Switchable Plasmonic Metasurface Utilizing the Electro-Optic Kerr Effect of a Blue Phase Liquid Crystal

A switchable metasurface composed of plasmonic split ring resonators and a polymer-stabilized liquid crystal blue phase is developed. Owing to field-induced birefringence (electro-optic Kerr effect), the state of polarization of the incident near infrared radiation changes, when a voltage is applied to the liquid crystal. Thus, different resonant modes of the split ring resonators can be addressed and the transmission spectrum changes accordingly. In comparison with other liquid crystal phases, blue phases have several advantages. For example, they are optically isotropic in the field-off state, so that no alignment layer is required. The results of the present study indicate that the advantages of these mesophases can be utilized for switchable metasurfaces.     

采用新型焊接电弧提高焊接生产的经济效益和焊缝质量

通过在传统的短路过渡电弧和射流过渡电弧的基础上进行创新,发展新型的焊接电弧,可以显著地提高电弧焊接在金属连接中的优越性。两种新的焊接电弧,forceArc~杂志焊接电弧和coldArc~焊接电弧可以在一个焊接电源上实现,对焊接生产具有现实意义。了解和掌握这些新型电弧的工艺特点,可以有效地将其应用到生产中,以此提高焊接产品的质量和焊接生产的经济效益。新型焊接电弧的出现使现有的有关焊前焊接接头准备的标准和规定,特别是有关坡口角度和焊接位置,需要重新考虑。新型焊接电弧可以应用于各种金属加工工业中的焊接生产,是对弧焊工艺的一个创新。     

Sediment-adsorbed total mercury flux through Yolo Bypass,the primary floodway and wetland in the Sacramento Valley,California

The fate and transport of mercury are of critical concern in lowland floodplains and wetlands worldwide, especially those with a history of upstream mining that increases the mobility of both dissolved and sediment-bound Hg in watersheds. A mass budget of total mercury (THg) quantifies sources and storage for particular areas — knowledge that is required for understanding of management options in lowland floodplains. In order to assess contaminant risk in the largest flood-control bypass, prime wetland, and restoration target in the Sacramento River basin, we estimated empirical relationships between THg, suspended sediment concentration (SSC), and streamflow (Q) for each of the major inputs and outputs using data from various publicly available sources. These relationships were improved by incorporating statistical representations of the dynamics of seasonal and intra-flood exhaustion (hysteresis) of sediment and mercury. Using continuous records of Q to estimate SSC suspended sediment flux and SSC to estimate THg flux, we computed the net transfer of sediment-adsorbed mercury through the Yolo Bypass over a decade, 1993–2003. Flood control weirs spilling Sacramento River floodwaters into the bypass deliver ~ 75% of the water and ~ 50% of the river's suspended sediment load, while one Coast Range tributary of the bypass, Cache Creek, contributes twice the THg load of the mainstem Sacramento. Although estimated sediment flux entering Yolo Bypass is balanced by efflux to the Sacramento/San Francisco Bay-Delta, there is much evidence of deposition and remobilization of sediment in Yolo Bypass during flooding. These factors point to the importance of the bypass as sedimentary reservoir and as an evolving substrate for biogeochemical processing of heavy metals. The estimates of mercury flux suggest net deposition of ~ 500 kg in the 24,000 ha floodway over a decade, dominated by two large floods, representing a storage reservoir for this important contaminant.     

Medical image computing at the Institute of Mathematics and Computer Science in Medicine,University Hospital Hamburg-Eppendorf

The author reviews the history of medical image computing at his institute, summarizes the achievements, sketches some of the difficulties encountered, and draws conclusions that might be of interest especially to people new to the field. The origin and history section provides a chronology of this work, emphasizing the milestones reached during the past three decades. In accordance with the author's group's focus on imaging, the paper is accompanied by many pictures, some of which, he thinks, are of historical value.     

Wavelength interval selection in multicomponent spectral analysis by moving window partial least-squares regression with applications to mid-infrared and near-infrared spectroscopic data

A new wavelength interval selection procedure, moving window partial least-squares regression (MWPLSR), is proposed for multicomponent spectral analysis. This procedure builds a series of PLS models in a window that moves over the whole spectral region and then locates useful spectral intervals in terms of the least complexity of PLS models reaching a desired error level. Based on a proposed theory demonstrating the necessity of wavelength selection, it is shown that MWPLSR provides a viable approach to eliminate the extra variability generated by non-composition-related factors such as the perturbations in experimental conditions and physical properties of samples. A salient advantage of MWPLSR is that the calibration model is very stable against the interference from non-composition-related factors. Moreover, the selection of spectral intervals in terms of the least model complexity enables the reduction of the size of a calibration sample set in calibration modeling. Two strategies are suggested for coupling the MWPLSR procedure with PLS for multicomponent spectral analysis: One is the inclusion of all selected intervals to develop a PLS calibration model, and the other is the combination of the PLS models built separately in each interval. The combination of multiple PLS models offers a novel potential tool for improving the performance of individual models. The proposed procedures are evaluated using two open-path Fourier transform infrared data sets and one near-infrared data set, each having different noise characteristics. The results reveal that the proposed procedures are very promising for vibrational spectroscopy-based multicomponent analyses and give much better prediction than the full-spectrum PLS modeling.     

Intel成功制作45nm芯片

Intel采用45nm工艺技术制作了该行业第一块全功能SRAM芯片,目标是于2007年采用该技术在300mm晶圆上开始制造芯片。目前Intel在Arizona和Oregon有两个制造厂制造65nm芯片,今年在Ireland和Oregon将有两个以上新厂投入生产。     

A Universal Laser-Pulse Apparatus for Thermophysical Measurements in Refractory Materials at Very High Temperatures

This paper presents a new experimental technique enabling thermophysical measurements to be carried out at very high temperatures in a very simple and small pressurized vessel in which the sample is heated by a continuous wave laser, and subsequently subjected to a short temperature pulse. The adopted method is essentially an extension of the laser-flash technique, widely used for thermal diffusivity measurements, whereby, in addition, the heat capacity and, hence, the thermal conductivity, , are simultaneously evaluated from the pulse analysis. Results are presented for the thermal diffusivity and heat capacity of graphite, zirconia, and uranium dioxide up to temperatures above 3000 K.