New design of large fully-steerable radio telescope reflector based on homogenized mesh structure

2021 ◽  
Vol 21 (10) ◽  
pp. 244
Author(s):  
Li-De Yan ◽  
Fei Zheng ◽  
Xi Rui
Keyword(s):  
Radio Telescope ◽  
Simulation Analysis ◽  
Structural Complexity ◽  
Radio Telescopes ◽  
Mesh Structure ◽  
Factors Affecting ◽  
Performance Requirements ◽  
Reflector System ◽  
Structure Scheme ◽  
Heavy Structure

Abstract The self-weight of a large fully-steerable radio telescope is one of the important factors affecting its performance. In the existing reflector system scheme, the problem of surface accuracy caused by its large and heavy structure has seriously restricted the application and implementation of large radio telescopes. Therefore, a new mesh structure scheme for a large fully-steerable radio telescope reflector is proposed in this paper. This scheme is based on a homogenized mesh back-up structure in the form of a quasi-geodesic grid and regular quasi-tri-prism or tetrahedron, which can significantly reduce the structural complexity and self-weight of the reflector under the condition that the reflector can meet the desired performance requirements. Finally, the feasibility and rationality of the scheme are evaluated by numerical simulation analysis, which has significant advantages and provides a new design for the reflector of a large fully-steerable radio telescope.

scholarly journals Pulsar science with the CHIME telescope

2017 ◽  
Vol 13 (S337) ◽  
pp. 179-182 ◽  
Author(s):  
Cherry Ng
Keyword(s):  
Northern Hemisphere ◽  
Radio Telescope ◽  
Field Of View ◽  
Radio Bursts ◽  
Radio Telescopes ◽  
Acoustic Oscillations ◽  
Daily Monitoring ◽  
Intensity Mapping ◽  
Pulsar Timing ◽  
Pulsar Timing Array

AbstractThe CHIME telescope (the Canadian Hydrogen Intensity Mapping Experiment) recently built in Penticton, Canada, is currently being commissioned. Originally designed as a cosmology experiment, it was soon recognized that CHIME has the potential to simultaneously serve as an incredibly useful radio telescope for pulsar science. CHIME operates across a wide bandwidth of 400–800 MHz and will have a collecting area and sensitivity comparable to that of the 100-m class radio telescopes. CHIME has a huge field of view of ~250 square degrees. It will be capable of observing 10 pulsars simultaneously, 24-hours per day, every day, while still accomplishing its missions to study Baryon Acoustic Oscillations and Fast Radio Bursts. It will carry out daily monitoring of roughly half of all pulsars in the northern hemisphere, including all NANOGrav pulsars employed in the Pulsar Timing Array project. It will cycle through all pulsars in the northern hemisphere with a range of cadence of no more than 10 days.

Design analysis of a standard injection screw for plasticising polycarbonate resins

2016 ◽  
Vol 36 (5) ◽  
pp. 537-548 ◽  
Author(s):  
Ming-Shyan Huang
Keyword(s):  
Simulation Analysis ◽  
Melt Temperature ◽  
Factors Affecting ◽  
Control Factors ◽  
Screw Length ◽  
Plastic Injection Moulding ◽  
Screw Diameter ◽  
Grey Relational ◽  
Injection Screw ◽  
Simulation Programme

Abstract The industrial use of plastic injection moulding machines is widespread. However, few studies have examined the injection screw, which is one of the key components of moulding machines. Studies have demonstrated that a properly designed injection screw improves both the moulding quality and the production rate. Factors that affect the plasticisation properties of conventional standard reciprocating screws include the screw geometry, the screw operation settings, and the processed resins. An ideal standard reciprocating screw exhibits a high plasticising capacity and excellent melt temperature homogeneity; however, these properties typically conflict. Through simulation analysis, this study investigated the optimal design of a standard reciprocating injection screw used for plasticising polycarbonate resins. First, the Taguchi method was integrated with a commercial simulation programme to identify the key control factors affecting the plasticising rate of a screw and the temperature uniformity of the melt. Simulation results revealed that the screw diameter, rotation speed, metering channel depth, ratio of the screw length to the screw diameter, and compression ratio substantially influence performance. Consequently, grey relational analysis was adopted to optimise the design of an injection screw that ensures sufficient quality according to the plasticisation rate and the homogeneity of molten plastic.

Experiment and Simulation Analysis of the Pressure Carrying Capacity of X80 Pipe with Metal Loss Defect on the Girth Weld

2021 ◽  
Vol 1035 ◽  
pp. 813-818
Author(s):  
Zheng Long Li ◽  
Lin Chen ◽  
Zhi Hong Li ◽  
Guo Shuai Yan ◽  
Wei Li
Keyword(s):  
Sensitivity Analysis ◽  
Carrying Capacity ◽  
Simulation Analysis ◽  
Water Pressure ◽  
Metal Loss ◽  
Factors Affecting ◽  
Element Simulation ◽  
Simulation Based ◽  
Blasting Test ◽  
Water Pressure Blasting

In order to study the pressure carrying capacity of X80 pipe with metal loss defect on the girth weld the water-pressure blasting test of the pipe with metal loss defect was analyzed by experiment and finite element simulation. Based on this, the sensitivity analysis of the factors affecting the pressure carrying of the pipeline, such as the circular size, the axial size, and the depth of the metal loss defect, was carried out. The research results show that the circular size of the metal loss defect on the girth weld had little impact to the pressure carrying capacity of the pipe while it reduced with the increasing of the axial size and the depth of the metal loss defect.

scholarly journals Space-VLBI observations of OH masers

2002 ◽  
Vol 206 ◽  
pp. 105-111 ◽  
Author(s):  
Vyacheslav I. Slysh ◽  
Maxim A. Voronkov ◽  
Irina E. Val'tts ◽  
Victor Migenes ◽  
K.M. Shibata ◽  
...  
Keyword(s):  
Brightness Temperature ◽  
Lower Limit ◽  
Radio Telescope ◽  
Angular Resolution ◽  
Main Line ◽  
Radio Telescopes ◽  
Space Radio Telescope ◽  
Vlbi Observations ◽  
Interstellar Scattering

We report on the first space-VLBI observations of the OH masers in two main-line OH transitions at 1665 and 1667 MHz. The observations involved the space radio telescope on board the Japanese satellite HALCA and an array of ground radio telescopes. The maps of the maser region and images of individual maser spots were produced with an angular resolution of 1 mas, which is several times higher than the angular resolution available on the ground. The maser spots were only partly resolved and a lower limit to the brightness temperature 6 × 1012 K was obtained. The masers seem to be located in the direction of low interstellar scattering.

Simulation Analysis of the Pressure Carrying Capacity of X80 Pipe with Plain Dents

2019 ◽  
Vol 944 ◽  
pp. 835-840
Author(s):  
Peng Song ◽  
Zheng Long Li ◽  
Yu Ran Fan ◽  
Lei Guo ◽  
Xi Xi Zhang ◽  
...  
Keyword(s):  
Sensitivity Analysis ◽  
Finite Element ◽  
Internal Pressure ◽  
Carrying Capacity ◽  
Formation Process ◽  
Simulation Analysis ◽  
Hydraulic Test ◽  
Factors Affecting ◽  
Element Simulation ◽  
Simulation Based

In order to study the pressure carrying capacity of X80 pipe with plain dents, the formation process and the hydraulic test were analyzed by finite element simulation. Based on this, the sensitivity analysis of the factors affecting the pressure carrying capacity of the pipeline, such as the internal pressure, the confinement state and the material performance, is carried out. Research results show that springback amount of the pipeline decreases due to the initial internal pressure, and constraint state has little effect on the pressure carrying capacity while increases with the increasing of the material tensile properties. When the depth of the dent is less than 6% pipe diameter or the strain of the dent is less than 6%, the dent has little impact to the pressure carrying capacity of the pipe.

scholarly journals A Study on the Multi-Agent Based Comprehensive Benefits Simulation Analysis and Synergistic Optimization Strategy of Distributed Energy in China

Energies ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 3260 ◽  
Author(s):  
Xiaohua Song ◽  
Mengdi Shu ◽  
Yimeng Wei ◽  
Jinpeng Liu
Keyword(s):  
Energy Demand ◽  
Simulation Analysis ◽  
Evaluation Index System ◽  
Chinese Government ◽  
Optimization Strategy ◽  
Distributed Energy ◽  
Continuous Growth ◽  
Factors Affecting ◽  
Comprehensive Benefit ◽  
Grid Side

With the economic and social development of China, the continuous growth of the energy demand is the trend for now and the future. As a consequence, distributed energy, especially distributed electricity power generation, has received more and more attention. Thus, the scale and utilization level of distributed energy has been continuously improved. However, due to the limitations of current technologies, resources, policies and other issues, the comprehensive benefits and synergy levels of energy sources need to be greatly enhanced. Based on the system dynamics model, this paper examines the factors affecting the comprehensive benefits of distributed energy in China, screens the key subjects, and using the literature review method, combined with the existing literature analysis, constructs a comprehensive benefit evaluation index system and evaluates the comprehensive benefits through case analysis. This paper also sorts out the distributed energy-related Chinese government policies from 2001 to 2017, and considers the scale of distributed energy development, then divides it into two development stages. The synergetic entropy is used to analyze the synergetic development degree of the two-stage distributed energy entities. The synergistic optimization strategy is proposed from the Chinese government side, power supply side, power grid side and user side, which provides theoretical methods and optimization suggestions for improving the comprehensive benefits of distributed energy and promoting sustainable development of energy.

Numerical Simulation of Internal Flow Drag Reduction with Triangular Riblet Surface

2013 ◽  
Vol 779-780 ◽  
pp. 401-405
Author(s):  
Zhi Guo Wei ◽  
Yong Li ◽  
Zhi Wu Ke ◽  
Xian Ling Li
Keyword(s):  
Numerical Simulation ◽  
Drag Reduction ◽  
Simulation Analysis ◽  
Internal Flow ◽  
Factors Affecting ◽  
Actual Application ◽  
Computational Fluid Dynamics Cfd ◽  
Wall Flow ◽  
Flow Drag ◽  
Riblet Surface

Computational fluid dynamics (CFD) numerical simulation is adopted to analyze the drag reduction ability of triangular riblet on tube internal flow. The resistance characteristic of smooth tube and tube covered with triangular riblet surface are compared, and the near wall flow structure over smooth surface and riblet surface are investigated. Based on the simulation analysis, the drag reduction mechanism of riblet surface is studied. Results show that the characteristic dimension of riblet section, i.e., height (h) and width (w) are main factors affecting drag reduction, suggesting that the riblet structure can be optimized according to the actual application condition.

Numerical Investigation on Fatigue Problem of Cable Net Structure of Five-Hundred-Meter Aperture Spherical Radio Telescope

2014 ◽  
Vol 936 ◽  
pp. 1351-1355 ◽  
Author(s):  
Peng Jiang
Keyword(s):  
Fatigue Life ◽  
Service Life ◽  
Active Control ◽  
Radio Telescope ◽  
Stress Amplitude ◽  
Stress Range ◽  
Relative Standard ◽  
Reflector Surface ◽  
Reflector System ◽  
Residual Fatigue

The reflector of Five-hundred-meter Aperture Spherical radio Telescope (FAST) is supported by cable-net structure, so that to enable its reflector surface to form a paraboloid from a sphere in real time through active control. However, such form-changing operation would lead to about 500MPa stress range for the cable-net structure. Such stress range is nearly twice as much of that defined by the relative standard. So the cable-net structure is the most critical and expendable part of FAST reflector system. So, the service life of FAST would directly depend on the residual fatigue life of its cable-net structure. The present paper would make an effort to find a more appropriate deformation strategy to decrease the stress amplitude of the cable during form-changing operation.

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