Failures of avionic generators and contactors operated under harsh ambient conditions

2012 ◽  
Vol 30 (1) ◽  
pp. 153-176
Author(s):  
Andrzej Gębura ◽  
Tomasz Radoń
Keyword(s):  
Climatic Conditions ◽  
Ambient Conditions ◽  
Power Devices ◽  
Lower Intensity ◽  
Fine Grained ◽  
Rotary Machines ◽  
Paint Coatings ◽  
Corrosion Pits ◽  
Fine Grained Sand ◽  
Final Consequence

The paper outlines failures of selected avionic electric power devices operated onboard of combat helicopters in Iraq and Afghanistan. While the authors were examining the electric power system of aircrafts in order to prolong their operation life they paid attention to numerous symptoms of wear demonstrated by some units of aircrafts. It was peculiar that such symptoms have never appeared during similar examinations of aircrafts operated in our country. By all accounts, the weird wear of components results from high intensity of flights and specific features of operating missions, but harsh climatic conditions seem to be the crucial factor. The authors believe that many of spotted failures experienced by electric power equipment may also happen to aircrafts operated in Poland but obviously, due to much lower intensity of operation and mild impact of environmental factors, such failures shall occur much later. The authors focused their attention on two groups of electric devices and associated destructive factors: 1. Air-cooled electric rotary machines. Fine-grained sand sucked together with air leads to very quick abrasion of protective paint coatings inside the machines. Not frequent but intense rainfalls are the reason for appearance of corrosion pits that lead to such effects as increase of pole shoe volumes. This, in turn, results in shearing of winding insulations with breakdowns (shorts) to ground and, as a final consequence, considerable drop of power demonstrated by an electric machine. 2. Contactors and electromagnets, which are allegedly tight. However, dust penetrates anyway via microfissures and disables operation of moving parts.

Overpressure Identification Using The Eaton Method on The Gumai Formation of Geragai Graben, Jambi Sub Basin

2020 ◽  
Author(s):  
A. O. Marnila
Keyword(s):  
Pressure Data ◽  
Stratigraphic Sequence ◽  
Fine Grained ◽  
Marine Sedimentation ◽  
Plot Analysis ◽  
Significant Reversal ◽  
Porosity And Permeability ◽  
Upper Level ◽  
Type Data ◽  
Fine Grained Sand

Geragai graben is located in the South Sumatera Basin. It was formed by mega sequence tectonic process with various stratigraphic sequence from land and marine sedimentation. One of the overpressure indication zones in the Geragai graben is in the Gumai Formation, where the sedimentation is dominated by fine grained sand and shale with low porosity and permeability. The aim of the study is to localize the overpressure zone and to analyze the overpressure mechanism on the Gumai Formation. The Eaton method was used to determine pore pressure value using wireline log data, pressure data (RFT/FIT), and well report. The significant reversal of sonic and porosity log is indicating an overpressure presence. The cross-plot analysis of velocity vs density and fluid type data from well reports were used to analyze the causes of overpressure in the Gumai Formation. The overpressure in Gumai Formation of Geragai graben is divided into two zones, they are in the upper level and lower level of the Gumai Formation. Low overpressure have occurred in the Upper Gumai Formation and mild overpressure on the Lower Gumai Formation. Based on the analyzed data, it could be predicted, that the overpressure mechanism in the Upper Gumai Formation might have been caused by a hydrocarbon buoyancy, whereas in the Lower Gumai Formation, might have been caused by disequilibrium compaction as a result of massive shale sequence.

scholarly journals Shrub vegetation shores strengthening and protection in Kalachevsky district of Volgograd area

2021 ◽  
Vol 25 (3) ◽  
pp. 65-72
Author(s):  
A.S. Solomentseva ◽  
Keyword(s):  
Surface Runoff ◽  
Climatic Conditions ◽  
Forest Stands ◽  
Effective Measure ◽  
Rosa Canina ◽  
Fine Grained ◽  
Fine Grained Soil ◽  
Subsurface Runoff ◽  
Protective Forest

The critical abrasion situation manifests itself on the coastal part of the Kalachevsky district due to the increasing anthropogenic load. The most important element of the complex of measures to combat silting of reservoirs and coastal abrasion, as well as an effective measure to strengthen the banks is forest vegetation. The objectives of the research were to study the soil, forest and climatic conditions of the object under study, to develop an assortment of shrubs and features of the formation of protective forest stands, as well as criteria for selecting an adapted assortment of tree and shrub vegetation and methods of caring for the soil and plantings. During the research, the most promising types of shrubs for creating upper protective forest stands were identified: Ligustrum vilgare L., Berberis vulgaris L., Cotoneaster lucidus Schltdl., Amelanchier Medik., Ribes aureum Pursh., Rosa canina L. It was found that the useful role of forest stands is manifested in their ability to convert surface runoff into subsurface runoff, to clean surface stock water from fine-grained soil, to weaken the speed of movement and to extinguish the energy of waves, binding the soil with roots. Recommendations are given for the creation and placement of anti-abrasion plantings, depending on the steepness and height of the slope. It is stated that one of the main measures for the care of the aboveground part of the plantings is the pruning of the crown, carried out taking into account the biological characteristics of their growth and development, including the removal of dry and damaged branches, thinning of the crown, preservation of the previously given crown size, rejuvenation of the crown. It is recommended to place shrubs depending on the landscape, soil and climatic conditions and features of abrasive processes in areas of constant, periodic, episodic flooding and strong moderate and weak flooding of the coastline.

Durable Architectural and Decorative Powder-Activated Concrete Using Waste-Crushing Stone Rocks

2019 ◽  
Vol 802 ◽  
pp. 1-15
Author(s):  
Sergey Victorovich Daletsky ◽  
Yuri Mikhailovich Kolitievsky ◽  
Victor Vasilievich Nikonov ◽  
Nikolay Nikolaevich Sirotin ◽  
Vladimir Vladimirovich Yudaev
Keyword(s):  
High Strength ◽  
High Density ◽  
Term Operation ◽  
Fine Grained ◽  
Concrete Mixtures ◽  
Technical Properties ◽  
Fine Grained Sand

The article consists in the development of compositions of self-compacting powder-activated fine-grained (sand) concrete mixtures, including color ones, for the production of high-density, high-strength and durable architectural and decorative concretes, which do not lose their architectural appeal during long-term operation, on the basis of multi-tonnage waste of stone crushing of various rocks, without the use of expensive mineral reactive components and the study of their physical and technical properties.

Particle size distributions of radioactive pollution soils and its influence on consistence of the shelterbelt forest ranges

2015 ◽  
Vol 5 (2) ◽  
pp. 93-103
Author(s):  
Маркина ◽  
Zoya Markina ◽  
Вечеров ◽  
Vladislav Vecherov
Keyword(s):  
Size Distributions ◽  
Clay Loam ◽  
Particle Size Distributions ◽  
Glacial Deposits ◽  
Parent Materials ◽  
Fine Grained ◽  
Soil Fractions ◽  
South West ◽  
Dominant Soil ◽  
Fine Grained Sand

Presents characteristic of the soil texture that formed at mixture of moraine and fluvial-glacial deposits, moraine that overlaid clay loam mantle, clay loam mantle in shelterbelt forest ranges at south-west areas of the Bryansk region that contaminate radioactive fallouts in conse-quence of the Chernobyl accident. Dominant soil fractions determined in soil horizonts, its formed at different parent rock materials. There is a growing number of fine-grained sand and silt soil fractions in the moraine overlaid clay loam mantle compared to fluvio-glacial deposits in the relief of parent materials.

Late Quaternary Climatic Variations in Northwest Africa Deduced from East Atlantic Sediment cores

1976 ◽  
Vol 6 (2) ◽  
pp. 299-314 ◽  
Author(s):  
Liselotte Diester-Haass
Keyword(s):  
Late Quaternary ◽  
Sediment Cores ◽  
Climatic Conditions ◽  
Terrigenous Material ◽  
East Atlantic ◽  
Humid Climate ◽  
Fine Grained ◽  
Senegal River ◽  
Northwest Africa ◽  
High Desert

Characteristic variations in glacial and interglacial periods are shown by the CaCO3 contents, amounts and grain size of terrigenous material (>40 μm), quartz/mica ratios, and desert quartz numbers in East Atlantic sediment cores, collected during Meteor cruise 25 off Sahara and Senegal, 15–27°N. The following results were obtained. During Holocene an arid climate with eolian supply from the continent prevailed throughout the region (fine grained, slight terrigenous input; high CaCO3 values; high desert quartz numbers) except in the Senegal area. Here terrigenous muds indicate river supply and hence humid climate. During upper and lower Würn the climate was humid in the present day Sahara north of 20°N (low desert quartz numbers: input of large quantities of coarse terrigenous material; low CaCO3 values). South of 20°N the climate was arid, the Senegal river input disappeared during upper Würm, desert quartz numbers are as high as in Sahara dune samples, and wind strength was stronger than in the Holocene. Climate during middle Würm resembled Holocene climatic conditions. Climatic conditions during Eem (Riss) were probably similar to those during Holocene (Würm).

scholarly journals New luminescence-based geochronology framing the last two glacial cycles at the southern limit of European Pleistocene loess in Stalać (Serbia)

2017 ◽  
Vol 44 (1) ◽  
pp. 150-161 ◽  
Author(s):  
Janina Bösken ◽  
Nicole Klasen ◽  
Christian Zeeden ◽  
Igor Obreht ◽  
Slobodan B Marković ◽  
...  
Keyword(s):  
Soil Formation ◽  
Climatic Conditions ◽  
Interglacial Period ◽  
Southeastern Europe ◽  
Glacial Cycles ◽  
Southern Limit ◽  
Fine Grained ◽  
Infrared Stimulated Luminescence ◽  
Tephra Layers ◽  
Balkan Region

Abstract A new geochronology was established for the Stalać loess-paleosol sequence (LPS) in Serbia. The section is located in the interior of the Central Balkan region, south of the typical loess distribution, in a zone of paleoclimatic shifts between continental and Mediterranean climate regimes. The sampled sequence contains four well-developed paleosol and loess layers, a crypto tephra and one visible tephra layer. Optically stimulated luminescence measurements showed a strong dependency of preheat temperature on equivalent dose for one fine-grained quartz sample, which makes it unsuitable for dating. A firm chronology framing the last two glacial cycles was established using fine-grained polyminerals and the post-infrared infrared stimulated luminescence (pIR50IR290) protocol instead. The characteristics of dated paleosols indicate similar climatic conditions during the last interstadial and interglacial phases, which were different from the penultimate interglacial period. The tephra within the L2 loess, probably related to tephra layers also found in other sections in Southeastern Europe, was sandwich-dated. The results indicate an age between 118 ka and 141 ka. Furthermore, a weak pedogenic layer dated to between 126 ka and 148 ka gives a first numerical age to this soil formation in Southeastern Europe.

scholarly journals Fine-grained Concrete Mix Design using Statistical Methods for Ultra-thin Whitetopping Overlay Application

2020 ◽  
Vol 6 ◽  
pp. 33-41
Author(s):  
Lam Ngoc Nguyen
Keyword(s):  
Compressive Strength ◽  
Thin Layer ◽  
Statistical Methods ◽  
Layer Structure ◽  
Concrete Strength ◽  
Climatic Conditions ◽  
Road Surface ◽  
Mix Design ◽  
Maintenance Cost ◽  
Fine Grained

Whitetopping is a thin layer structure covering on an existing asphalt pavement to improve resistance to rutting and increase the durability road surface. This thin layer usually made of concrete without coarse aggregate, is used mainly to repair the old damaged asphalt road surface without altering its texture. Due to the high longevity, using this type of concrete for reinforcing and repairing roads in unfavorable climatic conditions as in Vietnam brings technical, economic, environmental effective, and suitable with the trend of sustainable development. This article shows results on mix design of high performance fine - grained concrete used for thin whitetopping overlays from materials available in Vietnam by using statistical methods. The Design Expert 11.0 software was used to evaluate the influence and relationship between the influencing variables such as the ratio Water/Binder and the Sand/Binder ratio and concrete strength through the regression equation determination by experimental planning method. After checking the compatibility, the maximum value of the compressive strength and optimum mix design were found through solving this mathematical model. The concrete with optiumum proportion has good workability, high abrasion resistance; its compressive strength develops rapidly at early age and achieves more than 100MPa at 28 days. Using this Fine-grained concrete will help increasing durability and reduce the maintenance cost in the future.

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