Exploration of temperature effect on videogrammetric technique for displacement monitoring

Hua-Fei Zhou,Lin-Jun Lu,Zhao-Yi Li,Yi-Qing Ni 국제구조공학회 2020 Smart Structures and Systems, An International Jou Vol.25 No.2

There has been a sustained interest towards the non-contact structural displacement measurement by means of videogrammetric technique. On the way forward, one of the major concerns is the spurious image drift induced by temperature variation. This study therefore carries out an investigation into the temperature effect of videogrammetric technique, focusing on the exploration of the mechanism behind the temperature effect and the elimination of the temperature-caused measurement error. 2D videogrammetric measurement tests under monotonic or cyclic temperature variation are first performed. Features of measurement error and the casual relationship between temperature variation and measurement error are then studied. The variation of the temperature of digital camera is identified as the main cause of measurement error. An excellent linear relationship between them is revealed. After that, camera parameters are extracted from the mapping between world coordinates and pixels coordinates of the calibration targets. The coordinates of principle point and focal lengths show variations well correlated with temperature variation. The measurement error is thought to be an outcome mainly attributed to the variation of the coordinates of principle point. An approach for eliminating temperature-caused measurement error is finally proposed. Correlation models between camera parameters and temperature are formulated. Thereby, camera parameters under different temperature conditions can be predicted and the camera projective matrix can be updated accordingly. By reconstructing the world coordinates with the updated camera projective matrix, the temperature-caused measurement error is eliminated. A satisfactory performance has been achieved by the proposed approach in eliminating the temperature-caused measurement error.

Damage detection of a cable-stayed bridge based on the variation of stay cable forces eliminating environmental temperature effects

Chien-Chou Chen,Wen-Hwa Wu,Chun-Yan Liu,Gwolong Lai 국제구조공학회 2016 Smart Structures and Systems, An International Jou Vol.17 No.6

This study aims to establish an effective methodology for the detection of instant damages occurred in cable-stayed bridges with the measurements of cable vibration and structural temperatures. A transfer coefficient for the daily temperature variation and another for the long-term temperature variation are firstly determined to eliminate the environmental temperature effects from the cable force variation. Several thresholds corresponding to different levels of exceedance probability are then obtained to decide four upper criteria and four lower criteria for damage detection. With these criteria, the monitoring data for three stay cables of Ai-Lan Bridge are analyzed and compared to verify the proposed damage detection methodology. The simulated results to consider various damage scenarios unambiguously indicate that the damages with cable force changes larger than +-1.5% can be detected within 12 hours. Even though not exhaustively reflecting the environmental temperature effects on the cable force variation, both the effective temperature and the air temperature can be considered as valid indices to eliminate these effects at high and low monitoring costs.

Effects of Temperature on the Ground State of a Strongly-Coupling Magnetic Polaron and Mean Phonon Number in RbCl Quantum Pseudodot

Yong Sun,Zhao-Hua Ding,Jing-Lin Xiao 한국물리학회 2016 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.69 No.1

On the condition of strong electron-LO phonon coupling in a RbCl quantum pseudodot (QPD), the ground state energy and the mean number of phonons are calculated by using the Pekar variational method and quantum statistical theory. The variations of the ground state energy and the mean number with respect to the temperature and the cyclotron frequency of the magnetic field are studied in detail. We find that the absolute value of the ground state energy increases (decreases) with increasing temperature when the temperature is in the lower (higher) temperature region, and that the mean number increases with increasing temperature. The absolute value of the ground state energy is a decreasing function of the cyclotron frequency of the magnetic field whereas the mean number is an increasing function of it. We find two ways to tune the ground state energy and the mean number: controlling the temperature and controlling the cyclotron frequency of the magnetic field.

역사경관의 기온저감 효과에 관한 연구 -광평대군묘를 대상으로

정해연 ( Hai Yan Zheng ),김문성 ( Wen Cheng Jin ),이규석 ( Kyoo Seock Lee ) 한국정원학회 2009 한국전통조경학회지 Vol.27 No.3

SiC UMOSFET 구조에 따른 온도 신뢰성 분석

이정연(Jeongyeon Lee),김광수(Kwang-Soo Kim) 한국전기전자학회 2020 전기전자학회논문지 Vol.24 No.1

SiC 기반 소자는 silicon 소자 대비 1200V 이상의 고전압 환경에서 우수하게 동작하며 특히 매우 높은 온도에서 안정적인 특성을 보여준다. 따라서 최근 1700V급 UMOSFET이 전기 자동차, 항공기 등의 전력시스템의 사용을 목표로 활발하게 연구개발 되고 있다. 본 논문에서는 최근 연구되고 있는 세 종류의 1700급 UMOSFET-Conventional UMOSFET (C-UMOSFET), Source Trench UMOSFET (ST-UMOSFET), Local Floating Superjunction UMOSFET (LFS-UMOSFET)-에 대해 온도변화(300K-600K)에 따른 전력소자에서 중요한 변수 (breakdown voltage(BV), on-resistance(Ron), threshold voltage(vth), transconductance(gm))의 신뢰성 특성을 비교 분석하였다. 세 소자 모두 온도 증가에 따른 BV 증가, Ron 증가, vth 감소, gm 감소를 확인하였다. 그러나 세 소자의 구조 차이에 따라 BV, Ron vth, gm 변화에 차이가 있어 그 정도 및 원인에 대해 비교 분석하였다. 모든 결과는 sentaurus TCAD을 통해 simulation 되었다. SiC-based devices perform well in high-voltage environments of more than 1200V compared to silicon devices, and are particularly stable at very high temperatures. Therefore, 1700V UMOSFET has been actively researched and developed for the use of electric power systems such as electric vehicles and aircrafts. In this paper, we analysed thermal variations of critical variables (breakdown voltage (BV), on-resistance (Ron), threshold voltage (vth), and transconductance (gm)) for the three type 1700V UMOSFETs-Conventional UMOSFET (C-UMOSFET), Source Trench UMOSFET (STUMOSFET), and Local Floating Superjunction UMOSFET (LFS-UMOSFET). All three devices showed BV increase, Ron increase, vth decrease, and gm decrease with increasing temperature. However, there are differences in BV, vth, gm, according to the structural differences of the three devices, and the degree and cause of the analysis were compared. All results were simulated using sentaurus TCAD.

A New Method for Separating Temperature Effect of Bridge Strain Monitoring

Lei Huang,Jingzhou Xin,Jiafeng Yang,Shuangjiang Li,Jianting Zhou 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.8

Temperature has a significant influence on bridge strain monitoring data. To improve the accuracy of temperature effect separation in strain monitoring data, this paper proposes a temperature effect separation method comprising variational nonlinear chirp mode decomposition (VNCMD), principal component analysis (PCA) and blind source separation. Firstly, VNCMD was used to decompose the monitoring data of strain and temperature, and the intrinsic mode functions (IMF) of strain and temperature signals were obtained. Secondly, PCA was used to reduce the dimension of IMF, and the false components were eliminated to select the optimal components. After reducing the dimension, the components were used as the input of fast independent component analysis model for blind source separation. Finally, the feasibility and accuracy of the method was verified via the signal-to-noise ratio (SNR) in the simulated signal, and the separation results were evaluated using the Pearson correlation coefficient between the strain component and the corresponding temperature component in real bridge monitoring data. The proposed method performed better than the empirical mode decomposition (EMD) method. The signal-to-noise ratio (SNR) of VNCMD improved 51.80% for daily temperature difference effect and 32.41% for annual temperature difference effect in the numerical study, respectively; the correlation coefficients of VNCMD improved 52.90% for daily temperature difference effect and 4.26% for annual temperature difference effect in practical verification, respectively.

Effect of operating and geometrical parameters on real-time thermal effectiveness of closed-loop borehole heat exchangers in GSHP application

Satish Kumar,K. Murugesan 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.11

The present research work reports the experimental investigation of thermal effectiveness of closed loop single and double U-tube borehole heat exchangers (BHEs) of different depths and diameters. All the experiments were carried out by injecting a constant heat to ground for 48 hours using electric heaters of 3 kW and 5 kW capacities. In all the possible cases, constant and transient thermal effectiveness have been investigated to compare the thermal performance of BHEs. It is observed that the transient value of thermal effectiveness is more stable and consistent as compared to constant thermal effectiveness due consideration of borehole temperature variation during the operation in former case. Decreasing borehole depth by 14 % decreases the thermal effectiveness by 15 % in single U-tube BHE and 7 % in double U-tube BHE. Increasing electrical heat injection to the ground shows least influence on the average value of thermal effectiveness of single and double U-tube BHEs.

Comprehensive approach to understand the association between diurnal temperature range and mortality in East Asia

Kim, J.,Shin, J.,Lim, Y.H.,Honda, Y.,Hashizume, M.,Guo, Y.L.,Kan, H.,Yi, S.,Kim, H. Elsevier Pub.Co 2016 Science of the Total Environment Vol.539 No.-

An adverse association between diurnal temperature range (DTR) and mortality has been suggested, but with variable relationships in different cities. Comprehensive approaches to understanding the health effects of DTR using multinational data are required. We investigated the association between DTR and cause-specific mortality in an age-specific population and assessed the dependency of the health effects of DTR on geographic and climatic factors. Poisson generalized linear regression analyses with allowances for over-dispersion were applied to daily DTR and cause-specific mortality data from 30 cities in China, Japan, Korea, and Taiwan between 1979 and 2010, adjusted for various climatic and environmental factors. City-specific effects of DTR were estimated and summarized for the overall effects using geographic and climatic determinants in a meta-analysis. For all-cause, circulatory, and respiratory mortality, the greatest city-specific effects per 1<SUP>o</SUP>C DTR were found in Tianjin, China (1.80%; 95% confidence interval [CI]: 0.48, 3.14); Tangshan, China (2.25%; 95% CI: 0.65, 3.87); and Incheon, Korea (2.84%; 95% CI: 0.04, 5.73), respectively, and overall effects across 30 cities were 0.58% (95% CI: 0.44, 0.72), 0.81% (95% CI: 0.60, 1.03), and 0.90% (95% CI: 0.63, 1.18), respectively. Using quartile cutoff values for climatic (DTR, and mean temperature) and geographic (latitude, and longitude) characteristics, we divided the 30 cities into 4 different groups and conducted a meta-analysis within the groups using either a random or fixed effects model. Adverse effects of DTR were more pronounced for those aged ≥65years and varied according to geographic, longitudinal (0.07%; 95% CI: 0.05, 0.10), and climatic characteristics and the scale of DTR (0.33%; 95% CI: 0.12, 0.55) for overall all-cause mortality. The DTR is a risk factor affecting human health, depending on geographic location and the temperature variation, with particular vulnerability in aged populations.

진단용 초음파 검사시간에 따른 허벅지의 온도 변화에 관한 고찰

김지원(Jiwon Kim),임현수(Hyunsoo Lim) 한국방사선학회 2012 한국방사선학회 논문지 Vol.6 No.3

진단적 초음파가 태아에 미치는 영향에 대하여는 대부분의 연구결과, 심각한 영향을 미칠 가능성이 매우 낮다고 보고되고 있으나, 장시간의 과도한 조사는 초음파가 인체조직에 온도 상승이나 물리적인 영향을 줄 수 있어 초음파 검사시간에 따라 허벅지의 온도 변화를 조사하여 태아 초음파 검사 시 영향이 없는 시간을 알아보았다. 그 결과 초음파 검사 전보다 40분 안에는 온도가 떨어졌고 50분에는 허벅지의 온도가 검사 전보다 1℃이상 올라가는 것을 확인하였다. 그러므로 40분 안에 초음파 검사를 한다면 안전한 것으로 추론해 본다. Effect of prenatal ultrasound diagnosis have serious damage for the possibility has been reported very low. Long time ultrasound scan can rise the temperature in body tissues and affect the physical. Changes in body temperature have been studied with ultrasound scan time. Fetal ultrasonography were evaluated without the influence of time. The findings, ultrasound scan time in 40 minutes the temperature was reduced. 50 minute tissue temperature rose more than 1 ℃. If within 40 minutes of ultrasound to be safe guess.

열전발전량에 영향을 마치는 요인과 최적의 열전발전시스템에 관한연구

문채주(Moon Chae-joo),정의헌(Cheang Eui-hean),임정민(Lim Jung-min),박상진(Park Sang-jin),김태곤(Kim Tae-gon),김용구(Kim Young-gu) 한국태양에너지학회 2008 한국태양에너지학회 학술대회논문집 Vol.- No.-

This paper describes the causes and effects that have influence on thermoelectric generation. If heat transfer is unequal to thermoelectric modules, we could not get the maximum thermoelectric power. So, by experiment, we analysed the differences of power generation according to the state of the contact between thermoelectric module and heat source. And with the variation of heat transfer area, the generated power was analysed also. Using the experimental results we proposed a thermoelectric generation system.