Field-of-view-constrained impact angle control guidance with error convergence before interception considering speed changes

An impact angle control guidance law is proposed for stationary target interception considering missile's field-of-view limit and speed changes. The proposed impact angle control guidance law is structured as a biased proportional navigation with a time-varying bias. The proposed guidance law does not involve any switching logic for maintaining lock-on; hence, the guidance command is continuous during the entire engagement. Unlike the most existing studies, the proposed method guarantees that the impact angle error converges to zero before interception without the constant-speed assumption. To realize these desirable properties, the positive invariance of the bounded look angle interval and the change of independent variable are utilized. Numerical simulations are conducted to demonstrate the performance of the proposed guidance law.

Research on balanced self-weight of horizontal link heavy duty servo cylinder

In this article, the horizontal hinged heavy duty servo cylinder is taken as the research object. In the actual working process, while the servo hydraulic cylinder outputs the curve force, the cylinder body will also rotate with the hinge point to a certain extent. Because the position of the center of gravity is constantly changing, and the weight of the cylinder body is too large, the friction causes damage to the sealing structure and seriously affects the working efficiency of the equipment. In order to improve the sealing performance of the servo hydraulic cylinder, a corresponding study is carried out. Firstly, the working angle interval of servo cylinder is optimized to ensure that the friction is the least in this range. Based on this, a new supporting structure is proposed, in which a small hydraulic cylinder is installed at the bottom of the servo hydraulic cylinder body. By controlling the output force of the small hydraulic cylinder, the cylinder body and piston rod are aligned all the time. The servo cylinder body is flexibly processed to more realistically see the adverse effect of the friction, and the co-simulation method using MSC.ADAMS and MATLAB/Simulink verifies the new support structure to improve the sealing performance. According to the simulation results and experiment results, and combined with the deformation curve of the hydraulic cylinder, when the maximum displacement is 336 mm, the maximum rotation angle is 15.6°, the friction is the smallest, about 5801.9 N. It is known from the experiment results that after adding the new support structure, the frictional force is reduced to 1365.9 N, which reduces the friction of nearly 76.5%.

Human Face and Facial Parts Detection using Template Matching Technique

Face recognition has become relevant in recent years because of its potential applications. The aim of this paper is to find out the relevant techniques which give not only better accuracy also the efficient speed. There are several techniques available for face detection which give much better accuracy but the execution speed is not efficient. In this paper, a normalized cross-correlation template matching technique is used to solve this problem. According to the proposed algorithm, first different facial parts are detected likes mouth, eyes, and nose. If any of the two facial parts are found successfully then the face can be detected. For matching the templates with the target image, the template rotates at a certain angle interval.

Ceres observed at low phase angles by VIR-Dawn

Context. Particulate surfaces exhibit a surge of reflectance at low phase angles, a phenomenon referred to as the opposition effect (OE). Two mechanisms are recognized as responsible for the OE: shadow hiding (SH) and coherent backscattering. The latter is typically characterized by a small angular width of a few degrees at most and according to the theoretical prediction should exhibit wavelength and albedo dependence. Aims. We characterize the OE on the surface of Ceres using Dawn Visible InfraRed mapping spectrometer hyperspectral images at low phase angles. Furthermore, this dataset, coupled with previous observations, allows us to perform a complete spectrophotometric modeling at visual-to-infrared (VIS-IR) wavelengths (0.465–4.05 μm) in the broad phase angle range ≈0°−132°. Methods. We applied Hapke’s theory to the average phase curve for Ceres. Disk-resolved properties of the OE were investigated through an empirical model. Results. Across the investigated phase angle interval, Ceres’ average phase curve exhibits a smaller back-scattering contribution for increasing wavelengths. This determines a progressive spectral reddening at larger phase angles that we hypothesize as being related to the effect of submicron roughness on the grain surface. In the OE region, the shape of the phase curves is fairly constant across the VIS range and no sharp opposition surge at very small phase angles (α < 2°) can be recognized. This would suggest a major contribution from SH to Ceres’ OE. Assuming SH as the dominant mechanism, from the OE angular width we infer a high surface porosity (≈0.9), which appears in good qualitative agreement with Ceres’ low thermal inertia. Thanks to the OE observations we derive Ceres’ VIS-IR geometric albedo with a reference value at 0.55 μm of 0.098 ± 0.007. Mapping of the VIS normal albedo and OE angular width across a portion of the surface of Ceres does not reveal a spatial correlation between these quantities, consistent with SH dominating in the α = 0°−7° interval. The comparison of Ceres’ V -band magnitude curve with that of other asteroids indicates that Ceres’ OE is typical of a low-albedo object and compatible with the C-class type.

Methods for Grating Lobe Suppression in Ultrasound Plane Wave Imaging

Plane wave imaging has been proven to provide transmit beams with a narrow and uniform beam width throughout the imaging depth. The transmit beam pattern, however, exhibits strong grating lobes that have to be suppressed by a tightly focused receive beam pattern. In this paper, we present the conditions of grating lobe occurrence by analyzing the synthetic transmit beam pattern. Based on the analysis, the threshold of the angle interval is presented to completely eliminate grating lobe problems when using uniformly distributed plane wave angles. However, this threshold requires a very small angle interval (or, equivalently, too many angles). We propose the use of non-uniform plane wave angles to disperse the grating lobes in the spatial domain. In this paper, we present an approach using two uniform angle sets with different intervals to generate a non-uniform angle set. The proposed methods were verified by continuous-wave transmit beam patterns and broad-band 2D point spread functions obtained by computer simulations.

Comparison of different hadron production models for the study of π±, K±, protons and antiprotons production in proton–carbon interactions at 90 GeV/c

In this research paper, comprehensive results on the double differential yield of [Formula: see text] and [Formula: see text] mesons, protons and antiprotons as a function of laboratory momentum in several polar angle ranges from 0–420 mrad for pions, 0–360 mrad for kaons, proton and antiproton are reported. EPOS 1.99, EPOS-LHC and QGSJETII-04 models are used to perform simulations. The predictions of these models at 90 GeV/c are plotted for comparison, which shows that QGSJETII-04 model gives overall higher yield for [Formula: see text] mesons in the polar angle interval of 0–40 mrad but for the [Formula: see text] the yield is higher only up to 20 mrad. For [Formula: see text] mesons after 40 mrad, EPOS-LHC predicts higher yield as compared to EPOS 1.99 and QGSJETII-04 while EPOS-LHC and EPOS 1.99 give similar behavior in these two intervals. However, for [Formula: see text] mesons EPOS-LHC and EPOS 1.99 give similar behavior in these two intervals. For of [Formula: see text] mesons, QGSJETII-04 model gives higher predictions in all cases from 0–300 mrad, while EPOS 1.99 and EPOS-LHC show similar distributions. In case of protons, all models give similar distribution but this is not true for antiproton. All models are in good agreement for p [Formula: see text] 20 GeV/c. EPOS 1.99 produce lower yield compared to the other two models from 60–360 mrad polar angle interval.

Measurement of needle susceptibility artifacts in magnetic resonance images

The success of minimally invasive procedures under MR-guidance can be increased by the knowledge of the current needle pose. We hypothesize that a one-toone mapping exists between the needle orientation with respect to the static magnetic field and the cross-sectional shape of the needle’s susceptibility artifact. For this purpose, we derived a mathematical model, which describes the cross sectional geometry of the needle artifact. It is approximated by two ellipses. Certain parameters of these ellipses can be utilized for mapping the geometry of the needle artifact onto the needle orientation. The relation between the two ellipse parameters α (inclination of the semi-major axis) and b (length of the semi-minor axis) and the needle’s azimuth angle can be approximated by linear regression in a certain angle interval. A combination of these two ellipse parameters is suitable for estimating the needle’s azimuth angle within a range between 0° and 60°.

Study on Mathematical Model of Cylindricality Error

According to the standard definition of cylindricality error, set up any space surface cylindricality errors of least squares mathematics model. The coordinate origin of the model can be freely selected, nor equal angle interval among discrete sampling points. Analysis by computer simulation, results show that the model developed is right and pratical. On the basis of mathematical models, using four direct algorithm for unconstrained optimization, cylindricality errors can be evaluated in accordance with the minimum conditions. Mathematical models can be used for three-coordinate measuring machine and also available for other intelligent instrument for measuring parts of the cylindricality errors.