The field measurement of wind-induced response is of great significance to the wind resistance design of high-rise buildings, in particular torsional responses measured from high-rise buildings under ...typhoons. The measured high-rise building, with a height of 108 m, has 32 stories and is supported by giant trusses with four massive columns. Acceleration responses along translational and torsional directions were monitored synchronously and continuously during the passage of Typhoon Sarika on 18 October 2016. The wind speed and wind direction at the height of 115 m, the translational accelerations on a total of six floors and the angular accelerations on a total of four floors were recorded. The time and frequency domain characteristics of translational acceleration and torsional angular accelerations were analyzed. The amplitude-dependent translational and torsional modal frequencies of the measured building were identified by NExT-ERA, SSI, and RDT methods. The full-scale study is expected to provide useful information on the wind-resistant design of high-rise buildings in typhoon-prone regions.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
From 2014 to 2016, several wind resistant field measurements were conducted to the high-rise building in Haikou. Based on these measurements, the present paper disclosed the characteristics of the ...time-history responses of axial acceleration on different floors during four typhoons, including the Rammasun, Kalmaegi, Mujigae and Sarika typhoons. The modal parameters of the measured building were identified by Morlet time-frequency wavelet transform methods, and the amplitude-dependent modal damping ratios and frequencies along translational directions were investigated. The results show that the variation trend of modal frequency with acceleration amplitude identified by the Morlet wavelet is the same as that recognized by time-domain method, while it is scattered with the interval bar (min-average-max) due to the nonstationary response of typhoon. Meanwhile, the larger the amplitude of acceleration response of high-rise buildings under strong wind, the greater the time-varying fluctuation of modal parameters identified by wavelet transform, and the bigger the difference between the interval bar (min-average-max). The full-scale study is expected to provide useful information on the wind-resistant design of high-rise buildings in typhoon-prone regions.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
In electronic assemblies, quad flat package (QFP) is a widely used packaging method and its interconnection structure degradation is an important field in electronic reliability research. Although ...degradation processes and failure modes of QFP are various, presently, there are few researching articles on the degradation regularity and mechanism under the same failure mode. In this paper, QFP degradation experiment has been carried out. Three typical QFP degradation processes and failure modes are obtained by experiment data and crack microscopic analysis. Degradation features and curves are extracted through the health index from fusion of dynamic principal component and Mahalanobis distance(PCMD). The regularity shows that there is a similar inflection point in degradation rate curves, and degradation rates are significantly different after this point. Then, according to Darveaux failure physical model, the strain energy distribution of the crack initiation and propagation area is obtained by finite element simulation. Results show that average strain energy density in crack initiation area is similar but in crack propagation area is not, resulting in crack initiation at similar time but the crack propagation rate is different.
•Three typical QFP degradation trends and failure modes are obtained by experiment.•Degradation features are extracted through the PCMD health index.•Degradation regularity under same failure mode is discovered.•Average strain energy density in crack initiation area and crack propagation area is calculated according to Darveaux model.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Electronics installed in modern complex systems, like automotive and aircraft systems, are mainly subjected to mechanical vibrations in applications. The interconnection structure, as the mechanical ...fixing and electrical interconnection between the electrical device and the printed circuit board, is a key part in electronics. Presently, there are few researching articles on reliability of QFP interconnect structure under random vibration. In this paper, eight specimens of QFP100 with the self-testing real-time circuit have been tested to failure by subjecting to a narrow-band random vibration at its first natural frequency. The charging time of external capacitor in the self-test circuit has been extracted as the monitoring signal. Failure modes of interconnect structure have been analyzed in statistics. Then, the relationship between the monitoring signal and interconnect failure has been investigated. Finally, failure data, conforms to a two-parameter Weibull distribution, has been used to establish the life distribution of interconnect structure. Results show that there are four failure modes and three failure places in interconnect structure under random vibration, which is consistent with simulation results by FEM, and the charging time can characterize the failure and failure process of interconnect structure well.
•QFP package with the self-testing real-time circuit has been tested to failure under narrow-band random vibration.•The charging time of external capacitor in the self-testing circuit has been extracted as the monitoring signal.•The charging time can characterize the failure and failure process of interconnect structure well.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
The chip is the core component of the integrated circuit. Degradation and failure of chip solder joints can directly lead to function loss of the integrated circuit. In order to establish the ...degradation model of chip solder joints under coupled stress, this paper takes quad flat package (QFP) chip solder joints as the study object. First, solder joint degradation data and failure samples were obtained through fatigue tests under coupled stress. Three types of micro failure modes of solder joints were obtained by scanning electron microscope (SEM) analysis and finite element model (FEM) simulation results. Second, the characterization of degradation data was obtained by the principal component of Mahalanobis distance (PCMD) algorithm. It is found that solder joint degradation is divided into three stages: strain accumulation stage, crack propagation stage, and failure stage. Later, Coffin-Manson model and Paris model were modified based on the PCMD health index and strain simulation. The function relationship between strain accumulation time, crack propagation time, and strain was determined, respectively. Solder joint degradation models at different degradation stage were established. Finally, through strain simulation, the models can predict the strain accumulation time and failure time effectively under each failure mode, and their prediction accuracy is above 85%.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Emotion cause extraction (ECE) task that aims at extracting potential trigger events of certain emotions has attracted extensive attention recently. However, current work neglects the implicit ...emotion expressed without any explicit emotional keywords, which appears more frequently in application scenarios. The lack of explicit emotion information makes it extremely hard to extract emotion causes only with the local context. Moreover, an entire event is usually across multiple clauses, while existing work merely extracts cause events at clause level and cannot effectively capture complete cause event information. To address these issues, the events are first redefined at the tuple level and a span‐based tuple‐level algorithm is proposed to extract events from different clauses. Based on it, a corpus for implicit emotion cause extraction that tries to extract causes of implicit emotions is constructed. The authors propose a knowledge‐enriched joint‐learning model of implicit emotion recognition and implicit emotion cause extraction tasks (KJ‐IECE), which leverages commonsense knowledge from ConceptNet and NRC_VAD to better capture connections between emotion and corresponding cause events. Experiments on both implicit and explicit emotion cause extraction datasets demonstrate the effectiveness of the proposed model.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
A long-term load test performed for 470 days on two two-span prestressed concrete (PC) continuous box girders is reported in this paper. Load types were selected as the test variates, and structural ...responses such as support reactions, deflections, and concrete strains were monitored. Simultaneously, affiliated experiments such as material strength, creep, and shrinkage tests were conducted to investigate the time-dependent performances of the materials. Data obtained from these tests showed that deflections, strains, and support reactions develop rapidly in the beginning and stabilize afterward; the reactions of mid- and end-supports decline and rise over time, respectively. Time-dependent patterns of deflections and support reactions were analyzed on the basis of an effective modulus method, and a practical calculation method for long-term deflections considering reaction redistributions was proposed. The effects of the service environment on the performance of PC girders were evaluated through an incremental analysis method.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Up-conversion β-NaYF4:Yb(3+),Tm(3+)/NaYF4 core-shell nanoparticles (NYF NPs) with a high luminous intensity in the visible light region were synthesized by a hydrothermal reaction process. ...Photocurrent densities of the mesoscopic perovskite solar cells fabricated by incorporating up-conversion NYF NPs into the electron transporting layer are effectively enhanced. The effects of the thicknesses of the electron transporting layer and the weight ratio of up-conversion NYF NPs/TiO2 on the power conversion efficiency (PCE) of the as-fabricated devices were also investigated. The results indicate that the PCE of the optimized device achieves 16.9%, which is 20% higher than that of the device without introducing NYF NPs, and the steady-state PCE of the as-fabricated devices is close to its transient-state PCE. The up-conversion effect of NYF NPs is conducive to higher device performance rather than the nanoparticles as scattering centers to increase possible light absorption of the perovskite film or the electronic effect of the NaYF4 shell surface. These results can be further confirmed by finite-difference time-domain simulation. Photoluminescence results suggest that the multiphonon-assistance can accelerate the nonradiative recombination process at a lower temperature. Incorporating NYF NPs into the electron transporting layer opens a new approach to a promising family of electron transporting materials for mesoscopic perovskite solar cells.
This study investigates the vibration response and dynamic characteristics of the Shigudeng Pavilion under environmental excitation, employing a comprehensive approach that includes vibration ...response measurements, theoretical analysis, and finite element numerical simulation. An in-depth examination of the appearance and stress status of the Shigudeng Pavilion in Yao Ancient Village in southern Hunan was conducted, and the horizontal acceleration of different floors of the pavilion under environmental excitation was ascertained through field measurements. The NExT-ERA method was utilized to identify the modal parameters (frequency, damping ratio, and vibration pattern) of the measured timber construction. Subsequently, a finite element analysis model of the ancient timber building was developed and refined using ANSYS Workbench finite element software. This study proposes a specific repair plan addressing apparent defects and structural damage in the measured ancient timber building, offering theoretical and technical references for the conservation and repair of similar structures.
Full measurements for the wind field atop a 32-storey building (supported by four huge columns) and for the dynamic responses of different floors were conducted on 15 October 2017 to obtain the ...translational and torsional responses of the high-rise building during the Typhoon Khanun. The time histories of the torsional angular acceleration responses on the 24th and 32nd floors of the high-rise building were obtained using RA013 rotational accelerometer, and those of the translational acceleration responses on the 6th, 12th, 18th, 24th, 30th and 32nd floors along axial direction were recorded by the translational accelerometer. The variation rules of the translational and torsional acceleration responses with floor height and mean wind speed were disclosed, and the response ratios between the torsional and translational acceleration were analyzed when basic time intervals were 10 min. Based on the target probability method, the value range of the acceleration peak factor with different target reliability under Typhoon Khanun was proposed. The results show that the translational and torsional acceleration peak values and root mean squares are the power functions of mean wind speed. The values of acceleration peak factors are recommended to be 3.0 and 5.0 if target reliabilities are determined as 99.38% and 100%, respectively. Research on torsional response measurements can accumulate valuable scientific data and lay solid foundations for the subsequent studies on the torsional wind-resistant design of high-rise buildings.
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