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In this paper, deployment dynamics of a large-scale flexible solar array system on the ground is investigated. Firstly, the structure of the ground solar array system adopted in this paper is introduced. Then kinematic description of a single flexible body and kinematic constraint equations of two flexible bodies are both deduced. Next dynamic equation of the ground solar array system is established by the Jourdain velocity variation principle. Finally, the validity of the dynamic model is verified through comparison with the ADAMS software. Simulation results indicate that the proposed dynamic model is effective to describe the deployment dynamics of the flexible solar array system on the ground.

Purpose The purpose of this study is to investigate the deployment and control of cable-driven flexible solar arrays. Design/methodology/approach First, dynamic model of the system is established by using the Jourdain’s velocity variation principle and the single direction recursive construction method, including the dynamic equation of a single flexible body, the kinematical recursive relation of two adjacent flexible bodies and the dynamic equation of the solar array system. Then, the contribution of joint friction to the dynamic equation of the system is derived based on the virtual power principle. A three-dimensional revolute joint model is introduced and discussed in detail. Finally, a proportion-differentiation (PD) controller is designed to control the drift of the system caused by the deployment. Findings Simulation results show that the proposed model is effective to describe the deployment of flexible solar arrays, joint friction may affect the dynamic behavior of the system and the PD controller can effectively eliminate the spacecraft drift. Practical implications This model is useful to indicate the dynamics behavior of the solar array system with friction. Originality/value The relationship between ideal constraint force and Lagrange multipliers is derived. The contribution of joint friction to the dynamic equation of the system is derived based on the virtual power principle. A PD controller is designed to control the drift of the system caused by the deployment of solar arrays.

In this paper, we construct $2n-1$ locally indistinguishable orthogonal product states in $\mathbb{C}^n\otimes\mathbb{C}^{4}~(n>4)$ and $\mathbb{C}^n\otimes\mathbb{C}^{5}~(n\geq 5)$ respectively. Moreover, a set of locally indistinguishable orthogonal product states with $2(n+2l)-8$ elements in $\mathbb{C}^n\otimes\mathbb{C}^{2l}~(n\geq 2l>4)$ and a class of locally indistinguishable orthogonal product states with $2(n+2k+1)-7$ elements in $\mathbb{C}^n\otimes\mathbb{C}^{2k+1}~(n\geq 2k+1>5)$ are also constructed respectively. These classes of quantum states are then shown to be distinguishable by local operation and classical communication (LOCC) using a suitable $\mathbb{C}^2\otimes\mathbb{C}^2$ maximally entangled state respectively., 10 pages, 3 figures

Variable geometry truss manipulator (VGTM) has potential to work in the future space applications, of which a dynamic model is important to dynamic analysis and control of the system. In this paper, an approach is presented to model the dynamic equations of a VGTM by independent variables, which consists of two double-octahedral truss units and a 3-revolute-prismatic-spherical (3-RPS) parallel manipulator. In this approach, the kinematic recursive relations of two adjacent bodies and geometric constrains are used to deduce the kinematic equations of the VGTM, and Jourdain’s velocity variation principle is adopted to establish the dynamic equations of the system. The validity of the proposed dynamic model is verified by comparison of numerical simulations with the software ADAMS. Besides, an active controller for trajectory tracking of the system is designed by the computed torque method. The effectiveness of the controller is numerically proved.

In this paper, deployment dynamics and control of large-scale flexible solar array system with deployable mast are investigated. The adopted solar array system is introduced firstly, including system configuration, deployable mast and solar arrays with several mechanisms. Then dynamic equation of the solar array system is established by the Jourdain velocity variation principle and a method for dynamics with topology changes is introduced. In addition, a PD controller with disturbance estimation is designed to eliminate the drift of spacecraft mainbody. Finally the validity of the dynamic model is verified through a comparison with ADAMS software and the deployment process and dynamic behavior of the system are studied in detail. Simulation results indicate that the proposed model is effective to describe the deployment dynamics of the large-scale flexible solar arrays and the proposed controller is practical to eliminate the drift of spacecraft mainbody.

It is well known that the traditional modeling theories adopt the Cartesian coordinates to establish the dynamic equation of solar array system. The order of this equation is often very high, which is inconvenient for controller design. The Cartesian coordinates are difficult to be measured in practice. In this paper, the joint coordinates are used as generalized variables to establish the dynamic equation of the solar array system. The single direction recursive construction method and the Jourdain’s velocity variation principle are used in modeling the system. The order of the established equation is lower, and the joint coordinates are easily measured in practice. Besides the dynamics modeling, joint friction and control design are extensively studied in this paper too. A three-dimensional revolute joint model is introduced, and the contribution of joint friction to the dynamic equation of the system is deduced. A fuzzy PD controller is designed to eliminate the drift of spacecraft caused by the deployment of solar array. In the end of this paper, numerical simulations are carried out to analyze the deployment dynamics and control effect of the solar array system with friction.

It is well known that friction is an inevitable phenomenon existing in almost all mechanical systems including robotic systems. Friction can harm dynamic characteristics of mechanical systems as well as the accuracy of manual control. In this paper, we have comprehensively investigated the dynamic process of a flexible space robot with joint friction. Dynamic equation of the system is established based on the Jourdain's velocity variation principle and the single direction recursive construction method. The Coulomb friction model and LuGre friction model are adopted to describe the joint friction. The calculation method for joint friction is discussed in detail. Moreover, an active controller is designed by the computed torque control method for trajectory tracking control. Simulation results indicate that the proposed model is effective in describing the dynamics response of the system. Joint friction can cause oscillation of the joint response and vibration of the flexible link, as well as affecting the precision of position control of the system. From the results we present, it can also be inferred that the Coulomb friction model is limited in describing the nonlinear features of friction.

It is well known that friction is an inevitable phenomenon existing in almost all mechanical systems including robotic systems. It can affect dynamic characteristics of mechanical systems and even harm accuracy of manual control. In this paper, we have conducted comprehensive study in detail on dynamics and control of a space robot with joint friction. Dynamic equation of the system is established based on Jourdain׳s velocity variation principle and the single direction recursive construction method. The Coulomb friction model, the Stribeck friction model and the LuGre friction model are adopted to describe the joint friction. Meanwhile, the calculation method for joint friction is discussed in detail, and the relationship between ideal constraint force and Lagrange multipliers is derived. Moreover, an active controller is designed by the nonlinear decoupling method for the trajectory tracking for the system. The validity of the proposed dynamic model is verified by comparison of numerical simulation results and results obtained from the software ADAMS. And then we carry out a series of simulations in order to observe the influence of joint friction on operating a space robot with different friction models. We also study the interaction between the low-speed motion and joint friction in the process of trajectory tracking.

For solar array system, traditional modeling theories usually adopt the Cartesian coordinates to establish the dynamic equation of the system. The order of this equation is often too high and inconvenient to design control laws and the Cartesian coordinates are difficult to be measured in practice. This paper presents a modeling method for solar array system. In this method, joint coordinates of the solar panels, yoke and the spacecraft main-body are defined as the generalized variables. In this way, the dynamic equation derived here possesses lower order than those derived by other methods used before, which facilitates further control design. Moreover, the joint coordinates can be easily measured in practice. On the other hand, joint friction is an important issue to be considered. Joint friction could affect the stability and control precision of the system. Most existing studies on joint friction of solar array system are over-simplified into plane problems, and as a result, inaccuracy of friction force calculation output was incurred. In this paper, a three-dimensional revolute joint model is introduced, the calculation of joint friction is discussed in detail, and the relationship between ideal constraint force and Lagrange multipliers is derived. In addition, the control design of the solar array system is discussed and the fuzzy adaptive PD control method is used for controller design. At the end of this paper, the validity of the above studies is verified by the comparisons of numerical simulations with the ADAMS software.

It is well known that space robots play a significant role in the human space activities. Capturing a free floating object in space is one of important missions assigned to space robots and it has increasingly attracted researchers’ attention recently. In this paper, the dynamics and control of capturing a floating rigid body using a space robot are investigated. The dynamic model of the system is established by the single direction recursive construction method and the Jourdain’s velocity variation principle. The contact force between space robots and targets has been set up based on the Hertz contact theory. Then the influence on the whole system incurred by this contact force has been thoroughly analyzed through simulations of both central and eccentric impact. Our simulation result verified the impact on the whole system caused by the contact force, and it also indicated the extreme complexity of the dynamic response caused by impact during the capture process. The space robot base attitude has been controlled using the controller based on the nonlinear decoupling method. Our simulation results showed adequate effectiveness.

In this article, the Pro/Engineer virtual prototyping technology is used for three dimensional entity modeling, assembly, and simulation analysis of 1000KN·m large backstop in four design plans to confirm the integrity and assembling of backstop. By using the ANSYS/LS-DYNA software, it makes numerical simulation analysis of the backstop in non-return process, and through the analysis comparison to the simulation result, it obtains the optimization design plan of the 1000KN·m backstop.

Inter simple sequence repeat (ISSR) analysis was applied to samples of foxtail millet and its wild ancestor and other close relatives of the genus Setaria in order to detect domestication-related geographical structure and phylogenetic relationship of those species. Eighty-one accessions of nine Setaria species that originated from different regions were used in this study. Fourteen out of the 27 ISSR primers screened amplified successfully and a total of 156 markers were scored for all the accessions, with a high level of polymorphism being detected. The dendrogram based on UPGMA cluster analysis showed clear geographic structure among foxtail millet and its wild ancestor green foxtail, which implies that northern China is the domestication center for both the Chinese and European foxtail millet landraces used in this study. This result did not support the hypothesis that China and Europe are independent domestication centers for foxtail millet proposed by several previous studies based on morphological and isozyme data. The dendrogram also clearly classified the Setaria sample used into two groups, a viridis and a pumila groups. The viridis group was composed of S. viridis, S. italica, S. faberii, S. verticillata, S. leucopila, and S. queenslandica, and the pumila group consisted of S. parviflora and S. pumila, which is consistent with the recently proposed hypothesis of multiple origin of Setaria species. The phylogenetic relationships among different species are discussed.

In this study, analyses are conducted on the information features of a construction site, a cornfield and subsidence seeper land in a coal mining area with a synthetic aperture radar (SAR) image of medium resolution. Based on features of land cover of the coal mining area, on texture feature extraction and a selection method of a gray-level co-occurrence matrix (GLCM) of the SAR image, we propose in this study that the optimum window size for computing the GLCM is an appropriate sized window that can effectively distinguish different types of land cover. Next, a band combination was carried out over the text feature images and the band-filtered SAR image to secure a new multi-band image. After the transformation of the new image with principal component analysis, a classification is conducted selectively on three principal component bands with the most information. Finally, through training and experimenting with the samples, a better three-layered BP neural network was established to classify the SAR image. The results show that, assisted by texture information, the neural network classification improved the accuracy of SAR image classification by 14.6%, compared with a classification by maximum likelihood estimation without texture information.

Horizontal gene transfer is the gene exchange between different organisms or different organelles, which occurs frequently in prokaryotes. Many newly identified horizontal transfer events in eukaryotes indicates that it is a common phenomenon in all organisms. This paper describes the concept of horizontal gene transfer, the standard for judging a horizontal gene transfer events, the character, the mode, the way of horizontal gene transfer, and its impact on gene and genome evolution. The analyses of phylogenetic tree, base composition, selection pressure, intron sequence comparison, inserted special sequence, and biased nucleotide substitution are the most common methods used in previous researches. Evidence accumulated demonstrated that transposable sequences are most likely undergoing horizontal transferring. Transformation, conjugation, and transduction are the main forms of horizontal gene transfer in prokaryotes, but no clear clue was related with the mechanism of horizontal gene transfer in eukaryotes. Horizontal gene transfer plays a special role in genetic, genomic, and the biological evolution.

Horizontal gene transfer is the gene exchange between different organisms or different organelles, which occurs frequently in prokaryotes. Many newly identified horizontal transfer events in eukaryotes indicates that it is a common phenomenon in all organisms. This paper describes the concept of horizontal gene transfer, the standard for judging a horizontal gene transfer events, the character, the mode, the way of horizontal gene transfer, and its impact on gene and genome evolution. The analyses of phylogenetic tree, base composition, selection pressure, intron sequence comparison, inserted special sequence, and biased nucleotide substitution are the most common methods used in previous researches. Evidence accumulated demonstrated that transposable sequences are most likely undergoing horizontal transferring. Transformation, conjugation, and transduction are the main forms of horizontal gene transfer in prokaryotes, but no clear clue was related with the mechanism of horizontal gene transfer in eukaryotes. Horizontal gene transfer plays a special role in genetic, genomic, and the biological evolution.

(-)-gamma-Lactam is one of the key starting materials for the synthesis (-)-cabovir and (-)-abacavir, which serve as two powerful antiviral agents. The production of gamma-lactam using enzymatic resolution of racemic gamma-lactam was attempted in the paper. 20 out of 69 strains capable of producing lactamase were screened from soil samples collected in several districts throughout Beijing; particularly N-actylphenylalanine was used as sole carbon source in the screening method. It was found by chiral HPLC analysis that strain L29-9 was able to enantioselectively hydrolyze the (+)-isomer in the racemic lactam, thus giving the desired (-)-gamma-lactam with high enantiomeric excess (70%). Ferment conditions of strain L29-9, including carbon source, nitrogen source, pH, and culturing time, were studied and the optimum conditions were as follows: citric acid 2 g/L, yeast extract 5 g/L, pH 7.0, culturing for 40h. Biotransformation using whole cells of the strain was inducted at 30 degrees C for 12h, giving (-)-gamma-lactam as enantiopure product with yield up to 40% and 99.5% e.e.

It was found that in the chemical ionization (isobutane) mass spectra of some asymmetric secondary alcohols and α-amino acids, when a pair of enantiomers (such as R- and S-2-phenyIbutyric anhydride, R- and S-mandelic acid, R- and S-2-methylbutanoic acid or R- and S-α-phenyl ethyl amine) were used as reaction reagents, the relative abundances of characteristic ions formed by the stereoselective reaction between sample and reagent of the same configuration were much higher than those ions formed by the sample and a reagent of a different configuration. The absolute configuration of the sample molecule may be predicted by examination of mass spectra of the sample measured with R- and S-reagent respectively. This approach proved to be a convenient way for determination of the absolute configurations of organic molecules on a micromole level by mass Spectrometry.

Fast atom bombardment (FAB) followed by collisional activation (CA) mass spectrometry was used for structural analysis of steroidal oligoglycosides, containing two to four sugar units. In the molecular ion region of the FAB mass spectra of these underivatized natural products, intense protonated molecular ions were observed. The collisional activation spectra of these mass selected ions yield more sequence information than FAB mass spectra and are not contaminated with interfering peaks originating from impurities or matrix.