Ternary Hybrid Nanofluid with First and Second Order Velocity Slips: Dual Solutions with Stability Analysis

Modeling the boundary layer flow of ternary hybrid nanofluids is important for understanding and optimizing their thermal performance,particularly in applications where enhanced heat transfer and fluid dynamics are essential.This study numerically investigates the boundary layer flow of alumina-copper-silver/water nanofluid over a permeable stretching/shrinking sheet,incorporating both first and second-order velocity slip.The mathematical model is solved in MATLAB facilitated by the bvp4c function that employs the finite difference scheme and Lobatto IIIa formula.The solver successfully generates dual solutions for the model,and further analysis is conducted to assess their stability.The findings reported that only one of the solutions is stable.For the shrinking sheet case,increasing the first-order velocity slip delays boundary layer separation and enhances heat transfer,while,when the sheet is stretched,the second-order velocity slip accelerates separation and improves heat transfer.Boundary layer separation is most likely to occur when the sheet is shrinking;however,this can be controlled by adjusting the velocity slip with the inclusion of boundary layer suction.

Blood-based magnetohydrodynamic Casson hybrid nanofluid flow on convectively heated bi-directional porous stretching sheet with variable porosity and slip constraints

Fluid flow through porous spaces with variable porosity has wide-range applications,notably in biomedical and thermal engineering,where it plays a vital role in comprehending blood flow dynamics within cardiovascular systems,heat transfer and thermal management systems improve efficiency using porous materials with variable porosity.Keeping these important applications in view,in current study blood-based hybrid nanofluid flow has considered on a convectively heated sheet.The sheet exhibits the properties of a porous medium with variable porosity and extends in both the x and y directions.Blood has used as base fluid in which the nanoparticles of Cu and Cu O have been mixed.Thermal radiation,space-dependent,and thermal-dependent heat sources have been incorporated into the energy equation,while magnetic effects have been integrated into the momentum equations.Dimensionless variables have employed to transform the modeled equations into dimensionless form and facilitating their solution using bvp4c approach.It has concluded in this study that,both the primary and secondary velocities augmented with upsurge in variable porous factor and declined with escalation in stretching ratio,Casson,magnetic,and slip factors along x-and y-axes.Thermal distribution has grown up with upsurge in Casson factor,magnetic factor,thermal Biot number,and thermal/space-dependent heat sources while has retarded with growth in variable porous and stretching ratio factors.The findings of this investigation have been compared with the existing literature,revealing a strong agreement among present and established results that ensured the validation of the model and method used in this work.

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.

双摩擦块制动系统不同相对位置分布对stick-slip振动的影响

利用定制试验装置,研究圆形双摩擦块不同相对位置分布对制动系统摩擦学行为和动力学行为的影响,并采用有限元方法分析了摩擦块表面接触应力分布特点,探讨了不同相对位置分布与界面接触行为、摩擦磨损以及stick-slip振动之间的关联。综合试验结果和仿真分析结果表明:双摩擦块制动系统不同相对位置分布显著影响了制动系统界面接触压力分布及摩擦块表面磨损特性,使系统产生不同形式的stick-slip振动。在该试验下,沿摩擦盘径向分布的两个摩擦块表面磨损轻微,接触压力分布相对均匀和具有较小的stick-slip振动幅度。因此,合理设计摩擦块间的排布可以有效抑制盘块摩擦界面stick-slip振动,减轻摩擦块的磨损,减小系统部件振荡,从而提高摩擦系统稳定性。研究结果对汽车和火车(特别是高速列车)制动器的设计有较重要的参考价值。

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.

Synergistic effect of orientation and temperature on slip behavior and precipitation behavior of Al−Cu−Li single crystals

The slip behavior and precipitation behavior of four Al−Cu−Li single crystals with varying orientations at different temperatures were investigated using electron backscattering diffraction(EBSD)and transmission electron microscopy(TEM).The maximum differences in yield strength and ductility of the single crystals at room temperature are 41.6%and 14.7%,respectively.This indicates that the mechanical properties are strongly influenced by the crystal orientation.Moreover,grains with varying orientations exhibit distinct slip characteristics,including slip homogenization,slip localization,and multiple slip.In single crystal SC1,slip localization primarily contributes to its inferior ductility compared to other grains.Nevertheless,during deformation at 250℃,the distinct morphology and distribution of precipitates in the crystals are also correlated with orientation,which causes the increase in the maximum elongation difference to 20.8%in all selected single crystals.Notably,SC1,with a precipitate volume fraction of 2.65%,exhibits more severe slip localization compared to room temperature conditions,while SC2,with a precipitate volume fraction of 4.79%,demonstrates cross-slip characteristics,significantly enhancing the plastic deformation capacity of the Al−Cu−Li alloy.

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.

Effects ofslip mode on microstructure evolution and compressive flow behavior of extruded dilute Mg−0.5Bi−0.5Sn−0.5Mn alloy

The influence of the slip mode on the microstructure evolution and compressive flow behavior at different strains in an extruded dilute Mg−0.5Bi−0.5Sn−0.5Mn alloy was analyzed through electron backscatter diffraction,X-ray diffraction,transmission electron microscopy,and hot compression tests.The results showed that at a low strain of 0.05,the basal,pyramidaland<c+a>slip modes were simultaneously activated.Nevertheless,at the middle stage of deformation(strain of 0.1,0.2 and 0.5),theslip mode was difficult to be activated and<c+a>slip mode became dominant.The deformation process between strains of 0.2 and 0.5 was primarily characterized by the softening effect resulting from the simultaneous occurrence of continuous dynamic recrystallization and discontinuous dynamic recrystallization.Ultimately,at strain of 0.8,a dynamic equilibrium was established,with the flow stress remaining constant due to the interplay between the dynamic softening brought about by discontinuous dynamic recrystallization and the work-hardening effect induced by the activation of the basalslip mode.

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.

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.

Chemical Reaction on Williamson Nanofluid’s Radiative MHD Dissipative Stagnation Point Flow over an Exponentially Inclined Stretching Surface with Multi-Slip Effects

A wide range of technological and industrial domains,including heating processors,electrical systems,mechanical systems,and others,are facing issues as a result of the recent developments in heat transmission.Nanofluids are a novel type of heat transfer fluid that has the potential to provide solutions that will improve energy transfer.The current study investigates the effect of a magnetic field on the two-dimensional flow of Williamson nanofluid over an exponentially inclined stretched sheet.This investigation takes into account the presence of multi-slip effects.We also consider the influence of viscous dissipation,thermal radiation,chemical reactions,and suction on the fluid’s velocity.We convert the nonlinear governing partial differential equations(PDEs)of the fluid flow problem into dimensionless ordinary differential equations(ODEs)through the utilization of similarity variables.We then use the homotopy analysis method(HAM)to numerically solve the resulting ordinary differential equations(ODEs).We demonstrate the effects of numerous elements on a variety of profiles through graphical and tabular representations.We observe a drop in the velocity profile whenever we increase either the magnetic number or the suction parameter.Higher values of the Williamson parameter lead to an increase in the thermal profile,while the momentum of the flow displays a trend in the opposite direction.The potential applications of this unique model include chemical and biomolecule detection,environmental cleansing,and the initiation of radiation-induced chemical processes like polymerization,sterilization,and chemical synthesis.

塔里木盆地构造流体作用对超深层断控碳酸盐岩缝洞型储层的控制

基于露头、岩心、测井、录井、三维地震、地球化学实验和生产测试等资料,利用生产动态分析、流体包裹体测温及碳氧同位素测试等多种方法,系统探讨塔里木盆地的构造和流体作用对超深层断控碳酸盐岩缝洞型储层规模、储层质量及其有效性与连通性的控制机理。研究表明:①走滑断层规模、构造部位与岩石力学层共同控制了缝洞储层的发育规模。断层规模越大,储层规模越大;叠接挤压段的储层规模大于叠接拉分段,纯走滑段的储层规模相对较小;走滑断层的交汇部位、转折部位与端部的储层规模较大;垂向上储层发育的差异性受岩石力学层控制,脆性指数高的岩石力学层更有利于缝洞储层的发育。②多期走滑断层活动及流体改造共同控制了缝洞储层的有效性演化及其非均质性。加里东晚期—海西早期的大气淡水活动期为缝洞储层主要形成期;海西晚期热液活动进一步加剧了有效储集空间分布的非均质性。③走滑断层构造部位和现今地应力控制了缝洞储层连通性。叠接拉分段缝洞储层连通性好于纯走滑段,叠接挤压段较差;与现今地应力方向近平行的走滑断层控制的缝洞储层连通性好。优质缝洞型储层平面上主要分布于走滑断层的叠接拉分段两侧断层交汇区域,叠接挤压段中部区域、纯走滑段交叉部位、转折部位和端部的羽状断层区;剖面上集中于高脆性指数的岩石力学层段。

简牍所见秦及西汉初期的未成年“户人”研究

秦及西汉初期的简牍中出现了一些未成年“户人”,他们均为男性。未成年人成为“户人”的主要影响因素包括性别、尊卑及家庭规模等,年龄不是重要考量因素。未成年男性或担任“户人”,或提前服役,过于繁重的赋役迫使未成年男性作为劳动力的价值得到提升。未成年人“户人”被提前成人化,既体现了国家在行政管理上对个人身份信息的漠视,也说明了皇帝和官僚集团极尽可能压榨人民的剩余劳动。

强度空间非均质性与各向异性特征下边坡稳定性极限平衡滑面应力法

实际工程中,土体强度存在空间非均质性与各向异性特征,忽视这些特性将难以可靠地评估边坡稳定性。为此,对强度空间非均质性与各向异性特征下边坡稳定性开展深入研究。首先,改进现有空间非均质性模型和原始Casagrande各向异性模型,拓展其通用性与实用性。其次,对土体强度空间非均质性与各向异性进行耦合,并将其嵌入至拉剪改进模式下Mohr-Coulomb(简称M-C)强度准则当中。然后,在极限平衡理论的框架内,采用滑面应力计算模式代替传统条间力假设模式,并通过构建滑面应力函数以及引入滑面局部安全系数概念和滑面端部应力约束条件,实现边坡拉-剪与压-剪共同作用机制和边坡渐进破坏方式的融入。最后,基于滑体所满足的整体力学平衡条件,建立强度空间非均质性与各向异性特征下边坡稳定性极限平衡严格解答。经后续算例对比分析,提出的方法的可行性与有效性得以验证。此外,研究成果将可用于全面揭示强度空间非均质性与各向异性特征下边坡破坏机制。

粗集料形态对沥青路面抗滑性能影响研究

为进一步明确粗集料形态特征与沥青路面抗滑性能的关系,基于AIMS II设备获取了3种岩性4种整形程度粗集料的梯度棱角、纹理指标、球度、形态综合指标等形态指标,采用摆式摩擦仪和激光扫描仪获取沥青混合料表层的B PN20、平均构造深度M TD、形态参数、分形维数指标等抗滑性能评价指标,通过Pearson相关系数法建立粗集料形态指标与沥青混合料表层抗滑性能评价指标的关系。结果表明:混合粗集料加权期望梯度棱角值与路面B PN20值有较大相关度,相关系数达到0.9以上,建议在施工前提高粗集料的梯度棱角值,以确保沥青路面具有可靠的抗滑性能。研究成果有利于进一步改善沥青路面的抗滑性能。