一种高效的基于模式色散的全光积分器

对基于模式色散的全光积分器进行数值仿真和实验 研究,实现了一种一维展宽倾斜入射方 式的全光积分器。在模式色散的作用下,光信号经过光纤时不同的模式产生了不同的延 时,叠加后产生了积 分的效果;选用了较大面积的高速光电探测器(PD)接收多模光纤(MMF)的输出光束, 利用50m的MMF实现了时间窗口约为1.5ns的 全光积分器;最后使用该积分器对光信号进行了积分实验。由于 使用模式色散作为产生时延的主要方法,因此方法具有与波长无关的特性,而且 能在很短的光纤上获 得较大的时间窗口。一维展宽的入射方式具有很好的灵活性,易于调试和控制。     

256灰度级LED大屏幕视频控制器

概述复杂可编程逻辑器件（ＣＰＬＤ）的特点及发展趋势，对ＬＥＤ大屏幕视频控制器中的灰度扫描方法进行了讨论，提出２５６灰度级扫描时的实现方案，并用Ｌａｔｔｉｃｅ公司ｉｓｐＬＳＩ器件实现２５６灰度级ＬＥＤ大屏幕视频控制器的控制电路。     

Low power high precision current memory integrator for analoguesigma-delta modulator

A new current memory cell used in a sigma-delta modulator is presented. This cell uses a triode mode memory transistor and is able to work with a single 3V power supply     

Low complexity distributed video coding

ContextConventional video encoding is a computationally intensive process that requires a lot of computing resources, power and memory. Such codecs cannot be deployed in remote sensors that are constrained in terms of power, memory and computational capabilities. For such applications, distributed video coding might hold the answer.ObjectiveIn this paper, we propose a distributed video coding (DVC) architecture that adheres to the principles of DVC by shifting the computational complexity from the encoder to the decoder and caters to low-motion scenarios like video conferencing and surveillance of hallways and buildings.MethodThe architecture presented is block-based and introduces a simple yet effective classification scheme that aims at maximizing the use of skip blocks to exploit temporal correlation between consecutive frames. In addition to the skip blocks, a dynamic GOP size control algorithm is proposed that instantaneously alters the GOP size in response to the video statistics without causing any latency and without the need to buffer additional frames at the encoder. To facilitate real-time video delivery and consumption, iterative channel codes like low density parity check codes and turbo codes are not used and in their place a Bose–Chaudhuri–Hocquenghem (BCH) code with encoder rate control is used.ResultsIn spite of reducing the complexity and eliminating the feedback channel, the proposed architecture can match and even surpass the performance of current DVC systems making it a viable solution as a codec for low-motion scenarios.ConclusionWe conclude that the proposed architecture is a suitable solution for applications that require real-time, low bit rate video transmission but have constrained resources and cannot support the complex conventional video encoding solutions.Practical implicationsThe practical implications of the proposed DVC architecture include deployment in remote video sensors like hallway and building surveillance, video conferencing, video sensors that are deployed in remote regions (wildlife surveillance applications), and capsule endoscopy.     

Determining scale and sea state from water video.

In most image processing and computer vision applications, real-world scale can only be determined when calibration information is available. Dynamic scenes further complicate most situations. However, some types of dynamic scenes provide useful information that can be used to recover real-world scale. In this paper, we focus on ocean scenes and propose a method for finding sizes in real-world units and the sea state from an uncalibrated camera. Fourier transforms in the space and time dimensions yield spatial and temporal frequency spectra. For water waves, the dispersion relation defines a square relationship between the wavelength and period of a wave. Our method applies this dispersion relation to recover the real-world scale of an ocean sequence. The sea state--including the peak wavelength and period, the wind speed that generated the waves, and the wave heights--is also determined from the frequency spectrum of the sequence combined with stochastic oceanography models. The process is demonstrated on synthetic and real sequences, validating the results with known scene geometry. This has wide applications in port monitoring and coastal surveillance.     

较低倍X射线像的灰级修正

应用同型计算机直接采集电子探针Ｘ射线像,并用伪彩色显示技术进行观察。发现电子束扫描方式下的低倍Ｘ射线像存在严重失真,并且倍数越低越严重;相同倍数时,谱仪的低波段比高滤段严重;不同谱仪上迭起方向不同。极低倍Ｘ射线像已无法使用,较低倍Ｘ射线像可以进行灰级修理。修理方法是,在完全的相同的实验条件下,分别采集标样和试样中某元素的Ｘ射线像,根据标样Ｘ射线像找出各像素点的修理因子;用该修正因子对试样元素的Ｘ射     

Low cost carbon dioxide monitor

This paper describes the construction and characterization of an inexpensive monitor for volume leaks of CO₂ gas which is based on the principle of thermal conductivity. The need for such a system stems from the toxicity of the gas and its extensive use in society today. The low cost of the system is due to the use of inexpensive components.     

Low cost miniature thermoelectric generator

A low-cost thermoelectric generator realised using integrated circuit technology is described. The thermopile comprises polycrystalline silicon thermoelements on a quartz substrate and employs a design previously reported by the authors for a silicon on sapphire device. An approximate 10 fold decrease in the substrate thermal conductivity is achieved. Results of output measurements are presented and compared with those of previous work highlighting the advantages of the new approach.<>     

基于激光标刻的细胞簇灰度降阶模型

针对激光在物体表面标刻无法逼真具有连续色调的灰度图形的特征,建立了基于细胞簇灰度降阶模型,对标刻图形灰度数据信息以及降阶算法进行数学描述,对传统误差扩散的结构进行改善,形成由二次频域调制半色调的相应算法,构建最优细胞簇像素点分配相应模型,最后运算后的标刻图形数据通过增强纹理能量,极大程度上减少了周期性纹理缺陷,使处理后的标刻图形更加充分的表现原灰度图形信息,为激光标刻灰度图形提供了新的研究方向。     

A new transform coder for gray scale images using MRT

The demand for high-speed transmission of best quality images over the internet has led to a strong need for the development of better algorithm for coding images. The transform coders are highly popular in encoding images. M-dimensional real transform (MRT) gives an alternate representation of a signal in the frequency domain which involves only real addition. In this paper a new transform coder based on 4×4 MRT is proposed and its performance is analyzed for all types of grayscale images.     

Low bitrate video coding with depth compensation

A depth-compensated low bitrate hybrid video coder for videophone applications is described. Depth and associated position information is extracted from the video frames using an edge-based stereo algorithm. A global motion vector and scale factor are extracted from the depth map and used as parameters for a model of the moving object. These global parameters are used to make the motion-compensated prediction more effective, by compensating for the change in size of the object. Simulations show that the compensated coder results in coded sequences with SNRs up to 1 dB better than those coded with conventional hybrid coders, at a coding rate of 64 kbit/s     

Reducing the effect of charge-transfer inefficiency in a c.c.d. video integrator

The usefulness of c.c.d.s as video integrators is limited by the charge-transfer inefficiency of the device. A method of coding the signal before passage through the c.c.d. is described which greatly reduces the effect of this inefficiency.     

低功耗微处理系统温度监视器

ADM1021温度测控芯片采用最新的测量技术避免了常规方法中的预先校准过程,且具有设定温度限定值方便、AD转换率可选等优点,作为低功耗的温度监视器表现出良好的性能,在台式电脑、笔记本式电脑等领域应用广泛,是理想的温度测量仪器。     

Low bit-rate video compression with neural networks and temporalsubsampling

In this paper we describe a novel neural network technique for video compression, using a “point-process” type neural network model we have developed which is closer to biophysical reality and is mathematically much more tractable than standard models. Our algorithm uses an adaptive approach based upon the users' desired video quality Q, and achieves compression ratios of up to 500:1 for moving gray-scale images, based on a combination of motion detection, compression, and temporal subsampling of frames. This leads to a compression ratio of over 1000:1 for full-color video sequences with the addition of the standard 4:1:1 spatial subsampling ratios in the chrominance images. The signal-to-noise ratio ranges from 29 dB to over 34 dB. Compression is performed using a combination of motion detection, neural networks, and temporal subsampling of frames. A set of neural networks is used to adaptively select the desired compression of each picture block as a function of the reconstruction quality. The motion detection process separates out regions of the frame which need to be retransmitted. Temporal subsampling of frames, along with reconstruction techniques, lead to the high compression ratios     

Low cost wideband I-Q vector modulator

One of the applications of QPSK modulators is to control the amplitude and phase of an RF signal, working as a vector modulator. Recently there are several monolithic commercial circuits that can be easily used to frequencies of >4 GHz. First, the input signal must be decomposed into two quadrature components, which is usually done in a 3 dB 90° hybrid coupler. Using microstrip techniques, this I-Q vector modulator exhibits narrowband characteristics, due to the degradation of the hybrid performances with frequency. The authors show how the working bandwidth can be extended up to an octave by means of a versatile control system as described here, as an alternative to a new design of the RF stage     

低成本可燃性气体泄漏报警器

为了解决现有的可燃性气体泄漏报警器成本高、难推广的问题,研制了一种高性价比的可燃性气体泄满报警器.它采用一个单电源供电的双集成运放来实现信号取出、比较和报警驱动,采用一块简单的数字模拟开关和阻容充电电路解决可燃气报警装置的初始误报警,并能使报警灵敏度在传感器性能范围内任意可调.样机经实验与试用表明效果很好.该装置由于成本低廉,不仅可应用于工矿企业的可燃气泄漏报警,而且可推广到普通家庭.     

基于子图灰度比较的匹配模板选取算法

为降低图像匹配模板选取算法的时间复杂度,提出一种基于子图灰度比较编码的图像匹配模板选取算法.首先将子图等分为2×2子块,以子图及邻近区域的4×4子块的灰度比较关系为子图赋予一个编码;其次在所有子图编码中选取重复次数最少的编码对应的一个子图或若干个子图中图像方差最大者作为匹配模板.算法复杂度分析和仿真实验结果表明,该匹配...     

Stochastic total cost of ownership optimization for video streaming services

In industry, the total cost of ownership (TCO) for developing a communication service such as video streaming, comprises from two components; CAPital EXpenditure (CAPEX) and OPerational EXpenditure (OPEX). These two types of costs are interrelated and affect any service provider’s deployment strategy. In many traditional methods, selection of critical elements of a new service is performed in a heuristic manner aimed at reducing only the OPEX part of the TCO which is not necessarily optimal. Furthermore, exact cost modeling for such services is not always possible and contains some uncertainties. In the current work, the TCO optimization problem for video streaming over IP networks is formulated as a stochastic optimization problem using cost modeling of each video streaming element and capturing the effect of the model uncertainties. The solution of the proposed optimization problem can cope with the cost modeling uncertainties and track the dynamic features of the TCO and lead to a time-varying optimal solution. Numerical analysis results verify the developed method and analyze its sensitivity to input parameters variations. Using the proposed stochastic optimization approach, the video streaming service providers can improve their return on investment (ROI) through selecting the optimal number of the deployed edge servers in the presence of uncertainties in ownership costs.     

Low bit-rate video coding with spatio-temporal geometric transforms

A low bit-rate video coding technique that uses spatio-temporal geometric transforms is presented. Motion compensation based on the bilinear transform is employed to reduce the temporal redundancy of the video. The spatial redundancy of the motion compensated error images is reduced by a combination of fractals and the DCT. It is shown that in the objects boundaries of the motion compensated error image fractals outperforms the DCT, while in the smooth areas the DCT is better than fractals. A hybrid combination of fractals and the DCT gives the best result. The performance of this hybrid codec with geometrically transformed motion compensation is compared against the H.261 standard video codec at 64 kbit/s     

Operation and cost optimization of a distributed serversarchitecture for on-demand video services

Distributed servers architecture offers storage and streaming scalabilities for video services. In this letter, we propose and analyze an on-demand scheme in which the local servers store the beginning portion (i.e., the “prefix”) of videos and deliver it by means of unicast streams to the clients. The clients are able to merge onto on-going multicast streams delivered from the repository by means of their set-top buffers. Given a certain limited repository (and thereof multicast) bandwidth, we investigate how the total cost of the local servers can be minimized. We show that if the local storage is the main cost, the size of the prefixes is likely to increase with the video popularity. On the other hand, if the server cost mainly comes from streaming capacity, the size of the prefixes is likely to decrease asymptotically with the video popularity