Rice Crop Digital Image Compression Technology Based on Discrete Fourier Transform

[Objective] To study the digital image compression technology in rice monitoring system. [Method] A digital image compression technology program based on the discrete Fourier transform was proposed, and simulation experiments were carried out to compress the image at different compression ratios. [Result] When com- pression ratios were less than 30, the compression ratio, image entropy, average codeword length, coding efficiency and redundancy which reflected the quality of the coding, and the parameter PSNR which estimated the fidelity of the compressed im- age were all achieved good results that human eye could barely percept the differ- ence between the original image and decompressed image; and when the compres- sion ratios were more than 30, there was a certain distortion in the decompressed image. And when the compression ratio was 91.516 3, although the image had some distortion, the PSNR was still achieved to 21.528 2, and human eye could accept the decompressed image intuitively within the acceptable error range. [Conclusion] The results show that the proposed image compression program is a viable, effective, and better image compression technology which can satisfy the requirements of the crop monitoring system on image storage, transforming and transporting.

Strong noise attenuation method based on the multiuser kurtosis criterion

The strong noise produced by the leakage of electricity from marine seismic streamers is often received with seismic signals during marine seismic exploration. Traditional denoising methods show unsatisfactory effects when eliminating strong noise of this kind. Assuming that the strong noise signals have the same statistical properties, a blind source separation （BSS） algorithm is proposed in this paper that results in a new denoising algorithm based on the constrained multi-user kurtosis （MUK） optimization criterion. This method can separate strong noise that shares the same statistical properties as the seismic data records and then eliminate them. Theoretical and field data processing all show that the denoising algorithm, based on multi-user kurtosis optimization criterion, is valid for eliminating the strong noise which is produced by the leakage of electricity from the marine seismic streamer so as to preserve more effective signals and increase the signal-noise ratio. This method is feasible and widely applicable.

含较高噪声重叠峰的分辨

采用Daubechies正交小波滤波和样条卷积分峰联用方法对信噪比S/N≥ 2的含噪重叠双峰进行滤噪和分峰处理。滤波部分采用阈值法 ,较详细地探讨了阈值的选取规则 ;分峰部分利用样条卷积法 ,并给出了其算法公式。处理速度较快 ,算法也较简单。通过对模拟和实验信号的处理 ,发现该联用方法很有效 ,处理后的峰的峰位置误差≤ 3 0 % ,峰面积误差≤ 3 0 %

Application Research of Image Compression Technology in Monitoring System of Rape Crop in Areas of Qinling Mountains

[Objective] The aim was to present a proposal about a new image compression technology, in order to make the image be able to be stored in a smaller space and be transmitted with smaller bit rate on the premise of guaranteeing image quality in the rape crop monitoring system in Qinling Mountains. [Method] In the proposal, the color image was divided into brightness images with three fundamental colors, followed by sub-image division and DCT treatment. Then, coefficients of transform domain were quantized, and encoded and compressed as per Huffman coding. Finally, decompression was conducted through inverse process and decompressed images were matched. [Result] The simulation results show that when compression ratio of the color image of rape crops was 11.972 3∶1, human can not distinguish the differences between the decompressed images and the source images with naked eyes; when ratio was as high as 53.565 6∶1, PSNR was still above 30 dD,encoding efficiency achieved over 0.78 and redundancy was less than 0.22. [Conclusion] The results indicate that the proposed color image compression technology can achieve higher compression ratio on the premise of good image quality. In addition, image encoding quality and decompressed images achieved better results, which fully met requirement of image storage and transmission in monitoring system of rape crop in the Qinling Mountains.

Experimental Research on the Double-peak Characteristic of Underwater Radiated Noise in the Near Field on Top of a Submarine

The double-peak characteristic of underwater radiated noise in the near field on top of the target submarine was analyzed in depth on the basis of submarine test data on the sea. The contribution of three major noise sources to the radiated noise of a submarine were compared and analyzed, and emphasis was put on the original source, production mechanism, and their correlative characteristics. On the basis of analysis on underwater tracking and pass through characteristics of the target submarine, the double-peak phenomenon was reasonably interpreted. Furthermore, the correctness of the theoretical interpretation was verified adequately in real submarine tests. The double-peak phenomenon indicates that the space distributing character on submarine radiated noise are both asymmetrical with time and space, whereas that is provided with directivity. Studying the double-peak phenomenon in depth has important reference value and meaning in engineering practice for understanding the underwater radiated noise field of submarines.

Hump-Shaped Broadband Noise on a Fan at Off-Design Conditions

A spurious effect of blowing noise is sometimes detected on fans working at high flow rate, showing a large hump around 4000 Hz on the acoustic spectra. A Tollmien-Shlichtling （TS） effect is suspected, and several compressible LES are made on aerodynamic profiles to detect and investigate this phenomenon. Vortex shedding is observed at the trailing edge, triggering some density fluctuations when a thin boundary layer exists on the profile upper side. Acoustic waves with length equivalent to the chord are observed. A profile modification is proposed with a camber brought closer to the leading edge. This shape tested on a prototyped fan confirms the weakening of the TS effect.

Comparative analysis of different methods for image enhancement

Image enhancement technology plays a very important role to improve image quality in image processing. By enhancing some information and restraining other information selectively, it can improve image visual effect. The objective of this work is to implement the image enhancement to gray scale images using different techniques. After the fundamental methods of image enhancement processing are demonstrated, image enhancement algorithms based on space and frequency domains are systematically investigated and compared. The advantage and defect of the above-mentioned algorithms are analyzed. The algorithms of wavelet based image enhancement are also deduced and generalized. Wavelet transform modulus maxima(WTMM) is a method for detecting the fractal dimension of a signal, it is well used for image enhancement. The image techniques are compared by using the mean(μ),standard deviation(?), mean square error(MSE) and PSNR(peak signal to noise ratio). A group of experimental results demonstrate that the image enhancement algorithm based on wavelet transform is effective for image de-noising and enhancement. Wavelet transform modulus maxima method is one of the best methods for image enhancement.

Network-aware perceptual error concealment method for H.264 video with side information

In order to improve the video quality of transmission with data loss,a spatial and temporal error concealment method was proposed,which considered both the state information of the network and the perceptual weight of the video content.The proposed method dynamically changed the reliability weight of the neighboring macroblock,which was used to conceal the lost macroblocks according to the packet loss rate of the current channel state.The perceptual weight map was utilized as side information to do weighted pixel interpolation and side-match based motion compensation for spatial and temporal error concealment,respectively.And the perceptual weight of the neighboring macroblocks was adaptively modified according to the perceptual weight of the lost macroblocks.Compared with the method used in H.264 joint model,experiment results show that the proposed method performs well both in subjective video quality and objective video quality,and increases the average peak signal-to-noise ratio(PSNR) of the whole frame by about 0.4 dB when the video bitstreams are transmitted with packets loss.

Application of a joint algorithm based on L-T to pulse pressure detection signal of fiber Fabry-Perot nano pressure sensor

An improved denoising method and its application in pulse beat signal denoising are studied.The proposed denoising algorithm takes the advantages of local mean decomposition(LMD)and time-frequency peak filtering(TFPF),called L-T algorithm.As a classical time-frequency filtering method,TFPF can effectively suppress random noise with signal amplitude retained when selecting a longer window length,while the signal amplitude will be seriously attenuated when selecting a shorter window length.In order to maintain effective signal amplitude and suppress random noise,LMD and TFPF are improved.Firstly,the original signal is decomposed into progression-free survival(PFS)by LMD,and then the standard error of mean(SEM)of each product function is calculated to classify many PFSs into useful component,mixed component and noise component.Secondly,by using the shorter window TFPF for useful component and the longer window TFPF for mixed component,noise component is removed and the final signal is obtained after reconstruction.Finally,the proposed algorithm is used for noise reduction of an Fabry-Perot(F-P)pressure sensor.Experimental results show that compared with traditional wavelet,L-T algorithm has better denoising effect on sampled data.

Comprehensively Context-Aware Approach to Guaranteeing Multimedia Conferencing Services

Service-Oriented Communication(SOC)is a key research issue to enable media communications using the Service-Oriented Architecture(SOA).Motivated by the necessity to guarantee the service quality of our webbased multimedia conferencing system,we present a Comprehensively Context-Aware(CoCA)approach in this paper.One major problem in the existing end-to-end Quality of Service(QoS)management solutions is that they analyse and exploit the relationships between the QoS metrics and corresponding contexts in an isolated manner.In this paper,we propose a novel approach to leveraging such relationships in a comprehensive manner based on Bayesian networks and the fuzzy set theory.This approach includes three phases:1)information feedback and training,2)QoS-to-context mapping,and3)optimal context adaption.We implement the proposed CoCA in the real multimedia conferencing system and compare its performance with the existing bandwidth aware and playback buffer aware schemes.Experimental results show that the proposed CoCA outperforms the competing approaches in improving the average video Peak Signal-to-Noise Ratio(PSNR).It also exhibits good performance in preventing the playback buffer starvation.

DNA循环测序中的影响因素和图例分析

目的 通过对 2 0 40份样品的DNA测序 ,回顾性分析和研究DNA循环测序过程中一些影响因素及其序列图谱。方法 对测序中模板、引物、测序反应条件及其产物的纯化等因素进行比较研究。结果 模板因素是测序成败的主要原因 ,占测序失败的 70 %。模板的质量直接影响着测序图谱 ,模板纯度不够 ,序列曲线表现为可读序列短 ,开始时波峰过高不易判读 ,然后峰值迅速降低 ,并有噪峰出现 ,信号减弱 ,在原始资料中核苷酸曲线的波峰扁平或者没有信号。模板浓度过高 ,序列曲线呈现头重脚轻 ,可读序列短 ;而浓度过低 ,则信号衰减。引物问题引起测序失败占 15 4% ,主要原因为引物失效 ,与模板匹配不完全 ,Tm值过低等因素。利用 75 %异丙醇沉淀纯化测序反应产物 ,效果好且简单 ,经济。结论 测序的质量与模板的纯度、浓度有着直接的关系 ,在大规模的测序中 ,推荐使用异丙醇沉淀法。

Suppression of strong random noise in seismic data by using time-frequency peak filtering

Time-frequency peak filtering (TFPF) is highly efficient in suppressing random noise in seismic data. Although the hypothesis of stationary Gaussian white noise cannot be fulfilled in practical seismic data, TFPF can effectively suppress white and colored random noise with different intensities, as can be theoretically demonstrated by detecting such noise in synthetic seismic data. However, a "zero-drift" effect is observed in the filtered signal and is independent of the average power and variance of the random noise, but related to its mean value. Furthermore, we consider the situation where the local linearization of the seismic data cannot be satisfied absolutely and study the "distortion" characteristics of the filtered signal using TFPF on a triangular wave. We found that over-compensation is possible in the frequency band for the triangular wave. In addition, it is nonsymmetrical and has a relationship to the time-varying curvature of the seismic wavelet. The results also present an improved approach for TFPF.

Colored 3D surface reconstruction using Kinect sensor

A colored 3D surface reconstruction method which effectively fuses the information of both depth and color image using Microsoft Kinect is proposed and demonstrated by experiment.Kinect depth images are processed with the improved joint-bilateral filter based on region segmentation which efficiently combines the depth and color data to improve its quality.The registered depth data are integrated to achieve a surface reconstruction through the colored truncated signed distance fields presented in this paper.Finally,the improved ray casting for rendering full colored surface is implemented to estimate color texture of the reconstruction object.Capturing the depth and color images of a toy car,the improved joint-bilateral filter based on region segmentation is used to improve the quality of depth images and the peak signal-to-noise ratio(PSNR)is approximately 4.57 d B,which is better than 1.16 d B of the joint-bilateral filter.The colored construction results of toy car demonstrate the suitability and ability of the proposed method.

A network-aware error-resilient method using prioritized intra refresh for wireless video communications

We propose a novel prioritized intra refresh method for the wireless video communication.The proposed method considers the characteristics of the human visual system,the error-sensitivity of the bitstream,and the state of the time-varying wireless channel jointly.An expected perceptual distortion model was used to adjust the intra refresh rate adaptively.This model consists of the perceptual weight map based on an attention model,the bit error probability map based on bitstream size,and the dynamic channel state information(CSI).Experimental results indicate that,compared with other intra refresh methods that consider only the content of the video or the CSI,the proposed method improves the average peak signal-to-noise ratio(PSNR) of the whole frame by about 0.5 dB,and improves the average PSNR of the attention-area by about 0.8 dB.