回转水纺线法制取锡金属细线的成线性研究

本文采用自制的“回转水纺线法”装置研制出圆截面金属锡连续细微线(线径 d=1.2×10^(-4)m)。通过 SEM 观察了各种参数下所形成的连续细微线的表面形态,文中在实验观察的基础上,进一步阐明了回转水纺线法的成线机理。

标准物质成线性检验的判定

介绍了标准物质制备及使用中成线性检验的2种检验方法,分析了成线性检验的判定依据,并给出了相关检验的临界值.

急性等容性贫血时心率成线性升高

背景 人类急性等容性贫血时心血管反应被认为不同于其它物种,麻醉下的人体研究发现心率下降或者没有改变。先前的研究显示32例健康未用药的人群中发生急性等容性贫血时心率升高。

基于频率成比例重分配线性Chirplet变换的时频分析方法

齿轮故障信号具有典型的调制特征,其各个频率分量的瞬时频率轨迹具有成比例特征;同时,传统的时频方法存在时频能量集中度低、弱分量信号被淹没的问题。为此,提出了一种频率成比例重分配线性Chirplet变换(PFSRLCT)的时频分析方法。首先,修改了线性Chirplet变换,利用新的核函数来匹配信号的瞬时频率轨迹,以获得时频域表示,利用脊线搜索方法提取了时频脊线;然后,利用时频脊线和狄拉克函数构造了同步重分配算子,对所得到的时频结果进行了重分配,进一步提高了时频能量集中度;最后,利用模拟信号验证了PFSRLCT方法的有效性,并将其与其他方法进行了比较;此外又将该方法应用于实际齿轮箱故障信号的诊断,从所得到的时频结果中可以清楚地分辨出啮合频率fm及其谐波和边频带,所诊断出的故障类型与预设故障类型符合,验证了该方法的适用性。研究结果表明:PFSRLCT在处理具有瞬时频率轨迹成比例特征的信号时,显示出了良好的性能,在信噪比为-2 dB~10 dB时,所得的频率估计误差均小于0.01,在信噪比为-1 dB时,所得Rényi熵仅为4.7451,均明显小于其他方法,证明该方法的噪声鲁棒性相较于其他方法更强,能量集中度更高;同时,该方法应用于实际齿轮故障信号时,所得Rényi熵仅为3.0698,明显低于其他方法,说明其可以获得更高的时频能量集中度,具有更好的表现能力。

BACH:线性混成系统有界可达性模型检验工具

混成自动机的模型检验问题非常困难,即使是其中相对简单的一个子类——线性混成自动机,它的可达性问题仍然是不可判定的.现有的相关工具大都使用多面体计算来判定线性混成自动机状态空间的可达集,复杂度高、效率低,无法解决实际应用规模的问题.描述了一个面向线性混成系统有界可达性模型检验工具——BACH(bounded reachability checker),该工具能够沿指定路径(组)对单个线性混成自动机、多个线性混成自动机的组合进行可达性检验,并且在此基础上结合路径遍历技术完成对所有路径的有界可达性检验.实验数据显示,BACH不仅在面向路径可达性检验方面性能优异,可以适用于足够长度的路径,而且在针对所有路径的有界可达性检验时,BACH可以解决的问题规模也远远超过同类工具,已接近工业界应用的要求.

成层地基非线性波动问题人工边界与波动输入研究

建立了考虑非线性效应的无限成层地基波动模拟的时域人工边界条件及相应的波动输入方法。首先,推导了线性阻尼介质中的一维人工边界公式,进而推广得到近似的二维人工边界方程;然后,通过等效线性化处理,获得了近似考虑远场成层地基非线性效应的人工边界;最后,建立了相应的波动输入方法。数值算例表明,所给出的人工边界与波动输入方法具有良好的精度,可以方便地应用于成层地基非线性波动问题的研究。

基于Craig插值的线性混成系统符号化模型检测

最强后件的计算是模型检测算法的核心.本文使用一阶逻辑可满足性模线性算术理论给出线性混成自动机的有界模型检测表示公式,利用一阶逻辑公式不可满足情况下的插值存在性定理,对线性混成自动机的有界模型检测公式进行指定的划分,使用支持线性算术插值计算的可满足性模理论后端证明引擎的线性时间复杂度的消解反证技术获得这两部分公式间的插值公式,按一阶逻辑Craig插值的性质,所得到的插值公式就是模型检测过程中最强后件公式的上近似表示.有效地避免了使用逻辑编码方案实现线性混成自动机模型检测过程中需要双指数时间复杂度的量词消去操作求取最强后件公式,也不需像有界模型检测按步长展开变迁公式进行可满足性判定.最后本文在此最强后件计算的基础上,以有界模型检测技术作为反例确认方法,实现了一种无假反例的混成系统近似可达集计算算法.实验证明该算法与目前已经得到广泛工业应用的有界模型检测算法相比具有更优的性能.

线性混成系统的参数分析

针对线性混成系统中存在的一类典型未知参数问题，如实时系统的验证通常局限于给定具体数值，未考虑系统中任何时间参数或物理特征参数的计算等，给出了具体的计算过程．实例应用表明，该计算过程可以有效地求解线性混成系统中这类未知参数，并能保证系统按照规约的要求正确运行．

基于迁移系统分析的线性混成系统安全验证

混成自动机行为中既包含离散行为又包含连续行为,非常复杂。其安全性验证问题难以解决,即使是线性混成自动机,它的可达性问题也被证明是不可判定的。现有工具大都使用多面体计算来计算线性混成自动机的可达状态空间集,复杂度高,可处理问题规模非常有限。为了避免这类问题,实现了一种新的工具。该工具将线性混成自动机表达为等价的迁移系统,并利用迁移系统上不变式生成相关工作对混成自动机进行验证。实验数据表明,方法有效可行,工具具有良好的性能。

基于EHD微纳尺度3D打印中导电银浆成线规律的实验研究

基于EHD微纳尺度3D打印技术(电喷印)是最具应用前景的微纳尺度3D打印技术之一。通过实验研究了电喷印过程中导电银浆体积浓度、喷印距离、喷印电压及喷印头移动速度对成线性能的影响。实验结果表明:外加电压在一定范围内能形成泰勒锥,过大或过小都会影响泰勒锥的形成;在此范围内存在最佳值2 000 V,使线宽最小。随着喷印头移动速度的变化,线宽变化显著,速度过小或过大分别导致线宽过大或无法成线的现象。导电银浆体积浓度过小会导致线宽过大、体积浓度过大导致粘度过大无法喷印;存在最佳值6:1使线宽最小。在一定的喷印距离0.05~0.1 mm的范围内变化时,可以形成稳定喷印。距离过大或过小会导致无法成线现象。

SVM自适应波束成形算法

在天线阵列过载,以及强干扰与期望用户信号夹角过近的情况下,传统的线性阵列信号处理算法,如MMSE(minimum mean-squareerror)、NLMS(Normalized Least Mean Squares)等表现并不理想。SVM(SupportVectorMachine)是机器学习领域的最新成果,有较强的泛化能力,收敛快以及低复杂度等优点。本文提出了在上行波束成形中使用SVM算法,提高空域滤波的分辨率,与其他相关算法相比较,系统性能有了明显的改进。

高破片率弹钢光谱分析标准物质的研制

研制高破片率弹钢光谱分析标准物质。采用合理的熔炼工艺保证了标准物质的均匀性,检验结果表明该标准物质均匀性、稳定性良好。采用8家实验室协作定值,确定了C,Mn,Cr,Si,P等11种元素的标准值,对定值结果的不确定度进行了评定。对本套标准物质的定值元素进行线性考查,线性相关系数均在0.98以上。与国内同类标准物质相比,该套标准物质成分覆盖广,定值元素多,定值方法准确可靠。

Effect of Zr and Sc on mechanical properties and electrical conductivities of Al wires

In order to obtain the Al wires with good mechanical properties and high electrical conductivities, conductive wires of Al-0.16 Zr, Al-0.16 Sc, Al-0.12Sc-0.04Zr（mass fraction, %） and pure Al（99.996%） were produced with the diameter of 9.5 mm by continuous rheo-extrusion technology, and the extruded materials were heat treated and analyzed. The results show that the separate additions of 0.16% Sc and 0.16% Zr to pure Al improve the ultimate tensile strength but reduce the electrical conductivity, and the similar trend is found in the Al-0.12Sc-0.04 Zr alloy. After the subsequent heat treatment, the wire with the optimum comprehensive properties is Al-0.12Sc-0.04 Zr alloy, of which the ultimate tensile strength and electrical conductivity reach 160 MPa and 64.03%（IACS）, respectively.

飞秒激光光谱技术在燃烧领域的应用

基于飞秒激光的燃烧诊断技术,可实现燃烧场温度、速度、组分浓度等参数的在线测量。作为一种有效的诊断工具,飞秒激光诊断技术在燃烧领域中有着广泛的应用前景,将在提高燃烧效率和降低燃烧排放等方面发挥越来越重要的作用。本文通过综述飞秒多光子激光诱导荧光技术、飞秒激光成丝诱导非线性光谱技术以及飞秒激光电子激发示踪测速技术等飞秒激光在燃烧领域的具体应用实例,概括介绍了飞秒激光燃烧诊断技术的发展。在此基础上,对飞秒激光燃烧诊断技术在未来的发展潜力进行了分析与讨论,为相关研究人员提供参考。

Synthesis and photoluminescence properties of single-crystal ZnO hexagonal pyramids by PEG400-assisted thermal decomposition route

Large-scale synthesis of ZnO hexagonal pyramids was achieved by a simple thermal decomposition route of precursor at 240 oC in the presence of PEG400. The precursor was obtained by room-temperature solid-state grinding reaction between Zn（CH3COO）2-2H2O and Na2CO3. Crystal structure and morphology of the products were analyzed and characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, transmission electron microscopy （TEM） and high-resolution transmission electron microscopy （HRTEM）. The results of further experiments show that PEG400 has an important role in the formation of ZnO hexagonal pyramids. Difference between the single and double hexagonal pyramid structure may come from the special thermal decomposition reaction. The photoluminescence （PL） spectra of ZnO hexagonal pyramids exhibit strong near-band-edge emission at about 386 nm and weak green emission at about 550 nm. The Raman-active vibration at about 435 cm-1 suggests that the ZnO hexagonal pyramids have high crystallinity.

Resistivity Instability in Polysilicon Resistors Under Metal Interco-nnects and Its Suppression by Compensating Ion Implantation

The resistivity instability of the boron-doped polysilicon resistors being a line resistance element of ICs is within the range of several kΩ's,especially when our running the underneath metal interconnects.Polysilicon resistors have been fabricated under various processing conditions as well as some electrical and crystallographic characteristics have been obtained.It is shown the resistivity instability mainly results from the variational carrier mobility.By analyzing the Seto's model,the barrier height and trapped charge density are observed reducing under the Al over layer.Therefore,the resistance instability is also caused by both the charge trapping/detrapping occurring at polysilicon grain boundaries and the resultant variation in the potential barrier height.The formation of high-stability polysilicon resistors in the range of several kΩ's has been decided by compensating the ion implantation,which makes the charge trapping/detrapping at the grain boundary less susceptible to the hydrogen annealing.

Mixed Gl2／GH2 multi-channel multi-objective control synthesis for discrete time systems

This paper proposes a new approach for multi-objective robust control. The approach extends the standard generalized l2 (Gl2) and generalized H2 (GH2) conditions to a set of new linear matrix inequality (LMI) constraints based on a new stability condition. A technique for variable parameterization is introduced to the multi-objective control problem to preserve the linearity of the synthesis variables. Consequently, the multi-channel multi-objective mixed Gl2/GH2 control problem can be solved less conservatively using computationally tractable algorithms developed in the paper.

Low-dimensional multi-spectral space for color reproduction based on nonnegative constrained principal component analysis

In order to overcome the shortcomings that the reconstructed spectral reflectance may be negative when using the classic principal component analysis （PCA）to reduce the dimensions of the multi-spectral data, a nonnegative constrained principal component analysis method is proposed to construct a low-dimensional multi-spectral space and accomplish the conversion between the new constructed space and the multispectral space. First, the reason behind the negative data is analyzed and a nonnegative constraint is imposed on the classic PCA. Then a set of nonnegative linear independence weight vectors of principal components is obtained, by which a lowdimensional space is constructed. Finally, a nonlinear optimization technique is used to determine the projection vectors of the high-dimensional multi-spectral data in the constructed space. Experimental results show that the proposed method can keep the reconstructed spectral data in [ 0, 1 ]. The precision of the space created by the proposed method is equivalent to or even higher than that by the PCA.

Optimization of solar thermal power station LCOE based on NSGA-Ⅱ algorithm

In view of the high cost of solar thermal power generation in China,it is difficult to realize large-scale production in engineering and industrialization.Non-dominated sorting genetic algorithm II(NSGA-II)is applied to optimize the levelling cost of energy(LCOE)of the solar thermal power generation system in this paper.Firstly,the capacity and generation cost of the solar thermal power generation system are modeled according to the data of several sets of solar thermal power stations which have been put into production abroad.Secondly,the NSGA-II genetic algorithm and particle swarm algorithm are applied to the optimization of the solar thermal power station LCOE respectively.Finally,for the linear Fresnel solar thermal power system,the simulation experiments are conducted to analyze the effects of different solar energy generation capacities,different heat transfer mediums and loan interest rates on the generation price.The results show that due to the existence of scale effect,the greater the capacity of the power station,the lower the cost of leveling and electricity,and the influence of the types of heat storage medium and the loan on the cost of leveling electricity are relatively high.