scholarly journals Multi point monitoring method of prestressed tendon based on distributed sensors

2021 ◽  
Vol 2093 (1) ◽  
pp. 012042
Author(s):  
Wei Sun ◽  
Jun Du ◽  
Qiang Wang ◽  
Li Sun
Keyword(s):  
Monitoring Data ◽  
Small Range ◽  
Positive Role ◽  
Monitoring Method ◽  
Distributed Sensors ◽  
Construction Period ◽  
Strain Monitoring ◽  
Term Change ◽  
Tendon Strain

Abstract This paper presents a multi-point strain monitoring method based on distributed sensors, which can monitor the multi-point stress of prestressed tendons in concrete. Firstly, the special sensor protection device is installed in the designated position of the component. Then, the sensor is placed in the device and attached to the monitored prestressing tendon. After concrete pouring, the device can form a closed space around the sensor to ensure that the sensor can freely expand and move in a small range when the prestressed tendon is tensioned. The proposed method is applied to the monitoring of the construction period and initial operation period of a large-span spatial structure, and the research results show that the method proposed in this paper can well realize the multi-point monitoring of the prestressed tendon strain in the concrete, and effectively solve the engineering problems; through the analysis of the long-term monitoring data, we can accurately grasp the influence of each construction condition on the structure stress, and clarify the actual stress state and long-term change trend of the structure. The obtained monitoring data play a positive role in guiding the construction of prestressed structure, and the construction safety can be objectively evaluated by analyzing the monitoring data.

Comparing monitoring data collected by volunteers and professionals shows that citizen scientists can detect long-term change on coral reefs

2015 ◽  
Vol 24 ◽  
pp. 1-9 ◽  
Author(s):  
Graham Forrester ◽  
Patricia Baily ◽  
Dennis Conetta ◽  
Linda Forrester ◽  
Elizabeth Kintzing ◽  
...  
Keyword(s):  
Coral Reefs ◽  
Monitoring Data ◽  
Term Change

Study on FEM Numerical Simulation and Strain Monitoring of Tunnel Secondary Lining

2014 ◽  
Vol 580-583 ◽  
pp. 1105-1111
Author(s):  
Ying Na Li ◽  
Meng Liu ◽  
Sheng Wu ◽  
Hao Liu ◽  
Jian Kun Su ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Comparative Study ◽  
Monitoring Method ◽  
Strain Monitoring ◽  
Site Monitoring ◽  
Secondary Lining ◽  
Rock Tunnel ◽  
The Comparative Study ◽  
Fem Numerical Simulation

Safety of secondary lining is of utmost importance to tunnel engineering quality as the main load-bearing structure and the last waterproof line of rock tunnel under type III. The comparative study of strain state results from FEM numerical simulation and on-site monitoring in Yunnan Tianxin Tunnel was conducted to obtain the stress regularity of tunnel lining. The results showed that except vault, the strain states of secondary lining obtained by numerical simulation and on-site monitoring were consistent. The strain value of on-site monitoring was approximately 60%~70% to the simulation value. And the strain value of right side was greater than the value of the corresponding location on the left side. It’s noticed that high strain were found in tunnel haunch and arch springing. Great attention should be paid to arch springing for the largest strain value. The strain monitoring value of vault (309.83με~327.23με) has been detected larger than simulation value (209.37με), which matches well the crack phenomenon of vault. Therefore it’s significant to focus on the long-term monitoring of vault. The defects of single on-site monitoring method such as poor predictability were made up effectively by comparative study. The results achieved can be recommended for similar projects.

scholarly journals Monitoring Mechanism in Preservation of Monuments in Hot and Wet Climate Area

2015 ◽  
Vol XL-5/W7 ◽  
pp. 271-275
Author(s):  
M.C. Lee ◽  
Y.L. Tsai ◽  
M.L. Lin ◽  
L.W. Hang ◽  
C.Y. Chen
Keyword(s):  
Monitoring Data ◽  
Biological Behavior ◽  
Monitoring Method ◽  
Monitoring Period ◽  
Cultural Assets ◽  
Long Term Monitoring ◽  
Maintenance Personnel ◽  
Sensor Monitoring ◽  
Term Monitoring

Historic monuments and buildings are critical cultural assets which cannot be presented by again by human beings. Longer affected by natural climate, environment and biological behavior (including human), resulting in damage and the need for repair. Therefore, UNESCO proposed periodic reporting and reactive monitoring in 2007, in order to achieve “early detection, early repair”. This study discusses about suitable preservation monitoring methods for Taiwan. To shed light on damage and impact factors of historical buildings and cultural relics, the study is based on impact and sensor, monitoring method, monitoring period and maintenance personnel in order to propose standard operating procedures of monitoring method. <br><br> To reduce the rate of the human and sensor monitoring, with the long-term monitoring data analysis, it is calculated that 30 minutes is the best period of data collecting. Besides, the study is adopted regression analysis to select temperature variable only then calculate humidity variable function. <br><br> This study provides a reference monitoring method for monitoring personnel and maintenance personnel, and establishes a long-term monitoring data based information for damage and destroy in the future. Monitoring period and maintenance personnel can follow the data based to find out the damage points and problems, to keep the value of cultural assets.

Vivid Imagers Are Better at Detecting Salient Changes

2006 ◽  
Vol 27 (4) ◽  
pp. 218-228 ◽  
Author(s):  
Paul Rodway ◽  
Karen Gillies ◽  
Astrid Schepman
Keyword(s):  
Individual Differences ◽  
Change Detection ◽  
Visual Imagery ◽  
Detection Task ◽  
Level Of Detail ◽  
Detection Accuracy ◽  
Change Detection Task ◽  
Term Change ◽  
High Level

This study examined whether individual differences in the vividness of visual imagery influenced performance on a novel long-term change detection task. Participants were presented with a sequence of pictures, with each picture and its title displayed for 17  s, and then presented with changed or unchanged versions of those pictures and asked to detect whether the picture had been changed. Cuing the retrieval of the picture's image, by presenting the picture's title before the arrival of the changed picture, facilitated change detection accuracy. This suggests that the retrieval of the picture's representation immunizes it against overwriting by the arrival of the changed picture. The high and low vividness participants did not differ in overall levels of change detection accuracy. However, in replication of Gur and Hilgard (1975) , high vividness participants were significantly more accurate at detecting salient changes to pictures compared to low vividness participants. The results suggest that vivid images are not characterised by a high level of detail and that vivid imagery enhances memory for the salient aspects of a scene but not all of the details of a scene. Possible causes of this difference, and how they may lead to an understanding of individual differences in change detection, are considered.

Using Long-Term Population Monitoring Data to Prioritize Conservation Action among Rare Plant Species

2019 ◽  
Vol 39 (2) ◽  
pp. 169 ◽  
Author(s):  
Holly L. Bernardo ◽  
Pati Vitt ◽  
Rachel Goad ◽  
Susanne Masi ◽  
Tiffany M. Knight
Keyword(s):  
Plant Species ◽  
Population Monitoring ◽  
Monitoring Data ◽  
Rare Plant ◽  
Conservation Action ◽  
Rare Plant Species

Social Cohesion, Breaks, and Transformations in Italy, 535–600

2018 ◽  
Author(s):  
Walter Pohl
Keyword(s):  
The Political ◽  
Late Antique ◽  
Religious Context ◽  
Ancient Society ◽  
Complex Process ◽  
Term Change ◽  
Two Generations ◽  
Classical Culture

When the Gothic War began in Italy in 535, the country still conserved many features of classical culture and late antique administration. Much of that was lost in the political upheavals of the following decades. Building on Chris Wickham’s work, this contribution sketches an integrated perspective of these changes, attempting to relate the contingency of events to the logic of long-term change, discussing political options in relation to military and economic means, and asking in what ways the erosion of consensus may be understood in a cultural and religious context. What was the role of military entrepreneurs of more or less barbarian or Roman extraction in the distribution or destruction of resources? How did Christianity contribute to the transformation of ancient society? The old model of barbarian invasions can contribute little to understanding this complex process. It is remarkable that for two generations, all political strategies in Italy ultimately failed.

Structural displacement and strain monitoring based on the edge detection operator

2016 ◽  
Vol 20 (2) ◽  
pp. 191-201 ◽  
Author(s):  
Wei Lu ◽  
Yan Cui ◽  
Jun Teng
Keyword(s):  
Edge Detection ◽  
Image Features ◽  
Image Feature ◽  
Monitoring Method ◽  
Strain Monitoring ◽  
Morphological Operator ◽  
Filtering Effect ◽  
Circular Target ◽  
Plane Displacement ◽  
The Cost

To decrease the cost of instrumentation for the strain and displacement monitoring method that uses sensors as well as considers the structural health monitoring challenges in sensor installation, it is necessary to develop a machine vision-based monitoring method. For this method, the most important step is the accurate extraction of the image feature. In this article, the edge detection operator based on multi-scale structure elements and the compound mathematical morphological operator is proposed to provide improved image feature extraction. The proposed method can not only achieve an improved filtering effect and anti-noise ability but can also detect the edge more accurately. Furthermore, the required image features (vertex of a square calibration board and centroid of a circular target) can be accurately extracted using the extracted image edge information. For validation, the monitoring tests for the structural local mean strain and in-plane displacement were designed accordingly. Through analysis of the error between the measured and calculated values of the structural strain and displacement, the feasibility and effectiveness of the proposed edge detection operator are verified.

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