scholarly journals 3D Point Cloud Analysis for Damage Detection on Hyperboloid Cooling Tower Shells

2020 ◽  
Vol 12 (10) ◽  
pp. 1542 ◽  
Author(s):  
Maria Makuch ◽  
Pelagia Gawronek
Keyword(s):  
Reinforced Concrete ◽  
Laser Scanning ◽  
Cooling Tower ◽  
Recognition Rate ◽  
Principal Component ◽  
Region Growing ◽  
Inspection System ◽  
Cooling Towers ◽  
Warranty Period ◽  
Automatic Sequence

The safe operation and maintenance of the appropriate strength of hyperboloid cooling towers require special supervision and a maintenance plan that takes into consideration the condition of the structure. With three series of terrestrial laser scanning data, the paper presents an automatic inspection system for reinforced concrete cooling tower shells that ensures detection and measurement of damage together with the verification of the quality and durability of surface repairs as required by industry standards. The proposed solution provides an automatic sequence of algorithm steps with low computational requirements. The novel method is based on the analysis of values of the local surface curvature determined for each point in the cloud using principal component analysis and transformed using the square root function. Data segmentation into cloud points representing a uniform shell and identified defects was carried out using the region growing algorithm. The extent of extracted defects was defined through vectorisation with a convex hull. The proposed diagnostics strategy of reinforced concrete hyperboloid cooling towers was drafted and validated using an object currently under repair but in continuous service for fifty years. The results of detection and measurement of defects and verification of surface continuity at repaired sites were compared with traditional diagnostics results. It was shown that the sequence of algorithm steps successfully identified all cavities, scaling, and blisters in the shell recorded in the expert report (recognition rate—100%). Cartometric vectorisation of defects determined the scope of necessary shell repairs offering higher performance and detail level than direct contact measurement from suspended platforms. Analysis of local geometric features of repaired surfaces provided a reliable baseline for the evaluation of the repairs aimed at restoring the protective properties of the concrete surround, desirable especially in the warranty period.

scholarly journals Measurement point density and measurement methods in determining the geometric imperfections of shell surfaces

2018 ◽  
Vol 105 (1) ◽  
pp. 19-28
Author(s):  
Rafał Kocierz ◽  
Michał Rębisz ◽  
Łukasz Ortyl
Keyword(s):  
Laser Scanning ◽  
Cooling Tower ◽  
Optimal Number ◽  
Cooling Towers ◽  
Geometric Imperfections ◽  
Detailed Model ◽  
Exterior Surface ◽  
Shell Deformation ◽  
Accuracy Of Measurements ◽  
Correct Representation

Abstract In geodetic measurements of deformations in shell cooling towers, an important factor is to optimize the number of points representing the exterior surface of the shell. The conducted analyses of damage to such structures proved that cooling towers exhibited shell deformation consisting of irregular vertical waves (three concavities and two convexities), as well as seven horizontal waves. On this basis, it is claimed that, in accordance with the Shannon theorem, the correct representation of the generated waves requires the measurement of the cooling tower shell in a minimum of 12 vertical and 14 horizontal sections. Such density of the points may not be sufficient to represent local imperfections of the shell. The article presents the results of test measurements and their analysis, which were conducted to verify the assumptions as to the optimal number of measurement points for the shell of a cooling tower. The evaluation was based on a comparative analysis of the data obtained by the Terrestrial Laser Scanning (TLS) method, creating a very detailed model of geometric imperfections in an actual cooling tower with a height of 100 m. Based on the data obtained by the TLS method, point grids of various density were generated. An additional measurement of the cooling tower shell deformation was performed using a precise electronic total station with reflectorless measurement option. Therefore, it was possible to assess the accuracy of measurements by laser scanning in relation to measurements obtained by reflectorless total stations.

scholarly journals Technical and safety aspects at the demolition by blasting works of a cooling tower with a high of 72.00 m

2020 ◽  
Vol 305 ◽  
pp. 00072
Author(s):  
Robert Laszlo ◽  
Cristian Radeanu ◽  
Stefan Ilici ◽  
Mircea Grecea ◽  
Miklos Levente
Keyword(s):  
Reinforced Concrete ◽  
Cooling Tower ◽  
Point Of View ◽  
Cooling Towers ◽  
Slope Ratio ◽  
Base Diameter ◽  
Safety Aspects ◽  
Centre Of Gravity ◽  
Tower Height

From the point of view of demolition, one of the most interesting construction categories is the hyperboloid shape cooling towers. These seemingly fragile structures support at the base on a reinforced concrete belt and pillars. An important element to be taken into account when choosing the demolition solution is the slope of the tower. As this ratio between tower height and base diameter is greater (4-5), the easier is the demolition of the tower by overturning, respectively by moving the centre of gravity of the construction away from its base. In the case of the cooling tower described in this article, its height was 72.00 m and the base diameter of 52.00 m - the slope ratio index being less than 2, which was why the chosen solution of demolition was that of partial lateral collapse followed by a total crash of the tower on its position. The article describes how to perform the demolition of the cooling tower, the technical and safety solutions adopted for its successful collapse in the intended direction, in very sensitive location conditions regarding the constructions and installations in its immediate vicinity.

Case study: Theoretical calculation model and variable condition analysis research on the water-splashing noise for natural draft wet cooling towers

2020 ◽  
Vol 68 (2) ◽  
pp. 137-145
Author(s):  
Yang Zhouo ◽  
Ming Gao ◽  
Suoying He ◽  
Yuetao Shi ◽  
Fengzhong Sun
Keyword(s):  
Theoretical Model ◽  
Sound Pressure Level ◽  
Water Droplet ◽  
Water Distribution ◽  
Sound Pressure ◽  
Cooling Tower ◽  
Distribution Patterns ◽  
Calculation Model ◽  
Pressure Level ◽  
Cooling Towers

Based on the basic theory of water droplets impact noise, the generation mechanism and calculation model of the water-splashing noise for natural draft wet cooling towers were established in this study, and then by means of the custom software, the water-splashing noise was studied under different water droplet diameters and water-spraying densities as well as partition water distribution patterns conditions. Comparedwith the water-splashing noise of the field test, the average difference of the theoretical and the measured value is 0.82 dB, which validates the accuracy of the established theoretical model. The results based on theoretical model showed that, when the water droplet diameters are smaller in cooling tower, the attenuation of total sound pressure level of the water-splashing noise is greater. From 0 m to 8 m away from the cooling tower, the sound pressure level of the watersplashing noise of 3 mm and 6 mm water droplets decreases by 8.20 dB and 4.36 dB, respectively. Additionally, when the water-spraying density becomes twice of the designed value, the sound pressure level of water-splashing noise all increases by 3.01 dB for the cooling towers of 300 MW, 600 MW and 1000 MW units. Finally, under the partition water distribution patterns, the change of the sound pressure level is small. For the R s/2 and Rs/3 partition radius (Rs is the radius of water-spraying area), when the water-spraying density ratio between the outer and inner zone increases from 1 to 3, the sound pressure level of water-splashing noise increases by 0.7 dB and 0.3 dB, respectively.

scholarly journals Monitoring of the Production Process of Graded Concrete Component Using Terrestrial Laser Scanning

2021 ◽  
Vol 13 (9) ◽  
pp. 1622
Author(s):  
Yihui Yang ◽  
Laura Balangé ◽  
Oliver Gericke ◽  
Daniel Schmeer ◽  
Li Zhang ◽  
...  
Keyword(s):  
Production Process ◽  
Laser Scanning ◽  
Hollow Spheres ◽  
Terrestrial Laser Scanning ◽  
Region Growing ◽  
Casting Process ◽  
Concrete Surface ◽  
Cloud Data ◽  
Sphere Detection ◽  
Concrete Component

Accepting the ecological necessity of a drastic reduction of resource consumption and greenhouse gas emissions in the building industry, the Institute for Lightweight Structures and Conceptual Design (ILEK) at the University of Stuttgart is developing graded concrete components with integrated concrete hollow spheres. These components weigh a fraction of usual conventional components while exhibiting the same performance. Throughout the production process of a component, the positions of the hollow spheres and the level of the fresh concrete have to be monitored with high accuracy and in close to real-time, so that the quality and structural performance of the component can be guaranteed. In this contribution, effective solutions of multiple sphere detection and concrete surface modeling based on the technology of terrestrial laser scanning (TLS) during the casting process are proposed and realized by the Institute of Engineering Geodesy (IIGS). A complete monitoring concept is presented to acquire the point cloud data fast and with high-quality. The data processing method for multiple sphere segmentation based on the efficient combination of region growing and random sample consensus (RANSAC) exhibits great performance on computational efficiency and robustness. The feasibility and reliability of the proposed methods are verified and evaluated by an experiment monitoring the production of an exemplary graded concrete component. Some suggestions to improve the monitoring performance and relevant future work are given as well.

scholarly journals Cooling tower plume abatement and plume modeling: a review

2021 ◽  
Author(s):  
Shuo Li ◽  
M. R. Flynn
Keyword(s):  
Public Health ◽  
Solar Energy ◽  
Cooling Tower ◽  
Plume Rise ◽  
Cooling Towers ◽  
Moist Air ◽  
Novel Technologies ◽  
Plume Modeling ◽  
Dry Cooling Tower ◽  
Dry Cooling

AbstractVisible plumes above wet cooling towers are of great concern due to the associated aesthetic and environmental impacts. The parallel path wet/dry cooling tower is one of the most commonly used approaches for plume abatement, however, the associated capital cost is usually high due to the addition of the dry coils. Recently, passive technologies, which make use of free solar energy or the latent heat of the hot, moist air rising through the cooling tower fill, have been proposed to minimize or abate the visible plume and/or conserve water. In this review, we contrast established versus novel technologies and give a perspective on the relative merits and demerits of each. Of course, no assessment of the severity of a visible plume can be made without first understanding its atmospheric trajectory. To this end, numerous attempts, being either theoretical or numerical or experimental, have been proposed to predict plume behavior in atmospheres that are either uniform versus density-stratified or still versus windy (whether highly-turbulent or not). Problems of particular interests are plume rise/deflection, condensation and drift deposition, the latter consideration being a concern of public health due to the possible transport and spread of Legionella bacteria.

scholarly journals Multiscale Supervised Classification of Point Clouds with Urban and Forest Applications

Sensors ◽  
2019 ◽  
Vol 19 (20) ◽  
pp. 4523 ◽  
Author(s):  
Carlos Cabo ◽  
Celestino Ordóñez ◽  
Fernando Sáchez-Lasheras ◽  
Javier Roca-Pardiñas ◽  
and Javier de Cos-Juez
Keyword(s):  
Random Forest ◽  
Laser Scanning ◽  
Supervised Classification ◽  
Computing Time ◽  
Principal Component ◽  
Point Clouds ◽  
Support Vector ◽  
Linear Discriminant ◽  
Vector Machines ◽  
Input Variables

We analyze the utility of multiscale supervised classification algorithms for object detection and extraction from laser scanning or photogrammetric point clouds. Only the geometric information (the point coordinates) was considered, thus making the method independent of the systems used to collect the data. A maximum of five features (input variables) was used, four of them related to the eigenvalues obtained from a principal component analysis (PCA). PCA was carried out at six scales, defined by the diameter of a sphere around each observation. Four multiclass supervised classification models were tested (linear discriminant analysis, logistic regression, support vector machines, and random forest) in two different scenarios, urban and forest, formed by artificial and natural objects, respectively. The results obtained were accurate (overall accuracy over 80% for the urban dataset, and over 93% for the forest dataset), in the range of the best results found in the literature, regardless of the classification method. For both datasets, the random forest algorithm provided the best solution/results when discrimination capacity, computing time, and the ability to estimate the relative importance of each variable are considered together.

Predicting cooling tower plume dispersion

1997 ◽  
Vol 211 (4) ◽  
pp. 291-297 ◽  
Author(s):  
B E A Fisher
Keyword(s):  
Cooling Tower ◽  
Industrial Process ◽  
Local Environment ◽  
Meteorological Conditions ◽  
Performance Criteria ◽  
Plume Dispersion ◽  
Cooling Towers ◽  
Atmospheric Conditions ◽  
Operating Characteristics

An assessment of the effects of visible cooling tower plumes on the local environment can be a necessary part of any proposal for a new large industrial process. Predictions of the dispersion of plumes from cooling towers are based on methods developed for chimney emissions. However, the kinds of criteria used to judge the acceptability of cooling tower plumes are different from those used for stack plumes. The frequency of long elevated plumes and the frequency of ground fogging are the two main issues. It is shown that events associated with significant plume visibility are dependent both on the operating characteristics of the tower and on the occurrence of certain meteorological conditions. The dependence on atmospheric conditions is shown to be fairly complex and simple performance criteria based on the exit conditions from the tower are not sufficient for assessments.

Design of Cooling Towers by the Effectiveness-NTU Method

1989 ◽  
Vol 111 (4) ◽  
pp. 837-843 ◽  
Author(s):  
H. Jaber ◽  
R. L. Webb
Keyword(s):  
Heat Exchanger ◽  
Cooling Tower ◽  
Design Method ◽  
Design Methods ◽  
Parallel Flow ◽  
Basic Method ◽  
Cooling Towers ◽  
Flow Configuration ◽  
Heat Exchanger Design

This paper develops the effectiveness-NTU design method for cooling towers. The definitions for effectiveness and NTU are totally consistent with the fundamental definitions used in heat exchanger design. Sample calculations are presented for counter and crossflow cooling towers. Using the proper definitions, a person competent in heat exchanger design can easily use the same basic method to design a cooling tower of counter, cross, or parallel flow configuration. The problems associated with the curvature of the saturated air enthalpy line are also treated. A “one-increment” design ignores the effect of this curvature. Increased precision can be obtained by dividing the cooling range into two or more increments. The standard effectiveness-NTU method is then used for each of the increments. Calculations are presented to define the error associated with different numbers of increments. This defines the number of increments required to attain a desired degree of precision. The authors also summarize the LMED method introduced by Berman, and show that this is totally consistent with the effectiveness-NTU method. Hence, using proper and consistent terms, heat exchanger designers are shown how to use either the standard LMED or effectiveness-NTU design methods to design cooling towers.

Solder Bumps Inspection UsingPrincipal Component Analysis in Active Thermography

2014 ◽  
Vol 912-914 ◽  
pp. 1529-1533
Author(s):  
Xiang Ning Lu ◽  
Ji Guang Han ◽  
Su Hua Han ◽  
Su Ya Wang ◽  
Ming Hui Shao
Keyword(s):  
Principal Component Analysis ◽  
Principal Component ◽  
Component Analysis ◽  
Source Distribution ◽  
Inspection System ◽  
Thermal Contrast ◽  
Ir Camera ◽  
Active Thermography ◽  
Solder Bumps ◽  
Pixel Value

A nondestructive inspection system has been developed using the active thermography technology. However the solder defects can not be distinguished directly from the thermal images captured by IR camera because of the heating non-uniformities. The principal component analysis is explored to identify the defects of the solder bumps accurately and effectively. Thermal contrast image is obtained by subtracting source distribution map from the original thermal image. The hot spots corresponding to 16 solder bumps are segmented. The pixels with the thermal contrast values ranging from 0.18°C to 0.20°C are counted, and the maximum and the minimum of the pixel value are found out respectively, which are used in the principal component analysis. The missing bump is identified by the first principal component score. The results show that it is effective using the principal component analysis in active thermography for defects inspection of solder bumps in microelectronic packaging.

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