Research on Structural Design and Parametric Modeling of Trestle of Material Ropeway of Transmission Line

Aiming at the trestle of material ropeway of transmission line, the structural design of components was carried out with the combination of 3D design software. Parametric modeling method was adopted to carry out the modeling of components with different structural parameters. The stress status of components of trestle was analyzed, the design load of components was proposed, and the strength of the designed components was checked through finite element simulation analysis. The results show that the components can meet the requirements of structural strength. The proposed method can realize parametric modeling of solid model and effectively improve the design efficiency of material ropeway.

Floating Wind Turbine Model Test to Verify a MoorDyn Modification for Nonlinear Elastic Materials

As the Floating Offshore Wind industry matures it has become increasingly important for researchers to determine the next generation materials and processes that will allow platforms to be deployed in intermediate (50-85 m) water depths which challenge the efficiency of traditional catenary chain mooring systems and fixed-bottom jacket structures. One such technology, synthetic ropes, have in recent years come to the forefront of this effort. The challenge of designing synthetic rope moorings is the complex nonlinear tension-strain response inherent of some rope material choices. Currently, many numerical tools for modeling the dynamic behavior of FOWTs are limited to mooring materials that have a linear tension- strain response. In this paper an open source FOWT design and analysis program, OpenFAST, was modified to capture the more complex tension-strain responses of synthetic ropes. Simulations from the modified OpenFAST tool were then compared with 1:52-scale test data for a 6MW FOWT Semi- submersible platform in 55m of water subjected to representative design load cases. A strong correlation between the simulations and test data was observed.

Numerical and Experimental Predication of the Structural Cracking Within Reinforced Concrete Structure due to Conventional State of Loading

It has been well understanding that the occurrence of various crack patterns in the building during its construction life (from first time of construction up to finishing) then subjected to super imposed load or during the service life. Cracks developed due to exceeding of stresses more than the allowable strength, wherever happened on building component. This research works used the finite element method as a powerful tool to simulate the behavior of full constructed building with both concrete system and brick bearing wall. Where the adopted numerical procedure allows to the users to predict the response of building elements due to conventional state of loading. one of the most important response features was the cracking phenomenon, where the numerical model shown that its capability to predict the cracking sequence from the first time of initiating. The prediction of full response and behavior of each element and their connection, shown that the precise of factor of safety used by the designer, where the analysis prove that the design load was about 67% from the cracking load, and the ultimate load was about 260% from the design load. That will allow more sustainability and stability for long time deformation. Beside the numerical solution, there was an experimental part of study, where site investigation, it shown that all data recorded was constant values and the building was stable. Actually, with no increasing of loading, the building reach its stable state, and defect will not develop. That basically because of good design within conventional state of loading.

A Buffer Management Algorithm Based on Dynamic Marking Threshold to Restrain MicroBurst in Data Center Network

The data center has become the infrastructure of most Internet services, and its network carries different types of business flow, such as query, data backup, control information, etc. At the same time, the throughput-sensitive large flows occupy a lot of bandwidth, resulting in the small flow’s longer completion time, finally affecting the performance of the applications. Recent proposals consider only dynamically adjusting the ECN threshold or reversing the ECN packet priority. This paper combines these two improvements and presents the HDCQ method for coordinating data center queuing, separating large and small flows, and scheduling in order to ensure flow completion time. It uses the ECN mechanism to design load-adaptive marking threshold update algorithms for small flows to prevent micro-bursts from occurring. At the same time, packets marked with ECN or ACK are raised in priority, prompting these packets to be fed back to the sender as soon as possible, effectively reducing the TCP control loop delay. Extensive experimental analysis on the network simulator (NS-2) shows that the HDCQ algorithm has better performance in the face of micro-burst traffic, reducing the average flow completion time by up to 24% compared with the PIAS.

Wind tunnel test on mean wind forces and peak pressure acting on ellipsoidal nacelles of wind turbine

Mean wind forces and peak pressures acting on ellipsoidal nacelles are investigated by wind tunnel tests. The wind force coefficients of the ellipsoidal nacelles for the wind turbine design and the peak pressure coefficients for the nacelle cover design are proposed based on the experimental data. The wind force coefficients are expressed as functions of yaw angles. The proposed formulas are compared with Eurocode, Germanischer Lloyd and ASCE7-16. It is found that the mean wind force coefficients for the wind turbine nacelles are slightly underestimated in Eurocode. The equivalent maximum and minimum mean pressure coefficients are proposed for use in Design Load Case 6.1 and Design Load Case 6.2 of IEC 61400-1. The peak pressure coefficients are derived using a quasi-steady theory. The proposed equivalent maximum and minimum mean pressure coefficients are much larger than those specified in Germanischer Lloyd.

Simplified calculation of airblast variability and reliability-based design load factors for spherical air burst and hemispherical surface burst explosions

There can be significant uncertainty and variability with explosive blast loading. Standards and codes of practice are underpinned by reliability-based principles, and there is little reason not to apply these to explosive blast loading. This paper develops a simplified approach where regression equations may be used to predict the probabilistic model of airblast variability and associated reliability-based design load factors (or RBDFs) for all combinations of range, explosive mass and model errors. These models are applicable to (i) hemispherical surface bursts, and (ii) spherical free-air bursts. The benefit of this simplified approach is that the equations can be easily programed into a spreadsheet, computer code or other numerical methods. There is no need for any Monte-Carlo or other probabilistic calculations. Examples then illustrate how model error, range and explosive mass uncertainty and variability affect the variability of pressure and impulse, which in turn affect the damage assessment of residential construction.