Variational optical flow computation in real time.

This paper investigates the usefulness of bidirectional multigrid methods for variational optical flow computations. Although these numerical schemes are among the fastest methods for solving equation systems, they are rarely applied in the field of computer vision. We demonstrate how to employ those numerical methods for the treatment of variational optical flow formulations and show that the efficiency of this approach even allows for real-time performance on standard PCs. As a representative for variational optic flow methods, we consider the recently introduced combined local-global method. It can be considered as a noise-robust generalization of the Horn and Schunck technique. We present a decoupled, as well as a coupled, version of the classical Gauss-Seidel solver, and we develop several multgrid implementations based on a discretization coarse grid approximation. In contrast, with standard bidirectional multigrid algorithms, we take advantage of intergrid transfer operators that allow for nondyadic grid hierarchies. As a consequence, no restrictions concerning the image size or the number of traversed levels have to be imposed. In the experimental section, we juxtapose the developed multigrid schemes and demonstrate their superior performance when compared to unidirectional multgrid methods and nonhierachical solvers. For the well-known 316 x 252 Yosemite sequence, we succeeded in computing the complete set of dense flow fields in three quarters of a second on a 3.06-GHz Pentium4 PC. This corresponds to a frame rate of 18 flow fields per second which outperforms the widely-used Gauss-Seidel method by almost three orders of magnitude.     

投影用高亮度发光二极管的快速发展

在过去三年中,微型显示投影发光二极管(LED)光学引擎的亮度显著地加速增长,在某种程度上超出了许多业内人士的期望。这种快速增长促进了液晶投影电视的出现。综述了应用于投影的LED的进展及相应产品。讨论了基于LED的光引擎的设计,展望了其亮度改进以及新产品研制的前景。     

Interacting effects of tillage method,nitrogen fertiliser and secondary drainage on winter wheat production on a calcareous clay soil

The response of winter wheat to nitrogen fertiliser within the range 0–200 kg ha^?1 in 40 kg increments applied either in April or in May in two consecutive seasons (1976–77 and 1977–78) was tested in a field experiment on a calcareous clay soil that was either direct-drilled, shallow tine cultivated (5–8 cm), or mouldboard ploughed (23 cm). These cultivation methods had been used on the same plots in the four preceding seasons (1973 to 1976) in a comparison of cultivation systems. A comparison was also made with direct-drilling on land that had been deep tine cultivated (17 cm) during the 1973–76 experiment. In the second season (1977–78) effects were examined of newly drawn mole drains, on land that had been direct-drilled or ploughed. In both seasons the effect of cultivation method on grain yield was small when nitrogen fertiliser was applied at 80–120 kg N ha^?1. Nitrogen top dressings in April gave heavier yields than the equivalent dressings in May, partly because of dry weather after the May applications in both years. There was no interaction between method of cultivation and amount of nitrogen applied in 1976–77, but a significant interaction was detected in 1977–78 which was probably associated with less nitrogen being available in the uncultivated soil during the winter and spring. The results show that the potential yield of direct-drilled crops may have been underestimated in some earlier comparisons of different methods of cultivation where small uniform top dressings of nitrogen were applied to each cultivation treatment. Mole drainage increased yield especially at low rates of nitrogen and after direct drilling, These results indicate that direct-drilled and ploughed land may differ in their drainage requirements.     

Voltage refinement by deficit HOLZ line geometry

A method of refining electron beam voltage from deficit line intersections, using a quasi-kinematic scattering approximation, is described and applied to a silicon standard. It is shown that dynamical corrections are necessary for higher-index zone axes, such as 310 and 411, where a single deficit line associated with one dominant Bloch state is visible. This leads to a substantial difference in the refined voltage compared with that obtained from a purely kinematic approximation. Neglect of this dynamical correction term effectively invokes a systematic error that may lead to high precision but poor accuracy in higher-order Laue zone measurements of beam voltage or lattice parameters. Although relatively small, differences in the dynamical correction necessary for these two zones are confirmed experimentally for 100-300 keV electrons.     

全球通用三频段GSM单芯片收发信机

本文所述是一个全球通用GSM单芯片收发信机的实现方式 ,介绍了基于GSM标准的多频段无线结构方框 ,讨论了此类结构方框实现全球通用GSM收发信机的可能性。该单芯片集成电路使用了0 5 μmBiCMOS工艺 ,并封装在一块“9× 9”的CABGA中。本文还介绍了该收发信机工作参数的测量结果。     

Design of Engineered Elastomeric Substrate for Stretchable Active Devices and Sensors

In the field of flexible electronics, emerging applications require biocompatible and unobtrusive devices, which can withstand different modes of mechanical deformation and achieve low complexity in the fabrication process. Here, the fabrication of a mesa‐shaped elastomeric substrate, supporting thin‐film transistors (TFTs) and logic circuits (inverters), is reported. High‐relief structures are designed to minimize the strain experienced by the electronics, which are fabricated directly on the pillars' surface. In this design configuration, devices based on amorphous indium‐gallium‐zinc‐oxide can withstand different modes of deformation. Bending, stretching, and twisting experiments up to 6 mm radius, 20% uniaxial strain, and 180° global twisting, respectively, are performed to show stable electrical performance of the TFTs. Similarly, a fully integrated digital inverter is tested while stretched up to 20% elongation. As a proof of the versatility of mesa‐shaped geometry, a biocompatible and stretchable sensor for temperature mapping is also realized. Using pectin, which is a temperature‐sensitive material present in plant cells, the response of the sensor shows current modulation from 13 to 28 °C and functionality up to 15% strain. These results demonstrate the performance of highly flexible electronics for a broad variety of applications, including smart skin and health monitoring.     

Mesure du Débit d’Absorption Spécifique (das) des téléphones mobiles — contribution du projetcomobio à la normalisation internationale

Human exposure to electromagnetic fields emitted by mobile phones is characterised by the Specific Absorption Rate (sar). This value corresponds to therf power absorbed by unitary mass of the equivalent tissue. It represents the basic restriction used to define limit of human exposure torf electromagnetic fields. Academic and industrial labs have contributed through thecomobio project to define international standards for mobile phones certification.     

Design and analysis of UW-OFDM signals

Unique word-orthogonal frequency division multiplexing (UW-OFDM) is a novel signaling concept where the guard interval is implemented as a deterministic sequence, the so-called unique word. The UW is generated by introducing a certain level of redundancy in the frequency domain. Different data estimation strategies and the favourable bit error ratio (BER) performance of UW-OFDM, as well as comparisons to competing concepts have already extensively been discussed in previous papers. This work focuses on the different possibilities on how to generate UW-OFDM signals. The optimality of the two-step over the direct approach in systematic UW-OFDM is proved analytically, we present a heuristic algorithm that allows a fast numerical optimization of the redundant subcarrier positions, and we show that our original intuitive approach of spreading the redundant subcarriers in systematically encoded UW-OFDM by minimizing the mean redundant energy is practically also optimum w.r.t. transceiver based cost functions. Finally, we derive closed form approximations of the statistical symbol distributions on individual subcarriers as well as the redundant energy distribution and compare them with numerically found results.     

FastFabric: Scaling hyperledger fabric to 20 000 transactions per second

Blockchain technologies are expected to make a significant impact on a variety of industries. However, one issue holding them back is their limited transaction throughput, especially compared to established solutions such as distributed database systems. In this paper, we rearchitect a modern permissioned blockchain system, Hyperledger Fabric, to increase transaction throughput from 3000 to 20 000 transactions per second. We focus on performance bottlenecks beyond the consensus mechanism, and we propose architectural changes that reduce computation and I/O overhead during transaction ordering and validation to greatly improve throughput. Notably, our optimizations are fully plug‐and‐play and do not require any interface changes to Hyperledger Fabric.     

Free-Standing β-Ga<Subscript>2</Subscript>O<Subscript>3</Subscript> Thin Diaphragms

Free-standing, very thin, single-crystal β-gallium oxide (β-Ga₂O₃) diaphragms have been constructed and their dynamical mechanical properties characterized by noncontact, noninvasive optical measurements harnessing the multimode nanomechanical resonances of these suspended nanostructures. We synthesized single-crystal β-Ga₂O₃ using low-pressure chemical vapor deposition (LPCVD) on a 3C-SiC epilayer grown on Si substrate at temperature of 950°C for 1.5 h. The synthesized single-crystal nanoflakes had widths of ～ 2 μm to 30 μm and thicknesses of ～ 20 nm to 140 nm, from which we fabricated free-standing circular drumhead β-Ga₂O₃ diaphragms with thicknesses of ～ 23 nm to 73 nm and diameters of ～ 3.2 μm and ～ 5.2 μm using a dry stamp-transfer technique. Based on measurements of multiple flexural-mode mechanical resonances using ultrasensitive laser interferometric detection and performing thermal annealing at 250°C for 1.5 h, we quantified the effects of annealing and adsorption of atmospheric gas molecules on the resonant characteristics of the diaphragms. Furthermore, we studied the effects of structural nonidealities on these free-standing β-Ga₂O₃ nanoscale diaphragms. We present extensive characterization of the mechanical and optical properties of free-standing β-Ga₂O₃ diaphragms, paving the way for realization of resonant transducers using such nanomechanical structures for use in applications including gas sensing and ultraviolet radiation detection.