Co and postseismic fault slip models of the 2022 M_(W)6.7 Menyuan earthquake reveal conjugated faulting tectonics at the central section of the Lenglongling fault

The 2022 M_(W)6.7 Menyuan earthquake ruptured the western end of the Tianzhu seismic gap,providing an opportunity to study the regional seismogenic characteristics and seismic hazards.Here we use interferometric synthetic aperture radar(InSAR)and seismic data to study the mainshock rupture,early afterslip and the second largest aftershock of the 2022 Menyuan earthquake sequences.Our modeling results show that the mainshock ruptured the Lenglongling fault and the Tuolaishan fault with a maximum slip of~3 m.Rapid postseismic transient deformation occurred at the center of the Lenglongling fault.Our afterslip modeling reveals that the majority of afterslip occurred in the deeper part of the Lenglongling fault.A high-angle conjugated faulting event is found at the middle section of the Lenglongling fault.We use the stress inversion to investigate the possible triggering mechanism of the conjugated rupture event.The results indicate the maximum principal stress direction is in~222°,forming a~22°angle between the conjugated fault of second largest aftershock and the mainshock.The calculated normal stress changes indicate the region is within a pull-apart stress field,which favors such a conjugated rupturing event.Our study will help understand the rupture behavior of such kind of conjugated fault in other regions.

足式机器人SLIP模型向上跳跃台阶的运动控制

由于存在地势起伏,台阶对足式机器人运动稳定性会带来较大挑战.弹簧负载倒立摆模型(SLIP)作为研究足式机器人的优良模板,能否完成向上跳跃台阶的动作与其腿部摆角,起跳位置和跳跃高度都有密切的关系.由于调整模型腿部摆角规律容易引发运动失效,故本文在算法中引入虚拟弹簧腿,根据虚拟弹簧腿的运行规律确定合理起跳位置,根据起跳位置来控制系统跳跃高度进而完成跳跃台阶的动作.最后利用仿真软件进行多组仿真,结果表明本文算法对起跳区间划分合理,对起跳高度控制精准,能够实现SLIP模型跳跃台阶前后的稳定运动.

Revealing the role of pyramidal slip in the high ductility of Mg-Li alloy

The high ductility of Mg-Li alloy has been mainly ascribed to a high activity of pyramidal<c+a>slip to accommodate plastic strain.In the present study,however,a quantitative analysis reveals that Li-addition can only slightly stimulate the activation of pyramidal<c+a>slip under compression along the normal direction of a hot-rolled Mg-4.5 wt.%Li plate,with a relative activity of approximately 18%.Although the limited activity of pyramidal<c+a>slip alone cannot accommodate a large plastic strain,it effectively reduces the number of{10.11}−{10.12}double twins,which are believed to be favorable sites for crack initiation.The evidently reduced activity of double twins leads to a lower cracking tendency,and therefore improves ductility.

液体润滑浸渍表面(SLIPS)船舶防污涂层最新研究进展

综述了近3年来关于液体润滑浸渍表面(SLIPS)船舶防污涂层的研究进展,特别是润滑液的选择与涂层的结构设计,以及这些因素如何影响涂层的整体性能,以期为未来的研究提供最新思路及研究方法。

Coseismic deformation and fault slip distribution of the 2023 M_(W)7.8 and M_(W)7.6 earthquakes in Türkiye

On February 6,2023,a devastating earthquake with a moment magnitude of M_(W)7.8 struck the town of Pazarcik in south-central Türkiye,followed by another powerful earthquake with a moment magnitude of M_(W)7.6 that struck the nearby city of Elbistan 9 h later.To study the characteristics of surface deformation caused by this event and the influence of fault rupture,this study calculated the static coseismic deformation of 56 stations and dynamic displacement waveforms of 15 stations using data from the Turkish national fixed global navigation satellite system(GNSS)network.A maximum static coseismic displacement of 0.38 m for the M_(W)7.8 Kahramanmaras earthquake was observed at station ANTE,36 km from the epicenter,and a maximum dynamic coseismic displacement of 4.4 m for the M_(W)7.6 Elbistan earthquake was observed at station EKZ1,5 km from the epicenter.The rupture-slip distributions of the two earthquakes were inverted using GNSS coseismic deformation as a constraint.The results showed that the Kahramanmaras earthquake rupture segment was distinct and exposed on the ground,resulting in significant rupture slip along the Amanos and Pazarcik fault segments of the East Anatolian Fault.The maximum slip in the Pazarcik fault segment was 10.7 m,and rupture occurred at depths of 0–15 km.In the Cardak fault region,the Elbistan earthquake caused significant ruptures at depths of 0–12 km,with the largest amount of slip reaching 11.6 m.The Coulomb stress change caused by the Kahramanmaras earthquake rupture along the Cardak fault segment was approximately 2 bars,and the area of increased Coulomb stress corresponded to the subsequent rupture region of the M_(W)7.6 earthquake.Thus,it is likely that the M_(W)7.8 earthquake triggered or promoted the M_(W)7.6 earthquake.Based on the cumulative stress impact of the M_(W)7.8 and M_(W)7.6 events,the southwestern segment of the East Anatolian Fault,specifically the Amanos fault segment,experienced a Coulomb rupture stress change exceeding 2 bars,warranting further attention to assess its future seismic hazard risk.

Effect of pre-deformation on precipitation behavior of AZ80 alloy:Comparison of slip-and twinning-dominant deformation

This study investigates the effect of the deformation mode on the precipitation behavior of an extruded Mg-8.0Al-0.5Zn-0.2Mn(AZ80)alloy.The alloy samples are compared after the application of 3.5%tension and 3.5%compression along the extrusion direction to induce slip-dominant and twinning-dominant deformation modes,respectively.The pre-compressed(PC)sample,which contained numerous{10-12}tension twins,has a reduced grain size and a higher internal strain than the pre-tensioned(PT)sample,which is attributed to the inherent internal strain that occurs during the formation and growth of the twins.As a result,the precipitation behavior of the PC sample is accelerated,leading to its short peak aging time of 32 h,which is lower than those of the PT and as-extruded samples(48 and 100 h,respectively).Furthermore,fine continuous precipitates(CPs)rapidly form within the{10-12}twins,contributing to the enhanced hardness.Discontinuous precipitates(DPs),which have a hardness comparable to the CP-containing twinned regions,in the PC sample experience less coarsening during aging than those in the PT sample due to growth inhibition by the{10-12}twins.Ultimately,the{10-12}twins generated under the twinning-dominant deformation condition lead to enhanced precipitation behaviors,including the preferential formation and refinement of CPs and the suppressed coarsening of DPs.Consequently,pre-deformation that occurs{10-12}twinning exhibits more pronounced effects on precipitation acceleration and microstructural modification than slip-inducing pre-deformation.

Experimental investigation on fluid-induced slip behavior of fault filled with fault gouge

Fault zones are usually filled with fault gouge and accompanied by fault water.The coupled effect of fault gouge and water significantly impacts the slip behavior of the fault,which may weaken the fault structure and further induce rupture propagation and earthquakes.In this study,we carried out a laboratory experiment to investigate the fluid-induced slip behavior of fault filled with gouge.The friction evolution characteristic associated with fluid pressure and effective stress was investigated during the slip process.In addition,the role transformation process of the gouge on the slip behavior of fault was revealed.The experimental result indicates that the friction on the filled fault surface is significantly affected by fault gouge.The rupture of the gouge promotes fault slip and the fluid pressure plays a vital role in the initiation of fault slip.The fault gouge enhances the shearing strength of the fault and acts as a barrier before the initial slip under fluid injection.Nevertheless,the fault gouge would accelerate the fault slip and transform into lubricant after the initial slip.

Effect of boundary slip on electroosmotic flow in a curved rectangular microchannel

The aim of this study is to numerically investigate the impact of boundary slip on electroosmotic flow(EOF) in curved rectangular microchannels. Navier slip boundary conditions were employed at the curved microchannel walls. The electric potential distribution was governed by the Poisson–Boltzmann equation, whereas the velocity distribution was determined by the Navier–Stokes equation. The finite-difference method was employed to solve these two equations. The detailed discussion focuses on the impact of the curvature ratio, electrokinetic width, aspect ratio and slip length on the velocity. The results indicate that the present problem is strongly dependent on these parameters. The results demonstrate that by varying the dimensionless slip length from 0.001 to 0.01 while maintaining a curvature ratio of 0.5 there is a twofold increase in the maximum velocity. Moreover, this increase becomes more pronounced at higher curvature ratios. In addition, the velocity difference between the inner and outer radial regions increases with increasing slip length. Therefore, the incorporation of the slip boundary condition results in an augmented velocity and a more non-uniform velocity distribution. The findings presented here offer valuable insights into the design and optimization of EOF performance in curved hydrophobic microchannels featuring rectangular cross-sections.

Interseismic slip distribution and locking characteristics of the mid-southern segment of the Tanlu fault zone

We employ the block negative dislocation model to invert the distribution of fault coupling and slip rate deficit on the different segments of the Tanlu(Tancheng-Lujiang) fault zone, according to the GPS horizontal velocity field from 1991 to 2007(the first phase) and 2013 to 2018(the second phase). By comparing the deformation characteristics results, we discuss the relationship between the deformation characteristics with the M earthquake in Japan. The results showed that the fault coupling rate of the northern section of Tancheng in the second phase reduced compared with that in the first phase. However, the results of the two phases showed that the northern section of Juxian still has a high coupling rate, a deep blocking depth, and a dextral compressive deficit, which is the enrapture section of the 1668 Tancheng earthquake. At the same time, the area strain results show that the strain rate of the central and eastern regions of the second phase is obviously enhanced compared with that of the first phase. The occurrence of the great earthquake in Japan has played a specific role in alleviating the strain accumulation in the middle and south sections of the Tanlu fault zone. The results of the maximum shear strain show that the shear strain in the middle section of the Tanlu fault zone in the second phase is weaker than that in the first phase, and the maximum shear strain in the southern section is stronger than that in the first phase. The fault coupling coefficient of the south Sihong to Jiashan section is high, and it is also the unruptured section of historical earthquakes. At the same time, small earthquakes in this area are not active and accumulate stress easily, so the future earthquake risk deserves attention.

Risk factors and clinical significance of posterior slip of the proximal vertebral body after lower lumbar fusion

BACKGROUND Adjacent segment disease(ASD)after fusion surgery is frequently manifests as a cranial segment instability,disc herniation,spinal canal stenosis,spondylolisthesis or retrolisthesis.The risk factors and mechanisms of ASD have been widely discussed but never clearly defined.AIM To investigate the risk factors and clinical significance of retrograde movement of the proximal vertebral body after lower lumbar fusion.METHODS This was a retrospective analysis of the clinical data of patients who underwent transforaminal lumbar interbody fusion surgery between September 2015 and July 2021 and who were followed up for more than 2 years.Ninety-one patients with degenerative lumbar diseases were included(22 males and 69 females),with an average age of 52.3 years(40-73 years).According to whether there was retrograde movement of the adjacent vertebral body on postoperative X-rays,the patients were divided into retrograde and nonretrograde groups.The sagittal parameters of the spine and pelvis were evaluated before surgery,after surgery,and at the final follow-up.At the same time,the Oswestry Disability Index(ODI)and Visual Analogue Scale(VAS)were used to evaluate the patients’quality of life.RESULTS Nineteen patients(20.9%)who experienced retrograde movement of proximal adjacent segments were included in this study.The pelvic incidence(PI)of the patients in the retrograde group were significantly higher than those of the patients in the nonretrograde group before surgery,after surgery and at the final follow-up(P<0.05).There was no significant difference in lumbar lordosis(LL)between the two groups before the operation,but LL in the retrograde group was significantly greater than that in the nonretrograde group postoperatively and at the final follow-up.No significant differences were detected in terms of the|PI–LL|,and there was no significant difference in the preoperative lordosis distribution index(LDI)between the two groups.The LDIs of the retrograde group were 68.1%±11.5%and 67.2%±11.9%,respectively,which were significantly lower than those of the nonretrograde group(75.7%±10.4%and 74.3%±9.4%,respectively)(P<0.05).Moreover,the patients in the retrograde group had a greater incidence of a LDI<50%than those in the nonretrograde group(P<0.05).There were no significant differences in the ODI or VAS scores between the two groups before the operation,but the ODI and VAS scores in the retrograde group were significantly worse than those in the nonretrograde group after the operation and at the last follow-up,(P<0.05).CONCLUSION The incidence of posterior slippage after lower lumbar fusion was approximately 20.9%.The risk factors are related to a higher PI and distribution of lumbar lordosis.When a patient has a high PI and insufficient reconstruction of the lower lumbar spine,adjacent segment compensation via posterior vertebral body slippage is one of the factors that significantly affects surgical outcomes.

The advance in obtaining fault slip rate of strike slip fault-A review

Slip rate along the major active fault is an important parameter in the quantitative study of active tectonics.It is the average rate of fault slip during a certain period of time,reflecting the rate of strain energy accumulation on the fault zone.It cannot only be directly applied to evaluate the activity of the fault,the probabilistic seismic hazard analysis,but also important basic data for the study of geodynamics.However,due to the nonstandardized process of obtaining fault slip rates for a given strike-slip fault,the results could be diverse based on various methods by different researchers.In this review,we analyzed the main advances in the approaches to obtain fault slip rate.We found that there are four main sources affecting the final results of slip rate:the displacement along the fault,the dating of the corresponding displacement,the fitting of the displacement and corresponding dating results,and paleoslip analysis.The main advances in obtaining fault slip rates are based on improving the reli-ability of the above four main factors.To obtain a more reasonable and reliable slip rate for a given fault,it is necessary to select a suitable method according to the specific situation.

SLIP算法的几种变形算法

SLIP算法是目前在实际中应用较多的输入排队调度算法。本文描述了SLIP算法,并介绍了SLIP算法与多次迭代SLIP算法的几种变形算法,并对所述变形算法的进一步扩展提出了建议与展望。

Time-SLIP、CE-MRA、DSA在颈动脉斑块管腔狭窄检查的对照研究

目的:评估Time-SLIP血管成像的成像质量,评价Time-SLIP、CE-MRA以及DSA在颈动脉狭窄度评估方面的差异。方法:(1)35例具有颈动脉斑块的患者先后使用磁共振进行Time-SLIP和CE-MRA扫描,其中10例患者三天后进一步行颈动脉DSA检查。(2)在获取Time-SLIP和CE-MRA颈动脉血管图像后分别由两位副高级影像诊断医师对每幅图像质量、组织污染情况进行技术评分。(3)对Time-SLIP、CEMRA显示的血管数量进行评价。(4)对其中进行过DSA检查的10例患者,以NASCET法计算上述三种方法显示的颈动脉血管狭窄率。结果:(1)35例患者,Time-SLIP组和CE-MRA组中,图像质量为3分以上者分别占94.2%、97.1%;组织污染评分小于等于1分者分别占88.6%、82.9%;双侧颈动脉总共210条血管,Time-SLIP和CE-MRA分别显示两侧颈总动脉、颈内动脉及颈外动脉血管为199/210条和202/210条,其符合率分别为94.8%和96.2%。上述诊断两位医师的一致性较高,Kappa值>0.80,两种方法的差异无统计学意义(P>0.05)。(2)其中接受DSA检查的10例患者,以DSA诊断为金标准,在颈动脉狭窄的诊断中Time-SLIP诊断的敏感性92.31%,特异性97.87%,准确性96.67%,Kappa=0.90;CE-MRA诊断的敏感性100%,特异性97.87%,准确率98.33%,Kappa=0.95。结论:(1)Time-SLIP是一种无创MRA成像技术,成像质量较好。(2)Time-SLIP可以用于颈动脉狭窄评估。(3)由于Time-SLIP技术能有效提示管腔狭窄程度,因此其有较高的临床应用价值。

Influence of Tire Slip Angle on Adhesion CoefficientCharacteristic of Road Vehicles

Tire slip angle has a great influence on peak values of both logitudinal and lateral adhesion coefficients as well as optimal slip ratios. Regression equations based on the experi- mental data from several countries are given to describe their dependencies. The peak value of longitudiinal adhesion coefficient has a linear relationship with tire slip angle, but peak value of lateral has a complicated relationship; the optimal slip ratio of longitudinal has an exponent function relationship, the optimal slip ratio of lateral almost has nothinng to do with tire slipangle.

Experimental analysis of the slip sinkage effect based on real vehicle test

To improve the semi-empirical model, the slip sinkage effect is analyzed based on the real vehicle test. A dynamic testing system is used to gain the dynamic responses of wheel-soil interactions, The Gauss-Newton algorithm is adopted to estimate the undetermined parameters involved in the slip sinkage models. Wong＇s original model is compared with three typical slip sinkage models on the prediction performance of a drawbar pull. The maximum error rate, root mean squared error and correlation coefficient are utilized to evaluate the performance. The results indicate that the slip sinkage models outperform Wong＇s model and greatly improve the prediction accuracy. Lyasko＇s model is confirmed as an outstanding one for its comprehensive performance. Hence, the existence of the slip sinkage effect is validated. Lyasko＇s model is selected as an optimal one for the practical evaluation of military vehicle trafficability.

柔性双段腿的SLIP模型参数敏感性分析

为了反映腿部多段串联的多参数耦合特性,以SLIP(spring loaded inverted pendulum)模型为基础,建立了小腿含有串联线性伸缩弹簧的机器人柔性双段腿动力学模型。通过仿真分析其运动,获得柔性双段腿弹簧刚度、触地角度、虚拟腿长、膝关节角度、质量分布等参数的稳定域。通过对各个参数稳定域进行归一化处理和曲线拟合,获得参数稳定域变化曲线及参数敏感度排序。最后基于ADAMS与MATLAB联合仿真验证了柔性双段腿模型中参数敏感度排序的正确性。

Late-Quaternary Slip Rate and Seismic Activity of the Xianshuihe Fault Zone in Southwest China

The Xianshuihe fault zone is a seismo-genetic fault zone of left-lateral slip in Southwest China. Since 1725, a total of 59 Ms ≥ 5.0 earthquakes have occurred along this fault zone, including 18 Ms 6.0–6.9 and eight Ms ≥ 7.0 earthquakes. The seismic risk of the Xianshuihe fault zone is a large and realistic threat to the western Sichuan economic corridor. Based on previous studies, we carried out field geological survey and remote sensing interpretation in the fault zone. In addition, geophysical surveys, trenching and age-dating were conducted in the key parts to better understand the geometry, spatial distribution and activity of the fault zone. We infer to divide the fault zone into two parts： the northwest part and the southeast part, with total eight segments. Their Late Quaternary slip rates vary in a range of 11.5 mm/a –（3±1） mm/a. The seismic activities of the Xianshuihe fault zone are frequent and strong, periodical, and reoccurred. Combining the spatial and temporal distribution of the historical earthquakes, the seismic hazard of the Xianshuihe fault zone has been predicted by using the relationship between magnitude and frequency of earthquakes caused by different fault segments. The prediction results show that the segment between Daofu and Qianning has a possibility of Ms ≥ 7.0 earthquakes, while the segment between Shimian and Luding is likely to have earthquakes of about Ms 7.0. It is suggested to establish a GPS or In SAR-based real-time monitoring network of surface displacement to cover the Xianshuihe fault zone, and an early warning system of earthquakes and post seismic geohazards to cover the major residential areas.

基于iSLIP算法的高速Crossbar调度器的FPGA设计与实现

首先介绍了一种公平、有效的交叉矩阵调度算法—— i SLIP算法 ,接着提出了基于 i SLIP算法的调度器的 FPGA(Field Programmable Gate Array)实现 ,并针对调度器的核心部件——可编程优先级编码器 ,介绍了 4种设计方案 ,用 Xilinx公司的 Spartan- S1 0 PC84- 3 FPGA芯片实现。对实现结果的数据分析表明 ,采用温度计编码型 PPE的调度器更适用于构建高速、大容量交换网络。

Cycle slip detection approach based on time-relative positioning theory

An efficient cycle slip detection method is proposed for high precision positioning and navigation results with global positioning system （GPS）,which is based on the assumption of a high sampling interval, measurement errors are so small that they can be ignored in the temporal single difference observables. And ambiguities are ordinarily equal to zero,but could be the number of cycles that have ＂slipped＂ if loss-of-lock has occurred.Therefore,cycle slips are estimated as parameters of time-relative positioning observation equations.Because the temporal single difference observables are taken at different epochs and different stations with a single GPS receiver,if time-relative positioning observation equations are linearized as that of conventional relative positioning,the design matrix will be rank defective.To obtain a stable linearization scheme,time-relative positioning observation equations are further analyzed,and the concept of virtual measurement is applied.A sample of data collected on a vehicle test shows that a cycle slip detection approach based on time-relative positioning theory can detect slips at the value of one cycle.The results also indicate if two satellites are so near to each other that they have the same equivalent to satellite-receiver geometry,cycle slip detection will be difficult and may get wrong results.Cycle slips of different satellites also affect detection by satellite-receiver geometry.

Wheel slip-sinkage and its prediction model of lunar rover

In order to investigate wheel slip-sinkage problem, which is important for the design, control and simulation of lunar rovers, experiments were carried out with a wheel-soil interaction test system to measure the sinkage of three types of wheels in dimension with wheel lugs of different heights and numbers under a series of slip ratios (0-0.6). The curves of wheel sinkage versus slip ratio were obtained and it was found that the sinkage with slip ratio of 0.6 is 3-7 times of the static sinkage. Based on the experimental results, the slip-sinkage principle of lunar's rover lugged wheels (including the sinkage caused by longitudinal flow and side flow of soil, and soil digging of wheel lugs) was analyzed, and corresponding calculation equations were derived. All the factors that can cause slip sinkage were considered to improve the conventional wheel-soil interaction model, and a formula of changing the sinkage exponent with the slip ratio was established. Mathematical model for calculating the sinkage of wheel according to vertical load and slip ratio was developed. Calculation results show that this model can predict the slip-sinkage of wheel with high precision, making up the deficiency of Wong-Reece model that mainly reflects longitudinal slip-sinkage.