孤岛工作面撤出支架时的顶板加固及撤出工艺

11210高水充填工作面作为孤岛工作面,末采阶段顶板压力大。采用锚网支护控制工作面顶板,撤架时利用掩护架保证撤架空间安全,利用移架平台撤出剩余支架,实现了安全生产。     

A comparative study on the effect of loading speed and surface scratches on the flexural strength of aluminosilicate glass: Annealed vs. chemically strengthened

Quasi-static and dynamic three-point-bending experiments were conducted on both annealed and chemically strengthened aluminosilicate glass scratched by different normal loads. Scratched areas were observed by optical microscope and atomic force microscope. Chemically strengthened glass shows better resistance to surface scratch. These dynamic experiments were carried out using a modified Split Hopkinson Pressure Bar (SHPB) device and a pulse-shaping technique was used to keep constant loading speed to the specimens. In tests, high-speed photography was also used to observe the failure process of the specimens. The test results showed that the flexural strength of aluminosilicate glass (AG) strongly depends on the applied loading speed. Compared with its annealed counterpart, the chemically strengthened glass (CSG) showed higher flexural strength to both static and dynamic loadings. Moreover, the three-point bending experiments were conducted on scratched AG and CSG specimens and decrease of 20–40% in flexural strength was observed. The fractography analysis showed that in dynamic loading conditions the fracture surface was not smooth and has more secondary cracks as compared to static loading.     

Cross-Layer Optimization of Dynamic Packet Assignment for Video Transmission Over IEEE 802.11e Networks

Video transmission over IEEE 802.11e wireless networks still shows poor performance for large bandwidth demand and frequently changed environments. Thus, several enhancements of IEEE 802.11e were proposed. On the other hand, big frames and simultaneous sending of adjacent frames always cause packet dropping for buffer overflow. In the past, we proposed an IEEE 802.11e enhancement named DFAA and a content aware mechanism to solve the above problems. The motivation of this paper is to find a proper way to integrate these two mechanisms. A DFAA enhancement (DFAA-E) is proposed to make up the insufficiency of content aware mechanism. Experiments results show that the combination of DFAA-E and content aware mechanism improves the video decoded quality greatly. And its performance can be further enhanced by selecting the suitable settings of certain parameters.     

Test sample allocation method for testability verification test

An extended failure mode effect and criticality analysis (FMECA)-based sample allocation method for testability verification is presented in this study to deal with the poor representativeness of test sample sets and the randomness of the testability evaluation results caused by unreasonable selection of failure samples. First, the fault propagation intensity is introduced as part of the extended information of FMECA, and the sample allocation impact factors of component units and failure modes are determined under this framework. Then, the failure mode similarity and impact factor support are defined, and the game decision method for weighing the relationship between similarity and support is proposed to obtain the weight of failure mode impact factor. Finally, a two-step allocation framework of test samples is formulated to realize the sample allocation of component units and failure modes. This method is applied to the testability verification test of a launch control system. Results show that this method can obtain more representative test samples compared with the traditional sample allocation method while effectively reducing randomness of single testability evaluation result.     

An Artificial Skyrmion Platform with Robust Tunability in Synthetic Antiferromagnetic Multilayers

Magnetic skyrmions are topologically nontrivial spin structures, and their existence in ferromagnetically coupled multilayers has been widely reported with a disordered arrangement. Here, a nucleation scenario of ordered skyrmions in nanostructured synthetic antiferromagnetic (SAF) multilayers is proposed and experimentally demonstrated using direct magnetization imaging, indirect magnetometer and magnetoresistance measurement, and micromagnetic simulation. Instead of relying on Dzyaloshinskii–Moriya interaction, the antiferromagnetic interlayer exchange coupling in the SAF multilayers fulfills the role of nucleation and stabilization of skyrmions. The robustness of the proposed skyrmion nucleation scenario is examined against temperature from 4.5 to 300 K and device size from 400 to 1200 nm. Interestingly, these synthetic skyrmions still behave well with a size less than 100 nm. The higher stability than generic magnetic domains can be attributed to topological protection. The results thus provide an artificial skyrmion platform to meet the functional needs of high density and designable arrangement in magnonic and spintronic applications.     

Deploy Efficiency Driven k-Barrier Construction Scheme Based on Target Circle in Directional Sensor Network

Journal of Computer Science and Technology - With the increasing demand for security, building strong barrier coverage in directional sensor networks is important for effectively detecting...     

Optical Control of Cellular ATP Levels with a Photocaged Adenylate Kinase

We have developed a new tool for the optical control of cellular ATP concentrations with a photocaged adenylate kinase (Adk). The photocaged Adk is generated by substituting a catalytically essential lysine with a hydroxycoumarin-protected lysine through site-specific unnatural amino acid mutagenesis in both E. coli and mammalian cells. Caging of the critical lysine residue offers complete suppression of Adk's phosphotransferase activity and rapid restoration of its function both in vitro and in vivo upon optical stimulation. Light-activated Adk renders faster rescue of cell growth than chemically inducible expression of wild-type Adk in E. coli as well as rapid ATP depletion in mammalian cells. Thus, caging Adk provides a new tool for direct conditional perturbation of cellular ATP concentrations thereby enabling the investigation of ATP-coupled physiological events in temporally dynamic contexts.     

彩色轮胎的生产工艺及设计要点

介绍不同工艺的彩色轮胎，总结白胎侧和半彩轮胎的工艺、结构及配方设计要点。彩色轮胎改变了传统轮胎以单一黑色为主的状况，让轮胎颜色更加丰富；传统黑色轮胎的配方设计时只需考虑原材料对胶料性能的影响，彩色轮胎进行配方设计时则需同时兼顾原材料对胶料性能的影响。