New image processing algorithm for terminal guidance of multiple kinetic-energy impactors for disrupting hazardous asteroids

This paper describes the preliminary study results of developing a hypervelocity terminal intercept guidance system of a multiple kinetic-energy impactor vehicle(MKIV).The proposed MKIV system is intended to fragment or pulverize an asteroid of smaller than approximately 150 m in diameter that is detected with a mission lead time of shorter than 10 years,without using nuclear explosive devices.This paper focuses on the development of a new image processing algorithm based on Otsu’s method for the coordinated terminal intercept guidance and control of multiple kinetic-energy impactors employing visual and/or infrared sensors.A scaled polyhedron shape model of asteroid(216)Kleopatra is used as a fictional target asteroid.GPU-based simulation results demonstrate the feasibility of impacting a small irregular-shaped asteroid by using the proposed new image processing algorithm and a classical pulsed TPN(true proportional navigation)terminal guidance law.

Investigation of the effect of nozzle shape on supersonic/hypersonic impactors designed for size discrimination of nanoparticles

In this study the flow field and the nanoparticle collection efficiency of supersonic/hypersonic impactors with different nozzle shapes were studied using a computational modeling approach. The aim of this study was to develop a nozzle design for supersonic]hypersonic impactors with the smallest possible cut-off size d5o and rather sharp collection efficiency curves. The simulation results show that the changes in the angle and width of a converging nozzle do not alter the cut-off size of the impactor; however, using a conical Laval nozzle with an L]Dn ratio less than or equal to 2 reduced d5o. The effect of using a cap as a focuser in the nozzle of a supersonic/hypersonic impactor was also investigated. The results show that adding a cap in front of the nozzle had a noticeable effect on decreasing the cut-off size of the impactor. Both fiat disks and conical caps were examined, and it was observed that the nozzle with the conical cap had a lower cut-off size.

Computational investigation of powder coating of nanoparticles in supersonic and hypersonic impactors

In this study, numerical simulation of flow field in a supersonic/hypersonic impactor with one or two nozzles was carried out using a commercial computational fluid dynamics （CFD） software FLUENT. The objective was to investigate the effects of working parameters such as pressure ratio （50 〈 Po]Pb 〈 800）, nozzle diameters （D=0.23, 0.27, 0.45 mm）, nozzle to plate distance （0.5 〈L/D〈 50）, particle diameter （1 nm〈 dp 〈 100 nm ） and angle between two nozzles. A single-phase 3D unsteady-state model was implemented by the software. For this purpose, a user-defined function （UDF） was employed to implement nanoparticles for different assumptions of Cunningham correction factor. An axisymmetric form of the compressible Navier-Stokes and energy equations was used for both fluid flow and temperature; Lagrangian particle trajectory analysis was used for particle motion. Using the variable Cunningham cor- rection factor showed suitable agreement with experimental data in comparison with other methods. Results show that increase of the distance between nozzle and impaction plate causes increase of Mach number, the distance between bow shock and impaction plate, and the collection efficiency. Maximum jet velocity, distance between bow shock and impaction plate and collection efficiency increase by using two nozzles in supersonic and hypersonic imoactors.

冲击压实技术在旧混凝土路面修复中的应用

通过IMPACTOR2 0 0 0机破碎并击实旧水泥混凝土路面的试验 ,探讨其破碎击实的施工工艺和效果。结果表明 :该法能有效打碎并夯实旧混凝土路面 ,利用击碎的旧混凝土碎块作底基层 ,其当量模量得到提高 ,弯沉趋于均匀 ,可进一步防止面层出现反射裂缝 ,同时解决了旧混凝土废弃物的堆放问题 ,有利于环境保护。

冲击压实技术在旧混凝土路面修复中的应用

通过IMPACTOR 2000机破碎并击实旧水泥混凝土路面的试验,探讨了其破碎击实的施工工艺和效果。结果表明:该法能有效打碎并夯实旧混凝土路面,利用击碎的旧混凝土碎块作底基层,使当量模量得到提高,弯沉趋于均匀,可进一步防止面层出现反射裂缝,同时解决了旧混凝土废弃物的堆放问题,有利于环境保护。

A combined virtual impactor and field-effect transistor microsystem for particulate matter separation and detection

Ambient suspended particulate matter(PM)(primarily with particle diameter 2.5m or less,i.e.,PM2.5)can adversely affect ecosystems and human health.Currently,optical particle sensors based on light scattering dominate the portable PM sensing market.However,the light scattering method has poor adaptability to different-sized PM and adverse environmental conditions.Here,we design and develop a portable PM sensing microsystem that consists of a micromachined virtual impactor(VI)for particle separation,a thermophoretic deposition chip for particle collection,and an extended-gate field-effect transistor(FET)for particle analysis.This system can realize on-site separation,collection,and analysis of aerosol particles without being influenced by environmental factors.In this study,the design of the VI is thoroughly analyzed by numerical simulation,and mixtures of different-sized silicon dioxide(SiO2)particles are used in an experimental verification of the performance of the VI and FET.Considering the low cost and compact design of the whole system,the proposed PM analysis microsystem has potential for PM detection under a wide range of conditions,such as heavily polluted industrial environments and for point-of-need outdoor and indoor air quality monitoring.

Dynamic Performance Analysis of Gas-Liquid United Hydraulic Hammer

In order to improve the impactor performance, the dynamic performance of gas-liquid united hydraulic hammer should be optimized. Based on the analysis of the operating principle for the hydraulic impactor, one simulation model of gas-liquid united hydraulic impactor was built with AMESim software. By setting different simulation parameters, curves of displacement, velocity, acceleration and cavity pressure were obtained under different working conditions. The key component can be obtained by the analysis of activity index. The whole simulation results provide a reliable basis for component selection and parameter optimization of hydraulic impactor.

Optimum Shape of High Speed Impactor for Concrete Targets Using PSOA Heuristic

The present paper deals with the optimum shape design of an absolutely rigid impactor which penetrates into a semi-infinite concrete shield. The objective function to maximize is the depth of penetration (DOP for short) of the impactor;in the case of impactors with axisymmetric shapes DOP is calculated using formulas obtained by Ben-Dor et al. [1-3] with the method of local variations [4] and based on the mechanical model proposed by Forrestal and Tzou [5]. In the present paper we show that using a different class of admissible functions, more general than the axisymmetric one, better results can be obtained. To solve the formulated optimization problem we used a custom version of the particle swarm optimization method (briefly denoted by PSOA), a very recent numerical optimization algorithm of guided random global search. Numerical results show the optimal shape for various types of shields and corresponding DOP;some Ben-Dor et al. [1-3] results are compared to solutions obtained.

冲击稳压破碎技术及机械在旧水泥混凝土路面维护上的介绍

通过对冲击稳压破碎技术及破碎机械的介绍,表明此项新技术和新机械可以在旧水泥混凝土路面的维护上获得良好的社会及经济效益,可以达到节省工程成本,提高施工进度,有利于环保的目的。

Hydraulic impactor with impact energy and frequency adjusted independently and steplessly

Based on analysis of the present hydraulic impactor, a new hydraulic impactor with pressure feedback control was developed, whose structure and operation principle were introduced. The results show that the pressure of the impact system can be adjusted steplessly to change the impact energy of the impactor steplessly. By adjusting the oil flow of supply pump steplessly, the impact frequency will also be changed steplessly. So the impact energy and frequency of the new impactor can be adjusted independently and steplessly. In order to decrease the energy loss, a new kind of sleeve valve has been designed, which has features of little leakage, little pressure loss and low energy cost. The new type hydraulic impactor can be operated under various conditions with decreased energy consumption and improved operation efficiency.

Numerical Investigation of Bismuth Unloading Solidification with Abnormal Melting Characteristic

We present the processes and results of a numerical investigation of the bismuth unloading solidification by a graded density impactor, and demonstrate that the physical process may be realized due to bismuth abnormal melting characteristics. A more reasonable high-pressure solid equation of state of the fifth phase bismuth is introduced in our calculation and one type of graded density impactor made of 15 compositions of Mg-Cu material system is given in this paper. We detailedly investigate one possible proposed approach to achieve the unloading solidification physical process, and our numerical analysis on the thermodynamic state, the unloading path and the phase transformations.

Dynamic Modeling of Pedestrian Legform and Prediction of Pedestrian Injuries

Decreasing the death toll of pedestrians in traffic accidents is one of the most urgent tasks to be solved all over the world. This paper describes the prediction of pedestrian injuries for the TRL legform impactor using MATLAB. The TRL legform impactor consists of three parts: a femur, a tibia, and a ligament connecting them. The impactor was physically modelled with springs, dampers and two masses as a dynamic model. The impactor behaves in a translational and rotational motion during the collision with a vehicle. The behavior of the impactor during the crash event was captured by a high speed camera and is regarded as the four-degree-of-freedom system in terms of translational and rotational motions. Pedestrian injuries are evaluated by three physical quantities indexes: the acceleration of the tibia, both the displacement and the bending angle between the femur and the tibia. The physical model for the impactor was expressed mathematically by differential equations. In the case of modelling, the ligament connecting both the femur and the tibia in particular plays an important role. Shear forces were applied to the ligament in translational motions and the bending moments in rotational motion. Differential equations were expressed in the form of a state equation and an output equation by MATLAB. Numerical solutions were obtained by a block diagram with Simulink. As a result, it was found that the predicted injuries agree quite well with their experimented data in terms of acceleration, displacement, and the bending angle mentioned above.

Impactor冲击胀管系统及其应用——旧管更换的新技术，水平导向钻机的新天地

本文简述了非开挖市场的现状及旧管更换的需求潜力，着重介绍了新的胀管技术Impactor胀管系统的工作原理和系统构成、施工设计和施工过程、系统用于非开挖施工的优势，并且通过实际的应用案例进一步证实了该系统的可行性和高效率。

Establishment and Functional Evaluation of a Rat Model of Spinal Cord Injury

Objective:To explore the modified Allen impactor method in establishing a rat model of spinal cord injury,and to preliminarily evaluate the motor function of the forelimbs and hindlimbs of rats.Methods:Thirty female SD rats with a body weight of 255±21g were randomly divided into two groups,namely the sham-operated group and the operated group,with 15 rats in each group.The spinal cord injury SD rat model was established by exposing but not injuring the spinal cord in the sham-operated group,while the SD rat model was established by the modified Allen impactor method in the operated group.The Basso-Beattie-Bresnahan(BBB)rating scale was used to assess the rats’hindlimb motor neurobehavior.A rat model of spinal cord injury was established by the modified Allen impactor method.After the cells were transplanted,the BBB score was used to evaluate the motor function;the changes in the motor function of rats with spinal cord injury were detected.Results:The motor function and sensory function of the forelimbs and hindlimbs of the rats showed significant changes after five days.The motor function of the forelimbs and hindlimbs of the rats in the sham-operated group were essentially normal after three days(about 20 points);the sensory function of the rats in the operated group decreased significantly after five days;however,in the sham-operated group,it decreased to 0.The motor function scores of the rats in the operated group at each point of time were significantly lower than those in the sham-operated group(p<0.05),while the forelimb motor function scores were significantly higher than those in the sham-operated group(p<0.05).Conclusion:The modified Allen impactor method that was used to establish a rat model of spinal cord injury in this study can significantly reduce the motor function of rats.

Planetary defense mission concepts for disrupting/pulverizing hazardous asteroids with short warning time

This paper presents an overview of space mission concepts for disrupting or pulverizing hazardous asteroids, especially with warning time shorter than approximately 10 years. An innovative mission concept, referred to as a nuclear hypervelocity asteroid intercept vehicle (HAIV) system, employs both a kinetic-energy impactor and nuclear explosive devices. A new mission concept of exploiting a multiple kinetic-energy impactor vehicle (MKIV) system that doesn’t employ nuclear explosives is proposed in this paper, especially for asteroids smaller than approximately 150 m in diameter. The multiple shock wave interaction effect on disrupting or pulverizing a small asteroid is discussed using hydrodynamic simulation results. A multi-target terminal guidance problem and a planetary defense mission design employing a heavy-lift launch vehicle are also brie y discussed in support of the new non-nuclear MKIV mission concept. The nuclear HAIV and non-nuclear MKIV systems complement to each other to effectively mitigate the various asteroid impact threats with short warning time.

Size distribution and chemical characteristics of particles from crop residue open burning in North China

Crop residue open burning is an important emission source of ambient particles in China.This study analyzed the particle emission characteristics of crop residue open burning through combustion experiments with a novel open combustion simulation device using three typical crop straws in north China(corn,wheat,and rice).Particle samples size ranging from 0.006–9.890μm were collected by an Electrical Low Pressure Impactor plus,a high size-resolution instrument capable of dividing particles into 14 size stages.The size distributions of organic carbon(OC),elemental carbon(EC),water-soluble ions,and elements were analyzed,and source chemical profiles were constructed for PM0.1,PM1,PM2.5,and PM10.The number concentration of particles was concentrated in the Aiken nuclei mode(0.006–0.054μm),accounting for 75%of the total number,whereas the mass concentration was concentrated in the accumulation mode(0.054–0.949μm),accounting for 85.43%of the mass loading.OC,EC,Cl−,and K(include total K and water-soluble K)were the major chemical components of the particles,whose mass percentage distributions differed from those of other components.These fivemain components exhibited a bell-shaped size distribution in the 0.006–9.890μm range,whereas the other components exhibited a U-shaped distribution.Among the chemical profiles for PM0.1–PM10,OC was the most important component at 10–30%,followed by EC at 2%–8%.The proportions of K^(+),Cl^(−),and K varied substantially in different experimental groups,ranging from 0–15%,and K+and Cl−were significantly correlated(r=0.878,α=0.000).

Research Note Difference between low-volume and high-volume Andersen samplers in measuring atmospheric aerosols

The mass concentration and size distribution of aerosols in Tokaimura were investigated using a high-volume and a low-volume Andersen sampler. A difference was found using the two samplers： the concentration of total aerosols determined with the high-volume sampler is smaller than that of the low-volume sampler by 70-90% throughout the year. Compared to the high-volume sampler, low-volume sampler gave lower concentration for aerosols 〉7 μm, higher concentration for aerosols of 3.3-7.0 μm and 〈 1.1 μm, though similar results for aerosols of 1.1-3.3 μm. The low-volume sampler was found to have better separation efficiency and higher accuracy.

Comprehensive characterization of ambient nanoparticles collected near an industrial science park:Particle size distributions and relationships with environmental factors

We investigated the characteristics of ambient particles and their relationships with various environmental factors, including gaseous pollutants （CI-h, non-methane hydrocarbons （NMHC）, total hydrocarbons （THC）, NOx, CO, SO2）, meteorological parameters （humidity, temperature）, and time （day/night, workday/weekend）. We used an electrical low-pressure cascade impactor to measure the number and size distributions of ambient particles （0.007-10 ~m） that were collected approximately 1 km northwest of Hsinchu Science Park in Taiwan between February and May 2007. The number concentrations of particles were enhanced through photochemical reactions during the day. In addition, high traffic flow during workdays increased the formation of particulates. Except for SO2, all of the gaseous pollutants we studied （CH4, NMHC, THC, NOx, CO） correlated positively with the total number concentrations of ambient particles during daytime, indicating that they might contribute to the particulate burden. The poorer relationship between the SO2 level and the total number concentration of particles suggests that SO2 might participate indirectly in the nucleation process during particle formation, The high enrichment factors for Zn, Pb, Cu, and Mn, which mostly comprised the ultrafine particles （diameter： 〈 0.1 Ixm） and fine particles （diameter： 0.1-1 ~tm）, presumably arose from emissions from traffic and high technology factories. Heterogeneous reactions on solid particles might play a role in the removal of SOx and NOx from the atmosphere. Sulfides and nitrides can further react with these local pollutants, forming specific Cu-containing compounds： Cut （39%）, CuSO4 （34%）, and Cu（NO3）2 （27%）, within the ambient particles in this industrial area.

Impactor冲击胀管系统及其应用 旧管更换的新技术,水平导向钻机的新天地

本文简述了非开挖市场的现状及旧管更换的需求潜力,着重介绍了新的胀管技术Impactor,胀管系统的工作原理和系统构成、施工设计和施工过程、系统用于非开挖施工的优势,并且通过实际的应用案例进一步证实了该系统的可行性和高效率。