LENGTH OF SERIAL ELASTIC ELEMENT AND CONTRACT ELEMENT DURING VERTICAL JUMP: COMPARISON OF STATIC OPTIMIZATION AND DYNAMIC OPTIMIZATION

The purpose of this study was to: (1) compare the length of serial elastic element, contract element estimated by two different optimizations, and (2) examine that whether those methods are able to evaluate the length of serial elastic element, contract element. One healthy male performed a vertical jump with the maximal effort from a squat position. The coordinate data and the ground reaction force were obtained with a 3D motion analysis system (250Hz) and force platform (10WHz). For a dynamic optimization, we developed muscle activation driven forward dynamics simulation model. As a result, the pattern of length of element estimated by the dynamic optimization was similar to the pattern reported by Kurokawa et al. (2001). On the other hand, the pattern of length of element estimated by the static optimization differed from the pattern reported by Kurokawa et al. (2001). This finding might be useful to clear the mechanics of human movements

DYNAMICS OF SUPPORT HIP JOINT DURING MAXIMAL VELOCITY SPRINTING

The purpose of this study was to investigate the relationship between lower trunk motion and the support leg hip joint torque by three-dimensional (3D) analysis. Eight male sprinters ran 60-m with maximal effort from a standing position. Kinematic and kinetic data at the maximal speed phase were obtained with a 3D motion analysis system (250Hz) and force platform (1000Hz). As a result, there was a marginally significant negative correlation (r = -0.70, p = 0.051) between a running velocity and the peak backward angular acceleration of the support-side lower trunk during terminal support phase. It seems to be necessary for diminishing the backward angular acceleration to exert a large support hip adductor torque during the terminal support phase. These findings might be useful to improve maximal running velocity

Effects of Drive System Lubricant Additives upon Rolling Fatigue of Carburized and Hardened Steel Rollers

To clarify the effects of a drive system lubricant additive upon rolling fatigue of rollers manufactured from carburized and hardened steel, three types of oil were used as lubricants: one mineral base oil and the other two mineral base oils to which an S-P additive package and ATF additive package were added, respectively. These specimens were tested for sliding/rolling fatigue and examined for failure on the surface, rolling fatigue strength, and other properties. Roller surface temperatures and inter-roller frictional coefficients were found scarcely affected by the type of oil used. Irrespective of the difference in oil type, failure on the surface was found to be entirely spalling attributable to cracks generated in the subsurface. The depth at which spalling cracks had taken place was found nearly coincident with the depth at which a ratio of reversing orthogonal shear stress to hardness had amplitude A(Tyz/Hv) maximized. These depths were larger as Hertz stress became more prominent. Nevertheless, they were found hardly affected by the type of oil. Although rolling fatigue strength did not show a significant difference dependent upon the type of oil, it may be said that fatigue life would be somewhat negatively affected by an extreme pressure coated film with a content of sulfur and phosphorus

<Note>Observation of Feeding Behavior of Termite Using CCD Camera and Its Relation to the Generation of Acoustic Emission (AE)

この論文は国立情報学研究所の学術雑誌公開支援事業により電子化されました。The feeding behavior of a worker of Coptotermes formosanus Shiraki was observed with CCD camera under AE monitering. Two types of feeding behavior, biting and nibbling using the mandible, were observed. AEs were detected only when the termites bited or nibbled at the wood surface

Estimation of Unsaturated hydraulic parameters by In-situ technique

In-situ determination of fundamental hydraulic parameters like variably saturated hydraulic conductivity (K(FS)) and the matric flux potential (Φ(m)) provides a foundation from which several other unsaturated soil parameters can be estimated, namely the Alpha (α*) parameter. This Alpha parameter is the one of the components of 3D unsaturated flow in vadose zone and its value is the measure of the capillary component of unsaturated flow pattern. Here an in-situ technique, Pressure Infiltrometer is introduced to record the steady flow rate applying a constant positive head on an unsaturated soil surface. The aim of this paper is to check the shape factor of 3D flow geometry and to find out its sensitivity on other unsaturated hydraulic parameters and to find out the influence of Alpha parameters on the results of the in-situ estimation of field-saturated hydraulic conductivity

Impact of feed water pH and membrane material on nanofiltration of perfluorohexanoic acid in aqueous

Nanofiltration was thought to be a good option for the recovery of perfluorohexanoic acid (PFHxA) from industrial wastewater. In this study, two commercially available nanofiltration (NF) membranes (NF 270 and NTR-7450) were tested to concentrate the PFHxA in aqueous solution. Filtration test was conducted in crossflow filtration mode. Membrane flux and PFHxA rejection rate were monitored throughout the filtration test. The impact of initial feed water pH on membrane performance was investigated. Results demonstrated that the two NF membranes showed different response to the change of initial feed water pH, which was caused by the intrinsic properties of membrane material. The flux performance of NF 270 was stable, while its rejection rate of PFHxA was very sensitive to the change of initial feed water pH. Opposite result was obtained with NTR-7450. It had a very good stability on rejection rate, while its flux was very sensitive to the change of initial feed water pH. The mechanisms behind these phenomena were also discussed. The results obtained in this study should be very useful for the process design in practical engineering

Micro-PIXE (Particle Induced X-Ray Emission) Analysis of Aluminum in Rat-Liver Using MeV Heavy Ion Microprobes

Heavy ion microprobes (HIM) such as 3 MeV Si2+ and 3 MeV p2+ have been applied to the elemental analysis by PIXE (proton-induced X-ray emission). It was found that silicon and phosphorus microprobes have several times higher sensitivity for aluminum Kα X-rays than 2 MeV proton microprobes, and detection limits were more favorable in a phosphorus microprobe. Using a 3 MeV p2+ microprobe, the liver of a rat, which had been injected with aluminum-lactate, was investigated and it was found that aluminum segregates in areas with a dimension of about 10 μm. These areas could hardly be observed with 2 MeV proton microprobes

An Exceptionally Difficult Binary Quadratic Optimization Problem with Symmetry: a Challenge for The Largest Unsolved QAP Instance Tai256c

Tai256c is the largest unsolved quadratic assignment problem (QAP) instance in QAPLIB. It is known that QAP tai256c can be converted into a 256 dimensional binary quadratic optimization problem (BQOP) with a single cardinality constraint which requires the sum of the binary variables to be 92. As the BQOP is much simpler than the original QAP, the conversion increases the possibility to solve the QAP. Solving exactly the BQOP, however, is still very difficult. Indeed, a 1.48\% gap remains between the best known upper bound (UB) and lower bound (LB) of the unknown optimal value. This paper shows that the BQOP admits a nontrivial symmetry, a property that makes the BQOP very hard to solve. The symmetry induces equivalent subproblems in branch and bound (BB) methods. To effectively improve the LB, we propose an efficient BB method that incorporates a doubly nonnegative relaxation, the standard orbit branching and a technique to prune equivalent subproblems. With this BB method, a new LB with 1.25\% gap is successfully obtained, and computing an LB with $1.0\%$ gap is shown to be still quite difficult.Comment: 19 pages, 7 figures. arXiv admin note: substantial text overlap with arXiv:2210.1596

Implementation and Performance Evaluation of Distributed Autonomous Multi-Hop Vehicle-to-Vehicle Communications over TV White Space

This paper presents design and experimental evaluation of a distributed autonomous multi-hop vehicle-to-vehicle (V2V) communication system over TV white space performed in Japan. We propose the two-layer control channel model, which consists of the Zone Aware Control Channel (ZACC) and the Swarm Aware Control Channel (SACC), to establish the multi-hop network. Several vehicles construct a swarm using location information shared through ZACC, and share route and channel information, and available white space information through SACC. To evaluate the system we carried out field experiments with swarm made of three vehicles in a convoy. The vehicles observe channel occupancy via energy detection and agree on the control and the data channels autonomously. For coarse synchronization of quiet periods for sensing we use GPS driven oscillators, and introduce a time margin to accommodate for remaining drift. When a primary user is detected in any of the borrowed channels, the vehicles switch to a vacant channel without disrupting the ongoing multi-hop communication. We present the experimental results in terms of the time to establish control channel, channel switching time, delivery ratio of control message exchange, and throughput. As a result, we showed that our implementation can provide efficient and stable multi-hop V2V communication by using dynamic spectrum access (DSA) techniques