数字滤波算法在甲醛快速监测仪中的应用

在甲醛快速监测仪中,信号的采集与处理是一个相当关键的环节.为了取得正确的检测数据和测量结果,必须采取简单而有效的方法,消除被测信号中的噪音和干扰.本文着重介绍单片机系统中几种实用的数字滤波算法,并讲解甲醛快速监测仪中所采用的数字滤波算法.     

超短波中继台工作制式与通信链路的构成

在森林防火、灭火移动超短波无线电通信中,为克服高山对通信的影响,可建立超短波中继通信系统,利用高山中继台转发信号,实现延伸与迂回链路通信。本文主要是介绍有源超短波中继台工作制式与通信链路构成。一、中继台的组成及工作方法超短波中继台分有源中继台和无源中继台。具有放大中继信号能力的为有源中继台;没有放大中继信号能力的则为无源中继台。它们都具有转发信号的作用。有源中继台是由转信电台、天线、供电源等组成(见图1)。当A电台用f_1发信时,无线电台I     

DBSCAN聚类的频谱感知算法研究

为了提高认知无线电系统的检测概率,提出了一种两轮判决的感知算法,结合1 bit和2 bit能量检测技术,并在感知过程中进行了删减策略的优化,降低了系统的反馈开销。针对系统的安全问题,将上述的感知算法与DBSCAN聚类算法相结合,根据次用户本地感知结果和融合中心最终判决结果之间的差异来识别恶意用户。同时推导了系统的主要性能指标并进行性能仿真。仿真结果表明：两轮判决感知算法的系统检测概率较常用的能量检测算法有了显著提高,在结合DBSCAN后可以有效地识别恶意用户,干扰冲突概率明显降低,系统感知可靠性大大提高。     

一种改进的无线传感器网络的通信调度机制研究

在基于IEEE 802.15.4协议的网络中使用能量有效性通信调度(EETS)机制,可以得到良好的超帧参数配置,但是由于EETS机制优先采用长帧传输数据,在低带宽要求的无线传感器网络中性能不太理想.考虑采用长帧和短帧传输数据两种情况,提出了一种改进的能量有效性通信调度(E-EETS)机制,仿真结果表明E-EETS机制提...     

新技术用铁块无线传输信号和能量

英国科学家研发出一种技术,可以通过铁块来无线传输能量,研究人员表示,该技术可以应用于潜艇上,让潜艇的外部舱体无线传输能量和通信信号,还可应用于核工业和石油工业领域。研发这项技术的英国航空航天系统公司(BAE     

基于锁相环的有源电力滤波器谐波电流检测技术研究

设计了一种有源电力滤波器电流检测装置,装置采用锁相环电路获取电网电压基波频率及相位,通过传感器检测电网三相电压、电流,经信号痢理电路送至微处理器如DSPA／D端口,采集来的电压、电流信号以及电网电压基波频率,通过FBD算法获取谐波电流信号。利用理论公式推导,通过MATLAB的FBD算法仿真及搭建有源电力滤波器电流检测系统所获得的实验结果证明了理论的正确性和方法的可行性。     

基于熵的语音端点检测方法探讨

语音端点检测是语音通信中的一个重要环节。在实际应用中,通常要求首先对系统的输入信号进行判断,准确的找出语音信号的起始点和终止点。这样才能采集到真正的语音数据,减少数据量和运算量,并减少处理时间。因此语音端点检测算法研究意义重大。本文主要探讨基于熵的语音端点检测方法。     

基于熵和波形特征的木材损伤断裂过程声发射信号处理

为了通过声发射信号(AE)对木材内部损伤状态进行评估,本研究选择能够表征信号复杂程度(熵值)以及波形变化(脉冲因子、裕度因子、峰值因子、波形因子)的特征,并通过对木材试样三点加压弯曲实验采集原始声发射信号.另外,为了抑制干扰,提高信号特征对损伤状态的敏感性,提出了一种采用EMD分解方法,基于信号能量、瞬时频率、峭度值的...     

超短波通信上、下行信号不均等分析与对策

超短波通信上、下行信号不均等分析与对策葛云鹏（吉林省森林警察总队）在森林防火通信中．由于受高山障碍影响．每每产生上、下行信号不均等致使某一方电台出现能收到对方信号．而该台发出的信号对方收不到（此时电台发射功率正常）的现象。尤其扑救森林山火采用移动通信...     

瓦斯浓度红外检测噪声消除方法研究

将数学方法与实验方法相结合,通过测量信号和参考信号的比值,消除由于光源的不稳定及其他因素引起的检测误差、外界环境引起的误差等,并利用数学方法推导得到计算方程。实验结果验证此类方法的可行性,可有效消除井下复杂恶劣环境带来的一系列噪声干扰,包括检测系统固有的性能误差和外部环境引起的干扰误差。     

SOME PROBLEMS ON FOREST SAMPLING TECHNIQUES

INTRoDUCTIoNForestinventorymaybedefmedastheteeboqu9ofcollecting,evaluatinandpresent-ingspecifiedinformationonforestareas.AstherearemanydtherentsamPlingmethods,achoicemustfirstbemadeastowhichmethodsultsthegivenfieldShoplerandomsamPlingisthebasisofothermethdsandthesamPlingproQedureissimplynamedSRS.WeoftenhavetodealwithPOpulatonthatcanbesplituPintovarioussub-populationthatinsomeresPectofotheraremutUallydifferent,eachsub-populaton(calledstrAn)initSelfthenismorehomoge-nousthanthepopulatio…     

The use of compensatory and non-compensatory multi-criteria analysis for small-scale forestry

Small-scale farm forestry has the potential to offer many benefits both to landholders and the wider community. As with all changes in land-use practices, there are associated benefits and costs and these are not uniformly distributed. They have varying impacts on the different values, aspirations, goals and objectives that exist within the community. Furthermore, the community does not consider these values, aspirations, goals and objectives of equal importance. The degree of concern can vary from minor to high and overriding all other considerations. When evaluating farm forestry options it is necessary to address all of these concerns. This paper examines the combined use compensatory and non-compensatory multi-criteria analyses to evaluate forestry options, in a case study for the Darling Downs region of Queensland, Australia. These aggregation techniques are found to be highly complementary and together provide a comprehensive analysis. The compensatory technique provides a sound measure of overall performance of a forestry system, whereas the non-compensatory technique alerts decision-makers to presence of particularly poor performance with respect to individual criteria. The compensatory technique used is simple and understandable even for those with non-mathematical backgrounds. This analysis can identify and aid communication of the relative benefits and costs, and trade-offs, between economic, environmental and social considerations.     

同分等概记分方法及其在核桃选优中的应用

在研究考察事物过程中,有时需要对个体从不同方面考察分析许多指标,以判定某总体中个体间的优劣。同分等概方法是把所有的考察指标都同分等概地分数化,以总分     

Surface tension phenomena in the xylem sap of three diffuse porous temperate tree species

In plant physiology models involving bubble nucleation, expansion or elimination, it is typically assumed that the surface tension of xylem sap is equal to that of pure water, though this has never been tested. In this study we collected xylem sap from branches of the tree species Populus tremuloides, Betula papyrifera and Sorbus aucuparia over 3 months. We measured the instantaneous surface tension and followed changes over a period of 0.5-5 h using the pendant drop technique. In all three species the instantaneous surface tension was equal to or within a few percent of that of pure water. Further, in B. papyrifera and S. aucuparia the change over time following drop establishment, although significant, was very small. In P. tremuloides, however, there was a steep decline in surface tension over time that leveled off towards values 21-27% lower than that of pure water. This indicated the presence of surfactants. The values were lower for thinner distal branch segments than for proximal ones closer to the trunk. In some species it appears valid to assume that the surface tension of xylem sap is equal to that of water. However, in branch segments of P. tremuloides close to the terminal bud and hence potentially in other species as well, it may be necessary to take into account the presence of surfactants that reduce the surface tension over time.     

匈牙利的林业经营与管理经验初探

从建立森林资源管理体系、编制森林经理计划、制定促进林业发展的方针政策3个方面,论述了匈牙利在林业建设中积累的值得借鉴的经验,在分析匈牙利具有较高的森林资源管理水平时,又着重介绍了这个国家设置的在行政上是独立的、在法律上有地位的、在行使职权时有权威的森林资源监督机构。这个机构实际上是代表国家监督、调整、管理、保护全国的森林资源。     

社会林业发展与林权制度安排

从人的价值及行为形成机制出发,分析认为影响林业发展的核心因素是产权安排,目前我国林权制度存在所有权主体虚置、林地产权的各项权能边界不清、林地权属四至界限不清等问题.发展社会林业,必须界定出明晰的林业权能边界,强化林地使用权,保障四大权能.     

Purposes and challenges of public participation in regional and local forestry in Finland

Public participation in regional and local forest planning in Finland was researched. The questions were: (1) What is the purpose of public participation? (2) What are the challenges of public participation? The results are based on the analysis of discourse communities in a case study concerning a Regional Forest Programme and forest management planning. It was shown that the purpose of participation was to promote communication at the regional level and to gather information at the local level. The general conclusion is, that the regional forest programmes include practices to offer possibilities for communication among participants. This does not mean, that all the programme processes have reached consensus automatically. The case studied here reached compromise. The case study points out problems faced, if public participation would become common practice at the local level on non-industrial private forests lands. In forest management planning it would result in an excessively demanding mediator/expert role for the planner. The need to consider all relevant issues, e.g. biodiversity management, would also become apparent. The study supports the idea that public participation as communication has better possibilities to promote sustainable forest management than public participation as information gathering.     

关于国内外美丽乡村建设研究的进展与启示

近年来,随着全国各地陆续出台美丽乡村建设的相关政策以及制定专门的发展规划,对于美丽乡村建设的研究规模也逐年扩大,有关美丽乡村建设文献研究的来源也正体现出多学科关注的特点。其研究方法多以定性分析法、实地调查法为主,还有少量的实证分析;研究内容方面,国外美丽乡村的建设主要以东亚、欧美两个地区最具代表性,国内的美丽乡村建设研究主要包括美丽乡村的基础理论研究、建设水平的评价研究、规划设计研究、政策制度研究及传播推广研究。黑龙江省在美丽乡村建设方面无论是理论研究还是实践探索都还处于初期阶段,迫切需要在理论探索、问题归纳、出路探索等多方面持续展开一系列深入研究。所以在今后的研究过程中应注重多种研究方法相结合、深化理论研究、强化理论和实践的关系、吸收先进经验,以补己之短。     

Permutation procedures as a statistical tool in wood related applications

Summary Two variations of a class of permutation tests termed Multi-Response Permutation Procedures (MRPP1 and MRPP2) and the classical two-sample, two-sided t test were used to evaluate 72 data sets from tests on wood joints made with elastomeric construction adhesives. In all cases, the probability levels obtained from MRPP2 and the two-sample t test were nearly identical. This result stems from the fact that the test statistics of these two tests are theoretically equal. However, the underlying distributions of these two statistics are different. In several of the 72 comparisons, conflicting inferences about population differences were reached using MRPP1 and MRPP2. The results indicated that when the two data sets closely approximated a normal distribution and equal variances occurred, the MRPP2 (the permutation version of the t test) was the more optimal test. When validly-obtained extreme points were present, then the assumption of normality was not reasonable and MRPP1 was superior.The authors wish to express their thanks to the Colorado State Agricultural Experiment Station for their financial support of this study     

Wanderverhalten von Nonnenraupen unter dem Einflß von Metalleffekten

Investigations were made on migration-behaviour of caterpillars ofLymantria monacha influenced by pure metals, whose effects together with those of electric-magnetical powers are normally effective inside of zones of earth radiatons in fields. It was ascertained, that attraction of food, lying in different distances from the metals varied between normal zones and zones of earth-radiations. Inside of zones of earth-radiations the larvae were found very numerous (90–100%) on twigs next the metal, but inside of normal zones 40% and more migrated to food in maximal distance of the metal. From these results it can be assumed, that metals inside of normal-zones very likely restrict the caterpillars, but inside of zones of earth-radiations they seem to atract them. In the first case probably additional metal effects serve for diminishing of too strong electric-magnetical powers. The migration behaviour inside of normal zones influenced by metals would be in coincidence with preceding trials with nun-caterpillars inside of metal-zones, where the larvae showed a very high mortality. Diseased larvae were assembled nearly 100% by food in minimal distance of the metals.