on STS-50

    NASA Technical Reports Server (NTRS)

    Blanchard, Robert C.; Nicholson, John Y.; Ritter, James

    1993-01-01

    On-orbit Orbital Acceleration Research Experiment (OARE) data on STS-50 was examined in detail during a 2-day time period. Absolute acceleration levels were derived at the OARE location, the orbiter center-of-gravity, and at the STS-50 spacelab Crystal Growth Facility. The tri-axial OARE raw acceleration measurements (i.e., telemetered data) during the interval were filtered using a sliding trimmed mean filter in order to remove large acceleration spikes (e.g., thrusters) and reduce the noise. Twelve OARE measured biases in each acceleration channel during the 2-day interval were analyzed and applied to the filtered data. Similarly, the in situ measured x-axis scale factors in the sensor's most sensitive range were also analyzed and applied to the data. Due to equipment problem(s) on this flight, both y- and z- axis sensitive range scale factors were determined in a separate process (using the OARE maneuver data) and subsequently applied to the data. All known significant low-frequency corrections at the OARE location (i.e., both vertical and horizontal gravity-gradient, and rotational effects) were removed from the filtered data in order to produce the acceleration components at the orbiter's center-of-gravity, which are the aerodynamic signals along each body axes. Results indicate that there is a force of unknown origin being applied to the Orbiter in addition to the aerodynamic forces. The OARE instrument and all known gravitational and electromagnetic forces were reexamined, but none produce the observed effect. Thus, it is tentatively concluded that the Orbiter is creating the environment observed.

  5. Compact all-fiber interferometer system for shock acceleration measurement

    NASA Astrophysics Data System (ADS)

    Zhao, Jiang; Pi, Shaohua; Hong, Guangwei; Zhao, Dong; Jia, Bo

    2013-08-01

    Acceleration measurement plays an important role in a variety of fields in science and engineering. In particular, the accurate, continuous and non-contact recording of the shock acceleration profiles of the free target surfaces is considered as a critical technique in shock physics. Various kinds of optical interferometers have been developed to monitor the motion of the surfaces of shocked targets since the 1960s, for instance, the velocity interferometer system for any reflector, the fiber optic accelerometer, the photonic Doppler velocimetry system and the displacement interferometer. However, most of such systems rely on the coherent quasi-monochromatic illumination and discrete optic elements, which are costly in setting-up and maintenance. In 1996, L. Levin et al reported an interferometric fiber-optic Doppler velocimeter with high-dynamic range, in which fiber-coupled components were used to replace the discrete optic elements. However, the fringe visibility of the Levin's system is low because of the coupled components, which greatly limits the reliability and accuracy in the shock measurement. In this paper, a compact all-fiber interferometer system for measuring the shock acceleration is developed and tested. The advantage of the system is that not only removes the non-interfering light and enhances the fringe visibility, but also reduces polarization induced signal fading and the polarization induced phase shift. Moreover, it also does not require a source of long coherence length. The system bases entirely on single-mode fiber optics and mainly consists of a polarization beam splitter, a faraday rotator, a depolarizer and a 3×3 single-mode fiber coupler which work at 1310 nm wavelength. The optical systems of the interferometer are described and the experimental results compared with a shock acceleration calibration system with a pneumatic exciter (PneuShockTM Model 9525C by The Modal Shop) are reported. In the shock acceleration test, the

  6. Kr II laser-induced fluorescence for measuring plasma acceleration.

    PubMed

    Hargus, W A; Azarnia, G M; Nakles, M R

    2012-10-01

    We present the application of laser-induced fluorescence of singly ionized krypton as a diagnostic technique for quantifying the electrostatic acceleration within the discharge of a laboratory cross-field plasma accelerator also known as a Hall effect thruster, which has heritage as spacecraft propulsion. The 728.98 nm Kr II transition from the metastable 5d(4)D(7/2) to the 5p(4)P(5/2)(∘) state was used for the measurement of laser-induced fluorescence within the plasma discharge. From these measurements, it is possible to measure velocity as krypton ions are accelerated from near rest to approximately 21 km/s (190 eV). Ion temperature and the ion velocity distributions may also be extracted from the fluorescence data since available hyperfine splitting data allow for the Kr II 5d(4)D(7/2)-5p(4)P(5/2)(∘) transition lineshape to be modeled. From the analysis, the fluorescence lineshape appears to be a reasonable estimate for the relatively broad ion velocity distributions. However, due to an apparent overlap of the ion creation and acceleration regions within the discharge, the distributed velocity distributions increase ion temperature determination uncertainty significantly. Using the most probable ion velocity as a representative, or characteristic, measure of the ion acceleration, overall propellant energy deposition, and effective electric fields may be calculated. With this diagnostic technique, it is possible to nonintrusively characterize the ion acceleration both within the discharge and in the plume.

  7. Calibration of a Six-Degree-of-Freedom Acceleration Measurement Device

    DOT National Transportation Integrated Search

    1994-12-01

    This report describes the calibration of a six-degree-of-freedom acceleration measurement system designed for use in the measurement of linear and angular head accelerations of anthropomorphic dummies during crash tests. The calibration methodology, ...

  8. Correction of static pressure on a research aircraft in accelerated flight using differential pressure measurements

    NASA Astrophysics Data System (ADS)

    Rodi, A. R.; Leon, D. C.

    2012-05-01

    Geometric altitude data from a combined Global Navigation Satellite System (GNSS) and inertial measurement unit (IMU) system on the University of Wyoming King Air research aircraft are used to estimate acceleration effects on static pressure measurement. Using data collected during periods of accelerated flight, comparison of measured pressure with that derived from GNSS/IMU geometric altitude show that errors exceeding 150 Pa can occur which is significant in airspeed and atmospheric air motion determination. A method is developed to predict static pressure errors from analysis of differential pressure measurements from a Rosemount model 858 differential pressure air velocity probe. The method was evaluated with a carefully designed probe towed on connecting tubing behind the aircraft - a "trailing cone" - in steady flight, and shown to have a precision of about ±10 Pa over a wide range of conditions including various altitudes, power settings, and gear and flap extensions. Under accelerated flight conditions, compared to the GNSS/IMU data, this algorithm predicts corrections to a precision of better than ±20 Pa. Some limiting factors affecting the precision of static pressure measurement on a research aircraft are examined.

  9. Accelerator mass spectrometry for measurement of long-lived radioisotopes.

    PubMed

    Elmore, D; Phillips, F M

    1987-05-01

    Particle accelerators, such as those built for research in nuclear physics, can also be used together with magnetic and electrostatic mass analyzers to measure rare isotopes at very low abundance ratios. All molecular ions can be eliminated when accelerated to energies of millions of electron volts. Some atomic isobars can be eliminated with the use of negative ions; others can be separated at high energies by measuring their rate of energy loss in a detector. The long-lived radioisotopes (10)Be, (14)C,(26)A1, 36Cl, and (129)1 can now be measured in small natural samples having isotopic abundances in the range 10(-12) to 10(- 5) and as few as 10(5) atoms. In the past few years, research applications of accelerator mass spectrometry have been concentrated in the earth sciences (climatology, cosmochemistry, environmental chemistry, geochronology, glaciology, hydrology, igneous petrogenesis, minerals exploration, sedimentology, and volcanology), in anthropology and archeology (radiocarbon dating), and in physics (searches for exotic particles and measurement of halflives). In addition, accelerator mass spectrometry may become an important tool for the materials and biological sciences.

  10. Accelerator Mass Spectrometry for Measurement of Long-Lived Radioisotopes

    NASA Astrophysics Data System (ADS)

    Elmore, David; Phillips, Fred M.

    1987-05-01

    Particle accelerators, such as those built for research in nuclear physics, can also be used together with magnetic and electrostatic mass analyzers to measure rare isotopes at very low abundance ratios. All molecular ions can be eliminated when accelerated to energies of millions of electron volts. Some atomic isobars can be eliminated with the use of negative ions; others can be separated at high energies by measuring their rate of energy loss in a detector. The long-lived radioisotopes 10Be, 14C, 26Al, 36Cl, and 129I can now be measured in small natural samples having isotopic abundances in the range 10-12 to 10-15 and as few as 105 atoms. In the past few years, research applications of accelerator mass spectrometry have been concentrated in the earth sciences (climatology, cosmochemistry, environmental chemistry, geochronology, glaciology, hydrology, igneous petrogenesis, minerals exploration, sedimentology, and volcanology), in anthropology and archeology (radiocarbon dating), and in physics (searches for exotic particles and measurement of half-lives). In addition, accelerator mass spectrometry may become an important tool for the materials and biological sciences.

  11. Regional alveolar partial pressure of oxygen measurement with parallel accelerated hyperpolarized gas MRI.

    PubMed

    Kadlecek, Stephen; Hamedani, Hooman; Xu, Yinan; Emami, Kiarash; Xin, Yi; Ishii, Masaru; Rizi, Rahim

    2013-10-01

    Alveolar oxygen tension (Pao2) is sensitive to the interplay between local ventilation, perfusion, and alveolar-capillary membrane permeability, and thus reflects physiologic heterogeneity of healthy and diseased lung function. Several hyperpolarized helium ((3)He) magnetic resonance imaging (MRI)-based Pao2 mapping techniques have been reported, and considerable effort has gone toward reducing Pao2 measurement error. We present a new Pao2 imaging scheme, using parallel accelerated MRI, which significantly reduces measurement error. The proposed Pao2 mapping scheme was computer-simulated and was tested on both phantoms and five human subjects. Where possible, correspondence between actual local oxygen concentration and derived values was assessed for both bias (deviation from the true mean) and imaging artifact (deviation from the true spatial distribution). Phantom experiments demonstrated a significantly reduced coefficient of variation using the accelerated scheme. Simulation results support this observation and predict that correspondence between the true spatial distribution and the derived map is always superior using the accelerated scheme, although the improvement becomes less significant as the signal-to-noise ratio increases. Paired measurements in the human subjects, comparing accelerated and fully sampled schemes, show a reduced Pao2 distribution width for 41 of 46 slices. In contrast to proton MRI, acceleration of hyperpolarized imaging has no signal-to-noise penalty; its use in Pao2 measurement is therefore always beneficial. Comparison of multiple schemes shows that the benefit arises from a longer time-base during which oxygen-induced depolarization modifies the signal strength. Demonstration of the accelerated technique in human studies shows the feasibility of the method and suggests that measurement error is reduced here as well, particularly at low signal-to-noise levels. Copyright © 2013 AUR. Published by Elsevier Inc. All rights reserved.

  12. Accelerated Test Method for Corrosion Protective Coatings Project

    NASA Technical Reports Server (NTRS)

    Falker, John; Zeitlin, Nancy; Calle, Luz

    2015-01-01

    This project seeks to develop a new accelerated corrosion test method that predicts the long-term corrosion protection performance of spaceport structure coatings as accurately and reliably as current long-term atmospheric exposure tests. This new accelerated test method will shorten the time needed to evaluate the corrosion protection performance of coatings for NASA's critical ground support structures. Lifetime prediction for spaceport structure coatings has a 5-year qualification cycle using atmospheric exposure. Current accelerated corrosion tests often provide false positives and negatives for coating performance, do not correlate to atmospheric corrosion exposure results, and do not correlate with atmospheric exposure timescales for lifetime prediction.

  13. Detecting sea-level hazards: Simple regression-based methods for calculating the acceleration of sea level

    USGS Publications Warehouse

    Doran, Kara S.; Howd, Peter A.; Sallenger,, Asbury H.

    2016-01-04

    Recent studies, and most of their predecessors, use tide gage data to quantify SL acceleration, ASL(t). In the current study, three techniques were used to calculate acceleration from tide gage data, and of those examined, it was determined that the two techniques based on sliding a regression window through the time series are more robust compared to the technique that fits a single quadratic form to the entire time series, particularly if there is temporal variation in the magnitude of the acceleration. The single-fit quadratic regression method has been the most commonly used technique in determining acceleration in tide gage data. The inability of the single-fit method to account for time-varying acceleration may explain some of the inconsistent findings between investigators. Properly quantifying ASL(t) from field measurements is of particular importance in evaluating numerical models of past, present, and future SLR resulting from anticipated climate change.

  14. Intrinsic beam emittance of laser-accelerated electrons measured by x-ray spectroscopic imaging.

    PubMed

    Golovin, G; Banerjee, S; Liu, C; Chen, S; Zhang, J; Zhao, B; Zhang, P; Veale, M; Wilson, M; Seller, P; Umstadter, D

    2016-04-19

    The recent combination of ultra-intense lasers and laser-accelerated electron beams is enabling the development of a new generation of compact x-ray light sources, the coherence of which depends directly on electron beam emittance. Although the emittance of accelerated electron beams can be low, it can grow due to the effects of space charge during free-space propagation. Direct experimental measurement of this important property is complicated by micron-scale beam sizes, and the presence of intense fields at the location where space charge acts. Reported here is a novel, non-destructive, single-shot method that overcame this problem. It employed an intense laser probe pulse, and spectroscopic imaging of the inverse-Compton scattered x-rays, allowing measurement of an ultra-low value for the normalized transverse emittance, 0.15 (±0.06) π mm mrad, as well as study of its subsequent growth upon exiting the accelerator. The technique and results are critical for designing multi-stage laser-wakefield accelerators, and generating high-brightness, spatially coherent x-rays.

  15. Intrinsic beam emittance of laser-accelerated electrons measured by x-ray spectroscopic imaging

    DOE PAGES

    Golovin, G.; Banerjee, S.; Liu, C.; ...

    2016-04-19

    Here, the recent combination of ultra-intense lasers and laser-accelerated electron beams is enabling the development of a new generation of compact x-ray light sources, the coherence of which depends directly on electron beam emittance. Although the emittance of accelerated electron beams can be low, it can grow due to the effects of space charge during free-space propagation. Direct experimental measurement of this important property is complicated by micron-scale beam sizes, and the presence of intense fields at the location where space charge acts. Reported here is a novel, non-destructive, single-shot method that overcame this problem. It employed an intense lasermore » probe pulse, and spectroscopic imaging of the inverse-Compton scattered x-rays, allowing measurement of an ultra-low value for the normalized transverse emittance, 0.15 (±0.06) π mm mrad, as well as study of its subsequent growth upon exiting the accelerator. The technique and results are critical for designing multi-stage laser-wakefield accelerators, and generating high-brightness, spatially coherent x-rays.« less

  16. C-14 content of ten meteorites measured by tandem accelerator mass spectrometry

    NASA Technical Reports Server (NTRS)

    Brown, R. M.; Andrews, H. R.; Ball, G. C.; Burn, N.; Imahori, Y.; Milton, J. C. D.; Fireman, E. L.

    1984-01-01

    Measurements of C-14 in three North American and seven Antarctic meteorites show in most cases that this cosmogenic isotope, which is tightly bound, was separated from absorbed atmospheric radiocarbon by stepwise heating extractions. The present upper limit to age determination by the accelerator method varies from 50,000 to 70,000 years, depending on the mass and carbon content of the sample. The natural limit caused by cosmic ray production of C-14 in silicate rocks at 2000 m elevation is estimated to be 55,000 + or - 5000 years. An estimation is also made of the 'weathering ages' of the Antarctic meteorites from the specific activity of loosely bound CO2 which is thought to be absorbed from the terrestrial atmosphere. Accelerator measurements are found to agree with previous low level counting measurements, but are more sensitive and precise.

  17. Plasma Acceleration by Rotating Magnetic Field Method using Helicon Source

    NASA Astrophysics Data System (ADS)

    Furukawa, Takeru; Shimura, Kaichi; Kuwahara, Daisuke; Shinohara, Shunjiro

    2017-10-01

    Electrodeless plasma thrusters are very promising due to no electrode damage, leading to realize further deep space exploration. As one of the important proposals, we have been concentrating on Rotating Magnetic Field (RMF) acceleration method. High-dense plasma (up to 1013 cm-3) can be generated by using a radio frequency (rf) external antenna, and also accelerated by an antenna wound around outside of a discharge tube. In this scheme, thrust increment is achieved by the axial Lorentz force caused by non linear effects. RMF penetration condition into plasma can be more satisfied than our previous experiment, by increasing RMF coil current and decreasing the RMF frequency, causing higher thrust and fuel efficiency. Measurements of AC RMF component s have been conducted to investigate the acceleration mechanism and the field penetration experimentally. This study has been partially supported by Grant-in-Aid for Scientific Research (B: 17H02995) from the Japan Society for the Promotion of Science.

  18. PARTICLE ACCELERATOR AND METHOD OF CONTROLLING THE TEMPERATURE THEREOF

    DOEpatents

    Neal, R.B.; Gallagher, W.J.

    1960-10-11

    A method and means for controlling the temperature of a particle accelerator and more particularly to the maintenance of a constant and uniform temperature throughout a particle accelerator is offered. The novel feature of the invention resides in the provision of two individual heating applications to the accelerator structure. The first heating application provided is substantially a duplication of the accelerator heat created from energization, this first application being employed only when the accelerator is de-energized thereby maintaining the accelerator temperature constant with regard to time whether the accelerator is energized or not. The second heating application provided is designed to add to either the first application or energization heat in a manner to create the same uniform temperature throughout all portions of the accelerator.

  19. Spectroscopic measurements of plasma emission light for plasma-based acceleration experiments

    NASA Astrophysics Data System (ADS)

    Filippi, F.; Anania, M. P.; Biagioni, A.; Chiadroni, E.; Cianchi, A.; Ferrario, M.; Mostacci, A.; Palumbo, L.; Zigler, A.

    2016-09-01

    Advanced particle accelerators are based on the excitation of large amplitude plasma waves driven by either electron or laser beams. Future experiments scheduled at the SPARC_LAB test facility aim to demonstrate the acceleration of high brightness electron beams through the so-called resonant Plasma Wakefield Acceleration scheme in which a train of electron bunches (drivers) resonantly excites wakefields into a preformed hydrogen plasma; the last bunch (witness) injected at the proper accelerating phase gains energy from the wake. The quality of the accelerated beam depends strongly on plasma density and its distribution along the acceleration length. The measurements of plasma density of the order of 1016-1017 cm-3 can be performed with spectroscopic measurements of the plasma-emitted light. The measured density distribution for hydrogen filled capillary discharge with both Balmer alpha and Balmer beta lines and shot-to-shot variation are here reported.

  20. 236U measurement with accelerator mass spectrometry at CIAE

    NASA Astrophysics Data System (ADS)

    Wang, Xianggao; Jiang, Shan; He, Ming; Dong, Kejun; Wang, Wei; Li, Chaoli; He, Guozhu; Li, Shizhuo; Gong, Jie; Lu, Liyuan; Wu, Shaoyong

    2010-07-01

    236U is a long-lived radioactive isotope which is produced principally by thermal neutron capture on 235U. 236U may be potentially applied in geological research and nuclear safeguards. Accelerator mass spectrometry is presently the most sensitive technique for the measurement of 236U and a measurement method for long-lived heavy ion 236U has been developed. The set-up uses a dedicated injector and the newly proposed 208Pb 16O2- molecular ions for the simulation of 236U ion transport. A sensitivity of lower than 10 -10 has been achieved for the isotopic ratio 236U/ 238U in present work.

  1. Measurement of absolute gravity acceleration in Firenze

    NASA Astrophysics Data System (ADS)

    de Angelis, M.; Greco, F.; Pistorio, A.; Poli, N.; Prevedelli, M.; Saccorotti, G.; Sorrentino, F.; Tino, G. M.

    2011-01-01

    This paper reports the results from the accurate measurement of the acceleration of gravity g taken at two separate premises in the Polo Scientifico of the University of Firenze (Italy). In these laboratories, two separate experiments aiming at measuring the Newtonian constant and testing the Newtonian law at short distances are in progress. Both experiments require an independent knowledge on the local value of g. The only available datum, pertaining to the italian zero-order gravity network, was taken more than 20 years ago at a distance of more than 60 km from the study site. Gravity measurements were conducted using an FG5 absolute gravimeter, and accompanied by seismic recordings for evaluating the noise condition at the site. The absolute accelerations of gravity at the two laboratories are (980 492 160.6 ± 4.0) μGal and (980 492 048.3 ± 3.0) μGal for the European Laboratory for Non-Linear Spectroscopy (LENS) and Dipartimento di Fisica e Astronomia, respectively. Other than for the two referenced experiments, the data here presented will serve as a benchmark for any future study requiring an accurate knowledge of the absolute value of the acceleration of gravity in the study region.

  2. Online beam energy measurement of Beijing electron positron collider II linear accelerator

    NASA Astrophysics Data System (ADS)

    Wang, S.; Iqbal, M.; Liu, R.; Chi, Y.

    2016-02-01

    This paper describes online beam energy measurement of Beijing Electron Positron Collider upgraded version II linear accelerator (linac) adequately. It presents the calculation formula, gives the error analysis in detail, discusses the realization in practice, and makes some verification. The method mentioned here measures the beam energy by acquiring the horizontal beam position with three beam position monitors (BPMs), which eliminates the effect of orbit fluctuation, and is much better than the one using the single BPM. The error analysis indicates that this online measurement has further potential usage such as a part of beam energy feedback system. The reliability of this method is also discussed and demonstrated in this paper.

  3. Online beam energy measurement of Beijing electron positron collider II linear accelerator.

    PubMed

    Wang, S; Iqbal, M; Liu, R; Chi, Y

    2016-02-01

    This paper describes online beam energy measurement of Beijing Electron Positron Collider upgraded version II linear accelerator (linac) adequately. It presents the calculation formula, gives the error analysis in detail, discusses the realization in practice, and makes some verification. The method mentioned here measures the beam energy by acquiring the horizontal beam position with three beam position monitors (BPMs), which eliminates the effect of orbit fluctuation, and is much better than the one using the single BPM. The error analysis indicates that this online measurement has further potential usage such as a part of beam energy feedback system. The reliability of this method is also discussed and demonstrated in this paper.

  4. Preliminary determination of Newtonian gravitational constant with angular acceleration feedback method

    PubMed Central

    Xue, Chao; Quan, Li-Di; Yang, Shan-Qing; Wang, Bing-Peng; Wu, Jun-Fei; Shao, Cheng-Gang; Tu, Liang-Cheng; Milyukov, Vadim; Luo, Jun

    2014-01-01

    This paper describes the preliminary measurement of the Newtonian gravitational constant G with the angular acceleration feedback method at HUST. The apparatus has been built, and preliminary measurement performed, to test all aspects of the experimental design, particularly the feedback function, which was recently discussed in detail by Quan et al. The experimental results show that the residual twist angle of the torsion pendulum at the signal frequency introduces 0.4 ppm to the value of G. The relative uncertainty of the angular acceleration of the turntable is approximately 100 ppm, which is mainly limited by the stability of the apparatus. Therefore, the experiment has been modified with three features: (i) the height of the apparatus is reduced almost by half, (ii) the aluminium shelves were replaced with shelves made from ultra-low expansion material and (iii) a perfect compensation of the laboratory-fixed gravitational background will be carried out. With these improvements, the angular acceleration is expected to be determined with an uncertainty of better than 10 ppm, and a reliable value of G with 20 ppm or below will be obtained in the near future. PMID:25201996

  5. Effectiveness of Variable-Gain Kalman Filter Based on Angle Error Calculated from Acceleration Signals in Lower Limb Angle Measurement with Inertial Sensors

    PubMed Central

    Watanabe, Takashi

    2013-01-01

    The wearable sensor system developed by our group, which measured lower limb angles using Kalman-filtering-based method, was suggested to be useful in evaluation of gait function for rehabilitation support. However, it was expected to reduce variations of measurement errors. In this paper, a variable-Kalman-gain method based on angle error that was calculated from acceleration signals was proposed to improve measurement accuracy. The proposed method was tested comparing to fixed-gain Kalman filter and a variable-Kalman-gain method that was based on acceleration magnitude used in previous studies. First, in angle measurement in treadmill walking, the proposed method measured lower limb angles with the highest measurement accuracy and improved significantly foot inclination angle measurement, while it improved slightly shank and thigh inclination angles. The variable-gain method based on acceleration magnitude was not effective for our Kalman filter system. Then, in angle measurement of a rigid body model, it was shown that the proposed method had measurement accuracy similar to or higher than results seen in other studies that used markers of camera-based motion measurement system fixing on a rigid plate together with a sensor or on the sensor directly. The proposed method was found to be effective in angle measurement with inertial sensors. PMID:24282442

  6. Accelerated in vitro release testing method for naltrexone loaded PLGA microspheres.

    PubMed

    Andhariya, Janki V; Choi, Stephanie; Wang, Yan; Zou, Yuan; Burgess, Diane J; Shen, Jie

    2017-03-30

    The objective of the present study was to develop a discriminatory and reproducible accelerated release testing method for naltrexone loaded parenteral polymeric microspheres. The commercially available naltrexone microsphere product (Vivitrol ® ) was used as the testing formulation in the in vitro release method development, and both sample-and-separate and USP apparatus 4 methods were investigated. Following an in vitro drug stability study, frequent media replacement and addition of anti-oxidant in the release medium were used to prevent degradation of naltrexone during release testing at "real-time" (37°C) and "accelerated" (45°C), respectively. The USP apparatus 4 method was more reproducible than the sample-and-separate method. In addition, the accelerated release profile obtained using USP apparatus 4 had a shortened release duration (within seven days), and good correlation with the "real-time" release profile. Lastly, the discriminatory ability of the developed accelerated release method was assessed using compositionally equivalent naltrexone microspheres with different release characteristics. The developed accelerated USP apparatus 4 release method was able to detect differences in the release characteristics of the prepared naltrexone microspheres. Moreover, a linear correlation was observed between the "real-time" and accelerated release profiles of all the formulations investigated, suggesting that the release mechanism(s) may be similar under both conditions. These results indicate that the developed accelerated USP apparatus 4 method has the potential to be an appropriate fast quality control tool for long-acting naltrexone PLGA microspheres. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. Summary Report of Mission Acceleration Measurements for STS-78. Launched June 20, 1996

    NASA Technical Reports Server (NTRS)

    Hakimzadeh, Roshanak; Hrovat, Kenneth; McPherson, Kevin M.; Moskowitz, Milton E.; Rogers, Melissa J. B.

    1997-01-01

    The microgravity environment of the Space Shuttle Columbia was measured during the STS-78 mission using accelerometers from three different instruments: the Orbital Acceleration Research Experiment, the Space Acceleration Measurement System and the Microgravity Measurement Assembly. The quasi-steady environment was also calculated in near real-time during the mission by the Microgravity Analysis Workstation. The Orbital Acceleration Research Experiment provided investigators with real-time quasi-steady acceleration measurements. The Space Acceleration Measurement System recorded higher frequency data on-board for post-mission analysis. The Microgravity Measurement Assembly provided investigators with real-time quasi-steady and higher frequency acceleration measurements. The Microgravity Analysis Workstation provided calculation of the quasi-steady environment. This calculation was presented to the science teams in real-time during the mission. The microgravity environment related to several different Orbiter, crew and experiment operations is presented and interpreted in this report. A radiator deploy, the Flight Control System checkout, and a vernier reaction control system reboost demonstration had minimal effects on the acceleration environment, with excitation of frequencies in the 0.01 to 10 Hz range. Flash Evaporator System venting had no noticeable effect on the environment while supply and waste water dumps caused excursions of 2 x lO(exp -6) to 4 x 10(exp -6) g in the Y(sub b) and Z(sub b) directions. Crew sleep and ergometer exercise periods can be clearly seen in the acceleration data, as expected. Accelerations related to the two Life Science Laboratory Equipment Refrigerator/Freezers were apparent in the data as are accelerations caused by the Johnson Space Center Projects Centrifuge. As on previous microgravity missions, several signals are present in the acceleration data for which a source has not been identified. The causes of these accelerations

  8. Precise charge measurement for laser plasma accelerators

    NASA Astrophysics Data System (ADS)

    Nakamura, Kei; Gonsalves, Anthony; Lin, Chen; Sokollik, Thomas; Shiraishi, Satomi; van Tilborg, Jeroen; Smith, Alan; Rodgers, Dave; Donahue, Rick; Byrne, Warren; Leemans, Wim

    2011-10-01

    A comprehensive study of charge diagnostics was conducted to verify their validity for measuring electron beams produced by laser plasma accelerators (LPAs). The electron energy dependence of a scintillating screen (Lanex Fast) was studied with sub-nanosecond electron beams ranging from 106 MeV to 1522 MeV at the Lawrence Berkeley National Laboratory Advanced Light Source (ALS) synchrotron booster accelerator. Using an integrating current transformer as a calibration reference, the sensitivity of the Lanex Fast was found to decrease by 1% per 100 MeV increase of the energy. By using electron beams from LPA, cross calibrations of the charge were carried out with an integrating current transformer, scintillating screen (Lanex from Kodak), and activation based measurement. The diagnostics agreed within ~8%, showing that they all can provide accurate charge measurements for LPAs provided necessary cares. Work supported by the Office of Science, Office of High Energy Physics, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.

  9. Three dimensional finite element methods: Their role in the design of DC accelerator systems

    NASA Astrophysics Data System (ADS)

    Podaru, Nicolae C.; Gottdang, A.; Mous, D. J. W.

    2013-04-01

    High Voltage Engineering has designed, built and tested a 2 MV dual irradiation system that will be applied for radiation damage studies and ion beam material modification. The system consists of two independent accelerators which support simultaneous proton and electron irradiation (energy range 100 keV - 2 MeV) of target sizes of up to 300 × 300 mm2. Three dimensional finite element methods were used in the design of various parts of the system. The electrostatic solver was used to quantify essential parameters of the solid-state power supply generating the DC high voltage. The magnetostatic solver and ray tracing were used to optimize the electron/ion beam transport. Close agreement between design and measurements of the accelerator characteristics as well as beam performance indicate the usefulness of three dimensional finite element methods during accelerator system design.

  10. Preliminary determination of Newtonian gravitational constant with angular acceleration feedback method.

    PubMed

    Xue, Chao; Quan, Li-Di; Yang, Shan-Qing; Wang, Bing-Peng; Wu, Jun-Fei; Shao, Cheng-Gang; Tu, Liang-Cheng; Milyukov, Vadim; Luo, Jun

    2014-10-13

    This paper describes the preliminary measurement of the Newtonian gravitational constant G with the angular acceleration feedback method at HUST. The apparatus has been built, and preliminary measurement performed, to test all aspects of the experimental design, particularly the feedback function, which was recently discussed in detail by Quan et al. The experimental results show that the residual twist angle of the torsion pendulum at the signal frequency introduces 0.4 ppm to the value of G. The relative uncertainty of the angular acceleration of the turntable is approximately 100 ppm, which is mainly limited by the stability of the apparatus. Therefore, the experiment has been modified with three features: (i) the height of the apparatus is reduced almost by half, (ii) the aluminium shelves were replaced with shelves made from ultra-low expansion material and (iii) a perfect compensation of the laboratory-fixed gravitational background will be carried out. With these improvements, the angular acceleration is expected to be determined with an uncertainty of better than 10 ppm, and a reliable value of G with 20 ppm or below will be obtained in the near future. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

  11. On Solar Wind Origin and Acceleration: Measurements from ACE

    NASA Astrophysics Data System (ADS)

    Stakhiv, Mark; Lepri, Susan T.; Landi, Enrico; Tracy, Patrick; Zurbuchen, Thomas H.

    2016-10-01

    The origin and acceleration of the solar wind are still debated. In this paper, we search for signatures of the source region and acceleration mechanism of the solar wind in the plasma properties measured in situ by the Advanced Composition Explorer spacecraft. Using the elemental abundances as a proxy for the source region and the differential velocity and ion temperature ratios as a proxy for the acceleration mechanism, we are able to identify signatures pointing toward possible source regions and acceleration mechanisms. We find that the fast solar wind in the ecliptic plane is the same as that observed from the polar regions and is consistent with wave acceleration and coronal-hole origin. We also find that the slow wind is composed of two components: one similar to the fast solar wind (with slower velocity) and the other likely originating from closed magnetic loops. Both components of the slow solar wind show signatures of wave acceleration. From these findings, we draw a scenario that envisions two types of wind, with different source regions and release mechanisms, but the same wave acceleration mechanism.

  12. Accurate Measurement of Velocity and Acceleration of Seismic Vibrations near Nuclear Power Plants

    NASA Astrophysics Data System (ADS)

    Arif, Syed Javed; Imdadullah; Asghar, Mohammad Syed Jamil

    In spite of all prerequisite geological study based precautions, the sites of nuclear power plants are also susceptible to seismic vibrations and their consequent effects. The effect of the ongoing nuclear tragedy in Japan caused by an earthquake and its consequent tsunami on March 11, 2011 is currently beyond contemplations. It has led to a rethinking on nuclear power stations by various governments around the world. Therefore, the prediction of location and time of large earthquakes has regained a great importance. The earth crust is made up of several wide, thin and rigid plates like blocks which are in constant motion with respect to each other. A series of vibrations on the earth surface are produced by the generation of elastic seismic waves due to sudden rupture within the plates during the release of accumulated strain energy. The range of frequency of seismic vibrations is from 0 to 10 Hz. However, there appears a large variation in magnitude, velocity and acceleration of these vibrations. The response of existing or conventional methods of measurement of seismic vibrations is very slow, which is of the order of tens of seconds. A systematic and high resolution measurement of velocity and acceleration of these vibrations are useful to interpret the pattern of waves and their anomalies more accurately, which are useful for the prediction of an earthquake. In the proposed work, a fast rotating magnetic field (RMF) is used to measure the velocity and acceleration of seismic vibrations in the millisecond range. The broad spectrum of pulses within one second range, measured by proposed method, gives all possible values of instantaneous velocity and instantaneous acceleration of the seismic vibrations. The spectrum of pulses in millisecond range becomes available which is useful to measure the pattern of fore shocks to predict the time and location of large earthquakes more accurately. Moreover, instead of average, the peak values of these quantities are helpful

  13. Accelerated Learning: Madness with a Method.

    ERIC Educational Resources Information Center

    Zemke, Ron

    1995-01-01

    Accelerated learning methods have evolved into a variety of holistic techniques that involve participants in the learning process and overcome negative attitudes about learning. These components are part of the mix: the brain, learning environment, music, imaginative activities, suggestion, positive mental state, the arts, multiple intelligences,…

  14. Accelerated in-vitro release testing methods for extended-release parenteral dosage forms.

    PubMed

    Shen, Jie; Burgess, Diane J

    2012-07-01

    This review highlights current methods and strategies for accelerated in-vitro drug release testing of extended-release parenteral dosage forms such as polymeric microparticulate systems, lipid microparticulate systems, in-situ depot-forming systems and implants. Extended-release parenteral dosage forms are typically designed to maintain the effective drug concentration over periods of weeks, months or even years. Consequently, 'real-time' in-vitro release tests for these dosage forms are often run over a long time period. Accelerated in-vitro release methods can provide rapid evaluation and therefore are desirable for quality control purposes. To this end, different accelerated in-vitro release methods using United States Pharmacopeia (USP) apparatus have been developed. Different mechanisms of accelerating drug release from extended-release parenteral dosage forms, along with the accelerated in-vitro release testing methods currently employed are discussed. Accelerated in-vitro release testing methods with good discriminatory ability are critical for quality control of extended-release parenteral products. Methods that can be used in the development of in-vitro-in-vivo correlation (IVIVC) are desirable; however, for complex parenteral products this may not always be achievable. © 2012 The Authors. JPP © 2012 Royal Pharmaceutical Society.

  15. Accelerated in vitro release testing methods for extended release parenteral dosage forms

    PubMed Central

    Shen, Jie; Burgess, Diane J.

    2012-01-01

    Objectives This review highlights current methods and strategies for accelerated in vitro drug release testing of extended release parenteral dosage forms such as polymeric microparticulate systems, lipid microparticulate systems, in situ depot-forming systems, and implants. Key findings Extended release parenteral dosage forms are typically designed to maintain the effective drug concentration over periods of weeks, months or even years. Consequently, “real-time” in vitro release tests for these dosage forms are often run over a long time period. Accelerated in vitro release methods can provide rapid evaluation and therefore are desirable for quality control purposes. To this end, different accelerated in vitro release methods using United States Pharmacopoeia (USP) apparatus have been developed. Different mechanisms of accelerating drug release from extended release parenteral dosage forms, along with the accelerated in vitro release testing methods currently employed are discussed. Conclusions Accelerated in vitro release testing methods with good discriminatory ability are critical for quality control of extended release parenteral products. Methods that can be used in the development of in vitro-in vivo correlation (IVIVC) are desirable, however for complex parenteral products this may not always be achievable. PMID:22686344

  16. Methods for extracting aerodynamic accelerations from Orbiter High Resolution Accelerometer Package flight data

    NASA Technical Reports Server (NTRS)

    Thompson, J. M.; Russell, J. W.; Blanchard, R. C.

    1987-01-01

    This report presents a process for extracting the aerodynamic accelerations of the Shuttle Orbiter Vehicle from the High Resolution Accelerometer Package (HiRAP) flight data during reentry. The methods for obtaining low-level aerodynamic accelerations, principally in the rarefied flow regime, are applied to 10 Orbiter flights. The extraction process is presented using data obtained from Space Transportation System Flight 32 (Mission 61-C) as a typical example. This process involves correcting the HiRAP measurements for the effects of temperature bias and instrument offset from the Orbiter center of gravity, and removing acceleration data during times they are affected by thruster firings. The corrected data are then made continuous and smooth and are further enhanced by refining the temperature bias correction and removing effects of the auxiliary power unit actuation. The resulting data are the current best estimate of the Orbiter aerodynamic accelerations during reentry and will be used for further analyses of the Orbiter aerodynamics and the upper atmosphere characteristics.

  17. Miniature piezoelectric triaxial accelerometer measures cranial accelerations

    NASA Technical Reports Server (NTRS)

    Deboo, G. J.; Rogallo, V. L.

    1966-01-01

    Tiny triaxial accelerometer whose sensing elements are piezoelectric ceramic beams measures human cranial accelerations when a subject is exposed to a centrifuge or other simulators of g environments. This device could be considered for application in dental, medical, and automotive safety research.

  18. ON SOLAR WIND ORIGIN AND ACCELERATION: MEASUREMENTS FROM ACE

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

    Stakhiv, Mark; Lepri, Susan T.; Landi, Enrico

    The origin and acceleration of the solar wind are still debated. In this paper, we search for signatures of the source region and acceleration mechanism of the solar wind in the plasma properties measured in situ by the Advanced Composition Explorer spacecraft. Using the elemental abundances as a proxy for the source region and the differential velocity and ion temperature ratios as a proxy for the acceleration mechanism, we are able to identify signatures pointing toward possible source regions and acceleration mechanisms. We find that the fast solar wind in the ecliptic plane is the same as that observed frommore » the polar regions and is consistent with wave acceleration and coronal-hole origin. We also find that the slow wind is composed of two components: one similar to the fast solar wind (with slower velocity) and the other likely originating from closed magnetic loops. Both components of the slow solar wind show signatures of wave acceleration. From these findings, we draw a scenario that envisions two types of wind, with different source regions and release mechanisms, but the same wave acceleration mechanism.« less

  19. Gravity Acceleration Measurements Using a Soundcard

    ERIC Educational Resources Information Center

    Abellan-Garcia, Francisco J.; Garcia-Gamuz, Jose Antonio; Valerdi-Perez, Ramon P.; Ibanez-Mengual, Jose A.

    2012-01-01

    The aim of this paper is to determine the acceleration due to gravity "g", using a simple and low-cost experimental device. The time taken for a metallic ball to travel a predetermined distance is measured and recorded by a series of optical sensors. Four pairs of sensors are placed along the external surface of a vertical methacrylate tube at…

  20. Measurement of Transverse Wakefields Induced by a Misaligned Positron Bunch in a Hollow Channel Plasma Accelerator.

    PubMed

    Lindstrøm, C A; Adli, E; Allen, J M; An, W; Beekman, C; Clarke, C I; Clayton, C E; Corde, S; Doche, A; Frederico, J; Gessner, S J; Green, S Z; Hogan, M J; Joshi, C; Litos, M; Lu, W; Marsh, K A; Mori, W B; O'Shea, B D; Vafaei-Najafabadi, N; Yakimenko, V

    2018-03-23

    Hollow channel plasma wakefield acceleration is a proposed method to provide high acceleration gradients for electrons and positrons alike: a key to future lepton colliders. However, beams which are misaligned from the channel axis induce strong transverse wakefields, deflecting beams and reducing the collider luminosity. This undesirable consequence sets a tight constraint on the alignment accuracy of the beam propagating through the channel. Direct measurements of beam misalignment-induced transverse wakefields are therefore essential for designing mitigation strategies. We present the first quantitative measurements of transverse wakefields in a hollow plasma channel, induced by an off-axis 20 GeV positron bunch, and measured with another 20 GeV lower charge trailing positron probe bunch. The measurements are largely consistent with theory.

  1. Measurement of Transverse Wakefields Induced by a Misaligned Positron Bunch in a Hollow Channel Plasma Accelerator

    NASA Astrophysics Data System (ADS)

    Lindstrøm, C. A.; Adli, E.; Allen, J. M.; An, W.; Beekman, C.; Clarke, C. I.; Clayton, C. E.; Corde, S.; Doche, A.; Frederico, J.; Gessner, S. J.; Green, S. Z.; Hogan, M. J.; Joshi, C.; Litos, M.; Lu, W.; Marsh, K. A.; Mori, W. B.; O'Shea, B. D.; Vafaei-Najafabadi, N.; Yakimenko, V.

    2018-03-01

    Hollow channel plasma wakefield acceleration is a proposed method to provide high acceleration gradients for electrons and positrons alike: a key to future lepton colliders. However, beams which are misaligned from the channel axis induce strong transverse wakefields, deflecting beams and reducing the collider luminosity. This undesirable consequence sets a tight constraint on the alignment accuracy of the beam propagating through the channel. Direct measurements of beam misalignment-induced transverse wakefields are therefore essential for designing mitigation strategies. We present the first quantitative measurements of transverse wakefields in a hollow plasma channel, induced by an off-axis 20 GeV positron bunch, and measured with another 20 GeV lower charge trailing positron probe bunch. The measurements are largely consistent with theory.

  2. GPU accelerated manifold correction method for spinning compact binaries

    NASA Astrophysics Data System (ADS)

    Ran, Chong-xi; Liu, Song; Zhong, Shuang-ying

    2018-04-01

    The graphics processing unit (GPU) acceleration of the manifold correction algorithm based on the compute unified device architecture (CUDA) technology is designed to simulate the dynamic evolution of the Post-Newtonian (PN) Hamiltonian formulation of spinning compact binaries. The feasibility and the efficiency of parallel computation on GPU have been confirmed by various numerical experiments. The numerical comparisons show that the accuracy on GPU execution of manifold corrections method has a good agreement with the execution of codes on merely central processing unit (CPU-based) method. The acceleration ability when the codes are implemented on GPU can increase enormously through the use of shared memory and register optimization techniques without additional hardware costs, implying that the speedup is nearly 13 times as compared with the codes executed on CPU for phase space scan (including 314 × 314 orbits). In addition, GPU-accelerated manifold correction method is used to numerically study how dynamics are affected by the spin-induced quadrupole-monopole interaction for black hole binary system.

  3. Wavefront-sensor-based electron density measurements for laser-plasma accelerators.

    PubMed

    Plateau, G R; Matlis, N H; Geddes, C G R; Gonsalves, A J; Shiraishi, S; Lin, C; van Mourik, R A; Leemans, W P

    2010-03-01

    Characterization of the electron density in laser produced plasmas is presented using direct wavefront analysis of a probe laser beam. The performance of a laser-driven plasma-wakefield accelerator depends on the plasma wavelength and hence on the electron density. Density measurements using a conventional folded-wave interferometer and using a commercial wavefront sensor are compared for different regimes of the laser-plasma accelerator. It is shown that direct wavefront measurements agree with interferometric measurements and, because of the robustness of the compact commercial device, offer greater phase sensitivity and straightforward analysis, improving shot-to-shot plasma density diagnostics.

  4. Wavefront-sensor-based electron density measurements for laser-plasma accelerators

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

    Plateau, Guillaume; Matlis, Nicholas; Geddes, Cameron

    2010-02-20

    Characterization of the electron density in laser produced plasmas is presented using direct wavefront analysis of a probe laser beam. The performance of a laser-driven plasma-wakefield accelerator depends on the plasma wavelength, hence on the electron density. Density measurements using a conventional folded-wave interferometer and using a commercial wavefront sensor are compared for different regimes of the laser-plasma accelerator. It is shown that direct wavefront measurements agree with interferometric measurements and, because of the robustness of the compact commercial device, have greater phase sensitivity, straightforward analysis, improving shot-to-shot plasma-density diagnostics.

  5. A new method in accelerating PROPELLER MRI.

    PubMed

    Li, Bing Keong; D'Arcy, Michael; Weber, Ewald; Crozier, Stuart

    2008-01-01

    In this work, a new method has been proposed to accelerate the PROPELLER MRI operation. The proposed method uses a rotary phased array coil and a new method in acquiring the k-space strips and preparing the complete k-space trajectories data set. It is numerically shown that for a 12 strips PROPELLER MR brain imaging sequence, the operation time can be reduced by four folds, with no apparent loss in the image quality.

  6. An Accelerated Method for Soldering Testing

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

    Han, Qingyou; Xu, Hanbing; Ried, Paul

    2007-01-01

    An accelerated method for testing die soldering has been developed. High intensity ultrasonic vibrations have been applied to simulate the die casting conditions such as high pressure and high molten metal velocity on the pin. The soldering tendency of steels and coated pins has been examined. The results suggest that in the low carbon steel/Al system, the onset of soldering is 60 times faster with ultrasonic vibration than that without ultrasonic vibration. In the H13/A380 system, the onset of soldering reaction is accelerated to between 30-60 times. Coatings significantly reduce the soldering tendency. For purposes of this study, several commercialmore » coatings from Balzers demonstrated the potential for increasing the service life of core pins between 15 and 180 times.« less

  7. Measurement of Transverse Wakefields Induced by a Misaligned Positron Bunch in a Hollow Channel Plasma Accelerator

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

    Lindstrom, C. A.; Adli, E.; Allen, J. M.

    Hollow channel plasma wakefield acceleration is a proposed method to provide high acceleration gradients for electrons and positrons alike: a key to future lepton colliders. However, beams which are misaligned from the channel axis induce strong transverse wakefields, deflecting beams and reducing the collider luminosity. This undesirable consequence sets a tight constraint on the alignment accuracy of the beam propagating through the channel. Direct measurements of beam misalignment-induced transverse wakefields are therefore essential for designing mitigation strategies. We present the first quantitative measurements of transverse wakefields in a hollow plasma channel, induced by an off-axis 20 GeV positron bunch, andmore » measured with another 20 GeV lower charge trailing positron probe bunch. Furthermore, the measurements are largely consistent with theory.« less

  8. Measurement of Transverse Wakefields Induced by a Misaligned Positron Bunch in a Hollow Channel Plasma Accelerator

    DOE PAGES

    Lindstrom, C. A.; Adli, E.; Allen, J. M.; ...

    2018-03-23

    Hollow channel plasma wakefield acceleration is a proposed method to provide high acceleration gradients for electrons and positrons alike: a key to future lepton colliders. However, beams which are misaligned from the channel axis induce strong transverse wakefields, deflecting beams and reducing the collider luminosity. This undesirable consequence sets a tight constraint on the alignment accuracy of the beam propagating through the channel. Direct measurements of beam misalignment-induced transverse wakefields are therefore essential for designing mitigation strategies. We present the first quantitative measurements of transverse wakefields in a hollow plasma channel, induced by an off-axis 20 GeV positron bunch, andmore » measured with another 20 GeV lower charge trailing positron probe bunch. Furthermore, the measurements are largely consistent with theory.« less

  9. Method for generating a plasma wave to accelerate electrons

    DOEpatents

    Umstadter, D.; Esarey, E.; Kim, J.K.

    1997-06-10

    The invention provides a method and apparatus for generating large amplitude nonlinear plasma waves, driven by an optimized train of independently adjustable, intense laser pulses. In the method, optimal pulse widths, interpulse spacing, and intensity profiles of each pulse are determined for each pulse in a series of pulses. A resonant region of the plasma wave phase space is found where the plasma wave is driven most efficiently by the laser pulses. The accelerator system of the invention comprises several parts: the laser system, with its pulse-shaping subsystem; the electron gun system, also called beam source, which preferably comprises photo cathode electron source and RF-LINAC accelerator; electron photo-cathode triggering system; the electron diagnostics; and the feedback system between the electron diagnostics and the laser system. The system also includes plasma source including vacuum chamber, magnetic lens, and magnetic field means. The laser system produces a train of pulses that has been optimized to maximize the axial electric field amplitude of the plasma wave, and thus the electron acceleration, using the method of the invention. 21 figs.

  10. Method for generating a plasma wave to accelerate electrons

    DOEpatents

    Umstadter, Donald; Esarey, Eric; Kim, Joon K.

    1997-01-01

    The invention provides a method and apparatus for generating large amplitude nonlinear plasma waves, driven by an optimized train of independently adjustable, intense laser pulses. In the method, optimal pulse widths, interpulse spacing, and intensity profiles of each pulse are determined for each pulse in a series of pulses. A resonant region of the plasma wave phase space is found where the plasma wave is driven most efficiently by the laser pulses. The accelerator system of the invention comprises several parts: the laser system, with its pulse-shaping subsystem; the electron gun system, also called beam source, which preferably comprises photo cathode electron source and RF-LINAC accelerator; electron photo-cathode triggering system; the electron diagnostics; and the feedback system between the electron diagnostics and the laser system. The system also includes plasma source including vacuum chamber, magnetic lens, and magnetic field means. The laser system produces a train of pulses that has been optimized to maximize the axial electric field amplitude of the plasma wave, and thus the electron acceleration, using the method of the invention.

  11. Theory and measurements of emittance preservation in plasma wakefield acceleration

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

    Frederico, Joel

    2016-12-01

    In this dissertation, we examine the preservation and measurement of emittance in the plasma wakefield acceleration blowout regime. Plasma wakefield acceleration (PWFA) is a revolutionary approach to accelerating charged particles that has been demonstrated to have the potential for gradients orders of magnitude greater than traditional approaches. The application of PWFA to the design of a linear collider will make new high energy physics research possible, but the design parameters must first be shown to be competitive with traditional methods. Emittance preservation is necessary in the design of a linear collider in order to maximize luminosity. We examine the conditionsmore » necessary for circular symmetry in the PWFA blowout regime, and demonstrate that current proposals meet these bounds. We also present an application of beam lamentation which describes the process of beam parameter and emittance matching. We show that the emittance growth saturates as a consequence of energy spread in the beam. The initial beam parameters determine the amount of emittance growth, while the contribution of energy spread is negligible. We also present a model for ion motion in the presence of a beam that is much more dense than the plasma. By combining the model of ion motion and emittance growth, we find the emittance growth due to ion motion is minimal in the case of marginal ion motion. In addition, we present a simulation that validates the ion motion model, which is under further development to examine emittance growth of both marginal and pronounced ion motion. Finally, we present a proof-of-concept of an emittance measurement which may enable the analysis of emittance preservation in future PWFA experiments.« less

  12. SAMS Acceleration Measurements on Mir (NASA Increment 4)

    NASA Technical Reports Server (NTRS)

    DeLombard, Richard

    1998-01-01

    During NASA Increment 4 (January to May 1997), about 5 gigabytes of acceleration data were collected by the Space Acceleration Measurements System (SAMS) onboard the Russian Space Station, Mir. The data were recorded on 28 optical disks which were returned to Earth on STS-84. During this increment, SAMS data were collected in the Priroda module to support the Mir Structural Dynamics Experiment (MiSDE), the Binary Colloidal Alloy Tests (BCAT), Angular Liquid Bridge (ALB), Candle Flames in Microgravity (CFM), Diffusion Controlled Apparatus Module (DCAM), Enhanced Dynamic Load Sensors (EDLS), Forced Flow Flame Spreading Test (FFFr), Liquid Metal Diffusion (LMD), Protein Crystal Growth in Dewar (PCG/Dewar), Queen's University Experiments in Liquid Diffusion (QUELD), and Technical Evaluation of MIM (TEM). This report points out some of the salient features of the microgravity environment to which these experiments were exposed. Also documented are mission events of interest such as the docked phase of STS-84 operations, a Progress engine bum, Soyuz vehicle docking and undocking, and Progress vehicle docking. This report presents an overview of the SAMS acceleration measurements recorded by 10 Hz and 100 Hz sensor heads. The analyses included herein complement those presented in previous summary reports prepared by the Principal Investigator Microgravity Services (PIMS) group.

  13. The Rim Inertial Measuring System (RIMS). [to measure angular rate and linear acceleration of a moving vehicle

    NASA Technical Reports Server (NTRS)

    Groom, N. J.

    1979-01-01

    The rim inertial measuring system (RIMS) is introduced and an approach for extracting angular rate and linear acceleration information from a RIMS unit is presented and discussed. The RIMS consists of one or more small annular momentum control devices (AMCDs), mounted in a strapped down configuration, which are used to measure angular rates and linear accelerations of a moving vehicle. An AMCD consists of a spinning rim, a set of noncontacting magnetic bearings for supporting the rim, and a noncontacting electromagnetic spin motor. The approach for extracting angular rate and linear acceleration information is for a single spacecraft mounted RIMS unit.

  14. A coarse-grid projection method for accelerating incompressible flow computations

    NASA Astrophysics Data System (ADS)

    San, Omer; Staples, Anne E.

    2013-01-01

    We present a coarse-grid projection (CGP) method for accelerating incompressible flow computations, which is applicable to methods involving Poisson equations as incompressibility constraints. The CGP methodology is a modular approach that facilitates data transfer with simple interpolations and uses black-box solvers for the Poisson and advection-diffusion equations in the flow solver. After solving the Poisson equation on a coarsened grid, an interpolation scheme is used to obtain the fine data for subsequent time stepping on the full grid. A particular version of the method is applied here to the vorticity-stream function, primitive variable, and vorticity-velocity formulations of incompressible Navier-Stokes equations. We compute several benchmark flow problems on two-dimensional Cartesian and non-Cartesian grids, as well as a three-dimensional flow problem. The method is found to accelerate these computations while retaining a level of accuracy close to that of the fine resolution field, which is significantly better than the accuracy obtained for a similar computation performed solely using a coarse grid. A linear acceleration rate is obtained for all the cases we consider due to the linear-cost elliptic Poisson solver used, with reduction factors in computational time between 2 and 42. The computational savings are larger when a suboptimal Poisson solver is used. We also find that the computational savings increase with increasing distortion ratio on non-Cartesian grids, making the CGP method a useful tool for accelerating generalized curvilinear incompressible flow solvers.

  15. SU-E-T-543: Measurement of Neutron Activation From Different High Energy Varian Linear Accelerators

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

    Thatcher, T; Madsen, S; Sudowe, R

    2015-06-15

    Purpose: Linear accelerators producing photons above 10 MeV may induce photonuclear reactions in high Z components of the accelerator. These liberated neutrons can then activate the structural components of the accelerator and other materials in the beam path through neutron capture reactions. The induced activity within the accelerator may contribute to additional dose to both patients and personnel. This project seeks to determine the total activity and activity per activated isotope following irradiation in different Varian accelerators at energies above 10 MeV. Methods: A Varian 21IX accelerator was used to irradiate a 30 cm × 30 cm × 20 cmmore » solid water phantom with 15 MV x-rays. The phantom was placed at an SSD of 100 cm and at the center of a 20 cm × 20 cm field. Activation induced gamma spectra were acquired over a 5 minute interval after 1 and 15 minutes from completion of the irradiation. All measurements were made using a CANBERRA Falcon 5000 Portable HPGe detector. The majority of measurements were made in scattering geometry with the detector situated at 90° to the incident beam, 30 cm from the side of the phantom and approximately 10 cm from the top. A 5 minute background count was acquired and automatically subtracted from all subsequent measurements. Photon spectra were acquired for both open and MLC fields. Results: Based on spectral signatures, nuclides have been identified and their activities calculated for both open and MLC fields. Preliminary analyses suggest that activities from the activation products in the microcurie range. Conclusion: Activation isotopes have been identified and their relative activities determined. These activities are only gross estimates since efficiencies have not been determined for this source-detector geometry. Current efforts are focused on accurate determination of detector efficiencies using Monte Carlo calculations.« less

  16. A reproducible accelerated in vitro release testing method for PLGA microspheres.

    PubMed

    Shen, Jie; Lee, Kyulim; Choi, Stephanie; Qu, Wen; Wang, Yan; Burgess, Diane J

    2016-02-10

    The objective of the present study was to develop a discriminatory and reproducible accelerated in vitro release method for long-acting PLGA microspheres with inner structure/porosity differences. Risperidone was chosen as a model drug. Qualitatively and quantitatively equivalent PLGA microspheres with different inner structure/porosity were obtained using different manufacturing processes. Physicochemical properties as well as degradation profiles of the prepared microspheres were investigated. Furthermore, in vitro release testing of the prepared risperidone microspheres was performed using the most common in vitro release methods (i.e., sample-and-separate and flow through) for this type of product. The obtained compositionally equivalent risperidone microspheres had similar drug loading but different inner structure/porosity. When microsphere particle size appeared similar, porous risperidone microspheres showed faster microsphere degradation and drug release compared with less porous microspheres. Both in vitro release methods investigated were able to differentiate risperidone microsphere formulations with differences in porosity under real-time (37 °C) and accelerated (45 °C) testing conditions. Notably, only the accelerated USP apparatus 4 method showed good reproducibility for highly porous risperidone microspheres. These results indicated that the accelerated USP apparatus 4 method is an appropriate fast quality control tool for long-acting PLGA microspheres (even with porous structures). Copyright © 2015 Elsevier B.V. All rights reserved.

  17. Accelerator-based method of producing isotopes

    DOEpatents

    Nolen, Jr., Jerry A.; Gomes, Itacil C.

    2015-11-03

    The invention provides a method using accelerators to produce radio-isotopes in high quantities. The method comprises: supplying a "core" of low-enrichment fissile material arranged in a spherical array of LEU combined with water moderator. The array is surrounded by substrates which serve as multipliers and moderators as well as neutron shielding substrates. A flux of neutrons enters the low-enrichment fissile material and causes fissions therein for a time sufficient to generate desired quantities of isotopes from the fissile material. The radio-isotopes are extracted from said fissile material by chemical processing or other means.

  18. Method for computationally efficient design of dielectric laser accelerator structures

    DOE PAGES

    Hughes, Tyler; Veronis, Georgios; Wootton, Kent P.; ...

    2017-06-22

    Here, dielectric microstructures have generated much interest in recent years as a means of accelerating charged particles when powered by solid state lasers. The acceleration gradient (or particle energy gain per unit length) is an important figure of merit. To design structures with high acceleration gradients, we explore the adjoint variable method, a highly efficient technique used to compute the sensitivity of an objective with respect to a large number of parameters. With this formalism, the sensitivity of the acceleration gradient of a dielectric structure with respect to its entire spatial permittivity distribution is calculated by the use of onlymore » two full-field electromagnetic simulations, the original and ‘adjoint’. The adjoint simulation corresponds physically to the reciprocal situation of a point charge moving through the accelerator gap and radiating. Using this formalism, we perform numerical optimizations aimed at maximizing acceleration gradients, which generate fabricable structures of greatly improved performance in comparison to previously examined geometries.« less

  19. Optics measurement and correction during beam acceleration in the Relativistic Heavy Ion Collider

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

    Liu, C.; Marusic, A.; Minty, M.

    2014-09-09

    To minimize operational complexities, setup of collisions in high energy circular colliders typically involves acceleration with near constant β-functions followed by application of strong focusing quadrupoles at the interaction points (IPs) for the final beta-squeeze. At the Relativistic Heavy Ion Collider (RHIC) beam acceleration and optics squeeze are performed simultaneously. In the past, beam optics correction at RHIC has taken place at injection and at final energy with some interpolation of corrections into the acceleration cycle. Recent measurements of the beam optics during acceleration and squeeze have evidenced significant beta-beats which if corrected could minimize undesirable emittance dilutions and maximizemore » the spin polarization of polarized proton beams by avoidance of higher-order multipole fields sampled by particles within the bunch. In this report the methodology now operational at RHIC for beam optics corrections during acceleration with simultaneous beta-squeeze will be presented together with measurements which conclusively demonstrate the superior beam control. As a valuable by-product, the corrections have minimized the beta-beat at the profile monitors so reducing the dominant error in and providing more precise measurements of the evolution of the beam emittances during acceleration.« less

  20. Measurements of 59Ni in meteorites by accelerator mass spectrometry

    NASA Astrophysics Data System (ADS)

    Paul, M.; Fifield, L. K.; Fink, D.; Albrecht, A.; Allan, G. L.; Herzog, G.; Tuniz, C.

    1993-10-01

    Isotopic abundances of the radionuclide 59Ni (T1/2 = 76000 yr) were measured by accelerator mass spectrometry with the 14UD Pelletron tandem accelerator at the Australian National University and a detection system solely based on a multianode ionization chamber. The sensitivity limit in the measurement of 59Ni isotopic abundances is 5 × 10-13, as determined by residual interferences from isobaric 59Co and isotopic 58Ni ions. Cosmogenic 59Ni abundances 59Ni/Ni = (8-20) × 10-12 were measured in four samples prepared from the metal phase of two meteorites (mesosiderites). The ratio of the 59Ni abundances to those measured for 41Ca in the silicate phase of the same samples, is in fair agreement with the ratio of the production rates via thermal-neutron capture on 58Ni and 40Ca.

  1. An Accelerated Release Method of Risperidone Loaded PLGA Microspheres with Good IVIVC.

    PubMed

    Hu, Xiaoqin; Zhang, Jianwei; Tang, Xuemei; Li, Mingyuan; Ma, Siyu; Liu, Cheng; Gao, Yue; Zhang, Yue; Liu, Yan; Yu, Fanglin; Yang, Yang; Guo, Jia; Li, Zhiping; Mei, Xingguo

    2018-01-01

    A long release period lasting several days or several weeks is always needed and thereby it is tedious and time consuming to screen formulations of such microspheres with so long release period and evaluate their release profiles in vitro with conventional long-term or "real-time" release method. So, an accelerated release testing of such system is necessary for formulation design as well as quality control purpose. The purpose of this study is to obtain an accelerated release method of risperidone loaded poly(lactic-co-glycolic acid) (PLGA) microspheres with good in vitro/in vivo correlation (IVIVC). Two formulations of risperidone loaded PLGA microspheres used for evaluating IVIVC were prepared by O/W method. The accelerated release condition was optimized by investigating the effect of pH, osmotic pressure, temperature and ethanol concentration on the release of risperidone from microspheres and the in vitro accelerated release profiles of risperidone from PLGA microspheres were obtained under this optimized accelerated release condition. The plasma concentration of risperidone were also detected after subcutaneous injection of risperidone loaded microspheres to rats. The in vivo cumulative absorption profiles were then calculated using Wagner-Nelson model, Loo- Riegelman model and numerical convolution model, respectively. The correlation between in vitro accelerated release and in vivo cumulative absorption were finally evaluated with Least Square Method. It was shown that temperature and ethanol concentration significantly affected the release of risperidone from the microspheres while pH and osmotic pressure of release media slightly affected the release behavior of risperidone. The in vitro release of risperidone from microspheres were finally undergone in PBS (pH7.0, 300mosm) with 20% (V/V) ethanol at 45°C. The sustained and complete release of risperidone was observed in both formulations under the accelerated release condition although these two release

  2. Assessment on the methods of measuring the tyre-road contact patch stresses

    NASA Astrophysics Data System (ADS)

    Anghelache, G.; Moisescu, A.-R.; Buretea, D.

    2017-08-01

    The paper reviews established and modern methods for investigating tri-axial stress distributions in the tyre-road contact patch. The authors used three methods of measuring stress distributions: strain gauge method; force sensing technique; acceleration measurements. Four prototypes of instrumented pins transducers involving mentioned measuring methods were developed. Data acquisitions of the contact patch stresses distributions were performed using each transducer with instrumented pin. The results are analysed and compared, underlining the advantages and drawbacks of each method. The experimental results indicate that the three methods are valuable.

  3. A comparison of acceleration methods for solving the neutron transport k-eigenvalue problem

    NASA Astrophysics Data System (ADS)

    Willert, Jeffrey; Park, H.; Knoll, D. A.

    2014-10-01

    Over the past several years a number of papers have been written describing modern techniques for numerically computing the dominant eigenvalue of the neutron transport criticality problem. These methods fall into two distinct categories. The first category of methods rewrite the multi-group k-eigenvalue problem as a nonlinear system of equations and solve the resulting system using either a Jacobian-Free Newton-Krylov (JFNK) method or Nonlinear Krylov Acceleration (NKA), a variant of Anderson Acceleration. These methods are generally successful in significantly reducing the number of transport sweeps required to compute the dominant eigenvalue. The second category of methods utilize Moment-Based Acceleration (or High-Order/Low-Order (HOLO) Acceleration). These methods solve a sequence of modified diffusion eigenvalue problems whose solutions converge to the solution of the original transport eigenvalue problem. This second class of methods is, in our experience, always superior to the first, as most of the computational work is eliminated by the acceleration from the LO diffusion system. In this paper, we review each of these methods. Our computational results support our claim that the choice of which nonlinear solver to use, JFNK or NKA, should be secondary. The primary computational savings result from the implementation of a HOLO algorithm. We display computational results for a series of challenging multi-dimensional test problems.

  4. Summary Report of Mission Acceleration Measurements for STS-73, Launched October 20, 1995

    NASA Technical Reports Server (NTRS)

    Rogers, Melissa J. B.; DeLombard, Richard

    1996-01-01

    The microgravity environment of the Space Shuttle Columbia was measured during the STS-73 mission using accelerometers from five different instruments: the Orbital Acceleration Research Experiment, the Space Acceleration Measurement System, the Three-dimensional Microgravity Accelerometer, the Microgravity Measuring Device, and Suppression of Transient Accelerations by Levitation Evaluation System. The Microgravity Analysis Workstation quasi-steady environment calculation and comparison of this calculation with Orbital Acceleration Research Experiment data was used to assess how appropriate a planned attitude was expected to be for one Crystal Growth Facility experiment sample. The microgravity environment related to several different Orbiter, crew, and experiment operations is presented and interpreted in this report. Data are examined to show the effects of vernier reaction control system jet firings for Orbiter attitude control. This is compared to examples of data when no thrusters were firing, when the primary reaction control system jets were used for attitude control, and when single vernier jets were fired for test purposes. In general, vernier jets, when used for attitude control, cause accelerations in the 3 x 10(exp -4) g to 7 x 10(exp -4) g range. Primary jets used in this manner cause accelerations in the 0.01 to 0.025 g range. Other significant disturbance sources characterized are water dump operations, with Y(sub b) axis acceleration deviations of about 1 x 10(exp -6) g; payload bay door opening motion, with Y(sub o) and Z(sub o) axis accelerations of frequency 0.4 Hz; and probable Glovebox fan operations with notable frequency components at 20, 38, 43, 48, and 53 Hz. The STS-73 microgravity environment is comparable to the environments measured on earlier microgravity science missions.

  5. Single-shot measurements of low emittance beams from laser-plasma accelerators comparing two triggered injection methods

    NASA Astrophysics Data System (ADS)

    van Tilborg, Jeroen

    2017-10-01

    The success of laser plasma accelerator (LPA) based applications, such as a compact x-ray free electron laser (FEL), relies on the ability to produce electron beams with excellent 6D brightness, where brightness is defined as the ratio of charge to the product of the three normalized emittances. As such, parametric studies of the emittance of LPA generated electron beams are essential. Profiting from a stable and tunable LPA setup, combined with a carefully designed single-shot energy-dispersed emittance diagnostic, we present a direct comparison of charge dependent emittance measurements of electron beams generated by two different injection mechanisms: ionization injection and shock-induced density down-ramp injection. Both injection mechanisms have gained in popularity in recent years due to their demonstrated stable LPA performance. For the down-ramp injection configuration, normalized emittances a factor of two lower were recorded: less than 1 micron at spectral charge densities up to 2 pC/MeV. For both injection mechanisms, a contributing correlation of space charge to the emittance was identified. This measurement technique in general, and these results specifically, are critical to the evaluation of LPA injection methods and development of high-quality LPA beam lines worldwide. This work is supported by the U.S. DOE under Contract No. DE-AC02-05CH11231, by the U.S. DOE NNSA, DNN R&D (NA22), by the National Science Foundation under Grant No. PHY-1415596, and by the Gordon and Betty Moore Foundation under Grant ID GBMF4898.

  6. Measuring the Accelerations of Water Megamasers in Active Galaxy J0437+2456

    NASA Astrophysics Data System (ADS)

    Turner, Jeremy; Jeremy Turner

    2018-01-01

    The Megamaser Cosmology Project is measuring the Hubble constant using observations of 22 GHz water megamasers in the accretion disks of active galaxies within the Hubble flow. This approach uses the dynamics of the megamaser disks to determine their physical sizes and thereby find the angular-diameter distances to galaxies without relying on the cosmic distance ladder. We present Green Bank Telescope observations and analysis of the maser disk in the galaxy J0437+2456, which encircles a 2.9×106 M⊙ supermassive black hole. With spectral monitoring observations spanning over four years, we measure the centripetal acceleration of each individual maser component by tracking its velocity drift over time. These accelerations will be used in later work to model the maser disk and determine the distance to the galaxy. Our acceleration measurements use an iterative least squares fitting technique. For the systemic maser features, we find a mean acceleration of 1.87 ± 0.47 km/s/yr. This project was completed as part of the NSF REU program at NRAO.

  7. Detecting chaos in particle accelerators through the frequency map analysis method.

    PubMed

    Papaphilippou, Yannis

    2014-06-01

    The motion of beams in particle accelerators is dominated by a plethora of non-linear effects, which can enhance chaotic motion and limit their performance. The application of advanced non-linear dynamics methods for detecting and correcting these effects and thereby increasing the region of beam stability plays an essential role during the accelerator design phase but also their operation. After describing the nature of non-linear effects and their impact on performance parameters of different particle accelerator categories, the theory of non-linear particle motion is outlined. The recent developments on the methods employed for the analysis of chaotic beam motion are detailed. In particular, the ability of the frequency map analysis method to detect chaotic motion and guide the correction of non-linear effects is demonstrated in particle tracking simulations but also experimental data.

  8. Systems and methods for cylindrical hall thrusters with independently controllable ionization and acceleration stages

    DOEpatents

    Diamant, Kevin David; Raitses, Yevgeny; Fisch, Nathaniel Joseph

    2014-05-13

    Systems and methods may be provided for cylindrical Hall thrusters with independently controllable ionization and acceleration stages. The systems and methods may include a cylindrical channel having a center axial direction, a gas inlet for directing ionizable gas to an ionization section of the cylindrical channel, an ionization device that ionizes at least a portion of the ionizable gas within the ionization section to generate ionized gas, and an acceleration device distinct from the ionization device. The acceleration device may provide an axial electric field for an acceleration section of the cylindrical channel to accelerate the ionized gas through the acceleration section, where the axial electric field has an axial direction in relation to the center axial direction. The ionization section and the acceleration section of the cylindrical channel may be substantially non-overlapping.

  9. Microgravity Acceleration Measurement System (MAMS) Flight Configuration Verification and Status

    NASA Technical Reports Server (NTRS)

    Wagar, William

    2000-01-01

    The Microgravity Acceleration Measurement System (MAMS) is a precision spaceflight instrument designed to measure and characterize the microgravity environment existing in the US Lab Module of the International Space Station. Both vibratory and quasi-steady triaxial acceleration data are acquired and provided to an Ethernet data link. The MAMS Double Mid-Deck Locker (DMDL) EXPRESS Rack payload meets all the ISS IDD and ICD interface requirements as discussed in the paper which also presents flight configuration illustrations. The overall MAMS sensor and data acquisition performance and verification data are presented in addition to a discussion of the Command and Data Handling features implemented via the ISS, downlink and the GRC Telescience Center displays.

  10. Perception of linear acceleration in weightlessness

    NASA Technical Reports Server (NTRS)

    Arrott, A. P.; Young, L. R.

    1987-01-01

    Eye movements and subjective detection of acceleration were measured on human experimental subjects during vestibular sled acceleration during the D1 Spacelab Mission. Methods and results are reported on the time to detection of small acceleration steps, the threshold for detection of linear acceleration, perceived motion path, and CLOAT. A consistently shorter time to detection of small acceleration steps is found. Subjective reports of perceived motion during sinusoidal oscillation in weightlessness were qualitatively similar to reports on earth.

  11. Summary Report of Mission Acceleration Measurement for STS-87: Launched November 19, 1997

    NASA Technical Reports Server (NTRS)

    Rogers, Melissa J. B.; Hrovat, Kenneth; McPherson, Kevin; DeLombard, Richard; Reckart, Timothy

    1999-01-01

    Two accelerometer systems, the Orbital Acceleration Research Experiment and the Space Acceleration Measurement System, were used to measure and record the microgravity environment of the Orbiter Columbia during the STS-87 mission in November-December 1997. Data from two separate Space Acceleration Measurement System units were telemetered to the ground during the mission and data plots were displayed for investigators of the Fourth United States Microgravity Payload experiments in near real-time using the World Wide Web. Plots generated using Orbital Acceleration Research Experiment data (telemetered to the ground using a tape delay) were provided to the investigators using the World Wide Web approximately twelve hours after data recording. Disturbances in the microgravity environment as recorded by these instruments are grouped by source type: Orbiter systems, on-board activities, payload operations, and unknown sources. The environment related to the Ku-band antenna dither, Orbiter structural modes, attitude deadband collapses, water dump operations, crew sleep, and crew exercise was comparable to the effects of these sources on previous Orbiter missions. Disturbances related to operations of the Isothermal Dendritic Growth Experiment and Space Acceleration Measurement Systems that were not observed on previous missions are detailed. The effects of Orbiter cabin and airlock depressurization and extravehicular activities are also reported for the first time. A set of data plots representing the entire mission is included in the CD-ROM version of this report.

  12. New radiocarbon measurement methods in the Hertelendi Laboratory, Hungary

    NASA Astrophysics Data System (ADS)

    Janovics, Róbert; Major, István; Rinyu, László; Veres, Mihály; Molnár, Mihály

    2013-04-01

    In this paper we present two very different and novel methods for C-14 measurement from dissolved inorganic carbonate (DIC) of water samples. A new LSC sample preparation method for liquid scintillation C-14 measurements was implemented in the ATOMKI. The first method uses direct absorption into a special absorbent (Carbosorb E®) and a following liquid scintillation measurement. Typical sample size is 20-40 litre of water. The developed CO2 absorption method is fast, and simple. The C-14 activities is measured by an ultra low background LSC (TRI-CARB 3170 TR/SL, Perkin Elmer) including quenching parameter (tSIE).The corresponding limit of C-14 dating is 31200 year. Several tests were executed with old borehole CO2 gas without significant content of C-14 and also performed on samples of known C-14 activities between 29 and 7000 pMC, previously measured by GPC. The combined uncertainty of the described determination is about 2 % in the case of recent carbon. It is a very cost-effective and easy to use method based on a novel and simple static absorption process for the CO2 extracted from groundwater. The other very sensitive method is based on accelerator mass spectrometry (AMS) using gas ion source. This method does not require graphite generation and a small volume of water sample (1-20mL) is enough for the radiocarbon measurement. The procedure is very similar to pre-treatment of carbonate contained sample preparation for stable isotope measurement with gasbench technique. We applied a MICADAS type accelerator mass spectrometry (AMS) with gas ion source for C-14 analysis. The radiocarbon content of water was sat free with phosphoric acid and then the headspace gas was rinsed vials. The whole measurement needs only 20 min of each sample. The precision of measurement is better than 1% for modern samples. The preparation is vastly reduced compared to the other AMS methods and principally allows fully automated measurements of groundwater samples with an auto

  13. Fast-acting calorimeter measures heat output of plasma gun accelerator

    NASA Technical Reports Server (NTRS)

    Dethlefson, R.; Larson, A. V.; Liebing, L.

    1967-01-01

    Calorimeter measures the exhaust energy from a shot of a pulsed plasma gun accelerator. It has a fast response time and requires only one measurement to determine the total energy. It uses a long ribbon of copper foil wound around a glass frame to form a reentrant cavity.

  14. Parametric emittance measurements of electron beams produced by a laser plasma accelerator

    NASA Astrophysics Data System (ADS)

    Barber, S. K.; van Tilborg, J.; Schroeder, C. B.; Lehe, R.; Tsai, H.-E.; Swanson, K. K.; Steinke, S.; Nakamura, K.; Geddes, C. G. R.; Benedetti, C.; Esarey, E.; Leemans, W. P.

    2018-05-01

    Laser plasma accelerators (LPA) offer an exciting possibility to deliver high energy, high brightness electrons beams in drastically smaller distance scales than is typical for conventional accelerators. As such, LPAs draw considerable attention as potential drivers for next generation light sources and for a compact linear collider. In order to asses the viability of an LPA source for a particular application, the brightness of the source should be properly characterized. In this paper, we present charge dependent transverse emittance measurements of LPA sources using both ionization injection and shock induced density down ramp injection, with the latter delivering smaller transverse emittances by a factor of two when controlling for charge density. The single shot emittance method is described in detail with a discussion on limitations related to second order transport effects. The direct role of space charge is explored through a series of simulations and found to be consistent with experimental observations.

  15. Optics measurement and correction during acceleration with beta-squeeze in RHIC

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

    Liu, C.; Marusic, A.; Minty, M.

    2015-05-03

    In the past, beam optics correction at RHIC has only taken place at injection and at final energy, with interpolation of corrections partially into the acceleration cycle. Recent measurements of the beam optics during acceleration and squeeze have evidenced significant beta-beats that, if corrected, could minimize undesirable emittance dilutions and maximize the spin polarization of polarized proton beams by avoiding the high-order multipole fields sampled by particles within the bunch. We recently demonstrated successful beam optics corrections during acceleration at RHIC. We verified conclusively the superior control of the beam realized via these corrections

  16. Accelerated Adaptive Integration Method

    PubMed Central

    2015-01-01

    Conformational changes that occur upon ligand binding may be too slow to observe on the time scales routinely accessible using molecular dynamics simulations. The adaptive integration method (AIM) leverages the notion that when a ligand is either fully coupled or decoupled, according to λ, barrier heights may change, making some conformational transitions more accessible at certain λ values. AIM adaptively changes the value of λ in a single simulation so that conformations sampled at one value of λ seed the conformational space sampled at another λ value. Adapting the value of λ throughout a simulation, however, does not resolve issues in sampling when barriers remain high regardless of the λ value. In this work, we introduce a new method, called Accelerated AIM (AcclAIM), in which the potential energy function is flattened at intermediate values of λ, promoting the exploration of conformational space as the ligand is decoupled from its receptor. We show, with both a simple model system (Bromocyclohexane) and the more complex biomolecule Thrombin, that AcclAIM is a promising approach to overcome high barriers in the calculation of free energies, without the need for any statistical reweighting or additional processors. PMID:24780083

  17. Fluctuation Flooding Method (FFM) for accelerating conformational transitions of proteins.

    PubMed

    Harada, Ryuhei; Takano, Yu; Shigeta, Yasuteru

    2014-03-28

    A powerful conformational sampling method for accelerating structural transitions of proteins, "Fluctuation Flooding Method (FFM)," is proposed. In FFM, cycles of the following steps enhance the transitions: (i) extractions of largely fluctuating snapshots along anisotropic modes obtained from trajectories of multiple independent molecular dynamics (MD) simulations and (ii) conformational re-sampling of the snapshots via re-generations of initial velocities when re-starting MD simulations. In an application to bacteriophage T4 lysozyme, FFM successfully accelerated the open-closed transition with the 6 ns simulation starting solely from the open state, although the 1-μs canonical MD simulation failed to sample such a rare event.

  18. Fluctuation Flooding Method (FFM) for accelerating conformational transitions of proteins

    NASA Astrophysics Data System (ADS)

    Harada, Ryuhei; Takano, Yu; Shigeta, Yasuteru

    2014-03-01

    A powerful conformational sampling method for accelerating structural transitions of proteins, "Fluctuation Flooding Method (FFM)," is proposed. In FFM, cycles of the following steps enhance the transitions: (i) extractions of largely fluctuating snapshots along anisotropic modes obtained from trajectories of multiple independent molecular dynamics (MD) simulations and (ii) conformational re-sampling of the snapshots via re-generations of initial velocities when re-starting MD simulations. In an application to bacteriophage T4 lysozyme, FFM successfully accelerated the open-closed transition with the 6 ns simulation starting solely from the open state, although the 1-μs canonical MD simulation failed to sample such a rare event.

  19. Operation and reactivity measurements of an accelerator driven subcritical TRIGA reactor

    NASA Astrophysics Data System (ADS)

    O'Kelly, David Sean

    Experiments were performed at the Nuclear Engineering Teaching Laboratory (NETL) in 2005 and 2006 in which a 20 MeV linear electron accelerator operating as a photoneutron source was coupled to the TRIGA (Training, Research, Isotope production, General Atomics) Mark II research reactor at the University of Texas at Austin (UT) to simulate the operation and characteristics of a full-scale accelerator driven subcritical system (ADSS). The experimental program provided a relatively low-cost substitute for the higher power and complexity of internationally proposed systems utilizing proton accelerators and spallation neutron sources for an advanced ADSS that may be used for the burning of high-level radioactive waste. Various instrumentation methods that permitted ADSS neutron flux monitoring in high gamma radiation fields were successfully explored and the data was used to evaluate the Stochastic Pulsed Feynman method for reactivity monitoring.

  20. Motor recovery monitoring using acceleration measurements in post acute stroke patients

    PubMed Central

    2013-01-01

    Background Stroke is one of the major causes of morbidity and mortality. Its recovery and treatment depends on close clinical monitoring by a clinician especially during the first few hours after the onset of stroke. Patients who do not exhibit early motor recovery post thrombolysis may benefit from more aggressive treatment. Method A novel approach for monitoring stroke during the first few hours after the onset of stroke using a wireless accelerometer based motor activity monitoring system is developed. It monitors the motor activity by measuring the acceleration of the arms in three axes. In the presented proof of concept study, the measured acceleration data is transferred wirelessly using iMote2 platform to the base station that is equipped with an online algorithm capable of calculating an index equivalent to the National Institute of Health Stroke Score (NIHSS) motor index. The system is developed by collecting data from 15 patients. Results We have successfully demonstrated an end-to-end stroke monitoring system reporting an accuracy of calculating stroke index of more than 80%, highest Cohen’s overall agreement of 0.91 (with excellent κ coefficient of 0.76). Conclusion A wireless accelerometer based ‘hot stroke’ monitoring system is developed to monitor the motor recovery in acute-stroke patients. It has been shown to monitor stroke patients continuously, which has not been possible so far with high reliability. PMID:23590690

  1. Sonic boom measurements from accelerating supersonic tracked sleds

    NASA Technical Reports Server (NTRS)

    Reed, J. W.

    1974-01-01

    Supersonic sled tests on the Sandia 1524-m (5000-ft) track generate sonic booms of sufficient intensity to allow some airblast measurements at distance scales not obtained from wind tunnel or flight tests. During acceleration, an emitted curved boom wave propagates to a caustic, or focus. Detailed measurements around these caustics may help to clarify the overpressure magnification which can occur from real aircraft operations. Six fixed pressure gages have been operated to document the general noise field, and a mobile array of twelve gages.

  2. Field Emission in Superconducting Accelerators: Instrumented Measurements for Its Understanding and Mitigation

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

    Geng, Rongli; Freyberger, Arne P.; Legg, Robert A.

    Several new accelerator projects are adopting superconducting accelerator technology. When accelerating cavities maintain high RF gradients, field emission, the emission of electrons from cavity walls, can occur and may impact operational cavity gradient, radiological environment via activated components, and reliability. In this talk, we will discuss instrumented measurements of field emission from the two 1.1 GeV superconducting continuous wave (CW) linacs in CEBAF. The goal is to improve the understanding of field emission sources originating from cryomodule production, installation and operation. Such basic knowledge is needed in guiding field emission control, mitigation, and reduction toward high gradient and reliable operationmore » of superconducting accelerators.« less

  3. Methods of geometrical integration in accelerator physics

    NASA Astrophysics Data System (ADS)

    Andrianov, S. N.

    2016-12-01

    In the paper we consider a method of geometric integration for a long evolution of the particle beam in cyclic accelerators, based on the matrix representation of the operator of particles evolution. This method allows us to calculate the corresponding beam evolution in terms of two-dimensional matrices including for nonlinear effects. The ideology of the geometric integration introduces in appropriate computational algorithms amendments which are necessary for preserving the qualitative properties of maps presented in the form of the truncated series generated by the operator of evolution. This formalism extends both on polarized and intense beams. Examples of practical applications are described.

  4. Accelerator mass spectrometry.

    PubMed

    Hellborg, Ragnar; Skog, Göran

    2008-01-01

    In this overview the technique of accelerator mass spectrometry (AMS) and its use are described. AMS is a highly sensitive method of counting atoms. It is used to detect very low concentrations of natural isotopic abundances (typically in the range between 10(-12) and 10(-16)) of both radionuclides and stable nuclides. The main advantages of AMS compared to conventional radiometric methods are the use of smaller samples (mg and even sub-mg size) and shorter measuring times (less than 1 hr). The equipment used for AMS is almost exclusively based on the electrostatic tandem accelerator, although some of the newest systems are based on a slightly different principle. Dedicated accelerators as well as older "nuclear physics machines" can be found in the 80 or so AMS laboratories in existence today. The most widely used isotope studied with AMS is 14C. Besides radiocarbon dating this isotope is used in climate studies, biomedicine applications and many other fields. More than 100,000 14C samples are measured per year. Other isotopes studied include 10Be, 26Al, 36Cl, 41Ca, 59Ni, 129I, U, and Pu. Although these measurements are important, the number of samples of these other isotopes measured each year is estimated to be less than 10% of the number of 14C samples. Copyright 2008 Wiley Periodicals, Inc.

  5. SAMS Acceleration Measurement on Mir From March to September 1996

    NASA Technical Reports Server (NTRS)

    Moskowitz, Milton E.; Hrovat, Ken; Truong, Duc; Reckart, Timothy

    1997-01-01

    During NASA Increment 2 (March to September 1996), over 15 gigabytes of acceleration data were collected by the Space Acceleration Measurement System (SAMS) onboard the Russian Space Station, Mir. The data were recorded on 55 optical disks and were returned to Earth on STS-79. During this time, SAMS data were collected in the Kristall and Kvant modules, and in the Priroda module to support the following experiments: the Queen's University Experiments in Liquid Diffusion (QUELD), the Technological Evaluation of the MIM (TEM), the Forced Flow Flame Spreading Test (FFFT), and Candle Flames in Microgravity (CFM). This report points out some of the salient features of the microgravity environment to which these experiments were exposed. Also documented are mission events of interest such as the docked phase of STS-76 operations, an extravehicular activity (EVA) to install and deploy solar panels on the Kvant module, a Progress engine burn to raise Mir's altitude, and an on-orbit SAMS calibration procedure. Also included are a description of the Mir module orientations, and the panel notations within the modules. This report presents an overview of the SAMS acceleration measurements recorded by 10 Hz and 100 Hz sensor heads. Variations in the acceleration environment caused by unique activities such as crew exercise and life-support fans are presented. The analyses included herein complement those presented in previous mission summary reports published by the Principal Investigator Microgravity Services (PIMS) group.

  6. Miniature plasma accelerating detonator and method of detonating insensitive materials

    DOEpatents

    Bickes, Jr., Robert W.; Kopczewski, Michael R.; Schwarz, Alfred C.

    1986-01-01

    The invention is a detonator for use with high explosives. The detonator comprises a pair of parallel rail electrodes connected to a power supply. By shorting the electrodes at one end, a plasma is generated and accelerated toward the other end to impact against explosives. A projectile can be arranged between the rails to be accelerated by the plasma. An alternative arrangement is to a coaxial electrode construction. The invention also relates to a method of detonating explosives.

  7. Frontiers of beam diagnostics in plasma accelerators: Measuring the ultra-fast and ultra-cold

    NASA Astrophysics Data System (ADS)

    Cianchi, A.; Anania, M. P.; Bisesto, F.; Chiadroni, E.; Curcio, A.; Ferrario, M.; Giribono, A.; Marocchino, A.; Pompili, R.; Scifo, J.; Shpakov, V.; Vaccarezza, C.; Villa, F.; Mostacci, A.; Bacci, A.; Rossi, A. R.; Serafini, L.; Zigler, A.

    2018-05-01

    Advanced diagnostics are essential tools in the development of plasma-based accelerators. The accurate measurement of the quality of beams at the exit of the plasma channel is crucial to optimize the parameters of the plasma accelerator. 6D electron beam diagnostics will be reviewed with emphasis on emittance measurement, which is particularly complex due to large energy spread and divergence of the emerging beams, and on femtosecond bunch length measurements.

  8. Design and analysis of fractional order seismic transducer for displacement and acceleration measurements

    NASA Astrophysics Data System (ADS)

    Veeraian, Parthasarathi; Gandhi, Uma; Mangalanathan, Umapathy

    2018-04-01

    Seismic transducers are widely used for measurement of displacement, velocity, and acceleration. This paper presents the design of seismic transducer in the fractional domain for the measurement of displacement and acceleration. The fractional order transfer function for seismic displacement and acceleration transducer are derived using Grünwald-Letnikov derivative. Frequency response analysis of fractional order seismic displacement transducer (FOSDT) and fractional order seismic acceleration transducer (FOSAT) are carried out for different damping ratio with the different fractional order, and the maximum dynamic measurement range is identified. The results demonstrate that fractional order seismic transducer has increased dynamic measurement range and less phase distortion as compared to the conventional seismic transducer even with a lower damping ratio. Time response of FOSDT and FOSAT are derived analytically in terms of Mittag-Leffler function, the effect of fractional behavior in the time domain is evaluated from the impulse and step response. The fractional order system is found to have significantly reduced overshoot as compared to the conventional transducer. The fractional order seismic transducer design proposed in this paper is illustrated with a design example for FOSDT and FOSAT. Finally, an electrical equivalent of FOSDT and FOSAT is considered, and its frequency response is found to be in close agreement with the proposed fractional order seismic transducer.

  9. Miniature plasma accelerating detonator and method of detonating insensitive materials

    DOEpatents

    Bickes, R.W. Jr.; Kopczewski, M.R.; Schwarz, A.C.

    1985-01-04

    The invention is a detonator for use with high explosives. The detonator comprises a pair of parallel rail electrodes connected to a power supply. By shorting the electrodes at one end, a plasma is generated and accelerated toward the other end to impact against explosives. A projectile can be arranged between the rails to be accelerated by the plasma. An alternative arrangement is to a coaxial electrode construction. The invention also relates to a method of detonating explosives. 3 figs.

  10. Method for Monitoring of Neutron Fields near High-Energy Accelerators

    NASA Astrophysics Data System (ADS)

    Beskrovnaia, L. G.; Guseva, S. V.; Timoshenko, G. N.

    2018-05-01

    The monitoring of neutron radiation from high-energy accelerators cannot fully rely on the standard dosimeters and radiometers manufactured in Russia, since these are sensitive only to neutrons with energies below some 10 MeV. This is because neutrons of higher energies can significantly contribute to the personnel doses both close to the accelerator shield and in the neutron multiscattered field around the shield. In this paper, we propose to measure the ambient neutron dose in energy range 10-2 MeV to 1 GeV with a device consisting of two polyethylene balls with diameters of 3 and 10 in. housing slow-neutron detectors. The larger ball also comprises a lead converter (10'' + Pb). This device can be implemented in zonal radiation monitoring in the near-accelerator area.

  11. Wireless acceleration sensor of moving elements for condition monitoring of mechanisms

    NASA Astrophysics Data System (ADS)

    Sinitsin, Vladimir V.; Shestakov, Aleksandr L.

    2017-09-01

    Comprehensive analysis of the angular and linear accelerations of moving elements (shafts, gears) allows an increase in the quality of the condition monitoring of mechanisms. However, existing tools and methods measure either linear or angular acceleration with postprocessing. This paper suggests a new construction design of an angular acceleration sensor for moving elements. The sensor is mounted on a moving element and, among other things, the data transfer and electric power supply are carried out wirelessly. In addition, the authors introduce a method for processing the received information which makes it possible to divide the measured acceleration into the angular and linear components. The design has been validated by the results of laboratory tests of an experimental model of the sensor. The study has shown that this method provides a definite separation of the measured acceleration into linear and angular components, even in noise. This research contributes an advance in the range of methods and tools for condition monitoring of mechanisms.

  12. The Awful Truth About Zero-Gravity: Space Acceleration Measurement System; Orbital Acceleration Research Experiment

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Earth's gravity holds the Shuttle in orbit, as it does satellites and the Moon. The apparent weightlessness experienced by astronauts and experiments on the Shuttle is a balancing act, the result of free-fall, or continuously falling around Earth. An easy way to visualize what is happening is with a thought experiment that Sir Isaac Newton did in 1686. Newton envisioned a mountain extending above Earth's atmosphere so that friction with the air would be eliminated. He imagined a cannon atop the mountain and aimed parallel to the ground. Firing the cannon propels the cannonball forward. At the same time, Earth's gravity pulls the cannonball down to the surface and eventual impact. Newton visualized using enough powder to just balance gravity so the cannonball would circle the Earth. Like the cannonball, objects orbiting Earth are in continuous free-fall, and it appears that gravity has been eliminated. Yet, that appearance is deceiving. Activities aboard the Shuttle generate a range of accelerations that have effects similar to those of gravity. The crew works and exercises. The main data relay antenna quivers 17 times per second to prevent 'stiction,' where parts stick then release with a jerk. Cooling pumps, air fans, and other systems add vibration. And traces of Earth's atmosphere, even 200 miles up, drag on the Shuttle. While imperceptible to us, these vibrations can have a profound impact on the commercial research and scientific experiments aboard the Shuttle. Measuring these forces is necessary so that researchers and scientists can see what may have affected their experiments when analyzing data. On STS-107 this service is provided by the Space Acceleration Measurement System for Free Flyers (SAMS-FF) and the Orbital Acceleration Research Experiment (OARE). Precision data from these two instruments will help scientists analyze data from their experiments and eliminate outside influences from the phenomena they are studying during the mission.

  13. New estimation method of neutron skyshine for a high-energy particle accelerator

    NASA Astrophysics Data System (ADS)

    Oh, Joo-Hee; Jung, Nam-Suk; Lee, Hee-Seock; Ko, Seung-Kook

    2016-09-01

    A skyshine is the dominant component of the prompt radiation at off-site. Several experimental studies have been done to estimate the neutron skyshine at a few accelerator facilities. In this work, the neutron transports from a source place to off-site location were simulated using the Monte Carlo codes, FLUKA and PHITS. The transport paths were classified as skyshine, direct (transport), groundshine and multiple-shine to understand the contribution of each path and to develop a general evaluation method. The effect of each path was estimated in the view of the dose at far locations. The neutron dose was calculated using the neutron energy spectra obtained from each detector placed up to a maximum of 1 km from the accelerator. The highest altitude of the sky region in this simulation was set as 2 km from the floor of the accelerator facility. The initial model of this study was the 10 GeV electron accelerator, PAL-XFEL. Different compositions and densities of air, soil and ordinary concrete were applied in this calculation, and their dependences were reviewed. The estimation method used in this study was compared with the well-known methods suggested by Rindi, Stevenson and Stepleton, and also with the simple code, SHINE3. The results obtained using this method agreed well with those using Rindi's formula.

  14. Summary Status of the Space Acceleration Measurement System (SAMS), September 1993

    NASA Technical Reports Server (NTRS)

    DeLombard, Richard

    1993-01-01

    The Space Acceleration Measurement System (SAMS) was developed to measure the microgravity acceleration environment to which NASA science payloads are exposed during microgravity science missions on the shuttle. Six flight units have been fabricated to date. The inaugural flight of a SAMS unit was on STS-40 in June 1991 as part of the flrst Spacelab Life Sciences mission. Since that time, SAMS has flown on six additional missions and gathered 18 gigabytes of data representing 68 days of microgravity environment. The SAMS units have been flown in the shuttle middeck and cargo bay, in the Spacelab module, and in the Spacehab module. This paper summarizes the missions and experiments which SAMS has supported. The quantity of data and the utilization of the SAMS data is described. Future activities are briefly described for the SAMS project and.the Microgravity Measurement and Analysis Project (MMAP) to support science experiments and scientists with microgravity environment measurement and analysis.

  15. Summary Status of the Space Acceleration Measurement System (SAMS), September 1993

    NASA Technical Reports Server (NTRS)

    DeLombard, Richard

    1994-01-01

    The Space Acceleration Measurement System (SAMS) was developed to measure the microgravity acceleration environment to which NASA science payloads are exposed during microgravity science missions on the shuttle. Six flight units have been fabricated to date. The inaugural flight of a SAMS unit was on STS-40 in June 1991 as part of the First Spacelab Life Sciences mission. Since that time, SAMS has flown on six additional missions and gathered eighteen gigabytes of data representing sixty-eight days of microgravity environment. The SAMS units have been flown in the shuttle middeck and cargo bay, in the Spacelab module, and in the Spacehab module. This paper summarizes the missions and experiments which SAMS has supported. The quantity of data and the utilization of the SAMS data is described. Future activities are briefly described for the SAMS project and the Microgravity Measurement and Analysis project (MMAP) to support science experiments and scientists with microgravity environment measurement and analysis.

  16. First muon acceleration using a radio-frequency accelerator

    NASA Astrophysics Data System (ADS)

    Bae, S.; Choi, H.; Choi, S.; Fukao, Y.; Futatsukawa, K.; Hasegawa, K.; Iijima, T.; Iinuma, H.; Ishida, K.; Kawamura, N.; Kim, B.; Kitamura, R.; Ko, H. S.; Kondo, Y.; Li, S.; Mibe, T.; Miyake, Y.; Morishita, T.; Nakazawa, Y.; Otani, M.; Razuvaev, G. P.; Saito, N.; Shimomura, K.; Sue, Y.; Won, E.; Yamazaki, T.

    2018-05-01

    Muons have been accelerated by using a radio-frequency accelerator for the first time. Negative muonium atoms (Mu- ), which are bound states of positive muons (μ+) and two electrons, are generated from μ+'s through the electron capture process in an aluminum degrader. The generated Mu- 's are initially electrostatically accelerated and injected into a radio-frequency quadrupole linac (RFQ). In the RFQ, the Mu- 's are accelerated to 89 keV. The accelerated Mu- 's are identified by momentum measurement and time of flight. This compact muon linac opens the door to various muon accelerator applications including particle physics measurements and the construction of a transmission muon microscope.

  17. Solutions for acceleration measurement in vehicle crash tests

    NASA Astrophysics Data System (ADS)

    Dima, D. S.; Covaciu, D.

    2017-10-01

    Crash tests are useful for validating computer simulations of road traffic accidents. One of the most important parameters measured is the acceleration. The evolution of acceleration versus time, during a crash test, form a crash pulse. The correctness of the crash pulse determination depends on the data acquisition system used. Recommendations regarding the instrumentation for impact tests are given in standards, which are focused on the use of accelerometers as impact sensors. The goal of this paper is to present the device and software developed by authors for data acquisition and processing. The system includes two accelerometers with different input ranges, a processing unit based on a 32-bit microcontroller and a data logging unit with SD card. Data collected on card, as text files, is processed with a dedicated software running on personal computers. The processing is based on diagrams and includes the digital filters recommended in standards.

  18. Possible incorporation of petroleum-based carbons in biochemicals produced by bioprocess--biomass carbon ratio measured by accelerator mass spectrometry.

    PubMed

    Kunioka, Masao

    2010-06-01

    The biomass carbon ratios of biochemicals related to biomass have been reviewed. Commercial products from biomass were explained. The biomass carbon ratios of biochemical compounds were measured by accelerator mass spectrometry (AMS) based on the (14)C concentration of carbons in the compounds. This measuring method uses the mechanism that biomass carbons include a very low level of (14)C and petroleum carbons do not include (14)C similar to the carbon dating measuring method. It was confirmed that there were some biochemicals synthesized from petroleum-based carbons. This AMS method has a high accuracy with a small standard deviation and can be applied to plastic products.

  19. Measurement of the half-life of 79Se with accelerator mass spectrometry

    DOE PAGES

    Dou, Liang; Jiang, Shan; Wang, Xiao-Bo; ...

    2014-10-01

    The accelerator mass spectrometry (AMS) is an effective method for the determination of the half-life of long-lived radionuclides. In this paper, we report a method for measurement of the half-life of 79Se. The number of 79Se atoms was determined from measured 79Se/Se absolute ratios with the AMS system at the China Institute of Atomic Energy and the decay rate of 79Se was determined by counting the emitted β-rays with a liquid scintillation spectrometer. The major improvements of our measurements include using the high abundance of an 79Se sample which was cooled for many years to exclude the interference of short-livedmore » nuclides, the extraction of SeO 2 - molecular ions, that results in a suppression of the 79 Br background by as much as about five orders of magnitude. Also, an AMS measurement of the absolute ratio of 79 Se/Se was developed to avoid systematic errors. The results show that 79 Se/Se is (2.35±0.12)×10 -7 in the reference sample and the radioactivity of 79Se is (1.24±0.05) Bq/g, so the half-life of 79Se is (2.78±0.18)×10 5 a.« less

  20. Methods of Phase and Power Control in Magnetron Transmitters for Superconducting Accelerators

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

    Kazadevich, G.; Johnson, R.; Neubauer, M.

    Various methods of phase and power control in magnetron RF sources of superconducting accelerators intended for ADS-class projects were recently developed and studied with conventional 2.45 GHz, 1 kW, CW magnetrons operating in pulsed and CW regimes. Magnetron transmitters excited by a resonant (injection-locking) phasemodulated signal can provide phase and power control with the rates required for precise stabilization of phase and amplitude of the accelerating field in Superconducting RF (SRF) cavities of the intensity-frontier accelerators. An innovative technique that can significantly increase the magnetron transmitter efficiency at the widerange power control required for superconducting accelerators was developed and verifiedmore » with the 2.45 GHz magnetrons operating in CW and pulsed regimes. High efficiency magnetron transmitters of this type can significantly reduce the capital and operation costs of the ADSclass accelerator projects.« less

  1. Centrifugal accelerator, system and method for removing unwanted layers from a surface

    DOEpatents

    Foster, Christopher A.; Fisher, Paul W.

    1995-01-01

    A cryoblasting process having a centrifugal accelerator for accelerating frozen pellets of argon or carbon dioxide toward a target area utilizes an accelerator throw wheel designed to induce, during operation, the creation of a low-friction gas bearing within internal passages of the wheel which would otherwise retard acceleration of the pellets as they move through the passages. An associated system and method for removing paint from a surface with cryoblasting techniques involves the treating, such as a preheating, of the painted surface to soften the paint prior to the impacting of frozen pellets thereagainst to increase the rate of paint removal. A system and method for producing large quantities of frozen pellets from a liquid material, such as liquid argon or carbon dioxide, for use in a cryoblasting process utilizes a chamber into which the liquid material is introduced in the form of a jet which disintegrates into droplets. A non-condensible gas, such as inert helium or air, is injected into the chamber at a controlled rate so that the droplets freeze into bodies of relatively high density.

  2. Summary Report of Mission Acceleration Measurements for STS-65, Launched 8 July 1994

    NASA Technical Reports Server (NTRS)

    Rogers, Melissa J. B.; Delombard, Richard

    1995-01-01

    The second flight of the International Microgravity Laboratory (IML-2) payload on board the STS-65 mission was supported by three accelerometer instruments: The Orbital Acceleration Research Experiment (OARE) located close to the orbiter center of mass; the Quasi-Steady Acceleration Measurement experiment, and the Space Acceleration Measurement System (SAMS), both in the Spacelab module. A fourth accelerometer, the Microgravity Measuring Device recorded data in the middeck in support of exercise isolation tests.Data collected by OARE and SAMS during IML-2 are displayed in this report. The OARE data represent the microgravity environment below 1 Hz. The SAMS data represent the environment in the 0.01 Hz to 100 Hz range. Variations in the environment caused by unique activities are presented. Specific events addressed are: crew activity, crew exercise, experiment component mixing activities, experiment centrifuge operations, refrigerator/freezer operations and circulation pump operations. The analyses included in this report complement analyses presented in other mission summary reports.

  3. Fokker-Planck Equations of Stochastic Acceleration: A Study of Numerical Methods

    NASA Astrophysics Data System (ADS)

    Park, Brian T.; Petrosian, Vahe

    1996-03-01

    Stochastic wave-particle acceleration may be responsible for producing suprathermal particles in many astrophysical situations. The process can be described as a diffusion process through the Fokker-Planck equation. If the acceleration region is homogeneous and the scattering mean free path is much smaller than both the energy change mean free path and the size of the acceleration region, then the Fokker-Planck equation reduces to a simple form involving only the time and energy variables. in an earlier paper (Park & Petrosian 1995, hereafter Paper 1), we studied the analytic properties of the Fokker-Planck equation and found analytic solutions for some simple cases. In this paper, we study the numerical methods which must be used to solve more general forms of the equation. Two classes of numerical methods are finite difference methods and Monte Carlo simulations. We examine six finite difference methods, three fully implicit and three semi-implicit, and a stochastic simulation method which uses the exact correspondence between the Fokker-Planck equation and the it5 stochastic differential equation. As discussed in Paper I, Fokker-Planck equations derived under the above approximations are singular, causing problems with boundary conditions and numerical overflow and underflow. We evaluate each method using three sample equations to test its stability, accuracy, efficiency, and robustness for both time-dependent and steady state solutions. We conclude that the most robust finite difference method is the fully implicit Chang-Cooper method, with minor extensions to account for the escape and injection terms. Other methods suffer from stability and accuracy problems when dealing with some Fokker-Planck equations. The stochastic simulation method, although simple to implement, is susceptible to Poisson noise when insufficient test particles are used and is computationally very expensive compared to the finite difference method.

  4. Krylov Deferred Correction Accelerated Method of Lines Transpose for Parabolic Problems

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

    Jia, Jun; Jingfang, Huang

    2008-01-01

    In this paper, a new class of numerical methods for the accurate and efficient solutions of parabolic partial differential equations is presented. Unlike traditional method of lines (MoL), the new {\\bf \\it Krylov deferred correction (KDC) accelerated method of lines transpose (MoL^T)} first discretizes the temporal direction using Gaussian type nodes and spectral integration, and symbolically applies low-order time marching schemes to form a preconditioned elliptic system, which is then solved iteratively using Newton-Krylov techniques such as Newton-GMRES or Newton-BiCGStab method. Each function evaluation in the Newton-Krylov method is simply one low-order time-stepping approximation of the error by solving amore » decoupled system using available fast elliptic equation solvers. Preliminary numerical experiments show that the KDC accelerated MoL^T technique is unconditionally stable, can be spectrally accurate in both temporal and spatial directions, and allows optimal time-step sizes in long-time simulations.« less

  5. SAMS Acceleration Measurements on Mir from June to November 1995

    NASA Technical Reports Server (NTRS)

    DeLombard, Richard; Hrovat, Ken; Moskowitz, Milton; McPherson, Kevin

    1996-01-01

    The NASA Microgravity Science and Applications Division (MSAD) sponsors science experiments on a variety of microgravity carriers, including sounding rockets, drop towers, parabolic aircraft, and Orbiter missions. The MSAD sponsors the Space Acceleration Measurement System (SAMS) to support microgravity science experiments with acceleration measurements to characterize the microgravity environment to which the experiments were exposed. The Principal Investigator Microgravity Services project at the NASA Lewis Research Center supports principal investigators of microgravity experiments as they evaluate the effects of varying acceleration levels on their experiments. In 1993, a cooperative effort was started between the United States and Russia involving science utilization of the Russian Mir space station by scientists from the United States and Russia. MSAD is currently sponsoring science experiments participating in the Shuttle-Mir Science Program in cooperation with the Russians on the Mir space station. Included in the complement of MSAD experiments and equipment is a SAMS unit In a manner similar to Orbiter mission support, the SAMS unit supports science experiments from the U.S. and Russia by measuring the microgravity environment during experiment operations. The initial SAMS supported experiment was a Protein Crystal Growth (PCG) experiment from June to November 1995. SAMS data were obtained during the PCG operations on Mir in accordance with the PCG Principal Investigator's requirements. This report presents an overview of the SAMS data recorded to support this PCG experiment. The report contains plots of the SAMS 100 Hz sensor head data as an overview of the microgravity environment, including the STS-74 Shuttle-Mir docking.

  6. Measurement of 59Ni and 63Ni by accelerator mass spectrometry at CIAE

    NASA Astrophysics Data System (ADS)

    Wang, Xiaoming; He, Ming; Ruan, Xiangdong; Xu, Yongning; Shen, Hongtao; Du, Liang; Xiao, Caijin; Dong, Kejun; Jiang, Shan; Yang, Xuran; Lan, Xiaoxi; Wu, Shaoyong; Zhao, Qingzhang; Cai, Li; Pang, Fangfang

    2015-10-01

    The long lived isotopes 59Ni and 63Ni can be used in many areas such as radioactive waste management, neutron dosimetry, cosmic radiation study, and so on. Based on the large accelerator and a big Q3D magnetic spectrometer, the measurement method for 59Ni and 63Ni is under development at the AMS facility at China Institute of Atomic Energy (CIAE). By using the ΔE-Q3D technique with the Q3D magnetic spectrometer, the isobaric interferences were greatly reduced in the measurements of 59Ni and 63Ni. A four anode gas ionization chamber was then used to further identify isobars. With these techniques, the abundance sensitivities of 59Ni and 63Ni measurements are determined as 59Ni/Ni = 1 × 10-13 and 63Ni/Ni = 2 × 10-12, respectively.

  7. The radiation field measurement and analysis outside the shielding of A 10 MeV electron irradiation accelerator

    NASA Astrophysics Data System (ADS)

    Shang, Jing; Li, Juexin; Xu, Bing; Li, Yuxiong

    2011-10-01

    Electron accelerators are employed widely for diverse purposes in the irradiation-processing industry, from sterilizing medical products to treating gemstones. Because accelerators offer high efficiency, high power, and require little preventative maintenance, they are becoming more and more popular than using the 60Co isotope approach. However, the electron accelerator exposes potential radiation hazards. To protect workers and the public from exposure to radiation, the radiation field around the electronic accelerator must be assessed, especially that outside the shielding. Thus, we measured the radiation dose at different positions outside the shielding of a 10-MeV electron accelerator using a new data-acquisition unit named Mini-DDL (Mini-Digital Data Logging). The measurements accurately reflect the accelerator's radiation status. In this paper, we present our findings, results and compare them with our theoretical calculations. We conclude that the measurements taken outside the irradiation hall are consistent with the findings from our calculations, except in the maze outside the door of the accelerator room. We discuss the reason for this discrepancy.

  8. Effects of energy chirp on bunch length measurement in linear accelerator beams

    NASA Astrophysics Data System (ADS)

    Sabato, L.; Arpaia, P.; Giribono, A.; Liccardo, A.; Mostacci, A.; Palumbo, L.; Vaccarezza, C.; Variola, A.

    2017-08-01

    The effects of assumptions about bunch properties on the accuracy of the measurement method of the bunch length based on radio frequency deflectors (RFDs) in electron linear accelerators (LINACs) are investigated. In particular, when the electron bunch at the RFD has a non-negligible energy chirp (i.e. a correlation between the longitudinal positions and energies of the particle), the measurement is affected by a deterministic intrinsic error, which is directly related to the RFD phase offset. A case study on this effect in the electron LINAC of a gamma beam source at the Extreme Light Infrastructure-Nuclear Physics (ELI-NP) is reported. The relative error is estimated by using an electron generation and tracking (ELEGANT) code to define the reference measurements of the bunch length. The relative error is proved to increase linearly with the RFD phase offset. In particular, for an offset of {{7}\\circ} , corresponding to a vertical centroid offset at a screen of about 1 mm, the relative error is 4.5%.

  9. Correction of static pressure on a research aircraft in accelerated flight using differential pressure measurements

    NASA Astrophysics Data System (ADS)

    Rodi, A. R.; Leon, D. C.

    2012-11-01

    A method is described that estimates the error in the static pressure measurement on an aircraft from differential pressure measurements on the hemispherical surface of a Rosemount model 858AJ air velocity probe mounted on a boom ahead of the aircraft. The theoretical predictions for how the pressure should vary over the surface of the hemisphere, involving an unknown sensitivity parameter, leads to a set of equations that can be solved for the unknowns - angle of attack, angle of sideslip, dynamic pressure and the error in static pressure - if the sensitivity factor can be determined. The sensitivity factor was determined on the University of Wyoming King Air research aircraft by comparisons with the error measured with a carefully designed sonde towed on connecting tubing behind the aircraft - a trailing cone - and the result was shown to have a precision of about ±10 Pa over a wide range of conditions, including various altitudes, power settings, and gear and flap extensions. Under accelerated flight conditions, geometric altitude data from a combined Global Navigation Satellite System (GNSS) and inertial measurement unit (IMU) system are used to estimate acceleration effects on the error, and the algorithm is shown to predict corrections to a precision of better than ±20 Pa under those conditions. Some limiting factors affecting the precision of static pressure measurement on a research aircraft are discussed.

  10. Hypersonic rarefied-flow aerodynamics inferred from Shuttle Orbiter acceleration measurements

    NASA Technical Reports Server (NTRS)

    Blanchard, R. C.; Hinson, E. W.

    1989-01-01

    Data obtained from multiple flights of sensitive accelerometers on the Space Shuttle Orbiter during reentry have been used to develop an improved aerodynamic model for the Orbiter normal- and axial-force coefficients in hypersonic rarefied flow. The lack of simultaneous atmospheric density measurements was overcome in part by using the ratio of normal-to-axial acceleration, in which density cancels, as a constraint. Differences between the preflight model and the flight-acceleration-derived model in the continuum regime are attributed primarily to real gas effects. New insights are gained into the variation of the force coefficients in the transition between the continuum regime and free molecule flow.

  11. Summary Report of Mission Acceleration Measurements for STS-75, Launched February 22, 1996

    NASA Technical Reports Server (NTRS)

    Rogers, Melissa J. B.; Hrovat, Kenneth; Moskowitz, Milton E.; McPherson, Kevin M.; DeLombard, Richard

    1996-01-01

    Two accelerometers provided acceleration data during the STS-75 mission in support of the third United States Microgravity Payload (USMP-3) experiments. The Orbital Acceleration Research Experiment (OARE) and the Space Acceleration Measurement System (SAMS) provided a measure of the microgravity environment of the Space Shuttle Columbia. The OARE provided investigators with quasi-steady acceleration measurements after about a six hour time lag dictated by downlink constraints. SAMS data were downlinked in near-real-time and recorded on-board for post-mission analysis. An overview of the mission is provided as are brief discussions of these two accelerometer systems. Data analysis techniques used to process SAMS and OARE data are discussed Using a combination of these techniques, the microgravity environment related to several different Orbiter, crew, and experiment operations is presented and interpreted. The microgravity environment represented by SAMS and OARE data is comparable to the environments measured by the instruments on earlier microgravity science missions. The OARE data compared well with predictions of the quasi-steady environment. The SAMS data show the influence of thruster firings and crew motion (transient events) and of crew exercise, Orbiter systems, and experiment operations (oscillatory events). Thruster activity on this mission appears to be somewhat more frequent than on other microgravity missions with the combined firings of the F5L and F5R jets producing significant acceleration transients. The specific crew activities performed in the middeck and flight deck, the SPREE table rotations, the waste collection system compaction, and the fuel cell purge had negligible effects on the microgravity environment of the USMP-3 carriers. The Ku band antenna repositioning activity resulted in a brief interruption of the ubiquitous 17 Hz signal in the SAMS data. In addition, the auxiliary power unit operations during the Flight Control System checkout

  12. Gravity Compensation Method for Combined Accelerometer and Gyro Sensors Used in Cardiac Motion Measurements.

    PubMed

    Krogh, Magnus Reinsfelt; Nghiem, Giang M; Halvorsen, Per Steinar; Elle, Ole Jakob; Grymyr, Ole-Johannes; Hoff, Lars; Remme, Espen W

    2017-05-01

    A miniaturized accelerometer fixed to the heart can be used for monitoring of cardiac function. However, an accelerometer cannot differentiate between acceleration caused by motion and acceleration due to gravity. The accuracy of motion measurements is therefore dependent on how well the gravity component can be estimated and filtered from the measured signal. In this study we propose a new method for estimating the gravity, based on strapdown inertial navigation, using a combined accelerometer and gyro. The gyro was used to estimate the orientation of the gravity field and thereby remove it. We compared this method with two previously proposed gravity filtering methods in three experimental models using: (1) in silico computer simulated heart motion; (2) robot mimicked heart motion; and (3) in vivo measured motion on the heart in an animal model. The new method correlated excellently with the reference (r 2  > 0.93) and had a deviation from reference peak systolic displacement (6.3 ± 3.9 mm) below 0.2 ± 0.5 mm for the robot experiment model. The new method performed significantly better than the two previously proposed methods (p < 0.001). The results show that the proposed method using gyro can measure cardiac motion with high accuracy and performs better than existing methods for filtering the gravity component from the accelerometer signal.

  13. Summary Report of Mission Acceleration Measurements for STS-89: Launched January 22, 1998

    NASA Technical Reports Server (NTRS)

    Hrovat, Kenneth; McPherson, Kevin

    1999-01-01

    Support of microgravity research on the 89th flight of the Space Transportation System (STS-89) and a continued effort to characterize the acceleration environment of the Space Shuttle Orbiter and the Mir Space Station form the basis for this report. For the STS-89 mission, the Space Shuttle Endeavour was equipped with a Space Acceleration Measurement System (SAMS) unit, which collected more than a week's worth of data. During docked operations with Mir, a second SAMS unit collected approximately a day's worth of data yielding the only set of acceleration measurements recorded simultaneously on the two spacecraft. Based on the data acquired by these SAMS units, this report serves to characterize a number of acceleration events and quantify their impact on the local nature of the accelerations experienced at the Mechanics of Granular Materials (MGM) experiment location. Crew activity was shown to nearly double the median root-mean-square (RMS) acceleration level calculated below 10 Hz, while the Enhanced Orbiter Refrigerator/Freezer operating at about 22 Hz was a strong acceleration source in the vicinity of the MGM location. The MGM science requirement that the acceleration not exceed q I mg was violated numerous times during their experiment runs; however, no correlation with sample instability has been found to this point. Synchronization between the SAMS data from Endeavour and from Mir was shown to be close much of the time, but caution with respect to exact timing should be exercised when comparing these data. When orbiting as a separate vehicle prior to docking, Endeavour had prominent structural modes above 3 Hz, while Mir exhibited a cluster of modes around 1 Hz. When mated, a transition to common modes was apparent in the two SAMS data sets. This report is not a comprehensive analysis of the acceleration data, so those interested in further details should contact the Principal Investigator Microgravity Services team at the National Aeronautics and Space

  14. An Accelerated Method for Testing Soldering Tendency of Core Pins

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

    Han, Qingyou; Xu, Hanbing; Ried, Paul

    2010-01-01

    An accelerated method for testing die soldering has been developed. High intensity ultrasonic vibrations has been used to simulate the die casting conditions such as high pressure and high impingement speed of molten metal on the pin. Soldering tendency of steels and coated pins has been examined. The results indicate that in the low carbon steel/Al system, the onset of soldering is 60 times faster with ultrasonic vibration than that without ultrasonic vibration. In the H13/A380 system, the onset of soldering reaction is accelerated to 30-60 times. Coating significantly reduces the soldering tendency of the core pins.

  15. Consistency among distance measurements: transparency, BAO scale and accelerated expansion

    NASA Astrophysics Data System (ADS)

    Avgoustidis, Anastasios; Verde, Licia; Jimenez, Raul

    2009-06-01

    We explore consistency among different distance measures, including Supernovae Type Ia data, measurements of the Hubble parameter, and determination of the Baryon acoustic oscillation scale. We present new constraints on the cosmic transparency combining H(z) data together with the latest Supernovae Type Ia data compilation. This combination, in the context of a flat ΛCDM model, improves current constraints by nearly an order of magnitude although the constraints presented here are parametric rather than non-parametric. We re-examine the recently reported tension between the Baryon acoustic oscillation scale and Supernovae data in light of possible deviations from transparency, concluding that the source of the discrepancy may most likely be found among systematic effects of the modelling of the low redshift data or a simple ~ 2-σ statistical fluke, rather than in exotic physics. Finally, we attempt to draw model-independent conclusions about the recent accelerated expansion, determining the acceleration redshift to be zacc = 0.35+0.20-0.13 (1-σ).

  16. Summary Report of Mission Acceleration Measurements for MSL-1: STS-83, Launched April 14, 1997; STS-94, Launched July 1, 1997

    NASA Technical Reports Server (NTRS)

    Moskowitz, Milton E.; Hrovat, Kenneth; Tschen, Peter; McPherson, Kevin; Nati, Maurizio; Reckart, Timothy A.

    1998-01-01

    The microgravity environment of the Space Shuttle Columbia was measured during the STS-83 and STS-94 flights of the Microgravity Science Laboratory (MSL-1) mission using four different accelerometer systems: the Orbital Acceleration Research Experiment (OARE), the Space Acceleration Measurement System (SAMS), the Microgravity Measurement Assembly (MMA), and the Quasi-Steady Acceleration Measurement (QSAM) system. All four accelerometer systems provided investigators with acceleration measurements downlinked in near-real-time. Data from each system was recorded for post-mission analysis. The OARE measured the Shuttle's acceleration with high resolution in the quasi-steady frequency regime below about 0.1 Hz. The SAMS provided investigators with higher frequency acceleration measurements up to 25 Hz. The QSAM and MMA systems provided investigators with quasi-steady and higher frequency (up to 100 Hz) acceleration measurements, respectively. The microgravity environment related to various Orbiter maneuvers, crew activities, and experiment operations as measured by the OARE and MMA is presented and interpreted in section 8 of this report.

  17. Assessment of two-dimensional induced accelerations from measured kinematic and kinetic data.

    PubMed

    Hof, A L; Otten, E

    2005-11-01

    A simple algorithm is presented to calculate the induced accelerations of body segments in human walking for the sagittal plane. The method essentially consists of setting up 2x4 force equations, 4 moment equations, 2x3 joint constraint equations and two constraints related to the foot-ground interaction. Data needed for the equations are, next to masses and moments of inertia, the positions of ankle, knee and hip. This set of equations is put in the form of an 18x18 matrix or 20x20 matrix, the solution of which can be found by inversion. By applying input vectors related to gravity, to centripetal accelerations or to muscle moments, the 'induced' accelerations and reaction forces related to these inputs can be found separately. The method was tested for walking in one subject. Good agreement was found with published results obtained by much more complicated three-dimensional forward dynamic models.

  18. Methodology for the Calibration of the Data Acquisition with a Six-Degree-of-Freedom Acceleration Measurement Device

    DOT National Transportation Integrated Search

    1989-06-01

    This report describes a methodology for calibrating and gathering data with a six-degree-of-freedom acceleration measurement device that is intended to measure head acceleration of anthropomorphic dummies and human volunteers in automotive crash test...

  19. The effect of copper, MDA, and accelerated aging on jet fuel thermal stability as measured by the gravimetric JFTOT

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

    Pande, S.G.; Hardy, D.R.

    1995-05-01

    Thermally unstable jet fuels pose operational problems. In order to adequately identify such fuels, factors that realistically impact on thermal stability were examined. Evaluation was based on a quantitative method of measuring thermal stability, viz., NRL`s recently developed gravimetric JFTOT. This method gives a quantitative measurement of both the strip deposit and filterables formed. The pertinent factors examined, included the individual and interactive effects of: soluble copper, MDA (metal deactivator), and aging. The latter was accelerated to simulate field conditions of approximately six months aging at ambient temperature and pressure. The results indicate that the individual and interactive effects ofmore » copper, MDA, and accelerated aging appear to be fuel dependent. Based on the results, the three test fuels examined (one JP-8 and two JP-5s) were categorized as exhibiting very good, typical, and poor thermal stabilities, respectively. For both the very good and poor thermal stability fuels, the effect of copper in conjunction with accelerated aging did not significantly increase the total thermal deposits of the neat fuels. In contrast, for the typical thermal stability fuel, the combined effects of copper and accelerated aging, did. Furthermore, the addition of MDA prior to aging of the copper-doped, typical stability fuel significantly counteracted the adverse effect of copper and aging. A similar beneficial effect of MDA was not observed for the poor stability fuel. These results focus on the compositional differences among fuels and the need to elucidate these differences (physical and chemical) for a better understanding and prediction of their performance.« less

  20. Acceleration of Semiempirical QM/MM Methods through Message Passage Interface (MPI), Hybrid MPI/Open Multiprocessing, and Self-Consistent Field Accelerator Implementations.

    PubMed

    Ojeda-May, Pedro; Nam, Kwangho

    2017-08-08

    The strategy and implementation of scalable and efficient semiempirical (SE) QM/MM methods in CHARMM are described. The serial version of the code was first profiled to identify routines that required parallelization. Afterward, the code was parallelized and accelerated with three approaches. The first approach was the parallelization of the entire QM/MM routines, including the Fock matrix diagonalization routines, using the CHARMM message passage interface (MPI) machinery. In the second approach, two different self-consistent field (SCF) energy convergence accelerators were implemented using density and Fock matrices as targets for their extrapolations in the SCF procedure. In the third approach, the entire QM/MM and MM energy routines were accelerated by implementing the hybrid MPI/open multiprocessing (OpenMP) model in which both the task- and loop-level parallelization strategies were adopted to balance loads between different OpenMP threads. The present implementation was tested on two solvated enzyme systems (including <100 QM atoms) and an S N 2 symmetric reaction in water. The MPI version exceeded existing SE QM methods in CHARMM, which include the SCC-DFTB and SQUANTUM methods, by at least 4-fold. The use of SCF convergence accelerators further accelerated the code by ∼12-35% depending on the size of the QM region and the number of CPU cores used. Although the MPI version displayed good scalability, the performance was diminished for large numbers of MPI processes due to the overhead associated with MPI communications between nodes. This issue was partially overcome by the hybrid MPI/OpenMP approach which displayed a better scalability for a larger number of CPU cores (up to 64 CPUs in the tested systems).

  1. Development and evaluation of accelerated drug release testing methods for a matrix-type intravaginal ring.

    PubMed

    Externbrink, Anna; Eggenreich, Karin; Eder, Simone; Mohr, Stefan; Nickisch, Klaus; Klein, Sandra

    2017-01-01

    Accelerated drug release testing is a valuable quality control tool for long-acting non-oral extended release formulations. Currently, several intravaginal ring candidates designed for the long-term delivery of steroids or anti-infective drugs are being in the developing pipeline. The present article addresses the demand for accelerated drug release methods for these formulations. We describe the development and evaluation of accelerated release methods for a steroid releasing matrix-type intravaginal ring. The drug release properties of the formulation were evaluated under real-time and accelerated test conditions. Under real-time test conditions drug release from the intravaginal ring was strongly affected by the steroid solubility in the release medium. Under sufficient sink conditions that were provided in release media containing surfactants drug release was Fickian diffusion driven. Both temperature and hydro-organic dissolution media were successfully employed to accelerate drug release from the formulation. Drug release could be further increased by combining the temperature effect with the application of a hydro-organic release medium. The formulation continued to exhibit a diffusion controlled release kinetic under the investigated accelerated conditions. Moreover, the accelerated methods were able to differentiate between different prototypes of the intravaginal ring that exhibited different release profiles under real-time test conditions. Overall, the results of the present study indicate that both temperature and hydro-organic release media are valid parameters for accelerating drug release from the intravaginal ring. Variation of either a single or both parameters yielded release profiles that correlated well with real-time release. Copyright © 2016 Elsevier B.V. All rights reserved.

  2. rf breakdown measurements in electron beam driven 200 GHz copper and copper-silver accelerating structures

    DOE PAGES

    Dal Forno, Massimo; Dolgashev, Valery; Bowden, Gordon; ...

    2016-11-30

    This study explores the physics of vacuum rf breakdowns in subterahertz high-gradient traveling-wave accelerating structures. We present the experimental results of rf tests of 200 GHz metallic accelerating structures, made of copper and copper-silver. These experiments were carried out at the Facility for Advanced Accelerator Experimental Tests (FACET) at the SLAC National Accelerator Laboratory. The rf fields were excited by the FACET ultrarelativistic electron beam. The traveling-wave structure is an open geometry, 10 cm long, composed of two halves separated by a gap. The rf frequency of the fundamental accelerating mode depends on the gap size and can be changedmore » from 160 to 235 GHz. When the beam travels off axis, a deflecting field is induced in addition to the longitudinal field. We measure the deflecting forces by observing the displacement of the electron bunch and use this measurement to verify the expected accelerating gradient. Furthermore, we present the first quantitative measurement of rf breakdown rates in 200 GHz metallic accelerating structures. The breakdown rate of the copper structure is 10 –2 per pulse, with a peak surface electric field of 500 MV/m and a rf pulse length of 0.3 ns, which at a relatively large gap of 1.5 mm, or one wavelength, corresponds to an accelerating gradient of 56 MV/m. For the same breakdown rate, the copper-silver structure has a peak electric field of 320 MV/m at a pulse length of 0.5 ns. For a gap of 1.1 mm, or 0.74 wavelengths, this corresponds to an accelerating gradient of 50 MV/m.« less

  3. Unsupervised classification of Space Acceleration Measurement System (SAMS) data using ART2-A

    NASA Technical Reports Server (NTRS)

    Smith, A. D.; Sinha, A.

    1999-01-01

    The Space Acceleration Measurement System (SAMS) has been developed by NASA to monitor the microgravity acceleration environment aboard the space shuttle. The amount of data collected by a SAMS unit during a shuttle mission is in the several gigabytes range. Adaptive Resonance Theory 2-A (ART2-A), an unsupervised neural network, has been used to cluster these data and to develop cause and effect relationships among disturbances and the acceleration environment. Using input patterns formed on the basis of power spectral densities (psd), data collected from two missions, STS-050 and STS-057, have been clustered.

  4. Method and apparatus for varying accelerator beam output energy

    DOEpatents

    Young, Lloyd M.

    1998-01-01

    A coupled cavity accelerator (CCA) accelerates a charged particle beam with rf energy from a rf source. An input accelerating cavity receives the charged particle beam and an output accelerating cavity outputs the charged particle beam at an increased energy. Intermediate accelerating cavities connect the input and the output accelerating cavities to accelerate the charged particle beam. A plurality of tunable coupling cavities are arranged so that each one of the tunable coupling cavities respectively connect an adjacent pair of the input, output, and intermediate accelerating cavities to transfer the rf energy along the accelerating cavities. An output tunable coupling cavity can be detuned to variably change the phase of the rf energy reflected from the output coupling cavity so that regions of the accelerator can be selectively turned off when one of the intermediate tunable coupling cavities is also detuned.

  5. Vibration-Based Method Developed to Detect Cracks in Rotors During Acceleration Through Resonance

    NASA Technical Reports Server (NTRS)

    Sawicki, Jerzy T.; Baaklini, George Y.; Gyekenyesi, Andrew L.

    2004-01-01

    In recent years, there has been an increasing interest in developing rotating machinery shaft crack-detection methodologies and online techniques. Shaft crack problems present a significant safety and loss hazard in nearly every application of modern turbomachinery. In many cases, the rotors of modern machines are rapidly accelerated from rest to operating speed, to reduce the excessive vibrations at the critical speeds. The vibration monitoring during startup or shutdown has been receiving growing attention (ref. 1), especially for machines such as aircraft engines, which are subjected to frequent starts and stops, as well as high speeds and acceleration rates. It has been recognized that the presence of angular acceleration strongly affects the rotor's maximum response to unbalance and the speed at which it occurs. Unfortunately, conventional nondestructive evaluation (NDE) methods have unacceptable limits in terms of their application for online crack detection. Some of these techniques are time consuming and inconvenient for turbomachinery service testing. Almost all of these techniques require that the vicinity of the damage be known in advance, and they can provide only local information, with no indication of the structural strength at a component or system level. In addition, the effectiveness of these experimental techniques is affected by the high measurement noise levels existing in complex turbomachine structures. Therefore, the use of vibration monitoring along with vibration analysis has been receiving increasing attention.

  6. Accounting for measurement error in log regression models with applications to accelerated testing.

    PubMed

    Richardson, Robert; Tolley, H Dennis; Evenson, William E; Lunt, Barry M

    2018-01-01

    In regression settings, parameter estimates will be biased when the explanatory variables are measured with error. This bias can significantly affect modeling goals. In particular, accelerated lifetime testing involves an extrapolation of the fitted model, and a small amount of bias in parameter estimates may result in a significant increase in the bias of the extrapolated predictions. Additionally, bias may arise when the stochastic component of a log regression model is assumed to be multiplicative when the actual underlying stochastic component is additive. To account for these possible sources of bias, a log regression model with measurement error and additive error is approximated by a weighted regression model which can be estimated using Iteratively Re-weighted Least Squares. Using the reduced Eyring equation in an accelerated testing setting, the model is compared to previously accepted approaches to modeling accelerated testing data with both simulations and real data.

  7. Space Acceleration Measurement System-II: Microgravity Instrumentation for the International Space Station Research Community

    NASA Technical Reports Server (NTRS)

    Sutliff, Thomas J.

    1999-01-01

    The International Space Station opens for business in the year 2000, and with the opening, science investigations will take advantage of the unique conditions it provides as an on-orbit laboratory for research. With initiation of scientific studies comes a need to understand the environment present during research. The Space Acceleration Measurement System-II provides researchers a consistent means to understand the vibratory conditions present during experimentation on the International Space Station. The Space Acceleration Measurement System-II, or SAMS-II, detects vibrations present while the space station is operating. SAMS-II on-orbit hardware is comprised of two basic building block elements: a centralized control unit and multiple Remote Triaxial Sensors deployed to measure the acceleration environment at the point of scientific research, generally within a research rack. Ground Operations Equipment is deployed to complete the command, control and data telemetry elements of the SAMS-II implementation. Initially, operations consist of user requirements development, measurement sensor deployment and use, and data recovery on the ground. Future system enhancements will provide additional user functionality and support more simultaneous users.

  8. A method for the measurement and analysis of ride vibrations of transportation systems

    NASA Technical Reports Server (NTRS)

    Catherines, J. J.; Clevenson, S. A.; Scholl, H. F.

    1972-01-01

    The measurement and recording of ride vibrations which affect passenger comfort in transportation systems and the subsequent data-reduction methods necessary for interpreting the data present exceptional instrumentation requirements and necessitate the use of computers for specialized analysis techniques. A method is presented for both measuring and analyzing ride vibrations of the type encountered in ground and air transportation systems. A portable system for measuring and recording low-frequency, low-amplitude accelerations and specialized data-reduction procedures are described. Sample vibration measurements in the form of statistical parameters representative of typical transportation systems are also presented to demonstrate the utility of the techniques.

  9. Beam property measurement of a 300-kV ion source test stand for a 1-MV electrostatic accelerator

    NASA Astrophysics Data System (ADS)

    Park, Sae-Hoon; Kim, Dae-Il; Kim, Yu-Seok

    2016-09-01

    The KOMAC (Korea Multi-purpose Accelerator Complex) has been developing a 300-kV ion source test stand for a 1-MV electrostatic accelerator for industrial purposes. A RF ion source was operated at 200 MHz with its matching circuit. The beam profile and emittance were measured behind an accelerating column to confirm the beam property from the RF ion source. The beam profile was measured at the end of the accelerating tube and at the beam dump by using a beam profile monitor (BPM) and wire scanner. An Allison-type emittance scanner was installed behind the beam profile monitor (BPM) to measure the beam density in phase space. The measurement results for the beam profile and emittance are presented in this paper.

  10. Acceleration methods for multi-physics compressible flow

    NASA Astrophysics Data System (ADS)

    Peles, Oren; Turkel, Eli

    2018-04-01

    In this work we investigate the Runge-Kutta (RK)/Implicit smoother scheme as a convergence accelerator for complex multi-physics flow problems including turbulent, reactive and also two-phase flows. The flows considered are subsonic, transonic and supersonic flows in complex geometries, and also can be either steady or unsteady flows. All of these problems are considered to be a very stiff. We then introduce an acceleration method for the compressible Navier-Stokes equations. We start with the multigrid method for pure subsonic flow, including reactive flows. We then add the Rossow-Swanson-Turkel RK/Implicit smoother that enables performing all these complex flow simulations with a reasonable CFL number. We next discuss the RK/Implicit smoother for time dependent problem and also for low Mach numbers. The preconditioner includes an intrinsic low Mach number treatment inside the smoother operator. We also develop a modified Roe scheme with a corresponding flux Jacobian matrix. We then give the extension of the method for real gas and reactive flow. Reactive flows are governed by a system of inhomogeneous Navier-Stokes equations with very stiff source terms. The extension of the RK/Implicit smoother requires an approximation of the source term Jacobian. The properties of the Jacobian are very important for the stability of the method. We discuss what the chemical physics theory of chemical kinetics tells about the mathematical properties of the Jacobian matrix. We focus on the implication of the Le-Chatelier's principle on the sign of the diagonal entries of the Jacobian. We present the implementation of the method for turbulent flow. We use a two RANS turbulent model - one equation model - Spalart-Allmaras and a two-equation model - k-ω SST model. The last extension is for two-phase flows with a gas as a main phase and Eulerian representation of a dispersed particles phase (EDP). We present some examples for such flow computations inside a ballistic evaluation

  11. Modal Correction Method For Dynamically Induced Errors In Wind-Tunnel Model Attitude Measurements

    NASA Technical Reports Server (NTRS)

    Buehrle, R. D.; Young, C. P., Jr.

    1995-01-01

    This paper describes a method for correcting the dynamically induced bias errors in wind tunnel model attitude measurements using measured modal properties of the model system. At NASA Langley Research Center, the predominant instrumentation used to measure model attitude is a servo-accelerometer device that senses the model attitude with respect to the local vertical. Under smooth wind tunnel operating conditions, this inertial device can measure the model attitude with an accuracy of 0.01 degree. During wind tunnel tests when the model is responding at high dynamic amplitudes, the inertial device also senses the centrifugal acceleration associated with model vibration. This centrifugal acceleration results in a bias error in the model attitude measurement. A study of the response of a cantilevered model system to a simulated dynamic environment shows significant bias error in the model attitude measurement can occur and is vibration mode and amplitude dependent. For each vibration mode contributing to the bias error, the error is estimated from the measured modal properties and tangential accelerations at the model attitude device. Linear superposition is used to combine the bias estimates for individual modes to determine the overall bias error as a function of time. The modal correction model predicts the bias error to a high degree of accuracy for the vibration modes characterized in the simulated dynamic environment.

  12. Abrasive blast cleaning method for the renewal of worn-out acceleration tubes

    NASA Astrophysics Data System (ADS)

    Bartha, L.; Koltay, E.; Mórik, Gy.

    1996-04-01

    The degradation of the electrical properties of acceleration tubes emerging with performance time is known to be assigned mainly to impurities and surface breakdown tracks appearing on the inner surface of the insulators. Consequently, a radical treatment for removing the surface layer may result in a renewal of the tube. An abrasive blast cleaning procedure has been used on a set of worn-out acceleration tube units. The cleaned tube exhibited its original electrical characteristics and it has been used for more than 4000 h of operation up to the maximum rated voltage of our 5 MV electrostatic accelerator without any observable degradation. XRF and PIXE analytical measurements performed on used and blast-treated insulators as well as on electrode and pump oil samples reveal the contribution of elementary processes in the acceleration tube to the ageing of the tube and indicate the effectness of the blasting process used for the re-establishment of clean surface conditions.

  13. Method of correcting eddy current magnetic fields in particle accelerator vacuum chambers

    DOEpatents

    Danby, Gordon T.; Jackson, John W.

    1991-01-01

    A method for correcting magnetic field aberrations produced by eddy currents induced in a particle accelerator vacuum chamber housing is provided wherein correction windings are attached to selected positions on the housing and the windings are energized by transformer action from secondary coils, which coils are inductively coupled to the poles of electro-magnets that are powered to confine the charged particle beam within a desired orbit as the charged particles are accelerated through the vacuum chamber by a particle-driving rf field. The power inductively coupled to the secondary coils varies as a function of variations in the power supplied by the particle-accelerating rf field to a beam of particles accelerated through the vacuum chamber, so the current in the energized correction coils is effective to cancel eddy current flux fields that would otherwise be induced in the vacuum chamber by power variations in the particle beam.

  14. 2D electron density profile measurement in tokamak by laser-accelerated ion-beam probe.

    PubMed

    Chen, Y H; Yang, X Y; Lin, C; Wang, L; Xu, M; Wang, X G; Xiao, C J

    2014-11-01

    A new concept of Heavy Ion Beam Probe (HIBP) diagnostic has been proposed, of which the key is to replace the electrostatic accelerator of traditional HIBP by a laser-driven ion accelerator. Due to the large energy spread of ions, the laser-accelerated HIBP can measure the two-dimensional (2D) electron density profile of tokamak plasma. In a preliminary simulation, a 2D density profile was reconstructed with a spatial resolution of about 2 cm, and with the error below 15% in the core region. Diagnostics of 2D density fluctuation is also discussed.

  15. Trajectory measurements and correlations in the final focus beam line at the KEK Accelerator Test Facility

    NASA Astrophysics Data System (ADS)

    Renier, Y.; Bambade, P.; Tauchi, T.; White, G. R.; Boogert, S.

    2013-06-01

    The Accelerator Test Facility 2 (ATF2) commissioning group aims to demonstrate the feasibility of the beam delivery system of the next linear colliders (ILC and CLIC) as well as to define and to test the tuning methods. As the design vertical beam sizes of the linear colliders are about few nanometers, the stability of the trajectory as well as the control of the aberrations are very critical. ATF2 commissioning started in December 2008, and thanks to submicron resolution beam position monitors (BPMs), it has been possible to measure the beam position fluctuation along the final focus of ATF2 during the 2009 runs. The optics was not the nominal one yet, with a lower focusing to make the tuning easier. In this paper, a method to measure the noise of each BPM every pulse, in a model-independent way, will be presented. A method to reconstruct the trajectory’s fluctuations is developed which uses the previously determined BPM resolution. As this reconstruction provides a measurement of the beam energy fluctuations, it was also possible to measure the horizontal and vertical dispersion function at each BPMs parasitically. The spatial and angular dispersions can be fitted from these measurements with uncertainties comparable with usual measurements.

  16. Development of accelerated Raman and fluorescent Monte Carlo method

    NASA Astrophysics Data System (ADS)

    Dumont, Alexander P.; Patil, Chetan

    2018-02-01

    Monte Carlo (MC) modeling of photon propagation in turbid media is an essential tool for understanding optical interactions between light and tissue. Insight gathered from outputs of MC models assists in mapping between detected optical signals and bulk tissue optical properties, and as such, has proven useful for inverse calculations of tissue composition and optimization of the design of optical probes. MC models of Raman scattering have previously been implemented without consideration to background autofluorescence, despite its presence in raw measurements. Modeling both Raman and fluorescence profiles at high spectral resolution requires a significant increase in computation, but is more appropriate for investigating issues such as detection limits. We present a new Raman Fluorescence MC model developed atop an existing GPU parallelized MC framework that can run more than 300x times faster than CPU methods. The robust acceleration allows for the efficient production of both Raman and fluorescence outputs from the MC model. In addition, this model can handle arbitrary sample morphologies of excitation and collection geometries to more appropriately mimic experimental settings. We will present the model framework and initial results.

  17. Method of correcting eddy current magnetic fields in particle accelerator vacuum chambers

    DOEpatents

    Danby, G.T.; Jackson, J.W.

    1990-03-19

    A method for correcting magnetic field aberrations produced by eddy currents induced in a particle accelerator vacuum chamber housing is provided wherein correction windings are attached to selected positions on the housing and the windings are energized by transformer action from secondary coils, which coils are inductively coupled to the poles of electro-magnets that are powered to confine the charged particle beam within a desired orbit as the charged particles are accelerated through the vacuum chamber by a particle-driving rf field. The power inductively coupled to the secondary coils varies as a function of variations in the power supplied by the particle-accelerating rf field to a beam of particles accelerated through the vacuum chamber, so the current in the energized correction coils is effective to cancel eddy current flux fields that would otherwise be induced in the vacuum chamber by power variations (dB/dt) in the particle beam.

  18. Hybrid Monte Carlo/Deterministic Methods for Accelerating Active Interrogation Modeling

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

    Peplow, Douglas E.; Miller, Thomas Martin; Patton, Bruce W

    2013-01-01

    The potential for smuggling special nuclear material (SNM) into the United States is a major concern to homeland security, so federal agencies are investigating a variety of preventive measures, including detection and interdiction of SNM during transport. One approach for SNM detection, called active interrogation, uses a radiation source, such as a beam of neutrons or photons, to scan cargo containers and detect the products of induced fissions. In realistic cargo transport scenarios, the process of inducing and detecting fissions in SNM is difficult due to the presence of various and potentially thick materials between the radiation source and themore » SNM, and the practical limitations on radiation source strength and detection capabilities. Therefore, computer simulations are being used, along with experimental measurements, in efforts to design effective active interrogation detection systems. The computer simulations mostly consist of simulating radiation transport from the source to the detector region(s). Although the Monte Carlo method is predominantly used for these simulations, difficulties persist related to calculating statistically meaningful detector responses in practical computing times, thereby limiting their usefulness for design and evaluation of practical active interrogation systems. In previous work, the benefits of hybrid methods that use the results of approximate deterministic transport calculations to accelerate high-fidelity Monte Carlo simulations have been demonstrated for source-detector type problems. In this work, the hybrid methods are applied and evaluated for three example active interrogation problems. Additionally, a new approach is presented that uses multiple goal-based importance functions depending on a particle s relevance to the ultimate goal of the simulation. Results from the examples demonstrate that the application of hybrid methods to active interrogation problems dramatically increases their calculational

  19. Comparison of sampling methods for radiocarbon dating of carbonyls in air samples via accelerator mass spectrometry

    NASA Astrophysics Data System (ADS)

    Schindler, Matthias; Kretschmer, Wolfgang; Scharf, Andreas; Tschekalinskij, Alexander

    2016-05-01

    Three new methods to sample and prepare various carbonyl compounds for radiocarbon measurements were developed and tested. Two of these procedures utilized the Strecker synthetic method to form amino acids from carbonyl compounds with either sodium cyanide or trimethylsilyl cyanide. The third procedure used semicarbazide to form crystalline carbazones with the carbonyl compounds. The resulting amino acids and semicarbazones were then separated and purified using thin layer chromatography. The separated compounds were then combusted to CO2 and reduced to graphite to determine 14C content by accelerator mass spectrometry (AMS). All of these methods were also compared with the standard carbonyl compound sampling method wherein a compound is derivatized with 2,4-dinitrophenylhydrazine and then separated by high-performance liquid chromatography (HPLC).

  20. Repeatable electrical measurement instrumentation for use in the accelerated stress testing of thin film solar cells

    NASA Technical Reports Server (NTRS)

    Davis, C. W.; Lathrop, J. W.

    1985-01-01

    Attention is given to the construction, calibration, and performance of a repeatable measurement system for use in conjunction with the accelerated stress testing of a-Si:H cells. A filtered diode array is utilized to approximate the spectral response of any type of solar cell in discrete portions of the spectrum. It is noted that in order to achieve the necessary degree of overall repeatability, it is necessary to pay particular attention to methods of contacting and positioning the cells.

  1. A variable acceleration calibration system

    NASA Astrophysics Data System (ADS)

    Johnson, Thomas H.

    2011-12-01

    A variable acceleration calibration system that applies loads using gravitational and centripetal acceleration serves as an alternative, efficient and cost effective method for calibrating internal wind tunnel force balances. Two proof-of-concept variable acceleration calibration systems are designed, fabricated and tested. The NASA UT-36 force balance served as the test balance for the calibration experiments. The variable acceleration calibration systems are shown to be capable of performing three component calibration experiments with an approximate applied load error on the order of 1% of the full scale calibration loads. Sources of error are indentified using experimental design methods and a propagation of uncertainty analysis. Three types of uncertainty are indentified for the systems and are attributed to prediction error, calibration error and pure error. Angular velocity uncertainty is shown to be the largest indentified source of prediction error. The calibration uncertainties using a production variable acceleration based system are shown to be potentially equivalent to current methods. The production quality system can be realized using lighter materials and a more precise instrumentation. Further research is needed to account for balance deflection, forcing effects due to vibration, and large tare loads. A gyroscope measurement technique is shown to be capable of resolving the balance deflection angle calculation. Long term research objectives include a demonstration of a six degree of freedom calibration, and a large capacity balance calibration.

  2. Going nuts: Measuring free-fall acceleration by analyzing the sound of falling metal pieces

    NASA Astrophysics Data System (ADS)

    Kuhn, Jochen; Vogt, Patrik; Theilmann, Florian

    2016-03-01

    Galilei presented the kinematics of a one-dimensional accelerated motion with ease and in terms of elegant geometry. Moreover, he believed, "Philosophy [i.e. physics] is written in this grand book—I mean the universe—which stands continually open to our gaze, but it cannot be understood unless one first learns to comprehend the language and interpret the characters in which it is written. It is written in the language of mathematics, and its characters are triangles, circles, and other geometrical figures, without which it is humanly impossible to understand a single word of it." In classroom practice, however, it can be difficult to reveal this mathematical heart of nature; free fall and other accelerated motions often get obscured by friction or other sources of errors. In this paper, we introduce a method of analyzing free-fall motion indirectly by evaluating the noise of freely falling metal pieces. The method connects a deeper understanding of the mathematical structure of accelerated motion with the possibility to derive a numerical value for the free-fall acceleration g.

  3. On accelerated flow of MHD powell-eyring fluid via homotopy analysis method

    NASA Astrophysics Data System (ADS)

    Salah, Faisal; Viswanathan, K. K.; Aziz, Zainal Abdul

    2017-09-01

    The aim of this article is to obtain the approximate analytical solution for incompressible magnetohydrodynamic (MHD) flow for Powell-Eyring fluid induced by an accelerated plate. Both constant and variable accelerated cases are investigated. Approximate analytical solution in each case is obtained by using the Homotopy Analysis Method (HAM). The resulting nonlinear analysis is carried out to generate the series solution. Finally, Graphical outcomes of different values of the material constants parameters on the velocity flow field are discussed and analyzed.

  4. Acceleration and Velocity Sensing from Measured Strain

    NASA Technical Reports Server (NTRS)

    Pak, Chan-Gi; Truax, Roger

    2015-01-01

    A simple approach for computing acceleration and velocity of a structure from the strain is proposed in this study. First, deflection and slope of the structure are computed from the strain using a two-step theory. Frequencies of the structure are computed from the time histories of strain using a parameter estimation technique together with an autoregressive moving average model. From deflection, slope, and frequencies of the structure, acceleration and velocity of the structure can be obtained using the proposed approach. Simple harmonic motion is assumed for the acceleration computations, and the central difference equation with a linear autoregressive model is used for the computations of velocity. A cantilevered rectangular wing model is used to validate the simple approach. Quality of the computed deflection, acceleration, and velocity values are independent of the number of fibers. The central difference equation with a linear autoregressive model proposed in this study follows the target response with reasonable accuracy. Therefore, the handicap of the backward difference equation, phase shift, is successfully overcome.

  5. Locally adaptive parallel temperature accelerated dynamics method

    NASA Astrophysics Data System (ADS)

    Shim, Yunsic; Amar, Jacques G.

    2010-03-01

    The recently-developed temperature-accelerated dynamics (TAD) method [M. Sørensen and A.F. Voter, J. Chem. Phys. 112, 9599 (2000)] along with the more recently developed parallel TAD (parTAD) method [Y. Shim et al, Phys. Rev. B 76, 205439 (2007)] allow one to carry out non-equilibrium simulations over extended time and length scales. The basic idea behind TAD is to speed up transitions by carrying out a high-temperature MD simulation and then use the resulting information to obtain event times at the desired low temperature. In a typical implementation, a fixed high temperature Thigh is used. However, in general one expects that for each configuration there exists an optimal value of Thigh which depends on the particular transition pathways and activation energies for that configuration. Here we present a locally adaptive high-temperature TAD method in which instead of using a fixed Thigh the high temperature is dynamically adjusted in order to maximize simulation efficiency. Preliminary results of the performance obtained from parTAD simulations of Cu/Cu(100) growth using the locally adaptive Thigh method will also be presented.

  6. Paratransit Vehicle Test and Evaluation : Volume 2. Acceleration and Interior Measurement Tests.

    DOT National Transportation Integrated Search

    1978-06-01

    A series of tests and evaluations of two prototype vehicles for paratransit were conducted. This volume (Volume II) presents the test procedure and results of the acceleration and interior measurement test series. The tests determined the acceleratio...

  7. Experimental measurements of rf breakdowns and deflecting gradients in mm-wave metallic accelerating structures

    DOE PAGES

    Dal Forno, Massimo; Dolgashev, Valery; Bowden, Gordon; ...

    2016-05-03

    We present an experimental study of a high-gradient metallic accelerating structure at sub-THz frequencies, where we investigated the physics of rf breakdowns. Wakefields in the structure were excited by an ultrarelativistic electron beam. We present the first quantitative measurements of gradients and metal vacuum rf breakdowns in sub-THz accelerating cavities. When the beam travels off axis, a deflecting field is induced in addition to the longitudinal field. We measured the deflecting forces by observing the displacement and changes in the shape of the electron bunch. This behavior can be exploited for subfemtosecond beam diagnostics.

  8. Convergence acceleration of the Proteus computer code with multigrid methods

    NASA Technical Reports Server (NTRS)

    Demuren, A. O.; Ibraheem, S. O.

    1995-01-01

    This report presents the results of a study to implement convergence acceleration techniques based on the multigrid concept in the two-dimensional and three-dimensional versions of the Proteus computer code. The first section presents a review of the relevant literature on the implementation of the multigrid methods in computer codes for compressible flow analysis. The next two sections present detailed stability analysis of numerical schemes for solving the Euler and Navier-Stokes equations, based on conventional von Neumann analysis and the bi-grid analysis, respectively. The next section presents details of the computational method used in the Proteus computer code. Finally, the multigrid implementation and applications to several two-dimensional and three-dimensional test problems are presented. The results of the present study show that the multigrid method always leads to a reduction in the number of iterations (or time steps) required for convergence. However, there is an overhead associated with the use of multigrid acceleration. The overhead is higher in 2-D problems than in 3-D problems, thus overall multigrid savings in CPU time are in general better in the latter. Savings of about 40-50 percent are typical in 3-D problems, but they are about 20-30 percent in large 2-D problems. The present multigrid method is applicable to steady-state problems and is therefore ineffective in problems with inherently unstable solutions.

  9. Analytical Validation of Accelerator Mass Spectrometry for Pharmaceutical Development: the Measurement of Carbon-14 Isotope Ratio.

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

    Keck, B D; Ognibene, T; Vogel, J S

    2010-02-05

    Accelerator mass spectrometry (AMS) is an isotope based measurement technology that utilizes carbon-14 labeled compounds in the pharmaceutical development process to measure compounds at very low concentrations, empowers microdosing as an investigational tool, and extends the utility of {sup 14}C labeled compounds to dramatically lower levels. It is a form of isotope ratio mass spectrometry that can provide either measurements of total compound equivalents or, when coupled to separation technology such as chromatography, quantitation of specific compounds. The properties of AMS as a measurement technique are investigated here, and the parameters of method validation are shown. AMS, independent of anymore » separation technique to which it may be coupled, is shown to be accurate, linear, precise, and robust. As the sensitivity and universality of AMS is constantly being explored and expanded, this work underpins many areas of pharmaceutical development including drug metabolism as well as absorption, distribution and excretion of pharmaceutical compounds as a fundamental step in drug development. The validation parameters for pharmaceutical analyses were examined for the accelerator mass spectrometry measurement of {sup 14}C/C ratio, independent of chemical separation procedures. The isotope ratio measurement was specific (owing to the {sup 14}C label), stable across samples storage conditions for at least one year, linear over 4 orders of magnitude with an analytical range from one tenth Modern to at least 2000 Modern (instrument specific). Further, accuracy was excellent between 1 and 3 percent while precision expressed as coefficient of variation is between 1 and 6% determined primarily by radiocarbon content and the time spent analyzing a sample. Sensitivity, expressed as LOD and LLOQ was 1 and 10 attomoles of carbon-14 (which can be expressed as compound equivalents) and for a typical small molecule labeled at 10% incorporated with {sup 14}C corresponds to 30

  10. Active control of an innovative seat suspension system with acceleration measurement based friction estimation

    NASA Astrophysics Data System (ADS)

    Ning, Donghong; Sun, Shuaishuai; Li, Hongyi; Du, Haiping; Li, Weihua

    2016-12-01

    In this paper, an innovative active seat suspension system for vehicles is presented. This seat suspension prototype is built with two low cost actuators each of which has one rotary motor and one gear reducer. A H∞ controller with friction compensation is designed for the seat suspension control system where the friction is estimated and compensated based on the measurement of seat acceleration. This principal aim of this research was to control the low frequency vibration transferred or amplified by the vehicle (chassis) suspension, and to maintain the passivity of the seat suspension at high frequency (isolation vibration) while taking into consideration the trade-off between the active seat suspension cost and its high frequency performance. Sinusoidal excitations of 1-4.5 Hz were applied to test the active seat suspension both when controlled and when uncontrolled and this is compared with a well-tuned passive heavy duty vehicle seat suspension. The results indicate the effectiveness of the proposed control algorithm within the tested frequencies. Further tests were conducted using the excitations generated from a quarter-car model under bump and random road profiles. The bump road tests indicate the controlled active seat suspension has good transient response performance. The Power Spectral Density (PSD) method and ISO 2631-1 standards were applied to analyse the seat suspension's acceleration under random road conditions. Although some low magnitude and high frequency noise will inevitably be introduced by the active system, the weighted-frequency Root Mean Square (RMS) acceleration shows that this may not have a large effect on ride comfort. In fact, the ride comfort is improved from being an 'a little uncomfortable' to a 'not uncomfortable' level when compared with the well-tuned passive seat suspension. This low cost active seat suspension design and the proposed controller with the easily measured feedback signals are very practical for real

  11. Soiling of building envelope surfaces and its effect on solar reflectance – Part III: Interlaboratory study of an accelerated aging method for roofing materials

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

    Sleiman, Mohamad; Chen, Sharon; Gilbert, Haley E.

    A laboratory method to simulate natural exposure of roofing materials has been reported in a companion article. Here in the current article, we describe the results of an international, nine-participant interlaboratory study (ILS) conducted in accordance with ASTM Standard E691-09 to establish the precision and reproducibility of this protocol. The accelerated soiling and weathering method was applied four times by each laboratory to replicate coupons of 12 products representing a wide variety of roofing categories (single-ply membrane, factory-applied coating (on metal), bare metal, field-applied coating, asphalt shingle, modified-bitumen cap sheet, clay tile, and concrete tile). Participants reported initial and laboratory-agedmore » values of solar reflectance and thermal emittance. Measured solar reflectances were consistent within and across eight of the nine participating laboratories. Measured thermal emittances reported by six participants exhibited comparable consistency. For solar reflectance, the accelerated aging method is both repeatable and reproducible within an acceptable range of standard deviations: the repeatability standard deviation sr ranged from 0.008 to 0.015 (relative standard deviation of 1.2–2.1%) and the reproducibility standard deviation sR ranged from 0.022 to 0.036 (relative standard deviation of 3.2–5.8%). The ILS confirmed that the accelerated aging method can be reproduced by multiple independent laboratories with acceptable precision. In conclusion, this study supports the adoption of the accelerated aging practice to speed the evaluation and performance rating of new cool roofing materials.« less

  12. MLFMA-accelerated Nyström method for ultrasonic scattering - Numerical results and experimental validation

    NASA Astrophysics Data System (ADS)

    Gurrala, Praveen; Downs, Andrew; Chen, Kun; Song, Jiming; Roberts, Ron

    2018-04-01

    Full wave scattering models for ultrasonic waves are necessary for the accurate prediction of voltage signals received from complex defects/flaws in practical nondestructive evaluation (NDE) measurements. We propose the high-order Nyström method accelerated by the multilevel fast multipole algorithm (MLFMA) as an improvement to the state-of-the-art full-wave scattering models that are based on boundary integral equations. We present numerical results demonstrating improvements in simulation time and memory requirement. Particularly, we demonstrate the need for higher order geom-etry and field approximation in modeling NDE measurements. Also, we illustrate the importance of full-wave scattering models using experimental pulse-echo data from a spherical inclusion in a solid, which cannot be modeled accurately by approximation-based scattering models such as the Kirchhoff approximation.

  13. A coarse-grid projection method for accelerating incompressible flow computations

    NASA Astrophysics Data System (ADS)

    San, Omer; Staples, Anne

    2011-11-01

    We present a coarse-grid projection (CGP) algorithm for accelerating incompressible flow computations, which is applicable to methods involving Poisson equations as incompressibility constraints. CGP methodology is a modular approach that facilitates data transfer with simple interpolations and uses black-box solvers for the Poisson and advection-diffusion equations in the flow solver. Here, we investigate a particular CGP method for the vorticity-stream function formulation that uses the full weighting operation for mapping from fine to coarse grids, the third-order Runge-Kutta method for time stepping, and finite differences for the spatial discretization. After solving the Poisson equation on a coarsened grid, bilinear interpolation is used to obtain the fine data for consequent time stepping on the full grid. We compute several benchmark flows: the Taylor-Green vortex, a vortex pair merging, a double shear layer, decaying turbulence and the Taylor-Green vortex on a distorted grid. In all cases we use either FFT-based or V-cycle multigrid linear-cost Poisson solvers. Reducing the number of degrees of freedom of the Poisson solver by powers of two accelerates these computations while, for the first level of coarsening, retaining the same level of accuracy in the fine resolution vorticity field.

  14. Observation of acceleration and deceleration in gigaelectron-volt-per-metre gradient dielectric wakefield accelerators

    DOE PAGES

    O’Shea, B. D.; Andonian, G.; Barber, S. K.; ...

    2016-09-14

    There is urgent need to develop new acceleration techniques capable of exceeding gigaelectron-volt-per-metre (GeV m –1) gradients in order to enable future generations of both light sources and high-energy physics experiments. To address this need, short wavelength accelerators based on wakefields, where an intense relativistic electron beam radiates the demanded fields directly into the accelerator structure or medium, are currently under intense investigation. One such wakefield based accelerator, the dielectric wakefield accelerator, uses a dielectric lined-waveguide to support a wakefield used for acceleration. Here we show gradients of 1.347±0.020 GeV m –1 using a dielectric wakefield accelerator of 15 cmmore » length, with sub-millimetre transverse aperture, by measuring changes of the kinetic state of relativistic electron beams. We follow this measurement by demonstrating accelerating gradients of 320±17 MeV m –1. As a result, both measurements improve on previous measurements by and order of magnitude and show promise for dielectric wakefield accelerators as sources of high-energy electrons.« less

  15. Observation of acceleration and deceleration in gigaelectron-volt-per-metre gradient dielectric wakefield accelerators

    PubMed Central

    O'Shea, B. D.; Andonian, G.; Barber, S. K.; Fitzmorris, K. L.; Hakimi, S.; Harrison, J.; Hoang, P. D.; Hogan, M. J.; Naranjo, B.; Williams, O. B.; Yakimenko, V.; Rosenzweig, J. B.

    2016-01-01

    There is urgent need to develop new acceleration techniques capable of exceeding gigaelectron-volt-per-metre (GeV m−1) gradients in order to enable future generations of both light sources and high-energy physics experiments. To address this need, short wavelength accelerators based on wakefields, where an intense relativistic electron beam radiates the demanded fields directly into the accelerator structure or medium, are currently under intense investigation. One such wakefield based accelerator, the dielectric wakefield accelerator, uses a dielectric lined-waveguide to support a wakefield used for acceleration. Here we show gradients of 1.347±0.020 GeV m−1 using a dielectric wakefield accelerator of 15 cm length, with sub-millimetre transverse aperture, by measuring changes of the kinetic state of relativistic electron beams. We follow this measurement by demonstrating accelerating gradients of 320±17 MeV m−1. Both measurements improve on previous measurements by and order of magnitude and show promise for dielectric wakefield accelerators as sources of high-energy electrons. PMID:27624348

  16. Automatic detection of lameness in gestating group-housed sows using positioning and acceleration measurements.

    PubMed

    Traulsen, I; Breitenberger, S; Auer, W; Stamer, E; Müller, K; Krieter, J

    2016-06-01

    Lameness is an important issue in group-housed sows. Automatic detection systems are a beneficial diagnostic tool to support management. The aim of the present study was to evaluate data of a positioning system including acceleration measurements to detect lameness in group-housed sows. Data were acquired at the Futterkamp research farm from May 2012 until April 2013. In the gestation unit, 212 group-housed sows were equipped with an ear sensor to sample position and acceleration per sow and second. Three activity indices were calculated per sow and day: path length walked by a sow during the day (Path), number of squares (25×25 cm) visited during the day (Square) and variance of the acceleration measurement during the day (Acc). In addition, data on lameness treatments of the sows and a weekly lameness score were used as reference systems. To determine the influence of a lameness event, all indices were analysed in a linear random regression model. Test day, parity class and day before treatment had a significant influence on all activity indices (P<0.05). In healthy sows, indices Path and Square increased with increasing parity, whereas variance slightly decreased. The indices Path and Square showed a decreasing trend in a 14-day period before a lameness treatment and to a smaller extent before a lameness score of 2 (severe lameness). For the index acceleration, there was no obvious difference between the lame and non-lame periods. In conclusion, positioning and acceleration measurements with ear sensors can be used to describe the activity pattern of sows. However, improvements in sampling rate and analysis techniques should be made for a practical application as an automatic lameness detection system.

  17. Highly-Damped Spectral Acceleration as a Ground Motion Intensity Measure for Estimating Collapse Vulnerability of Buildings

    NASA Astrophysics Data System (ADS)

    Buyco, K.; Heaton, T. H.

    2016-12-01

    Current U.S. seismic code and performance-based design recommendations quantify ground motion intensity using 5%-damped spectral acceleration when estimating the collapse vulnerability of buildings. This intensity measure works well for predicting inter-story drift due to moderate shaking, but other measures have been shown to be better for estimating collapse risk.We propose using highly-damped (>10%) spectral acceleration to assess collapse vulnerability. As damping is increased, the spectral acceleration at a given period T begins to behave like a weighted average of the corresponding lowly-damped (i.e. 5%) spectrum at a range of periods. Weights for periods longer than T increase as damping increases. Using high damping is physically intuitive for two reasons. Firstly, ductile buildings dissipate a large amount of hysteretic energy before collapse and thus behave more like highly-damped systems. Secondly, heavily damaged buildings experience period-lengthening, giving further credence to the weighted-averaging property of highly-damped spectral acceleration.To determine the optimal damping value(s) for this ground motion intensity measure, we conduct incremental dynamic analysis for a suite of ground motions on several different mid-rise steel buildings and select the damping value yielding the lowest dispersion of intensity at the collapse threshold. Spectral acceleration calculated with damping as high as 70% has been shown to be a better indicator of collapse than that with 5% damping.

  18. An ultrasonic-accelerated oxidation method for determining the oxidative stability of biodiesel.

    PubMed

    Avila Orozco, Francisco D; Sousa, Antonio C; Domini, Claudia E; Ugulino Araujo, Mario Cesar; Fernández Band, Beatriz S

    2013-05-01

    Biodiesel is considered an alternative energy because it is produced from fats and vegetable oils by means of transesterification. Furthermore, it consists of fatty acid alkyl esters (FAAS) which have a great influence on biodiesel fuel properties and in the storage lifetime of biodiesel itself. The biodiesel storage stability is directly related to the oxidative stability parameter (Induction Time - IT) which is determined by means of the Rancimat® method. This method uses condutimetric monitoring and induces the degradation of FAAS by heating the sample at a constant temperature. The European Committee for Standardization established a standard (EN 14214) to determine the oxidative stability of biodiesel, which requires it to reach a minimum induction period of 6h as tested by Rancimat® method at 110°C. In this research, we aimed at developing a fast and simple alternative method to determine the induction time (IT) based on the FAAS ultrasonic-accelerated oxidation. The sonodegradation of biodiesel samples was induced by means of an ultrasonic homogenizer fitted with an immersible horn at 480Watts of power and 20 duty cycles. The UV-Vis spectrometry was used to monitor the FAAS sonodegradation by measuring the absorbance at 270nm every 2. Biodiesel samples from different feedstock were studied in this work. In all cases, IT was established as the inflection point of the absorbance versus time curve. The induction time values of all biodiesel samples determined using the proposed method was in accordance with those measured through the Rancimat® reference method by showing a R(2)=0.998. Copyright © 2012 Elsevier B.V. All rights reserved.

  19. Impurity measurements in semiconductor materials using trace element accelerator mass spectrometry

    NASA Astrophysics Data System (ADS)

    McDaniel, F. D.; Datar, S. A.; Nigam, M.; Ravi Prasad, G. V.

    2002-05-01

    Accelerator mass spectrometry (AMS) is commonly used to determine the abundance ratios of long-lived isotopes such as 10B, 14C, 36Cl, 129I, etc. to their stable counterparts at levels as low as 10 -16. Secondary ion mass spectrometry (SIMS) is routinely used to determine impurity levels in materials by depth profiling techniques. Trace-element accelerator mass spectrometry (TEAMS) is a combination of AMS and SIMS, presently being used at the University of North Texas, for high-sensitivity (ppb) impurity analyses of stable isotopes in semiconductor materials. The molecular break-up characteristics of AMS are used with TEAMS to remove the molecular interferences present in SIMS. Measurements made with different substrate/impurity combinations demonstrate that TEAMS has higher sensitivity for many elements than other techniques such as SIMS and can assist with materials characterization issues. For example, measurements of implanted As in the presence of Ge in Ge xSi 1- x/Si is difficult with SIMS because of molecular interferences from 74GeH, 29Si 30Si 16O, etc. With TEAMS, the molecular interferences are removed and higher sensitivities are obtained. Measured substrates include Si, SiGe, CoSi 2, GaAs and GaN. Measured impurities include B, N, F, Mg, P, Cl, Cr, Fe, Ni, Co, Cu, Zn, Ge, As, Se, Mo, Sn and Sb. A number of measurements will be presented to illustrate the range and power of TEAMS.

  20. Real-time estimation of helicopter rotor blade kinematics through measurement of rotation induced acceleration

    NASA Astrophysics Data System (ADS)

    Allred, C. Jeff; Churchill, David; Buckner, Gregory D.

    2017-07-01

    This paper presents a novel approach to monitoring rotor blade flap, lead-lag and pitch using an embedded gyroscope and symmetrically mounted MEMS accelerometers. The central hypothesis is that differential accelerometer measurements are proportional only to blade motion; fuselage acceleration and blade bending are inherently compensated for. The inverse kinematic relationships (from blade position to acceleration and angular rate) are derived and simulated to validate this hypothesis. An algorithm to solve the forward kinematic relationships (from sensor measurement to blade position) is developed using these simulation results. This algorithm is experimentally validated using a prototype device. The experimental results justify continued development of this kinematic estimation approach.

  1. SAMS Acceleration Measurements on Mir from May 1997 to June 1998 (NASA Increments 5, 6, and 7)

    NASA Technical Reports Server (NTRS)

    DeLombard, Richard

    1999-01-01

    During NASA Increments 5, 6, and 7 (May 1997 to June 1998), about eight gigabytes of acceleration data were collected by the Space Acceleration Measurement System (SAMS) onboard the Russian Space Station Mir. The data were recorded on twenty-seven optical disks which were returned to Earth on Orbiter missions STS-86, STS-89, and STS-91. During these increments, SAMS data were collected in the Priroda module to support various microgravity experiments. This report points out some of the salient features of the microgravity acceleration environment to which the experiments were exposed. This report presents an overview of the SAMS acceleration measurements recorded by 10 Hz and 100 Hz sensor heads. The analyses included herein complement those presented in previous Mir increment summary reports prepared by the Principal Investigator Microgravity Services project.

  2. A Least-Squares Commutator in the Iterative Subspace Method for Accelerating Self-Consistent Field Convergence.

    PubMed

    Li, Haichen; Yaron, David J

    2016-11-08

    A least-squares commutator in the iterative subspace (LCIIS) approach is explored for accelerating self-consistent field (SCF) calculations. LCIIS is similar to direct inversion of the iterative subspace (DIIS) methods in that the next iterate of the density matrix is obtained as a linear combination of past iterates. However, whereas DIIS methods find the linear combination by minimizing a sum of error vectors, LCIIS minimizes the Frobenius norm of the commutator between the density matrix and the Fock matrix. This minimization leads to a quartic problem that can be solved iteratively through a constrained Newton's method. The relationship between LCIIS and DIIS is discussed. Numerical experiments suggest that LCIIS leads to faster convergence than other SCF convergence accelerating methods in a statistically significant sense, and in a number of cases LCIIS leads to stable SCF solutions that are not found by other methods. The computational cost involved in solving the quartic minimization problem is small compared to the typical cost of SCF iterations and the approach is easily integrated into existing codes. LCIIS can therefore serve as a powerful addition to SCF convergence accelerating methods in computational quantum chemistry packages.

  3. Accelerated perturbation-resilient block-iterative projection methods with application to image reconstruction

    PubMed Central

    Nikazad, T; Davidi, R; Herman, G. T.

    2013-01-01

    We study the convergence of a class of accelerated perturbation-resilient block-iterative projection methods for solving systems of linear equations. We prove convergence to a fixed point of an operator even in the presence of summable perturbations of the iterates, irrespective of the consistency of the linear system. For a consistent system, the limit point is a solution of the system. In the inconsistent case, the symmetric version of our method converges to a weighted least squares solution. Perturbation resilience is utilized to approximate the minimum of a convex functional subject to the equations. A main contribution, as compared to previously published approaches to achieving similar aims, is a more than an order of magnitude speed-up, as demonstrated by applying the methods to problems of image reconstruction from projections. In addition, the accelerated algorithms are illustrated to be better, in a strict sense provided by the method of statistical hypothesis testing, than their unaccelerated versions for the task of detecting small tumors in the brain from X-ray CT projection data. PMID:23440911

  4. Accelerated perturbation-resilient block-iterative projection methods with application to image reconstruction.

    PubMed

    Nikazad, T; Davidi, R; Herman, G T

    2012-03-01

    We study the convergence of a class of accelerated perturbation-resilient block-iterative projection methods for solving systems of linear equations. We prove convergence to a fixed point of an operator even in the presence of summable perturbations of the iterates, irrespective of the consistency of the linear system. For a consistent system, the limit point is a solution of the system. In the inconsistent case, the symmetric version of our method converges to a weighted least squares solution. Perturbation resilience is utilized to approximate the minimum of a convex functional subject to the equations. A main contribution, as compared to previously published approaches to achieving similar aims, is a more than an order of magnitude speed-up, as demonstrated by applying the methods to problems of image reconstruction from projections. In addition, the accelerated algorithms are illustrated to be better, in a strict sense provided by the method of statistical hypothesis testing, than their unaccelerated versions for the task of detecting small tumors in the brain from X-ray CT projection data.

  5. A method for measurement of ultratrace 79Se with accelerator mass spectrometry

    NASA Astrophysics Data System (ADS)

    Wang, Wei; Guan, Yongjing; He, Ming; Jiang, Shan; Wu, Shaoyong; Li, Chaoli

    2010-04-01

    79Se is a long-lived fission product with chemical and radiological toxicity. It is one of the radionuclides of interest in nuclear waste disposal due to its potential migration capacity to the surface environment. Furthermore, 79Se is an ideal tracer in biomedicine. One of the major obstacles in the measurement of ultratrace 79Se with AMS is the strong interference from the isobaric nuclide 79Br. This paper presents a new ultra-sensitive method for 79Se measurements with AMS. The novel aspects of our procedures include the extraction of SeO2- molecular ions, that results in a suppression of 79Br background by as much as about five orders of magnitude; the selection of Ag 2SeO 3 as the chemical form of Se in the target sample, that brings about a relatively large and stable SeO2- beam current; and the renovation of the multi-anode detector, that makes 79Se better identified from the interfering nuclide 79Br. By using these procedures, a sensitivity of better than 1.0 × 10 -12 has been achieved for 79Se/Se measurement with the CIAE-AMS system. It is then possible to quantify the tracer 79Se in biological samples. Recently, we are prepared to develop the 79Se-AMS biological tracer methodology.

  6. Accelerated Fractional Ventilation Imaging with Hyperpolarized Gas MRI

    PubMed Central

    Emami, Kiarash; Xu, Yinan; Hamedani, Hooman; Profka, Harrilla; Kadlecek, Stephen; Xin, Yi; Ishii, Masaru; Rizi, Rahim R.

    2013-01-01

    PURPOSE To investigate the utility of accelerated imaging to enhance multi-breath fractional ventilation (r) measurement accuracy using HP gas MRI. Undersampling shortens the breath-hold time, thereby reducing the O2-induced signal decay and allows subjects to maintain a more physiologically relevant breathing pattern. Additionally it may improve r estimation accuracy by reducing RF destruction of HP gas. METHODS Image acceleration was achieved by using an 8-channel phased array coil. Undersampled image acquisition was simulated in a series of ventilation images and images were reconstructed for various matrix sizes (48–128) using GRAPPA. Parallel accelerated r imaging was also performed on five mechanically ventilated pigs. RESULTS Optimal acceleration factor was fairly invariable (2.0–2.2×) over the range of simulated resolutions. Estimation accuracy progressively improved with higher resolutions (39–51% error reduction). In vivo r values were not significantly different between the two methods: 0.27±0.09, 0.35±0.06, 0.40±0.04 (standard) versus 0.23±0.05, 0.34±0.03, 0.37±0.02 (accelerated); for anterior, medial and posterior slices, respectively, whereas the corresponding vertical r gradients were significant (P < 0.001): 0.021±0.007 (standard) versus 0.019±0.005 (accelerated) [cm−1]. CONCLUSION Quadruple phased array coil simulations resulted in an optimal acceleration factor of ~2× independent of imaging resolution. Results advocate undersampled image acceleration to improve accuracy of fractional ventilation measurement with HP gas MRI. PMID:23400938

  7. Light scattering microscopy measurements of single nuclei compared with GPU-accelerated FDTD simulations

    NASA Astrophysics Data System (ADS)

    Stark, Julian; Rothe, Thomas; Kieß, Steffen; Simon, Sven; Kienle, Alwin

    2016-04-01

    Single cell nuclei were investigated using two-dimensional angularly and spectrally resolved scattering microscopy. We show that even for a qualitative comparison of experimental and theoretical data, the standard Mie model of a homogeneous sphere proves to be insufficient. Hence, an accelerated finite-difference time-domain method using a graphics processor unit and domain decomposition was implemented to analyze the experimental scattering patterns. The measured cell nuclei were modeled as single spheres with randomly distributed spherical inclusions of different size and refractive index representing the nucleoli and clumps of chromatin. Taking into account the nuclear heterogeneity of a large number of inclusions yields a qualitative agreement between experimental and theoretical spectra and illustrates the impact of the nuclear micro- and nanostructure on the scattering patterns.

  8. Light scattering microscopy measurements of single nuclei compared with GPU-accelerated FDTD simulations.

    PubMed

    Stark, Julian; Rothe, Thomas; Kieß, Steffen; Simon, Sven; Kienle, Alwin

    2016-04-07

    Single cell nuclei were investigated using two-dimensional angularly and spectrally resolved scattering microscopy. We show that even for a qualitative comparison of experimental and theoretical data, the standard Mie model of a homogeneous sphere proves to be insufficient. Hence, an accelerated finite-difference time-domain method using a graphics processor unit and domain decomposition was implemented to analyze the experimental scattering patterns. The measured cell nuclei were modeled as single spheres with randomly distributed spherical inclusions of different size and refractive index representing the nucleoli and clumps of chromatin. Taking into account the nuclear heterogeneity of a large number of inclusions yields a qualitative agreement between experimental and theoretical spectra and illustrates the impact of the nuclear micro- and nanostructure on the scattering patterns.

  9. Accelerated Monte Carlo Methods for Coulomb Collisions

    NASA Astrophysics Data System (ADS)

    Rosin, Mark; Ricketson, Lee; Dimits, Andris; Caflisch, Russel; Cohen, Bruce

    2014-03-01

    We present a new highly efficient multi-level Monte Carlo (MLMC) simulation algorithm for Coulomb collisions in a plasma. The scheme, initially developed and used successfully for applications in financial mathematics, is applied here to kinetic plasmas for the first time. The method is based on a Langevin treatment of the Landau-Fokker-Planck equation and has a rich history derived from the works of Einstein and Chandrasekhar. The MLMC scheme successfully reduces the computational cost of achieving an RMS error ɛ in the numerical solution to collisional plasma problems from (ɛ-3) - for the standard state-of-the-art Langevin and binary collision algorithms - to a theoretically optimal (ɛ-2) scaling, when used in conjunction with an underlying Milstein discretization to the Langevin equation. In the test case presented here, the method accelerates simulations by factors of up to 100. We summarize the scheme, present some tricks for improving its efficiency yet further, and discuss the method's range of applicability. Work performed for US DOE by LLNL under contract DE-AC52- 07NA27344 and by UCLA under grant DE-FG02-05ER25710.

  10. Summary Report of Mission Acceleration Measurements for STS-62, Launched 4 March 1994

    NASA Technical Reports Server (NTRS)

    Rogers, Melissa J. B.; Delombard, Richard

    1994-01-01

    The second mission of the United States Microgravity Payload on-board the STS-62 mission was supported with three accelerometer instruments: the Orbital Acceleration Research Experiment (OARE) and two units of the Space Acceleration Measurements System (SAMS). The March 4, 1994 launch was the fourth successful mission for OARE and the ninth successful mission for SAMS. The OARE instrument utilizes a sensor for very low frequency measurements below one Hertz. The accelerations in this frequency range are typically referred to as quasisteady accelerations. One of the SAMS units had two remote triaxial sensor heads mounted on the forward MPESS structure between two furnance experiments, MEPHISTO and AADSF. These triaxial heads had low-pass filter cut-off frequencies at 10 and 25 Hz. The other SAMS unit utilized three remote triaxial sensor heads. Two of the sensor heads were mounted on the aft MPESS structure between the two experiments IDGE and ZENO. These triaxial heads had low-pass filter cut-off frequencies at 10 and 25 Hz. The third sensor head was mounted on the thermostat housing inside the IDGE experiment container. This triaxial head had a low-pass filter cut-off frequency at 5 Hz. This report is prepared to furnish interested experiment investigators with a guide to evaluating the acceleration environment during STS-62 and as a means of identifying areas which require further study. To achieve this purpose, various pieces of information are included, such as an overview of the STS-62 mission, a description of the accelerometer system flown on STS-62, some specific analysis of the accelerometer data in relation to the various mission activities, and an overview of the low-gravity environment during the entire mission. An evaluation form is included at the end of the report to solicit users' comments about the usefulness of this series of reports.

  11. Long-time atomistic dynamics through a new self-adaptive accelerated molecular dynamics method

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

    Gao, N.; Yang, L.; Gao, F.

    2017-02-27

    A self-adaptive accelerated molecular dynamics method is developed to model infrequent atomic- scale events, especially those events that occur on a rugged free-energy surface. Key in the new development is the use of the total displacement of the system at a given temperature to construct a boost-potential, which is slowly increased to accelerate the dynamics. The temperature is slowly increased to accelerate the dynamics. By allowing the system to evolve from one steady-state con guration to another by overcoming the transition state, this self-evolving approach makes it possible to explore the coupled motion of species that migrate on vastly differentmore » time scales. The migrations of single vacancy (V) and small He-V clusters, and the growth of nano-sized He-V clusters in Fe for times in the order of seconds are studied by this new method. An interstitial- assisted mechanism is rst explored for the migration of a helium-rich He-V cluster, while a new two-component Ostwald ripening mechanism is suggested for He-V cluster growth.« less

  12. SU-F-T-577: Comparison of Small Field Dosimetry Measurements in Fields Shaped with Conical Applicators On Two Different Accelerating Systems

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

    Muir, B; McEwen, M; Belec, J

    2016-06-15

    Purpose: To investigate small field dosimetry measurements and associated uncertainties when conical applicators are used to shape treatment fields from two different accelerating systems. Methods: Output factor measurements are made in water in beams from the CyberKnife radiosurgery system, which uses conical applicators to shape fields from a (flattening filter-free) 6 MV beam, and in a 6 MV beam from the Elekta Precise linear accelerator (with flattening filter) with BrainLab external conical applicators fitted to shape the field. The measurements use various detectors: (i) an Exradin A16 ion chamber, (ii) two Exradin W1 plastic scintillation detectors, (iii) a Sun Nuclearmore » Edge diode, and (iv) two PTW microDiamond synthetic diamond detectors. Profiles are used for accurate detector positioning and to specify field size (FWHM). Output factor measurements are corrected with detector specific correction factors taken from the literature where available and/or from Monte Carlo simulations using the EGSnrc code system. Results: Differences in measurements of up to 1.7% are observed with a given detector type in the same beam (i.e., intra-detector variability). Corrected results from different detectors in the same beam (inter-detector differences) show deviations up to 3 %. Combining data for all detectors and comparing results from the two accelerators results in a 5.9% maximum difference for the smallest field sizes (FWHM=5.2–5.6 mm), well outside the combined uncertainties (∼1% for the smallest beams) and/or differences among detectors. This suggests that the FWHM of a measured profile is not a good specifier to compare results from different small fields with the same nominal energy. Conclusion: Large differences in results for both intra-detector variability and inter-detector differences suggest potentially high uncertainties in detector-specific correction factors. Differences between the results measured in circular fields from different

  13. Standardization of Laser Methods and Techniques for Vibration Measurements and Calibrations

    NASA Astrophysics Data System (ADS)

    von Martens, Hans-Jürgen

    2010-05-01

    The realization and dissemination of the SI units of motion quantities (vibration and shock) have been based on laser interferometer methods specified in international documentary standards. New and refined laser methods and techniques developed by national metrology institutes and by leading manufacturers in the past two decades have been swiftly specified as standard methods for inclusion into in the series ISO 16063 of international documentary standards. A survey of ISO Standards for the calibration of vibration and shock transducers demonstrates the extended ranges and improved accuracy (measurement uncertainty) of laser methods and techniques for vibration and shock measurements and calibrations. The first standard for the calibration of laser vibrometers by laser interferometry or by a reference accelerometer calibrated by laser interferometry (ISO 16063-41) is on the stage of a Draft International Standard (DIS) and may be issued by the end of 2010. The standard methods with refined techniques proved to achieve wider measurement ranges and smaller measurement uncertainties than that specified in the ISO Standards. The applicability of different standardized interferometer methods to vibrations at high frequencies was recently demonstrated up to 347 kHz (acceleration amplitudes up to 350 km/s2). The relative deviations between the amplitude measurement results of the different interferometer methods that were applied simultaneously, differed by less than 1% in all cases.

  14. A new experimental method for the accelerated characterization of composite materials

    NASA Technical Reports Server (NTRS)

    Yeow, Y. T.; Morris, D. H.; Brinson, H. F.

    1978-01-01

    The use of composite materials for a variety of practical structural applications is presented and the need for an accelerated characterization procedure is assessed. A new experimental and analytical method is presented which allows the prediction of long term properties from short term tests. Some preliminary experimental results are presented.

  15. Direct measurement of the image displacement instability in a linear induction accelerator

    NASA Astrophysics Data System (ADS)

    Burris-Mog, T. J.; Ekdahl, C. A.; Moir, D. C.

    2017-06-01

    The image displacement instability (IDI) has been measured on the 20 MeV Axis I of the dual axis radiographic hydrodynamic test facility and compared to theory. A 0.23 kA electron beam was accelerated across 64 gaps in a low solenoid focusing field, and the position of the beam centroid was measured to 34.3 meters downstream from the cathode. One beam dynamics code was used to model the IDI from first principles, while another code characterized the effects of the resistive wall instability and the beam break-up (BBU) instability. Although the BBU instability was not found to influence the IDI, it appears that the IDI influences the BBU. Because the BBU theory does not fully account for the dependence on beam position for coupling to cavity transverse magnetic modes, the effect of the IDI is missing from the BBU theory. This becomes of particular concern to users of linear induction accelerators operating in or near low magnetic guide fields tunes.

  16. Laser-driven ion acceleration: methods, challenges and prospects

    NASA Astrophysics Data System (ADS)

    Badziak, J.

    2018-01-01

    The recent development of laser technology has resulted in the construction of short-pulse lasers capable of generating fs light pulses with PW powers and intensities exceeding 1021 W/cm2, and has laid the basis for the multi-PW lasers, just being built in Europe, that will produce fs pulses of ultra-relativistic intensities ~ 1023 - 1024 W/cm2. The interaction of such an intense laser pulse with a dense target can result in the generation of collimated beams of ions of multi-MeV to GeV energies of sub-ps time durations and of extremely high beam intensities and ion fluencies, barely attainable with conventional RF-driven accelerators. Ion beams with such unique features have the potential for application in various fields of scientific research as well as in medical and technological developments. This paper provides a brief review of state-of-the art in laser-driven ion acceleration, with a focus on basic ion acceleration mechanisms and the production of ultra-intense ion beams. The challenges facing laser-driven ion acceleration studies, in particular those connected with potential applications of laser-accelerated ion beams, are also discussed.

  17. Probing electron acceleration and x-ray emission in laser-plasma accelerators

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

    Thaury, C.; Ta Phuoc, K.; Corde, S.

    2013-06-15

    While laser-plasma accelerators have demonstrated a strong potential in the acceleration of electrons up to giga-electronvolt energies, few experimental tools for studying the acceleration physics have been developed. In this paper, we demonstrate a method for probing the acceleration process. A second laser beam, propagating perpendicular to the main beam, is focused on the gas jet few nanosecond before the main beam creates the accelerating plasma wave. This second beam is intense enough to ionize the gas and form a density depletion, which will locally inhibit the acceleration. The position of the density depletion is scanned along the interaction lengthmore » to probe the electron injection and acceleration, and the betatron X-ray emission. To illustrate the potential of the method, the variation of the injection position with the plasma density is studied.« less

  18. High spatial resolution measurements in a single stage ram accelerator

    NASA Technical Reports Server (NTRS)

    Hinkey, J. B.; Burnham, E. A.; Bruckner, A. P.

    1992-01-01

    High spatial resolution experimental tube wall pressure measurements of ram accelerator gas dynamic phenomena are presented in this paper. The ram accelerator is a ramjet-in-tube device which operates in a manner similar to that of a conventional ramjet. The projectile resembles the centerbody of a ramjet and travels supersonically through a tube filled with a combustible gaseous mixture, with the tube acting as the outer cowling. Pressure data are recorded as the projectile passes by sensors mounted in the tube wall at various locations along the tube. Utilization of special highly instrumented sections of tube has allowed the recording of gas dynamic phenomena with high resolution. High spatial resolution tube wall pressure data from the three regimes of propulsion studied to date (subdetonative, transdetonative, and superdetonative) in a single stage gas mixture are presented and reveal the three-dimensional character of the flow field induced by projectile fins and the canting of the fins and the canting of the projectile body relative to the tube wall. Also presented for comparison to the experimental data are calculations made with an inviscid, three-dimensional CFD code. The knowledge gained from these experiments and simulations is useful in understanding the underlying nature of ram accelerator propulsive regimes, as well as assisting in the validation of three-dimensional CFD coded which model unsteady, chemically reactive flows.

  19. Anderson acceleration of the Jacobi iterative method: An efficient alternative to Krylov methods for large, sparse linear systems

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

    Pratapa, Phanisri P.; Suryanarayana, Phanish; Pask, John E.

    We employ Anderson extrapolation to accelerate the classical Jacobi iterative method for large, sparse linear systems. Specifically, we utilize extrapolation at periodic intervals within the Jacobi iteration to develop the Alternating Anderson–Jacobi (AAJ) method. We verify the accuracy and efficacy of AAJ in a range of test cases, including nonsymmetric systems of equations. We demonstrate that AAJ possesses a favorable scaling with system size that is accompanied by a small prefactor, even in the absence of a preconditioner. In particular, we show that AAJ is able to accelerate the classical Jacobi iteration by over four orders of magnitude, with speed-upsmore » that increase as the system gets larger. Moreover, we find that AAJ significantly outperforms the Generalized Minimal Residual (GMRES) method in the range of problems considered here, with the relative performance again improving with size of the system. As a result, the proposed method represents a simple yet efficient technique that is particularly attractive for large-scale parallel solutions of linear systems of equations.« less

  20. Anderson acceleration of the Jacobi iterative method: An efficient alternative to Krylov methods for large, sparse linear systems

    DOE PAGES

    Pratapa, Phanisri P.; Suryanarayana, Phanish; Pask, John E.

    2015-12-01

    We employ Anderson extrapolation to accelerate the classical Jacobi iterative method for large, sparse linear systems. Specifically, we utilize extrapolation at periodic intervals within the Jacobi iteration to develop the Alternating Anderson–Jacobi (AAJ) method. We verify the accuracy and efficacy of AAJ in a range of test cases, including nonsymmetric systems of equations. We demonstrate that AAJ possesses a favorable scaling with system size that is accompanied by a small prefactor, even in the absence of a preconditioner. In particular, we show that AAJ is able to accelerate the classical Jacobi iteration by over four orders of magnitude, with speed-upsmore » that increase as the system gets larger. Moreover, we find that AAJ significantly outperforms the Generalized Minimal Residual (GMRES) method in the range of problems considered here, with the relative performance again improving with size of the system. As a result, the proposed method represents a simple yet efficient technique that is particularly attractive for large-scale parallel solutions of linear systems of equations.« less

  1. Shelf life prediction of canned fried-rice using accelerated shelf life testing (ASLT) arrhenius method

    NASA Astrophysics Data System (ADS)

    Kurniadi, M.; Bintang, R.; Kusumaningrum, A.; Nursiwi, A.; Nurhikmat, A.; Susanto, A.; Angwar, M.; Triwiyono; Frediansyah, A.

    2017-12-01

    Research on shelf-life prediction of canned fried rice using Accelerated Shelf-life Test (ASLT) of Arrhenius model has been conducted. The aim of this research to predict shelf life of canned-fried rice products. Lethality value of 121°C for 15 and 20 minutes and Total Plate count methods are used to determine time and temperatures of sterilization process.Various storage temperatures of ASLT Arrhenius method were 35, 45 and 55°C during 35days. Rancidity is one of the derivation quality of canned fried rice. In this research, sample of canned fried rice is tested using rancidity value (TBA). TBA value was used as parameter which be measured once a week periodically. The use of can for fried rice without any chemical preservative is one of the advantage of the product, additionaly the use of physicalproperties such as temperature and pressure during its process can extend the shelf life and reduce the microbial contamination. The same research has never done before for fried rice as ready to eat meal. The result showed that the optimum conditions of sterilization process were 121°C,15 minutes with total plate count number of 9,3 × 101 CFU/ml. Lethality value of canned fried rice at 121°C,15 minutes was 3.63 minutes. The calculated Shelf-life of canned fried rice using Accelerated Shelf-life Test (ASLT) of Arrhenius method was 10.3 months.

  2. Multi-GPU Accelerated Admittance Method for High-Resolution Human Exposure Evaluation.

    PubMed

    Xiong, Zubiao; Feng, Shi; Kautz, Richard; Chandra, Sandeep; Altunyurt, Nevin; Chen, Ji

    2015-12-01

    A multi-graphics processing unit (GPU) accelerated admittance method solver is presented for solving the induced electric field in high-resolution anatomical models of human body when exposed to external low-frequency magnetic fields. In the solver, the anatomical model is discretized as a three-dimensional network of admittances. The conjugate orthogonal conjugate gradient (COCG) iterative algorithm is employed to take advantage of the symmetric property of the complex-valued linear system of equations. Compared against the widely used biconjugate gradient stabilized method, the COCG algorithm can reduce the solving time by 3.5 times and reduce the storage requirement by about 40%. The iterative algorithm is then accelerated further by using multiple NVIDIA GPUs. The computations and data transfers between GPUs are overlapped in time by using asynchronous concurrent execution design. The communication overhead is well hidden so that the acceleration is nearly linear with the number of GPU cards. Numerical examples show that our GPU implementation running on four NVIDIA Tesla K20c cards can reach 90 times faster than the CPU implementation running on eight CPU cores (two Intel Xeon E5-2603 processors). The implemented solver is able to solve large dimensional problems efficiently. A whole adult body discretized in 1-mm resolution can be solved in just several minutes. The high efficiency achieved makes it practical to investigate human exposure involving a large number of cases with a high resolution that meets the requirements of international dosimetry guidelines.

  3. Validation of a noninvasive system for measuring head acceleration for use during boxing competition.

    PubMed

    Beckwith, Jonathan G; Chu, Jeffrey J; Greenwald, Richard M

    2007-08-01

    Although the epidemiology and mechanics of concussion in sports have been investigated for many years, the biomechanical factors that contribute to mild traumatic brain injury remain unclear because of the difficulties in measuring impact events in the field. The purpose of this study was to validate an instrumented boxing headgear (IBH) that can be used to measure impact severity and location during play. The instrumented boxing headgear data were processed to determine linear and rotational acceleration at the head center of gravity, impact location, and impact severity metrics, such as the Head Injury Criterion (HIC) and Gadd Severity Index (GSI). The instrumented boxing headgear was fitted to a Hybrid III (HIII) head form and impacted with a weighted pendulum to characterize accuracy and repeatability. Fifty-six impacts over 3 speeds and 5 locations were used to simulate blows most commonly observed in boxing. A high correlation between the HIII and instrumented boxing headgear was established for peak linear and rotational acceleration (r2= 0.91), HIC (r2 = 0.88), and GSI (r2 = 0.89). Mean location error was 9.7 +/- 5.2 masculine. Based on this study, the IBH is a valid system for measuring head acceleration and impact location that can be integrated into training and competition.

  4. On some variational acceleration techniques and related methods for local refinement

    NASA Astrophysics Data System (ADS)

    Teigland, Rune

    1998-10-01

    This paper shows that the well-known variational acceleration method described by Wachspress (E. Wachspress, Iterative Solution of Elliptic Systems and Applications to the Neutron Diffusion Equations of Reactor Physics, Prentice-Hall, Englewood Cliffs, NJ, 1966) and later generalized to multilevels (known as the additive correction multigrid method (B.R Huthchinson and G.D. Raithby, Numer. Heat Transf., 9, 511-537 (1986))) is similar to the FAC method of McCormick and Thomas (S.F McCormick and J.W. Thomas, Math. Comput., 46, 439-456 (1986)) and related multilevel methods. The performance of the method is demonstrated for some simple model problems using local refinement and suggestions for improving the performance of the method are given.

  5. A method for measuring the inertia properties of rigid bodies

    NASA Astrophysics Data System (ADS)

    Gobbi, M.; Mastinu, G.; Previati, G.

    2011-01-01

    A method for the measurement of the inertia properties of rigid bodies is presented. Given a rigid body and its mass, the method allows to measure (identify) the centre of gravity location and the inertia tensor during a single test. The proposed technique is based on the analysis of the free motion of a multi-cable pendulum to which the body under consideration is connected. The motion of the pendulum and the forces acting on the system are recorded and the inertia properties are identified by means of a proper mathematical procedure based on a least square estimation. After the body is positioned on the test rig, the full identification procedure takes less than 10 min. The natural frequencies of the pendulum and the accelerations involved are quite low, making this method suitable for many practical applications. In this paper, the proposed method is described and two test rigs are presented: the first is developed for bodies up to 3500 kg and the second for bodies up to 400 kg. A validation of the measurement method is performed with satisfactory results. The test rig holds a third part quality certificate according to an ISO 9001 standard and could be scaled up to measure the inertia properties of huge bodies, such as trucks, airplanes or even ships.

  6. Convergence acceleration of molecular dynamics methods for shocked materials using velocity scaling

    NASA Astrophysics Data System (ADS)

    Taylor, DeCarlos E.

    2017-03-01

    In this work, a convergence acceleration method applicable to extended system molecular dynamics techniques for shock simulations of materials is presented. The method uses velocity scaling to reduce the instantaneous value of the Rankine-Hugoniot conservation of energy constraint used in extended system molecular dynamics methods to more rapidly drive the system towards a converged Hugoniot state. When used in conjunction with the constant stress Hugoniostat method, the velocity scaled trajectories show faster convergence to the final Hugoniot state with little difference observed in the converged Hugoniot energy, pressure, volume and temperature. A derivation of the scale factor is presented and the performance of the technique is demonstrated using the boron carbide armour ceramic as a test material. It is shown that simulation of boron carbide Hugoniot states, from 5 to 20 GPa, using both a classical Tersoff potential and an ab initio density functional, are more rapidly convergent when the velocity scaling algorithm is applied. The accelerated convergence afforded by the current algorithm enables more rapid determination of Hugoniot states thus reducing the computational demand of such studies when using expensive ab initio or classical potentials.

  7. Summary of SLAC's SEY Measurement On Flat Accelerator Wall Materials

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

    Le Pimpec, F.; /PSI, Villigen /SLAC

    The electron cloud effect (ECE) causes beam instabilities in accelerator structures with intense positively charged bunched beams. Reduction of the secondary electron yield (SEY) of the beam pipe inner wall is effective in controlling cloud formation. We summarize SEY results obtained from flat TiN, TiZrV and Al surfaces carried out in a laboratory environment. SEY was measured after thermal conditioning, as well as after low energy, less than 300 eV, particle exposure.

  8. High power ring methods and accelerator driven subcritical reactor application

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

    Tahar, Malek Haj

    2016-08-07

    High power proton accelerators allow providing, by spallation reaction, the neutron fluxes necessary in the synthesis of fissile material, starting from Uranium 238 or Thorium 232. This is the basis of the concept of sub-critical operation of a reactor, for energy production or nuclear waste transmutation, with the objective of achieving cleaner, safer and more efficient process than today’s technologies allow. Designing, building and operating a proton accelerator in the 500-1000 MeV energy range, CW regime, MW power class still remains a challenge nowadays. There is a limited number of installations at present achieving beam characteristics in that class, e.g.,more » PSI in Villigen, 590 MeV CW beam from a cyclotron, SNS in Oakland, 1 GeV pulsed beam from a linear accelerator, in addition to projects as the ESS in Europe, a 5 MW beam from a linear accelerator. Furthermore, coupling an accelerator to a sub-critical nuclear reactor is a challenging proposition: some of the key issues/requirements are the design of a spallation target to withstand high power densities as well as ensure the safety of the installation. These two domains are the grounds of the PhD work: the focus is on the high power ring methods in the frame of the KURRI FFAG collaboration in Japan: upgrade of the installation towards high intensity is crucial to demonstrate the high beam power capability of FFAG. Thus, modeling of the beam dynamics and benchmarking of different codes was undertaken to validate the simulation results. Experimental results revealed some major losses that need to be understood and eventually overcome. By developing analytical models that account for the field defects, one identified major sources of imperfection in the design of scaling FFAG that explain the important tune variations resulting in the crossing of several betatron resonances. A new formula is derived to compute the tunes and properties established that characterize the effect of the field

  9. Shelf life prediction of apple brownies using accelerated method

    NASA Astrophysics Data System (ADS)

    Pulungan, M. H.; Sukmana, A. D.; Dewi, I. A.

    2018-03-01

    The aim of this research was to determine shelf life of apple brownies. Shelf life was determined with Accelerated Shelf Life Testing method and Arrhenius equation. Experiment was conducted at 25, 35, and 45°C for 30 days. Every five days, the sample was analysed for free fatty acid (FFA), water activity (Aw), and organoleptic acceptance (flavour, aroma, and texture). The shelf life of the apple brownies based on FFA were 110, 54, and 28 days at temperature of 25, 35, and 45°C, respectively.

  10. Convergence acceleration of the Proteus computer code with multigrid methods

    NASA Technical Reports Server (NTRS)

    Demuren, A. O.; Ibraheem, S. O.

    1992-01-01

    Presented here is the first part of a study to implement convergence acceleration techniques based on the multigrid concept in the Proteus computer code. A review is given of previous studies on the implementation of multigrid methods in computer codes for compressible flow analysis. Also presented is a detailed stability analysis of upwind and central-difference based numerical schemes for solving the Euler and Navier-Stokes equations. Results are given of a convergence study of the Proteus code on computational grids of different sizes. The results presented here form the foundation for the implementation of multigrid methods in the Proteus code.

  11. SAMS Acceleration Measurements on Mir From January to May 1997 (NASA Increment 4)

    NASA Technical Reports Server (NTRS)

    DeLombard, Richard

    1998-01-01

    During NASA Increment 4 (January to May 1997), about 5 gigabytes of acceleration data were collected by the Space Acceleration Measurements System (SAMS) onboard the Russian Space Station, Mir. The data were recorded on 28 optical disks which were returned to Earth on STS-84. During this increment, SAMS data were collected in the Priroda module to support the Mir Structural Dynamics Experiment (MiSDE), the Binary Colloidal Alloy Tests (BCAT), Angular Liquid Bridge (ALB), Candle Flames in Microgravity (CFM), Diffusion Controlled Apparatus Module (DCAM), Enhanced Dynamic Load Sensors (EDLS), Forced Flow Flame Spreading Test (FFFT), Liquid Metal Diffusion (LMD), Protein Crystal Growth in Dewar (PCG/Dewar), Queen's University Experiments in Liquid Diffusion (QUELD), and Technical Evaluation of MIM (TEM). This report points out some of the salient features of the microgravity environment to which these experiments were exposed. Also documented are mission events of interest such as the docked phase of STS-84 operations, a Progress engine burn, Soyuz vehicle docking and undocking, and Progress vehicle docking. This report presents an overview of the SAMS acceleration measurements recorded by 10 Hz and 100 Hz sensor heads. The analyses included herein complement those presented in previous summary reports prepared by the Principal Investigator Microgravity Services (PIMS) group.

  12. An accelerated training method for back propagation networks

    NASA Technical Reports Server (NTRS)

    Shelton, Robert O. (Inventor)

    1993-01-01

    The principal objective is to provide a training procedure for a feed forward, back propagation neural network which greatly accelerates the training process. A set of orthogonal singular vectors are determined from the input matrix such that the standard deviations of the projections of the input vectors along these singular vectors, as a set, are substantially maximized, thus providing an optimal means of presenting the input data. Novelty exists in the method of extracting from the set of input data, a set of features which can serve to represent the input data in a simplified manner, thus greatly reducing the time/expense to training the system.

  13. Acceleration and Velocity Sensing from Measured Strain

    NASA Technical Reports Server (NTRS)

    Pak, Chan-Gi; Truax, Roger

    2016-01-01

    A simple approach for computing acceleration and velocity of a structure from the strain is proposed in this study. First, deflection and slope of the structure are computed from the strain using a two-step theory. Frequencies of the structure are computed from the time histories of strain using a parameter estimation technique together with an Autoregressive Moving Average model. From deflection, slope, and frequencies of the structure, acceleration and velocity of the structure can be obtained using the proposed approach. shape sensing, fiber optic strain sensor, system equivalent reduction and expansion process.

  14. Engineering survey planning for the alignment of a particle accelerator: part I. Proposition of an assessment method

    NASA Astrophysics Data System (ADS)

    Junqueira Leão, Rodrigo; Raffaelo Baldo, Crhistian; Collucci da Costa Reis, Maria Luisa; Alves Trabanco, Jorge Luiz

    2018-03-01

    The performance of particle accelerators depends highly on the relative alignment between their components. The position and orientation of the magnetic lenses that form the trajectory of the charged beam is kept to micrometric tolerances in a range of hundreds of meters of the length of the machines. Therefore, the alignment problem is fundamentally of a dimensional metrology nature. There is no common way of expressing these tolerances in terms of terminology and alignment concept. The alignment needs for a certain machine is normally given in terms of deviations between the position of any magnet in the accelerator and the fitted line that relates the actual position of the magnets’ assembly. Root mean square errors and standard deviations are normally used interchangeably and measurement uncertainty is often neglected. Although some solutions have been employed successfully in several accelerators, there is no off-the-shelf solution to perform the alignment. Also, each alignment campaign makes use of different measuring instruments to achieve the desired results, which makes the alignment process a complex measurement chain. This paper explores these issues by reviewing the tolerances specified for the alignment of particle accelerators, and proposes a metric to assess the quality of the alignment. The metric has the advantage of fully integrating the measurement uncertainty in the process.

  15. Accelerator Science: Collider vs. Fixed Target

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

    Lincoln, Don

    Particle physics experiments employ high energy particle accelerators to make their measurements. However there are many kinds of particle accelerators with many interesting techniques. One important dichotomy is whether one takes a particle beam and have it hit a stationary target of atoms, or whether one takes two counter rotating beams of particles and smashes them together head on. In this video, Fermilab’s Dr. Don Lincoln explains the pros and cons of these two powerful methods of exploring the rules of the universe.

  16. Accelerator Science: Collider vs. Fixed Target

    ScienceCinema

    Lincoln, Don

    2018-01-16

    Particle physics experiments employ high energy particle accelerators to make their measurements. However there are many kinds of particle accelerators with many interesting techniques. One important dichotomy is whether one takes a particle beam and have it hit a stationary target of atoms, or whether one takes two counter rotating beams of particles and smashes them together head on. In this video, Fermilab’s Dr. Don Lincoln explains the pros and cons of these two powerful methods of exploring the rules of the universe.

  17. Note: An online testing method for lifetime projection of high power light-emitting diode under accelerated reliability test.

    PubMed

    Chen, Qi; Chen, Quan; Luo, Xiaobing

    2014-09-01

    In recent years, due to the fast development of high power light-emitting diode (LED), its lifetime prediction and assessment have become a crucial issue. Although the in situ measurement has been widely used for reliability testing in laser diode community, it has not been applied commonly in LED community. In this paper, an online testing method for LED life projection under accelerated reliability test was proposed and the prototype was built. The optical parametric data were collected. The systematic error and the measuring uncertainty were calculated to be within 0.2% and within 2%, respectively. With this online testing method, experimental data can be acquired continuously and sufficient amount of data can be gathered. Thus, the projection fitting accuracy can be improved (r(2) = 0.954) and testing duration can be shortened.

  18. The instantaneous linear motion information measurement method based on inertial sensors for ships

    NASA Astrophysics Data System (ADS)

    Yang, Xu; Huang, Jing; Gao, Chen; Quan, Wei; Li, Ming; Zhang, Yanshun

    2018-05-01

    Ship instantaneous line motion information is the important foundation for ship control, which needs to be measured accurately. For this purpose, an instantaneous line motion measurement method based on inertial sensors is put forward for ships. By introducing a half-fixed coordinate system to realize the separation between instantaneous line motion and ship master movement, the instantaneous line motion acceleration of ships can be obtained with higher accuracy. Then, the digital high-pass filter is applied to suppress the velocity error caused by the low frequency signal such as schuler period. Finally, the instantaneous linear motion displacement of ships can be measured accurately. Simulation experimental results show that the method is reliable and effective, and can realize the precise measurement of velocity and displacement of instantaneous line motion for ships.

  19. Accelerator-based neutrino oscillation experiments

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

    Harris, Deborah A.; /Fermilab

    2007-12-01

    Neutrino oscillations were first discovered by experiments looking at neutrinos coming from extra-terrestrial sources, namely the sun and the atmosphere, but we will be depending on earth-based sources to take many of the next steps in this field. This article describes what has been learned so far from accelerator-based neutrino oscillation experiments, and then describe very generally what the next accelerator-based steps are. In section 2 the article discusses how one uses an accelerator to make a neutrino beam, in particular, one made from decays in flight of charged pions. There are several different neutrino detection methods currently in use,more » or under development. In section 3 these are presented, with a description of the general concept, an example of such a detector, and then a brief discussion of the outstanding issues associated with this detection technique. Finally, section 4 describes how the measurements of oscillation probabilities are made. This includes a description of the near detector technique and how it can be used to make the most precise measurements of neutrino oscillations.« less

  20. The spinning disc: studying radial acceleration and its damping process with smartphone acceleration sensors

    NASA Astrophysics Data System (ADS)

    Hochberg, K.; Gröber, S.; Kuhn, J.; Müller, A.

    2014-03-01

    Here, we show the possibility of analysing circular motion and acceleration using the acceleration sensors of smartphones. For instance, the known linear dependence of the radial acceleration on the distance to the centre (a constant angular frequency) can be shown using multiple smartphones attached to a revolving disc. As a second example, the decrease of the radial acceleration and the rotation frequency due to friction can be measured and fitted with a quadratic function, in accordance with theory. Finally, because the disc is not set up exactly horizontal, each smartphone measures a component of the gravitational acceleration that adds to the radial acceleration during one half of the period and subtracts from the radial acceleration during the other half. Hence, every graph shows a small modulation, which can be used to determine the rotation frequency, thus converting a ‘nuisance effect’ into a source of useful information, making additional measurements with stopwatches or the like unnecessary.

  1. A flexible nonlinear diffusion acceleration method for the S N transport equations discretized with discontinuous finite elements

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

    Schunert, Sebastian; Wang, Yaqi; Gleicher, Frederick

    This paper presents a flexible nonlinear diffusion acceleration (NDA) method that discretizes both the S N transport equation and the diffusion equation using the discontinuous finite element method (DFEM). The method is flexible in that the diffusion equation can be discretized on a coarser mesh with the only restriction that it is nested within the transport mesh and the FEM shape function orders of the two equations can be different. The consistency of the transport and diffusion solutions at convergence is defined by using a projection operator mapping the transport into the diffusion FEM space. The diffusion weak form ismore » based on the modified incomplete interior penalty (MIP) diffusion DFEM discretization that is extended by volumetric drift, interior face, and boundary closure terms. In contrast to commonly used coarse mesh finite difference (CMFD) methods, the presented NDA method uses a full FEM discretized diffusion equation for acceleration. Suitable projection and prolongation operators arise naturally from the FEM framework. Via Fourier analysis and numerical experiments for a one-group, fixed source problem the following properties of the NDA method are established for structured quadrilateral meshes: (1) the presented method is unconditionally stable and effective in the presence of mild material heterogeneities if the same mesh and identical shape functions either of the bilinear or biquadratic type are used, (2) the NDA method remains unconditionally stable in the presence of strong heterogeneities, (3) the NDA method with bilinear elements extends the range of effectiveness and stability by a factor of two when compared to CMFD if a coarser diffusion mesh is selected. In addition, the method is tested for solving the C5G7 multigroup, eigenvalue problem using coarse and fine mesh acceleration. Finally, while NDA does not offer an advantage over CMFD for fine mesh acceleration, it reduces the iteration count required for convergence by almost

  2. A flexible nonlinear diffusion acceleration method for the S N transport equations discretized with discontinuous finite elements

    DOE PAGES

    Schunert, Sebastian; Wang, Yaqi; Gleicher, Frederick; ...

    2017-02-21

    This paper presents a flexible nonlinear diffusion acceleration (NDA) method that discretizes both the S N transport equation and the diffusion equation using the discontinuous finite element method (DFEM). The method is flexible in that the diffusion equation can be discretized on a coarser mesh with the only restriction that it is nested within the transport mesh and the FEM shape function orders of the two equations can be different. The consistency of the transport and diffusion solutions at convergence is defined by using a projection operator mapping the transport into the diffusion FEM space. The diffusion weak form ismore » based on the modified incomplete interior penalty (MIP) diffusion DFEM discretization that is extended by volumetric drift, interior face, and boundary closure terms. In contrast to commonly used coarse mesh finite difference (CMFD) methods, the presented NDA method uses a full FEM discretized diffusion equation for acceleration. Suitable projection and prolongation operators arise naturally from the FEM framework. Via Fourier analysis and numerical experiments for a one-group, fixed source problem the following properties of the NDA method are established for structured quadrilateral meshes: (1) the presented method is unconditionally stable and effective in the presence of mild material heterogeneities if the same mesh and identical shape functions either of the bilinear or biquadratic type are used, (2) the NDA method remains unconditionally stable in the presence of strong heterogeneities, (3) the NDA method with bilinear elements extends the range of effectiveness and stability by a factor of two when compared to CMFD if a coarser diffusion mesh is selected. In addition, the method is tested for solving the C5G7 multigroup, eigenvalue problem using coarse and fine mesh acceleration. Finally, while NDA does not offer an advantage over CMFD for fine mesh acceleration, it reduces the iteration count required for convergence by almost

  3. Direct and accelerated parameter mapping using the unscented Kalman filter.

    PubMed

    Zhao, Li; Feng, Xue; Meyer, Craig H

    2016-05-01

    To accelerate parameter mapping using a new paradigm that combines image reconstruction and model regression as a parameter state-tracking problem. In T2 mapping, the T2 map is first encoded in parameter space by multi-TE measurements and then encoded by Fourier transformation with readout/phase encoding gradients. Using a state transition function and a measurement function, the unscented Kalman filter can describe T2 mapping as a dynamic system and directly estimate the T2 map from the k-space data. The proposed method was validated with a numerical brain phantom and volunteer experiments with a multiple-contrast spin echo sequence. Its performance was compared with a conjugate-gradient nonlinear inversion method at undersampling factors of 2 to 8. An accelerated pulse sequence was developed based on this method to achieve prospective undersampling. Compared with the nonlinear inversion reconstruction, the proposed method had higher precision, improved structural similarity and reduced normalized root mean squared error, with acceleration factors up to 8 in numerical phantom and volunteer studies. This work describes a new perspective on parameter mapping by state tracking. The unscented Kalman filter provides a highly accelerated and efficient paradigm for T2 mapping. © 2015 Wiley Periodicals, Inc.

  4. Acceleration Environment of the International Space Station

    NASA Technical Reports Server (NTRS)

    McPherson, Kevin; Kelly, Eric; Keller, Jennifer

    2009-01-01

    Measurement of the microgravity acceleration environment on the International Space Station has been accomplished by two accelerometer systems since 2001. The Microgravity Acceleration Measurement System records the quasi-steady microgravity environment, including the influences of aerodynamic drag, vehicle rotation, and venting effects. Measurement of the vibratory/transient regime, comprised of vehicle, crew, and equipment disturbances, has been accomplished by the Space Acceleration Measurement System-II. Until the arrival of the Columbus Orbital Facility and the Japanese Experiment Module, the location of these sensors, and therefore, the measurement of the microgravity acceleration environment, has been limited to within the United States Laboratory. Japanese Aerospace Exploration Agency has developed a vibratory acceleration measurement system called the Microgravity Measurement Apparatus which will be deployed within the Japanese Experiment Module to make distributed measurements of the Japanese Experiment Module's vibratory acceleration environment. Two Space Acceleration Measurement System sensors from the United States Laboratory will be re-deployed to support vibratory acceleration data measurement within the Columbus Orbital Facility. The additional measurement opportunities resulting from the arrival of these new laboratories allows Principal Investigators with facilities located in these International Space Station research laboratories to obtain microgravity acceleration data in support of their sensitive experiments. The Principal Investigator Microgravity Services project, at NASA Glenn Research Center, in Cleveland, Ohio, has supported acceleration measurement systems and the microgravity scientific community through the processing, characterization, distribution, and archival of the microgravity acceleration data obtained from the International Space Station acceleration measurement systems. This paper summarizes the PIMS capabilities available

  5. Intraoperative acceleration measurements to quantify improvement in tremor during deep brain stimulation surgery.

    PubMed

    Shah, Ashesh; Coste, Jérôme; Lemaire, Jean-Jacques; Taub, Ethan; Schüpbach, W M Michael; Pollo, Claudio; Schkommodau, Erik; Guzman, Raphael; Hemm-Ode, Simone

    2017-05-01

    Deep brain stimulation (DBS) surgery is extensively used in the treatment of movement disorders. Nevertheless, methods to evaluate the clinical response during intraoperative stimulation tests to identify the optimal position for the implantation of the chronic DBS lead remain subjective. In this paper, we describe a new, versatile method for quantitative intraoperative evaluation of improvement in tremor with an acceleration sensor that is mounted on the patient's wrist during surgery. At each anatomical test position, the improvement in tremor compared to the initial tremor is estimated on the basis of extracted outcome measures. This method was tested on 15 tremor patients undergoing DBS surgery in two centers. Data from 359 stimulation tests were acquired. Our results suggest that accelerometric evaluation detects tremor changes more sensitively than subjective visual ratings. The effective stimulation current amplitudes identified from the quantitative data (1.1 ± 0.8 mA) are lower than those identified by visual evaluation (1.7 ± 0.8 mA) for similar improvement in tremor. Additionally, if these data had been used to choose the chronic implant position of the DBS lead, 15 of the 26 choices would have been different. These results show that our method of accelerometric evaluation can potentially improve DBS targeting.

  6. Social-emotional characteristics of gifted accelerated and non-accelerated students in the Netherlands.

    PubMed

    Hoogeveen, Lianne; van Hell, Janet G; Verhoeven, Ludo

    2012-12-01

    In the studies of acceleration conducted so far a multidimensional perspective has largely been neglected. No attempt has been made to relate social-emotional characteristics of accelerated versus non-accelerated students in perspective of environmental factors. In this study, social-emotional characteristics of accelerated gifted students in the Netherlands were examined in relation to personal and environmental factors. Self-concept and social contacts of accelerated (n = 148) and non-accelerated (n = 55) gifted students, aged 4 to 27 (M = 11.22, SD = 4.27) were measured. Self-concept and social contacts of accelerated and non-accelerated gifted students were measured using a questionnaire and a diary, and parents of these students evaluated their behavioural characteristics. Gender and birth order were studied as personal factors and grade, classroom, teachers' gender, teaching experience, and the quality of parent-school contact as environmental factors. The results showed minimal differences in the social-emotional characteristics of accelerated and non-accelerated gifted students. The few differences we found favoured the accelerated students. We also found that multiple grade skipping does not have negative effects on social-emotional characteristics, and that long-term effects of acceleration tend to be positive. As regards the possible modulation of personal and environmental factors, we merely found an impact of such factors in the non-accelerated group. The results of this study strongly suggest that social-emotional characteristics of accelerated gifted students and non-accelerated gifted students are largely similar. These results thus do not support worries expressed by teachers about the acceleration of gifted students. Our findings parallel the outcomes of earlier studies in the United States and Germany in that we observed that acceleration does not harm gifted students, not even in the case of multiple grade skipping. On the contrary, there is a

  7. Analysis of Monte Carlo accelerated iterative methods for sparse linear systems: Analysis of Monte Carlo accelerated iterative methods for sparse linear systems

    DOE PAGES

    Benzi, Michele; Evans, Thomas M.; Hamilton, Steven P.; ...

    2017-03-05

    Here, we consider hybrid deterministic-stochastic iterative algorithms for the solution of large, sparse linear systems. Starting from a convergent splitting of the coefficient matrix, we analyze various types of Monte Carlo acceleration schemes applied to the original preconditioned Richardson (stationary) iteration. We expect that these methods will have considerable potential for resiliency to faults when implemented on massively parallel machines. We also establish sufficient conditions for the convergence of the hybrid schemes, and we investigate different types of preconditioners including sparse approximate inverses. Numerical experiments on linear systems arising from the discretization of partial differential equations are presented.

  8. Quality control methods for linear accelerator radiation and mechanical axes alignment.

    PubMed

    Létourneau, Daniel; Keller, Harald; Becker, Nathan; Amin, Md Nurul; Norrlinger, Bernhard; Jaffray, David A

    2018-06-01

    The delivery accuracy of highly conformal dose distributions generated using intensity modulation and collimator, gantry, and couch degrees of freedom is directly affected by the quality of the alignment between the radiation beam and the mechanical axes of a linear accelerator. For this purpose, quality control (QC) guidelines recommend a tolerance of ±1 mm for the coincidence of the radiation and mechanical isocenters. Traditional QC methods for assessment of radiation and mechanical axes alignment (based on pointer alignment) are time consuming and complex tasks that provide limited accuracy. In this work, an automated test suite based on an analytical model of the linear accelerator motions was developed to streamline the QC of radiation and mechanical axes alignment. The proposed method used the automated analysis of megavoltage images of two simple task-specific phantoms acquired at different linear accelerator settings to determine the coincidence of the radiation and mechanical isocenters. The sensitivity and accuracy of the test suite were validated by introducing actual misalignments on a linear accelerator between the radiation axis and the mechanical axes using both beam steering and mechanical adjustments of the gantry and couch. The validation demonstrated that the new QC method can detect sub-millimeter misalignment between the radiation axis and the three mechanical axes of rotation. A displacement of the radiation source of 0.2 mm using beam steering parameters was easily detectable with the proposed collimator rotation axis test. Mechanical misalignments of the gantry and couch rotation axes of the same magnitude (0.2 mm) were also detectable using the new gantry and couch rotation axis tests. For the couch rotation axis, the phantom and test design allow detection of both translational and tilt misalignments with the radiation beam axis. For the collimator rotation axis, the test can isolate the misalignment between the beam radiation axis

  9. Direct measurement of the image displacement instability in a linear induction accelerator

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

    Burris-Mog, T. J.; Ekdahl, C. A.; Moir, D. C.

    The image displacement instability (IDI) has been measured on the 20 MeV Axis I of the dual axis radiographic hydrodynamic test facility and compared to theory. A 0.23 kA electron beam was accelerated across 64 gaps in a low solenoid focusing field, and the position of the beam centroid was measured to 34.3 meters downstream from the cathode. One beam dynamics code was used to model the IDI from first principles, while another code characterized the effects of the resistive wall instability and the beam break-up (BBU) instability. Although the BBU instability was not found to influence the IDI, itmore » appears that the IDI influences the BBU. Because the BBU theory does not fully account for the dependence on beam position for coupling to cavity transverse magnetic modes, the effect of the IDI is missing from the BBU theory. Finally, this becomes of particular concern to users of linear induction accelerators operating in or near low magnetic guide fields tunes.« less

  10. Direct measurement of the image displacement instability in a linear induction accelerator

    DOE PAGES

    Burris-Mog, T. J.; Ekdahl, C. A.; Moir, D. C.

    2017-06-19

    The image displacement instability (IDI) has been measured on the 20 MeV Axis I of the dual axis radiographic hydrodynamic test facility and compared to theory. A 0.23 kA electron beam was accelerated across 64 gaps in a low solenoid focusing field, and the position of the beam centroid was measured to 34.3 meters downstream from the cathode. One beam dynamics code was used to model the IDI from first principles, while another code characterized the effects of the resistive wall instability and the beam break-up (BBU) instability. Although the BBU instability was not found to influence the IDI, itmore » appears that the IDI influences the BBU. Because the BBU theory does not fully account for the dependence on beam position for coupling to cavity transverse magnetic modes, the effect of the IDI is missing from the BBU theory. Finally, this becomes of particular concern to users of linear induction accelerators operating in or near low magnetic guide fields tunes.« less

  11. A surrogate accelerated multicanonical Monte Carlo method for uncertainty quantification

    NASA Astrophysics Data System (ADS)

    Wu, Keyi; Li, Jinglai

    2016-09-01

    In this work we consider a class of uncertainty quantification problems where the system performance or reliability is characterized by a scalar parameter y. The performance parameter y is random due to the presence of various sources of uncertainty in the system, and our goal is to estimate the probability density function (PDF) of y. We propose to use the multicanonical Monte Carlo (MMC) method, a special type of adaptive importance sampling algorithms, to compute the PDF of interest. Moreover, we develop an adaptive algorithm to construct local Gaussian process surrogates to further accelerate the MMC iterations. With numerical examples we demonstrate that the proposed method can achieve several orders of magnitudes of speedup over the standard Monte Carlo methods.

  12. Perinatally acquired HIV infection accelerates epigenetic aging in South African adolescents.

    PubMed

    Horvath, Steve; Phillips, Nicole; Heany, Sarah J; Kobor, Michael S; Lin, David Ts; Myer, Landon; Zar, Heather J; Stein, Dan J; Levine, Andrew J; Hoare, Jacqueline

    2018-05-08

    Recent studies demonstrate that infection with the Human Immunodeficiency Virus-1 (HIV) is associated with accelerated aging effects in adults according to a highly accurate epigenetic biomarker of aging known as epigenetic clock. However, it not yet known whether epigenetic age acceleration occurs as early as adolescence in perinatally HIV-infected (PHIV+) youth. Observational study of PHIV and HIV-uninfected adolescents enrolled in the Cape Town Adolescent Antiretroviral Cohort (CTAAC) Study. The Illumina EPIC array was used to generate blood DNA methylation data from 204 PHIV and 44 age-matched, uninfected (HIV-) adolescents aged 9 to 12 years old. The epigenetic clock software and method was used to estimate two measures of epigenetic age acceleration. Each participant completed a comprehensive neuropsychological test battery upon enrolment to CTAAC. HIV is associated with biologically older blood in PHIV+ adolescents according to both measures of epigenetic age acceleration. One of the measures, extrinsic epigenetic age acceleration, is negatively correlated with measures of cognitive functioning (executive functioning, working memory, processing speed). Overall, our results indicate that epigenetic age acceleration in blood can be observed in PHIV+ adolescents and that these epigenetic changes accompany poorer cognitive functioning.

  13. World pendulum—a distributed remotely controlled laboratory (RCL) to measure the Earth's gravitational acceleration depending on geographical latitude

    NASA Astrophysics Data System (ADS)

    Gröber, S.; Vetter, M.; Eckert, B.; Jodl, H.-J.

    2007-05-01

    We suggest that different string pendulums are positioned at different locations on Earth and measure at each place the gravitational acceleration (accuracy Δg ~ 0.01 m s-2). Each pendulum can be remotely controlled via the internet by a computer located somewhere on Earth. The theoretical part describes the physical origin of this phenomenon g(phiv), that the Earth's effective gravitational acceleration g depends on the angle of latitude phiv. Then, we present all necessary formula to deduce g(phiv) from oscillations of a string pendulum. The technical part explains tips and tricks to realize such an apparatus to measure all necessary values with sufficient accuracy. In addition, we justify the precise dimensions of a physical pendulum such that the formula for a mathematical pendulum is applicable to determine g(phiv) without introducing errors. To conclude, we describe the internet version—the string pendulum as a remotely controlled laboratory. The teaching relevance and educational value will be discussed in detail at the end of this paper including global experimenting, using the internet and communication techniques in teaching and new ways of teaching and learning methods.

  14. Efficient Homodifunctional Bimolecular Ring-Closure Method for Cyclic Polymers by Combining RAFT and Self-Accelerating Click Reaction.

    PubMed

    Qu, Lin; Sun, Peng; Wu, Ying; Zhang, Ke; Liu, Zhengping

    2017-08-01

    An efficient metal-free homodifunctional bimolecular ring-closure method is developed for the formation of cyclic polymers by combining reversible addition-fragmentation chain transfer (RAFT) polymerization and self-accelerating click reaction. In this approach, α,ω-homodifunctional linear polymers with azide terminals are prepared by RAFT polymerization and postmodification of polymer chain end groups. By virtue of sym-dibenzo-1,5-cyclooctadiene-3,7-diyne (DBA) as small linkers, well-defined cyclic polymers are then prepared using the self-accelerating double strain-promoted azide-alkyne click (DSPAAC) reaction to ring-close the azide end-functionalized homodifunctional linear polymer precursors. Due to the self-accelerating property of DSPAAC ring-closing reaction, this novel method eliminates the requirement of equimolar amounts of telechelic polymers and small linkers in traditional bimolecular ring-closure methods. It facilitates this method to efficiently and conveniently produce varied pure cyclic polymers by employing an excess molar amount of DBA small linkers. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. A sensor fusion method for tracking vertical velocity and height based on inertial and barometric altimeter measurements.

    PubMed

    Sabatini, Angelo Maria; Genovese, Vincenzo

    2014-07-24

    A sensor fusion method was developed for vertical channel stabilization by fusing inertial measurements from an Inertial Measurement Unit (IMU) and pressure altitude measurements from a barometric altimeter integrated in the same device (baro-IMU). An Extended Kalman Filter (EKF) estimated the quaternion from the sensor frame to the navigation frame; the sensed specific force was rotated into the navigation frame and compensated for gravity, yielding the vertical linear acceleration; finally, a complementary filter driven by the vertical linear acceleration and the measured pressure altitude produced estimates of height and vertical velocity. A method was also developed to condition the measured pressure altitude using a whitening filter, which helped to remove the short-term correlation due to environment-dependent pressure changes from raw pressure altitude. The sensor fusion method was implemented to work on-line using data from a wireless baro-IMU and tested for the capability of tracking low-frequency small-amplitude vertical human-like motions that can be critical for stand-alone inertial sensor measurements. Validation tests were performed in different experimental conditions, namely no motion, free-fall motion, forced circular motion and squatting. Accurate on-line tracking of height and vertical velocity was achieved, giving confidence to the use of the sensor fusion method for tracking typical vertical human motions: velocity Root Mean Square Error (RMSE) was in the range 0.04-0.24 m/s; height RMSE was in the range 5-68 cm, with statistically significant performance gains when the whitening filter was used by the sensor fusion method to track relatively high-frequency vertical motions.

  16. ACCELERATION AND THE GIFTED.

    ERIC Educational Resources Information Center

    GIBSON, ARTHUR R.; STEPHANS, THOMAS M.

    ACCELERATION OF PUPILS AND SUBJECTS IS CONSIDERED A MEANS OF EDUCATING THE ACADEMICALLY GIFTED STUDENT. FIVE INTRODUCTORY ARTICLES PROVIDE A FRAMEWORK FOR THINKING ABOUT ACCELERATION. FIVE PROJECT REPORTS OF ACCELERATED PROGRAMS IN OHIO ARE INCLUDED. ACCELERATION IS NOW BEING REGARDED MORE FAVORABLY THAN FORMERLY, BECAUSE METHODS HAVE BEEN…

  17. Engineering survey planning for the alignment of a particle accelerator: part II. Design of a reference network and measurement strategy

    NASA Astrophysics Data System (ADS)

    Junqueira Leão, Rodrigo; Raffaelo Baldo, Crhistian; Collucci da Costa Reis, Maria Luisa; Alves Trabanco, Jorge Luiz

    2018-03-01

    The building blocks of particle accelerators are magnets responsible for keeping beams of charged particles at a desired trajectory. Magnets are commonly grouped in support structures named girders, which are mounted on vertical and horizontal stages. The performance of this type of machine is highly dependent on the relative alignment between its main components. The length of particle accelerators ranges from small machines to large-scale national or international facilities, with typical lengths of hundreds of meters to a few kilometers. This relatively large volume together with micrometric positioning tolerances make the alignment activity a classical large-scale dimensional metrology problem. The alignment concept relies on networks of fixed monuments installed on the building structure to which all accelerator components are referred. In this work, the Sirius accelerator is taken as a case study, and an alignment network is optimized via computational methods in terms of geometry, densification, and surveying procedure. Laser trackers are employed to guide the installation and measure the girders’ positions, using the optimized network as a reference and applying the metric developed in part I of this paper. Simulations demonstrate the feasibility of aligning the 220 girders of the Sirius synchrotron to better than 0.080 mm, at a coverage probability of 95%.

  18. Hoof accelerations and ground reaction forces of Thoroughbred racehorses measured on dirt, synthetic, and turf track surfaces.

    PubMed

    Setterbo, Jacob J; Garcia, Tanya C; Campbell, Ian P; Reese, Jennifer L; Morgan, Jessica M; Kim, Sun Y; Hubbard, Mont; Stover, Susan M

    2009-10-01

    To compare hoof acceleration and ground reaction force (GRF) data among dirt, synthetic, and turf surfaces in Thoroughbred racehorses. 3 healthy Thoroughbred racehorses. Forelimb hoof accelerations and GRFs were measured with an accelerometer and a dynamometric horseshoe during trot and canter on dirt, synthetic, and turf track surfaces at a racecourse. Maxima, minima, temporal components, and a measure of vibration were extracted from the data. Acceleration and GRF variables were compared statistically among surfaces. The synthetic surface often had the lowest peak accelerations, mean vibration, and peak GRFs. Peak acceleration during hoof landing was significantly smaller for the synthetic surface (mean + or - SE, 28.5g + or - 2.9g) than for the turf surface (42.9g + or - 3.8g). Hoof vibrations during hoof landing for the synthetic surface were < 70% of those for the dirt and turf surfaces. Peak GRF for the synthetic surface (11.5 + or - 0.4 N/kg) was 83% and 71% of those for the dirt (13.8 + or - 0.3 N/kg) and turf surfaces (16.1 + or - 0.7 N/kg), respectively. The relatively low hoof accelerations, vibrations, and peak GRFs associated with the synthetic surface evaluated in the present study indicated that synthetic surfaces have potential for injury reduction in Thoroughbred racehorses. However, because of the unique material properties and different nature of individual dirt, synthetic, and turf racetrack surfaces, extending the results of this study to encompass all track surfaces should be done with caution.

  19. Comparison of Nasal Acceleration and Nasalance across Vowels

    ERIC Educational Resources Information Center

    Thorp, Elias B.; Virnik, Boris T.; Stepp, Cara E.

    2013-01-01

    Purpose: The purpose of this study was to determine the performance of normalized nasal acceleration (NNA) relative to nasalance as estimates of nasalized versus nonnasalized vowel and sentence productions. Method: Participants were 18 healthy speakers of American English. NNA was measured using a custom sensor, and nasalance was measured using…

  20. Effect of processing method on accelerated weathering of wood-flour/HDPE composites

    Treesearch

    Nicole M. Stark; Laurent M. Matuana; Craig M. Clemons

    2003-01-01

    Wood-plastic lumber is promoted as a low maintenance high-durability product. When exposed to accelerated weathering, however, wood-plastic composites may experience a color change and/or loss in mechanical properties. Different methods of manufacturing wood-plastic composites lead to different surface characteristics, which can influence weathering, In this study, 50...

  1. Vibration environment - Acceleration mapping strategy and microgravity requirements for Spacelab and Space Station

    NASA Technical Reports Server (NTRS)

    Martin, Gary L.; Baugher, Charles R.; Delombard, Richard

    1990-01-01

    In order to define the acceleration requirements for future Shuttle and Space Station Freedom payloads, methods and hardware characterizing accelerations on microgravity experiment carriers are discussed. The different aspects of the acceleration environment and the acceptable disturbance levels are identified. The space acceleration measurement system features an adjustable bandwidth, wide dynamic range, data storage, and ability to be easily reconfigured and is expected to fly on the Spacelab Life Sciences-1. The acceleration characterization and analysis project describes the Shuttle acceleration environment and disturbance mechanisms, and facilitates the implementation of the microgravity research program.

  2. Coupling and decoupling of the accelerating units for pulsed synchronous linear accelerator

    NASA Astrophysics Data System (ADS)

    Shen, Yi; Liu, Yi; Ye, Mao; Zhang, Huang; Wang, Wei; Xia, Liansheng; Wang, Zhiwen; Yang, Chao; Shi, Jinshui; Zhang, Linwen; Deng, Jianjun

    2017-12-01

    A pulsed synchronous linear accelerator (PSLA), based on the solid-state pulse forming line, photoconductive semiconductor switch, and high gradient insulator technologies, is a novel linear accelerator. During the prototype PSLA commissioning, the energy gain of proton beams was found to be much lower than expected. In this paper, the degradation of the energy gain is explained by the circuit and cavity coupling effect of the accelerating units. The coupling effects of accelerating units are studied, and the circuit topologies of these two kinds of coupling effects are presented. Two methods utilizing inductance and membrane isolations, respectively, are proposed to reduce the circuit coupling effects. The effectiveness of the membrane isolation method is also supported by simulations. The decoupling efficiency of the metal drift tube is also researched. We carried out the experiments on circuit decoupling of the multiple accelerating cavity. The result shows that both circuit decoupling methods could increase the normalized voltage.

  3. Magnetic field error measurement of the CEBAF (NIST) wiggler using the pulsed wire method

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

    Wallace, Stephen; Colson, William; Neil, George

    1993-07-01

    The National Institute for Science and Technology (NIST) wiggler has been loaded to the Continuous Electron Beam Accelerator Facility (CEBAF). The pulsed wire method [R.W. Warren, Nucl. Instr. and Meth. A272 (1988) 267] has been used to measure the field errors of the entrance wiggler half, and the net path deflection was calculated to be Δx ≈ 5.2 m.

  4. Stochastic shock response spectrum decomposition method based on probabilistic definitions of temporal peak acceleration, spectral energy, and phase lag distributions of mechanical impact pyrotechnic shock test data

    NASA Astrophysics Data System (ADS)

    Hwang, James Ho-Jin; Duran, Adam

    2016-08-01

    Most of the times pyrotechnic shock design and test requirements for space systems are provided in Shock Response Spectrum (SRS) without the input time history. Since the SRS does not describe the input or the environment, a decomposition method is used to obtain the source time history. The main objective of this paper is to develop a decomposition method producing input time histories that can satisfy the SRS requirement based on the pyrotechnic shock test data measured from a mechanical impact test apparatus. At the heart of this decomposition method is the statistical representation of the pyrotechnic shock test data measured from the MIT Lincoln Laboratory (LL) designed Universal Pyrotechnic Shock Simulator (UPSS). Each pyrotechnic shock test data measured at the interface of a test unit has been analyzed to produce the temporal peak acceleration, Root Mean Square (RMS) acceleration, and the phase lag at each band center frequency. Maximum SRS of each filtered time history has been calculated to produce a relationship between the input and the response. Two new definitions are proposed as a result. The Peak Ratio (PR) is defined as the ratio between the maximum SRS and the temporal peak acceleration at each band center frequency. The ratio between the maximum SRS and the RMS acceleration is defined as the Energy Ratio (ER) at each band center frequency. Phase lag is estimated based on the time delay between the temporal peak acceleration at each band center frequency and the peak acceleration at the lowest band center frequency. This stochastic process has been applied to more than one hundred pyrotechnic shock test data to produce probabilistic definitions of the PR, ER, and the phase lag. The SRS is decomposed at each band center frequency using damped sinusoids with the PR and the decays obtained by matching the ER of the damped sinusoids to the ER of the test data. The final step in this stochastic SRS decomposition process is the Monte Carlo (MC

  5. Investigation of the characteristics of the Venus stratosphere from acceleration measurements during the braking of the Venera-13 and Venera-14 probes

    NASA Astrophysics Data System (ADS)

    Avduevskii, V. S.; Godnev, A. G.; Semenchenko, V. V.; Uspenskii, G. R.; Cheremukhina, Z. P.

    1983-03-01

    Acceleration measurements in the preparachute segment of descent during the aerodynamics braking of Venera-13 and Venera-14 were made in order to study the characteristics of the Venus stratosphere and mesosphere. Results of axial-acceleration measurements are presented, and attention is given to atmospheric density and pressure profiles obtained from the accelerometer data and vertical temperature profiles acquired from Venera and Pioneer-Venus acceleration data.

  6. Laser driven ion accelerator

    DOEpatents

    Tajima, Toshiki

    2006-04-18

    A system and method of accelerating ions in an accelerator to optimize the energy produced by a light source. Several parameters may be controlled in constructing a target used in the accelerator system to adjust performance of the accelerator system. These parameters include the material, thickness, geometry and surface of the target.

  7. Apparatus and method for the acceleration of projectiles to hypervelocities

    DOEpatents

    Hertzberg, Abraham; Bruckner, Adam P.; Bogdanoff, David W.

    1990-01-01

    A projectile is initially accelerated to a supersonic velocity and then injected into a launch tube filled with a gaseous propellant. The projectile outer surface and launch tube inner surface form a ramjet having a diffuser, a combustion chamber and a nozzle. A catalytic coated flame holder projecting from the projectile ignites the gaseous propellant in the combustion chamber thereby accelerating the projectile in a subsonic combustion mode zone. The projectile then enters an overdriven detonation wave launch tube zone wherein further projectile acceleration is achieved by a formed, controlled overdriven detonation wave capable of igniting the gaseous propellant in the combustion chamber. Ultrahigh velocity projectile accelerations are achieved in a launch tube layered detonation zone having an inner sleeve filled with hydrogen gas. An explosive, which is disposed in the annular zone between the inner sleeve and the launch tube, explodes responsive to an impinging shock wave emanating from the diffuser of the accelerating projectile thereby forcing the inner sleeve inward and imparting an acceleration to the projectile. For applications wherein solid or liquid high explosives are employed, the explosion thereof forces the inner sleeve inward, forming a throat behind the projectile. This throat chokes flow behind, thereby imparting an acceleration to the projectile.

  8. Electron density measurement in gas discharge plasmas by optical and acoustic methods

    NASA Astrophysics Data System (ADS)

    Biagioni, A.; Anania, M. P.; Bellaveglia, M.; Chiadroni, E.; Cianchi, A.; Di Giovenale, D.; Di Pirro, G.; Ferrario, M.; Filippi, F.; Mostacci, A.; Pompili, R.; Shpakov, V.; Vaccarezza, C.; Villa, F.; Zigler, A.

    2016-08-01

    Plasma density represents a very important parameter for both laser wakefield and plasma wakefield acceleration, which use a gas-filled capillary plasma source. Several techniques can be used to measure the plasma density within a capillary discharge, which are mainly based on optical diagnostic methods, as for example the well-known spectroscopic method using the Stark broadening effect. In this work, we introduce a preliminary study on an alternative way to detect the plasma density, based on the shock waves produced by gas discharge in a capillary. Firstly, the measurements of the acoustic spectral content relative to the laser-induced plasmas by a solid target allowed us to understand the main properties of the acoustic waves produced during this kind of plasma generation; afterwards, we have extended such acoustic technique to the capillary plasma source in order to calibrate it by comparison with the stark broadening method.

  9. SCAT3 changes from baseline and associations with X2 Patch measured head acceleration in amateur Australian football players.

    PubMed

    Willmott, Catherine; McIntosh, Andrew S; Howard, Teresa; Mitra, Biswadev; Dimech-Betancourt, Bleydy; Donovan, Jarrod; Rosenfeld, Jeffrey V

    2018-05-01

    To investigate changes from baseline on SCAT3 as a result of football game exposure, and association with X2 Patch measured head acceleration events in amateur Australian footballers. Prospective cohort. Peak linear acceleration (PLA) of the head (>10 g) was measured by wearable head acceleration sensor X2 Biosystems X-Patch in male (n=34) and female (n=19) Australian footballers. SCAT3 was administered at baseline (B) and post-game (PG). 1394 head acceleration events (HEA) >10 g were measured. Mean and median HEA PLA were recorded as 15.2 g (SD=9.2, range=10.0-115.8) and 12.4 g (IQR=11.0-15.6) respectively. No significant difference in median HEA PLA (g) was detected across gender (p=0.55), however, more HEAs were recorded in males (p=0.03). A greater number (p=0.004) and severity (p<0.001) of symptoms were reported PG than at B. No significant association between number of HEA or median PLA, and SCAT3 change scores (p>0.05 for all), was identified for either gender. Increase in symptom severity post game was not associated with X2 measured HEA. Males sustained more HEA, however HEA PLA magnitude did not differ across gender. Further work on the validation of head acceleration sensors is required and their role in sports concussion research and medical management. Copyright © 2017 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

  10. Player Monitoring in Indoor Team Sports: Concurrent Validity of Inertial Measurement Units to Quantify Average and Peak Acceleration Values

    PubMed Central

    Roell, Mareike; Roecker, Kai; Gehring, Dominic; Mahler, Hubert; Gollhofer, Albert

    2018-01-01

    The increasing interest in assessing physical demands in team sports has led to the development of multiple sports related monitoring systems. Due to technical limitations, these systems primarily could be applied to outdoor sports, whereas an equivalent indoor locomotion analysis is not established yet. Technological development of inertial measurement units (IMU) broadens the possibilities for player monitoring and enables the quantification of locomotor movements in indoor environments. The aim of the current study was to validate an IMU measuring by determining average and peak human acceleration under indoor conditions in team sport specific movements. Data of a single wearable tracking device including an IMU (Optimeye S5, Catapult Sports, Melbourne, Australia) were compared to the results of a 3D motion analysis (MA) system (Vicon Motion Systems, Oxford, UK) during selected standardized movement simulations in an indoor laboratory (n = 56). A low-pass filtering method for gravity correction (LF) and two sensor fusion algorithms for orientation estimation [Complementary Filter (CF), Kalman-Filter (KF)] were implemented and compared with MA system data. Significant differences (p < 0.05) were found between LF and MA data but not between sensor fusion algorithms and MA. Higher precision and lower relative errors were found for CF (RMSE = 0.05; CV = 2.6%) and KF (RMSE = 0.15; CV = 3.8%) both compared to the LF method (RMSE = 1.14; CV = 47.6%) regarding the magnitude of the resulting vector and strongly emphasize the implementation of orientation estimation to accurately describe human acceleration. Comparing both sensor fusion algorithms, CF revealed slightly lower errors than KF and additionally provided valuable information about positive and negative acceleration values in all three movement planes with moderate to good validity (CV = 3.9 – 17.8%). Compared to x- and y-axis superior results were found for the z-axis. These findings demonstrate that IMU

  11. Quartz crystal resonator g sensitivity measurement methods and recent results

    NASA Astrophysics Data System (ADS)

    Driscoll, M. M.

    1990-09-01

    A technique for accurate measurements of quartz crystal resonator vibration sensitivity is described. The technique utilizes a crystal oscillator circuit in which a prescribed length of coaxial cable is used to connect the resonator to the oscillator sustaining stage. A method is provided for determination and removal of measurement errors normally introduced as a result of cable vibration. In addition to oscillator-type measurements, it is also possible to perform similar vibration sensitivity measurements using a synthesized signal generator with the resonator installed in a passive phase bridge. Test results are reported for 40 and 50 MHz, fifth overtone AT-cut, and third overtone SC-cut crystals. Acceleration sensitivity (gamma vector) values for the SC-cut resonators were typically four times smaller (5 x 10 to the -10th/g) than for the AT-cut units. However, smaller unit-to-unit gamma vector magnitude variation was exhibited by the AT-cut resonators.

  12. Development of a neutron spectrometer using multi-wire spark chambers for the measurement of the spectra of stray neutrons in the vicinity of high energy accelerators

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

    Lim, Chun Bin

    A method of neutron spectrometry which measures the energy spectra of the stray neutrons around the high energy accelerators, roughly between 50 MeV and 300 MeV has been developed using a series of multi-wire spark chambers and polyethylene n-p converters.

  13. Motor recovery monitoring using acceleration measurements in post acute stroke patients.

    PubMed

    Gubbi, Jayavardhana; Rao, Aravinda S; Fang, Kun; Yan, Bernard; Palaniswami, Marimuthu

    2013-04-16

    Stroke is one of the major causes of morbidity and mortality. Its recovery and treatment depends on close clinical monitoring by a clinician especially during the first few hours after the onset of stroke. Patients who do not exhibit early motor recovery post thrombolysis may benefit from more aggressive treatment. A novel approach for monitoring stroke during the first few hours after the onset of stroke using a wireless accelerometer based motor activity monitoring system is developed. It monitors the motor activity by measuring the acceleration of the arms in three axes. In the presented proof of concept study, the measured acceleration data is transferred wirelessly using iMote2 platform to the base station that is equipped with an online algorithm capable of calculating an index equivalent to the National Institute of Health Stroke Score (NIHSS) motor index. The system is developed by collecting data from 15 patients. We have successfully demonstrated an end-to-end stroke monitoring system reporting an accuracy of calculating stroke index of more than 80%, highest Cohen's overall agreement of 0.91 (with excellent κ coefficient of 0.76). A wireless accelerometer based 'hot stroke' monitoring system is developed to monitor the motor recovery in acute-stroke patients. It has been shown to monitor stroke patients continuously, which has not been possible so far with high reliability.

  14. A Sensor Fusion Method for Tracking Vertical Velocity and Height Based on Inertial and Barometric Altimeter Measurements

    PubMed Central

    Sabatini, Angelo Maria; Genovese, Vincenzo

    2014-01-01

    A sensor fusion method was developed for vertical channel stabilization by fusing inertial measurements from an Inertial Measurement Unit (IMU) and pressure altitude measurements from a barometric altimeter integrated in the same device (baro-IMU). An Extended Kalman Filter (EKF) estimated the quaternion from the sensor frame to the navigation frame; the sensed specific force was rotated into the navigation frame and compensated for gravity, yielding the vertical linear acceleration; finally, a complementary filter driven by the vertical linear acceleration and the measured pressure altitude produced estimates of height and vertical velocity. A method was also developed to condition the measured pressure altitude using a whitening filter, which helped to remove the short-term correlation due to environment-dependent pressure changes from raw pressure altitude. The sensor fusion method was implemented to work on-line using data from a wireless baro-IMU and tested for the capability of tracking low-frequency small-amplitude vertical human-like motions that can be critical for stand-alone inertial sensor measurements. Validation tests were performed in different experimental conditions, namely no motion, free-fall motion, forced circular motion and squatting. Accurate on-line tracking of height and vertical velocity was achieved, giving confidence to the use of the sensor fusion method for tracking typical vertical human motions: velocity Root Mean Square Error (RMSE) was in the range 0.04–0.24 m/s; height RMSE was in the range 5–68 cm, with statistically significant performance gains when the whitening filter was used by the sensor fusion method to track relatively high-frequency vertical motions. PMID:25061835

  15. Induction linear accelerators

    NASA Astrophysics Data System (ADS)

    Birx, Daniel

    1992-03-01

    Among the family of particle accelerators, the Induction Linear Accelerator is the best suited for the acceleration of high current electron beams. Because the electromagnetic radiation used to accelerate the electron beam is not stored in the cavities but is supplied by transmission lines during the beam pulse it is possible to utilize very low Q (typically<10) structures and very large beam pipes. This combination increases the beam breakup limited maximum currents to of order kiloamperes. The micropulse lengths of these machines are measured in 10's of nanoseconds and duty factors as high as 10-4 have been achieved. Until recently the major problem with these machines has been associated with the pulse power drive. Beam currents of kiloamperes and accelerating potentials of megavolts require peak power drives of gigawatts since no energy is stored in the structure. The marriage of liner accelerator technology and nonlinear magnetic compressors has produced some unique capabilities. It now appears possible to produce electron beams with average currents measured in amperes, peak currents in kiloamperes and gradients exceeding 1 MeV/meter, with power efficiencies approaching 50%. The nonlinear magnetic compression technology has replaced the spark gap drivers used on earlier accelerators with state-of-the-art all-solid-state SCR commutated compression chains. The reliability of these machines is now approaching 1010 shot MTBF. In the following paper we will briefly review the historical development of induction linear accelerators and then discuss the design considerations.

  16. Accelerator mass spectrometry of small biological samples.

    PubMed

    Salehpour, Mehran; Forsgard, Niklas; Possnert, Göran

    2008-12-01

    Accelerator mass spectrometry (AMS) is an ultra-sensitive technique for isotopic ratio measurements. In the biomedical field, AMS can be used to measure femtomolar concentrations of labeled drugs in body fluids, with direct applications in early drug development such as Microdosing. Likewise, the regenerative properties of cells which are of fundamental significance in stem-cell research can be determined with an accuracy of a few years by AMS analysis of human DNA. However, AMS nominally requires about 1 mg of carbon per sample which is not always available when dealing with specific body substances such as localized, organ-specific DNA samples. Consequently, it is of analytical interest to develop methods for the routine analysis of small samples in the range of a few tens of microg. We have used a 5 MV Pelletron tandem accelerator to study small biological samples using AMS. Different methods are presented and compared. A (12)C-carrier sample preparation method is described which is potentially more sensitive and less susceptible to contamination than the standard procedures.

  17. An accelerated photo-magnetic imaging reconstruction algorithm based on an analytical forward solution and a fast Jacobian assembly method

    NASA Astrophysics Data System (ADS)

    Nouizi, F.; Erkol, H.; Luk, A.; Marks, M.; Unlu, M. B.; Gulsen, G.

    2016-10-01

    We previously introduced photo-magnetic imaging (PMI), an imaging technique that illuminates the medium under investigation with near-infrared light and measures the induced temperature increase using magnetic resonance thermometry (MRT). Using a multiphysics solver combining photon migration and heat diffusion, PMI models the spatiotemporal distribution of temperature variation and recovers high resolution optical absorption images using these temperature maps. In this paper, we present a new fast non-iterative reconstruction algorithm for PMI. This new algorithm uses analytic methods during the resolution of the forward problem and the assembly of the sensitivity matrix. We validate our new analytic-based algorithm with the first generation finite element method (FEM) based reconstruction algorithm previously developed by our team. The validation is performed using, first synthetic data and afterwards, real MRT measured temperature maps. Our new method accelerates the reconstruction process 30-fold when compared to a single iteration of the FEM-based algorithm.

  18. Results of Measurements of Accelerations of Technological Devices onboard the FotonSpacecraft

    NASA Astrophysics Data System (ADS)

    Barmin, I. V.; Volkov, M. V.; Egorov, A. V.; Reut, E. F.; Senchenkov, A. S.

    2001-07-01

    This paper generalizes the results of measuring the residual accelerations arising when investigations in space materials science are carried out onboard the unmanned Fotonspacecraft. The levels of vibroaccelerations are analyzed in the frequency band of 1 500 Hz for the technological devices UZ01, UZ04, and POLIZON, developed by the Federal Unitary State Enterprise “Barmin Design Bureau of General Machine Building” (V.P. Barmin KBOM). The levels of accelerations are estimated in the frequency band of 0 1 Hz in the zone of technological operations of these facilities. The basic sources of vibroaccelerations acting upon the frames of devices are determined in the capsule zone, where technological processes of producing new materials take place. In the frequency band of 1 500 Hz the vibroaccelerations are shown to be generated by the operation of Fotonspacecraft units and a drive of capsule translation during the technological process. On the capsule frame they reach the values of (1 3) × 10 3 g. The level of linear accelerations in the infralow-frequency band is determined by rotational motions of the Fotonspacecraft. It depends on the device location with respect to the spacecraft center of mass and does not exceed (1 7) × 10 6 gin the steady-state regime in the zone of technological activity.

  19. Space acceleration measurement system description and operations on the First Spacelab Life Sciences Mission

    NASA Technical Reports Server (NTRS)

    Delombard, Richard; Finley, Brian D.

    1991-01-01

    The Space Acceleration Measurement System (SAMS) project and flight units are briefly described. The SAMS operations during the STS-40 mission are summarized, and a preliminary look at some of the acceleration data from that mission are provided. The background and rationale for the SAMS project is described to better illustrate its goals. The functions and capabilities of each SAMS flight unit are first explained, then the STS-40 mission, the SAMS's function for that mission, and the preparation of the SAMS are described. Observations about the SAMS operations during the first SAMS mission are then discussed. Some sample data are presented illustrating several aspects of the mission's microgravity environment.

  20. METHOD OF PRODUCING AND ACCELERATING AN ION BEAM

    NASA Technical Reports Server (NTRS)

    Foster, John E. (Inventor)

    2005-01-01

    A method of producing and accelerating an ion beam comprising the steps of providing a magnetic field with a cusp that opens in an outward direction along a centerline that passes through a vertex of the cusp: providing an ionizing gas that sprays outward through at least one capillary-like orifice in a plenum that is positioned such that the orifice is on the centerline in the cusp, outward of the vortex of the cusp; providing a cathode electron source, and positioning it outward of the orifice and off of the centerline; and positively charging the plenum relative to the cathode electron source such that the plenum functions as m anode. A hot filament may be used as the cathode electron source, and permanent magnets may be used to provide the magnetic field.

  1. Acceleration and Rotation in a Pendulum Ride, Measured Using an iPhone 4

    ERIC Educational Resources Information Center

    Pendrill, Ann-Marie; Rohlen, Johan

    2011-01-01

    Many modern cell phones have built-in sensors that may be used as a resource for physics education. Amusement rides offer examples of many different types of motion, where the acceleration leads to forces experienced throughout the body. A comoving 3D-accelerometer gives an electronic measurement of the varying forces acting on the rider, but a…

  2. Means and method for the focusing and acceleration of parallel beams of charged particles

    DOEpatents

    Maschke, Alfred W.

    1983-07-05

    A novel apparatus and method for focussing beams of charged particles comprising planar arrays of electrostatic quadrupoles. The quadrupole arrays may comprise electrodes which are shared by two or more quadrupoles. Such quadrupole arrays are particularly adapted to providing strong focussing forces for high current, high brightness, beams of charged particles, said beams further comprising a plurality of parallel beams, or beamlets, each such beamlet being focussed by one quadrupole of the array. Such arrays may be incorporated in various devices wherein beams of charged particles are accelerated or transported, such as linear accelerators, klystron tubes, beam transport lines, etc.

  3. ELECTROSTATIC ACCELERATORS (in French)

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

    Gerbier, R.

    1962-04-01

    The various methods presently in use for producing the continuous high voltage necessary for the operation of electrostatic accelerators are reviewed. The methods considered are voltage multiplier units (Greinacher and Morganstern types) and electrostatic instruments (Van de Graaff and Trump machines and Felici rotnting cylinder instruments). The electrostatic accelerators used at Grenoble which give currents of several milliamperes at voltages up to 1.2 Mv are described. In this energy region electron accelerators and neutron generators offer very interesting possibilities. (auth)

  4. 3D graphics hardware accelerator programming methods for real-time visualization systems

    NASA Astrophysics Data System (ADS)

    Souetov, Andrew E.

    2001-02-01

    The paper deals with new approaches in software design for creating real-time applications that use modern graphics acceleration hardware. The growing complexity of such type of software compels programmers to use different types of CASE systems in design and development process. The subject under discussion is integration of such systems in a development process, their effective use, and the combination of these new methods with the necessity to produce optimal codes. A method of simulation integration and modeling tools in real-time software development cycle is described.

  5. 3D graphics hardware accelerator programming methods for real-time visualization systems

    NASA Astrophysics Data System (ADS)

    Souetov, Andrew E.

    2000-02-01

    The paper deals with new approaches in software design for creating real-time applications that use modern graphics acceleration hardware. The growing complexity of such type of software compels programmers to use different types of CASE systems in design and development process. The subject under discussion is integration of such systems in a development process, their effective use, and the combination of these new methods with the necessity to produce optimal codes. A method of simulation integration and modeling tools in real-time software development cycle is described.

  6. An accelerated proximal augmented Lagrangian method and its application in compressive sensing.

    PubMed

    Sun, Min; Liu, Jing

    2017-01-01

    As a first-order method, the augmented Lagrangian method (ALM) is a benchmark solver for linearly constrained convex programming, and in practice some semi-definite proximal terms are often added to its primal variable's subproblem to make it more implementable. In this paper, we propose an accelerated PALM with indefinite proximal regularization (PALM-IPR) for convex programming with linear constraints, which generalizes the proximal terms from semi-definite to indefinite. Under mild assumptions, we establish the worst-case [Formula: see text] convergence rate of PALM-IPR in a non-ergodic sense. Finally, numerical results show that our new method is feasible and efficient for solving compressive sensing.

  7. Measurement method of magnetic field for the wire suspended micro-pendulum accelerometer.

    PubMed

    Lu, Yongle; Li, Leilei; Hu, Ning; Pan, Yingjun; Ren, Chunhua

    2015-04-13

    Force producer is one of the core components of a Wire Suspended Micro-Pendulum Accelerometer; and the stability of permanent magnet in the force producer determines the consistency of the acceleration sensor's scale factor. For an assembled accelerometer; direct measurement of magnetic field strength is not a feasible option; as the magnetometer probe cannot be laid inside the micro-space of the sensor. This paper proposed an indirect measurement method of the remnant magnetization of Micro-Pendulum Accelerometer. The measurement is based on the working principle of the accelerometer; using the current output at several different scenarios to resolve the remnant magnetization of the permanent magnet. Iterative Least Squares algorithm was used for the adjustment of the data due to nonlinearity of this problem. The calculated remnant magnetization was 1.035 T. Compared to the true value; the error was less than 0.001 T. The proposed method provides an effective theoretical guidance for measuring the magnetic field of the Wire Suspended Micro-Pendulum Accelerometer; correcting the scale factor and temperature influence coefficients; etc.

  8. A GPU-accelerated semi-implicit fractional-step method for numerical solutions of incompressible Navier-Stokes equations

    NASA Astrophysics Data System (ADS)

    Ha, Sanghyun; Park, Junshin; You, Donghyun

    2018-01-01

    Utility of the computational power of Graphics Processing Units (GPUs) is elaborated for solutions of incompressible Navier-Stokes equations which are integrated using a semi-implicit fractional-step method. The Alternating Direction Implicit (ADI) and the Fourier-transform-based direct solution methods used in the semi-implicit fractional-step method take advantage of multiple tridiagonal matrices whose inversion is known as the major bottleneck for acceleration on a typical multi-core machine. A novel implementation of the semi-implicit fractional-step method designed for GPU acceleration of the incompressible Navier-Stokes equations is presented. Aspects of the programing model of Compute Unified Device Architecture (CUDA), which are critical to the bandwidth-bound nature of the present method are discussed in detail. A data layout for efficient use of CUDA libraries is proposed for acceleration of tridiagonal matrix inversion and fast Fourier transform. OpenMP is employed for concurrent collection of turbulence statistics on a CPU while the Navier-Stokes equations are computed on a GPU. Performance of the present method using CUDA is assessed by comparing the speed of solving three tridiagonal matrices using ADI with the speed of solving one heptadiagonal matrix using a conjugate gradient method. An overall speedup of 20 times is achieved using a Tesla K40 GPU in comparison with a single-core Xeon E5-2660 v3 CPU in simulations of turbulent boundary-layer flow over a flat plate conducted on over 134 million grids. Enhanced performance of 48 times speedup is reached for the same problem using a Tesla P100 GPU.

  9. Measurements of Acceleration Due to Gravity.

    ERIC Educational Resources Information Center

    Crummett, Bill

    1990-01-01

    The principle means by which g has been measured are summarized. Discussed are "Kater's Reversible Pendulum," falling rules, and interferometry methods. Types of corrections and various sources of uncertainty are considered. (CW)

  10. Fast hydrological model calibration based on the heterogeneous parallel computing accelerated shuffled complex evolution method

    NASA Astrophysics Data System (ADS)

    Kan, Guangyuan; He, Xiaoyan; Ding, Liuqian; Li, Jiren; Hong, Yang; Zuo, Depeng; Ren, Minglei; Lei, Tianjie; Liang, Ke

    2018-01-01

    Hydrological model calibration has been a hot issue for decades. The shuffled complex evolution method developed at the University of Arizona (SCE-UA) has been proved to be an effective and robust optimization approach. However, its computational efficiency deteriorates significantly when the amount of hydrometeorological data increases. In recent years, the rise of heterogeneous parallel computing has brought hope for the acceleration of hydrological model calibration. This study proposed a parallel SCE-UA method and applied it to the calibration of a watershed rainfall-runoff model, the Xinanjiang model. The parallel method was implemented on heterogeneous computing systems using OpenMP and CUDA. Performance testing and sensitivity analysis were carried out to verify its correctness and efficiency. Comparison results indicated that heterogeneous parallel computing-accelerated SCE-UA converged much more quickly than the original serial version and possessed satisfactory accuracy and stability for the task of fast hydrological model calibration.

  11. Summary Report of Mission Acceleration Measurements for STS-79. Launched 16 Sep. 1996

    NASA Technical Reports Server (NTRS)

    Rogers, Melissa J. B.; Moskowitz, Milton E.; Hrovat, Kenneth; Reckart, Timothy A.

    1997-01-01

    The Space Acceleration Measurement System (SAMS) collected acceleration data in support of the Mechanics of Granular Materials experiment during the STS-79 Mir docking mission, September 1996. STS-79 was the first opportunity to record SAMS data on an Orbiter while it was docked to Mir. Crew exercise activities in the Atlantis middeck and the Mir base module are apparent in the data. The acceleration signals related to the Enhanced Orbiter Refrigerator Freezer had different characteristics when comparing the data recorded on Atlantis on STS-79 with the data recorded on Mir during STS-74. This is probably due, at least in part, to different transmission paths and SAMS sensor head mounting mechanisms. Data collected on Atlantis during the STS-79 docking indicate that accelerations due to vehicle and solar array structural modes from Mir transfer to Atlantis and that the structural modes of the Atlantis-Mir complex are different from those of either vehicle independently. A 0.18 Hz component of the SAMS data, present while the two vehicles were docked, was probably caused by the Mir solar arrays. Compared to Atlantis structural modes of about 3.9 and 4.9 Hz, the Atlantis-Mir complex has structural components of about 4.5 and 5.1 Hz. After docking, apparent structural modes appeared in the data at about 0.8 and 1.8 Hz. The appearance, disappearance, and change in the structural modes during the docking and undocking phases of the joint Atlantis-Mir operations indicates that the structural modes of the two spacecraft have an effect on the microgravity environment of each other. The transfer of structural and equipment related accelerations between vehicles is something that should be considered in the International Space Station era.

  12. Application of probabilistic modelling for the uncertainty evaluation of alignment measurements of large accelerator magnets assemblies

    NASA Astrophysics Data System (ADS)

    Doytchinov, I.; Tonnellier, X.; Shore, P.; Nicquevert, B.; Modena, M.; Mainaud Durand, H.

    2018-05-01

    Micrometric assembly and alignment requirements for future particle accelerators, and especially large assemblies, create the need for accurate uncertainty budgeting of alignment measurements. Measurements and uncertainties have to be accurately stated and traceable, to international standards, for metre-long sized assemblies, in the range of tens of µm. Indeed, these hundreds of assemblies will be produced and measured by several suppliers around the world, and will have to be integrated into a single machine. As part of the PACMAN project at CERN, we proposed and studied a practical application of probabilistic modelling of task-specific alignment uncertainty by applying a simulation by constraints calibration method. Using this method, we calibrated our measurement model using available data from ISO standardised tests (10360 series) for the metrology equipment. We combined this model with reference measurements and analysis of the measured data to quantify the actual specific uncertainty of each alignment measurement procedure. Our methodology was successfully validated against a calibrated and traceable 3D artefact as part of an international inter-laboratory study. The validated models were used to study the expected alignment uncertainty and important sensitivity factors in measuring the shortest and longest of the compact linear collider study assemblies, 0.54 m and 2.1 m respectively. In both cases, the laboratory alignment uncertainty was within the targeted uncertainty budget of 12 µm (68% confidence level). It was found that the remaining uncertainty budget for any additional alignment error compensations, such as the thermal drift error due to variation in machine operation heat load conditions, must be within 8.9 µm and 9.8 µm (68% confidence level) respectively.

  13. HEAVY ION LINEAR ACCELERATOR

    DOEpatents

    Van Atta, C.M.; Beringer, R.; Smith, L.

    1959-01-01

    A linear accelerator of heavy ions is described. The basic contributions of the invention consist of a method and apparatus for obtaining high energy particles of an element with an increased charge-to-mass ratio. The method comprises the steps of ionizing the atoms of an element, accelerating the resultant ions to an energy substantially equal to one Mev per nucleon, stripping orbital electrons from the accelerated ions by passing the ions through a curtain of elemental vapor disposed transversely of the path of the ions to provide a second charge-to-mass ratio, and finally accelerating the resultant stripped ions to a final energy of at least ten Mev per nucleon.

  14. SU-F-P-36: Automation of Linear Accelerator Star Shot Measurement with Advanced XML Scripting and Electronic Portal Imaging Device

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

    Nguyen, N; Knutson, N; Schmidt, M

    Purpose: To verify a method used to automatically acquire jaw, MLC, collimator and couch star shots for a Varian TrueBeam linear accelerator utilizing Developer Mode and an Electronic Portal Imaging Device (EPID). Methods: An XML script was written to automate motion of the jaws, MLC, collimator and couch in TrueBeam Developer Mode (TBDM) to acquire star shot measurements. The XML script also dictates MV imaging parameters to facilitate automatic acquisition and recording of integrated EPID images. Since couch star shot measurements cannot be acquired using a combination of EPID and jaw/MLC collimation alone due to a fixed imager geometry, amore » method utilizing a 5mm wide steel ruler placed on the table and centered within a 15×15cm2 open field to produce a surrogate of the narrow field aperture was investigated. Four individual star shot measurements (X jaw, Y jaw, MLC and couch) were obtained using our proposed as well as traditional film-based method. Integrated EPID images and scanned measurement films were analyzed and compared. Results: Star shot (X jaw, Y jaw, MLC and couch) measurements were obtained in a single 5 minute delivery using the TBDM XML script method compared to 60 minutes for equivalent traditional film measurements. Analysis of the images and films demonstrated comparable isocentricity results, agreeing within 0.3mm of each other. Conclusion: The presented automatic approach of acquiring star shot measurements using TBDM and EPID has proven to be more efficient than the traditional film approach with equivalent results.« less

  15. Implementing Expertise-Based Training Methods to Accelerate the Development of Peer Academic Coaches

    ERIC Educational Resources Information Center

    Blair, Lisa

    2016-01-01

    The field of expertise studies offers several models from which to develop training programs that accelerate the development of novice performers in a variety of domains. This research study implemented two methods of expertise-based training in a course to develop undergraduate peer academic coaches through a ten-week program. An existing…

  16. Continuous Wavelet Transform Analysis of Acceleration Signals Measured from a Wave Buoy

    PubMed Central

    Chuang, Laurence Zsu-Hsin; Wu, Li-Chung; Wang, Jong-Hao

    2013-01-01

    Accelerometers, which can be installed inside a floating platform on the sea, are among the most commonly used sensors for operational ocean wave measurements. To examine the non-stationary features of ocean waves, this study was conducted to derive a wavelet spectrum of ocean waves and to synthesize sea surface elevations from vertical acceleration signals of a wave buoy through the continuous wavelet transform theory. The short-time wave features can be revealed by simultaneously examining the wavelet spectrum and the synthetic sea surface elevations. The in situ wave signals were applied to verify the practicality of the wavelet-based algorithm. We confirm that the spectral leakage and the noise at very-low-frequency bins influenced the accuracies of the estimated wavelet spectrum and the synthetic sea surface elevations. The appropriate thresholds of these two factors were explored. To study the short-time wave features from the wave records, the acceleration signals recorded from an accelerometer inside a discus wave buoy are analysed. The results from the wavelet spectrum show the evidence of short-time nonlinear wave events. Our study also reveals that more surface profiles with higher vertical asymmetry can be found from short-time nonlinear wave with stronger harmonic spectral peak. Finally, we conclude that the algorithms of continuous wavelet transform are practical for revealing the short-time wave features of the buoy acceleration signals. PMID:23966188

  17. The effect of accelerated aging on the wear of UHMWPE.

    PubMed

    Sakoda, H; Fisher, J; Lu, S; Buchanan, F

    2001-01-01

    Oxidative degradation of UHMWPE has been found to be a cause of elevated wear rate of the polymer in total joint replacement leading to failure of these devices. In order to evaluate long term stability of polymers, various accelerated aging methods have been developed. In this study, wear rates of shelf aged UHMWPE and "accelerated aged" UHMWPE were compared using a multi-directional pin-on-plate wear test machine in order to evaluate the effect of the accelerated aging on wear. Wear factors of the aged materials were found to depend on their density, which is a measure of oxidation level. Finally, accelerated aging was calibrated against shelf aging in terms of wear rate. Copyright 2001 Kluwer Academic Publishers

  18. Measuring Gravitation Using Polarization Spectroscopy

    NASA Technical Reports Server (NTRS)

    Matsko, Andrey; Yu, Nan; Maleki, Lute

    2004-01-01

    A proposed method of measuring gravitational acceleration would involve the application of polarization spectroscopy to an ultracold, vertically moving cloud of atoms (an atomic fountain). A related proposed method involving measurements of absorption of light pulses like those used in conventional atomic interferometry would yield an estimate of the number of atoms participating in the interferometric interaction. The basis of the first-mentioned proposed method is that the rotation of polarization of light is affected by the acceleration of atoms along the path of propagation of the light. The rotation of polarization is associated with a phase shift: When an atom moving in a laboratory reference interacts with an electromagnetic wave, the energy levels of the atom are Doppler-shifted, relative to where they would be if the atom were stationary. The Doppler shift gives rise to changes in the detuning of the light from the corresponding atomic transitions. This detuning, in turn, causes the electromagnetic wave to undergo a phase shift that can be measured by conventional means. One would infer the gravitational acceleration and/or the gradient of the gravitational acceleration from the phase measurements.

  19. Similar head impact acceleration measured using instrumented ear patches in a junior rugby union team during matches in comparison with other sports.

    PubMed

    King, Doug A; Hume, Patria A; Gissane, Conor; Clark, Trevor N

    2016-07-01

    OBJECTIVE Direct impact with the head and the inertial loading of the head have been postulated as major mechanisms of head-related injuries, such as concussion. METHODS This descriptive observational study was conducted to quantify the head impact acceleration characteristics in under-9-year-old junior rugby union players in New Zealand. The impact magnitude, frequency, and location were collected with a wireless head impact sensor that was worn by 14 junior rugby players who participated in 4 matches. RESULTS A total of 721 impacts > 10g were recorded. The median (interquartile range [IQR]) number of impacts per player was 46 (IQR 37-58), resulting in 10 (IQR 4-18) impacts to the head per player per match. The median impact magnitudes recorded were 15g (IQR 12g-21g) for linear acceleration and 2296 rad/sec(2) (IQR 1352-4152 rad/sec(2)) for rotational acceleration. CONCLUSIONS There were 121 impacts (16.8%) above the rotational injury risk limit and 1 (0.1%) impact above the linear injury risk limit. The acceleration magnitude and number of head impacts in junior rugby union players were higher than those previously reported in similar age-group sports participants. The median linear acceleration for the under-9-year-old rugby players were similar to 7- to 8-year-old American football players, but lower than 9- to 12-year-old youth American football players. The median rotational accelerations measured were higher than the median and 95th percentiles in youth, high school, and collegiate American football players.

  20. Theory and methods for measuring the effective multiplication constant in ADS

    NASA Astrophysics Data System (ADS)

    Rugama Saez, Yolanda

    2001-10-01

    In the thesis an absolute measurements technique for the subcriticality determination is presented. The ADS is a hybrid system where a subcritical system is fed by a proton accelerator. There are different proposals to define an ADS, one is to use plutonium and minor actinides from power plants waste as fuel to be transmuted into non radioactive isotopes (transmuter/burner, ATW). Another proposal is to use a Th232-U233 cycle (Energy Amplifier), being that thorium is an interesting and abundant fertile isotope. The development of accelerator driven systems (ADS) requires the development of methods to monitor and control the subcriticality of this kind of system without interfering with its normal operation mode. With this finality, we have applied noise analysis techniques that allow us to characterise the system when it is operating. The method presented in this thesis is based on the stochastic neutron and photon transport theory that can be implemented by presently available neutron/photon transport codes. In this work, first we analyse the stochastic transport theory which has been applied to define a parameter to determine the subcritical reactivity monitoring measurements. Finally we give the main limitations and recommendations for these subcritical monitoring methodology. As a result of the theoretical methodology, done in the first part of this thesis, a monitoring measurement technique has been developed and verified using two coupled Monte Carlo programs. The first one, LAHET, simulates the spallation collisions and the high energy transport and the other, MCNP-DSP, is used to estimate the counting statistics from a neutron/photon ray counter in a fissile system, as well as the transport for neutron with energies less than 20 MeV. From the coupling of both codes we developed the LAHET/MCNP-DSP code which, has the capability to simulate the total process in the ADS from the proton interaction to the signal detector processing. In these simulations, we

  1. Quartz crystal resonator g sensitivity measurement methods and recent results.

    PubMed

    Driscoll, M M

    1990-01-01

    A technique for accurate measurements of quartz crystal resonator vibration sensitivity is described. The technique utilizes a crystal oscillator circuit in which a prescribed length of coaxial cable is used to connect the resonator to the oscillator sustaining stage. A method is provided for determination and removal of measurement errors normally introduced as a result of cable vibration. In addition to oscillator-type measurements, it is also possible to perform similar vibration sensitivity measurements using a synthesized signal generator with the resonator installed in a passive phase bridge. Test results are reported for 40 and 50 MHz, fifth overtone AT-cut, and third overtone SC-cut crystals. Acceleration sensitivity (gamma vector) values for the SC-cut resonators were typically four times smaller (5x10(-10) per g) than for the AT-cut units. However, smaller unit-to-unit gamma vector magnitude variation was exhibited by the AT-cut resonators. Oscillator sustaining stage vibration sensitivity was characterized by an equivalent open-loop phase modulation of 10(-6) rad/g.

  2. Moving at the Speed of Potential: A Mixed-Methods Study of Accelerating Developmental Students in a California Community College

    ERIC Educational Resources Information Center

    Parks, Paula L.

    2014-01-01

    Most developmental community college students are not completing the composition sequence successfully. This mixed-methods study examined acceleration as a way to help developmental community college students complete the composition sequence more quickly and more successfully. Acceleration is a curricular redesign that includes challenging…

  3. Summary report of mission acceleration measurements for Spacehab-01, STS-57 launched 21 June 1993

    NASA Technical Reports Server (NTRS)

    Finley, Brian; Grodsinsky, Carlos; Delombard, Richard

    1994-01-01

    The maiden voyage of the commercial Spacehab laboratory module onboard the STS-57 mission was integrated with several accelerometer packages, one of which was the Space Acceleration Measurement System (SAMS). The June 21st 1993, launch was the seventh successful mission for the Office of Life and Microgravity Sciences and Application's (OLMSA) SAMS unit. This flight was also complemented by a second accelerometer system. The Three Dimensional Microgravity Accelerometer (3-DMA), a Code C funded acceleration measurement system, offering an on-orbit residual calibration as a reference for the unit's four triaxial accelerometers. The SAMS accelerometer unit utilized three remote triaxial sensor heads mounted on the forward Spacehab module bulkhead and on one centrally located experiment locker door. These triaxial heads had filter cut-offs set to 5, 50, and 1000 Hz. The mission also included other experiment specific accelerometer packages in various locations.

  4. The Krylov accelerated SIMPLE(R) method for flow problems in industrial furnaces

    NASA Astrophysics Data System (ADS)

    Vuik, C.; Saghir, A.; Boerstoel, G. P.

    2000-08-01

    Numerical modeling of the melting and combustion process is an important tool in gaining understanding of the physical and chemical phenomena that occur in a gas- or oil-fired glass-melting furnace. The incompressible Navier-Stokes equations are used to model the gas flow in the furnace. The discrete Navier-Stokes equations are solved by the SIMPLE(R) pressure-correction method. In these applications, many SIMPLE(R) iterations are necessary to obtain an accurate solution. In this paper, Krylov accelerated versions are proposed: GCR-SIMPLE(R). The properties of these methods are investigated for a simple two-dimensional flow. Thereafter, the efficiencies of the methods are compared for three-dimensional flows in industrial glass-melting furnaces. Copyright

  5. Measurement of changes in linear accelerator photon energy through flatness variation using an ion chamber array

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

    Gao Song; Balter, Peter A.; Rose, Mark

    2013-04-15

    Purpose: To compare the use of flatness versus percent depth dose (PDD) for determining changes in photon beam energy for a megavoltage linear accelerator. Methods: Energy changes were accomplished by adjusting the bending magnet current by up to {+-}15% in 5% increments away from the value used clinically. Two metrics for flatness, relative flatness in the central 80% of the field (Flat) and average maximum dose along the diagonals normalized by central axis dose (F{sub DN}), were measured using a commercially available planner ionization chamber array. PDD was measured in water at depths of 5 and 10 cm in 3more » Multiplication-Sign 3 cm{sup 2} and 10 Multiplication-Sign 10 cm{sup 2} fields using a cylindrical chamber. Results: PDD was more sensitive to changes in energy when the beam energy was increased than when it was decreased. For the 18-MV beam in particular, PDD was not sensitive to energy reductions below the nominal energy. The value of Flat was found to be more sensitive to decreases in energy than to increases, with little sensitivity to energy increases above the nominal energy for 18-MV beams. F{sub DN} was the only metric that was found to be sensitive to both increases and reductions of energy for both the 6- and 18-MV beams. Conclusions: Flatness based metrics were found to be more sensitive to energy changes than PDD, In particular, F{sub DN} was found to be the most sensitive metric to energy changes for photon beams of 6 and 18 MV. The ionization chamber array allows this metric to be conveniently measured as part of routine accelerator quality assurance.« less

  6. Acceleration performance of individual European sea bass Dicentrarchus labrax measured with a sprint performance chamber: comparison with high-speed cinematography and correlates with ecological performance.

    PubMed

    Vandamm, Joshua P; Marras, Stefano; Claireaux, Guy; Handelsman, Corey A; Nelson, Jay A

    2012-01-01

    Locomotor performance can influence the ecological and evolutionary success of a species. For fish, favorable outcomes of predator-prey encounters are often presumably due to robust acceleration ability. Although escape-response or "fast-start" studies utilizing high-speed cinematography are prevalent, little is known about the contribution of relative acceleration performance to ecological or evolutionary success in a species. This dearth of knowledge may be due to the time-consuming nature of analyzing film, which imposes a practical limit on sample sizes. Herein, we present a high-throughput potential alternative for measuring fish acceleration performance using a sprint performance chamber (SPC). The acceleration performance of a large number of juvenile European sea bass (Dicentrarchus labrax) from two populations was analyzed. Animals from both hatchery and natural ontogenies were assessed, and animals of known acceleration ability had their ecological performance measured in a mesocosm environment. Individuals from one population also had their acceleration performance assessed by both high-speed cinematography and an SPC. Acceleration performance measured in an SPC was lower than that measured by classical high-speed video techniques. However, short-term repeatability and interindividual variation of acceleration performance were similar between the two techniques, and the SPC recorded higher sprint swimming velocities. Wild fish were quicker to accelerate in an SPC and had significantly greater accelerations than all groups of hatchery-raised fish. Acceleration performance had no significant effect on ecological performance (as assessed through animal growth and survival in the mesocosms). However, it is worth noting that wild animals did survive predation in the mesocosm better than farmed ones. Moreover, the hatchery-originated fish that survived the mesocosm experiment, when no predators were present, displayed significantly increased acceleration

  7. Double temporal sparsity based accelerated reconstruction of compressively sensed resting-state fMRI.

    PubMed

    Aggarwal, Priya; Gupta, Anubha

    2017-12-01

    A number of reconstruction methods have been proposed recently for accelerated functional Magnetic Resonance Imaging (fMRI) data collection. However, existing methods suffer with the challenge of greater artifacts at high acceleration factors. This paper addresses the issue of accelerating fMRI collection via undersampled k-space measurements combined with the proposed method based on l 1 -l 1 norm constraints, wherein we impose first l 1 -norm sparsity on the voxel time series (temporal data) in the transformed domain and the second l 1 -norm sparsity on the successive difference of the same temporal data. Hence, we name the proposed method as Double Temporal Sparsity based Reconstruction (DTSR) method. The robustness of the proposed DTSR method has been thoroughly evaluated both at the subject level and at the group level on real fMRI data. Results are presented at various acceleration factors. Quantitative analysis in terms of Peak Signal-to-Noise Ratio (PSNR) and other metrics, and qualitative analysis in terms of reproducibility of brain Resting State Networks (RSNs) demonstrate that the proposed method is accurate and robust. In addition, the proposed DTSR method preserves brain networks that are important for studying fMRI data. Compared to the existing methods, the DTSR method shows promising potential with an improvement of 10-12 dB in PSNR with acceleration factors upto 3.5 on resting state fMRI data. Simulation results on real data demonstrate that DTSR method can be used to acquire accelerated fMRI with accurate detection of RSNs. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. A novel accelerated in vitro release method to evaluate the release of thymopentin from PLGA microspheres.

    PubMed

    Xie, Xiangyang; Li, Zhiping; Zhang, Ling; Chi, Qiang; Yang, Yanfang; Zhang, Hui; Yang, Yang; Mei, Xingguo

    2015-01-01

    A novel accelerated method of good correlations with "real-time" release to evaluate in vitro thymopentin release from poly (D, L-lactide-co-glycolide) (PLGA) microsphere was developed. Thymopentin-loaded microspheres were made from three types of PLGA, and peptide release was studied in various conditions. Incomplete release of peptide (<60%) from microspheres was found in accelerated testing with two typical release media. This problem was circumvented by adding organic solvents to the release media and varying the temperature in the media heating process. Release media containing three kinds of organic solvents at 50 °C were tested, respectively, and hydro-alcoholic solution was selected for further study. After the surfactant concentration (0.06%, W/V) and ethanol concentration (20%, V/V) were fixed, a gradient heating program, consisting of three stages and each stage with a different temperature, was introduced to enhance the correlations between the short- and long-term release. After adjusting the heating time of each stage, a good correlation (R(2) = 9896, formulation 8 K; R(2) = 0.9898, formulation 13 K; R(2) = 0.9886, formulation 28 K) between accelerated and "real-time" release was obtained. By optimizing the conditions as ethanol concentration and temperature gradients, this accelerated method may be appropriate for similar peptide formulations that not well correlate with "real-time" release.

  9. Mass spectrometry with accelerators.

    PubMed

    Litherland, A E; Zhao, X-L; Kieser, W E

    2011-01-01

    As one in a series of articles on Canadian contributions to mass spectrometry, this review begins with an outline of the history of accelerator mass spectrometry (AMS), noting roles played by researchers at three Canadian AMS laboratories. After a description of the unique features of AMS, three examples, (14)C, (10)Be, and (129)I are given to illustrate the methods. The capabilities of mass spectrometry have been extended by the addition of atomic isobar selection, molecular isobar attenuation, further ion acceleration, followed by ion detection and ion identification at essentially zero dark current or ion flux. This has been accomplished by exploiting the techniques and accelerators of atomic and nuclear physics. In 1939, the first principles of AMS were established using a cyclotron. In 1977 the selection of isobars in the ion source was established when it was shown that the (14)N(-) ion was very unstable, or extremely difficult to create, making a tandem electrostatic accelerator highly suitable for assisting the mass spectrometric measurement of the rare long-lived radioactive isotope (14)C in the environment. This observation, together with the large attenuation of the molecular isobars (13)CH(-) and (12)CH 2(-) during tandem acceleration and the observed very low background contamination from the ion source, was found to facilitate the mass spectrometry of (14)C to at least a level of (14)C/C ~ 6 × 10(-16), the equivalent of a radiocarbon age of 60,000 years. Tandem Accelerator Mass Spectrometry, or AMS, has now made possible the accurate radiocarbon dating of milligram-sized carbon samples by ion counting as well as dating and tracing with many other long-lived radioactive isotopes such as (10)Be, (26)Al, (36)Cl, and (129)I. The difficulty of obtaining large anion currents with low electron affinities and the difficulties of isobar separation, especially for the heavier mass ions, has prompted the use of molecular anions and the search for alternative

  10. Subattomole sensitivity in biological accelerator mass spectrometry.

    PubMed

    Salehpour, Mehran; Possnert, Göran; Bryhni, Helge

    2008-05-15

    The Uppsala University 5 MV Pelletron tandem accelerator has been used to study (14)C-labeled biological samples utilizing accelerator mass spectrometry (AMS) technology. We have adapted a sample preparation method for small biological samples down to a few tens of micrograms of carbon, involving among others, miniaturizing of the graphitization reactor. Standard AMS requires about 1 mg of carbon with a limit of quantitation of about 10 amol. Results are presented for a range of small sample sizes with concentrations down to below 1 pM of a pharmaceutical substance in human blood. It is shown that (14)C-labeled molecular markers can be routinely measured from the femtomole range down to a few hundred zeptomole (10 (-21) mol), without the use of any additional separation methods.

  11. Improving power output of inertial energy harvesters by employing principal component analysis of input acceleration

    NASA Astrophysics Data System (ADS)

    Smilek, Jan; Hadas, Zdenek

    2017-02-01

    In this paper we propose the use of principal component analysis to process the measured acceleration data in order to determine the direction of acceleration with the highest variance on given frequency of interest. This method can be used for improving the power generated by inertial energy harvesters. Their power output is highly dependent on the excitation acceleration magnitude and frequency, but the axes of acceleration measurements might not always be perfectly aligned with the directions of movement, and therefore the generated power output might be severely underestimated in simulations, possibly leading to false conclusions about the feasibility of using the inertial energy harvester for the examined application.

  12. Fabrication of 94Zr thin target for recoil distance doppler shift method of lifetime measurement

    NASA Astrophysics Data System (ADS)

    Gupta, C. K.; Rohilla, Aman; Abhilash, S. R.; Kabiraj, D.; Singh, R. P.; Mehta, D.; Chamoli, S. K.

    2014-11-01

    A thin isotopic 94Zr target of thickness 520 μg /cm2 has been prepared for recoil distance Doppler shift method (RDM) lifetime measurement by using an electron beam deposition method on tantalum backing of 3.5 mg/cm2 thickness at Inter University Accelerator Center (IUAC), New Delhi. To meet the special requirement of smoothness of surface for RDM lifetime measurement and also to protect the outer layer of 94Zr from peeling off, a very thin layer of gold has been evaporated on a 94Zr target on a specially designed substrate holder. In all, 143 mg of 99.6% enriched 94Zr target material was utilized for the fabrication of 94Zr targets. The target has been successfully used in a recent RDM lifetime measurement experiment at IUAC.

  13. Epigenetic Age Acceleration Assessed with Human White-Matter Images.

    PubMed

    Hodgson, Karen; Carless, Melanie A; Kulkarni, Hemant; Curran, Joanne E; Sprooten, Emma; Knowles, Emma E; Mathias, Samuel; Göring, Harald H H; Yao, Nailin; Olvera, Rene L; Fox, Peter T; Almasy, Laura; Duggirala, Ravi; Blangero, John; Glahn, David C

    2017-05-03

    The accurate estimation of age using methylation data has proved a useful and heritable biomarker, with acceleration in epigenetic age predicting a number of age-related phenotypes. Measures of white matter integrity in the brain are also heritable and highly sensitive to both normal and pathological aging processes across adulthood. We consider the phenotypic and genetic interrelationships between epigenetic age acceleration and white matter integrity in humans. Our goal was to investigate processes that underlie interindividual variability in age-related changes in the brain. Using blood taken from a Mexican-American extended pedigree sample ( n = 628; age = 23.28-93.11 years), epigenetic age was estimated using the method developed by Horvath (2013). For n = 376 individuals, diffusion tensor imaging scans were also available. The interrelationship between epigenetic age acceleration and global white matter integrity was investigated with variance decomposition methods. To test for neuroanatomical specificity, 16 specific tracts were additionally considered. We observed negative phenotypic correlations between epigenetic age acceleration and global white matter tract integrity (ρ pheno = -0.119, p = 0.028), with evidence of shared genetic (ρ gene = -0.463, p = 0.013) but not environmental influences. Negative phenotypic and genetic correlations with age acceleration were also seen for a number of specific white matter tracts, along with additional negative phenotypic correlations between granulocyte abundance and white matter integrity. These findings (i.e., increased acceleration in epigenetic age in peripheral blood correlates with reduced white matter integrity in the brain and shares common genetic influences) provide a window into the neurobiology of aging processes within the brain and a potential biomarker of normal and pathological brain aging. SIGNIFICANCE STATEMENT Epigenetic measures can be used to predict age with a high degree of accuracy and so

  14. Method of accelerating photons by a relativistic plasma wave

    DOEpatents

    Dawson, John M.; Wilks, Scott C.

    1990-01-01

    Photons of a laser pulse have their group velocity accelerated in a plasma as they are placed on a downward density gradient of a plasma wave of which the phase velocity nearly matches the group velocity of the photons. This acceleration results in a frequency upshift. If the unperturbed plasma has a slight density gradient in the direction of propagation, the photon frequencies can be continuously upshifted to significantly greater values.

  15. Flow characteristics in a canine aneurysm model: A comparison of 4D accelerated phase-contrast MR measurements and computational fluid dynamics simulations

    PubMed Central

    Jiang, Jingfeng; Johnson, Kevin; Valen-Sendstad, Kristian; Mardal, Kent-Andre; Wieben, Oliver; Strother, Charles

    2011-01-01

    Purpose: Our purpose was to compare quantitatively velocity fields in and around experimental canine aneurysms as measured using an accelerated 4D PC-MR angiography (MRA) method and calculated based on animal-specific CFD simulations. Methods: Two animals with a surgically created bifurcation aneurysm were imaged using an accelerated 4D PC-MRA method. Meshes were created based on the geometries obtained from the PC-MRA and simulations using “subject-specific” pulsatile velocity waveforms and geometries were then solved using a commercial CFD solver. Qualitative visual assessments and quantitative comparisons of the time-resolved velocity fields obtained from the PC-MRA measurements and the CFD simulations were performed using a defined similarity metric combining both angular and magnitude differences of vector fields. Results: PC-MRA and image-based CFD not only yielded visually consistent representations of 3D streamlines in and around both aneurysms, but also showed good agreement with regard to the spatial velocity distributions. The estimated similarity between time-resolved velocity fields from both techniques was reasonably high (mean value >0.60; one being the highest and zero being the lowest). Relative differences in inflow and outflow zones among selected planes were also reasonable (on the order of 10%–20%). The correlation between CFD-calculated and PC-MRA-measured time-averaged wall shear stresses was low (0.22 and 0.31, p < 0.001). Conclusions: In two experimental canine aneurysms, PC-MRA and image-based CFD showed favorable agreement in intra-aneurismal velocity fields. Combining these two complementary techniques likely will further improve the ability to characterize and interpret the complex flow that occurs in human intracranial aneurysms. PMID:22047395

  16. Method of and apparatus for accelerating a projectile

    DOEpatents

    Goldstein, Yeshayahu S. A.; Tidman, Derek A.

    1986-01-01

    A projectile is accelerated along a confined path by supplying a pulsed high pressure, high velocity plasma jet to the rear of the projectile as the projectile traverses the path. The jet enters the confined path at a non-zero angle relative to the projectile path. The pulse is derived from a dielectric capillary tube having an interior wall from which plasma forming material is ablated in response to a discharge voltage. The projectile can be accelerated in response to the kinetic energy in the plasma jet or in response to a pressure increase of gases in the confined path resulting from the heat added to the gases by the plasma.

  17. Modeling of Particle Acceleration at Multiple Shocks via Diffusive Shock Acceleration: Preliminary Results

    NASA Technical Reports Server (NTRS)

    Parker, L. Neergaard; Zank, G. P.

    2013-01-01

    Successful forecasting of energetic particle events in space weather models require algorithms for correctly predicting the spectrum of ions accelerated from a background population of charged particles. We present preliminary results from a model that diffusively accelerates particles at multiple shocks. Our basic approach is related to box models in which a distribution of particles is diffusively accelerated inside the box while simultaneously experiencing decompression through adiabatic expansion and losses from the convection and diffusion of particles outside the box. We adiabatically decompress the accelerated particle distribution between each shock by either the method explored in Melrose and Pope (1993) and Pope and Melrose (1994) or by the approach set forth in Zank et al. (2000) where we solve the transport equation by a method analogous to operator splitting. The second method incorporates the additional loss terms of convection and diffusion and allows for the use of a variable time between shocks. We use a maximum injection energy (E(sub max)) appropriate for quasi-parallel and quasi-perpendicular shocks and provide a preliminary application of the diffusive acceleration of particles by multiple shocks with frequencies appropriate for solar maximum (i.e., a non-Markovian process).

  18. Measurement and Characterization of the Acceleration Environment on Board the Space Station

    NASA Technical Reports Server (NTRS)

    Baugher, Charles R. (Editor)

    1990-01-01

    This workshop provides a comprehensive overview of the work and status of each of these areas to provide a basis for establishing a systematic approach to the challenge of avoiding these difficulties during the Space Station era of materials experimentation. The discussions were arranged in the order of: the scientific understanding of the requirements for a micro-gravity environment, a history of acceleration measurements on spacecraft, the state of accelerometer technology, and the current understanding of the predicted Space Station environment.

  19. Acceleration and rotation in a pendulum ride, measured using an iPhone 4

    NASA Astrophysics Data System (ADS)

    Pendrill, Ann-Marie; Rohlén, Johan

    2011-11-01

    Many modern cell phones have built-in sensors that may be used as a resource for physics education. Amusement rides offer examples of many different types of motion, where the acceleration leads to forces experienced throughout the body. A comoving 3D-accelerometer gives an electronic measurement of the varying forces acting on the rider, but a complete description of a motion also requires measurement of the rotation around the three axes, as provided, for example, by the iPhone 4. Here we present and interpret accelerometer and gyroscope data that were collected on a rotary pendulum ride.

  20. Dental movement acceleration: Literature review by an alternative scientific evidence method

    PubMed Central

    Camacho, Angela Domínguez; Cujar, Sergio Andres Velásquez

    2014-01-01

    The aim of this study was to analyze the majority of publications using effective methods to speed up orthodontic treatment and determine which publications carry high evidence-based value. The literature published in Pubmed from 1984 to 2013 was reviewed, in addition to well-known reports that were not classified under this database. To facilitate evidence-based decision making, guidelines such as the Consolidation Standards of Reporting Trials, Preferred Reporting items for systematic Reviews and Meta-analyses, and Transparent Reporting of Evaluations with Non-randomized Designs check list were used. The studies were initially divided into three groups: local application of cell mediators, physical stimuli, and techniques that took advantage of the regional acceleration phenomena. The articles were classified according to their level of evidence using an alternative method for orthodontic scientific article classification. 1a: Systematic Reviews (SR) of randomized clinical trials (RCTs), 1b: Individual RCT, 2a: SR of cohort studies, 2b: Individual cohort study, controlled clinical trials and low quality RCT, 3a: SR of case-control studies, 3b: Individual case-control study, low quality cohort study and short time following split mouth designs. 4: Case-series, low quality case-control study and non-systematic review, and 5: Expert opinion. The highest level of evidence for each group was: (1) local application of cell mediators: the highest level of evidence corresponds to a 3B level in Prostaglandins and Vitamin D; (2) physical stimuli: vibratory forces and low level laser irradiation have evidence level 2b, Electrical current is classified as 3b evidence-based level, Pulsed Electromagnetic Field is placed on the 4th level on the evidence scale; and (3) regional acceleration phenomena related techniques: for corticotomy the majority of the reports belong to level 4. Piezocision, dentoalveolar distraction, alveocentesis, monocortical tooth dislocation and ligament

  1. Challenges of accelerated aging techniques for elastomer lifetime predictions

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

    Gillen, Kenneth T.; Bernstein, R.; Celina, M.

    Elastomers are often degraded when exposed to air or high humidity for extended times (years to decades). Lifetime estimates normally involve extrapolating accelerated aging results made at higher than ambient environments. Several potential problems associated with such studies are reviewed, and experimental and theoretical methods to address them are provided. The importance of verifying time–temperature superposition of degradation data is emphasized as evidence that the overall nature of the degradation process remains unchanged versus acceleration temperature. The confounding effects that occur when diffusion-limited oxidation (DLO) contributes under accelerated conditions are described, and it is shown that the DLO magnitude canmore » be modeled by measurements or estimates of the oxygen permeability coefficient (P Ox) and oxygen consumption rate (Φ). P Ox and Φ measurements can be influenced by DLO, and it is demonstrated how confident values can be derived. In addition, several experimental profiling techniques that screen for DLO effects are discussed. Values of Φ taken from high temperature to temperatures approaching ambient can be used to more confidently extrapolate accelerated aging results for air-aged materials, and many studies now show that Arrhenius extrapolations bend to lower activation energies as aging temperatures are lowered. Furthermore, best approaches for accelerated aging extrapolations of humidity-exposed materials are also offered.« less

  2. Challenges of accelerated aging techniques for elastomer lifetime predictions

    DOE PAGES

    Gillen, Kenneth T.; Bernstein, R.; Celina, M.

    2015-03-01

    Elastomers are often degraded when exposed to air or high humidity for extended times (years to decades). Lifetime estimates normally involve extrapolating accelerated aging results made at higher than ambient environments. Several potential problems associated with such studies are reviewed, and experimental and theoretical methods to address them are provided. The importance of verifying time–temperature superposition of degradation data is emphasized as evidence that the overall nature of the degradation process remains unchanged versus acceleration temperature. The confounding effects that occur when diffusion-limited oxidation (DLO) contributes under accelerated conditions are described, and it is shown that the DLO magnitude canmore » be modeled by measurements or estimates of the oxygen permeability coefficient (P Ox) and oxygen consumption rate (Φ). P Ox and Φ measurements can be influenced by DLO, and it is demonstrated how confident values can be derived. In addition, several experimental profiling techniques that screen for DLO effects are discussed. Values of Φ taken from high temperature to temperatures approaching ambient can be used to more confidently extrapolate accelerated aging results for air-aged materials, and many studies now show that Arrhenius extrapolations bend to lower activation energies as aging temperatures are lowered. Furthermore, best approaches for accelerated aging extrapolations of humidity-exposed materials are also offered.« less

  3. Accelerated stress testing of thin film solar cells: Development of test methods and preliminary results

    NASA Technical Reports Server (NTRS)

    Lathrop, J. W.

    1985-01-01

    If thin film cells are to be considered a viable option for terrestrial power generation their reliability attributes will need to be explored and confidence in their stability obtained through accelerated testing. Development of a thin film accelerated test program will be more difficult than was the case for crystalline cells because of the monolithic construction nature of the cells. Specially constructed test samples will need to be fabricated, requiring committment to the concept of accelerated testing by the manufacturers. A new test schedule appropriate to thin film cells will need to be developed which will be different from that used in connection with crystalline cells. Preliminary work has been started to seek thin film schedule variations to two of the simplest tests: unbiased temperature and unbiased temperature humidity. Still to be examined are tests which involve the passage of current during temperature and/or humidity stress, either by biasing in the forward (or reverse) directions or by the application of light during stress. Investigation of these current (voltage) accelerated tests will involve development of methods of reliably contacting the thin conductive films during stress.

  4. Anderson acceleration and application to the three-temperature energy equations

    NASA Astrophysics Data System (ADS)

    An, Hengbin; Jia, Xiaowei; Walker, Homer F.

    2017-10-01

    The Anderson acceleration method is an algorithm for accelerating the convergence of fixed-point iterations, including the Picard method. Anderson acceleration was first proposed in 1965 and, for some years, has been used successfully to accelerate the convergence of self-consistent field iterations in electronic-structure computations. Recently, the method has attracted growing attention in other application areas and among numerical analysts. Compared with a Newton-like method, an advantage of Anderson acceleration is that there is no need to form the Jacobian matrix. Thus the method is easy to implement. In this paper, an Anderson-accelerated Picard method is employed to solve the three-temperature energy equations, which are a type of strong nonlinear radiation-diffusion equations. Two strategies are used to improve the robustness of the Anderson acceleration method. One strategy is to adjust the iterates when necessary to satisfy the physical constraint. Another strategy is to monitor and, if necessary, reduce the matrix condition number of the least-squares problem in the Anderson-acceleration implementation so that numerical stability can be guaranteed. Numerical results show that the Anderson-accelerated Picard method can solve the three-temperature energy equations efficiently. Compared with the Picard method without acceleration, Anderson acceleration can reduce the number of iterations by at least half. A comparison between a Jacobian-free Newton-Krylov method, the Picard method, and the Anderson-accelerated Picard method is conducted in this paper.

  5. On the feasibility of sub-100 nm rad emittance measurement in plasma accelerators using permanent magnetic quadrupoles

    NASA Astrophysics Data System (ADS)

    Li, F.; Wu, Y. P.; Nie, Z.; Guo, B.; Zhang, X. H.; Huang, S.; Zhang, J.; Cheng, Z.; Ma, Y.; Fang, Y.; Zhang, C. J.; Wan, Y.; Xu, X. L.; Hua, J. F.; Pai, C. H.; Lu, W.; Gu, Y. Q.

    2018-01-01

    Low emittance (sub-100 nm rad) measurement of electron beams in plasma accelerators has been a challenging issue for a while. Among various measurement schemes, measurements based on single-shot quad-scan using permanent magnetic quadrupoles (PMQs) has been recently reported with emittance as low as ˜200 nm Weingartner (2012 Phys. Rev. Spec. Top. Accel. Beams 15 111302). However, the accuracy and reliability of this method have not been systematically analyzed. Such analysis is critical for evaluating the potential of sub-100 nm rad emittance measurement using any scheme. In this paper, we analyze the effects of various nonideal physical factors on the accuracy and reliability using the PMQ method. These factors include aberration induced by a high order field, PMQ misalignment and angular fluctuation of incoming beams. Our conclusions are as follows: (i) the aberrations caused by high order fields of PMQs are relatively weak for low emittance measurement as long as the PMQs are properly constructed. A series of PMQs were manufactured and measured at Tsinghua University, and using numerical simulations their high order field effects were found to be negligible . (ii) The largest measurement error of emittance is caused by the angular misalignment between PMQs. For low emittance measurement of ˜100 MeV beams, an angular alignment accuracy of 0.1° is necessary. This requirement can be eased for beams with higher energies. (iii) The transverse position misalignment of PMQs and angular fluctuation of incoming beams only cause a translational and rotational shift of measured signals, respectively, therefore, there is no effect on the measured value of emittance. (iv) The spatial resolution and efficiency of the detection system need to be properly designed to guarantee the accuracy of sub-100 nm rad emittance measurement.

  6. Lithium target performance evaluation for low-energy accelerator-based in vivo measurements using gamma spectroscopy.

    PubMed

    Aslam; Prestwich, W V; McNeill, F E

    2003-03-01

    The operating conditions at McMaster KN Van de Graaf accelerator have been optimized to produce neutrons via the (7)Li(p, n)(7)Be reaction for in vivo neutron activation analysis. In a number of earlier studies (development of an accelerator based system for in vivo neutron activation analysis measurements of manganese in humans, Ph.D. Thesis, McMaster University, Hamilton, ON, Canada; Appl. Radiat. Isot. 53 (2000) 657; in vivo measurement of some trace elements in human Bone, Ph.D. Thesis. McMaster University, Hamilton, ON, Canada), a significant discrepancy between the experimental and the calculated neutron doses has been pointed out. The hypotheses formulated in the above references to explain the deviation of the experimental results from analytical calculations, have been tested experimentally. The performance of the lithium target for neutron production has been evaluated by measuring the (7)Be activity produced as a result of (p, n) interaction with (7)Li. In contradiction to the formulated hypotheses, lithium target performance was found to be mainly affected by inefficient target cooling and the presence of oxides layer on target surface. An appropriate choice of these parameters resulted in neutron yields same as predicated by analytical calculations.

  7. Development of wide area environment accelerator operation and diagnostics method

    NASA Astrophysics Data System (ADS)

    Uchiyama, Akito; Furukawa, Kazuro

    2015-08-01

    Remote operation and diagnostic systems for particle accelerators have been developed for beam operation and maintenance in various situations. Even though fully remote experiments are not necessary, the remote diagnosis and maintenance of the accelerator is required. Considering remote-operation operator interfaces (OPIs), the use of standard protocols such as the hypertext transfer protocol (HTTP) is advantageous, because system-dependent protocols are unnecessary between the remote client and the on-site server. Here, we have developed a client system based on WebSocket, which is a new protocol provided by the Internet Engineering Task Force for Web-based systems, as a next-generation Web-based OPI using the Experimental Physics and Industrial Control System Channel Access protocol. As a result of this implementation, WebSocket-based client systems have become available for remote operation. Also, as regards practical application, the remote operation of an accelerator via a wide area network (WAN) faces a number of challenges, e.g., the accelerator has both experimental device and radiation generator characteristics. Any error in remote control system operation could result in an immediate breakdown. Therefore, we propose the implementation of an operator intervention system for remote accelerator diagnostics and support that can obviate any differences between the local control room and remote locations. Here, remote-operation Web-based OPIs, which resolve security issues, are developed.

  8. Semiconductor acceleration sensor

    NASA Astrophysics Data System (ADS)

    Ueyanagi, Katsumichi; Kobayashi, Mitsuo; Goto, Tomoaki

    1996-09-01

    This paper reports a practical semiconductor acceleration sensor especially suited for automotive air bag systems. The acceleration sensor includes four beams arranged in a swastika structure. Two piezoresistors are formed on each beam. These eight piezoresistors constitute a Wheatstone bridge. The swastika structure of the sensing elements, an upper glass plate and a lower glass plate exhibit the squeeze film effect which enhances air dumping, by which the constituent silicon is prevented from breakdown. The present acceleration sensor has the following features. The acceleration force component perpendicular to the sensing direction can be cancelled. The cross-axis sensitivity is less than 3 percent. And, the erroneous offset caused by the differences between the thermal expansion coefficients of the constituent materials can be canceled. The high aspect ratio configuration realized by plasma etching facilitates reducing the dimensions and improving the sensitivity of the acceleration sensor. The present acceleration sensor is 3.9 mm by 3.9 mm in area and 1.2 mm in thickness. The present acceleration sensor can measure from -50 to +50 G with sensitivity of 0.275 mV/G and with non-linearity of less than 1 percent. The acceleration sensor withstands shock of 3000 G.

  9. [Shielding design and detection of neutrons from medical and industrial electron accelerators--simple method of design calculation for neutron shielding].

    PubMed

    Nakamura, T; Uwamino, Y

    1986-02-01

    The neutron leakage from medical and industrial electron accelerators has become an important problem and its detection and shielding is being performed in their facilities. This study provides a new simple method of design calculation for neutron shielding of those electron accelerator facilities by dividing into the following five categories; neutron dose distribution in the accelerator room, neutron attenuation through the wall and the door in the accelerator room, neutron and secondary photon dose distributions in the maze, neutron and secondary photon attenuation through the door at the end of the maze, neutron leakage outside the facility-skyshine.

  10. Method for generating extreme ultraviolet with mather-type plasma accelerators for use in Extreme Ultraviolet Lithography

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

    Hassanein, Ahmed; Konkashbaev, Isak

    A device and method for generating extremely short-wave ultraviolet electromagnetic wave uses two intersecting plasma beams generated by two plasma accelerators. The intersection of the two plasma beams emits electromagnetic radiation and in particular radiation in the extreme ultraviolet wavelength. In the preferred orientation two axially aligned counter streaming plasmas collide to produce an intense source of electromagnetic radiation at the 13.5 nm wavelength. The Mather type plasma accelerators can utilize tin, or lithium covered electrodes. Tin, lithium or xenon can be used as the photon emitting gas source.

  11. Analysis of quality control data of eight modern radiotherapy linear accelerators: the short- and long-term behaviours of the outputs and the reproducibility of quality control measurements

    NASA Astrophysics Data System (ADS)

    Kapanen, Mika; Tenhunen, Mikko; Hämäläinen, Tuomo; Sipilä, Petri; Parkkinen, Ritva; Järvinen, Hannu

    2006-07-01

    Quality control (QC) data of radiotherapy linear accelerators, collected by Helsinki University Central Hospital between the years 2000 and 2004, were analysed. The goal was to provide information for the evaluation and elaboration of QC of accelerator outputs and to propose a method for QC data analysis. Short- and long-term drifts in outputs were quantified by fitting empirical mathematical models to the QC measurements. Normally, long-term drifts were well (<=1%) modelled by either a straight line or a single-exponential function. A drift of 2% occurred in 18 ± 12 months. The shortest drift times of only 2-3 months were observed for some new accelerators just after the commissioning but they stabilized during the first 2-3 years. The short-term reproducibility and the long-term stability of local constancy checks, carried out with a sealed plane parallel ion chamber, were also estimated by fitting empirical models to the QC measurements. The reproducibility was 0.2-0.5% depending on the positioning practice of a device. Long-term instabilities of about 0.3%/month were observed for some checking devices. The reproducibility of local absorbed dose measurements was estimated to be about 0.5%. The proposed empirical model fitting of QC data facilitates the recognition of erroneous QC measurements and abnormal output behaviour, caused by malfunctions, offering a tool to improve dose control.

  12. Influence of the ambient acceleration field upon acute acceleration tolerance in chickens

    NASA Technical Reports Server (NTRS)

    Smith, A. H.; Spangler, W. L.; Rhode, E. A.; Burton, R. R.

    1979-01-01

    The paper measured the acceleration tolerance of domestic fowl (Rhode Island Red cocks), acutely exposed to a 6 Gz field, as the time over which a normal heart rate can be maintained. This period of circulatory adjustment ends abruptly with pronounced bradycardia. For chickens which previously have been physiologically adapted to 2.5 -G field, the acute acceleration tolerance is greatly increased. The influence of the ambient acceleration field on the adjustment of the circulatory system appears to be a general phenomenon.

  13. A Method of Calibrating Airspeed Installations on Airplanes at Transonic and Supersonic Speeds by the Use of Accelerometer and Attitude-Angle Measurements

    NASA Technical Reports Server (NTRS)

    Zalovick, John A; Lina, Lindsay J; Trant, James P , Jr

    1953-01-01

    A method is described for calibrating airspeed installation on airplanes at transonic and supersonic speeds in vertical-plane maneuvers in which use is made of measurements of normal and longitudinal accelerations and attitude angle. In this method all the required instrumentation is carried within the airplane. An analytical study of the effects of various sources of error on the accuracy of an airspeed calibration by the accelerometer method indicated that the required measurements can be made accurately enough to insure a satisfactory calibration.

  14. Fusion-neutron measurements for magnetized liner inertial fusion experiments on the Z accelerator

    DOE PAGES

    Hahn, K. D.; Chandler, G. A.; Ruiz, C. L.; ...

    2016-05-26

    Several magnetized liner inertial fusion (MagLIF) experiments have been conducted on the Z accelerator at Sandia National Laboratories since late 2013. Measurements of the primary DD (2.45 MeV) neutrons for these experiments suggest that the neutron production is thermonuclear. Primary DD yields up to 3e12 with ion temperatures ~2-3 keV have been achieved. Measurements of the secondary DT (14 MeV) neutrons indicate that the fuel is significantly magnetized. Measurements of down-scattered neutrons from the beryllium liner suggest ρR liner ~ 1g/cm 2. Neutron bang times, estimated from neutron time-of-flight (nTOF) measurements, coincide with peak x-ray production. Furthermore, plans to improvemore » and expand the Z neutron diagnostic suite include neutron burn-history diagnostics, increased sensitivity and higher precision nTOF detectors, and neutron recoil-based yield and spectral measurements.« less

  15. Fusion-neutron measurements for magnetized liner inertial fusion experiments on the Z accelerator

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

    Hahn, K. D.; Chandler, G. A.; Ruiz, C. L.

    Several magnetized liner inertial fusion (MagLIF) experiments have been conducted on the Z accelerator at Sandia National Laboratories since late 2013. Measurements of the primary DD (2.45 MeV) neutrons for these experiments suggest that the neutron production is thermonuclear. Primary DD yields up to 3e12 with ion temperatures ~2-3 keV have been achieved. Measurements of the secondary DT (14 MeV) neutrons indicate that the fuel is significantly magnetized. Measurements of down-scattered neutrons from the beryllium liner suggest ρR liner ~ 1g/cm 2. Neutron bang times, estimated from neutron time-of-flight (nTOF) measurements, coincide with peak x-ray production. Furthermore, plans to improvemore » and expand the Z neutron diagnostic suite include neutron burn-history diagnostics, increased sensitivity and higher precision nTOF detectors, and neutron recoil-based yield and spectral measurements.« less

  16. Optical measurements of flyer plate acceleration by emulsion explosive

    NASA Astrophysics Data System (ADS)

    Kubota, Shiro; Shimada, Hideki; Matsui, Kikuo; Ogata, Yuji; Seto, Masahiro; Masui, Akira; Wada, Yuji; Liu, Zhi-Yue; Itoh, Shigeru

    2001-04-01

    This paper presents the study on the application of explosive welding technique to the field of the urgent repair of the gas and water pipe networks. The essential parameters related to the explosive welding are scrutinized from the point of view of the minimizing the damage to the steel pipe after welded explosively with a flyer plate. The emulsion explosive is contained in a rectangular hard-paper box whose bottom is the flyer plate with 100 mm length, 25 mm width and 1.5 mm thickness. The flyer motions of the flyer plates accelerated by emulsion explosive are observed by high-speed photography from the side and front view of the flyer plate. The damage to the pipe by the flyer plate is discussed with the results of the observation of flyer motion and explosive welding test under various experimental conditions. Moreover, one way to control the motion of the flyer plate is proposed. We put a PMMA buffer block into the explosive. The flying process of flyer plate is calculated by the finite different scheme based on the ALE method. The effectiveness of this method is demonstrated by the experimental and numerical studies.

  17. Intercomparison of photon dose measurements at the 8 MeV electron accelerator

    NASA Astrophysics Data System (ADS)

    Angelescu, T.; Ghiordănescu, N.; Băl ţă ţeanu, N.; Labău, V.; Vasilescu, A.

    1997-02-01

    Measurements of dose with thermoluminescent detectors (TLD) and an ionisation chamber were performed in the range of 5-70 Gy in the electron bremsstrahlung field with a maximum energy of 8 MeV of the Bucharest linear accelerator. Previous calibration was done with a 60Co source. The results of the intercomparison were used in dosimetry of the n - γ field of the ΣΣ irradiation facility, with a photon spectrum similar to the 8 MeV bremsstrahlung field [T. Angelescu et al., Nucl. Instr. and Meth. A 378 (1996) 594].

  18. Innovative real-time and non-destructive method of beam profile measurement under large beam current irradiation for BNCT

    NASA Astrophysics Data System (ADS)

    Takada, M.; Kamada, S.; Suda, M.; Fujii, R.; Nakamura, M.; Hoshi, M.; Sato, H.; Endo, S.; Hamano, T.; Arai, S.; Higashimata, A.

    2012-10-01

    We developed a real-time and non-destructive method of beam profile measurement on a target under large beam current irradiation, and without any complex radiation detectors or electrical circuits. We measured the beam profiles on a target by observing the target temperature using an infrared-radiation thermometer camera. The target temperatures were increased and decreased quickly by starting and stopping the beam irradiation within 1 s in response speed. Our method could trace beam movements rapidly. The beam size and position were calibrated by measuring O-ring heat on the target. Our method has the potential to measure beam profiles at beam current over 1 mA for proton and deuteron with the energy around 3 MeV and allows accelerator operators to adjust the beam location during beam irradiation experiments without decreasing the beam current.

  19. FPGA Acceleration of the phylogenetic likelihood function for Bayesian MCMC inference methods.

    PubMed

    Zierke, Stephanie; Bakos, Jason D

    2010-04-12

    Likelihood (ML)-based phylogenetic inference has become a popular method for estimating the evolutionary relationships among species based on genomic sequence data. This method is used in applications such as RAxML, GARLI, MrBayes, PAML, and PAUP. The Phylogenetic Likelihood Function (PLF) is an important kernel computation for this method. The PLF consists of a loop with no conditional behavior or dependencies between iterations. As such it contains a high potential for exploiting parallelism using micro-architectural techniques. In this paper, we describe a technique for mapping the PLF and supporting logic onto a Field Programmable Gate Array (FPGA)-based co-processor. By leveraging the FPGA's on-chip DSP modules and the high-bandwidth local memory attached to the FPGA, the resultant co-processor can accelerate ML-based methods and outperform state-of-the-art multi-core processors. We use the MrBayes 3 tool as a framework for designing our co-processor. For large datasets, we estimate that our accelerated MrBayes, if run on a current-generation FPGA, achieves a 10x speedup relative to software running on a state-of-the-art server-class microprocessor. The FPGA-based implementation achieves its performance by deeply pipelining the likelihood computations, performing multiple floating-point operations in parallel, and through a natural log approximation that is chosen specifically to leverage a deeply pipelined custom architecture. Heterogeneous computing, which combines general-purpose processors with special-purpose co-processors such as FPGAs and GPUs, is a promising approach for high-performance phylogeny inference as shown by the growing body of literature in this field. FPGAs in particular are well-suited for this task because of their low power consumption as compared to many-core processors and Graphics Processor Units (GPUs).

  20. In Situ, Time-Resolved Accelerator Grid Erosion Measurements in the NSTAR 8000 Hour Ion Engine Wear Test

    NASA Technical Reports Server (NTRS)

    Sovey, J.

    1997-01-01

    Time-resolved, in situ measurements of the charge exchange ion erosion pattern on the downstream face of the accelerator grid have been made during an ongoin wear test of the NSTAR 30 cm ion thruster.

  1. Particle Accelerator Focus Automation

    NASA Astrophysics Data System (ADS)

    Lopes, José; Rocha, Jorge; Redondo, Luís; Cruz, João

    2017-08-01

    The Laboratório de Aceleradores e Tecnologias de Radiação (LATR) at the Campus Tecnológico e Nuclear, of Instituto Superior Técnico (IST) has a horizontal electrostatic particle accelerator based on the Van de Graaff machine which is used for research in the area of material characterization. This machine produces alfa (He+) and proton (H+) beams of some μA currents up to 2 MeV/q energies. Beam focusing is obtained using a cylindrical lens of the Einzel type, assembled near the high voltage terminal. This paper describes the developed system that automatically focuses the ion beam, using a personal computer running the LabVIEW software, a multifunction input/output board and signal conditioning circuits. The focusing procedure consists of a scanning method to find the lens bias voltage which maximizes the beam current measured on a beam stopper target, which is used as feedback for the scanning cycle. This system, as part of a wider start up and shut down automation system built for this particle accelerator, brings great advantages to the operation of the accelerator by turning it faster and easier to operate, requiring less human presence, and adding the possibility of total remote control in safe conditions.

  2. Advanced Accelerators: Particle, Photon and Plasma Wave Interactions

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

    Williams, Ronald L.

    2017-06-29

    The overall objective of this project was to study the acceleration of electrons to very high energies over very short distances based on trapping slowly moving electrons in the fast moving potential wells of large amplitude plasma waves, which have relativistic phase velocities. These relativistic plasma waves, or wakefields, are the basis of table-top accelerators that have been shown to accelerate electrons to the same high energies as kilometer-length linear particle colliders operating using traditional decades-old acceleration techniques. The accelerating electrostatic fields of the relativistic plasma wave accelerators can be as large as GigaVolts/meter, and our goal was to studymore » techniques for remotely measuring these large fields by injecting low energy probe electron beams across the plasma wave and measuring the beam’s deflection. Our method of study was via computer simulations, and these results suggested that the deflection of the probe electron beam was directly proportional to the amplitude of the plasma wave. This is the basis of a proposed diagnostic technique, and numerous studies were performed to determine the effects of changing the electron beam, plasma wave and laser beam parameters. Further simulation studies included copropagating laser beams with the relativistic plasma waves. New interesting results came out of these studies including the prediction that very small scale electron beam bunching occurs, and an anomalous line focusing of the electron beam occurs under certain conditions. These studies were summarized in the dissertation of a graduate student who obtained the Ph.D. in physics. This past research program has motivated ideas for further research to corroborate these results using particle-in-cell simulation tools which will help design a test-of-concept experiment in our laboratory and a scaled up version for testing at a major wakefield accelerator facility.« less

  3. Accelerated weight histogram method for exploring free energy landscapes

    NASA Astrophysics Data System (ADS)

    Lindahl, V.; Lidmar, J.; Hess, B.

    2014-07-01

    Calculating free energies is an important and notoriously difficult task for molecular simulations. The rapid increase in computational power has made it possible to probe increasingly complex systems, yet extracting accurate free energies from these simulations remains a major challenge. Fully exploring the free energy landscape of, say, a biological macromolecule typically requires sampling large conformational changes and slow transitions. Often, the only feasible way to study such a system is to simulate it using an enhanced sampling method. The accelerated weight histogram (AWH) method is a new, efficient extended ensemble sampling technique which adaptively biases the simulation to promote exploration of the free energy landscape. The AWH method uses a probability weight histogram which allows for efficient free energy updates and results in an easy discretization procedure. A major advantage of the method is its general formulation, making it a powerful platform for developing further extensions and analyzing its relation to already existing methods. Here, we demonstrate its efficiency and general applicability by calculating the potential of mean force along a reaction coordinate for both a single dimension and multiple dimensions. We make use of a non-uniform, free energy dependent target distribution in reaction coordinate space so that computational efforts are not wasted on physically irrelevant regions. We present numerical results for molecular dynamics simulations of lithium acetate in solution and chignolin, a 10-residue long peptide that folds into a β-hairpin. We further present practical guidelines for setting up and running an AWH simulation.

  4. Accelerated weight histogram method for exploring free energy landscapes.

    PubMed

    Lindahl, V; Lidmar, J; Hess, B

    2014-07-28

    Calculating free energies is an important and notoriously difficult task for molecular simulations. The rapid increase in computational power has made it possible to probe increasingly complex systems, yet extracting accurate free energies from these simulations remains a major challenge. Fully exploring the free energy landscape of, say, a biological macromolecule typically requires sampling large conformational changes and slow transitions. Often, the only feasible way to study such a system is to simulate it using an enhanced sampling method. The accelerated weight histogram (AWH) method is a new, efficient extended ensemble sampling technique which adaptively biases the simulation to promote exploration of the free energy landscape. The AWH method uses a probability weight histogram which allows for efficient free energy updates and results in an easy discretization procedure. A major advantage of the method is its general formulation, making it a powerful platform for developing further extensions and analyzing its relation to already existing methods. Here, we demonstrate its efficiency and general applicability by calculating the potential of mean force along a reaction coordinate for both a single dimension and multiple dimensions. We make use of a non-uniform, free energy dependent target distribution in reaction coordinate space so that computational efforts are not wasted on physically irrelevant regions. We present numerical results for molecular dynamics simulations of lithium acetate in solution and chignolin, a 10-residue long peptide that folds into a β-hairpin. We further present practical guidelines for setting up and running an AWH simulation.

  5. Two-stage light-gas magnetoplasma accelerator for hypervelocity impact simulation

    NASA Astrophysics Data System (ADS)

    Khramtsov, P. P.; Vasetskij, V. A.; Makhnach, A. I.; Grishenko, V. M.; Chernik, M. Yu; Shikh, I. A.; Doroshko, M. V.

    2016-11-01

    The development of macroparticles acceleration methods for high-speed impact simulation in a laboratory is an actual problem due to increasing of space flights duration and necessity of providing adequate spacecraft protection against micrometeoroid and space debris impacts. This paper presents results of experimental study of a two-stage light- gas magnetoplasma launcher for acceleration of a macroparticle, in which a coaxial plasma accelerator creates a shock wave in a high-pressure channel filled with light gas. Graphite and steel spheres with diameter of 2.5-4 mm were used as a projectile and were accelerated to the speed of 0.8-4.8 km/s. A launching of particle occurred in vacuum. For projectile velocity control the speed measuring method was developed. The error of this metod does not exceed 5%. The process of projectile flight from the barrel and the process of a particle collision with a target were registered by use of high-speed camera. The results of projectile collision with elements of meteoroid shielding are presented. In order to increase the projectile velocity, the high-pressure channel should be filled with hydrogen. However, we used helium in our experiments for safety reasons. Therefore, we can expect that the range of mass and velocity of the accelerated particles can be extended by use of hydrogen as an accelerating gas.

  6. Modelling Schumann resonances from ELF measurements using non-linear optimization methods

    NASA Astrophysics Data System (ADS)

    Castro, Francisco; Toledo-Redondo, Sergio; Fornieles, Jesús; Salinas, Alfonso; Portí, Jorge; Navarro, Enrique; Sierra, Pablo

    2017-04-01

    Schumann resonances (SR) can be found in planetary atmospheres, inside the cavity formed by the conducting surface of the planet and the lower ionosphere. They are a powerful tool to investigate both the electric processes that occur in the atmosphere and the characteristics of the surface and the lower ionosphere. In this study, the measurements are obtained in the ELF (Extremely Low Frequency) Juan Antonio Morente station located in the national park of Sierra Nevada. The three first modes, contained in the frequency band between 6 to 25 Hz, will be considered. For each time series recorded by the station, the amplitude spectrum was estimated by using Bartlett averaging. Then, the central frequencies and amplitudes of the SRs were obtained by fitting the spectrum with non-linear functions. In the poster, a study of nonlinear unconstrained optimization methods applied to the estimation of the Schumann Resonances will be presented. Non-linear fit, also known as optimization process, is the procedure followed in obtaining Schumann Resonances from the natural electromagnetic noise. The optimization methods that have been analysed are: Levenberg-Marquardt, Conjugate Gradient, Gradient, Newton and Quasi-Newton. The functions that the different methods fit to data are three lorentzian curves plus a straight line. Gaussian curves have also been considered. The conclusions of this study are outlined in the following paragraphs: i) Natural electromagnetic noise is better fitted using Lorentzian functions; ii) the measurement bandwidth can accelerate the convergence of the optimization method; iii) Gradient method has less convergence and has a highest mean squared error (MSE) between measurement and the fitted function, whereas Levenberg-Marquad, Gradient conjugate method and Cuasi-Newton method give similar results (Newton method presents higher MSE); v) There are differences in the MSE between the parameters that define the fit function, and an interval from 1% to 5% has

  7. Comparison of measured electron energy spectra for six matched, radiotherapy accelerators.

    PubMed

    McLaughlin, David J; Hogstrom, Kenneth R; Neck, Daniel W; Gibbons, John P

    2018-05-01

    This study compares energy spectra of the multiple electron beams of individual radiotherapy machines, as well as the sets of spectra across multiple matched machines. Also, energy spectrum metrics are compared with central-axis percent depth-dose (PDD) metrics. A lightweight, permanent magnet spectrometer was used to measure energy spectra for seven electron beams (7-20 MeV) on six matched Elekta Infinity accelerators with the MLCi2 treatment head. PDD measurements in the distal falloff region provided R 50 and R 80-20 metrics in Plastic Water ® , which correlated with energy spectrum metrics, peak mean energy (PME) and full-width at half maximum (FWHM). Visual inspection of energy spectra and their metrics showed whether beams on single machines were properly tuned, i.e., FWHM is expected to increase and peak height decrease monotonically with increased PME. Also, PME spacings are expected to be approximately equal for 7-13 MeV beams (0.5-cm R 90 spacing) and for 13-16 MeV beams (1.0-cm R 90 spacing). Most machines failed these expectations, presumably due to tolerances for initial beam matching (0.05 cm in R 90 ; 0.10 cm in R 80-20 ) and ongoing quality assurance (0.2 cm in R 50 ). Also, comparison of energy spectra or metrics for a single beam energy (six machines) showed outlying spectra. These variations in energy spectra provided ample data spread for correlating PME and FWHM with PDD metrics. Least-squares fits showed that R 50 and R 80-20 varied linearly and supralinearly with PME, respectively; however, both suggested a secondary dependence on FWHM. Hence, PME and FWHM could serve as surrogates for R 50 and R 80-20 for beam tuning by the accelerator engineer, possibly being more sensitive (e.g., 0.1 cm in R 80-20 corresponded to 2.0 MeV in FWHM). Results of this study suggest a lightweight, permanent magnet spectrometer could be a useful beam-tuning instrument for the accelerator engineer to (a) match electron beams prior to beam commissioning

  8. A broadband fast multipole accelerated boundary element method for the three dimensional Helmholtz equation.

    PubMed

    Gumerov, Nail A; Duraiswami, Ramani

    2009-01-01

    The development of a fast multipole method (FMM) accelerated iterative solution of the boundary element method (BEM) for the Helmholtz equations in three dimensions is described. The FMM for the Helmholtz equation is significantly different for problems with low and high kD (where k is the wavenumber and D the domain size), and for large problems the method must be switched between levels of the hierarchy. The BEM requires several approximate computations (numerical quadrature, approximations of the boundary shapes using elements), and these errors must be balanced against approximations introduced by the FMM and the convergence criterion for iterative solution. These different errors must all be chosen in a way that, on the one hand, excess work is not done and, on the other, that the error achieved by the overall computation is acceptable. Details of translation operators for low and high kD, choice of representations, and BEM quadrature schemes, all consistent with these approximations, are described. A novel preconditioner using a low accuracy FMM accelerated solver as a right preconditioner is also described. Results of the developed solvers for large boundary value problems with 0.0001 less, similarkD less, similar500 are presented and shown to perform close to theoretical expectations.

  9. Acceleration of charged particles by crossed cyclotron waves, Resonant Moments Method

    NASA Astrophysics Data System (ADS)

    Ponomarjov, M.; Carati, D.

    A mechanism for enhanced acceleration of charged particles in crossing radio frequency or micro waves propagating at different angles with respect to an external magnetic field is investigated. This mechanism consists in introducing low amplitude secondary waves in order to improve the parallel momentum transfer from the high amplitude primary wave to charged particles. The use of two parallel counter-propagating waves has recently been considered (Gell and Nakach, 1999) and numerical tests (Louies et al, 2001) have shown that the two-wave scheme may lead to higher averaged parallel velocity. On the other hand, it has been concluded that it may be more effective to accelerate electrons when the waves propagate obliquely to the external magnetic field (Karimabadi and Angelopoulos 1989, Cohen et al 1991). The idea considered here is similar although no constraint is imposed on the refraction indices of the primary and the secondary waves. The theoretical analysis of the acceleration mechanism is based on the Resonance Moments Method (RMM) in which moments of the velocity distribution are computed by using an averages over the resonant layers (RL)i only instead of a complete phase-space average. The quantities obtained using this approach, referred to as Resonant Moments (RM), suggest the existence of optimal angles of propagation for the primary and secondary waves as long as the maximization of the parallel flux of charged particles is considered. The fraction of charged particles that are close to the resonance conditions, that correspond to the RL, becomes then as important as the time these particles remain resonant. The secondary wave tends to maintain a pseudo-equilibrium velocity distribution by continuously re-filling the RL. Our suggestions are confirmed by direct numerical simulations for a populations of 105 relativistic electrons. The secondary wave yields a clear increase (up to one order of magnitude) of the average parallel velocity of the particles

  10. Proton acceleration measurements using fs laser irradiation of foils in the target normal sheath acceleration regime

    NASA Astrophysics Data System (ADS)

    Batani, D.; Boutoux, G.; Burgy, F.; Jakubowska, K.; Ducret, J. E.

    2018-05-01

    We present experimental results obtained at the CELIA laboratory using the laser ECLIPSE to study proton acceleration from ultra-intense laser pulses. Several types of targets were irradiated with different laser conditions (focusing and prepulse level). Proton emission was characterized using time-of-flight detectors (SiC and diamond) and a Thomson parabola spectrometer. In all cases, the maximum energy of observed protons was of the order of 260 keV with a large energy spectrum. Such characteristics are typical of protons emitted following the target normal sheath acceleration mechanism for low-energy short-pulse lasers like ECLIPSE.

  11. Acceleration Noise Measurements for LISA

    NASA Astrophysics Data System (ADS)

    Schlamminger, Stephan; Gundlach, Jens

    2005-04-01

    The close spacing between the proof mass and the housing in the LISA (Laser Interferometer Space Antenna) spacecraft has been a concern as there may be spurious feeble forces. Such forces may limit the performance of the gravity wave detector at frequencies below 3 mHz and must be studied experimentally. We are performing ultra sensitive torsion balance tests to investigate such effects. Our torsion pendulum and a nearby plate are designed to simulate the LISA proof mass with its adjacent housing surface. We study torque noise on the pendulum as a function of separation between the surfaces. In order to exceed the LISA requirement we are probing the acceleration noise at much closer separations, than those planned for LISA. We have taken data at separations as small as 0.15 mm.

  12. Stability analysis of multigrid acceleration methods for the solution of partial differential equations

    NASA Technical Reports Server (NTRS)

    Fay, John F.

    1990-01-01

    A calculation is made of the stability of various relaxation schemes for the numerical solution of partial differential equations. A multigrid acceleration method is introduced, and its effects on stability are explored. A detailed stability analysis of a simple case is carried out and verified by numerical experiment. It is shown that the use of multigrids can speed convergence by several orders of magnitude without adversely affecting stability.

  13. Laser interferometry method for absolute measurement of the acceleration of gravity

    NASA Technical Reports Server (NTRS)

    Hudson, O. K.

    1971-01-01

    Gravimeter permits more accurate and precise absolute measurement of g without reference to Potsdam values as absolute standards. Device is basically Michelson laser beam interferometer in which one arm is mass fitted with corner cube reflector.

  14. Comparison of trunk acceleration ratios during stair negotiation in old-old females.

    PubMed

    Shin, Sun-Shil; Yoo, Won-Gyu

    2016-06-01

    [Purpose] This study compared trunk acceleration ratios in old-old adult females during stair negotiation. [Subjects and Methods] Twelve old-old adult females who could walk independently volunteered for this study. This study measured gait time and trunk acceleration ratios using an accelerometer during ascending and descending stairs [Results] The trunk acceleration ratio when descending stairs was significantly higher than that when ascending stairs. [Conclusion] These findings suggest that old-old females have greater deterioration of upper trunk control function for descending than for ascending stairs, regardless of task time. In addition, the trunk acceleration ratio during stair negotiation is a useful clinical marker to predict function and balance control ability in old-old females.

  15. Comparison of accelerated and conventional corneal collagen cross-linking for progressive keratoconus.

    PubMed

    Cınar, Yasin; Cingü, Abdullah Kürşat; Türkcü, Fatih Mehmet; Çınar, Tuba; Yüksel, Harun; Özkurt, Zeynep Gürsel; Çaça, Ihsan

    2014-09-01

    To compare outcomes of accelerated and conventional corneal cross-linking (CXL) for progressive keratoconus (KC). Patients were divided into two groups as the accelerated CXL group and the conventional CXL group. The uncorrected distant visual acuity (UDVA), corrected distant visual acuity (CDVA), refraction and keratometric values were measured preoperatively and postoperatively. The data of the two groups were compared statistically. The mean UDVA and CDVA were better at the six month postoperative when compared with preoperative values in two groups. While change in UDVA and CDVA was statistically significant in the accelerated CXL group (p = 0.035 and p = 0.047, respectively), it did not reach statistical significance in the conventional CXL group (p = 0.184 and p = 0.113, respectively). The decrease in the mean corneal power (Km) and maximum keratometric value (Kmax) were statistically significant in both groups (p = 0.012 and 0.046, respectively in the accelerated CXL group, p = 0.012 and 0.041, respectively, in the conventional CXL group). There was no statistically significant difference in visual and refractive results between the two groups (p > 0.05). Refractive and visual results of the accelerated CXL method and the conventional CXL method for the treatment of KC in short time period were similar. The accelerated CXL method faster and provide high throughput of the patients.

  16. Sensor fusion for structural tilt estimation using an acceleration-based tilt sensor and a gyroscope

    NASA Astrophysics Data System (ADS)

    Liu, Cheng; Park, Jong-Woong; Spencer, B. F., Jr.; Moon, Do-Soo; Fan, Jiansheng

    2017-10-01

    A tilt sensor can provide useful information regarding the health of structural systems. Most existing tilt sensors are gravity/acceleration based and can provide accurate measurements of static responses. However, for dynamic tilt, acceleration can dramatically affect the measured responses due to crosstalk. Thus, dynamic tilt measurement is still a challenging problem. One option is to integrate the output of a gyroscope sensor, which measures the angular velocity, to obtain the tilt; however, problems arise because the low-frequency sensitivity of the gyroscope is poor. This paper proposes a new approach to dynamic tilt measurements, fusing together information from a MEMS-based gyroscope and an acceleration-based tilt sensor. The gyroscope provides good estimates of the tilt at higher frequencies, whereas the acceleration measurements are used to estimate the tilt at lower frequencies. The Tikhonov regularization approach is employed to fuse these measurements together and overcome the ill-posed nature of the problem. The solution is carried out in the frequency domain and then implemented in the time domain using FIR filters to ensure stability. The proposed method is validated numerically and experimentally to show that it performs well in estimating both the pseudo-static and dynamic tilt measurements.

  17. Beam-based measurements of long-range transverse wakefields in the Compact Linear Collider main-linac accelerating structure

    DOE PAGES

    Zha, Hao; Latina, Andrea; Grudiev, Alexej; ...

    2016-01-20

    The baseline design of CLIC (Compact Linear Collider) uses X-band accelerating structures for its main linacs. In order to maintain beam stability in multibunch operation, long-range transverse wakefields must be suppressed by 2 orders of magnitude between successive bunches, which are separated in time by 0.5 ns. Such strong wakefield suppression is achieved by equipping every accelerating structure cell with four damping waveguides terminated with individual rf loads. A beam-based experiment to directly measure the effectiveness of this long-range transverse wakefield and benchmark simulations was made in the FACET test facility at SLAC using a prototype CLIC accelerating structure. Furthermore,more » the experiment showed good agreement with the simulations and a strong suppression of the wakefields with an unprecedented minimum resolution of 0.1 V/(pC mm m).« less

  18. Measurement of performance using acceleration control and pulse control in simulated spacecraft docking operations

    NASA Technical Reports Server (NTRS)

    Brody, Adam R.; Ellis, Stephen R.

    1992-01-01

    Nine commercial airline pilots served as test subjects in a study to compare acceleration control with pulse control in simulated spacecraft maneuvers. Simulated remote dockings of an orbital maneuvering vehicle (OMV) to a space station were initiated from 50, 100, and 150 meters along the station's -V-bar (minus velocity vector). All unsuccessful missions were reflown. Five way mixed analysis of variance (ANOVA) with one between factor, first mode, and four within factors (mode, bloch, range, and trial) were performed on the data. Recorded performance measures included mission duration and fuel consumption along each of the three coordinate axes. Mission duration was lower with pulse mode, while delta V (fuel consumption) was lower with acceleration mode. Subjects used more fuel to travel faster with pulse mode than with acceleration mode. Mission duration, delta V, X delta V, Y delta V., and Z delta V all increased with range. Subjects commanded the OMV to 'fly' at faster rates from further distances. These higher average velocities were paid for with increased fuel consumption. Asymmetrical transfer was found in that the mode transitions could not be predicted solely from the mission duration main effect. More testing is advised to understand the manual control aspects of spaceflight maneuvers better.

  19. On some Aitken-like acceleration of the Schwarz method

    NASA Astrophysics Data System (ADS)

    Garbey, M.; Tromeur-Dervout, D.

    2002-12-01

    In this paper we present a family of domain decomposition based on Aitken-like acceleration of the Schwarz method seen as an iterative procedure with a linear rate of convergence. We first present the so-called Aitken-Schwarz procedure for linear differential operators. The solver can be a direct solver when applied to the Helmholtz problem with five-point finite difference scheme on regular grids. We then introduce the Steffensen-Schwarz variant which is an iterative domain decomposition solver that can be applied to linear and nonlinear problems. We show that these solvers have reasonable numerical efficiency compared to classical fast solvers for the Poisson problem or multigrids for more general linear and nonlinear elliptic problems. However, the salient feature of our method is that our algorithm has high tolerance to slow network in the context of distributed parallel computing and is attractive, generally speaking, to use with computer architecture for which performance is limited by the memory bandwidth rather than the flop performance of the CPU. This is nowadays the case for most parallel. computer using the RISC processor architecture. We will illustrate this highly desirable property of our algorithm with large-scale computing experiments.

  20. Development of Acceleration Sensor and Acceleration Evaluation System for Super-Low-Range Frequencies

    NASA Astrophysics Data System (ADS)

    Asano, Shogo; Matsumoto, Hideki

    2001-05-01

    This paper describes the development process for acceleration sensors used on automobiles and an acceleration evaluation system designed specifically for acceleration at super-low-range frequencies. The features of the newly developed sensor are as follows. 1) Original piezo-bimorph design based on a disc-center-fixed structure achieves pyroeffect cancelling and stabilization of sensor characteristics and enables the detection of the acceleration of 0.0009 G at the super-low-range-frequency of 0.03 Hz. 2) The addition of a self-diagnostic function utilizing the characteristics of piezoceramics enables constant monitoring of sensor failure. The frequency range of acceleration for accurate vehicle motion control is considered to be from DC to about 50 Hz. However, the measurement of acceleration in the super-low-range frequency near DC has been difficult because of mechanical and electrical noise interruption. This has delayed the development of the acceleration sensor for automotive use. We have succeeded in the development of an acceleration evaluation system for super-low-range frequencies from 0.015 Hz to 2 Hz with detection of the acceleration range from 0.0002 G (0.2 gal) to 1 G, as well as the development of a piezoelectric-type acceleration sensor for automotive use.

  1. Modeling of Particle Acceleration at Multiple Shocks Via Diffusive Shock Acceleration: Preliminary Results

    NASA Astrophysics Data System (ADS)

    Parker, L. N.; Zank, G. P.

    2013-12-01

    Successful forecasting of energetic particle events in space weather models require algorithms for correctly predicting the spectrum of ions accelerated from a background population of charged particles. We present preliminary results from a model that diffusively accelerates particles at multiple shocks. Our basic approach is related to box models (Protheroe and Stanev, 1998; Moraal and Axford, 1983; Ball and Kirk, 1992; Drury et al., 1999) in which a distribution of particles is diffusively accelerated inside the box while simultaneously experiencing decompression through adiabatic expansion and losses from the convection and diffusion of particles outside the box (Melrose and Pope, 1993; Zank et al., 2000). We adiabatically decompress the accelerated particle distribution between each shock by either the method explored in Melrose and Pope (1993) and Pope and Melrose (1994) or by the approach set forth in Zank et al. (2000) where we solve the transport equation by a method analogous to operator splitting. The second method incorporates the additional loss terms of convection and diffusion and allows for the use of a variable time between shocks. We use a maximum injection energy (Emax) appropriate for quasi-parallel and quasi-perpendicular shocks (Zank et al., 2000, 2006; Dosch and Shalchi, 2010) and provide a preliminary application of the diffusive acceleration of particles by multiple shocks with frequencies appropriate for solar maximum (i.e., a non-Markovian process).

  2. The influence of Unruh effect on quantum steering for accelerated two-level detectors with different measurements

    NASA Astrophysics Data System (ADS)

    Liu, Tonghua; Wang, Jieci; Jing, Jiliang; Fan, Heng

    2018-03-01

    We propose a tight measure of quantum steering and study the dynamics of steering in a relativistic setting via different quantifiers. We present the dynamics of steering between two correlated Unruh-Dewitt detectors when one of them locally interacts with external scalar field. We find that the quantum steering, either measured by the entropic steering inequality or the Cavalcanti-Jones-Wiseman-Reid inequality, is fragile under the influence of Unruh thermal noise. The quantum steering is found always asymmetric and the asymmetry is extremely sensitive to the initial state parameter. In addition, the steering-type quantum correlations experience "sudden death" for some accelerations, which are quite different from the behaviors of other quantum correlations in the same system. It is worth noting that the domination value of the tight quantum steering exists a transformation point with increasing acceleration. We also find that the robustness of quantum steerability under the Unruh thermal noise can be realized by choosing the smallest energy gap in the detectors.

  3. Investigation of using shrinking method in construction of Institute for Research in Fundamental Sciences Electron Linear Accelerator TW-tube (IPM TW-Linac tube)

    NASA Astrophysics Data System (ADS)

    Ghasemi, F.; Abbasi Davani, F.

    2015-06-01

    Due to Iran's growing need for accelerators in various applications, IPM's electron Linac project has been defined. This accelerator is a 15 MeV energy S-band traveling-wave accelerator which is being designed and constructed based on the klystron that has been built in Iran. Based on the design, operating mode is π /2 and the accelerating chamber consists of two 60cm long tubes with constant impedance and a 30cm long buncher. Amongst all construction methods, shrinking method is selected for construction of IPM's electron Linac tube because it has a simple procedure and there is no need for large vacuum or hydrogen furnaces. In this paper, different aspects of this method are investigated. According to the calculations, linear ratio of frequency alteration to radius change is 787.8 MHz/cm, and the maximum deformation at the tube wall where disks and the tube make contact is 2.7μ m. Applying shrinking method for construction of 8- and 24-cavity tubes results in satisfactory frequency and quality factor. Average deviations of cavities frequency of 8- and 24-cavity tubes to the design values are 0.68 MHz and 1.8 MHz respectively before tune and 0.2 MHz and 0.4 MHz after tune. Accelerating tubes, buncher, and high power couplers of IPM's electron linac are constructed using shrinking method.

  4. The effect of acceleration versus displacement methods on steady-state boundary forces

    NASA Technical Reports Server (NTRS)

    Mcghee, D. S.

    1992-01-01

    This study describes the acceleration and displacement methods for use in the recovery of coupled system boundary forces. A simple two degree of freedom system has been used for illustration. The effect of the choice of method for use with indeterminate or over-constrained boundaries has been investigated. It has specifically looked at results from a simple two dimensional beam problem using both methods. Much work has been done on the effect of Craig-Bampton modal truncation system displacements and forces, however, little work has been done on system level modal truncation. The findings of this study indicate that the effect of this system level truncation is significant. This may be particularly true for the 35 Hz system cutoff frequency that is required by the space shuttle. From this study's findings, recommendations for areas of study with space shuttle payload systems are made.

  5. Accelerating gradient improvement using shape-tailor laser front in radiation pressure acceleration progress

    NASA Astrophysics Data System (ADS)

    Wang, W. P.; Shen, B. F.; Xu, Z. Z.

    2017-05-01

    The accelerating gradient of a proton beam is crucial for stable radiation pressure acceleration (RPA) because the multi-dimensional instabilities increase γ times slower in the relativistic region. In this paper, a shape-tailored laser is proposed to significantly accelerate the ions in a controllable high accelerating gradient. In this method, the fastest ions initially rest in the middle of the foil are controlled to catch the compressed electron layer at the end of the hole-boring stage, thus the light-sail stage can start as soon as possible. Then the compressed electron layer is accelerated tightly together with the fastest ions by the shaped laser intensity, which further increases the accelerating gradient in the light-sail stage. Such tailored pulse may be beneficial for the RPA driven by the 10-fs 10 petawatt laser in the future.

  6. Latitudinal variation of speed and mass flux in the acceleration region of the solar wind inferred from spectral broadening measurements

    NASA Technical Reports Server (NTRS)

    Woo, Richard; Goldstein, Richard M.

    1994-01-01

    Spectral broadening measurements conducted at S-band (13-cm wavelength) during solar minimum conditions in the heliocentric distance range of 3-8 R(sub O) by Mariner 4, Pioneer 10, Mariner 10, Helios 1, Helios 2, and Viking have been combined to reveal a factor of 2.6 reduction in bandwidth from equator to pole. Since spectral broadening bandwidth depends on electron density fluctuation and solar wind speed, and latitudinal variation of the former is available from coherence bandwidth measurements, the remote sensing spectral broadening measurements provide the first determination of the latitudinal variation of solar wind speed in the acceleration region. When combined with electron density measurements deduced from white-light coronagraphs, this result also leads to the first determination of the latitudinal variation of mass flux in the acceleration region. From equator to pole, solar wind speed increases by a factor of 2.2, while mass flux decreases by a factor of 2.3. These results are consistent with measurements of solar wind speed by multi-station intensity scintillation measurements, as well as measurements of mass flux inferred from Lyman alpha observations, both of which pertain to the solar wind beyond 0.5 AU. The spectral broadening observations, therefore, strengthen earlier conclusions about the latitudinal variation of solar wind speed and mass flux, and reinforce current solar coronal models and their implications for solar wind acceleration and solar wind modeling.

  7. Measurements of δ11B in water by use of a mass spectrometer with accelerator

    NASA Astrophysics Data System (ADS)

    Di Fusco, Egidio; Rubino, Mauro; Marzaioli, Fabio; Di Rienzo, Brunella; Stellato, Luisa; Ricci, Andreina; Porzio, Giuseppe; D'onofrio, Antonio; Terrasi, Filippo

    2017-12-01

    This study describes the tests carried out to measure the isotopic composition of Boron (B) in water samples by use of the magnetic spectrometer and accelerator of the Center for Isotopic Research on Cultural and Environmental heritage (CIRCE) of Italy. B was extracted from water samples to obtain Boric acid (B(OH)3), which was then analyzed. We quantified the precision of our experimental system and the variability introduced by the chemical extraction measuring chemically untreated and treated pure B(OH)3 samples. We found an instrumental precision around 10‰ (1σ), but, by increasing the number of replicates (>30), we obtained a standard deviation of the mean (σerr) around 3‰ or lower. We also tested whether the chemical extraction caused isotopic fractionation and found a small fractionation (ε = 5 ± 4‰) of treated samples normalized against untreated ones, compatible with zero at 2σ. In order to avoid δ11B biases, we decided to normalize unknown treated samples with treated standards. Finally, we measured δ11B of seawater and groundwater samples to test the analytical method, and obtained values of 30 ± 6‰ and -4 ± 4‰ respectively. We conclude that our experimental system is only suitable when remarkable (>10‰) δ11B differences exist among water samples, but cannot be used to measure natural differences (<10‰) unless the total uncertainty is significantly decreased.

  8. Exploring phase space using smartphone acceleration and rotation sensors simultaneously

    NASA Astrophysics Data System (ADS)

    Monteiro, Martín; Cabeza, Cecilia; Martí, Arturo C.

    2014-07-01

    A paradigmatic physical system as the physical pendulum is experimentally studied using the acceleration and rotation (gyroscope) sensors available on smartphones and other devices such as iPads and tablets. A smartphone is fixed to the outside of a bicycle wheel whose axis is kept horizontal and fixed. The compound system, wheel plus smartphone, defines a physical pendulum which can rotate, giving full turns in one direction, or oscillate about the equilibrium position (performing either small or large oscillations). Measurements of the radial and tangential acceleration and the angular velocity obtained with smartphone sensors allow a deep insight into the dynamics of the system to be gained. In addition, thanks to the simultaneous use of the acceleration and rotation sensors, trajectories in the phase space are directly obtained. The coherence of the measures obtained with the different sensors and by traditional methods is remarkable. Indeed, due to their low cost and increasing availability, smartphone sensors are valuable tools that can be used in most undergraduate laboratories.

  9. ACCELERATION INTEGRATOR

    DOEpatents

    Pope, K.E.

    1958-01-01

    This patent relates to an improved acceleration integrator and more particularly to apparatus of this nature which is gyrostabilized. The device may be used to sense the attainment by an airborne vehicle of a predetermined velocitv or distance along a given vector path. In its broad aspects, the acceleration integrator utilizes a magnetized element rotatable driven by a synchronous motor and having a cylin drical flux gap and a restrained eddy- current drag cap deposed to move into the gap. The angular velocity imparted to the rotatable cap shaft is transmitted in a positive manner to the magnetized element through a servo feedback loop. The resultant angular velocity of tae cap is proportional to the acceleration of the housing in this manner and means may be used to measure the velocity and operate switches at a pre-set magnitude. To make the above-described dcvice sensitive to acceleration in only one direction the magnetized element forms the spinning inertia element of a free gyroscope, and the outer housing functions as a gimbal of a gyroscope.

  10. Demonstration of a positron beam-driven hollow channel plasma wakefield accelerator

    NASA Astrophysics Data System (ADS)

    Gessner, Spencer; Adli, Erik; Allen, James M.; An, Weiming; Clarke, Christine I.; Clayton, Chris E.; Corde, Sebastien; Delahaye, J. P.; Frederico, Joel; Green, Selina Z.; Hast, Carsten; Hogan, Mark J.; Joshi, Chan; Lindstrøm, Carl A.; Lipkowitz, Nate; Litos, Michael; Lu, Wei; Marsh, Kenneth A.; Mori, Warren B.; O'Shea, Brendan; Vafaei-Najafabadi, Navid; Walz, Dieter; Yakimenko, Vitaly; Yocky, Gerald

    2016-06-01

    Plasma wakefield accelerators have been used to accelerate electron and positron particle beams with gradients that are orders of magnitude larger than those achieved in conventional accelerators. In addition to being accelerated by the plasma wakefield, the beam particles also experience strong transverse forces that may disrupt the beam quality. Hollow plasma channels have been proposed as a technique for generating accelerating fields without transverse forces. Here we demonstrate a method for creating an extended hollow plasma channel and measure the wakefields created by an ultrarelativistic positron beam as it propagates through the channel. The plasma channel is created by directing a high-intensity laser pulse with a spatially modulated profile into lithium vapour, which results in an annular region of ionization. A peak decelerating field of 230 MeV m-1 is inferred from changes in the beam energy spectrum, in good agreement with theory and particle-in-cell simulations.

  11. Modeling of Particle Acceleration at Multiple Shocks Via Diffusive Shock Acceleration: Preliminary Results

    NASA Technical Reports Server (NTRS)

    Parker, Linda Neergaard; Zank, Gary P.

    2013-01-01

    We present preliminary results from a model that diffusively accelerates particles at multiple shocks. Our basic approach is related to box models (Protheroe and Stanev, 1998; Moraal and Axford, 1983; Ball and Kirk, 1992; Drury et al., 1999) in which a distribution of particles is diffusively accelerated inside the box while simultaneously experiencing decompression through adiabatic expansion and losses from the convection and diffusion of particles outside the box (Melrose and Pope, 1993; Zank et al., 2000). We adiabatically decompress the accelerated particle distribution between each shock by either the method explored in Melrose and Pope (1993) and Pope and Melrose (1994) or by the approach set forth in Zank et al. (2000) where we solve the transport equation by a method analogous to operator splitting. The second method incorporates the additional loss terms of convection and diffusion and allows for the use of a variable time between shocks. We use a maximum injection energy (Emax) appropriate for quasi-parallel and quasi-perpendicular shocks (Zank et al., 2000, 2006; Dosch and Shalchi, 2010) and provide a preliminary application of the diffusive acceleration of particles by multiple shocks with frequencies appropriate for solar maximum (i.e., a non-Markovian process).

  12. Accelerated molecular dynamics: A promising and efficient simulation method for biomolecules

    NASA Astrophysics Data System (ADS)

    Hamelberg, Donald; Mongan, John; McCammon, J. Andrew

    2004-06-01

    Many interesting dynamic properties of biological molecules cannot be simulated directly using molecular dynamics because of nanosecond time scale limitations. These systems are trapped in potential energy minima with high free energy barriers for large numbers of computational steps. The dynamic evolution of many molecular systems occurs through a series of rare events as the system moves from one potential energy basin to another. Therefore, we have proposed a robust bias potential function that can be used in an efficient accelerated molecular dynamics approach to simulate the transition of high energy barriers without any advance knowledge of the location of either the potential energy wells or saddle points. In this method, the potential energy landscape is altered by adding a bias potential to the true potential such that the escape rates from potential wells are enhanced, which accelerates and extends the time scale in molecular dynamics simulations. Our definition of the bias potential echoes the underlying shape of the potential energy landscape on the modified surface, thus allowing for the potential energy minima to be well defined, and hence properly sampled during the simulation. We have shown that our approach, which can be extended to biomolecules, samples the conformational space more efficiently than normal molecular dynamics simulations, and converges to the correct canonical distribution.

  13. Acceleration Modes and Transitions in Pulsed Plasma Accelerators

    NASA Technical Reports Server (NTRS)

    Polzin, Kurt A.; Greve, Christine M.

    2018-01-01

    accelerators was developed by Cheng, et al. The Coaxial High ENerGy (CHENG) thruster operated on the 10-microseconds timescales of pulsed plasma thrusters, but claimed high thrust density, high efficiency and low electrode erosion rates, which are more consistent with the deflagration mode of acceleration. Separate work on gas-fed pulsed plasma thrusters (PPTs) by Ziemer, et al. identified two separate regimes of performance. The regime at higher mass bits (termed Mode I in that work) possessed relatively constant thrust efficiency (ratio of jet kinetic energy to input electrical energy) as a function of mass bit. In the second regime at very low mass bits (termed Mode II), the efficiency increased with decreasing mass bit. Work by Poehlmann et al. and by Sitaraman and Raja sought to understand the performance of the CHENG thruster and the Mode I / Mode II performance in PPTs by modeling the acceleration using the Hugoniot Relation, with the detonation and deflagration modes representing two distinct sets of solutions to the relevant conservation laws. These works studied the proposal that, depending upon the values of the various controllable parameters, the accelerator would operate in either the detonation or deflagration mode. In the present work, we propose a variation on the explanation for the differences in performance between the various pulsed plasma accelerators. Instead of treating the accelerator as if it were only operating in one mode or the other during a pulse, we model the initial stage of the discharge in all cases as an accelerating current sheet (detonation mode). If the current sheet reaches the exit of the accelerator before the discharge is completed, the acceleration mode transitions to the deflagration mode type found in the quasi-steady MPD thrusters. This modeling method is used to demonstrate that standard gas-fed pulsed plasma accelerators, the CHENG thruster, and the quasi-steady MPD accelerator are variations of the same device, with the overall

  14. Pulsed electromagnetic gas acceleration

    NASA Technical Reports Server (NTRS)

    Jahn, R. G.; Vonjaskowsky, W. F.; Clark, K. E.

    1974-01-01

    Detailed measurements of the axial velocity profile and electromagnetic structure of a high power, quasi-steady MPD discharge are used to formulate a gasdynamic model of the acceleration process. Conceptually dividing the accelerated plasma into an inner flow and an outer flow, it is found that more than two-thirds of the total power in the plasma is deposited in the inner flow, accelerating it to an exhaust velocity of 12.5 km/sec. The outer flow, which is accelerated to a velocity of only 6.2 km/sec, appears to provide a current conduction path between the inner flow and the anode. Related cathode studies have shown that the critical current for the onset of terminal voltage fluctuations, which was recently shown to be a function of the cathode area, appears to reach an asymptote for cathodes of very large surface area. Detailed floating potential measurements show that the fluctuations are confined to the vicinity of the cathode and hence reflect a cathode emission process rather than a fundamental limit on MPD performance.

  15. Staging of RF-accelerating Units in a MEMS-based Ion Accelerator

    NASA Astrophysics Data System (ADS)

    Persaud, A.; Seidl, P. A.; Ji, Q.; Feinberg, E.; Waldron, W. L.; Schenkel, T.; Ardanuc, S.; Vinayakumar, K. B.; Lal, A.

    Multiple Electrostatic Quadrupole Array Linear Accelerators (MEQALACs) provide an opportunity to realize compact radio- frequency (RF) accelerator structures that can deliver very high beam currents. MEQALACs have been previously realized with acceleration gap distances and beam aperture sizes of the order of centimeters. Through advances in Micro-Electro-Mechanical Systems (MEMS) fabrication, MEQALACs can now be scaled down to the sub-millimeter regime and batch processed on wafer substrates. In this paper we show first results from using three RF stages in a compact MEMS-based ion accelerator. The results presented show proof-of-concept with accelerator structures formed from printed circuit boards using a 3 × 3 beamlet arrangement and noble gas ions at 10 keV. We present a simple model to describe the measured results. We also discuss some of the scaling behaviour of a compact MEQALAC. The MEMS-based approach enables a low-cost, highly versatile accelerator covering a wide range of currents (10 μA to 100 mA) and beam energies (100 keV to several MeV). Applications include ion-beam analysis, mass spectrometry, materials processing, and at very high beam powers, plasma heating.

  16. Staging of RF-accelerating Units in a MEMS-based Ion Accelerator

    DOE PAGES

    Persaud, A.; Seidl, P. A.; Ji, Q.; ...

    2017-10-26

    Multiple Electrostatic Quadrupole Array Linear Accelerators (MEQALACs) provide an opportunity to realize compact radio- frequency (RF) accelerator structures that can deliver very high beam currents. MEQALACs have been previously realized with acceleration gap distances and beam aperture sizes of the order of centimeters. Through advances in Micro-Electro-Mechanical Systems (MEMS) fabrication, MEQALACs can now be scaled down to the sub-millimeter regime and batch processed on wafer substrates. In this paper we show first results from using three RF stages in a compact MEMS-based ion accelerator. The results presented show proof-of-concept with accelerator structures formed from printed circuit boards using a 3more » × 3 beamlet arrangement and noble gas ions at 10 keV. We present a simple model to describe the measured results. We also discuss some of the scaling behaviour of a compact MEQALAC. The MEMS-based approach enables a low-cost, highly versatile accelerator covering a wide range of currents (10 μA to 100 mA) and beam energies (100 keV to several MeV). Applications include ion-beam analysis, mass spectrometry, materials processing, and at very high beam powers, plasma heating.« less

  17. Staging of RF-accelerating Units in a MEMS-based Ion Accelerator

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

    Persaud, A.; Seidl, P. A.; Ji, Q.

    Multiple Electrostatic Quadrupole Array Linear Accelerators (MEQALACs) provide an opportunity to realize compact radio- frequency (RF) accelerator structures that can deliver very high beam currents. MEQALACs have been previously realized with acceleration gap distances and beam aperture sizes of the order of centimeters. Through advances in Micro-Electro-Mechanical Systems (MEMS) fabrication, MEQALACs can now be scaled down to the sub-millimeter regime and batch processed on wafer substrates. In this paper we show first results from using three RF stages in a compact MEMS-based ion accelerator. The results presented show proof-of-concept with accelerator structures formed from printed circuit boards using a 3more » × 3 beamlet arrangement and noble gas ions at 10 keV. We present a simple model to describe the measured results. We also discuss some of the scaling behaviour of a compact MEQALAC. The MEMS-based approach enables a low-cost, highly versatile accelerator covering a wide range of currents (10 μA to 100 mA) and beam energies (100 keV to several MeV). Applications include ion-beam analysis, mass spectrometry, materials processing, and at very high beam powers, plasma heating.« less

  18. A Novel Permanent Magnetic Angular Acceleration Sensor

    PubMed Central

    Zhao, Hao; Feng, Hao

    2015-01-01

    Angular acceleration is an important parameter for status monitoring and fault diagnosis of rotary machinery. Therefore, we developed a novel permanent magnetic angular acceleration sensor, which is without rotation angle limitations and could directly measure the instantaneous angular acceleration of the rotating system. The sensor rotor only needs to be coaxially connected with the rotating system, which enables convenient sensor installation. For the cup structure of the sensor rotor, it has a relatively small rotational inertia. Due to the unique mechanical structure of the sensor, the output signal of the sensor can be directed without a slip ring, which avoids signal weakening effect. In this paper, the operating principle of the sensor is described, and simulated using finite element method. The sensitivity of the sensor is calibrated by torsional pendulum and angle sensor, yielding an experimental result of about 0.88 mV/(rad·s−2). Finally, the angular acceleration of the actual rotating system has been tested, using both a single-phase asynchronous motor and a step motor. Experimental result confirms the operating principle of the sensor and indicates that the sensor has good practicability. PMID:26151217

  19. Gadolinium-148 and other spallation production cross section measurements for accelerator target facilities

    NASA Astrophysics Data System (ADS)

    Kelley, Karen Corzine

    At the Los Alamos Neutron Science Center accelerator complex, protons are accelerated to 800 MeV and directed to two tungsten targets, Target 4 at the Weapons Neutron Research facility and the 1L target at the Lujan Center. The Department of Energy requires hazard classification analyses to be performed on these targets and places limits on certain radionuclide inventories in the targets to avoid characterizing the facilities as "nuclear facilities." Gadolinium-148 is a radionuclide created from the spallation of tungsten. Allowed isotopic inventories are particularly low for this isotope because it is an alpha-particle emitter with a 75-year half-life. The activity level of Gadolinium-148 is low, but it encompasses almost two-thirds of the total dose burden for the two tungsten targets based on present yield estimates. From a hazard classification standpoint, this severely limits the lifetime of these tungsten targets. The cross section is not well-established experimentally and this is the motivation for measuring the Gadolinium-148 production cross section from tungsten. In a series of experiments at the Weapons Neutron Research facility, Gadolinium-148 production was measured for 600- and 800-MeV protons on tungsten, tantalum, and gold. These experiments used 3 mum thin tungsten, tantalum, and gold foils and 10 mum thin aluminum activation foils. In addition, spallation yields were determined for many short-lived and long-lived spallation products with these foils using gamma and alpha spectroscopy and compared with predictions of the Los Alamos National Laboratory codes CEM2k+GEM2 and MCNPX. The cumulative Gadolinium-148 production cross section measured from tantalum, tungsten, and gold for incident 600-MeV protons were 15.2 +/- 4.0, 8.31 +/- 0.92, and 0.591 +/- 0.155, respectively. The average production cross sections measured at 800 MeV were 28.6 +/- 3.5, 19.4 +/- 1.8, and 3.69 +/- 0.50 for tantalum, tungsten, and gold, respectively. These cumulative

  20. Search for optimal 3D wave launching configurations for the acceleration of charged particles in a magnetized plasma: Resonant Moments Method

    NASA Astrophysics Data System (ADS)

    Ponomarjov, Maxim; Carati, Daniele

    2004-11-01

    Three-dimensional electromagnetic wave configurations are proposed for accelerating charged particles in an external magnetic field. A primary wave responsible for the acceleration is coupled to a secondary wave generating the chaotic motion of the particles. The wave vectors and the magnetic field are not supposed to be co-planar and create a fully three dimensional system. This configuration produces faster acceleration with low amplitude. The idea considered here is similar to Refs. [1-2] although no constraint is imposed on the refraction indices. The theoretical analysis of the acceleration mechanism is based on the Resonance Moments Method (RMM) in which the velocity distribution and its moments are approximated by using an average over the resonant layers (RL)i only instead of a complete phase-space averages. The quantities obtained using this approach, referred to as Resonant Moments (RM), suggest the existence of optimal angles of propagation for the primary and secondary waves as long as the maximization of the parallel flux of charged particles is considered The secondary wave tends to maintain a pseudo-equilibrium velocity distribution by continuously re-filling the RL. Our suggestions are confirmed by direct numerical simulations of particle trajectories. The parameters for these simulations are relevant to magnetic plasma fusion experiments in electron cyclotron resonance heating and electron acceleration in planetary magnetospheres. Although measures of the distributions clearly show a departure from thermal equilibrium, the stochastization effect of the secondary wave yields a clear increase (up to one order of magnitude) of the average parallel velocity of the particles. It is a quite promising result since the amplitude of the secondary wave is ten times lower the one of the first wave. 1 H. Karimabadi and V. Angelopoulos, Phys. Rev. Lett., 62, 2342 (1989). 2 B. I. Cohen, R. H Cohen, W. M. Nevins, and T. D. Rognlien, Rev. Mod. Phys., 63, 949 (1991).

  1. Radiotherapy using a laser proton accelerator

    NASA Astrophysics Data System (ADS)

    Murakami, Masao; Hishikawa, Yoshio; Miyajima, Satoshi; Okazaki, Yoshiko; Sutherland, Kenneth L.; Abe, Mitsuyuki; Bulanov, Sergei V.; Daido, Hiroyuki; Esirkepov, Timur Zh.; Koga, James; Yamagiwa, Mitsuru; Tajima, Toshiki

    2008-06-01

    Laser acceleration promises innovation in particle beam therapy of cancer where an ultra-compact accelerator system for cancer beam therapy can become affordable to a broad range of patients. This is not feasible without the introduction of a technology that is radically different from the conventional accelerator-based approach. Because of its compactness and other novel characteristics, the laser acceleration method provides many enhanced capabilities

  2. Accelerator based epithermal neutron source

    NASA Astrophysics Data System (ADS)

    Taskaev, S. Yu.

    2015-11-01

    We review the current status of the development of accelerator sources of epithermal neutrons for boron neutron capture therapy (BNCT), a promising method of malignant tumor treatment. Particular attention is given to the source of epithermal neutrons on the basis of a new type of charged particle accelerator: tandem accelerator with vacuum insulation and lithium neutron-producing target. It is also shown that the accelerator with specialized targets makes it possible to generate fast and monoenergetic neutrons, resonance and monoenergetic gamma-rays, alpha-particles, and positrons.

  3. Three-dimensional photoacoustic tomography based on graphics-processing-unit-accelerated finite element method.

    PubMed

    Peng, Kuan; He, Ling; Zhu, Ziqiang; Tang, Jingtian; Xiao, Jiaying

    2013-12-01

    Compared with commonly used analytical reconstruction methods, the frequency-domain finite element method (FEM) based approach has proven to be an accurate and flexible algorithm for photoacoustic tomography. However, the FEM-based algorithm is computationally demanding, especially for three-dimensional cases. To enhance the algorithm's efficiency, in this work a parallel computational strategy is implemented in the framework of the FEM-based reconstruction algorithm using a graphic-processing-unit parallel frame named the "compute unified device architecture." A series of simulation experiments is carried out to test the accuracy and accelerating effect of the improved method. The results obtained indicate that the parallel calculation does not change the accuracy of the reconstruction algorithm, while its computational cost is significantly reduced by a factor of 38.9 with a GTX 580 graphics card using the improved method.

  4. Depth Profiles of Mg, Si, and Zn Implants in GaN by Trace Element Accelerator Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Ravi Prasad, G. V.; Pelicon, P.; Mitchell, L. J.; McDaniel, F. D.

    2003-08-01

    GaN is one of the most promising electronic materials for applications requiring high-power, high frequencies, or high-temperatures as well as opto-electronics in the blue to ultraviolet spectral region. We have recently measured depth profiles of Mg, Si, and Zn implants in GaN substrates by the TEAMS particle counting method for both matrix and trace elements, using a gas ionization chamber. Trace Element Accelerator Mass Spectrometry (TEAMS) is a combination of Secondary Ion Mass Spectrometry (SIMS) and Accelerator Mass Spectrometry (AMS) to measure trace elements at ppb levels. Negative ions from a SIMS like source are injected into a tandem accelerator. Molecular interferences inherent with the SIMS method are eliminated in the TEAMS method. Negative ion currents are extremely low with GaN as neither gallium nor nitrogen readily forms negative ions making the depth profile measurements more difficult. The energies of the measured ions are in the range of 4-8 MeV. A careful selection of mass/charge ratios of the detected ions combined with energy-loss behavior of the ions in the ionization chamber eliminated molecular interferences.

  5. Skyshine radiation resulting from 6 MV and 10 MV photon beams from a medical accelerator.

    PubMed

    Elder, Deirdre H; Harmon, Joseph F; Borak, Thomas B

    2010-07-01

    Skyshine radiation scattered in the atmosphere above a radiation therapy accelerator facility can result in measurable dose rates at locations near the facility on the ground and at roof level. A Reuter Stokes RSS-120 pressurized ion chamber was used to measure exposure rates in the vicinity of a Varian Trilogy Linear Accelerator at the Colorado State University Veterinary Medical Center. The linear accelerator was used to deliver bremsstrahlung photons from 6 MeV and 10 MeV electron beams with several combinations of field sizes and gantry angles. An equation for modeling skyshine radiation in the vicinity of medical accelerators was published by the National Council on Radiation Protection and Measurements in 2005. However, this model did not provide a good fit to the observed dose rates at ground level or on the roof. A more accurate method of estimating skyshine may be to measure the exposure rate of the radiation exiting the roof of the facility and to scale the results using the graphs presented in this paper.

  6. Demonstration of a positron beam-driven hollow channel plasma wakefield accelerator

    DOE PAGES

    Gessner, Spencer; Adli, Erik; Allen, James M.; ...

    2016-06-02

    Plasma wakefield accelerators have been used to accelerate electron and positron particle beams with gradients that are orders of magnitude larger than those achieved in conventional accelerators. In addition to being accelerated by the plasma wakefield, the beam particles also experience strong transverse forces that may disrupt the beam quality. Hollow plasma channels have been proposed as a technique for generating accelerating fields without transverse forces. In this study, we demonstrate a method for creating an extended hollow plasma channel and measure the wakefields created by an ultrarelativistic positron beam as it propagates through the channel. The plasma channel ismore » created by directing a high-intensity laser pulse with a spatially modulated profile into lithium vapour, which results in an annular region of ionization. A peak decelerating field of 230 MeV m -1 is inferred from changes in the beam energy spectrum, in good agreement with theory and particle-in-cell simulations.« less

  7. Demonstration of a positron beam-driven hollow channel plasma wakefield accelerator

    PubMed Central

    Gessner, Spencer; Adli, Erik; Allen, James M.; An, Weiming; Clarke, Christine I.; Clayton, Chris E.; Corde, Sebastien; Delahaye, J. P.; Frederico, Joel; Green, Selina Z.; Hast, Carsten; Hogan, Mark J.; Joshi, Chan; Lindstrøm, Carl A.; Lipkowitz, Nate; Litos, Michael; Lu, Wei; Marsh, Kenneth A.; Mori, Warren B.; O'Shea, Brendan; Vafaei-Najafabadi, Navid; Walz, Dieter; Yakimenko, Vitaly; Yocky, Gerald

    2016-01-01

    Plasma wakefield accelerators have been used to accelerate electron and positron particle beams with gradients that are orders of magnitude larger than those achieved in conventional accelerators. In addition to being accelerated by the plasma wakefield, the beam particles also experience strong transverse forces that may disrupt the beam quality. Hollow plasma channels have been proposed as a technique for generating accelerating fields without transverse forces. Here we demonstrate a method for creating an extended hollow plasma channel and measure the wakefields created by an ultrarelativistic positron beam as it propagates through the channel. The plasma channel is created by directing a high-intensity laser pulse with a spatially modulated profile into lithium vapour, which results in an annular region of ionization. A peak decelerating field of 230 MeV m−1 is inferred from changes in the beam energy spectrum, in good agreement with theory and particle-in-cell simulations. PMID:27250570

  8. Comparison of microstickies measurement methods. Part I, sample preparation and measurement methods

    Treesearch

    Mahendra R. Doshi; Angeles Blanco; Carlos Negro; Gilles M. Dorris; Carlos C. Castro; Axel Hamann; R. Daniel Haynes; Carl Houtman; Karen Scallon; Hans-Joachim Putz; Hans Johansson; R.A. Venditti; K. Copeland; H.-M. Chang

    2003-01-01

    Recently, we completed a project on the comparison of macrostickies measurement methods. Based on the success of the project, we decided to embark on this new project on comparison of microstickies measurement methods. When we started this project, there were some concerns and doubts principally due to the lack of an accepted definition of microstickies. However, we...

  9. A SIMPLE METHOD FOR MEASURING THE ELECTRON-BEAM MAGNETIZATION

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

    Halavanau, A.; Qiang, G.; Wisniewski, E.

    2016-10-18

    There are a number of projects that require magnetized beams, such as electron cooling or aiding in “flat” beam transforms. Here we explore a simple technique to characterize the magnetization, observed through the angular momentum of magnetized beams. These beams are produced through photoemission. The generating drive laser first passes through microlens arrays (fly-eye light condensers) to form a transversely modulated pulse incident on the photocathode surface [1]. The resulting charge distribution is then accelerated from the photocathode. We explore the evolution of the pattern via the relative shearing of the beamlets, providing information about the angular momentum. This methodmore » is illustrated through numerical simulations and preliminary measurements carried out at the Argonne Wakefield Accelerator (AWA) facility are presented.« less

  10. Evaluation Measures and Methods: Some Intersections.

    ERIC Educational Resources Information Center

    Elliott, John

    The literature is reviewed for four combinations of evaluation measures and methods: traditional methods with traditional measures (T-Meth/T-Mea), nontraditional methods with traditional measures (N-Meth/T-Mea), traditional measures with nontraditional measures (T-Meth/N-Mea), and nontraditional methods with nontraditional measures (N-Meth/N-Mea).…

  11. High gradient tests of metallic mm-wave accelerating structures

    DOE PAGES

    Dal Forno, Massimo; Dolgashev, Valery; Bowden, Gordon; ...

    2017-05-10

    This study explores the physics of vacuum rf breakdowns in high gradient mm-wave accelerating structures. We performed a series of experiments with 100 GHz and 200 GHz metallic accelerating structures, at the Facility for Advanced Accelerator Experimental Tests (FACET) at the SLAC National Accelerator Laboratory. This paper presents the experimental results of rf tests of 100 GHz travelling-wave accelerating structures, made of hard copper-silver alloy. The results are compared with pure hard copper structures. The rf fields were excited by the FACET ultra-relativistic electron beam. The accelerating structures have open geometries, 10 cm long, composed of two halves separated bymore » a variable gap. The rf frequency of the fundamental accelerating mode depends on the gap size and can be changed from 90 GHz to 140 GHz. The measured frequency and pulse length are consistent with our simulations. When the beam travels off-axis, a deflecting field is induced in addition to the decelerating longitudinal field. We measured the deflecting forces by observing the displacement of the electron bunch and used this measurement to verify the expected accelerating gradient. We present the first quantitative measurement of rf breakdown rates in 100 GHz copper-silver accelerating structure, which was 10 –3 per pulse, with peak electric field of 0.42 GV/m, an accelerating gradient of 127 MV/m, at a pulse length of 2.3 ns. The goal of our studies is to understand the physics of gradient limitations in order to increase the energy reach of future accelerators.« less

  12. High gradient tests of metallic mm-wave accelerating structures

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

    Dal Forno, Massimo; Dolgashev, Valery; Bowden, Gordon

    This study explores the physics of vacuum rf breakdowns in high gradient mm-wave accelerating structures. We performed a series of experiments with 100 GHz and 200 GHz metallic accelerating structures, at the Facility for Advanced Accelerator Experimental Tests (FACET) at the SLAC National Accelerator Laboratory. This paper presents the experimental results of rf tests of 100 GHz travelling-wave accelerating structures, made of hard copper-silver alloy. The results are compared with pure hard copper structures. The rf fields were excited by the FACET ultra-relativistic electron beam. The accelerating structures have open geometries, 10 cm long, composed of two halves separated bymore » a variable gap. The rf frequency of the fundamental accelerating mode depends on the gap size and can be changed from 90 GHz to 140 GHz. The measured frequency and pulse length are consistent with our simulations. When the beam travels off-axis, a deflecting field is induced in addition to the decelerating longitudinal field. We measured the deflecting forces by observing the displacement of the electron bunch and used this measurement to verify the expected accelerating gradient. We present the first quantitative measurement of rf breakdown rates in 100 GHz copper-silver accelerating structure, which was 10 –3 per pulse, with peak electric field of 0.42 GV/m, an accelerating gradient of 127 MV/m, at a pulse length of 2.3 ns. The goal of our studies is to understand the physics of gradient limitations in order to increase the energy reach of future accelerators.« less

  13. Validation of cardiac accelerometer sensor measurements.

    PubMed

    Remme, Espen W; Hoff, Lars; Halvorsen, Per Steinar; Naerum, Edvard; Skulstad, Helge; Fleischer, Lars A; Elle, Ole Jakob; Fosse, Erik

    2009-12-01

    In this study we have investigated the accuracy of an accelerometer sensor designed for the measurement of cardiac motion and automatic detection of motion abnormalities caused by myocardial ischaemia. The accelerometer, attached to the left ventricular wall, changed its orientation relative to the direction of gravity during the cardiac cycle. This caused a varying gravity component in the measured acceleration signal that introduced an error in the calculation of myocardial motion. Circumferential displacement, velocity and rotation of the left ventricular apical region were calculated from the measured acceleration signal. We developed a mathematical method to separate translational and gravitational acceleration components based on a priori assumptions of myocardial motion. The accuracy of the measured motion was investigated by comparison with known motion of a robot arm programmed to move like the heart wall. The accuracy was also investigated in an animal study. The sensor measurements were compared with simultaneously recorded motion from a robot arm attached next to the sensor on the heart and with measured motion by echocardiography and a video camera. The developed compensation method for the varying gravity component improved the accuracy of the calculated velocity and displacement traces, giving very good agreement with the reference methods.

  14. Principal Investigator Microgravity Services Role in ISS Acceleration Data Distribution

    NASA Technical Reports Server (NTRS)

    McPherson, Kevin

    1999-01-01

    Measurement of the microgravity acceleration environment on the International Space Station will be accomplished by two accelerometer systems. The Microgravity Acceleration Measurement System will record the quasi-steady microgravity environment, including the influences of aerodynamic drag, vehicle rotation, and venting effects. Measurement of the vibratory/transient regime comprised of vehicle, crew, and equipment disturbances will be accomplished by the Space Acceleration Measurement System-II. Due to the dynamic nature of the microgravity environment and its potential to influence sensitive experiments, Principal Investigators require distribution of microgravity acceleration in a timely and straightforward fashion. In addition to this timely distribution of the data, long term access to International Space Station microgravity environment acceleration data is required. The NASA Glenn Research Center's Principal Investigator Microgravity Services project will provide the means for real-time and post experiment distribution of microgravity acceleration data to microgravity science Principal Investigators. Real-time distribution of microgravity environment acceleration data will be accomplished via the World Wide Web. Data packets from the Microgravity Acceleration Measurement System and the Space Acceleration Measurement System-II will be routed from onboard the International Space Station to the NASA Glenn Research Center's Telescience Support Center. Principal Investigator Microgravity Services' ground support equipment located at the Telescience Support Center will be capable of generating a standard suite of acceleration data displays, including various time domain and frequency domain options. These data displays will be updated in real-time and will periodically update images available via the Principal Investigator Microgravity Services web page.

  15. Investigation on target normal sheath acceleration through measurements of ions energy distribution

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

    Tudisco, S., E-mail: tudisco@lns.infn.it; Cirrone, G. A. P.; Mascali, D.

    2016-02-15

    An experimental campaign aiming at investigating the ion acceleration mechanisms through laser-matter interaction in femtosecond domain has been carried out at the Intense Laser Irradiation Laboratory facility with a laser intensity of up to 2 × 10{sup 19} W/cm{sup 2}. A Thomson parabola spectrometer was used to obtain the spectra of the ions of the different species accelerated. Here, we show the energy spectra of light-ions and we discuss their dependence on structural characteristics of the target and the role of surface and target bulk in the acceleration process.

  16. Maximum Acceleration Recording Circuit

    NASA Technical Reports Server (NTRS)

    Bozeman, Richard J., Jr.

    1995-01-01

    Coarsely digitized maximum levels recorded in blown fuses. Circuit feeds power to accelerometer and makes nonvolatile record of maximum level to which output of accelerometer rises during measurement interval. In comparison with inertia-type single-preset-trip-point mechanical maximum-acceleration-recording devices, circuit weighs less, occupies less space, and records accelerations within narrower bands of uncertainty. In comparison with prior electronic data-acquisition systems designed for same purpose, circuit simpler, less bulky, consumes less power, costs and analysis of data recorded in magnetic or electronic memory devices. Circuit used, for example, to record accelerations to which commodities subjected during transportation on trucks.

  17. A novel method for measurement of MR fluid sedimentation and its experimental verification

    NASA Astrophysics Data System (ADS)

    Roupec, J.; Berka, P.; Mazůrek, I.; Strecker, Z.; Kubík, M.; Macháček, O.; Taheri Andani, M.

    2017-10-01

    This article presents a novel sedimentation measurement technique based on quantifying the changes in magnetic flux density when the magnetorheological fluid (MRF) passes through the air gap of the magnetic circuit. The sedimented MRF appears to have as a result of increased iron content. Accordingly, the sedimented portion of the sample displays a higher magnetic conductivity than the unsedimented area that contains less iron particles. The data analysis and evaluation methodology is elaborated along with an example set of measurements, which are compared against the visual observations and available data in the literature. Experiments indicate that unlike the existing methods, the new technique is able to accurately generate the complete curves of the sedimentation profile in a long-term sedimentation. The proposed method is capable of successfully detecting the area with the tightest particle configuration near the bottom (‘cake’ layer). It also addresses the issues with the development of an unclear boundary between the carrier fluid and the sediment (mudline) during an accelerated sedimentation process; improves the sensitivity of the sedimentation detection and accurately measure the changes in particle concentration with a high resolution.

  18. Periodic Pulay method for robust and efficient convergence acceleration of self-consistent field iterations

    DOE PAGES

    Banerjee, Amartya S.; Suryanarayana, Phanish; Pask, John E.

    2016-01-21

    Pulay's Direct Inversion in the Iterative Subspace (DIIS) method is one of the most widely used mixing schemes for accelerating the self-consistent solution of electronic structure problems. In this work, we propose a simple generalization of DIIS in which Pulay extrapolation is performed at periodic intervals rather than on every self-consistent field iteration, and linear mixing is performed on all other iterations. Lastly, we demonstrate through numerical tests on a wide variety of materials systems in the framework of density functional theory that the proposed generalization of Pulay's method significantly improves its robustness and efficiency.

  19. Acceleration Measurement and Characterization in Support of the USMP-4 Payloads

    NASA Technical Reports Server (NTRS)

    Rogers, M. J. B.; Hrovat, K.; McPherson, K.; DeLombard, R.; Reckart, T.

    1999-01-01

    One common characteristic of the USMP-4 experiments is that various effects of gravity make it difficult, if not impossible, to achieve usable results when performing the experiments on Earth's surface. Therefore, the investigators took advantage of the microgravity environment afforded by being in low-Earth orbit to perform their research. Interpretation of the experiment results both during the mission and upon post-mission analyses of data and samples required an understanding of the microgravity environment in which the experiments were conducted. To achieve that understanding, data were collected using the Orbital Acceleration Research Experiment (OARE) and two Space Acceleration Measurement Systems (SAMS). Data from those systems, combined with an assessment of mission and experiment activities, were used to characterize the microgravity environment that existed on Columbia during the mission. The text herein gives details about some characteristics of the environment that were noted during the mission and during post-mission data analysis. The disturbances studied include the Ku-band antenna 17 Hz dither; the effect of changing the Orbiter attitude deadband limits; the effects of different bicycle ergometer configurations; and the effect of IDGE (Isothermal Dendritic Growth Experiment) experiment fans and SAMS computer hard drives. Additional information about the microgravity environment is provided. Supplementary data plots representing the environment throughout the majority of the mission are available at the Uniform Resource Locator (URL). Data files for both SAMS and OARE are accessible via anonymous file transfer protocol from the file server.

  20. On the Use of Accelerated Aging Methods for Screening High Temperature Polymeric Composite Materials

    NASA Technical Reports Server (NTRS)

    Gates, Thomas S.; Grayson, Michael A.

    1999-01-01

    A rational approach to the problem of accelerated testing of high temperature polymeric composites is discussed. The methods provided are considered tools useful in the screening of new materials systems for long-term application to extreme environments that include elevated temperature, moisture, oxygen, and mechanical load. The need for reproducible mechanisms, indicator properties, and real-time data are outlined as well as the methodologies for specific aging mechanisms.

  1. Anomalous acceleration of ions in a plasma accelerator with an anodic layer

    NASA Astrophysics Data System (ADS)

    V, M. BARDAKOV; S, D. IVANOV; A, V. KAZANTSEV; N, A. STROKIN; A, N. STUPIN; Binhao, JIANG; Zhenyu, WANG

    2018-03-01

    In a plasma accelerator with an anodic layer (PAAL), we discovered experimentally the effect of ‘super-acceleration’ of the bulk of the ions to energies W exceeding the energy equivalent to the discharge voltage V d. The E × B discharge was ignited in an environment of atomic argon and helium and molecular nitrogen. Singly charged argon ions were accelerated most effectively in the case of the largest discharge currents and pressure P of the working gas. Helium ions with W > eV d (e being the electron charge) were only recorded at maximum pressures. Molecular nitrogen was not accelerated to energies W > eV d. Anomalous acceleration is realized in the range of radial magnetic fields on the anode 2.8 × 10 -2 ≤ B rA ≤ 4 × 10 -2 T. It was also found analytically that the cathode of the accelerator can receive anomalously accelerated ions. In this case, the value of the potential in the anodic layer becomes higher than the anode potential, and the anode current exceeds some critical value. Numerical modeling in terms of the developed theory showed qualitative agreement between modeling data and measurements.

  2. Insights into accelerated liposomal release of topotecan in plasma monitored by a non-invasive fluorescence spectroscopic method

    PubMed Central

    Fugit, Kyle D.; Jyoti, Amar; Upreti, Meenakshi; Anderson, Bradley D.

    2014-01-01

    A non-invasive fluorescence method was developed to monitor liposomal release kinetics of the anticancer agent topotecan (TPT) in physiological fluids and subsequently used to explore the cause of accelerated release in plasma. Analyses of fluorescence excitation spectra confirmed that unencapsulated TPT exhibits a red shift in its spectrum as pH is increased. This property was used to monitor TPT release from actively loaded liposomal formulations having a low intravesicular pH. Mathematical release models were developed to extract reliable rate constants for TPT release in aqueous solutions monitored by fluorescence and release kinetics obtained by HPLC. Using the fluorescence method, accelerated TPT release was observed in plasma as previously reported in the literature. Simulations to estimate the intravesicular pH were conducted to demonstrate that accelerated release correlated with alterations in the low intravesicular pH. This was attributed to the presence of ammonia in plasma samples rather than proteins and other plasma components generally believed to alter release kinetics in physiological samples. These findings shed light on the critical role that ammonia may play in contributing to the preclinical/clinical variability and performance seen with actively-loaded liposomal formulations of TPT and other weakly-basic anticancer agents. PMID:25456833

  3. Radiation from violently accelerated bodies

    NASA Astrophysics Data System (ADS)

    Gerlach, Ulrich H.

    2001-11-01

    A determination is made of the radiation emitted by a linearly uniformly accelerated uncharged dipole transmitter. It is found that, first of all, the radiation rate is given by the familiar Larmor formula, but it is augmented by an amount which becomes dominant for sufficiently high acceleration. For an accelerated dipole oscillator, the criterion is that the center of mass motion become relativistic within one oscillation period. The augmented formula and the measurements which it summarizes presuppose an expanding inertial observation frame. A static inertial reference frame will not do. Secondly, it is found that the radiation measured in the expanding inertial frame is received with 100% fidelity. There is no blueshift or redshift due to the accelerative motion of the transmitter. Finally, it is found that a pair of coherently radiating oscillators accelerating (into opposite directions) in their respective causally disjoint Rindler-coordinatized sectors produces an interference pattern in the expanding inertial frame. Like the pattern of a Young double slit interferometer, this Rindler interferometer pattern has a fringe spacing which is inversely proportional to the proper separation and the proper frequency of the accelerated sources. The interferometer, as well as the augmented Larmor formula, provide a unifying perspective. It joins adjacent Rindler-coordinatized neighborhoods into a single spacetime arena for scattering and radiation from accelerated bodies.

  4. Determination of neutral beam injection accelerator grid deformation using beam emission measurements

    NASA Astrophysics Data System (ADS)

    Nightingale, M. P. S.; Kugel, H.; Gee, S. J.; Price, M. N.

    1999-01-01

    Theoretical modeling of 1-2 MW positive hydrogen ion neutral injectors developed at Oak Ridge National Laboratory (ORNL) has suggested that the plasma grid temperature could rise by up to 180 °C at pulse lengths above 0.5 s, leading to a grid deformation on the order of 5 mm, with a consequent change in focal length (from 4 to 2 m) and beamlet focusing. One of these injectors (on loan from ORNL) was used to achieve record β values on the Small Tight Aspect Ratio Tokamak at Culham, and two more are to be used on the Mega-Ampere Spherical Tokamak (MAST) at pulse lengths of up to 5 s. Since the grid modeling has never been tested experimentally, a method for diagnosing changes in beam transport as a function of pulse length using light emitted by the beam is now under development at Culham to see if grid modifications are required for MAST. Initial experimental results, carried out using a 50 A 30 keV hydrogen beam, are presented (including comparison with thermocouple data using an EK98 graphite beam stop). These confirm that emission measurement should allow the accelerator focal length and beamlet divergence to be determined to accuracies of better than ±0.45 m and ±0.2°, respectively (compared to nominal values of 4 m and 1.2°).

  5. Monte Carlo-based fluorescence molecular tomography reconstruction method accelerated by a cluster of graphic processing units.

    PubMed

    Quan, Guotao; Gong, Hui; Deng, Yong; Fu, Jianwei; Luo, Qingming

    2011-02-01

    High-speed fluorescence molecular tomography (FMT) reconstruction for 3-D heterogeneous media is still one of the most challenging problems in diffusive optical fluorescence imaging. In this paper, we propose a fast FMT reconstruction method that is based on Monte Carlo (MC) simulation and accelerated by a cluster of graphics processing units (GPUs). Based on the Message Passing Interface standard, we modified the MC code for fast FMT reconstruction, and different Green's functions representing the flux distribution in media are calculated simultaneously by different GPUs in the cluster. A load-balancing method was also developed to increase the computational efficiency. By applying the Fréchet derivative, a Jacobian matrix is formed to reconstruct the distribution of the fluorochromes using the calculated Green's functions. Phantom experiments have shown that only 10 min are required to get reconstruction results with a cluster of 6 GPUs, rather than 6 h with a cluster of multiple dual opteron CPU nodes. Because of the advantages of high accuracy and suitability for 3-D heterogeneity media with refractive-index-unmatched boundaries from the MC simulation, the GPU cluster-accelerated method provides a reliable approach to high-speed reconstruction for FMT imaging.

  6. Acceleration modules in linear induction accelerators

    NASA Astrophysics Data System (ADS)

    Wang, Shao-Heng; Deng, Jian-Jun

    2014-05-01

    The Linear Induction Accelerator (LIA) is a unique type of accelerator that is capable of accelerating kilo-Ampere charged particle current to tens of MeV energy. The present development of LIA in MHz bursting mode and the successful application into a synchrotron have broadened LIA's usage scope. Although the transformer model is widely used to explain the acceleration mechanism of LIAs, it is not appropriate to consider the induction electric field as the field which accelerates charged particles for many modern LIAs. We have examined the transition of the magnetic cores' functions during the LIA acceleration modules' evolution, distinguished transformer type and transmission line type LIA acceleration modules, and re-considered several related issues based on transmission line type LIA acceleration module. This clarified understanding should help in the further development and design of LIA acceleration modules.

  7. Correlation of Noise Signature to Pulsed Power Events at the HERMES III Accelerator.

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

    Lewis, Barbara; Joseph, Nathan Ryan; Salazar, Juan Diego

    2016-11-01

    The HERMES III accelerator, which is located at Sandia National Laboratories' Tech Area IV, is the largest pulsed gamma X-ray source in the world. The accelerator is made up of 20 inductive cavities that are charged to 1 MV each by complex pulsed power circuitry. The firing time of the machine components ranges between the microsecond and nanosecond timescales. This results in a variety of electromagnetic frequencies when the accelerator fires. Testing was done to identify the HERMES electromagnetic noise signal and to map it to the various accelerator trigger events. This report will show the measurement methods used tomore » capture the noise spectrum produced from the machine and correlate this noise signature with machine events.« less

  8. Noncontact methods for measuring water-surface elevations and velocities in rivers: Implications for depth and discharge extraction

    USGS Publications Warehouse

    Nelson, Jonathan M.; Kinzel, Paul J.; McDonald, Richard R.; Schmeeckle, Mark

    2016-01-01

    Recently developed optical and videographic methods for measuring water-surface properties in a noninvasive manner hold great promise for extracting river hydraulic and bathymetric information. This paper describes such a technique, concentrating on the method of infrared videog- raphy for measuring surface velocities and both acoustic (laboratory-based) and laser-scanning (field-based) techniques for measuring water-surface elevations. In ideal laboratory situations with simple flows, appropriate spatial and temporal averaging results in accurate water-surface elevations and water-surface velocities. In test cases, this accuracy is sufficient to allow direct inversion of the governing equations of motion to produce estimates of depth and discharge. Unlike other optical techniques for determining local depth that rely on transmissivity of the water column (bathymetric lidar, multi/hyperspectral correlation), this method uses only water-surface information, so even deep and/or turbid flows can be investigated. However, significant errors arise in areas of nonhydrostatic spatial accelerations, such as those associated with flow over bedforms or other relatively steep obstacles. Using laboratory measurements for test cases, the cause of these errors is examined and both a simple semi-empirical method and computational results are presented that can potentially reduce bathymetric inversion errors.

  9. A method for evaluating dynamical friction in linear ball bearings.

    PubMed

    Fujii, Yusaku; Maru, Koichi; Jin, Tao; Yupapin, Preecha P; Mitatha, Somsak

    2010-01-01

    A method is proposed for evaluating the dynamical friction of linear bearings, whose motion is not perfectly linear due to some play in its internal mechanism. In this method, the moving part of a linear bearing is made to move freely, and the force acting on the moving part is measured as the inertial force given by the product of its mass and the acceleration of its centre of gravity. To evaluate the acceleration of its centre of gravity, the acceleration of two different points on it is measured using a dual-axis optical interferometer.

  10. Measuring the Impact of Technology on Nurse Workflow: A Mixed Methods Approach

    ERIC Educational Resources Information Center

    Cady, Rhonda Guse

    2012-01-01

    Background. Investment in health information technology (HIT) is rapidly accelerating. The absence of contextual or situational analysis of the environment in which HIT is incorporated makes it difficult to measure success or failure. The methodology introduced in this paper combines observational research with time-motion study to measure the…

  11. Anode power deposition in quasi-steady MPD arcs. [accelerator anode heat flux measurement

    NASA Technical Reports Server (NTRS)

    Saber, A. J.; Jahn, R. G.

    1973-01-01

    The power deposited in the anode of a quasi-steady MPD accelerator has been measured directly by thermocouples attached to the inside surface of a shell anode which provide a local measurement of anode heat flux. The results over a range of arc currents from 5.5 to 44 kiloamperes and argon mass flows from 1 g/sec to 48 g/sec show that the fraction of the total input power deposited in the anode decreases drastically from 50% at an arc power of 200 kW to 10% at 20 MW, and that anode power is not uniformly deposited in the anode. A theoretical model of the anode heat transfer, including effects of anode work function, electron thermal energy, and anode sheath, can be brought into reasonable agreement with the measurements, provided the effective range of the conduction electrons from within the discharge plasma to the anode surface is properly acknowledged.

  12. Track profile approximation using railcar body acceleration data.

    DOT National Transportation Integrated Search

    2014-12-01

    Accelerations are frequently measured from the car body of a rail vehicle, which is mounted above one or more suspension : systems. Measuring accelerations in the car body is largely done for convenience, as mounting an accelerometer to a truck or ax...

  13. Microwave-Accelerated Method for Ultra-Rapid Extraction of Neisseria gonorrhoeae DNA for Downstream Detection

    PubMed Central

    Melendez, Johan H.; Santaus, Tonya M.; Brinsley, Gregory; Kiang, Daniel; Mali, Buddha; Hardick, Justin; Gaydos, Charlotte A.; Geddes, Chris D.

    2016-01-01

    Nucleic acid-based detection of gonorrhea infections typically require a two-step process involving isolation of the nucleic acid, followed by the detection of the genomic target often involving PCR-based approaches. In an effort to improve on current detection approaches, we have developed a unique two-step microwave-accelerated approach for rapid extraction and detection of Neisseria gonorrhoeae (GC) DNA. Our approach is based on the use of highly-focused microwave radiation to rapidly lyse bacterial cells, release, and subsequently fragment microbial DNA. The DNA target is then detected by a process known as microwave-accelerated metal-enhanced fluorescence (MAMEF), an ultra-sensitive direct DNA detection analytical technique. In the present study, we show that highly focused microwaves at 2.45 GHz, using 12.3 mm gold film equilateral triangles, are able to rapidly lyse both bacteria cells and fragment DNA in a time- and microwave power-dependent manner. Detection of the extracted DNA can be performed by MAMEF, without the need for DNA amplification in less than 10 minutes total time or by other PCR-based approaches. Collectively, the use of a microwave-accelerated method for the release and detection of DNA represents a significant step forward towards the development of a point-of-care (POC) platform for detection of gonorrhea infections. PMID:27325503

  14. Microwave-accelerated method for ultra-rapid extraction of Neisseria gonorrhoeae DNA for downstream detection.

    PubMed

    Melendez, Johan H; Santaus, Tonya M; Brinsley, Gregory; Kiang, Daniel; Mali, Buddha; Hardick, Justin; Gaydos, Charlotte A; Geddes, Chris D

    2016-10-01

    Nucleic acid-based detection of gonorrhea infections typically require a two-step process involving isolation of the nucleic acid, followed by detection of the genomic target often involving polymerase chain reaction (PCR)-based approaches. In an effort to improve on current detection approaches, we have developed a unique two-step microwave-accelerated approach for rapid extraction and detection of Neisseria gonorrhoeae (gonorrhea, GC) DNA. Our approach is based on the use of highly focused microwave radiation to rapidly lyse bacterial cells, release, and subsequently fragment microbial DNA. The DNA target is then detected by a process known as microwave-accelerated metal-enhanced fluorescence (MAMEF), an ultra-sensitive direct DNA detection analytical technique. In the current study, we show that highly focused microwaves at 2.45 GHz, using 12.3-mm gold film equilateral triangles, are able to rapidly lyse both bacteria cells and fragment DNA in a time- and microwave power-dependent manner. Detection of the extracted DNA can be performed by MAMEF, without the need for DNA amplification, in less than 10 min total time or by other PCR-based approaches. Collectively, the use of a microwave-accelerated method for the release and detection of DNA represents a significant step forward toward the development of a point-of-care (POC) platform for detection of gonorrhea infections. Copyright © 2016 Elsevier Inc. All rights reserved.

  15. Secular Acceleration of Barnard's Star

    NASA Astrophysics Data System (ADS)

    Bartlett, Jennifer L.; Ianna, P. A.

    2009-01-01

    Barnard's Star should have significant secular acceleration because it lies close to the Sun and has the highest known proper motion along with a large radial velocity. It will pass within about 1.4 pc in another 9,750 years. Secular changes in proper motion and radial velocity are essentially the Coriolis and centrifugal accelerations, respectively, arising from use of a rotating coordinate system defined by the Sun-star radius vector. Although stellar space velocities measured with respect to the Sun are essentially constant, these perspective effects arise with changing distance and viewing angle. Hipparcos-2 plus Nidever et al. (2002) predict a perspective change in the proper motion of 1.285±0.006 mas yr-2 for Barnard's Star. Recent analysis of 900+ photographic plates between 1968 and 1998 with the 26.25-in (0.67-m) McCormick refractor detected a secular acceleration of 1.25±0.04 mas yr-2, which agrees with the predicted value within the measurement errors. Earlier, Benedict et al. (1999) measured its secular acceleration to be 1.2±0.2 mas yr-2 using 3 years of HST FGS observations. Similarly, a perspective change in radial velocity of 4.50±0.01 m s-1 yr-1 can be predicted for Barnard's Star. Kürster et al. (2003) detected variations in their observations of it that are largely attributable to secular acceleration along the line of sight with some contribution from stellar activity. Although secular acceleration effects have been limited for past studies of stellar motions, they can be significant for observations extending over decades or for high-precision measurements required to detect extrasolar planets. Future studies will need to consider this factor for the nearest stars and for those with large proper motions or radial velocities. NSF grant AST 98-20711; Litton Marine Systems; Peninsula Community Foundation Levinson Fund; UVa Governor's Fellowship, Dean's F&A Fellowship, and Graduate School of Arts and Sciences; and, US Naval Observatory

  16. Methodology and measures for preventing unacceptable flow-accelerated corrosion thinning of pipelines and equipment of NPP power generating units

    NASA Astrophysics Data System (ADS)

    Tomarov, G. V.; Shipkov, A. A.; Lovchev, V. N.; Gutsev, D. F.

    2016-10-01

    Problems of metal flow-accelerated corrosion (FAC) in the pipelines and equipment of the condensate- feeding and wet-steam paths of NPP power-generating units (PGU) are examined. Goals, objectives, and main principles of the methodology for the implementation of an integrated program of AO Concern Rosenergoatom for the prevention of unacceptable FAC thinning and for increasing operational flow-accelerated corrosion resistance of NPP EaP are worded (further the Program). A role is determined and potentialities are shown for the use of Russian software packages in the evaluation and prediction of FAC rate upon solving practical problems for the timely detection of unacceptable FAC thinning in the elements of pipelines and equipment (EaP) of the secondary circuit of NPP PGU. Information is given concerning the structure, properties, and functions of the software systems for plant personnel support in the monitoring and planning of the inservice inspection of FAC thinning elements of pipelines and equipment of the secondary circuit of NPP PGUs, which are created and implemented at some Russian NPPs equipped with VVER-1000, VVER-440, and BN-600 reactors. It is noted that one of the most important practical results of software packages for supporting NPP personnel concerning the issue of flow-accelerated corrosion consists in revealing elements under a hazard of intense local FAC thinning. Examples are given for successful practice at some Russian NPP concerning the use of software systems for supporting the personnel in early detection of secondary-circuit pipeline elements with FAC thinning close to an unacceptable level. Intermediate results of working on the Program are presented and new tasks set in 2012 as a part of the updated program are denoted. The prospects of the developed methods and tools in the scope of the Program measures at the stages of design and construction of NPP PGU are discussed. The main directions of the work on solving the problems of flow-accelerated

  17. Self-organizing map (SOM) of space acceleration measurement system (SAMS) data.

    PubMed

    Sinha, A; Smith, A D

    1999-01-01

    In this paper, space acceleration measurement system (SAMS) data have been classified using self-organizing map (SOM) networks without any supervision; i.e., no a priori knowledge is assumed regarding input patterns belonging to a certain class. Input patterns are created on the basis of power spectral densities of SAMS data. Results for SAMS data from STS-50 and STS-57 missions are presented. Following issues are discussed in details: impact of number of neurons, global ordering of SOM weight vectors, effectiveness of a SOM in data classification, and effects of shifting time windows in the generation of input patterns. The concept of 'cascade of SOM networks' is also developed and tested. It has been found that a SOM network can successfully classify SAMS data obtained during STS-50 and STS-57 missions.

  18. Self-organizing map (SOM) of space acceleration measurement system (SAMS) data

    NASA Technical Reports Server (NTRS)

    Sinha, A.; Smith, A. D.

    1999-01-01

    In this paper, space acceleration measurement system (SAMS) data have been classified using self-organizing map (SOM) networks without any supervision; i.e., no a priori knowledge is assumed regarding input patterns belonging to a certain class. Input patterns are created on the basis of power spectral densities of SAMS data. Results for SAMS data from STS-50 and STS-57 missions are presented. Following issues are discussed in details: impact of number of neurons, global ordering of SOM weight vectors, effectiveness of a SOM in data classification, and effects of shifting time windows in the generation of input patterns. The concept of 'cascade of SOM networks' is also developed and tested. It has been found that a SOM network can successfully classify SAMS data obtained during STS-50 and STS-57 missions.

  19. Accelerated life testing of spacecraft subsystems

    NASA Technical Reports Server (NTRS)

    Wiksten, D.; Swanson, J.

    1972-01-01

    The rationale and requirements for conducting accelerated life tests on electronic subsystems of spacecraft are presented. A method for applying data on the reliability and temperature sensitivity of the parts contained in a sybsystem to the selection of accelerated life test parameters is described. Additional considerations affecting the formulation of test requirements are identified, and practical limitations of accelerated aging are described.

  20. Monitoring oil displacement processes with k-t accelerated spin echo SPI.

    PubMed

    Li, Ming; Xiao, Dan; Romero-Zerón, Laura; Balcom, Bruce J

    2016-03-01

    Magnetic resonance imaging (MRI) is a robust tool to monitor oil displacement processes in porous media. Conventional MRI measurement times can be lengthy, which hinders monitoring time-dependent displacements. Knowledge of the oil and water microscopic distribution is important because their pore scale behavior reflects the oil trapping mechanisms. The oil and water pore scale distribution is reflected in the magnetic resonance T2 signal lifetime distribution. In this work, a pure phase-encoding MRI technique, spin echo SPI (SE-SPI), was employed to monitor oil displacement during water flooding and polymer flooding. A k-t acceleration method, with low-rank matrix completion, was employed to improve the temporal resolution of the SE-SPI MRI measurements. Comparison to conventional SE-SPI T2 mapping measurements revealed that the k-t accelerated measurement was more sensitive and provided higher-quality results. It was demonstrated that the k-t acceleration decreased the average measurement time from 66.7 to 20.3 min in this work. A perfluorinated oil, containing no (1) H, and H2 O brine were employed to distinguish oil and water phases in model flooding experiments. High-quality 1D water saturation profiles were acquired from the k-t accelerated SE-SPI measurements. Spatially and temporally resolved T2 distributions were extracted from the profile data. The shift in the (1) H T2 distribution of water in the pore space to longer lifetimes during water flooding and polymer flooding is consistent with increased water content in the pore space. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.

  1. Optical Diagnostics for Plasma-based Particle Accelerators

    NASA Astrophysics Data System (ADS)

    Muggli, Patric

    2009-05-01

    One of the challenges for plasma-based particle accelerators is to measure the spatio-temporal characteristics of the accelerated particle bunch. ``Optical'' diagnostics are particularly interesting and useful because of the large number of techniques that exits to determine the properties of photon pulses. The accelerated bunch can produce photons pulses that carry information about its characteristics for example through synchrotron radiation in a magnet, Cherenkov radiation in a gas, and transition radiation (TR) at the boundary between two media with different dielectric constants. Depending on the wavelength of the emission when compared to the particle bunch length, the radiation can be incoherent or coherent. Incoherent TR in the optical range (or OTR) is useful to measure the transverse spatial characteristics of the beam, such as charge distribution and size. Coherent TR (or CTR) carries information about the bunch length that can in principle be retrieved by standard auto-correlation or interferometric techniques, as well as by spectral measurements. A measurement of the total CTR energy emitted by bunches with constant charge can also be used as a shot-to-shot measurement for the relative bunch length as the CTR energy is proportional to the square of the bunch population and inversely proportional to its length (for a fixed distribution). Spectral interferometry can also yield the spacing between bunches in the case where multiple bunches are trapped in subsequent buckets of the plasma wave. Cherenkov radiation can be used as an energy threshold diagnostic for low energy particles. Cherenkov, synchrotron and transition radiation can be used in a dispersive section of the beam line to measure the bunch energy spectrum. The application of these diagnostics to plasma-based particle accelerators, with emphasis on the beam-driven, plasma wakefield accelerator (PWFA) at the SLAC National Accelerator Laboratory will be discussed.

  2. Essential energy space random walk via energy space metadynamics method to accelerate molecular dynamics simulations

    NASA Astrophysics Data System (ADS)

    Li, Hongzhi; Min, Donghong; Liu, Yusong; Yang, Wei

    2007-09-01

    To overcome the possible pseudoergodicity problem, molecular dynamic simulation can be accelerated via the realization of an energy space random walk. To achieve this, a biased free energy function (BFEF) needs to be priori obtained. Although the quality of BFEF is essential for sampling efficiency, its generation is usually tedious and nontrivial. In this work, we present an energy space metadynamics algorithm to efficiently and robustly obtain BFEFs. Moreover, in order to deal with the associated diffusion sampling problem caused by the random walk in the total energy space, the idea in the original umbrella sampling method is generalized to be the random walk in the essential energy space, which only includes the energy terms determining the conformation of a region of interest. This essential energy space generalization allows the realization of efficient localized enhanced sampling and also offers the possibility of further sampling efficiency improvement when high frequency energy terms irrelevant to the target events are free of activation. The energy space metadynamics method and its generalization in the essential energy space for the molecular dynamics acceleration are demonstrated in the simulation of a pentanelike system, the blocked alanine dipeptide model, and the leucine model.

  3. An effective method of UV-oxidation of dissolved organic carbon in natural waters for radiocarbon analysis by accelerator mass spectrometry

    NASA Astrophysics Data System (ADS)

    Xue, Yuejun; Ge, Tiantian; Wang, Xuchen

    2015-12-01

    Radiocarbon (14C) measurement of dissolved organic carbon (DOC) is a very powerful tool to study the sources, transformation and cycling of carbon in the ocean. The technique, however, remains great challenges for complete and successful oxidation of sufficient DOC with low blanks for high precision carbon isotopic ratio analysis, largely due to the overwhelming proportion of salts and low DOC concentrations in the ocean. In this paper, we report an effective UV-Oxidation method for oxidizing DOC in natural waters for radiocarbon analysis by accelerator mass spectrometry (AMS). The UV-oxidation system and method show 95%±4% oxidation efficiency and high reproducibility for DOC in both river and seawater samples. The blanks associated with the method was also low (about 3 µg C) that is critical for 14C analysis. As a great advantage of the method, multiple water samples can be oxidized at the same time so it reduces the sample processing time substantially compared with other UV-oxidation method currently being used in other laboratories. We have used the system and method for 14C studies of DOC in rivers, estuaries, and oceanic environments and have received promise results.

  4. A method for estimating mount isolations of powertrain mounting systems

    NASA Astrophysics Data System (ADS)

    Qin, Wu; Shangguan, Wen-Bin; Luo, Guohai; Xie, Zhengchao

    2018-07-01

    A method for calculating isolation ratios of mounts at a powertrain mounting systems (PMS) is proposed assuming a powertrain as a rigid body and using the identified powertrain excitation forces and the measured IPI (input point inertance) of mounting points at the body side. With measured accelerations of mounts at powertrain and body sides of one Vehicle (Vehicle A), the excitation forces of a powertrain are identified using conversational method firstly. Another Vehicle (Vehicle B) has the same powertrain as that of Vehicle A, but with different body and mount configuration. The accelerations of mounts at powertrain side of a PMS on Vehicle B are calculated using the powertrain excitation forces identified from Vehicle A. The identified forces of the powertrain are validated by comparing the calculated and the measured accelerations of mounts at the powertrain side of the powertrain on Vehicle B. A method for calculating acceleration of mounting point at body side for Vehicle B is presented using the identified powertrain excitation forces and the measured IPI at a connecting point between car body and mount. Using the calculated accelerations of mounts at powertrain side and body side at different directions, the isolation ratios of a mount are then estimated. The isolation ratios are validated using the experiment, which verified the proposed methods for estimating isolation ratios of mounts. The developed method is beneficial for optimizing mount stiffness to meet mount isolation requirements before prototype.

  5. Shelf Life Prediction for Canned Gudeg using Accelerated Shelf Life Testing (ASLT) Based on Arrhenius Method

    NASA Astrophysics Data System (ADS)

    Nurhayati, R.; Rahayu NH, E.; Susanto, A.; Khasanah, Y.

    2017-04-01

    Gudeg is traditional food from Yogyakarta. It is consist of jackfruit, chicken, egg and coconut milk. Gudeg generally have a short shelf life. Canning or commercial sterilization is one way to extend the shelf life of gudeg. This aims of this research is to predict the shelf life of Andrawinaloka canned gudeg with Accelerated Shelf Life Test methods, Arrhenius model. Canned gudeg stored at three different temperature, there are 37, 50 and 60°C for two months. Measuring the number of Thio Barbituric Acid (TBA), as a critical aspect, were tested every 7 days. Arrhenius model approach is done with the equation order 0 and order 1. The analysis showed that the equation of order 0 can be used as an approach to estimating the shelf life of canned gudeg. The storage of Andrawinaloka canned gudeg at 30°C is predicted untill 21 months and 24 months for 25°C.

  6. Accelerator science in medical physics.

    PubMed

    Peach, K; Wilson, P; Jones, B

    2011-12-01

    The use of cyclotrons and synchrotrons to accelerate charged particles in hospital settings for the purpose of cancer therapy is increasing. Consequently, there is a growing demand from medical physicists, radiographers, physicians and oncologists for articles that explain the basic physical concepts of these technologies. There are unique advantages and disadvantages to all methods of acceleration. Several promising alternative methods of accelerating particles also have to be considered since they will become increasingly available with time; however, there are still many technical problems with these that require solving. This article serves as an introduction to this complex area of physics, and will be of benefit to those engaged in cancer therapy, or who intend to acquire such technologies in the future.

  7. High spatial resolution measurements of ram accelerator gas dynamic phenomena

    NASA Technical Reports Server (NTRS)

    Hinkey, J. B.; Burnham, E. A.; Bruckner, A. P.

    1992-01-01

    High spatial resolution experimental tube wall pressure measurements of ram accelerator gas dynamic phenomena are presented. The projectile resembles the centerbody of a ramjet and travels supersonically through a tube filled with a combustible gaseous mixture, with the tube acting as the outer cowling. Pressure data are recorded as the projectile passes by sensors mounted in the tube wall at various locations along the tube. Data obtained by using a special highly instrumented section of tube has allowed the recording of gas dynamic phenomena with a spatial resolution on the order of one tenth the projectile length. High spatial resolution tube wall pressure data from the three regimes of propulsion studied to date (subdetonative, transdetonative, and superdetonative) are presented and reveal the 3D character of the flowfield induced by projectile fins and the canting of the projectile body relative to the tube wall. Also presented for comparison to the experimental data are calculations made with an inviscid, 3D CFD code.

  8. The progress about measurements of the proton beam characteristics of the JUNA 400 kV accelerator

    NASA Astrophysics Data System (ADS)

    Wang, Shuo; Li, Kuoang

    2018-04-01

    China JinPing underground Laboratory (CJPL) was established inside the tunnels piercing Jinping Mountain in Sichuan Province, China, which can provide an ideal environment for low background experiment. Jinping Underground laboratory for Nuclear Astrophysics (JUNA) is one of the major research programs in CJPL. A new 400 kV accelerator, with high current based on an ECR source, will be installed into CJPL for the study of key nuclear reactions in astrophysics. The beam characteristics of the accelerator, like absolute energy, energy spread, and long-term energy stability, will be determined by several well-known resonance and non-resonance reactions. Due to the new accelerator still being under construction, the resonance reaction of 27Al(p, γ)28Si and non-resonance 12C(p, γ)13N were studied at the 320 kV high-voltage platform of Institute of Modern Physics in Lanzhou, China. The energy spread of proton beam is about 1.0 keV and the long-term energy stability of proton beam is better than ±200eV during 4 hours measurement.

  9. Water bath accelerated curing of concrete.

    DOT National Transportation Integrated Search

    1970-01-01

    Water bath methods for accelerating the strength development of portland cement concrete were investigated in a two phase study as follows. Phase I - Participation in a cooperative accelerated strength testing program sponsored by the American Societ...

  10. Continuous estimates on the earthquake early warning magnitude by use of the near-field acceleration records

    NASA Astrophysics Data System (ADS)

    Li, Jun; Jin, Xing; Wei, Yongxiang; Zhang, Hongcai

    2013-10-01

    In this article, the seismic records of Japan's Kik-net are selected to measure the acceleration, displacement, and effective peak acceleration of each seismic record within a certain time after P wave, then a continuous estimation is given on earthquake early warning magnitude through statistical analysis method, and Wenchuan earthquake record is utilized to check the method. The results show that the reliability of earthquake early warning magnitude continuously increases with the increase of the seismic information, the biggest residual happens if the acceleration is adopted to fit earthquake magnitude, which may be caused by rich high-frequency components and large dispersion of peak value in acceleration record, the influence caused by the high-frequency components can be effectively reduced if the effective peak acceleration and peak displacement is adopted, it is estimated that the dispersion of earthquake magnitude obviously reduces, but it is easy for peak displacement to be affected by long-period drifting. In various components, the residual enlargement phenomenon at vertical direction is almost unobvious, thus it is recommended in this article that the effective peak acceleration at vertical direction is preferred to estimate earthquake early warning magnitude. Through adopting Wenchuan strong earthquake record to check the method mentioned in this article, it is found that this method can be used to quickly, stably, and accurately estimate the early warning magnitude of this earthquake, which shows that this method is completely applicable for earthquake early warning.

  11. A simple differential steady-state method to measure the thermal conductivity of solid bulk materials with high accuracy.

    PubMed

    Kraemer, D; Chen, G

    2014-02-01

    Accurate measurements of thermal conductivity are of great importance for materials research and development. Steady-state methods determine thermal conductivity directly from the proportionality between heat flow and an applied temperature difference (Fourier Law). Although theoretically simple, in practice, achieving high accuracies with steady-state methods is challenging and requires rather complex experimental setups due to temperature sensor uncertainties and parasitic heat loss. We developed a simple differential steady-state method in which the sample is mounted between an electric heater and a temperature-controlled heat sink. Our method calibrates for parasitic heat losses from the electric heater during the measurement by maintaining a constant heater temperature close to the environmental temperature while varying the heat sink temperature. This enables a large signal-to-noise ratio which permits accurate measurements of samples with small thermal conductance values without an additional heater calibration measurement or sophisticated heater guards to eliminate parasitic heater losses. Additionally, the differential nature of the method largely eliminates the uncertainties of the temperature sensors, permitting measurements with small temperature differences, which is advantageous for samples with high thermal conductance values and/or with strongly temperature-dependent thermal conductivities. In order to accelerate measurements of more than one sample, the proposed method allows for measuring several samples consecutively at each temperature measurement point without adding significant error. We demonstrate the method by performing thermal conductivity measurements on commercial bulk thermoelectric Bi2Te3 samples in the temperature range of 30-150 °C with an error below 3%.

  12. Method and system for measuring multiphase flow using multiple pressure differentials

    DOEpatents

    Fincke, James R.

    2001-01-01

    An improved method and system for measuring a multiphase flow in a pressure flow meter. An extended throat venturi is used and pressure of the multiphase flow is measured at three or more positions in the venturi, which define two or more pressure differentials in the flow conduit. The differential pressures are then used to calculate the mass flow of the gas phase, the total mass flow, and the liquid phase. The method for determining the mass flow of the high void fraction fluid flow and the gas flow includes certain steps. The first step is calculating a gas density for the gas flow. The next two steps are finding a normalized gas mass flow rate through the venturi and computing a gas mass flow rate. The following step is estimating the gas velocity in the venturi tube throat. The next step is calculating the pressure drop experienced by the gas-phase due to work performed by the gas phase in accelerating the liquid phase between the upstream pressure measuring point and the pressure measuring point in the venturi throat. Another step is estimating the liquid velocity in the venturi throat using the calculated pressure drop experienced by the gas-phase due to work performed by the gas phase. Then the friction is computed between the liquid phase and a wall in the venturi tube. Finally, the total mass flow rate based on measured pressure in the venturi throat is calculated, and the mass flow rate of the liquid phase is calculated from the difference of the total mass flow rate and the gas mass flow rate.

  13. A traveling-wave forward coupler design for a new accelerating mode in a silicon woodpile accelerator

    DOE PAGES

    Wu, Ziran; Lee, Chunghun H.; Wootton, Kent P.; ...

    2016-03-01

    Silicon woodpile photonic crystals provide a base structure that can be used to build a three-dimensional dielectric waveguide system for high-gradient laser driven acceleration. A new woodpile waveguide design that hosts a phase synchronous, centrally confined accelerating mode is proposed. Comparing with previously discovered silicon woodpile accelerating modes, this mode shows advantages in terms of better electron beam loading and higher achievable acceleration gradient. Several traveling-wave coupler design schemes developed for multi-cell RF cavity accelerators are adapted to the woodpile power coupler design for this new accelerating mode. Design of a forward coupled, highly efficient silicon woodpile accelerator is achieved.more » Simulation shows high efficiency of over 75% of the drive laser power coupled to this fundamental accelerating mode, with less than 15% backward wave scattering. The estimated acceleration gradient, when the coupler structure is driven at the damage threshold fluence of silicon at its operating 1.506 μm wavelength, can reach 185 MV/m. Lastly, a 17-layer woodpile waveguide structure was successfully fabricated, and the measured bandgap is in excellent agreement with simulation.« less

  14. A traveling-wave forward coupler design for a new accelerating mode in a silicon woodpile accelerator

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

    Wu, Ziran; Lee, Chunghun H.; Wootton, Kent P.

    Silicon woodpile photonic crystals provide a base structure that can be used to build a three-dimensional dielectric waveguide system for high-gradient laser driven acceleration. A new woodpile waveguide design that hosts a phase synchronous, centrally confined accelerating mode is proposed. Comparing with previously discovered silicon woodpile accelerating modes, this mode shows advantages in terms of better electron beam loading and higher achievable acceleration gradient. Several traveling-wave coupler design schemes developed for multi-cell RF cavity accelerators are adapted to the woodpile power coupler design for this new accelerating mode. Design of a forward coupled, highly efficient silicon woodpile accelerator is achieved.more » Simulation shows high efficiency of over 75% of the drive laser power coupled to this fundamental accelerating mode, with less than 15% backward wave scattering. The estimated acceleration gradient, when the coupler structure is driven at the damage threshold fluence of silicon at its operating 1.506 μm wavelength, can reach 185 MV/m. Lastly, a 17-layer woodpile waveguide structure was successfully fabricated, and the measured bandgap is in excellent agreement with simulation.« less

  15. The acceleration dependent validity and reliability of 10 Hz GPS.

    PubMed

    Akenhead, Richard; French, Duncan; Thompson, Kevin G; Hayes, Philip R

    2014-09-01

    To examine the validity and inter-unit reliability of 10 Hz GPS for measuring instantaneous velocity during maximal accelerations. Experimental. Two 10 Hz GPS devices secured to a sliding platform mounted on a custom built monorail were towed whilst sprinting maximally over 10 m. Displacement of GPS devices was measured using a laser sampling at 2000 Hz, from which velocity and mean acceleration were derived. Velocity data was pooled into acceleration thresholds according to mean acceleration. Agreement between laser and GPS measures of instantaneous velocity within each acceleration threshold was examined using least squares linear regression and Bland-Altman limits of agreement (LOA). Inter-unit reliability was expressed as typical error (TE) and a Pearson correlation coefficient. Mean bias ± 95% LOA during accelerations of 0-0.99 ms(-2) was 0.12 ± 0.27 ms(-1), decreasing to -0.40 ± 0.67 ms(-1) during accelerations >4 ms(-2). Standard error of the estimate ± 95% CI (SEE) increased from 0.12 ± 0.02 ms(-1) during accelerations of 0-0.99 ms(-2) to 0.32 ± 0.06 ms(-1) during accelerations >4 ms(-2). TE increased from 0.05 ± 0.01 to 0.12 ± 0.01 ms(-1) during accelerations of 0-0.99 ms(-2) and >4 ms(-2) respectively. The validity and reliability of 10 Hz GPS for the measurement of instantaneous velocity has been shown to be inversely related to acceleration. Those using 10 Hz GPS should be aware that during accelerations of over 4 ms(-2), accuracy is compromised. Copyright © 2013 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

  16. Estimation of Attitude and External Acceleration Using Inertial Sensor Measurement During Various Dynamic Conditions

    PubMed Central

    Lee, Jung Keun; Park, Edward J.; Robinovitch, Stephen N.

    2012-01-01

    This paper proposes a Kalman filter-based attitude (i.e., roll and pitch) estimation algorithm using an inertial sensor composed of a triaxial accelerometer and a triaxial gyroscope. In particular, the proposed algorithm has been developed for accurate attitude estimation during dynamic conditions, in which external acceleration is present. Although external acceleration is the main source of the attitude estimation error and despite the need for its accurate estimation in many applications, this problem that can be critical for the attitude estimation has not been addressed explicitly in the literature. Accordingly, this paper addresses the combined estimation problem of the attitude and external acceleration. Experimental tests were conducted to verify the performance of the proposed algorithm in various dynamic condition settings and to provide further insight into the variations in the estimation accuracy. Furthermore, two different approaches for dealing with the estimation problem during dynamic conditions were compared, i.e., threshold-based switching approach versus acceleration model-based approach. Based on an external acceleration model, the proposed algorithm was capable of estimating accurate attitudes and external accelerations for short accelerated periods, showing its high effectiveness during short-term fast dynamic conditions. Contrariwise, when the testing condition involved prolonged high external accelerations, the proposed algorithm exhibited gradually increasing errors. However, as soon as the condition returned to static or quasi-static conditions, the algorithm was able to stabilize the estimation error, regaining its high estimation accuracy. PMID:22977288

  17. A Quantitative Analysis of Methods Used for Avoidance and Acceleration of Developmental Mathematics Sequences in Community College

    ERIC Educational Resources Information Center

    Travers, Steven T.

    2017-01-01

    Many developmental mathematics programs at community colleges in recent years have undergone a process of redesign in an attempt increase the historical poor rate of student successful completion of required developmental coursework. Various curriculum and instructional design models that incorporate methods of avoiding and accelerating the…

  18. Method for technology-delivered healthcare measures.

    PubMed

    Kramer-Jackman, Kelli Lee; Popkess-Vawter, Sue

    2011-12-01

    Current healthcare literature lacks development and evaluation methods for research and practice measures administered by technology. Researchers with varying levels of informatics experience are developing technology-delivered measures because of the numerous advantages they offer. Hasty development of technology-delivered measures can present issues that negatively influence administration and psychometric properties. The Method for Technology-delivered Healthcare Measures is designed to systematically guide the development and evaluation of technology-delivered measures. The five-step Method for Technology-delivered Healthcare Measures includes establishment of content, e-Health literacy, technology delivery, expert usability, and participant usability. Background information and Method for Technology-delivered Healthcare Measures steps are detailed.

  19. Acute Effect of Different Combined Stretching Methods on Acceleration and Speed in Soccer Players.

    PubMed

    Amiri-Khorasani, Mohammadtaghi; Calleja-Gonzalez, Julio; Mogharabi-Manzari, Mansooreh

    2016-04-01

    The purpose of this study was to investigate the acute effect of different stretching methods, during a warm-up, on the acceleration and speed of soccer players. The acceleration performance of 20 collegiate soccer players (body height: 177.25 ± 5.31 cm; body mass: 65.10 ± 5.62 kg; age: 16.85 ± 0.87 years; BMI: 20.70 ± 5.54; experience: 8.46 ± 1.49 years) was evaluated after different warm-up procedures, using 10 and 20 m tests. Subjects performed five types of a warm-up: static, dynamic, combined static + dynamic, combined dynamic + static, and no-stretching. Subjects were divided into five groups. Each group performed five different warm-up protocols in five non-consecutive days. The warm-up protocol used for each group was randomly assigned. The protocols consisted of 4 min jogging, a 1 min stretching program (except for the no-stretching protocol), and 2 min rest periods, followed by the 10 and 20 m sprint test, on the same day. The current findings showed significant differences in the 10 and 20 m tests after dynamic stretching compared with static, combined, and no-stretching protocols. There were also significant differences between the combined stretching compared with static and no-stretching protocols. We concluded that soccer players performed better with respect to acceleration and speed, after dynamic and combined stretching, as they were able to produce more force for a faster execution.

  20. The feasibility of isobaric suppression of 26Mg via post-accelerator foil stripping for the measurement of 26Al [The feasibility of isobaric suppression of 26Mg via post-accelerator foil stripping for the measurement of 26Al.

    DOE PAGES

    Tumey, Scott J.; Brown, Thomas A.; Finkel, Robert C.; ...

    2012-09-13

    Most accelerator mass spectrometry measurements of 26Al utilize the Al- ion despite lower source currents compared with AlO- since the stable isobar 26Mg does not form elemental negative ions. A gas-filled magnet allows sufficient suppression of 26Mg thus enabling the use of the more intense 26AlO- ion. However, most AMS systems do not include a gas-filled magnet. We therefore explored the feasibility of suppressing 26Mg by using a post-accelerator stripping foil. With this approach, combined with the use of alternative cathode matrices, we were able to suppress 26Mg by a factor of twenty. This suppression was insufficient to enable themore » use of 26AlO-, however further refinement of our system may permit its use in the future.« less

  1. Particle acceleration at shocks in the inner heliosphere

    NASA Astrophysics Data System (ADS)

    Parker, Linda Neergaard

    multiple shock model is developed based in part on the box model of (Protheroe and Stanev, 1998; Moraal and Axford, 1983; Ball and Kirk, 1992; Drury et al. 1999) that accelerates particles at multiple shocks and decompresses the particles between shocks via two methods. The first method of decompression is based on the that used by Melrose and Pope (1993), which adiabatically decompresses particles between shocks. The second method solves the cosmic ray transport equation and adiabatically decompresses between shocks and includes the loss of particles through convection and diffusion. The transport method allows for the inclusion of a temporal variability and thus allows for a more representative frequency distribution of shocks. The transport method of decompression and loss is used to accelerate particles at seventy-three shocks in a thirty day time period. Comparisons with observations taken at 1 AU during the same time period are encouraging as the model is able to reproduce the observed amplitude of the accelerated particles and in part the variability. This work provides the basis for developing more sophisticated models that can be applied to a suite of observations

  2. Another Look at Strong Ground Motion Accelerations and Stress Drop

    NASA Astrophysics Data System (ADS)

    Baltay, A.; Prieto, G.; Ide, S.; Hanks, T. C.; Beroza, G. C.

    2010-12-01

    The relationship between earthquake stress drop and ground motion acceleration is central to seismic hazard analysis. We revisit measurements of root-mean-square (RMS) acceleration, arms, using KikNet accelerometer data from Japan. We directly measure RMS and peak acceleration, and estimate both apparent stress and corner frequencies using the empirical Green’s function (eGf) coda method of Baltay et al. [2010]. We predict armsfrom corner frequency and stress drop following McGuire and Hanks [1980] to compare with measurements. The theoretical relationship does a good job of predicting observed arms. We use four earthquake sequences in Japan to investigate the source parameters and accelerations: the 2008 Iwate-Miyagi earthquake; the off-Kamaishi repeating sequence; and the 2004 and 2007 Niigata events. In each data set, we choose events that are nearly co-located so that the path term to any station is constant. Small events are used as empirical Green’s functions to correct for propagation effects. For all sequences, we find that the apparent stress averages ~1 MPa for most events. Corner frequencies are consistent with Mo-1/3 scaling. We find the ratio of stress drop and apparent stress to be 5, consistent with the theoretical derivation of Singh and Ordaz [1994], using a Brune [1970] spectra. armsis theoretically proportional to stress drop and the inverse square root of the corner frequency. We show that this calculation can be used as a proxy for armsobservations from strong motion records, using recent data from the four earthquake sequences mentioned above. Even for the Iwate-Miyagi mainshock, which experienced over 4 g’s of acceleration, we find that apparent stress, stress drop and corner frequency follow expected scaling laws and support self-similarity.

  3. Teleportation with Multiple Accelerated Partners

    NASA Astrophysics Data System (ADS)

    Sagheer, A.; Hamdoun, H.; Metwally, N.

    2015-09-01

    As the current revolution in communication is underway, quantum teleportation can increase the level of security in quantum communication applications. In this paper, we present a quantum teleportation procedure that capable to teleport either accelerated or non-accelerated information through different quantum channels. These quantum channels are based on accelerated multi-qubit states, where each qubit of each of these channels represents a partner. Namely, these states are the W state, Greenberger-Horne-Zeilinger (GHZ) state, and the GHZ-like state. Here, we show that the fidelity of teleporting accelerated information is higher than the fidelity of teleporting non-accelerated information, both through a quantum channel that is based on accelerated state. Also, the comparison among the performance of these three channels shows that the degree of fidelity depends on type of the used channel, type of the measurement, and value of the acceleration. The result of comparison concludes that teleporting information through channel that is based on the GHZ state is more robust than teleporting information through channels that are based on the other two states. For future work, the proposed procedure can be generalized later to achieve communication through a wider quantum network.

  4. Demonstration of improved sensitivity of echo interferometers to gravitational acceleration

    NASA Astrophysics Data System (ADS)

    Mok, C.; Barrett, B.; Carew, A.; Berthiaume, R.; Beattie, S.; Kumarakrishnan, A.

    2013-08-01

    We have developed two configurations of an echo interferometer that rely on standing-wave excitation of a laser-cooled sample of rubidium atoms. Both configurations can be used to measure acceleration a along the axis of excitation. For a two-pulse configuration, the signal from the interferometer is modulated at the recoil frequency and exhibits a sinusoidal frequency chirp as a function of pulse spacing. In comparison, for a three-pulse stimulated-echo configuration, the signal is observed without recoil modulation and exhibits a modulation at a single frequency as a function of pulse spacing. The three-pulse configuration is less sensitive to effects of vibrations and magnetic field curvature, leading to a longer experimental time scale. For both configurations of the atom interferometer (AI), we show that a measurement of acceleration with a statistical precision of 0.5% can be realized by analyzing the shape of the echo envelope that has a temporal duration of a few microseconds. Using the two-pulse AI, we obtain measurements of acceleration that are statistically precise to 6 parts per million (ppm) on a 25 ms time scale. In comparison, using the three-pulse AI, we obtain measurements of acceleration that are statistically precise to 0.4 ppm on a time scale of 50 ms. A further statistical enhancement is achieved by analyzing the data across the echo envelope so that the statistical error is reduced to 75 parts per billion (ppb). The inhomogeneous field of a magnetized vacuum chamber limited the experimental time scale and resulted in prominent systematic effects. Extended time scales and improved signal-to-noise ratio observed in recent echo experiments using a nonmagnetic vacuum chamber suggest that echo techniques are suitable for a high-precision measurement of gravitational acceleration g. We discuss methods for reducing systematic effects and improving the signal-to-noise ratio. Simulations of both AI configurations with a time scale of 300 ms suggest

  5. Who Set the Fire? Determination of Arson Accelerants by GC-MS in an Instrumental Methods Course

    NASA Astrophysics Data System (ADS)

    Sodeman, David A.; Lillard, Sheri J.

    2001-09-01

    Forensic scenarios have advantages over traditional experiments in the instrumental laboratory from the perspectives of both teaching and learning. First, students feel that they are calculating more than just a number from their experiments and that their results have meaning. Second, we are teaching techniques that are used in the real world and students can no longer complain, "This is not how it is done in the real world." This experiment is designed for upper-division chemistry and chemical engineering majors taking an instrumental methods course. The experimental approach simulates the steps an arson investigator would take to determine if arson was the cause of a fire. Charred (unknown) samples of wood and five standards of liquid accelerants are prepared in sealed containers and presented to the students for headspace gas chromatography (GC) with quadrupole mass spectrometric (MS) detection. Students interpret the standards and the charred samples using chromatographic retention times and MS data. From this information, they determine which accelerant was used to start the fire. They are also asked to discuss differences between the chromatograms of the charred sample and the corresponding liquid accelerant.

  6. Accelerator Test of an Imaging Calorimeter

    NASA Technical Reports Server (NTRS)

    Christl, Mark J.; Adams, James H., Jr.; Binns, R. W.; Derrickson, J. H.; Fountain, W. F.; Howell, L. W.; Gregory, J. C.; Hink, P. L.; Israel, M. H.; Kippen, R. M.; hide

    2001-01-01

    The Imaging Calorimeter for ACCESS (ICA) utilizes a thin sampling calorimeter concept for direct measurements of high-energy cosmic rays. The ICA design uses arrays of small scintillating fibers to measure the energy and trajectory of the produced cascades. A test instrument has been developed to study the performance of this concept at accelerator energies and for comparison with simulations. Two test exposures have been completed using a CERN test beam. Some results from the accelerator tests are presented.

  7. Accelerate quasi Monte Carlo method for solving systems of linear algebraic equations through shared memory

    NASA Astrophysics Data System (ADS)

    Lai, Siyan; Xu, Ying; Shao, Bo; Guo, Menghan; Lin, Xiaola

    2017-04-01

    In this paper we study on Monte Carlo method for solving systems of linear algebraic equations (SLAE) based on shared memory. Former research demostrated that GPU can effectively speed up the computations of this issue. Our purpose is to optimize Monte Carlo method simulation on GPUmemoryachritecture specifically. Random numbers are organized to storein shared memory, which aims to accelerate the parallel algorithm. Bank conflicts can be avoided by our Collaborative Thread Arrays(CTA)scheme. The results of experiments show that the shared memory based strategy can speed up the computaions over than 3X at most.

  8. Electric rail gun projectile acceleration to high velocity

    NASA Technical Reports Server (NTRS)

    Bauer, D. P.; Mccormick, T. J.; Barber, J. P.

    1982-01-01

    Electric rail accelerators are being investigated for application in electric propulsion systems. Several electric propulsion applications require that the rail accelerator be capable of launching projectiles at velocities above 10 km/s. An experimental program was conducted to develop rail accelerator technology for high velocity projectile launch. Several 6 mm bore, 3 m long rail accelerators were fabricated. Projectiles with a mass of 0.2 g were accelerated by plasmas, carrying currents up to 150 kA. Experimental design and results are described. Results indicate that the accelerator performed as predicted for a fraction of the total projectile acceleration. The disparity between predicted and measured results are discussed.

  9. A new perspective on global mean sea level (GMSL) acceleration

    NASA Astrophysics Data System (ADS)

    Watson, Phil J.

    2016-06-01

    The vast body of contemporary climate change science is largely underpinned by the premise of a measured acceleration from anthropogenic forcings evident in key climate change proxies -- greenhouse gas emissions, temperature, and mean sea level. By virtue, over recent years, the issue of whether or not there is a measurable acceleration in global mean sea level has resulted in fierce, widespread professional, social, and political debate. Attempts to measure acceleration in global mean sea level (GMSL) have often used comparatively crude analysis techniques providing little temporal instruction on these key questions. This work proposes improved techniques to measure real-time velocity and acceleration based on five GMSL reconstructions spanning the time frame from 1807 to 2014 with substantially improved temporal resolution. While this analysis highlights key differences between the respective reconstructions, there is now more robust, convincing evidence of recent acceleration in the trend of GMSL.

  10. General purpose programmable accelerator board

    DOEpatents

    Robertson, Perry J.; Witzke, Edward L.

    2001-01-01

    A general purpose accelerator board and acceleration method comprising use of: one or more programmable logic devices; a plurality of memory blocks; bus interface for communicating data between the memory blocks and devices external to the board; and dynamic programming capabilities for providing logic to the programmable logic device to be executed on data in the memory blocks.

  11. Slip Ratio Estimation and Regenerative Brake Control for Decelerating Electric Vehicles without Detection of Vehicle Velocity and Acceleration

    NASA Astrophysics Data System (ADS)

    Suzuki, Toru; Fujimoto, Hiroshi

    In slip ratio control systems, it is necessary to detect the vehicle velocity in order to obtain the slip ratio. However, it is very difficult to measure this velocity directly. We have proposed slip ratio estimation and control methods that do not require the vehicle velocity with acceleration. In this paper, the slip ratio estimation and control methods are proposed without detecting the vehicle velocity and acceleration when it is decelerating. We carried out simulations and experiments by using an electric vehicle to verify the effectiveness of the proposed method.

  12. Autocalibrating motion-corrected wave-encoding for highly accelerated free-breathing abdominal MRI.

    PubMed

    Chen, Feiyu; Zhang, Tao; Cheng, Joseph Y; Shi, Xinwei; Pauly, John M; Vasanawala, Shreyas S

    2017-11-01

    To develop a motion-robust wave-encoding technique for highly accelerated free-breathing abdominal MRI. A comprehensive 3D wave-encoding-based method was developed to enable fast free-breathing abdominal imaging: (a) auto-calibration for wave-encoding was designed to avoid extra scan for coil sensitivity measurement; (b) intrinsic butterfly navigators were used to track respiratory motion; (c) variable-density sampling was included to enable compressed sensing; (d) golden-angle radial-Cartesian hybrid view-ordering was incorporated to improve motion robustness; and (e) localized rigid motion correction was combined with parallel imaging compressed sensing reconstruction to reconstruct the highly accelerated wave-encoded datasets. The proposed method was tested on six subjects and image quality was compared with standard accelerated Cartesian acquisition both with and without respiratory triggering. Inverse gradient entropy and normalized gradient squared metrics were calculated, testing whether image quality was improved using paired t-tests. For respiratory-triggered scans, wave-encoding significantly reduced residual aliasing and blurring compared with standard Cartesian acquisition (metrics suggesting P < 0.05). For non-respiratory-triggered scans, the proposed method yielded significantly better motion correction compared with standard motion-corrected Cartesian acquisition (metrics suggesting P < 0.01). The proposed methods can reduce motion artifacts and improve overall image quality of highly accelerated free-breathing abdominal MRI. Magn Reson Med 78:1757-1766, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

  13. Driver-witness electron beam acceleration in dielectric mm-scale capillaries

    NASA Astrophysics Data System (ADS)

    Lekomtsev, K.; Aryshev, A.; Tishchenko, A. A.; Shevelev, M.; Lyapin, A.; Boogert, S.; Karataev, P.; Terunuma, N.; Urakawa, J.

    2018-05-01

    We investigated a corrugated mm-scale capillary as a compact accelerating structure in the driver-witness acceleration scheme, and suggested a methodology to measure the acceleration of the witness bunch. The accelerating fields produced by the driver bunch and the energy spread of the witness bunch in a corrugated capillary and in a capillary with a constant inner radius were measured and simulated for both on-axis and off-axis beam propagation. Our simulations predicted a change in the accelerating field structure for the corrugated capillary. Also, an approximately twofold increase of the witness bunch energy gain on the first accelerating cycle was expected for both capillaries for the off-axis beam propagation. These results were confirmed in the experiment, and the maximum measured acceleration of 170 keV /m at 20 pC driver beam charge was achieved for off-axis beam propagation. The driver bunch showed an increase in energy spread of up to 11%, depending on the capillary geometry and beam propagation, with a suppression of the longitudinal energy spread in the witness bunch of up to 15%.

  14. In situ baking method for degassing of a kicker magnet in accelerator beam line

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

    Kamiya, Junichiro, E-mail: kamiya.junichiro@jaea.go.jp; Ogiwara, Norio; Yanagibashi, Toru

    In this study, the authors propose a new in situ degassing method by which only kicker magnets in the accelerator beam line are baked out without raising the temperature of the vacuum chamber to prevent unwanted thermal expansion of the chamber. By simply installing the heater and thermal radiation shield plates between the kicker magnet and the chamber wall, most of the heat flux from the heater directs toward the kicker magnet. The result of the verification test showed that each part of the kicker magnet was heated to above the target temperature with a small rise in the vacuummore » chamber temperature. A graphite heater was selected in this application to bake-out the kicker magnet in the beam line to ensure reliability and easy maintainability of the heater. The vacuum characteristics of graphite were suitable for heater operation in the beam line. A preliminary heat-up test conducted in the accelerator beam line also showed that each part of the kicker magnet was successfully heated and that thermal expansion of the chamber was negligibly small.« less

  15. Real-time measurement and monitoring of absorbed dose for electron beams

    NASA Astrophysics Data System (ADS)

    Korenev, Sergey; Korenev, Ivan; Rumega, Stanislav; Grossman, Leon

    2004-09-01

    The real-time method and system for measurement and monitoring of absorbed dose for industrial and research electron accelerators is considered in the report. The system was created on the basis of beam parameters method. The main concept of this method consists in the measurement of dissipated kinetic energy of electrons in the irradiated product, determination of number of electrons and mass of irradiated product in the same cell by following calculation of absorbed dose in the cell. The manual and automation systems for dose measurements are described. The systems are acceptable for all types of electron accelerators.

  16. Neck Strength Imbalance Correlates With Increased Head Acceleration in Soccer Heading

    PubMed Central

    Dezman, Zachary D.W.; Ledet, Eric H.; Kerr, Hamish A.

    2013-01-01

    Background: Soccer heading is using the head to directly contact the ball, often to advance the ball down the field or score. It is a skill fundamental to the game, yet it has come under scrutiny. Repeated subclinical effects of heading may compound over time, resulting in neurologic deficits. Greater head accelerations are linked to brain injury. Developing an understanding of how the neck muscles help stabilize and reduce head acceleration during impact may help prevent brain injury. Hypothesis: Neck strength imbalance correlates to increasing head acceleration during impact while heading a soccer ball. Study Design: Observational laboratory investigation. Methods: Sixteen Division I and II collegiate soccer players headed a ball in a controlled indoor laboratory setting while player motions were recorded by a 14-camera Vicon MX motion capture system. Neck flexor and extensor strength of each player was measured using a spring-type clinical dynamometer. Results: Players were served soccer balls by hand at a mean velocity of 4.29 m/s (±0.74 m/s). Players returned the ball to the server using a heading maneuver at a mean velocity of 5.48 m/s (±1.18 m/s). Mean neck strength difference was positively correlated with angular head acceleration (rho = 0.497; P = 0.05), with a trend toward significance for linear head acceleration (rho = 0.485; P = 0.057). Conclusion: This study suggests that symmetrical strength in neck flexors and extensors reduces head acceleration experienced during low-velocity heading in experienced collegiate players. Clinical Relevance: Balanced neck strength may reduce head acceleration cumulative subclinical injury. Since neck strength is a measureable and amenable strength training intervention, this may represent a modifiable intrinsic risk factor for injury. PMID:24459547

  17. Accelerated Compressed Sensing Based CT Image Reconstruction.

    PubMed

    Hashemi, SayedMasoud; Beheshti, Soosan; Gill, Patrick R; Paul, Narinder S; Cobbold, Richard S C

    2015-01-01

    In X-ray computed tomography (CT) an important objective is to reduce the radiation dose without significantly degrading the image quality. Compressed sensing (CS) enables the radiation dose to be reduced by producing diagnostic images from a limited number of projections. However, conventional CS-based algorithms are computationally intensive and time-consuming. We propose a new algorithm that accelerates the CS-based reconstruction by using a fast pseudopolar Fourier based Radon transform and rebinning the diverging fan beams to parallel beams. The reconstruction process is analyzed using a maximum-a-posterior approach, which is transformed into a weighted CS problem. The weights involved in the proposed model are calculated based on the statistical characteristics of the reconstruction process, which is formulated in terms of the measurement noise and rebinning interpolation error. Therefore, the proposed method not only accelerates the reconstruction, but also removes the rebinning and interpolation errors. Simulation results are shown for phantoms and a patient. For example, a 512 × 512 Shepp-Logan phantom when reconstructed from 128 rebinned projections using a conventional CS method had 10% error, whereas with the proposed method the reconstruction error was less than 1%. Moreover, computation times of less than 30 sec were obtained using a standard desktop computer without numerical optimization.

  18. Accelerated Compressed Sensing Based CT Image Reconstruction

    PubMed Central

    Hashemi, SayedMasoud; Beheshti, Soosan; Gill, Patrick R.; Paul, Narinder S.; Cobbold, Richard S. C.

    2015-01-01

    In X-ray computed tomography (CT) an important objective is to reduce the radiation dose without significantly degrading the image quality. Compressed sensing (CS) enables the radiation dose to be reduced by producing diagnostic images from a limited number of projections. However, conventional CS-based algorithms are computationally intensive and time-consuming. We propose a new algorithm that accelerates the CS-based reconstruction by using a fast pseudopolar Fourier based Radon transform and rebinning the diverging fan beams to parallel beams. The reconstruction process is analyzed using a maximum-a-posterior approach, which is transformed into a weighted CS problem. The weights involved in the proposed model are calculated based on the statistical characteristics of the reconstruction process, which is formulated in terms of the measurement noise and rebinning interpolation error. Therefore, the proposed method not only accelerates the reconstruction, but also removes the rebinning and interpolation errors. Simulation results are shown for phantoms and a patient. For example, a 512 × 512 Shepp-Logan phantom when reconstructed from 128 rebinned projections using a conventional CS method had 10% error, whereas with the proposed method the reconstruction error was less than 1%. Moreover, computation times of less than 30 sec were obtained using a standard desktop computer without numerical optimization. PMID:26167200

  19. Quasi-Steady Acceleration Direction Indicator in Three Dimensions

    NASA Technical Reports Server (NTRS)

    DeLombard, Richard; Nelson, Emily S.; Jules, Kenol

    2000-01-01

    Many materials processing and fluids physics experiments conducted in a microgravity environment require knowledge of the orientation of the low-frequency acceleration vector. This need becomes especially acute for space experiments such as directional solidification of a molten semiconductor, which is extremely sensitive to orientation and may involve tens of hours of operations of a materials furnace. These low-frequency acceleration data have been measured for many Shuttle missions with the Orbital Acceleration Research Experiment. Previous attempts at using fluid chambers for acceleration measurements have met with limited success due to pointing and vehicle attitude complications. An acceleration direction indicator is described, which is comprised of two orthogonal short cylinders of fluid, each with a small bubble. The motion and the position of the bubble within the chamber will indicate the direction of the acceleration experienced at the sensor location. The direction of the acceleration vector may then be calculated from these data. The frequency response of such an instrument may be tailored for particular experiments with the proper selection of fluid and gas parameters, surface type, and geometry. A three-dimensional system for sensing and displaying the low-frequency acceleration direction via an innovative technique described in this paper has advantages in terms of size, mass, and power compared with electronic instrumentation systems.

  20. Comparison of measured with calculated dose distribution from a 120-MeV electron beam from a laser-plasma accelerator.

    PubMed

    Lundh, O; Rechatin, C; Faure, J; Ben-Ismaïl, A; Lim, J; De Wagter, C; De Neve, W; Malka, V

    2012-06-01

    To evaluate the dose distribution of a 120-MeV laser-plasma accelerated electron beam which may be of potential interest for high-energy electron radiation therapy. In the interaction between an intense laser pulse and a helium gas jet, a well collimated electron beam with very high energy is produced. A secondary laser beam is used to optically control and to tune the electron beam energy and charge. The potential use of this beam for radiation treatment is evaluated experimentally by measurements of dose deposition in a polystyrene phantom. The results are compared to Monte Carlo simulations using the geant4 code. It has been shown that the laser-plasma accelerated electron beam can deliver a peak dose of more than 1 Gy at the entrance of the phantom in a single laser shot by direct irradiation, without the use of intermediate magnetic transport or focusing. The dose distribution is peaked on axis, with narrow lateral penumbra. Monte Carlo simulations of electron beam propagation and dose deposition indicate that the propagation of the intense electron beam (with large self-fields) can be described by standard models that exclude collective effects in the response of the material. The measurements show that the high-energy electron beams produced by an optically injected laser-plasma accelerator can deliver high enough dose at penetration depths of interest for electron beam radiotherapy of deep-seated tumors. Many engineering issues must be resolved before laser-accelerated electrons can be used for cancer therapy, but they also represent exciting challenges for future research. © 2012 American Association of Physicists in Medicine.

  1. Accelerated Profile HMM Searches

    PubMed Central

    Eddy, Sean R.

    2011-01-01

    Profile hidden Markov models (profile HMMs) and probabilistic inference methods have made important contributions to the theory of sequence database homology search. However, practical use of profile HMM methods has been hindered by the computational expense of existing software implementations. Here I describe an acceleration heuristic for profile HMMs, the “multiple segment Viterbi” (MSV) algorithm. The MSV algorithm computes an optimal sum of multiple ungapped local alignment segments using a striped vector-parallel approach previously described for fast Smith/Waterman alignment. MSV scores follow the same statistical distribution as gapped optimal local alignment scores, allowing rapid evaluation of significance of an MSV score and thus facilitating its use as a heuristic filter. I also describe a 20-fold acceleration of the standard profile HMM Forward/Backward algorithms using a method I call “sparse rescaling”. These methods are assembled in a pipeline in which high-scoring MSV hits are passed on for reanalysis with the full HMM Forward/Backward algorithm. This accelerated pipeline is implemented in the freely available HMMER3 software package. Performance benchmarks show that the use of the heuristic MSV filter sacrifices negligible sensitivity compared to unaccelerated profile HMM searches. HMMER3 is substantially more sensitive and 100- to 1000-fold faster than HMMER2. HMMER3 is now about as fast as BLAST for protein searches. PMID:22039361

  2. Amplitude-dependent orbital period in alternating gradient accelerators

    DOE PAGES

    Machida, S.; Kelliher, D. J.; Edmonds, C. S.; ...

    2016-03-16

    Orbital period in a ring accelerator and time of flight in a linear accelerator depend on the amplitude of betatron oscillations. The variation is negligible in ordinary particle accelerators with relatively small beam emittance. In an accelerator for large emittance beams like muons and unstable nuclei, however, this effect cannot be ignored. In this study, we measured orbital period in a linear non-scaling fixed-field alternating-gradient accelerator, which is a candidate for muon acceleration, and compared it with the theoretical prediction. The good agreement between them gives important ground for the design of particle accelerators for a new generation of particlemore » and nuclear physics experiments.« less

  3. Measurements in Transitional Boundary Layers Under High Free-Stream Turbulence and Strong Acceleration Conditions

    NASA Technical Reports Server (NTRS)

    Volino, Ralph J.; Simon, Terrence W.

    1995-01-01

    Measurements from transitional, heated boundary layers along a concave-curved test wall are presented and discussed. A boundary layer subject to low free-stream turbulence intensity (FSTI), which contains stationary streamwise (Gortler) vortices, is documented. The low FSTI measurements are followed by measurements in boundary layers subject to high (initially 8%) free-stream turbulence intensity and moderate to strong streamwise acceleration. Conditions were chosen to simulate those present on the downstream half of the pressure side of a gas turbine airfoil. Mean flow characteristics as well as turbulence statistics, including the turbulent shear stress, turbulent heat flux, and turbulent Prandtl number, are documented. A technique called "octant analysis" is introduced and applied to several cases from the literature as well as to data from the present study. Spectral analysis was applied to describe the effects of turbulence scales of different sizes during transition. To the authors'knowledge, this is the first detailed documentation of boundary layer transition under such high free-stream turbulence conditions.

  4. EDITORIAL: Metrological Aspects of Accelerator Technology and High Energy Physics Experiments

    NASA Astrophysics Data System (ADS)

    Romaniuk, Ryszard S.; Pozniak, Krzysztof T.

    2007-08-01

    The subject of this special feature in Measurement Science and Technology concerns measurement methods, devices and subsystems, both hardware and software aspects, applied in large experiments of high energy physics (HEP) and superconducting RF accelerator technology (SRF). These experiments concern mainly the physics of elementary particles or the building of new machines and detectors. The papers present practical examples of applied solutions in large, contemporary, international research projects such as HERA, LHC, FLASH, XFEL, ILC and others. These machines are unique in their global scale and consist of extremely dedicated apparatus. The apparatus is characterized by very large dimensions, a considerable use of resources and a high level of overall technical complexity. They possess a large number of measurement channels (ranging from thousands to over 100 million), are characterized by fast of processing of measured data and high measurement accuracies, and work in quite adverse environments. The measurement channels cooperate with a large number of different sensors of momenta, energies, trajectories of elementary particles, electron, proton and photon beam profiles, accelerating fields in resonant cavities, and many others. The provision of high quality measurement systems requires the designers to use only the most up-to-date technical solutions, measurement technologies, components and devices. Research work in these demanding fields is a natural birthplace of new measurement methods, new data processing and acquisition algorithms, complex, networked measurement system diagnostics and monitoring. These developments are taking place in both hardware and software layers. The chief intention of this special feature is that the papers represent equally some of the most current metrology research problems in HEP and SRF. The accepted papers have been divided into four topical groups: superconducting cavities (4 papers), low level RF systems (8 papers

  5. Torque-based optimal acceleration control for electric vehicle

    NASA Astrophysics Data System (ADS)

    Lu, Dongbin; Ouyang, Minggao

    2014-03-01

    The existing research of the acceleration control mainly focuses on an optimization of the velocity trajectory with respect to a criterion formulation that weights acceleration time and fuel consumption. The minimum-fuel acceleration problem in conventional vehicle has been solved by Pontryagin's maximum principle and dynamic programming algorithm, respectively. The acceleration control with minimum energy consumption for battery electric vehicle(EV) has not been reported. In this paper, the permanent magnet synchronous motor(PMSM) is controlled by the field oriented control(FOC) method and the electric drive system for the EV(including the PMSM, the inverter and the battery) is modeled to favor over a detailed consumption map. The analytical algorithm is proposed to analyze the optimal acceleration control and the optimal torque versus speed curve in the acceleration process is obtained. Considering the acceleration time, a penalty function is introduced to realize a fast vehicle speed tracking. The optimal acceleration control is also addressed with dynamic programming(DP). This method can solve the optimal acceleration problem with precise time constraint, but it consumes a large amount of computation time. The EV used in simulation and experiment is a four-wheel hub motor drive electric vehicle. The simulation and experimental results show that the required battery energy has little difference between the acceleration control solved by analytical algorithm and that solved by DP, and is greatly reduced comparing with the constant pedal opening acceleration. The proposed analytical and DP algorithms can minimize the energy consumption in EV's acceleration process and the analytical algorithm is easy to be implemented in real-time control.

  6. Accelerating rates of cognitive decline and imaging markers associated with β-amyloid pathology

    PubMed Central

    Mattsson, Niklas; Mackin, R. Scott; Schöll, Michael; Nosheny, Rachel L.; Tosun, Duygu; Donohue, Michael C.; Aisen, Paul S.; Jagust, William J.; Weiner, Michael W.

    2016-01-01

    Objective: To estimate points along the spectrum of β-amyloid pathology at which rates of change of several measures of neuronal injury and cognitive decline begin to accelerate. Methods: In 460 patients with mild cognitive impairment (MCI), we estimated the points at which rates of florbetapir PET, fluorodeoxyglucose (FDG) PET, MRI, and cognitive and functional decline begin to accelerate with respect to baseline CSF Aβ42. Points of initial acceleration in rates of decline were estimated using mixed-effects regression. Results: Rates of neuronal injury and cognitive and even functional decline accelerate substantially before the conventional threshold for amyloid positivity, with rates of florbetapir PET and FDG PET accelerating early. Temporal lobe atrophy rates also accelerate prior to the threshold, but not before the acceleration of cognitive and functional decline. Conclusions: A considerable proportion of patients with MCI would not meet inclusion criteria for a trial using the current threshold for amyloid positivity, even though on average, they are experiencing cognitive/functional decline associated with prethreshold levels of CSF Aβ42. Future trials in early Alzheimer disease might consider revising the criteria regarding β-amyloid thresholds to include the range of amyloid associated with the first signs of accelerating rates of decline. PMID:27164667

  7. Accelerating rates of cognitive decline and imaging markers associated with β-amyloid pathology

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

    Insel, Philip S.; Mattsson, Niklas; Mackin, R. Scott

    Objective: Our objective is to estimate points along the spectrum of β-amyloid pathology at which rates of change of several measures of neuronal injury and cognitive decline begin to accelerate. Methods: In 460 patients with mild cognitive impairment (MCI), we estimated the points at which rates of florbetapir PET, fluorodeoxyglucose (FDG) PET, MRI, and cognitive and functional decline begin to accelerate with respect to baseline CSF Aβ 42. Points of initial acceleration in rates of decline were estimated using mixed-effects regression. Results: Rates of neuronal injury and cognitive and even functional decline accelerate substantially before the conventional threshold for amyloidmore » positivity, with rates of florbetapir PET and FDG PET accelerating early. Temporal lobe atrophy rates also accelerate prior to the threshold, but not before the acceleration of cognitive and functional decline. Conclusions: A considerable proportion of patients with MCI would not meet inclusion criteria for a trial using the current threshold for amyloid positivity, even though on average, they are experiencing cognitive/functional decline associated with prethreshold levels of CSF Aβ 42. Lastly, future trials in early Alzheimer disease might consider revising the criteria regarding β-amyloid thresholds to include the range of amyloid associated with the first signs of accelerating rates of decline.« less

  8. Accelerating rates of cognitive decline and imaging markers associated with β-amyloid pathology

    DOE PAGES

    Insel, Philip S.; Mattsson, Niklas; Mackin, R. Scott; ...

    2016-04-15

    Objective: Our objective is to estimate points along the spectrum of β-amyloid pathology at which rates of change of several measures of neuronal injury and cognitive decline begin to accelerate. Methods: In 460 patients with mild cognitive impairment (MCI), we estimated the points at which rates of florbetapir PET, fluorodeoxyglucose (FDG) PET, MRI, and cognitive and functional decline begin to accelerate with respect to baseline CSF Aβ 42. Points of initial acceleration in rates of decline were estimated using mixed-effects regression. Results: Rates of neuronal injury and cognitive and even functional decline accelerate substantially before the conventional threshold for amyloidmore » positivity, with rates of florbetapir PET and FDG PET accelerating early. Temporal lobe atrophy rates also accelerate prior to the threshold, but not before the acceleration of cognitive and functional decline. Conclusions: A considerable proportion of patients with MCI would not meet inclusion criteria for a trial using the current threshold for amyloid positivity, even though on average, they are experiencing cognitive/functional decline associated with prethreshold levels of CSF Aβ 42. Lastly, future trials in early Alzheimer disease might consider revising the criteria regarding β-amyloid thresholds to include the range of amyloid associated with the first signs of accelerating rates of decline.« less

  9. Verification of Non-Invasive Blood Glucose Measurement Method Based on Pulse Wave Signal Detected by FBG Sensor System.

    PubMed

    Kurasawa, Shintaro; Koyama, Shouhei; Ishizawa, Hiroaki; Fujimoto, Keisaku; Chino, Shun

    2017-11-23

    This paper describes and verifies a non-invasive blood glucose measurement method using a fiber Bragg grating (FBG) sensor system. The FBG sensor is installed on the radial artery, and the strain (pulse wave) that is propagated from the heartbeat is measured. The measured pulse wave signal was used as a collection of feature vectors for multivariate analysis aiming to determine the blood glucose level. The time axis of the pulse wave signal was normalized by two signal processing methods: the shortest-time-cut process and 1-s-normalization process. The measurement accuracy of the calculated blood glucose level was compared with the accuracy of these signal processing methods. It was impossible to calculate a blood glucose level exceeding 200 mg/dL in the calibration curve that was constructed by the shortest-time-cut process. In the 1-s-normalization process, the measurement accuracy of the blood glucose level was improved, and a blood glucose level exceeding 200 mg/dL could be calculated. By verifying the loading vector of each calibration curve to calculate the blood glucose level with a high measurement accuracy, we found the gradient of the peak of the pulse wave at the acceleration plethysmogram greatly affected.

  10. An Experimental Study on the Fabrication of Glass-based Acceleration Sensor Body Using Micro Powder Blasting Method

    PubMed Central

    Park, Dong-Sam; Yun, Dae-Jin; Cho, Myeong-Woo; Shin, Bong-Cheol

    2007-01-01

    This study investigated the feasibility of the micro powder blasting technique for the micro fabrication of sensor structures using the Pyrex glass to replace the existing silicon-based acceleration sensor fabrication processes. As the preliminary experiments, the effects of the blasting pressure, the mass flow rate of abrasive and the number of nozzle scanning times on erosion depth of the Pyrex and the soda lime glasses were examined. From the experimental results, optimal blasting conditions were selected for the Pyrex glass machining. The dimensions of the designed glass sensor was 1.7×1.7×0.6mm for the vibrating mass, and 2.9×0.7×0.2mm for the cantilever beam. The machining results showed that the dimensional errors of the machined glass sensor ranged from 3 μm in minimum to 20 μm in maximum. These results imply that the micro powder blasting method can be applied for the micromachining of glass-based acceleration sensors to replace the exiting method.

  11. Stochastic modeling of Lagrangian accelerations

    NASA Astrophysics Data System (ADS)

    Reynolds, Andy

    2002-11-01

    It is shown how Sawford's second-order Lagrangian stochastic model (Phys. Fluids A 3, 1577-1586, 1991) for fluid-particle accelerations can be combined with a model for the evolution of the dissipation rate (Pope and Chen, Phys. Fluids A 2, 1437-1449, 1990) to produce a Lagrangian stochastic model that is consistent with both the measured distribution of Lagrangian accelerations (La Porta et al., Nature 409, 1017-1019, 2001) and Kolmogorov's similarity theory. The later condition is found not to be satisfied when a constant dissipation rate is employed and consistency with prescribed acceleration statistics is enforced through fulfilment of a well-mixed condition.

  12. Experimental Methods Using Photogrammetric Techniques for Parachute Canopy Shape Measurements

    NASA Technical Reports Server (NTRS)

    Jones, Thomas W.; Downey, James M.; Lunsford, Charles B.; Desabrais, Kenneth J.; Noetscher, Gregory

    2007-01-01

    NASA Langley Research Center in partnership with the U.S. Army Natick Soldier Center has collaborated on the development of a payload instrumentation package to record the physical parameters observed during parachute air drop tests. The instrumentation package records a variety of parameters including canopy shape, suspension line loads, payload 3-axis acceleration, and payload velocity. This report discusses the instrumentation design and development process, as well as the photogrammetric measurement technique used to provide shape measurements. The scaled model tests were conducted in the NASA Glenn Plum Brook Space Propulsion Facility, OH.

  13. On isocentre adjustment and quality control in linear accelerator based radiosurgery with circular collimators and room lasers.

    PubMed

    Treuer, H; Hoevels, M; Luyken, K; Gierich, A; Kocher, M; Müller, R P; Sturm, V

    2000-08-01

    We have developed a densitometric method for measuring the isocentric accuracy and the accuracy of marking the isocentre position for linear accelerator based radiosurgery with circular collimators and room lasers. Isocentric shots are used to determine the accuracy of marking the isocentre position with room lasers and star shots are used to determine the wobble of the gantry and table rotation movement, the effect of gantry sag, the stereotactic collimator alignment, and the minimal distance between gantry and table rotation axes. Since the method is based on densitometric measurements, beam spot stability is implicitly tested. The method developed is also suitable for quality assurance and has proved to be useful in optimizing isocentric accuracy. The method is simple to perform and only requires a film box and film scanner for instrumentation. Thus, the method has the potential to become widely available and may therefore be useful in standardizing the description of linear accelerator based radiosurgical systems.

  14. Evaluation of accelerated iterative x-ray CT image reconstruction using floating point graphics hardware.

    PubMed

    Kole, J S; Beekman, F J

    2006-02-21

    Statistical reconstruction methods offer possibilities to improve image quality as compared with analytical methods, but current reconstruction times prohibit routine application in clinical and micro-CT. In particular, for cone-beam x-ray CT, the use of graphics hardware has been proposed to accelerate the forward and back-projection operations, in order to reduce reconstruction times. In the past, wide application of this texture hardware mapping approach was hampered owing to limited intrinsic accuracy. Recently, however, floating point precision has become available in the latest generation commodity graphics cards. In this paper, we utilize this feature to construct a graphics hardware accelerated version of the ordered subset convex reconstruction algorithm. The aims of this paper are (i) to study the impact of using graphics hardware acceleration for statistical reconstruction on the reconstructed image accuracy and (ii) to measure the speed increase one can obtain by using graphics hardware acceleration. We compare the unaccelerated algorithm with the graphics hardware accelerated version, and for the latter we consider two different interpolation techniques. A simulation study of a micro-CT scanner with a mathematical phantom shows that at almost preserved reconstructed image accuracy, speed-ups of a factor 40 to 222 can be achieved, compared with the unaccelerated algorithm, and depending on the phantom and detector sizes. Reconstruction from physical phantom data reconfirms the usability of the accelerated algorithm for practical cases.

  15. Radioisotope Dating with Accelerators.

    ERIC Educational Resources Information Center

    Muller, Richard A.

    1979-01-01

    Explains a new method of detecting radioactive isotopes by counting their accelerated ions rather than the atoms that decay during the counting period. This method increases the sensitivity by several orders of magnitude, and allows one to find the ages of much older and smaller samples. (GA)

  16. World Pendulum--A Distributed Remotely Controlled Laboratory (RCL) to Measure the Earth's Gravitational Acceleration Depending on Geographical Latitude

    ERIC Educational Resources Information Center

    Grober, S.; Vetter, M.; Eckert, B.; Jodl, H.-J.

    2007-01-01

    We suggest that different string pendulums are positioned at different locations on Earth and measure at each place the gravitational acceleration (accuracy [delta]g is approximately equal to 0.01 m s[superscript -2]). Each pendulum can be remotely controlled via the internet by a computer located somewhere on Earth. The theoretical part describes…

  17. A multiresolution approach for the convergence acceleration of multivariate curve resolution methods.

    PubMed

    Sawall, Mathias; Kubis, Christoph; Börner, Armin; Selent, Detlef; Neymeyr, Klaus

    2015-09-03

    Modern computerized spectroscopic instrumentation can result in high volumes of spectroscopic data. Such accurate measurements rise special computational challenges for multivariate curve resolution techniques since pure component factorizations are often solved via constrained minimization problems. The computational costs for these calculations rapidly grow with an increased time or frequency resolution of the spectral measurements. The key idea of this paper is to define for the given high-dimensional spectroscopic data a sequence of coarsened subproblems with reduced resolutions. The multiresolution algorithm first computes a pure component factorization for the coarsest problem with the lowest resolution. Then the factorization results are used as initial values for the next problem with a higher resolution. Good initial values result in a fast solution on the next refined level. This procedure is repeated and finally a factorization is determined for the highest level of resolution. The described multiresolution approach allows a considerable convergence acceleration. The computational procedure is analyzed and is tested for experimental spectroscopic data from the rhodium-catalyzed hydroformylation together with various soft and hard models. Copyright © 2015 Elsevier B.V. All rights reserved.

  18. Flow accelerated organic coating degradation

    NASA Astrophysics Data System (ADS)

    Zhou, Qixin

    Applying organic coatings is a common and the most cost effective way to protect metallic objects and structures from corrosion. Water entry into coating-metal interface is usually the main cause for the deterioration of organic coatings, which leads to coating delamination and underfilm corrosion. Recently, flowing fluids over sample surface have received attention due to their capability to accelerate material degradation. A plethora of works has focused on the flow induced metal corrosion, while few studies have investigated the flow accelerated organic coating degradation. Flowing fluids above coating surface affect corrosion by enhancing the water transport and abrading the surface due to fluid shear. Hence, it is of great importance to understand the influence of flowing fluids on the degradation of corrosion protective organic coatings. In this study, a pigmented marine coating and several clear coatings were exposed to the laminar flow and stationary immersion. The laminar flow was pressure driven and confined in a flow channel. A 3.5 wt% sodium chloride solution and pure water was employed as the working fluid with a variety of flow rates. The corrosion protective properties of organic coatings were monitored inline by Electrochemical Impedance Spectroscopy (EIS) measurement. Equivalent circuit models were employed to interpret the EIS spectra. The time evolution of coating resistance and capacitance obtained from the model was studied to demonstrate the coating degradation. Thickness, gloss, and other topography characterizations were conducted to facilitate the assessment of the corrosion. The working fluids were characterized by Fourier Transform Infrared Spectrometer (FTIR) and conductivity measurement. The influence of flow rate, fluid shear, fluid composition, and other effects in the coating degradation were investigated. We conclude that flowing fluid on the coating surface accelerates the transport of water, oxygen, and ions into the coating, as

  19. Practical method and device for enhancing pulse contrast ratio for lasers and electron accelerators

    DOEpatents

    Zhang, Shukui; Wilson, Guy

    2014-09-23

    An apparatus and method for enhancing pulse contrast ratios for drive lasers and electron accelerators. The invention comprises a mechanical dual-shutter system wherein the shutters are placed sequentially in series in a laser beam path. Each shutter of the dual shutter system has an individually operated trigger for opening and closing the shutter. As the triggers are operated individually, the delay between opening and closing first shutter and opening and closing the second shutter is variable providing for variable differential time windows and enhancement of pulse contrast ratio.

  20. Variable Acceleration Force Calibration System (VACS)

    NASA Technical Reports Server (NTRS)

    Rhew, Ray D.; Parker, Peter A.; Johnson, Thomas H.; Landman, Drew

    2014-01-01

    Conventionally, force balances have been calibrated manually, using a complex system of free hanging precision weights, bell cranks, and/or other mechanical components. Conventional methods may provide sufficient accuracy in some instances, but are often quite complex and labor-intensive, requiring three to four man-weeks to complete each full calibration. To ensure accuracy, gravity-based loading is typically utilized. However, this often causes difficulty when applying loads in three simultaneous, orthogonal axes. A complex system of levers, cranks, and cables must be used, introducing increased sources of systematic error, and significantly increasing the time and labor intensity required to complete the calibration. One aspect of the VACS is a method wherein the mass utilized for calibration is held constant, and the acceleration is changed to thereby generate relatively large forces with relatively small test masses. Multiple forces can be applied to a force balance without changing the test mass, and dynamic forces can be applied by rotation or oscillating acceleration. If rotational motion is utilized, a mass is rigidly attached to a force balance, and the mass is exposed to a rotational field. A large force can be applied by utilizing a large rotational velocity. A centrifuge or rotating table can be used to create the rotational field, and fixtures can be utilized to position the force balance. The acceleration may also be linear. For example, a table that moves linearly and accelerates in a sinusoidal manner may also be utilized. The test mass does not have to move in a path that is parallel to the ground, and no re-leveling is therefore required. Balance deflection corrections may be applied passively by monitoring the orientation of the force balance with a three-axis accelerometer package. Deflections are measured during each test run, and adjustments with respect to the true applied load can be made during the post-processing stage. This paper will

  1. A method of measuring and correcting tilt of anti - vibration wind turbines based on screening algorithm

    NASA Astrophysics Data System (ADS)

    Xiao, Zhongxiu

    2018-04-01

    A Method of Measuring and Correcting Tilt of Anti - vibration Wind Turbines Based on Screening Algorithm is proposed in this paper. First of all, we design a device which the core is the acceleration sensor ADXL203, the inclination is measured by installing it on the tower of the wind turbine as well as the engine room. Next using the Kalman filter algorithm to filter effectively by establishing a state space model for signal and noise. Then we use matlab for simulation. Considering the impact of the tower and nacelle vibration on the collected data, the original data and the filtering data are classified and stored by the Screening algorithm, then filter the filtering data to make the output data more accurate. Finally, we eliminate installation errors by using algorithm to achieve the tilt correction. The device based on this method has high precision, low cost and anti-vibration advantages. It has a wide range of application and promotion value.

  2. Time Recovery for a Complex Process Using Accelerated Dynamics.

    PubMed

    Paz, S Alexis; Leiva, Ezequiel P M

    2015-04-14

    The hyperdynamics method (HD) developed by Voter (J. Chem. Phys. 1996, 106, 4665) sets the theoretical basis to construct an accelerated simulation scheme that holds the time scale information. Since HD is based on transition state theory, pseudoequilibrium conditions (PEC) must be satisfied before any system in a trapped state may be accelerated. As the system evolves, many trapped states may appear, and the PEC must be assumed in each one to accelerate the escape. However, since the system evolution is a priori unknown, the PEC cannot be permanently assumed to be true. Furthermore, the different parameters of the bias function used may need drastic recalibration during this evolution. To overcome these problems, we present a general scheme to switch between HD and conventional molecular dynamics (MD) in an automatic fashion during the simulation. To decide when HD should start and finish, criteria based on the energetic properties of the system are introduced. On the other hand, a very simple bias function is proposed, leading to a straightforward on-the-fly set up of the required parameters. A way to measure the quality of the simulation is suggested. The efficiency of the present hybrid HD-MD method is tested for a two-dimensional model potential and for the coalescence process of two nanoparticles. In spite of the important complexity of the latter system (165 degrees of freedoms), some relevant mechanistic properties were recovered within the present method.

  3. Computational Accelerator Physics. Proceedings

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

    Bisognano, J.J.; Mondelli, A.A.

    1997-04-01

    The sixty two papers appearing in this volume were presented at CAP96, the Computational Accelerator Physics Conference held in Williamsburg, Virginia from September 24{minus}27,1996. Science Applications International Corporation (SAIC) and the Thomas Jefferson National Accelerator Facility (Jefferson lab) jointly hosted CAP96, with financial support from the U.S. department of Energy`s Office of Energy Research and the Office of Naval reasearch. Topics ranged from descriptions of specific codes to advanced computing techniques and numerical methods. Update talks were presented on nearly all of the accelerator community`s major electromagnetic and particle tracking codes. Among all papers, thirty of them are abstracted formore » the Energy Science and Technology database.(AIP)« less

  4. Application of gamma-ray radiography and gravimetric measurements after accelerated corrosion tests of steel embedded in mortar

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

    Duffó, Gustavo, E-mail: duffo@cnea.gov.ar; Consejo Nacional de Investigaciones Científicas y Técnicas; Universidad Nacional de San Martín, Av. Gral. Paz 1499, 1650 San Martín, Buenos Aires

    2015-08-15

    The accelerated corrosion by the impressed current technique is widely used in studies of concrete durability since it has the advantage that tests can be carried out within reasonable periods of time. In the present work the relationship between the applied current density and the resulting damage on the reinforcing steel, by applying optical microscopy, scanning electron microscopy, gamma-ray radiography and gravimetric measurements, was studied by means of the implementation of accelerated corrosion tests on reinforced mortar. The results show that the efficiency of the applied current is between 1 and 77%, regardless of the applied current density, the water/cementmore » ratio and the mortar cover depth of the specimens. The results show the applicability of the gamma-ray radiography technique to detect localized corrosion of steel rebars in laboratory specimens.« less

  5. A Numerical Method for the Simulation of Skew Brownian Motion and its Application to Diffusive Shock Acceleration of Charged Particles

    NASA Astrophysics Data System (ADS)

    McEvoy, Erica L.

    Stochastic differential equations are becoming a popular tool for modeling the transport and acceleration of cosmic rays in the heliosphere. In diffusive shock acceleration, cosmic rays diffuse across a region of discontinuity where the up- stream diffusion coefficient abruptly changes to the downstream value. Because the method of stochastic integration has not yet been developed to handle these types of discontinuities, I utilize methods and ideas from probability theory to develop a conceptual framework for the treatment of such discontinuities. Using this framework, I then produce some simple numerical algorithms that allow one to incorporate and simulate a variety of discontinuities (or boundary conditions) using stochastic integration. These algorithms were then modified to create a new algorithm which incorporates the discontinuous change in diffusion coefficient found in shock acceleration (known as Skew Brownian Motion). The originality of this algorithm lies in the fact that it is the first of its kind to be statistically exact, so that one obtains accuracy without the use of approximations (other than the machine precision error). I then apply this algorithm to model the problem of diffusive shock acceleration, modifying it to incorporate the additional effect of the discontinuous flow speed profile found at the shock. A steady-state solution is obtained that accurately simulates this phenomenon. This result represents a significant improvement over previous approximation algorithms, and will be useful for the simulation of discontinuous diffusion processes in other fields, such as biology and finance.

  6. Accuracy of ringless casting and accelerated wax-elimination technique: a comparative in vitro study.

    PubMed

    Prasad, Rahul; Al-Keraif, Abdulaziz Abdullah; Kathuria, Nidhi; Gandhi, P V; Bhide, S V

    2014-02-01

    The purpose of this study was to determine whether the ringless casting and accelerated wax-elimination techniques can be combined to offer a cost-effective, clinically acceptable, and time-saving alternative for fabricating single unit castings in fixed prosthodontics. Sixty standardized wax copings were fabricated on a type IV stone replica of a stainless steel die. The wax patterns were divided into four groups. The first group was cast using the ringless investment technique and conventional wax-elimination method; the second group was cast using the ringless investment technique and accelerated wax-elimination method; the third group was cast using the conventional metal ring investment technique and conventional wax-elimination method; the fourth group was cast using the metal ring investment technique and accelerated wax-elimination method. The vertical marginal gap was measured at four sites per specimen, using a digital optical microscope at 100× magnification. The results were analyzed using two-way ANOVA to determine statistical significance. The vertical marginal gaps of castings fabricated using the ringless technique (76.98 ± 7.59 μm) were significantly less (p < 0.05) than those castings fabricated using the conventional metal ring technique (138.44 ± 28.59 μm); however, the vertical marginal gaps of the conventional (102.63 ± 36.12 μm) and accelerated wax-elimination (112.79 ± 38.34 μm) castings were not statistically significant (p > 0.05). The ringless investment technique can produce castings with higher accuracy and can be favorably combined with the accelerated wax-elimination method as a vital alternative to the time-consuming conventional technique of casting restorations in fixed prosthodontics. © 2013 by the American College of Prosthodontists.

  7. Ferroelectric ceramics in a pyroelectric accelerator

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

    Shchagin, A. V., E-mail: shchagin@kipt.kharkov.ua; Belgorod State University, Belgorod 308015; Miroshnik, V. S.

    2015-12-07

    The applicability of polarized ferroelectric ceramics as a pyroelectric in a pyroelectric accelerator is shown by experiments. The spectra of X-ray radiation of energy up to tens of keV, generated by accelerated electrons, have been measured on heating and cooling of the ceramics in vacuum. It is suggested that curved layers of polarized ferroelectric ceramics be used as elements of ceramic pyroelectric accelerators. Besides, nanotubes and nanowires manufactured from ferroelectric ceramics are proposed for the use in nanometer-scale ceramic pyroelectric nanoaccelerators for future applications in nanotechnologies.

  8. On the Use of Accelerated Test Methods for Characterization of Advanced Composite Materials

    NASA Technical Reports Server (NTRS)

    Gates, Thomas S.

    2003-01-01

    A rational approach to the problem of accelerated testing for material characterization of advanced polymer matrix composites is discussed. The experimental and analytical methods provided should be viewed as a set of tools useful in the screening of material systems for long-term engineering properties in aerospace applications. Consideration is given to long-term exposure in extreme environments that include elevated temperature, reduced temperature, moisture, oxygen, and mechanical load. Analytical formulations useful for predictive models that are based on the principles of time-based superposition are presented. The need for reproducible mechanisms, indicator properties, and real-time data are outlined as well as the methodologies for determining specific aging mechanisms.

  9. A 6% measurement of the Hubble parameter at z ∼0.45: direct evidence of the epoch of cosmic re-acceleration

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

    Moresco, Michele; Cimatti, Andrea; Citro, Annalisa

    2016-05-01

    Deriving the expansion history of the Universe is a major goal of modern cosmology. To date, the most accurate measurements have been obtained with Type Ia Supernovae (SNe) and Baryon Acoustic Oscillations (BAO), providing evidence for the existence of a transition epoch at which the expansion rate changes from decelerated to accelerated. However, these results have been obtained within the framework of specific cosmological models that must be implicitly or explicitly assumed in the measurement. It is therefore crucial to obtain measurements of the accelerated expansion of the Universe independently of assumptions on cosmological models. Here we exploit the unprecedentedmore » statistics provided by the Baryon Oscillation Spectroscopic Survey (BOSS, [1-3]) Data Release 9 to provide new constraints on the Hubble parameter H ( z ) using the cosmic chronometers approach. We extract a sample of more than 130000 of the most massive and passively evolving galaxies, obtaining five new cosmology-independent H ( z ) measurements in the redshift range 0.3 < z < 0.5, with an accuracy of ∼11–16% incorporating both statistical and systematic errors. Once combined, these measurements yield a 6% accuracy constraint of H ( z = 0.4293) = 91.8 ± 5.3 km/s/Mpc. The new data are crucial to provide the first cosmology-independent determination of the transition redshift at high statistical significance, measuring z {sub t} = 0.4 ± 0.1, and to significantly disfavor the null hypothesis of no transition between decelerated and accelerated expansion at 99.9% confidence level. This analysis highlights the wide potential of the cosmic chronometers approach: it permits to derive constraints on the expansion history of the Universe with results competitive with standard probes, and most importantly, being the estimates independent of the cosmological model, it can constrain cosmologies beyond—and including—the ΛCDM model.« less

  10. Reliability of segmental accelerations measured using a new wireless gait analysis system.

    PubMed

    Kavanagh, Justin J; Morrison, Steven; James, Daniel A; Barrett, Rod

    2006-01-01

    The purpose of this study was to determine the inter- and intra-examiner reliability, and stride-to-stride reliability, of an accelerometer-based gait analysis system which measured 3D accelerations of the upper and lower body during self-selected slow, preferred and fast walking speeds. Eight subjects attended two testing sessions in which accelerometers were attached to the head, neck, lower trunk, and right shank. In the initial testing session, two different examiners attached the accelerometers and performed the same testing procedures. A single examiner repeated the procedure in a subsequent testing session. All data were collected using a new wireless gait analysis system, which features near real-time data transmission via a Bluetooth network. Reliability for each testing condition (4 locations, 3 directions, 3 speeds) was quantified using a waveform similarity statistic known as the coefficient of multiple determination (CMD). CMD's ranged from 0.60 to 0.98 across all test conditions and were not significantly different for inter-examiner (0.86), intra-examiner (0.87), and stride-to-stride reliability (0.86). The highest repeatability for the effect of location, direction and walking speed were for the shank segment (0.94), the vertical direction (0.91) and the fast walking speed (0.91), respectively. Overall, these results indicate that a high degree of waveform repeatability was obtained using a new gait system under test-retest conditions involving single and dual examiners. Furthermore, differences in acceleration waveform repeatability associated with the reapplication of accelerometers were small in relation to normal motor variability.

  11. Compact Superconducting Radio-frequency Accelerators and Innovative RF Systems

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

    Kephart, Robert; Chattopadhyay, Swaapan; Milton, Stephen

    2015-04-10

    We will present several new technical and design breakthroughs that enable the creation of a new class of compact linear electron accelerators for industrial purposes. Use of Superconducting Radio-Frequency (SRF) cavities allow accelerators less than 1.5 M in length to create electron beams beyond 10 MeV and with average beam powers measured in 10’s of KW. These machines can have the capability to vary the output energy dynamically to produce brehmstrahlung x-rays of varying spectral coverage for applications such as rapid scanning of moving cargo for security purposes. Such compact accelerators will also be cost effective for many existing andmore » new industrial applications. Examples include radiation crosslinking of plastics and rubbers, creation of pure materials with surface properties radically altered from the bulk, modification of bulk or surface optical properties of materials, sterilization of medical instruments animal solid or liquid waste, and destruction of organic compounds in industrial waste water effluents. Small enough to be located on a mobile platform, such accelerators will enable new remediation methods for chemical and biological spills and/or in-situ crosslinking of materials. We will describe one current design under development at Fermilab including plans for prototype and value-engineering to reduce costs. We will also describe development of new nano-structured field-emitter arrays as sources of electrons, new methods for fabricating and cooling superconducting RF cavities, and a new novel RF power source based on magnetrons with full phase and amplitude control.« less

  12. Accelerated 1 H MRSI using randomly undersampled spiral-based k-space trajectories.

    PubMed

    Chatnuntawech, Itthi; Gagoski, Borjan; Bilgic, Berkin; Cauley, Stephen F; Setsompop, Kawin; Adalsteinsson, Elfar

    2014-07-30

    To develop and evaluate the performance of an acquisition and reconstruction method for accelerated MR spectroscopic imaging (MRSI) through undersampling of spiral trajectories. A randomly undersampled spiral acquisition and sensitivity encoding (SENSE) with total variation (TV) regularization, random SENSE+TV, is developed and evaluated on single-slice numerical phantom, in vivo single-slice MRSI, and in vivo three-dimensional (3D)-MRSI at 3 Tesla. Random SENSE+TV was compared with five alternative methods for accelerated MRSI. For the in vivo single-slice MRSI, random SENSE+TV yields up to 2.7 and 2 times reduction in root-mean-square error (RMSE) of reconstructed N-acetyl aspartate (NAA), creatine, and choline maps, compared with the denoised fully sampled and uniformly undersampled SENSE+TV methods with the same acquisition time, respectively. For the in vivo 3D-MRSI, random SENSE+TV yields up to 1.6 times reduction in RMSE, compared with uniform SENSE+TV. Furthermore, by using random SENSE+TV, we have demonstrated on the in vivo single-slice and 3D-MRSI that acceleration factors of 4.5 and 4 are achievable with the same quality as the fully sampled data, as measured by RMSE of reconstructed NAA map, respectively. With the same scan time, random SENSE+TV yields lower RMSEs of metabolite maps than other methods evaluated. Random SENSE+TV achieves up to 4.5-fold acceleration with comparable data quality as the fully sampled acquisition. Magn Reson Med, 2014. © 2014 Wiley Periodicals, Inc. © 2014 Wiley Periodicals, Inc.

  13. Accelerated aging: prediction of chemical stability of pharmaceuticals.

    PubMed

    Waterman, Kenneth C; Adami, Roger C

    2005-04-11

    Methods of rapidly and accurately assessing the chemical stability of pharmaceutical dosage forms are reviewed with respect to the major degradation mechanisms generally observed in pharmaceutical development. Methods are discussed, with the appropriate caveats, for accelerated aging of liquid and solid dosage forms, including small and large molecule active pharmaceutical ingredients. In particular, this review covers general thermal methods, as well as accelerated aging methods appropriate to oxidation, hydrolysis, reaction with reactive excipient impurities, photolysis and protein denaturation.

  14. A GPU-Accelerated Parameter Interpolation Thermodynamic Integration Free Energy Method.

    PubMed

    Giese, Timothy J; York, Darrin M

    2018-03-13

    There has been a resurgence of interest in free energy methods motivated by the performance enhancements offered by molecular dynamics (MD) software written for specialized hardware, such as graphics processing units (GPUs). In this work, we exploit the properties of a parameter-interpolated thermodynamic integration (PI-TI) method to connect states by their molecular mechanical (MM) parameter values. This pathway is shown to be better behaved for Mg 2+ → Ca 2+ transformations than traditional linear alchemical pathways (with and without soft-core potentials). The PI-TI method has the practical advantage that no modification of the MD code is required to propagate the dynamics, and unlike with linear alchemical mixing, only one electrostatic evaluation is needed (e.g., single call to particle-mesh Ewald) leading to better performance. In the case of AMBER, this enables all the performance benefits of GPU-acceleration to be realized, in addition to unlocking the full spectrum of features available within the MD software, such as Hamiltonian replica exchange (HREM). The TI derivative evaluation can be accomplished efficiently in a post-processing step by reanalyzing the statistically independent trajectory frames in parallel for high throughput. We also show how one can evaluate the particle mesh Ewald contribution to the TI derivative evaluation without needing to perform two reciprocal space calculations. We apply the PI-TI method with HREM on GPUs in AMBER to predict p K a values in double stranded RNA molecules and make comparison with experiments. Convergence to under 0.25 units for these systems required 100 ns or more of sampling per window and coupling of windows with HREM. We find that MM charges derived from ab initio QM/MM fragment calculations improve the agreement between calculation and experimental results.

  15. How to Produce a Reactor Neutron Spectrum Using a Proton Accelerator

    DOE PAGES

    Burns, Kimberly A.; Wootan, David W.; Gates, Robert O.; ...

    2015-06-18

    A method for reproducing the neutron energy spectrum present in the core of an operating nuclear reactor using an engineered target in an accelerator proton beam is proposed. The protons interact with a target to create neutrons through various (p,n) type reactions. Spectral tailoring of the emitted neutrons can be used to modify the energy of the generated neutron spectrum to represent various reactor spectra. Through the use of moderators and reflectors, the neutron spectrum can be modified to reproduce many different spectra of interest including spectra in small thermal test reactors, large pressurized water reactors, and fast reactors. Themore » particular application of this methodology is the design of an experimental approach for using an accelerator to measure the betas produced during fission to be used to reduce uncertainties in the interpretation of reactor antineutrino measurements. This approach involves using a proton accelerator to produce a neutron field representative of a power reactor, and using this neutron field to irradiate fission foils of the primary isotopes contributing to fission in the reactor, creating unstable, neutron rich fission products that subsequently beta decay and emit electron antineutrinos. A major advantage of an accelerator neutron source over a neutron beam from a thermal reactor is that the fast neutrons can be slowed down or tailored to approximate various power reactor spectra. An accelerator based neutron source that can be tailored to match various reactor neutron spectra provides an advantage for control in studying how changes in the neutron spectra affect parameters such as the resulting fission product beta spectrum.« less

  16. Acceleration of convergence of vector sequences

    NASA Technical Reports Server (NTRS)

    Sidi, A.; Ford, W. F.; Smith, D. A.

    1983-01-01

    A general approach to the construction of convergence acceleration methods for vector sequence is proposed. Using this approach, one can generate some known methods, such as the minimal polynomial extrapolation, the reduced rank extrapolation, and the topological epsilon algorithm, and also some new ones. Some of the new methods are easier to implement than the known methods and are observed to have similar numerical properties. The convergence analysis of these new methods is carried out, and it is shown that they are especially suitable for accelerating the convergence of vector sequences that are obtained when one solves linear systems of equations iteratively. A stability analysis is also given, and numerical examples are provided. The convergence and stability properties of the topological epsilon algorithm are likewise given.

  17. Angular distribution of electrons from powerful accelerators

    NASA Astrophysics Data System (ADS)

    Stepovik, A. P.; Lartsev, V. D.; Blinov, V. S.

    2007-07-01

    A technique for measuring the angular distribution of electrons escaping from the center of the window of the IGUR-3 and ÉMIR-M powerful accelerators (designed at the All-Russia Institute of Technical Physics, Russian Federal Nuclear Center) into ambient air is presented, and measurement data are reported. The number of electrons is measured with cable detectors (the solid angle of the collimator of the detector is ≈0.01 sr). The measurements are made in three azimuthal directions in 120° intervals in the polar angle range 0 22°. The angular distributions of the electrons coming out of the accelerators are represented in the form of B splines.

  18. Pressure fluctuation caused by moderate acceleration

    NASA Astrophysics Data System (ADS)

    Tagawa, Yoshiyuki; Kurihara, Chihiro; Kiyama, Akihito

    2017-11-01

    Pressure fluctuation caused by acceleration of a liquid column is observed in various important technologies, e.g. water-hammer in a pipeline. The magnitude of fluctuation can be estimated by two different approaches: When the duration time of acceleration is much shorter than the propagation time for a pressure wave to travel the length of the liquid column, e.g. sudden valve closure for a long pipe, Joukowsky equation is applied. In contrast, if the acceleration duration is much longer, the liquid is modeled as a rigid column, ignoring compressibility of the fluid. However, many of practical cases exist between these two extremes. In this study we propose a model describing pressure fluctuation when the duration of acceleration is in the same order of the propagation time for a pressure wave, i.e. under moderate acceleration. The novel model considers both temporal and spatial evolutions of pressure propagation as well as gradual pressure rise during the acceleration. We conduct experiments in which we impose acceleration to a liquid with varying the length of the liquid column, acceleration duration, and properties of liquids. The ratio between the acceleration duration and the propagation time is in the range of 0.02 - 2. The model agrees well with measurement results. JSPS KAKENHI Grant Numbers 26709007 and 17H01246.

  19. Innovative single-shot diagnostics for electrons from laser wakefield acceleration at FLAME

    NASA Astrophysics Data System (ADS)

    Bisesto, F. G.; Anania, M. P.; Cianchi, A.; Chiadroni, E.; Curcio, A.; Ferrario, M.; Pompili, R.; Zigler, A.

    2017-07-01

    Plasma wakefield acceleration is the most promising acceleration technique known nowadays, able to provide very high accelerating fields (> 100 GV/m), enabling acceleration of electrons to GeV energy in few centimeters. Here we present all the plasma related activities currently underway at SPARC_LAB exploiting the high power laser FLAME. In particular, we will give an overview of the single shot diagnostics employed: Electro Optic Sampling (EOS) for temporal measurement and Optical Transition Radiation (OTR) for an innovative one shot emittance measurements. In detail, the EOS technique has been employed to measure for the first time the longitudinal profile of electric field of fast electrons escaping from a solid target, driving the ions and protons acceleration, and to study the impact of using different target shapes. Moreover, a novel scheme for one shot emittance measurements based on OTR, developed and tested at SPARC_LAB LINAC, used in an experiment on electrons from laser wakefield acceleration still undergoing, will be shown.

  20. Role of failure-mechanism identification in accelerated testing

    NASA Technical Reports Server (NTRS)

    Hu, J. M.; Barker, D.; Dasgupta, A.; Arora, A.

    1993-01-01

    Accelerated life testing techniques provide a short-cut method to investigate the reliability of electronic devices with respect to certain dominant failure mechanisms that occur under normal operating conditions. However, accelerated tests have often been conducted without knowledge of the failure mechanisms and without ensuring that the test accelerated the same mechanism as that observed under normal operating conditions. This paper summarizes common failure mechanisms in electronic devices and packages and investigates possible failure mechanism shifting during accelerated testing.