Abstract Military unmanned ground vehicles are often used in wild natural environment, autonomous following and accompanying security are typical functions. In order to make a quantitative assessment about the autonomous following performance of unmanned ground vehicles on unstructured scenarios, a set of evaluation index system construction method is proposed based on the combination of risk analysis and key performance indexes. First, the kinematics model of autonomous vehicle following in straight and curve based on meta-trajectory is established. Second, the key indexes affecting the following performance are analyzed and obtained from collision risk and lost risk. Third, the evaluation index system of autonomous following performance is constructed from five dimensions: average following speed, collision risk, collision hazard degree, following stability and lost risk. Finally, two unmanned vehicles are tested, the results show that the conclusion based on the constructed evaluation index system can significantly reflect the difference of autonomous following performance, which is basically consistent with the subjective evaluation of the test personnel.
As a renewable energy source, solar energy has become an important part of human energy use. However, facilities utilizing solar energy are often complex and technically difficult, and preparation equipment and materials are expensive, while these equipment and materials often cause new environmental pollution. Soil, which exists in large quantities on the earth's surface, is an inexhaustible natural material with loose and stable properties. Due to the specificity of its composition and microscopic form, the soil has an inherent advantage as a medium for solar thermal and photovoltaic conversion. Here, we built an integrated solar energy utilization system, the Integrated Soil Utilization Module (ISUM), integrating multi-functions into one hybrid system, which enables solar-driven water vapor and electricity generation and soil remediation. The evaporation rate of the soil represented by the rocky land was 1.2 kg·m-2·h-1 under 1-sun irradiation with evaporation induced voltage of 0.3 V. With only seven days of continuous exposure to sunlight, the removal of heavy metal ions from the soil reached 90%, while the pH was raised to near neutral. The combined application of readily available natural soil with solar energy not only demonstrates the potential of a soil for solar desalination and power generation, but in addition, solar-driven interfacial evaporation provides an energy-efficient, environmentally friendly, and sustainable method for purifying heavy metal and acid-contaminated soil.
As the cornerstone of severe accident management strategy, either in-vessel or ex-vessel retention of core melt (IVR or EVR) plays a pivotal role in the stabilization and termination of a severe accident and ultimately secures the safety goal of “Practical elimination of large radioactive release” for light water reactors. In contrast to the IVR measures that are more or less identical in reactor designs, the EVR measures are quite different from design to design. This study intended to give a critical review on the EVR measures adopted in the reactor designs of VVER-1000, EPR, ESBWR, EU-APR1400 and APWR. The review study began with a general description of the existing EVR measures, including their principles, operational procedures and research efforts. We then focused our discussions on the pros and cons of each EVR measure through the comparisons with the IVR and with the others in terms of simplicity, reliability and economy. We finally tried to identify the remaining issues and uncertainties in the qualification of the EVR measures, based on which potential design improvements and future research needs were recommended.
Three-dimensional hydrophobic and efficient electromagnetic shielding Cu/wood/Cu laminated composites were prepared by a simple one-step electroless Cu process. The number of electroless Cu on wood surface and the treatment time of electroless Cu were used as variables. The effects of independent variables in the range from 0.3 ×10−3 to 3.0 GHz (L-band) on the conductivity, water contact angle and electromagnetic shielding effectiveness of the composite were analyzed. The Cu particles are fully filled in the wood hierarchical porous structure, and the metal coating uniformly covers the entire wood surface. After three times of electroless Cu, the conductivity of the composite can reach 7255 S/cm, the contact angle is 130.8° when the time is 12 min, showing good hydrophobic properties, and the average electromagnetic shielding effectiveness is as high as 96 dB. Compared with the L-band (94 dB), the twice electroless sample has a maximum shielding effectiveness of 85.6 dB in the X-band (8.2-12.4 GHz), which can shield a large number of incident electromagnetic waves to achieve high absorption and low reflection. The anisotropic internal porous structure of wood matrix and the multi-interface polarization between wood and Cu are the main reasons for the effective electromagnetic interference shielding performance of Cu/wood/Cu laminated composites.
Preschool teachers' attitudes toward preschool inclusive education (PIE) greatly influence their inclusive education practice. However, few instruments in this area with sound psychometric properties are available for Chinese teachers. The current study aims to validate the Multidimensional Attitudes toward Preschool Inclusive Education Scale (MATPIES) in a Chinese sample and adapt it to the Chinese context (MATPIES-C). A total of 653 preschool teachers participated in this study. The results revealed that (1) the original three-factor structure of MATPIES was not supported by the Chinese sample, and a four-factor structure emerged instead; the derived factors were affective, behavioural, cognitive-arrangement and cognitive-significance. (2) MATPIES-C reported high reliability (reliability coefficients = .904, .921, .827, .831, respectively), and its convergent and discriminant validity were also verified. (3) Comparisons between scores from each sub-construct revealed that the preschool teachers presented mixed attitudes toward PIE and further supported the newly derived four-factor structure. Thus, MATPIES-C provides a sound foundation for future research on Chinese preschool teachers' attitudes toward PIE and can serve as evaluation indicators of PIE training programs for preschool teachers.
'/%3e%3cuse xlink:href='%23a' transform='rotate(23.036 .093 25.536)'/%3e%3cuse xlink:href='%23a' transform='rotate(45.87 1.273 16.18)'/%3e%3cuse xlink:href='%23a' transform='rotate(69.945 .996 12.078)'/%3e%3cuse xlink:href='%23a' transform='rotate(20.66 -19.689 31.932)'/%3e%3c/svg%3e)