使用AMIRA拍摄沃达丰纪录片

正摄影师约翰·佩里(Johann Perry)最近为一支加纳青少年足球队拍摄了一条纪录短片,这支足球队得到机会去参加在英国举行的锦标赛。这条名叫《我的第一次世界大赛》的12分钟影片是应AKQA广告公司委托,由位于伦敦的Firecracker电影公司制作的。它是沃达丰第一次广告宣传活动品牌纪录短片系列的其中一部,仅仅用了四个拍摄日就完成了。以下为约翰·佩里分享此次使用AMIRA拍摄此片的经历与技巧。     

Simulation is essential for embedded control systems with task jitter

Sampling or task jitter affects the performance of digital control systems but realistic simulation of this effect has not been possible to date. Our previous work has developed a novel method to simulate sampling jitter in MATLAB/Simulink simulation software where the jitter is generated randomly. What has been missing is a way to capture sampling jitter from a target platform and then feed this timing information into the simulation. This paper presents a low-cost and novel solution to these problems. The method uses an Arduino board to capture task jitter from two different hardware platforms with multiple stressing conditions. Then the recorded performance data is used to drive realistic simulations of a control system. Measurement shows that the task jitter data does not follow any specific random distribution such as Gaussian or Uniform. Furthermore, very occasional timing patterns, which may not be picked up while testing a real system, can result in extreme controller responses. This novel method allows comparisons of different platforms and reduces the effort required to choose the most appropriate platform for full implementation.

     

A New Sidelobe Correction Algorithm for Microwave Radiometers: Application to the Envisat Instrument

The antenna temperature measured by a microwave radiometer is converted in brightness temperature (TB) by removing the different contributions that do not come from the main lobe of the antenna. Among them, the Earth contribution in the sidelobes may be significant as for the Environmental Satellite mission due to the antenna position on the platform. In such a case, simple corrections commonly applied on previous altimetry missions are inadequate, and a more accurate correction should be determined. We propose in this paper a new method based on global seasonal tables of contamination. This allows application of an accurate sidelobe correction in space and time in the retrieved TB computation     

Link adaptation for wireless systems

To improve the robustness and reliability of wireless transmissions, two complementary link adaptation techniques are employed: adaptive modulation and coding (AMC) at the physical layer and hybrid automatic retransmission request (HARQ) at the medium access control layer. Because of their effectiveness in combating errors induced by the wireless channel, AMC and HARQ are now integral components of most emerging broadband wireless system standards, for example, LTE and WiMAX. Spectral efficiency (SE) as measured in bit per second per Hertz is one important parameter used to characterize a wireless system for comparison between different systems or between different configurations of the same system. This work provides a holistic approach of cross‐layer optimizations with the intent of maximizing SE by combining AMC and HARQ. It formulates closed‐form equations for calculating the average SE for wireless systems with the Rayleigh fading channel model. A new online algorithm is developed to optimize SE for both Rayleigh and non‐Rayleigh fading channel. Simulations using proven LTE model are performed to compare SE obtained from closed‐form equations and the developed algorithm for different system configurations. With the developed algorithm to determine how many retransmissions required in addition to the initial transmission in advance depending on the current wireless channel condition, the latency can be reduced up to 24 ms when sending the initial transmission and all of its retransmissions sooner than waiting for retransmission requests as is done previously. Copyright © 2012 John Wiley & Sons, Ltd.     

Optimal block boundary pre/postfiltering for wavelet-based image and video compression.

This paper presents a pre/postfiltering framework to reduce the reconstruction errors near block boundaries in wavelet-based image and video compression. Two algorithms are developed to obtain the optimal filter, based on boundary filter bank and polyphase structure, respectively. A low-complexity structure is employed to approximate the optimal solution. Performances of the proposed method in the removal of JPEG 2000 tiling artifact and the jittering artifact of three-dimensional wavelet video coding are reported. Comparisons with other methods demonstrate the advantages of our pre/postfiltering framework.     

3.2 Tbit/s (80 × 40 Gbit/s) phase-shaped binary transmissionover 3 × 100 km with 0.8 bit/s/Hz efficiency

50 GHz-spaced 80 × 40 Gbit/s WDM transmission over 300 km of TeraLight^TM fibre is demonstrated without polarisation demultiplexing, using the PSBT format. A record capacity of 3.2 Tbit/s is thus achieved over the C-band only, with a spectral efficiency of 0.8 bit/s/Hz     

Low phase noise millimeter-wave frequency sources using InP-basedHBT MMIC technology

A family of millimeter-wave sources based on InP heterojunction bipolar transistor (HBT) monolithic microwave/millimeter-wave integrated circuit (MMIC) technology has been developed. These sources include 40-GHz, 46-GHz, 62-GHz MMIC fundamental mode oscillators, and a 95-GHz frequency source module using a 23.8-GHz InP HBT MMIC dielectric resonator oscillator (DRO) in conjunction with a GaAs-based high electron mobility transistor (HEMT) MMIC frequency quadrupler and W-band output amplifiers. Good phase noise performance was achieved due to the low 1/f noise of the InP-based HBT devices. To our knowledge, this is the first demonstration of millimeter-wave sources using InP-based HBT MMIC's     

Viscosity and optical measurement on fluoride glasses

Scattering loss and viscosity against temperature measurements have been carried out on fluoride glasses. The results indicate for the first time a ?-4 behaviour for scattering loss in the 0.45?0.75 ?m wavelength range. Activation energies for viscous flow were found to be similar for both ZrF4? and HfF4?based glasses.