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Search Results: 1 - 10 of 304781 matches for " 王卓然 "
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压力传感器动态校准不确定度评定
Uncertainty evaluation for the dynamic calibration of pressure transducer

李强,中宇,卓然
- , 2015, DOI: 10.13700/j.bh.1001-5965.2014.0356
Abstract: 摘要 压力传感器动态校准不确定度是表征其测量精度的重要指标.提出一种用于压力传感器动态校准不确定度评价的灰色方法.首先,使用正弦压力发生器产生标准的正弦压力信号驱动被校传感器,获取传感器特征输出;然后采用灰色关联分析处理传感器特征数据,得到权重数列;之后建立灰色模型并计算出各校准频率点的灰色偏度;最后采用加权最小二乘法去拟合以得到的工作频率范围内所有频率点的不确定数据,建立起被校压力传感器的动态校准不确定度模型.设置了幅值变化及不变两种情况下的实验验证方案,使用本文所提灰方法及黄方法分别对各方案下的数据进行处理;实验结果的对比表明:两种方案下所得动态校准不确定度曲线模型具有一致性;其中幅值变化情况下,两种方法在指定校准频率点所得校准不确定度的相对误差优于6%,在测试频率点相对误差也小于10%;幅值不变情况下,在大部分频率点处所得相对误差普遍小于5%,部分优于0.018%.实验分析证明,所提灰方法能很可靠地评估压力传感器动态校准不确定度.
Abstract: The uncertainty of dynamic calibration for pressure transducer is a key indicator of its dynamic measurement precision. A novel grey method (GM) was proposed to evaluate the dynamic calibration uncertainty of pressure transducer. Firstly, a sine pressure generator was used to produce required sine pressure signal to drive the calibrated pressure transducer and obtain output of transducer. Secondly, using the grey relational analysis to deal with the measurement sequences outputted, a weighted value sequence was obtained. Thirdly, a grey model was established to calculate the calibration uncertainty of appointed frequency. Finally, a weighted least-square fitting method was applied to do fitting with the calibration uncertainty of appointed frequency, and then a dynamic calibration uncertainty model was established. An experimental verification under the calibration condition of changing amplitude and unchanging amplitude was set up. Grey method and Huang method (HM) were used to process the output of pressure transducer separately. The results show that the curve models of dynamic calibration uncertainty are consistent with each other in the setting condition. What is more, under changing amplitude, the relative error of calibration uncertainty obtained by the two methods is superior to 6% at appointed frequency points and is also less-than 10% at testing frequency points. Under unchanging amplitude, the relative error is less than 5% at most of frequency points and is superior to 0.018% at some testing frequency points. Based on the above analysis, it can be approved that the grey method can evaluate the dynamic calibration uncertainty of pressure transducer reliably.
Maximizing empower of Spartina alterniflora community.
互花米草群落功率最大化倾向

金丽,卓然,钦佩
应用生态学报 , 2010,
Abstract: When a new plant species is introduced to a new district, its disturbance could alter the structure of original ecosystem, resulting in the formation of a distinctive self-organized ecosystem to develop the maximizing empower under the new situation. In this paper, an emergy analysis method was made on the two ecosystems Spartina alterniflora salt marsh and mudflat in North Jiangsu. Compared with the mudflat, S. alterniflora ecosystem had a 1.52E+18 sej higher annual total emergy output, 4.72 times of emergy density, and about 5 times of base emergy yield ratio. S. alterniflora ecosystem could use the energy more efficiently to increase its emergy storage and to realize it self’s empower maximizing. After invading into a tidal flat ecosystem, S. alterniflora via self organization could promote the ecosystem to achieve empower maximizing, and to full play its ecological services. However, too fast propagation and spread could induce a series of negative effects, such as inhibiting native plants, trenching on sea-route, and endangering the seashells breeding, etc.
互花米草群落功率最大化倾向
金丽,卓然,钦佩
应用生态学报 , 2010,
Abstract: 植物新种进入新区域后,通过扰动或搅局,改变生态系统的结构,形成有特色的自组织生态系统,趋向新条件下的功率最大化.本文应用能值分析的方法,分别对苏北互花米草生态系统和光滩生态系统进行能值分析和系统评估.结果表明:互花米草生态系统每年能值产出比光滩生态系统高1.52e+18sej.能值密度是光滩的4.72倍,基础能值产出率约为光滩生态系统的5倍.互花米草生态系统能更有效地利用能量,增加系统内部的能值贮存,实现系统内部的功率最大化.互花米草入侵某区域滩涂后,通过自组织促使整个互花米草生态系统趋于功率最大化,充分发挥生态服务功能,但由于其繁殖扩散过快,导致种群爆发,产生了一系列负面效应,如抑制本土物种、侵占航道、危害贝类养殖等.
认知诊断测验中的项目功能差异检测方法比较
卓然,郭磊,边玉芳
心理学报 , 2014,
Abstract: ?检测项目功能差异(dif)是认知诊断测验中很重要的问题。首先将逻辑斯蒂克回归法(lr)引入认知诊断测验dif检测,然后将lr法与mh法和wald检验法的dif检验效果进行比较。在比较中同时考察了匹配变量、dif种类、dif大小和受测者人数的影响。结果表明:(1)lr法在认知诊断测验dif检测中,检验力较高,一类错误率较低。(2)lr法在检测认知诊断测验的dif时,不受认知诊断方法的影响。(3)lr法可以有效区分一致性dif和非一致性dif,并有较高检验力和较低一类错误率。(4)采用知识状态作为匹配变量,能够得到较理想的检验力和一类错误率。(5)dif越大,受测者人数越多,统计检验力越高,但一类错误率不受影响。
用半导体环形激光器产生混沌信号
张鑫,袁国慧,卓然
强激光与粒子束 , 2012,
Abstract: ??提出了一种由一个分布式反馈激光器为主激光器和一个半导体环形激光器为从激光器组成的主从式激光混沌系统方案,主激光器产生的光单向注入到从激光器中,通过调整注入系数、主从激光器的失谐频率和从激光器的偏置电流,使从激光器工作在混沌状态,输出混沌信号。从基于光注入条件下的环形激光器的速率方程组入手,数值模拟了主从激光器的失谐频率、注入系数和从激光器的偏置电流3个工作参量对从激光器输出动态的影响。研究表明:外光注入条件下,半导体环形激光器可以产生混沌信号。通过分析得出:当失谐频率为3.9ghz、注入系数为0.07、偏置电流为81ma时,环形激光器可以产生功率谱平坦、带宽较宽的高质量混沌信号。
结合a分层的兼具项目曝光和广义测验重叠率控制的选题策略
郭磊,卓然,,边玉芳
心理学报 , 2014,
Abstract: ?测验安全和题库使用率在计算机化自适应测验中十分重要,特别是高风险测验。传统的shgt法兼具同时控制项目曝光率和广义测验重叠率的功能,但题库使用率较差。a分层法能够提高题库使用率,但对过度曝光的项目控制不足。本研究将a分层法的思想与shgt法相结合,各取所长,提出了3种新的选题方法:shgt_a法,shgt_b法和shgt_c法。研究结果表明:(1)与shgt法相比,新方法均可以在有效地控制项目曝光率和广义测验重叠率同时,极大地提高题库使用率;(2)随着预设项目曝光率(rmax)和广义测验重叠率()取值的增大以及共享人数a的减小,新方法对被试能力估计的精度呈上升趋势。比起shgt法,新方法仍能保持很高的题库使用率;(3)当区分度和难度的相关(rab)较大时,shgt_b和shgt_c法在能力估计精度方面优于shgt_a法;(4)在不同的测验考察内容比例下,3种新方法对被试能力估计的精度均较好;(5)与shgt法相比,新方法能够有效地控制项目曝光率过度控制的问题。
压力传感器激波管校准条件下的动态参数估计
Dynamic parameter estimation of pressure transducer in shock tube calibration test

李强,中宇,卓然,燕虎
- , 2015, DOI: 10.13700/j.bh.1001-5965.2014.0549
Abstract: 摘要 激波管是一种关键的压力传感器动态校准装置,但是由于其输出的不稳定性,使得被校准压力传感器的输出数据常常难以直接用于动态建模,且所建模型的准确性也难以表征.提出一种用于激波管校准压力传感器的动态参数估计方法.首先使用基于信息方法处理被校准压力传感器在阶跃激励下的输出数据,得到最优估计值序列、上界序列和下界序列;然后,对所得最优估计值序列、上界序列和下界序列分别进行白化滤波和差分建模,得到最优估计模型、上界模型和下界模型;之后对各个模型进行求解,最优估计模型得出被校准压力传感器的最优特征指标,上界模型和下界模型所得结果构成最优性能指标的估计区间.选用恩德福克200系列压阻传感器进行激波管校准实验,得出时域动态指标的相对误差小于8.17%,频域动态指标相对误差小于9.15%;所有指标均100%位于求得的估计区间内.
Abstract:Shock tube is the key device in the pressure transducer dynamic calibration. But as the output of pressure transducer often contains strong interference, which makes it difficult to directly use the output to build the dynamic model of calibrated pressure transducer, in addition, the accuracy of the model is hard to be characterized. A parameter estimation method was proposed which could be applied to pressure transducer in shock tube calibration test. Firstly, the operation of information generation was employed to process the output of calibrated pressure transducer under the pressure of step excitation, and then estimated sequences, upper boundary and lower boundary were obtained. Secondly, the processing methods about filtering and modeling were used to deal with the estimated sequences, upper and lower boundary, and then we could obtain the best estimated value model, the upper boundary model and the lower boundary model. Finally, by solving the obtained models, the indicators obtained by the best estimated model was the best characteristic indicator of the calibrated transducer, the indicators obtained by upper and lower boundary model could compose confidence interval of best indicators, it could show the reliability of the best indicators. A calibration test of shock tube is conducted with the piezoresistive pressure transducer of Endevco 200 series type. The relative errors of dynamic indices of time-domain are no more than 8.17%; the relative errors of dynamic indices of frequency-domain are no more than 9.15%. All the obtained indicators fall in the estimated interval with 100% probability of reliability.
电励磁双凸极无刷直流发电机非线性PI调压技术的研究
,曹小庆,卓然,严仰光
中国电机工程学报 , 2006,
Abstract: 针对12/8极电励磁式双凸极(EMDS)无刷直流发电机的非线性特性,提出了一种新的非线性PI调压控制方法,该算法中比例和积分参数随调压误差的变化而非线性变化。设计了以DSP为核心的数字调压器,利用实验离线辨识的方法建立发电机系统的数学模型,在此基础上设计了算法参数,与传统PI算法做了实验对比,结果表明其抗干扰能力比常规PI调节器强。为了进一步提高系统的动态性能,在非线性PI算法中加入了负载电流前馈补偿控制。实验结果表明,在系统突加和突卸负载两种情况下,采用具有负载电流前馈补偿的非线性PI控制后,发电机电压不仅恢复时间明显缩短,而且电压波动幅值也大大减小,系统的动态性能得到了明显的提高,而且具有高的稳态精度。
ZrB2-SiC钎焊接头界面产物及反应层生长规律
卓然,徐晓龙,征征
材料工程 , 2013, DOI: 10.3969/j.issn.1001-4381.2013.12.008
Abstract: 采用TiZrNiCu非晶活性钎料进行ZrB2-SiC复合陶瓷的真空钎焊连接,通过电子扫描显微镜、能谱分析仪及X射线衍射分析仪,分析钎焊过程接头界面反应产物,阐述产物形成机理。利用扩散理论,结合Ti元素在固溶体层的扩散行为,对界面中复合材料侧形成的Zr(s,s)固溶体层进行动力学分析,得到了描述Zr(s,s)固溶体层生长行为的动力学方程。
ZrB2高温陶瓷钎焊接头的界面组织和性能
卓然,征征,吴广东,朱晓智
材料工程 , 2010,
Abstract: 采用Ti-Zr-Ni-Cu钎料对ZrB2-SiC陶瓷的真空钎焊工艺进行研究。借助SEM,EDS和XRD等分析测试手段,分析了接头的界面组织结构及性能。实验结果表明接头界面产物主要有TiC,ZrC,Ti5Si3,Zr2Si,Zr(s,s),(Ti,Zr)(Ni,Cu)等。随着钎焊温度和钎焊保温时间的增加,钎焊接头中的Zr(s,s)层厚度不断增加,焊缝两侧灰色相Ti5Si3+Zr2Si的体积和数量逐渐增加并向焊缝中部生长伸展,焊缝接头中的黑色相TiC+ZrC的体积和数量明显增加,其分布贯穿整个焊缝。当钎焊温度为920℃,钎焊时间为10min时,钎焊接头的抗剪切强度最高,达到143.5MPa。
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