Orthogonal Angles Research Articles

Low velocity impact response of 2D and 3D Kevlar/polypropylene composites

In this study, low velocity impact (LVI) behaviors of composite laminates reinforced with fabrics of different architecture are investigated. Three kinds of fabric architecture, namely, two-dimensional plain woven (2D-P), three-dimensional orthogonal (3D-O) and three-dimensional angle interlock (3D-A), are prepared with Kevlar 29 (Kevlar) yarns. Composite laminates are manufactured with Kevlar fabrics and polypropylene (PP) resin. These composites are impact tested at 4 m/s and 6 m/s impact velocities. The post-impact response of the composites of different fabric architecture is studied. The results revealed that the impact resistance is mainly dependent on the in-plane stiffness of the laminates. The energy absorption ability is predominantly influenced by the existence of yarns in the thickness direction. The 3D composites absorbed 14–26% higher energy than the 2D laminates. Especially, 3D-A laminates exhibited a higher peak load (14.21–30.25%), more energy absorption (12.7–26.2%) and lower cone formation at the back of the target (25–39%) as compared to 3D-O and 2D-P composites.

A Minimal Closed-form Solution for the Perspective Three Orthogonal Angles (P3oA) Problem: Application To Visual Odometry

We provide a simple closed-form solution to the Perspective three orthogonal angles (P3oA) problem: given the projection of three orthogonal lines in a calibrated camera, find their 3D directions. Upon this solution, an algorithm for the estimation of the camera relative rotation between two frames is proposed. The key idea is to detect triplets of orthogonal lines in a hypothesize-and-test framework and use all of them to compute the camera rotation in a robust way. This approach is suitable for human-made environments where numerous groups of orthogonal lines exist. We evaluate the numerical stability of the P3oA solution and the estimation of the relative rotation with synthetic and real data, comparing our results to other state-of-the-art approaches.

Ballistic impact response of Kevlar® reinforced thermoplastic composite armors

The ballistic impact response of thermoplastic-based composite armors made from Kevlar® fabric and polypropylene (PP) matrix has been investigated against ballistic test standard NIJ-STD 0106.01 Type IIIA. Kevlar® fabrics of different architectures, namely 2D plain woven, 3D orthogonal and 3D angle interlock fabrics, were produced and used as reinforcements to fabricate composite armor panels, using compression molding technology. Interfacial property between PP and Kevlar® was improved by adding a coupling agent called maleic anhydride grafted PP. Reduced density was observed in Kevlar® thermoplastic-based composites as compared to that of the thermoset-based laminates. Ballistic impact tests were imparted with 9 mm full metal jacket (FMJ) on armor panels having different fabric architecture. Ballistic test results revealed that 2D armor was 2.4–7% more susceptible to damage than 3D armors. Hydrocode simulations were carried out using ANSYS AUTODYN v. 14.0 to obtain an estimate for the ballistic limit velocity and simulate failure modes. Post-impact damage patterns obtained from the simulations were compared with the experimental results to assess the performance of the simulations. Good correlation between the hydrocode simulations and experiments was found, both in terms of failure modes and damage patterns. 3D composite armors were able to confront the 9 mm FMJ projectile; however, the 2D plain woven armors failed. The increase in the ballistic limit from 2D plain woven armor to 3D orthogonal and 3D angle interlock armors was 16.44% and 20%, respectively, indicating the effect of fabric architecture.

THE GRISM LENS-AMPLIFIED SURVEY FROM SPACE (GLASS). I. SURVEY OVERVIEW AND FIRST DATA RELEASE

We give an overview of the Grism Lens Amplified Survey from Space (GLASS), a large Hubble Space Telescope program aimed at obtaining grism spectroscopy of the fields of ten massive clusters of galaxies at redshift z=0.308-0.686, including the Hubble Frontier Fields (HFF). The Wide Field Camera 3 yields near infrared spectra of the cluster cores, covering the wavelength range 0.81-1.69mum through grisms G102 and G141, while the Advanced Camera for Surveys in parallel mode provides G800L spectra of the infall regions of the clusters. The WFC3 spectra are taken at two almost orthogonal position angles in order to minimize the effects of confusion. After summarizing the scientific drivers of GLASS, we describe the sample selection as well as the observing strategy and data processing pipeline. We then utilize MACSJ0717.5+3745, a HFF cluster and the first one observed by GLASS, to illustrate the data quality and the high-level data products. Each spectrum brighter than H_AB=23 is visually inspected by at least two co-authors and a redshift is measured when sufficient information is present in the spectra. Furthermore, we conducted a thorough search for emission lines through all the GLASS WFC3 spectra with the aim of measuring redshifts for sources with continuum fainter than H_AB=23. We provide a catalog of 139 emission-line based spectroscopic redshifts for extragalactic sources, including three new redshifts of multiple image systems (one probable, two tentative). In addition to the data itself we also release software tools that are helpful to navigate the data.

Nonscattering Waveguides Based on Tensor Impedance Surfaces

A tensor impedance surface waveguide is built using anisotropic unit cells. The waveguide can propagate a confined waveguide mode along its axis while waves incident to the guide at an orthogonal direction pass through as if the waveguides were not present. Both straight and curved implementations are demonstrated. Surface waves incident at an angle to the waveguide show reflection and refraction at the impedance interface. A theoretical model for tensor impedance surface waveguides is generalized to include dispersive unit cells and bending loss around curves. Dispersion results for modes propagating in the waveguide show agreement between the theory, simulation, and experimental measurements. A curved waveguide is also constructed which guides surface waves around a curve and is transparent to surface waves incident at an orthogonal angle.

A compact time-of-flight mass spectrometer for ion source characterization.

A compact time-of-flight mass spectrometer with overall dimension of about 413 × 250 × 414 mm based on orthogonal injection and angle reflection has been developed for ion source characterization. Configuration and principle of the time-of-flight mass spectrometer are introduced in this paper. The mass resolution is optimized to be about 1690 (FWHM), and the ion energy detection range is tested to be between about 3 and 163 eV with the help of electron impact ion source. High mass resolution and compact configuration make this spectrometer useful to provide a valuable diagnostic for ion spectra fundamental research and study the mass to charge composition of plasma with wide range of parameters.

3个任意角度与2个正交角度偏振图像复原实验比较

3个任意角度与2个正交角度偏振图像复原实验比较

A Low Profile Four-Way Directional Antenna with Dual Polarization

This paper presents a low profile dual polarized directional antenna composed of loop and dipole arrays mounted on a ground plane with each loops and dipoles being fed independently. Each loop antenna is paired with a reflector while each dipole antenna is paired with a director and a reflector. The proposed antenna is intended for an indoor base station (BS) with resonance frequency of 2.4 GHz and capable of producing four orthogonal directional pattern with downward elevation angle equals to 30°; and half power bandwidth (HPBW) less than 80°; in both vertical and horizontal polarization. The reflection characteristics of the loop and dipole arrays are less than -10 dB and the mutual coupling between the vertical and horizontal polarization elements is nearly less than -20 dB. In later progress, the dipole antenna was substituted with printed dipole antenna to achieve a better performance. Both the calculated and measured results demonstrated that the desired radiation patterns were achieved, and the measured results agreed well with the calculated ones. Consequently, a low profile antenna with a thickness of 0.16 λ (20 mm) having the expected radiation pattern is successfully designed.

Single Field Spot-Scanning (SFSS) Is Dosimetrically Superior to 2-Field Intensity Modulated Proton Therapy (IMPT) for Proton Postmastectomy Radiation Therapy (PMRT)

Single Field Spot-Scanning (SFSS) Is Dosimetrically Superior to 2-Field Intensity Modulated Proton Therapy (IMPT) for Proton Postmastectomy Radiation Therapy (PMRT)

An Immediate Error Compensation Method for PCB Alignment Based on Image Measurement

The parallelism between an industrial camera and a servo motion direction is corrected with the help of image measurement to shadowed geometric contours. Then a nearly orthogonal angle between XY servo motion directions is obtained according to an inherent geometry relationship in contours. The installation error of a PCB in platform is compensated based on automatic multi-spot imaging finally. An experimental prototype was built while the PCB alignment was implemented on a lot of samples according to the method introduced above. It proves that the developed immediate alignment method as well as its specific embodiment fulfills the requirement of positioning accuracy in the initial design.

Algorithms for Two-dimensional XRD Data Evaluation

The diffracted x-rays from a polycrystalline (powder) sample form a series diffraction cones in space since large numbers of crystals oriented randomly in the space are covered by the incident x-ray beam. Each diffraction cone corresponds to the diffraction from the same family of crystalline planes in all the participating grains. When a two-dimensional (2D) detector is used for x-ray powder diffraction, the diffraction cones are intercepted by the 2D detector and the x-ray intensity distribution on the sensing area is converted to an image-like diffraction pattern. The 2D pattern contains the scattering intensity distribution as a function of two orthogonal angles. One is the Bragg angle 2θ and the other is the azimuthal angle about the incident x-ray beam, denoted by γ. A 2D diffraction pattern can be analyzed directly or by data reduction to the intensity distribution along γ or 2θ. The γ-integration can reduce the 2D pattern into a diffraction profile analogs to the conventional diffraction pattern which is the diffraction intensity distribution as a function of 2θ angles. This kind of diffraction pattern can be evaluated by most exiting software and algorithms for conventional applications, such as, phase identification, structure refinement and 2θ-profile analysis. However, the materials structure information associated to the intensity distribution along γ direction is lost through γ-integration. The intensity distribution and 2θ variations along γ contain more information, such as the orientation distribution, strain states, crystallite size and shape distribution. In order to understand and analyze 2D diffraction data, new approaches and algorithms are necessary. The diffraction vector approach has been approved to be the genuine theory in 2D data analysis. The unit diffraction vector used for 2D analysis is a function of both 2θ and γ. The unit diffraction vector for all the pixels in the 2D pattern measured in the laboratory coordinates can be transformed to the sample coordinates. The vector components can then be used to derive fundamental equations for many applications, including stress, texture, crystal orientation and crystal size evaluation by γ-profile analysis. The unit diffraction vector is also used in polarization and absorption correction.

SU‐E‐T‐513: Probabilistic Approach to Plan Evaluation in Linac‐Based Stereotactic Radiosurgery: A Patient Specific Uncertainty Analysis

Purpose:Acoustic neuroma is treated using highly conformal, framed‐based radiosurgery. The gross target volume (GTV) is located near the radiosensitive brainstem. Currently, plan evaluation methods that consider GTV dose conformity and dose to organs at risk (OAR) do not account for setup uncertainty, thereby potentially giving a false sense of target coverage and OAR sparing. More realistic plan evaluations should consider delivery uncertainties. In this work, we introduce a new plan evaluation method based on probability and investigate the effect of translational and rotational setup errors.Methods:Clinically approved 18 acoustic neuroma treatment plans were studied retrospectively. For each treatment plan, 200 new dose distributions were re‐calculated while introducing both translational (in all cardinal directions) and rotational errors (in all 3 orthogonal rotation angles). The magnitude of errors for each simulation was randomly generated from the Gaussian distribution with one standard deviation of 0.5 mm and 0.5 degree respectively. From the simulated dose distributions, an approximated probability density function of dose objective for both GTV and brainstem were calculated. The probability density function was then used to compute the probability of delivering prescribed dose to 90% of GTV for each patient. For brainstem, the probability of limiting maximum dose to 11Gy was calculated. These probabilistic metrics were then analyzed with respect to GTV volume, conformity index, and min and max dose to the GTV and brainstem.Results:Across all cases, the average probability of delivering prescribed dose to the 90% of GTV volume was 85±14%. Four patients showed > 50% risk of exceeding 11Gy limit to the brainstem.Conclusion:In highly conformal, single fraction radiosurgery, a small setup error can be critical. We found that the probabilistic assessment of plan objectives can be used to quantitatively assess true target coverage better than the conventional plan assessment metrics.

The Research on Cutting Performance of Two Kinds of Ti (C,N)-Based Cermet Cutters

A systematic cutting test was conducted turning normalized AISI1045 carbon steel with two kinds of Ti (C, N)-based cermet cutters, which were made with micron and nanometer TiC powders. And the cutting performance and abrasion mechanism was discussed in the article. The effect of tool orthogonal clearance on tool life was also researched in this paper. Results showed that: The tool life was affected seriously by tool orthogonal clearance angle, and the optimum tool orthogonal clearance angle of Ti (C, N)-based cermet cutter was 5°when cutting normalized AISI1045 steel. The cutting Performance of Ti (C, N)-based cermet cutters which were made with nanoTiC powders was better than the ones which were made with micron TiC powders obviously. And the primary wear behaviors were wear.

An improved topographic mapping technique from airborne lidar: application in a forested hillside

We developed a robust method to reconstruct a digital terrain model (DTM) by classifying raw light detection and ranging (lidar) points into ground and non-ground points with the help of the Progressive Terrain Fragmentation (PTF) method. PTF applies iterative steps for searching terrain points by approximating terrain surfaces using the triangulated irregular network (TIN) model constructed from ground return points. Instead of using absolute slope or offset distance, PTF uses orthogonal distance and relative angle between a triangular plane and a node. Due to this characteristic, PTF was able to classify raw lidar points into ground and non-ground points on a heterogeneous steep forested area with a small number of parameters. We tested this approach by using a lidar data set covering a part of the Angelo Coast Range Reserve on the South Fork of the Eel River in Mendocino County, California, USA. We used systematically positioned 16 reference plots to determine the optimal parameter that can be used to separate ground and non-ground points from raw lidar point clouds. We tested at different admissible hillslope angles (15° to 20°), and the minimum total error (1.6%) was acquired at the angle value of 18°. Because classifying raw lidar points into ground and non-ground points is the basis for other types of analyses, we expect that our study will provide more accurate terrain approximation and contribute to improving the extraction of other forest biophysical parameters.

SU‐E‐J‐38: Fast Patient Localization Method in Total Marrow Irradiation with Helical Tomotherapy

Purpose: Reducing imaging and treatment times is a crucial issue in total marrow irradiation (TMI) with helical tomotherapy. The purpose of this study was to develop the fast patient localization method for TMI patients with helical tomotherapy. Methods: The topographic images were acquired by getting the megavoltage CT (MVCT) after running calibration procedures with the couch traversing through the gantry at static orthogonal beam angles. Geometric and detector response corrections were performed to generate a MV topogram (MVtopo). We also generated kilovoltage topogram (kVtopo) from the projection data of 3D CT images datasets to reproduce the same geometry as MVtopo. Imaging dose and the optimal image acquisition parameters including jaw size, couch velocity, and dose rate were investigated. Geometric uncertainty and image quality of MVtopo were analyzed. In‐house image registration software was developed and verified with a rando phantom. Finally, MVtopo was acquired for a TMI patient. Results: The longitudinal geometric uncertainty was 0 mm, 10.2 mm, and 23.6 mm, in the jaw size of 0.3 cm, 1 cm, and 2.5 cm, respectively. No jaw size dependency in the lateral geometric uncertainty was observed. Couch velocity did not have an effect on the geometric uncertainty. The doses of MVCT and MVtopo with the jaw size of 3 mm and the couch velocity of 0.8cm/sec were 1.5cGy, and 1.7 cGy, respectively. Contrast‐Noise‐ratio, noise, and MTF were improved by using lower dose rate (55MU/min) and smaller jaw size (3 mm). The image registration accuracy with our in‐house software was within 1 mm. In a clinical TMI case, MVtopo with couch speed of 1.0cm/s reduced imaging time by 80% compared with MVCT. The couch shifts derived from KVCT with MVCT registration, and kVtopo with MVtopo registrations agreed within 4 mm. Conclusion: The MVtopo could be useful for TMI treatment with helical tomotherapy. This work was supported by the National Institute of Health grants (1R01CA154491‐01).This work was also supported by PHS Cancer Center Support Grant P30CA77398.

Miniaturized Fluorometer Based on Total Internal Reflector and Condensing Mirror

A miniaturized fluorescence detection system based on total internal reflection (TIR) configuration, which is applicable to detecting the presence of biological materials labeled with fluorescence dye in micro total analysis systems (μTAS), is proposed. In conventional fluorescence testing and analysis devices, interference between the excitation light beam and the emitted light from dyes is unavoidable. This paper presents a fluorescence detection system based on TIR configuration that allows the excitation light beam and the emitted light to be spatially perpendicular to each other so as to minimize the interference where fluorescence emission is detected at the orthogonal angle to the excitation beam. We achieved the limit of detection of about 5 nmol/L with a high linearity of 0.994 over a wide range of 6-FAM mol concentration, being comparable to that in earlier studies.

Frequency Structures Vibration Identified by an Adaptative Filtering Techiques Applied on GPS L1 Signal

This paper is part of a research under enhancement since 2001, in which the main objective is to measure small dynamic displacements by analysis of L1 GPS carrier frequency with 1575.42 MHz—wavelength 19.05 cm, under an adaptive method for collecting data and filtering techniques. This method, named Phase Residual Method (PRM) is based on the frequency domain analysis of the phase residuals resulted from the L1 double difference static data processing of two satellites in almost orthogonal elevation angle. In this work it is proposed to obtain the phase residuals directly from the raw phase observable collected in a short baseline during a limited time span, in lieu of obtaining the residual data file from regular GPS processing programs. In order to improve the ability to detect millimetric displacements, two filtering techniques are introduced. The first one is the autocorrelation that reduces the phase noise with random time behavior. The other one is the running mean to separate low frequency from the high frequency phase sources. Two trials are presented to verify the proposed method and filtering techniques applied. One simulates a 2.5 millimeter vertical GPS antenna displacement and the second using the data collected during a bridge dynamic load test. The results show a good consistency to detect millimetric oscillations from L1 frequency and filtering techniques.

An Experimentalapproach to Investigate the Effect of Process Conditions on Exit Burr formation in Shapingan Aluminiumalloy

At the exit edge of the wokpiece, burrs are usually found during shaping operation. Gradual rotation of the positive shear plane to the negative shear plane may be the reason behind it. This is due to absence of any support material at the exit end of cut. In the present work, a number of orthogonal shaping experiments is performed on aluminium alloy (4600-M) in dry environment under different cutting velocities, orthogonal rake angles and exit edge bevel angles to observe the occurrence of burr formation. Experimental results are analysed through ANOVA to find out the significance of the effect of cutting parameters and exit edge bevel angle to control the exit burr formation. It is noted that exit edge bevel angle has the most significant effect. An exit edge bevel angle of 15° is recommended in shaping operation when burr becomes negligible.

A feasibility study of digital tomosynthesis for volumetric dental imaging

We present a volumetric dental tomography method that compensates for insufficient projection views obtained from limited-angle scans. The reconstruction algorithm is based on the backprojection filtering method which employs apodizing filters that reduce out-of-plane blur artifacts and suppress high-frequency noise. In order to accompolish this volumetric imaging two volume-reconstructed datasets are synthesized. These individual datasets provide two different limited-angle scans performed at orthogonal angles. The obtained reconstructed images, using less than 15% of the number of projection views needed for a full skull phantom scan, demonstrate the potential use of the proposed method in dental imaging applications. This method enables a much smaller radiation dose for the patient compared to conventional dental tomography.

Behavior of Expelled Glass Fragments During Projectile Penetration and Perforation of Glass

Bullets striking common forms of flat glass with an orthogonal intercept angle result in a cloud of ejected glass fragments that are in concert with the exiting bullet's flight path. This is not the case with strikes at angles other than orthogonal. In these situations, the expelled glass fragments follow a very different course from that of the exiting projectile. This is both counterintuitive and a potential source of serious error in the evaluation and reconstruction of a shooting victim's position and orientation at the moment the victim was struck by a bullet that has passed through a nearby source of glass such as a vehicle side window or a window in a building. The flight path of the ejected glass fragments is, however, predictable and is dictated by the orientation of the plane of the glass opposite the projectile's impact site.In all cases, these expelled glass particles have considerable velocity and can produce pseudostippling of the skin in individuals located downrange of bullet-struck glass and near the projectile's exit site. The distribution and location of such pseudostippling and its relationship to the associated bullet hole in glass have important reconstructive value. A proper and reliable reconstruction of the victim's position in such cases will require the integration of scene information with the autopsy findings.