CRITICAL REVIEW OF PHYSICAL MODELLING OF SNOW ACCUMULATION  ON ROOFS WITH ARBITRARY GEOMETRY

A review of the most significant domestic and, due to numerical superiority, foreign works on physical modelling of snow transport and snow accumulation processes, in particular, for the purpose of determining snow loads on roofs with arbitrary geometry, is presented. The existing practice of development of recommendations on assignment of snow loads in Russian laboratories is considered and critically evaluated. Comparison of do-mesticworks with scientific articles in the advanced world scientific journals and foreign regulatory documents leads to unfavorable conclusions. Recommendations on assigning snow loads, issued by Russian laboratories on the basisof extremely outdated and poorly substantiated methodology, bear a serious risk for evaluating mechan-ical safety of modern structures, for which such recommendations are developed. Recommendations are offered to remedy this current dangerous practice. The article also gives some suggestions on forming a basis for field observations of snow loads on existing roofs.

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CRITICAL REVIEW OF MODERN NUMERICAL MODELLING OF SNOW ACCUMULATION ON ROOFS WITH ARBITRARY GEOMETRY

International Journal for Computational Civil and Structural Engineering ◽

10.22337/2587-9618-2021-17-4-40-59 ◽

2021 ◽

Vol 17 (4) ◽

pp. 40-59

Author(s):

Alexander Belostotsky ◽

Nikita Britikov ◽

Oleg Goryachevsky

Keyword(s):

Numerical Methods ◽

Numerical Modelling ◽

Mathematical Models ◽

Scale Effects ◽

Numerical Models ◽

Complex Problem ◽

Snow Accumulation ◽

Wind Tunnels ◽

Arbitrary Geometry ◽

Snow Transport

The calculation of snow loads on roofs of buildings and structures with arbitrary geometry is a complex problem, solving which requires simulating snow accumulation with acceptable engineering accuracy. Experiments in wind tunnels, although widely used in recent years, do not allow to reproduce the real full-scale effects of all snow transport subprocesses, since it is impossible to satisfy all the similarity conditions. This situation, coupled with the continuous improvement of mathematical models, numerical methods, computer technologies and related software, makes the development and future implementation of numerical modelling in real construction practice and regulatory documents inevitable. This paper reviews currently existing mathematical models and numerical methods used to calculate the forms of snow deposits. And, although the lack of significant progress in the field of modelling snow accumulation still remains one of the major problems in CFD, use of existing models, supported by field observations and experimental data, allows to reproduce reasonably accurate snow distributions. The importance of the “symbiosis” between classical experimental methods and modern numerical models is specifically emphasized in the paper, as well as the fact that only the joint use of approaches can comprehensively describe modelling of snow accumulation and snow transport and provide better solutions to a wider range of problems.

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Prediction of snowmelt derived streamflow in a wetland dominated prairie basin

Hydrology and Earth System Sciences Discussions ◽

10.5194/hessd-7-1103-2010 ◽

2010 ◽

Vol 7 (1) ◽

pp. 1103-1141 ◽

Cited By ~ 2

Author(s):

X. Fang ◽

J. W. Pomeroy ◽

C. J. Westbrook ◽

X. Guo ◽

A. G. Minke ◽

...

Keyword(s):

Soil Moisture ◽

Hydrological Model ◽

Snow Accumulation ◽

Model Parameters ◽

Field Observations ◽

Runoff Generation ◽

Stream Channels ◽

Physically Based ◽

Set Up ◽

Spot 5

Abstract. The eastern Canadian Prairies are dominated by cropland, pasture, woodland and wetland areas. The region is characterized by many poor and internal drainage systems and large amounts of surface water storage. Consequently, basins here have proven challenging to hydrological model predictions which assume good drainage to stream channels. The Cold Regions Hydrological Modelling platform (CRHM) is an assembly system that can be used to set up physically based, flexible, object oriented models. CRHM was used to create a prairie hydrological model for the externally drained Smith Creek Research Basin (~400 km2), east-central Saskatchewan. Physically based modules were sequentially linked in CRHM to simulate snow processes, frozen soils, variable contributing area and wetland storage and runoff generation. Five "representative basins" (RBs) were used and each was divided into seven hydrological response units (HRUs): fallow, stubble, grassland, river channel, open water, woodland, and wetland as derived from a supervised classification of SPOT 5 imagery. Two types of modelling approaches calibrated and uncalibrated, were set up for 2007/08 and 2008/09 simulation periods. For the calibrated modelling, only the surface depression capacity of upland area was calibrated in the 2007/08 simulation period by comparing simulated and observed hydrographs; while other model parameters and all parameters in the uncalibrated modelling were estimated from field observations of soils and vegetation cover, SPOT 5 imagery, and analysis of drainage network and wetland GIS datasets as well as topographic map based and LiDAR DEMs. All the parameters except for the initial soil properties and antecedent wetland storage were kept the same in the 2008/09 simulation period. The model performance in predicting snowpack, soil moisture and streamflow was evaluated and comparisons were made between the calibrated and uncalibrated modelling for both simulation periods. Calibrated and uncalibrated predictions of snow accumulation were very similar and compared fairly well with the distributed field observations for the 2007/08 period with slightly poorer results for the 2008/09 period. Soil moisture content at a point during the early spring was adequately simulated and very comparable between calibrated and uncalibrated results for both simulation periods. The calibrated modelling had somewhat better performance in simulating spring streamflow in both simulation periods, whereas the uncalibrated modelling was still able to capture the streamflow hydrographs with good accuracy. This suggests that prediction of prairie basins without calibration is possible if sufficient data on meteorology, basin landcover and physiography are available.

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A snow-transport model for complex terrain

Journal of Glaciology ◽

10.3189/s0022143000002021 ◽

1998 ◽

Vol 44 (148) ◽

pp. 498-516 ◽

Cited By ~ 35

Author(s):

Glen E. Liston ◽

Matthew Sturm

Keyword(s):

Snow Depth ◽

Depth Distribution ◽

Snow Water Equivalent ◽

Transport Model ◽

Vegetation Type ◽

Cold Season ◽

Snow Accumulation ◽

Surface Shear Stress ◽

Surface Shear ◽

Snow Transport

AbstractAs part of the winter environment in middle- and high-latitude regions, the interactions between wind, vegetation, topography and snowfall produce snow covers of non-uniform depth and snow water-equivalent distribution. A physically based numerical snow-transport model (SnowTran-3D) is developed and used to simulate this three-dimensional snow-depth evolution over topographically variable terrain. The mass-transport model includes processes related to vegetation snow-holding capacity, topographic modification of wind speeds, snow-cover shear strength, wind-induced surface-shear stress, snow transport resulting from saltation and suspension, snow accumulation and erosion, and sublimation of the blowing and drifting snow. The model simulates the cold-season evolution of snow-depth distribution when forced with inputs of vegetation type and topography, and atmospheric foreings of air temperature, humidity, wind speed and direction, and precipitation. Model outputs include the spatial and temporal evolution of snow depth resulting from variations in precipitation, saltation and suspension transport, and sublimation. Using 4 years of snow-depth distribution observations from the foothills north of the Brooks Range in Arctic Alaska, the model is found to simulate closely the observed snow-depth distribution patterns and the interannual variability.

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A Probabilistic Approach to the Prediction of Snow Loads

Canadian Journal of Civil Engineering ◽

10.1139/l74-003 ◽

1974 ◽

Vol 1 (1) ◽

pp. 28-49 ◽

Cited By ~ 15

Author(s):

N. Isyumov ◽

A. G. Davenport

Keyword(s):

Formation Process ◽

Extreme Values ◽

Meteorological Data ◽

Digital Simulation ◽

Probabilistic Approach ◽

Snow Accumulation ◽

Meteorological Variables ◽

Snow Load ◽

Design Values ◽

Snow Loads

The magnitudes of loads imposed by snow depend upon a number of climatological and meteorological variables and as a result exhibit marked variations geographically, due to local effects within a particular region, and with time. The snowload formation process, which depends both on the macro- and microclimates of such meteorological variables as the depth of the snowfall, the snowfall density, wind speed, air temperature etc., as well as, the size and geometry of particular roofs and the influence of their immediate environment, is discussed.A model of the snow load formation process based on a mass balance approach, which takes into account the deposition of snow by individual snowfalls and the depletion of the snow load by wind action and thermal effects, is introduced. The use of this approach requires the establishment of statistical descriptions of the various meteorological variables, as well as a knowledge of the physical process of snow accumulation and depletion for a particular roof. The statistical properties of some of the more important meteorological variables are discussed. Also presented are some model derived data of snow accumulation and depletion for particular roofs located in different terrain.It is shown that even relatively simple statistical descriptions of the relevant meteorological data and snow accumulation and depletion mechanisms can lead to realistic predictions of roof snow loads. Snow loads on a flat roof are generated by a digital simulation technique and compared with full scale observations. Annual extreme values of the simulated snow load process are presented and compared with currently specified design values. Comments are made regarding the practicability of this approach.

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Seeking and reading patterns of schorlarly articles

Brazilian Journal of Information Science ◽

10.36311/1981-1640.2009.v3n2.03.p32 ◽

2010 ◽

Vol 3 (2) ◽

Author(s):

Sadao Omote ◽

Paulo Sergio Teixeira do Prado ◽

Helen de Castro Silva Casarin

Keyword(s):

Graduate Students ◽

Doctoral Students ◽

Critical Review ◽

Information Seeking ◽

Scientific Information ◽

Fisher Exact Test ◽

Scientific Journals ◽

Exact Test ◽

Electronic Questionnaire ◽

Education Data

This article presents part of a larger study on the use of reference sources to perform bibliographical search by graduate students in Education. Data relating to the use of the scientific journals by these students are presented and discussed. Sixty Education graduate students, 28 Master degree and 32 Doctoral, answered an electronic questionnaire. The students indicated the types of articles usually read and the importance attributed to each one. For each of treated themes in the electronic questionnaire, data are initially presented and analyzed in the set of the 60 participants of the study and then compared between master and doctoral students. Were used the Chi-squared (?2) test, the Fisher exact test and the Spearman’s correlation coefficient. Research reports were more frequently pointed out but less valued in comparison to articles referring to critical review and theoretical essay. Methodological articles, appearing in fourth position according to reading frequency and importance attributed, are more valued by doctoral than master students. The students read these articles using different procedures. The possible reasons for the students valorizing the articles of critical review and theoretical essays are discussed. The present study intends to offer a contribution to understand the use of scientific information by students, describing some graduate students’ habits related to information seeking in scientific journals, and reading of the articles published.

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The Overproduction of Truth

10.1093/oso/9780198799887.001.0001 ◽

2018 ◽

Author(s):

Gianfranco Pacchioni

Keyword(s):

Critical Review ◽

Scientific Journals ◽

Huge Amount ◽

Scientific Publications ◽

The Troubles ◽

Contemporary Science ◽

The World ◽

Personal Reflections ◽

Science Production

The way science is done has changed radically in the last years. The personal reflections and experiences of a protagonist help us to understand the mechanisms of contemporary science. A system where passion, dedication and reliability, have increasingly less room, pressed by hard market laws. From vocation of a few, science has become the profession of many, possibly too many. With consequences and risks, such as the increase of frauds, plagiarism, but in particular with a huge amount of scientific publications, often of little relevance. The solution? A slow approach with more emphasis to quality than quantity, that helps us to rediscover the central role of a responsible scientist. The work is a critical review and assessment of present-day policies and behaviors in science production and publication, touching upon the tumultuous growth of scientific Journals, in parallel to the growth of self-declared scientists over the world. Along with personal reminiscences of times past, the author investigates the loopholes and hoaxes of pretended Journals and non-existing Congresses, so common nowadays in the scientific arena. The troubles with bibliometric indices are also discussed, as resulting in large part from the above distortions of science life.

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Does Poverty Research in Russia Follow the Scientific Method?

Voprosy Ekonomiki ◽

10.32609/0042-8736-2008-6-44-60 ◽

2008 ◽

pp. 44-60

Author(s):

M. Lokshin

Keyword(s):

Critical Review ◽

Scientific Method ◽

Scientific Publication ◽

Policy Advice ◽

Scientific Journals ◽

Review Of Literature ◽

Russian Government ◽

Russian Scientific

This paper presents the first critical review of literature on poverty published in Russia between 1992 and 2006. Using a dataset of about 250 publications in Russian scientific journals we assess whether the poverty research in Russia satisfies the general criteria of a scientific publication and if such studies could provide reliable guidance to the Russian government as it maps out its anti-poverty policies. Our findings indicate that only a small portion of papers on poverty published in Russia in 1992-2006 follow the universally-recognized principles of the scientific method. The utility of policy advice based on such research is questionable. We also suggest certain steps that could, in our view, improve the quality of poverty research in Russia.

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A critical review of some ecological studies on scientific journals.

Journal of Information Processing and Management ◽

10.1241/johokanri.29.863 ◽

1987 ◽

Vol 29 (10) ◽

pp. 863-870

Author(s):

Shigeaki YAMAZAKI

Keyword(s):

Critical Review ◽

Scientific Journals ◽

Ecological Studies

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Remote monitoring of the snow loads on a roof of buildings

Journal Ice and Snow ◽

10.15356/2076-6734-2016-2-246-252 ◽

2016 ◽

Vol 56 (2) ◽

pp. 246-252

Author(s):

V. A. Lobkina ◽

I. A. Kononov ◽

A. A. Potapov

Keyword(s):

Remote Monitoring ◽

Winter Season ◽

Snow Accumulation ◽

Snow Melting ◽

Snow Load ◽

Load Change ◽

Load Cells ◽

Snow Loads ◽

Flat Roof ◽

Snow Loading

Obtaining actual data on a change in the value of snow load for a snowfall is an important task the solution of which is usually neglected. The purpose of the work was to obtain a data on dynamics of the snow load change on a roof for a snowfall. A system for remote monitoring of the snow load was developed for this purpose. This system allows continuous gathering and transmission of the data on the snow load change from a unit of area. Obtaining this information gives an indication of the size of snow loading and dynamics of the snow accumulation during snowfall. The developed system provides continuous collection and transmission of data about the changing snow load per unit area. This information makes possible judging values of the snow load and its dynamics during a snowfall. Using of this system allows monitoring of snow accumulation during a snowfall. Discreteness of the system is 1 minute, and the sensitivity to the load change is 50 g. The platform is designed for a load less than 100 kg. When a snowfall ends the platform should be cleaned. In 2015, the system has been just tested, but in future we plan to use the system without cleaning for the whole snow season. In this connection, the more powerful sensors will be used. The system consists of a rectangular platform with an area of 1 m2, and it is equipped with four load cells «TOQUES» BBA at the corners. It was used for two months from late January to mid-March. In total, nine snowfalls were observed. In the winter season of 2014/15, increases of snow loads changed within the range of 10–100 kg/m2. Analysis of the data shows that the maximum snow load exerted on the roof takes place at a snowfall peak, after that it decreases under the influence of external factors. Three main factors influencing formation of the snow loads on a flat roof are as follows: the quantity of solid precipitation, the snow melting, and redistribution of snow by wind. Using of the system allows obtaining actual values of snow load on roofs of buildings instead of data calculated from the snow weight on the ground. These values can be then used to correct standards for the snow loads.

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