基于子空间的指数和分解及在信道估计中的应用

指数和序列分解问题是一个经典的数学问题,Prony方法和Prony-Kung方法是解决此问题的经典方法。用支撑子空间的观点仔细分析了Prony-Kung方法,在此基础上,理论证明了指数和序列分解问题可以归纳于支撑子空间的确定问题,并对受噪声污染的指数和序列提出了具有低复杂度的Lloyd-like搜索支撑子空间的算法。最后,把以上算法应用于毫米波信道估计,仿真结果表明了此应用的有效性。

An improved bearing fault detection strategy based on artificial bee colony algorithm

The operating state of bearing affects the performance of rotating machinery;thus,how to accurately extract features from the original vibration signals and recognise the faulty parts as early as possible is very critical.In this study,the one‐dimensional ternary model which has been proved to be an effective statistical method in feature selection is introduced and shapelet transformation is proposed to calculate the parameter of one‐dimensional ternary model that is usually selected by trial and error.Then XGBoost is used to recognise the faults from the obtained features,and artificial bee colony algorithm(ABC)is introduced to optimise the parameters of XGBoost.Moreover,for improving the performance of intelligent algorithm,an improved strategy where the evolution is guided by the probability that the optimal solution appears in certain solution space is proposed.The experimental results based on the failure vibration signal samples show that the average accuracy of fault signal recognition can reach 97%,which is much higher than the ones corresponding to traditional extraction strategies.And with the help of improved ABC algorithm,the performance of XGBoost classifier could be optimised;the accuracy could be improved from 97.02%to 98.60%compared with the traditional classification strategy.

Difference Analysis of MRI Apparent Diffusion Coefficient and R_(2)^(*)Value Between Small Hepatocellular Carcinoma and Cirrhosis Nodules

Objective:To investigate the differences of apparent diffusion coefficient and transverse relaxation rate(R_(2)^(*))in magnetic resonance imaging(MRI)between micro hepatocellular carcinoma and nodules of cirrhosis.Method:The clinical data of 68 patients with micro hepatocellular carcinoma(76 lesions)and 45 patients with nodular cirrhosis(48 lesions)were retrospectively analyzed.Diffusion weighted imaging and R_(2)^(*)imaging were performed on all patients.The differences of apparent diffusion coefficient and R_(2)^(*)values in patients with micro hepatocellular carcinoma and nodular cirrhosis were compared.Receiver operating characteristic(ROC)curves were drawn to evaluate the diagnostic efficacy of apparent diffusion coefficient values and R_(2)^(*)values for microhepatocellular carcinoma.Result:Compared with nodules of cirrhosis,the mean apparent diffusion coefficient and R_(2)^(*)value of micro-hepatocellular carcinoma were significantly decreased(P<0.05).The diagnosis threshold of apparent diffusion coefficient is at 1.35×10^(-3)mm^(2)/s,and the sensitivity for the diagnosis of micro-hepatocellular carcinoma was 80.88%,and the specificity was 91.11%,and the corresponding area under the ROC curve was 0.88;The diagnostic threshold for R_(2)^(*)value was at 53.96 Hz,and the sensitivity for the diagnosis of small hepatocellular carcinoma was 91.18%,and the specificity was 77.78%,and the corresponding area under the ROC curve was 0.84.Conclusion:MRI apparent diffusion coefficient value and R_(2)^(*)value can be used to differentiate and diagnose micro hepatocellular carcinoma and nodules of cirrhosis,in which the apparent diffusion coefficient of nodules of cirrhosis was less than 1.35×10^(-3)mm^(2)/s,R_(2)^(*)values were lower than 53.96 Hz may indicate the occurrence of nodular canceration.

Clinical Study of Magnetic Resonance Imaging,Diffusion Weighted Imaging and Dynamic Contrast-enhanced Imaging in the Diagnosis of Endometrial Carcinoma

Objective:To evaluate the value of DWI,DCE-MRI and magnetic resonance imaging(MRI)in the diagnosis of endometrial cancer.Method:The MRI,DWI and DCE-MRI imaging data of 80 patients with suspected endometrial cancer were analyzed.The diagnostic value of MRI,DWI and DCE-MRI in endometrial cancer was analyzed based on the postoperative pathological diagnosis results.The diagnostic efficacy of quantitative parameters Ktrans value,Kep value,Ve value and ADC in endometrial cancer was analyzed by ROC.Result:Among the 80 patients,61 had endometrial carcinoma and 19 had benign endometrial disease.The accuracy of MRI,DWI and DCE-MRI in the diagnosis of endometrial cancer was 57.38%,63.93%and 80.33%,respectively.The specificity was 78.95%,82.41%and 84.21%,respectively.The ADC values of endometrial cancer patients were lower than those of benign patients(P<0.05),and the values of Ktrans,Kep and Ve were higher than those of benign patients(P<0.05).The ktrans and ADC in the diagnosis of endometrial cancer were higher,which was 0.922(95%CI:0.864-0.992,P=0.000)and 0.872(95%CI:0.767-0.977.P=0.000),respectively.Conclusion:DWI and DCE-MRI had high value in the diagnosis of endometrial cancer.Its parameters,Ktrans and ADC,can be used as quantitative indicators for the early diagnosis of endometrial cancer.

An Algorithm for Generation of Attack Signatures Based on Sequences Alignment

This paper presents a new algorithm for generation of attack signatures based on sequence alignment. The algorithm is composed of two parts: a local alignment algorithm-GASBSLA (Generation of Attack Signatures Based on Sequence Local Alignment) and a multi-sequence alignment algorithm-TGMSA (Tri-stage Gradual Multi-Sequence Alignment). With the inspiration of sequence alignment used in Bioinformatics, GASBSLA replaces global alignment and constant weight penalty model by local alignment and affine penalty model to improve the generality of attack signatures. TGMSA presents a new pruning policy to make the algorithm more insensitive to noises in the generation of attack signatures. In this paper, GASBSLA and TGMSA are described in detail and validated by experiments.

Research on Survivability of Mobile Ad-hoc Network

In this paper, we analyze the survivability of Mobile Ad Hoc Network systemically and give a detailed description of the survivability issues related to the MANET. We begin our work with analyzing the requirements of survivability of ad hoc network, and then we classify the impacts that affect survivability into three categories: dynamic topology, faults and attacks. The impacts of these factors are analyzed individually. A simulation environment for the MANET towards survivability is designed and implemented as well. Experiments that under the requirements and the impacts we de-clared are done based on this environment.

单发单收系统下联合解码方法的性能分析

对于一个单发单收的无线通信系统,本文推导了联合解码法,并对其性能做出了理论的分析,得到了其成对错误概率的解析公式。基于此公式的分析表明,不用信道估计的联合解码法的性能要优于基于信道估计方法的系统性能。并且在某些特定的条件下,不发送训练序列的系统性能要优于基于训练序列的系统性能。所有的仿真证实了上述结论。

Sintering behaviour and microwave dielectric properties of MgO-2B_(2)O_(3)--xwt%BaCu(B_(2)O_(5))-ywt%H_(3)BO_(3) ceramics

This study investigates the bulk density,sintering behaviour,and microwave dielectric properties of the MgO-2B_(2)O_(3) series ceramics synthesised by solid-state reaction.According to the X-ray diffraction and microstructural analyses,the as-prepared MgO-2B_(2)O_(3) ceramics possess a single-phase structure with a rod-like morphology.The effects of different quantities of H_(3)BO_(3) and BaCu(B_(2)O5)(BCB)on the bulk density,sintering behaviour,and microwave dielectric properties of the MgO-2B_(2)O_(3) ceramics were investigated.Accordingly,the optimal sintering temperature was obtained by adding 30 wt%H_(3)BO_(3) and 8 wt%BCB.We also reduced the sintering temperature to 825°C.Furthermore,the addition of 40 wt%H_(3)BO_(3) and 4 wt%BCB increased the quality factor,permittivity,and temperature coefficient of resonance frequency of MgO-2B_(2)O_(3) to 44,306 GHz(at 15 GHz),5.1,and-32 ppm/℃,respectively.These properties make MgO-2B_(2)O_(3) a viable low-temperature co-fired ceramic with broad applications in microwave dielectrics.

代谢节点的咽喉要道

Glycerol is a simple polyhydroxy-three-carbon compound that is highly hydrophilic and is considered a central intermediate metabolite for cellular metabolism.It is found at the crossroads among several metabolic pathways,such as glycolysis and gluconeogenesis(for carbohydrates),lipogenesis,lipolysis,and glyceroneogenesis(for lipids),pentose-phosphate pathway(for nucleic acids),amino acid synthesis,and even energy generation by oxidative phosphorylation[1](Fig.1).

Automatic quantitative analysis of metabolism inactivation concentration in single bacterium using stimulated Raman scattering microscopy with deep learning image segmentation

Rapid antimicrobial susceptibility testing(AST)is urgently needed to slow down the emergence of antibioticresistant bacteria and treat infections with correct antibiotics.Stimulated Raman scattering(SRS)microscopy is a technique that enables rapid chemical-bond imaging with sub-cellular resolution.It can obtain the AST results with a single bacterium resolution.Although the SRS imaging assay is relatively fast,taking less than 2 h,the calculation of single-cell metabolism inactivation concentration(SC-MIC)is performed manually and takes a long time.The bottleneck tasks that hinder the SC-MIC throughput include bacterial segmentation and intensity thresholding.To address these issues,we devised a hybrid algorithm to segment single bacteria from SRS images with automatic thresholding.Our proposed method comprises a U-Net convolutional neural network(CNN),DropBlock,and secondary segmentation post-processing.Our results show that SC-MIC calculation can be accomplished within 1 min and more accurate segmentation results using deep learning-based bacterial segmentation method,which is essential for its clinical applications.