Mutual Collision Research Articles

Crustal Motion of Chinese Mainland and Preparation of MS8.0 Wenchuan Earthquake in Sichuan Province

AbstractWe calculated the moving velocities in Chinese mainland for 1999~2007 years and dynamic moving velocities for 2004~2007 years according to the data from Crustal Movement Observation Network of China. We calculated the activity parameters of Longmenshan fault zone based on the parameters of Qinghai‐Tibet and South China subplates, studied the change of the motion field of Chinese mainland, and analyzed the relations between the characteristics of the motion field of the crust and the Wenchuan MS8.0 earthquake. The research revealed that the present‐day crustal motion zoning is basically consistent with the geological neotectonic units, indicating that the recent crustal tectonic activity is the inheritance from and development of the neotectonic movement; The dynamic force of crustal motion of Chinese mainland is mainly associated with the action caused by the mutual collision and underthrust of India plate, and Pacific plate to the Eurasia plate. The MS8.0 Wenchuan earthquake is mainly due to the lateral motion caused by the northward pushing of India plate to Qinghai‐Xizang subplate, resulting in that Longmenshan fault is compressed to accumulate energy for the MS8.0 Wenchuan earthquake. The crustal dynamic motion in the period of 2004~2007 strengthened the strike slip of Longmenshan fault zone and it transformed from the stable state of compressive strain accumulation to an easy active state under shear force.

Influence of structure disorders and temperatures of systems on the bio-energy transport in protein molecules (II)

Influence of structure disorders and temperatures of systems on the bio-energy transport in protein molecules (II)

The refinement treatment of martensite in Cu–11.38 wt.%Al–0.43 wt.%Be shape memory alloys

The refinement treatment of martensite in Cu–11.38 wt.%Al–0.43 wt.%Be (Cu–22.71 at.%Al–2.57 at.%Be) shape memory alloy was investigated in this work. The results show that the aging treatment at a temperature near the eutectoid temperature caused numbers of oval-like renucleated parent phase in the matrix. Following the TEM-EDX analysis, a concentration gradient of Al content is caused because the Al-rich renucleated phase formed in the matrix. Therefore, the occurrence immediately provides potential sites for heterogeneous nucleation. When a large number of martensites grow simultaneously, mutual collision and obstruction occur, creating a cluster microstructure of fine martensite and improving the recovery ability of the alloy.

Nanoparticle coagulation in fractionally charged and charge fluctuating dusty plasmas

The kinetics of nanoparticle coagulation has been studied in fractionally charged and charge fluctuating dusty plasmas. The coagulation occurs when the mutual collision frequency among nanoparticles exceeds their charging and decharging/neutralization frequency. Interestingly, the coagulation is suppressed while a fraction (several percent) of nanoparticles are negatively charged in a plasma, in which stochastic charging plays an important role. A model is developed to predict a phase diagram of the coagulation and its suppression.

Orbital Stability of Protoplanetary Systems in Nebular Gas and Implications for Terrestrial Planet Formation

The oligarchic growth model of planetary accretion predicts the formation of protoplanets of similar sizes, and the final stage of terrestrial planet formation involves long-term orbital instability and mutual collision of protoplanets through their gravitational interaction. However, the mass of the protoplanets formed by oligarchic growth depends on the initial surface density of the protoplanetary disk, as well as the distance from the central star. In order to better understand the final stage of terrestrial planet formation in disks with various profiles, we perform orbital integration for systems of five protoplanets and examine the dependence of the orbital instability timescale of the systems on the mass of the protoplanets, Mp, both with and without nebular gas. Previous studies have shown that the timescale for orbital instability in the absence of nebular gas increases exponentially with the initial semimajor axis difference between the protoplanets. We find that the exponential constant is independent of the mass of the protoplanets, as long as the initial separation is measured in units of ~M, which is very close to the previously derived mass dependence of the critical separation for the onset of chaotic behavior in the restricted circular three-body problem. In the presence of nebular gas, on the other hand, protoplanetary systems are stabilized by gas drag and experience no orbital instability when the initial semimajor axis difference is larger than a certain critical value. Using these results, we discuss the orbital stability of protoplanetary systems in disks with various surface densities.

NUMERICAL SIMULATION OF GRAVEL BED DEFORMATION ON THE BASIS OF PARTICLE MOTION ANALYSIS

Numerical simulation of sediment wave formation was conducted in the present study. Saltation model has been extended in order to analyze the entire motion of particle which starts by being picked-up from a bed and ceases its motion by depositing on it. The procedure in which a mutual collision between moving particles can be explained physically was newly invented here to consider the effect of interaction between them. Based on such models, the multi-particle motion can be analyzed simultaneously. In this paper, the gravel bed deformation which is caused by each particle motions was predicted under the same condition of flume experiment.

Visualization and analysis of electrodynamic behavior during cardiac arrhythmias

Sudden cardiac death is the primary cause of mortality in the industrialized world. Ventricular tachycardia and lethal arrhythmias such as ventricular fibrillation are believed to be the result of reentrant electrical activity, i.e., self‐sustained electrical activity which continues to re‐excite regions of cardiac tissue independently of the natural pacemaker rhythm. The mechanisms behind fibrillation initiation, maintenance, and termination by a defibrillatory shock are largely unknown. Cardiac fibrillation is characterized by a complex spatial interaction of nonstationary spiral waves; however, the nature of this interaction is an ongoing topic of investigation. The organizing center of reentry is a topological defect called a phase singularity in two dimensions, a filament in three dimensions; an understanding of fibrillation behavior may be obtained by localizing and tracking these defects. Experimentally, the electrodynamic behavior is typically investigated via optical mapping using voltage‐sensitive fluorescent dyes. In this thesis, a technique to detect phase singularities based upon topological charge was applied to nonlinear time‐series and phase portrait analysis of optical signals, and later extended to filament detection; this procedure was shown to be both efficient and mathematically robust. An alternate method to reconstruct the phase portrait was also explored and shown to overcome some of the limitations of the time‐series method as well as permitting singularity detection closer to initiation than previously allowed. Numerically examining the interaction dynamics of a simple filament configuration paralleling that seen in experimental preparations indicated that a critical bifurcation in filament lifetime exists between attractive and repulsive behavior along with annihilation by mutual collision and collapse by shrinkage, which could be represented by a difference of Yukawa potentials by treating the filaments as a pair of point charges. The inclusion of optical depth effects into a numerical model of three‐dimensional filament activity was studied, and suggested that these effects have a significant impact on observed epicardial activity. Finally, a three‐dimensional geometric reconstruction of an isolated, perfused heart with the fluorescence information as a texture map, previously developed as a proof‐of‐concept, was shown to be a viable tool for whole‐heart singularity visualization.

Constraints on star formation from the close packing of protostars in clusters

The mm-wave continuum sources (MCS) in Ophiuchus have mutual collision rates less than their collapse rates by a factor of 10 to 100, suggesting most will form stars without further interactions. However, this ratio of rates would have exceeded unity in the past if the MCS were 2.5 times larger than they are now. Such a high previous ratio was not likely, suggesting that the MCS grew from smaller sizes at a constant high density, possible behind turbulent shocks. Proximity constraints are even more important in massive clusters, where massive stars with the same or greater space density are more strongly interacting than the Ophiuchus MCS. As a result, the density contrast for MCS must be larger in massive clusters than it is in Ophiuchus, or significant coalescence will occur in the protostellar phase, possible forming a massive black hole. A proportionality to the second power of the Mach number allows the MCS cores to collapse independently. These results suggest that stars in dense clusters generally form on a dynamical time by the continuous collection and rapid collapse of turbulence-shocked gas. Implications of proximity constraints on the initial stellar mass function are also discussed.

Production of hot plasmas by hypervelocity impact

Very hot plasmas can be obtained by mutual collision of projectiles accelerated to high velocities up to 400 km/s. The electromagnetic drive of lithium or iron circular wires is considered by using either high frequency or constant magnetic fields. When deuterium and tritium are present, fusion reactions are expected. Considering iron, fusion could start from a temperature of 1.4/spl times/10/sup 6/ because energy has been released by the recombination of multiple charged ions.

Collisional Rates within Newly Formed Asteroid Families

A statistical analysis of the mutual collisions among members of asteroid families during the very early times after family formation has been performed. The statistical properties of the collisions (probability, distribution of velocity, and so on) have been computed using an algorithm effective even in cases in which the longitude of the nodes and the longitudes of the perihelia of the orbits under consideration are not distributed uniformly. The results show the occurrence of a strong enhancement in the mutual collision rate among family members, immediately after family formation. Nevertheless, this episode lasts for a relatively short time, and it does not affect too severely the overall collisional evolution of the family. The early enhancement of mutual collisions, however, may influence the cratering record exhibited by the surfaces of family members, possibly laying the foundation for the early development of a surface regolith layer.

高E/n放電空間における振動準位の高いN<SUB>2</SUB>(C<SUP>3</SUP>Π<SUB>u</SUB>)の生成過程

The authors have studied on generation processes of N2(C3Πu) in discharge of high E/n region. In this investigation, the spatial distribution of N2 Second Positive Bands was measured and was compared with the calculated results obtained by the Monte-Carlo method. From the results, it is suggested that N2(C3Πu) was generated by any processes including direct excitation from the ground state. To confirm the generation process except the direct one, time after glow method was used. As a result, slow decay component on intensity of N2 Second Positive Bands was detected. Its relaxation time was about 0.5ms. The relaxation time is similar to the effective life time of N2(A3Σu+). Then, in discharge of high E/n region, it is shown that the rate of N2(C3Πu, υ'=3, 4) generated by re-excitation process of N2(A3Σu+) mutual collision is high.

Control of initial growth processes of epitaxial films using pulsed molecular beams

Kinetics of epitaxial thin film growth was analyzed from the experiments using pulsed organic molecular beams. It was found that a minimum appears in the nucleation density as a function of on-off cycle time when the substrate temperature is near the threshold between growth and reevaporation. This feature can be explained by assuming desorption of molecules induced by mutual collision on the surface, for which orientation-sensitive intermolecular forces are responsible.

Simple analysis of correlation in few-body Coulomb systems: Application in the diffusion Monte Carlo method

An apporach is presented in order to study the interelectronic correlation in few-electron atomic or molecular systems. The main point is that the correlation is described as a mutual collision between all the electrons. This approach allows the determination of simple wave functions for complex systems including only three parameters, with a clear physical meaning. The method is applied to study three- and four-electron systems in different states, including the so-called hollow states for lithium and beryllium. The overall results are found to be in good agreement with those deduced using much more sophisticated wave functions. Subsequently, the present wave functions are chosen as trial wave functions in the diffusion Monte Carlo method. This approach leads to a very accurate determination of the ground-state energies of lithium, lithium negative ion, and beryllium atoms, indicating that it becomes possible to deduce with very good accuracy some properties of relatively complex systems with a quite simple wave function.

Microcavity polariton scattering probed by coherent control experiments

We present coherent control experiments which simultaneously probe both the coherence and the population dynamics of the exciton–photon polariton states in a semiconductor microcavity. The coherent manipulation of either the spin orientation or the density of polaritons is demonstrated leading to the measurement of the optical dephasing time. The polariton scattering by acoustical phonons or by mutual collision processes are investigated by a simultaneous measurement of both the optical dephasing time T2and the decay time T1of the radiant states. These results clearly evidence a quenching of the different scattering processes at resonance.

Insights on normal vocal-fold oscillation from the acoustic dissection of single glottic pulses in vocal fry

Vocal-fold oscillation has been investigated from the viewpoint of kinematics and dynamics of single glottal pulse at normal intensity vocal fry frequencies, using a modified Sondhi tube. Key moments in the cycle are opening and closing actions, which appear to be very sudden. These events may be noted in two ‘‘kinks’’ which appear along traces of the EGG and glottal cross-sectional area functions. Between opening and closing boundary encounters, vocal folds seem to travel in quasiballistic fashion, being slingshotted out by feedback from the subglottal pressure wave and ending their traverse across the glottal opening with mutual collision The abrupt opening and closing gestures of the glottis permit the glottal valve to modulate subglottal volume flow against the inertia of tracheal air. Acoustic emissions from the glottis may be thought of as flow fluctuations which compensate for changes in fluctuating glottal area, thereby maintaining approximately incompressible flow. Fluctuations of glottal area generate the bulk of F0 energy while upper formants owe their spectral energy to boundary layer events that happen near the violent endpoints of glottal motion.

Selection Rules and Probabilities of Exciton-Exciton Collisions

Selection rules are summarized for a mutual collision of two Wannier-Mott excitons which produces one free hole and one free electron. Calculation of probabilities per second of the collision: exciton + exciton → electron + hole in a perfect nonmetallic crystal for slow excitons in 1s and 2p states with isotropic effective mass of electron and hole has been performed assuming that the conduction band minimum and the valence band maximum are localized at the center of the Brillouin zone.

Origin of broken phenocrysts in ash-flow tuffs

Surprisingly little attention has been devoted to the textural nature of phenocrysts of feldspar and quartz in tuff. Although many geologists have briefly alluded to “broken” phenocrysts, none have addressed their origin in any detail. Petrographic study of 117 cooling units in the middle Tertiary ash-flow province of the Great Basin, United States, provides a basis for characterization of the shapes and for interpretation of the origin of felsic phenocrysts in ash-flow tuffs. Although not proven to be wholly ineffective, breakage of phenocrysts by mutual impact in the erupting magma and pyroclastic flow is doubtful for at least four reasons. First, the statistical probability of mutual collision between phenocrysts diminishes exponentially as their proportion to vitroclasts diminishes (e.g., only 1% probability for 10% phenocrysts); collision is less likely if pyroclasts move by laminar rather than turbulent flow. Second, the coating of glass and/or melt on the phenocrysts provides a cushion that absorbs the impact force. Third, plagioclases broken by impact in the laboratory have unusual shapes unlike those seen in Great Basin tuffs. Fourth, euhedral phenocrysts of feldspar are commonplace in many Great Basin tuffs, and in some they constitute a significant proportion of the phenocrysts, indicating that mutual impact does not modify all intratelluric crystals during explosive eruption. The two most populated categories of phenocryst shape in Great Basin tuffs probably correspond to what has been previously called “broken” phenocrysts. Somewhat less than half of the plagioclase and many sanidine phenocrysts are subhedral to anhedral. These are similar in shape, size, and composition to grains in polycrystalline aggregates within the same thin section. Kindred aggregates and discrete phenocrysts could have been derived from holocrystalline to partly crystalline material in the magma chamber that was disaggregated to varying extents during explosive eruption. More than half of the plagioclase and all of the quartz phenocrysts in Great Basin tuffs consist of irregularly shaped fragments with cuspate, embayed outlines, resembling pieces of a jigsaw puzzle, which we call phenoclasts. Inclusions of glass are common and are especially evident in larger, more or less whole crystals. Textural features of some phenocrysts in cognate pumice clasts in the tuffs reveal that they broke apart while still in the vesiculating but unfragmented magma. As the erupting magma decompressed, vesiculation of the melt that was entrapped at higher pressures as inclusions within the phenocrysts blew them apart, forming the phenoclasts. Shapes of felsic phenocrysts in volcanic rocks provide insight into their mode of emplacement. Euhedral phenocrysts are common in ash-flow tuffs as well as lava flows. Phenoclasts, however, are diagnostic of ash-flow tuffs, because they do not occur in Plinian ash-fall deposits and are rare in lava flows. These textural contrasts are useful for interpretation of generally older, but in any case altered and recrystallized, volcanic rocks. In such rocks, critical groundmass features and field relations that could provide clues to their origin have been obscured, but the shapes of relict phenocrysts are commonly well preserved.

Impact of satellite constellation arrangement on the future orbital debris environment

The proposed concept of communication satellite constellation such as Iridium (with 66 satellites) and Teledesic (with 840 satellites) in LEO has been studied for its operational constrains and the impact to the evolution of the future orbital debris environment. A large number of spacecraft in constellation creates a spike in spatial density distribution at a place where they are collocated in a thin shell, which in turn increases the collision probability with other space objects passing through the thin shell. Once a collision has occurred, most of the collision fragments and the damaged spacecraft will drift in the vicinity of the thin shell and further increase the mutual collision rate for the objects in the shell. This cascading effect is not only devastating to the operation of communication satellites in a constellation, but also has a significant impact on the evolution of the future orbital debris environment. Model calculations with a constellation of 1000 satellites at 600, 800, 1000 or 1500 km altitude are used to examine the fate of the satellites in the constellation and assess the impact on the orbital debris environment following the event. It is found that the optimal operational condition for these constellation satellites is to have a small cross-sectional area and for the constellation to be placed at an altitude region away from high concentrations of current space objects.

Collision Avoidance Using Communication between Autonomous Mobile Robots

This paper addresses mutual collision avoidance between multiple mobile robots based on a layered strategy. In this Strategy, static motion generation and dynamic motion generation of several levels are provided , and a proper level of dynamic motion generation is selected for mutual collision avoidance according to the complexity of the situation. We have implemented two typical methods in the layered strategy , which are rules-based local collision avoidance and negotiation-based global one using communication. In each method, a robot detects collision and applies as a local method as possible. Experimental results show two actual mobile robots can achieve mutual collision avoidance based on the layered strategy.

宇宙ロボット 通信を用いた複数自律移動ロボットの相互衝突回避

This paper addresses mutual collision avoidance between multiple mobile robots based on a layered strategy. In this strategy, static motion generation and dynamic motion generation of several levels are provided, and a proper level of dynamic motion generation is selected for mutual collision avoidance according to the complexity of the situation. We have implemented two typical methods in the layered strategy, which are rule-based local collision avoidance and negotiation-based global one using communication. In each method, a robot detects collision and applies as a local method as possible. Experimental results show two actual mobile robots can achieve mutual collision avoidance based on the layered strategy.