scholarly journals Fiber Optic-Based Thermal Integrity Profiling of Drilled Shaft: Inverse Modeling for Spiral Fiber Deployment Strategy

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5377
Author(s):  
Wen Deng ◽  
Ruoyu Zhong ◽  
Haiying Ma
Keyword(s):  
Temperature Distribution ◽  
Inverse Modeling ◽  
Fiber Optic ◽  
Forward Modeling ◽  
Effective Radius ◽  
Drilled Shafts ◽  
Drilled Shaft ◽  
Measured Temperature ◽  
Deployment Strategy ◽  
Thermal Integrity

The current state of practice to interpret the thermal integrity profiling (TIP) data of drilled shaft is the so-called effective radius method. It uses the concrete pouring log and average temperature to construct a relationship between temperature distribution and effective radius that can be used to reconstruct a drilled shaft model. While this effective radius method is computationally inexpensive and has good operationality, it is not good at predicting the dimensions and shape of shaft defects. Upgrading the sensor used in conventional TIP from thermocouples/thermal wires to fiber optic sensors, the spatial resolution of the measured temperature will be enhanced. By using the newly proposed spiral fiber deployment strategy, we can improve the reconstruction of shaft defects in the integrity testing of drilled shafts. The corresponding inverse modeling of defected shaft reconstruction for spiral deployment is proposed in this paper based on the temperature distribution pattern that is learned from forward modeling. Through inverse modeling, the details of defects in drilled shafts can be reconstructed numerically. An analysis of the results shows that the prediction by inverse modeling has good agreement with the forward modeling set up initially. This work helps the evolution of the TIP from the nondestructive testing stage to the quantitative nondestructive evaluation stage.

Evaluation of Thermal Integrity Profiling and Crosshole Sonic Logging for Drilled Shafts with Concrete Defects

2019 ◽  
Vol 2673 (8) ◽  
pp. 86-98
Author(s):  
Andrew Z. Boeckmann ◽  
J. Erik Loehr
Keyword(s):  
Temperature Effect ◽  
Temperature Rise ◽  
Maximum Rate ◽  
Drilled Shafts ◽  
Test Method ◽  
Drilled Shaft ◽  
Integrity Test ◽  
Sonic Logging ◽  
Thermal Integrity

Thermal integrity profiling (TIP), which uses temperatures measured along drilled shafts during concrete curing to identify defects, has recently gained favor as an allowable concrete integrity test method for drilled shafts. Drilled shaft concrete temperatures are theoretically sensitive to defects anywhere within the shaft, which presents an opportunity for improving detection over the widely used crosshole sonic logging (CSL) method. This paper describes investigations conducted to compare detectability from TIP and CSL measurements for various types of defects. TIP and CLS measurements are presented for three full-scale drilled shafts constructed with ten intentional defects varying in location, character, and size. Comparison of these measurements indicates TIP and CSL tests are generally complementary with regard to their detection abilities. Each test method is effective for identifying certain types of defects, but limited or incapable of identifying other types of defects. The paper also includes an evaluation of the role of time on the detectability of TIP interpretations, demonstrating that the temperature effect of defects generally peaks around the time of the maximum rate of temperature rise and decreases significantly thereafter.

scholarly journals A Method for Reconstruction of Boiler Combustion Temperature Field Based on Acoustic Tomography

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Yuhui Wu ◽  
Xinzhi Zhou ◽  
Li Zhao ◽  
Chenlong Dong ◽  
Hailin Wang
Keyword(s):  
Temperature Field ◽  
Temperature Distribution ◽  
Optimal Parameter ◽  
Interpolation Method ◽  
Least Square Method ◽  
Reconstruction Algorithm ◽  
Least Square ◽  
Temperature Fields ◽  
Acoustic Tomography ◽  
Measured Temperature

Acoustic tomography (AT), as a noninvasive temperature measurement method, can achieve temperature field measurement in harsh environments. In order to achieve the measurement of the temperature distribution in the furnace and improve the accuracy of AT reconstruction, a temperature field reconstruction algorithm based on the radial basis function (RBF) interpolation method optimized by the evaluation function (EF-RBFI for short) is proposed. Based on a small amount of temperature data obtained by the least square method (LSM), the RBF is used for interpolation. And, the functional relationship between the parameter of RBF and the root-mean-square (RMS) error of the reconstruction results is established in this paper, which serves as the objective function for the effect evaluation, so as to determine the optimal parameter of RBF. The detailed temperature description of the entire measured temperature field is finally established. Through the reconstruction of three different types of temperature fields provided by Dongfang Boiler Works, the results and error analysis show that the EF-RBFI algorithm can describe the temperature distribution information of the measured combustion area globally and is able to reconstruct the temperature field with high precision.

scholarly journals How representative are FLUXNET measurements of surface fluxes during temperature extremes?

2018 ◽  
Author(s):  
Sophie V. J. van der Horst ◽  
Andrew J. Pitman ◽  
Martin G. De Kauwe ◽  
Anna Ukkola ◽  
Gab Abramowitz ◽  
...  
Keyword(s):  
Temperature Distribution ◽  
Latent Heat ◽  
Net Ecosystem Exchange ◽  
The United States ◽  
Fair Use ◽  
Heat Fluxes ◽  
Temperature Extremes ◽  
Measured Temperature ◽  
Sensible Heat ◽  
Lower Tail

Abstract. In response to a warming climate, temperature extremes are changing in many regions of the world. Therefore, understanding how the fluxes of sensible heat, latent heat and net ecosystem exchange respond and contribute to these changes is important. We examined 216 sites from the open access Tier 1 FLUXNET2015 and Free-Fair-Use La Thuile datasets, focussing only on observed (non-gap filled) data periods. We examined the availability of sensible heat, latent heat and net ecosystem exchange observations coincident in time with measured temperature for all temperatures, and separately for the upper and lower tail of the temperature distribution and expressed this availability as a measurement ratio. We showed that the measurement ratios for both sensible and latent heat fluxes are generally lower (0.79 and 0.73 respectively) than for temperature, and the measurement ratio of net ecosystem exchange measurements are appreciably lower (0.42). However, sites do exist with a high proportion of measured sensible and latent heat fluxes, mostly over the United States, Europe and Australia. Few sites have a high proportion of measured fluxes at the lower tail of the temperature distribution over very cold regions (e.g. Alaska, Russia) and at the upper tail in many warm regions (e.g. Central America and the majority of the Mediterranean region), and many of the world’s coldest and hottest regions are not represented in the freely available FLUXNET data at all (e.g. India, the Gulf States, Greenland and Antarctica). However, some sites do provide measured fluxes at extreme temperatures suggesting an opportunity for the FLUXNET community to share strategies to increase measurement availability at the tails of the temperature distribution. We also highlight a wide discrepancy between the measurement ratios across FLUXNET sites that is not related to the actual temperature or rainfall regimes at the site, which we cannot explain. Our analysis provides guidance to help select eddy covariance sites for researchers interested in exploring responses to temperature extremes.

Expansive concrete drilled shafts

1985 ◽  
Vol 12 (2) ◽  
pp. 382-395 ◽  
Author(s):  
Shamim A. Sheikh ◽  
Michael W. O'Neill ◽  
M. A. Mehrazarin
Keyword(s):  
Load Transfer ◽  
Stress Path ◽  
Drilled Shafts ◽  
Drilled Shaft ◽  
Cement Concrete ◽  
Bored Pile ◽  
Expansive Concrete ◽  
Stiff Clay ◽  
Expansive Cement

A hypothesis is presented in this paper that states that expansive cement concrete produces a stronger bond between the concrete in a drilled shaft (bored pile) and the surrounding soil than does normal cement; this results in an increase in the frictional component of capacity and a reduction in the settlement of the shaft at working load levels.Four types of expansive cement, type "K" cement (the expansive cement available commercially) and three made from commercially available materials, were tested for their expansion characteristics; two of them were selected to be used in two instrumented drilled shafts in stiff clay. Normal (type 1) cement was used in a third shaft to serve as a reference. The three shafts were tested to failure after essentially all the expansion was deemed to have taken place in the two expansive concrete shafts. Lateral and longitudinal expansion of the shafts were monitored during the curing period. Load–settlement behaviour and load transfer between shafts and soil during the tests were studied.The test results permitted the preliminary conclusion that expansive cement concrete can increase the frictional capacity of drilled shafts in stiff clay by as much as 50% and reduce the settlement by about 50%. The results are valid for short-term behaviour of drilled shafts made of expansive cement. The long-term behaviour of such shafts remains to be studied. Key words: base bearing capacity, bored pile, cement (expansive), concrete (structural), drilled shaft, ettringite, expansion, frictional capacity, settlement, stress path.

Numerical Simulation of Temperature Distribution in a Containment Vessel of an Operating PWR Plant

2015 ◽  
Vol 1 (1) ◽  
Author(s):  
Yoichi Utanohara ◽  
Michio Murase ◽  
Akihiro Masui ◽  
Ryo Inomata ◽  
Yuji Kamiya
Keyword(s):  
Numerical Simulation ◽  
Temperature Distribution ◽  
Temperature Gradient ◽  
Heat Release ◽  
Gas Phase ◽  
Large Temperature ◽  
Measured Temperature ◽  
Average Temperature ◽  
Containment Vessel ◽  
Large Temperature Gradient

The structural integrity of the containment vessel (CV) for a pressurized water reactor (PWR) plant under a loss-of-coolant accident is evaluated by a safety analysis code that uses the average temperature of gas phase in the CV during reactor operation as an initial condition. Since the estimation of the average temperature by measurement is difficult, this paper addressed the numerical simulation for the temperature distribution in the CV of an operating PWR plant. The simulation considered heat generation of the equipment, the ventilation and air conditioning systems (VAC), heat transfer to the structure, and heat release to the CV exterior based on the design values of the PWR plant. The temperature increased with a rise in height within the CV and the flow field transformed from forced convection to natural convection. Compared with the measured temperature data in the actual PWR plant, predicted temperatures in the lower regions agreed well with the measured values. The temperature differences became larger above the fourth floor, and the temperature inside the steam generator (SG) loop chamber on the fourth floor was most strongly underestimated, −16.2  K due to the large temperature gradient around the heat release equipment. Nevertheless, the predicted temperature distribution represented a qualitative tendency, low at the bottom of the CV and increases with a rise in height within the CV. The total volume-averaged temperature was nearly equal to the average gas phase temperature. To improve the predictive performance, parameter studies regarding heat from the equipment and the reconsideration of the numerical model that can be applicable to large temperature gradient around the equipment are needed.

Field P–y curves in weathered rock

2007 ◽  
Vol 44 (7) ◽  
pp. 753-764 ◽  
Author(s):  
Kook Hwan Cho ◽  
Mohammed A Gabr ◽  
Shane Clark ◽  
Roy H Borden
Keyword(s):  
Field Tests ◽  
Drilled Shafts ◽  
Drilled Shaft ◽  
Weak Rock ◽  
Strain Gages ◽  
Weathered Rock ◽  
Clay Model ◽  
Rock Model ◽  
Stiff Clay ◽  
Subgrade Modulus

In weathered and decomposed rock profiles, the lack of an acceptable analysis procedure for estimating lateral load–displacement response of drilled shafts is compounded by the unavailability of weathered material properties, including the material's lateral subgrade reaction modulus. Such deficiency often leads to the overdesign of the drilled shaft foundation. Six field tests were conducted on drilled shafts to investigate the shape and magnitude of P–y curves in weathered rock material at three locations in North Carolina. The tested shafts were instrumented using dial gages, strain gages, and continuous vertical inclinometers. The measured load versus deflection data are used to study the stiffness response of weathered rock. Measured lateral responses are compared with the results estimated based on a "weak rock" model and a stiff clay model. The comparison shows that Reese's weak rock model overestimated the resistances of the tested shafts while the stiff clay model consistently underestimated the measured shaft resistances. The measured and computed results are analyzed and discussed.Key words: drilled shaft, weathered rock P–y curve, subgrade modulus, ultimate resistances in weathered rock, verification tests.

Application of Fiber Optic BOTDA Sensor for Fire Detection in a Building

2006 ◽  
Vol 321-323 ◽  
pp. 212-216
Author(s):  
Il Bum Kwon ◽  
Chi Yeop Kim ◽  
Dae Cheol Seo
Keyword(s):  
Temperature Distribution ◽  
Optical Fiber ◽  
Fiber Optic ◽  
Smart Structures ◽  
Fire Detection ◽  
Fiber Optic Sensor ◽  
Sensor System ◽  
Real Time Processing ◽  
Optic Sensor ◽  
Electro Optic

Smart structures are to be possessed many functions to sense the external effects, such as seismic loads, temperature, and impact by some explosion, influenced on the safety of structures. This work was focused on the development of a sensing function of smart structures to get the temperature distribution on structures to detect fire occurrences. A fiber optic BOTDA (Brillouin Optical Time Domain Analysis) sensor system was developed to detect the fire occurrence by measuring the temperature distribution of a building’s exterior surfaces. This fiber optic sensor system was constructed with a laser diode and two electro-optic modulators, which made this system faster than systems using only one electro-optic modulator. The temperature distributed on an optical fiber can be measured by this fiber optic BOTDA sensor. An optical fiber, 1400 m in length, was installed on the surface of a building. Using real-time processing of the sensor system, we were able to monitor temperature distribution on the building’s surfaces, and changes in temperature distribution were also measured accurately with this fiber optic sensor.

Study on Thermal Elongation Error of Whirlwind Hard Milling Ballscrew

2013 ◽  
Vol 589-590 ◽  
pp. 221-226
Author(s):  
Yan Feng Li ◽  
Xian Chun Song ◽  
Hong Kui Jiang ◽  
Xiang Rong Xu
Keyword(s):  
Temperature Distribution ◽  
Distribution Pattern ◽  
Measured Temperature ◽  
Hard Milling ◽  
Environmental Technology ◽  
Dynamic Temperature ◽  
Pitch Error ◽  
High Efficient ◽  
Simulation Results ◽  
Screw Pitch

Whirlwind hard milling is a new high-efficient and environmental technology for maching process ballscrew thread. Thermal elongation of the workpiece in processing is one of the main reasons causing the screw-pitch error. The screw-pitch error due to thermal elongation caused by milling heat were analyzed . The dynamic temperature distribution simulation and thermal elogation of the workpiece were carried out with ANSYS software.Compared the simulation results with measured temperature during processing of the workpiece,the temperature distribution pattern is consistent.The result indicate that the law of thermal elongation of the free end and unprocessed section of ballscrew simulated by ANSYS is helpful to compensate screw-pitch error caused by thermal elogation.

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