具有打印输出的多功能功率自行车测功仪的研制报告

采用单片机的功率自行车测功仪，可使功率自行车上的运动定量化。本文从测功仪的设计思路、电路原理和软件结构几个方面进行了论述和研讨。     

Effects of C impurities on the elastic properties of NiAl intermetallics

The atomic configuration and ductility of Ni Al intermetallics affected by C impurity have been studied with a first-principles pseudo-potential method. The calculation results indicate that for the substitutional cases, C prefers to replace Ni other than Al in most of the cases except for the Ni-rich case. As compared with the interstitial cases, the C atom can be more easily occupy the Ni-rich octahedron position in both of the Ni-rich and Al-rich cases. The brittleness will be decreased and the ductility will be increased after the Ni Al intermetallics doped with the impurity C atom.     

发展中国家实现比较优势向竞争优势转化的途径——创新与技术

作为发展中国家在国际市场竞争中如何有效地实现比较优势向竞争优势的转化是本文论述的核心。针对传统比较优势的局限性,著名经济学家波特指出,具有竞争优势的比较优势不是先天的资源禀赋,而是后天的,需要创造的。这就是波特所强调的创新,深入分析就会发现,比较优势向竞争优势转化的途径就是创新和技术。     

Automatic user goals identification based on anchor text and click-through data

Understanding the underlying goal behind a user＇s Web query has been proved to be helpful to improve the quality of search. This paper focuses on the problem of automatic identification of query types according to the goals. Four novel entropy-based features extracted from anchor data and click-through data are proposed, and a support vector machines （SVM） classifier is used to identify the user＇s goal based on these features. Experi- mental results show that the proposed entropy-based features are more effective than those reported in previous work. By combin- ing multiple features the goals for more than 97% of the queries studied can be correctly identified. Besides these, this paper reaches the following important conclusions： First, anchor-based features are more effective than click-through-based features; Second, the number of sites is more reliable than the number of links; Third, click-distribution- based features are more effective than session-based ones.     

先锋褐煤二硫化碳和甲醇萃取物的分析

分别以CS2和甲醇为溶剂,辅以超声波对先锋褐煤进行常温萃取,利用傅里叶变换红外光谱(FTIR)和气相色谱/质谱(GC/MS)分析萃取物的组成及结构。结果表明,两种萃取物中共检测到124种有机化合物;CS2萃取物中烃类化合物相对含量较高,占CS2萃取物总量的52.08%,从C14~C30(除C23外)烷连续分布;甲醇萃取物中含氧和含氮化合物相对含量较高,分别占甲醇萃取物总量的39.28%和20.95%;此外还检测到多种生物标示物。     

一种实用的混合有源电力滤波器的设计和仿真

提出了一种结构简单,实用性比较强的拓扑结构,分析了混合有源滤波器(HAPF)各部分器件参数选取的方法,并介绍开关管关断尖峰电压的抑制措施;实验仿真结果表明,这种混合有源滤波器较好地发挥了无源滤波器(PF)和有源滤波器(APF)的优点,并减小了系统的容量,具有良好的无功电流和谐波电流补偿效果.     

川滇地区地壳结构的虚拟地表震源 反射测深法研究

基于中国地震局地质研究所在中国四川西部布设的流动地震观测台阵数据,用近年发展起来的虚拟地表震源反射测深方法研究川滇地区的地壳结构。结果表明,川滇地块、松潘-甘孜地块和杨子地块3个地块虚拟地表震源反射测深的莫霍面深度存在明显差异:1)四川盆地为40 km左右;2)川滇地块为45~50 km;3)松潘-甘孜地块为30~40 km。四川盆地虚拟地表震源反射测深的莫霍面深度与艾里重力均衡模型所预测的结果基本上一致,而川滇地块和松潘-甘孜地块虚拟地表震源反射测深的莫霍面深度明显小于前人得到的接收函数莫霍面深度和艾里重力均衡模型预测的结果。可能与四川盆地地壳结构简单,而川滇地块及松潘-甘孜地块地壳结构复杂有关。同时,结果显示,在鲜水河断裂和安宁河断裂处虚拟地表震源反射测深的莫霍面深度明显变浅,可能与这些深大断裂处地幔物质的上涌有关。研究结果可为认识青藏高原东南缘的构造变形模式提供新的约束。     

基于遥感协同数据对岩性进行监督分类——以阿尔金西段江格勒萨依地区为例

阿尔金西段高压变质带是地质科学研究热门地区,而江格勒萨依地区又是深入探索该地区的重要前沿基地之一,考虑到该区自然地理环境,无法实地进行细致调查,因此遥感地质调查成为重要手段。收集光谱分辨率居中的Landsat-8数据和空间分辨率相对较高的Worldview-2数据,并以Landsat-8数据光谱特征和Worldview-2数据纹理特征为主辅以Worldview-2数据光谱特征进行协同得到协同数据,通过对原始数据和协同数据进行最大似然法监督分类,得到该地区中生代沉积岩及前寒武变质岩分类结果,验证表明协同数据分类总体精度较高,监督分类方法在阿尔金西段地质调查过程中具有推广的可能性。     

Predictive control for mechanical system with backlash based on hybrid model

The mechanical system with backlash is distinguished between a “backlash mode” and a “contact mode”. The inherent switching between the two operating modes makes the system a prime example of hybrid system. For eliminating the bad effect of backlash, a piecewise affine (PWA) model of the mechanical servo system with backlash is built. The optimal control of constrained PWA system is obtained by taking advantage of model predictive control (MPC) method, and the explicit solution of MPC in a look-up table form is figured out by combining the dynamic programming and multi-parametric quadratic programming, thereby establishing an explicit hybrid model predictive controller. Furthermore, a piecewise quadratic (PWQ) function for guaranteeing the stability of closed-loop control is found by formulating the search of PWQ function as a semi-definite programming problem. In the tracking experiments, it is demonstrated that the explicit hybrid model predictive controller has a good traction control effect on the mechanical system with backlash. The error meets the demands of real system. Further, compared to the direct on-line computation, the computation burden is reduced by the explicit solution, thereby being suitable for real-time control of system with short sampling time.