Quality of Service Improvement for High-Speed Railway Communications

With the fast development of highspeed railways, a call for fulfilling the notion of communication at ＂anytime, anywhere＂ for high-speed train passengers in the Train Operating Control System is on the way. In order to make a realization of that, new railway wireless communication networks are needed. The most promising one is the Long Term Evolution for Railway which will provide broadband access, fast handover, and reliable communication for high mobility users. However, with the increase of speed, the system is subjected to high bit error rate, Doppler frequency shift and handover failure just like other system does. This paper is trying to solve these problems by employing MIMO technique. Specifically, the goal is to provide higher data rate, higher reliability, less delay, and other relative quality of services for passengers. MIMO performance analysis, resource allocation, and access control for handover and various services in a two-hop model are proposed in this paper. Analytical results and simulation results show that the proposed model and schemes perform well in improving the system performances.     

Calculation of all cubic single-crystal elastic constants from single atomistic simulation: Hydrogen effect and elastic constants of nickel

Previous direct methods for evaluating all elastic constants require separate molecular dynamics runs with different loads. Here, we show that only a single run is enough to evaluate all elastic constants of cubic crystals. We evaluate the temperature dependence of all elastic constants of Ni to check the reliability of the embedded-atom method potential developed by Angelo et al. and study the effects of hydrogen on elastic constants.     

派生诉讼中的取证与举证问题研究

派生诉讼中的原告和被告存在严重的信息不对称,这导致原告举证困难.对涉及举证问题的前置请求阶段和审判阶段均从举证责任归属、举证程度要求以及获取证据途径几个方面进行了研究,力求在便利股东提起派生诉讼的同时对公司的经营管理不造成过度的干扰.     

Study on the dynamic resistance switching properties of NiO thin films

The resistive switching properties of NiO-based memory cells were investigated utilizing test structures with a storage contact size of 150 nm in diameter. Two well defined stable resistance states with high OFF/ON ratios were achieved by unipolar operation. Detailed electrical characterizations with respect to nonvolatile memory applications reveal fast (< 300 ns) and reliable switching performance at low operating voltages (< 2.5 V). Promising results of endurance data (> 1000 cycles) and retention tests up to 110 °C show excellent stability and indicate the competitive potential with respect to established nonvolatile memory devices.     

纯棉纬弹织物尺寸稳定性的控制

纯棉纬弹织物性能优异，但在染整加工过程中尺寸稳定性不易控制，造成成品门幅不稳定，甚至达不到客户要求，本文基于实验及生产实践，合理选择坯布密度及门幅，正确控制前处理工艺条件，灵活制订后处理工艺路线及工艺条件，既保证外观，弹性伸长率等性能符合要求，又获得满意的纬向尺寸稳定性。     

弹力机织物的结构参数对其保形性的影响

在对氨纶弹力机织物多项参数进行测试的基础上，采用多元线性回归方法，分析了织物结构参数与保形性的关系，研究结果表明：纱线氨纶含量对织物的保形性影响最大，其次为织经和织物紧度。     

Providing Security and Interoperation of Heterogeneous Systems

Interoperation and information sharing among databases independently developed and maintained by different organizations is today a pressing need, if not a practice. Governmental, military, financial, medical, and private institutions are more and more required to become part of a distributed infrastructure and selectively share their data with other organizations. This sharing process inevitably opens the local system to new vulnerabilities and enlarges the space of possible threats to the data and resources it maintains. As a complicating factor, in general, data sources are heterogeneous both in the data models they adopt and in the security models by which protection requirements are stated. We present a modeling and architectural solution to the problem of providing interoperation while preserving autonomy and security of the local sources based on the use of wrappers and a mediator. A wrapper associated with each source provides a uniform data interface and a mapping between the source's security lattice and other lattices. The mediator processes global access requests by interfacing applications and data sources. The combination of wrappers and mediator thus provides a uniform data model interface and allows the mapping between restrictions stated by the different security policies. We describe the practical application of these ideas to the problem of trusted interoperation of health care databases, targeted to enforcing security in distributed applications referring to independent heterogeneous sources protected by mandatory policy restrictions. We describe the architecture and operation of the system developed, and describe the tasks of the different components.     

Non-visual interaction with graphs assisted with directional-predictive sounds and vibrations: a comparative study

Blind and visually impaired students need special educational and developmental tools to allow them to interact with graphic entities on PDA and desktop platforms. In previous research, stylus movements regarding the hidden graph were sonified with three directional-predictive sound (DPS) signals, taking into account an exploration behavior and the concept of the capture radius. The results indicated that the scanpaths were by 24–40% shorter in length and task completion times decreased by 20–25%. The goal of the study presented in this paper was to measure and compare the subjective performance recorded with directional-predictive vibrations (DPV) regarding the subjective performance achieved when the hidden graphic images were explored with DPS. The study also aimed to find out which kind of feedback cues would require less cognitive efforts in interpreting their meaning. The prototype of vibro-tactile pen with embedded vibration motor was used to produce DPV instead of sounds. The performance of eight blindfolded subjects was investigated in terms of the number of both feedbacks used and the time spent to complete non-visual inspection of the hidden graphs. There was a statistically significant difference between the average number of DPS and vibrations and task completion time taken by the players to discover the features of hidden graphs being explored with different capture radius. The experimental findings confirmed the beneficial use of DPS signals in the task when cross-modal coordination should benefit the user in the absence of visual information when compared with DPV patterns.     

非洲：机遇的土地

非洲经济在过去几年中有了整体的回升，电信的发展为非洲的振兴带来了希望。非洲各国的电信业正在发生变革，国有电信运营公司开始走向私有化，电信市场引入竞争。在国家通信缺乏的情况下，率先引入竞争的移动通信发展迅速，特别是预付费业务成为移动通信发展的最大驱动力。在外国企业介入本地运营市场的同时，本土的电信公司也迅速成长起来并赢得了自己的市场空间。另外，在Internet接入方面，非洲落后于全世界多数地区，尚在等待起飞的良机。总之，非洲是机遇之地，但非洲需要付出巨大的努力才能获得真正的发展。     

Detection of shock-wave-induced internal stresses in Cu-Al-Ni shape memory alloy by means of acoustic technique

1. The present results indicate that the stress-induced β₁→γ₁′ martensitic transformation occurs for an impact duration of 2 × 10⁻⁶ s. This time interval appears to be sufficient also for the subsequent deformation of the γ₁′ martensitic phase to occur.2. A structure memory effect has been found: Cu-Al-Ni austenitic crystals, shock-loaded at room temperature to induce γ₁′–martensite, recall during subsequent temperature-induced martensitic transformation the martensitic variant structure (elastic properties) formed under the shock loading.3. Elastic properties of quenched β₁′ and γ₁′ crystals of the Cu-Al-Ni system are extremely sensitive to the shock-wave loading. Mechanisms of these effects, as well as of the structure memory effect, include the generation of internal stresses due to the high elastic anisotropy of the martensitic phases. These internal stresses either change the distribution of martensitic variants or govern the formation of the martensitic variant structure during the temperature-induced martensitic transformation. The generation of high internal stresses by impact loading of the β₁′ martensitic phase is also detected by several anelastic phenomena.4. In contrast to elastic and anelastic properties, transformation temperatures are insensitive to the impact loading, pointing to the difference of structural elements responsible for the anelastic effects and for the interval and hysteresis of the thermoelastic martensitic transformation.