关注细节以确保Bluetooth+WiFi的服务质量

蓝牙和802.11b/g WiFi都是重要的无线技术,常被应用于笔记本电脑、PDA、个人多媒体播放器(PMP)以及手机等设备中.     

Toward a direct measure of video quality perception using EEG

An approach to the direct measurement of perception of video quality change using electroencephalography (EEG) is presented. Subjects viewed 8-s video clips while their brain activity was registered using EEG. The video signal was either uncompressed at full length or changed from uncompressed to a lower quality level at a random time point. The distortions were introduced by a hybrid video codec. Subjects had to indicate whether they had perceived a quality change. In response to a quality change, a positive voltage change in EEG (the so-called P3 component) was observed at latency of about 400-600 ms for all subjects. The voltage change positively correlated with the magnitude of the video quality change, substantiating the P3 component as a graded neural index of the perception of video quality change within the presented paradigm. By applying machine learning techniques, we could classify on a single-trial basis whether a subject perceived a quality change. Interestingly, some video clips wherein changes were missed (i.e., not reported) by the subject were classified as quality changes, suggesting that the brain detected a change, although the subject did not press a button. In conclusion, abrupt changes of video quality give rise to specific components in the EEG that can be detected on a single-trial basis. Potentially, a neurotechnological approach to video assessment could lead to a more objective quantification of quality change detection, overcoming the limitations of subjective approaches (such as subjective bias and the requirement of an overt response). Furthermore, it allows for real-time applications wherein the brain response to a video clip is monitored while it is being viewed.     

On the Energy Detection of Unknown Signals Over Fading Channels

This letter addresses the problem of energy detection of an unknown signal over a multipath channel. It starts with the no-diversity case, and presents some alternative closed-form expressions for the probability of detection to those recently reported in the literature. Detection capability is boosted by implementing both square-law combining and square-law selection diversity schemes     

Real structure of partially ordered crystals

Partial order in crystals is a frequently observed phenomenon in minerals and synthetic materials. The partially ordered structures are characterized by low-dimensional order of the real structure. In the case of 1D structures, the ordered units can be described as rods; 2D structures contain ordered layers. The disorder of the real structures is indicated by prominent diffuse scattering in the diffraction patterns of single crystals. No simple method for the quantitative analysis of the diffuse scattering exists, therefore the determination of essential characteristics of the structures is complicated. However, the determination can be facilitated using a combination of different methods, including electron microscopy, computation and X-ray diffraction.     

用于先进的双嵌入和栓工艺的低缺陷钨CMP高性价比浆料(英文)

介绍了用于钨双嵌入和钨栓CMP工艺的新型CMP3200TM氧化铝浆料,测试证明,这种浆料在110nm技术节点的钨CMP工艺应用中取得了理想的效果。通过对氧化铝粒子制造工艺的有效控制,获得了可满足110nm技术节点双嵌入和栓层钨CMP工艺要求的低缺陷率,高性价比的氧化铝蛐硝酸铁浆料。从而在价格竞争激烈的半导体制造领域,特别是代工市场引起了业界越来越多的关注。     

Ionic Hydrogels with Biomimetic 4D‐Printed Mechanical Gradients: Models for Soft‐Bodied Aquatic Organisms

Direct‐ink writing (DIW), a rapidly growing and advancing form of additive manufacturing, provides capacities for on‐demand tailoring of materials to meet specific requirements for final designs. The penultimate challenge faced with the increasing demand of customization is to extend beyond modification of shape to create 4D structures, dynamic 3D structures that can respond to stimuli in the local environment. Patterning material gradients is foundational for assembly of 4D structures, however, there remains a general need for useful materials chemistries to generate gray scale gradients via DIW. Here, presented is a simple materials assembly paradigm using DIW to pattern ionotropic gradients in hydrogels. Using structures that architecturally mimic sea‐jelly organisms, the capabilities of spatial patterning are highlighted as exemplified by selectively programming the valency of the ion‐binding agents. Spatial gradients, when combined with geometry, allow for programming the flexibility and movement of iron oxide nanoparticle–loaded ionotropic hydrogels to generate 4D‐printed structures that actuate in the presence of local magnetic fields. This work highlights approaches to 4D design complexity that exploits 3D‐printed gray‐scale/gradient mechanics.     

Drawing of optical fiber with internal codrawn wire and conductive coating and electrooptic modulation demonstration

One hundred twenty meters of fiber with an internal codrawn wire and electrically conductive coating was successfully fabricated for the first time. The integration of the conductive coating and wire was all performed during the fiber draw stage, in a process that enabled arbitrarily long lengths of fiber to be made. The wire combined with the conductive coating enables a strong electric field to be formed across the optical core. Such a fiber is ideal for thermally poling long lengths and for nonlinear device applications such as optical switches and modulators.     

Direct observation of the stacked structure in substituted copper phthalocyanine LB films with STM

The in-plane molecular structures of octa-alkyl substituted copper phthalocyanine LB films deposited on graphite have been resolved with a scanning tunnelling microscope (STM). The face-to-face stacking of Pc macrocycles has been observed in the topographies of R₈PcCu monolayers. The stacking period was found to be 3.8–4 Å and the molecular rows were separated by 19 Å and 16 A for (C₆H₁₃)PcCu and (C₅H₁₁)PcCu respectively.     

Operator dependence of 3-D ultrasound-based computational fluid dynamics for the carotid bifurcation

The association between vascular wall shear stress (WSS) and the local development of atherosclerotic plaque makes estimation of in vivo WSS of considerable interest. Three-dimensional ultrasound (3DUS) combined with computational fluid dynamics (CFD) provides a potentially valuable tool for acquiring subject-specific WSS, but the interoperator and intraoperator variability associated with WSS calculations using this method is not known. Here, the accuracy, reproducibility and operator dependence of 3DUS-based computational fluid dynamics were examined through a phantom and in vivo studies. A carotid phantom was scanned and reconstructed by two operators. In the in vivo study, four operators scanned a healthy subject a total of 11 times, and their scan data were processed by three individuals. The study showed that with some basic training, operators could acquire accurate carotid geometry for flow reconstructions. The variability of measured cross-sectional area and predicted shear stress was 8.17% and 0.193 N/m/sup 2/ respectively for the in vivo study. It was shown that the variability of the examined parameters was more dependent on the scan operators than the image processing operator. The range of variability of geometrical and flow parameters reported here can be used as a reference for future in vivo studies using the 3DUS-based CFD approach.