Mechanism of brittle-ductile transition of a glass-ceramic rigid substrate

The hardness, elastic modulus, and scratch resistance of a glass-ceramic rigid substrate were measured by nanoindentation and nanoscratch, and the fracture toughness was measured by indentation using a Vickers indenter. The results show that the hardness and elastic modulus at a peak indentation depth of 200 nm are 9.04 and 94.70 GPa, respectively. These values reflect the properties of the glass-ceramic rigid substrate. The fracture toughness value of the glass-ceramic rigid substrate is 2.63 MPa·m1/2. The material removal mechanisms are seen to be directly related to normal force on the tip. The critical load and scratch depth estimated from the scratch depth profile after scratching and the friction profile are 268.60 mN and 335.10 nm, respectively. If the load and scratch depth are under the critical values, the glass-ceramic rigid substrate will undergo plastic flow rather than fracture. The formula of critical depth of cut described by Bifnao et al. is modified based on the difference of critical scratch depth     

Metallogenic epoch and genesis of the gold deposits in Jiaodong Peninsula, Eastern China: a regional review

Gold deposits are characterized by multi-sources, superimposition, large scale and temporal-spatial concentration in Jiaodong Peninsula, Eastern China. In this paper, we review the history and the development of the study on metallogenic chronology and genesis of gold deposits, summarize the main features of superimposed metallogenesis, provide evidence of the Mesozoic complex metallogenic system, and point out some problems for further research of Jiaodong gold deposit cluster from a regional view. Although gold deposits are different in genetic types, ore-forming materials and geological settings, our research indicates that the accumulation and emplacement of the ore-forming materials are temporally-spatially concentrated on a large scale, and the main metallogenic epoch of Jiaodong gold deposits was concentrated in Mesozoic. Metallogenic chronology and geological-geochemical data indicate that there are two periods of gold mineralizations occurred in 130-110 Ma and 90-80 Ma respectively in Jiaodong ore cluster. The gold deposit cluster results from the superimposition of the polygenetic mineralization, and further study is needed to investigate the formation and evolution of the Mesozoic complex metallogenic system.     

A TTP-Independent Watermarking Protocol Based on Commutative Cryptosystem for Copyright Protection in E-Commerce

For the purpose of deterring unauthorized duplication and distribution of multimedia contents in e-commerce, some Buyer-seller watermarking protocols which combine of traditional watermarking and fingerprinting techniques have been proposed, However, previous protocols have potential risk from trust third party （TTP） because all entities （including multi-buyers and multi-sellers） mentioned in protocol construct a star tupology like connection, in which the watermark certification authority （WCA） serves as the central point in the interaction and therefore its availability probably turns out to be the vital bottleneck of reliability and efficiency to the whole system. Secondly, WCA holds entire information about watermark used hy Buyers so that an innocent Buyer can he found as guilty if WCA collude with the Seller. In this paper, we propose a watermarking protocol to address the problems using cryptographic technologies in phase of watermark generation. The resuh is a TTP-independent and collusion-secure buyer-seller watermarking protocol.     

显微组织对无限冷硬铸铁轧辊热疲劳性能的影响

文章介绍在无限冷硬铸铁轧辊上切取板状热疲劳试样,在自制的热疲劳试验机上进行了冷热循环实验,研究了显微组织对无限冷硬铸铁热疲劳裂纹萌生及扩展的影响.结果表明,热疲劳裂纹在石墨尖端处、珠光体基体及共晶碳化物中萌生;热疲劳裂纹主要在钢基体与共晶莱氏体界面处、钢基体内扩展及穿越共晶碳化物.     

An Energy-Saving Task Scheduling Strategy Based on Vacation Queuing Theory in Cloud Computing

High energy consumption is one of the key issues of cloud computing systems. Incoming jobs in cloud computing environments have the nature of randomness, and compute nodes have to be powered on all the time to await incoming tasks. This results in a great waste of energy. An energy-saving task scheduling algorithm based on the vacation queuing model for cloud computing systems is proposed in this paper. First, we use the vacation queuing model with exhaustive service to model the task schedule of a heterogeneous cloud computing system.Next, based on the busy period and busy cycle under steady state, we analyze the expectations of task sojourn time and energy consumption of compute nodes in the heterogeneous cloud computing system. Subsequently, we propose a task scheduling algorithm based on similar tasks to reduce the energy consumption. Simulation results show that the proposed algorithm can reduce the energy consumption of the cloud computing system effectively while meeting the task performance.     

Impact of urbanization on changes in temperature extremes in Beijing during 1978–2008

To quantify the impact of urbanization on changes in observed surface air temperature and extremes, a homogenized dataset of daily mean, maximum and minimum temperature （Trn, Trnax and Train） observations at 20 stations in Greater Beijing （GBJ） from 1978 to 2008 is analyzed. In contrast with previous studies, a cluster analysis is done to objectively classify observing stations into four categories （urbanized, suburban, rural and mountain）, which is checked with remote-sensing night-light images since the 1990s. At urbanized sites, there is an added warming trend in annual mean Tm representing an average of 10.9% （up to 18.4% or 0.12℃/decade at the most strongly influenced site） of overall warming. Corresponding contributions for Train are 12.7% （up to 20.8% or 0.19℃/decade） and 24% for diurnal temperature range DTR （up to 37.4% or 0.149℃/decade） over the last three dec- ades. Although it has not had a significant impact on daytime records （Tmax）, urbanization has enhanced the increasing （decreasing） trend of extremely warm （cold） nights by an average of 12.7% or 2.07 d/decade （29.0% or 5.06 d/decade） at the urbanized sites since the 1970s.     

Immune Algorithm for Selecting Optimum Services in Web Services Composition

0 IntroductionInha rveec eenmte yregaerds a,sa t ghreo Iwnitnegrn neut mdbeverel oofps W aetb a S fearsvtic reast e( .W TSshe)Webis nowevolving into a distributed device of computationfroma collection of information resources[1]. But individualWeb services usually cannot satisfy some customers’require-ments ,so we always needtointegrate existingservices to cre-ate newvalue-added composed services .The process model underlying a composite identifies thefunctionalities required by the servic…     

Thermal effect of the cable-stayed bridge tower

0　IntroductionXiantaoHanjiangRiverHighwayBridgelocatesonnorth westsuburbofXiantaocity ,crossesovertheHanjiangRiv er.Thecable stayedbridgeisasingle towersystemwiththespansof (5 0 + 82 + 180 )m .Thenon symmetricalstructureisusedheresothatthemainpiercankeepoffthemainchannel.Thesectionofthegirderisnotconstantinorderthatthedeadloadcanbeinbalancealthoughthespansaredifferent.Thedeckwidthis 2 3m (notincludingthewidthofthecablelane) ,laterallayoutisthatofdouble directionfour lanewithoutsidewalk ,b…     

挠性航天器大角度机动的振动抑制控制

建立了带变速控制力矩陀螺群的挠性航天器的动力学模型,应用误差四元数来描述姿态运动,将星体大角度姿态机动问题转化为误差四元数的调节问题.针对挠性航天器三轴同时姿态机动时挠性附件的振动抑制问题,提出了基于动态输出反馈控制的振动抑制方法,设计了仅利用姿态四元数而无需以角速度测量、挠性变形位移及速率测量作为反馈的动态控制规律.基于Lyapunov方法证明了所设计的动态控制器保证了姿态的渐近稳定和模态振动的衰减.基于Matlab/Simulink进行了仿真验证,结果表明了所提出的控制方法的可行性和有效性.     

机动天基平台惯性/天文组合导航的研究

为了实现机动天基平台的长时间、高精度和低成本自主导航,采用了低精度惯性导航系统和天文导航系统进行组合。以扩展卡尔曼滤波算法为基础,通过建立系统状态方程和量测方程,并进行量测方程的线性化,将捷联惯导和星敏感器分别测得的姿态信息进行数据融合,估计出组合导航系统的误差状态量,从而修正捷联惯导系统的导航参数。仿真结果表明,在1000s内,平台姿态角误差稳定收敛在20?,定位误差优于纯惯导解算,证实了该方案的实用性。