Application of ALE Method on the Numerical Simulation of Reinforced Concrete Penetration

LS-DYNA program and the principle of ALE method were introduced, and the target features of the reinforced concrete penetration were analyzed by using the D material model and the ALE method. A numerical simulation has been done to show the penetration visually and veritably. The simulation results are analyzed carefully and explicitly prove their significance to the research of reinforced concrete penetration.

Round robin using the depth of penetration test method on an armour grade alumina

The depth of penetration(DOP)method is a well-known ballistic test method for characterisation and ranking of ceramic armour materials.The ceramic tile is bonded to a backing material of semi-infinite thickness,and the penetration depth of the projectile gives a measure of the performance of the ceramic.There is,however,an inherent variability in the results from this test method.In this work,the accuracy and the variability of the DOP method has been investigated in a round robin exercise.Six ballistic test centres took part in the exercise.A test protocol was developed,in which the threat type(projectile and impact conditions)and a procedure on how to prepare the targets were specified.The targets consisted of alumina tiles of two different thicknesses that were bonded to polycarbonate backing cubes.Two different 7.62 mm armour piercing projectiles were employed;one with a hard steel core and one with a tungsten carbide core.The projectiles and the other materials all came from single material batches in order to avoid batch-to-batch variations in material properties.These materials were distributed between the ballistic test centres.The test results of the different ballistic test facilities were collected and compared.There was not a lot of variation between the average DOP values obtained at each laboratory,but the variation in penetration depth between shots was high.The consequence of this variation may be less confidence in the test results,and a statistical method was used to evaluate the required number of tests that are sufficient to obtain an average result with high confidence.In most cases,the required number of tests is much higher than what is practically feasible.This work was conducted as part of the European Defence Agency-project CERAMBALL.

Computational Simulation of Hypervelocity Penetration Using Adaptive SPH Method

The normal hypervelocity impact of an Al-thin plate by an Al-sphere was numerically simulated by using the adaptive smoothed particle hydrodynamics (ASPH) method. In this method, the isotropic smoothing algorithm of standard SPH is replaced with anisotropic smoothing involving ellipsoidal kernels whose axes evolve automatically to follow the mean particle spacing as it varies in time, space, and direction around each particle. Using the ASPH, the anisotropic volume changes under strong shock condition are captured more accurately and clearly. The sophisticated features of meshless and Lagrangian nature inherent in the SPH method are kept for treating large deformations, large inhomogeneities and tracing free surfaces in the extremely transient impact process. A two-dimensional ASPH program is coded with C++. The developed hydrocode is examined for example problems of hypervelocity impacts of solid materials. The results obtained from the numerical simulation are compared with available experimental ones. Good agreement is observed.

A study of particles penetration in sieving process on a linear vibration screen

This paper presented an investigation of particle collision and penetration using the discrete element method to understand the motion of particles and improve theoretical treatment in the sieving process. The process progressively was divided into looseness, stratification, collision, and penetration. Particle penetration has a direct effect on the screening performance. The penetration probability was defined, and the mathematical relationships between particle penetration and vibration parameters were established using the least squares method. To obtain the ideal penetration probability for materials the amplitude and frequency should preferably be near 3.0 mm and 25 Hz, respectively. The vibration direction angle has only a slight effect on penetration. The stage of the screening process from 0.1 to 0.7 s is the primary region for collision and penetration. This paper focused on the sieving process to more fully understand how particle collision and penetration influence the screening efficiency.

Modified Method for Estimating Organic Carbon Density in Discontinuous Karst Soil Using Ground-Penetrating Radar and Geostatistics

The conventional method which assumes the soil distribution is continuous was unsuitable for estimating soil organic carbon density(SOCD) in Karst areas because of its discontinuous soil distribution. The accurate estimation of SOCD in Karst areas is essential for carbon sequestration assessment in China. In this study, a modified method,which considers the vertical proportion of soil area in the profile when calculating the SOCD, was developed to estimate the SOCD in a typical Karst peak-cluster depression area in southwest China. In the modified method, ground-penetrating radar(GPR) technology was used to detect the distribution and thickness of soil. The accuracy of the method was confirmed through comparison with the data obtained using a validation method, in which the soil thickness was measured by excavation. In comparison with the conventional method and average-soil-depth method,the SOCD estimated using the GPR method showed the minimum relative error with respect to that obtained using the validation method. At a regional scale, the average SOCDs at depths of 0-20 cm and 0-100 cm, which were interpolated by ordinary kriging,were 1.49(ranging from 0.03-5.65) and 2.26(0.09-11.60) kgm-2based on GPR method in our study area(covering 393.6 hm2), respectively. Therefore, the modified method can be applied on the accurate estimation of SOCD in discontinuous soil areas such as Karst regions.

Penetration grouting reinforcement of sandy gravel

To study the relationship between grouting effect and grouting factors, three factors （seven parameters） directionless pressure and small cycle grouting model experiment on sandy gravel was done, which was designed according to uniform design method. And regressing was applied to analysis of the test data. The two models test results indicate that when the diffusing radius of grout changes from 26 to 51 cm, the grouted sandy gravel compressing strength changes from 2.13 to 12.30 MPa; the relationship between diffusing radius（R） and water cement ratio（m）, permeability coefficient（k）, grouting pressure（p）, grouting time（t） is R=19.953m^0.121k^0.429p^0.412t^0.437; the relationship between compressing strength（P） and porosity（n）, water cement ratio, grouting pressure, grouting time is P =0.984n^0.517m6-1.488p^0.118t^0.031. So the porosity of sandy gravel, the permeability coefficient of sandy gravel, grouting pressure, grouting time, water cement ratio are main factors to influence the grouting effect. The grouting pressure is the main factor to influence grouting diffusing radius, and the water cement ratio is the main factor to influence grouted sandy gravel compressing strength.

Penetration depth for yaw-inducing bursting layer impacted by projectile

In order to accurately estimate the anti-penetration capacity of yaw-inducing bursting layer with irregular barriers on surface impacted by projectile,the theoretical model of attack angle and angular velocity for projectile impacting on irregular barrier was achieved according to the macroscopic relation of contact force versus contact time,in which the main factors such as the relative geometrical characteristics of projectile and irregular barrier,material property and impact velocity of projectile influencing on yaw-inducing effectiveness were considered.On the basis of considering synthetically the influences of attack angle,impact velocity,impact angle of projectile and uncontrolled free surface of target,the theoretical formulation of penetration depth for bursting layer with irregular barriers on surface impacted by projectile was presented by expressing the stress of an optional point on the nose of projectile according to the relation of stress versus velocity.The theoretical results indicate that in the case of oblique impact embodying effect of attack angle,the penetration depth is reduced with the increase of impact angle,attack angle or angular velocity,and penetration trajectory is also deflected obviously.The effectiveness of angular velocity influencing on penetration depth is increased with impact velocity increasing.The theoretical results are in good agreement with test data for low impact velocity.

Finite difference time domain method forward simulation of complex geoelectricity ground penetrating radar model

The ground penetrating radar(GPR) forward simulation all aims at the singular and regular models, such as sandwich model, round cavity, square cavity, and so on, which are comparably simple. But as to the forward of curl interface underground or “v” figure complex model, it is difficult to realize. So it is important to forward the complex geoelectricity model. This paper takes two Maxwell’s vorticity equations as departure point, makes use of the principles of Yee’s space grid model theory and the basic principle finite difference time domain method, and deduces a GPR forward system of equation of two dimensional spaces. The Mur super absorbed boundary condition is adopted to solve the super strong reflection on the interceptive boundary when there is the forward simulation. And a self-made program is used to process forward simulation to two typical geoelectricity model.

Real-time measurement of welding temperature field and closed loop control of penetration

Colormetric method of images by using two different wavelength images is a new measuring method for welding temperature field on the basis of ordinary colorimetric method, which depends little on the measuring distance, emissivity of body etc. In this paper the real time measuring system and measuring principle of welding temperature field are described, the whole welding temperature field is real time measured, so the temperature distribution at the welding direction and its cross section is obtained, then parameters of thermal cycle. With data from the temperature closed loop control system of the parameters of temperature field is developed and tested. Experimental results prove that it has high measurement speed (time of a field within 0.5 s ) and good dynamic response quality. Weld penetration can be controlled satisfactorily under the variation of welding condition such as welding thickness, welding speed and weldment gap etc.

Discrete Element Modelling of Dynamic Behaviour of Rockfills forResisting High Speed Projectile Penetration

This paper presents a convex polyhedral based discrete element method for modelling the dynamic behaviour ofrockfills for resisting high speed projectile penetration. The contact between two convex polyhedra is defined by theMinkowski overlap and determined by the GJK and EPA algorithm. The contact force is calculated by a Minkowskioverlap based normal model. The rotational motion of polyhedral particles is solved by employing a quaternionbased orientation representation scheme. The energy-conserving nature of the polyhedral DEM method ensures arobust and effective modelling of convex particle systems. The method is applied to simulate the dynamic behaviourof a rockfill system under impact of a high speed projectile. The rockfill sample is generated by a three-dimensionalVoronoi meso method with a specific particle size distribution. The penetrating process of the projectile strikingthe rockfill target is simulated. Some physical quantities associated with the projectile such as the residual velocity,penetration resistance, and deflection angle are monitored which can reflect the influence of the characteristics ofthe rockfill target on its anti-penetration performance. It can be concluded that the developed polyhedral DEMmethod is a very promising numerical approach in analysing the dynamic behaviour of rockfill systems subject tohigh speed projectile impact.

An element-free Galerkin method for ground penetrating radar numerical simulation

An element-free Galerkin method(EFGM) is used to solve the two-dimensional(2D) ground penetrating radar(GPR)modelling problems, due to its simple pre-processing, the absence of elements and high accuracy. Different from element-based numerical methods, this approach makes nodes free from the elemental restraint and avoids the explicit mesh discretization. First, we derived the boundary value problem for the 2D GPR simulation problems. Second, a penalty function approach and a boundary condition truncated method were used to enforce the essential and the absorbing boundary conditions, respectively. A three-layered GPR model was used to verify our element-free approach. The numerical solutions show that our solutions have an excellent agreement with solutions of a finite element method(FEM). Then, we used the EFGM to simulate one more complex model to show its capability and limitations. Simulation results show that one obvious advantage of EFGM is the absence of element mesh, which makes the method very flexible. Due to the use of MLS fitting, a key feature of EFM, is that both the dependent variable and its gradient are continuous and have high precision.

Neutron penetration in labyrinths under different beam losses

Multiple analytical methods and Monte Carlo simulations were performed to evaluate neutron penetration in straight and curved labyrinths. Factors studied included variations in beam losses of off-axis point source,on-axis point source,and line source. For the straight labyrinth, it was found that the analytical expressions neglect the dose rate platform appearing at the bend of the labyrinth, and the agreement between analytical methods and Monte Carlo estimation was related to the type of neutron source term. For the curved labyrinth, the neutron attenuation length obtained under different conditions was nearly identical and appeared to be in quite good accord with the empirical formula calculation. Moreover, the neutron energy spectra along the centerline distance of the labyrinth were also analyzed. In the first leg, differences in beam loss led to variance in the distribution of spectra,while in the second and subsequent legs, the spectra were similar, where the main contributors were thermal neutrons. This work is valuable for practical design of the labyrinths in the accelerator facilities.

Obtaining 2D Soil Resistance Profiles from the Integration of Electrical Resistivity Data and Standard Penetration Test (SPT) and Light Dynamic Penetrometer (DPL) Resistance Tests—Applications in Mass Movements Studies

In Brazil and various regions globally, the initiation of landslides is frequently associated with rainfall;yet the spatial arrangement of geological structures and stratification considerably influences landslide occurrences. The multifaceted nature of these influences makes the surveillance of mass movements a highly intricate task, requiring an understanding of numerous interdependent variables. Recent years have seen an emergence in scholarly research aimed at integrating geophysical and geotechnical methodologies. The conjoint examination of geophysical and geotechnical data offers an enhanced perspective into subsurface structures. Within this work, a methodology is proposed for the synchronous analysis of electrical resistivity geophysical data and geotechnical data, specifically those extracted from the Light Dynamic Penetrometer (DPL) and Standard Penetration Test (SPT). This study involved a linear fitting process to correlate resistivity with N10/SPT N-values from DPL/SPT soundings, culminating in a 2D profile of N10/SPT N-values predicated on electrical profiles. The findings of this research furnish invaluable insights into slope stability by allowing for a two-dimensional representation of penetration resistance properties. Through the synthesis of geophysical and geotechnical data, this project aims to augment the comprehension of subsurface conditions, with potential implications for refining landslide risk evaluations. This endeavor offers insight into the formulation of more effective and precise slope management protocols and disaster prevention strategies.

Application of geophysical methods in fine detection of urban concealed karst:A case study of Wuhan City,China

The construction of modern livable cities faces challenges in karst areas,including ground collapse and engineering problems.Wuhan,with a population of 13.74×10^(6) and approximately 1161 km^(2)of soluble rocks in the urban area of 8569.15 km^(2),predominantly consists of concealed karst areas where occasional ground collapse events occur,posing significant threats to underground engineering projects.To address these challenges,a comprehensive geological survey was conducted in Wuhan,focusing on major karstrelated issues.Geophysical methods offer advantages over drilling in detecting concealed karst areas due to their efficiency,non-destructiveness,and flexibility.This paper reviewed the karst geological characteristics in Wuhan and the geophysical exploration methods for karst,selected eight effective geophysical methods for field experimentation,evaluated their suitability,and proposed method combinations for different karst scenarios.The results show that different geophysical methods have varying applicability for karst detection in Wuhan,and combining multiple methods enhances detection effectiveness.The specific recommendations for method combinations provided in this study serve as a valuable reference for karst detection in Wuhan.

论《广瘟疫论》透疫四法对吴又可透疫理念的继承与发挥

吴又可善用透法治疗疫病,对后世影响深远。清代名医戴天章在吴氏学说基础上撰成《广瘟疫论》,书中对通腑透邪、逐瘀泄热、开达膜原、滋养透邪透疫四法论述尤为深入,具有重要指导意义。本文深入剖析戴天章《广瘟疫论》透疫四法,主要包括开达膜原明辨表里,注重“孤邪”;通腑透邪力辟寒温,“三分”指征,细化治方;逐瘀泄热倡用“蓄血三焦辨证”;论广滋养透邪,增述“五变”,从中探寻其对吴又可透疫理念的继承与发挥,如疫邪在半表半里之时达原饮和柴胡剂之运用区分、开达膜原之“孤邪”加味法、通腑透邪六大用药手法、“厥阴蓄血”证治等,以期对现代临床提供助力。

THREE-DIMENSIONAL TRAJECTORY OPTIMIZATION WITH DIRECT METHOD

The principle of direct method used in optimal control problem is introduced. Details of applying this method to flight trajectory generation are presented including calculation of velocity and controls histories. And capabilities of flight and propulsion systems are considered also. Combined with digital terrain map technique, the direct method is applied to the three dimensional trajectory optimization for low altitude penetration, and simplex algorithm is used to solve the parameters in optimization. For the small number of parameters, the trajectory can be optimized in real time on board.

基于多功能探管仪的PE燃气管道探测应用分析

PE管作为燃气管网系统的重要组成部分,具有非金属、不导电、不导磁特性,给燃气管道探测工作造成一定的难度。常规的燃气管道探测技术易受信号干扰、埋深、应用条件等因素限制,不能满足PE管燃气探测工作,选择合适的方法准确定位埋地PE管道对企业管网安全运行管理具有十分重要的意义。本文以信阳市平桥区燃气PE管道探测为例,系统地阐述了多功能探管仪的工作原理和定位方法,分析了管线特征点的确定方法,并通过现场开挖对多功能探管仪燃气探测的可行性、准确性进行了验证,为后续同类项目的实施提供了一定的参考。

劣化润滑脂对新能源汽车电机轴承性能的影响

为研究不同劣化时期润滑脂对新能源汽车电机轴承性能的影响,并选取合适的润滑脂,采用试验的方法,研究了两种候选润滑脂及其对轴承性能的影响。首先,采用静态热劣化法获得了21组不同劣化时期的润滑脂样品,并分析了润滑脂样品的锥入度、分油率等特性变化;然后,在考虑轴承工况的基础上,利用高速轴承漏脂温升性能试验机等设备试验研究了不同劣化时间润滑脂对轴承漏脂、温升、振动和噪音等性能的影响;最后,综合分析了润滑脂的劣化及其对轴承性能的影响,为新能源汽车电机轴承选择了合适的润滑脂。研究结果表明:A型润滑脂的性能更稳定,其非工作锥入度变化率为32.53%,分油率在0~0.053%范围内波动,其特性变化均小于B型润滑脂;两种劣化润滑脂均导致轴承外圈温度升高、轴承振动速度和噪音增大,但B型润滑脂对轴承振动速度和噪音的影响较大,其部分高频增加900%、噪音升高27%。因此,综合考虑润滑脂的分油率、锥入度,以及润滑脂对轴承温升、振动和噪音等使用性能的影响,推荐A型润滑脂为新能源汽车电机轴承润滑介质。该研究结果对新能源汽车电机轴承润滑介质的选择具有较为重要指导意义。

Data processing and initial results of Chang'e-3 lunar penetrating radar

To improve our understanding of the formation and evolution of the Moon, one of the payloads onboard the Chang＇e-3 （CE-3） rover is Lunar Penetrating Radar （LPR）. This investigation is the first attempt to explore the lunar subsurface structure by using ground penetrating radar with high resolution. We have probed the subsur- face to a depth of several hundred meters using LPR. In-orbit testing, data processing and the preliminary results are presented. These observations have revealed the con- figuration of regolith where the thickness of regolith varies from about 4 m to 6 m. In addition, one layer of lunar rock, which is about 330 m deep and might have been accumulated during the depositional hiatus of mare basalts, was detected.

Discussion on applying an analytical method to optimize the anti-freeze design parameters for underground water pipelines in seasonally frozen areas

Adopting the quasi-three-dimensional （Quasi-3D） numerical method to optimize the anti-freeze design parameters of an underground pipeline usually involves heavy numerical calculations. Here, the fitting formulae between the safe con-veyance distance （SCD） of a water pipeline and six influencing factors are established based on the lowest water temper-ature （LWT） along the pipeline axis direction. With reference to the current widely used anti-freeze design approaches for underground pipelines in seasonally frozen areas, this paper first analyzes the feasibility of applying the maximum frozen penetration （MFP） instead of the mean annual ground surface temperature （MAGST） and soil water content （SWC） to calculate the SCD. The results show that the SCD depends on the buried depth if the MFP is fixed and the variation of the MAGST and SWC combination does not significantly change the SCD. A comprehensive formula for the SCD is estab-lished based on the relationships between the SCD and several primary influencing factors and the interaction among them. This formula involves five easy-to-access parameters： the MFP, buried depth, pipeline diameter, flow velocity, and inlet water temperature. A comparison between the analytical method and the numerical results based on the Quasi-3D method indicates that the two methods are in good agreement overall. The analytic method can be used to optimize the anti-freeze design parameters of underground water pipelines in seasonally frozen areas under the condition of a 1.5 safety coefficient.