试论微小信号采集电路的设计与研究

本文介绍了微小信号采集电路的硬件、软件设计和工作原理,将采集到的微小信号放大后进行A/D转换,并通过串行通信方式传送到上位机,以便对信号进行分析处理.经对所制作微小信号采集电路的试验测试,结果显示,采集电路性能满足设计要求.     

浅析高效率音频功率放大器——D类功放

在音频领域发展的几十年里,A类,B类,AB类音频功率放大器一直占着主导地位。随着科技的不断发展,音频功率放大器也有了新的研究成果—D类功率放大器。D类功率放大器有很多优点,因为低功耗产生热量较少,节省印制电路板(PCB)面积和成本,并且能够延长便携式系统的电池寿命。D类放大器,是通过控制开关单元的ON/OFF,驱动扬声器的放大器。D类放大器是最近几年才发展起来的,在系统的耐用上以及音频质量等都有了很大的提高。     

比较器—线性组件非线性运用的基本电路

比较器是一种能够对输入信号电压与给定参考电压进行比较,视输入信号电压大于还是小于给定参考电压来决定输出状态的电路,因此,它具有比较和鉴别的能力。它应用于林业架空索道拉定、超载报警和木材装车材积测标等装置中。线性组件作为放大器运用时,是工作在闭环状态下,在它的开环电压增益足够大时,其输出和输入间的关系与运算放大器本     

CT扫描攀爬机器人模糊PID力控制算法

【目的】提出一种CT扫描攀爬机器人水平伸缩关节夹持力模糊PID控制算法,以实现其夹持力的精确控制,增强对古建筑立木柱的安全保护。【方法】首先,使用巴特沃斯二阶低通滤波器对压力传感器输出值进行滤波,减弱噪声等干扰信号对测量值的影响;然后,以力误差和力误差变化率为系统输入,选择三角函数为隶属度函数进行模糊化处理,根据PID整理规则分别建立PID参数的模糊推理规则,利用系数加权平均法对系统输出进行反模糊化处理;最后,对比分析模糊PID控制算法和耦合PD控制算法的力控制效果。【结果】接触过程中,压力传感器信号经滤波处理后,波动明显减小。夹紧过程中,相比耦合PD控制算法,模糊PID控制算法的夹持力控制精度最大可提高51.8%,相对关节力误差最高可提高99.8%,力调节时间也不同程度优化,且模糊PID控制算法还可消除夹持力调节过程中的超调现象。【结论】巴特沃斯二阶低通滤波可有效滤除压力传感器输出值中噪声等信号的干扰,提高接触检测的可靠性;相比耦合PD控制算法,模糊PID控制算法具有更好的夹持力控制效果,不仅可以提高CT扫描攀爬机器人工作的可靠性,而且能够进一步保证古建筑木立柱的安全。     

I/O板卡的开发技术及工业现场控制系统抗干扰措施

主要从硬件构成及抗干扰措施方面介绍一种采用单片机技术开发的含RS-232接口的I/O板卡.该卡能实现11路A/D转换、4路D/A转换、16路开关量输入和16路开关量输出及1路16位的定时器控制;通过在单片机方和PC机方制定相应的通讯协议,该卡能直接用于采用计算机技术、对要求数据传输速率比较高的工业现场控制系统中.     

微机系统与接口技术实验系统的硬件设计

介绍基于STC12C5A32S2单片机为核心的实验系统研制与设计.运用扩展数据存储器技术、串行口通信技术、D/A转换、显示器与接口技术和时钟芯片接口技术的有效组合,实现串口联机程序下载.     

“绿色重合性能量突变体系”新概念的提出及理论研究

指出了用绿色能量场作为变量代入动力学系统数学模型中的输入变量、状态变量及输出变量后,问题的关键是启动可控制的输入能量变量场或激励信号是否能撬动绿色能量状态变量的突变而输出绿色能量变量,建立动态数学模型、取出能量应用。     

浅谈电脑式压力机吨位计的设计

1吨位计的工作原理及其调整压力机吨位计采用组合应变片来检测压力机工作时滑块的应力,测量压力机曲柄在不同转角时滑块所承受的负载,监视各种异常状态,从而可保证压力机的正常工作。该装置构成框图如图1所示。组合应变片为每边350Ω的四应变片式电桥,将四个应变片分别固定在压力机四个立柱的内侧。当压力机工作时,四个立柱由于受力而发生微小变形,组合应变片随之产生弹性变形,这时在电桥对角线上即有输出,然后将这个被检测出的输出信号转换成电信号。因该信号本身很微弱,故通过模拟放大器把它放大到容易处理的程度,放大后的信号经过A/D转…     

射频接收电路的改进及综合测试

射频接收机作为无线通讯系统的最前端,其结构和性能直接影响整个通信系统的通信质量。射频接收电路是把天线接收进来的带有调制的射频信号转变成基带信号,再把基带信号的幅度放大后输出给基带控制板。现有的射频接收电路存在模拟灵敏度和数字灵敏度较低、失真度较高、邻道选择性较低、双信号选择性较低、互调抗扰性指标较低、一致性较差等缺点。通过改进射频接收电路的压控振荡器电路和混频器电路,以提高系统的稳定性、噪声系数、增益、灵敏度等,使电路的本振、射频与中频间的隔离性和互调性更好。通过对改进后电路进行综合测试可以看出：模拟灵敏度提高了2～4 dB,数字灵敏度提高了2～4 dB,失真度整体明显降低,邻道选择性提高了10～13 dB,双信号选择性提高了7 dB,互调抗扰性指标提高了4 dB,远端极限通话距离提高了0.5 km,改进效果明显。     

一种用于公共场所水流终端的智能控制系统

介绍了一种用于公共场所水流终端的智能控制系统,系统中包括中央控制模块,此中央控制模块的信号输入端连接有传感模块,中央控制模块的信号输出端连接有指示装置和多个伺服电机,伺服电机通过传动机构分别与水流管路的总水阀及末端放水阀连接。能够减少公共场所水资源流失,并使供水管路终端得到更好的维护。     

赣中北毛竹表型特征的地理变异初探

调查研究江西省中北部6个毛竹林（Ⅲ度竹）的胸径、全株杆鲜重、全株枝叶鲜重、杆长、全杆节数、枝下节数、枝盘数、枝下高、叶长和叶宽、叶片长宽比、胸径处竹壁厚度、竹腔径、壁腔比、竹材含水率等表型特征。运用SAS8.1软件进行多元线性回归分析和偏相关分析,研究表明：全株杆鲜重、全株枝叶鲜重和胸径处竹壁厚呈现随经度变化的地理模式,其它表型特征随经度的变化不明显;所调查的表型特征均没有表现随纬度和海拔的变化而变化的地理变异模式。     

Chemical study and medical application of saponins as anti-cancer agents

Saponins are a group of naturally occurring plant glycosides, characterized by their strong foam-forming properties in aqueous solution. The presence of saponins has been reported in more than 100 families of plants out of which at least 150 kinds of natural saponins have been found to possess significant anti-cancer properties. There are more than 11 distinguished classes of saponins including dammaranes, tirucallanes, lupanes, hopanes, oleananes, taraxasteranes, ursanes, cycloartanes, lanostanes, cucurbitanes and steroids. Due to the great variability of their structures, saponins always display anti-tumorigenic effects through varieties of antitumor pathways. In addition, there are a large amount of saponins that still either remain to be trapped or studied in details by the medicinal chemists. This article reviews many such structures and their related chemistry along with the recent advances in understanding mechanism of action and structure–function relationships of saponins at the molecular and cellular levels. These aglycones have been described and their classification and distribution have been listed in the review. Some special saponins with strong antitumor effects have also been exhibited. Ginsenosides, belonging to dammaranes, have been found beneficial targeted on inhibition of tumor angiogenesis by suppressing its inducer in the endothelial cells of blood vessels, and then on prevention of adhering, invasion, and metastasis of tumor cells. Dioscin, one of the steroidal saponins, and its aglycone diosgenin also have been extensively studied on its antitumor effect by cell cycle arrest and apoptosis. Other important molecules discussed include oleanane saponins such as avicins, platycodons, saikosaponins, and soysaponins along with tubeimosides.     

一个世纪来黑龙江省森林景观动态研究

With the help of GIS tool of ARC/INFO,ARCVIEW and FRAGSTATS,the map of forest resource distribution of Heilongjiang Province was analyzed in 1896,1949 and 1981.Using total area,mean patch size,patch density,coefficient of patch size variation,mean patch fractal dimension and mean shape index,we studied the change of forest landscape pattem and the change of each patch types in this region.As a result,the total area of forest landscape and mean patch size decreased sharply,the quantity and density of patches increased,the juxtaposition of patches weakened,the shape of patch tended to become regular,and the border of patch simplified.All these showed that the forest landscape of this area tended to fragment gradually,and the fragment of Korean pine forest is the severest.the diversity of whole forest landscape and the eveness of landscape types distribution reduced gradually.Human impact,instead of climate change and forest community succession,is the most important reason for such dramatic chages.     

两种危害松类的新叶蜂(膜翅目, 广腰亚目, 松叶蜂科)

本文记述了中国松叶蜂昆虫两新种,马尾松吉松叶蜂和油松吉松叶蜂。文中附有形态特征图4幅。     

秃杉的物种确立、天然林种群特征、保护、引种和种源选择研究

根据秃杉有关的研究文献,对秃杉物种的确立,天然林的生物多样性、空间分布、动态和更新演替等种群特征,原生地保护与迁地保护,引种地气候和立地的适应性,速生性,抗寒、耐高温干旱、耐萌、抗风和抗病虫害能力等抗逆性,种源的遗传多样性,种源地理变异和生态适应性,种子、苗期及林木生长的变异,不同年龄林木生长性状的相关性,优良种源选择和种源区划等的研究进行了综合评述。     

论人本主义管理理念

组织最重要的资源是人,要实现组织目标就要有合理的管理,人本主义管理理念就是在管理过程中以人为本,以尊重人格,突出柔性管理,关心员工发展的双赢策略,确立员工的主人翁地位和注重员工培训为人本主义管理的思想内容。     

中国林业战略的现状及可持续发展战略

本文通过对中国林业的现状及存在的一系列生态、环境、经济和社会问题的分析讨论,重点强调了森林及整个林业在我国社会和经济发展中的重要作用。同时,作者提出可持续发展,特别是林业的可持续发展是解决我国当前生态环境和经济社会问题的关键和必由之路。并从生态学、经济学和社会学的角度,论证和阐述了林业可持续发展的目标、准则,以及我国林业的可持续发展战略。参11。     

Decomposition and nutrient release in needle litter from nitrogen‐fertilized scots pine (pinus sylvestris) stands

Decomposition of Scots pine needle litter originating from five stands treated with different amounts of nitrogen fertilizer was measured over a 4‐year period in a mature Scots pine forest. The litter types, which differed in initial concentrations of nitrogen, phosphorus, potassium, and sulfur, but not in gross organic composition, were studied with respect to mass loss, ingrowth of total fungal mycelium, and net release of nutrients. During the first year of decomposition, rates of mass loss and ingrowth of fungal mycelium were highest in the nutrient‐rich litter. Phosphorus concentration was found to be the main factor affecting mass‐loss rate, and the rate of fungal ingrowth was positively correlated with initial nitrogen concentration. After this initial period, decomposition rates decreased, and after 4 years, accumulated mass loss and amounts of fungal mycelium were similar in all five litter types. These findings may be due, in part, to a lower rate of lignin decomposition in nitrogen‐enriched litter. Of the elements, potassium and magnesium were most rapidly lost from the litter, and their release was most pronounced during the first year. Calcium release was proportional to the loss in organic matter. Initially, the release of nitrogen and phosphorus was positively related to their concentrations in litter, however, during later stages of decomposition the differences among litter types levelled out. There was a tendency for concentrations of all elements, except nitrogen, in the different litters to approach similar levels as decomposition proceeded. Thus, after 4 years the nutrient composition of the various litter types was very similar, except for higher nitrogen concentrations in the originally most nutrient‐rich litters. The importance of the results in terms of substrate quality in fertilized as well as in non‐fertilized forests is discussed.     

哈尔滨工程大学校园绿化改造方案

本文通过对哈尔滨工程大学绿化现状的分析,在规划中,提出了"一园、二区、三空间、四廊道、六组团"整体绿化景观,使设计更科学、布局更完整、结构更清晰。在新校区规划为体现学校从"发现—研究—收获"的这一发展历程。提出"新校区、新建筑、新景观"的思想,设计出简洁、现代、生态且充满创造精神的新景观。结合不同的区域特点分别提出了详细设计方案,展现出知识不断求索创新、积累升华的过程。     

竹业引领人类生活更美好

文章介绍了竹材在建筑、家具、交通、日用品等领域的应用现状,分析了竹材在性能、成本、资源量及环保等方面具有的多种优势,以及木材、塑料、钢材、陶瓷应用局限性和劣势,提出了竹木并举、以竹代塑、竹钢协同、竹瓷互补潜在的创新应用方向。在当前化石能源日益枯竭、环境压力越来越大的情况下,发展竹产业、应用竹产品是一项改变人类生活、促进绿色发展的重要举措,是健康生活、生态人居、绿色发展的正确方向。