scholarly journals Numerical simulation of the condensation process in high voltage switchgear based on the temperature and humidity distribution

2021 ◽  
Vol 2087 (1) ◽  
pp. 012082
Author(s):  
Peng Wang ◽  
Jingwen Sun ◽  
Pipei Zhang ◽  
Jiangwei Wang ◽  
Zhonghua Zhao
Keyword(s):  
Relative Humidity ◽  
Circuit Breaker ◽  
Calculation Model ◽  
Condensation Process ◽  
Field Coupling ◽  
Temperature And Humidity ◽  
Safety And Reliability ◽  
Operating Current ◽  
Calculation Results ◽  
Current Flows

Abstract The condensation on solid materials surface inside switchgear is an important reason threatening its safety and reliability. The formation of condensation is closely related to the temperature and humidity distribution inside the switchgear. A 3-D simplified finite element calculation model for the switchgear is established, including the bus bar, the wall bushing, the circuit breaker, the cables and other key components. Based on the electromagnetic-temperature-humidity multi-physical field coupling method, the temperature distribution inside the switchgear are calculated when the operating current flows through the bus-bar. Furthermore, the humidity diffusion process is also calculated when the relative humidity of external environment was 0.8, and the relative humidity inside the switchgear is obtained. The calculation results show that the surface humidity of the contact box of the circuit breaker is the highest whereas the temperature is the lowest, which is the location where the condensation is easy to occur.

Establishing and Checking the Temperature and Humidity Coupled Model about Asphalt Pavement Structure

2013 ◽  
Vol 423-426 ◽  
pp. 1126-1131
Author(s):  
Bo Wang
Keyword(s):  
Asphalt Pavement ◽  
Coupled Model ◽  
High Accuracy ◽  
Calculation Model ◽  
Predictive Analysis ◽  
Coupled Equations ◽  
Temperature And Humidity ◽  
Key Factor ◽  
Calculation Results ◽  
Pavement Structure

Temperature and humidity of the pavement affected the performance of the pavement structure as the key factor. In this paper, we used the classic migration theory of temperature and humidity, and considered the actual characteristics of the asphalt pavement structure，established a temperature and humidity coupled equations for the asphalt pavement and got the calculation model by discretization，determined the boundary conditions and calculation parameters。Compared the calculation results with the actual results, we found that the model has high accuracy，it was able to meet the requirement of the predictive analysis about internal temperature and humidity of asphalt pavement in the work of researching and designing.

Multi-lamellar organization of fully deuterated lipid extracts of yeast membranes

2014 ◽  
Vol 70 (12) ◽  
pp. 3167-3176 ◽  
Author(s):  
Yuri Gerelli ◽  
Alexis de Ghellinck ◽  
Juliette Jouhet ◽  
Valérie Laux ◽  
Michael Haertlein ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Neutron Diffraction ◽  
Structural Complexity ◽  
Structural Features ◽  
Metabolic Effects ◽  
Growth Media ◽  
Small Momentum Transfer ◽  
Lipid Species ◽  
Two Samples ◽  
Temperature And Humidity

Neutron scattering studies on mimetic biomembranes are currently limited by the low availability of deuterated unsaturated lipid species. In the present work, results from the first neutron diffraction experiments on fully deuterated lipid extracts from the yeastPichia pastorisare presented. The structural features of these fully deuterated lipid stacks are compared with those of their hydrogenous analogues and with other similar synthetic systems. The influence of temperature and humidity on the samples has been investigated by means of small momentum-transfer neutron diffraction. All of the lipid extracts investigated self-assemble into multi-lamellar stacks having different structural periodicities; the stacking distances are affected by temperature and humidity without altering the basic underlying arrangement. At high relative humidity the deuterated and hydrogenous samples are similar in their multi-lamellar arrangement, being characterized by two main periodicities of ∼75 and ∼110 Å reflecting the presence of a large number of polar phospholipid molecules. Larger differences are found at lower relative humidity, where hydrogenous lipids are characterized by a larger single lamellar structure than that observed in the deuterated samples. In both cases the heterogeneity in composition is reflected in a wide structural complexity. The different behaviour upon dehydration can be related to compositional differences in the molecular composition of the two samples, which is attributed to metabolic effects related to the use of perdeuterated growth media.

Experimental Study on Hygroscopicity of Rapeseed (Brassica Napus)

2012 ◽  
Vol 479-481 ◽  
pp. 2275-2278
Author(s):  
Ming Jin Yang ◽  
Wu Ming Xu ◽  
Tian Tang ◽  
Ling Yang ◽  
Feng Liu
Keyword(s):  
Experimental Study ◽  
Brassica Napus ◽  
Relative Humidity ◽  
Moisture Absorption ◽  
Early Period ◽  
Critical Relative Humidity ◽  
Temperature And Humidity ◽  
Higher Temperature

The hygroscopicity property of the rapeseed at different temperature and humidity was experimental studied in this paper. Tested results show that: the moisture absorption rates increase with the increase of relative humidity at the early period of absorption, and higher temperature leads to earlier reach of moisture equilibrium; the critical relative humidity(CRH) increases with the increase of temperature; the optional relative humidity for safety storage of rapeseed should be controlled less than 60%.

scholarly journals Numerical Differential Protection of Power Transformer using Innovative Algorithm

2019 ◽  
Vol 8 (5S3) ◽  
pp. 438-446
Keyword(s):  
Power Transformer ◽  
Algorithm Design ◽  
Point Of View ◽  
Inrush Current ◽  
Current Transformers ◽  
Simulink Model ◽  
Internal Fault ◽  
Safety And Reliability ◽  
Operating Current ◽  
Primary Current

This paper presents a new innovative algorithm for Numerical Differential Relay design of transformer. Fault information is critical for operating and maintaining power networks. This algorithm provides accurate performance for transformer by which is independent of system conditions such as: External fault, Inrush current, CT saturation. Locating transformer faults quickly and accurately is very important for economy, safety and reliability point of view. Both fault-detection and protection indices are derived by using Numerical Differential Relay algorithm design of transformer. The embedded based differential and operating current measurement device is called numerical differential relay is among the most important development in the field of instantaneous fault operation. Numerical relay provides measurement of differential current and operating current at power transformer above 5MVA in substation. Simulation studies are carried out using MATLAB Software show that the proposed scheme provides a high accuracy and fast relay response in internal fault conditions. Current transformers form an important part of protective systems. Ideal Current Transformers (CTs) are expected to reflect the primary current faithfully on the secondary side. Under conditions the CT saturates, and hence it cannot reproduce the primary current faithfully. This paper deals with simulation methods for determining CT performance under different factor. A Simulink model has been developed to observe CT response under steady state w.r.t Burden, Turns ratio, Asymmetrical current, Hysteresis conditions. Thus, it is now possible to evaluate the CT performance under these factors

scholarly journals The Effect of Temperature and Humidity May Reduce the Growth Rate of the Coronavirus Disease 2019 Epidemic

2020 ◽  
Author(s):  
Lei Qin ◽  
Qiang Sun ◽  
Jiani Shao ◽  
Yang Chen ◽  
Xiaomei Zhang ◽  
...  
Keyword(s):  
Growth Rate ◽  
Relative Humidity ◽  
Effect Of Temperature ◽  
Average Temperature ◽  
Temperature And Humidity ◽  
Scatter Plots ◽  
Low Humidity ◽  
Average Relative Humidity ◽  
Effects Of Temperature ◽  
The Relationship

Abstract Background: The effects of temperature and humidity on the epidemic growth of coronavirus disease 2019 (COVID-19)remains unclear.Methods: Daily scatter plots between the epidemic growth rate (GR) and average temperature (AT) or average relative humidity (ARH) were presented with curve fitting through the “loess” method. The heterogeneity across days and provinces were calculated to assess the necessity of using a longitudinal model. Fixed effect models with polynomial terms were developed to quantify the relationship between variations in the GR and AT or ARH.Results: An increased AT dramatically reduced the GR when the AT was lower than −5°C, the GR was moderately reduced when the AT ranged from −5°C to 15°C, and the GR increased when the AT exceeded 15°C. An increasedARH increased theGR when the ARH was lower than 72% and reduced theGR when the ARH exceeded 72%.Conclusions: High temperatures and low humidity may reduce the GR of the COVID-19 epidemic. The temperature and humidity curves were not linearly associated with the COVID-19 GR.

scholarly journals A new temperature- and humidity-dependent surface site density approach for deposition ice nucleation

2015 ◽  
Vol 15 (7) ◽  
pp. 3703-3717 ◽  
Author(s):  
I. Steinke ◽  
C. Hoose ◽  
O. Möhler ◽  
P. Connolly ◽  
T. Leisner
Keyword(s):  
Contact Angle ◽  
Relative Humidity ◽  
Active Surface ◽  
Ice Nucleation ◽  
Nucleation Theory ◽  
Classical Nucleation Theory ◽  
Aerosol Size Distribution ◽  
Surface Site ◽  
Linear Behavior ◽  
Temperature And Humidity

Abstract. Deposition nucleation experiments with Arizona Test Dust (ATD) as a surrogate for mineral dusts were conducted at the AIDA cloud chamber at temperatures between 220 and 250 K. The influence of the aerosol size distribution and the cooling rate on the ice nucleation efficiencies was investigated. Ice nucleation active surface site (INAS) densities were calculated to quantify the ice nucleation efficiency as a function of temperature, humidity and the aerosol surface area concentration. Additionally, a contact angle parameterization according to classical nucleation theory was fitted to the experimental data in order to relate the ice nucleation efficiencies to contact angle distributions. From this study it can be concluded that the INAS density formulation is a very useful tool to describe the temperature- and humidity-dependent ice nucleation efficiency of ATD particles. Deposition nucleation on ATD particles can be described by a temperature- and relative-humidity-dependent INAS density function ns(T, Sice) with ns(xtherm) = 1.88 ×105 · exp(0.2659 · xtherm) [m−2] , (1) where the temperature- and saturation-dependent function xtherm is defined as xtherm = −(T−273.2)+(Sice−1) ×100, (2) with the saturation ratio with respect to ice Sice >1 and within a temperature range between 226 and 250 K. For lower temperatures, xtherm deviates from a linear behavior with temperature and relative humidity over ice. Also, two different approaches for describing the time dependence of deposition nucleation initiated by ATD particles are proposed. Box model estimates suggest that the time-dependent contribution is only relevant for small cooling rates and low number fractions of ice-active particles.

Research of Calculation Models for Exhaust Enthalpy of Steam Turbine

2012 ◽  
Vol 550-553 ◽  
pp. 3160-3163
Author(s):  
Yong Guang Ma ◽  
Ning Ran ◽  
Bing Zheng
Keyword(s):  
Energy Balance ◽  
Steam Turbine ◽  
Open System ◽  
Performance Monitoring ◽  
Thermal Power ◽  
Energy Balance Equation ◽  
Calculation Model ◽  
Power Generating Unit ◽  
Calculation Results ◽  
Unit Performance

For the low pressure (LP) cylinder of a steam turbine, computation of the exhaust enthalpy is an important part in thermal power generating unit performance monitoring. A new online model for calculating the exhaust enthalpy was proposed aiming at the limitation of existing online calculation model for calculating the enthalpy of steam turbine LP cylinder exhaust steam. This model treats LP cylinder, condenser and corresponding heater as an open system, according to the energy balance equation of this open system, figuring out its exhaust enthalpy. Calculation results of typical steam turbine show that: in a large load change range, the results are close to thermal experimental value, the accuracy is similar to energy balance method.

scholarly journals Trends in continental temperature and humidity directly linked to ocean warming

2018 ◽  
Vol 115 (19) ◽  
pp. 4863-4868 ◽  
Author(s):  
Michael P. Byrne ◽  
Paul A. O’Gorman
Keyword(s):  
Relative Humidity ◽  
Land Surface ◽  
Moisture Transport ◽  
Climate Change Impacts ◽  
Atmospheric Dynamics ◽  
Specific Humidity ◽  
Climate Projections ◽  
Moist Static Energy ◽  
Temperature And Humidity ◽  
Static Energy

In recent decades, the land surface has warmed substantially more than the ocean surface, and relative humidity has fallen over land. Amplified warming and declining relative humidity over land are also dominant features of future climate projections, with implications for climate-change impacts. An emerging body of research has shown how constraints from atmospheric dynamics and moisture budgets are important for projected future land–ocean contrasts, but these ideas have not been used to investigate temperature and humidity records over recent decades. Here we show how both the temperature and humidity changes observed over land between 1979 and 2016 are linked to warming over neighboring oceans. A simple analytical theory, based on atmospheric dynamics and moisture transport, predicts equal changes in moist static energy over land and ocean and equal fractional changes in specific humidity over land and ocean. The theory is shown to be consistent with the observed trends in land temperature and humidity given the warming over ocean. Amplified land warming is needed for the increase in moist static energy over drier land to match that over ocean, and land relative humidity decreases because land specific humidity is linked via moisture transport to the weaker warming over ocean. However, there is considerable variability about the best-fit trend in land relative humidity that requires further investigation and which may be related to factors such as changes in atmospheric circulations and land-surface properties.

Lastverteilung in Planetenrollengewindetrieben/Description of the load distribution in planetary roller screws

2020 ◽  
Vol 110 (05) ◽  
pp. 322-327
Author(s):  
Christian Brecher ◽  
Thomas Frenken ◽  
Gabriel Axelrad ◽  
Stephan Neus
Keyword(s):  
Load Distribution ◽  
Load Capacity ◽  
Calculation Model ◽  
Axial Stiffness ◽  
Contact Points ◽  
Calculation Results ◽  
Roller Screw ◽  
The Individual ◽  
Individual Contact ◽  
High Load Capacity

Planetenrollengewindetriebe finden aufgrund ihrer hohen Tragfähigkeit Anwendung in Bereichen, in denen Kugelgewindetriebe an ihre Lastgrenzen stoßen. Um ein Berechnungsmodell für Planentenrollengewindetriebe zu entwickeln, wurden Berechnungsmethoden zur Beschreibung der Lastverteilung innerhalb des Planetenrollengewindetriebs entwickelt. Mit diesen lassen sich die in den einzelnen Kontaktpunkten wirkenden Kräfte sowie die Verlagerungen des Gewindetriebs bestimmen. Die Berechnungsergebnisse werden unter anderem für die Berechnung der statischen axialen Steifigkeit und der Ermüdungslebensdauer benötigt.   Due to their high load capacity, planetary roller screws are used in areas where ball screws reach their load limits. To develop a calculation model for planetary roller screws, calculation methods to describe the load distribution within the planetary roller screw were developed in this step. With these methods, the forces acting in the individual contact points as well as the displacements of the screw drive can be determined. The calculation results are required, among other things, for the calculation of static axial stiffness and fatigue life.

Memoirs: The Early Embryonic Development of Rhodnius Prolixus (Hemiptera, Heteroptera)

1935 ◽  
Vol s2-78 (309) ◽  
pp. 71-90
Author(s):  
HELEN MELLANBY
Keyword(s):  
Relative Humidity ◽  
Embryonic Development ◽  
Early Development ◽  
Constant Temperature ◽  
Germ Cells ◽  
Rhodnius Prolixus ◽  
Posterior Pole ◽  
Early Embryonic Development ◽  
Temperature And Humidity ◽  
Cent Relative Humidity

1. Eggs of Rhodnius prolixus were incubated at constant temperature and humidity (21° C. and 90 per cent, relative humidity). Eighty-five per cent, was the lowest record of the controls hatched successfully under these conditions. 2. The processes of maturation and fertilization were not studied. 3. Cleavage begins 12-13 hours after incubation. At 25 hours there are 32 nuclei. Yolk-cells are derived from cleavage nuclei, and they multiply by mitosis up to 50 hours. Blastoderm formation is complete after 55-60 hours of incubation. 4. The ventral embryonic rudiment is similar to that of many other insects. As soon as it is formed, germ-cells are budded off at the posterior pole of the egg. 5. The first stage in blastokinesis is fully described. 6. The formation of the mesoderm is by invagination and overgrowth. 7. The endoderm arises from two proliferating areas situated anteriorly and posteriorly. 8. Numerous cells are given off into the yolk during the early development of the embryo. There they disintegrate.

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