利用独立分量分析法去除地震噪声

 独立分量分析（ICA）作为盲源分离（BSS）的一种新方法,是分解观测数据中独立信息的有力工具。以往的ICA算法一般假设噪声可以忽略不计，而实际的观测数据中又常常包含一些加性噪声。对于加性噪声的影响不能忽略的情况下，改进的ICA算法首先利用非零时间滞后协方差，应用两步特征值分解法(EVD)可成功地去除部分加性噪声的影响；再利用ICA算法就能更好地分离出原信号。本文通过对地震理论模型和实际资料的试验，说明改进的ICA算法能够有效地克服加性噪声对常规ICA算法的影响，能够分离出地震资料中的有效信号，从而实现利用独立分量分析压制地震资料噪声的目的。     

LM2717型双降压直流/直流变换器的原理及其应用设计

LM2717是美国国家半导体公司推出的一款全新的高性能变换器,内含两个脉宽调制(PWM)直流/直流转换器,功能强大.介绍了该器件的主要参数、工作原理和引脚功能,讨论利用LM2717进行应用设计时选择外部器件的原则及设计中应注意的问题.     

Minimum-Energy Translational Trajectory Generation for Differential-Driven Wheeled Mobile Robots

Mobile robots can be used in many applications, such as exploration, search and rescue, reconnaissance, security, and cleaning. Mobile robots usually carry batteries as their energy source and their operational time is restricted by the finite energy available from the batteries. Therefore, energy constraints are critical to the service time of mobile robots. This paper investigates the minimum-energy control problem for translational trajectory generation, which minimizes the energy drawn from the batteries. Optimal control theory is used to find the optimal velocity trajectory in analytic form. To demonstrate energy efficiency obtainable, we performed simulations of minimum-energy velocity control and compared the results with loss-minimization control and energy-optimal trapezoidal velocity profiles. Simulation results showed that significant energy savings can be achieved, of up to 9% compared with loss-minimization control and up to 10% compared with energy-optimal trapezoidal velocity profile. We also performed an actual robot experiment using Pioneer 3-AT platform to show the validity of the proposed minimum-energy velocity control. The experimental results revealed that the proposed minimum-energy velocity control can save the battery energy up to 10% compared with loss-minimization control. Categories (3): Robot control, (5): RobotMotion Planning     

Until的用法以及与其他词的辨析

通过例句讲解了until的用法,辨析了until与till、before的异同,并列举了高中英语和大学英语部分课文及习题中的例句。     

离心式永磁直流发电机的设计研究

离心式永磁直流发电机把皮带轮与离心式转子设计为一体,磁场得到了充分利用,降低了成本。本文介绍了电子稳压器通过移相、削波输出电压稳定的直流电,解决了小型农用车的低速照明问题和用电设施需用直流电的问题。     

Reasoning with Intensional Negative Adjectivals: Semantics, Pragmatics, and Context

Intensional negative adjectives alleged , artificial , fake , false , former , and toy are unusual adjectives that depending on context may or may not be restricting functions. A formal theory of their semantics, pragmatics, and context that uniformly accounts for their complex mathematical and computational characteristics and captures some peculiarities of individual adjectives is presented.
Such adjectives are formalized as new concept builders, negation‐like functions that operate on the values of intensional properties of the concepts denoted by their arguments and yield new concepts whose intensional properties have values consistent with the negation of the old values. Understanding these new concepts involves semantics, pragmatics and context‐dependency of natural language. It is argued that intensional negative adjectives can be viewed as a special‐purpose, weaker, conntext‐dependent negationin natural language. The theory explains and predicts many inferences licensed by expressions involving such adjectives. Implementation of sample examples demonstrates its computational feasibility. Computation of context‐dependent interpretation is discussed.
The theory allows one to enhance a knowledge representation system with similar concept building, negation‐like, context‐dependent functions, the availability of which appears to be a distinct characteristic of natural languages.     

Frontolimbic Response to Negative Feedback in Clinical Depression.

Functional neuroimaging suggests that limbic regions of the medial frontal cortex may be abnormally active in individuals with depression. These regions, including the anterior cingulate cortex, are engaged in both action regulation, such as monitoring errors and conflict, and affect regulation, such as responding to pain. The authors examined whether clinically depressed subjects would show abnormal sensitivity of frontolimbic networks as they evaluated negative feedback. Depressed subjects and matched control subjects performed a video game in the laboratory as a 256-channel EEG was recorded. Speed of performance on each trial was graded with a feedback signal of A, C, or F. By 350 ms after the feedback signal, depressed subjects showed a larger medial frontal negativity for all feedback compared with control subjects with a particularly striking response to the F grade. This response was strongest for moderately depressed subjects and was attenuated for subjects who were more severely depressed. Localization analyses suggested that negative feedback engaged sources in the anterior cingulate and insular cortices. These results suggest that moderate depression may sensitize limbic networks to respond strongly to aversive events. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

一种直流力矩电机跑合防堵转控制电路

本文介绍了一种力矩电机跑合防堵转控制电路。作者对该电路的原理、使用和调试以及实验结果进行了描述。     

特高压输电线路负序方向纵联保护

采用数字式二阶RC低通滤波器和半波差分傅里叶算法，结合相序变换滤取负序分量，可在微机保护中实现负序方向元件，并可在故障初几毫秒内正确动作。用该方法实现的负序方向元件可正确及时地捕捉到由不对称故障发展起来的三相短路故障瞬间的不对称，故可以反映各种不对称故障和由不对称故障发展起来的三相故障。仿真试验验证了用所提出的方法实现的负序方向元件用于特高压输电线路的可行性和优越性。     

环境资源负外部性与产权理论的新进展

环境资源共有产权的特性使得社会成员只能通过自身感知和理解确定对环境资源的产权边界，并且产权的实施是非排他的，所以与环境资源有关的负外部性较其他具有直接因果关系的外部性特殊。在治理这类负外部性的过程中，产权理论也有了新的发展。本文从分析环境资源产权的特殊性入手，对于产权弱化、产权分割、创建新产权和自愿合作基础上认知产权调整等负外部性内部化理论进行了分析。