XML queries and algebra in the Enosys integration platform

We describe the Enosys XML integration platform, focusing on the query language, algebra, and architecture of its query processor. The platform enables the development of eBusiness applications in customer relationship management, e-commerce, supply chain management, and decision support. These applications often require that data be integrated dynamically from multiple information sources. The Enosys platform allows one to build (virtual and/or materialized) integrated XML views of multiple sources, using XML queries as view definitions. During run-time, the application issues XML queries against the views. Queries and views are translated into the XCQL algebra and are combined into a single algebra expression/plan. Query plan composition and query plan decomposition challenges are faced in this process. Finally, the query processor lazily evaluates the result, using an appropriate adaptation of relational database iterator models to XML. The paper describes the platform architecture and components, the supported XML query language and the query processor architecture. It focuses on the underlying XML query algebra, which differs from the algebras that have been considered by W3C in that it is particularly tuned to semistructured data and to optimization and efficient evaluation in a system that follows the conventional architecture of database systems.     

Automated optimal design of a two-stage helical gear reducer

The design space of multi-stage transmissions is usually very large and heavily constrained. This places significant demands on the algorithm employed to search it, but successful optimization has the potential to yield considerably better designs than conventional heuristics, at the same time enabling a better understanding of the trade-offs between various objectives (such as service life and overall weight). Here we tackle a two-stage helical gear transmission design problem (complete with the sizing and selection of shafts, bearings, housing, etc.) using a two-phase evolutionary algorithm in a formulation that can be extended to include additional stages or different layouts.     

基于一种优化算法的大坝变形性态模型(英文)

大型水库大坝安全监测系统的监测数据可用来建立多种重要的结构安全状态参数下的预测模型。提出了一种基于基因算法的非线性、退化性态模型。以大坝顶部的上、下游位移作为状态参数为例,以倒垂数据作为数据输出,库水位和气温以及前7,15,30和60d的平均值作为外在影响因子。选取坝高58m、坝长190m的Herculane拱坝的332个数据集作为输入-输出参数,时间序列为2000年1月-2007年6月。从这个数据序列获得回归系数,并进行检验确认。同理,可得其他参数下性态预测模型。这些模型能够解释实时监测中的数据,并能迅速辨识某些情况下的大坝安全潜在风险。     

The concept of the bacterial battery

Electrochemical impedance spectroscopy (EIS) has been used to characterize the electrochemical properties of Al 2024 and pure copper in Luria Bertani (LB) medium and in the same medium containing Shewanella oneidensis MR-1 (ATCC 700550). Potentiodynamic polarization curves have been used to determine the power output of the Al 2024/Cu battery in the two media. For pure Cu significant changes of the impedance spectra have been found in the presence of the bacteria. The spectra resembled those usually observed for polymer-coated metals. Another unexpected result was the increase of the cell voltage and the maximum power output of the Cu/Al 2024 cell with increasing exposure time in the presence of MR-1.     

Superparamagnetic nanomagnetites modified with histidine and tyrosine

Magnetite nanoparticles coated with tyrosine and histidine were synthesized by in situ decomposition of the precursors–coordination compounds containing the aminoacids as ligands. All of the obtained compounds were characterized using infrared spectroscopy (FTIR), X-ray diffraction, Mössbauer spectroscopy, magnetic and thermal measurements. Data demonstrate the presence of the aminoacids chemisorbed on the surface of magnetite nanoparticles and their superparamagnetic character.     

浅析称重传感器和仪表的故障检测方法

通过以下这些查明故障的步骤，一个技术员应该能够以较有效的方式解决大多数秤的问题。     

Fundamental studies on large area Cu(In,Ga)Se2 films for high efficiency solar cells

This work reports the growth and characterization of thin films of Cu(In,Ga)Se₂ (CIGS), which were grown by sequential sputtering, electrodeposition, and physical vapor deposition. Photovoltaic cells have been fabricated using these films with CdS heterojunction partners and the performance has been characterized. The effect of annealing conditions (temperature and duration) on the CIGS film microstructure and corresponding device performance has been investigated. Structure-property correlations were made using diffraction studies and Rietveld analysis. SEM studies were carried out to understand the effect of microstructure of the CIGS films on the solar cell efficiency. Cell efficiencies in excess of 10% have been achieved by using optimized annealing conditions. In addition, the optical properties of the sputtered CIGS films were characterized using variable angle spectroscopic ellipsometry and sputtered CIGS films were found to have optimum band gap.     

Optimal superior-order curvature-corrected voltage reference based on the weight difference of gate-source voltages

A new curvature-correction technique for improving the temperature behavior of a CMOS voltage reference will be presented. The reducing of the temperature coefficient for the reference voltage will be realized compensating the nonlinear temperature dependence of the gate-source voltage for a MOS transistor working in weak inversion with the difference between two gate-source voltages. These MOS transistors are biased at drain currents with different temperature dependencies (PTAT and PTAT ^α, respectively), α parameter being selected to the optimal value for the implementing technology. The PTAT voltage generator will be designed using an original Offset Voltage Follower block, with the advantage of a reduced silicon occupied area as a result of replacing classical resistors by MOS active devices. SPICE simulation reports TC = 1.95 ppm/K for an extended temperature range, 273 K < T < 363 K, without considering the parameters spread. The circuit is compatible with low-power low-voltage designed, having a maximal power consumption of 0.4 μW for a minimal supply voltage of 1.1 V.     

Flow visualization of natural convection in a vertical channel with asymmetric heating

A dynamical study of the flow in an asymmetrically heated vertical plane channel has been conducted experimentally. Experiments were carried out in water for three aspect ratios and for a range of modified Rayleigh numbers corresponding to the boundary layer flow regime. The flow dynamics were characterized by means of visualization techniques based on laser tomography using discrete and continuous tracers. Flow visualizations were carried out in the plane of symmetry of the channel along its entire height. The investigations focused more specifically on the influence of the aspect ratio and the modified Rayleigh number on the flow structure both in steady-state regime and during the transitional phase occurring just after the start of the heating. An upward boundary layer flow is found near the heated wall, accompanied by a reverse flow developing on the opposite side from the top open-end of the channel. In steady state, the reverse flow takes the form of an elongated eight-shaped structure with two main recirculation cells. The length of the upper cell of the eight-shape structure decreases with increasing aspect ratio. For a fixed aspect ratio, the increase in modified Rayleigh number results in a decrease in the penetration of the reverse flow. During the transient the flow structure is shown to evolve from a single cell to a final eight-shaped structure.