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On 8 January 2022, an MS6.9 earthquake occurred in the Menyuan county, Qinghai province at the northeastern margin of the Tibetan Plateau. A dense observatory network consisting of accelerographs and intensity meters has obtained many acceleration recordings in this region, which previously had only a few strong motion recordings. Using acceleration data recorded by 141 accelerographs and micro-electro mechanical system (MEMS)-based intensity meters within 100 km of the causative fault, we investigated the spatial distribution and attenuation characteristics of the near-source ground motion during this event. The observed response spectra were compared with the prediction obtained using the NGA-West2 models. It was found that, in the long-period section of >1.0 s, the acceleration response spectra in the rupture forward direction (southeast of the epicenter) were greater than the prediction, while observations on the northwest side were lower than the prediction. Through the spatial distribution of the ground motion and quantitative analysis of the residuals, we found that the rupture directivity effects on the ground motions were controlled by the spatial azimuth relative to the fault and the along-strike projected length of the rupture, which mainly affected the long-period portion of the >1.0 s. In the rupture forward direction, the spectral accelerations (SAs) with periods of 1.0–10.0 s were enhanced to 1.18–1.56 times the average. In the backward direction (northwest of the epicenter), the SAs with periods of 1.0–10.0 s were only 0.63–0.86 times the average. The rupture directivity effects during the MS6.9 (MW6.6) earthquake exhibited an obvious period-dependence and narrowband characteristics, and the amplification effects were the strongest at 5.0 s. The amplification factors in the straight forward directions were underestimated by the empirical model. Two typical velocity pulse records were observed in the rupture forward direction, and their response spectra were significantly amplified at long periods of greater than 1.0 s, with peak amplification values of 4.0–6.0 near the characteristic period of the pulses. This amplification was related to the resonance excited by a specific periodic pulse. Our study provides a reference of quantifying near-source effects for both moderate and major shallow crustal earthquakes by using MEMS recordings in this region.

A recent research focus has been on developing sustainable and renewable high-performance electromagnetic shielding materials. We present here a robust and effective top-down method in which polydopamine (PDA) is added to delignified wood via in situ polymerization, and Ag particles are successfully deposited in the wood channel via PDA’s adhesive property with a subsequent silver mirror reaction. According to our findings, when the AgNO3 content is 30 g/L, the conductivity of 2-mm-thick conductive wood reached 500 S/cm with an electromagnetic interference shielding efficiency of 50 dB in the X-band. The three-dimensional network structure of the wood is preserved, and thus it has good mechanical properties. Hence, silver-plated wood can be used as an electromagnetic shielding material that requires high strength.

Due to the low output voltage of photovoltaic cells and fuel cells, a high-voltage-gain dc–dc converter is indispensable in the renewable energy power generation systems. In this article, a series of high-voltage-gain capacitor clamped dc–dc converters is constructed based on interleaved boost structures by considering the requirement of low input current ripple in fuel cell application. Furthermore, the construction method of capacitor clamped dc–dc converters is summarized according to the construction processes of these converters. Finally, the capacitor clamped dc–dc converter with the voltage gain of 3/(1− D ) is analyzed in detail. Then, a 250-W prototype is built to validate the theoretical analysis and the construction method.

The heating industries are extremely dispersed in China, and most heating enterprises are small in scale, poor in foundation, and chaotic in safety management. The construction method of the double prevention mechanism of heating enterprises in China was analyzed and studied based on the PDCA cycle model and the improved risk assessment method for operating conditions. The analytic hierarchy process was used to determine the weight of dangerous and harmful factors and corresponding control measures for an accident type. The concept of “failure frequency” was introduced, and the calculation method of accident probability (L) was modified so that the accurate hierarchical control and dynamic risk assessment of accident risks can be realized. At the same time, the failure of control measures is defined as “hidden danger” in this paper. Finally, the bidirectional dynamic transmission mechanism of hidden danger investigation and treatment and risk hierarchical control was established. The main problems existing in the construction of double prevention mechanism of heating enterprises in China were discussed and some countermeasures and suggestions were put forward. According to the above methods and steps, the double prevention mechanism of heating enterprises can be reasonably established. Thus, the risks can be effectively identified, the hidden dangers can be controlled, and the safety production of heating enterprises can be guaranteed.

In renewable energy generation systems, the DC–DC converter with high voltage gain is indispensable, which is used to convert the low output voltage of photovoltaic (PV) cells and fuel cells to the high DC bus voltage. In this study, a cost-effective clamping capacitor boost (CCB) converter with high voltage gain is proposed. In the basis of the conventional boost converter, a clamping capacitor cell with two capacitors and two diodes is embedded. Then, the voltage gain of the proposed CCB converter can be doubled compared with the conventional boost converter. Further, unlike the switched capacitor high voltage gain converter, there is no large current spikes on the capacitors in the proposed CCB converter, which can reduce the current stresses and the costs of capacitors a lot. The operation principles and characteristics of the proposed CCB converter are analysed in detail and verified by simulation. Finally, a 450 W prototype is implemented to validate the performances and advantages of the proposed CCB converter. The proposed CCB converter provides a cost-effective choice for high voltage gain converters in the renewable energy generation system with PV cells.

Considering the rapidity and lesser sample amount required, the Fourier Transform Infrared Spectra (FTIR) was often used to quantitatively determine the rubber content of Russian dandelion, guayule, etc. This is because their chemical structure are cis-1,4-polyisoprene (CPI) which has a unique and isolate skeleton stretching vibration peak at 835 cm−1 band, and is convenient for determining the rubber content. However, this method is not suitable for Eucommia Ulmoides (EU) gum which will crystallize easily at room temperature due to the regular chemical structure of trans-1,4-polyisoprene (TPI), that will restrict the skeleton stretching vibration of TPI greatly. As a result, its FTIR spectrum only shows a very small peak at 845 cm−1 band hiding among a number of crystalline peaks around nearby, thus it cannot be used to determine the rubber content of Eucommia ulmoides oliv (E. ulmoids) directly. Actually, these crystalline peaks could be eliminated easily by elevating the temperature over 60 °C, and a unique and isolate skeleton stretching vibration characteristic band at 845 cm−1 was left alone in the TPI's FTIR spectrum which can be used expediently to determine the content of EU gum. At the present paper, the Variable Temperature Fourier Transform Infrared Spectroscopy (VTFTIR) was used to determine the rubber content of E. ulmoides. The results indicate that the rubber content of E. ulmoides samples (1–40, 5–35, 22–11) provided by Northwest Agriculture and Forestry University (NAFU) are 4.66%, 4.04%, 4.32% respectively, and the errors of average value were less than 5% compared with Soxhlet Extraction.

In this paper, a 3L capacitor clamping DC-DC converter with low current ripple and high voltage gain is presented for photovoltaic generation system and fuel cells generation system. The proposed converter is comprised by 3L structure and capacitor clamping structure. By adopting 3L structure in the low voltage side, the proposed converter has the feature of low input current ripple. By adopting the capacitor clamping structure in the high voltage side, the voltage gain of the proposed converter is four times of the Boost converter, and the voltage stresses of the switches are 1/4 of the output voltage. Furthermore, the operating principle and the electrical characteristics of the proposed converter are analyzed in detail. Finally, an experimental prototype is built to verify the theoretical analysis. The proposed converter is suitable for power converter between low input voltage source and high DC bus.

Trabajo presentado en el 23rd Symposium on Biodiversity and Evolutionary Biology of the German Botanical Societ, celebrado en Munich (Alemania), del 8 al 11 de septiembre 2016