补水泵变频调速定压技术在热水供暖系统的应用

简要介绍热水供暖系统常见的定压方式,阐述了补水泵变频调速定压系统的工作原理和补水泵的设计选型方法,并就节能效益与传统补水泵定压进行了对比分析,指出该定压系统的优缺点。     

基于δ算子的网络控制系统最优控制方法

针对具有时延的网络控制系统研究其最优控制问题.利用线性离散系统有限时域的增量式差分变换来取代传统的离散变换,在δ算子域内应用动态规划理论,设计线性离散二次型最优控制律,将包含时延参数的当前状态量和前一时刻的控制信号组成增广向量并进行闭环反馈控制律设计.经过理论和仿真验证,当采样周期趋于无穷小时,δ算子域离散系统的模型参数逼近于相应的连续时间模型参数.     

Coupler design for an L-band electron linac

The RF coupler is a key component for an accelerating structure which is the most important component for a linac. In order to feed microwave power into the accelerating cavities effectively, the coupler has to be well matched with the feeding waveguide. In this paper, an electron linac coupler was designed, constructed and tested. A numerical simulation method based on the Kyhl's method was employed to search for the optimal dimensions of the coupler. The frequency and the coupling coefficient as a function of the coupler dimensions were also calculated. The results fitted the Kyhl's method simulation results well and gave tolerances of the coupler. The coupler was brazed to the accelerating cavities and it was cold-tested and hot-tested. The experimental results were consistent with the numerical simulation results.     

Computed laminography and reconstruction algorithm

Computed laminography (CL) is an alternative to computed tomography if large objects are to be inspected with high resolution. This is especially true for planar objects. In this paper, we set up a new scanning geometry for CL, and study the algebraic reconstruction technique (ART) for CL imaging. We compare the results of ART with variant weighted functions by computer simulation with a digital phantom. It proves that ART algorithm is a good choice for the CL system.     

生态保护是发展生态旅游的根基

本文由生态旅游的兴起而论,分析探讨了生态旅游开发中的凸现问题,并对生态保护提出了相关的建议。     

肺部X线检查对于诊断小儿支气管肺炎的临床意义

根据对100例小儿支气管肺炎病例的分析、X线肺部阳性表现，对于支气管肺炎的早期诊断仅有参考作用，不能以X线表现定诊断。     

蔺草黄斑病的成因及其控制技术探讨

多年的调查、观测、试验和研究结果表明：蔺草黄斑病5月中旬初见，6月上旬后盛发，6月中旬进入发病高峰。草茎个体生育期45～50d是优质长草。受肥、水、气候等不良环境因素影响，草茎伸长缓慢，并且不断成熟老化，抗性逐渐减弱，导致黄斑病的发生，所以是一种生理衰老造成的生理性病害。控制黄斑病的关键是通过综合技术措施压低发病率，如合适的群体、壮健的个体、良好的环境条件，通过促根、壮茎等措施提高抗性，延缓生理衰老和适时喷施药物等。喷施30％爱苗EC能够有效控制黄斑病的发生，防治效果为53．4％-94．5％，平均为68％。     

点接触ZK型蜗杆传动理论分析方法及特点

本文运用啮合理论分析了点接触 ZK 型蜗杆副的理论计算方法,把点接触 ZK 型蜗杆副逆向问题简化为一个三参数超越方程的求解,并运用该简化计算方法分析了西德标准中的数据资料。