18420 research outputs found
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Inspection Program Development for Stationary Operation of Fatigue-Prone Aircraft Park
No full textThe paper describes the development of the methodology of the choice of aircraft fleet’s inspec-tion intervals. This methodology is verified, using the experimental fatigue crack growth data. Meth-odology includes in the economic parameters, such as the inspection costs. Using this method it is possible to find safe- enough and the most cost- effective inspection planning programs. In addition the paper includes testing of the methodology at different design permissive fatigue failure (FF) prob-abilities and their impact on the real probability of FF and the number of inspection intervals for the model with one aircraft and with aircraft fleet
Reliability of Aircraft an Airline
No full textThe reliability of aircraft (AC) and airline (AL) operation can be ensured by the implementation of a specific inspectio
Is there Enough Space for the Shopping Malls in Latvia?
No full textThe article comprises the analysis and the vision on the development of the large-scale retail real estate in Latvia. This is an extended research version. Last year the results were presented on the Annual International scientific conference „Whither our Economies” in Vilnius. The authors focus their attention on the large-scale shopping centers that are presented by over 360 thousand sq.m of gross leasable area and planned to be a little less than doubled up to 2015. The target is to analyze the target audience and business scope, therefore the authors decide on the standardization of the shopping centers as the objects of the research, the spatial planning concept for the retail real estate within the theoretical and practical scope
Starptautiskas kartogrāfijas mācību grāmatas sagatavošanas problēmas
No full textVeidojot starptautisku mācību grāmatu, pirmkārt, būtu jāvienojas par vairākumam valstu pieņemamu variantu. Otrkārt, jāvienojas par starptautisku autoru kolektīvu, mācību līdzekļa atveidošanas formu ne tikai papīra, bet arī elektroniskā versijā. Treškārt, jāvienojas par mācību līdzekļa valodām un līdz ar to par terminoloģiju. Grāmatā jābūt kartogrāfijā pielietojamo specializēto programmatūru raksturojumam. Nenoliedzami, svarīgs ir starptautiska mācību līdzekļa sagatavošanas un publicēšanas finansējums. Par to būtu jāuzņemas pārraudzība Starptautiskajai Kartogrāfijas asociācijai
Analytical Assessment of Sustainable Development Concept
No full textGenerally, sustainability dimension is related to a context, timing and scale. Although the context of sustainability can be various – either general or more specific, the timing is oriented to the long-term, but the scale has a global nature. The main purpose of the paper is to assess analytically the sustainable development concept. This new approach for solving the problems and achieving the goals of sustainable development is related to efficiently applied systems approach that determines necessity to amalgamate political, economical, social and ecological systems of the state into a unified system of sustainable development. The findings of the study show the impact of the effect of ecological footprint and of international experience on possibilities to evaluate sustainable development. Sustainable development concept is open to a variety of interpretations. Comprehensive and comparative approach, exploring sustainable development concept in the light of global processes, leads to an experience of measuring and finding the specific applications of the concept, including land management field
Influence of Boiler Damages on Life Time of Tank Car
No full textRaksts ir veltīts vagona-cisternas katla bojājumu ietekmes uz vagona-cisternas kalpošanas termiņu pētījumam
Scour near Engineering Structures under Stratified Bed Conditions
No full textA hydraulic structures in flow (intakes, abutments, spurs, guide banks) damage because of scour at foundations at stratified river bed conditions is an important problem. Influence of the stratification of the river bed on scour development at foundations is confirmed by some authors, but literature analysis shows that there are no methods to find values of the scour depth. The aim of the study is to find the influence of the river bed stratification on the depth of scour at hydraulic structures. Scour at abutments, elliptical and strait guide banks at uniform and stratified bed conditions under steady and unsteady clear-water conditions was studied. Tests were made with uniform grains size sands with one or two layers of different mean size diameters. Different sequence of the stratification was used- fine sand of different thickness on the top of the coarse sand, or coarse sand of different thickness on the top of fine sand. Tests were made with the different hydraulic conditions, contracting rate, Froude numbers of approaching flow and local densimetric Froude numbers. Tests were conducted 7 hours and computer modelling was used to calculate equilibrium stage of scour. New method for computing depth of scour hole at elliptical guide banks at stratified bed conditions is presented. This method allows calculate scour depth in layers with different grain sizes of the river bed materials, thickness and their sequence combination. Method is confirmed by tests results. It was found that depth of scour depends on the grain size, sequence and thickness of the river bed layers. The most critical conditions for structures are when fine sand layer is under the coarse sand layer. When the coarse layer is scoured, depth of scour is rapidly developing in the next fine sand layer. In that case the dominant grain size for computing depth of scour at foundations at stratified bed conditions is mean diameter of the second layer or next, where the scour stops. To calculate depth of scour near hydraulic structures in flow using grain size d50 on the top of the river bed and not to take into account stratification of the river bed, can lead to wrong results and considerable damages and losses
Floods Impact on Scour at Guide Banks in Plain Rivers
No full textThe differential
equation of equilibrium for the bed sediment movement for
clear-water conditions is used and a new mathematical model
for computing the scour development with time at the
elliptical guide banks is elaborated. We suggest to solve
initial equations numerically using software packages
available for the solution of the Cauchy problem. In this case
the time step can be chosen in order to guarantee desired
accuracy of the solution. In particular, using adaptive
integration formulas, one can select the step size
automatically. There are at least two advantages of the
proposed approach in comparison with the our method used
before (Gjunsburgs et al.,2006): the next time step can be
selected by analyzing the properties of the solution at the
previous time steps, that is, one can choose a smaller time
steps, where the solution changes quickly and larger time
steps where the solution does not change too much, and there
is no need to approximate scour depth s h by a constant at e
Multiple Floods Impact on Scour at Engineering Structures
No full textThe scour development in time during multiple floods and equilibrium stage and the assessment of flood
damage risk for bridge abutments have been investigated. A method for computing scour development in time at
hydraulic structures during multiple floods was used. The test confirmation of the method allows us to perform
computer modelling of scour processes and estimate the influence of floods with different probability, duration,
frequency, and sequence on the depth of scour. It was found that the scour parameters increase with decreasing
probability and with increasing duration and frequency of the floods. The sequence of floods can increase or reduce the
scour development in time, depending on their probability. The successive floods of the same probability considerably
increase the value of scour depth. The results obtained are presented