Conformation Optimization Based on Impulse Grounding Resistance for Ground Electrode of Power Lines

2014 ◽  
Vol 986-987 ◽  
pp. 1930-1933
Author(s):  
Guang Zu Ge ◽  
Bo Tang ◽  
Zi Hang Qu ◽  
Yu Li ◽  
Bin Chen
Keyword(s):  
Safety Margin ◽  
Effective Area ◽  
Power Lines ◽  
Calculation Formula ◽  
Grounding Resistance ◽  
Practical Engineering ◽  
Coefficient Method

Reducing tower ground’s impulse grounding resistance can prevent the power lines from lightning effectively. The concept of impulse grounding resistance is described. Calculation formula of the impulse grounding resistance for ground electrode in different Conformations is derived with impulse coefficient method. The conformation of the ground electrode is improved according to the theory of impulse grounding resistance is decreased when the effective area of the electrode is reduced, using ETAP for simulation of the improved ground electrode. The results show that the impulse grounding resistance of the improved ground electrode can be reduced to 41.1% of the original, and safety margin is larger in practical engineering.

scholarly journals Reliable Design: Basic Approach

2018 ◽  
Vol 198 ◽  
pp. 02006 ◽  
Author(s):  
Jiří Stodola ◽  
Jan Furch
Keyword(s):  
Safety Margin ◽  
Stochastic Approach ◽  
Distribution Law ◽  
Reliability Design ◽  
Fault Resistance ◽  
Practical Engineering ◽  
Operating Stress ◽  
Reliable Design ◽  
Ultimate Condition ◽  
Production Probability

The knowledge and experience learnt from product designing have resulted in development of their reliability theory. The classical concept of safe – life is based on product over dimensioned design that considers safety factor or safety margin for measure. However, practical engineering has found this concept in a manner inconvenient as design fault-resistance to determine the ultimate condition and operating stress are random values. A way out is in the concept of stochastic approach to reliability design resulting from the defect-production probability distribution law. That concept allows product designing with predetermined reliability, such as in the example contained in this paper.

scholarly journals Reliability Modeling and Assessment of Component with Multiple Weak Sites under Complex Loading

2014 ◽  
Vol 2014 ◽  
pp. 1-9
Author(s):  
Wenxue Qian ◽  
Xiaowei Yin ◽  
Liyang Xie
Keyword(s):  
Static Loading ◽  
Safety Margin ◽  
Complex Loading ◽  
The Other ◽  
Reliability Model ◽  
Reliability Modeling ◽  
Component Reliability ◽  
Reliability Design ◽  
Practical Engineering ◽  
Weak Site

A component with multiple weak sites is widely used in practical engineering and the existence of multiple weak sites can significantly decrease the component reliability. On the other hand, only a few components bear static loading and most components bear dynamic loading. In this paper, a reliability model of isomorphic component with multiple weak sites is built based on an order statistics model and the influences of strength decentrality and loading decentrality on isomorphic component with multiple weak sites are discussed. Furthermore the influence of loading times is studied in detail. The results show that unlike a component with only one weak site, not only does the failure of a component with multiple weak sites have a relationship with the safety margin, but there also exist relationships with the number of weak sites, the loading roughness, and loading times. The work in this paper is of some guiding significance in reliability design and assessment of a component with multiple weak sites under complex loading.

Research for Non-Destructive Detection of Vertical Prestressed Tensile Force in Box Girder

2013 ◽  
Vol 838-841 ◽  
pp. 2052-2057
Author(s):  
Bian Wu ◽  
Wei Cui ◽  
Jia Long Sun ◽  
Yi Yu Long
Keyword(s):  
Prestressed Concrete ◽  
Tensile Force ◽  
Engineering Application ◽  
Beam Model ◽  
Box Girder ◽  
Elastic Supports ◽  
Practical Engineering ◽  
Prestressed Reinforcement ◽  
Non Destructive ◽  
Coefficient Method

Fine rolled twisted bars as the vertical prestressed reinforcement has been widely used in the prestressed concrete box girder, but it is hard to effectively control the loss of prestressed force in the practical engineering. Too much loss of prestressed force will lead to diagonal cracks in box girder webs. According to the dynamic theory, take the exposed segment of fine rolled twisted bars as the beam model, take the anchorage segment as a rigid arm and two elastic supports, this article establishes the plane elastic support model of vertical prestressed fine rolled twisted bar. The nonlinear relationship between vertical prestressed tensile force P and the plane stiffness of elastic supports K is established by an indoor experiment, and at the same time the anchoring section stiffness coefficient method is used to verify the effectiveness of this method and conduct an engineering application. This paper provides a theoretical basis for the test of vertical prestressed tensile force in box girder.

Research of Loop Pre-Stress Tension Test for Cable-Stayed Bridge Pylon Based on Full-Scale Sectional Model

2013 ◽  
Vol 275-277 ◽  
pp. 1141-1146
Author(s):  
Qi Wei Liu ◽  
Shu Wen Huang ◽  
Yong Hong ◽  
Wen Lin Luo
Keyword(s):  
Model Experiment ◽  
Reference Value ◽  
Tension Test ◽  
Full Scale ◽  
Calculation Formula ◽  
Cable Stayed Bridge ◽  
Practical Engineering ◽  
Deviation Factor ◽  
Sectional Model ◽  
Prestressing Tendon

Based on full-scale sectional model experiment for cable pylon anchorage zone of cable-stayed bridge, this research tested the friction factor and deviation factor of the duct. The reason that tension elongation of loop prestressing tendon exceeded the provision of ±6% in specification was analyzed systematically. A correctional calculation formula was proposed, with quantitative analysis for influencing factors of tension elongation. The formula shows good applicability in practical engineering and has reference value for similar loop prestressing tendon.

Research on the Formula of the Height of Bearing Push-Extend under-Reamed of the Push-Extend Multi-under-Reamed Pile

2013 ◽  
Vol 694-697 ◽  
pp. 883-886
Author(s):  
Yong Mei Qian ◽  
Xiao Long Liu ◽  
Ruo Zhu Wang
Keyword(s):  
Theoretical Analysis ◽  
Pile Foundation ◽  
Theoretical Basis ◽  
Shear Resistance ◽  
Calculation Formula ◽  
Foundation Design ◽  
Concrete Pile ◽  
Practical Engineering

As there is no definite calculation formula of the height of bearing push-extend reamed of the Push-extend Multi-under-reamed Concrete Pile at present, in the paper, according to the theoretical analysis and the experimental achievements on the failure principle of the soil of the Push-extend Multi-under-reamed Concrete Pile, it is made that using the theory of shear resistance to carry on the analysis, deduce the check formula of the height of bearing push-extend reamed of the Push-extend Multi-under-reamed Concrete Pile, and it is put forward that the reliable theoretical basis of the Push-extend Multi-under-reamed Concrete Pour Pile foundation design for practical engineering.

scholarly journals Research on application of single index membership function based on power coefficient method

2021 ◽  
Vol 2083 (3) ◽  
pp. 032070
Author(s):  
Na Liu
Keyword(s):  
Regional Distribution ◽  
Power Coefficient ◽  
Efficiency Coefficient ◽  
Distribution Characteristics ◽  
Membership Functions ◽  
Distribution Problem ◽  
Single Index ◽  
Practical Engineering ◽  
Research On Application ◽  
Coefficient Method

Abstract The power coefficient method can determine the satisfactory value and the unallowable value of the index, quantify multiple targets, and then determine the power coefficient value of each target. Combining the distribution characteristics of the four types of membership functions, this paper innovatively proposes to solve the regional distribution problem of single-index membership functions by means of an improved efficiency coefficient method, and combined with empirical research, the application of this mathematical method in practical engineering.

The limits of human performance

2008 ◽  
Vol 44 ◽  
pp. 11-26 ◽  
Author(s):  
Ralph Beneke ◽  
Dieter Böning
Keyword(s):  
Human Performance ◽  
Safety Margin ◽  
Afferent Input ◽  
Metabolic Energy ◽  
Human Organism ◽  
Mechanical Resistance ◽  
As Doping ◽  
Gene And Protein Expression ◽  
Underlying Mechanisms ◽  
Biochemical Research

Human performance, defined by mechanical resistance and distance per time, includes human, task and environmental factors, all interrelated. It requires metabolic energy provided by anaerobic and aerobic metabolic energy sources. These sources have specific limitations in the capacity and rate to provide re-phosphorylation energy, which determines individual ratios of aerobic and anaerobic metabolic power and their sustainability. In healthy athletes, limits to provide and utilize metabolic energy are multifactorial, carefully matched and include a safety margin imposed in order to protect the integrity of the human organism under maximal effort. Perception of afferent input associated with effort leads to conscious or unconscious decisions to modulate or terminate performance; however, the underlying mechanisms of cerebral control are not fully understood. The idea to move borders of performance with the help of biochemicals is two millennia old. Biochemical findings resulted in highly effective substances widely used to increase performance in daily life, during preparation for sport events and during competition, but many of them must be considered as doping and therefore illegal. Supplements and food have ergogenic potential; however, numerous concepts are controversially discussed with respect to legality and particularly evidence in terms of usefulness and risks. The effect of evidence-based nutritional strategies on adaptations in terms of gene and protein expression that occur in skeletal muscle during and after exercise training sessions is widely unknown. Biochemical research is essential for better understanding of the basic mechanisms causing fatigue and the regulation of the dynamic adaptation to physical and mental training.

Cognitive Processing of Film Cuts Among 4- to 8-Year-Old Children

2012 ◽  
Vol 17 (4) ◽  
pp. 257-265 ◽  
Author(s):  
Carmen Munk ◽  
Günter Daniel Rey ◽  
Anna Katharina Diergarten ◽  
Gerhild Nieding ◽  
Wolfgang Schneider ◽  
...  
Keyword(s):  
Eye Movements ◽  
Cognitive Processing ◽  
Media Literacy ◽  
Age Groups ◽  
Reaction Times ◽  
Time Span ◽  
Short Film ◽  
Calculation Formula ◽  
Eye Tracker ◽  
Chronological Sequence

An eye tracker experiment investigated 4-, 6-, and 8-year old children’s cognitive processing of film cuts. Nine short film sequences with or without editing errors were presented to 79 children. Eye movements up to 400 ms after the targeted film cuts were measured and analyzed using a new calculation formula based on Manhattan Metrics. No age effects were found for jump cuts (i.e., small movement discontinuities in a film). However, disturbances resulting from reversed-angle shots (i.e., a switch of the left-right position of actors in successive shots) led to increased reaction times between 6- and 8-year old children, whereas children of all age groups had difficulties coping with narrative discontinuity (i.e., the canonical chronological sequence of film actions is disrupted). Furthermore, 4-year old children showed a greater number of overall eye movements than 6- and 8-year old children. This indicates that some viewing skills are developed between 4 and 6 years of age. The results of the study provide evidence of a crucial time span of knowledge acquisition for television-based media literacy between 4 and 8 years.

Hydrostatic Fiber Optic Liquid Level Sensor with position sensitive detector

Metrologiya ◽  
2020 ◽  
pp. 38-51
Author(s):  
V. N. Astapov ◽  
I. N. Kozlova
Keyword(s):  
Fiber Optic ◽  
Effective Area ◽  
Raw Material ◽  
Position Sensitive Detector ◽  
Fiber Optic Sensor ◽  
Liquid Level ◽  
Problem Solution ◽  
Sensitive Detector ◽  
Position Sensitive ◽  
Triangulation Sensor

This article presents the rationale and methodology for developing an intrinsically safe device, namely, a hydrostatic fiber optic sensor with a position-sensitive detector for monitoring the level of oil products in large-capacity tanks at oil depots and during pumping in a raw material warehouses. This device suitable for continuous monitoring of the liquid level, based on the measurement of a hydrostatic column of liquid with automatic offset of changes in the density of the liquid. Offset is carried out by means of a displacer (a fully submerged float), inside which a housing with a position-sensitive detector (PSD) is integrated. Theoretical validation of the bellows suspension usage for a displacer is given. During filling a container with a liquid whose level is measured, liquid bellows, the movement of which is recorded by an optical triangulation sensor using the reflected infrared ray incident on the bottom of the bellows. The principle of the triangulation sensor operation is based on the geometric properties of the triangles. The pulses of infrared radiation come through a fiber optic cable. In order to measure the movement of the surface (the bottom of the bellows) by measuring the movement of the reflected beam, a position-sensitive detector is used, which is located in a remote controller. In this device for the intrinsic safety problem solution, optical inputs of a fiber optic flat cable are located in the active zone of the sensor, which is connected to the optical inputs of a position-sensitive detector, operated on the principles of photoelectric effect. The light spot moving along the sensitive zone and converted by the detector into a one-dimensional signal proportional to the distance to the object. hydrostatically applies pressure over the entire effective area of the measuring

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