锚杆锯切设备自动化改造技术应用

通过对锚杆锯切设备的设计、改进情况进行总结，详细介绍了自动化改造前后的设备工作原理、结构组成以及各部分工作过程动作描述等内容，根据改造前后的各项数据统计分析，列出了自动化改造后产品质量、生产效率和企业的利润的变化，同时还有设备故障率、工人劳动强度、设备操作人员数量的减少以及工厂生产环境由污染型转变成节能环保型企业等相关内容，展示所取得的有益效果。     

NiTi-W原位复合材料的马氏体相变与性能

为获得高性能NiTi基记忆合金复合材料,通过熔炼、锻造、拔丝等手段获得一种NiTi-W原位复合材料。利用SEM扫描电镜观察材料显微组织;DSC测试材料的马氏体相变行为;利用WDT II-20万能拉伸试验机测试材料的力学性能。SEM分析结果显示,拔丝加工使W纤维直径细化至几微米,甚至亚微米级别,在NiTi基体中沿拔丝方向一致排布。DSC测试结果显示,材料经不同温度退火后展现出复杂的可逆马氏体相变行为,在某些升、降温曲线上出现多个吸放热峰现象。拉伸测试结果显示,600 ℃退火样品经适当的预拉伸变形后,屈服强度会大大增加,由~200 MPa提升到~800 MPa,断裂应力超过1 GPa,断裂应变高达40%,材料展现出优秀的线性超弹性,是一种集高强度、高塑性、高线性超弹性于一身的高性能材料。     

An efficient nonlinear polynomial color characterization method based on interrelations of color spaces

A well-known color characterization method is to take an image of a color chart and then to find the mapping matrix from the digital RGBs to the corresponding known CIEXYZs. However, the prediction errors are generally large in CIELAB color space because of the nonlinear transformation from CIEXYZs to CIELABs. In this article, we propose an efficient and simple nonlinear method for the color characterization of input devices. The approach for deriving a colorimetric mapping between digital RGB signals and CIELAB tristimulus values uses the polynomial modeling by considering the interrelations among the standard CIE color spaces. Furthermore, to improve the accuracy of solution, we take the polynomial root terms extension. Our algorithm is simple to implement because only a least-squares mapping should be solved. Various computational results are given to demonstrate the efficiency and capability of the proposed method.     

High pressure modifications in amorphous boron suboxide: An ab initio study

Using constant pressure ab initio calculations, we probe the high-pressure modifications in amorphous boron suboxide (B₆O) consisting of glassy boron trioxide (B₂O₃) and boron (B) domains up to a theoretical pressure of 100 GPa. At this pressure, the structure remains amorphous. We find a steady increase in the average coordination of both B and oxygen (O) atoms. O atoms mostly attain threefold coordination as in B₂O₃ glass at high pressures. On the other hand, the mean coordination number of B-atoms reaches six at high pressures and the structural changes in B-rich regions are perceived to be quite analogous to those of amorphous B. B₁₂ clusters are found to persevere during the pressurizing process and the high-pressure modifications occur predominantly around O-atoms and the regions that connect the pentagonal pyramid-like motifs to each other. Upon pressure release, some high-pressure configurations persist in the model and another noncrystalline structure being about 10% denser than the original state is recovered, suggesting a permanent densification and a possible irreversible amorphous-to-amorphous phase transformation in B₆O. The recovered network shows slightly better mechanical properties than the uncompressed model. During the compression and decompression processes, amorphous B₆O remains semiconducting. The delocalization of some band tail states is seen at high pressures.     

基于深度信念网络的列车故障音频诊断方法

铁路在交通运输行业有着举足轻重的地位，一旦列车发生故障将会导致严重的生命财产损失。由于列车发生故障的概率相对较低，因此难以捕获列车的故障样本。针对上述问题，提出了一种无监督学习的列车故障识别方法，通过检测列车音频信号来识别列车故障。该方法基于深度信念网络(DBN)，利用小波包分解提取检测信号的特征向量并将其作为DBN的输入，待网络充分训练后，由训练好的DBN识别当前列车的运行状况。现场监测实验结果表明，该方法能够在无监督的条件下有效识别列车故障，保障了列车的运行安全。     

Thermodynamic properties of sodium pyrovanadate (Na4V2O7) at high temperature (298.15–873 K)

The sodium pyrovanadate (Na₄V₂O₇) powder was synthesized by solid-state reaction using sodium carbonate (Na₂CO₃) and vanadium pentoxide (V₂O₅) as raw materials. X-ray powder diffraction (XRD), scanning electron microscope (SEM), and differential scanning calorimeter (DSC) were used to accurately characterize the synthesized sample. The solid-state phase transformation from α-Na₄V₂O₇ to β-Na₄V₂O₇ occurs at the temperature 696 K and the enthalpy is equals to 1.03 ± 0.01 kJ/mol, the endothermic effect at 931 K and the enthalpy is equals to 31.35 ± 0.31 kJ/mol, which is related to the melting of Na₄V₂O₇. The high-temperature heat capacity of Na₄V₂O₇ was measured using a Multi-high temperature calorimeter 96 line and DSC. The obtained high-temperature heat capacity of Na₄V₂O₇, as a function of temperature, was modeled as: Cp=314.62+0.05T-5494390T^-2 J·mol^-1·K^-1 (298.15-873 K). The temperature dependence on heat capacity was then used for computing changes in the enthalpy, entropy, and Gibbs free energy at the specific temperature internal.     

Anomalous kinetics of lath martensite formation in stainless steel

The kinetics of lath martensite formation in Fe–17·3 wt-%Cr–7·1 wt-%Ni–1·1 wt-%Al–0·08 wt-%C stainless steel was investigated with magnetometry and microscopy. Lath martensite forms during cooling, heating and isothermally. For the first time, it is shown by magnetometry during extremely slow isochronal cooling that transformation rate maxima occur, which are interrupted by virtually transformation free temperature regions. Microscopy confirms martensite formation after athermal nucleation of clusters followed by their time dependent growth. The observations are interpreted in terms of time dependent autocatalytic lath martensite formation followed by mechanical stabilisation of austenite during the transformation process.     

Microstructural evolution and corresponding property changes after deep cryotreatment of tool steel

The microstructural evolution and structure–property correlation subjected to deep cryotreatment of tool steel were studied. The results show that the retained austenite continues to transform into martensite almost but not complete at low temperature. The topography of retained austenite exhibits as a nanoscale thin film with a thickness range of 20–60?nm between the martensite laths. The changes of internal friction peaks have been explained well by the coupling model, which indicates that deep cryotreatment is not only removing retained austenite but also promoting the interstitial carbon atoms segregated to nearby dislocations under the shrinking strain energy. In addition, more carbides precipitated from the matrix during tempering in cryotreated samples and were verified by analyses of transmission electron microscopy.     

Thermal and transport properties of as-grown Ni-rich TiNi shape memory alloys

Electrical resistivity, Seebeck coefficient, specific heat and thermal conductivity measurements on the Ti_50−xNi_50+x (x = 0.0–1.6 at.%) shape memory alloys are performed to investigate their thermal and transport properties. In this study, anomalous features are observed in both cooling and heating cycles in all measured physical properties of the slightly Ni-rich TiNi alloys (x ≤ 1.0), corresponds to the transformation between the B19′ martensite and B2 austenite phases. Besides, the transition temperature is found to decrease gradually with increasing Ni content, and the driving force for the transition is also found to diminish slowly with the addition of excess Ni, as revealed by specific heat measurements. While the signature of martensitic transformation vanishes for the Ni-rich TiNi alloys with x ≥ 1.3, the characteristics of strain glass transition start to appear. The Seebeck coefficients of these TiNi alloys were found to be positive, suggesting the hole-type carriers dominate the thermoelectric transport. From the high-temperature Seebeck coefficients, the estimated value of Fermi energy ranges from ∼1.5 eV (Ti_48.4Ni_51.6) to ∼2.1 eV (Ti₅₀Ni₅₀), indicating the metallic nature of these alloys. In addition, the thermal conductivity of the slightly Ni-rich TiNi alloys with x ≤ 1.0 shows a distinct anomalous feature at the B19′ → B2 transition, likely due to the variation in lattice thermal conductivity.     

Origin of stress overshoot in amorphous solids

Based on the shear-transformation-zone (STZ) theory, we propose a constitutive model for describing homogeneous elastoplastic deformation of amorphous solids where the interaction of shear transformations and free volume dynamics is incorporated. This theoretical model can reproduce the stress overshoot behavior that shows the dependence of strain rate, temperature, STZ population and dilatancy of systems. It reveals that the stress overshoots its steady state value due to the delayed activation of shear transformations that results from the insufficient free volume in the system. However, the subsequent strain softening (stress drop) is attributed to the shear-induced dilatation that is a result of the positive interplay between shear transformations and free volume creation, the latter playing the dominant role. Our analysis also demonstrates that the STZs, as basic carriers of amorphous plasticity, govern the yielding of the system, whereas the free volume dynamics significantly affects the post-yielding behaviors.