Application of the FDTD for the optimization of broad-band transitions between different types of transmission lines

2002 ◽  
Vol 38 (2) ◽  
pp. 593-596 ◽  
Author(s):  
E. Reiche ◽  
F.H. Uhlmann
Keyword(s):  
Transmission Lines ◽  
Broad Band ◽  
Different Types

scholarly journals Using the CIFIST grid of CO5BOLD 3D model atmospheres to study the effects of stellar granulation on photometric colours

2018 ◽  
Vol 613 ◽  
pp. A24 ◽  
Author(s):  
A. Kučinskas ◽  
J. Klevas ◽  
H.-G. Ludwig ◽  
P. Bonifacio ◽  
M. Steffen ◽  
...  
Keyword(s):  
Main Sequence ◽  
Broad Band ◽  
Stellar Atmospheres ◽  
Spectral Energy ◽  
Energy Distributions ◽  
Different Types ◽  
Convective Motions ◽  
Effective Temperatures ◽  
Red Giant ◽  
Colour Indices

Aims. We studied the influence of convection on the spectral energy distributions (SEDs), photometric magnitudes, and colour indices of different types of stars across the H–R diagram. Methods. The 3D hydrodynamical CO5BOLD, averaged ⟨3D⟩, and 1D hydrostatic LHD model atmospheres were used to compute SEDs of stars on the main sequence (MS), main sequence turn-off (TO), subgiant branch (SGB), and red giant branch (RGB), in each case at two different effective temperatures and two metallicities, [M∕H] = 0.0 and − 2.0. Using the obtained SEDs, we calculated photometric magnitudes and colour indices in the broad-band Johnson-Cousins UBVRI and 2MASS JHKs, and the medium-band Strömgren uvby photometric systems. Results. The 3D–1D differences in photometric magnitudes and colour indices are small in both photometric systems and typically do not exceed ± 0.03 mag. Only in the case of the coolest giants located on the upper RGB are the differences in the U and u bands able reach ≈−0.2 mag at [M∕H] = 0.0 and ≈−0.1 mag at [M∕H] = −2.0. Generally, the 3D–1D differences are largest in the blue-UV part of the spectrum and decrease towards longer wavelengths. They are also sensitive to the effective temperature and are significantly smaller in hotter stars. Metallicity also plays a role and leads to slightly larger 3D–1D differences at [M∕H] = 0.0. All these patterns are caused by a complex interplay between the radiation field, opacities, and horizontal temperature fluctuations that occur due to convective motions in stellar atmospheres. Although small, the 3D–1D differences in the magnitudes and colour indices are nevertheless comparable to or larger than typical photometric uncertainties and may therefore cause non-negligible systematic differences in the estimated effective temperatures.

scholarly journals Role of different types of protective forest stands in fodder productivity of rangeland in the Western Caspian region

2021 ◽  
Vol 16 (4) ◽  
pp. 389-399
Author(s):  
Ludmila P. Rybashlykova ◽  
Svetlana N. Sivceva ◽  
Tatyana F. Mahovikova
Keyword(s):  
Field Experiments ◽  
Robinia Pseudoacacia ◽  
Broad Band ◽  
Fold Increase ◽  
Dry Weight ◽  
Caspian Region ◽  
North Caucasus ◽  
Tree Crown ◽  
Crown Cover ◽  
Different Types

Forest pastures with different tree crown cover were studied. The seasonal dynamics of the yield and nutritional value of grass and twig-leaf fodder of forest pasture was studied. The unsystematic use of pastures in arid territories has increased the process of degradation and has become one of the factors of depletion of their natural vegetation. The use of forest reclamation in the 70s and 90s on sandy lands and pastures in the Western Caspian region made it possible to create significant areas of forest pasture land with strip and massive stands of Ulmus pumila L. and Robinia pseudoacacia L. Different types of tree stands created on pastures not only improve the microclimate and form a comfortable environment for grazing animals, but also are an additional source of valuable twig feed. The aim of the research was to study forage productivity of forest pastures with different types of plantings on the sands of the Western Caspian region. The objects of the research were forest pastures with different species composition and tree crown cover. Studies on the forage productivity of forest-reclaimed pastures were conducted in 2018-2020 on the basis of the North Caucasus branch of Federal Scientific Centre of Agroecology, Complex Melioration and Protective Af-forestation of the Russian Academy of Sciences. The research was based on field experiments and laboratory analyses. According to the results of the study, forest-reclaimed pastures with unsystematic grazing had 1.52-fold increase in productivity compared to natural ones. The largest amount of twig-leaf feed was formed in broad-band Robinia stands in summer-autumn period. The total gross stock of natural pastures of the Western Caspian region did not exceed 0.30.4 t/ha of dry weight, the consumed stock was 0.20.3 t/ha. With the help of strip and massive plantings on degraded pasture lands, it is possible to increase significantly their productivity and quality with the achievement of 7 MJ of exchange energy and 0.260.29 feed units in 1 kg of elm and robinia twig-leaf feed during droughts.

Motions of Chromospheric Fine Structures

1974 ◽  
Vol 56 ◽  
pp. 97-135 ◽  
Author(s):  
Edward N. Frazier
Keyword(s):  
Line Profile ◽  
Profile Analysis ◽  
Broad Band ◽  
Empirical Models ◽  
Line Profile Analysis ◽  
The Core ◽  
Different Types ◽  
Fine Structures ◽  
Observational Techniques ◽  
Lower Chromosphere

This review concerns itself with the measurement of the effects of chromospheric motions and the diagnosis of those motions themselves over approximately the last ten years. The different types of observational techniques are described. The different size regimes of motions are reviewed and their possible effects on observable quantities are discussed. The different types of motion in the lower chromosphere are reviewed, including microturbulence, ‘layered’ motions, and observations and interpretation of asymmetries in the core of the CaII K line. The observation of motions in Hα mottles on the disk and spicules on the limb are reviewed, from the standpoint of both line profile analysis and broad-band measurements. The interpretation of these motions and attempts to construct empirical models of chromospheric fine structures are discussed.

Modal Current and Cumulative Sum Based Fault Detection Approach in Transmission Lines

2018 ◽  
Vol 19 (6) ◽  
Author(s):  
Mohammad Amin Jarrahi ◽  
Haidar Samet
Keyword(s):  
Fault Detection ◽  
Transmission Lines ◽  
Fault Analysis ◽  
Cumulative Sum ◽  
Efficiency Assessment ◽  
Fast Approach ◽  
Detection Approach ◽  
Three Phase ◽  
Different Types ◽  
Types Of Faults

AbstractIn this paper, a simple and fast approach is suggested for fault detection in transmission lines. The proposed technique utilizes a modified cumulative sum approach for a modal current to identify faults. The modal current is derived by proper linear mixing of three-phase currents. Since different types of faults may occur in transmission lines, all three-phase currents should be considered during fault analysis. By converting three-phase currents to a modal current, the processing time is reduced and less memory is needed. In this paper, a modal current is processed instead of three-phase currents. The modified cumulative sum approach presented in this paper is capable of decreasing computational burdens on the digital relay and accelerating the fault detection procedure. The proposed fault detection technique is evaluated in four different systems. Moreover, some real recorded field data were deliberated in the efficiency assessment of the proposed method. The results denote high accuracy and quickness of the proposed approach. Furthermore, the performance of the proposed methodology is compared with some other similar methods from different aspects.

Research Progress on Manual Ice Measurement Devices for Overhead Transmission Lines

2013 ◽  
Vol 765-767 ◽  
pp. 2272-2275
Author(s):  
Jia Lun Yang ◽  
Kuan Jun Zhu ◽  
Bin Liu ◽  
Jia Jun Si ◽  
Quan Yin ◽  
...  
Keyword(s):  
Transmission Lines ◽  
Wind Direction ◽  
Power Grid ◽  
Classification Criteria ◽  
Research Progress ◽  
Existing Problems ◽  
Overhead Transmission Lines ◽  
Different Types ◽  
Measurement Devices ◽  
Further Development

Sufficient icing data are very important for the design and operation of power grid in the places with potential accreted ice, meaning that it is necessary to pay due attention to the ice measurement devices. In this paper, the current ice measurement devices are classified into different types according to corresponding classification criteria with the aim of understanding the characteristics of each type of devices. Moreover, the research progress of the manual ice measurement devices are introduced in detail, including the diameter of conductors, the angle between conductor and wind direction. Finally, the existing problems are proposed for the further development of manual ice measurement devices for overhead transmission lines.

Comparison of Electrical-Environment Characteristics Between Two Different Types of EHV Transmission Lines

2003 ◽  
Vol 36 (20) ◽  
pp. 881-886
Author(s):  
Tae-In Jang ◽  
Seong-Doo Lee ◽  
Koo-Yong Shin ◽  
Dong-Il Lee
Keyword(s):  
Transmission Lines ◽  
Different Types

scholarly journals STUDY AND PERFORMANCE OF PARTIAL DISCHARGE OF MODEL FOR DIFFERENT TYPE INSULATION MATERIALS WITH CAPACITANCE VALUE

2021 ◽  
Vol 8 (12) ◽  
pp. 323-327
Author(s):  
Neetu Baghelkar ◽  
Abhishek Dubey
Keyword(s):  
High Voltage ◽  
Transmission Lines ◽  
Partial Discharge ◽  
Electrical Equipment ◽  
Partial Discharges ◽  
Electrical System ◽  
Insulating Material ◽  
Different Types ◽  
And Performance ◽  
Short Time

The properties of the insulating material must be the best to avoid failure of electrical equipment. Partial discharges act as electrical sparks that occur within insulation and the high-voltage electrical system. The different types of voltage and current pulses are produced, which last for a very short time. Partial discharge is taking place in high voltage power equipment such as cables, transmission lines and transformers, etc.

scholarly journals Electromagnetic interference in a multiconductor transmission system – MTL

2019 ◽  
Vol XXII (2) ◽  
pp. 343-351
Author(s):  
Ciocioi I.
Keyword(s):  
Transmission Lines ◽  
Electromagnetic Interference ◽  
Printed Circuit Boards ◽  
Electronic Circuit ◽  
Electromagnetic Coupling ◽  
Circuit Boards ◽  
Printed Circuit ◽  
Different Types ◽  
Correct Function ◽  
Coupling Phenomena

In electrical and electronic practice, many connection and transmission elements (cables) are used as a multi-conductor transmission lines (MTL). The electromagnetic fields existing in the environment of these multiconductor transmission lines and can generate different types of coupling phenomena, causing EMC problems by the appearance of the unwanted EMI, disturbing the correct function and altering the information. Electromagnetic coupling between the circuits/cables of a circuit (also known as crosstalk) can also occur between the signal and power paths of an assembly made on printed circuit boards, PCB (printed board circuit), so it is important that when designing such an electrical / electronic circuit, these aspects should be taken into account.

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