混凝土的使用越来越广泛,其健康状况越来越被重视.混凝土裂缝的发生发展特征是混凝土健康状况的重要表征参数.钢筋是混凝土固有结构,针对混凝土内部的裂缝,提出一种应用钢筋天线的裂缝监测方法,设置内嵌于混凝土中的发射、接收钢筋天线对,通过天线对S21参数的幅值来检测混凝土内裂缝.构建CST Studio Suite软件仿真模型,利用CST Studio Suite软件计算钢筋天线对S21参数幅值,分析S21参数幅值与裂缝状态的关系,结果表明混凝土内部的裂缝状态会对S21参数幅值产生明显的影响,根据S21参数幅值的特征可以实现裂缝检测.对无裂缝模型和有裂缝模型的S21参数幅值进行求比值处理,其比值超过某个阈值即认为能辨识裂缝,并将该段能辨识裂缝的频带定义为特征频带.仿真结果发现,不同裂缝厚度、不同裂缝角度、不同裂缝位置时的S21参数幅值均有显著变化,证明了在混凝土内设置钢筋发射、接收天线对,测量电磁波传播的S21参数,通过S21参数幅值可以判断混凝土裂缝及裂缝特征.

A 3 mu m passively Q-switched Ho3-/Pr3- co-doped fiber laser by using Au nanocages as saturable absorber is demonstrated. Stable Q-switched pulse trains with a repetition rate of 82. 0 kHz are initially obtained as the pump power increases to 99. 7 mW. When the pump power increases to 347. 1 mW , the largest output power of 50. 7 mW with a pulse duration of 2. 21 mu s and a corresponding repetition rate of 169. 5 kHz is obtained. This study indicates that Au nanocages have a great potential as an outstanding optical modulator for mid-infrared pulses generation.

We report a wavelength-tunable high-repetition-rate passively Q-switched fluoride fiber laser around 3 μm by using Ti 3 C 2 T x MXene as saturable absorber (SA). The Ti 3 C 2 T x MXene was synthesized by selectively etching aluminum layers in Ti 3 AlC 2 . The modulation depth, non-saturation loss and saturation fluence of the SA at 2866 nm were measured to be 43.10%, 25.16%, and 0.50 mJ /cm 2 , respectively. By introducing the Ti 3 C 2 T x SA into a Ho 3+ /Pr 3+ -codoped fluoride fiber, stable Q-switched pulses with a continuously tuning range of 30.8 nm (2868.4 nm-2899.2 nm) were achieved. The repetition rate was as high as 215.3 kHz with an output power of 142 mW at the wavelength of 2879.0 nm. Such compact mid-infrared Q-switched laser source with a high repetition rate is of great importance in various applications such as medicine, high-resolution photoacoustic microscopy, and remote sensing. Our work indicates that the Ti 3 C 2 T x MXene is a promising broadband light modulator for pulsed laser sources around 3 μm.

We report a watt-level passively Q-switched 2.8 μm mid-infrared multi-mode fiber laser by employing multi-layered two-dimensional MXene-Ti3C2Tx as the saturable absorber (SA). The MXene-Ti3C2Tx is fabricated by selectively etching aluminum layers in Ti3AlC2. The non-saturable loss, modulation depth, and saturable intensity of the SA at 2866 nm were measured to be 25.0%, 33.2%, and 0.043 GW/cm2, respectively. The maximum average output power of the Ti3C2TxQ-switched fiber laser reached 1.09 W at 28.23% slope efficiency. The pulse repetition rate, shortest pulse width, pulse peak power, and single-pulse energy were 78.12 kHz, 1.04 μs, 13.4 W, and 13.93 μJ, respectively. This is the first demonstration of watt-level pulse generation in a mid-infrared fiber laser using low dimensional materials, to the best of our knowledge. These results indicate that the Ti3C2Tx is a reliable and superior broadband SA for high power mid-infrared pulsed laser generation.

The automatic detection of hypernasality degrees in cleft palate speech can provide effective, objective and non-invasive basis for the assessment of velopharyngeal function in clinical. In this work, an automatic detection system of hypernasality degrees in cleft palate has been researched. The human auditory model is applied to extract the inner pre-sentation of speech signal as the front-end processing, and the SLR(Soft-Limited Ratio)spectral features extracted from the synchronous detector is used as the acoustic characteristic parameters. The 1-v-1 SVM(1-v-1 Support Vector Machine) is utilized to automatically detect the hypernasality degrees(normal, mild, moderate and severe hypernasality). Experi-mental data include total 3 086 speeches from 56 kids, the comparisons of filter bank’s kind and number, synchronous detector and lateral inhibitory network are discussed. And the results show that the Gammatone filter based on ERB (Equivalent Rectangular Bandwidth)scale performs better than the wavelet-packet filter based on Bark scale, and the fil-ter bank with 54 channels can effectively weigh the time cost and recognition accuracy of our algorithm, and SLR spectral features extracted from the synchronous detector has better recognition than LIN spectral features extracted from the lateral inhibition network. The highest accuracy of the automatic detection of four-hypernasality degree is 91.50%.

Q-switched fiber lasers emitting at around 3 μm have been widely applied in various scientific and industrial fields, such as molecular spectroscopy, laser surgery, material processing, remote sensing, and mid-infrared (mid-IR) supercontinuum source generation. Au nanocages (Au-NCs) have attracted much attention recently due to their outstanding saturable absorption properties including broadband absorption, ultrafast optical response (a few picoseconds), and large third-order optical nonlinearity coefficient that caused by local surface plasmon resonance (LSPR). We propose and demonstrate a tunable Er3+ doped ZBLAN fiber laser using Au-NCs as a Q-switcher for the first time. Nonlinear absorption of the Au-NCs was measured by a home-made Ho3+/Pr3+ co-doped mode-locked fiber laser at 2850 nm. The measured modulation depth, saturation intensity and non-saturation loss are 10.73%, 0.11 MW/cm2 and 3.26%, respectively. The central wavelength of the Q-switched pulses could be tuned across 54.1 nm (from 2753.0 to 2807.1 nm). The Q-switched fiber laser delivers a maximum average power of 253.7 mW with corresponding pulse energy of 4.06 μJ and pulse width of 1.30 μs at repetition rate of 62.5 kHz. Our work shows the Au-NCs are promising saturable absorbers (SAs) for 3 μm mid-infrared (mid-IR) pulse generation.

Q-switched fiber lasers emitting at around 3 mu m have been widely applied in various scientific and industrial fields, such as molecular spectroscopy, laser surgery, material processing, remote sensing, and mid-infrared (mid-IR) supercontinuum source generation. Au nanocages (Au-NCs) have attracted much attention recently due to their outstanding saturable absorption properties including broadband absorption, ultrafast optical response (a few picoseconds), and large third-order optical nonlinearity coefficient that caused by local surface plasmon resonance (LSPR). We propose and demonstrate a tunable Er3+ doped ZBLAN fiber laser using Au-NCs as a Q-switcher for the first time. Nonlinear absorption of the Au-NCs was measured by a home-made Ho3+/Pr3+ co-doped mode-locked fiber laser at 2850 nm. The measured modulation depth, saturation intensity and non-saturation loss are 10.73%, 0.11 MW/cm(2) and 3.26%, respectively. The central wavelength of the Q-switched pulses could be tuned across 54.1 nm (from 2753.0 to 2807.1 nm). The Q-switched fiber laser delivers a maximum average power of 253.7 mW with corresponding pulse energy of 4.06 mu J and pulse width of 1.30 mu s at repetition rate of 62.5 kHz. Our work shows the Au-NCs are promising saturable absorbers (SAs) for 3 mu m mid-infrared (mid-IR) pulse generation.

背景:选择脑电图参考电极方式是分析事件相关电位的关键步骤,但是参考电极事件相关电位成分影响的相关研究较少.目的:从统计学和头皮电位拓扑学角度比较分析了平均参考、左耳乳突参考和零参考对面孔识别事件相关电位成分的影响.方法:使用的脑电图数据来自国际公开数据库Open fMRI中的多模态人类神经影像数据集.招募了19名正常或矫正视力正常的健康者进行视觉刺激试验,试验的视觉刺激因子分别为陌生人脸和扰乱人脸.使用brainstorm软件对3种参考(平均参考、左耳参考、零参考)方式下,在枕颞叶区域采集到的事件相关电位,进行N170潜伏期和幅值分析,并进行头皮电位拓扑图和源定位计算,对3种参考下的实验结果进行对比分析.结果 与结论:①与扰乱人脸相比,陌生人脸诱发的事件相关电位N170有更短的潜伏期和更大N170幅值的特点,N170潜伏期没有显著性差异,N170幅值有显著性差异;②拓扑结果表明,在相同的刺激因子下大脑右侧颞叶比左侧枕叶活动更为强烈,且只有REST参考能够最好地揭示大脑右侧颞叶和前额叶区域在陌生人脸和扰乱人脸刺激时存在显著性差异;③结果说明,REST参考方式下得到的脑电图数据更加真实准确,这为进一步研究面孔识别神经机制提供了帮助,为面孔识别相关实验参考电极的选择提供依据.

Au nanocages (Au-NCs) have attracted wide attention as low-dimensional materials with broadband absorption, ultrafast optical response, large third-order optical nonlinearity coefficient, and high photothermal stability and thermal tolerance. By employing Au-NCs as saturable absorbers, we demonstrate a widely tunable passively Q-switched erbium-doped fluoride fiber laser at the wavelength of 2.8 µm. When operates at 2778.0 nm, this laser delivers stable Q-switched pulses with a maximum average power of 584.6 mW at a pulse repetition rate of 80.6 kHz. The minimum pulse duration attained was 1.16 µs corresponding with the single pulse energy of 7.25 µJ. Our results present onefold increase in pulse energy over previously published values achieved from Au nanoparticles based 3-µm passively Q-switched fiber lasers. By introducing a plane ruled grating, a tuning rage of 57.0 nm from 2753.0 to 2810.0 nm is achieved, while maintaining stable Q-switched operation. To our knowledge, this is the first time to demonstrate that Au-NCs can realize mid-infrared pulsed laser. Our research results show that Au-NCs are promising broadband nonlinear modulators for mid-infrared pulse generation.

The resolution of traditional fluorescence microscopy is limited due to the optical diffraction. Various techniques have been developed to surpass the diffraction limit in recent years. Among these methods, nonlinear structured illumination microscopy (nonlinear SIM) is able to provide fast imaging speed, wide field of view and considerable resolution enhancement simultaneously. However, the current developed nonlinear SIM approaches have their own defects. We report a potential better nonlinear SIM for live-cell imaging termed 'Matrix STED-SIM' with patterned illumination based on both structured excitation grid and stimulated emission depletion (STED) grid. Theory and simulation analysis are presented for illustrating the feasibility of our method to achieve better super-resolution imaging than other current approaches. In addition, we demonstrate the robustness and potential practicability of this new method considering the impact of image noise and exposures.

CT脑血管的三维重构依赖于图像的二维断层扫描,脑血管感兴趣区的提取是图像处理的关键.为了保证CT脑血管三维重建的图像质量,本文提出了基于曲线聚类的CT脑血管感兴趣区提取算法,首先移除头部CT图像中的头部骨骼,随后采用曲线聚类提取脑血管感兴趣区.该方法关注显影剂的时间放射性曲线的时间序列特征,能够有效的提取脑血管边缘,实验表明该方法具有良好的精度与鲁棒性.

This paper presents an initial/final segmentation algorithm in cleft palate speech.Through subjective test and objective F test and t test,it is proven that there are significant differences between cleft palate speech and normal speech. Two types of syllables are defined firstly:Class I syllable whose initial has the characteristics of voiceless phoneme,and Class II syllable whose initial has the characteristics of voiced phoneme.These two types of syllables are classified based on hierarchical fuzzy clustering model.Then for the class I syllable,a similar-to-voiced-sound weighting function and similar-to-unvoiced-sound probability function are defined,in order to achieve the roughly initial/final segmentation.The accurate location of initial/final boundary in class I syllable is achieved,through calculating the first-order difference of autocorrelation function's peak number.For the class II syllable,based on the waveform difference between initial and final,the energy's jumping point of short-autocorrelation function is found in order to achieve the initial/final segmenta-tion.The experiment results show that the proposed algorithm achieves a high segmentation accuracy rate:Segmentation accuracy for class I syllables is 90.72%,and segmentation accuracy for class II syllables is 92.90%.

Fluorescence microscopy plays an important role in biomedical imaging because of its high sensitivity and specificity. However, the resolution of traditional fluorescence microscopy is limited due to the optical diffraction. Various techniques have been developed to surpass the diffraction limit in recent years. Among these existing methods, nonlinear structured illumination microscopy (SIM) simultaneously provides the ability of fast imaging speed, wide field of view and extended resolution improvement. However, the current developed nonlinear SIM approaches such as Saturated SIM and Photoswitching SIM have their own defects due to the strong photon bleaching and slow photoswitching speed respectively. We report a new nonlinear SIM technique based on stimulated emission depletion (STED), the illumination pattern of which combining both structured excitation field and structured STED field (SSTED-SIM). Theoretical study and simulation analysis have been conducted to demonstrate that SSTED-SIM performs better than other existing nonlinear SIM.

Objective:There is a significant difference in the hearing rehabilitation between the congenitally deaf children after cochlear implant(CI). The intrinsic mechanism that affects the hearing rehabilitation in patients was discussed from the perspective of evoked EEG source activity.Method:Firstly, we collected the ERP data from 23 patients and 10 control group children during 0, 3, 6, 9 and 12 months after CI. According to the hearing rehabilitation during 12 months after CI, the patients were divided into two groups: rehabilitation of "the good" and "the poor". Then we used sLORETA to show the changes in the groups of patients' cerebral cortex and compared with the control group.Result:Cross-modal reorganization of cerebral cortex exists in the congenitally deaf children. The cross-modal reorganization gradually degraded and the activity of the relevant cortex followed by normally after CI. There was a statistically significant difference(P < 0.05) in the temporal lobe and the associated cortex around parietal lobe between "the good" and "the poor" groups after 12 months.Conclusion:The normalization of the cross-modal reorganization in patients reflects the hearing rehabilitation after CI, especially the normalization of the activity of the temporal lobe and the associated cortex around parietal lobe, which influences the rehabilitation effect of the auditory function to some extent. This research demonstrated the detection of the mechanism has important significance for the hearing recovery training and evaluation of the hearing rehabilitation after CI.

Based on the double closed-loop DC model,aiming at the difficulty of current DC double closedloop PID controller parameters tuning and optimization,according to the artificial bee colony algorithm which is introduced into the DC double closed-loop speed regulation system,the DC motor speed and parameters of PID controller is realized and the optimal results of artificial bee colony algorithm is compared and analyzed by using the step response of the system.The results show that the dynamic-performance-index-improved artificial bee colony algorithm can obtain better performance than the traditional design method and is followed faster and robust,Thus,a better overall performance and practical method is proposed for PID parameter optimization.

Objective To compare the efficacy and complications of the extend endoscopic endonasal approach (EEA) and open transcranial approach for resection of craniopharyngiomas. Methods The clinical data from 46 patients with craniopharyngiomas with extend EEA and 54 patients with transcranial route in our department was analyzed retrospectively. The gross total resection (GTR) rate,length of hospital stays and complications of the two groups were compared. Results The tumor diameters of were larger in the endoscopic group than in the transcranial group (3.5 ± 1.3cm vs. 3.0±0.8 cm, P<0.05). The endoscopic group had a greater GTR rate (67.4％vs. 46.3％, P<0.05)and improved visual outcome(84.2％ vs. 59.5％,P<0.05),but lower rate of hypopituitarism (56.5％ vs. 75.9％,P<0.05)and permanent diabetes insipidus (51.4％ vs.72.7％,P<0.05). On the contrast, the endoscopic group had a greater rate of cerebrospinal fluid leak(4.3％ vs. 0.0％,P>0.05)and longer hospital stays(17.0±3.6 d vs. 13.1±2.3 d,P<0.01). Hyposmia(34.8％)and hemorrhinia (2.2％)only happened in the endoscopic group. Conclusion Compared with transcranial route, the extend EEA for craniopharyngiomas is minimal invasion and effective, which can effectively improve the GTR rate and reduce the clinical symptoms.

Cochlear implant (CI) is the only method for efficacious treatment of congenital severe deafness at present. However, for children with congenital severe deafness after CI, the mechanism of the structural and functional changes of their cerebral cortex is not clear. This study was based on the cross-modal reorganization of deaf patients. Event related potential (ERP) and source localization technique were used to visualize the change of cortical activity in children with congenital severe deafness during 1-year period (0, 1, 3, 6, 9 and 12 months after CI). We aimed to investigate the association between hearing restoration and cross-modal reorganization in children with congenital severe deafness after CI. The results showed that the cross-modal reorganization exists in children with congenital severe deafness. During hearing restoration, the function of the cross-modal reorganization reversed to the normal state. The method and conclusions of this study may be of significance in guiding the training and evaluation of hearing rehabilitation after CI in patients.

This study aimed to investigate the dysfunctional ascending/descending pain pathways at the thalamic level in patients with migraine without aura (MWoA) using the effective connectivity analysis of the resting-state functional MRI. Twenty MWoA and 25 matched healthy controls participated in the resting-state functional MRI scans. The directional interactions between the posterior thalamus (PTH) and other brain regions were investigated using the Granger causality analysis and choosing bilateral PTH as two individual seeds. Pearson's correlation analysis was carried out between the abnormal effective connectivity and the headache duration and pain intensity of MWoA. Compared with healthy controls, MWoA showed decreased inflows to the bilateral PTH from the ventromedial prefrontal cortex and the left precuneus/posterior cingulate cortex, decreased outflow from the left PTH to the ipsilateral dorsomedial prefrontal cortex, and increased inflow to the right PTH from the ipsilateral dorsolateral prefrontal cortex. In addition, the abnormal inflows to the right PTH from the ventromedial prefrontal cortex and the right dorsolateral prefrontal cortex correlated positively with the headache duration and pain intensity, respectively. The abnormal ascending/descending pain pathways between the thalamus and these cortical regions indicate a disrupted pain modulation in affective and sensory domains, which suggests a disequilibrium of pain inhibition and facilitation in MWoA. These findings may help to shed light on the pathophysiologic mechanisms of migraine.

A based state-space feedback optimized control is proposed to meet the requirements of the switched power ampliifer performance in biomaterial fatigue systems. In order to minimize high-frequency switching losses and voltage stresses, the soft-switched phase-shifting ZVZCS full bridge topology is introduced to construct the power conversion circuit. According to the state-space averaging analysis, a dynamic linear switching model is established. Using the quadratic optimal rule, a servo controller is gradually developed to track the excitation current on inductive load. Good dynamic response and steady state performance of system is proved through the computer-aided simulation and experimental data analysis.

Magnetic resonance imaging (MRI) is by nature a multi-modality technique that provides complementary information about different aspects of diseases. So far no attempts have been reported to assess the potential of multi-modal MRI in discriminating individuals with and without migraine, so in this study, we proposed a classification approach to examine whether or not the integration of multiple MRI features could improve the classification performance between migraine patients without aura (MWoA) and healthy controls. Twenty-one MWoA patients and 28 healthy controls participated in this study. Resting-state functional MRI data was acquired to derive three functional measures: the amplitude of low-frequency fluctuations, regional homogeneity and regional functional correlation strength; and structural MRI data was obtained to measure the regional gray matter volume. For each measure, the values of 116 pre-defined regions of interest were extracted as classification features. Features were first selected and combined by a multi-kernel strategy; then a support vector machine classifier was trained to distinguish the subjects at individual level. The performance of the classifier was evaluated using a leave-one-out cross-validation method, and the final classification accuracy obtained was 83.67% (with a sensitivity of 92.86% and a specificity of 71.43%). The anterior cingulate cortex, prefrontal cortex, orbitofrontal cortex and the insula contributed the most discriminative features. In general, our proposed framework shows a promising classification capability for MWoA by integrating information from multiple MRI features.