scholarly journals Rare Weather Phenomena and the Work of Large-Format Roof Coverings

2019 ◽  
Vol 29 (3) ◽  
pp. 123-133 ◽  
Author(s):  
Barbara Ksit ◽  
Anna Szymczak-Graczyk
Keyword(s):  
Wind Velocity ◽  
Large Scale ◽  
Wind Load ◽  
Unique Combination ◽  
Large Format ◽  
Cover Layer ◽  
Wind Action ◽  
Hurricane Wind ◽  
Fundamental Value ◽  
Variable Wind

Abstract Wind action belongs to loads that are environmentally variable. Wind action is included in the basic combination of loads, whereas hurricane wind action is classified as a unique combination. Due to large gusts of wind, the roof coverings of large-scale buildings are exposed to detachment of their cover layer. The article presents the effects of over-normative wind, which occurred on January 19, 2018 and was named the cyclone Frederic/David. The purpose of the article is to show that in design of roof coverings made of large-format materials, such as membranes, it is crucial to accept wind load values properly in order to ensure a right spacing between fasteners. The presented results might be an important contribution to the debate on the necessity for increasing the fundamental value of the basic wind velocity in the perimeter and corner zones of large-format roofs.

Numerical Analysis of Wind Load on Large-Scale Storage Tank under Inverse Installation

2012 ◽  
Vol 174-177 ◽  
pp. 3078-3082
Author(s):  
Dong Li Lv ◽  
Tao Zhang
Keyword(s):  
Wind Velocity ◽  
Storage Tank ◽  
Large Scale ◽  
High Efficiency ◽  
Model Building ◽  
Wind Load ◽  
Tank Wall ◽  
Instability Problem ◽  
Promotion Process ◽  
Lifting Equipment

Inverse installation method of large-scale storage tank has such advantages as less investment, high efficiency, no aloft work, et al, but instability problem may occur during the promotion process in the case of a gale. To evaluate the wind load encountering a gale during the stage of construction, flow field around tank was studied by CFD. Based on simplification and model building of flip tank, the flow fields were simulated for different inlet wind velocity. Combined with the contract of the velocity field inside and outside of tank, the characteristics of the pressure distribution on the tank wall were discussed. The horizontal and vertical wind load on tank wall was calculated and the law of wind load affected by inlet wind velocity was analyzed. The result of the wind load for different inlet wind velocity provided the basis of construction stress analysis of hydraulic lifting equipment for flip-tank.

A Different Kind of Animal

2019 ◽  
Author(s):  
Robert Boyd
Keyword(s):  
Cognitive Ability ◽  
Cultural Adaptation ◽  
Dominant Species ◽  
Large Scale ◽  
Human Beings ◽  
Unique Combination ◽  
Essential Ingredient ◽  
Princeton University

Human beings have evolved to become the most dominant species on Earth. This astonishing transformation is usually explained in terms of cognitive ability—people are just smarter than all the rest. But this book argues that culture—our ability to learn from each other—has been the essential ingredient of our remarkable success. The book shows how a unique combination of cultural adaptation and large-scale cooperation has transformed our species and assured our survival—making us the different kind of animal we are today. The book is based on the Tanner Lectures delivered at Princeton University, featuring challenging responses across the chapters.

Accelerating Large-Format Metal Additive Manufacturing: How Controls R&D Is Driving Speed, Scale, and Efficiency

2020 ◽  
Author(s):  
Brian T. Gibson ◽  
Paritosh Mhatre ◽  
Michael C. Borish ◽  
Justin L. West ◽  
Emma D. Betters ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Large Scale ◽  
Closed Loop ◽  
Size Control ◽  
Pool Size ◽  
Large Format ◽  
Layer Height ◽  
Melt Pool ◽  
The Impact ◽  
Melt Pool Size

Abstract This article highlights work at Oak Ridge National Laboratory’s Manufacturing Demonstration Facility to develop closed-loop, feedback control for laser-wire based Directed Energy Deposition, a form of metal Big Area Additive Manufacturing (m-BAAM), a process being developed in partnership with GKN Aerospace specifically for the production of Ti-6Al-4V pre-forms for aerospace components. A large-scale structural demonstrator component is presented as a case-study in which not just control, but the entire 3D printing workflow for m-BAAM is discussed in detail, including design principles for large-format metal AM, toolpath generation, parameter development, process control, and system operation, as well as post-print net-shape geometric analysis and finish machining. In terms of control, a multi-sensor approach has been utilized to measure both layer height and melt pool size, and multiple modes of closed-loop control have been developed to manipulate process parameters (laser power, print speed, deposition rate) to control these variables. Layer height control and melt pool size control have yielded excellent local (intralayer) and global (component-level) geometry control, and the impact of melt pool size control in particular on thermal gradients and material properties is the subject of continuing research. Further, these modes of control have allowed the process to advance to higher deposition rates (exceeding 7.5 lb/hr), larger parts (1-meter scale), shorter build times, and higher overall efficiency. The control modes are examined individually, highlighting their development, demonstration, and lessons learned, and it is shown how they operate concurrently to enable the printing of a large-scale, near net shape Ti-6Al-4V component.

Prognostic criteria for Polar Lows

2021 ◽  
Author(s):  
Natalia Vazaeva ◽  
Otto Chkhetiani ◽  
Michael Kurgansky
Keyword(s):  
Numerical Simulation ◽  
Wind Velocity ◽  
Large Scale ◽  
Satellite Image ◽  
Development Stage ◽  
Mature Stage ◽  
Initial Development ◽  
Polar Lows ◽  
Prognostic Criteria ◽  
Main Challenge

<p>Polar lows (PLs) are important mesoscale (horizontal diameter up to 1000 km) maritime weather systems at high latitudes, forming pole ward from the polar front. We consider the possible prognostic criteria of PLs, in particular, the kinematic helicity as a quadratic characteristic related to the integral vortex formations and the kinematic vorticity number (KVN). To calculate such characteristics we use reanalysis data and the results of numerical simulation with the WRF-ARW model (Version 4.1.) for the PLs over the Nordic (Norwegian and Barents) seas. For comparison, experimental data are used.</p><p>Our estimate of helicity is based on the connection of an integral helicity (IH) in the Ekman layer with the geostrophic wind velocity, due to the good correlation between IH and half the sum of the wind velocity squared. We have chosen IH averaged over preselected area covering the locality of PLs genesis. This area was moving along with the centre of PL during the numerical simulation.</p><p>The genesis of PLs can be divided into three stages: (i) an initial development stage, in which a number of small vortices appear in a shear zone; (ii) a late development stage, characterized by the merger of vortices; (iii) a mature stage, in which only a single PL is present. Approximately one day before PL formation, a significant increase in helicity was observed. The average helicity bulk density of large-scale motions has values of 0.3 – 0.4 ms<sup>-2</sup>. The local changes in helicity are adjacent to the front side of the PLs. The IH criterion described facilitates the identification of the PLs genesis area. For a more detailed analysis of the PL genesis, it is recommended to apply KVN, which is the additional indicator of PL size and intensity. At the moment of maximum intensity of PLs KVN can reach values of 12 – 14 units. The advantage of using KVN is also in its clear change directly in the centre of the emerging PLs, which allows to precisely indicates the limits of the most intense part of PLs.</p><p>The main challenge is to make the operational forecast of PLs possible through the selection of the prognostic integral characteristics of PLs, sufficient for PLs identification and for analysis of their size and intensity in a convenient, usable and understandable way. The criteria associated with vorticity and helicity are reflected in the PLs genesis and development quite clearly. At this time, such a claim is only a hypothesis, which must be tested using a larger set of cases. Future work will need to extend these analyses to other active PL basins. Also, it would be interesting to compare the representation of PLs by using any other criteria. It is intended to use our combined criteria as a precursor to machine learning-based PLs identification procedure where satellite image analysis and capture of particular cloud patterns are currently applied in most of the cases. It would eliminate the time consuming first stage of collecting data sets.</p><p>This work was supported by the Russian Science Foundation (project No. 19-17-00248).</p>

An efficient Cholesky decomposition and applications for the simulation of large-scale random wind velocity fields

2018 ◽  
Vol 22 (6) ◽  
pp. 1255-1265 ◽  
Author(s):  
Yongle Li ◽  
Chuanjin Yu ◽  
Xingyu Chen ◽  
Xinyu Xu ◽  
Koffi Togbenou ◽  
...  
Keyword(s):  
Wind Velocity ◽  
Large Scale ◽  
Spectral Representation ◽  
Cholesky Decomposition ◽  
Velocity Fields ◽  
Data Driven ◽  
Long Span Bridges ◽  
Long Span ◽  
Spectral Representation Method ◽  
Representation Method

A growing number of long-span bridges are under construction across straits or through valleys, where the wind characteristics are complex and inhomogeneous. The simulation of inhomogeneous random wind velocity fields on such long-span bridges with the spectral representation method will require significant computation resources due to the time-consuming issues associated with the Cholesky decomposition of the power spectrum density matrixes. In order to improve the efficiency of the decomposition, a novel and efficient formulation of the Cholesky decomposition, called “Band-Limited Cholesky decomposition,” is proposed and corresponding simulation schemes are suggested. The key idea is to convert the coherence matrixes into band matrixes whose decomposition requires less computational cost and storage. Subsequently, each decomposed coherence matrix is also a band matrix with high sparsity. As the zero-valued elements have no contribution to the simulation calculation, the proposed method is further expedited by limiting the calculation to the non-zero elements only. The proposed methods are data-driven ones, which can be applicable broadly for simulating many complicated large-scale random wind velocity fields, especially for the inhomogeneous ones. Through the data-driven strategies presented in the study, a numerical example involving inhomogeneous random wind velocity field simulation on a long-span bridge is performed. Compared to the traditional spectral representation method, the simulation results are with high accuracy and the entire simulation procedure is about 2.5 times faster by the proposed method for the simulation of one hundred wind velocity processes.

scholarly journals On (post) modern economy and (non) freedom

2005 ◽  
Vol 50 (166) ◽  
pp. 193-217
Author(s):  
Krstan Malesevic
Keyword(s):  
Large Scale ◽  
Human Life ◽  
General Internal ◽  
Modern Economy ◽  
Summum Bonum ◽  
Essential Questions ◽  
Human Liberty ◽  
Fundamental Value ◽  
The Impact ◽  
Modern Technologies

The (post)modern economy finds itself undoubtedly in the center of a large scale, radical contradictory, and uncertain current transformation of the world. Together with the (post)modern technologies it composes the dominant core of the globalizing processes, often referred to as globalization. The key features and especially the accumulated consequences of these processes pose a challenge for scientific and theoretical thought in the form of essential questions and dilemmas which are in the last instance tied to the impact of globalization on the quality and meaning of human life. This problem relates as much to individuals as it does to different social groups and human communities, that is to the entire humanity as such. This paper attempts to problematise these contradictory relationships between global corporative, economy as an instrumental value and the human liberty as a substantive i.e. the highest, value in itself (summum bonum), which gives meaning and dignity to human life. Therefore if economy in one form or another covers most of human practical activity then it is certain that it can have decisive impact on the most fundamental value of human life, that is the value of freedom (individual, general, internal and external). Of course the impact of economy can act either way - as an encouragement or, as it often happens, as a deterrent to expansion of the human freedom. This paper aims to briefly indicate some causes, characteristics and consequences of global economic processes which, in a way paradoxically, contribute more to narrowing than to opening spaces of human liberty, or simply generate proliferation of "hedonism of unfreedom". Is this another case of "surplus of knowledge" and "deficit of wisdom" that so strongly characterize our age, or something else?.

Spatial Design and Placemaking: Learning From Video Games

2017 ◽  
Vol 21 (3) ◽  
pp. 208-232 ◽  
Author(s):  
Ricardo Álvarez ◽  
Fábio Duarte
Keyword(s):  
Video Games ◽  
Video Game ◽  
Large Scale ◽  
Urban Life ◽  
Human Interaction ◽  
Multiple Viewpoints ◽  
Spatial Design ◽  
Fundamental Value ◽  
Game Developers ◽  
Games Development

Spatial design and placemaking are fundamental to create a vibrant urban life, whereas video games are designed primarily for temporary amusement. However, they both share the same essence of creating large-scale artificial environments for human interaction as their fundamental value. Video game developers have been successfully using spatial design tools to create virtual environments to engage players and build narratives, understanding, and appropriating many characteristics of what makes a place tick. In this article, we argue that spatial design and placemaking could learn from video games development, by incorporating features ranging from storytelling and multiple viewpoints to participatory practices and flexible design.

Determination of Basic Wind Velocity for Wind Load-Governed Limit State

2019 ◽  
Author(s):  
Ji Hyeon Kim ◽  
Hae-Sung Lee
Keyword(s):  
Wind Velocity ◽  
Reliability Index ◽  
General Procedure ◽  
Limit State ◽  
Wind Load ◽  
Wind Pressure ◽  
Load Factor ◽  
Load Effect ◽  
Design Life ◽  
Target Reliability Index

<p>This paper proposes a general procedure for evaluating a nominal value of wind velocity for a wind load- governed limit state to secure a target reliability index during the design life of a structure. The nominal value of wind velocity, referred to as a basic wind velocity, and wind load factor should be determined so that the factored wind load effect secures a target reliability index for a wind load-governed limit state. In this study, the analytical form of the return period of the basic wind velocity is expressed as a function of the target reliability index, wind load factor, and statistical parameters of wind pressure, which are derived as linear functions of the coefficient of wind velocity. The proposed approach is applied to the Korean Highway Bridge Design Code-Cable supported Bridge, which specifies the design life of a structure as 100- and 200-year.</p>

scholarly journals Semi-Automatic 3D City Model Generation from Large-Format Aerial Images

2018 ◽  
Vol 7 (9) ◽  
pp. 339 ◽  
Author(s):  
Mehmet Buyukdemircioglu ◽  
Sultan Kocaman ◽  
Umit Isikdag
Keyword(s):  
Large Scale ◽  
3D Visualization ◽  
Aerial Images ◽  
Model Generation ◽  
City Management ◽  
Large Format ◽  
3D City Models ◽  
3D City Model ◽  
City Model ◽  
City Models

3D city models have become crucial for better city management, and can be used for various purposes such as disaster management, navigation, solar potential computation and planning simulations. 3D city models are not only visual models, and they can also be used for thematic queries and analyzes with the help of semantic data. The models can be produced using different data sources and methods. In this study, vector basemaps and large-format aerial images, which are regularly produced in accordance with the large scale map production regulations in Turkey, have been used to develop a workflow for semi-automatic 3D city model generation. The aim of this study is to propose a procedure for the production of 3D city models from existing aerial photogrammetric datasets without additional data acquisition efforts and/or costly manual editing. To prove the methodology, a 3D city model has been generated with semi-automatic methods at LoD2 (Level of Detail 2) of CityGML (City Geographic Markup Language) using the data of the study area over Cesme Town of Izmir Province, Turkey. The generated model is automatically textured and additional developments have been performed for 3D visualization of the model on the web. The problems encountered throughout the study and approaches to solve them are presented here. Consequently, the approach introduced in this study yields promising results for low-cost 3D city model production with the data at hand.

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