Bending Angle Measurements Research Articles

Pedestrian Lower Limb Injury Criteria Evaluation: A Finite Element Approach

Objective. In pedestrian traumas, lower limb injuries occur under lateral shearing and bending at the knee joint level. One way to improve injury mechanisms description and consequently knee joint safety is to evaluate the ultimate shearing and bending levels at which ligaments start being injured. Methods. As such data cannot easily and accurately be recorded clinically or during experiments, we show in this article how numerical simulation can be used to estimate such thresholds. This work was performed with the Lower Limb Model for Safety (LLMS) in pure lateral bending and shearing conditions, with an extended range of impact velocities. Results. One result concerns the ultimate knee lateral bending angle and shearing displacement measurements for potential failure of ligaments (posterior cruciate, medial collateral, anterior cruciates and tibial collateral). They were evaluated to be close to 16° and 15 mm, respectively. Conclusion. The lower leg model used in this study is an advanced FE model of the lower limb, validated under various situations. Its accurate anatomical description allows a wide range of applications. According to the validity domain of the model, it offered a valuable tool for the numerical evaluation of potential injuries and the definition of injury risk criterion for knee joint.

Retrieval of temperature and water vapor profiles from radio occultation refractivity and bending angle measurements using an Optimal Estimation approach: a simulation study

Abstract. The Optimal Estimation Method is used to retrieve temperature and water vapor profiles from simulated radio occultation measurements in order to assess how different retrieval schemes may affect the assimilation of this data. High resolution ECMWF global fields are used by a state-of-the-art radio occultation simulator to provide quasi-realistic bending angle and refractivity profiles. Both types of profiles are used in the retrieval process to assess their advantages and disadvantages. The impact of the GPS measurement is expressed as an improvement over the a priori knowledge (taken from a 24h old analysis). Large improvements are found for temperature in the upper troposphere and lower stratosphere. Only very small improvements are found in the lower troposphere, where water vapor is present. Water vapor improvements are only significant between about 1 km to 7 km. No pronounced difference is found between retrievals based upon bending angles or refractivity. Results are compared to idealized retrievals, where the atmosphere is spherically symmetric and instrument noise is not included. Comparing idealized to quasi-realistic calculations shows that the main impact of a ray tracing algorithm can be expected for low latitude water vapor, where the horizontal variability is high. We also address the effect of altitude correlations in the temperature and water vapor. Overall, we find that water vapor and temperature retrievals using bending angle profiles are more CPU intensive than refractivity profiles, but that they do not provide significantly better results.

Development of a Data Glove With Reducing Sensors Based on Magnetic Induction

In this paper, we present the development of a data glove system using magnetic induction coils as finger movement sensors. This data glove has the capability of measuring ten degrees of freedom of a hand with only five sensors that are arranged properly on the palmar surface instead of the dorsal surface. Because these sensors are installed on the finger phalange positions, there is no contact point between the sensors and the finger joints. Hence, the shape of the sensors does not change as the fingers are bending, and the quality of measurement and the lifetime of the sensors will not decrease with time. Additionally, the motion constraints of the finger joints are investigated to simplify the development of the data glove. For the convenience of using this glove, a simple and efficient calibration process consisting of two steps is also provided, so that all required parameters can be determined automatically. The theoretical formulation of the bending angles of proximal interphalangeal, metacarpophalangeal, and thumb interphalangeal joints as well as the calibration equations are derived directly from the positions and orientations of the generator and sensor coils on the data glove. Also described and realized are the circuit block diagram and the construction of the data glove system. To prevent the interference among the generator coils, we adopt the time division method to scan the generator and sensor coils. So far, the experimental results of the sensors performing linear movement and bending angle measurements directly using an oscilloscope in less noisy environments are very satisfactory. It reveals that our data glove is available for a man-machine interface.

One‐dimensional variational (1‐D Var) retrieval of temperature, water vapor, and a reference pressure from radio occultation measurements: A sensitivity analysis

A 1‐D Var retrieval study of simulated radio occultation measurements is presented. Temperature and a water vapor profile are retrieved along with a reference pressure to generate the pressure profile by applying the hydrostatic equation. High‐resolution European Center for Medium‐Range Weather Forecasts (ECMWF) atmospheric fields are used by a ray tracing tool to calculate the exact positions of the tangent point. The 1‐D atmospheric profiles following the calculated tangent point trajectory in the 3‐D ECMWF fields are used to simulate bending angle measurements with a 1‐D forward model. Assimilation of these bending angles in a 1‐D Var tool employing the same 1‐D forward model is performed. We analyze the sensitivity of the retrieval to changes in vertical resolution, horizontal smearing of the tangent point trajectory, and the assumption of hydrostatic equilibrium for a nonvertical atmospheric scan. We find that retrievals calculated without adequate vertical resolution can have significant errors in temperature and water vapor. Errors in the retrieval by assuming hydrostatic equilibrium for a nonvertical scan generally cause only minor errors in the retrieved profiles. A study into the occurrence of rays curving down toward the Earth surface indicates that about 5–10% of the profiles could experience so‐called critical refraction at altitudes between 0.5 km and 2 km in case of the applied high‐resolution ECMWF data.

Application of an optimal estimation inverse method to GPS/MET bending angle observations

Palmer et al. [2000] describes an optimal estimation inverse method for radio occultation (RO) bending angle measurements to retrieve simultaneously temperature, humidity, and surface pressure; outlines quality control procedures for retrieved profiles; and investigates the results from numerical simulations. Here we present retrievals that use bending angle observations from the Global Positioning System Meteorology (GPS/MET) satellite instrument and a priori information from the European Centre for Medium‐Range Weather Forecasts analyses. Retrieved profiles are compared with correlative radiosondes, United Kingdom Meterological Office (UKMO) model analyses, and retrievals from the conventional inverse method. Retrieved temperature profiles are generally colder than analyses but agree with the conventional inverse method to within 1 K. Water vapor retrievals are generally drier than the UKMO analyses and wetter than the radiosonde profiles. Quality of retrieved surface pressure values are related to the extent to which RO observations reach into the troposphere. Low‐latitude retrievals make large adjustments to surface pressure and tropospheric temperatures, which are directly linked to the lack of water vapor above 300 hPa in the inverse model, consistent with previous studies. A study of individual occultations at low and high latitude shows that the optimal retrievals are able to resolve small‐scale atmospheric structure exhibited by the conventional inverse method and collocated radiosondes, not shown by analyses.

Computer simulation and experimental investigation of sheet metal bending using laser beam scanning

Computer simulation and experimental investigation of the sheet metal bending into a V-shape by the laser beam scanning without an external force exerted onto it have been performed. A 3-D FEM simulation has been carried out, which includes a non-linear transient indirect coupled thermal-structural analysis accounting for the temperature dependency of the thermal and mechanical properties of the materials. The bending angle, distribution of stress–strain, temperature and residual stresses have been obtained from the simulations. The sheet metal bending had been performed for different materials, thicknesses, scanning speeds and laser powers. The measurement of real-time temperature and bending angle was carried out. The bending angle is affected by the mechanical and thermal properties of the sheet metal material, the process parameters, and the output of laser energy. The bending angle is increased with the number of laser beam scanning passes and is the function of the laser power and the laser beam scanning speed. The simulation results are in agreement with the experimental results.

A nonlinear optimal estimation inverse method for radio occultation measurements of temperature, humidity, and surface pressure

An optimal estimation inverse method is presented which can be used to retrieve simultaneously vertical profiles of temperature and specific humidity, in addition to surface pressure, from satellite‐to‐satellite radio occultation observations of the Earth's atmosphere. The method is a nonlinear, maximum a posteriori technique which can accommodate most aspects of the real radio occultation problem and is found to be stable and to converge rapidly in most cases. The optimal estimation inverse method has two distinct advantages over the analytic inverse method in that it accounts for some of the effects of horizontal gradients and is able to retrieve optimally temperature and humidity simultaneously from the observations. It is also able to account for observation noise and other sources of error. Combined, these advantages ensure a realistic retrieval of atmospheric quantities. A complete error analysis emerges naturally from the optimal estimation theory, allowing a full characterization of the solution. Using this analysis, a quality control scheme is implemented which allows anomalous retrieval conditions to be recognized and removed, thus preventing gross retrieval errors. The inverse method presented in this paper has been implemented for bending angle measurements derived from GPS/MET radio occultation observations of the Earth. Preliminary results from simulated data suggest that these observations have the potential to improve numerical weather prediction model analyses significantly throughout their vertical range.

Wrapping of DNA around the E.coli RNA polymerase open promoter complex.

High-resolution atomic force microscopy (AFM) and biochemical methods were used to analyze the structure of Escherichia coli RNA polymerase.sigma(70) (RNAP) open promoter complex (RP(o)). A detailed analysis of a large number of molecules shows that the DNA contour length of RP(o) is reduced by approximately 30 nm (approximately 90 bp) relative to the free DNA. The DNA bend angle measured with different methods varied from 55 to 88 degrees. The contour length reduction and the DNA bend angle were much less in inactive RNAP-DNA complexes. These results, together with previously published observations, strongly support the notion that during transcription initiation, the promoter DNA wraps nearly 300 degrees around the polymerase. This amount of DNA bending requires an energy of 60 kJ/mol. The structural analysis of the open promoter complexes revealed that two-thirds of the DNA wrapped around the RNAP is part of a region upstream of the transcription start site, whereas the remaining one-third is part of the downstream region. Based on these data, a model of the sigma(70).RP(o) conformation is proposed.

?-Ray-induced degradation: A comparative study for homo- and copolymers of polypropylene

Disposable medical supplies are currently made of polypropylene, which are conveniently sterilized by exposure to γ-rays. However, the homopolymers (HP) and random copolymer (CP) of polypropylene, when exposed to high-energy γ-irradiation, undergo oxidative degradation and loss in mechanical properties. In the current article, a comparative study of the effect of γ-irradiation at different irradiation doses and the postirradiation oxidation on both the polymers is reported. The loss in mechanical properties was monitored by the bend angle and tensile measurements. The yellowness index measurements were carried out as a function of the irradiation dose and postirradiation storage time. The changes in the molecular weight (MW) and molecular weight distribution (MWD) were monitored using melt index (MI) measurements. The changes in chemical structure was determined using infrared spectroscopy. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65: 2715–2720, 1997

Interlaminar and intralaminar fracture modes in 0/90 cross-ply glass/epoxy laminate

Delamination of a cross-ply 0/90 glass fibre-reinforced composite laminate with an epoxy-phenol matrix was studied using a double cantilever beam test. Fracture toughness was determined by measurement of bend angle of the cantilever beams. Results obtained with this method were in agreement with those from conventional compliance and area methods. Two different fracture modes were observed: interlaminar and intralaminar. In the interlaminar fracture mode, crack jumps in the space between two neighbouring 0° and 90° plies were observed. With the interlaminar fracture mode, during crack initiation G Ic decreased with crack length. Intralaminar fracture mode consisted of the gradual growth of a crack through a 0° ply. Fibres bridging the opposite sides of the crack were observed in this case, and fracture toughness G Ic did not change with crack length. G Ic (420 J m −2) at intralaminar fracture mode was approximately twice that at interlaminar fracture mode (220 J m −2). The difference in fracture toughness was explained by the dissipation of energy by fibres bridging the opposite sides of the crack at intralaminar fracture mode.