Plane Mode Research Articles

Effect of parallel joint interaction on mechanical behavior of jointed rock mass models

To better understand the interaction of parallel joints and its effect on the mechanical behavior of jointed rock mass models, the results of a physical experiment program undertaken in the laboratory were present in this manuscript. The joint spacing and joint overlap are varied to alter the relative positions of parallel joints in geometry. Accordingly, four basic failure modes identified from the testing results are tensile failure across the joint plane, shear failure along the joint plane, tensile failure along the joint plane, and intact material failure. The wing cracks from tensile failure across the joint plane mode represent the interaction between parallel joints which depends on the joint dip angle, joint spacing and joint overlap. With the increment of parallel joint interaction, the corresponding normalized strength and maximum displacement at peak stress of jointed rock mass models reduced generally except at α=0°.

An Efficient Architecture of Intra Prediction and TQ/IQIT Module of Video Encoder

Objectives: In this paper, an efficient architecture of intra prediction module of H.264 high profile encoder is proposed. This module can be operated in 308 cycles for one macroblock. Methods/Statistical Analysis: The plane mode removal and SAD (Sum of Absolute Difference) distortion calculation are adopted to reduce the hardware cost and cycle. The sharing method of the Q (Quantization) and IQ (Inverse Quantization) modules for I4MB and I8MB prediction, calculation method of the DC value of I16MB and chroma predictions in prediction cycles to speed up the macroblock processing cycle are proposed. Findings: The proposed hardware was verified with the vector generated by reference C using JM13.2. The designed circuit has 250 K gate counts by using TSMC 0.18 um process including SRAM memory and can operate in 160 MHz clock. Improvements/Applications: The cycle for one macroblock is reduced compared with other architectures.

평면 모델링을 통한 깊이 영상 부호화의 개선

본 논문에서는 평면을 모델링하여 깊이 정보를 보정하고 부호화를 개선하는 방법을 제안한다. 먼저 보정하고자 하는 화소를 중심으로 수평, 수직 방향으로 최소 자승법을 이용하여 평면을 모델링한 후 예측 오차에 근거하여 예측된 평면이 적합한지 판단한다. 그 후 모델링된 평면상의 깊이 화소 값으로 보정한다. 제안된 방법을 통해 평면으로 이루어진 깊이 영상뿐만 아니라 다양한 깊이 정보를 가지는 깊이 영상에 대해서도 보정이 가능하다. 제안된 방법을 적용하여 부호화 성능을 나타내는 엔트로피 척도를 측정한 결과, 부호화 성능이 최대 80.2% 개선된 것을 확인하였다. In this paper, we propose a method of correcting depth image by the plane modeling and then improving the coding performance. We model a plane by using the least squares method to the horizontal and vertical directions including the target pixel, and then determine that the predicted plane is suitable from the estimate error. After that, we correct the target pixel by the plane mode. The proposed method can correct not only the depth image composed the plane but also the complex depth image. From the simulation result that measures the entropy power, which can estimate the coding performance, we can see that the coding performance by the proposed method is improved up to 80.2%.

Thermal Conductivity and Pressure-Dependent Raman Studies of Vertical Graphene Nanosheets

Thermal and mechanical properties of graphene sheet are of significant importance in the areas of thermal and stress management, respectively. Here, we report the thermal conductivity and high-pressure behaviors of unsupported vertical graphene nanosheets (VGNs) grown by electron cyclotron resonance-plasma enhanced chemical vapor deposition method. Structural morphology of the as-grown VGNs on SiO2/Si substrate suggests a homogeneous, uniformly interconnected network of graphene sheets standing vertically on a basal nanographitic layer. On examination of edges of exfoliated sheets using transmission electron microscopy, seven layers of graphene is estimated. The frequency of the G-band (E2g-in plane mode) is found to vary linearly with temperature. The first-order temperature coefficient for G-band is found to be 1.47(1) × 10–2 cm–1 K–1. Using the G-band temperature coefficient and its position dependence on excitation laser power, the thermal conductivity of the VGNs at room temperature is estimated to b...

Damage detection in laminated composite plates via an optimal wavelet selection criterion

Delamination is a potential risk of failure considered as one of the failure modes and frequently occurs in composites due to its relatively low inter-laminar fracture toughness. In recent years, the majority of activities in this field have been focused on raising the level of sensitivity of these devising methods for detecting tiny damages. In this article, damage detection method via wavelet transform has been examined, and an appropriate procedure has been proposed to increase sensitivity of this transform for damage detection. Among the inherent impediments of classical wavelet transforms, the generality of these transforms and ignoring the studied signal can be mentioned. Consequently, various wavelet selection algorithms leading to provide appropriate wavelet functions with respect to the characteristics of the signal have been examined. As a novelty in the field, the correlation between wavelet and strain energy signal is considered as a criterion for optimal wavelet selection. In wavelet transforms, in addition to original wavelet functions, the signals used for damage detection are also of high importance. To achieve this goal, the frequency-weighted strain energy ratio signals resulting from intact and damaged forms have been exploited. Also, the edges’ effects were removed through stringing of plane mode shape signals. Moreover, by summing wavelet coefficients in all scale factors plus natural frequencies, the focus can bring to the detection of one or more damages in a laminated composite plate with symmetric layup. Finally, a quantitative measure to compare different wavelets has been presented.

Strictly convergent nonsingular terminal sliding mode guidance law with impact angle constraints

In this paper, we develop a strictly convergent nonsingular terminal sliding mode guidance law for missiles with impact angle constraints. A novel nonsingular terminal sliding mode (NNTSM) control scheme is first proposed to improve the effectiveness of conventional terminal sliding mode in the whole phase plane, where the time taken to reach both the sliding surface and equilibrium point is guaranteed to be finite time. The proposed NNTSM control scheme is then applied to the guidance law of missiles with impact angle constraints, where extended state observer is designed to estimate the target acceleration. Simulation results are presented to validate the proposed guidance law.

Failure mode transition of Nb phase from cleavage to dimple/tear in Nb-16Si-based alloys prepared via spark plasma sintering

The influence of Nb powder sizes and morphologies (equiaxed and flaky powders) on fracture behaviour of the Nb-16Si alloy and a Nb-16Si-22Ti-2Al-2Hf-7Cr alloy with a Nb/Nb5Si3 microstructure fabricated via spark plasma sintering (SPS) was investigated. A decrease in the Nb powder size from 78.8μm to 4.9μm led to a fine-grain (9.9μm) Nb matrix plus a Nb5Si3 island microstructure, which changed fracture mode of Nb from cleavage to a mixed mode of dimple, tear and cleavage, the fracture toughness (KQ) of the Nb-16Si samples was significantly improved from 8.2MPa·m1/2 to 12.4MPa·m1/2. A further improvement of KQ to 15.8MPa·m1/2 was achieved in the Nb-16Si-22Ti-2Al-2Hf-7Cr alloy owing to full dimples on the finer Nb grains (11.2μm) through the addition of 22at.% Ti and 2at.% Hf. When the flaky Nb powders (123.6μm in diameter and 15.1μm in thickness) were used, two fracture modes were observed in one flaky Nb grain, i.e., the cleavage mode in the radial plane and the dimple/tear mode in the thickness plane of the flaky Nb grain. These fracture modes in one flaky Nb grain are also beneficial to improving KQ of the bulk Nb-16Si sample.

Acoustical gas-leak detection in the presence of multiple reflections, dispersion, and uncorrelated noise using optimized residual complexity.

Precise acoustical leak detection calls for robust time-delay estimates, which minimize the probability of false alarms in the face of dispersive propagation, multiple reflections, and uncorrelated background noise. Providing evidence that higher order modes and multi-reflected signals behave like sets of correlated noise, this work uses a regression model to optimize residual complexity in the presence of both correlated and uncorrelated noise. This optimized residual complexity (ORC) is highly robust since it takes into account both the level and complexity of noise. The lower complexity of the dispersive modes and multiple reflections, compared to the complexity of the plane mode, points to the robustness of ORC against multiple reflections and dispersion. Experimental investigations using recorded sounds of gas leaking from a pipe confirm the robustness of ORC against multiple reflections. Numerical simulations also show robustness against dispersive modes, even when they disturb the linearity of the cross-spectrum phase. Comparisons with other methods-mutual information, cross correlation, and residual complexity-underline the general advantages of ORC in terms of robustness in the presence of reflection and dispersion, against both correlated and uncorrelated noise, and to short signals.

PLC-based mode multi/demultiplexers for mode division multiplexing

Abstract Recently developed PLC-based mode multi/demultiplexers (MUX/DEMUXs) for mode division multiplexing (MDM) transmission are reviewed. We firstly show the operation principle and basic characteristics of PLC-based MUX/DEMUXs with an asymmetric directional coupler (ADC). We then demonstrate the 3-mode (2LP-mode) multiplexing of the LP01, LP11a, and LP11b modes by using fabricated PLC-based mode MUX/DEMUX on one chip. In order to excite LP11b mode in the same plane, a PLC-based LP11 mode rotator is introduced. Finally, we show the PLC-based 6-mode (4LP-mode) MUX/DEMUX with a uniform height by using ADCs, LP11 mode rotators, and tapered waveguides. It is shown that the LP21a mode can be excited from the LP11b mode by using ADC, and the two nearly degenerated LP21b and LP02 modes can be (de)multiplexed separately by using tapered mode converter from E13 (E31) mode to LP21b (LP02) mode.

Solar seeing monitor MISOLFA: A new method for estimating atmospheric turbulence parameters

Daily observation conditions are needed when observing the Sun at high angular resolution. MISOLFA is a daytime seeing monitor developed for this purpose that allows the estimation of the spatial and temporal parameters of atmospheric turbulence. This information is necessary, for instance, for astrometric measurements of the solar radius performed at Calern Observatory (France) with SODISM II, the ground-based version of the SODISM instrument of the PICARD mission. We present a new way to estimate the spatial parameters of atmospheric turbulence for daily observations. This method is less sensitive to vibrations and guiding defaults of the telescope since it uses short-exposure images. It is based on the comparison of the optical transfer function obtained from solar data and the theoretical values deduced from the Kolmogorov and Von Ka`rma`n models. This method, previously tested on simulated solar images, is applied to real data recorded at Calern Observatory in July 2013 with the MISOLFA monitor. First, we use data recorded in the pupil plane mode of MISOLFA and evaluate the turbulence characteristic times of angle- of-arrival fluctuations: between 5 and 16 milliseconds. Second, we use the focal plane mode of MISOLFA to simultaneously record solar images to obtain isoplanatic angles: ranging from 1 to 5 arcseconds (in agreement with previously published values). These images and our new method allow Fried’s parameter to be measured; it ranges from 0.5 cm to 4.7 cm with a mean value of 1.5 cm when Kolmogorov’s model is considered, and from less than 0.5 to 2.6 cm with a mean value of 1.3 cm for the Von Ka`rma`n model. Measurements of the spatial coherence outer scale parameter are also obtained when using the Von Karman model; it ranges from 0.25 to 13 meters with a mean value of 3.4 meters for the four days of observation that we analyzed. We found that its value can undergo large variations in only a few hours and that more data analysis is needed to better define its statistics.

Effects of Strong Turbulence on the Spiral Plane Mode of Whittaker–Gaussian Beam through Terrene-Atmosphere**Supported by the Fundamental Research Funds for the Central Universities under Grant No JUSRP51517, and the Graduate Student Research Innovation Project of Jiangsu-Province General University under Grant No KYLX15_1187.

The analytic formulae of probability distribution of spiral plane modes for the Whittaker–Gaussian (WG) beams with orbital angular momentum (OAM) in strong turbulence regime are modeled based on the modified Rytov approximation. Numerical results show that the crosstalk range of OAM modes in the vicinity of signal mode increases with the increasing refractive-index construction parameter. However, effects of change of the width of the Gaussian envelope and the parameter W0 of WG beams on normalization energy weight of signal mode can be ignored. We find theoretically that signal spiral plane mode of WG beams at each OAM level approximatively has the same normalization energy weight, implying that the channels with WG (pseudo non-diffraction) beam have higher channel capacity than the channels with the Laguerre–Gaussian beam.

Adaptive multimode signal reconstruction from time-frequency representations.

This paper discusses methods for the adaptive reconstruction of the modes of multicomponent AM–FM signals by their time–frequency (TF) representation derived from their short-time Fourier transform (STFT). The STFT of an AM–FM component or mode spreads the information relative to that mode in the TF plane around curves commonly called ridges. An alternative view is to consider a mode as a particular TF domain termed a basin of attraction. Here we discuss two new approaches to mode reconstruction. The first determines the ridge associated with a mode by considering the location where the direction of the reassignment vector sharply changes, the technique used to determine the basin of attraction being directly derived from that used for ridge extraction. A second uses the fact that the STFT of a signal is fully characterized by its zeros (and then the particular distribution of these zeros for Gaussian noise) to deduce an algorithm to compute the mode domains. For both techniques, mode reconstruction is then carried out by simply integrating the information inside these basins of attraction or domains.

Effect of chamfering of cable clamp plate on shear behaviour of CFRP tendons

The use of carbon fibre reinforced polymer (CFRP) tendons instead of steel tendons is a promising method for improving the overall performance of beam string structures. However, research on the shear behaviour of CFRP tendons is insufficient. In this paper, the effect of chamfering of the cable clamp plate used in the connected joint between prestressed tendons and struts for beam string structures on the shear behaviour of CFRP tendons was analyzed. The transverse shear tests were conducted on 5-mm-, 7-mm- and 9-mm-diameter transverse enhanced CFRP tendons to investigate the effect of chamfering. Experimental results show that the chamfering increased the transverse shear strength of 7-mm-diameter CFRP tendons significantly (approximately 15%) and slightly (approximately 0–3%) improved the shear strength of the 5-mm- and 9-mm-diameter tendons. The transverse shear deformation of the three diameters of CFRP tendons increased by 35%, 77% and 92% compared with no chamfering effect. Another important result is that the mechanical mechanism and failure mode of shear plane for all specimens were changed by the chamfering. Complete cross-section fracture on the shear plane of CFRP tendons has not occurred, and the tendons can still have some transverse bearing capacity after shear failure.

The Research of Influence of Cold Rolling Conditions on Mechanical Properties Anisotropy of Sheets from Aluminum Alloy 8011A

The study results of the influence research of reduction ratio in cold rolling on the anisotropy of mechanical properties of sheets from aluminum alloy 8011A are shown in this article. It was determined that the effect of cold rolling on various mechanical properties is different. However, for all characteristics were usual to change the distribution mode and variance reduction in sheet plane during the high ratios of deformation. At the 85-90% reduction ratio it is observed the leveling of mechanical properties in sheet plane.

Formation of single-mode laser in transverse plane of perovskite microwire via micromanipulation.

The synthesized perovskites are randomly distributed and their optical properties are fixed after synthesis. Here we demonstrate the tailoring of lasing properties of perovskite microwire via micromanipulation. One microwire has been lifted by a tungsten probe and repositioned on a nearby perovskite microplate with one end suspended in air. Consequently, the conventional Fabry-Perot lasers are completely suppressed and a single laser peak has been observed. The numerical calculations reveal that the single-mode laser is formed by the whispering-gallery mode in the transverse plane of microwire. Our research provides a simple way to tailor the properties of microwire postsynthesis.

Analysis of tunnel hydrodynamic characteristics for planing trimaran by model tests and numerical simulations

The planing trimaran hull has unique hydrodynamic performance due to the tunnel region. In this paper, results of experimental and numerical studies for the planing trimaran hull are presented to analyze the hydrodynamic characteristics of tunnel and its effect on the hull body. Model tests were carried out for volume based Froude number ranging from 0.90 to 5.87. Resistance, sinkage and trim angle obtained by towing tank show that the planing trimaran has poor resistance performance at the hump region, while it operates quite well in the planing mode. A three dimensional computational fluid dynamic (CFD) code based on the Finite Volume Method (FVM) was used to simulate the forward motion of the hull body with two degrees of freedom (heave and pitch) when Froude number is above 3.16. Calculated results were validated with the experimental data and showed good agreement. Wave profile, dynamic lift, longitudinal center of pressure and flow vectors in the tunnel region at various Froude numbers were provided to explain the hydrodynamic and aerodynamic mechanism of this region. At last, models with different tunnel height and beam were calculated to study the influence of tunnel configuration on hull behaviors and hydrodynamic performance.

Crack Front Segmentation and Facet Coarsening in Mixed-Mode Fracture.

A planar crack generically segments into an array of "daughter cracks" shaped as tilted facets when loaded with both a tensile stress normal to the crack plane (mode I) and a shear stress parallel to the crack front (mode III). We investigate facet propagation and coarsening using insitu microscopy observations of fracture surfaces at different stages of quasistatic mixed-mode crack propagation and phase-field simulations. The results demonstrate that the bifurcation from propagating a planar to segmented crack front is strongly subcritical, reconciling previous theoretical predictions of linear stability analysis with experimental observations. They further show that facet coarsening is a self-similar process driven by a spatial period-doubling instability of facet arrays.

Multi-modal vibration amplitudes of taut inclined cables due to direct and/or parametric excitation

Cables are often prone to potentially damaging large amplitude vibrations. The dynamic excitation may be from external loading or motion of the cable ends, the latter including direct excitation, normally from components of end motion transverse to the cable, and parametric excitation induced by axial components of end motion causing dynamic tension variations. Geometric nonlinearity can be important, causing stiffening behaviour and nonlinear modal coupling. Previous analyses of the vibrations, often neglecting sag, have generally dealt with direct and parametric excitation separately or have reverted to numerical solutions of the responses. Here a nonlinear cable model is adopted, applicable to taut cables such as on cable-stayed bridges, that allows for cable inclination, small sag (such that the vibration modes are similar to those of a taut string), multiple modes in both planes and end motion and/or external forcing close to any natural frequency. Based on the method of scaling and averaging it is found that, for sinusoidal inputs and positive damping, non-zero steady state responses can only occur in the modes in each plane with natural frequencies close to the excitation frequency and those with natural frequencies close to half this frequency. Analytical solutions, in the form of non-dimensional polynomial equations, are derived for the steady state vibration amplitudes in up to three modes simultaneously: the directly excited mode, the corresponding nonlinearly coupled mode in the orthogonal plane and a parametrically excited mode with half the natural frequency. The stability of the solutions is also identified. The outputs of the equations are consistent with previous results, where available. Example results from the analytical solutions are presented for a typical inclined bridge cable subject to vertical excitation of the lower end, and they are validated by numerical integration of the equations of motion and against some previous experimental results. It is shown that the modal interactions and sag (although very small) affect the responses significantly.

Investigation of spatial resolution characteristics of an in vivo microcomputed tomography system

The spatial resolution characteristics of an in vivo microcomputed tomography (CT) system was investigated in the in-plane (x–y), cross plane (z) and projection imaging modes. The microCT system utilized in this study employs a flat panel detector with a 127µm pixel pitch, a microfocus x-ray tube with a focal spot size ranging from 5–30µm, and accommodates three geometric magnifications (M) of 1.72, 2.54 and 5.10. The in-plane modulation transfer function (MTF) curves were measured as a function of the number of projections, geometric magnification (M), detector binning and reconstruction magnification (MRecon). The in plane cutoff frequency (10% MTF) ranged from 2.31lp/mm (M=1.72, 2×2 binning) to 12.56lp/mm (M=5.10, 1×1 binning) and a bar pattern phantom validated those measurements. A slight degradation in the spatial resolution was observed when comparing the image reconstruction with 511 and 918 projections, whose effect was visible at the lower frequencies. Small value of MRecon has little or no impact on the in-plane spatial resolution owning to a stable system. Large value of MRecon has implications on the spatial resolution and it was evident when comparing the bar pattern images reconstructed with MRecon=1.25 and 2.5. The cross plane MTF curves showed that the spatial resolution increased as the slice thickness decreased. The cutoff frequencies in the projection imaging mode yielded slightly higher values as compared to the in-plane and cross plane modes at all the geometric magnifications (M). At M=5.10, the cutoff resolution of the projection and cross plane on an ultra-high contrast resolution bar chip phantom were 14.9lp/mm and 13–13.5lp/mm. Due to the finite focal spot size of the x-ray tube, the detector blur and the reconstruction kernel functions, the system׳s spatial resolution does not reach the limiting spatial resolution as defined by the Nyquist׳s detector criteria with an ideal point source. The geometric magnification employed in the microCTs provide a tradeoff between field of view and spatial resolution for a wide range of applications.

Research of small spacecraft dynamiсs taking into account the influence of elastic vibrations of asjacent solar panels and aerodynamic moment

The article presents the analysis of the dynamics of small spacecraft (SS) with affixed solar panels which have a certain degree of elasticity due to their construction. A mathematical model of spacecraft disturbed motion during the boost phase is formed which takes into account the body elasticity and the presence of liquid filling. A finite-dimensional system of equations of SS elastic disturbed motion is formed in the process of constructing the model taking into account power dissipation. The issues of elastic vibrations that appear after the dynamic operations connected with SS re-orientation or reconstruction of some of its elements are discussed. Research has been conducted using a modeling complex to estimate the influence of elastic vibrations of the SS structure on the precision and dynamic characteristics of the control system such as the analysis of transition process duration and maximum amplitude of variations of the measured value of SS angular velocity. Dependences of SS angular speed on time have been obtained. The analysis of the results obtained shows that elastic vibrations of the SS structure have a strong impact on spacecraft dynamics in the spinning mode. It is noted that the vibrations in the pitch channel are the most crucial, It is there that vibrations out of the panel plane and twist modes relative to the symmetry axis of opened panel flaps take place in the nominal position of solar panels. Moreover, spacecraft motion during the process of its separation from the space rocket is discussed taking into account the influence of small aerodynamic moment.