空气横掠叉排三维外肋管束换热及流阻特性的实验研究

对由重庆大学研制开发的新型三维外肋管叉排管束的换热及流动特性进行正交优化实验研究。实验结果表明：与光管管束相比，在Re=2900-14000范围内，三维外肋管束的换热系数增大了1.5-2.5倍，阻力增大了1－3.5倍。对实验数据进行逐步回归，得出了实验条件下的换热及流阻的准则方程式，并对肋几何参数对换热及流阻的影响进行了分析。     

城市污水生物—生态处理工艺的能效分析

采用生物—生态组合工艺处理城市污水,其中生物单元采用连续流一体化生物反应器(CIBR),生态单元采用波形潜流人工湿地。根据原水水质和生态单元处理效能的季节性变化,通过调整CIBR生物单元的运行工况,实现了对城市污水的高效、低耗、稳定、达标处理。该系统的出水水质全年可稳定地达到《城镇污水处理厂污染物排放标准》(GB 18918—2002)的一级A标准,处理能耗平均为0.362(kW.h)/m3,在达到相同处理效果的基础上,比A2/O工艺和Bardenpho工艺分别降低了37.69%和57.91%。该组合工艺的节能原理是建立在生物单元变工况运行与生态单元低能耗脱氮除磷共同作用基础上的。     

Numerical investigation of erosion on a staggered tube bank by particle laden flows with immersed boundary method

In the present paper, particle-laden flows past 10 × 11 staggered stainless steel tube banks in a duct and the caused erosion are investigated using point-particle Eulerian–Lagrangian method. The continuous gas flow field is obtained through direct numerical simulation. The coupling between fluid and the embedded tubes is handled through the multi-direct forcing immersed boundary method. Four types of coal ash particles with Stokes numbers 0.01, 0.1, 1.0, 10.0, are considered. The collision and erosion characteristics on the tubes located in the middle of the duct are analyzed in detail. It has been found that the global tube erosion of the first tube increases with the increment of the particle size, but particles with an intermediate Stokes number of 1.0 cause the most erosion to the other downstream tubes due to preferential accumulation effect. Results predict much more erosion to the second row of tubes in staggered tube banks than the first row of tubes. Global erosion to the tubes near the wall is much larger than the corresponding ones located in the center, especially far downstream. The maximum local tube erosion occurs within certain angle regions around the tubes, where more attention needs to be paid to prevent erosion.     

对银行批扣电费工作的思考

分析了银行批扣电费系统的优越性和开展银行批扣电费的可行性,探讨了银行批扣电费方式的应用前景,认为这是使得用电客户、供电企业和银行三方都受益的工程,提出了积极推广银行批扣电费工作的实施措施。     

谈谈电力系统无功补偿装置

变电站无功补偿装置是电力系统中重要设备之一,变电站并列电容器组是保证系统电压质量和降低电能损耗的重要设备,从理论上通过简单的计算,得出并联电容器组的各设备间的配合问题,为装置各元件的设计、安装设计,运行提供参考依据。     

Multirate-based fast parallel algorithms for DCT-kernel-based real-valued discrete Gabor transform

Fast parallel algorithms for the DCT-kernel-based real-valued discrete Gabor transform (RDGT) and its inverse transform are presented based on multirate signal processing. An analysis convolver bank is designed for the RDGT and a synthesis convolver bank is designed for its inverse transform. The parallel channels in each of the two convolver banks have a unified structure and can apply the fast DCT algorithms to reduce computation. The computational complexity of each parallel channel is low and depends mainly on the length of the discrete input signal and the number of the Gabor frequency sampling points. Every parallel channel corresponds to one RDGT coefficient, and all the RDGT coefficients are computed in parallel during the analysis process and are finally reconstructed in parallel as pieces of the original signal during the synthesis process. The computational complexity related to the computational time of each RDGT coefficient or each piece of the reconstructed signal in the proposed parallel algorithms is analyzed and compared with those in the existing major parallel algorithms for the RDGT and its inverse transform. The results indicate that the proposed multirate-based fast parallel algorithms for the RDGT are attractive for real-time signal processing.     

一种子带分频段信道估计算法

针对当前高速率通信中信道阶数很长导致信道估计和均衡困难的问题,利用子带 滤波器组近似完全重构的特点,提出一种在子带内进行分频段信道估计、在全频带综合信道 参数的估计方法。该方法较全频带信道估计收敛速度快,收敛误差小,能很好适应恶劣的信 道情况。虽然总的计算量大于全频带信道估计,但由于采用并行计算,所以能大大减少运算 时间。仿真试验表明,在重构误差足够小的情况下,子带数目越多,收敛越快,收敛残差比 全频带信道估计小5 dB左右。     

基于拟合优度检测的子带频谱检测算法

根据雷达对抗侦察接收信号的特点,设计了基于动态非均匀信道化滤波的接收结构.重点研究了其中的频谱感知环节,提出了基于拟合优度检测的子带频谱检测算法.该算法首先假设至少含有K个子带不存在信号,再根据能量最小的K个子带输出估计噪声方差,用估计的噪声方差标准化各子带输出,从而将子带频谱检测问题转化为子带拟合优度的检测问题.该算法能够适用于噪声方差未知且无任何信号先验信息情况.理论分析和仿真实验证明了算法的有效性.     

基于UG的波浪形棘轮参数化设计

依据波浪形曲线方程.利用UG表达式实现波浪形棘轮的参数化精确建模,并以此为模板,借助VC++平台,利用UG/Open二次开发模块,设计MenuScript菜单和UIStyler对话框,编写UG/Open API编程接口及其控制程序,实现模型的调用和更改,进行波浪形棘轮参数化设计,提供了一种三维设计的新思路。