核电厂新型正面进水板框式旋转滤网的设计研究

针对传统正面进水旋转滤网普遍存在的过流断面小影响取水安全、网板提升过程污物易跌落和反冲洗不彻底造成污物夹带等突出问题,以某核电厂水力特征为例,在建立水力模型的基础上,开展了新型正面进水旋转滤网非全断面拦截、网板捞污斗角度优化和全翻转反冲洗卸污等多项创新设计研究.同时,搭建了大型试验台对新型正面进水旋转滤网的拦截清理能力进行验证.结果 表明,在保证核电厂循环水系统(CRF)和重要厂用水系统(SEC)取水量的前提下,即使新型正面进水旋转滤网完全堵塞,也能对83.3％以上过流断面的污物进行有效的预拦截和清理,能极大减轻过滤终端——鼓型滤网的清污压力.     

层叠式高层建筑多维风振效应试验研究

层叠式高层建筑由于体型不规则,且承受三维风荷载作用,其在强风作用下的风致振动效应区别于一般超高层建筑.结合某大型盒式单元构成的超高层建筑,在进行了刚性同步测压风洞试验的基础上,分别对大楼结构的水平、垂直风致振动效应进行了计算和分析,并详细分析了关键风向下结构的等效静风荷载.结果表明:对层叠式不规则结构应综合考虑平动和扭转效应;在结构水平向风效应较大的风向下,平均分量贡献占主导,结构横风振动效应不突出;结构层叠处的大悬挑结构竖向振动效果不明显,可按刚体的阵风效应进行风荷载取值.     

贯入法检测传统灰浆抗压强度试验研究

将贯入法引入文物建筑传统灰浆抗压强度检测当中,以纯白灰、多种配比白灰砂浆以及掺灰泥等传统灰浆为研究对象,研究了手工青砖砌体中传统灰浆灰缝和灰浆试块贯入深度的相关关系,得出了线性回归公式;进行了传统灰浆抗压强度随龄期增长试验,建立了各种灰浆抗压强度随龄期增长曲线,依据《贯入法检测砌筑砂浆抗压强度技术规程》(JGJ/T 136-2017)规定的测强曲线制定方法,建立了传统灰浆贯入法测强曲线.通过实际工程项目的验证,表明该曲线的精度较好,可用于文物建筑墙体砌筑所研究种类的传统灰浆的贯入法测强.     

Tunable microwave absorption properties of nickel-carbon nanofibers prepared by electrospinning

The nickel-carbon nanofibers (Ni-C NFs) were fabricated by the electrospinning of poly(vinyl alcohol) (PVA) and nickel acetate tetrahydrate (NiAc) solution precursor with succedent PVA pyrolyzation and calcination process. The microwave absorption performance and electromagnetic (EM) parameters of the NFs were researched over the frequency range of 2.0–18.0?GHz. Both the impedance matching and EM wave absorption properties of the Ni-C NFs were improved by changing the carbonization temperature. The effect of graphitization degree on reflection loss (RL) and the possible loss mechanisms were directly displayed in the comparative study of each sample. The optimal RL value of ??44.9?dB and an effective frequency bandwidth of 3.0?GHz under a thickness of 3.0?mm can be reached by a sample calcined at 650?°C. These lightweight Ni-C NFs composites can be promising candidates for EM wave absorbers due to the combination of multiple loss mechanisms, nano-size effect and good impedance matching between Ni nanoparticles and CNFs.     

A fuzzy logic PI control with feedforward compensation for hydrogen pressure in vehicular fuel cell system

In a vehicular fuel cell system, alternative load and frequent purge action can lead to anode pressure varies with the hydrogen mass flow fluctuation. It's crucial to control the pressure difference between anode and cathode within a reasonable range to avoid adverse phenomena such as membrane failure, reactant starvation, or even water management fault. In this paper, an improved proportional integrative (PI) controller by the fuzzy logic technique that considers the engineer experience and knowledge on the hydrogen supply system behavior is proposed for hydrogen pressure control, in which the PI parameters are tuned by a fuzzy decision process. Furthermore, load current and purge action regarded as input disturbances are applied for feedforward compensation to reduce the pressure response hysteresis. A hydrogen supply subsystem based on the proportional valve is modeled, and corresponding parameters are determined by analyzing the response time and steady pressure fluctuation. The performance of the conventional PI controller, the fuzzy logic PI (FLPI) controller and fuzzy logic PI with feedforward (FLPIF) controller is validated. The presented results indicated that the FLPI controller significantly improves the dynamic response of hydrogen pressure compared to the PI controller, and the FLPIF controller can further reduce overshoot caused by disturbance. Finally, the proposed FLPIF controller is implemented on a rapid prototype platform of the hydrogen supply subsystem and an actual fuel cell system, exhibiting satisfactory performance.     

一种5 重real-time PCR筛查转基因水稻方法的建立

以转基因水稻中最常用的CaMV35S启动子、NOS终止子、Cry1Ab/Ac基因、HPT基因及SPS水稻内标基因为研究对象，利用5 种不同的荧光信号（FAM、HEX、Taxas Red、Cy5、Cy5.5）进行多重实时聚合酶链式反应（real-time polymerase chain reaction，real-time PCR）检测方法的研究。通过引物组合筛选、反应体系优化、特异性测试、灵敏度测试、适用性测试等一系列实验，建立了5 重real-time PCR方法，灵敏度可达0.032%。此方法具有灵敏度高、结果准确、通量大等优点，可实现水稻中转基因成分的快速、高效检测。     

长河坝水电站大坝填筑快速施工措施探讨

长河坝水电站大坝填筑施工过程中采用的快速施工方法或措施,在满足施工质量和安全要求下,加快了施工进度,实现参建各方共赢。现将施工总体方法及措施总结,以供类似工程借鉴。     

Influence of geosynthetic reinforcement on the stability of an embankment with rigid columns embedded in an inclined underlying stratum

Incompressible dipping substrata are commonly encountered in engineering practice. Compared to horizontal underlying strata, the inclined underlying stratum increase the risk of collapse of embankments reinforced with columns because it weakens the restraint of the column base. The objective of this study is to investigate the effectiveness of geosynthetics on improving the embankment stability when the underlying stratum is inclined. The influence of geosynthetic tensile stiffness on the ultimate surcharge and failure mechanism is studied. A deep-seated failure with column tilting occurs when the geosynthetic tensile stiffness is low, whereas a lateral sliding occurs when the geosynthetic tensile stiffness is high. To illustrate the contribution of geosynthetics, the distribution of the lateral pressures acting on the columns is analyzed.