Seismic damage characteristics of large-diameter shield tunnel lining under extreme-intensity earthquake

Lipid residue analysis of Chinese ritual bronzes: Methodological and archaeological implications

In China, liquid residue was mostly found in sealed bronze vessels associated with alcohol drinks, which are supposed to conserve the complete composition of the beverage, including the additives. So far, most of them have not been sufficiently scientifically verified. In this study, the liquid residue in bronze jars from the late Western Han period in the burial area of Jin Yang ancient city site was investigated by GC/MS, LC–MS/MS, SEM and Raman spectroscopy. These sensitive versatile techniques had unintended consequences in addition to confirming the presence of fermentation products (monosaccharides, alditols, glycerol-related substances and organic acids). The enrichment of oxalic acid, VLCFA (very-long-chain fatty acid), and alkaloids hints that multiple plants were involved in the beverage preparation. The quinazoline alkaloid products from the sediments reveal an important Rutaceae ingredient, which relates to multiple ancient spices and Chinese herbs. Therefore, the liquid residues from Jin Yang ancient city site imply that they are the earliest known herbal wine remains in East Asia to this day. 

Chemical investigation of herbal wine from Jin Yang ancient city site during the late Western Han period in China

Lightning rod structures are susceptible to wind loads due to their high slenderness ratio, high flexibility, and light weight. The wind-induced dynamic response of a lightning rod is critical for structural safety and reliability. The traditional methods for this response, including observation and simulation, focus on structural health monitoring (SHM), wind tunnel tests (WTTs), or fluid–structure interaction (FSI) simulations. However, all these approaches require considerable financial or computational investment. Additionally, problems such as data loss or data anomalies in the sensor monitoring process often occur during SHM or WTTs. This paper proposes an algorithm based on a long short-term memory (LSTM) network to predict the wind-induced dynamic response and to solve the problem of data link fracture caused by abnormal sensor data transmission or wind-induced damage to lightning rod structures under different wind speeds. The effectiveness and applicability of the proposed framework are demonstrated using actual monitoring data. Root-mean-squared error (RMSE), determination of coefficient (R2), variance accounted for (VAF), and the refined Willmott index (RWI) are employed as performance assessment indices for the proposed network model. At the same time, the random forest algorithm is adopted to analyze the correlation between the data of the different measurement points on the lightning rod structure. The results show that the LSTM method proposed in this paper has a high accuracy for the prediction of “missing” strain data during lightning rod strain monitoring under wind speeds of 15.81~31.62 m/s. Even under the extreme wind speed of 31.62 m/s, the values of RMSE, MAE, R2, RWI and VAF are 0.24053, 0.18213, 0.94539, 0.88172 and 0.94444, respectively, which are within the acceptable range. Using the data feature importance analysis function, it is found that the predicted strain data of the measurement point on the top part of the lightning rod structure are closely related to the test strain data of the two adjacent sections of the structure, and the effect of the test strain data of the measurement points that are far from the predicted measurement point can be ignored.

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Long Short-Term Memory Network for Predicting Wind-Induced Vibration Response of Lightning Rod Structures

Abstract For the first time, the influence of fatigue and aging effects on phase transition and ferroelectric switching is studied for the composite based on ferroelectric polycrystals of triglycine sulfate and nanocellulose with different concentrations. The fatigue in samples was created by the exposure to a sinusoidal electric field, while the aging was investigated for samples after 240 h under dry conditions without the pre-exposure. It was figured out that the exposure led to the increase in phase transition temperature and the inhibition of polarization switching. On the contrary, the aging resulted in improving polarization switching and reducing the phase transition temperature.

Fatigue and Aging in a Ferroelectric Composite Based on Triglycine Sulfate Combined with Nanocellulose

With a 500 kV high-voltage substation structure with lightning rods taken as an engineering example, the mechanical behaviors of lightning rod joints are analyzed based on bearing capacity tests of a typical lightning rod structure and reinforced lightning rod structure. In addition, finite element models are built with ANSYS software and verified by experimental results to design an aeroelastic model based on wind tunnel tests and to calculate hot-spot stresses in the subsequent fatigue life analysis. On this basis, according to the aeroelastic model wind tunnel testing results, the fatigue lifetimes of the lightning rod structures are analyzed according to the rain-flow counting method, hot-spot stress range S-N curve and linear fatigue cumulative damage theory. The results show that the bearing capacity and fatigue properties of typical lightning rod joints cannot meet the design requirements, while reinforced lightning rod joints have a better bearing capacity and longer fatigue life because the stress concentration in the joints is significantly relieved. With the distribution of the wind speed and direction at the engineering example site, the wind-induced vibration fatigue life of the typical lightning rod structure is 11.68 years, which is far less than the mandated 50-year design period. In contrast, the fatigue life of the corresponding reinforced lightning rod structure is greatly improved and reaches 326.4 years, which indicates that the reinforcement method is efficient. Overall, the proposed fatigue life estimation method for lightning rod structure joints is feasible and workable. 

Experimental study on the bearing capacity and fatigue life of lightning rod structure joints in high-voltage substation structures

Characterization of liquor remains in Beibaie site, central China during the 8th century BCE

In order to solve the problem of high-amplitude and high-frequency interference generated by the electric drive system of new energy vehicles, the author proposes a closed-loop research method for on-load electromagnetic compatibility testing and simulation for electric drive systems of new energy vehicles. The method includes EMC design of the electric drive system on-load test equipment, establishment of a conducted EMI simulation platform for the electric drive system under load conditions, and optimization of the conducted EMI performance of the electric drive system based on key parameters and PWM control. Experimental results show that if the parasitic inductance of the IGBT gate increases, the conducted emission level in the frequency range of 2∼30 MHz will increase, and there is basically no change at the low frequency, and the position of each resonance point shifts to the relatively low frequency. The experiment was replaced with the DPWM3 modulation mode, and the conducted emission amplitude was reduced by about 2 dBμV in the range of 200 kHz∼2 MHz, and there was basically no change on the whole. Conclusion. It is proved that the electromagnetic compatibility closed-loop development technology of the electric drive system of new energy vehicles under load conditions can meet the development needs of new energy vehicles in the environment where energy problems and air pollution problems are becoming more and more serious.

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Jingpu Li

Papers

Experimental study on the bearing capacity and fatigue life of lightning rod structure joints in high-voltage substation structures

Characterization of liquor remains in Beibaie site, central China during the 8th century BCE

On-Load Electromagnetic Compatibility Test and Simulation Closed-Loop of the Electric Drive System of New Energy Vehicles