Analysis of Shock Acceleration by Dotting of Finger Braille and Influence of Postures of Receiver＇s Hand

Finger Braille is one of the tactual communication media of deafblind people. In one-handed Finger Braille, a sender dots the left part of the Braille code on the Distal Interphalangeal （DIP） joints of the index, middle and ring fingers of a receiver, and subsequently dots the right part of the Braille code on the Proximal Interphalangeal （PIP）joints of the same fingers. Because there is a small number of non-disabled people who are skilled in Finger Braille, deafblind people communicate in this medium only through an interpreter. We have been developing a Finger Braille recognition system using small piezoelectric accelerometers worn by the receiver To recognize the dotted positions （DIP or PIP joints）, we have made a hypothesis that the dotting on the DIP joints causes a hard impact, and the dotting on the PIP joints causes a soft impact, when the receiver＇s hand forms a natural longitudinal arch on the desk. The difference of each impact is indicated by its damping amplitude ratio. In this paper, a measurement experiment about the postures of the receiver＇s hand was conducted. The postures of the receiver＇s hand were as follows： forming the natural longitudinal arch on the desk and fully contacting the desk. As a result, the dotting on the DIP joints of both postures caused the hard impacts; the dotting on the PIP joints caused the soft impact when the receiver＇s hand formed the natural longitudinal arch; the dotting on the PIP joints caused the hard impact when the receiver＇s hand fully contacted the desk. Therefore, we could verify the hypothesis.

Effects of density profile and multi-species target on laser-heated thermal-pressure-driven shock wave acceleration

The shock wave acceleration of ions driven by laser-heated thermal pressure is studied through one-dimensional particle-in-cell simulation and analysis. The generation of high-energy mono-energetic protons in recent experiments （D. Haberberger et al., 2012 Nat. Phys. 8 95） is attributed to the use of exponentially decaying density profile of the plasma target. It does not only keep the shock velocity stable but also suppresses the normal target normal sheath acceleration. The effects of target composition are also examined, where a similar collective velocity of all ion species is demonstrated. The results also give some reference to future experiments of producing energetic heavy ions.

Effect of Thermal Shock Process in Accelerated Environment Spectrum on the Fatigue Life of 7B04-T6 Aluminum Alloy

The effect of thermal shock, in an accelerated-corrosion environment spectrum, on the fatigue and corrosion behavior of 7B04-T6 aluminum alloy, was determined. The environment spectrum consists of two modules, namely： salt-spray corrosion and thermal shock. The effect of thermal shock on the mechanical properties was determined via tensile tests; SEM, DCS, and XRD were used to determine the effect of thermal shock on the corrosion products. In addition, the corrosion resistance of the products was ascertained through electrochemical testing. The results show that the mechanical properties and fatigue life of the aluminum alloy will decline with prolonged thermal shock time. The thermal shock process may result in denser surface corrosion products than those formed on the no thermal shock specimens, and transformation of some Al（OH）_3 into Al OOH. Al OOH may have resulted in improved corrosion resistance and hence a lower decrease in the fatigue life after corrosion, compared with that of the no thermal shock specimen. Repeated corrosion/thermal shock may have delayed further decease in the fatigue life. Therefore, selection of an appropriate equivalent thermal shock temperature and time was essential for designing the environmental spectrum.

Experimental Study of Structure Shock Vibration in Soil Caused by Explosion of Conventional Weapons

When hitting underground structures directly or exploding in rock-soil media near underground structures, the conventional weapons with large charge weight will make underground structures be subjected to strong shock vibration and cause personal casualty and damage of precision electronic equipments. The shock vibration has become one of the cardinal killing means of weapons. However, the existing methods of predicting structure shock vibration are limited evidently. In this paper the coupling coefficient of acceleration in clayey soil is obtained firstly. Subsequently based on repeated experiments of chemical explosion, after dimension analysis and by using method of multivariate stepwise regression, the calculation formulae of shock vibration acceleration for the underground structure are obtained finally. The formulae consider top and side explosion respectively, taking into account the effects of penetration depth, charge weight, distance to explosion center, rock-soil media, size of structure and buried depth. They are easy to use with high practicability and degree of confidence, and can provide credible evidence for prediction of shock vibration and vibration isolating design of underground structure.

Energy spectral property in an isolated CME-driven shock

Observations from multiple spacecraft show that there are energy spectral ＂breaks＂ at 1-10 MeV in some large CME-driven shocks. However, numerical models can hardly simulate this property due to high computational expense. The present paper focuses on analyzing these energy spectral ＂breaks＂ by Monte Carlo particle simulations of an isolated CME-driven shock. Taking the 2006 Dec 14 CME-driven shock as an example, we investigate the formation of this energy spectral property. For this purpose, we apply different values for the scattering time in our isolated shock model to obtain the highest energy ＂tails,＂ which can potentially exceed the ＂break＂ energy range. However, we have not found the highest energy ＂tails＂ beyond the ＂break＂ energy range, but instead find that the highest energy ＂tails＂ reach saturation near the range of energy at 5 MeV. So, we believe that there exists an energy spectral ＂cut off＂ in an isolated shock. If there is no interaction with another shock, there would not be formation of the energy spectral ＂break＂ property.

Analysis of the CME-driven shock from the SEP event that occurred on 2006 December 14

In a solar flare or coronal mass ejection （CME）, observations of the subse- quent interplanetary shock provide us with strong evidence of particle acceleration to energies of multiple MeV, even up to GeV. Diffusive shock acceleration is an efficient mechanism for particle acceleration. For investigating the shock structure, the energy injection and energy spectrum ofa CME-driven shock, we perform a dynamical Monte Carlo simulation of the CME-driven shock that occurred on 2006 December 14 using an anisotropic scattering law. The simulated results of the shock＇s fine structure, par- ticle injection, and energy spectrum are presented. We find that our simulation results give a good fit to the observations from multiple spacecraft.

Solar Energetic Particle Event of 2005 January 20:Release Times and Possible Sources

Based on cosmic ray data obtained by neutron monitors at the Earth＇s surface, and data on near-relativistic electrons measured by the WIND satellite, as well as on solar X-ray and radio burst data, the solar energetic particle （SEP） event of 2005 January 20 is studied. The results show that this event is a mixed event where the flare is dominant in the acceleration of the SEPs, the interplanetary shock accelerates mainly solar protons with energies below 130 MeV, while the relativistic protons are only accelerated by the solar flare. The interplanetary shock had an obvious acceleration effect on relativistic electrons with energies greater than 2 MeV. It was found that the solar release time for the relativistic protons was about 06：41 UT, while that for the near-relativistic electrons was about 06：39 UT. The latter turned Out to be about 2 rain later than the onset time of the interplanetary type HI burst.

Particle acceleration and transport in the inner heliosphere

In the solar system, our Sun is Nature's most efficient particle accelerator. In large solar flares and fast coronal mass ejections(CMEs), protons and heavy ions can be accelerated to over ~GeV/nucleon. Large flares and fast CMEs often occur together. However there are clues that different acceleration mechanisms exist in these two processes. In solar flares, particles are accelerated at magnetic reconnection sites and stochastic acceleration likely dominates. In comparison, at CME-driven shocks,diffusive shock acceleration dominates. Besides solar flares and CMEs, which are transient events, acceleration of particles has also been observed in other places in the solar system, including the solar wind termination shock, planetary bow shocks, and shocks bounding the Corotation Interaction Regions(CIRs). Understanding how particles are accelerated in these places has been a central topic of space physics. However, because observations of energetic particles are often made at spacecraft near the Earth,propagation of energetic particles in the solar wind smears out many distinct features of the acceleration process. The propagation of a charged particle in the solar wind closely relates to the turbulent electric field and magnetic field of the solar wind through particle-wave interaction. A correct interpretation of the observations therefore requires a thorough understanding of the solar wind turbulence. Conversely, one can deduce properties of the solar wind turbulence from energetic particle observations. In this article I briefly review some of the current state of knowledge of particle acceleration and transport in the inner heliosphere and discuss a few topics which may bear the key features to further understand the problem of particle acceleration and transport.