- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
7.4: Visual Fatigue during Viewing High-Dynamic Range Display
摘要： The visual fatigue caused by one hour’s viewing of High-Dynamic Range (HDR) and Standard-Dynamic Range (SDR) display has been through subjective reports, ophthalmological parameters and physiological signals. The results show that visual fatigue becomes more serious with increasing time under the two modes. Compared to SDR display, one hour of viewing HDR display produces significantly greater tired eyes symptom and low frequency power (LF) of heart rate variability.
关键词： High-Dynamic Range display,Standard-Dynamic Range display,visual fatigue,visual fatigue indicator
更新于2025-09-09 09:28:46
-
[IEEE 2018 Condition Monitoring and Diagnosis (CMD) - Perth, WA (2018.9.23-2018.9.26)] 2018 Condition Monitoring and Diagnosis (CMD) - Usability of fiber Bragg grating sensors for the fatigue life monitoring of overhead transmission lines
摘要： Fretting fatigue of transmission lines, caused by Aeolian vibration, always leads to catastrophic failure of conductors. The fatigue life monitoring of overhead transmission lines is an effective method to foresee strands broken of the conductor. Fatigue severity is usually expressed by alternating bending stress which occurs in the vicinity of suspension clamps during vibration. Given that it is hard to measure the fatigue stress directly, according to IEEE, alternating bending amplitude is recommended as a substitute measured parameter for fatigue life. In this paper, an on-line monitoring system based on a fiber- optic acceleration sensor is designed to analyze the fatigue life of overhead transmission lines in Aeolian vibration surveillance. Considering its superior performance of anti-electromagnetic interference, Fiber Bragg Grating (FBG) sensor is used to measure alternating bending amplitude of overhead transmission lines. And a Cumulative Fatigue Damage (CFD) method, which is based on alternating bending amplitude for vibration and the Stress-Cycle (S-N) curves, is proposed to calculate the fatigue life of overhead transmission lines. A case study of the one-month measurement data of Aeolian vibration for 1000kV Ultra-High Voltage (UHV) transmission lines is presented. Then an on-line monitoring system based on a fiber-optic acceleration sensor is designed to analyze the fatigue life of overhead transmission lines in Aeolian vibration surveillance.
关键词： Fretting fatigue,Aeolian vibration,life prediction,fiber Bragg grating
更新于2025-09-09 09:28:46
-
[ASME ASME 2018 37th International Conference on Ocean, Offshore and Arctic Engineering - Madrid, Spain (Sunday 17 June 2018)] Volume 5: Pipelines, Risers, and Subsea Systems - Development and Testing of a Friction-Based Post-Installable Fiber-Optic Monitoring System for Subsea Applications
摘要： This paper continues to document the design, development, and test of a friction-based (non-adhesive) post-installable fiber-optic strain sensing system for oil and gas applications – especially those that require deployment on existing subsea structures. (Ref: OMAE2017-61494 Development and Testing of a Friction-Based Post-Installable Sensor for Subsea Fiber-Optic Monitoring Systems [1]). The prototype fiber-optic monitoring system collects a wide range of real-time data, which can be used to determine structural loading, fatigue, temperature, pressure, and flow assurance on operational platforms. The primary challenge of a post-installed instrumentation monitoring system is to ensure secure coupling between the sensors and the structure of interest for reliable measurements. Friction-based coupling devices have the potential to overcome installation challenges caused by marine growth and soil contamination on subsea structures, flowlines, or risers. This particular design solution is compatible with structures that are suspended in the water column and those that are resting on the seabed. In addition, the system can be installed by commercial divers in shallow depths or by remotely operated vehicles in deep-water applications. Operational limitations of the initial design concept were identified in the previous series of tests (2016-2017), and several innovative enhancements have been implemented which resulted in significant improvements in sensor system coupling and strain measurement correlation with traditional strain measuring devices. This paper provides a summary of the notable prototype design changes, full-scale test article buildup, and detailed performance data recorded during tension and compression loading that simulated representative offshore conditions. The test results were positive and demonstrated the effectiveness of the design enhancements. Compromises made during mounting of the sensing elements resulted in better performance in tension than compression. These effects are well understood and are fully discussed, and do not influence the viability of the design changes. This study is part of a continuing collaboration between the Houston-based NASA-Johnson Space Center and Astro Technology, Inc. within a study called Clear Gulf. The primary objective of the Clear Gulf study is to develop advanced instrumentation technologies that will improve operational safety and reduce the risk of hydrocarbon spillage. NASA provided unique insights, expansive test facilities, and technical expertise to advance these technologies that would benefit the environment, the public, and commercial industries.
关键词： structural loading,subsea,fiber-optic,flow assurance,monitoring system,temperature,pressure,friction-based,fatigue,post-installable
更新于2025-09-09 09:28:46
-
Effects of polymeric filler on polarization fatigue of 1-3 0.74Pb(Mg <sub/>1/3</sub> Nb <sub/>2/3</sub> )O <sub/>3</sub> -0.26PbTiO <sub/>3</sub> single crystal/polymer composites
摘要： Polarization fatigue tests have been conducted on both bulk Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMN-xPT) single crystals and two 1-3 PMN-xPT/polymer composites with both “soft” and “hard” epoxy fillers, respectively. The variations of remnant polarization, coercive electric field, and micro-crack morphology under 10 Hz cyclic electric loading were studied. It was found that the magnitude of coercive field for both composites was higher compared to that of single crystals. However, as the number of cycles increases, the degradation ratio of remnant polarization and the increased portion of coercive field for both composites were lower than that of single crystals; the sequence is PMN-0.26PT bulk single crystal > 1-3 PMN-0.26PT/soft epoxy composites > 1-3 PMN-0.26PT/hard epoxy composites. In addition, the observed micro-crack propagation morphology shows that 1-3 PMN-0.26PT/hard epoxy composites can substantially improve fatigue-resistance owing to the lower stretching strain benefiting from the polymeric filler. Our results indicated that 1-3 PMN-0.26PT/polymer composites present much better electric polarization stability.
关键词： epoxy fillers,PMN-xPT single crystals,polymer composites,micro-crack morphology,polarization fatigue
更新于2025-09-09 09:28:46
-
Temperature-Dependent Domain Dynamics and Electrical Properties of Nd-doped Bi4Ti2.99Mn0.01O12 Thin Films in Fatigue Process
摘要： Bi4Ti2.99Mn0.01O12 (BTM) thin films with different ratio of neodymium (Nd) doping were prepared on Pt(111)/Ti/SiO2/Si(100) substrates through a sol-gel method. The effects of Nd doping on domain dynamics and temperature-dependent fatigue behaviors of BTM thin films were systematically studied. The polarization fatigues of BTM (not doped) and Bi3.5Nd0.5Ti2.99Mn0.01O12 (BNTM05) thin films first get better with the increasing temperature (T) from 300 to 350 K and then become worse from 350 to 400 K, while Bi3.15Nd0.85Ti2.99Mn0.01O12 (BNTM85) thin films show enhanced fatigue endurance from 300 to 400 K. It can be shown that the long-range diffusion of oxygen vacancies in BTM thin film happens more easily through the impedance spectra analysis with T from 300 to 475 K, which can be verified by a lower activation energies (0.13–0.14 eV) compared to those of BNTM05 and BNTM85 (0.17–0.21 eV). Using a temperature-dependent piezoresponse force microscopy (PFM), we have found more responsive domain fragments in Nd-substituted films. The microscopic domain evolution from 298 to 448 K was done to further explain that the domain wall unpinning effect has been enhanced with increasing T. The correlation between microscopic domain dynamics and macroscopic electrical properties clearly demonstrates the effects of charged domain wall in Nd-doped BTM thin films during the fatigue tests.
关键词： domain pinning,temperature-dependent fatigue,domain wall
更新于2025-09-09 09:28:46
-
Composition-dependent xBa(Zr0.2Ti0.8)O3-(1-x)(Ba0.7Ca0.3)TiO3 bulk ceramics for high energy storage applications
摘要： This work reports the composition dependent microstructure, dielectric, ferroelectric and energy storage properties, and the phase transitions sequence of lead free xBa(Zr0.2Ti0.8)O3-(1-x)(Ba0.7Ca0.3)TiO3 [xBZT-(1-x)BCT] ceramics, with x = 0.4, 0.5 and 0.6, prepared by solid state reaction method. The XRD and Raman scattering results confirm the coexistence of rhombohedral and tetragonal phases at room temperature (RT). The temperature dependence of Raman scattering spectra, dielectric permittivity and polarization points a first phase transition from ferroelectric rhombohedral phase to ferroelectric tetragonal phase at a temperature (TR-T) of 40 0C and a second phase transition from ferroelectric tetragonal phase - paraelectric pseudocubic phase at a temperature (TT-C) of 110 0C. The dielectric analysis suggests that the phase transition at TT-C is of diffusive type and the BZT-BCT ceramics are a relaxor type ferroelectric materials. The composition induced variation in the temperature dependence of dielectric losses was correlated with full width half maxima (FWHM) of A1, E(LO) Raman mode. The saturation polarization (Ps) ≈ 8.3 μC/cm2 and coercive fields ≈ 2.9 kV/cm were found to be optimum at composition x = 0.6 and is attributed to grain size effect. It is also shown that BZT-BCT ceramics exhibit a fatigue free response up to 105 cycles. The effect of a.c. electric field amplitude and temperature on energy storage density and storage efficiency is also discussed. The presence of high TT-C (110 0C), a high dielectric constant (εr ≈ 12285) with low dielectric loss (0.03), good polarization (Ps) ≈ 8.3 μC/cm2) and large recoverable energy density (W = 121 mJ/cm3) with an energy storage efficiency (η) of 70 % at an electric field of 25 kV/cm in 0.6BZT-0.4BCT ceramics make them suitable candidates for energy storage capacitor applications.
关键词： spontaneous polarization,Raman spectroscopy,dielectric constant,lead free ceramics,Energy storage capacitors,fatigue
更新于2025-09-09 09:28:46
-
Effect of grain size on piezoelectric, ferroelectric and dielectric properties of PMN-PT ceramics
摘要： Grain size has significant effects on the electromechanical response of piezoceramics. Since the sintering temperature and holding duration affect the grain size and correspondingly their effective piezoelectric response, these issues should be appropriately addressed in order to properly design smart and intelligent systems. In this paper, PMN-PT piezoceramics with the different grain sizes are synthesized by using conventional solid state processing and two-stage sintering method. Grain size effects on the hysteresis, fatigue and creep response are analyzed. Dielectric, ferroelectric and piezoelectric material properties of PMN-PT ceramics are investigated. The piezoelectric coefficient and remnant polarization exhibit diverse grain size effects depending on the sintering temperature and holding duration. The relative dielectric permittivity, piezoelectric coupling constant and dielectric constant show maximum values of 4001, 559 pC/N and 0.696 for the microstructure with average grain size of 3.8 μm. The myriad effects of grain size on piezoelectric response are reported in details.
关键词： Grain size,Fatigue,Piezoelectric,Creep
更新于2025-09-04 15:30:14
-
Non-contact fatigue crack detection in civil infrastructure through image overlapping and crack breathing sensing
摘要： Fatigue cracks are of critical structural safety concern in civil infrastructure. Many existing fatigue crack sensing methods are contact-based, hence extensive human operation is necessary for sensor and/or actuator deployment. In this study, we propose a vision-based non-contact approach to detect fatigue cracks through image overlapping. We treat crack breathing behavior, the small cyclic movement of the crack perpendicular to the crack path under repetitive fatigue loads, as a robust indicator for crack identification. The differential image features provoked by a breathing crack can be extracted, enhanced, and visualized through a series of image processing techniques. The performance of the proposed approach is experimentally validated through two laboratory setups including a small-scale steel compact specimen and a large-scale bridge to cross-frame connection specimen. Test results demonstrate the capability of the proposed approach in reliably identifying the fatigue crack, even the true crack is surrounded by other non-crack features.
关键词： Computer vision,Bridges,Civil infrastructure,Feature matching,Non-contact sensing,Image processing,Structural health monitoring,Image registration,Breathing crack,Fatigue crack detection
更新于2025-09-04 15:30:14
-
Detection of eye strain through blink rate and sclera area using raspberry-pi
摘要： In this paper, a unique approach is proposed to determine eye strain in children caused due to the prolonged exposure to LCD and PDP screens. Blink rate and area of eye sclera are the two efficient metrics relied upon to determine eye strain. Initially, blink rate is computed by monitoring state transitions from open to closed eyes. To segment the sclera region of the eye Otsu’s thresholding and colour tracking, were implemented. These approaches had limitations due to illumination and skin tone. To overcome this, Modified Otsu using Colour Tracking is proposed in this paper. The occurrence of eye strain is determined by comparing the values of the metrics derived in real time with a threshold. The proposed algorithm detects eye strain with an accuracy of 83%. After detection of fatigue an alert message is sent to caretakers.
关键词： Eye fatigue,Otsu,blink rate,sclera,raspberry-pi
更新于2025-09-04 15:30:14