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Given a road network G = (V,E), where V (E) denotes the set of vertices(edges) in G, a set of points of interest P and a query point q residing in G, the reverse furthest neighbors (RfnR) query in road networks fetches a set of points p ∈ P that take q as their furthest neighbor compared with all points in P ∪ {q}. This is the monochromatic RfnR (MrfnR) query. Another interesting version of RfnR query is the bichromatic reverse furthest neighbor (BrfnR) query. Given two sets of points P and Q, and a query point q ∈ Q, a BrfnR query fetches a set of points p ∈ P that take q as their furthest neighbor compared with all points in Q. This paper presents efficient algorithms for both MrfnR and BrfnR queries, which utilize landmarks and partitioning-based techniques. Experiments on real datasets confirm the efficiency and scalability of proposed algorithms.

With the rapid development of 3D CAD technology, 3D assembly process is playing an important role in the on-site assembly. A closed-loop control method and three-dimensional site visualization technology site is presented. The methodology takes into account CAD design stage, assembly process design, site assembly and site inspection. The method includes three key technologies: the verification process technology of three-dimensional assembly process, optimization and process simulation techniques of site assembly, closed-loop control technology of assembly process quality inspection. Finally, the method and technology has applied in the actual assembly, and achieved good results.

The assembly of ship blocks is achieved through welding. To get a high level of closure accuracy, finite element analysis (FEA) is always needed to predict the welding deformation. However, the fast automatic mesh generation technique during the finite element method (FEM) for the ship assembly is not mature enough yet. Due to the complex ship architecture, during FEA, the model must be built up manually in most cases. This process is complicated and the errors are easy to occur. Consequently, the efficiency of FEA during the ship assembly is highly affected. Automatic mesh generation is a key factor restricting the development of FEM, since the quality and speed of the mesh generation directly influence the accuracy of calculation and the efficiency of analysis. In the field of marine engineering and aerospace engineering, the mesh elements are required to be quadrilateral. However, the technique of the quadrilateral mesh generation is still more difficult and less mature than that of the triangular mesh generation. This work proposed a hybrid mesh generation algorithm, borrowing the advantages from both the quad-morphing algorithm and the paving algorithm as well as considering the factor of multi-constraints. An example case is also given to illustrate the result of this proposed algorithm.

Assembly processes are very complex and hard to setup in one-time for large-scale products. Much assembly information is produced in various assembly processes and such information has not integrated or considered for next assembly processes. This leads to problems of deciding manufacturing tolerance of productions quality in the final assembly process. An object-oriented assembly information model and visualization for VAFM (Virtual Assembly Fat Model), is presented in the paper. The information modeling for assembly processes considers not only geometry data, but also non-geometry information, and those information produced by assembly process evolve, mature and derived during the whole assembly process. The paper presents modeling language based on XML and distributed storage based BSON for assembly object. The visualization of VAFM is also presented.

Slopes are a typical terrain of the rugged lunar surface. Using a modified model for wheel-terrain interaction, a terramechanics model for down-slope travel of a lunar rover is established. In order to describe the soil sinkage of different wheels more accurately, soil deformation by the front wheels is taken into account and the front and rear wheel sinkages are calculated separately. Finally, a motion control strategy for rover descent is proposed based upon analysis of its descending course, and validated by simulation in a 3D lunar rover visual simulation platform.

Large-scale component assembly, such as the installation of aircraft wings and ship section etc., is usually high cost, long cycle. Virtual assembly simulation gives the possibility of direct and visual perceive of assembly before the actual assembly using digital prototype. A new virtual assembly model, called VAFM (Virtual Assembly Fat Model), is presented. It integrates not only geometry data, but non-geometry information is embedded. All information of model will evolve, mature and derived gradually, from thin to fat, during the whole assembly process. The paper gives the definition of a VAFM, its framework and the evolution rules of the fat model. Meanwhile the paper design the modeling language based XML. Finally, the visualization of VAFM is also presented..

Rover dynamics simulation is an essential component of its 3-D visualization platform. Here we present a Bekker theory-based rover soft-soil dynamics model to accurately reflect the wheel-ground interaction as the rover navigates on the lunar surface. A rover dynamics model was then established using the multi-body dynamics simulation system, Vortex, with an integrated soft-soil dynamics computing module, to carry out whole vehicle simulation, which revealed the kinetics features of rover locomotion in the complex lunar terrain.

Motor drive control is the major study field in the development of lunar rover. Based on the double-closed DC loop adjustable-speed system, a motor drive simulation module using a position recursive PID control algorithm is developed, which is integrated into the multi-body dynamics simulation system, to carry out the whole lunar rover simulation. And the cruise process of lunar rover locomotion in the complex lunar terrain is simulated in a virtual environment.

To improve the maintainability, scalability, and reusability of models in complicated Missile Weapon System simulation, the system of a hardware-in-the-loop (HIL) simulation system based on high Level Architecture (HLA) and Modelica is designed, which can satisfy the need of interoperability among federates, and the simulation model library of missile based on Modelica is developed. Simulation application of missile trajectory and scene simulation is devised and is introduced into the federation to achieve the interaction between them and other federates. New simulation application incorporated with latest simulation technology can easily be introduced into the existing simulation system if they are in accordance with the HLA standards. The scene simulation application provides developers with a visual method to assess the performance of the system, which works as a federation in the HLA-based system. The results of missile trajectory simulation and scene simulation are given. The reusability of Modelica-based missile model provides designers with great flexibility and reusability in developing new missile models.

A lot of practical problem, such as the scheduling of jobs on multiple parallel production lines and the scheduling of multiple vehicles transporting goods in logistics, can be modeled as the multiple traveling salesman problem (MTSP). Due to the combinatorial complexity of the MTSP, it is necessary to use heuristics to solve the problem, and a discrete particle swarm optimization (DPSO) algorithm is employed in this paper. Particle swarm optimization (PSO) in the continuous space has obtained great success in resolving some minimization problems. But when applying PSO for the MTSP, a difficulty rises, which is to find a suitable mapping between sequence and continuous position of particles in particle swarm optimization. For overcoming this difficulty, PSO is combined with ant colony optimization (ACO), and the mapping between sequence and continuous position of particles is established. To verify the efficiency of the DPSO algorithm, it is used to solve the MTSP and its performance is compared with the ACO and some traditional DPSO algorithms. The computational results show that the proposed DPSO algorithm is efficient.

Success of rescue process is determined by reliability and safety of rescue device. Virtual prototype technology is introduced into the dynamics simulation and optimization for the design of an operating mechanism for loading deep submergence rescue vehicle, and the 3D CAD software, multibody system dynamics analysis software were combined. Taking into account wave excitation input at sea state 5 and 8 as the extreme marine working conditions, the virtual prototyping model of the operating mechanism is built by ADAMS. The whole topology relations of the vehicle are defined. Dynamics characteristics of key parts are analyzed in various virtual environments, which is quite difficult to be realized by physical tank test. Optimization strategy is proposed and verified by increasing the number of horizontal wheels and adding gap between horizontal wheels and the track. This method offers a new way to study the innovative design of similar marine special mechanism.

Tillering is one of the most important agronomic traits of rice. In order to explore the molecular mechanism of rice tillering, a high-tillering dwarf 1-2 (htd1-2) mutant was isolated from the offspring of the indica rice (Oryza sativa L. ssp. indica) variety 9311 treated with 350Gy 60Co gamma-radiation. Genetic analysis showed that both high tillering and dwarf phenotypes of htd1-2 were controlled by a single recessive nuclear gene. By means of molecular marker technique, the HIGH-TILLERING DWARF1-2(HTD1-2) gene was mapped between two CAPS markers A6 and E2 on chromosome 4 within 116 kilobases. Within this region, there is a cloned gene HIGH-TILLERING DWARF1(HTD1), which controls rice tillering. By comparing sequences of HTD1 between htd1-2 and 9311, in combination with the results from dCAPS analysis, we believed that HTD1 is an orthologue of the gene HTD1-2. Because of different genetic backgrounds, htd1 and htd1-2 have different phenotypes although they are the allelic mutants. Furthermore, removal of axillary buds proved that dwarfism of htd1-2 mutant is partly attributed to its excessive tillers.

Within a shipyard, designers have their own design objectives and moreover apply different software on heterogeneous hardware platforms; nevertheless requested collabtive operation still remains in the comple design circumstance. The paper presents a data hub model to sovle this problem and improve effectiveness and efficiency for ship design. The model is simulation-driven and consists of two main parts, including data management and integrated simulation environment. The data management processes the simulation-based design data storage, access and transformation. The integrated simulation environment bridges the gap among the multidisciplinary domain including CAD geometry, CAE, virtual navigation, kinematics and dynamics simulation. In addition, an application is developed to evaluate the validity of data hub model for ship design.

The first late Late Cambrian basinal-facies trilobites to be described from Tasmania are from a succession exposed 8.5 km west of Birch Inlet, south-western Tasmania. Twenty-one taxa are described; the six agnostoid species include a new species of Leiagnostus, L inletensis. The polymeroids include five new species: Hedinaspis uniformis, Proceratopyge longa, Niobella birchensisSkljarella expansa and Ivshinaspis reticulata.SkljarellaIvshinaspis are described for the first time from Australia. The specimens are preserved in siltstone belonging to a basinal facies; the fauna has more in common with those of the South-East China Faunal Province than with the shallow-water carbonate-facies faunas from northern Australia. The fauna is of late Late Cambrian age (Payntonian–earliest Datsonian) on the north Australian biostratigraphic scale. The Birch Inlet fauna is correlated with those of the Siyangshan Formation of Zhejiang, the Guoziguonen Formation of Xinjiang and the Shengjiawan Formation of Hunan. There are similarities with late Late Cambrian faunas from Nevada, Kazakhstan and New Zealand. Key words: Trilobita, Late Cambrian, Tasmania, basinal facies, biostratigraphy, palaeobiogeography.

Tillering is one of the most important agronomic traits of rice. In order to explore the molecular mechanism of rice tillering, a high-tillering dwarf 1-2 (htd1-2) mutant was isolated from the offspring of the indica rice (Oryza sativa L. ssp. indica) variety 9311 treated with 350Gy 60Co gamma-radiation. Genetic analysis showed that both high tillering and dwarf phenotypes of htd1-2 were controlled by a single recessive nuclear gene. By means of molecular marker technique, the HIGH-TILLERING DWARF1-2(HTD1-2) gene was mapped between two CAPS markers A6 and E2 on chromosome 4 within 116 kilobases. Within this region, there is a cloned gene HIGH-TILLERING DWARF1(HTD1), which controls rice tillering. By comparing sequences of HTD1 between htd1-2 and 9311, in combination with the results from dCAPS analysis, we believed that HTD1 is an orthologue of the gene HTD1-2. Because of different genetic backgrounds, htd1 and htd1-2 have different phenotypes although they are the allelic mutants. Furthermore, removal of axillary buds proved that dwarfism of htd1-2 mutant is partly attributed to its excessive tillers.

Wild rice has adapted to weather and unfavorable environments under natural selection. It has been well recognized as a natural gene bank that conserves a lot of specific genes presently not available for extinct in the cultivated rice. There is an urgent need to explore these specific genes. The present paper summarized current researches in molecular mapping and cloning of useful genes from wild rice,and their potential application in breeding.

Late Middle Cambrian trilobites are described from two localities in northwestern Tasmania. Twenty-four trilobite taxa are documented. The 15 agnostoid species include Paraclavagnostus longus sp. nov. which is placed in the Utagnostinae, a new subfamily of the Clavagnostidae. The nine polymeroid species include a new member of the Rhyssometopidae, Tasmana truncata gen. et sp. nov. Three other new species of polymeroids are erected: Fuchouia tasmaniensis, Nepea delicata and Nepea hellyeri. Both faunas correlate with the Lejopyge laevigata Zone on the northern Australia biostratigraphic scale, possibly with the L. laevigata II Zone. When compared with Hunan, China, correlation is with the upper part of the Lejopyge laevigata Zone, and particularly with the lower part of the Proagnostus bulbus Zone.