The reaction process of the Bi-Sr-Ca-Cu-O system and the forming mechanism of the 2212 superconducting phase

The reaction process and the reaction behavior of each component in the Bi-Sr-Ca-Cu-O system are presented in this paper. It reveals that the reaction is carried out in three different stages: forming of an insulating interphase at 680°C–790°C, forming of the 2212 superconducting phase at 790°C–860°C and forming often semiconducting phases in the presence of the liquid phase at 860°C–970°C. It is also confirmed that the 2212 superconducting phase (T _c=85 K) is formed by the reaction of a trinary interphase together with CuO, SrO and CaO. A new two-step method is presented to prepare the 2212 superconducting phase by a presynthesized interphase.     

Aberration athermal design for infrared search and trace optical system

To satisfy environment requirement of infrared search and trace optical system, an infrared diffractive/refractive hybrid optical system in 3.7–4.8 μm with 11.42° of field of view for passive athermalization is presented. The system is consisted of three lenses, including two aspheric surfaces and a diffraction surface, which has only two materials Ge and Si. The optical system has compact structure, small volume and light weight. The image quality of the system approaches the diffraction limit in the temperature range −80 °C to 160 °C. It is compatible with staring focal plane array which has a format of 320 × 240 and the pixel pitch of 30 μm. The system need not move the compensated lens repeatedly to obtain the best images from −80 °C to 160 °C and enhances the performance of target tracking and recognition.     

300～1100nm多波段成像光学系统设计及杂光分析

设计了一套300～1100nm多波段光学系统,该系统能对目标的近紫外、可见光和近红外3个波段同时成像,可满足目标多波段信息探测的要求。由于在光学系统中镜筒内壁反射和棱镜表面反射会产生杂光和鬼像,因此,利用Light—Tools软件对此系统的杂光和鬼像进行了模拟分析。模拟结果表明,视场之外11．7—18．3°和-11．7～-18．3°的入射光线被胶合棱镜上下表面反射后,会聚焦到3个探测器靶面范围内,形成鬼像;6．2°-9．8°和一6．2°--9．8°的入射光线被镜筒反射后会在3个探测器上形成杂光。利用设计的多波段光学系统进行了相关实验,结果证明了模拟分析的正确性,表明此分析能用于指导多波段光学系统的设计和研制。提出了减少杂光和鬼像的相应措施,实验结果验证了提出的措施能够减少杂光及消除鬼像,提高系统成像质量。     

Effect of surface lay in the surface roughness evaluation using machine vision

This work explores the influence of orientation of surface lay pattern of the machined components, while quantifying the surface roughness using machine vision approach. The surface images are captured from milled low carbon steel specimens with different roughness values using a vision system with coaxial lighting arrangement at different angular orientations of the work pieces (0°, 30°, 45°, 60°, 90°, 120°, 135°, 150°, and 180°). The captured images are subjected to preprocessing in order to retain the frequency components that attribute to roughness using a Gaussian filter by adapting the filtering procedures specified in ISO 4288. Numerous image based parameters such as gray level average (G_a), gray level co-occurrence matrix based image quantification parameters namely contrast, correlation, energy or uniformity, maximum probability and differential box courting based fractal dimension are computed from the surface images captured at different angular positions of the work piece. The computed vision based parameters are compared and correlated with the roughness average (R_a) obtained using a stylus instrument and the results are analyzed. The results clearly indicated that it is important to consider the orientation of the work piece when the machine vision approach is used to quantify the surface texture parameters.     

Temperature dependence of the stability of written bits in a magnetic hard-disk medium investigated by magnetic force microscopy

The thermal stability of written bits in a magnetic hard-disk medium has been investigated with a magnetic force microscope (MFM), which was equipped with an in situ heating system capable of heating the medium up to 300 °C. It is shown that both the annealing temperature and the duration have significant effect on the decay of the MFM signal. No signal decay is observed when annealing for 30 min up to temperatures of 200 °C. The MFM signal decays rapidly with increasing temperature, for temperatures over 200 °C. Repeated annealing at 280 °C with a duration below 10 min does not cause any signal decay.     

Design and verification of LSR module in laser display

The LSR module of optical engine in laser display has been designed and discussed in this paper. It has also been tested and verified with the scattering sheet of 5°, 10° and 20°. The experiment demonstrates that the method of rotating the scattering sheet with 10° can effectively suppress laser speckle in our system. It can make the speckle contrast of large power projection system drop to 4.2% < 5%, which reaches the acceptable range of the human eyes.     

Mutual diffusion in the titanium-vanadium-niobium system

Mutual diffusion is investigated in the Ti-V-Nb system at 1000 and 1200°C. A computation is performed by the Matano-Kirkaldy method for 89 points of an isothermal section at 1200°C and 101 points at 1000°C. Niobium was selected as solvent. It is found that the diagonal mutual diffusion coefficients grow by almost two orders as the composition approaches the titanium angle. Nondiagonal coefficients take on both positive and negative values.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 10, pp. 86–91, October, 1985.     

Phase relations and transformations in the system PbTe-GeTe

Results of a study of the pseudobinary system PbTe-GeTe are reported and discussed. A new phase diagram, the dependence of the lattice constants on alloy composition, and measurements of a phase transformation in Pb_1−xGe_xTe are presented. Complete solid solubility is found above 570°C. An exsolution dome extends from a maximum at 570°C (near 60 mole % GeTe) to about 5 and 96 mole % GeTe at 300°C. For alloys with compositions near GeTe the unit cell parameters depend markedly on the concentration of cation vacancies. The temperature for the cubic to trigonal phase transformation depends on alloy composition, decreasing from about 670°K for x = 1 to 0°K for x ≈ 0·01. The variation of lattice parameters at the transition temperature is continuous within experimental precision.     

Effect of the heat treatment on the infrared emissivity of indium tin oxide (ITO) films

Indium tin oxide (ITO) films were deposited on glass substrates at temperatures ranging from 100 °C to 400 °C by direct current magnetron sputtering. The mean infrared emissivities at the waveband of 8-14 μm were measured in process of heating and cooling between room temperature and 350 °C. Microstructure and phases of ITO films before (Group A) and after (Group B) heat treatment were characterized by SEM and XRD, respectively. Electrical properties were characterized with a four-point probe method and by Hall measurement system. During heat treatment, the infrared emissivity of the film increases with the increase of temperature, and decreases with the decrease of temperature. While, the infrared emissivity of the films decreases slightly around 250 °C in heating process. On the other hand, after heat treatment, the crystalline phases of the films have no obvious change. However, both the resistivity and the infrared emissivity of all films decrease.     

Energy monitoring and analysis during deformation of bedded-sandstone: Use of acoustic emission

This paper investigates the mechanical behaviour and energy releasing characteristics of bedded-sandstone with bedding layers in different orientations, under uniaxial compression. Cylindrical sandstone specimens (54 mm diameter and 108 mm height) with bedding layers inclined at angles of 10°, 20°, 35°, 55°, and 83° to the minor principal stress direction, were produced to perform a series of Uniaxial Compressive Strength (UCS) tests. One of the two identical sample sets was fully-saturated with water before testing and the other set was tested under dry conditions. An acoustic emission system was employed in all the testing to monitor the acoustic energy release during the whole deformation process of specimens. From the test results, the critical joint orientation was observed as 55° for both dry and saturated samples and the peak-strength losses due to water were 15.56%, 20.06%, 13.5%, 13.2%, and 13.52% for the bedding orientations 10°, 20°, 35°, 55°, and 83°, respectively. The failure mechanisms for the specimens with bedding layers in 10°, 20° orientations showed splitting type failure, while the specimens with bedding layers in 55°, 83° orientations were failed by sliding along a weaker bedding layer. The failure mechanism for the specimens with bedding layers in 35° orientation showed a mixed failure mode of both splitting and sliding types. Analysis of the acoustic energy, captured from the acoustic emission detection system, revealed that the acoustic energy release is considerably higher in dry specimens than that of the saturated specimens at any bedding orientation. In addition, higher energy release was observed for specimens with bedding layers oriented in shallow angles (which were undergoing splitting type failures), whereas specimens with steeply oriented bedding layers (which were undergoing sliding type failures) showed a comparatively less energy release under both dry and saturated conditions. Moreover, a considerable amount of energy dissipation before the ultimate failure was observed for specimens with bedding layers oriented in shallow angles under both dry and saturated conditions. These results confirm that when rock having bedding layers inclined in shallow angles the failures could be more violent and devastative than the failures of rock with steeply oriented bedding layers.     

A temperature sensor based on optical microfiber knot resonator

A type of compact temperature sensor based on microfiber knot resonator is proposed and demonstrated experimentally. The microfiber knot, which is assembled by two fiber probes, is placed on a plate glass substrate and coated with low-index polymer to keep the system robust. Sensitivities of this kind of temperature sensor as 0.27 nm/°C in heating process (when temperature ranges from 28 to 140 °C) and −0.28 nm/°C in cooling process (when temperature ranges from 135 to 25 °C) are obtained. Temperature resolution of 0.5 °C is demonstrated and higher resolution is predicted with a high-resolution spectrometer.     

Study of the spectra of fast deuterons produced in the interaction of 670 MeV protons with nuclei

The spectra of deuterons emitted at angles of 6.5°, 9.5°, 13.5° and 16° (lab system) in the interaction of protons with the nuclei ¹H, ²H, ⁶Li, ⁷Li, C, Al, Cu, Rh and Pb have been measured in the momentum range 700–1700 MeV/c. The secondary particles were analyzed with the help of magnetic and time-of-flight spectrometers. The differential cross sections for deuteron production in the reactions p + 〈2N〉 → N + d and p + 〈N〉 → d + π have been measured for selected nuclei and angles. The effective numbers of nucleons and of two-nucleon clusters for the investigated nuclei were determined. The results obtained are discussed in terms of the dispersion theory of direct nuclear reactions.     

A phase quadrature interferometer for measuring the small optical rotation angle of a chiral medium

The passage of a linearly polarized beam through a chiral material and a phase retarder will induce a phase difference between the s and p polarizations of the beam. In this study, a phase quadrature interferometer is designed to measure the phase difference variation proportional to the optical rotation. The proportionality constant (or measurement sensitivity) can be greatly enhanced by setting the retardation of the phase retarder close to 0° or 180°. The experimental results demonstrate that with our system we can obtain a measurement resolution for the rotational angle of better than 3.5° × 10⁻⁴. This method has several advantages such as a simple optical setup, easier operation in real time, and low cost. In addition, due to the common-path arrangement, surrounding noise can be eliminated.     

Understanding the relationship between the structure of an organofunctional methoxysilane bilayer and its properties as adhesion primer for Zn-epoxidized rubber system

The structure of a new organofunctional methoxysilane bilayer system, which was found to improve the adhesion of epoxidized natural rubber (ENR) to zinc, is analyzed by High Resolution Electron Energy Loss and Infrared Reflection Absorption Spectroscopy. This bilayer is formed when zinc plate is successively dip-coated in water-alcohol solutions of γ-mercaptopropyltrimethoxysilane and aminopropyltrimethoxysilane. The optimal adhesion, obtained when both silane layers are cured at 110 °C, is due to the specific structure of this bilayer, which depends dramatically on the cure temperature of the first layer. From HREELS results under the conditions of an impact mechanism, it is shown that the surface density of NH₂ groups (which react with the epoxy groups of rubber and provide the adhesion of the whole system) is much higher when the γ-MPS layer is cured at 110 °C instead of 70 °C or room temperature. This high NH₂ group surface density is also confirmed by wettability measurements, which indicate a marked increase in the basic component of the surface energy at 110 °C. An IRRAS study of the γ-MPS layer deposited on zinc shows that up to 70 °C hydrolysis of the SiOCH₃ groups is poor, and becomes effective only after the zinc/γ-MPS layer is dipped in the basic APS solution. This makes the penetration of APS molecules across the γ-MPS layer easier and, consequently, amino groups can interact with zinc. Therefore, they are unavailable for a reaction with epoxy groups. In contrast, when the γ-MPS layer is cured at 110 °C or higher, hydrolysis of its SiOCH₃ groups begins and, simultaneously, lateral cross-linking occurs between SiOH groups. Under these conditions, penetration of the γ-MPS layer by APS molecules is hindered and lateral mixed cross-linking occurs at the interface γ-MPS/APS via the SiOH groups. This entails a greater density of pendant amino groups directed towards the surface, which enhances the practical adhesion of rubber to zinc.     

滤光片式双视场成像光谱仪光学系统设计

为了满足机载搜索与跟踪系统的实际使用要求,根据变焦系统的基本理论和成像光谱系统的特点,设计一个滤光片式双视场成像光谱仪光学系统实例。系统采用1/3英寸CCD接收,像元尺寸为6.0 m6.0 m。通过高斯法分析与求解得到初始结构,使用Zemax软件对其优化,实现0.45 m～0.7 m/0.6 m～0.95 m双波段清晰成像,通过轴向移动变倍组完成139.75/32.25双视场转换,在视场切换过程中,F数为5.6且恒定不变。设计结果表明:在各谱段下系统宽视场畸变3.5%,窄视场畸变0.2%,探测器的Nyquist频率50 lp/mm处光学传递函数的峰值均大于0.5,系统的最小后截距大于35 mm,用以安装滤光片轮,满足装配要求。     

Effects of copper on the thermoelectric performance parameter

Results are presented on conductivity, Hall effect, and thermo-emf for cadmium antimonide crystals containing 0.001–1% Cu in the range 90 ° to 380 ° K. The parameter z is calculated for the range 140 °–380 ° K for four concentrations.     

Influence of temperature variations on the entropy and correlation of the Grey-Level Co-occurrence Matrix from B-Mode images

In this work, the feasibility of texture parameters extracted from B-Mode images were explored in quantifying medium temperature variation. The goal is to understand how parameters obtained from the gray-level content can be used to improve the actual state-of-the-art methods for non-invasive temperature estimation (NITE). B-Mode images were collected from a tissue mimic phantom heated in a water bath. The phantom is a mixture of water, glycerin, agar-agar and graphite powder. This mixture aims to have similar acoustical properties to in vivo muscle. Images from the phantom were collected using an ultrasound system that has a mechanical sector transducer working at 3.5 MHz. Three temperature curves were collected, and variations between 27 and 44 °C during 60 min were allowed. Two parameters (correlation and entropy) were determined from Grey-Level Co-occurrence Matrix (GLCM) extracted from image, and then assessed for non-invasive temperature estimation. Entropy values were capable of identifying variations of 2.0 °C. Besides, it was possible to quantify variations from normal human body temperature (37 °C) to critical values, as 41 °C. In contrast, despite correlation parameter values (obtained from GLCM) presented a correlation coefficient of 0.84 with temperature variation, the high dispersion of values limited the temperature assessment.     

A LEED investigation of the chemisorption of nitrous oxide on a tungsten (100) surface

Nitrous oxide has been adsorbed on the tungsten (100) surface at 295 and 500°K. Flash desorption experiments show two binding states of nitrogen which desorb at 1005 and 1275°K. When both nitrogen states and the oxygen state from the dissociated nitrous oxide molecule are on the surface, there are no new LEED features. When the 1005°K nitrogen state is desorbed, a (4 × 1) LEED pattern occurs. When all the nitrogen is desorbed, a (2 × 1) oxide pattern remains. The oxygen is desorbed as a volatile tungsten oxide. A model of the sorbate surface which is consistent with the facts currently available on the nitrous oxide-tungsten system is described.     

Magnetite nanoparticles prepared by the glass crystallization method and their physical properties

Glass melts in the system Fe₂O₃/FeO/CaO/Na₂O/B₂O₃ were prepared from the raw materials, by firstly reducing them by flushing with nitrogen and subsequently roller quenching. The flakes obtained had a thickness of around 150 μm and were thermally treated at temperatures in the range from 550 to 620 °C. X-ray diffraction gave evidence of the occurrence of nanocrystalline magnetite. Magnetization measurements at room temperature show ferromagnetic behaviour and no hysteresis. Temperature-dependent measurements showed a monotonic decrease of the saturation magnetization with temperature, and a Curie temperature of 553 °C. The primary mean particle core diameter is around 10 nm after annealing at 570 °C.     

Alloying behavior at the AuGeNi/GaSb interface: Photoemission studies of the effects of annealing temperature

An ultra-thin AuGeNi alloy (84%/12%/4% by weight) overlayer of 5 nm was evaporated onto Te-doped n-type (100) oriented GaSb substrates. Samples were annealed in ultra-high vacuum (UHV), with a base pressure of 10^–10 Torr at either 300°C, 500°C, or 700°C for 12 h. The reacted interface was then revealed by Ar ion sputter-depth profiling. The highest percentage of Ge in the deep interface region was observed for the sample annealed at 500°C. Annealing at 500°C also leads to a uniform distribution of Ga, Sb, and Au concentrations. Results show that virtually all Au, Ge, and Ni evaporate away after annealing at 700°C. Au-based AuGa alloy formation was indicated by the shifts of Au 4f core-levels and the metallic Ga 3d peak. The small variation of Au 4f core-levels with sputtering for samples annealed at 500°C is the evidence of AuGa uniform alloying from the surface to the interface. It has been, therefore, concluded that annealing at 500°C forms a more uniform distribution of cluster size throughout the interface than annealing at 300°C or 700°C.