用混合弹性模型解决图象变形匹配问题

由于用传统的刚体匹配方法难以解决待匹配图象之间的结构差异 ,因此需要引入变形模型来进行图象的非刚体匹配 .为此提出了一种利用混合弹性模型 (HEM)来解决图象变形匹配问题的新方法 .该方法不需要预先提取图象的特征 ,而是直接利用匹配图象之间的灰度信息来实现图象之间的匹配 .匹配时 ,首先通过基于主轴的方法来实现两幅图象之间的全局仿射匹配 ;然后利用线性弹簧网模型来求取两幅图象之间的相关性 ,并进一步利用薄板样条模型来实现两幅图象的变形匹配 .该方法在匹配过程中还采取了多分辨率匹配策略 ,合成图象和医学脑图象的实验结果表明 ,该方法是有效的     

Stress transmission through three-dimensional granular crystals with stacking faults

We explore the effect of stacking fault defects on the transmission of forces in three-dimensional face-centered-cubic granular crystals. An external force is applied to a small area at the top surface of a crystalline packing of granular beads containing one or two stacking faults at various depths. The response forces at the bottom surface are measured and found to correspond to predictions based on vector force balance within the geometry of the defects. We identify the elementary stacking fault as a boundary between two pure face-centered-cubic crystals with different stacking orders. Other stacking faults produce response force patterns that can be viewed as resulting from repetitions of this basic defect. As the number of stacking faults increases, the intensity pattern evolves toward that of an hexagonal-close-packed crystal. This leads to the conclusion that the force pattern of that crystal structure can be viewed as the extreme limit of a face-centered-cubic crystal with a stacking fault at every layer.This work was supported by NSF-CTS 0090490 and by the NSF MRSEC Program under DMR-0213745. MJS acknowledges support by the University of Chicago MRSEC Summer 2002 REU program.     

Transformation of the EFQM approach from business towards operations excellence

The purpose of this paper is to provide an enabler-based approach for a supervised self-assessment of operations excellence (OsE). Based on the latest approaches of excellence in operations from the literature as well as on the philosophy of the EFQM model, an OsE working definition was developed. In contrast to operational excellence (OE), which deals exclusively with the optimization of result driven processes, OsE promotes the enhancement of operation-specific enablers and linked results. The evaluation of crucial cause–effect relationships of relevant enabler and result criteria supports the determination of a company’s capability to achieve sustainability and excellence in terms of its operations. To foster a methodical integration of OsE in organizations, a phase model for a systematic assessment process was designed and verified with 24 companies in the Austrian machinery and metalware industries.     

Loss characteristics in coplanar propagation waveguides fabricated on IIa diamond substrates

The properties of coplanar propagation waveguides (CPW) on various diamond substrates are investigated. We demonstrate that on such material, the physico-chemical surface treatments may be fundamental to obtain good microwave properties. CPW were processed on single crystal CVD diamond samples that were grown either as bulk substrate or as a thin epitaxial layer on a type IIa natural diamond substrate. These CPW exhibited losses around 0.15 dB/mm at 10 GHz and 0.25 dB/mm at 40 GHz. Temperature-dependant measurements imply that structural defects may involve parasitic current conduction. The loss angle tangents of both samples have then been extracted from a quasi-TEM numerical modelling, they are about 0.025 for each kind of substrate.     

AlGaN/GaN MISHEMT with hBN as gate dielectric

Metal/Insulator/Semiconductor AlGaN/GaN High Electron Mobility Transistors (MISHEMTs) on sapphire substrate were fabricated with hexagonal Boron Nitride (hBN) thin film as gate dielectric. The hBN thin film, deposited by MW-PECVD, is an insulator permitting to obtain a low leakage current gate, an interface state density as low as 5 × 1011 cm^? 2 eV^? 1 for hBN/AlGaN interface and low roughness surface less than 0.4 nm. HBN thin film is deposited to have optical c-axis oriented weakly tilted to the perpendicular at the AlGaN barrier surface and to increase the lateral electrical resistivity. DC measurement on MISHEMT exhibits promising performance for microwave power devices associated to a good gate charge control in enhancement mode.     

Prognose der Sorptionskinetik organischer Schadstoffe in heterogenem Aquifermaterial

A model for the simulation of kinetic sorption processes in heterogeneous aquifer material is presented. Sorption kinetics is responsible for the long persistence of many organic contaminants in the subsurface. Therefore, reliable model predictions of these processes are of major importance concerning, for instance, the design of efficient remediation strategies. The modeling approach presented here recognizes sorption kinetics as retarded diffusion within the intra-particle pore space and, in particular, takes into account the sedimentological and petrographical composition of the aquifer material. This is in accordance with results from laboratory experiments quantifying sorption/desorption processes. For solving the model equations a finite-difference scheme is applied which incorporates several features proven to be relevant in practical model applications (mass balance, flexible choice of boundary conditions, easy handling). The simulation results shown here focus on the impact of aquifer heterogeneity (lithological composition, grain size distribution) on sorption and desorption kinetics of organic contaminants. Furthermore, this approach can be straightforwardly coupled to existing software for simulating multi-dimensional solute transport.     

Field screening of waterborne petroleum hydrocarbons by thickness shear-mode resonator measurements

An inexpensive, field-portable sensor for direct, aggregate determination of aqueous petroleum hydrocarbons (PH) down to sub-ppm levels was developed. The basis of this sensor was an unusual, highly nongravimetric frequency response of 10 MHz (series fundamental) AT-cut quartz crystals when coated with rubbery silicone films. The response depended linearly and reliably on the total concentration of dissolved hydrocarbons over a range of 0.01-100 mg x L(-1) or up to aqueous solubility limits. Calibration sensitivities were measured individually for laboratory-prepared solutions of BTEX (benzene, toluene, ethylbenzene, and xylene isomers) and C6-C8 aliphatic components. Each component demonstrated a method detection limit (MDL) in the low-to sub-ppm range (benzene 10 mg x L(-1), n-hexane 0.54 mg x L(-1)) for light coatings of a commercially available poly-(dimethylsiloxane) gum (OV-1, > 10(6) g x mol(-1)) and lower MDLs for heavier coatings. Pairwise responses for the aliphatic and benzenoid standards were additive, indicating that aggregate determinations of mixtures (especially light fuels) were possible. Natural matrix interferences caused by sample turbidity and ionic strength were overcome by simple preparative methods. Fuel-spiked natural waters were determined with respect to standards and verified by gas chromatography. A 0.19 mg x L(-1) MDL for gasoline was obtained for heavy OV-1 films. Field determinations of groundwater surrounding a leaking underground fuel tank demonstrated that the sensor and method were useful for on-site PH screening. Large differences between the equilibration times of aliphatic and benzenoid components also indicated one avenue for BTEX speciation with the device.     

Evaluation of IP over WDM Network Architectures

The commonly used IP-backbone network architecture of today is IP/ATM/SDH/WDM. This architecture has many redundant functionalities and is not optimized to transport IP traffic. New approaches for simplified network architectures try to eliminate redundant functionalities and to decrease the protocol overhead and thereby transport IP as efficiently as possible over WDM-based optical networks. EURESCOM project P918 Integration of IP-over-optical networks: networking and management investigated scenarios for optimized IP transport in WDM-based backbone networks. In this paper, three architectures, namely Gigabit Ethernet, Packet over Sonet/SDH and Dynamic Packet Transport are investigated and evaluated as an alternative to the IP/ATM/SDH/WDM architecture.     

Low-Frequency Noise Assessment of Silicon Passivated Ge pMOSFETs With TiN/TaN/ HfO2 Gate Stack

The low-frequency noise of pMOSFETs fabricated in epitaxial germanium-on-silicon substrates is studied. The gate stack consists of a TiN/TaN metal gate on top of a 1.3-nm equivalent oxide thickness HfO₂/SiO₂ gate dielectric bilayer. The latter is grown by chemical oxidation of a thin epitaxial silicon film deposited to passivate the germanium surface. It is shown that the spectrum is of the 1/f^gamma type, which obeys number fluctuations for intermediate gate voltage overdrives. A correlation between the low-field mobility and the oxide trap density derived from the 1/f noise magnitude and the interface trap density obtained from charge pumping is reported and explained by considering remote Coulomb scattering