全角模式半球谐振陀螺阻尼误差补偿方法研究

全角(WA)模式作为一种新型陀螺控制模式,可使陀螺具有高动态范围和稳定的标度因数,有广阔的发展前景。而阻尼不均匀是影响全角模式陀螺精度的重要因素。在研究全角模式下的运动模型和控制方案基础上,针对半球谐振陀螺阻尼不均匀导致的速率阈值和振型角漂移现象,创造性地提出了振型自进动和前馈阻尼补偿相结合的补偿方案。通过试验测试,半球谐振陀螺在经过补偿后突破了原先0.01°/s的速率阈值,并且其输出波动由0.37°降低到了0.048°。该方法达成的周向阻尼不均匀性的标定与补偿作用不局限于半球谐振陀螺,对于其他类型的哥氏振动陀螺,也能够起到同样的效果,对降低陀螺由阻尼不均匀引起的误差有重要意义。

Simulation and experimental validation of three-dimensional dendrite growth

A three-dimensional （3-D） modified cellular automaton （MCA） method was developed for simulating the dendrite morphology of cubic system alloys. Two-dimensional （2-D） equations of growth velocities of the dendrite tip, interface curvature and anisotropy of the surface energy were extended to 3-D system in the model. Therefore, the model was able to describe the morphology evolution of 3-D dendrites. Then, the model was applied to simulate the mechanism of spacing adjustment for 3-D columnar dendrite growth, and the competitive growth of columnar dendrites with different preferred growth orientations under constant temperature gradient and pulling velocity. Directional solidification experiments of NH4Cl-H2O transparent alloy were performed. It was found that the simulated results compared well with the experimental results. Therefore, the model was reliable for simulating the 3-D dendrite growth of cubic system alloys.

Computation of lower derivatives of rational triangular Bézier surfaces and their bounds estimation

By introducing the homogenous coordinates, degree elevation formulas and combinatorial identities, also by using multiplication of Bernstein polynomials and identity transformation on equations, this paper presents some explicit formulas of the first and second derivatives of rational triangular Bézier surface with respect to each variable (including the mixed derivative) and derives some estimations of bound both on the direction and magnitude of the corresponding derivatives. All the results above have value not only in surface theory but also in practice.

Finding Dirac Spin Effect in NUT Spacetime

In the present study, we are interested in finding the spin precession of a Dirac particle in expanding and rotating NUT spaeetime. A tetrad with two functions to be determined is applied to the field equation of the teleparallel theory of gravity via a coordinate transformation. The vector, the axial-vector and the tensor parts of the torsion tensor are obtained. We found that the vector parts are in the radial and Ф-directions. The axial-vector torsion is along r-direction while its other components along θ and oh-directions vanish everywhere. The vector connected with Dirac spin has been evaluated as well.

An Immune Self-adaptive Differential Evolution Algorithm with Application to Estimate Kinetic Parameters for Homogeneous Mercury Oxidation

A new version of differential evolution （DE） algorithm, in which immune concepts and methods are applied to determine the parameter setting, named immune self-adaptive differential evolution （ISDE）, is proposed to improve the performance of the DE algorithm. During the actual operation, ISDE seeks the optimal parameters arising from the evolutionary process, which enable ISDE to alter the algorithm for different optimization problems and improve the performance of ISDE by the control parameters＇ self-adaptation. The .performance of the proposed method is studied with the use of nine benchmark problems and compared with original DE algorithm ~nd-other well-known self-adaptive DE algorithms. The experiments conducted show that the ISDE clearly outperforms the other DE algorithms in all benchmark functions. Furthermore, ISDE is applied to develop the kinetic model for homogeneous mercury. （Hg） oxidation in flue gas, and satisfactory results are obtained.

Effect of Acupuncture on Free Radicals in Rats with Early Experimental Spinal Cord Injury

Effect of acupuncture on free radicals after spinal cord injury was observed in rats with experimental spinal cord injury (SCI). Results indicated that within 24 hours after SCI malondialdehyde (MDA) increased progressively, 2 hours after SCI it reached the peak; and the superoxide dismutase (SOD) activity decreased significantly at the same hours, the decrease being the most marked 2-6 hours after SCI. The MDA content in the acupuncture group was significantly lower (P

Standardization of English Navigation Terminology in Railway Traffic Domain

The technical progress and the globalization accelerate rapidly the development of new disciplines and sub-disciplines. Consequently, new and specific terminology is necessary. In addition, the interdisciplinarity contributes as well to the development of communication problems between non-professionals and experts of a special domain or between experts of different domains--as well at international level. Usually, technical terms are defined differently according to their domains. Therefore, a new terminological approach will avoid semantic vagueness as synonymy, antonymy, risk of confusion, hypernymy-hyponymy relations and polysemy, homonymy, etc.. For example, the terms ＂localization＂ and ＂positioning＂ are prototypes for this semantic vagueness. The objective of the iglos （＂intelligent glossary＂） terminology work of the Institute of Traffic Safety and Automation Engineering of the Technische Universigit Braunschweig is to clarify the multilingual and multidisciplinary misunderstanding between special languages of different domains by standardizing the definitions of technical terms. The focus of this paper lies on semantic problems of English navigation terminology in railway traffic domain and the clarification of the semantic vagueness between its terms with a modeling process and a linguistic method with different criteria. Finally, the result of these approaches should be a consistent navigation terminology in the railway domain.

Auto recognition of carbonate microfacies based on an improved back propagation neural network

Though traditional methods could recognize some facies, e.g. lagoon facies, backshoal facies and foreshoal facies, they couldn't recognize reef facies and shoal facies well. To solve this problem, back propagation neural network(BP-ANN) and an improved BP-ANN with better stability and suitability, optimized by a particle swarm optimizer(PSO) algorithm(PSO-BP-ANN) were proposed to solve the microfacies' auto discrimination of M formation from the R oil field in Iraq. Fourteen wells with complete core, borehole and log data were chosen as the standard wells and 120 microfacies samples were inferred from these 14 wells. Besides, the average value of gamma, neutron and density logs as well as the sum of squares of deviations of gamma were extracted as key parameters to build log facies(facies from log measurements)-microfacies transforming model. The total 120 log facies samples were divided into 12 kinds of log facies and 6 kinds of microfacies, e.g. lagoon bioclasts micrite limestone microfacies, shoal bioclasts grainstone microfacies, backshoal bioclasts packstone microfacies, foreshoal bioclasts micrite limestone microfacies, shallow continental micrite limestone microfacies and reef limestone microfacies. Furthermore, 68 samples of these 120 log facies samples were chosen as training samples and another 52 samples were gotten as testing samples to test the predicting ability of the discrimination template. Compared with conventional methods, like Bayes stepwise discrimination, both the BP-ANN and PSO-BP-ANN can integrate more log details with a correct rate higher than 85%. Furthermore, PSO-BP-ANN has more simple structure, smaller amount of weight and threshold and less iteration time.

The Potentially Dangerous Asteroid （99942） Apophis

This paper computed the newest impact solutions of the potentially dangerous asteroid （99942） Apophis based on 4,138 optical observations from March 15.10789 UTC （Universal Time Coordinated）, 2004 to February 28.089569 UTC, 2014 and 20 radar observations from January 27, 2005 through March 15, 2013, as of June 20, 2014. Using the freely available the OrbFit software Package, this paper followed its orbit forward in the searching for close approaches with the Earth and possible impacts up to year 2116. With the different A2 non-gravitational parameter in the motion of the asteroid （99942） Apophis, this paper computed possible impact solutions using the JPL DE405 （Jet Propulsion Laboratory Development Ephemeris） and 25 additional massive perturbed asteroids. Additionally, this paper used weighing and selection methods adopted in the OrbFit software as prepared by the NEODyS （Near Earth Objects--Dynamical Side） Team. Moreover, this paper used method of computing the orbit of Apophis taking into account star catalog debiasing and an error model with assumed astrometric errors RMS （root mean square）, deduced from the observational material of the given observatories. JPL＇s Sentry and NEODyS＇s CLOMMON2, two automatic monitoring systems routinely scanning for possible impacts in the next hundred years. Only for several dangerous asteroids presented results are computed with the non-gravitational parameters. This paper detected possible impacts of the asteroid （99942） Apophis only with the non-gravitational parameter, A2 〉 0. It was appeared that impacts in 2068, 2087, 2105 and in 2111 were possible only when Apophis rotated in prograde direction.

The Design for Automation of Pellet-Forming Process in HL-2A Pellet Fueling System

In the ever fusion experiments in SWIP, pellet forming process was carried out through adjusting relative devices by staff member in site, which will make every pellet-forming process slight distinction and will result in pellet difference in shape, size and intensity. In the intervals of HL-2A discharges, staff member have to go site to accomplish the pellet-forming process, this wastes human power and increase the potential danger. So it is necessary to develop a remote control system to perform the pellet-forming process. The control system needs have the features of real-time, reliability and be easy to operate and maintain.

Simulation of Spin-3/2 Blume-Capel Model on a Cellular Automaton with Heating and Cooling Algorithm

The spin-3/2 B1ume-Capel model is studied using the heating and cooling algorithms improved from the Creutz cellular automaton （CCA）. The calculations are done on various sizes of the simple cubic lattice in the 0 ≤ D/J ≤ 5 parameter region. The phase diagram of the model and temperature variation of the thermodynamic quantities are obtained. We confirm the existence of a critical end point within the heating calculations. However, in contrast to the heating calculations, we do not obtain the first-order line at low temperature with cooling algorithm calculations. The results are compared with those of other theories.

Enhancing pose accuracy of space robot by improved differential evolution

Due to the intense vibration durirLg launching and rigorous orbital temperature environment, the kinematic parameters of space robot may be largely deviated from their nominal parameters. The disparity will cause the real pose （including position and orientation） of the end effector not to match the desired one, and further hinder the space robot from performing the scheduled mission. To improve pose accuracy of space robot, a new self-calibration method using the distance measurement provided by a laser-ranger fixed on the end-effector is proposed. A distance-measurement model of the space robot is built according to the distance from the starting point of the laser beam to the intersection point at the declining plane. Based on the model, the cost function about the pose error is derived. The kinematic calibration is transferred to a non-linear system optimization problem, which is solved by the improved differential evolution （DE） algoritlun. A six-degree of freedom （6-DOF） robot is used as a practical simulation example, and the simulation results show： 1） A significant improvement of pose accuracy of space robot can be obtained by distance measurement only; 2） Search efficiency is increased by improved DE; 3） More calibration configurations may make calibration results better.

Battle damage assessment based on an improved Kullback-Leibler divergence sparse autoencoder

The nodes number of the hidden layer in a deep learning network is quite difficult to determine with traditional methods. To solve this problem, an improved Kullback-Leibler divergence sparse autoencoder （KL-SAE） is proposed in this paper, which can be applied to battle damage assessment （BDA）. This method can select automatically the hidden layer feature which contributes most to data reconstruction, and abandon the hidden layer feature which contributes least. Therefore, the structure of the network can be modified. In addition, the method can select automatically hidden layer feature without loss of the network prediction accuracy and increase the computation speed. Experiments on University ofCalifomia-Irvine （UCI） data sets and BDA for battle damage data demonstrate that the method outperforms other reference data-driven methods. The following results can be found from this paper. First, the improved KL-SAE regression network can guarantee the prediction accuracy and increase the speed of training networks and prediction. Second, the proposed network can select automatically hidden layer effective feature and modify the structure of the network by optimizing the nodes number of the hidden layer.

Constraints on a scalar-tensor theory with an intermediate-range force by binary pulsars

Searching for an intermediate-range force has been considerable interests in gravity experiments. In this paper, aiming at a scalartensor theory with an intermediate-range force, we have derived the metric and equations of motion （EOMs） in the first post- Newtonian （1PN） approximation for general matter without specific equation of state and N point masses firstly. Subsequently, the secular periastron precession ω of binary pulsars in harmonic coordinates is given. After that, ω of four binary pulsars data （PSR B1913＋16, PSR B1534＋12, PSR J0737-3039 and PSR B2127＋11C） have been used to constrain the intermediate-range force, namely, the parameters G and λ. α and λ respectively represent the strength of the intermediate-range force coupling and its length scale. The limits from four binary pulsars data are respectively A = （4.95 ±0.02）× 10^8 m and a = （2.30±0.01）× 10^8 if β = 1, where fl is a parameter like standard parametrized post-Newtonian parameter βPPN. When three degrees of freedom （α, λ and β = β - 1 ） in lσ confidence level are considered, it yields α = （4.21 ±0.01）× 10^4, λ= （4.51 ±0.01）× 10^7 m and β = （-3.30 ±0.01）× 10^-3. Through our research on the scalar-tensor theory with the intermediate-range force, it shows that the parameter α is directly related to the parameter γ （α = （1 - γ）/（1 ＋ γ））. Thus, this presents the constraints on 1 - γ by binary pulsars which is about 10^-4 for three degrees of freedom.

Regular Global Attractors of Type Ⅲ Thermoelastic Extensible Beams

For β∈ R,the authors consider the evolution system in the unknown variables u and ααttu+αxxxxu+αxxtα-(β+αxu L22)αxxu=f,αttα-αxxα-αxxtα-αxxtu=0 describing the dynamics of type III thermoelastic extensible beams,where the dissipation is entirely contributed by the second equation ruling the evolution of the thermal displacement α.Under natural boundary conditions,the existence of the global attractor of optimal regularity for the related dynamical system acting on the phase space of weak energy solutions is established.