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1.
m序列法测量室内脉冲响应已经被广泛接受,鉴于实际系统中的噪声和非线性会降低脉冲响应测量的精确性,对m序列法测量过程中室内系统微弱非线性所引起的失真进行了分析.叠加有微弱非线性的室内系统在时域可以等效为一个线性子系统和非线性无记忆环节的级联模型.根据该模型,推导了单一非线性作用下运用m序列法测量的室内脉冲响应误差,并且分析了该方法对各阶非线性的抑制能力.仿真实验验证了推论的正确性.  相似文献   

2.
NaI(Tl)探测器因具有探测效率高和成本低等优点,常被用于核辐射能谱测量和核辐射监管等领域.由于实验条件等的限制,研究人员往往较难获取理想的实验核信号,虽然可以借助探测器的仿真信号来实现研究目的,但是常规的探测器单指数或双指数模型和实际采集到的核信号模型存在一定的差异,需要一种更为精准的数学模型对探测器输出信号进行描述.我们通过对探测器信号形成过程分析,将探测器视为线性时不变系统,探测器各个部分响应的总卷积即为输出的核信号模型.本文建立的探测器输出信号卷积模型,结合实测伽玛源的幅度分布规律和相邻脉冲时间间隔分布规律,可以提供更精确的NaI(Tl)探测器输出信号,以便用于伽玛能谱测量算法研究;通过调节脉冲间隔时间大小,可以仿真不同计数下探测器输出信号的堆积情形,以便用于堆积信号还原算法研究.经过与伽玛辐射源的对比测试,该仿真信号与真实探测器输出信号一致,既避免了研究人员接触放射源,提高辐射防护安全性,又为开展数字化核信号处理算法研究及能谱算法研究提供了极大的便利性.  相似文献   

3.
研制了一种全自动1.064μm红外导引头的成像光斑测试仪,介绍了各部分功能实现的措施以及最小成像光斑和离焦光斑的图像处理方法,该测试仪以1.064μm导引头为被测对象,采用1.064μm的激光光源模拟无穷远点光源,以红外面阵CCD探测器为接收器,实时采集的信号通过RS-232串口通信进入计算机,采用重心法对所采集的光斑信号进行处理,分析光源通过被检测系统后在其焦面上和成像光斑的质量,它用数据和三维图形显示测量结果,可用于检测红外导引头最佳像面和离焦像面光斑的位置、大小及光能分布,并用于测试轴外视场的光斑,全部检测实现了“一键通”,该方法可以广泛应用于不同光学系统的检测,评价光学系统的质量,特别是光学聚焦系统的质量。  相似文献   

4.
现场大尺寸测量量值溯源   总被引:2,自引:0,他引:2  
为了评价大尺寸测量量值的准确性,需要建立大尺寸测量的量值溯源体系.针对研究的大尺寸配对视觉测量网的溯源难题,以激光跟踪仪作为高精度标准仪器,利用四元数空间配准算法将所有视觉传感器测量值统一到激光跟踪仪坐标系下,对其测量值现场原位溯源,并通过空间性能评价实验对激光跟踪仪溯源.实验表明,激光跟踪仪的不确定度为10μm+0.8μm/m,配对式视觉测量网的不确定度优于0.2mm.应用本文的方法可现场快速对多数大尺寸测量仪器溯源。研制的配对式视觉测量网络满足多数大尺寸测量任务.  相似文献   

5.
基于粒子滤波的仅有角测量的被动跟踪   总被引:1,自引:0,他引:1  
基于粒子滤波,提出了仅有角测量无源被动跟踪的新解决方法.该方法采用“当前”统计模型,使用粒子滤波算法,融合了双站测量数据.在双站测量的被动跟踪试验中,仿真结果证实了该方法能有效跟踪高度机动的目标.  相似文献   

6.
嫦娥一号绕月卫星对月球重力场模型的优化   总被引:2,自引:0,他引:2  
月球重力场是揭示月球内部结构和物质组成的重要信息,探测月球重力场仍然是绕月探测任务中的重要科学目标之一.在已有月球重力场模型基础上,利用嫦娥一号探测数据,并结合“月女神”一号探测器、月球勘察者(LP)及早期月球探测器轨道跟踪数据,本文解算得到了高精度月球重力场模型CEGM02(100阶次),在CEGM01月球重力场模型基础上对模型进行了优化.对新模型的分析结果表明,嫦娥一号卫星轨道跟踪数据的融入,使得对月球重力场长波长部分的解算精度有显著提高,相比于SGMl00h模型在5阶以内精度提高约2倍,在10阶以内有明显贡献,在20阶内都有贡献.初步判断这是由于嫦娥一号卫星轨道动量轮卸载的频度不足“月女神”的1/4,而同时轨道相对较高所导致.文中结合CEGM02和激光测月观测结果解算了月球平均转动惯量0.393446(±0.000006),对月球内部构造研究提供了更强的约束.  相似文献   

7.
基于距离和信息的单目标精确跟踪   总被引:5,自引:2,他引:5  
对仅有“距离和”测量信息的多传感器系统提出了一种对量测方程预处理的快速卡尔曼跟踪算法.该卡尔曼跟踪算法通过对量测方程预处理得到目标位置与“距离和”测量量成线性关系的观测方程;状态变量只选目标的空间坐标,而速度矢量仅作为确定性输入量加入状态方程,速度矢量通过引入速度“伪测量值”滤波得到.并同以前的跟踪算法仿真比较表明,该方法计算量小,收敛速度快,精度高,具有一定的实用价值.  相似文献   

8.
在空战中,需要基于空中移动平台对机动目标进行自适应跟踪.由于机动目标“当前”统计模型符合实际目标的动力特征,所以文中基于该模型,针对空基多平台多传感器环境,推导了机动目标跟踪的状态方程和测量方程,并给出了机动目标自适应跟踪算法.Monte—Carlo仿真表明,该方法能有效地估计出机动目标的运动状态.  相似文献   

9.
云层红外表观辐射模型的研究   总被引:4,自引:0,他引:4  
在前人对云层红外辐射与反射模型研究的基础上,建立了导引头实际接收的表观光谱辐射亮度(包含云层辐射和反射、天空背景与路径等效辐射)模型,适用于导引头远离云层以及处于云层中的情况.通过傅里叶光谱辐射计对几种远离云层的中、低云表观辐射亮度进行了实际测量,并与模型计算数据进行对比.结果表明:在3~5μm和8~12μm波段,模型计算与实际测量结果具有较好的一致性,可以用于导引头的模拟分析.  相似文献   

10.
研制了一套二维电阻热采物理模拟系统. 该系统包括五个组成部分:模型主体、注入系统、采出系统、抽真空系统和温度测量系统.其模型主体的体积为400 ×400 ×36m m . 在模型底部开有若干个温度测量孔,通过测量孔将测温热电偶放置在模拟油藏中. 电热油藏的物理模拟过程中的温度测量采用自行研制的温度场数据采集系统,实现了在线监测. 可利用该系统研究电场提高原油采收效率的方法及其影响因素,更适合于电热油藏的机理性研究.  相似文献   

11.
Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.  相似文献   

12.
何延凌 《科技信息》2008,(4):258-258
Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women's language from these perspectives: pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women's language, more attention should be paid to language use in social context. What's more, the linguistic phenomena in a speaking community can be understood more thoroughly.  相似文献   

13.
理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。  相似文献   

14.
The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3~4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰~ -7.8‰, PDB) and matrix dolomites (-6.6‰~ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084~0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078~0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.  相似文献   

15.
In the 19th century the society was controlled by men, and women were just appendants of them, they had not any rights and freedom. But Jane was an exception, she showed some characteristics of early feminist. Jane showed her characteristics of feminism in three aspects: rebellion, equality, and independence. These characteristics were helpful to her success, and feminism is the only way out for women of that time.  相似文献   

16.
As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.  相似文献   

17.
There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.  相似文献   

18.
王慧 《科技信息》2008,(10):240-240
Wuthering Heights, Emily Bronte's only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.  相似文献   

19.
The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.  相似文献   

20.
The non-orthogonal localized molecular orbital(NOLMO)is the most localized representation of electronic degrees of freedom.As such,NOLMOs are thus potentially the most efficient for linear scaling calculations of electronic structures for large systems.However,direct ab initio calculations with NOLMO have not been fully implemented and widely used,partly because of the slow convergence issue in the optimization of NOLMO.We devel-  相似文献   

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