Analytical model of variable characteristic of coefficient of restitution and its application to ball trajectory planning

In this article, we investigate the behavior of the coefficient of restitution (COR) which is an important parameter in many impact-related fields. In many cases, the COR is considered as a constant value, but it varies according to many variables. In this paper, we introduce an analytical variable COR model considering aerodynamics along with its verification through experiment. To introduce and analyze the variable characteristic of the COR model, the collision phenomenon between a pendulum and two kinds of ball is employed as an example and aerodynamics such as drag force is considered for analyzing the after-effect of the collision. Collision velocity of the pendulum, dynamic parameters of colliding bodies, contact time, drag coefficient, the air density, and the cross-sectional area of the ball are found as the typical variables of analytical COR model. This observation generalizes the result in previous researches. To verify new COR model, the travel distances for the curve-fitted constant COR model and the curve-fitted variable COR model are compared through simulation and experiment. Moreover, comparison between constant COR and variable COR is presented in several points of view. Finally, using the variable COR model, the travel distance of the ball for given collision velocity can be estimated.     

On a statistical damage constitutive model for rock materials

A statistical damage constitutive model for rocks with strain softening behaviour is put forward, using the theory of continuous damage mechanics together with statistical mesoscopic strength theory based on maximum entropy distribution. In statistical constitutive modelling, the probabilistic distribution of mesoscopic element strength in rocks is a critical piece of information, which was conventionally described by various empirical distributions among which the Weibull distribution was extensively used. In this paper, an alternative and universal distribution, i.e. maximum entropy distribution, is proposed to describe the statistical property of mesoscopic strength in rocks. By incorporating the entropy distribution information into a damage variable, the paper derives a new constitutive model, which is verified by conventional triaxial experiments and dynamic experiments on rock specimens. To illustrate suitability and flexibility, the new model is compared to the well-established Weibull-distribution-based models.     

采煤机参数与煤岩硬度关系公式修正系数研究

针对当前煤矿综采工作面采煤机无法自动、准确识别煤岩性状的问题,分析了采煤机截割电动机参数与反映煤岩硬度的普氏系数的关系公式,得出两者近似成比例线性关系;通过实测数据,得到关系公式中修正系数的取值范围;最后通过实际应用验证了根据修正系数推断出的普氏系数与实际情况相符。     

A two-temperature model of hydrate-bearing rock

A two-temperature model for describing the temperature field of a heat source in a hydrate-bearing rock is proposed. For the water/ice phase, the enthalpy formulation of the Stefan problem is used. Numerical simulation is accomplished through the finite element method.     

基于摩擦系数的扩散模型

根据分子间摩擦系数与组分自扩散系数关系,提出一个新的互扩散系数模型。模型分为3部分：组成项、自扩散系数和化学势与组分关系。采用文献自扩散系数值,并用不同状态方程以计算化学势与组分关系,模拟1 132～1 810℃之间不同组成二氧化碳气体混合物的互扩散系数,并与实验值做了比较。结果表明采用Peng-Robinson(PR),Redlich-Kwong(RK)及Van der Waals(VdW)方程计算化学势与组分关系而得到的模拟结果优于Virial方程,且平均误差在5%之内。     

A digital rock density map of New Zealand

Digital geological maps of New Zealand (QMAP) are combined with 9256 samples with rock density measurements from the national rock catalogue PETLAB and supplementary geological sources to generate a first digital density model of New Zealand. This digital density model will be used to compile a new geoid model for New Zealand. The geological map GIS dataset contains 123 unique main rock types spread over more than 1800 mapping units. Through these main rock types, rock densities from measurements in the PETLAB database and other sources have been assigned to geological mapping units. A mean surface rock density of 2440 kg/m³ for New Zealand is obtained from the analysis of the derived digital density model. The lower North Island mean of 2336 kg/m³ reflects the predominance of relatively young, weakly consolidated sedimentary rock, tephra, and ignimbrite compared to the South Island’s 2514 kg/m³ mean where igneous intrusions and metamorphosed sedimentary rocks including schist and gneiss are more common. All of these values are significantly lower than the mean density of the upper continental crust that is commonly adopted in geological, geophysical, and geodetic applications (2670 kg/m³) and typically attributed to the crystalline and granitic rock formations. The lighter density has implications for the calculation of the geoid surface and gravimetric reductions through New Zealand.     

一种重力敏感器阻尼系数测试方法

当重力敏感器内部充满阻尼液时,其表体内弹性系统的阻尼系数由阻尼液粘度和敏感器内部结构共同决定.提出了一种实际测量重力敏感器阻尼系数的测试方法.分析了重力敏感器的阻尼系数和内部结构的关系,给出了敏感器工作原理模型,推导出敏感质量振幅的函数关系式.通过在力矩线圈上施加不同频率、不同幅值的激励源信号并测试敏感质量振幅的方式,绘制出不同阻尼系数下敏感质量的振幅-频率关系曲线,将之与理论函数曲线对照来确定相应的阻尼系数值.试验结果表明:该阻尼系数测试方法能够有效地测试出充满不同粘度阻尼液的重量敏感器的阻尼系数,为阻尼液粘度的选取和控制回路的设计提供参考.     

A modal decomposition of the Hopf normal form coefficient

The local stability of a nonlinear dynamical system at an equilibrium point with a pair of purely imaginary eigenvalues can be assessed through the computation of a cubic Hopf normal form coefficient, assuming the remaining eigenvalues have negative real parts. In this paper, a modal decomposition of the Hopf coefficient is proved. The decomposition provides a new methodology for analyzing the Hopf cubic normal form coefficient in a formal way. The framework is illustrated by nonlinear stability analysis of two control designs where it is shown that the Hopf coefficient can be stabilized through modal nonlinear feedbacks     

A flexible coefficient smooth transition time series model

We consider a flexible smooth transition autoregressive (STAR) model with multiple regimes and multiple transition variables. This formulation can be interpreted as a time varying linear model where the coefficients are the outputs of a single hidden layer feedforward neural network. This proposal has the major advantage of nesting several nonlinear models, such as, the self-exciting threshold autoregressive (SETAR), the autoregressive neural network (AR-NN), and the logistic STAR models. Furthermore, if the neural network is interpreted as a nonparametric universal approximation to any Borel measurable function, our formulation is directly comparable to the functional coefficient autoregressive (FAR) and the single-index coefficient regression models. A model building procedure is developed based on statistical inference arguments. A Monte Carlo experiment showed that the procedure works in small samples, and its performance improves, as it should, in medium size samples. Several real examples are also addressed.     

A program to calculate a general recoupling coefficient

Title of adaptation: ADAPT TO INTEGER ARITHMETIC Adaptation number: 0002 Reference to original program:Catalogue number: AAGD; Title: NJSYM; Ref. in CPC: 1 (1970) 241 Author of original program: P.G. Burke Computer: ICL 1906A, Installation: Oxford University; Oxford, England; IBM 370/165; C.I.R.C.E., Orsay, France. Operating system: GEORGE 3 No. of cards required to effect adaptation (including directive cards): 176 Card punching code: EBCDIC     

高电源抑制比低温漂带隙基准源设计

设计并实现了一种新的高PSRR、低TC带隙基准源。重点研究了带隙基准源电源抑制能力,尤其是高频PSRR,达到宽频带范围PSRR高性能指标。采用0.35μm BiCMOS工艺进行仿真,结果表明,PSRR在1 Hz频率下达-108.5 dB,在15 MHz频率下达-58.9 dB;采用二次温漂补偿电路使得带隙基准源常温下输出参考电压1.183 V,在-40℃⁹5℃温度范围内,温漂系数低达1.5 ppm/℃。     

A machine level based-similarity coefficient for forming manufacturing cells

In cellular manufacturing literature, early work heavily focused on the use of routers as a way of forming product families and manufacturing cells. later, several measures of similarity among machines and parts have been proposed by different authors. Similarity coefficients use more data in addition to the machines visited. In this paper, a new similarity coefficient is proposed which incorporates not only the type of machines but also the level (number) of machines required. The potential benefits of the proposed similarity coefficient is demonstrated with an example problem using three clustering algorithms namely, SLINK, ALINK and CLINK. The results obtained by using this new similarity coefficient are compared with those of the Jaccard's Similarity Coefficient.     

A strategy for coefficient quantization in digital control algorithms

A strategy for quantizing the coefficients in a general second order digital control algorithm is presented. First, the errors in the magnitude and phase functions for the algorithm are derived in terms of the filter coefficients. By specifying a maximum allowable error for each function over a given frequency range, quantization regions can then be established. An example consisting of a lag-lead digital control algorithm is included to illustrate the procedure.     

A blind watermarking method using maximum wavelet coefficient quantization

This paper proposes a blind watermarking algorithm based on maximum wavelet coefficient quantization for copyright protection. The wavelet coefficients are grouped into different block size and blocks are randomly selected from different subbands. We add different energies to the maximum wavelet coefficient under the constraint that the maximum wavelet coefficient is always maximum in a block. The watermark is embedded the local maximum coefficient which can effectively resist attacks. Also, using the block-based watermarking, we can extract the watermark without using the original image or watermark. Experimental results show that the proposed method is quite robust under either non-geometry or geometry attacks.     

The production data-based similarity coefficient versus Jaccard''s similarity coefficient

This paper compares the performance of Jaccard's similarity coefficient with the production data-based similarity coefficient. A number of machine-component charts taken from the literature or randomly generated are used to form machine-component groups. Then, the sum of intercellular and intracellular material handling costs for each machine-component group is calculated and used as a basis for performance evaluation of the two similarity coefficients.     

A method of solving the coefficient inverse problems of wave tomography

In this paper, the problem of nonlinear wave tomography is formulated as a coefficient inverse problem for a hyperbolic equation in the time domain. Efficient methods for solving the inverse problems of wave tomography for the case of transparent boundary conditions are presented. The algorithms are designed for supercomputers. We prove the Fréchet differentiability theorem for the residual functional and derive an exact expression for the Fréchet derivative in the case of a transparent boundary in the direct and conjugate problems. The expression for the Fréchet derivative of the residual functional remains valid if the experimental data are provided for only a part of the boundary. The effectiveness of the proposed method is illustrated by the numerical solution of a model problem of low-frequency wave tomography. The model problem is tailored to apply to the differential diagnosis of breast cancer.     

A method for transformation of engineering bill of materials to maintenance bill of materials

In order to solve the transformation problem of Bill of Materials (BOM) from engineering BOM to maintenance BOM for Maintenance, Repair and Overhaul (MRO) systems, a formal transformation model of BOM view is proposed. In this model, the intermediate component, inherited component, virtual component are defined in the specific maintenance management domain, and the transformation process from engineering BOM to maintenance BOM is discussed through feature recognition methods and rules. The proposed transformation model has been developed and deployed in an MRO system for a steel manufacturing enterprise.     

A new approach to bootstrap inference in functional coefficient models

To infer on functional dependence of regression parameters, a new, factor based bootstrap approach is introduced, that is robust under various forms of heteroskedastic error terms. Modeling the functional coefficient parametrically, the bootstrap approximation of an F-statistic is shown to hold asymptotically. In simulation studies with both parametric and nonparametric functional coefficients, factor based bootstrap inference outperforms the wild bootstrap and pairs bootstrap approach, according to its rejection frequencies under the null hypothesis. Applying the functional coefficient model to a cross sectional investment regression on savings, the saving retention coefficient is found to depend on third variables as the population growth rate and the openness ratio.     

A modified coefficient ideal for use with the strict transform

Two main algorithmic approaches are known for making Hironaka’s proof of resolution of singularities in characteristic zero constructive. Their main differences are the use of different notions of transforms during the resolution process and the different use of exceptional divisors in the descent in ambient dimension. In this article, we focus on the first difference. Only the approach using the weak transform has up until now been successfully used in implementations, because the other one requires an explicit stratification by the Hilbert-Samuel function at each step of the algorithm which is highly impractical due to the high complexity of the computation of such a stratification. In this article, a (hybrid-type) algorithmic approach is proposed which allows the use of the strict transform without the full impact of the complexity of the stratification by the Hilbert-Samuel function at each step of the desingularization process. This new approach is not intended to always be superior to the previously implemented one, instead it has its strengths precisely at the weak point of the other one and is thus a candidate to be joined with it by an appropriate heuristic.     

基于柔化矩阵的广义预测控制快速算法

本文针对输入要求平稳的系统设备提出了一种预测控制新算法.该算法通过对输入增量引入柔化系数矩阵从而进行约束,避免了矩阵求逆的计算,大大减少了计算量,确保了系统的快速性,同时保留了广义预测控制的基本特征.其次,控制算法中改善了传统广义预测控制算法的单一性,充分利用预测信息的补偿作用进行加权平均,很好得抑制了超调的出现.通过挤出机的压力系统做仿真试验,结果验证了该算法的有效性.