Zonal disintegration phenomenon in enclosing rock mass surrounding deep tunnels -- Elasto-plastic analysis of stress field of enclosing rock mass

The zonal disintegration phenomenon (ZDP) is a typical phenomenon in deep block rock masses. In order to investigate the mechanism of ZDP, an improved non-linear Hock-Brown strength criterion and a bi-linear constitutive model of rock mass were used to analyze the elasto-plastic stress field of the enclosing rock mass around a deep round tunnel. The radius of the plastic region and stress of the enclosing rock mass were obtained by introducing dimensionless parameters of radial distance. The results show that tunneling in deep rock mass causes a maximum stress zone to appear in the vicinity of the boundary of the elastic and the plas-tic zone in the surrounding rock mass. Under the compression of a large tangential force and a small radial force, the rock mass in the maximum stress zone was in an approximate uniaxial loading state, which could lead to a split failure in the rock mass.     

虚拟样机中模型库关联关系的研究

为了解决复杂产品虚拟样机模型库管理方法引起的虚拟样机间模型的可复用性低、共享性低、存储不方便等问题,提出了一种基于虚拟样机中模型库关联关系的管理方法.通过对虚拟样机协同开发过程分析,建立了基于功能级的元模型.通过研究元模型间的约束关系发现了关联关系层,并实现了基于关联关系的模型库管理系统,在一定程度上解决了以上提出的问题.     

基于单片机的病房无线呼叫系统设计

为解决传统病房有线呼叫系统存在的布线复杂、易出故障、维修不便、不能在现有床位基础上及时增加新床位信息等问题,提出了无线呼叫系统设计。采用STC89C52系列单片机作为主控芯片,nRF905作为无线收发的核心芯片,并配以相应的LCD显示屏和声光报警器,设计出了无线病房呼叫系统。结果表明,该系统可靠传输距离达90 m以上,具有一定的抗干扰性,且可以临时方便增加床位显示信息,能够满足医院的临时实际需求。该系统性能稳定,操作简便,可以有效代替传统有线呼叫系统。     

Research on technology of desktop virtualization based on SPICE protocol and its improvement solutions

Increasingly mature cloud computing technology promotes virtual desktop technology, which can solve many problems existing in traditional computing models. However, virtual desktop solutions introduce the thorny problem of how to deliver a real desktop experience to users, as if they are using it locally, especially when playing video. The SPICE （simple protocol for independent computing environments） virtual desktop solution provides several image compression algorithms to address this problem with the purpose of making virtual desktops as real as possible. Although different compression algorithms can contribute their own abilities to different images to a large extent, switching between them is a big problem that consumes a large amount of resources to detect the different type of image and also causes jitter of the virtual desktop. This paper proposes a new solution, called SPICEx, using the JPEG2000 compression algorithm with dynamic compression ratios to solve the problem and finally validates that the performance is better than that of SPICE. With better quality of user experience and also reducing bandwidth consumption, SPICEx solution is meaningful in virtual desktop fields and can be widely used.     

An SVD-based adaptive robust speech steganography using MDCT coefficient

Multimedia Tools and Applications - Speech is one of the essential ways of communication. The study of speech steganography provides great value in information security. To improve imperceptibility...     

高分2号图像业务化大气校正查找表的设计与实现

为实现高分2号图像(GF2)业务化大气校正,利用矢量6S模型(6SV)将辐射传输散射与吸收进行分离计算,其中散射部分采用涵盖各种大气模式、气溶胶类型、成像几何等条件下的大气校正查找表(look-up tables,LUTs)表示,大气吸收部分采用6SV拟合计算的6种大气模式下大气透过率的经验公式表示,这种处理有效简化了查找表大小.在内存4 GB、主频3.10 GHz条件下,通过比较基于本查找表方法和基于FLAASH大气校正软件对北京地区一景GF2数据处理.结果表明:以6SV模型直接大气校正法结果作为真值,两者的绝对误差分别为0.8%和2.6%,处理时间分别为77 s和240 s,该大气校正查找表在处理精度和效率更加适合业务化大气校正.     

液压系统进、旁油路联合调速回路分析

在定量液压泵供油的系统中给出进、旁油路联合调速的回路,通过对2种进、旁油路联合调速的定量分析,推导出理论计算依据,得出这2种进、旁油路联合调速的调速特点。     

Oxidation behavior and mechanism of aluminum oxynitride (AlON) at elevated temperatures

The oxidation behavior and mechanism of aluminum oxynitride (AlON) powder exposed to air at elevated temperatures between 800°C and 1300°C was investigated by X-ray diffractometry (XRD), scanning electron microscope (SEM), electron spin resonance (ESR), nuclear magnetic resonance (NMR), and simultaneous thermogravimetry, differential thermal analysis, and mass spectrometry techniques (TG-DTA-MS). The weight of AlON gradually increases to a maximum value at 1150°C and then decreases with further heating. Meanwhile, AlON powder undergoes chemical changes, as evidenced by lattice expansion, and turns eventually into alumina. ESR spectra reveal the occurrence of lone pair electrons in the oxidized products and the intensity of corresponding resonance signal increases before disappearing with the increase in temperature. Combined with the results of NMR and TG-DTA-MS, the measured data suggest that Al-N in [AlO₃N] tetrahedron and [AlO₅N] octahedron are gradually oxidized into Al-O-N group with lone pair electrons, which causes continuous weight gain and lattice expansion. Further oxidation at higher temperatures results in alumina and N₂.     

高钒高速钢碳化钒形态的数值化分析

针对碳化钒的不同形态,设计出定量分析软件,并利用形状因子K,实现了高钒高速钢不同碳化物形态数值化处理,当K介于0.785～1.000之间碳化钒形态为团球状;K≤0.223,碳化钒呈开花状.高钒高速钢当碳含量达到4.2%时,K为0.86和当量直径D为0.78μm,碳化物呈团球状均匀分布.     

中厚板轧机工作辊失效分析及对策

介绍了济钢中厚板厂使用国外高镍铬和高铬工作辊的主要失效形式 ,并对该工作辊的断裂和裂纹产生原因进行了分析 ,同时针对所存在的问题提出了对策和具体改进措施。