基于BM和IBM的地下空区顶板安全厚度确定

针对似层矿开采的特点,以卡房分矿I-9采空区为工程实例,将地下空区顶板视为梁模型、改进梁模型,结合岩梁、结构力学和材料力学理论,以顶板岩层抗拉强度为控制条件,推导出地下空区不同跨度下顶板的安全厚度。研究结果表明：顶板安全厚度随空区跨度的增加而增大,近乎呈线性关系。低水平应力时随空区跨度增加对项板厚度整体影响都较小;当采空区跨度较小时,不同水平应力程度对顶板安全厚度的影响可忽略不计;当空区跨度达到一定程度时,对比梁模型计算的结果,随空区跨度的增加改进梁模型计算的顶板安全厚度增加幅度变大。     

Vibrational stimulation of the skin using both electrical and mechanical stimuli

Pulmonary eosinophilic granuloma diagnosed by lung biopsy is described; the case demonstrates the remission and relapse that may occur.     

The application of Baosteel mechanical and electronic products in the metallurgical logistics management

This paper elaborates core and related technologies with the theme of the application of Baosteel mechanical and electronic products in metallurgical logistics management.It introduces the model of logistics management in iron and steel enterprise,especially focuses on the vital roles of Mechano - electronic Products in this model.Then it describes sensor detection device and marking & identification equipment, considered as the main methods of logistics tracking in production equipment layer.Consequently logistics tracking is also explained and promoted to logistics management level.We mainly present some technologies about the wireless data transmission and crane positioning system in this section.And some new prospective R&D study results and more comprehensive solutions for mechanical and electrical products from Baosight are also introduced.Finally the significances of metallurgical logistics management are summarized.     

Determination of thresholds for detection of cerebellar blood flow deficits in brain SPECT images

Two observer studies were performed to determine the threshold (i.e., ratio of the counts in a lesion area to the counts in the corresponding contralateral region) at which two experienced observers diagnosed blood flow deficits in the cerebellum in 99mTc-HMPAO SPECT scans to be clinically significant, and investigate the effect of the intensity mapping scale on the detectability of lesions. METHODS: Lesions representing blood flow deficits varying from no decrease to a 12.5% decrease were simulated in 300 patient images. The first study, a receiver-operator characteristics (ROC) experiment, used two observers to compare the detectability of lesions with three intensity mapping scales: two pseudocolor scales, and a linear gray scale. A second "threshold-criterion" study was done to estimate the threshold at which observers determine deficits to be clinically significant. RESULTS: In the ROC study, the observers were more accurate in detecting lesions displayed in pseudocolor than in gray scale. In the threshold-criterion study, the threshold at which observers assessed clinically significant deficits was found to range between 0.900 and 0.950 (corresponding to a 5%-10% decrease in counts), depending on the observer, and the intensity mapping scale. For both observers, the detection threshold was higher (i.e., closer to 1.0) with the pseudocolor scale than with the gray scale. CONCLUSION: The definition of a threshold value for use in quantitative techniques is dependent on both the observer and the intensity mapping scale. Observers were more accurate with the pseudocolor scales.     

Determination of kinetic parameters for both reversible and irreversible first-order reactions

The paper reviews the main recent publications concerning infrared (IR) spectroscopy as applied to the study of lipid-protein interactions in model and cell membranes, lipoproteins, and related systems (e.g. lung surfactant). The review focuses mainly on transmission IR. Based on the available data, a number of general conclusions are presented on the perturbations caused by proteins on either the hydrocarbon chains, the polar headgroups or the interface region. Lipid-protein interactions in native cell membranes do not reveal significant differences from what is observed in semisynthetic model systems.     

The distribution of human TCR junctional region lengths shifts with age in both CD4 and CD8 T cells

Several normal and pathological antigen-driven immune responses are associated with limited TCR usage. CDR3 sequence and to some extent length represent clonal markers which can be used to follow the course of an immune response. We investigated whether differences exist in the CDR3 length distribution in the CD4 versus CD8 populations which might reflect the HLA class restriction of the T cell subpopulation. We showed that the range is similar in both the CD4 and CD8 populations for most BV families. Differences exist between CDR3 length distributions of adult versus cord blood CD4 and CD8 T cells. The percentage expressing CDR3 of 10 amino acids or more across all BV families was significantly lower in the cord blood T cells compared to the adults for both CD4 and CD8 populations. This is likely to reflect either differences in the development of the T cell population such as increased N region length post-partum or may be the result of foreign antigen exposure. To address this issue, samples of TCRBV sequences from cord and adult T cell populations were compared. No significant differences were found in either exonucleolytic removal or N region addition between the adult and cord blood samples suggesting that the population shift is the result of antigen exposure. No spectratype distortions existed for any BV family in the adult or cord blood CD4 populations; however, distortions were seen in CD8 populations from all the adults and much less frequently in the cord blood T cells. We investigated the ability to detect clonality at frequencies that one would expect to find antigen-specific T cells in the peripheral repertoire. It was possible to identify a clone at a frequency of 0.1% in a polyclonal CD4 population. This frequency corresponds to that of some individual clones after antigen-driven T cell expansion and establishes parameters within which T cell immune responses may be tracked ex vivo.     

Influence of silicon and phosphorous on the mechanical properties of both ferrite and dual-phase steels

A study has been made of the influence of up to 2 pct Si and 0.42 pct P upon the strength and ductility of ferrites over a wide grain size range; the grain size was varied fromd ^−1/2 mm^−1/2 = 4 to 14. Although the ductility decreased with increasing strength for all the alloys, the 2 pct Si alloy had the best combination of strength and ductility. The ferrites containing 2 pct Si and 0.2 pct P had greater uniform elongations than conventional HSLA steels at the same tensile strength; it is thought that the ductility of the ferrites is enhanced by the presence of Si while the ductility of conventional HSLA steels is reduced by the presence of carbide precipitates. With the theory for a composite of two ductile phases and the results for the fine-grained alloyed ferrites, the change in uniform elongation as a function of tensile strength was predicted for dual-phase (martensite plus ferrite) steels. Good agreement was found between the prediction and experimental results for dual-phase steels containing up to 0.2 pct P or 2 pct Si; the 2 pct Si alloy had the best combination of strength and ductility of all dual-phase steels so far reported. This study again emphasizes the importance of the high strength, high ductility ferrite in controlling the properties of dual-phase steels.     

X射线荧光光谱法测定废旧电子元器件中的金

将一定量废旧电子元器件溶解后的含金溶液加入到人工配制的基体中,制成X射线荧光分析样片,使其基体组成相近,消除了基体效应,提高了分析的精密度和准确度。与化学分析方法(氢醌容量法)测定结果相比,该方法具有简单快速、准确度高、测定成本低等特点,可替代化学分析方法。     

First-principles investigation of mechanical and electronic properties of LaAg5 Laves phase under pressure

The effects of applied pressure on the structural, mechanical, and electronic properties of LaAg5 compound were investigated employing the first-principles method based on the density functional theory. The mechanical results demonstrated that bulk modulus, shear modulus and Young's modulus presented the linearly increasing dependences on the external pressure; the B/G and Poisson's ratio indicated that La Ag5 compound was a ductile material with central forces in interatomic under pressure from 0 to 40 GPa; the universal anisotropic index was performed to investigate the elastic anisotropic of La Ag5. Additionally, the pressure dependence of the density of states and Mulliken charge were also discussed. The bonding characterization in La Ag5 was composed of metallic, covalent and ionic. The metallic component was derived from free-electron transferring from Ag-s and Ag-d to Ag-p, and from La-s to La-d. The ionic component was due to the charge movement from La to Ag. The covalent was owing to Ag-p-La-d bonding hybridization and Ag-s-Ag-p in the Ag atomic chains. The covalent and ionic bonds were stronger under pressure but there was no significant change in metallic nature.     

冷却工艺对汽车大梁钢510L组织性能的影响

对汽车大梁钢510L进行了实验室热轧试验,研究了轧后冷却工艺变化对试验钢组织和力学性能的影响.结果表明,在轧后4种不同的冷却模式中,超快冷-层流冷却模式所获得的组织最为细小,强度最高.在层流冷却-空冷-层流冷却模式下,随着卷取温度的降低,抗拉强度显著提高,屈强比降低,可实现510L的升级轧制.     

GRF薄壁空心管混凝土梁构件的力学性能实验研究

通过对GRF薄壁空心管混凝土梁构件的实验研究和理论分析表明,在弹性阶段,外荷载和GRF薄壁空心管混凝土梁构件的各个部位的应变关系与弹性理论计算结果基本一致,由此可见,设计计算时采用弹性理论计算公式是合理的,梁构件的弹性极限荷载为其极限承载力的25%左右;在反复外荷载的作用下,其极限承载力可增加16%左右;当外荷载接近其极限承载力时,斜裂缝向上延伸到集中荷载作用点位置,向下延伸到纵向钢筋,并沿着纵向钢筋向支座发展,产生撕裂裂缝,直至破坏.这些可为现浇钢筋混凝土GRF薄壁空心楼板的设计计算提供参考.