129 research outputs found
Design of a bioinspired ray robot with flexible fins
This paper presents the design and construction of a biomimetic swimming robot inspired by the locomotion of rays. These fishes move by flapping their pectoral fins and creating a wave that moves in the opposite direction to the direction of motion, pushing the water back and giving the fish a propulsive force due to momentum conservation. The robot's fins are molded from silicone rubber and moved by a servo motor that drives a mechanism inside the leading edge of each fin. The traveling wave, mimicking the movement of the fin, is passively generated by the flexibility of the rubber itself. The robot is also equipped with a tail that acts as a rudder, helpful in performing maneuvers. The rigid central body of the robot is the housing for motors, electronics, and batteries
Design of a swimming snake robot
This paper presents the design and realization of a bioinspired snake robot that can move on the water surface. This robot mimics the locomotion strategies of anguilliform fishes such as eels and lampreys, which have a thin, long, cylindrical body and whose movement resembles the crawling of a snake. An autonomous underwater vehicle with such a shape can pass through narrow crevices and reach places inaccessible to other swimming robots. Moreover, this locomotion entails a high energy efficiency and outstanding agility in maneuvers. The body of the bioinspired robot consists of a modular structure in which each module contains a battery, the electronic board, and a servo motor that drives the following module. The head of the robot has a different shape as it contains a camera and an ultrasonic sensor used to detect obstacles. In addition to the design of the robot, this paper also describes the implementation of the kinematic model
Hand-arm vibration in motocross: measurement and mitigation actions
SUMMARY
Objective. This study focused on the quantification of vibration which reaches the hands of motocross riders and on the reduction of such vibration thanks to the handlebar and handlebar mounts.
Background. Vibration transmitted through the hand and arm can lead to vascular and musculo- skeletal problems that are well documented in the scientific literature. Controlled studies identi- fying plate-handlebar characteristics effects on the vibration attenuation in motocross are lacking. Methods. We measured the vibration exposure of professional and recreational motocross riders on a motocross track and replicated the vibration patterns on a LDS V930 shaker in the laboratory, to analyze the effectiveness of various components in reducing the rider vibration exposure. Labo- ratory tests were performed with ten subjects randomly gripping different combinations of handle- bars and steering plates, and questionnaires were used to evaluate the comfort. Objective measure- ments of vibration reduction were then compared to the subjective values of perceived comfort. Results. According to the current EU legislation, the measured vibration levels reach the expo- sure limit in less than 1h. The mechanical characteristics of the handlebars and steering plates have a limited effect on the vibration transmitted to the rider’s hands. The rubber elements that many manufacturers use to reduce the vibration have limited effects at frequencies that are harmful for the musculoskeletal system. Questionnaires results have no correlation with the measured plate and handlebar performances.
Conclusions. Most of the techniques used to reduce the hand-arm vibration exposure of moto- cross drivers are ineffective
Peripheral facial palsy following ventriculoperitoneal shunt. The lesson we have learned
The most frequent complications after shunt surgery are infective and obstructive. Other types are less common, and eventually occur due to technical errors during brain ventricular puncture, opening the intraperitoneal cavity or the tunnelling of the catheter between the two points. Although rare, there are well-reported complications related to the poor positioning of the distal catheter, with perforation of organs and tissues. We report a very rare case of a male patient with normal pressure hydrocephalus submitted to ventriculoperitoneal shunt. During tunnelling of the shunt stylet, a peripheral facial palsy due to injury to the extra cranial segment of the facial nerve occurred. To the best of our knowledge this is the second case described in Literature. The patient and the surgeon should be aware of this very rare but possible complication in shunt surgery being careful to the course of the facial nerve in the mastoid region
Global parameter identification of stochastic reaction networks from single trajectories
We consider the problem of inferring the unknown parameters of a stochastic
biochemical network model from a single measured time-course of the
concentration of some of the involved species. Such measurements are available,
e.g., from live-cell fluorescence microscopy in image-based systems biology. In
addition, fluctuation time-courses from, e.g., fluorescence correlation
spectroscopy provide additional information about the system dynamics that can
be used to more robustly infer parameters than when considering only mean
concentrations. Estimating model parameters from a single experimental
trajectory enables single-cell measurements and quantification of cell--cell
variability. We propose a novel combination of an adaptive Monte Carlo sampler,
called Gaussian Adaptation, and efficient exact stochastic simulation
algorithms that allows parameter identification from single stochastic
trajectories. We benchmark the proposed method on a linear and a non-linear
reaction network at steady state and during transient phases. In addition, we
demonstrate that the present method also provides an ellipsoidal volume
estimate of the viable part of parameter space and is able to estimate the
physical volume of the compartment in which the observed reactions take place.Comment: Article in print as a book chapter in Springer's "Advances in Systems
Biology
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