Research Partners,Teaching Partners: A Collaboration between FYC Faculty and Librarians to Study Students’ Research and Writing Habits

In Spring 2012, instruction librarians collaborated with first year composition (FYC) faculty to study students’ research habits as they related to writing. We collected process narratives from students in the introductory FYC course at the beginning and end of the fall semester, and a group of librarians and FYC faculty coded them together. Although we did not achieve one of our initial research goals, we still gained valuable insight into how our students perceive sources and the research process. We applied what we learned to create new instructional materials and developed a valuable relationship with FYC faculty.     

频谱细化在电力谐波分析仪中的应用

论文提出一种基于二段式FFT频谱细化算法,利用了存贮空间中保存的前一次计算的数据,增加了实际计算的数据长度,在运算时间增加不多的情况下,提高了FFT的频率分辨率.并利用谐波分析仪上DSP芯片强大的数字信号处理能力对数据进行分析和处理.该算法作为谐波分析方法用于谐波分析仪中,能提高了谐波分析仪的精确度和快速性.     

一种用于动态电压恢复器的电压跌落检测算法

针对传统的电压跌落d-q检测算法和Hilbert检测算法在补偿快速性和抗干扰性方面存在矛盾的问题,提出了一种将d-q检测算法与Hilbert检测算法相结合的电压跌落检测新算法:对电网侧电压信号采样后,经d-q检测单元得到谐波补偿波形;然后滤除3次谐波,滤波后的信号再经Hilbert检测单元得到电压幅值补偿波形;叠加该2种补偿波形可确定最终的补偿波形。仿真结果表明,该检测算法对于含3次谐波的电压跌落补偿效果较好,兼具补偿快速性和抗干扰能力。     

一种改进的谐波电流检测方法

针对传统的ip-iq谐波电流检测方法采用锁相环虽然能得到三相电流的基频和初相角,但当电网电压发生畸变时则存在检测精度较低、电路复杂的问题,提出了一种改进的无锁相环的谐波电流检测方法;详细分析了当电网电压发生畸变时,在三相电流对称和不对称的情况下该改进方法的检测原理,并给出了该改进方法应用于单相电路谐波电流检测的实现。实验结果表明,该改进方法能够准确、实时地检测谐波电流,且算法简单。     

高阶统计量方法在谐波恢复中的应用

谐波恢复是信号处理中的重要问题,谐波恢复就是在噪声中分析组成信号的各次谐波.噪声分为加性噪声和乘性噪声,本文分析加性噪声和乘性噪声的特点,提出采用高阶统计量的方法抑制噪声,恢复谐波.通过四阶统计量的切片抑制乘性噪声,采用二阶累积量谱抑制加性噪声.仿真结果表明,本方法具有很好的抑制噪声效果.     

Ehrenfeucht-Fraïssé games in finite set theory

In this article, with Ehrenfeucht-Fraïssé games we prove that Δ₁≠Δ₀ on BFR, which implies Δ≠Δ₀ on BFR, and thus solve an open problem raised by Albert Atserias in his dissertation (Δ₀,Δ₁,Δ are fragments of first order logic and BFR is a class of finite sets which in essence is equivalent to a class of finite pure arithmetic structures with built-in BIT predicate).     

无码间串扰传输特性动态仿真分析与研究

码间串扰和信道噪声是影响基带传输系统性能的两个主要因素。因此,如何消除它们的影响,使系统的误码率达到规定的要求是数字基带系统中必须研究的两个问题。奈奎斯特第一准则为消除码间串扰奠定了理论基础。本文将以此为依据,通过使用Systemview和MATLAB软件实现对基带传输系统的仿真,并根据所得图形从消除码间串扰的角度来定性地分析无码间串扰系统函数的传输特性。实验中所得结果将对我们的理解和实践均有一定的指导作用。     

基于EMS系统的低频减载实时计算的实现

目前电网调度生产中尚不能实现低频减载的在线实时监测,调度无法及时掌握低频减载控制负荷,给电网的安全稳定运行造成一定的安全隐患。为解决该问题,在EMS系统中开发了基于设备的动态拓扑功能,利用广度优先算法将末端设备的负荷动态拓扑到需统计的单位母线上,从而实时显示每条母线8轮低频减载值,再利用E语言文件将计算好的值传给上一级单位进行更高电压等级母线的实时统计。     

Small Changes,Big Impact: Tungsten Bronzes with Extremely Large Second Harmonic Generation Achieved by the Transition Metal Doping on the B-Site

Two novel transition metal-doped tungsten bronze oxides, Pb_2.15Li_0.85Nb_4.85Ti_0.15O₁₅ (PLNT) and Pb_2.15Li_0.55Nb_4.85W_0.15O₁₅ (PLNW), are synthesized by high-temperature solid-state reactions. The Rietveld method using the high-resolution synchrotron radiation indicates that PLNT and PLNW crystallize in the orthorhombic polar noncentrosymmetric space group, Pmn2₁ (no. 31). As a class of tungsten bronze oxide, PLNT and PLNW retain a unique rigid framework composed of d⁰ transition metal cation (Ti⁴⁺ or W⁶⁺)-doped highly distorted NbO₆ octahedra along with the subsequently generated Pb/LiO₁₂ and PbO₁₅ polyhedra. Interestingly, the d⁰ transition metal-doped tungsten bronzes, PLNT and PLNW, exhibit extremely large second-harmonic generation (SHG) responses of 56 and 67 × KH₂PO₄, respectively. The observed immeasurably strong SHG is mainly attributed to a net polarization originating from the alignment of highly distorted NbO₆ octahedra with doped transition metals in the frameworks. It is believed that doping transition metal cations at the B-site of the tungsten bronze structures should be an innovative strategy to develop novel high-performance nonlinear optical materials.     

Harmonic control of a dual-valve hydraulic servo system with dynamically allocated flows

Modern industries face increasing demands to improve the precision and workability of equipment, leading to stringent requirements for hydraulic servo systems in terms of flow, accuracy, and output power. High-flow servo valves and multi-valve synchronous control methods have seen more applications in the industry to meet these demands. However, high-flow servo valves are expensive and have unsatisfactory performance, and synchronous control methods require servo valves to have the same hydraulic characteristics, resulting in higher cost and lower accuracy of high-flow hydraulic servo systems. Also, very little has been conducted on controlling single actuators using multiple valves. In this study, we design a novel dual-valve hydraulic servo system structure with a high-flow proportional directional valve that is connected in parallel with a low-flow servo valve and further develop the mathematical model of this dual-valve system. Next, a harmonic control scheme was proposed, which included a flow allocation layer and trajectory tracking layer. Thereby, we achieved optimal control of two valves, and robust performance was guaranteed. Finally, we investigate the relationships between the flows of two valves, the deadband of the proportional directional valve, and trajectory tracking errors. Experimental results show that the proposed control scheme can effectively adjust the output flow of each valve dynamically according to the tracking trajectory and the hydraulic characteristics of the two valves, and the tracking performance of the servo system is significantly improved. This method is promised to enable the realization of an economical, high-flow, high-precision hydraulic servo system that can be generally used in various fields, such as marine engineering and construction.