Canopy biology is the natural science that aimed at understanding of the biodiversity, biological processes, and ecological functions of forest canopies. Canopies determine the structural and ...energetic properties of forest ecosystems. Since the 1980s, canopy biology has progressed rapidly through the development of methods for accessing treetops. The rope climbing techniques used widely in canopy studies have developed from diverse procedures that allow human access to the top layers of forest vegetation. In comparison with other access hardware, e.g., cranes and gantries, rope assemblies have advantages in terms of user mobility, repeated access, and cost. The availability and safety of tree climbing techniques have improved with recent developments in mountain climbing gear and methodologies for their use. In this review, we use candidate studies to introduce the advantages, prospects and challenges of climbing techniques for tree canopy studies. Tree climbing allows excellent access to treetops in all types of forests, across all geographical locations. We expect further progress through combinations of rope climbing and other access methodologies. In the interests of safety and effectiveness, a platform should be developed for the distribution of relevant information to prospective tree climbing researchers and those who may wish to use the procedures for other activities, such as arboriculture.
The purpose of this study is to calculate the maintenance interval time (MIT) of steel structure of a large gantry crane in shipyard, and provide basis for maintenance plan. By analyzing mechanical ...model of lifting process, stress spectrum and fatigue damage are calculated. Based on fatigue reliability theory, rational MIT and maintenance strategy are suggested. Compare with the existing empirical regulation, the solution of this study is safer, cheaper and more efficient.
This paper presents a petri net model for examining effectiveness of straddle carrier direct-system operation. Dynamic of operation is addressed by formal petri net model that affiliates types of ...operation and sequences of motion for various agents in container terminal. An interchange model in the petri net is introduced to represent transloading process that controls the flow of containers between agents. In addition, simulation model was developed to examine the deployment scenarios of gantry cranes, straddle carriers and truck slots at transfer point. The results suggest terminal performance indicators such as level of productivity, waiting time and equipment’s idle time for each deployment scenarios which is beneficial as decision support systems for efficient management of terminal equipment.
Rail mounted gantry crane (RMGC) scheduling is important in reducing makespan of handling operation and improving container handling efficiency. In this paper, we present an RMGC scheduling ...optimization model, whose objective is to determine an optimization handling sequence in order to minimize RMGC idle load time in handling tasks. An ant colony optimization is proposed to obtain near optimal solutions. Computational experiments on a specific railway container terminal are conducted to illustrate the proposed model and solution algorithm. The results show that the proposed method is effective in reducing the idle load time of RMGC.
A systematic approach to real-time simulation of multibody systems requires a versatile real-time simulation environment. Such an environment includes, besides the numerical solver core of the ...mechanism dynamics, a graphics engine, and, in many cases, a physical visualization environment. The use of real-time simulation in human-in-the-loop-simulation (HIL) sets requirements for the flexible connection of the operator to the dynamics model. A visual preprocessor can be used for reducing modeling errors and for rationalizing model building by utilizing different preprogrammed components. An effective preprocessor should also offer a possibility to connect basic operator controls to the simulation model as well as enable the description of the virtual world.This paper focuses on the description of the real-time multibody simulation environment developed in Lappeenranta University of Technology. The simulation software environment consists of several function libraries in order to achieve an extendable and modular program structure. The core of the system is the dynamic solver module which is initialized using XML-based input files processed in the parser module. The graphics engine includes the visualization of the virtual world and a Graphical User Interface (GUI) for controlling the environment. A networking library is used to connect the graphics engine to the solver core via a client–server interface and allows distribution of the environment across multiple computers. In conclusion, the modeling stages and definition of the control interfaces are illustrated with the gantry crane model.
Trolley positioning and payload swinging control problem of a flexible cable gantry crane system are addressed in this paper. The system’s equations of motion that couple the crane’s cable and ...actuators dynamics are derived via extended Hamilton’s principle. The control signal is designed based on the Lyapunov direct method to derive control force and backstepping technique is employed to determine input signal for the actuator. The stability of the closed loop system is proven analytically. Numerical simulations are included to demonstrate the effectiveness and robustness of the closed-loop system.
In a modern rail–rail transshipment yard huge gantry cranes transship containers between different freight trains, so that hub-and-spoke railway systems are enabled. In this context, we consider the ...transshipment yard scheduling problem (TYSP) where trains have to be assigned to bundles, which jointly enter and leave the yard. The objective is to minimize split moves and revisits. Split moves appear whenever containers have to be exchanged between trains of different bundles, whereas revisits occur if a train has to enter the yard twice, because some container dedicated to this train was not available during its first visit. We extend the basic TYSP, so that additional real-world requirements of modern rail–rail yards, e.g., the one currently constructed in Hannover-Lehrte, are considered. We provide complexity proofs for different problem settings and present several heuristic procedures as well as one exact algorithm. The paper concludes with computational results showing the efficiency of the proposed algorithms.
A kind of parametric finite element analysis system for the L type gantry crane's gate frame is developed by making use of the secondary development on the platform of ANSYS, MATLAB through VC++ ...programming. The interface technology of VC++, ANSYS, and MATLAB is employed as well as the encapsulation on APDL. To input the parameter in the VC++ and to calculate the quality of the L type gantry crane so as to obtain the network training specimens constituted with 20 sets of parameters. The BP network is used to establish the mapping relationship which provides the adaptability function for the genetic algorithm. The genetic algorithm is adopted to accomplish the quality optimization. Then the ANSYS software is employed to simulate the optimized L type gantry crane. The results of the optimization and simulation show that the overall performance of the L type gantry crane has improved dramatically.
In this paper, we introduce an integer linear program for planning the layout of container yards. We concentrate on a special layout class of container yards which we call yard layout with transfer ...lanes. For those layouts typically rubber tired gantry cranes are used for stacking operations and trucks for horizontal transports. We show that the optimization model can be formulated as a special type of a resource constrained shortest path problem for which the LP relaxation always has at least one integer optimal solution. This model is restricted to a rectangular storage yard which allows a linear formulation. For an arbitrary shaped container yard we adopt the model and develop a variable neighborhood descent (VND) heuristic for solving non-rectangular instances. Concerning the rectangular case, we show that the VND heuristic achieves optimal solutions for 38% of the realistic test instances.
This project presents investigations into the development of hybrid input-shaping and PID control schemes for active sway control of a gantry crane system. The application of positive input shaping ...involves a technique that can reduce the sway by creating a common signal that cancels its own vibration and used as a feed-forward control which is for controlling the sway angle of the pendulum, while the proportional integral derivative (PID) controller is used as a feedback control which is for controlling the crane position. The PID controller was tuned using Ziegler-Nichols method to get the best performance of the system. The hybrid input-shaping and PID control schemes guarantee a fast input tracking capability, precise payload positioning and very minimal sway motion. The modeling of gantry crane is used to simulate the system using MATLAB/SIMULINK software. The results of the response with the controllers are presented in time domains and frequency domains. The performances of control schemes are examined in terms of level of input tracking capability, sway angle reduction and time response specification.
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