Present-day movement characteristics of the Qinghai Nanshan fault and its surrounding area from GPS observation

The Qinghai Nanshan fault is a larger fault in the Northeastern Xizang Plateau.In previous studies,its movement characteristics are mainly investigated with geological and seismic observations,and the tectonic transformation role of the fault on its east is not yet clear.This study uses data fusion to obtain denser GPS observations near the Qinghai Nanshan fault.Based on tectonic characteristics,we establish a block model to investigate the fault slip rate,locking degree,and slip deficit.The results show that the Qinghai Nanshan fault slip rate is characterized by sinistral and convergent movement.Both the sinistral and convergent rates display a decreasing trend from west to east.The locking degree and slip deficit are higher in the western segment(with an average of about 0.74 and 1.1 mm/a)and lower in the eastern segment.Then,we construct a strain rate field using GPS observations to analyze the regional strain characteristics.The results indicate that along the fault,the western segment shows a larger shear strain rate and negative dilation rate.Regional earthquake records show that the frequency of earthquakes is lower near the fault.The joint results suggest that the western segment may have a higher earthquake risk.In addition,the insignificant fault slip rate in the eastern segment may indicate that it does not participate in the tectonic transformation among the Riyueshan,Lajishan,and West Qinling faults.

Experimental study on age and gender differences in microscopic movement characteristics of students

Campus security has aroused many concerns from the whole society.Stampede is one of the most frequent and influential accidents in campus.Studies on pedestrian dynamics especially focusing on students are essential for campus security,which are helpful to improve facility design and emergency evacuation strategy.In this paper,primary and middle school students were recruited to participate in the single-file experiments.The microscopic movement characteristics,including walking speed,headway,gait characteristics(step length,step frequency and swaying amplitude)and their relations were investigated.Age and gender differences in the headway-speed diagram and space requirements were analyzed by statistical tests.The results indicated that the impacts of age and gender were significant.There were three stages for the influence of gender on the headway-speed diagram for both age groups.The impacts on students'space requirements were consistent for different age and gender groups.But the impacts of age and gender on free-flow speed were affected by each other.Due to the connection of walking speed and gait characteristics,the comparisons of gait characteristics between different ages and genders were performed to understand the corresponding differences in speed more deeply.The results showed that differences in step length and swaying amplitude between males and females were significant for both age groups.The effect of gender on step frequency was significant for primary students.But for middle school students,whether gender had significant impact on step frequency was not clear here because of the large P-value.Besides,the influence of age on gait characteristics changed with gender.

Movement characteristics and present seismic activity of Ordos Block

The present horizontal movement of the Ordos Block is the result of the movement interaction between the Ordos Block and the mainland of China.The main dynamic sources are the northeastern pushing by Qinghaie Tibet Block,and the northwestern extension of the northern margin of the block.The latest GPS velocity field observational evidences shows that the velocity field of Ordos Block and around has a significant change from 1999 to 2015,and the change is significant in the northeast margin,the northwest margin,the southwest margin,and the southeast margin of the block.The velocity of left lateral movement of the northsouthern margin of Ordos Block is much larger than the right lateral movement of its eastsouthern margin.By using the seismic data of Ordos Block since 1970,the analysis of strain accumulation,strain release,stress distribution,and stress field show that the northern margin of Ordos Block is the main active area not only in the block edge,but also in North China.The strain around Ordos Block has been accumulating continuously since 2000,and this is the longest period of strain accumulation since 1970.Some signs of strain relief appeared after Alashanzuoqi Ms5.8 earthquake in 2015.There are some areas with extremely large strain anomalies appear in the northern margin of Ordos Block.

Magnetotelluric imaging and tectonic movement characteristics of the central Yunnan sub-block and its adjacent areas

The central Yunnan sub-block is an important channel for southeast migration of materials in the Qinghai-Xizang Plateau,and therefore a key area to study tectonic movement and deformation.In this study,a three-dimensional electrical structure of the crust and upper mantle lithosphere was derived from magnetotelluric data inversion along a survey line across the central Yunnan sub-block.Results suggest that the middle and upper crust of the central Yunnan sub-block is comprised of several independent high-resistivity bodies.Deep extension of some faults was revealed according to electrical structure and relocated microseismicity.The Chenghai fault extends downward along the eastern boundary of a high-resistivity body.The Yuanmou fault dips to the west and extends to the depth along the boundary between two high-resistivity bodies.The Tanglang-Yimen fault cuts through a high-resistivity body in the middle and upper crust.There is an obvious high-conductivity C1 layer in the lower crust in the eastern part of the central Yunnan sub-block,and its western border displays an obvious structural boundary in the shallow part.The eastern part of the central Yunnan sub-block moves eastward relative to the western part(bounded by the west side of a high-resistivity body R3 in the C1 west).C1 is speculated to be characterized by low rheological strength and viscosity,thus reducing the resistance to eastward movement of the eastern part.Owing to the combined action of C1 and its western boundary,the eastern materials slip eastward faster relative to R3.Due to South China Block resistance,the middle and upper crust in the eastern part is within a compressional tectonic environment,consistent with the negative dilatation rate and the presence of compressive faults in this region.The C1 ground surface has a low strain rate,indicating weak deformation in this region and rigid motion dominance.Our results suggest that under the decoupling effect of the high-conductivity layer in the lower crust,the independent rigid blocks in the middle and upper crust can also exhibit tectonic deformation characteristics of rigid extrusion.

Research on the influences of motion characteristics of jetting projectile charge under water

Shaped charge warhead is important for enhancing the damage performance of underwater weapons.This paper used finite element analysis software and based on JPC water penetration experiments to examine the influence of liner parameters(wall thickness,material),charge aspect ratio,and stand-off distance on the movement characteristics of JPC in water.The findings reveal that the head diameter of the JPC increases and experiences significant erosion after entering the water,the effective length of the JPC in water undergoes two distinct phases:a growth phase and a decrease phase,with the velocity of the JPC decaying exponentially.Increasing the liner thickness,stand-off distance and the charge aspect ratio can improve the erosion resistance and the velocity retention capacity of the JPC.The optimal ranges for liner thickness and stand-off distance are 0.0363D_(k) to 0.0545D_(k)(D_(k) is the charge diameter),the stand-off distance should be within 1.0D_(k).After the charge aspect ratio higher than 1.25,the charge structure exerts minimal influence the movement characteristics of the JPC in water.Material density plays a crucial role in the velocity decay pattern of the JPC during penetration.JPC with higher densities exhibit superior velocity retention capabilities in water,with the velocity decay pattern converging if the densities are similar.Consequently,copper,tantalum and tungsten liners are deemed appropriate for underwater shaped charge warhead.Finally,the results will provide an important reference for the design of underwater shaped charge warhead.

Thornthwaite moisture index and depth of suction change under current and future climate‒An Australian study

Climate change is one of the major global challenges and it can have a significant influence on the behaviour and resilience of geotechnical structures.The changes in moisture content in soil lead to effective stress changes and can be accompanied by significant volume changes in reactive/expansive soils.The volume change leads to ground movement and can exert additional stresses on structures founded on or within a shallow depth of such soils.Climate change is likely to amplify the ground movement potential and the associated problems are likely to worsen.The effect of atmospheric boundary interaction on soil behaviour has often been correlated to Thornthwaite moisture index(TMI).In this study,the long-term weather data and anticipated future projections for various emission scenarios were used to generate a series of TMI maps for Australia.The changes in TMI were then correlated to the depth of suction change(H s),an important input in ground movement calculation.Under all climate scenarios considered,reductions in TMI and increases in H s values were observed.A hypothetical design scenario of a footing on expansive soil under current and future climate is discussed.It is observed that a design that might be considered adequate under the current climate scenario,may fail under future scenarios and accommodations should be made in the design for such events.

Experiment and analysis of potato-soil separation based on impact recording technology

In order to discover the damage mechanism and improve separation performance in the separation process of potato-soil mixture,the experiment was conducted on an in-house test-bed.The impact recording device and high-speed camera technology were employed in order to obtain the instantaneous dynamics of the potato-soil mixture for detail data analysis.Five vibration intensities were defined according to the vibration frequency and amplitude.It was found that the mean number of impacts and maximum impact acceleration increased significantly as the level of vibration intensity rose.As a result,the separation performance increased significantly,however,the bruising rate also increased to a certain extent.The mathematical relationship between the maximum impact acceleration and the factors of interest,including vibration amplitude,the vibration frequency and the operating speed of the separation sieves was established through the response surface experiment.It was demonstrated that the presented model was capable to reflect the degree of the factors on influencing bruising rate and separation performance.According to the significance on the maximum impact acceleration,the factors of interest were given in a descending order with vibration frequency,vibration amplitude,running speed of the separation sieve.A set of the optimum operating parameters were found to achieve a desired separation performance as follows,the vibration amplitude was 34.1 mm,the vibration frequency was 5.24 Hz,the running speed of the separation sieve was 2.05 m/s;where the maximum impact acceleration was 98.62 g,the relative error was 3.23%,the bruising rate was 1.81%and the separation performance was 98.5%.The presented model can potentially provide a technical reference for further investigation of the separation mechanism and development of measures for reducing the loss of separation.