活塞异形销孔加工的研究

依据汽车活塞采用异形销孔的必要性和国内外异形销孔加工的现状，采用压电陶瓷驱动的柔性铰链机构实现镗刀的径向微位移。根据活塞异形销孔几何特征和压电陶瓷驱动器的控制精度高、刚性好和大频响特点，在位置反馈的系统中引入重复控制和反馈通道的开不前馈控制，从而提高了系统的稳定性和跟踪精度。实验表明加工精度可达3μm。     

伺服阀用液压放大式GMA的设计及建模

针对超磁致伸缩致动器输出位移有限,无法直接驱动伺服阀阀芯运动的问题,设计了一种基于柔性活塞的新型液压式微位移放大机构:由超磁致伸缩(GMM)棒驱动大活塞变形,并通过密闭容腔内的油液在小活塞端将GMM棒的输出位移放大。建立了超磁致伸缩致动器及其液压式微位移放大机构的耦合模型,采用弹性小挠度理论,有限元法和液压弹簧刚度理论对放大机构进行了分析和优化,并制作了样机。仿真和实验表明,所设计的液压式微位移放大机构可将GMM棒位移放大3.2倍,所建立的耦合模型较准确,误差在10%以内。     

超磁致伸缩材料控制模型的研究

超磁致伸缩材料作为一种新型、高效的功能材料在许多领域显示出良好的应用前景,但是由于其存在滞回、非线性等不足,限制了它的进一步应用。文章在分析超磁致伸缩现象产生机理的基础上,给出了其基于磁感应强度的控制模型,并通过分析和实验研究得出,采用磁感应强度的控制方法可减小超磁致伸缩材料滞回,提高其控制精度的结论。     

稀土超磁致伸缩材料的发展

稀土超磁致伸缩材料以其优良的特性和广泛的应用前景,在国际范围内得到了普遍的重视,已成为磁致伸缩材料研究的重点。文中简要介绍了稀土超磁致伸缩材料的特性以及性能优势,研究现状及应用,展望了今后的研究方向和发展。     

超磁致伸缩材料及其应用

介绍了超磁致伸缩材料具有高磁致伸缩应变λ，能量转换效率高、工作频带宽、频率特性好；稳定性好、可靠性高，其磁致伸缩性能不随时间而变化，无过热失效等特点；开发出的TbxDyt（1-x）Fe，合金，在较低的外磁场下就能达到超磁致伸缩效果，并对TbFez，DyFe2，Tb0.3Dy0.7Fe2（Terfenol-D）做了特性对比；超磁致伸缩材料在声频和超声技术方面广阔的应用前景，超磁致伸缩材料的应用及研究对发展声纳技术、水声对抗技术、海洋开发与探测技术将起到关键性作用。     

超磁致伸缩材料在骨传导听觉装置上的应用

超磁致伸缩材料(简称GMM)是制作低频换能器的理想功能材料。介绍了GMM的磁致伸缩机理及其本身特性;与传统磁致伸缩材料以及当前广泛应用在骨传导听觉装置上的电磁和压电材料进行了分析比较;综述了GMM在骨传导听觉装置上的应用现状;重点介绍了骨传导发音振子的设计构想,并且对超磁致伸缩式骨传导听觉装置在军事通信上的应用进行了展望。     

高压氧治疗29例一氧化碳中毒致迟发脑病的效果分析

论述了超磁致伸缩材料在电液控制元件中的应用研究现状,基于超磁致伸缩材料的特点和未来航空航天领域对高频大流量伺服阀的迫切需求,提出了一种由超磁致伸缩执行器驱动的新型射流伺服阀的结构,分析了其工作原理与特点,同时对该新结构伺服阀涉及的温度控制、热补偿、预压力施加与零位调节与驱动磁场均匀化等关键技术进行了详细分析并给出了具体实施方法.     

磁感应强度控制的超磁致微位移器电源研究

超磁致伸缩材料是近年发展起来的新型功能材料，应用于微位移驱动器时具有精度高、推力大等优点。在采用磁感应强度作为负反馈控制量的基础上，推导了从控制量得到代表驱动器位移信号的过程，设计了相应的高精度驱动电源。通过实验，对于超磁致伸缩微位移器驱动电源静态和动态特性作了详细的分析和研究。     

超磁致伸缩微位移驱动器的研究

新型超磁致伸缩材料ＴｂＤｙＦｅ具有输出力大、位移分辨力高及位移范围大等特点,将其应用于微位移驱动器中,将极大提高驱动器的性能指标,从而推动超精加工技术的发展。文中介绍了应用超磁伸缩材料研制的驱动器的结构及性能,并建立磁－机械耦合西式,以利于超磁致伸缩器件的研究及设计。     

超磁致伸缩薄膜性能测试系统研究

针对超磁致伸缩薄膜制备过程中所关心的性能测试问题,提出了利用外加磁场引起薄膜变形,运用微位移传感器测试薄膜变形的新方法,以此为基础,建立了超磁致伸缩薄膜性能测试系统,并通过本系统测试比较了不同条件下制备的Tbo.27 Dy0.73 Fe2 薄膜的磁性能.结果表明,在制备磁致伸缩薄膜材料过程中施加一个平行于薄膜长度方向的磁场,可得到更好的磁致伸缩性能.     

一种高压共轨喷油器的驱动电路设计

分析了高压共轨喷油器电磁阀工作原理,设计的驱动模块采用高电压、大电流对电磁阀的开启加以控制,随后采用低电压、小电流的PWM波维持导通,满足了高压共轨喷油器电磁阀驱动控制的要求。试验表明此驱动电路性能优异,设计运行可靠,能满足高压共轨喷油器电磁阀驱动控制的要求。     

基于自适应小生境混合遗传算法的说话人识别

为了解决传统高斯混合模型(Gaussian Mixture Model,GMM)对初值敏感,在实际训练中极易得到局部最优参数的问题,本文提出了一种GMM参数优化的新方法.将小生境技术与最大似然估计融入到遗传训练过程,形成了一种新的混合算法,缓解了遗传算法产生的"早熟"现象,提高了算法的局部搜索能力.采用自适应策略来控制交叉和变异算子,同时在适应度评价中融入了其他用户的区分性信息,提高了模型的分类精度,增强了GMM的泛化能力.实验表明,与传统和改进的两种方法相比,本文的方法都可以得到更优的模型参数,使得系统的识别率进一步提高.     

基于改进GMM与帧差法的运动棉杂率分析算法研究

针对清梳棉流程中产出棉含杂高、质量差的问题,结合改进高斯混合模型(Gaussian mixed model,GMM)与帧差法,提出一种局部运动棉杂率控制优化方法。首先针对清棉机除杂原理及棉杂特性进行分析;其次通过提取视频关键帧并改进GMM与帧差法对图像序列“与”运算实现目标的精确提取,进而通过设计GMM分类器获得棉杂率并进行分析;最后与传统的检测算法作对比验证。实验表明,改进后的算法在有效性以及实用性方面优于传统算法。同时,通过引入闭环控制能满足工业高精度、实时性的需求。     

Multiscale fragile watermarking based on the Gaussian mixture model.

In this paper, a new multiscale fragile watermarking scheme based on the Gaussian mixture model (GMM) is presented. First, a GMM is developed to describe the statistical characteristics of images in the wavelet domain and an expectation-maximization algorithm is employed to identify GMM model parameters. With wavelet multiscale subspaces being divided into watermarking blocks, the GMM model parameters of different watermarking blocks are adjusted to form certain relationships, which are employed for the presented new fragile watermarking scheme for authentication. An optimal watermark embedding method is developed to achieve minimum watermarking distortion. A secret embedding key is designed to securely embed the fragile watermarks so that the new method is robust to counterfeiting, even when the malicious attackers are fully aware of the watermark embedding algorithm. It is shown that the presented new method can securely embed a message bit stream, such as personal signatures or copyright logos, into a host image as fragile watermarks. Compared with conventional fragile watermark techniques, this new statistical model based method modifies only a small amount of image data such that the distortion on the host image is imperceptible. Meanwhile, with the embedded message bits spreading over the entire image area through the statistical model, the new method can detect and localize image tampering. Besides, the new multiscale implementation of fragile watermarks based on the presented method can help distinguish some normal image operations such as JPEG compression from malicious image attacks and, thus, can be used for semi-fragile watermarking.     

数控地毯样机选纱系统研究

为适应快速化、智能化生产需求,在传统纺机选纱机构基础上,提出一种新型数控地毯样机的选纱系统。该系统上位机采用Visual Basic 6.0进行系统软件开发,实现地毯图案花型数据读取与转换等功能。下位机综合运用GALIL运动控制卡、接近开关、电磁阀等部件实现系统运动控制。结果证明,该系统可自动进行纱线选取与漏纱检测,准确高效,满足生产要求,提高了样品质量和生产速度。     

High-quality voice conversion system based on GMM statistical parameters and RBF neural network

A voice conversion （VC） system was designed based on Gaussian mixture model （GMM） and radial basis function （RBF） neural network. As a voice conversion model, RBF network needs quantities of training data to improve its performance. For one speech, the networks trained by different segments of data have different transformation effects. Since trying segment by segment to obtain the best conversion effect is complex, a conversion method was proposed, that uses GMM for statistics before training RBF network to aim at the problem. The speech transformation and representation using adaptive interpolation of weighted spectrum （STRAIGHT） model is used for accurate extraction of vocal tract spectrum. Then GMM is used to classify the numerous spectral parameters. The obtained mean parameters were trained in RBF network. Experiment reveals that, the soft classification ability of GMM can promptly realize the reduction and classification of training data under the premise of ensuring the training effect. The selection complexity is decreased thereafter. Compared to the conventional RBF network training methods, this method can make the transformation of spectral parameters more effective and improve the quality of converted speech.     

用前腔面“泄漏激光”作为监控信号的AlGaAs/GaAs光纤耦合激光器

本文报导用前腔面“泄漏激光”作为监控信号的新方法。这种分光方式没有插入损失,跟踪线性。初步结果表明,它能满足目前通信系统自动光功率控制的要求。     

基于超级电容储能方式的秒级磁场

针对高功率微波(HPM)源的引导磁场需求,设计并研制了一套基于超级电容储能方式的秒级脉冲磁场系统。首先简要说明了基于超级电容储能方式磁场系统的基本原理和计算方法,接着详细讨论了超级电容磁场电源设计和对应的螺线管磁场线圈设计,最后通过模拟和实验验证了储能型磁场系统可以输出秒级磁场脉冲,满足高功率微波磁场需求。结果显示,超级电容脉冲磁场输出稳定,磁场位形较好,比较适宜于高功率微波源系统的外加磁场系统。最后分析了设计和仿真过程中的问题并展望了此类技术的应用前景。     

太阳能与空气能双热源热泵系统实验平台设计

为解决太阳能和空气能利用中存在的能量转换效率低的问题,设计了太阳能与空气能双热源热泵系统实验平台。实验平台主要由变频压缩机、PV/T蒸发器、风冷蒸发器、蓄热水箱、电子膨胀阀、数据采集与控制系统等组成,以太阳能和空气能作为热源,R134a作为制冷工质,通过控制电磁阀和电子膨胀阀,实现3种运行模式。利用PLC和组态软件实现实验参数采集与监控,并能开展一系列综合性、创新性实验,满足科研与专业教学的需要。     

New insight at level set & Gaussian mixture model for natural image segmentation

Level set method and Gaussian Mixture model (GMM) are two very valuable tools for natural image segmentation. The former aims to acquire good geometrical continuity of segmentation boundaries, while the latter focuses on analyzing statistical properties of image feature data. Some studies on the integration between them have been reported due to their complementarity in the last 10 years. However, these studies generally supposed that the image-featured data density distribution of every segmented domain is independent with each other and can be separately approximated by Gaussian model or GMM, which conflicts with the fundamental idea of GMM clustering-based image segmentation. To remedy this problem, we give a new insight at image segmentation objective under the combined framework between Bayesian theory and GMM density approximation. Thereby, a novel level set image segmentation method integrated with GMM (GMMLS) is proposed. Then, the theoretical analysis on GMMLS is given, in which some valuable results are demonstrated. At last, several types of natural image segmentation experiments are reported and the corresponding results indicate that GMMLS can obtain better or at least equivalent performance compared with existing relevant methods in almost all cases.