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In this study, diamond/silicon carbide (SiC) composites were prepared by liquid Si infiltration. The effects of the infiltration temperature on the densification, diamond graphitization, and thermal conductivity of the composites were investigated. The effects of the diamond content on the thermal conductivity and bending strength were also explored. X‐ray diffraction and Raman spectroscopy detected diamond graphitization at an infiltration temperature of 1480°C. Almost no graphitized diamond was observed due to reactions between silicon and carbon to form SiC at infiltration temperatures higher than 1480°C. As the infiltration temperature increased, graphitized diamond was consumed, and the thermal conductivity of the composite rose. The thermal conductivity and bending strength of the composites depended on the diamond content, reaching values of 257 W/m K and 237 MPa, respectively, for the sample with a diamond content of 17.9 vol.%. The higher bending strength was mainly ascribed to the high diamond content and well‐bonded interface. [ABSTRACT FROM AUTHOR]

Light is the most essential environmental factor that plants require for the growth and development. However, light is highly heterogeneous in natural condition, and plants have to evolve a series of strategies to acclimate the dynamic light since it is sessile. The photosynthetic performance and regulatory mechanisms involved in acclimation were elucidated in shade-tolerant plant Amorphophallus xiei under steady state and fluctuating high light. The dissipation and allocation of light energy, photosynthetic capacity, and antioxidant defense were examined in A. xiei cultivated under 4%, 17%, and 100% of full sunlight. High-light-grown plants exhibited reduced photosynthesis and the slowest response to simulated sunflecks than the other two treatments. Maximum and actual efficiency of PSII photochemistry (Fv′/Fm′ and ΦPSII) and electron transport rate (ETR) were lowest, and non-photochemical quenching (NPQ) were highest in high-light-grown plants than in low- and intermediate-light-grown plants subjected to different photon flux densities (PFD) and intercellular CO2 concentrations (Ci). Fv′/Fm′, ΦPSII, ETR and NPQ were lowest in high-light-grown A. xiei than others, when plants were exposed to simulated sunflecks. In fully light-induced leaves, high-light-grown plants showed a maximum value in quantum efficiency of light-dependent thermal dissipation (ΦNPQ), and a minimum value in ΦPSII was recorded. Low-light-grown plants subjected to simulated sunflecks, a maximum value in ΦNPQ and ΦPSII were observed. Mass-based nitrogen content (Narea), specific leaf area (SLA), superoxide dismutase (SOD) and catalase (CAT) activities significantly declined with the increase of growth irradiance. The high-light-grown plants showed higher xanthophyll de-epoxidation and ascorbate–glutathione cycle activity, while low-light-grown plants showed higher neoxanthin and β-carotene contents. In general, high-light-grown A. xiei generally show a depressed photosynthetic capacity, and are efficient in dissipating excess light energy by NPQ under a steady-state light but not under a highly fluctuating light. Low-light-grown plants show a rapid photosynthetic assimilation response to sunflecks and then a rapid activation of the energy-dependent quenching (qE) component of NPQ under the sunflecks. In addition, high-light-grown plants, although using various strategies to reduce light absorption and to scavenge reactive oxygen species, have less efficient protection against photodamage. [ABSTRACT FROM AUTHOR]

Aiming at the problem that the loading device only has manual control function, the dynamic load characteristic of the high power device's driving system was expounded. A set of designing methods about simulating controllable loading and testing's device was put forward. The mechanical loading device base on magnetic powder clutch and permanent magnet synchronous motor, the upper computer control interface,the control core based on Freescale 56F8346 DSP,the motor driving unit based on power electronics,the high precision current sampling based on MAX1415,a excitation current source base on DC/DC switching circuit and the current detection for excitation current source output based on hall current sensor were designed. At last, the hardware and software of this device was developed. The experiment was worked out and the results show that the dynamic load's analog loading and measurement and control of this exploited device is realized. It offers a important platform for the test of hardware and software and the performance analysis for high power device's driving system. [ABSTRACT FROM AUTHOR]

The general model describing the spectral reflectance of silicon photodiodes is based on the thin-film Fresnel formulas and the known refractive indices of the materials of the photodiodes. It is amended in this paper by considering the diffuse reflectance of the light in Si materials. A precision spectrometer is developed to measurement the specular and diffuse reflectance of a silicon photodiode over the wavelength range from 400 to 900 nm. The results are compared with the corresponding values predicted by the general model and the new model. It is found that the predicted values by the general model show agreement with the experimental values of specular reflectance and show obvious difference with the total reflectance in visible and infrared region. The new model, which considers the diffuse reflection, can predict the total reflectance well. [ABSTRACT FROM AUTHOR]