组合体破损稳性计算方法研究

探讨了计算组合体破损浮态及稳性的一种方法。将复杂形状的组合体看作是由若干简单部分组成的整体,首先求解各部分的水下及水线面要素,然后进行组合得到组合体要素,再完成其破损浮态及稳性计算。计算时采用了格林公式积分方法。实例计算表明该方法计算简便、可靠,且易于编程实现。     

A Review of Permanent Magnet Stirring During Metal Solidification

Metallurgical and Materials Transactions B - Rather than using conventional electromagnetic stirring (EMS) with three-phase alternating current, permanent magnet stirring (PMS), based on the use of...     

Emotion recognition based on physiological signals using brain asymmetry index and echo state network

Neural Computing and Applications - This paper proposes a method to evaluate the degree of emotion being motivated in continuous music videos based on asymmetry index (AsI). By collecting two...     

Kinetics of Reduction of Low-Grade Nickel Laterite Ore Using Carbon Monoxide

Reduction of a low-grade nickel laterite ore with carbon monoxide to produce Fe-Ni alloy was investigated using a thermo-gravimetric analysis (TGA) method. Non-isothermal reduction tests with a fixed heating rate of 10 °C/min from room temperature to 1200 °C were carried out to determine the different reduction stages and reaction products in each state. Combining measured mass losses with theoretically calculated values together with X-ray diffraction analysis, the products of different reduction stages were identified and a reaction path was established. Isothermal reduction tests with temperatures ranging from 500 °C to 1100 °C were performed to evaluate the temperature dependence of the reduction kinetics. Various kinetic models were fitted to the experimental data to further determine the rate-controlling step in the isothermal tests. Then, two groups of TG experiments were carried out to study the effect of CO flow rate and sample mass on the rate of reaction. The results indicated that the reduction rate increases with the increase of the reduction temperature from 500 °C to 1100 °C. More alloy products are formed and the apparent activation energies increase from 8.6 to 14.7 kJ/mol with the increase of the reduction temperature from 700 °C to 1100 °C. Accordingly, it was proposed that diffusion of CO in the gas bulk and through the pores of the laterite ore sample bed are the rate limiting steps.     

Inclusion characteristics and microstructure properties under different cooling conditions in steel with nanoparticles addition

In the present study, the experimental steel containing nanoparticles was manufactured and then cooled to room temperature under different cooling rates. The differences on the inclusion characteristics and microstructure morphologies between the original steel and experimental steel were compared. The results revealed that the majority of reaction products in the experimental steel were Al₂O₃–MgO-bearing hybrid inclusions. These inclusions under brine quenching, and water quenching had large potential for inducing intra-granular acicular ferrites (IAF). Hence the microstructure in the experimental steel mainly consisted of fine IAF. For the original steel, SiO₂–MnO–MnS-based inclusions could hardly induce IAF, and the microstructure consisted of relatively larger intra-granular banded ferrites, and intra-granular polygonal ferrites. The differences on microstructure morphologies between the two steels had a correlation with the inclusion composition, and size. These were the primary factors to determine whether a particular type of inclusion could induce IAF effectively or not.     

Superior Yield Strength and High-Tensile-Toughness Matching of Medium-Mn Steel with Gradient Structure Developed by Cyclic Torsion

A multiphase-gradient-structured medium-Mn steel with dislocation/stacking fault (SF) density gradient, austenite fraction gradient, and grain size gradient is designed and fabricated by cyclic torsion. It exhibits higher yield strength (YS) (942 MPa), ultimate tensile strength (1295 MPa), and tensile toughness (290 mJ mm⁻³) than its homogeneous counterpart (672, 1273 MPa, and 278 mJ mm⁻³, respectively). High-density-interlaced SFs are generated at the surface region because of the change in strain path and stress state during cyclic torsion. These massive interactive SFs promote the persistent martensite transformation of the retained austenite in the surface region within the entire uniform strain range. Therefore, in addition to the central layer, the surface region in the gradient structures provides strong strain hardening. Moreover, the continuous martensite transformation in the surface region allows the gradient structure to be retained even after tensile failure, which is beneficial for improving the heterogeneous-deformation-induced (HDI) hardening of the gradient-structured sample during tensile deformation. Thus, the combination of active and persistent transformation-induced plasticity effect and HDI hardening contributes to its excellent tensile toughness and ductility. Quantitative analysis indicates that HDI strengthening and dislocation strengthening play a dominant role in the sample's ultrahigh YS.     

基于环概化的半同构泛化算法研究

为了防止个人隐私的泄漏,通常在数据共享前需要对其在准标识符上的属性值作概化处理,以消除链接攻击,从而实现在共享中对敏感属性的匿名保护.数据的概化处理增加了属性值的不确定性,也不可避免地造成一定的信息损失.基于环概化(ring generalization)的异构处理算法能够在减少匿名化所导致的数据信息损失的同时,提供更强的隐私保护.提出生成所有基于环概化置换的算法,同时研究置换计数问题,证明了其基数满足O(α\\+n),α>1.在此基础上,提出了一种半同构泛化算法,能在数据共享中实现匿名数据保护,同时降低概化所带来的数据信息损失.     

风/柴并联系统中柴油发电机组的选型与节油分析

介绍了风力发电机/柴油发电机并联运行系统中的柴油发电机组选型时应考虑的问题及风/柴并联持续运行系统的节油途径。     

Correlation between ultrabroadband near-infrared emission and Yb3+/Ni2+ dopants distribution in highly transparent germanate glass-ceramics containing zinc gallogermanate nanospinels

The photoluminescence properties of dopants are strongly correlated with their distributions in host phosphors, the knowledge of which, however, is not well established yet. In this paper, the distribution of the active dopants, for example, trivalent ytterbium (Yb³⁺) and bivalent nickel (Ni²⁺) in a highly transparent germanate glass-ceramic containing thermally grown Zn_1+xGa_2−2xGe_xO₄ (0 ≤ x ≤ 1) nanospinels, is revealed by an analytical transmission electron microscope. The elemental mapping and linescan analysis confirm that both Yb³⁺ and Ni²⁺ accumulate preferentially in the germanium-substituted ZnGa₂O₄ nanospinels embedded in the glass. The influence of glass crystallization on the electric transition properties of Yb³⁺ is presented. An enhanced ultrabroadband near infrared emission of Ni²⁺ is observed as a result of efficient energy transfer from Yb³⁺ to Ni²⁺ accumulated in the nanocrystals. Discussions are given to account for the detailed mechanisms of the efficient energy transfer occurring between the dopants.     

The Effect of Surface Finish on Low-Temperature Acetylene-Based Carburization of 316L Austenitic Stainless Steel

We observed a strong influence of surface finish on the efficacy of low-temperature acetylene-based carburization of AISI 316L austenitic stainless steel. Steel coupons were prepared with different surface finishes prior to carburization, from P400 SiC grit paper to 1-µm-diameter-diamond-paste. The samples with the finer surface finish developed a thicker “case” (a carbon-rich hardened surface layer) and a larger surface carbon concentration. Transmission electron microscopy revealed that the differences arose mainly from the nature of the deformation-induced disturbed layer on the steel surface. A thick (>400 nm) disturbed layer consisting of nano-crystalline grains (≈10 nm diameter) inhibits acetylene-based carburization. The experimental observations can be explained by assuming that during machining or coarse polishing, the surface oxide layer is broken up and becomes incorporated into the deformation-induced disturbed layer. The incorporated oxide-rich films retard or completely prevent the ingress of carbon into the stainless steel.