量子物理的思维范式对长度计量研究创新的启发

一、引言有人如是说:"任何哲学革命首先在于它提供了一种崭新的思维范式,也正是这种崭新的思维范式才导致了哲学的革命。"哲学对其他科学具有指导作用,新的哲学思维范式会对科技革命产生促进     

使用有限元和无限元耦合求解声辐射问题

使用有限元和无限元方法耦合求解了封闭空间的声辐射问题,根据求得的声源表面的信息,利用克希荷夫公式来求解整个外声场.这种方法和边界元方法相比,在达到相同的求解精度情况下,计算效率得到极大的提高,而且使用这种方法求解声辐射问题时计算简单,易于推广.     

卷积方程的拟合求解法

本文提出卷积方程的一种求解方法.它可用于根据实洲数据辨识一个参数未知的线性平移不变系统.利用所述方法可依次确定系统的阶数、极点和系数。最后,我们讨论了误差情况和给出了数值例子,表明所提出的方法是可行的。     

求解刚-柔组合结构的隐式-显式混合法

针对整体柔性、局部刚性的组合结构系统的动力反应分析,推出了一种隐式-显式混合算法的逐步积分方法.这种混合求解方法,在一个算法步中,对柔性部分采用显式方法求解,对刚性部分则采用隐式方法求解,充分利用了隐式算法无条件稳定的优点和显式算法计算高效的优点.混合法稳定域大小表达式中的频率为柔性部分的最高频率,而不是整体结构的最高频率,这就避开了局部刚性导致显式算法时间步长需要过于细化的缺点.这种方法可以作为一种高效的逐步积分方法,用来求解土-结构相互作用、液固耦合系统等的动力反应.算例表明了方法的正确性.     

一种新型SH波传播特性研究

1.引言 Michio Kadota等于2001年首次提出了一种在 ST-90°X石英基片上利用重金属制成的叉指换能器与反射栅而激发的一种新型剪切(SH)波.这种波具有较大的机电耦合系数和反射系数,良好的频率温度特性.Michio Kadota等人已经将这种SH波应用于实现一种小型化的谐振器式滤波器[1][2] [3],取得了好的实际效果.Michio Kadota等人是利用Campbell的方法对这种波的传播特性即传播速度以及机电耦合系数来进行分析与求解的[4],这种方法比较烦琐,也不利于进一步扩展其应用,研究其特性.本文利用层状介质中波的传播的方法求解[5],求解过程简单准确.本文给出了求解的过程以及计算结果,并与前人的计算结果进行了对比,结果表明了其较好的一致性.     

求一类矩阵方程组的最小二乘中心对称解及其最佳逼近的迭代法

本文提出了求一类矩阵方程组的最小二乘中心对称解的一种迭代法.通过这种方法,对任意初始的中心对称矩阵,在没有舍入误差的情况下,经过有限步迭代,得到它的一个最小二乘中心对称解.并且,通过选择一种特殊的初始中心对称矩阵,得到它的最小范数中心对称解.另外,给定中心对称矩阵,利用此方法可得到它的最佳逼近中心对称解.数值例子表明,这种方法是有效的.     

滑动索系结构的统一分析方法——冷冻-升温法

结构工程中存在大量的滑动索系结构,但目前还没有有效的计算方法求解这种结构的内力和变形,因而使得这种结构的理论研究滞后于它的工程应用。提出了一种新颖、有效、通用的处理方法,称为冷冻-升温法(FHM),能有效地解决采用钢索滑移节点对计算结构内力和变形存在的困难。通过对不同算例进行分析,说明了这种方法的通用性和有效性。     

对于Broyden方法和Schubert方法Kantorovich型分析的一些改进

1.引言 在对一些求解非线性方程组F(x)=0的方法所进行的Kantcrcvich型分析中,对于h的限制起着关键的作用。因为它实质上就是对于F(x_0)的值的限制,它的大小决定了初始近似X_0选择区域的大小。因此放宽这种限制的工作是有意义的。熟知,在Newton法Kanto-     

格构塔架顺风位移响应实用计算模型与求解内力位移加载法

基于风洞试验得到的格构式塔架顺风向一阶广义荷载谱,利用导出的实用高阶广义荷载谱,进一步导出了位移反应的实用计算公式,提出了"位移加载"求解格构塔架内力的方法,并以-输电塔为例描述了该方法的实现过程.与已有方法相比,计算公式可考虑高阶模态的贡献且推导过程更加合理,建议的内力求解方法可避免传统方法中需要建立等效静力风荷载的这一步骤.针对格构式高耸结构,文中位移计算公式实用,内力求解方法合理、操作简单,可进一步推广应用.     

非线性耦合系统的变分迭代算法

本文提出了求解非线性耦合系统的一种迭代算法,这种方法是应用广泛拉氏乘子构造较正泛函,然后用变分理论最佳识别。这种方法对初近似不敏感,也没有“小参数”的限制,可广泛用于非线性振动问题。     

弧焊电源温升自动测试微机系统

弧焊电源温升自动测试微机系统以微机为核心，外围设备有显示器、磁盘动器、打印机等。在温升试验时，通过微机控制焊接通、断电时间、并适时采样，进行数据处理，温度显示，而且适时记录各参数，实现试验过程的全自动化。     

悬臂梁防振包装系统功率流研究

将子结构导纳法和当量导纳技术相结合，采用连续隔振器模型，对通过连续隔振器流入悬臂梁式结构的包装体的功率流进行研究，从功率流的角度提出避免共振破坏，提高防振包装效果的条件和参数选择方法。     

Geometry-based machining precedence reasoning for feature-based process planning

This paper presents a method to generate machining precedence relations systematically based on the geometric information of the part. The feature recognition method using Alternating Sum of Volumes with Partitioning (ASVP) Decomposition is applied to obtain a Form Feature Decomposition (FFD) of a part model. Form features are classified into a taxonomy of atomic machining features to which machining process information has been associated. Geometry-based precedence relations between features are systematically generated using the face dependency information obtained by ASVP Decomposition and the features' associated machining process information. Multiple sets of precedence relations are generated as alternative precedence trees based on the feature types and machining process considerations. These precedence trees can be further enhanced with precedence relations from tolerance specifications and machining expertise. Machining sequence planning can be performed for each of these precedence trees while minimizing the number of tool changes. The precedence trees may then be evaluated based on machining cost and other criteria. The precedence-reasoning module is currently being implemented within a comprehensive computer-aided process planning system.     

Dirichlet自由变形方法及其在建立尺寸驱动人体模型中的应用

自由变形(Free-FormDeformation,FFD)是与物体表示无关的变形方法的重要分支,被广泛地应用于计算机动画和几何建模领域中。Dirichlet自由变形(DirichletFree-FormDeformation,DFFD)是众多自由变形方法中的一种。相比其它的自由变形方法,它有更大的灵活性,能够任意设置控制点。简要论述了各种Dirichlet自由变形方法及其扩展,同时提出了建立在非Sibson坐标系统上的Dirichlet自由变形方法,最后应用它们定义了一种可由身高、胸围等服装领域关心的尺寸和体形特征进行驱动的人体模型。     

多酮基聚芳醚酮的结晶行为

以1,3-二(4-氯甲酰基苯甲酰基)苯(i-DMBC)和1,4-二(4-苯氧基苯甲酰基)苯(p-DPOPKK)为单体,通过低温溶液共缩聚反应合成了主链含多酮基的聚芳醚酮。用差示扫描量热法(DSC)及广角X射线衍射(WAXD)技术研究了含多酮基聚芳醚酮的结晶行为。研究结果表明,多酮基聚芳醚酮聚合物中存在多晶型,通过等温结晶、冷牵伸取向等方式对熔融-淬火处理后的无定型聚合物进行诱导结晶,可以改变聚合物的结晶度及结构中不同晶型的比例。     

Understanding stability relationships among three curcumin polymorphs

Understanding thermodynamic stability relationship among polymorphs of any active pharmaceutical ingredient (API) is a necessary step for drug formulation development. Knowledge of such relationship enables identification of a stable polymorphic form at the prevalent conditions. Curcumin, a pharmaceutically active ingredient found in herbal spice turmeric, exists in three polymorphic forms; a monoclinic form (Form 1) and two orthorhombic forms (Form 2 and Form 3). However, thermodynamic stability relationships among curcumin polymorphs have not been ascertained yet. This work therefore, was focused on understanding thermodynamic stability relationships among curcumin polymorphs. During purification of curcumin, the pressure applied for vacuum evaporation of organic solvent was found to significantly affect the polymorphic outcome. Form 1 was obtained at pressures ranging from 300 to 400?mbar whereas Form 2 was obtained at pressures ranging from 100 to 200?mbar. Form 3 was obtained by liquid antisolvent precipitation using ultrasound and Bovine Serum Albumin (BSA) as an additive. The obtained polymorphs were characterized by X-ray diffraction (XRD) and Differential Scanning Calorimetry (DSC) techniques. Relative stability of polymorphs was established by conducting solvent mediated transformation studies, thermal analysis through DSC and variable temperature X-ray diffraction studies (VT-XRD). It was observed that Form 2 and Form 3 irreversibly convert to Form 1 upon heating. Further, Form 2 and Form 3 convert to Form 1 in aqueous organic solutions at temperatures ranging from 0?°C to 50?°C. Thus, the curcumin polymorphs were found to be monotropically related to each other with the monoclinic form (Form 1) being the most stable form.     

X-Ray Powder Diffraction Study on the Grinding Effect of the Polymorphs of a Novel and Orally Effective Uricosuric Agent: FR76505

The polymorphism of a novel and orally effective uricosuric agent, [3-(4-bromo-2-fluorobenzyl)-7-fluoro-2,4-dioxo-1,2,3,4-tetrahydro-quinazolin-1-yl] acetic acid, designated as FR76505, was characterized by X-ray powder diffractometry and thermal analysis. In the crystalline state, FR76505 exists in at least three polymorphic forms, Forms A, B and C. Among them, Form B is a stable form, and Forms A and C which are transformed to Form B are metastable forms. Form C was not stable enough to keep its state even at room temperature. Therefore, it was not suitable to be used for the pharmaceutical preparation, and further investigation for Form C was not carried out. The mechanochemical effect of grinding makes the crystallite size smaller and the lattice strain larger for both the Forms A and B crystals. After grinding for 60 minutes, both forms changed into noncrystalline powders. Thermal behavior of the ground sample was investigated by the X-ray powder diffractometry under the heating condition, as well as the thermal analysis. It is concluded that the mechanochemical effect of grinding made Form A change into Form B easily, and the increase of a grinding time led the transformation temperature lower.     

X-Ray Powder Diffraction Study on the Grinding Effect of the Polymorphs of a Novel and Orally Effective Uricosuric Agent: FR76505

The polymorphism of a novel and orally effective uricosuric agent, [3-(4-bromo-2-fluorobenzyl)-7-fluoro-2,4-dioxo-1,2,3,4-tetrahydro-quinazolin-1-yl] acetic acid, designated as FR76505, was characterized by X-ray powder diffractometry and thermal analysis. In the crystalline state, FR76505 exists in at least three polymorphic forms, Forms A, B and C. Among them, Form B is a stable form, and Forms A and C which are transformed to Form B are metastable forms. Form C was not stable enough to keep its state even at room temperature. Therefore, it was not suitable to be used for the pharmaceutical preparation, and further investigation for Form C was not carried out. The mechanochemical effect of grinding makes the crystallite size smaller and the lattice strain larger for both the Forms A and B crystals. After grinding for 60 minutes, both forms changed into noncrystalline powders. Thermal behavior of the ground sample was investigated by the X-ray powder diffractometry under the heating condition, as well as the thermal analysis. It is concluded that the mechanochemical effect of grinding made Form A change into Form B easily, and the increase of a grinding time led the transformation temperature lower.     

基于模糊c均值聚类算法的控制图模式识别

控制图模式识别能够区分制造过程中的一般因素与异常因素,提高制造过程中的产品质量,减少成本,提高效益。利用蒙特卡洛方法产生样本;采用一维离散小波变换处理原始数据;利用模糊c均值聚类算法进行控制图模式识别。识别准确率99.43%,其标准差为0.002 8。这表明基于该方法的控制图模式识别准确率高,稳定性好,较现有的控制图模式识别方法具有简易、高效等特点。     

The work function of doped polyaniline nanoparticles observed by Kelvin probe force microscopy

The work function of polyaniline nanoparticles in the emeraldine base state was determined by Kelvin probe force microscopy to be ～270 meV higher than that of similar nanoparticles in the emeraldine salt state. Normal tapping mode atomic force microscopy could not be used to distinguish between the particles due to their similar morphologies and sizes. Moreover, other potential measurement systems, such as using zeta potentials, were not suitable for the measurement of surface charges of doped nanoparticles due to their encapsulation by interfering chemical groups. Kelvin probe force microscopy can be used to overcome these limitations and unambiguously distinguish between the bare and doped polyaniline nanoparticles.