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High-speed jets (HSJs) occur frequently in Earth’s magnetosheath downstream of the quasi-parallel bow shock. They have great impacts on the magnetosheath and the magnetosphere. Using a two-dimensional global hybrid simulation, we investigate the formation and evolution of the HSJs with an IMF cone angle of 0°. The quasi-parallel shock is near the subsolar point, and the HSJs begin to appear in the quasi-parallel magnetosheath with a parallel (perpendicular) scale size of about 1RE (0.2RE). These HSJs then converge, leading to the formation of a large-scale HSJ with a parallel (perpendicular) scale size of 6RE (1.2RE). Some long HSJs, with a large parallel but small perpendicular scale size, are formed at the quasi-parallel bow shock and extend toward the quasi-perpendicular magnetosheath along with the background magnetosheath flow. Moreover, these long HSJs can cause filamentary structures in the magnetosheath.

Collecting in shallow water (water depth: ~30 m) is an emerging field that requires robotics for replacing human divers. Soft robots have several promising features (e.g., safe interaction with the environments, lightweight, etc.) for performing such tasks. In this article, we developed an underwater robotic system with a three-degree-of-freedom (3-DoF) soft manipulator for spatial delicate grasping in shallow water. First, we present the design and fabrication of the soft manipulator with an opposite-bending-and-stretching structure (OBSS). Then, we proposed a simple and efficient kinematics method for controlling the spatial location and trajectory of the soft manipulator’s end effector. The inverse kinematics of the OBSS manipulator can be solved efficiently (computation time: 8.2 ms). According to this inverse kinematics method, we demonstrated that the OBSS soft manipulator could track complex two-dimensional and three-dimensional trajectories, including star, helix, etc. Further, we performed real-time closed-loop pick-and-place experiments of the manipulator with binocular and on-hand cameras in a lab aquarium. Hydrodynamic experiments showed that the OBSS soft manipulator produced little force (less than 0.459 N) and torque (less than 0.228 N·m), which suggested its low-inertia feature during the underwater operation. Finally, we demonstrated that the underwater robotic system with the OBSS soft manipulator successfully collected seafood animals at the bottom of the natural oceanic environment. The robot successfully collected eight sea echini and one sea cucumber within 20 minutes at a water depth of around 10 m.

Surface treatment is known as a very efficient measure by which to modulate the surface properties of biomaterials in terms of grain structure, topography, roughness and chemistry to determine the osseointegration of implants. In this work, a two-step method of surface modification was employed to impart high osteogenic activity and biomineralization capacity on a Ti-25Nb-3Mo-2Sn-3Zr alloy (a type of β-titanium named TLM). The preliminary surface mechanical attrition treatment (SMAT) refined the average grain size from 170 ± 19 μm to 74 ± 8 nm in the TLM surface layer and promoted the surface to be much rougher and more hydrophilic. The subsequent Ca-ion implantation did not change the surface roughness and topography obviously, but enhanced the surface wettability of the SMAT-treated TLM alloy. The

Supplemental material, IJRR_Supplementary_text_1 for A soft manipulator for efficient delicate grasping in shallow water: Modeling, control, and real-world experiments by Zheyuan Gong, Xi Fang, Xingyu Chen, Jiahui Cheng, Zhexin Xie, Jiaqi Liu, Bohan Chen, Hui Yang, Shihan Kong, Yufei Hao, Tianmiao Wang, Junzhi Yu and Li Wen in The International Journal of Robotics Research

Background and objective: Proviral insertion site in Moloney murine leukemia virus (PIM)2 functions as a serine/threonine kinase to participate in regulating cell proliferation and cell cycle. PIM2 has been shown to be elevated in the lung cancer cell lines. This study was performed to investigate the role of PIM2 in lung adenocarcinoma cell growth. Mateial and methods: Expression level of PIM2 in lung adenocarcinoma tissues and cells was detected by qRT-PCR (quantitative Reverse Transcription PCR) and western blot. The over-expression and knockdown of PIM2 were separately established by employing pcDNA and siRNA to explore the effects on the cell viability, apoptosis, invasion and migration. The downstream pathways were evaluated by western blot assay. Results: Lung adenocarcinoma tissues and cells showed an elevation of both PIM2 mRNA and protein expression. Knocking down PIM2 decreased the cell viability and promoted the apoptosis, which can be reversed by pcDNA-mediated over-expression of PIM2. PIM2 silencing suppressed the promotional effect of over-expression of PIM2 on cell invasion and migration through increasing IκBα expression and decreasing the X-linked inhibitor of apoptosis protein (XIAP), p65 and IκBα phosphorylation. While, over-expression of PIM2 showed opposite effect on IκBα and XIAP expression or p65 and IκBα phosphorylation. Conclusion: PIM2 can not only suppress lung adenocarcinoma cell apoptosis but also promote cell migration and invasion depending on XIAP/NF-κB signaling pathway.

Currents are believed to exist in mirror mode structures and to be self-consistent with the magnetic field depression. Here, we investigate a train of mirror mode structures in the terrestrial plasma sheet on 11 August 2017 measured by the Magnetospheric Multiscale mission. We find that bipolar current densities exist in the cross-section of two hole-like mirror mode structures, referred to as magnetic dips. The bipolar current in the magnetic dip with a size of ~2.2 ρi (the ion gyro radius) is mainly contributed by variations of the electron velocity, which is mainly formed by the magnetic gradient-curvature drift. For another magnetic dip with a size of ~6.6 ρi, the bipolar current is mainly caused by an ion bipolar velocity, which can be explained by the collective behaviors of the ion drift motions. These observations suggest that the electrons and ions play different roles in the formation of currents in magnetic dips with different sizes.

Adaptive soft-matter machines are developed using the complex multiphase organohydrogels with multistable mechanical states., Many biological organisms can tune their mechanical properties to adapt to environments in multistable modes, but the current synthetic materials, with bistable states, have a limited ability to alter mechanical stiffness. Here, we constructed programmable organohydrogels with multistable mechanical states by an on-demand modular assembly of noneutectic phase transition components inside microrganogel inclusions. The resultant multiphase organohydrogel exhibits precisely controllable thermo-induced stepwise switching (i.e., triple, quadruple, and quintuple switching) mechanics and a self-healing property. The organohydrogel was introduced into the design of soft-matter machines, yielding a soft gripper with adaptive grasping through stiffness matching with various objects under pneumatic-thermal hybrid actuation. Meanwhile, a programmable adhesion of octopus-inspired robotic tentacles on a wide range of surface morphologies was realized. These results demonstrated the applicability of these organohydrogels in lifelike soft robotics in unconstructed and human body environments.

This article presented a four-fingered soft bionic robotic gripper with variable effective actuator lengths. By combining approaches of finite element analysis, quasi-static analytical modeling, and experimental measurements, the deformation of the single soft actuator as a function of air pressure input in free space was analyzed. To investigate the effect of the effective actuator length on the gripping performance of the gripper, we conducted systematical experiments to evaluate the pull-off force, the actuation speed, the precision and error tolerance of the soft gripper while grasping objects of various sizes and shapes. A combination of depressurization and pressurization in actuation as well as applying variable effective actuator length enhanced the gripper’s performance significantly, with no sensors. For example, with tunable effective actuator length, the gripper was able to grasp objects ranging from 2 mm – 170 mm robustly. Under the optimal length, the gripper could generate the maximum pull-off force for the corresponding object size; the precision and the error tolerance of the gripper were also significantly improved compared to those of the gripper with full-length. Our soft robotic prototype exhibits a simple control and low-cost approach of gripping a wide range of objects and may have wide leverage for future industrial operations.

One-dimensional (1-D) hybrid simulations have demonstrated that a quasi-parallel shock is non-stationary and undergoes a reformation process. Recently, two-dimensional (2-D) hybrid simulations have revealed that ripples along the shock front is an inherent property of a quasi-parallel shock. In this paper, we investigate reformation process of a rippled quasi-parallel shock with a 2-D hybrid simulation model. The simulation results show that at a rippled shock, incident particles behave differently and just can be partially reflected at some specific locations along the rippled shock front, and the reflected particles will form an ion beam that moves back to the upstream along the magnetic field. Then, the beam locally interacts with upstream waves, and the waves are enhanced and finally steepen into a new shock front. As the upstream incident plasma moves to the shock front, the new shock front will approach and merge with the old shock front. Such a process occurs only before these locations along the shock front, and after the merging of the new shock front and old shock front is finished, a relatively plane shock front is formed. Subsequently, a new rippled shock front is again generated due to its interaction with the upstream waves, and it will repeat the previous process. In this pattern, the shock reforms itself quasi-periodically, at the same time, ripples can shift along the shock front. The simulations present a more complete view of reformation for quasi-parallel shocks.

Currents are believed to exist in mirror mode structures and to be self-consistent with the magnetic field depression. Here, we investigate a train of mirror mode structures in the terrestrial plasma sheet on 11 August 2017 measured by the Magnetospheric Multiscale mission data. We find that a bipolar current exists in the cross-section of two hole-like mirror mode structures, referred to as magnetic dips. The bipolar current in the magnetic dip with a size of ~ 3 ρi (the ion gyro radius) is mainly contributed by an electron bipolar velocity, which is mainly formed by the magnetic gradient-curvature drift. For another magnetic dip with a size of ~ 6.67 ρi, the bipolar current is mainly caused by an ion bipolar velocity, which can be explained by the ion diamagnetic drift. These observations suggest that the electrons and ions play different roles in the formation of currents in magnetic dips with different sizes.

Conventional rigid electronic systems use a number of metallization layers to route all necessary connections to and from isolated surface mount devices using well-established printed circuit board technology. In contrast, present solutions to prepare stretchable electronic systems are typically confined to a single stretchable metallization layer. Crossovers and vertical interconnect accesses remain challenging; consequently, no reliable stretchable printed circuit board (SPCB) method has established. This article reports an industry compatible SPCB manufacturing method that enables multilayer crossovers and vertical interconnect accesses to interconnect isolated devices within an elastomeric matrix. As a demonstration, a stretchable (260%) active matrix with integrated electronic and optoelectronic surface mount devices is shown that can deform reversibly into various 3D shapes including hemispherical, conical or pyramid., To realize multilayer stretchable printed circuit boards (SPCBs), advancements in industrially-viable materials and processing methods are required. Here, the authors report multilayer SPCBs with electrical wiring capable of interconnecting isolated devices in different layers within an elastomeric matrix.

In this paper, we propose a soft actuator embedded with conductive liquid alloy (eGaIn) and Shape Memory Polymer (SMP). The conductive liquid alloy functions as bending sensor as well as pressure sensor. The three segments of the SMP layer can be heated optionally by applying 400mA current to different sections of the conductive silver fiber to achieve tunable stiffness, and enable the soft actuator with variable degree-of-freedom (DoF) configurations. Through real-time feedback of the bending sensor that has been calibrated, we realized proprioception of all mechanical configurations of the soft actuator under free load. We also achieved geometrical feature recognition of different objects while all segments of the actuator were softened. Finally, experimental verification of the prototype was conducted on a variety of objects in condition that the geometrical features were unknown. The results show improved enveloping and reliable grasping performance.

Experimental observations from space missions (including more recently CLUSTER and THEMIS data) have clearly revealed the existence of high speed jets (HSJs) in the downstream region of the quasi-parallel terrestrial bow shock. Presently, two-dimensional (2-D) hybrid simulations are performed in order to investigate the formation of such HSJs through a rippled quasi-parallel shock front. The simulation results show that (i) such shock fronts are strongly nonstationary along the shock normal, and (ii) ripples are evidenced along the shock front as the upstream ULF waves (excited by interaction between incident and reflected ions) are convected back to the front by the solar wind and contribute to the rippling formation. Then, these ripples are inherent structures of a quasi-parallel shock. As a consequence, new incident solar wind ions interact differently at different locations along the shock surface, and the ion bulk velocity strongly differs locally as ions are transmitted downstream. Preliminary results show that (i) local bursty patterns of turbulent magnetic field may form within the rippled front and play the role of local secondary shock, (ii) some incident ion flows penetrate the front, suffer some deflection (instead of being decelerated) at the locations of these secondary shocks, and are at the origin of well structured (filamentary) HSJs downstream, and (iii) the spatial scales of HSJs are in a good agreement with experimental observations. Such downstream HSJs are shown to be generated by local curvature effects (front rippling) and the nonstationarity of the shock front itself.

Soft grippers based on fluidic elastomer actuators have the characteristics of gentle and adaptable grasping that is difficult to realize by rigid grippers. However, it remains challenging to implement a compact gripping device that has multiple bending configurations to exert appropriate force, and sensory capabilities to evaluate the grasping state. Here, we present a soft gripper with variable effective lengths (VELs) that is achieved by rapidly softening selective shape memory polymer sections (within 0.6 s) via a flexible heater. A vortex tube is used to jet cold airflow to accelerate the stiffening process (within 14 s). We show that the soft gripper can not only identify objects but also exert higher gripping force by setting appropriate length according to pneumatic-thermal hybrid actuation. We further propose a touch-reconfiguration-grasp strategy to showcase the synergy of VELs and sensory feedback. The gripper first touches the object under the fully softened state and evaluates the grasping condition based on the sensors’ feedback, then reconfigures the bending length and grasps the object until successful. We envision that soft grippers with sensing ability and reconfigurable grasping configurations would be promising for future applications in unconstructed environments.

This paper presents a soft actuator embedded with conductive liquid metal and shape memory epoxy (SME) which function together to enable self-sensing, tunable mechanical degrees of freedom (DoF), and variable stiffness. We embedded thermoplastic shape memory epoxy in the bottom portion of the actuator. Different sections of the SME could be selectively softened by an implanted conductive silver yarn located at different positions. When an electric current passes through the conductive silver yarn, it induces a phase transition that changes the epoxy from stiff state to compliant state. Each section of SME could be softened within 5 s by applying a current of 200 mA to the silver yarn. To acquire the strain curvature, eGaIn was infused into a microchannel surrounding the chambers of the soft actuator. A spiral-shaped eGaIn sensor was also attached to the tip of the actuator to perceive the contact with reliable dynamic force response. Systematic experiments were performed to characterize the stiffness, tunable DoF, and sensing property. We show the ability of the soft composite actuator to support a weight of 200g at the tip (as a cantilever) while maintaining the shape and the ability to recover its original shape after large bending deformation. In particular, seven different motion patterns could be achieved under the same pneumatic pressure of the actuator due to selectively heating the SME sections. A gripper which was fabricated by assembling two actuators to a base was able to grasp the weight up to 56 times of a single actuator through an appropriate motion pattern. For demonstration purposes, the gripper was used to grasp various objects by adjusting the DoF and stiffness with real-time feedback of the bending strain and the contact force.

In this paper, with two-dimensional (2-D) hybrid simulations, we study the generation mechanism of filamentary structures downstream of a quasi-parallel shock. The results show that in the downstream both the amplitude of magnetic field and number density exhibit obvious filamentary structures, and the magnetic field and number density are anticorrelated. Detailed analysis find that these downstream compressive waves propagate almost perpendicular to the magnetic field, and the dominant wave number is around the inverse of ion kinetic scale. Their parallel and perpendicular components roughly satisfies(where and represent the parallel and in-plane perpendicular components of magnetic field, is the wave number in the perpendicular direction, and in the ion gyroradius), and their Alfven ratio also roughly agree with the analytical relation (where and indicate the Alfven ratio and plasma beta), while the corresponding cross helicity and compressibility show good agreement with previous theoretical calculations. All these properties are consistent with those of kinetic slow waves (KSWs). Therefore, we conclude that the filamentary structures in the downstream of a quasi-parallel shock are produced due to the excitation of KSWs., 29 pages, 10 figures

The free energy provided by the ion temperature anisotropy is considered to be the source of ion cyclotron waves in the downstream of a quasi-perpendicular shock. Besides the proton cyclotron waves excited by the proton temperature anisotropy, He2 + is decelerated differentially from the protons by the shock due to its different charge-to-mass ratio and forms a bunched ring-like distribution in the immediate downstream of the quasi-perpendicular shock. However, how the helium cyclotron waves associated with the anisotropic distribution of He2 + are excited is still in debate. In this paper, with two-dimensional (2-D) hybrid simulations, we investigate He2 + dynamics and its role in the ion cyclotron waves downstream of quasi-perpendicular shocks (the proton plasma beta in the upstream is 0.4). A bunched ring-like distribution of He2 + is formed in the immediate downstream of the quasi-perpendicular shocks; then it evolves into a shell-like distribution. At last, a bi-Maxwellian distribution of He2 + is generated in the far downstream. In the medium and low Mach number shocks, besides the proton cyclotron waves excited near the shock front, there is another enhancement of the magnetic fluctuations in the downstream. The results show that the helium cyclotron waves can be driven directly by the bunched ring-like distribution of He2 + in a low or medium Mach number quasi-perpendicular shock. The relevance of our simulation results to the satellite observations is also discussed in this paper.

In this study, we built a four-fingered soft robotic gripper with tunable effective finger lengths. This robotic model is purely made of soft materials and allows two working modes that require very simple control: 1) deflate the soft fingers for bending to one direction therefore to open the gripper “claw” and 2) inflate the fingers with compressed air for bending to the reverse direction, therefore to grip objects reversibly. Systematic tests of the gripping performance of the soft robotic model were conducted for 5 effective finger lengths ranging from 30 mm to 100 mm. Under each effective length, we measured the pull-off force of 8 sphere-shaped objects with diameters from 20 to 90mm, and five typical geometric shaped objects including sphere, cubic and cylinder etc. We also measured the pull-off force of gripping objects with different stiffness. Notably, we found that each object with different size prefer a “sweet” effective finger length for generating maximum pull-off force. We show that tunable effective finger length for the soft robot can significantly improve the performance when gripping multiple objects. Current soft robotic prototype exhibits a simple-control, low-cost approach of grasping objects with different size, weight, and shape as well as material stiffness, and may open up new avenues for future industrial gripping.

In this paper, two-dimensional (2-D) hybrid simulations are performed to investigate ion dynamics at a rippled quasi-parallel shock. The results show that the ripples around the shock front are inherent structures of a quasi-parallel shock, and the reformation of the shock is not synchronous along the surface of the shock front. By following the trajectories of the upstream ions, we find that these ions behave differently when they interact with the shock front at different positions along the shock surface. The upstream particles are easier to transmit through the upper part of a ripple, and the bulk velocity in the corresponding downstream is larger, where a high-speed jet is formed. In the lower part of the ripple, the upstream particles tend to be reflected by the shock. For the reflected ions by the shock, they may suffer multiple stage acceleration when moving along the shock surface, or trapped between the upstream waves and the shock front. At last, these ions may escape to the further upstream or enter the downstream, therefore, the superthermal ions can be found in both the upstream and downstream., 33 pages, 10 figures

Objective. To achieve the automatic and accurate reporting of hospital medical record home page information. Method. Analyzing the requirements of data reporting for the medical record home page, setting a data rules validation engine and developing a docking program for the data reporting of the medical record home page. Result. Owing to the adoption of the data docking program developed based on a hospital data platform, the automatic and accurate reporting of the medical record home page information is realized, the automatic analysis and collection of 84 indexes corresponding to the reported data, the rules engine validation and the display of extracted data are also realized. Conclusion. The medical record home page information reported by the hospital data docking system meets related requirements of the National Health and Family Planning Commission; and furthermore the hospital's medical record quality management level is effectively improved.

Whistler mode waves in the Earth's magnetosphere have already been widely investigated in the linear or quasi-linear regime, but there is still lack of research on nonlinear physical processes. In this paper, with a 2-D PIC simulation model, we have studied the parametric decay of oblique whistler waves for the first time. The parametric decay of an oblique whistler wave first occurs along its propagating direction, which involves a backward daughter whistler wave and a forward ion acoustic mode. This is quite similar to the parametric decay of parallel whistler waves in 1-D simulations. Interestingly, the parametric decay will then take place along the perpendicular direction, which can generate a family of daughter whistler waves along the perpendicular direction with the nearly same parallel wave number. Meanwhile, the highly oblique whistler waves will also be excited during this perpendicular decay, whose wave normal angle can even reach up to the resonant cone angle. Moreover, the parametric decay tends to be stronger for the pump whistler wave with a larger frequency or larger amplitude. But the growth rate of the parametric decay has little change when the wave normal angle of the pump whistler wave varies within a limited range. Interestingly, parallel whistler waves can also experience the similar decay process, which may suggest that the parametric decay of whistler waves should be a multi-dimensional process in nature. During the decay process, the generated ion acoustic waves can accelerate a part of protons through the Landau resonance. Our simulation results not only uncover the evolution pattern of whistler waves during the parametric decay in a two-dimensional regime but also propose a potential nonlinear physical process related to whistler waves in the Earth's magnetosphere.

This paper presents a soft actuator embedded with two types of eutectic alloys which enable sensing, tunable mechanical degrees of freedom (DOF), and variable stiffness properties. To modulate the stiffness of the actuator, we embedded a low melting point alloy (LMPA) in the bottom portion of the soft actuator. Different sections of the LMPA could be selectively melted by the Ni–Cr wires twined underneath. To acquire the curvature information, EGaIn (eutectic gallium indium) was infused into a microchannel surrounding the chambers of the soft actuator. Systematic experiments were performed to characterize the stiffness, tunable DOF, and sensing the bending curvature. We found that the average bending force and elasticity modulus could be increased about 35 and 4000 times, respectively, with the LMPA in a solid state. The entire LMPA could be melted from a solid to a liquid state within 12 s. In particular, up to six different motion patterns could be achieved under each pneumatic pressure of the soft actuator. Furthermore, the kinematics of the actuator under different motion patterns could be obtained by a mathematical model whose input was provided by the EGaIn sensor. For demonstration purposes, a two-fingered gripper was fabricated to grasp various objects by adjusting the DOF and mechanical stiffness.

A decision-feedback equalizer (DFE) for Multi-h CPM in aeronautical telemetry is presented in this paper. This algorithm estimates the inter-symbol interference and cancels it from the samples used to make the bit decisions. The approach improves the bit estimates sequentially, thereby increasing the probability of obtaining accurate estimates. Simulation results show an 1 dB improvement in bit error rate performance than the MMSE-equalizer for Multi-h CPM in a multipath channel environment.

This article presented the optimization parameter of a bidirectional soft actuator and evaluated the properties of the actuator. The systematic simulation was conducted to investigate the effect of the top wedged angle (the angle for the wedged shape of the actuator structure) of the chamber on the bending extent of the actuator when it is deflated. We also investigated the width of the actuator and the material combinations of the two layers with the relation to the deformation performance. A mathematical model was also built to reveal the deformation of the actuator as a function of the geometrical parameters of the inner chambers and the material properties. We quantitatively measured the bending radius and the actuation time of the actuator both in air and under water. Digital particle image velocimetry experiments were conducted under water to observe the flow patterns around the actuator. We found that the top wedged angle has a significant effect on the outward bending of the actuator when it is deflated, and 15° was found to be optimal for bending into a larger gripping space. The result shows that the actuator can deform much easier with a bigger width. Utilizing a soft gripper that was built by mounting four actuators to a three-dimensional-printed rigid support, we found that the prototype can grip objects of different sizes, shapes, and material stiffness in amphibious environments.

The superthermal ions at a quasi-parallel collisionless shock are considered to be generated during the reformation of the shock. Recently, hybrid simulations of a quasi-parallel shock have shown that during the reformation of a quasi-parallel shock the large-amplitude upstream low-frequency waves can trap the reflected ions at the shock front when they try to move upstream, and then these reflected ions can be accelerated several times to become superthermal ions. In this paper, with the Cluster observations of a quasi-parallel shock event, the relevance between the large-amplitude upstream low-frequency waves and the superthermal ions (about several keV) have been studied. The observations clearly show that the differential energy flux of superthermal ions in the upstream region is modulated by the upstream low-frequency waves, and the maxima of the differential energy flux are usually located between the peaks of these waves (including the shock front and the peak of the upstream wave just in front of the shock front). These superthermal ions are considered to originate from the reflected ions at the shock front, and the modulation is caused due to the trapping of the reflected ions between the upstream waves or the upstream waves and the shock front when these reflected ions try to travel upstream. It verifies the results from hybrid simulations, where the upstream waves play an important role in the generation of superthermal ions in a quasi-parallel shock.