Crustal deformation on the Chinese mainland during 1998—2004 based on GPS data

This study focuses on resolving moderate amounts of crustal motion at the continental scale based on a large volume of global positioning system（GPS） data during 1998e2014. A state-of-the-art GPS processing strategy was used to resolve position time series and velocities from carrier beat phases for all available data. Position time series were closely analyzed to estimate linear constant, coseismic displacements, postseismic motions, and other parameters. We present coseismic offsets inferred from the GPS data for the 2010 Yushu and 2014 Yutian earthquakes, and also illustrate transient postseismic motions following the 2001 Kokoxili, 2008 Wenchuan, and 2011 Tohoku-Oki earthquakes. Since not all GPS position time series dominated by postseismic motions can be modeled and corrected reasonably, we present contemporary horizontal velocities from 2009 to 2014 for campaign stations and from 1998 to 2014 for continuous stations, irrespective of postseismic deformations. Our study concludes that we need to accumulate observations over a greater duration and apply accurate postseismic modeling to correct for transient displacement in order to resolve reasonable interseismic velocity.

Numerical simulation of influences of the earth medium's lateral heterogeneity on co- and post-seismic deformation

Many studies revealed that the Earth medium＇s lateral heterogeneity can cause considerable effects on the co- and post-seismic deformation field. In this study, the threedimensional finite element numerical method are adopted to quantify the effects of lateral heterogeneity caused by material parameters and fault dip angle on the co- and postseismic deformation in the near- and far-field. Our results show that： 1） the medium＇s lateral heterogeneity does affect the co-seismic deformation, with the effects increasing with the medium＇s lateral heterogeneity caused by material parameters; 2） the Lame parameters play a more dominant role than density in the effects caused by lateral heterogeneity; 3） when a fault＇s dip angle is smaller than 90, the effects of the medium＇s lateral heterogeneity on the hanging wall are greater than on the footwall; 4） the impact of lateral heterogeneity caused by the viscosity coefficient on the post-seismic deformation can affect a large area, including the near- and far-field.

Evolution of mechanical parameters of Shuangjiangkou granite under different loading cycles and stress paths

Surrounding rocks at different locations are generally subjected to different stress paths during the process of deep hard rock excavation.In this study,to reveal the mechanical parameters of deep surrounding rock under different stress paths,a new cyclic loading and unloading test method for controlled true triaxial loading and unloading and principal stress direction interchange was proposed,and the evolution of mechanical parameters of Shuangjiangkou granite under different stress paths was studied,including the deformation modulus,elastic deformation increment ratios,fracture degree,cohesion and internal friction angle.Additionally,stress path coefficient was defined to characterize different stress paths,and the functional relationships among the stress path coefficient,rock fracture degree difference coefficient,cohesion and internal friction angle were obtained.The results show that during the true triaxial cyclic loading and unloading process,the deformation modulus and cohesion gradually decrease,while the internal friction angle gradually increases with increasing equivalent crack strain.The stress path coefficient is exponentially related to the rock fracture degree difference coefficient.As the stress path coefficient increases,the degrees of cohesion weakening and internal friction angle strengthening decrease linearly.During cyclic loading and unloading under true triaxial principal stress direction interchange,the direction of crack development changes,and the deformation modulus increases,while the cohesion and internal friction angle decrease slightly,indicating that the principal stress direction interchange has a strengthening effect on the surrounding rocks.Finally,the influences of the principal stress interchange direction on the stabilities of deep engineering excavation projects are discussed.

The critical pressure for driving a red blood cell through a contracting microfluidic channel

When a red blood cell （RBC） is driven by a pressure gradient through a microfluidic channel, its passage or blockage provides a measure of the rigidity of the cell. This has been developed as a means to separate RBCs according to their mechanical properties, which are known to change with pathological conditions such as malaria infection. In this study, we use numerical simulations to establish a quantitative connection between the minimum pressure needed to drive an RBC through a contracting microfluidic channel and the rigidity of the cell membrane. This provides the basis for designing such devices and interpreting the experimental data.

STUDY OF CONSTITUTIVE RELATIONS FOR PSEUDO-ELASTICITY AND SHAPE MEMORY BEHAVIOR

Constitutive relations are given for the description of the deformation behavior of shape memory materials. The deformation is the superposition of the elastic, the thermal and the phase transformation deformation caused by the transformation from one to the other among the high temperature phase, the low temperature phase and the stress induced phase. The phase transformation is controlled by the driving force, i.e., the Gibbs energy difference between the phases.

Dynamic deformation behavior of a face-centered cubic FeCoNiCrMn high-entropy alloy

In this study, mechanical tests were conducted oil a face-centered cubic FeCoNiCrMn high-entropy alloy, both in tension and compression, in a wide range of strain rates （10^-4-10^4 s^-1） to systematically investigate its dynamic response and underlying deformation mechanism. Materials with different grain sizes were tested to understand the effect of grain size, thus grain boundary volume, on the mechanical prop-erties. Microstructures of various samples both before and after deformation were examined using elec-tron backscatter diffraction and transmission electron microscopy. The dislocation structure as well as deformation-induced twins were analyzed and correlated with the measured mechanical properties. Plastic stability during tension of the current high-entropy alloy （HEA）, in particular, at dynamic strain rates, was discussed in lights of strain-rate sensitivity and work hardening rate. It was found that, under dynamic conditions, the strength and uniform ductility increased simultaneously as a result of the mas-sive formation of deformation twins. Specifically, an ultimate tensile strength of 734 MPa and uniform elongation of-63% are obtained at 2.3×10^3 s^-1, indicating that the alloy has great potential for energy absorption upon impact loading.

Global case studies of soft-sediment deformation structures(SSDS): Definitions,classifications, advances, origins, and problems

Soft-sediment deformation structures（SSDS）have been the focus of attention for over 150 years.Existing unconstrained definitions allow one to classify a wide range of features under the umbrella phrase＂SSDS＂.As a consequence,a plethora of at least 120 different types of SSDS（e.g.,convolute bedding,slump folds,load casts,dish-and-pillar structures,pockmarks,raindrop imprints,explosive sandegravel craters,clastic injections,crushed and deformed stromatolites,etc.）have been recognized in strata ranging in age from Paleoproterozoic to the present time.The two factors that control the origin of SSDS are prelithification deformation and liquidization.A sedimentological compendium of 140 case studies of SSDS worldwide,which include 30 case studies of scientific drilling at sea（DSDP/ODP/IODP）,published during a period between 1863and 2017,has yielded at least 31 different origins.Earthquakes have remained the single most dominant cause of SSDS because of the prevailing＂seismite＂mindset.Selected advances on SSDS research are：（1）an experimental study that revealed a quantitative similarity between raindrop-impact cratering and asteroid-impact cratering;（2）IODP Expedition 308 in the Gulf of Mexico that documented extensive lateral extent（〉12 km）of mass-transport deposits（MTD）with SSDS that are unrelated to earthquakes;（3）contributions on documentation of pockmarks,on recognition of new structures,and on large-scale sediment deformation on Mars.Problems that hinder our understanding of SSDS still remain.They are：（1）vague definitions of the phrase＂soft-sediment deformation＂;（2）complex factors that govern the origin of SSDS;（3）omission of vital empirical data in documenting vertical changes in facies using measured sedimentological logs;（4）difficulties in distinguishing depositional processes from tectonic events;（5）a model-driven interpretation of SSDS（i.e.,earthquake being the singular cause）;（6）routine application of the genetic term＂seismites＂to the＂SSDS＂,thus undermining the basic tenet of process sedimentology（i.e.,separation of interpretation from observation）;（7）the absence of objective criteria to differentiate 21 triggering mechanisms of liquefaction and related SSDS;（8）application of the process concept＂high-density turbidity currents＂,a process that has never been documented in modern oceans;（9）application of the process concept＂sediment creep＂with a velocity connotation that cannot be inferred from the ancient record;（10）classification of pockmarks,which are hollow spaces（i.e.,without sediments）as SSDS,with their problematic origins by fluid expulsion,sediment degassing,fish activity,etc.;（11）application of the Earth＇s climate-change model;and most importantly,（12）an arbitrary distinction between depositional process and sediment deformation.Despite a profusion of literature on SSDS,our understanding of their origin remains muddled.A solution to the chronic SSDS problem is to utilize the robust core dataset from scientific drilling at sea（DSDP/ODP/IODP）with a constrained definition of SSDS.

Crustal deformation and tectonic levels of Nujiang Gorge since the Miocene

Crustal deformation shows different patterns at different depths due to changes in the physical properties of rock.Tectonic levels can be defined based on the geometry and deformation mechanisms of crustal deformation patterns. Nujiang Gorge, with a high riverbed drop, great erosion depth, and strong deformation, has rock exposures at different tectonic levels and thus provides an ideal lab for deformation study. This paper takes the Nujiang Gorge from Chawalong to Fugong as the object to identify structural deformation patterns at different depths through field study and deformation analysis. At depth, the primary form of deformation is flow deformation, as shown on the outcrops at Maji. Ductile shear deformation can be found in many outcrops within the study region, e.g., the Gaoligong dextral shear zone and Puladi-Songta sinistral shear zone that lie to the south and north of Maji, respectively. Further to the north of Puladi, the dominated deformation pattern is similar fold and dense sub-vertical foliation. In addition, brittle faults, as evidence of shallow deformation, can be seen overprinting on the deeper deformation features all over the region. Based on those observations, this paper identifies four tectonic levels from depth to the surface: flow deformation, ductile shear deformation, similar fold, and brittle fault deformation, all of which result from the NEE-SWW compressive stress field. Further evidence from studies on the region′s thermal evolution and regional tectonics suggests that the development of different tectonic levels is closely linked to the discrepant uplift or denudation since the Miocene(~21 Ma).

Evolution of microstructure and texture in copper during repetitive extrusion-upsetting and subsequent annealing

The evolution of the microstructure and texture in copper has been studied during repetitive extrusionupsetting（REU） to a total von Mises strain of 4.7 and during subsequent annealing at different temperatures. It is found that the texture is significantly altered by each deformation pass. A duplex 001 ＋ 111 fiber texture with an increased 111 component is observed after each extrusion pass,whereas the 110 fiber component dominates the texture after each upsetting pass. During REU, the microstructure is refined by deformation-induced boundaries. The average cell size after a total strain of 4.7 is measured to be ~0.3 μm. This refined microstructure is unstable at room temperature as is evident from the presence of a small number of recrystallized grains in the deformed matrix. Pronounced recrystallization took place during annealing at 200？C for 1 h with recrystallized grains developing predominantly in high misorientation regions. At 350？C the microstructure is fully recrystallized with an average grain size of only 2.3 μm and a very weak crystallographic texture. This REU-processed and subsequently annealed material is considered to be potentially suitable for using as a material for sputtering targets.

Serration and Noise Behavior in Advanced Materials

The Chinese Materials Research Society（C-MRS）Conference（2015）was held in the Guizhou Park Hotel International Conference Center,Guiyang,China,from July 10-14,2015.This conference consists of 30symposia,including 4international symposia.As one of 4international symposia,＂Serration and noise behavior in advanced materials＂