Nitrogen utilization and transformation in red soil fertilized with urea and ryegrass

The influence of fertilization with urea and ryegrass on nitrogen utilization and transformation in red soil has been studied by using ^15N tracer method.When urea and ryegrass were applied alone or in combination,the percentage of N uptaken by ryegrass from labelled urea was 3 and 1.7 times that from labelled ryegrass for the application rate of 200mgN.kg^-1 and 100mgN.kg^-1,respectively;combining application of ryegrass and ureareduced uptake of urea N and increased uptake of ryegrass N by ryegrass plant,but the percentage of N residued in soil increased for urea and decreased for ryegrass.when urea and ryegrass were applied alone,the percentage of N residued in soil from labelled ryegrass was more than 69% while that from labelled urea was less than 25%,and much more ryegrass N was incorporated into humus than urea N.     

Radionuclides in primary coolant of a fluoride salt-cooled high-temperature reactor during normal operation

The release of fission products from coated particle fuel to primary coolant,as well as the activation of coolant and impurities,were analysed for a fluoride salt-cooled high-temperature reactor (FHR) system,and the activity of radionuclides accumulated in the coolant during normal operation was calculated.The release rate (release fraction per unit time) of fission products was calculated with STACY code,which is modelled mainly based on the Fick's law,while the activation of coolant and impurities was calculated with SCALE code.The accumulation of radionuclides in the coolant has been calculated with a simplified model,which is generally a time integration considering the generation and decay of radionuclides.The results show that activation products are the dominant gamma source in the primary coolant system during normal operation of the FHR while fission products become the dominant source after shutdown.In operation condition,health-impacts related nuclides such as 3H,and 14C originate from the activation of lithium and coolant impurities including carbon,nitrogen,and oxygen.According to the calculated effective cross sections of neutron activation,6Li and 14N are the dominant 3H production source and 14C production source,respectively.Considering the high production rate,3H and 14C should be treated before being released to the environment.     

基于MPSoC的轻量化汽车检测系统及硬件加速 平台设计与优化

针对车辆分类检测在精度和实时性方面存在的挑战,提出了一项改进方案,以优化YOLOv5s 模型,旨在实现轻量化 的汽车检测。通过在MPSoC硬件架构的现场可编程门阵列(FPGA) 上设计系统,成功打造了一个具备高精度、快速检测和低 能耗的解决方案。为了使得模型更适合嵌入式设备部署,采用了MobileNetv3 Small 替代YOLOv5s 的主干网络,并引入卷积 块注意力模块(CBAM) 注意力机制和Inner-IoU Loss 优化方法,使模型在轻量化的同时提升了检测精度和速度。改进后的模 型相较于原始Yolov5s模型,平均精度均值(mAP) 提升了14.8%,参数量减少了49.7%,模型体积减小了40.7%,计算量减 少了48.9%,在NVIDIA 3060上,改进后的检测速度提升了48.8%,达到了82 fps。此外,还利用FPGA 对YOLOv5s 进行了 硬件加速。经过优化的系统达到了45fps 的检测帧率,并保持了较高的精度和速度,这一系统易于部署,适用于智能交通系 统,满足其高效实时监测的需求。     

高铁混凝土简支预应力箱梁施工技术研究

结合我国某高铁预应力混凝土简支箱梁采用后张法施工的过程,简要论述三项关键工序、高性能混凝土耐久性指标的保证措施、减小箱梁后期徐变的相关施工措施及注意要点,以确保满足高速铁路运营的安全性、高速度、高平顺性和舒适度.     

除盐水制备技术进展

介绍了几种水除盐技术(蒸馏、离子交换、电渗析、反渗透、电去离子和电吸附)的原理、发展及应用现状,分析了水除盐技术发展的整体脉络,并预测了发展前景.     

信息技术实施规划

主要介绍了制定企业信息技术实施规划的一种方法，包括现状的诊断，目标方向的决策和规划的预测等三个方面的内容，并讨论了与实施规划相关的问题。     

天基发射与载人登月初探

登月是载人航天向深空探测的延续，它与载人飞船工程相比，可靠性要求更高，工程规模更大，资金投入更多。结合国外登月历程和我国航天事业取得的重大成就，探讨了利用现有运载技术，分批次将登月飞船和航天员送入近地轨道，并在天基发射平台上进行组装发射，实现载人登月的设想；并就天基发射平台和天基发射方式进行了初步探讨。