Towards magnetically actuated 3D-printed micro-optical elements

Automatic evaluation of sports motion: A generic computation of spatial and temporal errors

The analysis on the forced vibration of a system with elastically supported viscous damper whose damping is accompanied by the Coulomb friction is a very complicated one, for the reason that its every cycle is composed of two different kinds of motions and that seven boundary conditions are needed to solve it. In this paper, the author presents certain characters of the vibration of a system with optimum damping and Coulomb friction, the calculation of which is carried out by a digital computer. It became clear from the results of the analysis and the experiments that, while the Coulomb friction is smaller than the disturbing force, the amplitude seems to grow larger continuously from infinite damping curve to the optimum damping one as the frequency increases, but in the case where the friction overcomes the disturbing force, a jumping phenomenon of the amplitude occurs at a fixed place corresponding to the amount of friction.

Photophoresis—Light induced motion of particles suspended in gas

Human concepts can be roughly divided into entities (prototypically referred to in language by nouns) and events (prototypically referred to in language by verbs). While much work in cognitive neuroscience has investigated how the brain represents different categories of entities, less attention has been given to the more basic distinction between entities and events. We used functional magnetic resonance imaging to examine brain activity while subjects performed a conceptual matching task that required them to access knowledge of objects and actions, using either pictures or words. Since action events involve movement through space, we hypothesized that accessing knowledge of actions would cause greater activation in brain regions involved in motion or spatial processing. In comparison to objects, accessing knowledge of actions through pictures was accompanied by increased activity bilaterally in the human MT/MST and nearby regions of the lateral temporal cortex. Accessing knowledge of actions through words activated areas just anterior and dorsal to area MT/MST on the left, within the posterior aspect of the middle and superior temporal gyri. We propose that the lateral occipital-temporal cortex contains a mosaic of neural regions that processes different kinds of motion, ranging from the perception of objects moving in the world to the conception of movement implied in action verbs. The lateral occipital-temporal cortex mediates the perceptual and conceptual features of action events, similar to the way that the ventral occipital-temporal cortex processes the perceptual and conceptual features of entities.

Non-monotonous actuation, that is, different kinds of motion in response to a single stimulus, is observed in some natural materials but difficult to implement in synthetic systems. Herein, polymer hydrogel sheets made from polyacrylamide (PAAm) or poly(dimethylacrylamide) (PDMAA) with a cross-linking gradient along the sheet thickness are reported. These are obtained by thermally initiated free radical polymerization using a specially designed Teflon mold with a glass lid. The resulting PAAm hydrogels undergo non-monotonous actuation (rolling into a tube and re-opening) when exposed to aqueous media as a single external stimulus. Their actuation kinetics is tuned with anions that have specific ion effects in their interaction with the surrounding solvent and the polymer itself: structure-breaking chloride enhances the hydration of the polymer backbone, structure-making sulfate decreases it, and is thus slowing down the actuation kinetics of the PAAm hydrogels. The PDMAA gel rolls up instantaneously in aqueous NaCl and only re-opens after 24h. PDMAA actuation in aqueous Na2 SO4 is only moderate as the gel didnot swell in that solvent. Bilayer hydrogels made from PAAm and PDMAA (without gradient) show monotonic actuation, closing in NaCl solution and re-opening in Na2 SO4 .

A large number of CCD images of the SL9 impact clouds in the visible from July to October 1994 has allowed us to study the morphological changes and motions of the impact clouds. Our measurements show the existence of at least three different kind of motions: (1) Eastward expansion during the first two days of the largest impact regions (K, L, G) with velocities in the range from 36 to 60 m/s; (2) Clouds that act probably as passive tracers of the stratospheric flow (velocities in the range −15 to 20 m/s); (3) Local motions of the cloud elements with meridional components, sometimes related to the interaction with anticyclonic ovals in nearby latitudes (velocities ∼ 20 m/s). The average zonal velocity relative to System III of the cores of impacts E, A, C, W, K, L, G, R, Q1 and H was (up to 18 August) u = −1.7±1.0 m/s with an average jovicentric latitude of −43.8°±0.4°.

Spatio-temporal decomposition of 2D travelling waves from video measurements

Slow relaxations in salicylsalicylic acid studied by dielectric techniques

We propose a non-linear generative model for human motion data that uses an undirected model with binary latent variables and real-valued variables that represent joint angles. The latent and visible variables at each time step receive directed connections from the visible variables at the last few time-steps. Such an architecture makes on-line inference efficient and allows us to use a simple approximate learning procedure. After training, the model finds a single set of parameters that simultaneously capture several different kinds of motion. We demonstrate the power of our approach by synthesizing various motion sequences and by performing on-line filling in of data lost during motion capture.

Underwater experiments are usually very expensive and hard to perform. It is really essential to develop such experimental bench especially in Bangladesh which is crisscrossed by water. This paper presents design and construction of a low-cost Hybrid Remotely Operated Vehicle (HROV) for underwater surveillance. This HROV uses modern technology for its proper functioning. The principles of the structure design of the HROV are kept the device considerably affected by the characteristics parameter in water such as mass, buoyancy, hydrodynamic forces etc. For maneuvering of the HROV, uses Brushless Direct Current (BLDC) motor with suitable propeller placed in vectored configuration in order to produce different kinds of motion. Navigation system uses a full High Definition (HD) camera, Nine Degree of Freedom (9DOF) and a depth and pressure sensor. The orientation of the HROV determined using Direction Cosine Matrix (DCM) algorithm from the high-rate inertial measurement unit (IMU) consist of accelerometer, gyros, and magnetometer. This information is presented on a screen with the control unit. There provide some additional devices for the safety of the device to overcome any unwanted consequences.

This paper describes a novel approach for human motion recognition via motion feature vectors collected from a micro Inertial Measurement Unit (μlMU), which measures angular rates and accelerations of the three different directions in the workspace based on MEMS sensors. The recognizer is composed of three parts. The first part is a preprocessor, in which Vector Quantization is used to reduce dimensions of vectors. Recognition is implemented by the second part, which is a classifier composed of Hidden Markov Model and an efficient second layer criterion. The third part uses a sliding window algorithm for precise recognition. There were 200 sequences (about 100,000 vectors) for 10 different kinds of motions tested in our work, including falling-down motion and other typical human motions. Experimental results show that for the given 10 different categories, correct recognition rates range from 95 %-100 %, of which the falling-down motion can be classified from others with a 100 % recognition rate.

Experimental investigation the effect of nanoparticle concentration on the rheological behavior of paraffin-based nickel ferrofluid

Magnetic actuation of microscopic devices in a liquid environment has been achieved in various ways, which can be grouped into rolling, propelling and swimming. Previous actuators were designed with a focus on one particular type of magnetic actuation. We have shown earlier that efficient magnetic propellers can be selected from randomly shaped magnetic nanostructures synthesized in solution. Here we show that these synthesized nanostructures can be used for all three types of magnetic actuation. Whereas it might not be surprising that single structures can roll in addition to propelling, swimming is unexpectedly also observed using the same material. In this case, however, the magnetically guided self-assembly of several individual particles into chain-like structures is necessary to obtain swimmers, since individual rigid nanostructures cannot swim. Interestingly, the direction of the swimming motion is not necessarily parallel to the long axis of the chain-like assembly, a finding that had been theoretically expected but experimentally not observed so far. Our findings show that the range of structures that can be effectively actuated by external magnetic fields is much broader than assumed until now. This could open up new opportunities for the design of magnetically actuated devices.

Biological cilia exhibit metachronal movements that enable the expulsion of substances such as mucus and bacterial cells. Inspired by biological cilia, significant progress has been made in recent years in the development of artificial cilia. In particular, magnetic actuation has emerged as a prominent strategy for real-time, remote-controlled manipulation, offering noninvasive and reversible operation without inducing irreversible damage. However, the fabrication of artificial microcilia is currently constrained by limitations in achieving high aspect ratios, cost-effectiveness, and scalable production. In this study, advanced laser manufacturing is used to drill porous silicon (Si) templates, successfully demolding microcilia with a high aspect ratio (exceeding 9). By integrating silicon dioxide (SiO2) nanoparticles, a superhydrophobic surface is achieved with a hierarchical micro-nano structure. The experiments demonstrated that these structured microcilia not only exhibit remarkable durability but also maintain long-term superhydrophobicity. Furthermore, by blending with magnetic iron (II, III) oxide (Fe3O4) nanoparticles, superhydrophobic magnetic microcilia arrays (SMMA) are developed, enabling droplet transportation on their surface controlled by an external magnetic field. These artificial microcilia have potential applications in biomedical devices, self-cleaning anti-fouling surfaces, and human sensingtechnologies.

We made magnetostrietive actuators and electromagnetic actuators by using various kinds of magnetic thin film. The magnetostrictive actuators were bimorph cantilever actuators and a traveling machine, composed of magnetostrictive amorphous Tb-Fe and Sm-Fe thin films on a polyirmide substrate. The 3-mm-long cantilever actuator using a 3-μm-thick substrate exhibited large deflection above 100μm in magnetic fields as low as 24 kA/m, and above 500 μm at a resonant frequency of 29 Hz in an alternating magnetic field of 24 kA/m. The electromagnetic actuators are driven by magnetic torque, which made “flying” actuation possible. These magnetic actuators need no power supply cables, because they are driven by an external magnetic field.