A mediator-based approach for integrating heterogeneous multimedia sources

In many applications, the information required by the user cannot be found in just one source, but has to be retrieved from many varying sources. This is true not only of formatted data in database management systems, but also of textual documents and multimedia data, such as images and videos. We propose a mediator system that provides the end-user with a single query interface to an integrated view of multiple heterogeneous data sources. We exploit the capabilities of the MOMIS integration system and the MILOS multimedia data management system. Each multimedia source is managed by an instance of MILOS, in which a collection of multimedia records is made accessible by means of similarity searches employing the query-by-example paradigm. MOMIS provides an integrated virtual view of the underlying multimedia sources, thus offering unified multimedia access services. Two features are that MILOS is flexible—it is not tied to any particular similarity function—and the MOMIS’s mediator query processor only exploits the ranks of the local answers.     

Stability Problems in Soil‐Structure Interfaces: Experimental Observations and Numerical Study

This article presents experimental results of tests on soil‐structure interfaces carried out on a new “ring simple shear” apparatus specially developed at Ecole Nationale des Ponts and Chaussées, Paris, for such studies. In this apparatus strain localization takes place at or near the surface of the rotating steel drum that forms the soil‐structure interface. Depending on the conditions of tests, in terms of surface roughness, special instrumentation is capable of recording local as well as global response. Three tests on Hostun gravel at different confining radial pressures have been conducted and a deviatoric hardening model with nonassociated flow rule has been adopted for their numerical simulations. The point of inception of strain localization based on various theoretical considerations has been discussed and experimentally verified. The post‐peak behavior is simulated by employing a homogenization technique in which the soil sample is treated as a composite material consisting of a shear band surrounded by intact material. A deviatoric strain softening model has been adopted for the shear band. It is shown that the mechanism of failure and the response of the soil sample is reasonably well simulated. Although there are some concerns regarding the homogeneity of the sample, the post‐peak stage and the overall mechanical response of gravel‐steel interface are rather well reproduced.     

Synthesis, morphology and compositional evolution of silicon nanowires directly grown on SnO(2) substrates

We here propose an all-in situ method for growing vapor-liquid-solid (VLS) silicon nanowires (SiNWs) directly on SnO(2) substrates in a plasma-enhanced chemical vapor deposition system. The tin catalysts are formed by a well-controlled H(2) plasma treatment of the SnO(2) layer. The lowest temperature for the tin-catalyzed VLS SiNWs growth in a silane plasma is ～250?°C. The effects of substrate temperature and H(2) dilution of silane on the morphology and compositional evolution of the SiNWs were systematically investigated. The catalyst content in the SiNWs can be effectively controlled by the deposition temperature. Moreover, enhanced absorption (down to ～1.1?eV) is achieved due to the strong light trapping and anti-reflection effects in the straight and long tapered SiNWs.     

Polarization properties of oblique incidence scanning tunneling microscopy-tip-enhanced Raman spectroscopy

We used scanning tunneling microscopy-tip-enhanced Raman spectroscopy (STM-TERS) to study the polarization properties of near-field scattering on a crystalline material as well as on a dye adsorbate. The measurements on a (111)-oriented c-Si sample were found to be well described by a recently proposed model for TERS and allowed for a characterization of the polarization properties of the tips used. The tip enhancement was stronger for excitation radiation having a field component along the tip axis for both types of samples. A non-negligible enhancement was also found for the field component perpendicular to the tip axis.     

Biomass fueling of a SOFC by integrated gasifier: Study of the effect of operating conditions on system performance

Biomass gasification can be efficiently integrated with Solid Oxide Fuel Cells (SOFCs) to properly deploy the energy content of this renewable source and increasing the ratio of electric to thermal converted energy. The key objective of this work is to analyze in a systematic and wide process the integration of a biomass gasifier process with the SOFC operation. In particular the work aims at identifying the role of SOFC H₂ utilization as a basic parameter to maximize the system output and avoid gasifier bad operation issues such as tar production and carbon deposition. An efficient simulation framework is used to that purpose allowing for a detailed analysis of the influence of key driving parameters. The performance of the integrated system is thoroughly analyzed in the range of 1–2 kW electric power by also varying the input biomass characteristics in terms of Moisture Content (MC). Results show how a variation of the SOFC H₂ utilization, a parameter whose effects are also correlated with the gasifier air requirement, affects electrical power output also depending on the biomass Moisture Content.     

Neoprene-concrete friction relationships for seismic assessment of existing precast buildings

In Italy many precast industrial buildings built between 1950s and 1970s present beam-column connections with strength coming from neoprene-concrete friction. Numerical studies recently performed by the authors confirm that, in order to determine the seismic vulnerability of such structures, a reliable value of the neoprene-concrete friction coefficient has to be known. Technical bibliography provides many and different values for this coefficient; consequently, in order to define reliable values, a specific experimental campaign is carried out. Three types of experimental tests are performed: tests on neoprene hardness, tilting tests and pulling tests; in the last case, the specimen is also axially loaded.Tilting tests provide a value of the mean friction coefficient equal to about 0.5, with very low C.O.V.. Pulling tests underline a friction strength dependence on axial load and, in particular, a decrease in the friction coefficient as the axial load increases; a relationship for compressive stress-neoprene-concrete friction coefficient is proposed.     

消除背景照明的跨导同步放大

光传感器可用于很多重要领域,从消费电子产品中的环境光测量与相机曝光控制．到光谱吸收分光计、热成像IR（红外）探测仪以及双色高温探测仪等科学仪器。例如．在光学分光应用中．在确定材料与设备特性时．关键是对探测光束强度的正确测量。必须消除DC或极低频率背光所导致的任何影响。另外．为了增加SNR（信噪比）．可以采用窄带、相位敏感或锁定探测技术．对探测光源进行机械式斩波或调制。     

AMnO3 (A=La, Nd, Sm) and Sm1−xSrxMnO3 perovskites as combustion catalysts: structural, redox and catalytic properties

Catalytic combustion of methane has been investigated over AMnO₃ (A = La, Nd, Sm) and Sm_1−xSr_xMnO₃ (x = 0.1, 0.3, 0.5) perovskites prepared by citrate method. The catalysts were characterized by chemical analysis, XRD and TPR techniques. Catalytic activity measurements were carried out with a fixed bed reactor at T = 623–1023 K, space velocity = 40 000 N cm³ g⁻¹ h⁻¹, CH₄ concentration = 0.4% v/v, O₂ concentration = 10% v/v.

Specific surface areas of perovskites were in the range 13–20 m² g⁻¹. XRD analysis showed that LaMnO₃, NdMnO₃, SmMnO₃ and Sm_1−xSr_xMnO₃ (x = 0.1) are single phase perovskite type oxides. Traces of Sm₂O₃ besides the perovskite phase were detected in the Sm_1−xSr_xMnO₃ catalysts for x = 0.3, 0.5. Chemical analysis gave evidence of the presence of a significant fraction of Mn(IV) in AMnO₃. The fraction of Mn(IV) in the Sm_1−xSr_xMnO₃ samples increased with x. TPR measurements on AMnO₃ showed that the perovskites were reduced in two steps at low and high temperature, related to Mn(IV) → Mn(III) and Mn(III) → Mn(II) reductions, respectively. The onset temperatures were in the order LaMnO₃ > NdMnO₃ > SmMnO₃. In Sm_1−xSr_xMnO₃ the Sr substitution for Sm caused the formation of Mn(IV) easily reducible to Mn(II) even at low temperature. Catalytic activity tests showed that all samples gave methane complete conversion with 100% selectivity to CO₂ below 1023 K. The activation energies of the AMnO₃ perovskites varied in the same order as the onset temperatures in TPR experiments suggesting that the catalytic activity is affected by the reducibility of manganese. Sr substitution for Sm in SmMnO₃ perovskites resulted in a reduction of activity with respect to the unsubstituted perovskite. This behaviour was related to the reduction of Mn(IV) to Mn(II), occurring under reaction conditions, hindering the redox mechanism.     

使用"封装上系统"智能器件为经济型机顶盒供电

电子设备比几年前增加了许多功能，“片上系统”成为满足更高的电路复杂性和可靠性以及降低成本的需求的解决方案。“片上系统”是指在同一个封装内组装两个集成电路的封装方法。这种新的封装方法满足了所有的单片集成电路解决方案无法满足的应用需求，特别是那些功率要求不断提高而专用的热设计的成本不能提高的交流-直流变流器、大功率系统和高压系统。