Maria Mytiliniou  Joeri A. J. Wondergem  Thomas Schmidt  Doris Heinrich 《Journal of the Royal Society Interface》2022,19(187)

Intracellular transport is pivotal for cell growth and survival. Malfunctions in this process have been associated with devastating neurodegenerative diseases, highlighting the need for a deeper understanding of the mechanisms involved. Here, we use an experimental methodology that leads neurites of differentiated PC12 cells into either one of two configurations: a one-dimensional configuration, where the neurites align along lines, or a two-dimensional configuration, where the neurites adopt a random orientation and shape on a flat substrate. We subsequently monitored the motion of functional organelles, the lysosomes, inside the neurites. Implementing a time-resolved analysis of the mean-squared displacement, we quantitatively characterized distinct motion modes of the lysosomes. Our results indicate that neurite alignment gives rise to faster diffusive and super-diffusive lysosomal motion than the situation in which the neurites are randomly oriented. After inducing lysosome swelling through an osmotic challenge by sucrose, we confirmed the predicted slowdown in diffusive mobility. Surprisingly, we found that the swelling-induced mobility change affected each of the (sub-/super-)diffusive motion modes differently and depended on the alignment configuration of the neurites. Our findings imply that intracellular transport is significantly and robustly dependent on cell morphology, which might in part be controlled by the extracellular matrix.  相似文献   

    

Liu Chao  Huang Yuhao  Lu Yuanchun 《Structural Concrete》2019,20(6):1871-1882

An experiment on high‐strain hardening ultra‐high‐performance concrete (UHPC) stitching joints was conducted based on the bridge‐stitching project of Jiyang viaduct, Shanghai. In this experiment, asymmetrical loading was used to simulate the bridge differential settlement caused by soil settlement. The experimental results showed that the entire process could be divided into three stages: elastic stage, cracks developing stage, and failure stage. During these stages, cracks appeared at the bottom of the UHPC slab. Then, many microcracks appeared at the side of the UHPC slab. These microcracks appeared in the form of microcrack clusters, and the width of these cracks increased slowly. It indicated that UHPC had good crack‐control ability. Finally, the main crack appeared at the bottom of the UHPC slab, and the transverse reinforcements yielded. It indicated that the reinforcement layout met the requirements of the failure mode of the specimen. For further analysis, the finite‐element model (FEM) was established. And the results showed that the bending resistance of the joints could be effectively enhanced by increasing the free length of the joint or reducing the thickness of the joint. Based on this experiment and analysis, a nonconnected joint form between slabs and girders was put forward. And the detailed reinforcement scheme of this nonconnected joint form was given. This reinforcement scheme could serve as a reference for similar projects.  相似文献   

    

Yoshiyuki Ishikawa  Ryota Maseki  Sho Aono  Yuichi Kimura  Nobuyuki Yamato 《JAPAN ARCHITECTURAL REVIEW》2019,2(3):259-268

This paper presents an analytical study of a multistage pendulum tuned mass damper (TMD) with a long stroke. Installing TMD is a practical way of adding damping to existing high‐rise buildings against the possible long‐period and long‐duration earthquakes, because both the TMD and amount of reinforcement to the building have low weights. To verify the effectiveness of the TMD, it is necessary to evaluate the effect of the small rotational and uplifting motions when the weight vibrates with a large amplitude. To evaluate these effects, an analytical model that includes the geometric nonlinearity and uplifting motion of the multistage pendulum TMD is presented. The model is verified by a comparison of the simulation results with experimental results of a shaking table test for a multistage pendulum. The time history analysis of the multistage pendulum, modeled as an 18 degrees of freedom system installed on top of a high‐rise building, is conducted. The rolling, torsional, and uplifting motions did not significantly affect the stable transverse motion of the TMD.  相似文献   

    

Olumuyiwa Otegbeye  Sandile S. Motsa  Md. Sharifuddin Ansari 《亚洲传热研究》2019,48(4):1413-1439

Mixed convection flow of a nanofluid near a vertical cone embedded in a a porous medium with Soret and Dufour effects is exercised. The bearing of a porous medium is recounted by the Darcy model. The partial differential equations, modeling the concerned problem, is nondimensionalised by implementing compatible transformations, which results in a similar form. A new paired spectral quasilinearization method is adopted to get the accurate numerical solution. Convergence and accuracy of the solution is elaborated by analyzing the norm of residual and solution errors. Alteration of velocity, temperature, nanoparticle and solute concentration profiles due to flow controlling parameters, namely, Brownian motion, thermophoresis, Soret, Dufour, Lewis number, and buoyancy ratio is outlined by reproducing the obtained numerical solution in graphs and tables. Analysis reveals that the flow profiles are greatly influenced by the physical parameters under investigation.  相似文献   

    

《Advanced Electronic Materials》2018,4(4)

Highly sensitive flexible tactile sensors that can be fabricated in a low cost and efficient way are in great demand for intelligent soft robotics and friendly human–machine interaction. Herein, a highly sensitive flexible tactile sensor is developed by using bionic micropatterned polydimethylsiloxane (m‐PDMS) replicated from lotus leaf. The m‐PDMS substrate consists of high‐aspect‐ratio and low‐density microtowers, and is covered by ultrathin silver nanowires as a bottom electrode. The capacitive sensing device is constructed by sandwiching the bottom electrode, a colorless polyimides dielectric layer, and a top electrode, and exhibits a high sensitivity of ≈1.2 k Pa⁻¹, a ultralow limit of detection <0.8 Pa, and a fast response time of 36 ms. The finite‐elemental analysis indicates that the sparse and high‐aspect‐ratio microtowers are critical to achieve high sensitivity, low limit of detection, and fast response to external stimulus. The flexible tactile sensor also exhibits high robustness: it can be tested for at least 100 000 cycles without showing fatigue. More importantly, the flexible tactile sensors are potentially useful in intelligent soft robots, health monitoring, and motion detection. Besides, the fabrication strategy may offer a guideline to design other microstructures for improving the performance of flexible tactile sensors.  相似文献   

    

Seung Jae Kim  Onnuri Kim  Moon Jeong Park 《Advanced materials (Deerfield Beach, Fla.)》2018,30(12)

Natural double‐layered structures observed in living organisms are known to exhibit asymmetric volume changes with environmental triggers. Typical examples are natural roots of plants, which show unique self‐organized bending behavior in response to environmental stimuli. Herein, light‐ and electro‐active polymer (LEAP) based actuators with a double‐layered structure are reported. The LEAP actuators exhibit an improvement of 250% in displacement and hold an object three times heavier as compared to that in the case of conventional electro‐active polymer actuators. Most interestingly, the bending motion of the LEAP actuators can be effectively locked for a few tens of minutes even in the absence of a power supply. Further, the self‐locking LEAP actuators show a large and reversible bending strain of more than 2.0% and require only 6.2 mW h cm^?2 of energy to hold an object for 15 min at an operating voltage of 3 V. These novel self‐locking soft actuators should find wide applicability in artificial muscles, biomedical microdevices, and various innovative soft robot technologies.  相似文献   

    

Xudong Li  Jianyong Yao  Changsheng Zhou 《International Journal of Adaptive Control and Signal Processing》2017,31(11):1544-1566

Most previous advanced motion control of hydraulic actuators used full‐state feedback control techniques. However, in many cases, only position feedback is available, and thus, there are imperious demands for output‐feedback control for hydraulic systems. This paper firstly transforms a hydraulic model into an output feedback–dependent form. Thus, the K‐filter can be employed, which provides exponentially convergent estimates of the unmeasured states. Furthermore, this observer has an extended filter structure so that online parameter adaptation can be utilized. In addition, it is a well‐known fact that any realistic model of a hydraulic system suffers from significant extent of uncertain nonlinearities and parametric uncertainties. This paper constructs an adaptive robust controller with backstepping techniques, which is able to take into account not only the effect of parameter variations coming from various hydraulic parameters but also the effect of hard‐to‐model nonlinearities such as uncompensated friction forces, modeling errors, and external disturbances. Moreover, estimation errors that come from initial state estimates and uncompensated disturbances are dealt with via certain robust feedback at each step of the adaptive robust backstepping design. After that, a detailed stability analysis for the output‐feedback closed‐loop system is scrupulously checked, which shows that all states are bounded and that the controller achieves a guaranteed transient performance and final tracking accuracy in general and asymptotic output tracking in the presence of parametric uncertainties only. Extensive experimental results are obtained for a hydraulic actuator system and verify the high‐performance nature of the proposed output‐feedback control strategy.  相似文献   

    

《IEEJ Transactions on Electrical and Electronic Engineering》2017,12(2):228-243

Reliable estimation of the vehicle position is the main prerequisite in all autonomous mobile robotic applications. Image‐scale uncertainty in correlation‐based monocular visual odometry systems negatively affects the accuracy of the vehicle motion estimation. This paper presents the development of a new technique and algorithm to estimate image‐scale variations due to camera height fluctuations when the vehicle is driven on uneven terrains or when the height of vehicle from ground changes as a result of changes in load or number of passengers in the vehicle. This technique depends on marking the image frames by two red laser points, as independent reference points, which have a certain distance between them. The image‐scale variations can be estimated by monitoring the variations in the distance between these two reference points. The proposed technique eliminates the need for camera recalibration and the use of sensors to measure the variations of camera height from ground, such as laser range finders and acceleration sensors. The developed system uses a single downward‐facing monocular camera supported by a lighting module and installed underneath the test vehicle to avoid the negative effect of directional sunlight and shadows, which can disturb the correlation. Indoor and outdoor experiments have proven the efficiency of the suggested technique in resolving image‐scale uncertainty and ensuring an image‐scale‐invariant correlation‐based matching, with only less than 5% additional computational time. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.  相似文献   

    

《IEEJ Transactions on Electrical and Electronic Engineering》2017,12(6):803-808

Real haptics has been an unsolved problem since its beginning in the 1940s. After much R&D, including the early works in the United States and other countries, bilateral control designed in the acceleration space is a solution for this issue. The quality of touch and tactile sensation is heavily dependent on the transparency between the master side and the slave side. Robust motion control, which is equivalent to acceleration control, gives high transparency. Real haptics is now a key concept in 21st century where the quality of life should be the basis of our society. Various examples are also given. © 2017 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.  相似文献   

    

Annabel Prause 《Sequential Analysis》2017,36(2):151-178

We study detection methods for multivariable signals under dependent noise. The main focus is on three-dimensional signals; that is, on signals in the space–time domain. Examples for such signals are multifaceted. They include geographic and climatic data as well as image data that are observed over a fixed time horizon. We assume that the signal is observed as a finite block of noisy samples whereby we are interested in detecting changes from a given reference signal. Our detector statistic is based on a sequential partial sum process, related to classical signal decomposition and reconstruction approaches applied to the sampled signal. We show that this detector process converges weakly under the no change null hypothesis that the signal coincides with the reference signal, provided that the spatial–temporal partial sum process associated with the random field of the noise terms disturbing the sampled signal converges to a Brownian motion. More generally, we also establish the limiting distribution under a wide class of local alternatives that allows for smooth as well as discontinuous changes. Our results also cover extensions to the case in which the reference signal is unknown. We conclude with an extensive simulation study of the detection algorithm.  相似文献