XY Direction Research Articles

Effect of matrix-alloying-element chromium on the microstructure and properties of graphite flakes/copper composites fabricated by hot pressing sintering

Copper matrix composites reinforced with graphite flakes (GFs/Cu) were fabricated by powder hot pressing method and the alloying chromium (Cr) element in powdered form was directly added into the Cu matrix powder to enhance the interfacial bonding between GFs and Cu matrix. Effects of addition of Cr on thermal conductivity (TC), coefficient of thermal expansion (CTE), and bending strength of GFs/Cu composites in XY (basal plane of GF) and Z directions were investigated in this study. The results showed that in XY direction, the TC of 50 vol% GFs/Cu composites increased from 560 to 628 W m−1 K−1 after adding 2.0 wt% Cr, and the bending strength nearly doubled from 53.8 (GF/Cu) to 93 MPa. The CTE in Z direction could be obviously reduced with Cr addition, which dropped gradually from 9.4 to 3.2 ppm K−1 at 150 °C with the increase in content of Cr from 0 to 5.0 wt%. This improvement in TC, bending strength, and CTE is attributed to the formation of carbide transition layer at the interface between Cu and graphite. The detailed influence of carbide layer on the properties of the composites was thoroughly studied by corresponding evolution of interfacial microstructure with increasing Cr content.

Depth compensating calculation method of computer-generated holograms using symmetry and similarity of zone plates

Computer-generated hologram (CGH) is a promising 3D display technology while it is challenged by heavy computation load and vast memory requirement. To solve these problems, a depth compensating CGH calculation method based on symmetry and similarity of zone plates is proposed and implemented on graphics processing unit (GPU). An improved LUT method is put forward to compute the distances between object points and hologram pixels in the XY direction. The concept of depth compensating factor is defined and used for calculating the holograms of points with different depth positions instead of layer-based methods. The proposed method is suitable for arbitrary sampling objects with lower memory usage and higher computational efficiency compared to other CGH methods. The effectiveness of the proposed method is validated by numerical and optical experiments.

Influence of fabric architecture on compressive and failure mechanism of Cf/Mg composite fabricated by LSEVI

Four kinds of Cf/Mg composites with different fabric architectures were fabricated by liquid–solid extrusion following vacuum infiltration (LSEVI) technique. The influence of fabric architecture on compressive properties of Cf/Mg composites was investigated, and the microstructure and failure surfaces were examined by SEM. The results showed that Cf/Mg composites were anisotropic material and the fabric architecture had great influence on their compressive performance. Moreover, fabric crimp had a negative influence on compressive properties of Cf/Mg composite. The composite with non-woven carbon fabric perform had the highest compressive strength (XY direction). Compared with 3K plain-woven carbon cloth composite whose fiber bundles had 3000 monofilaments, 1K plain-woven carbon cloth composite had better compressive properties. The analysis of failure surface indicated that the failure modes of Cf/Mg composites were mainly shear failure and delamination failure.

Reflecting microscope system with a 0.99 numerical aperture designed for three-dimensional fluorescence imaging of individual molecules at cryogenic temperatures.

We have developed a cryogenic fluorescence microscope system, the core of which is a reflecting objective that consists of spherical and aspherical mirrors. The use of an aspherical mirror allows the reflecting objective to have a numerical aperture (NA) of up to 0.99, which is close to the maximum possible NA of 1.03 in superfluid helium. The performance of the system at a temperature of 1.7 K was tested by recording a three-dimensional fluorescence image of individual quantum dots using excitation wavelengths (λex) of 532 nm and 635 nm. At 1.7 K, the microscope worked with achromatic and nearly diffraction-limited performance. The 1/e2 radius (Γ) of the point spread function of the reflecting objective in the lateral (xy) direction was 0.212 ± 0.008 μm at λex = 532 nm and was less than 1.2 times the simulated value for a perfectly polished objective. The radius Γ in the axial (z) direction was 0.91 ± 0.04 μm at λex = 532 nm and was less than 1.4 times the simulated value of Γ. The chromatic aberrations between the two wavelengths were one order of magnitude smaller than Γ in each direction.

Lightweight carbon-bonded carbon fiber composites with quasi-layered and network structure

Abstract Lightweight carbon-bonded carbon fiber (CBCF) composites were fabricated with chopped carbon fibers and dilute phenolic resin solution by pressure filtration, followed by carbonization at 1000 °C in argon. The as-prepared CBCF composites had a homogenous fiber network distribution in xy direction and quasi-layered structure in z direction. The pyrolytic carbon derived from phenolic resin was mainly accumulated at the intersections and surfaces of chopped carbon fibers. The composites possessed compressive strengths ranged from 0.93–6.63 MPa in xy direction to 0.30–2.01 MPa in z direction with a density of 0.162–0.381 g cm − 3 . The thermal conductivity increased from 0.314–0.505 to 0.139–0.368 Wm − 1 K − 1 in xy and z directions, respectively. The experimental results indicate that the CBCF composites prepared by this technique can significantly contribute to improve the thermal insulation and mechanical properties at high temperature.

Mechanism of original damage of thin optical components induced by surface particle contamination

Based on the optical transmission theory, the reason why front-surface particle contamination may induce the original damage of thin optical components is considered, and a damage mechanism is put forward: The localized thermal deformation of an optical element induced by the thermal effect of particle contamination together with the shading effect of it can disturb the laser beams. Simulated results show that for a high power laser, the localized thermal deformation of thin optical components, which disturbs the laser beam, is an important cause to produce strong light intensity modulations. The surface shape, phase delay, and thermal diffusion length of a localized thermal deformation are constantly changing with the increase of laser pulse shot number, so the highest light intensity modulation will be produced at different positions in the thickness direction or the xy direction on the rear-surface of an optical element. This not only can easily induce some damages on the rear-surface of the optical element, but also cause the interior damages scattered in the thickness direction.

Study on Process and Properties of Needling Silica Fiber Reinforced Silica Composites

With the development of military weapons, the demand of weapons is growing. But now 2.5 D silica fiber reinforced silica composites have long production period, high cost,which limited the production and schedule of weapons. This paper studied low cost manufacturing technology from two aspects of fiber preform weaving mode and molding process. The preforms were prepared with needling process.CT images of needling preform, thermophysical properties and mechanical properties and dielectric properties of needling silica fiber reinforced silica composites were studied inthis paper.The results showed that needling SiO2f/SiO2 composites had short production period and low cost, which had good mechanical properties.Tensile strength was 20.1MPa, compressive strength of XY direction was 88.3MPa,bending strength was 52.2MPa. Dielectric contant was less than 3.05 and dielectric loss was less than 8×10-3.

Influence of heat treatment temperature on microstructure and thermal expansion properties of 2D carbon/carbon composites

The influence of heat treatment from 1900 to 2650 °C on microstructure and thermal expansion properties of thermal gradient chemical vapor infiltration (TCVI)-infiltrated 2D carbon/carbon composites was investigated. The structure evolution was characterized by polarized light microscopy, X-ray diffractometer, Raman spectroscopy and thermal expansion behavior was studied by thermal dilatometer. The results revealed that with the increasing heat treatment temperature, successive microstructural changes in carbon matrix and fibers occurred, and cracks and pores in the composites increased. These resulted in a 35.6% decrease of CTE in Z direction and a 13.9% decrease in XY direction in the composites heat-treated at 2650 °C compared with as-deposited composites. The CTE mainly depended on the thermal expansion of matrix in Z direction while it relied on that of the fibers in XY direction.

Simulation on Roadheader Rear Supporting Leg Vibration Moulding

Using three-dimensional discrete element method (DEM) to simulate the vibration of the evaporated pattern casting molding process, accordingly summary the influence law of vibration direction effecting on dry sand filling. The results show that the 3DOF vibration filling effect is best, 2DOF takes second place, 1DOF is the worst. In the 2DOF vibration the YZ direction is best, XY direction worst. Meanwhile Y direction vibration works best in 1DOF vibration, second is X direction, and Z direction gets worst.

Novel design for an ultra high precision 3D micro probe for CMM applications

The paper reports on the design and testing of several new piezoresistive ultra high precision 3D microprobes for the use in coordinate measuring machines (CMM). The microprobes are all composed of three primary components a piezoresitive sensing element and stylus with probing sphere. The sensing element consists of a bossed KOH-etched silicon membrane with diffused piezoresistors. Several designs were investigated to increase sensor sensitivity while improving the anisotropy of stiffness. The initial design used a Wheatstone bridge piezoresistor configuration with a solid sensing membrane. Additionally, apertures where added to the solid silicon membrane to increase stress within the piezoresistors which untimely led to higher probe tip sensitivity. To improve the stiffness in the xy direction of the probe tip a double triangle design was tested that bonded two sensor chips back to back. This was found reduce the ratio between the stiffness in xy- and z-direction from 32 initially to 2.

Electrostatic rotator for alignment purposes in multi electron beam systems

In single charged particle beam column the alignment is obtained either by mechanical shift of the lenses or by XY alignment deflectors. The problem in multi beam array systems is that it is only possible to deflect the array of beams in the XY direction and not able to correct for a possible rotation errors between arrays blocks. A new concept is presented here that can electro statically align multi beam array systems.

Monte Carlo Modeling of Light Scattering in Paper

The theory of radiation transmission describes the interaction of radiation with the medium which scatters and absorbs the light. The solutions of radiation transport, which were obtained during the previous century, have been applied on the broad fan of problems from neutron diffusion, optical tomography, spreading of infra-red and visible light in atmosphere to paper and prints. At the beginning the majority of problems of radiation transport were unbeatable, but with the improvement of mathematical tools and approximations, and the computers become quicker and powerful the solutions become more specialized and effective. The first approximate solution was given by Schuster (1905) who presumed in the solution the radiation in only forward and backward direction. Under this influence Kubelka and Munk (1931) have developed their well known model. The original Kubelka-Munk theory was developed for spreading the light in parallel colored layers boundlessly extended in xy direction (Kubelka , Emmel ) (in order to avoid the problems connected with the boundary conditions). The basic assumption of Kubelka-Munk theory is that the layer is uniform and the light distribution within the layer is diffuse. From these assumptions the transport of light in the layer was simplified

High‐Rate SiO2 Deposition by Oxygen Cold Arc Plasma Jet at Atmospheric Pressure

AbstractSiO2 thin films were deposited by a cold arc plasma jet at atmospheric pressure. The cold arc plasma jet was operated with O2 gas of 30 L · min−1, while a He/TEOS mixture of 1 000 sccm was added to the plume of the plasma jet as a precursor. The plasma jet was continuously moved in the xy direction for uniform film thickness. The deposition rate at various conditions was studied by controlling the substrate distance, precursor inlet position, and substrate temperature; the physical and chemical properties of the films were characterized by SEM and XPS. A high deposition rate was attained using the cold arc plasma jet deposition system in open air; it is suggested that this originates from the abundant oxygen atoms produced in the cold arc plasma jet.magnified image

Dynamically Corrected Transition State Theory Calculations of Self-Diffusion in Anisotropic Nanoporous Materials

We apply the dynamically corrected transition state theory to confinements with complex structures. This method is able to compute self-diffusion coefficients for adsorbate-adsorbent systems far beyond the time scales accessible to molecular dynamics. Two example cage/window-type confinements are examined: ethane in ERI- and CHA-type zeolites. In ERI-type zeolites, each hop in the z direction is preceded by a hop in xy direction and diffusion is anisotropic. The lattice for CHA-type zeolite is a rhombohedral Bravais lattice, and diffusion can be considered isotropic in practice. The anisotropic behavior of ERI-type cages reverses with loading, i.e., at low loading the diffusion in the z direction is two times faster than in the xy direction, while for higher loadings this changes to a z diffusivity that is more than two times slower. At low loading the diffusion is impeded by the eight-ring windows, i.e., the exits out of the cage to the next, but at higher loadings the barrier is formed by the center of the cages.

Theoretical Analysis and Basic Experiments for the 3D Displacement Measurement Using Ring-Shaped Laser Beam

For flexible 3D positioning of a complex 3D mechanism, it is needed to measure 3D displacement of the end-effecter of the mechanism in high precision and by non-contact method. It was common to use plural sensors or scales together to measure the 3D displacement. However, it is difficult to calibrate the sensitivities of the plural sensors or scales. A novel 3D displacement measurement is proposed using an optical system in which lens focuses are collected at the center of the sphere, which has been used for the radius measurement of the sphere. Instead of facing in the XY direction that has high sensitivity, new ideas are necessary for the measurement in the Z direction of the optics where focuses are collected at the center of the sphere. The displacement in the XY direction and the one in the Z direction can be measured at the same time by using a ring-shaped laser beam instead of a simple ray.

リングビームを用いた三次元変位測定法（第１報）―理論解析と基礎実験―

For three dimensional positioning of a complex three dimensional mechanism flexibly, it is needs to measure three dimensional displacement of an end-effecter of the mechanism in the high precision by non-contact method. It was common to put the plural sensor or scale together and to measure the three dimensional displacement of the mechanism. However, it is difficult to calibrate positions and sensitivities of the plural sensor or scale. Therefore, the novel three dimensional displacement measuring method is proposed using the optics that focus is collected in the center of the spherical target which has been used for the radius measurement of the ball. Instead of high sensitivity on measuring in the XY direction, new ideas are necessary for the measurement in the Z direction in this optics. Therefore, a ring beam is used instead of the simple ray for Z direction measurement. The theoretical examination and simulation of the three dimensional displacement measurement using the ring beam are done and that validity is confirmed by the series of the experiments.

P‐30: Fine Patterning of Lateral Three Color Emitters for Organic EL Devices Using a Metal Mask Sliding in Vacuum Vapor Deposition

AbstractIn order to form high‐resolusion pixels for a small organic elctroluminescent (EL) device having a three‐color independent emission system using a low molecular evaporation method, a metal mask sliding control system with a pulse control motor was made for the initial trials. This system has a substrate holding table which has the functions of rotation angle adjustment, adjustment of the XY direction movements, adjustment of the Z direction movements and an XY stage for a metal mask sliding which is based on the leaf spring structure. The patterning of the RGB thin films was done by precisely controlling the position of the XY stage for a metal mask sliding using a DC servomotor. An organic EL device, which has the sub‐pixel pitch of 33 μm × 100 μm, aperture ratio of 70% and 254 ppi (pixel/inch), has been manufactured using this system.

Accuracy of stereotactic coordinate transformation using a localisation frame and computed tomographic imaging

The accuracy of coordinate transformation from a CT image to a stereotactic frame was investigated for stereotactic systems using a localisation frame and matrix-based coordinate transformation. The main source of error influencing calculation was input data, due to inaccurate calculation of the centres of the rods of the localisation frame in the CT image, and the propagation of this input error during subsequent matrix calculation. Systemic errors during matrix calculation do not exist, and rounding off errors were of subordinate importance compared to the input data error. The influence of input data error on coordinate transformation was studied by geometric methods, computer simulation, and numerical analysis. In the geometric model, input data errors affected the calculation of the centres of the three oblique rods in the frame space and shifted them three points upwards or downwards on the axis of each rod. The three centres of the oblique rods defined the "CT plane" in the 3D space of the stereotactic frame. Displacements of these three centres caused a characteristic tilting of the CT plane. The positions of the correct and tilted CT planes defined the spatial error properties for all target points on the CT plane. The computer simulation investigated the effects on matrix-based transformation of all possible displacement combinations on the three oblique rods by 1 pixel (1. 16 mm) in the x and y directions. A characteristic, space-dependent distribution of the frame-related coordinates was obtained for each target point. In the centre of the frame, we found a maximal deviation of 1.0 mm in the xy direction and 2 mm in the z direction. This corresponded to an error amplification of 0.73 in the xy direction and 1.22 in the z direction relative to the error at the centres of the rods. The maximum deviation (found in the periphery) for all combinations on the three oblique rods was 1.7 mm in the xy direction and 3.3 mm in the z direction. This resulted in an amplification of 1.03 in the xy direction and 2.01 in the z direction. This results had to be multiplied by 2 to obtain a maximal error estimate for displacements including all nine rods of the localisation frame. Numerical analysis showed stable solutions with low error amplification for hexagonal frame arrangements.

Surface characterization of a rosin sizing agent in paper by means of EPMA, ESCA and TOF-SIMS

Abstract EPMA(e1ectronprobe micro analysis), ESCA (electron spectroscopy for chemical analysis) and TOF-SIMS (time of flight type secondary ion mass spectrometry) were used to detect the distribution of a rosin sizing agent in paper. For EPMA we labelled paper samples with osmium tetroxide which enabled the detection of rosin in the XY direction of the paper sheet. For ESCA we labelled paper samples with fluorine which also enabled the detection of rosin. At the same time, the ESCA angle-dependent technique was used to obtain depth profiles of the rosin. Also, distribution images of rosin on an extremely thin ( 1 nm) surface layer were made observable by monitoring fragment ions from the rosin with TOF-SIMS. By using EPMA, a notable difference in rosin distribution was shown on the pulp fiber. However, according to the TOF-SIMS examination, the rosin was shown to be distributed relatively even in an extremely thin surface layer. The ESCA angle- dependent technique showed that rosin was present mainly on the outer surface layer.

Piezoelectric torsional actuator

Piezoelectric torsional actuators have been developed from single ceramic cylindrical bodies using PZT based high d constant piezoelectric ceramics. The actuator geometry is able to produce rotational motion directly by DC voltage control without conventional complex conversion from XY direction motions. The key feature of this actuator is the interdigital electrode on the outer surface of the cylinder at an angle of 45° from the length axis of the cylinder, and the design of this electrode is critical for adjusting torsional angle and driving voltage. When the cylinder wall thickness and the ratio between electrode width and pitch are kept constant, the rotational angle is approximately proportional to the electric field, i.e. the narrower electrode gap needs smaller driving voltage in order to obtain a certain rotational angle. Among the three different diameter samples tested, actual rotational displacements are the same under the same conditions. Therefore, the rotational angle is reversibly proportional to the diameter of the piezoelectric cylinder.