Texture heterogeneities in αp/αs titanium forging analysed by EBSD-Relation to fatigue crack propagation

The microstructure and the local texture of a large IMI 834 forging were characterized using the Electron Back Scattered Diffraction (EBSD) technique. Crystallographic domains called macrozones and formed by a majority of primary α_p grains with their     axes in nearly the same direction were found. They had a band-like structure, parallel to the axial direction of the forging. The influence of these macrozones on the cold dwell-fatigue properties was studied. Several samples were tested under cold dwell-fatigue conditions. The crack initiation and the short-distance propagation region optically matched a bright region that contained numerous quasi-cleavage facets. The analysis of the EBSD measurements showed that this bright region was enclosed within a sharp textured region with     axes at less than 30° from the loading axis. The crystallographic features of the crack nucleation site and the crack propagation path were also analysed.     

异相电解/超声波方法制备超细金属粉末

研究一种异相电解/超声波制备超细金属粉末的新方法,并应用该方法对制备超细铁粉末进行研究,成功地制备出超细金属铁粉末。该方法主要用于相对氢而言的较活泼金属粉末的制备,也可以应用于相对氢而言的不活泼金属粉末的制备,适用范围广,电解效率高,成本低,具有工业化应用前景。     

Images of absolute retardance L.Δn, using the rotating polariser method

Modulation techniques for measuring changes in optical birefringence, such as the rotating-polariser method (Wood & Glazer, 1980, J. Appl. Crystallogr . 13, 217), allow one to determine |sin δ|, δ = 2π L Δ n /λ, Δ n = double refraction, L  = light path and λ = wavelength. However, they generally suffer from not providing absolute values of the optical retardance or are limited to relatively low retardance values. In addition, knowledge of the absolute phase is required when establishing the correct values of optical orientation information. In this paper, it is shown how the phase δ, and thus optical retardance, can be extracted from combining measurements of |sin δ| at different wavelengths. The new approach works on each single point of a 2-D picture without the need to correlate with neighbouring points. There is virtually no limit to the retardance, and the computational efforts are small compared with other methods (e.g. Ajovalasit et al. 1998, J. Strain Analysis 33 , 75). When used with imaging techniques, such as the rotating polariser method of Glazer, Lewis & Kaminsky 1996 ( Proc. R. Soc. London Series A452 , 2751) this process has the potential to identify automatically optically anisotropic substances under the microscope. The algorithm derived in this paper is valid not only for birefringence studies, but can be applied to all studies of interfering light waves.     

“工业4.0”下的“液压4.0”与智能液压元件技术

根据工业革命的发展规律与液压技术的比照,由于液压技术的发展与历次工业革命高度重合,因此从工业4.0引申出液压4.0的概念,并有其本身的发展特点。为了让液气密行业更加深入和更加快速地开展工业4.0的智能化发展,在这里比较深入地剖析了智能液压元件的原理、构成与功能,与此同时,对于传统液气密行业过去很少涉及的CAN总线的技术基础与概念作了介绍,并涉及一些入门的技术概念,以便行业的企业管理者与工程技术人员能更快运用它们。最后也分析了智能液压元件给用户与生产商带来的效益。     

Numerical study of a water distillation system using solar energy

This paper tackles an optimization approach in order to boost the fresh water production of a new design of a solar still which is located at Sfax engineering national school in Tunisia. This optimization approach is based upon the above mentioned design’s improvement by coupling the conventional solar still into at a condenser, solar air and water collector and humidifier. This new concept of a distiller solar still using humidification- dehumidification processes (HD) is exploited for the desalination purpose. As a result of this work, the humidification- dehumidification processes have an essential effect in improving the solar still performance. Performance has been predicted theoretically in terms of water and inner glass cover temperatures, the inlet temperature of air and water of the new concept of distiller on water condensation rate and fresh water production. A general model based on heat and mass transfers in each component of the unit has been developed in steady dynamic regime. The developed model is used, simulating the HD system, to investigate the influence of the meteorological and operating parameters on the system productivity. The obtained set of ordinary differential equations has been converted to a set of algebraic system of equations by the functional approximation method of orthogonal collocation. The developed model is used to simulate the HD system in order to investigate the steady state behavior of each component of the unit and the entire system exposed to a variation of the entrance parameters and meteorological conditions. The obtained results were compared with those of other studies and the comparison gives a good validity of the present results.

     

The wear of ultrafine WC–Co hard metals

The wear performance of ultrafine-grained tungsten carbide–cobalt (WC–Co) hard metals during three-body abrasion and particle erosion has been evaluated and compared to that of similar conventional coarser grained hard metals. The tungsten carbide grain size varied between 0.5 and 3 μm with cobalt contents ranging from 6 to 15%. Silica particles were used in both forms of testing. Erosion was carried out at 60 ms⁻¹ at an impact angle of 75° and abrasion at a velocity of 0.5 ms⁻¹ and a load of 50 N.

The wear resistance of the ultrafine grades was found to be at least double that of the closest conventional fine grained hard metals. These increases in wear performance are considerably higher than any corresponding increase in hardness which is, at most, 25% and is not achieved at the expense of fracture toughness which is maintained at a similar level to that of conventional fine grained hard metals. The increase in wear resistance coincides with a change in the mechanism of material removal. Sub-micron materials experience ductile deformation and bulk removal of material whilst coarser grades display more localised response with extensive fragmentation of the WC grains.     

用于煤超微气流粉碎喷嘴设计关键参数的研究

针对气流粉碎的特点,分析了气流粉碎在煤超微粉碎方面的应用,根据超音速喷嘴设计的一般原理及相关理论,研究了气流粉碎部件喷嘴设计的主要参数、喷嘴的喷气速度、工质流量及喷嘴几何参数,得到了喷嘴设计过程中的关键参数对煤超微粉碎性能的影响,为煤的超微粉碎指明了发展方向.     

Fault detection in the distillation column process using Kullback Leibler divergence

Chemical plants are complex large-scale systems which need designing robust fault detection schemes to ensure high product quality, reliability and safety under different operating conditions. The present paper is concerned with a feasibility study of the application of the black-box modeling method and Kullback Leibler divergence (KLD) to the fault detection in a distillation column process. A Nonlinear Auto-Regressive Moving Average with eXogenous input (NARMAX) polynomial model is firstly developed to estimate the nonlinear behavior of the plant. Furthermore, the KLD is applied to detect abnormal modes. The proposed FD method is implemented and validated experimentally using realistic faults of a distillation plant of laboratory scale. The experimental results clearly demonstrate the fact that proposed method is effective and gives early alarm to operators.     

Straigtness measurement using a heterodyne moiré method

Optical heterodyne interferometry is a new interference technique, allowing quick and accurate measurements of dimension. A similar technique can determine the fringe phase of the moiré method as intensity is modulated by movement of the reference grating. The phase difference between certain points in the moiré pattern is detected automatically.The interference fringes generated by laser are used to measure straightness. Small displacement of fringes is detected with the heterodyne moiré method. Generally, beam flutter caused by air disturbance becomes a serious problem in systems using long beam paths, though it can be reduced by controlling the air flow.     

Damage detection in glass/epoxy composite structure using 8–12 GHz X-band

In this study, an electromagnetic wave 8–12 GHz X band microwave was utilized to detect various types of damage in a woven fabric composite structure. Damages, such as cracks, delamination, bubbles, and voids, were synthesized artificially in accordance to ASTM D2734. Variable thicknesses of composite structure were also analyzed, and the influence of defect on the transmitted signal was investigated. Network analyzer (ENA5701C) in X-band was utilized for this investigation. Detection was based on the changes in the electromagnetic properties, such as permittivity and permeability, and the reflection and transmission to microwaves were based on standard samples. These were implemented for each case of defect selected for this study. Experimental tests revealed that damage in the transparent glass/epoxy composite can be recognized clearly. Particularly, sample thickness was detected when the microwave was applied. This testing method can be considered an inline operation and non-destructive testing for such composites, especially during fabrication.     

基于色谱模拟蒸馏技术的石油馏分恩氏蒸馏馏程测定方法

以美国材料与试验协会（ASTM）方法为基础模型,提出一种基于色谱模拟蒸馏技术的恩氏蒸馏馏程测定方法。利用模型计算值与实验值之间的误差获得模型校正参数,对原始模型进行校正。校正模型已成功地应用于直馏汽油、煤油和柴油等馏分的恩氏蒸馏馏程预测。利用校正模型预测得到的馏程数据能够满足恩氏蒸馏测试重复性的要求。色谱模拟蒸馏是一种可以取代恩氏蒸馏的馏程测定方法。     

φFLIM: a new method to avoid aliasing in frequency-domain fluorescence lifetime imaging microscopy

In conventional wide‐field frequency‐domain fluorescence lifetime imaging microscopy (FLIM), excitation light is intensity‐modulated at megahertz frequencies. Emitted fluorescence is recorded by a CCD camera through an image intensifier, which is modulated at the same frequency. From images recorded at various phase differences between excitation and intensifier gain modulation, the phase and modulation depth of the emitted light is obtained. The fluorescence lifetime is determined from the delay and the decrease in modulation depth of the emission relative to the excitation. A minimum of three images is required, but in this case measurements become susceptible to aliasing caused by the presence of higher harmonics. Taking more images to avoid this is not always possible owing to phototoxicity or movement. A method is introduced, φFLIM, requiring only three recordings that is not susceptible to aliasing. The phase difference between the excitation and the intensifier is scanned over the entire 360° range following a predefined phase profile, during which the image produced by the intensifier is integrated onto the CCD camera, yielding a single image. Three different images are produced following this procedure, each with a different phase profile. Measurements were performed with a conventional wide‐field frequency‐domain FLIM system based on an acousto‐optic modulator for modulation of the excitation and a microchannel‐plate image intensifier coupled to a CCD camera for the detection. By analysis of the harmonic content of measured signals it was found that the third harmonic was effectively the highest present. Using the conventional method with three recordings, phase errors due to aliasing of up to ± 29° and modulation depth errors of up to 30% were found. Errors in lifetimes of YFP‐transfected HeLa cells were as high as 100%. With φFLIM, using the same specimen and settings, systematic errors due to aliasing did not occur.     

A practical R&D selection model using fuzzy pay-off method

The aim of this paper is to develop a practical R&D portfolio selection model that addresses effective R&D project valuation issue, while it tackles R&D uncertainty in portfolio optimization. Fuzzy sets theory is employed to capture and model the inaccuracy in project information. To avoid the well-known complications of fuzzy real option valuation, the fuzzy pay-off method is used to more effectively value R&D projects. The resulting problem is formulated as a fuzzy zero–one integer programming model which is later transformed into a crisp mathematical formulation to solve the problem for various degrees of risk. A numerical example is used to illustrate the proposed approach.     

Terminal protein-induced stretching of bacteriophage φ29 DNA

Stretching of DNA molecules helps to resolve detail during the fluorescence microscopy of both single DNA molecules and single DNA–protein complexes. To make stretching occur, intricate procedures of specimen preparation and manipulation have been developed in previous studies. By contrast, the present study demonstrates that conventional procedures of specimen preparation cause DNA stretching to occur, if the specimen is the double‐stranded DNA genome of bacteriophage φ29. Necessary for this stretching is a protein covalently bound at both 5′ termini of φ29 DNA molecules. Some DNA molecules are attached to a cover glass only at the two ends. Others are attached at one end only with the other end free in solution. The extent of stretching varies from ～50% overstretched to ～50% understretched. The understretched DNA molecules are internally mobile to a variable extent. In addition to stretching, some φ29 DNA molecules also undergo assembly to form both linear and branched concatemers observed by single‐molecule fluorescence microscopy. The assembly also requires the terminal protein. The stretched DNA molecules are potentially useful for observing DNA biochemistry at the single molecule level.     

TEM, HRTEM, electron holography and electron tomography studies of γ' and γ nanoparticles in Inconel 718 superalloy

The aim of the study was the identification of γ' and γ strengthening precipitates in a commercial nickel-base superalloy Inconel 718 (Ni-19Fe-18Cr-5Nb-3Mo-1Ti-0.5Al-0.04C, wt %) using TEM dark-field, HRTEM, electron holography and electron tomography imaging. To identify γ' and γ nanoparticles unambiguously, a systematic analysis of experimental and theoretical diffraction patterns were performed. Using HRTEM method it was possible to analyse small areas of precipitates appearance. Electron holography and electron tomography techniques show new possibilities of visualization of γ' and γ nanoparticles. The analysis by means of different complementary TEM methods showed that γ particles exhibit a shape of thin plates, while γ' phase precipitates are almost spherical.     

Breast histopathology image segmentation using spatio‐colour‐texture based graph partition method

This paper proposes a novel integrated spatio‐colour‐texture based graph partitioning method for segmentation of nuclear arrangement in tubules with a lumen or in solid islands without a lumen from digitized Hematoxylin–Eosin stained breast histology images, in order to automate the process of histology breast image analysis to assist the pathologists. We propose a new similarity based super pixel generation method and integrate it with texton representation to form spatio‐colour‐texture map of Breast Histology Image. Then a new weighted distance based similarity measure is used for generation of graph and final segmentation using normalized cuts method is obtained. The extensive experiments carried shows that the proposed algorithm can segment nuclear arrangement in normal as well as malignant duct in breast histology tissue image. For evaluation of the proposed method the ground‐truth image database of 100 malignant and nonmalignant breast histology images is created with the help of two expert pathologists and the quantitative evaluation of proposed breast histology image segmentation has been performed. It shows that the proposed method outperforms over other methods.     

8×8越野车越障高度计算

基于8×8越野车独立悬架匹配计算,各种参数的设定均为理想状态,整车质心为在数模中计算所得,弹簧刚度取满载时的刚度,忽略越障过程中的刚度变化,且整车轴荷为估算值。通过设定不同地面摩擦系数的情况下,建立数学模型,计算四个轴越障高度以及各轴所需驱动力。该计算方法也适用于轻、中型越野车越障能力计算。