A method for coordinating the distributed transmission of imagery.

Distributed imaging using sensor arrays is gaining popularity among various research and development communities. A common bottleneck within such an imaging sensor network is the large resulting data load. In applications for which transmission power and/or bandwidth are constrained, this can drastically decrease the sensor network lifetime. We present an algorithm that efficiently exploits inter- and intrasensor correlation for the purpose of power-constrained distributed transmission of sensor-network imagery. Gains in network lifetime up to 114% are obtained when using the suggested algorithm with lossless compression. Our results also demonstrate that when lossy compression is employed, much larger gains are achieved. For example, when a normalized root-mean-squared error of 0.78% can be tolerated in the received measurements, the network lifetime increases by a factor of 2.8, as compared to the (optimized) lossless case.     

先进封装电镀中活性边界层的减薄

晶圆表面如果有一层薄且均匀的流体边界层,将有助于克服光刻图形带来的挑战,得到更均匀的金属沉积层。     

平板投影光楔的图象质量

我们报道了一种厚度为20mm的14英寸平板投影显示屏,其亮度可达5000尼特、分辨率为600×800。这种显示器由现成的有机玻璃制成,使用只带梯形预畸变的无需调节的视频投影仪。在厚度为20mm对角线为50英寸屏幕上光学模拟预示XGA分辨率,亮度为500尼特、对比度与传统投影仪相当。     

Efficiency Enhancement in Organic Photovoltaic Cells: Consequences of Optimizing Series Resistance

Here, means to enhance power conversion efficiency (PCE or η) in bulk‐heterojunction (BHJ) organic photovoltaic (OPV) cells by optimizing the series resistance (R_s)—also known as the cell internal resistance—are studied. It is shown that current state‐of‐the‐art BHJ OPVs are approaching the limit for which efficiency can be improved via R_s reduction alone. This evaluation addresses OPVs based on a poly(3‐hexylthiophene):6,6‐phenyl C₆₁‐butyric acid methyl ester (P3HT:PCBM) active layer, as well as future high‐efficiency OPVs (η > 10%). A diode‐based modeling approach is used to assess changes in R_s. Given that typical published P3HT:PCBM test cells have relatively small areas (～0.1 cm²), the analysis is extended to consider efficiency losses for larger area cells and shows that the transparent anode conductivity is then the dominant materials parameter affecting R_s efficiency losses. A model is developed that uses cell sizes and anode conductivities to predict current–voltage response as a function of resistive losses. The results show that the losses due to R_s remain minimal until relatively large cell areas (>0.1 cm²) are employed. Finally, R_s effects on a projected high‐efficiency OPV scenario are assessed, based on the goal of cell efficiencies >10%. Here, R_s optimization effects remain modest; however, there are now more pronounced losses due to cell size, and it is shown how these losses can be mitigated by using higher conductivity anodes.     

Doping efficiency and energy-level scheme in C60F48-doped zinc–tetraphenylporphyrin films

High resolution synchrotron-based core level spectroscopy was used to examine the energy level alignment at the interface of zinc–tetraphenylporphyrin films doped by the surface acceptor C₆₀F₄₈. Two distinct fluorofullerene charge states were identified, corresponding to ionized and neutral molecules, and their relative concentration as a function of coverage was used to evaluate the probability of occupation of the acceptor lowest unoccupied molecular orbital (LUMO). From an initial acceptor energy of ?0.25 eV, the C₆₀F₄₈ LUMO shifts upwards with coverage due to a doping-induced interfacial dipole potential, and stabilization of the LUMO at an energy 0.45 eV above the Fermi energy was obtained. While the energy difference upon saturation is consistent with the results obtained for other donor–acceptor systems that have been interpreted as Fermi level pinning, the present work shows that the energy offset is a direct consequence of the interplay between Fermi–Dirac statistics in combination with the interfacial dipole potential.     

Discovery and Evaluation of a Functional Ternary Polymer Blend for Bone Repair: Translation from a Microarray to a Clinical Model

Skeletal tissue regeneration is often required following trauma, where substantial bone or cartilage loss may be encountered and is a significant driver for the development of biomaterials with a defined 3D structural network. Solvent blending is a process that avoids complications associated with conventional thermal or mechanical polymer blending or synthesis, opening up large areas of chemical and physical space, while potentially simplifying regulatory pathways towards in vivo application. Here ternary mixtures of natural and synthetic polymers were solvent blended and evaluated as potential bone tissue engineering matrices for osteoregeneration by the assessment of growth and differentiation of STRO‐1+ skeletal stem cells. Several of the blend materials were found to be excellent supports for human bone marrow‐derived STRO‐1+ skeletal cells and fetal skeletal cells, with the optimized blend exhibiting in vivo osteogenic potential, suggesting that these polymer blends could act as suitable matrices for bioengineering of hard tissues.     

An autocorrelation-based time domain analysis technique for monitoring perfusion and oxygenation in transplanted organs

In designing an implantable sensor for perfusion monitoring of transplant organs the ability of the sensor to gather perfusion information with limited power consumption and in near real time is paramount. The following work was performed to provide a processing method that is able to predict perfusion and oxygenation change within the blood flowing through a transplanted organ. For this application, an autocorrelation-based algorithm was used to reduce the acquisition time required for fast Fourier transform (FFT) analysis while retaining the accuracy inherent to FFT analysis. In order to provide data proving that the developed method is able to predict perfusion as accurately as FFT two experiments were developed isolating both periodic and quasi-periodic cardiac frequencies. It was shown that the autocorrelation-based method was able to perform comparably with FFT (limited to a sampling frequency of 300 Hz) and maintain accuracy down to acquisition times as low as 4 s in length.     

Correspondence between the location of evoked potential generators and sites of maximal sensitivity to stimulation

The potential recorded by a set of electrodes as an action potential traverses a small axonal segment is proportional to the transmembrane potential produced during stimulation of that axon segment by the same set of recording electrodes, under certain circumstances. First, the membrane must have a constant thickness which is so small that the difference between the surface area of the inner and outer surfaces is minimal. Second, all media must be linear. Third, there must be a monotonically increasing relation between the mean transmembrane potential induced by a stimulus and the maximum transmembrane potential. Fourth, as each axon segment depolarizes, the transmembrane current and change in membrane potential during this time are same. This principle remains true for magnetic stimulation and recording as long as currents generated at the boundaries between regions of differing conductivity outside the axon contribute minimally to the field at the axon. This allows the identification of the point at which an action potential generates a maximal extracellular potential as the point that is stimulated with the lowest threshold.     

汽车启动／停止系统电源方案

为了限制油耗,一些汽车制造商在其新一代车型中应用了“启动/停止”（Start／Stop）功能。当汽车停下来时,这些创新的系统关闭发动机;而当驾驶人的脚从刹车踏板移向油门踏板时,就自动重新启动发动机。这就帮助降低市区驾车及停停走走式的交通繁忙期时的油耗。