Effect of High-Pressure Torsion Processing and Annealing on Hydrogen Embrittlement of Type 304 Metastable Austenitic Stainless Steel

The effect of high-pressure torsion (HPT) and annealing on hydrogen embrittlement (HE) of a type 304 stainless steel was studied by metallographic characterization and tensile test after hydrogen gas charging. A volume fraction of ~78 pct of the austenite transformed to α′ martensite by the HPT processing at an equivalent strain of ~30. Annealing the HPT-processed specimen at a temperature of 873 K (600 °C) for 0.5 hours decreased the α′ martensite to ~31 pct with the average grain size reduced to ~0.43 μm through the reverse austenitic transformation. Hydrogen charge into the HPT-processed and the HPT+annealed specimens in the hydrogen content of ~10 to 20 ppm led to no severe HE but appeared in the solution-treated specimen. Especially the 873 K (600 °C) annealed specimen had the ~1.4 GPa tensile strength and the ~50 pct reduction of area (RA) despite the hydrogenation.     

基于智能传感器的矿井水文监测系统的设计

基于智能传感器的应用,设计了一种矿井水文监测系统。该系统集智能水压传感器等于一体,同时具有体积小、成本低、可靠性好、响应速度快和智能化程度高等优点。可以对多种水文参数进行监控,同时将数据、文字、图形和图像等与多媒体有机结合,以提高信息的准确率。     

液压支架的自动反冲洗过滤系统的设计

自动反冲洗过滤系统实现了井下液压支架二级过滤器反冲洗的自动化。该系统利用过滤器前后的压力差来得到反馈信号以控制液压阀,实现液压支架的自动反冲洗过滤,具有更好的安全性和可靠性。     

Investigation of the relation between surface roughness and friction properties of polyester fabrics after abrasion

This paper focused on the investigation of surface roughness and friction properties of polyester fabrics after abrasion. Experiments were performed on polyester woven fabrics produced from the same yarns in warp and weft directions but with different constructional properties. Surface roughness parameters of amplitude, spacing and hybrid, along with static and kinetic coefficients of friction were measured before and after multiple abrasion cycles. Abrasion was used in order to change the surface characteristic (peak and valley heights and depths and their distributions) in such a way by forming ruptured fiber ends under the control of abrasion. Measurements were made along warp, weft, and diagonal directions. The results showed that roughness parameters decreased numerically as abrasion cycles increased and as ruptured fiber ends formed. Static and kinetic coefficients of friction changed in different manners when measurements were performed along warp and weft directions. It was concluded that initial and resultant peak heights and valley depths together with their distribution on fabric surface govern roughness and friction properties of surfaces in opposite ways. Roughness parameters of skewness and kurtosis could be further considered in the research of friction properties of textile surfaces.     

Effect of urban transformation on the values of historic sites around mosques:Two cases in Manisa,Turkey

This study presents a framework for assessing the cultural asset values of historic sites around mosques. Case studies are selected from provinces of Manisa, Turkey, namely, Çarşı in Salihli with its new urban development and Pazaryeri in Gördes that is abandoned and currently considered as an archaeological site. Literature review, archive research, historical research, comparative study, and site survey are carried out to evaluate the urban development of site neighborhoods with a retrospective perspective. An approach presenting the effects of urban transformations on the cultural asset values of the historic neighborhood centers is proposed. The cases reveal that the urban aesthetic is nearly all lost today, but the holiness of each site preserves its authenticity while the historic land use is sustained. Their preservation problems are lack of maintenance and abandonment due to disasters, illegal interventions, inappropriate development plans, and unsuitable restoration approaches. The principles proposed for managing these historic environments consider their cultural asset values in relation to urban history, development of coherent strategies for their presentation, and participation of all actors to their preservation and development.     

Critical assessment of methods for measurement of temperature profiles and heat load history in microwave heating processes—A review

Limitations of microwave processing due to inhomogeneities of power input and energy absorption have been widely described. Over- and underheated product areas influence reproducibility, product quality, and possibly safety. Although a broad range of methods is available for temperature measurement and evaluation of time/temperature effects, none of them is sufficiently able to detect temperature differences and thermally induced effects within the product caused by inhomogeneous heating. The purpose of this review is to critically assess different methods of temperature measurement for their suitability for different microwave applications, namely metallic temperature sensors, thermal imaging, pyrometer measurement, fiber optic sensors, microwave radiometry, magnetic resonance imaging, liquid crystal thermography, thermal paper, and biological and chemical time-temperature indicators. These methods are evaluated according to their advantages and limitations, method characteristics, and potential interference with the electric field. Special attention is given to spatial resolution, accuracy, handling, and purpose of measurement, that is, development work or online production control. Differences of methods and examples of practical application and failure in microwave-assisted food processing are discussed with a special focus on microwave pasteurization and microwave-assisted drying. Based on this assessment, it is suggested that infrared cameras for measuring temperature distribution at the product surface and partially inside the product in combination with a chemical time/temperature indicator (e.g., Maillard reaction, generating heat-induced color variations, depending on local energy absorption) appear to be the most appropriate system for future practical application in microwave food process control, microwave system development, and product design. Reliable detection of inhomogeneous heating is a prerequisite to counteracte inhomogeneity by a targeted adjustment of process and product parameters in microwave applications.     

煤层坚硬顶板综采面初次放顶爆破技术

本文介绍了顾北矿1212(1)综采工作面切眼松动爆破强制放顶技术,圆满地解决了初放期间的顶板管理问题,取得了较好的安全效益。     

Hydrogen uptake in austenitic stainless steels by exposure to gaseous hydrogen and its effect on tensile deformation

Hydrogen solubility and diffusivity of Fe–Cr–Ni austenitic stainless steels were measured through exposure to gaseous hydrogen at a pressure of 10 MPa over the temperature range 110–235 °C. The hydrogen solubility depended on the alloy compositions, whereas the diffusion coefficients were nearly identical at a given temperature. Hydrogen uptake in the stable austenitic steels by exposure to high-pressure gaseous hydrogen led to some loss of ductility, while their fracture surfaces showed evidence of plastic deformation. This was attributed to the enhanced inhomogeneity of plastic deformation in the presence of hydrogen and the increased stress for plastic instability with increasing hydrogen concentration.     

Surface roughness properties of polyester woven fabrics after abrasion

Effect of abrasion on surface roughness properties of textured polyester woven fabrics has been investigated. The effects of weft density, weft yarn filament number, fiber fineness, and weave pattern on surface roughness after abrasion were studied. Surface roughness values of control fabric (not abraded) and abraded fabrics after four different abrasion cycles were discussed according to different constructional parameters. Surface roughness values of fabrics changed according to abrasion cycles and the changes were related to yarn float lengths, yarn densities, yarn fiber fineness, and initial fabric surface roughness. A general overview of the results showed that abrasion eliminated the effect of texture especially at the fabric samples with initially high surface roughness. The surface roughness of fabrics with initially high surface roughness decreased at a greater extent than the ones with low surface roughness after abrasion. Fabrics with high surface roughness were affected more by abrasion and the effect of abrasion on rough surfaces depended on different manners regarding the compactness of woven structures.     

Surface roughness properties of wool woven fabrics after abrasion

Effects of abrasion on surface roughness properties together with appearance of woven wool fabrics have been investigated. The effects of weft yarn count, weft yarn density, and weave pattern on fabric surface roughness after abrasion were researched. Surface roughness values of control fabric (not abraded) and abraded fabrics after four different abrasion cycles were discussed according to different fabric constructional parameters. It was observed that the greatest decreases in surface roughness values after abrasion were observed in loose fabric structures which had the highest initial fabric surface roughness values (coarse yarn, low yarn density, and low yarn intersection). The results showed that change of roughness properties of wool fabric surfaces after abrasion depends on the initial surface roughness values and on the amount of contact area of fabrics based on the fabric constructional parameters.