Global motion estimation from randomly selected motion vector groups and GM/LM based applications

Fast global motion estimation has been paid much attention in video compression and analysis. In this paper, a global motion estimation method is proposed by randomly selected motion vector groups in the compression domain directly. It is carried out by refining the centroid of the global motion parameters corresponding to the motion vector groups. Simulation results on different global motions show its effectiveness and robustness against noise and motion vector loss. Finally, two applications, namely the text occluded region recovery and the error concealment, are presented using the global motion/local motion information. Experimental results show the effectiveness of the proposed method. This work is supported in part by China National Natural Science Foundation (CNSF) under Project No.60572045, the Ministry of Education of China Ph. D. Program Foundation under Project No.20050698033, and by a Cooperation Project (2005.7- 2007.7) with Microsoft Research Asia.     

基于全局运动补偿编码的AVS编码器设计

对全局运动估计算法进行了改进的基础上,提出了基于全局运动补偿编码的编码体系,并实现了基于全局运动补偿编码的AVS编码器。通过标准测试序列的测试表明,基于全局运动补偿的编码器可以使重建图像的质量有一定程度的提高。     

一种提高H.261编码性能的实现方法

研究表明采用最小均方误差或绝对误差准则的块匹配运动估值算法对H.261编码器来说不是最好的。本文提出了一种改进的块匹配运动估值算法。它所采用的准则不仅考虑了预测误差能量的大小,还考虑了运动矢量信息以及帧间预测误差的编码比特数目的多少.实验结果表明新的准则能够显著地改善H.261的编码性能。     

Design and fabrication of sub-μs silicon-on-insulator thermo-optic 4×4 switch matrix

A rearrangeable nonblocking silicon-on-insulator-based thermo-optic 4x4 switch matrix with spot size converters （SSCs） and a new driving circuit are designed and fabricated. The introduction of a spot size converter （SSC） has decreased the insertion loss to less than 10dB and the new driving circuit has improved the response speed to less than l~s.     

Global-motion estimation in image sequences of 3-D scenes for coding applications

A technique for global-motion estimation and compensation in image sequences of 3-D scenes is described in this paper. Each frame is segmented into regions whose motion can be described by a single set of parameters and a set of motion parameters is estimated for each segment. This is done using an iterative block-based image segmentation combined with the estimation of the parameters describing the global motion of each segment. The segmentation is done using a Gibbs-Markov model-based iterative technique for finding a local optimum solution to a maximum a posteriori probability (MAP) segmentation problem. The initial condition for this process is obtained by applying a Hough transform to the motion vectors of each block in the frame obtained by block matching. In each iteration, given a segmentation, the motion parameters are estimated using the least-squares (LS) technique. To obtain the final segmentation and the more appropriate higher-order motion model for each segment, a final stage of splitting/merging of segments is needed. This step is performed on the basis of maximum-likelihood decisions combined with the determination of the higher-order model parameters by LS. The incorporation of the proposed global-motion estimation technique in an image-sequence coder was found to bring about a substantial reduction in bit-rate without degrading the perceived quality or the PSNR.     

A multicast dynamic wavelength assignment algorithm based on matching degree

The wavelength assignment with multiple multicast requests in fixed routing WDM network is studied. A new multicast dynamic wavelength assignment algorithm is presented based on matching degree. First, the wavelength matching degree between available wavelengths and multicast routing trees is introduced into the algorithm. Then, the wave.length assignment is translated into the maximum weight matching in bipartite graph, and this matching problem is solved by using an extended Kuhn-Munkres algorithm. The simulation results prove that the overall optimal wavelength assignment scheme is obtained in polynomial time. At the same time, the proposed algorithm can reduce the connecting blocking probability and＂ improve the system resource utilization.     

Periodical rocking long period gratings in PANDA fibers for high temperature and refractive index sensing

We report periodical rocking long period gratings (PR-LPGs) in PANDA fibers fabricated with CO2 laser. The PR-LPGs achieve very high coupling efficiency of 19 dB with 12 periods and a 3.5° twist angle in just one scanning cycle, which is much more effective than the conventional CO2 laser fabrication technique. This type of LPGs exhibits polarization-selective resonance dips which demonstrate different sensitivities to environmental parameters. The high temperature and external refractive index sensitivities are measured simultaneously, so it can be used as a wavelength-selective polarization filter and sensor. This work has been supported by the National Natural Science Foundation of China (No.61605168), the Natural Science Foundation of Hebei Province (No.F2016203392), the College and University Natural Science Foundation of Hebei Province (No.QN2016078), the Science and Technology Project of Qinhuangdao City (No.201601B050), and the Intramural Doctoral Foundation of Yanshan Universtiy (No.B1011). E-mail:jinwa@ysu.edu.cn      

A 2× 2 SOI mach-zehnder thermo-optical switch based on strongly guided paired multimode interference couplers

A silicon-on-insulator 2× 2 Mach-Zehnder thermo-optical switch is developed based on strongly guided paired multimode interference couplers. The multimode-interference couplers were etched deeply for improving coupler characteristics such as self-imaging quality, uniformity and fabrication toierance. The proposed switch achieves good performances, including a low insertion loss of -11.0dB, a fiber-waveguide coupling loss of-4.3dB and a fast response speed measured to be 3.5 and 8.8 μs for raise and fall switching time, respectively.     

Global point tracking based panoramic image stabilization system

A novel image stabilization system is presented,which consists of a global feature point tracking based motion estimation,a Kalman filtering based motion smoothing and an image mosaic based panoramic compensation.The global motion is estimated using feature point matching and iteration with the least-square method.Then,the Kalman filter is applied to smooth the original motion vectors to effectively alleviate unwanted camera vibrations and follow the intentional camera scan.Lastly,the loss information of im...     

Numerical simulation and experimental investigation of Ti-6Al-4V melted by CW fiber laser at different pressures

The interaction of continuous wave (CW) fiber laser with Ti-6Al-4V alloy is investigated numerically and experimentally at different laser fluence values and ambient pressures of N2 atmosphere to determine the melting time threshold of Ti-6Al-4V alloy. A 2D-axisymmetric numerical model considering heat transfer and laminar flow is established to describe the melting process. The simulation results indicate that material melts earlier at lower pressure (8.0 Pa) than at higher pressure (8.8×104 Pa) in several milliseconds with the same laser fluence. The experimental results demonstrate that the melting time threshold at high laser fluence (above 1.89×108 W/m2) is shorter for lower pressure (vacuum), which is consistent with the simulation. While the melting time threshold at low laser fluence (below 1.89×108 W/m2) is shorter for higher pressure. The possible aspects which can affect the melting process include the increased heat loss induced by the heat conduction between the metal surface and the ambient gas with the increased pressure, and the absorption variation of the coarse surface resulted from the chemical reaction. This work has been supported by the National Natural Science Foundation of China for Young Scholars (No.11402120), the Jiangsu Provincial Natural Science Foundation for Young Scholars (No.BK20140796), and the Fundamental Research Funds for the Central Universities (No.30915015104). E-mail:hanbing@njust.edu.cn      

Applying Hopfield neural network to QoS routing in communication network

The main goal of routing solutions is to satisfy the requirements of the Quality of Service （QoS） for every admitted connection as well as to achieve a global efficiency in resource utilization. In this paper proposes a solution based on Hopfield neural network （HNN） to deal with one of representative routing problems in uni-cast routing, i. e. the multi-constrained（MC） routing problem. Computer simulation shows that we can obtain the optimal path very rapidly with our new Lyapunov energy functions.     

Magnetic field sensor based on peanut-shape structure and multimode fiber

An all fiber magnetic field sensor with peanut-shape structure based on multimode fiber (MMF) is proposed and experimentally demonstrated. The sensing structure and magnetic fluid (MF) are both encapsulated in capillary, and the effective refractive index of MF is affected by surrounding magnetic field strength. The measurement of magnetic field is realized by observing the wavelength drift of interference peak. The transmission spectrum generated by Mach-Zehnder interferometer (MZI) includes core-core mode interference and core-cladding mode interference. Experimental results demonstrate that the core-cladding mode interference is sensitive to magnetic field, and the magnetic field sensitivity is 0.047 8 nm/mT. In addition, two kinds of interference dips are sensitive to temperature, and the sensitivities are 0.060 0 nm/°C and 0.052 6 nm/°C, respectively. So the simultaneous measurement of magnetic field strength and temperature can be achieved based on sensitivity matrix. This work has been supported by the National High Technology Research and Development Program of China (No.2013AA014200), the National Natural Science Foundation of China (No.11444001), and the Municipal Natural Science Foundation of Tianjin (No.14JCYBJC16500). E-mail:13821538563@163.com      

A 4th order fully integrated active RC complex filter with novel automatic tuning systems

This letter introduces a 4th order active RC complex filter with 1.5MHz center frequency and 1MHz bandwidth. The total harmonic distortion of the filter is less than –60dB and the image rejection ratio is greater than 60dB. A novel technique is also proposed in this letter to automatically adjust the variation of the time constant. The advantages of the proposed method are its high precision and simplicity. Using 5bits control words, the tuning error is less than ±1.6%.     

The Analysis of the Parameters and the Functions of Rectangular Waveguide E-plane Filter

In this paper, to analyze the discontinuity structure of E-plane metal insert by mode matching method, and metal insert thickness and resonator length impact on filter design. This work was supported by the Natural Science Foundation of Jiangsu Province of China under Grant No. BK2008357.     

A very low bit rate video coder based on vector quantization

Describes a video coder based on a hybrid DPCM-vector quantization algorithm that is suited for bit rates ranging from 8-16 kb/s. The proposed approach involves segmenting difference images into variable-size and variable-shape blocks and performing segmentation and motion compensation simultaneously. The purpose of obtaining motion vectors for variable-size and variable-shape blocks is to improve the quality of motion estimation, particularly in those areas where the edges of moving objects are situated. For the larger blocks, decimation takes place in order to simplify vector quantization. For very active blocks, which are always of small dimension, a specific vector quantizer has been applied, the fuzzy classified vector quantizer (FCVQ). The coding algorithm described displays good performance in the compression of test sequences at the rates of 8 and 16 kb/s; the signal-to-noise ratios obtained are good in both cases. The complexity of the coder implementation is comparable to that of conventional hybrid coders, while the decoder is much simpler in this proposal.     

A flat microwave photonic filter based on M-Z modulator and fiber Bragg grating

A new multiple-taps and flat microwave photonic filter, which is composed of fiber Bragg grating, M-Z modulator and erbium-doped fiber, is put forward. The flat band-pass or flat band-stop response can be realized by adjusting the coupler＇s factor and the reflectivity of the fiber Bragg grating or the gain of the erbium-doped fiber. The free spectral range of the filter can be tuned by controlling the length of the erbium-doped fiber. The potential and feasibility of the proposed filtering structures have been demonstrated by simulation.     

Development of three-dimensional profiler for large field micro-surface topography measurement

This paper presents a large field phase-shifting interference microscope for micro-surface topographymeasurement. A PZT is used as the Z-directional phase shifter. The interference microscope is the combination of the infinity tube microscope with the Mirau two-beam interferometer. Two-dimensional precision motorized stage is aligned as the scanning system in theX- and Y-direction to extend the test surface measurement range to 12.5 mm× 12.5 mm. The minimum displacement is 0.039 μm and the overlapped proportion is 0.22. A fast stitching algorithm is proposed based on grid matching. According to the reflectivity of the core and the ferrule, the plate with the transmission/reflectivity ratio of 70/30 is selected to balance the interference intensity. The instrument is proved to be valid by actual measurement of the end surface of an optical fiber connector.     

An FBG impact location system based on broadband light source and improved TDoA algorithm

When a structure material is damaged by impact events, the reliability and lifetime of the material will be severely affected. So impact location is considered as the prime approach for structural health and damage monitoring. In this study, a novel fiber Bragg grating (FBG) impact location system based on broadband light source is designed, aiming at the shortcoming of existing location systems based on FBG. An improved localization algorithm based on the time difference of arrival (TDoA) is proposed for impact location. According to this algorithm, the impact position can be accurately predicted without wave velocity. Impact planar location experiments are carried out for verification of the FBG impact location system and algorithm on a400 mm×400 mm×3 mm aluminum alloy plate. The resulted locating error shows high precision and good stability of the proposed system. This work has been supported by the National Natural Science Foundation of China (Nos.61503218, 61403233, 61573226 and 61473176), the Excellent Young and Middle-Aged Scientist Award Grant of Shandong Province of China (No.BS2013DX018), and the Natural Science Foundation of Shandong Province for Outstanding Young Talents (No.ZR2015JL021). E-mail:pangdan@163.com