Slow Acceleration Research Articles

INTERRUPTED ERUPTION OF LARGE QUIESCENT FILAMENT ASSOCIATED WITH A HALO CME

ABSTRACT We analyze the observations of an eruptive quiescent filament associated with a halo Coronal Mass Ejection (CME). We use observations from the Atmospheric Imaging Assembly (AIA) instrument onboard the Solar Dynamics Observatory (SDO), Solar and Heliospheric Observatory (SOHO)/Large Angle and Spectrometric Coronagraph (LASCO), and the Solar Terrestrial Relations Observatory (STEREO A/B) satellites. The filament exhibits a slow-rise phase followed by a gradual acceleration and then completely disappears. The filament could be traced in STEREO observations up to an altitude of about 1.44 R ⊙ , where its rise speed reached ∼14 km s−1 and disappeared completely at about 10:32 UT on 2011 October 21. The CME associated with the filament eruption and two bright ribbons in the chromosphere both appeared at about 01:30 UT on October 22, i.e., 15 hr after the filament eruption was seen in He ii 304 Å filtergrams. We show that this delay is abnormally large even if the slow rise speed and slow acceleration of the filament are taken into account. To understand the cause of this delay, we compute the decay index (n) of the overlying coronal magnetic field. The height distribution of the decay index, n, suggests that the zone of instability ( n > 1) at a lower altitude, 144–480 Mm, is followed by a zone of stability ( n < 1) between 540 and 660 Mm. We interpret the observed delay to be due to the presence of the latter zone, i.e., the zone of stability, which could provide a second quasi-equilibrium state to the filament until it finally erupts.

Effects of Lampricide on Olfaction and Behavior in Young-of-the-Year Lake Sturgeon (Acipenser fulvescens).

The lampricide, 3-trifluoromethyl-4-nitrophenol (TFM), is a primary component to sea lamprey control in the Laurentian Great Lakes. Though the lethal effects of TFM are well-known, the sublethal effects on fishes are virtually unknown. Here we studied the effects of TFM on the olfactory capabilities and behavior of young-of-the-year (YOY) lake sturgeon (Acipenser fulvescens). At ecologically relevant concentrations of TFM there was reduced olfactory response to all three cues (l-alanine, taurocholic acid, food cue) tested, suggesting that TFM inhibits both olfactory sensory neurons tested. Sturgeon exposed to TFM also showed a reduced attraction to the scent of food and reduced consumption of food relative to unexposed fish. Exposed fish were more active than control fish, but with slower acceleration. Fish were able to detect the scent of TFM, but failed to avoid it in behavioral trials. The connection between neurophysiological and behavioral changes, and the commonality of habitats between sturgeon and lamprey ammocoetes, suggests that there may be effects at the ecosystem level in streams that undergo lamprey control treatments.

Driving Performance of Adaptive Driving Controls using Drive-by-Wire Technology for People with Disabilities

Objective: The purpose of this study was to develop and evaluate high technology adaptive driving controls, such as mini steering wheel-lever system and joystick system, for the people with physical disabilities in the driving simulator. Background: The drivers with severe physical disabilities have problems in operation of the motor vehicle because of reduced muscle strength and limited range of motion. Therefore, if the remote control system with driver-by-wire technology is used for adaptive driving controls for people with physical limitations, the disabled people can improve their quality of life by driving a motor vehicle. Method: We developed the remotely controlled driving simulator with drive-by-wire technology, e.g., mini steering wheel-lever system and joystick system, in order to evaluate driving performance in a safe environment for people with severe physical disabilities. STISim Drive 3 software was used for driving test and the customized Labview program was used in order to control the servomotors and the adaptive driving devices. Thirty subjects participated in the study to evaluate driving performance associated with three different driving controls: conventional driving control, mini steering wheel-lever controls and joystick controls. We analyzed the driving performance in three different courses: straight lane course for acceleration and braking performance, a curved course for steering performance, and intersections for coupled performance. Results: The mini steering wheel-lever system and joystick system developed in this study showed no significant statistical difference (p >0.05) compared to the conventional driving system in the acceleration performance (specified speed travel time, average speed when passing on the right), steering performance (lane departure at the slow curved road, high-speed curved road and the intersection), and braking performance (brake reaction time). However, conventional driving system showed significant statistical difference (p 0.05). The subjects with physical disabilities showed a tendency of relatively slow acceleration (p 0.05) according to the characteristics of the subjects. Conclusion: The driving performance with mini steering wheel-lever system and joystick control system showed no significant statistical difference compared to conventional system in the driving simulator. Application: This study can be used to design primary controls with driver-by-wire technology for adaptive vehicle and to improve their community mobility for people with severe physical disabilities.

Comparison of Rotating and Translating Wings: Force Production and Vortex Characteristics

Experiments were conducted on a rectangular flat plate wing at high incidence to compare the force production and leading-edge vortex location and strength as a function of time for eight sets of wing kinematics: rectilinear and rotational pitch and surge, with fast and slow accelerations. The primary differences observed in the force histories were between the pitch and surge cases, and they occurred during the acceleration or pitching portions of the motions. The force histories were found to be similar between the rectilinear and rotational cases. The leading-edge vortex trajectories in the rectilinear cases were found to be similar when compared on a new time scale , related to the integrated leading-edge-normal velocity. The vortex trajectory of the rotational cases matched those of the rectilinear cases until the leading-edge vortex in the rotational case settled into a position attached to the wing. Circulation values of the leading-edge vortex for all cases were found to collapse when plotted versus and scaled by the instantaneous leading-edge-normal velocity. The results demonstrate a successful collapse of both vortex quantities and force production using only leading-edge kinematics.

Phase change in subducted lithosphere, impulse, and quantizing Earth surface deformations

Abstract. The new paradigm of plate tectonics began in 1960 with Harry H. Hess's 1960 realization that new ocean floor was being created today and is not everywhere of Precambrian age as previously thought. In the following decades an unprecedented coming together of bathymetric, topographic, magnetic, gravity, seismicity, seismic profiling data occurred, all supporting and building upon the concept of plate tectonics. Most investigators accepted the premise that there was no net torque amongst the plates. Bowin (2010) demonstrated that plates accelerated and decelerated at rates 10−8 times smaller than plate velocities, and that globally angular momentum is conserved by plate tectonic motions, but few appeared to note its existence. Here we first summarize how we separate where different mass sources may lie within the Earth and how we can estimate their mass. The Earth's greatest mass anomalies arise from topography of the boundary between the metallic nickel–iron core and the silicate mantle that dominate the Earth's spherical harmonic degree 2 and 3 potential field coefficients, and overwhelm all other internal mass anomalies. The mass anomalies due to phase changes in olivine and pyroxene in subducted lithosphere are hidden within the spherical harmonic degree 4–10 packet, and are an order of magnitude smaller than those from the core–mantle boundary. Then we explore the geometry of the Emperor and Hawaiian seamount chains and the 60° bend between them that aids in documenting the slow acceleration during both the Pacific Plate's northward motion that formed the Emperor seamount chain and its westward motion that formed the Hawaiian seamount chain, but it decelerated at the time of the bend (46 Myr). Although the 60° change in direction of the Pacific Plate at of the bend, there appears to have been nary a pause in a passive spreading history for the North Atlantic Plate, for example. This, too, supports phase change being the single driver for plate tectonics and conservation of angular momentum. Since mountain building we now know results from changes in momentum, we have calculated an experimental deformation index value (1–1000) based on a world topographic grid at 5 arcmin spacing and displayed those results for viewing.

PERIODIC DENSITY STRUCTURES AND THE ORIGIN OF THE SLOW SOLAR WIND

The source of the slow solar wind has challenged scientists for years. Periodic density structures (PDSs), observed regularly in the solar wind at 1 AU, can be used to address this challenge. These structures have length scales of hundreds to several thousands of megameters and frequencies of tens to hundreds of minutes. Two lines of evidence indicate that PDSs are formed in the solar corona as part of the slow solar wind release and/or acceleration processes. The first is corresponding changes in compositional data in situ, and the second is PDSs observed in the inner Heliospheric Imaging data on board the Solar Terrestrial Relations Observatory (STEREO)/Sun Earth Connection Coronal and Heliospheric Investigation (SECCHI) suite. The periodic nature of these density structures is both a useful identifier as well as an important physical constraint on their origin. In this paper, we present the results of tracking periodic structures identified in the inner Heliospheric Imager in SECCHI back in time through the corresponding outer coronagraph (COR2) images. We demonstrate that the PDSs are formed around or below 2.5 solar radii—the inner edge of the COR2 field of view. We compute the occurrence rates of PDSs in 10 days of COR2 images both as a function of their periodicity and location in the solar corona, and we find that this set of PDSs occurs preferentially with a periodicity of ∼90 minutes and occurs near streamers. Lastly, we show that their acceleration and expansion through COR2 is self-similar, thus their frequency is constant at distances beyond 2.5 solar radii.

Clinical roles of fixation suppression failure in dizzy patients in the ENT clinic

Conclusion: Any test for visual fixation suppression by itself is insufficient for screening central pathology and should be interpreted in conjunction with other neurotologic findings. Objectives: We evaluated the correlation of visual fixation suppression (VFS) under three different test conditions (spontaneous nystagmus, caloric stimulation, and slow harmonic acceleration, SHA), as well as the diagnostic accuracy of each test for predicting central pathology, in dizzy patients. Methods: We retrospectively reviewed cases in a tertiary referral center; 504 consecutive dizzy patients who visited the ENT clinic were enrolled. The fixation index (FI, slow component velocity during fixation/slow component velocity before fixation × 100%) for the caloric test and spontaneous nystagmus was calculated and failure was indicated when the FI was greater than 60%. VFS during the SHA test at a frequency of 0.04 Hz was also performed and gain more than 0.2 was considered as failure of VFS. Results: The incidence of VFS failure was 5.4% in the caloric test, 3.4% in spontaneous nystagmus, and 2.3% in the SHA test, respectively. Significant correlation was found only between the caloric test and the SHA test (r = 0.341, p < 0.001). The sensitivity of VFS in different tests did not exceed 35%. The specificity of VFS was highest (96.4%) in the 0.04 Hz SHA test, and exceeded 80% in the other tests.

Rotating Stall Observations in a High Speed Compressor—Part I: Experimental Study

In this two-part paper, the phenomenon of part span rotating stall is studied. The objective is to improve understanding of the physics by which stable and persistent rotating stall occurs within high speed axial flow compressors. This phenomenon is studied both experimentally (Part I) and through the use of unsteady RANS simulations (Part II). In this paper, the behavior of an eight stage high speed compressor is studied during slow acceleration maneuvres along a fixed working line. Casing mounted pressure transducers and rotor mounted strain gages are used to examine the spectral content of any unsteadiness in the flow and its behavior across the operating range. By deliberate aerodynamic mismatching of the front stages through adjustment of three rows of variable stator vanes (VSVs), stable rotating stall is initiated. The observed behavior falls into two “families” of high and low frequency when tracked on the instrumentation. Further analysis based on the Doppler shift between the static and rotating measurements confirms that these respective phenomena are due to rotating stall of high and low cell count. Acoustic modes resulting from stall/rotor interaction are also identified. Strong correlation of the stall intensity with simple 1D meanline predicted loading parameters suggests that these families of behavior are independently linked to the stalling of different regions within the compressor.

Short-bunch extraction in a rapid cycling synchrotron

Short bunch beams of high intensity are required by many applications, and they are usually obtained by using bunch compression before the extraction in relatively slow cycling synchrotrons or accumulator rings. In this article, short bunch extraction by the bunch compression method is proposed to apply to a rapid cycling synchrotron (RCS) where the time duration is very limited to exploit the bunch compression process. The method is practically applied in the RCS of the China Spallation Neutron Source (CSNS) to obtain short-bunch beams for white neutron applications. Different short-bunch extraction scenarios have been studied, from keeping full beam power to reduced beam powers. A special desynchronization method is designed to solve the problem of slow acceleration during the bunch rotation process when the magnetic field is still ramping up. The space charge effect and beam loading effect during the bunch compression have also been taken into account in this high-intensity RCS. Multiparticle simulations have been carried out to show the effectiveness of the method with the input of the CSNS RCS. With a sacrifice of about two-thirds of the beam power, the rms bunch length of the extracted beam can be reduced to about one-ninth of the one in the nominal operation mode.

Slow Slip Acceleration beneath Andaman Islands Triggered by the 11 April 2012 Indian Ocean Earthquakes

The M-w 8.6 and 8.2 strike-slip earthquakes that struck the northeast Indian Ocean on 11 April 2012 resulted in coseismic deformation both at near and distant sites. The slip distribution, deduced using seismic-wave analysis for the orthogonal faults that ruptured during these earthquakes, is sufficient to predict the coseismic displacements at the Global Positioning System (GPS) sites, such as NTUS, PALK, and CUSV, but fall short at four continuous sites in the Andaman Islands region. Slip modeling, for times prior to the events, suggests that the lower portion of the thrust fault beneath the Andaman Islands has been slipping at least at the rate of 40 cm/yr, in response to the 2004 Sumatra-Andaman coseismic stress change. Modeling of GPS displacements suggests that the en echelon and orthogonal fault ruptures of the 2012 intraplate oceanic earthquakes could have possibly accelerated the ongoing slow slip, along the lower portion of the thrust fault beneath the islands with a month-long slip of 4-10 cm. The misfit to the coseismic GPS displacements along the Andaman Islands could be improved with a better source model, assuming that no local process contributed to this anomaly.

Cost-effectiveness of alternative powertrains for reduced energy use and CO2 emissions in passenger vehicles

This work analysed the cost-effectiveness of avoiding carbon dioxide (CO2) emissions using advanced internal combustion engines, hybrids, plug-in hybrids, fuel cell vehicles and electric vehicles across the nine UK passenger vehicles segments. Across all vehicle types and powertrain groups, minimum installed motive power was dependent most on the time to accelerate from zero to 96.6km/h (60mph). Hybridising the powertrain reduced the difference in energy use between vehicles with slow (tz-60>8s) and fast acceleration (tz-60<8s) times. The cost premium associated with advanced powertrains was dependent most on the powertrain chosen, rather than the performance required. Improving non-powertrain components reduced vehicle road load and allowed total motive capacity to decrease by 17%, energy use by 11%, manufacturing cost premiums by 13% and CO2 emissions abatement costs by 15%. All vehicles with advanced internal combustion engines, most hybrid and plug-in hybrid powertrains reduced net CO2 emissions and had lower lifetime operating costs than the respective segment reference vehicle. Most powertrains using fuel cells and all electric vehicles had positive CO2 emissions abatement costs. However, only vehicles using advanced internal combustion engines and parallel hybrid vehicles may be attractive to consumers by the fuel savings offsetting increases in vehicle cost within two years. This work demonstrates that fuel savings are possible relative to today’s fleet, but indicates that the most cost-effective way of reducing fuel consumption and CO2 emissions is by advanced combustion technologies and hybridisation with a parallel topology.

Record breaking bursts in a fiber bundle model of creep rupture

We investigate the statistics of record breaking events in the time series of crackling bursts in a fiber bundle model of the creep rupture of heterogeneous materials. In the model fibers break due to two mechanisms: slowly accumulating damage triggers bursts of immediate breakings analogous to acoustic emissions in experiments. The rupture process accelerates such that the size of breaking avalanches increases while the waiting time between consecutive events decreases towards failure. Record events are defined as bursts which have a larger size than all previous events in the time series. We analyze the statistics of records focusing on the limit of equal load sharing (ELS) of the model and compare the results to the record statistics of sequences of independent identically distributed random variables. Computer simulations revealed that the number of records grows with the logarithm of the event number except for the close vicinity of macroscopic failure where an exponential dependence is evidenced. The two regimes can be attributed to the dominance of disorder with small burst sizes and to stress enhancements giving rise efficient triggering of extended bursts, respectively. Both the size of records and the increments between consecutive record events are characterized by power law distributions with a common exponent 1.33 significantly different from the usual ELS burst size exponents of fiber bundles. The distribution of waiting times follows the same behavior, however, with two distinct exponents for low and high loads. Studying the evolution of records we identify a load dependent characteristic scale of the system which separates slow down and acceleration of record breaking as failure is approached.

The wind of W Hydrae as seen byHerschel

Asymptotic giant branch (AGB) stars lose their envelopes by means of a stellar wind whose driving mechanism is not understood well. Characterizing the composition and thermal and dynamical structure of the outflow provides constraints that are essential for understanding AGB evolution, including the rate of mass loss and isotopic ratios. We modeled the CO emission from the wind of the low mass-loss rate oxygen-rich AGB star W Hya using data obtained by the HIFI, PACS, and SPIRE instruments onboard the Herschel Space Observatory and ground-based telescopes. $^{12}$CO and $^{13}$CO lines are used to constrain the intrinsic $^{12}$C/$^{13}$C ratio from resolved HIFI lines. The acceleration of the outflow up to about 5.5 km/s is quite slow and can be represented by a beta-type velocity law with index 5. Beyond this point, acceleration up the terminal velocity of 7 km/s is faster. Using the J=10-9, 9-8, and 6-5 transitions, we find an intrinsic $^{12}$C/$^{13}$C ratio of $18\pm10$ for W Hya, where the error bar is mostly due to uncertainties in the $^{12}$CO abundance and the stellar flux around 4.6 $\mu$m. To match the low-excitation CO lines, these molecules need to be photo-dissociated at about 500 stellar radii. The radial dust emission intensity profile measured by PACS images at 70 $\mu$m shows substantially stronger emission than our model predicts beyond 20 arcsec. The initial slow acceleration of the wind implies inefficient wind driving in the lower part of the envelope. The final injection of momentum in the wind might be the result of an increase in the opacity thanks to the late condensation of dust species. The derived intrinsic isotopologue ratio for W Hya is consistent with values set by the first dredge-up and suggestive of an initial mass of 2 M$_\odot$ or more. However, the uncertainty in the main-sequence mass derived based on this isotopologic ratio is large.

Magnetohydrodynamic study for three-dimensional instability of the Petschek type magnetic reconnection

The 3D instability of the spontaneous fast magnetic reconnection process is studied with magnetohydrodynamics (MHD) simulations, where the 2D model of the spontaneous fast magnetic reconnection is destabilized in three dimension. As well known in many 2D numerical MHD studies, when a 1D current sheet is destabilized with the current-driven anomalous resistivity, the 2D Petschek type fast magnetic reconnection is established. This paper shows that the 2D Petschek type fast magnetic reconnection can be destabilized in three dimension by an initial resistive disturbance which includes a weak fluctuation in the sheet current direction, i.e., along the magnetic neutral line. The resulting 3D fast magnetic reconnection finally becomes intermittent and random through a 3D instability. In addition, it is also shown that the 3D instability is suppressed by the uniform resistivity. It suggests that the 3D instability is caused in the Petschek-type reconnection process which is characterized by a strongly localized magnetic diffusion region and the slow shock acceleration of the plasma jets and is suppressed in the Sweet-Parker type reconnection process.

Hydration mechanism of tricalcium silicate (alite)

In this review paper, the hydration of alite with reference to its stages and mechanism is discussed. The overall hydration process of alite is divided in four stages: period of initial reaction, period of slow reaction, acceleration period and deceleration period. The addition of calcium sulfate modifies the hydration process of alite, the rate of reaction of tricalcium aluminate, the interactions of silicates and aluminates and the kinetics of the deceleration period. Different hydration products are obtained in the presence of calcium chloride, which not only activate the hydration process but improve the strength of cement mortar.

Search forη-mesic4He with the WASA-at-COSY detector

An exclusive measurement of the excitation function for the dd->3Heppi- reaction was performed at the Cooler Synchrotron COSY-Juelich with the WASA-at-COSY detection system. The data were taken during a slow acceleration of the beam from 2.185 GeV/c to 2.400 GeV/c crossing the kinematic threshold for the eta meson production in the dd->4He-eta reaction at 2.336 GeV/c. The corresponding excess energy with respect to the 4He-eta system varied from -51.4MeV to 22MeV. The integrated luminosity in the experiment was determined using the dd->3Hen reaction. The shape of the excitation function for the dd->3Heppi- was examined. No signal of the 4He-eta bound state was observed. An upper limit for the cross-section for the bound state formation and decay in the process dd->(4He-eta)bound->3Heppi- was determined on the 90% confidence level and it varies from 20nb to 27nb for the bound state width ranging from 5MeV to 35MeV, respectively.

Optimal design of linear vibrators used in touch screen mobile phones

Because of the advances in the wireless communication technology, mobile phones have become necessary devices in modern society. With the touch screen-based input methods provided by smartphones, mobile devices have become more interactive. Thus, the vibrators for such devices need to be more responsive to interact directly with humans. However, typical vibrators are not suited for this purpose mainly because of their low vibration performance and high costs. In the recent decade, linear vibrators have been adopted because of their better vibration performance. However, the conventional linear vibrators suffered from slower acceleration drawback under the same input power. This paper proposes a novel structure of linear vibrators to improve the vibration acceleration. The finite element method was used to analyze the electromagnetic and mechanical characteristics of the linear vibrator. Design of experiments and response surface method optimization were performed to maximize the acceleration. Simulation and experimental results revealed that the optimization increased the acceleration of the vibrator by 33% compared with the prototype.

Kinematic Factors Affecting Fast and Slow Straight and Change-of-Direction Acceleration Times

In many sports, players are often required to accelerate immediately after rapid changes of direction (CODs) before performing a subsequent COD movement. Therefore, court-based players will often not attain their maximum velocity before having to decelerate and change direction. The purpose of this study was to determine what kinematic factors affected fast and slow straight acceleration (SA) and change-of-direction acceleration (CODA) times. National under-21 netball players performed 3 trials each of a 2.5-m SA and a CODA involving a 180° COD followed immediately by a 2.5-m sprint. Players were grouped into either a faster or slower category based on performance times (2.5-m time). Significantly higher average step frequency (4%, p = 0.03) was observed for the faster group when compared with the slower group in the CODA task. For the SA task, faster times were associated with significantly smaller average step lengths (SLs; 7%, p = 0.03), greater torso angles (i.e., greater forward lean; 30-37%, p < 0.001), and smaller hip angle (less knee lift) in the first step (21-22%, p = 0.00). The SA task was associated with significantly longer average SLs (21-23%, p = 0.00) and significantly longer SL across all 3 steps as compared with the CODA task (17-27%, p < 0.001) A significantly increased forward lean was associated with the first step of the SA task (34%, p < 0.001) and significantly higher knee lift for the first and second steps of the SA task (11-22%, p = 0.00 and 0.04, respectively). These kinematic differences can be used for training purposes for both coaches and strength and conditioning practitioners.

A bilateral head injury that shows graded brain damage and behavioral deficits in adultmice

Reliable animal models of traumatic brain injury (TBI) are essential to test novel hypotheses and therapeutic interventions. In this study, based on advantages of both the closed head injury (CHI) and controlled cortical impact (CCI) models, we developed a bilateral head injury model in mice. C57BL/6 mice were used in this study. A midline craniotomy (5mm diameter) was performed extending 2mm anteriorly and 3mm posteriorly from the bregma, centered over the sagittal suture. The skull flap was left in place. A cortical impact on the surface of the skull flap was performed using an electromagnetic impactor. Here we report that the injury significantly decreased the neuroscore and increased foot drops in a severity-dependent manner. Severity-related deficits in performance on a rotarod device were also found at both slow and fast accelerations. These findings suggest that our TBI model can produce graded motor deficits. In addition, Morris water maze testing showed increased latency to locate a hidden platform in a severity-dependent manner, suggesting that our model can also produce graded memory deficits. Furthermore, an adhesive removal test revealed significant increases in time-to-contact and time-to-remove the adhesive tape from the paw in a severity-dependent manner, indicating that our TBI model produced graded somatosensory and motor deficits. Histological analysis presented a clear gradation in brain tissue damage following graded brain injuries. These findings collectively suggest that the current model may offer a sensitive, reliable and clinically-relevant model for assessments of therapeutic strategies forTBI.

ON THE LOW-FREQUENCY BOUNDARY OF SUN-GENERATED MAGNETOHYDRODYNAMIC TURBULENCE IN THE SLOW SOLAR WIND

New aspects of the slow solar wind turbulent heating and acceleration are investigated. A physical meaning of the lower boundary of the Alfv\'en wave turbulent spectra in the solar atmosphere and the solar wind is studied and the significance of this natural parameter is demonstrated. Via an analytical and quantitative treatment of the problem we show that a truncation of the wave spectra from the lower frequency side, which is a consequence of the solar magnetic field structure and its cyclic changes, results in a significant reduction of the heat production and acceleration rates. An appropriate analysis is presented regarding the link of the considered problem with existing observational data and slow solar wind initiation scenarios.